Final Report Summary - ACTICOSPACK (Reducing the levels of preservatives in cosmetic products through active packaging technologies)
Executive Summary:
ACTICOSPACK project focused at the development of active packaging solutions for three target cosmetic products. Each cosmetic product required different packages to be developed:
Active polyethylene (PE) bottle for sun lotion
Active polypropylene (PP) pot for facial cream
Active polyethylene terephthalate (PET) bottle for shampoo
ACTICOSPACK project started in December 2012 and ended in November 2014. Different activities dealing with research and technology developments as well other activities related with dissemination, exploitation of results and management were carried out along these two years of project.
ACTICOSPACK involved the participation of seven partners from different European countries (Spain, Italy, Portugal and Germany), who perfectly complemented the project to perform all the required activities with excellence. The consortium had the participation of 5 SMEs (2 cosmetic and 3 packaging companies) and 2 research centres specialized in microbial/toxicological safety and packaging technologies. The results of the project were supported by the interest of an international retailer representing more than 550 hypermarkets and 750 supermarkets in around 12 European countries.
The project provided valuable results in the area of cosmetic preservatives by studying antimicrobial and toxicological issues applied to the development of specific cosmetic formulations with reduced contents of preservatives. The application of typical cosmetic preservatives in packaging development was an innovative aspect of the project that was especially researched with positive results. The generation of knowledge on the performance of the new packaging solutions was crucial to achieve the final ACTICOSPACK goals.
Along the project, several technological barriers were encountered in the way of developing the new active packages. In this sense, the high level of expertise provided by both SMEs and Reseach Centres allowed solving each barrier successfully thus achieving all the different milestones of the project within the expected project lifetime.
The project generated at the end, 15 technical deliverables released at confidential level, 7 dissemination materials developed for the general public and other documents related with the protection and exploitation of the results by the consortium.
Project Context and Objectives:
Cosmetics play an essential role in our daily lives. They are important consumer products with an essential role in everyone's life: apart from "traditional" cosmetic products, such as make-up and perfumes, it also includes products for personal hygiene.
Over 450 million Europeans use a variety of cosmetic products on a regular basis; soap, shampoo, conditioner, deodorant, toothpaste, shaving cream, aftershave, cleanser, perfume, make-up and a host of other products.
Nowadays is impossible to imagine a world without personal care products. Cosmetics help people to feel better, to gain in self-esteem and confidence, especially in difficult time; for instance, the “Look Good Feel Better” campaign showed how the cosmetics industry helps to support women with cancer helping them to combat the visible effects of cancer treatments. Cosmetics also play a key role in human health; for instance, soap protects from many bacteria and other microorganisms, toothpaste keep healthy teeth and gums that prevent some diseases and sunscreens help in protecting skin from the ultra-violet rays that can severely damage it.
Several factors affect the quality and safety and hence the shelf life of the cosmetic products such as the oxygen, the light, the humidity or the growth of microorganisms, among others. In this sense, microbial contamination of cosmetic products is a matter of great importance to the cosmetic industry. Some examples of microorganisms commonly isolated from poorly preserved water-based products include Klebsiella, Enterobacter, Staphylococcus and Bacillus species, Pseudomonas, including P. aeruginosa, Burkholderiacepacia, Penicillium and Candida albicans. Gram-negatives are most common and, as they have very diverse metabolic capabilities, can survive in a wide range of environments and are often introduced through water supplies.
Regulation 1223/2009 on cosmetic products includes the microbiological quality as a mandatory parameter to be included in the safety report of the cosmetic product. The Cosmetics, Toiletry & Perfumery Association UK recommends a total viable count of aerobic bacteria, yeast and moulds of less than 100 c.f.u. per gram for eye and baby products, and 1,000 c.f.u. per gram for other products at completion of manufacture. Harmful microorganisms should not be detectable using standard plate count (SPC) techniques and P. aeruginosa, Staphylococcus aureus and C. Albicans are used as indicator organisms.
Chemical preservatives are active ingredients added to the cosmetics products able to prevent the growth of spoiling and pathogenic bacteria and fungi (yeast and moulds). Preservatives are used nowadays in a high number of cosmetic products. Of all of them, the most used are the para-hydroxy-benzoates or parabens which are currently under revision in Europe. In this sense, some of them will be restricted and forbidden in the cosmetic legislation in the near future due to safety issues. In addition, the consumer demands to the cosmetic market is moving towards the use of more natural and preservative-free cosmetics.
On the other hand, the usual practice in cosmetic formulation is to overdose the products with preservatives in order to provide the adequate quality and safety margin along its entire shelf-life. However, the minimum concentration of preservatives required to inhibit the growth of microorganisms (known as MIC, “minimum inhibitory concentration”) is normally quite lower than the contents added to the cosmetics. The reason to overdose the cosmetics is to guarantee that the content of preservatives is maintained above the MIC along the cosmetic shelf-life considering that preservatives are degraded and consumed along time. If the cosmetic was not overdosed, the content of preservatives would go below the MIC before the required commercial shelf-life of the cosmetic and therefore its quality and safety would not be guaranteed.
The ACTICOSPACK project seeks for a technological solution able to reduce the content of preservatives in the cosmetic products while maintaining the quality and safety for the same or even longer shelf life. In concrete, the technological solution proposed in ACTICOSPACK goes through the development of a packaging solution with active properties. This means that the package will be able to interact with the cosmetic product, therefore bringing the package from a simple inert container to an active package.
In this sense, the cosmetic preservatives are included into the package instead of into the cosmetics, thus acting as a reservoir of preservatives. Later on, the active package releases the preservatives into the cosmetic products due to the mass transfer (migration) properties given by many polymeric materials like those used in packaging. The release of the preservatives from the package continues until an equilibrium between the content of the preservative into the packaging material and the cosmetic product is reached.
In the situation of using an active package, the preservative concentration lost by consumption or degradation is recuperated because of the content released from the active package. In this way, two benefits are obtained; the first one is that a lower content of preservative is needed in the cosmetic product (ideally equal to the MIC value) and the second one is that the preservative effect is maintained for a longer time until the preservative in the packaging material is totally consumed. Therefore, this technology allows making preservatives more effective, even in the event of being in the cosmetic product in a lower content than currently used.
The main objective of ACTICOSPACK was the development of active packaging solutions for three target cosmetic products and packages. In concrete, an active PE bottle for sun lotion, an active PP pot for facial cream and an active PET bottle for shampoo.
Other main objectives of ACTICOSPACK contributing to the main goal were:
- Selection of the most promising preservative systems to be included into the packaging materials based first on the antimicrobial effectiveness, but also on thermal and chemical stability and toxicological safety.
- Development of the adequate processes to incorporate the selected cosmetic preservative systems into packaging materials. It should be considered that not all the preservatives used in cosmetics are suitable to be incorporated into packaging materials. In this sense, the most promising preservatives need to fulfil with additional requirements such as thermal stability at temperatures around 200ºC, compatibility with the packaging materials and show adequate diffusion properties.
- Optimization of the packaging material composition and characteristics to provide the best preservation performance. This objective involves the complete characterization of the release of the preservatives from the different packaging materials into the target cosmetic products, and, the application of computer mathematical simulation studies.
- Pilot and industrial scaling-up of the active packaging materials developed to obtain final 3D active packaging prototypes. The achievement of this objective checked the viability of the available industrial processes to produce the new packages and implementation measures.
- Validation of the active packaging prototypes based on two key issues;
i) demonstrating the performance of the new prototypes in the industrial filling and packing lines of the cosmetic manufacturer/packer
ii) demonstrating the ability of the new active packages to preserve the microbial quality criteria of the cosmetic products
Project Results:
ACTICOSPACK was divided into three main phases:
- Phase 1 aimed to develop the new scientific knowledge needed to understand the behaviour of the cosmetic preservatives in the different systems (cosmetic products and packaging materials).
- Phase 2 dealt with the transformation of the scientific and technological knowledge generated in phase 1 into technologically advanced products (active packages releasing antimicrobial preservatives).
- Phase 3 dealt with the validation or demonstration of the performance of the new active packages with especial emphasis on demonstrating the industrial application and the added value that the new solutions will bring to the cosmetic products.
ACTICOSPACK generated results on each of these phases that demonstrated the suitability of the active packaging technology in reducing the levels of preservatives in cosmetic while maintaining its quality and safety along shelf-life.
Main results obtained in Phase 1
The first main result obtained was related with the selection of an initial set of preservative systems (PS) considered suitable to be used as cosmetic preservatives systems for each target cosmetic product (sun lotion, facial care cream and shampoo) and to be included into packaging materials for active package development.
Eight preservative systems were proposed. All of them are based on the mixture of several substances which provide synergies towards the antimicrobial activity. Some of these preservative systems are based on chemicals already used in cosmetic while others are quite innovative in its application as cosmetic preservatives and are derived from natural sources.
The performance of the preservative systems was evaluated towards antimicrobial effectiveness by means of in vitro and in situ tests. In addition, other complementary characterizations were performed dealing with the evaluation of the thermal and chemical stability as well as with the toxicological safety.
Antimicrobial efficacy of the 8 preservative systems was performed by means of microdilution susceptibility assays against different target microorganisms including bacteria such as Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus, and fungi such as Candida albicans and Aspergillus brasiliensis. In these tests, it was evaluated if the chosen preservative systems are antimicrobial effective in general. The tests were performed with the preservative systems alone (no cosmetic matrix) using microdilution susceptibility testing (“MIC-Test”). The MIC test evaluates the minimum concentration necessary to inhibit microbial growth. In this pretest, both native samples and samples after thermal treatment of the respective preservative system were investigated to evaluate potential loss of efficacy upon increased temperatures which are necessary for the incorporation process of the preservatives into the packaging.
The testing for antimicrobial efficacy of preservative systems and cosmetic product/preservative systems were performed according to 1) DIN EN ISO 11930:2012 „Evaluation of the antimicrobial protection of a cosmetic product”, 2) the European Pharmacopeia, Section 5.1.3 „Efficacy of antimicrobial preservation“ for cosmetic product challenge tests and 3) CLSI guidelines M07-A8 for antibacterial and M38-A2 and M27-A3 for antifungal susceptibility testing by microdilution assays.
The results obtained showed:
i) All preservative systems showed antimicrobial efficacy against Staphylococcus aureus. System 1 was only effective in medium concentrations, while system 2-8 were efficient at lower concentrations. Thermal treatment did not influence antimicrobial efficacy of any of the systems tested.
ii) All preservative systems showed antimicrobial efficacy against Escherichia coli. Preservative system 1, 4 and 5 were only effective in medium concentrations. Systems 2, 3 and 6-8 were efficient at low concentrations. Thermal treatment did not influence antimicrobial efficacy of any of the preservative systems.
iii) Results with Pseudomonas aeruginosa showed that this microorganism had the highest resistance vs. antimicrobial treatment with the preservative systems. Preservative System 1 was not efficient in the chosen concentration range. Preservative systems 4, 5, 6 and 7 were only effective at the highest concentrations. Systems 2, 3 and 8 were highly efficient at low concentration. Thermal treatment did not alter efficacy of systems 2-8, however, system 1 showed antimicrobial efficacy only after thermal treatment.
iv) All preservative systems showed antifungal efficacy against Candida albicans and Aspergillus brasiliensis (spores) in an acceptable concentration range.
