Bio-based Resins for Sustainable Coatings
Why is the market leaning toward bio-based materials?
Rising temperatures and declining sea ice figures are now providing irrefutable evidence for global warming. Seven of the ten hottest years on record have occurred in the last decade (2009-2018). Arctic sea ice area has set new record lows for April, May, July and August in 2019. As a result, consumers and producers expressing the need to accelerate move towards a greener global economy. Greater demand for sustainable systems and increasing carbon-footprint sensitivity are increasingly turning consumers and manufacturers away from fossil fuel based ingredients and towards sustainable solutions. The coatings industry is going through the same general transition.
What are bio resins?
The search for greener options has led manufacturers to closely examine their formulations. A coating formulation consists of several major ingredients (depending on the application):
- Resin (Binder)
- Liquid (Solvent or Water)
- Pigments
- Additives
Resins have generally been identified by industry experts as having the greatest potential for replacement with bio-based solutions. Bio resins are, partially or completely, based on monomers which are derived from biological sources. These resins have green appeal as they replace petrochemical based ingredients with plant-based alternatives. The most common plant sources for the production of bio resins are corn and soybean by-products from bio-diesel refinement. Other sources include potatoes, sugarcane, sugar beets, castor beans, lignocellulose, cashew nut shells, algae and whey. Use of bio-based raw materials in coatings is not a recent development. Their use actually pre-dates the use of petrochemicals. Today however, majority of paints and varnishes produced are based on fossil raw materials. The situation is now set to change. Bio resins, which were a novelty only a few years ago, are fast moving into the mainstream.
Bio-based resins are fast gaining importance in the coatings industry
A survey of 160 experts in the coatings industry was conducted by the European Coatings Journal (EC) in 2019. The study reveals interesting trends regarding transition to bio-based resins.
Results show that bio-based raw materials are gaining importance in the coatings market at an increasing pace. About 77% of the respondents believe that bio-based coatings are now more important for their business than they were five years ago. |
Source: European Coatings Journal
|
What factors are driving the change?
|
Consumer demand
Coating manufacturers, raw material producers and distributors all agree that the end-user demand in the business-to-consumer (B2C) market is expected to outpace push for bio-based coatings in the business-to-business (B2B) market.
This means that consumer demand for a greener product is expected to drive manufacturers towards greener ingredients. According to the 2018 climate action research report by IKEA, ‘nearly 90% of people say they are willing to change their behavior to help fight climate change.
|
Source: European Coatings Journal
|
|
Environmental Regulations
The EC survey also reveals environmental regulations as the second most important driver of this transition. Environmental and safety regulations are becoming increasingly stringent globally. Coating manufactures must, therefore, carefully preplan their move towards greener and safer products. Air pollution is now the world's leading environmental threat to public health. It accounts for about 7 million deaths around the world every year. According to a 2014 Institute for Health Metrics and Evaluation estimate, two-thirds of all life-years lost to environmentally linked deaths and disabilities are attributable to airborne pollutants. Air pollution Issues are even more acute in rapidly industrializing nations such as China and India. To deal with these issues, governments, world over, are setting limits on levels of emissions and Volatile Organic Compounds (VOC).
|
Source: European Coatings Journal
|
| The EU directive 2004/42/EC sets the maximum permissible content of VOC’s in paints, varnishes and vehice refinishing products. VOCs can contribute to several health problems when inhaled, including irritation in the airways, nausea, headaches, and may cause damage to the kidneys, liver, or the nervous system. The US environmental protection agency (EPA) has also mandated the VOC limits for a wide range of consumer products. Several US states have draft even more stringent VOC content limits than the EPA. |
Health Concerns
Consumer preference for low emission coatings emanates not just from concerns about the planet but also from concerns regarding their own health. People want to breathe cleaner, healthier air both outside and inside their homes. Consumers are increasingly concerned about the harmful substances that interior paints may release into their homes. These substances can be inhaled into the airways which may lead to deterioration of health over time. According to the findings of a 2019 USP market research on behalf of DSM, consumers are concerned about harmful emissions when painting interiors especially children rooms. Consumers and painters agree that personal safety is the most appealing recent innovation in wall paints. Consumers have a growing preference for buying paints containing bio-based material which are perceived as healthier and environment friendly.
Consumers are concerned about harmful emissions when painting interiors especially children rooms.
Like consumers, also painters increasingly express their preference to work with wall paints which are free of toxins and lower the risk to their health. An increasing proportion of painters are reporting that customers ask them to use environment-friendly paint products for their jobs. A majority of painters across Europe acknowledge that they pay attention to eco-labels when buying paint products. Preference for solvent-free paint products is also growing across Europe. An increasing number of home-owners ask their painters to use solvent-free paint products. The painters themselves are also showing greater preference for solvent free products.
Towards sustainable paint technology
Whether solvent-borne or water-borne, most coatings today are largely made from fossil sources. Water-borne coatings already represent a step in the right direction, as they replace the solvent content with water reducing the fossil-based content of the coating. Formulating coatings with bio-based binders further reduces the fossil-content of the coating by replacing the petrochemical based resin with a bio-based alternative.
The bio based content of a material can be determined using a method called carbon dating. This method measures and compares the ratio of Carbon 14 (C14) to Carbon 12 (C12) in the material. Material derived from recent biological matter has a higher ratio of C14 to C12 than material obtained from fossil sources such as coal and oil. Use of these bio based resins can help paint manufacturers reduce their carbon footprint.
Manufacturers are continuously searching for more cost-effective ways of converting bio products into the monomers required to build a resin. To facilitate the transition to more sustainable products, resin manufacturers offer bio-based resins as drop-in substitutes for petro-based products currently in use. Generally, these bio resins are carefully designed so they require little or no adjustment in product formulation and offer comparable performance. More sophisticated bio-based resins however take benefit from novel (bio)chemistry and monomers, which may require additional formulation effort but carry the reward of new product properties which may open doors to new markets and applications.
Performance of bio resins
The increasing emphasis on bio-based materials arises as much from responsible manufacturers looking to reduce their ecological footprint as from regulations requiring minimum bio-based content in finished products. Manufacturers are also looking to benefit from government incentives on the use of renewable resources. In addition, bio-based materials offer consistent availability, and do not show the same price volatility as exhibited by oil and its derivatives. These incentives are convincing coating manufacturers to seek bio-based alternatives which can meet or exceed the performance of traditional coating technologies.
Alkyds are the oldest bio-based resins used in the coatings industry. Solvent-borne formulation of alkyds, however lead to high fossil based VOC content in the product. Stricter air pollution regulations and increasing awareness of health hazards necessitate use of lower VOC alternatives. Coatings based on alkyd resins undergo a yellowing process with time. The problem is compounded in paints with higher solid content and severely affects the appearance of whites, light colors and clear coats. Water based acrylic coatings reduce the VOC content and are non-yellowing. Acrylic waterborne paints, however, derive a major proportion of their resin component from petro based sources.