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Sustainable colouring of bio-based, home-compostable polymers
More and more manufacturers and brands are declaring bio-based, home-compostable polymers as the benchmark when it comes to research and development for solutions as part of their sustainability strategy.
Helmut Nägele and Jürgen Pfitzer, Managing Directors at TECNARO, and Marco Meixner, Head of Research and Development at LIFOCOLOR FARBEN, take a close look at the reasons for this in addition to examining the associated demands on colours and additives.
The international debates surrounding the environmental impact of the use of polymers are multifaceted and are very much in full swing. Along the entire supply chain, the aim is to increase recycling rates, reduce microplastics and increasingly transform single-use goods into reusable products. In addition to efforts to create polymers as a material base that has been and can be recycled, it is becoming increasingly important to avoid fossil-based raw materials in light of continuously rising CO2 emissions and the associated climate change as well as the ever-increasing scarcity of resources.
An organic recycling system requires a renewable basis
“For many companies, the view of the circular economy within the polymer supply chain is becoming more and more nuanced. A renewable raw material that degrades in the most environmentally-friendly way possible, in line with the idea of ‘putting back into nature what you took out’, is the ultimate ideal in the sustainability reports of various stakeholders”, explains Helmut Nägele, Managing Director at TECNARO GmbH. The expert in technologies for the industrial use of renewable raw materials in polymer processing (TECNARO) specialises in the development, production and distribution of organic-based biopolymers and biocomposites.
The advantage of reducing CO2 emissions
It’s not only this closed-loop concept that is leading to an increasing demand for biodegradeable components. Another advantage of a regenerative, renewable basis which is completely biodegradable, such as that of lignin, cellulose, sugar, vegetable oils and starch to name just a few, is the reduced carbon footprint in the end product. “Substituting the use of fossil-based polymers is an effective way for manufacturers to take a big step towards achieving their goals for CO2 reduction. Politics currently has its own way of providing appropriate incentives in this regard in the way it sets CO2 prices. For example, in contrast to petroleum-based variants, with our materials, the only CO2 that is released at the end of the product life cycle during the combustion or composting process is that which was previously removed from the atmosphere through photosynthesis”, Nägele explains.
Political guidelines are on the increase
Another political aspect comes into play here, with the EU Directive on single-use plastic (2019/904), the planned Regulations of the European Chemical Agency (ECHA) to prevent microplastics from being released into the environment and other European projects such as the Green Deal aimed at developing the society and the economy in an environmentally sustainable way for the coming decades, fossil-based polymer goods are once again coming under scrutiny. There are, however, already statements and review papers which argue for exemptions from restrictions and bans on certain bio-based biopolymers, referring to very strict criteria of complete biodegradability in the open environment, i.e. at least under home-composting conditions at ambient temperature.
High-quality biopolymers established on the market
Like TECNARO with its ARBOBLEND® types, other polymer manufacturers have also established variants on the market which also have very good technical properties despite their resistance to microorganisms, in addition to a basis made of 100% renewable, organic materials and being degradable under home-composting conditions. These include variably adjustable rigidity and viscosity, high impact resistance, heat resistance and food conformity, among others.
In light of the circumstances mentioned above, the polymer supply chain must also consider the aforementioned polymer types in its strategies. As with the recycling topic in general, proper disposal, reprocessing and further scaling of degradable biopolymers must of course also continue to be developed. This can and will make these biopolymer concepts even more relevant for product applications with a short life cycle and representative for a sustainable alternative in all aspects.
All aggregates must meet the highest standards
A bio-based, home-compostable raw material is an important basis for polymer products. However, an entire product can only meet the highest standards for degradability and recycling if all its components meet the same standards. This is now a field of activity at the masterbatch manufacturer LIFOCOLOR, with a significantly increased share. The group designs and manufactures tailor-made masterbatches, additive batches and combi-batches, including for applications made of biopolymers. “We strive to develop products from bio-based, degradable polymers as this is a strategic and conceptual goal for us. In every respect, we want to supply needs-based and highly sustainable colours in order to optimise the circulation of materials”, explains Marco Meixner, Head of Research and Development at LIFOCOLOR FARBEN.
A particularly environmentally-friendly range of colourants
To meet the requirement of degradability under home-composting conditions, the selection of pigments and ingredients must go beyond the DIN 13432 standard, which sets the guidelines for industrial composting. The trend colour series Color Road 2022 was launched mid of last year as a pilot project for an initial standard colour palette. The colourants for the bio-based, home-compostable carrier polymer from the TECNARO range have been selected according to adequate criteria of their chemical composition. This means that all colourants decompose into water, carbon dioxide and organic biocompatible molecules or minerals under home-composting conditions. As a result, no toxic or contaminating components are released into the natural environment, as is the case when the suitable material itself decomposes. Under these conditions, the entire end product can be successfully certified with regards to home-compostability (such as via OK Home Compost, DIN CERTO).
The project and the standards of the bio C master batches, as they are called (C for compostable), show that biodegradable polymers can even be coloured to match the latest trends. Biodegradable doesn’t have to look boring, on the contrary: sustainability and trend colours go together perfectly. Polymer colouring which also aspires to be degradable in ambient temperatures no longer needs to be limited to dark and dull colour spectra.
Trend shift towards more brilliance and colour variety
The trend shift in terms of colour variety and brilliance can be attributed in part to more optimal raw materials available on the market. Light or transparent biopolymer types from the TECNARO portfolio, among others, offer ideal possibilities for colouring. The darker the raw material, the more challenging it is to achieve the right intensity of certain colour spectra, and higher concentrations also increase the costs of colouring. Colourant manufacturers have continued to successively optimise their portfolios, which also constitutes a driving progress in this area. More detailed information on limits and selections based on composting standards are giving a positive boost to the options for development and solutions for masterbatches. Certification of raw materials and colourants, for example according to “OK compost”, helps suppliers such as LIFOCOLOR to set even clearer standards for biodegradable masterbatch compositions in the future.
More colourants based on renewable resources in demand
“Of course, there are still challenges: We always have to adapt our master batch products to the need and desire for a base that is completely organic and degradable without impairing the basic properties of the biopolymer while possibly even improving its functionality or stability”, explains Marco Meixner. “In the additive sector, there are already equally comparable solutions, even if the synthetic components are still significantly more diverse in every respect. Here, we also continue to rely on the innovative strength of our suppliers, i.e. manufacturers in the polymer, colourant and additive sectors, to also drive forward our continuous research.” More and more brand-name companies are voicing their requests for colourants to also be produced increasingly on the basis of renewable raw materials in the future. “This is the next step for a colour concept that fits in with a closed-loop economy in the organic sector”, says Marco Meixner, “we are pursuing innovations in this area at full speed over the next few years”.
 European Commission, Research and Innovation (December 2020). Biodegradability of plastics in the open environment. Last accessed 5 July 2021, from https://ec.europa.eu/info/publications/biodegradability-plastics-open-environment_en.
To show the possibilities for colouring biopolymers, Lifocolor for the first time designed its trend colour series in 2022 specifically for colouring home-compostable biopolymers.
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