Based on the results of the microdilution assays the most promising preservative systems were chosen to be measured in the cosmetic product challenge test:
- sun care: preservative system 2
- facial cream: preservative system 5
- shampoo: preservative system 8
Upon proven antimicrobial efficacy in the pretest, the performance of the preservative systems in the respective cosmetic products (sun care, facial cream and shampoo) was evaluated in challenge test (in situ tests).
To this end, different batches of cosmetic products containing around 6 - 7 different concentrations of each preservative system (including samples with no preservatives) were manufactured by the cosmetic partners. The performance of the preservative systems within the cosmetic product was tested using a challenge test adapted from the guidelines ISO11930 and European Pharmacopeia. This test consists in inoculating the different cosmetic products with a known volume of germ suspension. Then, the inoculated samples of the cosmetic products were incubated in the dark at room temperature for up to 28 days. On day 1, 7, 14 and 28 samples were drawn and the viable germ load was assessed via dilution plating on agar plates. The antimicrobial efficacy of the preservative systems was determined by assessment of the reduction of the viable germ number in the product versus the samples with no preservatives.
The challenge tests were performed starting with the most promising preservative systems according to the results of the microdilution susceptibility tests. In concrete, the antimicrobial efficacy of 5 systems was evaluated according to the acceptance criteria of ISO11930. The main results obtained showed:
i) Sun care + Preservative system 2
The presented data of the challenge tests using sun care lotion indicate that preservative system 2 is highly efficient in protecting the cosmetic product sun lotion against bacterial and fungal growth according to ISO11930 guideline acceptance criteria.
ii) Facial cream + Preservative system 5
The obtained data indicate that only high concentrations of preservative system 5 provide efficient protection of the facial cream cosmetic product versus all tested bacterial contaminations.
iii) Facial cream + Preservative system 5 + Preservative system 2
For all test germs it can be concluded that mostly there is no survival over time in facial cream with only PS5, but an outgrowth of Aspergillus can occur. Thus, the addition of PS2 increases efficacy and safety of the product.
iv) Shampoo + Preservative system 8
The chosen preservative system 8 provides efficient protection from growth of microorganisms that are able to survive in the shampoo matrix (E. coli, P.aeruginosa).
v) Shampoo + Preservative system 5 + Preservative system 2
For all test germs the survival in shampoo per se is very limited with viable germs only present until day 1 to 7. Thus, according to ISO11930 acceptance criteria no further protection by preservative system might be needed. However, the use of PS5+2 for some germs shows clear reduction of the bacterial load on day 1 indicating an increased safety with addition of PS5+2.
In addition to this antimicrobial evaluation, thermal & chemical stability and toxicological studies were performed as part of the evaluation of the suitability of the candidate PS to incorporated in active packaging materials.
The objective of the thermal stability study is to evaluate the suitability of the preservative systems to overcome the thermal stresses produced during the manufacturing of the active packaging materials. The preferred technique to incorporate the preservative systems into the packaging materials are based on working with the polymers in molten state at temperatures over the 180ºC.
The thermal stability of the preservative systems were carried out by means of two set of experiments. One based on Thermogravimetric Analyses (TGA) in which the PS were heated at a constant heating rate, and another one based on subjecting the PS to a constant temperature for a given period of time in a closed environment to reduce volatilities and measure real losses due to thermal degradation.
Prior to study the thermal stability of the preservative systems, it was necessary to develop the adequate analytical methodologies to determine the content of the main chemicals taking part of each preservative system. In this sense, methods based on gas and liquid chromatography techniques were set up.
As main results of the thermal stability analysis, almost all the chemical constituents in PS1 (natural extract) showed some extent of degradation. In this sense, the most important finding was the significant degradation of the terpinenes with a parallel increase of cymene. In this sense, some scientific publications have already reported that terpinenes are transformed by oxidation into cymene which could be favoured by the thermal treatments. Similarly to PS1, the terpinenes that were present in the PS6, 7 and 8 coming from the natural extracts that were added to these preservative systems were thermally degraded and transformed into cymene. Other natural substances were also moderately degraded after the thermal treatment. PS3, 4 and 5 showed also some degradation of some of the components (mainly those related with the natural extracts). Finally, PS2 was the most stable preservative system with no thermal degradation of the two chemical components of this PS.
The objective of the chemical stability study was to evaluate in what extent the preservative systems that were added to the cosmetics are consumed along time. The components of the preservative system could interact with some of the components of the cosmetic product reducing the available amount able to exert antimicrobial activity. Moreover, preservatives are usually consumed when exerting their action against microorganisms. As a consequence, the study of the evolution of the concentration of the preservative system in the cosmetic product is needed in order to set up their shelf-life.
The chemical stability study was based on the guidelines described by ICH (International Conference for Harmonization), Colipa (European cosmetic, toiletry and perfumery association), and Anvisa (Brazilian Health Agency). Samples of the three cosmetic products were exposed to three different storage conditions. Samples were taken at specific periods of time to analyse the content of the chemicals in the cosmetics by means of the ad-hoc developed analytical methodologies. In concrete, the chemical stability was measured up to 90 days.
The results obtained showed that some of the PS had a good chemical stability in the different cosmetic products while some degradations were observed for other active agents. For instance, the main component of PS3 showed a clear degradation and conversion into some degradation substance along time which was favoured by increasing the temperature.
Finally, the toxicological assessment of the selected PS was performed by carrying out several tests. In this sense, the toxicity assessment of the preservative systems were carried out in two phases. During the first one, cytotoxicity on Human HaCaT keratinocytes and AMES tests (method that uses bacteria to test whether a given chemical can cause mutations in the DNA of the test organism) were carried out with the whole set of preservative systems. Then, the final selected preservative systems were further evaluated in a second phase in terms of chromosome aberrations and cell gene mutations. The results coming from the first tests were used to screen the safety of all the preservative systems while the tests carried out in the second phase were performed to complete the safety dossier of the final selected systems.
The main results obtained in the first evaluation of the PS showed a good correlation between the different cytotoxicity tests performed with the Human HaCaT keratinocytes. Results allowed determining the lowest observed adverse effect levels (LOAELs) of each system. On the other hand, in the AMES test the preservative systems neither induced a two-fold or greater increase in the mean number of revertant colonies as compared to the negative controls nor a dose related increase. Therefore, the preservative systems tested did not induce a mutagenic effect (induction of gene mutation).
On the other hand, further complementary toxicity tests were carried out with the final selected preservative systems (i.e. PS2 and PS5):
i) In Vitro Mammalian Cell Gene Mutation Test (OECD Guideline 476) which measures the mutagenic potential of the PS based on quantification of forward mutations at the thymidine kinase locus of mouse lymphoma L5178Y/TK+/- cells, and,
ii) In Vitro Mammalian Chromosome Aberration Test (OECD Guideline 473) which measures if the PS has the potential to cause breakage of chromosomes (clastogenic) in cultured mammalian somatic cells.
The main conclusions arising from these two tests showed that neither PS2 nor PS5 showed evidences to be mutagenic in mammalian cells and to produce mammalian chromosome aberrations.
So far, all the results obtained were related with the study of the suitability of the PS to impart antimicrobial activity, to withstand thermal processes and to be safe. In Phase 1 of ACTICOSPACK it was also evaluated the feasibility of introducing the 8 preservative systems into different packaging materials by means of the conventional processes applied to produce the final target packages:
PE bottle for sun lotion, PP pot for facial cream and PET bottle for shampoo.
The first task in this part was to identify the requirements that the new active packaging materials should fulfil for each of the three target cosmetic products (facial cream, sun cream and shampoo). These requirements were mainly related with the cosmetic products themselves but also with the packaging processing technologies to be applied:
i) Extrusion blown moulding (EBM) for the PE bottles. It consists in a continuous or intermittent melt flow (called parison) coming from an extruder that goes to a mould to form the package. This technique represents the 65% of the market.
ii) Injection moulding for PP pots. Injection moulding is a processing technique for polymers that produces parts by pushing molten polymers into a mould by the action of a high pressure using a screw or piston. The mould cavity cools the polymers hardening them to the shape of the cavity. The most commonly thermoplastic polymers can be injected by this process although high flow index materials are the best choice, particularly for thin wall parts.
iii) Injection stretch blown moulding (ISBM) for PET bottles. ISBM processes are based on two processes and machines; injection moulding (IM) to produce the preforms and stretch blown moulding (SBM) to blow the preform into a hollow package. It is quite usual to find machines that integrate both processes (integrate two stations of the same machine). This is the most used technique to process rigid packaging based on PET.
Packaging requirements such as gas barrier properties or transparency are of key importance in the preservation and commercialization of the target cosmetic products. On the other hand, the development of packaging materials by extrusion processes may introduce thermal and mechanical stresses that need to be carefully evaluated in order to design the best approach to incorporate the active substances into the packaging materials.
Based on the initial 8 PS chosen at the beginning of the project, at least three PS were chosen to be studied for each packaging case. In the initial stages of the active packaging developments, the incorporation of the PS in the selected polymeric resins (PE, PP and PET) was carried out using a lab scaled twin screw extruder and injection module. The incorporation of the preservatives in each polymeric matrix was attempted at different contents. Considering the number of polymeric resins, the preservative systems, contents, replicates and repetitions for confirming results, more than 150 different extrusion batches or trials were carried out along these trials.
For each batch, the processing parameters (temperatures, screw speed, residence time, etc.) of the extruder and injection module were set in function of the technical data sheets provided by the polymer suppliers and in function of the observed behaviour of the blend polymer-preservative system. Some response parameters were recorded during the processing of the materials such as the torque of the screw versus time in order to analyse the effect on the processing of each preservative system and its concentration.
The main results obtained were for each case:
i) The preservative systems PS1, PS2 and PS3 were incorporated to three polymers used in EBM: PP, HDPE and LDPE. The inclusion of PS1 and PS2 into the PP and the HDPE could be carried out even at the highest preservative content. However, PS3 showed some incompatibility with the PP and the HDPE especially at high contents because of the inconsistence of the curves. In the case of the inclusion into LDPE, the 3 PS behave similarly. The viscosity variation during process is not significant at 2% compared with the processing of neat LDPE. At higher contents the materials become more fluid due to the plasticisation effect of the preservative systems.
ii) The preservative systems PS1, PS2, PS4 and PS5 were incorporated to PP for injection moulding. In this case, the response curves showed that all three systems behave well thus indicating a good incorporation into the polymer even at the highest content.
iii) The preservative systems PS6, PS7 and PS8 were incorporated to the PET. PET is a polyester polymer with a highly hygroscopic material that requires a previous drying before processing to reduce moisture. During the processing of this material, the mixing chamber was purged with nitrogen in order to ensure that polymer melt is free of oxygen and moisture taken from ambient.
First trials with the three preservative systems provoked a viscosity drop of more than 70%. This means that polymer was significantly damaged and PET becomes useless. Some other trials were carried out decreasing the content of the preservative systems. Even in these cases, comparing the torque curves of PET/PS compounds with the reference PET, the viscosity drops in more than 50% - 75%. That means that polymer properties cannot be ensured because of the significant molecular weight loss.
