Skip to main content

Nanotextured surfaces for membranes, protective textiles, friction pads and abrasive materials

Periodic Reporting for period 2 - NanoTextSurf (Nanotextured surfaces for membranes, protective textiles, friction pads and abrasive materials)

Reporting period: 2019-05-01 to 2020-11-30

The project approach was to develop nanostructured surfaces with bionanomaterials. Nanocelluloses produced either with chemical and/or mechanical means from cellulose fibres are non-toxic, biodegradable, ultra-strong and durable. They can be used to replace currently used hazard materials in innovative products and improve product durability. However, cellulose nanomaterials are viscous dispersions and therefore it is necessary to modify existing surface treatment application processes for applying them. The use of cellulose nanomaterials have been studied earlier mainly in laboratory scale. The nanotextured products and their mechanically enhanced performance were demonstrated with pilot scale trials. The production of novel durable products need to be profitable, environmentally acceptable and safe not only for producers but also for users.
Main objectives were to develop open access pilot lines on industrially relevant scale and use them to demonstrate nanotextured products. These surface treated products targeted for improved mechanical properties and durability. The results were planned to be transferred to the existing manufacturing lines. The project targeted to generate new jobs and secure that the manufacturing of developed products would be more sustainable than existing ones.
Optimised formulations based on nanocelluloses were studied for cast coating thin layers on industrial membranes. Pre-treatments of industrial membranes and nanocellulose coating formulations were studied to ensure adequate adhesion between nanocellulose and substrate interface. This additional anchoring polymer improved adhesion and therefore application basins were designed and executed in the surface treatment pilot line. The antifouling capability of the coatings was determined with protein adhesion method in continuous flux conditions. This in pilot scale demonstrated solution showed that nanocellulose coated microfiltration membranes had potential as ultrafiltration system but higher porosity is still needed for an efficient ultrafiltration process.
Different surfactants were studied to foam nanocelluloses and produce stable foams for the surface treatment of nonwovens for water filtering application. The effect of additives on bubble properties, the stability of nanocellulose foams in application were first studied in laboratory. Later both foam and dispersion coatings were applied on viscose substrate in pilot-scale. The water permeance and capture of metal ions was evaluated. They showed attractive metal ion adsorption but more tests, in particular under real non-laboratory conditions, are required to push this technology towards industrial scale. These filters had already good performance to remove hardness and suspended solids.
Nanocellulose based screen printing formulations were studied for protective textiles. The target was to develop lean products with high strength properties without impairing moisture control and breathability. Optimised formulations were trialled with different screens first in laboratory and pilot scale in order to study stability and product performance. The final demonstrations in production scale confirmed that nanocelluloses improved the tensile properties of fabrics in both directions but the tear strength improved only in one direction. The air permeability was reduced but water vapour resistance was not significantly affected.
A nanocellulose based formulation was applied with cast coating to produce flexible materials with stable friction properties, low vibrations and low wear. They were tested in laboratory and with high loading tests. The friction coefficient obtained was in the range required for friction paper used on multiple-disc clutches. The developed material was able to hold the load at which the cranes operate but was not able to hold an overload that is necessary to allow for a margin of error in the operation. The coated textile wes were impregnated with other chemicals to improve their performance further. These friction pads showed excellent durability and very good fading behaviour, important property in determining reliability.
The results of the developed barrier paper for abrasive materials indicated that they can be used for the development of abrasive paper products with lower environmental impacts than thw ones with oil-based solutions. The second approach to develop innovative abrasive materials on textiles was to use organic solvent free foam coating formulation that was designed with water-based organic binders and small abrasive particles. The pilot foam coating application was modified to improve the controllability and adjustment of the nip with two rolls in the application. The third approach on plastic substrate was to replace partially oil-based UV curable binder with nanocellulose to obtain higher mechanical durability with printing technology. The final demonstrators were produced with upgraded open access coating and existing industrial printing pilot lines. The results were evaluated with industrial sanding tests and compared to the existing products. These developed abrasive structures are suitable to finessing type sanding applications.
Besides the product related modifications to the pilot machines, solutions to tackle general challenges were studied. Drying of the cast coated nanocellulose layers is a major challenge and was studied in pilot scale in order to find efficient application and drying strategies. The in-line measuring technologies to measure the thickness of the applied film or coating layer and moisture content after drying were studied. These techniques were proven to function and were executed to be available for future trials.
Four potential demonstration cases were chosen for sustainability assessment. The success of the innovative products for membranes were directly linked to the targeted performance criteria. If achieved in future, the production of the enhanced product seems promising. Combined sustainability and safety assessments of the enhanced protective textiles are encouraging for the further development as they could create a new market niche. The sustainability and safety assessment of the final innovative production concept developed for friction materials need to be finalised later when the final concept and more reliable data is available. Based on all aspects covered by the sustainability and safety assessment of the innovative abrasive material products a market launch seems very promising. Other industrial areas benefiting from results outside the consortium could be hospital textiles, industrial wipes, air purification filters and food packaging materials.
Fouling of membranes is one of the key cost parameters for membrane plants causing costs related to needs of more frequent cleaning or replacement of the membranes. Further research is needed to achieve the targeted impacts. The costs of friction materials can be reduced, if the number of components are reduced. The concept for innovative friction materials by coating looks promising but it requires further development and techno-economic studies before taking it to market as ready product. Barrier solution and two novel concepts for abrasive materials look very promising and their development is continued directly in three industrial scale implementation projects. Results will be exploited in packaging materials, nonwovens for health care sector and in other industrial areas.
Open access pilot illustration
Open access pilot photo
In-line measurement, photo
NanoTextSurf project logo