Additives/Masterbatches Colour and Additive Solutions for While the total market for bioplastics is still relatively small compared to the overall plastic market but for anyone working with bioplastics in any form, there are a wide range of options when it comes to colourants and additive masterbatches. These range from standard pigments and additives, tested and certified pigments and additives and wholly natural pigments and additives. All have their advantages and disadvantages depending on whether we are talking about bio-identical standard resins (polymers that are made from renewable resources but which have properties identical to fossil-derived plastics, also referred to as drop-in bioplastics), true biopolymers (made from biobased monomers and such that are biodegradable or compostable) or fossil fuel based biodegradable or compostable plastics. With bio-identical resins, adding colour and additives is straightforward. Because they are chemically identical to fossil-derived materials, they are recyclable with and have an afterlife similar to conventional plastics. Therefore, conventional additives and pigments can be compounded into a bio-identical carrier resin and used in exactly the same way they would be with standard resins. Their environmental impact is the same. For degradable or compostable polymers like polylactic acid (PLA), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), starch-based biopolymers (like Mater-bi ® from Novamont), and other less common biopolymers, the situation gets a little more complicated because users have a number of options available to them. COLOR MASTERBATCHES For coloring PLA, Clariant offers the RENOL ® -bl range of color masterbatches using conventional pigments in a PLA carrier resin, so they are also biodegradable. Fifteen standard colors are available and custom colors can be formulated as well. They offer good light-fastness and have heat resistance up to 240C, making them suitable for processing with PLA. A more limited range of colors is available for Materbi and PHA. These RENOL-ba masterbatches are also formulated using conventional pigments and a biopolymer carrier resin. The colors for Mater-bi were developed in close collaboration with Novamont. For biopolymer users who want a 100 % natural color solution, Clariant offers the RENOL-natur family of masterbatches made with pigments derived entirely from nature. RENOL-natur colours are very earthy and organiclooking, some with excellent clarity, and the variety of colours available includes red, orange, yellow and green. Natural carmine red colourants are derived from the cochineal insect. Orange curcuma comes from the root of the spice plant turmeric, and yellow urucum is found in flowers that grow in tropical regions like Brazil. The greens come from chlorophyll and other plant sources. These colours can be combined to create additional shades and tones. Physical properties, such as lightfastness, are not as high as would be expected from non-renewable pigments or dye, so they are not suitable for all projects. Finished articles made with the Clariant RENOL-natur are biodegradable according to the EN 13432 standard. Some grades are also industrially and home compostable. More about compostability see below. Additive Masterbatches For improving the properties of biopolymers, as well as adding functionality, Clariant offers CESA ® -brand additive masterbatches that can add value to and improve the performance and handling of biopolymers. As with the pigments discussed above, these masterbatches are formulated using standard active ingredients in an appropriate biopolymer carrier resin. They include: • Light stabilizers that protect the polymer by efficiently absorbing UV-radiation, which is very important in applications like agricultural film. They can also protect the contents of packaged goods. • Anti-blocking agents prevent adhesion between layers of film to aid in unwinding and also make it easier de-nest and handle thermoformed articles. • Chemical foaming agents (endothermic) are used in the production of foamed sheets used to form food trays. • Melt stabilizers or chain extenders help prevent degradation of intrinsic viscosity during processing of PLA and are often used to improve the process stability during extrusion of foamed sheets. • Nucleating agents can be used to control the clarity of the biopolymers and to increase stiffness and flexural modulus. Nucleating agents are also used to control the size and uniformity of the cells in foamed material. • Impact modifiers reduce brittleness and anti-static agents minimize the build-up of static electricity that can result in handling difficulties and dust accumulation. 14 bioplastics MAGAZINE [03/20] Vol. 15
Additives/Masterbatches Bioplastics By: Jan Sueltemeyer Global Head of Innovation & Sustainability Clariant Muttenz, Switzerland As with the colourants, there are natural alternatives to the standard ingredients and these are offered in CESAnatur masterbatches. Beeswax, for instance, can be used as a slip or anti-blocking agent. A molecule extracted from fruit, when used in high concentrations can provide UV protection, and plant-derived antistatic agents are also available. Vitamin E is a naturally occurring antioxidant. OK Compost certification Most biopolymers can be composted in industrial facilities and some also break down in home composting heaps, but at a much slower rate. However the artificial pigments and additives that may be used in bioplastics do not break down, leading to concern about heavy-metal content and possible plant toxicity. For this reason several standards (i.e.: EU Packaging Directive (94/62/EEC) and EN 13432:2000) have been put forward to regulate, among other things, the quality of resulting compost. It is also the reason for the creation of the OK compost certification program administered by the TÜV AUSTRIA Belgium testing organization. Recently, Clariant RENOL-compostable colour masterbatches and CESA-compostable additive masterbatches were awarded OK compost HOME and OK compost INDUSTRIAL labels by TÜV AUSTRIA Belgium This means compostability is guaranteed not only in industrial composting plants, but also in home garden compost heaps, where conditions are less controlled. To comply with the applicable standards, the Clariant OK compost masterbatches use only non-toxic and and the amount of colourant or additive used in a given volume of plastic is strictly limited. Available carrier resins include PLA and Mater–bi. A total of ten OK compost certified standard colours are available and custom formulations are available. CESAcompostable additives include UV/light stabilizers, slip/antiblock agents, anti-static agents and optical brighteners, among others. Part of the certification process requires that plants making certifiable masterbatches institute strict process and quality control procedures and that an OK compost Officer be named. He is responsible for conformity of production and has the authority to deal with the corrective actions in case of nonconformity. Five Clariant plants have qualified. Products made at Clariant plants in Poliagno, Italy, and Sant Andreu de la Barca, Spain, initially received OK compost INDUSTRIAL certification in 2012 and the latest testing adds the more challenging OK compost HOME label to their products. In addition, plants in Ahrensburg and Lahnstein, Germany, can now make masterbatches that are compliant with both standards. The Clariant plant in Phanthong, Thailand, can now supply OK-compost-labeled masterbatches to Asian customers. www.clariant.com bioplastics MAGAZINE [03/20] Vol. 15 15