In order to check if these results were consequence only because of the preservative system or due to an interaction with the PET, the PS6, 7 and 8 were processed with PP. The curves obtained in this case showed that these PS behave similarly to PS1 with no big differences in comparison with the curve of the neat PP.
On the other hand, some additional tests trying to incorporate PS1 to PS5 into PET were also carried out. The results obtained showed that all the PS provoked a great impact on the processability of PET. These results confirmed that PET seemed to be no-good polymer for incorporating additives such as the cosmetic preservative systems as consequence of the results obtained.
At this stage, the ACTICOSPACK consortium decided to explore alternative approaches for the case of the active packaging development based on PET materials. These approaches considered the impossibility of introducing the PS directly into the PET matrix and therefore they considered the application of multilayer structures based on coating technologies. Two main approaches were researched. The first one involved the application of sprayable coatings and the second one involved the use of polymers applied as hot-melt coatings onto the PET bottles.
Regarding spray coating, several polymeric resins were tested. Some of them were commercialized in ready-to-use sprayable solutions dispersed in water or solvent and others were prepared in situ in laboratory. The preservative system was incorporated to the resin dispersions in several contents.
Then, these solutions were sprayed onto PET materials using an airspray system using a gravity handheld gun attached to a compressed air pipeline. Different parameters were optimized such as air pressure, fluid flow, number of strokes and time, temperature, etc. In this sense, almost all the systems could be sprayed. The materials were characterized in terms of grammage, thickness and adhesion of the sprayed coating layer to the PET based on the standard ISO 2409:2013 “Cross-cut test”. In addition, the content of preservative incorporated to each material was determined by means of thermogravimetry analyses (TGA) and by chemical solvent extraction and subsequent chromatographic analyses.
Based on the results obtained, it was concluded that the spray coatings were adequate in terms of sprayability, adhesion to PET substrate and incorporation of PS, although the process required further optimization.
However, after carrying out some ageing tests in which shampoo was put in contact with coated PET, it was observed that the anchorage of the polymer was not strong enough to resist the chemical attack of the shampoo components. Therefore, a new battery of trials were carried out in order to improve the adhesion between the coating layer containing the active agents of PS and the PET materials.
The new trials involved the application of PET surface treatments, the use of primers and other coating polymer resins. In this sense, the results obtained with the new resin showed a good sprayability of the solutions containing PS, a good transparency and an adequate adherence to the PET materials even after contact with the shampoo. In fact, spray coating trials were carried out at pilot scale level in Phase 2. However, the active packaging system obtained was not suitable to satisfy the demanded antimicrobial requirements of the shampoo.
In this sense, a new approach was researched based on the application of hot-melt resins as coating layers to the PET. To this end, the resins were mixed with the preservative system PS by means of a melting extruder and the molten compound was directly added to the PET materials like in a lamination process. The results obtained after characterizing this system showed an adequate adhesion after contact with shampoo for at least 2 months and a significant content of PS incorporated. Therefore, this system was finally selected to be scaled-up in Phase 2 of the project as part of the active package development for PET bottles.
In addition to the evaluation of the processability of the materials by means of extrusion/injection and spray/hot-melt coating processes, the content of PS surviving to each case and the homogeneity of the different materials developed was evaluated to confirm that a real active package was obtained.
To this end, the content of the PS and the main active chemicals that were incorporated in the different packaging materials was analysed by means of thermogravimetric (TGA) and chemical analyses which were developed ad-hoc for each specific case. The adequate analytical methodology was developed by setting up a first step based on the extraction of the preservative systems with different type of solvents and the subsequent quantification carried out by means of gas and liquid chromatographic techniques. The development of these analytical methodologies are crucial as future assays to be considered in the quality control of the new active packages produced at industrial level.
The PS quantification results obtained showed a clear correlation between the content determined by TGA and chemical analysis and the amount of PS added to the packaging materials during the processing trials. The percentage of PS incorporated (that is an estimation of the yield of the process) showed values ranged between the 50% and 100%. In terms of comparative results, the materials based on the incorporation of PS2 gave the best values with rates of incorporation higher than 85%, independently of the polymeric matrix. Finally, the quantification results obtained when analysing the active materials based on PET clearly showed the chemical reaction between PET and most of the PS since no PS could be detected in any case.
Considering the results obtained in the characterization of the PS and the active packaging development results it was concluded that the most promising final active packaging/cosmetic systems would be based on the following combinations:
i) Active PE bottle incorporating PS2 for sun lotion products
ii) Active PP pot incorporating PS2 for facial cream products already containing PS5 in the cosmetic formulation
iii) Active PET bottle based on coating layer containing PS2 for shampoo already containing PS5 in the cosmetic formulation
Next activities focused on studying the release of the PS from each packaging material aiming at describing the mode of action of the materials which involves three steps:
i) Diffusion of the preservatives through the polymeric matrix
ii) Dissolution or mass transfer of the preservative at the interface packaging-product
iii) Diffusion or dispersion of the preservative through the cosmetic matrix.
The migration or release of the PS from the packages continues until an equilibrium between the content in packaging and the cosmetic is reached. Three parameters are of key importance when characterizing the release from active packages to cosmetics; the diffusion rate in the package (D pack), the diffusion rate in the cosmetic (D cosm) and the ratio between the concentration in the package and in the cosmetic product at equilibrium (K). Several mass-transfer tests were carried out to determine these kinetic and equilibrium parameters under controlled environmental conditions in order to accurately assess the performance and effectiveness of the active packaging materials developed into the project:
i) The diffusion coefficients through the different cosmetic matrices were estimated for PS2. The results obtained showed that the diffusion coefficients were dependent on the type of cosmetic matrix. For instance, diffusion in the shampoo was faster than in facial cream, while diffusion in sun lotion showed the lowest values.
ii) The diffusion within the packaging materials was studied considering an experimental design in a way that mathematical modelling of the migration kinetics could be performed. The results obtained showed that the PS was able to be released from the different polymeric matrices. Although the kinetics associated to each case was different; coated PET showed the faster kinetics, followed by PE and PP matrices. On the other hand, it was observed that the higher the temperature, the faster the release of PS.
iii) Finally, the equilibrium coefficients (K) which offers a measure of the ratio between the content of active agent in the packaging material to the content in the cosmetic were also evaluated by placing in contact de packaging materials containing the preservatives and the cosmetic products. The K values obtained reflect the differences between the different systems. The K values decrease as the temperature increases what means that the release of the active agents is favoured at higher temperatures. On the other hand, the K values for the system based on PE/sun lotion showed lower values than the PP/facial cream. For the case of the system based on EVA disk for PET and the shampoo, the release of the active agents was almost complete.
In the framework of ACTICOSPACK, the effectiveness of the active package is strongly related to the balance between the controlled release of the cosmetic preservatives and the microbial growth kinetics. In this sense, microbial inhibition cannot be achieved if the release rate of the active preservatives from the package is not sufficient to reach the minimum inhibition concentration (MIC) of the target microorganism or cannot be sustained throughout cosmetic shelf-life because it is too fast. Therefore, the optimal active packaging properties have to be obtained.
In this sense, the estimated diffusion from the package (D pack) and the equilibrium constant (K) are the key parameters in this case: The first parameter should be equal to the consumption/degradation rate of the PS in the cosmetic matrix and the second one should have a value that allows getting a preservative content in the cosmetic product close to the MIC value.
Once obtained these parameters, they were used to optimize the active package characteristics by means of mathematical simulations carried out with specific calculation software. The goal of the mathematical simulations performed was to find the most adequate active package for the preservation of the target cosmetics considering the specific systems of ACTICOSPACK.
To this end, different scenarios were simulated considering different degradation/consumption rate of PS in the cosmetic matrices along its shelf-life. In this sense, it was stablished as goal to recover up to a 30% of the amount of active agents lost by degradation/consumption along the cosmetic shelf-life with the active packages.
In a first optimization step of each of the packaging solutions for the specific cosmetic products, it was determined that the best packages would have a large thickness that makes industrially not feasible to produce them. Therefore, a refinement of the active package characteristics was considered. In this sense, the content of each individual chemical agent taking part of PS2 was optimized for each case of package/cosmetic.
After this optimization carried out by mathematical simulation, a comparison between the expected performance of the new active packages versus the use of overdosed cosmetics packed into conventional packages with non-active properties was performed for each package/cosmetic case. In this sense, the main results obtained showed that the values that are achieved are ranged between the 7.5% of shelf-life extension for the case of the coated PET bottle for shampoo containing 3% less of preservatives, the 25% for the case of the PE bottle for sun lotion containing 5% less of preservatives and the 90% for the case of the PP pot for facial cream containing 9% less of preservatives.
Therefore, the use of the active packages developed into the project increases the preservation of the target cosmetics what is a valuable new tool for its commercialization.
Main results obtained in Phase 2
Once determined the active packages to be developed for each cosmetic case, Phase 2 aimed at scaling-up the developments to pilot and industrial levels to obtain some kind of 3D package prototypes: PE bottle, PP pot and PET bottle with an active coating.
Several trials were carried out by the packaging industrial partners along the project in order to fix the processing windows, to produce samples for further tests in other WPs and to study a complete battery of packaging characteristics.
The main goal of these trials was to set-up the processing windows (that is the parameters controlling the manufacturing process) of the pilot/industrial lines to the new materials. Therefore, an assessment of the industrial processability of the materials and the identification of possible additional processing activities raised during trials in the industrial environment were obtained.
Results showed that in all the cases, a previous compounding process was needed. Compounding is a process of mixing or blending polymers with additives in molten state. There are many processes called formally, “melt compounding” although the most used technique in plastics industry is to use intermeshing twin-screw extruders as compounding equipment.
Due the huge number of compounding processes, there are many possibilities to configure the process in terms of equipment definition, feeding systems and feeding sequence. The selection of a specific machine configuration for a given blend or mixture depends on the nature of components to be blended and the physical parameters like viscosity, volatility and chemical moieties. The configuration of the screw of the compounding extruder is of key importance in order to effectively blend PS with the corresponding polymers for each package. Several temperature profiles were tried in order to optimise the compounding conditions. In this sense, the objective was to process at as much low temperature as possible to reduce the possible thermal degradation of the active components. On the other hand, other parameters like production and screw speed were also optimised in order to maintain a reasonable level of energy.
All the compounds (i.e. blends of PS2 and polymers) were characterized in terms of PS2 content to evaluate the yield of the compounding process and the melt flow index (MFI). The results obtained showed the incorporation of PS2 to the compounds were above 90%. This yield was significantly higher than the values observed in the laboratory trials due to the higher efficiency of the pilot scale feeders and because of the lower residence time into the extruder. On the other hand, it was observed that the addition of PS2 changed the rheological behaviour of the polymers. The MFI increased with the increase of the content of PS2. This increase showed a linear tendency and the MFI was twice the neat polymer for the compounds with the highest content of PS2. For the case of PE, the melt strength (which is important in EBM process) could be affected, but the best way to evaluate the impact of the variation of this parameter is to process using a real geometry of the parison and bottle (stretch ratio). It was supposed that the introduction of some small variation on the processing temperature of the extrusion blown moulding will compensate the viscosity drop. The evaluation of the quality of the package, particularly the thickness profile, will be critical to evaluate if the parison has enough melt strength. In the case of PP, the injection moulding process will probably not be limited by such MFI variation.
