Periodic Reporting for period 1 - CelloSparx (Sustainable pigments and glitter from renewable cellulose)
Reporting period: 2023-08-01 to 2025-01-31
Effect pigments, tiny glittering particles that add shine to products, are worth over $2.3 billion and account for 16% of the global inorganic pigment trade. Found in products such as car paints, cosmetics, fashion and food, these pigments contain harmful materials such as microplastics, metals and mineral oxides. Microplastics, which accumulate in the body and in water supplies, are a key concern, with 5,500 tonnes released into European waters each year from cosmetics alone. Glitter microplastics account for 0.05% of this pollution, prompting EU bans on single-use plastics and microplastics in various applications.
Mica and titanium dioxide, commonly used in effect pigments, are also of concern. Mica is mined by over 30,000 children in India, and although responsible initiatives exist, they have failed to meet targets. Titania has been linked to cancer risks, leading to a European ban on its use in food by 2022, and raising concerns about its use in cosmetics, pharmaceuticals and packaging. Companies that rely on titania-based pigments are looking for alternatives.
The plastics industry is a major source of carbon emissions, and mineral extraction processes also emit significant greenhouse gases. These materials are unsustainable over their entire life cycle, creating an urgent need for truly sustainable alternatives to traditional effect pigments and glitter.
CelloSparx aims to develop a climate-friendly and circular alternative to traditional effect pigments and glitter based on cellulose, the most abundant biopolymer on the planet.
The origin: Prof. Silvia Vignolini's research focuses on understanding how nature produces vibrant colours and how to develop cellulose-based dyes and pigments. Prior to the project, her group at the Department of Chemistry at the University of Cambridge demonstrated a way to scale up the production of the pigments. One of the bottlenecks has been access to sufficient production capacity to put key process insights into practice. The group had already developed formulations to produce high quality multi-coloured pigments at laboratory scale. However, the production process was highly manual and inefficient, relying, for example, on slow drying conditions.
In the project, we aimed to move this much-needed technology from TRL6 to TRL7 by addressing two main objectives: 1) to scale up the production of the effect pigments and glitter from several grams to kilograms and 2) to demonstrate the low carbon footprint, biodegradability and ecotoxicity of the effect pigments produced.
Mica and titanium dioxide, commonly used in effect pigments, are also of concern. Mica is mined by over 30,000 children in India, and although responsible initiatives exist, they have failed to meet targets. Titania has been linked to cancer risks, leading to a European ban on its use in food by 2022, and raising concerns about its use in cosmetics, pharmaceuticals and packaging. Companies that rely on titania-based pigments are looking for alternatives.
The plastics industry is a major source of carbon emissions, and mineral extraction processes also emit significant greenhouse gases. These materials are unsustainable over their entire life cycle, creating an urgent need for truly sustainable alternatives to traditional effect pigments and glitter.
CelloSparx aims to develop a climate-friendly and circular alternative to traditional effect pigments and glitter based on cellulose, the most abundant biopolymer on the planet.
The origin: Prof. Silvia Vignolini's research focuses on understanding how nature produces vibrant colours and how to develop cellulose-based dyes and pigments. Prior to the project, her group at the Department of Chemistry at the University of Cambridge demonstrated a way to scale up the production of the pigments. One of the bottlenecks has been access to sufficient production capacity to put key process insights into practice. The group had already developed formulations to produce high quality multi-coloured pigments at laboratory scale. However, the production process was highly manual and inefficient, relying, for example, on slow drying conditions.
In the project, we aimed to move this much-needed technology from TRL6 to TRL7 by addressing two main objectives: 1) to scale up the production of the effect pigments and glitter from several grams to kilograms and 2) to demonstrate the low carbon footprint, biodegradability and ecotoxicity of the effect pigments produced.
Activities performed and main achievements
Optimisation of Cellulose nanocrystal (CNC) formulation
Firstly, we focused on adapting our formulations to the suspensions provided by the new manufacturer CelluForce (https://celluforce.com/(opens in new window)) and innovating with a new preparation protocol. We focused on optimising cellulose nanocrystal (CNC) stability and processability by studying the influence of desulfation on CNCs. CNCs prepared via H2SO4 hydrolysis carry negatively charged sulfate groups on their surface.
1 These surface charges not only facilitate CNC dispersion through electrostatic repulsion but also play a pivotal role in determining their suspension behaviours and self-assembly properties.2 3 However, detailed investigations into the relationship between surface charge density, suspension dynamics, and the resulting structural colouration remain limited. By understanding this process, CNCs can be precisely tailored to create an economical, scalable and application-specific large-scale CNC manufacturing process. Using a single batch of CNCs, the variability in CNC length, width, and thickness was minimised in our studies, allowing well-controlled experiments to focus on surface charge modifications only. Among the different desulfation methods, hydrothermal treatment showed minimal effect on CNC morphology compared to NaOH or HCl treatments.
Scale-up of CNC production
The next important step was to scale up production to the kilogram level. To facilitate scale-up, the project evaluated several commercially available production lines, including different application and drying technologies. A company, Sparxell (https://sparxell.com/(opens in new window)) has been set up to exploit the results of the project. Sparxell is enabled to scale up the production of photonic films from laboratory scale to pilot scale production.
Significant progress has been made towards kilo-scale production. Pigment production capacity was scaled up 100-fold, reaching kg-scale by testing different drying rates and temperature profiles. The coating liquid deposition process was improved, and modifications were made to the existing line to provide the necessary parameters for consistent product manufacturing. Liquid preparation and application studies were carried out. We have defined the parameters to achieve sufficiently high liquid and film quality and demonstrated repeatable pigment production over a number of trials.