After generating the active compounds, they were used to manufacture the different target active packages:
i) The industrial equipment used for the production of the PE bottles consisted in an extrusion blow moulding machine, a mould and other auxiliaries such as the raw material feeding system and the leak tester. The EBM plant was composed by an extruder, an extrusion die that forms three parisons, a cutting device, and a clamping system. The mould has 6 cavities and it was divided into two parts of three cavities each, that work alternatively during the cycle time. This allows the overlapping of other operations, thus improving the production capacity. Five different combinations of materials were processed at the industrial trials.
The materials could be processed without major problems. The only required modification was the decrease of the die temperatures. This modification was in technical agreement with the increase of the MFI measured on the blends. It was also noticed that the scrap parts were cut with more difficulty for the compound with the highest PS2 content although just a minor regulation of the cutting parts was required.
All the new package prototypes collected for quality control tests resulted in conformity with the production specifications. No difference in the quality attributes can be identified between the standard components and the parts manufactured with the new active compounds.
ii) The industrial equipment used for the production of the PP pots consisted in an injection moulding machine. The mould has 6 cavities injected at once. Four different combinations of materials were processed at the industrial trials.
The processing conditions needed to be slightly changed when injecting the PP based compounds containing PS2. These changes were mainly related to the increase of the MFI of the compounds and because of the appearance of some visual defects (mainly flashes and halos) of the package prototypes which were corrected by changing the injection speed, the second injection pressure and the back pressure.
There were not significant troubles in the injection moulding of all the PP/PS2 compounds. In fact, all the compounds had a similar rheological behaviour so that there was no need to change the processing parameters when the different compounds were processed.
iii) Finally, the application of the active coatings onto PET bottles was successfully carried out using a pilot scale extruder. All the processes needed to developed the active bottles were carried out in one single step: Compounding of coating polymer with PS2 and the application of the molten polymeric compound to the PET bottle. The implementation of this solution at industrial level can be easily performed by introducing a ram extruder or mass molten injection system.
In conclusion, the different tests carried out indicated that the new active compounds were successfully processed at industrial and pilot scale levels.
After the production of the new active package prototypes they were characterized in terms of mechanical, chemical, barrier to gases and thermal properties to evaluate the possible impact of the addition of the PS into the polymeric matrix on all of them. In this sense, some target requirements imposed by each specific cosmetic product selected into the project (sun lotion, facial cream and shampoo) to their corresponding packages (PE bottle, PP pot and PET bottle, respectively) were previously identified in Phase 1.
The main results obtained showed that the active packages tend to have poorer properties than the conventional ones, although considering the packaging requirements identified for the target cosmetics, in none of the cases the modified packaging properties restricted the use within the current conditions to commercialize them.
In concrete, for the case of the PET bottles for shampoo, the inclusion of the active coating on the PET bottle does not alter the inherent barrier, mechanical and thermal properties of the conventional package. The main difference between the active package and the conventional one is in terms of weight since the coating increased it.
For the case of the PE based bottles for sun lotion, the inclusion of PS2 into the PE polymeric material just modifies the oxygen permeability and mechanical properties of the materials versus the conventional PE bottles. In this sense, the modification of the barrier properties to oxygen is not critical since the wall thickness of the bottle is still high enough to consider the material as good barrier package. On the other hand, the modification of the mechanical properties, especially the vertical compression resistance, does not have any impact on the current transport and distribution practices; more than 100 package units could be stuck above the new packages which is by far higher than the current practices.
Similarly to the case of the PE bottles, the main properties affected for the PP active pots (oxygen barrier and mechanical resistance) do not have any practical effect when considering the target cosmetic and the current transport and distribution practices. The oxygen barrier properties and mechanical resistance are lower than the values given by the conventional packages but the values are completely suitable for the target cosmetic requirements. The thickness of the active PP pot confers very good barrier properties while the inclusion of the active PP pot inside other external PP pot avoids the exposure of the active PP pot to mechanical stresses. Anyway, the active PP pot alone will be able to withstand more than 700 package units above it.
Therefore, although some properties of the packages have been modified as consequence of the inclusion of the active preservative system, this does not alter the normal practices in using these cosmetic packages.
Main results obtained in Phase 3
The final phase of the project started once the active prototypes were industrially developed. In this phase, the new packages were used to carry out filling and packing trials at the industrial facilities of the cosmetic producer and to study the evolution of the quality of the cosmetics along time.
In these filling and packing trials, two series of packages were carried out inside cleanrooms with a controlled environment preventing contaminations; one using the conventional or habitual package (i.e. non-active) and another one using the active packages. After the trial, the main conclusion was that no specific modifications in the normal packaging process applied by the cosmetic manufacturer needed to be considered when using the new active packages.
The three different cosmetics packed into the active and non-active packages were studied along time to determine the microbial, chemical and sensorial quality. In this sense, a real storage test should be carried out. However, these tests were un-practical to be performed within the schedule of the project since they usually take at least from 6 months up to 1 year. Therefore, it was decided to carry out an ad-hoc test aiming to find differences between active and non-active packages in the microbial quality of the cosmetics within 1-1.5 months of test duration.
To this end, the initial content of preservatives directly incorporated into the cosmetic products were in most of the cases below the MIC in order to bring the microbial preservation of the cosmetics below the limit at the initial time. Subsequently, the idea was to bring the cosmetic preservation above this MIC value because of the release of the preservative agents from the packages.
The performance of the active packaging regarding antimicrobial activity was tested in situ in the cosmetic products packed in the active versus the control conventional packaging. In parallel, the release of the active agents was followed along storage days both in the cosmetic products and in the packages. Finally, the cosmetics were evaluated in terms of sensorial attributes by means of the study of the colour, aspect, consistency of the cosmetic matrix, separation of phases and odours by the technical staff of the cosmetic producer.
The results obtained showed that the active packages were able to release the preservatives and no sensorial differences were found. In addition, several trends towards an increased antimicrobial performance of the active packages versus non-active ones were observed for sun lotion and shampoo. Unfortunately, facial cream was contaminated with external microorganisms and the antimicrobial tests could not be performed.
The results obtained in these tests provided valuable information to be considered in the simulation models to further optimize the new active packages considering real shelf-life conditions.
Potential Impact:
The expected final result in ACTICOSPACK project was to reduce the content of preservatives used in cosmetics while keeping its quality and safety along the same or even longer shelf-life. The proposed technological solution to achieve this goal was to develop tailor-made active packages for three specific cosmetic products. In concrete, ACTICOSPACK involved the following systems:
1. Active bottle based on PET for shampoo
2. Active bottle based on PE for sun lotion
3. Active pot based on PP for facial care cream
Different results were obtained along the project lifetime that were approaching the project to its final goal. A continuous evaluation of the advancement was monitored by checking the results versus the key milestones. They included the identification of preservative systems joining an adequate antimicrobial effectiveness for each cosmetic product in addition to an adequate thermal stability to be processed at high temperature when incorporated into the packaging materials. Other key milestones included the verification of the implementation of results at industrial level to obtain real 3D packages and the evidence of an adequate performance of the active packaging systems.
As final conclusion of ACTICOSPACK, results demonstrated that the reduction of preservatives in the cosmetics is possible while keeping an adequate preservation. In fact, the current level of the preservative system worked into the project used in cosmetics are around 0.9% while the eventual combination of natural preservatives and the active packages makes possible its reduction to levels of 0.5% or even lower thus meaning reductions around 50%.
The activities carried out within the project provided an overall approach to packaging development valuable for all companies. Besides foreground knowledge achieved, companies have evaluated patentability of the new products and will proceed according to this patentability evaluation. In addition, further steps towards industrialization of results and market introduction are being evaluated by project members in an active way.
Based on the potential benefits carried out by ACTICOSPACK results, wider implications are envisaged at politics, society, economy and even at environmental level:
Political – Safety and human health protection is a key topic at European level. European Scientific Committees has recently recommended restricting the limits of some preservatives such as propyl- and butylparaben, and more restrictions are envisaged. The new packages will contribute in replacing paraben derivatives in the cosmetic formulation thus alleviating in some way the uncertainty whether the actual allowed maximum content confers the adequate margin of safety.
Societal – Consumers demand less synthetic preservatives and more green or natural cosmetic products. Both demands are fulfilled with the new packages; parabens can be replaced or reduced but also the green or natural preservatives. At relative large contents, the natural origin of the preservative is not a guarantee of safety and can also impart sensory alterations in the cosmetic products.
Commercial – The possibility of enhancing the cosmetic stability and thus extending the shelf life of the cosmetic products with the new solution brings the opportunity to the European cosmetic SMEs of expanding their business beyond local and national frontiers. This will place Europe at the forefront of the packaging technology and make stronger the exporting position of Europe in the global market.
Environmental – The cosmetic sector is also aware to the sustainability. In this sense, the possibility of extending the shelf life of the cosmetic products with the new solution will reduce the cosmetic wastes but more importantly will reduce the packaging wastes (the personal care packaging involves several thousand million packaging units). In addition, larger shelf life also favours larger size packages that also reduce packaging wastes.
Economic – The European trend of reducing the levels of preservatives in the formulations are forcing to invest money and resources in new formulations and new preservative systems. Substitution of a new ingredient typically requires the manufacturer to conduct a full-scale reformulation effort including safety, stability, and consumer acceptance tests. In this sense, the new active package brings a technological solution to the cosmetic sector to adapt to new content restrictions and consumer’s demands based on the same formulation but with less preservatives.
Finally, several materials for disseminating the project, the main results obtained and the European funds provided by the Research for SMEs project programme were developed. In concrete, information of the project was disseminated through different channels along the project lifetime and some of them can still be found via internet:
• Specific project website at http://www.acticospack.eu
• Brochure
• Press releases available in printed and electronic portals
• Specific video on the project (available at http://www.acticospack.eu)
• Video news at national TV channels
• Specific poster of the project
List of Websites:
http://www.acticospack.eu
Relevant contact details:
Coordinator
ESPANOLA DE NUEVOS TRATAMIENTOS SA
Spain
CALLE JORDI DE SANT JORDI S N
ALCOY, Spain
Administrative contact: Luis Torró
Tel.: +34902 820 750
Participants
INDUPLAST SPA
Italy
VIA EUROPA 34
BOLGARE, Italy
Administrative contact: Rossana Cortesi
Tel.: +390358354103
GEPACK – EMPRESA TRANSFORMADORA DE PLASTICOS SA
Portugal
RUA 1 DE AVRIL EDIFICIO GEPACK
AVEIRAS DE CIMA, Portugal
Administrative contact: Ana Domingos
Tel.: +351 263 470 210
LAMEPLAST SPA
Italy
VIA G. VERGA 1-27
NOVI DI MOENA, Italy
Administrative contact: Enrico Salvarani
Tel.: +39059673873
Fax: +39059671688
INSTITUTO TECNOLOGICO DEL EMBALAJE, TRANSPORTE Y LOGISTICA
Spain
Calle Albert Einstein. Parque Tecnológico. 1
Paterna, Spain
Administrative contact: Jose Bermudez
Tel.: +34 961820114
Fax: +34 961820001
FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG E.V
Germany
Hansastrasse 27C
MUENCHEN, Germany
Administrative contact: Meike Muller
Tel.: +49 89 1205 2723
Fax: +49 89 1205 7534
ACTICOSPACK project focused at the development of active packaging solutions for three target cosmetic products. Each cosmetic product required different packages to be developed:
Active polyethylene (PE) bottle for sun lotion
Active polypropylene (PP) pot for facial cream
Active polyethylene terephthalate (PET) bottle for shampoo
ACTICOSPACK project started in December 2012 and ended in November 2014. Different activities dealing with research and technology developments as well other activities related with dissemination, exploitation of results and management were carried out along these two years of project.
ACTICOSPACK involved the participation of seven partners from different European countries (Spain, Italy, Portugal and Germany), who perfectly complemented the project to perform all the required activities with excellence. The consortium had the participation of 5 SMEs (2 cosmetic and 3 packaging companies) and 2 research centres specialized in microbial/toxicological safety and packaging technologies. The results of the project were supported by the interest of an international retailer representing more than 550 hypermarkets and 750 supermarkets in around 12 European countries.
The project provided valuable results in the area of cosmetic preservatives by studying antimicrobial and toxicological issues applied to the development of specific cosmetic formulations with reduced contents of preservatives. The application of typical cosmetic preservatives in packaging development was an innovative aspect of the project that was especially researched with positive results. The generation of knowledge on the performance of the new packaging solutions was crucial to achieve the final ACTICOSPACK goals.
Along the project, several technological barriers were encountered in the way of developing the new active packages. In this sense, the high level of expertise provided by both SMEs and Reseach Centres allowed solving each barrier successfully thus achieving all the different milestones of the project within the expected project lifetime.
The project generated at the end, 15 technical deliverables released at confidential level, 7 dissemination materials developed for the general public and other documents related with the protection and exploitation of the results by the consortium.
Project Context and Objectives:
Cosmetics play an essential role in our daily lives. They are important consumer products with an essential role in everyone's life: apart from "traditional" cosmetic products, such as make-up and perfumes, it also includes products for personal hygiene.
Over 450 million Europeans use a variety of cosmetic products on a regular basis; soap, shampoo, conditioner, deodorant, toothpaste, shaving cream, aftershave, cleanser, perfume, make-up and a host of other products.
Nowadays is impossible to imagine a world without personal care products. Cosmetics help people to feel better, to gain in self-esteem and confidence, especially in difficult time; for instance, the “Look Good Feel Better” campaign showed how the cosmetics industry helps to support women with cancer helping them to combat the visible effects of cancer treatments. Cosmetics also play a key role in human health; for instance, soap protects from many bacteria and other microorganisms, toothpaste keep healthy teeth and gums that prevent some diseases and sunscreens help in protecting skin from the ultra-violet rays that can severely damage it.
Several factors affect the quality and safety and hence the shelf life of the cosmetic products such as the oxygen, the light, the humidity or the growth of microorganisms, among others. In this sense, microbial contamination of cosmetic products is a matter of great importance to the cosmetic industry. Some examples of microorganisms commonly isolated from poorly preserved water-based products include Klebsiella, Enterobacter, Staphylococcus and Bacillus species, Pseudomonas, including P. aeruginosa, Burkholderiacepacia, Penicillium and Candida albicans. Gram-negatives are most common and, as they have very diverse metabolic capabilities, can survive in a wide range of environments and are often introduced through water supplies.
Regulation 1223/2009 on cosmetic products includes the microbiological quality as a mandatory parameter to be included in the safety report of the cosmetic product. The Cosmetics, Toiletry & Perfumery Association UK recommends a total viable count of aerobic bacteria, yeast and moulds of less than 100 c.f.u. per gram for eye and baby products, and 1,000 c.f.u. per gram for other products at completion of manufacture. Harmful microorganisms should not be detectable using standard plate count (SPC) techniques and P. aeruginosa, Staphylococcus aureus and C. Albicans are used as indicator organisms.
Chemical preservatives are active ingredients added to the cosmetics products able to prevent the growth of spoiling and pathogenic bacteria and fungi (yeast and moulds). Preservatives are used nowadays in a high number of cosmetic products. Of all of them, the most used are the para-hydroxy-benzoates or parabens which are currently under revision in Europe. In this sense, some of them will be restricted and forbidden in the cosmetic legislation in the near future due to safety issues. In addition, the consumer demands to the cosmetic market is moving towards the use of more natural and preservative-free cosmetics.
On the other hand, the usual practice in cosmetic formulation is to overdose the products with preservatives in order to provide the adequate quality and safety margin along its entire shelf-life. However, the minimum concentration of preservatives required to inhibit the growth of microorganisms (known as MIC, “minimum inhibitory concentration”) is normally quite lower than the contents added to the cosmetics. The reason to overdose the cosmetics is to guarantee that the content of preservatives is maintained above the MIC along the cosmetic shelf-life considering that preservatives are degraded and consumed along time. If the cosmetic was not overdosed, the content of preservatives would go below the MIC before the required commercial shelf-life of the cosmetic and therefore its quality and safety would not be guaranteed.
The ACTICOSPACK project seeks for a technological solution able to reduce the content of preservatives in the cosmetic products while maintaining the quality and safety for the same or even longer shelf life. In concrete, the technological solution proposed in ACTICOSPACK goes through the development of a packaging solution with active properties. This means that the package will be able to interact with the cosmetic product, therefore bringing the package from a simple inert container to an active package.
In this sense, the cosmetic preservatives are included into the package instead of into the cosmetics, thus acting as a reservoir of preservatives. Later on, the active package releases the preservatives into the cosmetic products due to the mass transfer (migration) properties given by many polymeric materials like those used in packaging. The release of the preservatives from the package continues until an equilibrium between the content of the preservative into the packaging material and the cosmetic product is reached.
In the situation of using an active package, the preservative concentration lost by consumption or degradation is recuperated because of the content released from the active package. In this way, two benefits are obtained; the first one is that a lower content of preservative is needed in the cosmetic product (ideally equal to the MIC value) and the second one is that the preservative effect is maintained for a longer time until the preservative in the packaging material is totally consumed. Therefore, this technology allows making preservatives more effective, even in the event of being in the cosmetic product in a lower content than currently used.
The main objective of ACTICOSPACK was the development of active packaging solutions for three target cosmetic products and packages. In concrete, an active PE bottle for sun lotion, an active PP pot for facial cream and an active PET bottle for shampoo.
Other main objectives of ACTICOSPACK contributing to the main goal were:
- Selection of the most promising preservative systems to be included into the packaging materials based first on the antimicrobial effectiveness, but also on thermal and chemical stability and toxicological safety.
- Development of the adequate processes to incorporate the selected cosmetic preservative systems into packaging materials. It should be considered that not all the preservatives used in cosmetics are suitable to be incorporated into packaging materials. In this sense, the most promising preservatives need to fulfil with additional requirements such as thermal stability at temperatures around 200ºC, compatibility with the packaging materials and show adequate diffusion properties.
- Optimization of the packaging material composition and characteristics to provide the best preservation performance. This objective involves the complete characterization of the release of the preservatives from the different packaging materials into the target cosmetic products, and, the application of computer mathematical simulation studies.
- Pilot and industrial scaling-up of the active packaging materials developed to obtain final 3D active packaging prototypes. The achievement of this objective checked the viability of the available industrial processes to produce the new packages and implementation measures.
- Validation of the active packaging prototypes based on two key issues;
i) demonstrating the performance of the new prototypes in the industrial filling and packing lines of the cosmetic manufacturer/packer
ii) demonstrating the ability of the new active packages to preserve the microbial quality criteria of the cosmetic products
Project Results:
ACTICOSPACK was divided into three main phases:
- Phase 1 aimed to develop the new scientific knowledge needed to understand the behaviour of the cosmetic preservatives in the different systems (cosmetic products and packaging materials).
- Phase 2 dealt with the transformation of the scientific and technological knowledge generated in phase 1 into technologically advanced products (active packages releasing antimicrobial preservatives).
- Phase 3 dealt with the validation or demonstration of the performance of the new active packages with especial emphasis on demonstrating the industrial application and the added value that the new solutions will bring to the cosmetic products.
ACTICOSPACK generated results on each of these phases that demonstrated the suitability of the active packaging technology in reducing the levels of preservatives in cosmetic while maintaining its quality and safety along shelf-life.
Main results obtained in Phase 1
The first main result obtained was related with the selection of an initial set of preservative systems (PS) considered suitable to be used as cosmetic preservatives systems for each target cosmetic product (sun lotion, facial care cream and shampoo) and to be included into packaging materials for active package development.
Eight preservative systems were proposed. All of them are based on the mixture of several substances which provide synergies towards the antimicrobial activity. Some of these preservative systems are based on chemicals already used in cosmetic while others are quite innovative in its application as cosmetic preservatives and are derived from natural sources.
The performance of the preservative systems was evaluated towards antimicrobial effectiveness by means of in vitro and in situ tests. In addition, other complementary characterizations were performed dealing with the evaluation of the thermal and chemical stability as well as with the toxicological safety.
Antimicrobial efficacy of the 8 preservative systems was performed by means of microdilution susceptibility assays against different target microorganisms including bacteria such as Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus, and fungi such as Candida albicans and Aspergillus brasiliensis. In these tests, it was evaluated if the chosen preservative systems are antimicrobial effective in general. The tests were performed with the preservative systems alone (no cosmetic matrix) using microdilution susceptibility testing (“MIC-Test”). The MIC test evaluates the minimum concentration necessary to inhibit microbial growth. In this pretest, both native samples and samples after thermal treatment of the respective preservative system were investigated to evaluate potential loss of efficacy upon increased temperatures which are necessary for the incorporation process of the preservatives into the packaging.
The testing for antimicrobial efficacy of preservative systems and cosmetic product/preservative systems were performed according to 1) DIN EN ISO 11930:2012 „Evaluation of the antimicrobial protection of a cosmetic product”, 2) the European Pharmacopeia, Section 5.1.3 „Efficacy of antimicrobial preservation“ for cosmetic product challenge tests and 3) CLSI guidelines M07-A8 for antibacterial and M38-A2 and M27-A3 for antifungal susceptibility testing by microdilution assays.
The results obtained showed:
i) All preservative systems showed antimicrobial efficacy against Staphylococcus aureus. System 1 was only effective in medium concentrations, while system 2-8 were efficient at lower concentrations. Thermal treatment did not influence antimicrobial efficacy of any of the systems tested.
ii) All preservative systems showed antimicrobial efficacy against Escherichia coli. Preservative system 1, 4 and 5 were only effective in medium concentrations. Systems 2, 3 and 6-8 were efficient at low concentrations. Thermal treatment did not influence antimicrobial efficacy of any of the preservative systems.
iii) Results with Pseudomonas aeruginosa showed that this microorganism had the highest resistance vs. antimicrobial treatment with the preservative systems. Preservative System 1 was not efficient in the chosen concentration range. Preservative systems 4, 5, 6 and 7 were only effective at the highest concentrations. Systems 2, 3 and 8 were highly efficient at low concentration. Thermal treatment did not alter efficacy of systems 2-8, however, system 1 showed antimicrobial efficacy only after thermal treatment.
iv) All preservative systems showed antifungal efficacy against Candida albicans and Aspergillus brasiliensis (spores) in an acceptable concentration range.