The market engagement was well received and supported the launch of the Sparxell spin-out.
As part of the project, a study was conducted and published to assess the ecotoxicological effects of cellulose nanocrystalline glitter compared to conventional polyethylene terephthalate (PET) glitter. These results position CNC glitter as an environmentally friendly alternative to PET glitter, potentially reducing the ecological risks associated with microplastic pollution in soil.
The main objectives of the project—1) scaling up the production of effect pigments and glitter from several grams to kilograms, and 2) demonstrating the low carbon footprint, biodegradability, and ecotoxicity of the produced pigments—the following results have been achieved:
Scale-up
Pigment production capacity was scaled up 100-fold to kg scale by testing different drying rates and temperature profiles, fulfilling objective 1 of the project.
A spin-out company, Sparxell (https://sparxell.com/(opens in new window)) was established enabling the scale up the production of photonic films from laboratory to pilot scale
Optimisation of Cellulose nanocrystal (CNC) formulation
Firstly, we focused on adapting our formulations to the suspensions provided by the new manufacturer CelluForce (https://celluforce.com/(opens in new window)) and innovating with a new preparation protocol. We focused on optimising cellulose nanocrystal (CNC) stability and processability by studying the influence of desulfation on CNCs. CNCs prepared via H2SO4 hydrolysis carry negatively charged sulfate groups on their surface.
1 These surface charges not only facilitate CNC dispersion through electrostatic repulsion but also play a pivotal role in determining their suspension behaviours and self-assembly properties.2 3 However, detailed investigations into the relationship between surface charge density, suspension dynamics, and the resulting structural colouration remain limited. By understanding this process, CNCs can be precisely tailored to create an economical, scalable and application-specific large-scale CNC manufacturing process. Using a single batch of CNCs, the variability in CNC length, width, and thickness was minimised in our studies, allowing well-controlled experiments to focus on surface charge modifications only. Among the different desulfation methods, hydrothermal treatment showed minimal effect on CNC morphology compared to NaOH or HCl treatments.
Scale-up of CNC production
The next important step was to scale up production to the kilogram level. To facilitate scale-up, the project evaluated several commercially available production lines, including different application and drying technologies. A company, Sparxell (https://sparxell.com/(opens in new window)) has been set up to exploit the results of the project. Sparxell is enabled to scale up the production of photonic films from laboratory scale to pilot scale production.
Significant progress has been made towards kilo-scale production. Pigment production capacity was scaled up 100-fold, reaching kg-scale by testing different drying rates and temperature profiles. The coating liquid deposition process was improved, and modifications were made to the existing line to provide the necessary parameters for consistent product manufacturing. Liquid preparation and application studies were carried out. We have defined the parameters to achieve sufficiently high liquid and film quality and demonstrated repeatable pigment production over a number of trials.
The market engagement was well received and supported the launch of the Sparxell spin-out.
As part of the project, a study was conducted and published to assess the ecotoxicological effects of cellulose nanocrystalline glitter compared to conventional polyethylene terephthalate (PET) glitter. These results position CNC glitter as an environmentally friendly alternative to PET glitter, potentially reducing the ecological risks associated with microplastic pollution in soil.
The main objectives of the project—1) scaling up the production of effect pigments and glitter from several grams to kilograms, and 2) demonstrating the low carbon footprint, biodegradability, and ecotoxicity of the produced pigments—the following results have been achieved:
Scale-up
Pigment production capacity was scaled up 100-fold to kg scale by testing different drying rates and temperature profiles, fulfilling objective 1 of the project.
A spin-out company, Sparxell (https://sparxell.com/(opens in new window)) was established enabling the scale up the production of photonic films from laboratory to pilot scale
Impact
The pigments we develop deliver colour intensity and sparkle, and because they are made entirely from cellulose, they offer the competitive advantage of being biodegradable, while eliminating the concerns associated with other products. They can directly replace large plastic-based glitter used in textiles and housewares, and compete with highly processed and problematic titanium dioxide and mica-based effect pigments used in cosmetics, food, paints and packaging. The properties of our cellulose-based pigment are attractive because they are likely to comply with future regulations. In addition, the cellulose can be sourced locally from other cellulose-rich sources such as agricultural and food waste, providing a short and resilient supply chain and a significantly reduced carbon footprint.
Key needs to ensure further uptake and success
It was a challenge to optimise the scale-up on the roll-to-roll machine and we need to find a new machine. The roll-to-roll machine we were using was not optimal. So, we have to find new manufacturers and define a new configuration to make the process economically viable. The cost is still too high. We see the need to increase the throughput of the machine. Our strategy is to use a machine with a wider web to double production at the same speed.
The pigments we develop deliver colour intensity and sparkle, and because they are made entirely from cellulose, they offer the competitive advantage of being biodegradable, while eliminating the concerns associated with other products. They can directly replace large plastic-based glitter used in textiles and housewares, and compete with highly processed and problematic titanium dioxide and mica-based effect pigments used in cosmetics, food, paints and packaging. The properties of our cellulose-based pigment are attractive because they are likely to comply with future regulations. In addition, the cellulose can be sourced locally from other cellulose-rich sources such as agricultural and food waste, providing a short and resilient supply chain and a significantly reduced carbon footprint.
Key needs to ensure further uptake and success
It was a challenge to optimise the scale-up on the roll-to-roll machine and we need to find a new machine. The roll-to-roll machine we were using was not optimal. So, we have to find new manufacturers and define a new configuration to make the process economically viable. The cost is still too high. We see the need to increase the throughput of the machine. Our strategy is to use a machine with a wider web to double production at the same speed.