Based on the results of the microdilution assays the most promising preservative systems were chosen to be measured in the cosmetic product challenge test:
- sun care: preservative system 2
- facial cream: preservative system 5
- shampoo: preservative system 8
Upon proven antimicrobial efficacy in the pretest, the performance of the preservative systems in the respective cosmetic products (sun care, facial cream and shampoo) was evaluated in challenge test (in situ tests).
To this end, different batches of cosmetic products containing around 6 - 7 different concentrations of each preservative system (including samples with no preservatives) were manufactured by the cosmetic partners. The performance of the preservative systems within the cosmetic product was tested using a challenge test adapted from the guidelines ISO11930 and European Pharmacopeia. This test consists in inoculating the different cosmetic products with a known volume of germ suspension. Then, the inoculated samples of the cosmetic products were incubated in the dark at room temperature for up to 28 days. On day 1, 7, 14 and 28 samples were drawn and the viable germ load was assessed via dilution plating on agar plates. The antimicrobial efficacy of the preservative systems was determined by assessment of the reduction of the viable germ number in the product versus the samples with no preservatives.
The challenge tests were performed starting with the most promising preservative systems according to the results of the microdilution susceptibility tests. In concrete, the antimicrobial efficacy of 5 systems was evaluated according to the acceptance criteria of ISO11930. The main results obtained showed:
i) Sun care + Preservative system 2
The presented data of the challenge tests using sun care lotion indicate that preservative system 2 is highly efficient in protecting the cosmetic product sun lotion against bacterial and fungal growth according to ISO11930 guideline acceptance criteria.
ii) Facial cream + Preservative system 5
The obtained data indicate that only high concentrations of preservative system 5 provide efficient protection of the facial cream cosmetic product versus all tested bacterial contaminations.
iii) Facial cream + Preservative system 5 + Preservative system 2
For all test germs it can be concluded that mostly there is no survival over time in facial cream with only PS5, but an outgrowth of Aspergillus can occur. Thus, the addition of PS2 increases efficacy and safety of the product.
iv) Shampoo + Preservative system 8
The chosen preservative system 8 provides efficient protection from growth of microorganisms that are able to survive in the shampoo matrix (E. coli, P.aeruginosa).
v) Shampoo + Preservative system 5 + Preservative system 2
For all test germs the survival in shampoo per se is very limited with viable germs only present until day 1 to 7. Thus, according to ISO11930 acceptance criteria no further protection by preservative system might be needed. However, the use of PS5+2 for some germs shows clear reduction of the bacterial load on day 1 indicating an increased safety with addition of PS5+2.
In addition to this antimicrobial evaluation, thermal & chemical stability and toxicological studies were performed as part of the evaluation of the suitability of the candidate PS to incorporated in active packaging materials.
The objective of the thermal stability study is to evaluate the suitability of the preservative systems to overcome the thermal stresses produced during the manufacturing of the active packaging materials. The preferred technique to incorporate the preservative systems into the packaging materials are based on working with the polymers in molten state at temperatures over the 180ºC.
The thermal stability of the preservative systems were carried out by means of two set of experiments. One based on Thermogravimetric Analyses (TGA) in which the PS were heated at a constant heating rate, and another one based on subjecting the PS to a constant temperature for a given period of time in a closed environment to reduce volatilities and measure real losses due to thermal degradation.
Prior to study the thermal stability of the preservative systems, it was necessary to develop the adequate analytical methodologies to determine the content of the main chemicals taking part of each preservative system. In this sense, methods based on gas and liquid chromatography techniques were set up.
As main results of the thermal stability analysis, almost all the chemical constituents in PS1 (natural extract) showed some extent of degradation. In this sense, the most important finding was the significant degradation of the terpinenes with a parallel increase of cymene. In this sense, some scientific publications have already reported that terpinenes are transformed by oxidation into cymene which could be favoured by the thermal treatments. Similarly to PS1, the terpinenes that were present in the PS6, 7 and 8 coming from the natural extracts that were added to these preservative systems were thermally degraded and transformed into cymene. Other natural substances were also moderately degraded after the thermal treatment. PS3, 4 and 5 showed also some degradation of some of the components (mainly those related with the natural extracts). Finally, PS2 was the most stable preservative system with no thermal degradation of the two chemical components of this PS.
The objective of the chemical stability study was to evaluate in what extent the preservative systems that were added to the cosmetics are consumed along time. The components of the preservative system could interact with some of the components of the cosmetic product reducing the available amount able to exert antimicrobial activity. Moreover, preservatives are usually consumed when exerting their action against microorganisms. As a consequence, the study of the evolution of the concentration of the preservative system in the cosmetic product is needed in order to set up their shelf-life.
The chemical stability study was based on the guidelines described by ICH (International Conference for Harmonization), Colipa (European cosmetic, toiletry and perfumery association), and Anvisa (Brazilian Health Agency). Samples of the three cosmetic products were exposed to three different storage conditions. Samples were taken at specific periods of time to analyse the content of the chemicals in the cosmetics by means of the ad-hoc developed analytical methodologies. In concrete, the chemical stability was measured up to 90 days.
The results obtained showed that some of the PS had a good chemical stability in the different cosmetic products while some degradations were observed for other active agents. For instance, the main component of PS3 showed a clear degradation and conversion into some degradation substance along time which was favoured by increasing the temperature.
Finally, the toxicological assessment of the selected PS was performed by carrying out several tests. In this sense, the toxicity assessment of the preservative systems were carried out in two phases. During the first one, cytotoxicity on Human HaCaT keratinocytes and AMES tests (method that uses bacteria to test whether a given chemical can cause mutations in the DNA of the test organism) were carried out with the whole set of preservative systems. Then, the final selected preservative systems were further evaluated in a second phase in terms of chromosome aberrations and cell gene mutations. The results coming from the first tests were used to screen the safety of all the preservative systems while the tests carried out in the second phase were performed to complete the safety dossier of the final selected systems.
The main results obtained in the first evaluation of the PS showed a good correlation between the different cytotoxicity tests performed with the Human HaCaT keratinocytes. Results allowed determining the lowest observed adverse effect levels (LOAELs) of each system. On the other hand, in the AMES test the preservative systems neither induced a two-fold or greater increase in the mean number of revertant colonies as compared to the negative controls nor a dose related increase. Therefore, the preservative systems tested did not induce a mutagenic effect (induction of gene mutation).
On the other hand, further complementary toxicity tests were carried out with the final selected preservative systems (i.e. PS2 and PS5):
i) In Vitro Mammalian Cell Gene Mutation Test (OECD Guideline 476) which measures the mutagenic potential of the PS based on quantification of forward mutations at the thymidine kinase locus of mouse lymphoma L5178Y/TK+/- cells, and,
ii) In Vitro Mammalian Chromosome Aberration Test (OECD Guideline 473) which measures if the PS has the potential to cause breakage of chromosomes (clastogenic) in cultured mammalian somatic cells.
The main conclusions arising from these two tests showed that neither PS2 nor PS5 showed evidences to be mutagenic in mammalian cells and to produce mammalian chromosome aberrations.
So far, all the results obtained were related with the study of the suitability of the PS to impart antimicrobial activity, to withstand thermal processes and to be safe. In Phase 1 of ACTICOSPACK it was also evaluated the feasibility of introducing the 8 preservative systems into different packaging materials by means of the conventional processes applied to produce the final target packages:
PE bottle for sun lotion, PP pot for facial cream and PET bottle for shampoo.
The first task in this part was to identify the requirements that the new active packaging materials should fulfil for each of the three target cosmetic products (facial cream, sun cream and shampoo). These requirements were mainly related with the cosmetic products themselves but also with the packaging processing technologies to be applied:
i) Extrusion blown moulding (EBM) for the PE bottles. It consists in a continuous or intermittent melt flow (called parison) coming from an extruder that goes to a mould to form the package. This technique represents the 65% of the market.
ii) Injection moulding for PP pots. Injection moulding is a processing technique for polymers that produces parts by pushing molten polymers into a mould by the action of a high pressure using a screw or piston. The mould cavity cools the polymers hardening them to the shape of the cavity. The most commonly thermoplastic polymers can be injected by this process although high flow index materials are the best choice, particularly for thin wall parts.
iii) Injection stretch blown moulding (ISBM) for PET bottles. ISBM processes are based on two processes and machines; injection moulding (IM) to produce the preforms and stretch blown moulding (SBM) to blow the preform into a hollow package. It is quite usual to find machines that integrate both processes (integrate two stations of the same machine). This is the most used technique to process rigid packaging based on PET.
Packaging requirements such as gas barrier properties or transparency are of key importance in the preservation and commercialization of the target cosmetic products. On the other hand, the development of packaging materials by extrusion processes may introduce thermal and mechanical stresses that need to be carefully evaluated in order to design the best approach to incorporate the active substances into the packaging materials.
Based on the initial 8 PS chosen at the beginning of the project, at least three PS were chosen to be studied for each packaging case. In the initial stages of the active packaging developments, the incorporation of the PS in the selected polymeric resins (PE, PP and PET) was carried out using a lab scaled twin screw extruder and injection module. The incorporation of the preservatives in each polymeric matrix was attempted at different contents. Considering the number of polymeric resins, the preservative systems, contents, replicates and repetitions for confirming results, more than 150 different extrusion batches or trials were carried out along these trials.
For each batch, the processing parameters (temperatures, screw speed, residence time, etc.) of the extruder and injection module were set in function of the technical data sheets provided by the polymer suppliers and in function of the observed behaviour of the blend polymer-preservative system. Some response parameters were recorded during the processing of the materials such as the torque of the screw versus time in order to analyse the effect on the processing of each preservative system and its concentration.
The main results obtained were for each case:
i) The preservative systems PS1, PS2 and PS3 were incorporated to three polymers used in EBM: PP, HDPE and LDPE. The inclusion of PS1 and PS2 into the PP and the HDPE could be carried out even at the highest preservative content. However, PS3 showed some incompatibility with the PP and the HDPE especially at high contents because of the inconsistence of the curves. In the case of the inclusion into LDPE, the 3 PS behave similarly. The viscosity variation during process is not significant at 2% compared with the processing of neat LDPE. At higher contents the materials become more fluid due to the plasticisation effect of the preservative systems.
ii) The preservative systems PS1, PS2, PS4 and PS5 were incorporated to PP for injection moulding. In this case, the response curves showed that all three systems behave well thus indicating a good incorporation into the polymer even at the highest content.
iii) The preservative systems PS6, PS7 and PS8 were incorporated to the PET. PET is a polyester polymer with a highly hygroscopic material that requires a previous drying before processing to reduce moisture. During the processing of this material, the mixing chamber was purged with nitrogen in order to ensure that polymer melt is free of oxygen and moisture taken from ambient.
First trials with the three preservative systems provoked a viscosity drop of more than 70%. This means that polymer was significantly damaged and PET becomes useless. Some other trials were carried out decreasing the content of the preservative systems. Even in these cases, comparing the torque curves of PET/PS compounds with the reference PET, the viscosity drops in more than 50% - 75%. That means that polymer properties cannot be ensured because of the significant molecular weight loss.
In order to check if these results were consequence only because of the preservative system or due to an interaction with the PET, the PS6, 7 and 8 were processed with PP. The curves obtained in this case showed that these PS behave similarly to PS1 with no big differences in comparison with the curve of the neat PP.
On the other hand, some additional tests trying to incorporate PS1 to PS5 into PET were also carried out. The results obtained showed that all the PS provoked a great impact on the processability of PET. These results confirmed that PET seemed to be no-good polymer for incorporating additives such as the cosmetic preservative systems as consequence of the results obtained.
At this stage, the ACTICOSPACK consortium decided to explore alternative approaches for the case of the active packaging development based on PET materials. These approaches considered the impossibility of introducing the PS directly into the PET matrix and therefore they considered the application of multilayer structures based on coating technologies. Two main approaches were researched. The first one involved the application of sprayable coatings and the second one involved the use of polymers applied as hot-melt coatings onto the PET bottles.
Regarding spray coating, several polymeric resins were tested. Some of them were commercialized in ready-to-use sprayable solutions dispersed in water or solvent and others were prepared in situ in laboratory. The preservative system was incorporated to the resin dispersions in several contents.
Then, these solutions were sprayed onto PET materials using an airspray system using a gravity handheld gun attached to a compressed air pipeline. Different parameters were optimized such as air pressure, fluid flow, number of strokes and time, temperature, etc. In this sense, almost all the systems could be sprayed. The materials were characterized in terms of grammage, thickness and adhesion of the sprayed coating layer to the PET based on the standard ISO 2409:2013 “Cross-cut test”. In addition, the content of preservative incorporated to each material was determined by means of thermogravimetry analyses (TGA) and by chemical solvent extraction and subsequent chromatographic analyses.
Based on the results obtained, it was concluded that the spray coatings were adequate in terms of sprayability, adhesion to PET substrate and incorporation of PS, although the process required further optimization.
However, after carrying out some ageing tests in which shampoo was put in contact with coated PET, it was observed that the anchorage of the polymer was not strong enough to resist the chemical attack of the shampoo components. Therefore, a new battery of trials were carried out in order to improve the adhesion between the coating layer containing the active agents of PS and the PET materials.
The new trials involved the application of PET surface treatments, the use of primers and other coating polymer resins. In this sense, the results obtained with the new resin showed a good sprayability of the solutions containing PS, a good transparency and an adequate adherence to the PET materials even after contact with the shampoo. In fact, spray coating trials were carried out at pilot scale level in Phase 2. However, the active packaging system obtained was not suitable to satisfy the demanded antimicrobial requirements of the shampoo.
In this sense, a new approach was researched based on the application of hot-melt resins as coating layers to the PET. To this end, the resins were mixed with the preservative system PS by means of a melting extruder and the molten compound was directly added to the PET materials like in a lamination process. The results obtained after characterizing this system showed an adequate adhesion after contact with shampoo for at least 2 months and a significant content of PS incorporated. Therefore, this system was finally selected to be scaled-up in Phase 2 of the project as part of the active package development for PET bottles.
In addition to the evaluation of the processability of the materials by means of extrusion/injection and spray/hot-melt coating processes, the content of PS surviving to each case and the homogeneity of the different materials developed was evaluated to confirm that a real active package was obtained.
To this end, the content of the PS and the main active chemicals that were incorporated in the different packaging materials was analysed by means of thermogravimetric (TGA) and chemical analyses which were developed ad-hoc for each specific case. The adequate analytical methodology was developed by setting up a first step based on the extraction of the preservative systems with different type of solvents and the subsequent quantification carried out by means of gas and liquid chromatographic techniques. The development of these analytical methodologies are crucial as future assays to be considered in the quality control of the new active packages produced at industrial level.
The PS quantification results obtained showed a clear correlation between the content determined by TGA and chemical analysis and the amount of PS added to the packaging materials during the processing trials. The percentage of PS incorporated (that is an estimation of the yield of the process) showed values ranged between the 50% and 100%. In terms of comparative results, the materials based on the incorporation of PS2 gave the best values with rates of incorporation higher than 85%, independently of the polymeric matrix. Finally, the quantification results obtained when analysing the active materials based on PET clearly showed the chemical reaction between PET and most of the PS since no PS could be detected in any case.
Considering the results obtained in the characterization of the PS and the active packaging development results it was concluded that the most promising final active packaging/cosmetic systems would be based on the following combinations:
i) Active PE bottle incorporating PS2 for sun lotion products
ii) Active PP pot incorporating PS2 for facial cream products already containing PS5 in the cosmetic formulation
iii) Active PET bottle based on coating layer containing PS2 for shampoo already containing PS5 in the cosmetic formulation
Next activities focused on studying the release of the PS from each packaging material aiming at describing the mode of action of the materials which involves three steps:
i) Diffusion of the preservatives through the polymeric matrix
ii) Dissolution or mass transfer of the preservative at the interface packaging-product
iii) Diffusion or dispersion of the preservative through the cosmetic matrix.
The migration or release of the PS from the packages continues until an equilibrium between the content in packaging and the cosmetic is reached. Three parameters are of key importance when characterizing the release from active packages to cosmetics; the diffusion rate in the package (D pack), the diffusion rate in the cosmetic (D cosm) and the ratio between the concentration in the package and in the cosmetic product at equilibrium (K). Several mass-transfer tests were carried out to determine these kinetic and equilibrium parameters under controlled environmental conditions in order to accurately assess the performance and effectiveness of the active packaging materials developed into the project:
i) The diffusion coefficients through the different cosmetic matrices were estimated for PS2. The results obtained showed that the diffusion coefficients were dependent on the type of cosmetic matrix. For instance, diffusion in the shampoo was faster than in facial cream, while diffusion in sun lotion showed the lowest values.
ii) The diffusion within the packaging materials was studied considering an experimental design in a way that mathematical modelling of the migration kinetics could be performed. The results obtained showed that the PS was able to be released from the different polymeric matrices. Although the kinetics associated to each case was different; coated PET showed the faster kinetics, followed by PE and PP matrices. On the other hand, it was observed that the higher the temperature, the faster the release of PS.
iii) Finally, the equilibrium coefficients (K) which offers a measure of the ratio between the content of active agent in the packaging material to the content in the cosmetic were also evaluated by placing in contact de packaging materials containing the preservatives and the cosmetic products. The K values obtained reflect the differences between the different systems. The K values decrease as the temperature increases what means that the release of the active agents is favoured at higher temperatures. On the other hand, the K values for the system based on PE/sun lotion showed lower values than the PP/facial cream. For the case of the system based on EVA disk for PET and the shampoo, the release of the active agents was almost complete.
In the framework of ACTICOSPACK, the effectiveness of the active package is strongly related to the balance between the controlled release of the cosmetic preservatives and the microbial growth kinetics. In this sense, microbial inhibition cannot be achieved if the release rate of the active preservatives from the package is not sufficient to reach the minimum inhibition concentration (MIC) of the target microorganism or cannot be sustained throughout cosmetic shelf-life because it is too fast. Therefore, the optimal active packaging properties have to be obtained.
In this sense, the estimated diffusion from the package (D pack) and the equilibrium constant (K) are the key parameters in this case: The first parameter should be equal to the consumption/degradation rate of the PS in the cosmetic matrix and the second one should have a value that allows getting a preservative content in the cosmetic product close to the MIC value.
Once obtained these parameters, they were used to optimize the active package characteristics by means of mathematical simulations carried out with specific calculation software. The goal of the mathematical simulations performed was to find the most adequate active package for the preservation of the target cosmetics considering the specific systems of ACTICOSPACK.
To this end, different scenarios were simulated considering different degradation/consumption rate of PS in the cosmetic matrices along its shelf-life. In this sense, it was stablished as goal to recover up to a 30% of the amount of active agents lost by degradation/consumption along the cosmetic shelf-life with the active packages.
In a first optimization step of each of the packaging solutions for the specific cosmetic products, it was determined that the best packages would have a large thickness that makes industrially not feasible to produce them. Therefore, a refinement of the active package characteristics was considered. In this sense, the content of each individual chemical agent taking part of PS2 was optimized for each case of package/cosmetic.
After this optimization carried out by mathematical simulation, a comparison between the expected performance of the new active packages versus the use of overdosed cosmetics packed into conventional packages with non-active properties was performed for each package/cosmetic case. In this sense, the main results obtained showed that the values that are achieved are ranged between the 7.5% of shelf-life extension for the case of the coated PET bottle for shampoo containing 3% less of preservatives, the 25% for the case of the PE bottle for sun lotion containing 5% less of preservatives and the 90% for the case of the PP pot for facial cream containing 9% less of preservatives.
Therefore, the use of the active packages developed into the project increases the preservation of the target cosmetics what is a valuable new tool for its commercialization.
Main results obtained in Phase 2
Once determined the active packages to be developed for each cosmetic case, Phase 2 aimed at scaling-up the developments to pilot and industrial levels to obtain some kind of 3D package prototypes: PE bottle, PP pot and PET bottle with an active coating.
Several trials were carried out by the packaging industrial partners along the project in order to fix the processing windows, to produce samples for further tests in other WPs and to study a complete battery of packaging characteristics.
The main goal of these trials was to set-up the processing windows (that is the parameters controlling the manufacturing process) of the pilot/industrial lines to the new materials. Therefore, an assessment of the industrial processability of the materials and the identification of possible additional processing activities raised during trials in the industrial environment were obtained.
Results showed that in all the cases, a previous compounding process was needed. Compounding is a process of mixing or blending polymers with additives in molten state. There are many processes called formally, “melt compounding” although the most used technique in plastics industry is to use intermeshing twin-screw extruders as compounding equipment.
Due the huge number of compounding processes, there are many possibilities to configure the process in terms of equipment definition, feeding systems and feeding sequence. The selection of a specific machine configuration for a given blend or mixture depends on the nature of components to be blended and the physical parameters like viscosity, volatility and chemical moieties. The configuration of the screw of the compounding extruder is of key importance in order to effectively blend PS with the corresponding polymers for each package. Several temperature profiles were tried in order to optimise the compounding conditions. In this sense, the objective was to process at as much low temperature as possible to reduce the possible thermal degradation of the active components. On the other hand, other parameters like production and screw speed were also optimised in order to maintain a reasonable level of energy.
All the compounds (i.e. blends of PS2 and polymers) were characterized in terms of PS2 content to evaluate the yield of the compounding process and the melt flow index (MFI). The results obtained showed the incorporation of PS2 to the compounds were above 90%. This yield was significantly higher than the values observed in the laboratory trials due to the higher efficiency of the pilot scale feeders and because of the lower residence time into the extruder. On the other hand, it was observed that the addition of PS2 changed the rheological behaviour of the polymers. The MFI increased with the increase of the content of PS2. This increase showed a linear tendency and the MFI was twice the neat polymer for the compounds with the highest content of PS2. For the case of PE, the melt strength (which is important in EBM process) could be affected, but the best way to evaluate the impact of the variation of this parameter is to process using a real geometry of the parison and bottle (stretch ratio). It was supposed that the introduction of some small variation on the processing temperature of the extrusion blown moulding will compensate the viscosity drop. The evaluation of the quality of the package, particularly the thickness profile, will be critical to evaluate if the parison has enough melt strength. In the case of PP, the injection moulding process will probably not be limited by such MFI variation.
After generating the active compounds, they were used to manufacture the different target active packages:
i) The industrial equipment used for the production of the PE bottles consisted in an extrusion blow moulding machine, a mould and other auxiliaries such as the raw material feeding system and the leak tester. The EBM plant was composed by an extruder, an extrusion die that forms three parisons, a cutting device, and a clamping system. The mould has 6 cavities and it was divided into two parts of three cavities each, that work alternatively during the cycle time. This allows the overlapping of other operations, thus improving the production capacity. Five different combinations of materials were processed at the industrial trials.
The materials could be processed without major problems. The only required modification was the decrease of the die temperatures. This modification was in technical agreement with the increase of the MFI measured on the blends. It was also noticed that the scrap parts were cut with more difficulty for the compound with the highest PS2 content although just a minor regulation of the cutting parts was required.
All the new package prototypes collected for quality control tests resulted in conformity with the production specifications. No difference in the quality attributes can be identified between the standard components and the parts manufactured with the new active compounds.
ii) The industrial equipment used for the production of the PP pots consisted in an injection moulding machine. The mould has 6 cavities injected at once. Four different combinations of materials were processed at the industrial trials.
The processing conditions needed to be slightly changed when injecting the PP based compounds containing PS2. These changes were mainly related to the increase of the MFI of the compounds and because of the appearance of some visual defects (mainly flashes and halos) of the package prototypes which were corrected by changing the injection speed, the second injection pressure and the back pressure.
There were not significant troubles in the injection moulding of all the PP/PS2 compounds. In fact, all the compounds had a similar rheological behaviour so that there was no need to change the processing parameters when the different compounds were processed.
iii) Finally, the application of the active coatings onto PET bottles was successfully carried out using a pilot scale extruder. All the processes needed to developed the active bottles were carried out in one single step: Compounding of coating polymer with PS2 and the application of the molten polymeric compound to the PET bottle. The implementation of this solution at industrial level can be easily performed by introducing a ram extruder or mass molten injection system.
In conclusion, the different tests carried out indicated that the new active compounds were successfully processed at industrial and pilot scale levels.
After the production of the new active package prototypes they were characterized in terms of mechanical, chemical, barrier to gases and thermal properties to evaluate the possible impact of the addition of the PS into the polymeric matrix on all of them. In this sense, some target requirements imposed by each specific cosmetic product selected into the project (sun lotion, facial cream and shampoo) to their corresponding packages (PE bottle, PP pot and PET bottle, respectively) were previously identified in Phase 1.
The main results obtained showed that the active packages tend to have poorer properties than the conventional ones, although considering the packaging requirements identified for the target cosmetics, in none of the cases the modified packaging properties restricted the use within the current conditions to commercialize them.
In concrete, for the case of the PET bottles for shampoo, the inclusion of the active coating on the PET bottle does not alter the inherent barrier, mechanical and thermal properties of the conventional package. The main difference between the active package and the conventional one is in terms of weight since the coating increased it.
For the case of the PE based bottles for sun lotion, the inclusion of PS2 into the PE polymeric material just modifies the oxygen permeability and mechanical properties of the materials versus the conventional PE bottles. In this sense, the modification of the barrier properties to oxygen is not critical since the wall thickness of the bottle is still high enough to consider the material as good barrier package. On the other hand, the modification of the mechanical properties, especially the vertical compression resistance, does not have any impact on the current transport and distribution practices; more than 100 package units could be stuck above the new packages which is by far higher than the current practices.
Similarly to the case of the PE bottles, the main properties affected for the PP active pots (oxygen barrier and mechanical resistance) do not have any practical effect when considering the target cosmetic and the current transport and distribution practices. The oxygen barrier properties and mechanical resistance are lower than the values given by the conventional packages but the values are completely suitable for the target cosmetic requirements. The thickness of the active PP pot confers very good barrier properties while the inclusion of the active PP pot inside other external PP pot avoids the exposure of the active PP pot to mechanical stresses. Anyway, the active PP pot alone will be able to withstand more than 700 package units above it.
Therefore, although some properties of the packages have been modified as consequence of the inclusion of the active preservative system, this does not alter the normal practices in using these cosmetic packages.
Main results obtained in Phase 3
The final phase of the project started once the active prototypes were industrially developed. In this phase, the new packages were used to carry out filling and packing trials at the industrial facilities of the cosmetic producer and to study the evolution of the quality of the cosmetics along time.
In these filling and packing trials, two series of packages were carried out inside cleanrooms with a controlled environment preventing contaminations; one using the conventional or habitual package (i.e. non-active) and another one using the active packages. After the trial, the main conclusion was that no specific modifications in the normal packaging process applied by the cosmetic manufacturer needed to be considered when using the new active packages.
The three different cosmetics packed into the active and non-active packages were studied along time to determine the microbial, chemical and sensorial quality. In this sense, a real storage test should be carried out. However, these tests were un-practical to be performed within the schedule of the project since they usually take at least from 6 months up to 1 year. Therefore, it was decided to carry out an ad-hoc test aiming to find differences between active and non-active packages in the microbial quality of the cosmetics within 1-1.5 months of test duration.
To this end, the initial content of preservatives directly incorporated into the cosmetic products were in most of the cases below the MIC in order to bring the microbial preservation of the cosmetics below the limit at the initial time. Subsequently, the idea was to bring the cosmetic preservation above this MIC value because of the release of the preservative agents from the packages.
The performance of the active packaging regarding antimicrobial activity was tested in situ in the cosmetic products packed in the active versus the control conventional packaging. In parallel, the release of the active agents was followed along storage days both in the cosmetic products and in the packages. Finally, the cosmetics were evaluated in terms of sensorial attributes by means of the study of the colour, aspect, consistency of the cosmetic matrix, separation of phases and odours by the technical staff of the cosmetic producer.
The results obtained showed that the active packages were able to release the preservatives and no sensorial differences were found. In addition, several trends towards an increased antimicrobial performance of the active packages versus non-active ones were observed for sun lotion and shampoo. Unfortunately, facial cream was contaminated with external microorganisms and the antimicrobial tests could not be performed.
The results obtained in these tests provided valuable information to be considered in the simulation models to further optimize the new active packages considering real shelf-life conditions.
Potential Impact:
The expected final result in ACTICOSPACK project was to reduce the content of preservatives used in cosmetics while keeping its quality and safety along the same or even longer shelf-life. The proposed technological solution to achieve this goal was to develop tailor-made active packages for three specific cosmetic products. In concrete, ACTICOSPACK involved the following systems:
1. Active bottle based on PET for shampoo
2. Active bottle based on PE for sun lotion
3. Active pot based on PP for facial care cream
Different results were obtained along the project lifetime that were approaching the project to its final goal. A continuous evaluation of the advancement was monitored by checking the results versus the key milestones. They included the identification of preservative systems joining an adequate antimicrobial effectiveness for each cosmetic product in addition to an adequate thermal stability to be processed at high temperature when incorporated into the packaging materials. Other key milestones included the verification of the implementation of results at industrial level to obtain real 3D packages and the evidence of an adequate performance of the active packaging systems.
As final conclusion of ACTICOSPACK, results demonstrated that the reduction of preservatives in the cosmetics is possible while keeping an adequate preservation. In fact, the current level of the preservative system worked into the project used in cosmetics are around 0.9% while the eventual combination of natural preservatives and the active packages makes possible its reduction to levels of 0.5% or even lower thus meaning reductions around 50%.
The activities carried out within the project provided an overall approach to packaging development valuable for all companies. Besides foreground knowledge achieved, companies have evaluated patentability of the new products and will proceed according to this patentability evaluation. In addition, further steps towards industrialization of results and market introduction are being evaluated by project members in an active way.
Based on the potential benefits carried out by ACTICOSPACK results, wider implications are envisaged at politics, society, economy and even at environmental level:
Political – Safety and human health protection is a key topic at European level. European Scientific Committees has recently recommended restricting the limits of some preservatives such as propyl- and butylparaben, and more restrictions are envisaged. The new packages will contribute in replacing paraben derivatives in the cosmetic formulation thus alleviating in some way the uncertainty whether the actual allowed maximum content confers the adequate margin of safety.
Societal – Consumers demand less synthetic preservatives and more green or natural cosmetic products. Both demands are fulfilled with the new packages; parabens can be replaced or reduced but also the green or natural preservatives. At relative large contents, the natural origin of the preservative is not a guarantee of safety and can also impart sensory alterations in the cosmetic products.
Commercial – The possibility of enhancing the cosmetic stability and thus extending the shelf life of the cosmetic products with the new solution brings the opportunity to the European cosmetic SMEs of expanding their business beyond local and national frontiers. This will place Europe at the forefront of the packaging technology and make stronger the exporting position of Europe in the global market.
Environmental – The cosmetic sector is also aware to the sustainability. In this sense, the possibility of extending the shelf life of the cosmetic products with the new solution will reduce the cosmetic wastes but more importantly will reduce the packaging wastes (the personal care packaging involves several thousand million packaging units). In addition, larger shelf life also favours larger size packages that also reduce packaging wastes.
Economic – The European trend of reducing the levels of preservatives in the formulations are forcing to invest money and resources in new formulations and new preservative systems. Substitution of a new ingredient typically requires the manufacturer to conduct a full-scale reformulation effort including safety, stability, and consumer acceptance tests. In this sense, the new active package brings a technological solution to the cosmetic sector to adapt to new content restrictions and consumer’s demands based on the same formulation but with less preservatives.
Finally, several materials for disseminating the project, the main results obtained and the European funds provided by the Research for SMEs project programme were developed. In concrete, information of the project was disseminated through different channels along the project lifetime and some of them can still be found via internet:
• Specific project website at http://www.acticospack.eu
• Brochure
• Press releases available in printed and electronic portals
• Specific video on the project (available at http://www.acticospack.eu)
• Video news at national TV channels
• Specific poster of the project
List of Websites:
http://www.acticospack.eu
Relevant contact details:
Coordinator
ESPANOLA DE NUEVOS TRATAMIENTOS SA
Spain
CALLE JORDI DE SANT JORDI S N
ALCOY, Spain
Administrative contact: Luis Torró
Tel.: +34902 820 750
Participants
INDUPLAST SPA
Italy
VIA EUROPA 34
BOLGARE, Italy
Administrative contact: Rossana Cortesi
Tel.: +390358354103
GEPACK – EMPRESA TRANSFORMADORA DE PLASTICOS SA
Portugal
RUA 1 DE AVRIL EDIFICIO GEPACK
AVEIRAS DE CIMA, Portugal
Administrative contact: Ana Domingos
Tel.: +351 263 470 210
LAMEPLAST SPA
Italy
VIA G. VERGA 1-27
NOVI DI MOENA, Italy
Administrative contact: Enrico Salvarani
Tel.: +39059673873
Fax: +39059671688
INSTITUTO TECNOLOGICO DEL EMBALAJE, TRANSPORTE Y LOGISTICA
Spain
Calle Albert Einstein. Parque Tecnológico. 1
Paterna, Spain
Administrative contact: Jose Bermudez
Tel.: +34 961820114
Fax: +34 961820001
FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG E.V
Germany
Hansastrasse 27C
MUENCHEN, Germany
Administrative contact: Meike Muller
Tel.: +49 89 1205 2723
Fax: +49 89 1205 7534