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Building a Sustainable Coatings Infrastructure

By Madison J. Sloan, L. Elise Matolyak, and Rebecca Chen, PPG |

Recent advancements in coatings technologies are driving the industry toward more sustainable performance

Globally, there has been an increase in the number of chemicals identified as “chemicals of concern,” as well as restrictions on the emissions of volatile organic compounds (VOCs), resulting in new federal initiatives and driving the development of new manufacturing processes. One of the more significant global initiatives for chemical restriction is China’s 13 th Five-Year Plan (2016–2020), which has identified environmental protection as a key objective [ 1]. China’s Five-Year Plan is driving more government regulations involving sustainability and corporate social responsibility, especially in manufacturing processes [ 1]. These regulations have a major impact, specifically for paints and coatings, since solvent-borne technologies will be restricted in China by the end of 2020 [ 1]. Thus, technological advancements in industrial coatings are essential in this environmentally conscious world to support coatings end-users as they make transitions in technology (Figure 1).

The complexity of changing the industrial culture mandates that manufacturers consider how best to implement sustainable coatings systems. As manufacturers are increasingly cognizant of the globalization of products, they are keenly aware of environmental requirements that must be considered. This article covers some industrial developments related to sustainable coatings, as well as methods to facilitate their implementation as an industry standard.

FIGURE 1. Industrial coatings are essential to preserve the lifetime of equipment and infrastructure, and much research and development work is being done to improve their sustainability footprint

Chemistry and formulation

With increasing regulations and heightened awareness about the environmental impact of VOCs, there are a number of innovations within the coatings industry that are focused on improved sustainability. For instance, powder coatings eliminate the use of solvents and have excellent transfer efficiency [ 2]; however, complex shapes and edge coverage can be challenging for powder-based systems. Therefore, the research and development of high-edge powder solutions is imperative to help improve the corrosion resistance of this technology [ 2]. While some coatings technologies, such as powder, high-solids, waterborne and radiation-cure, help reduce the carbon footprint of coatings, each has its limitations. Table 1 gives a brief summary of the coating technologies that can reduce or eliminate VOCs. In this description, a thick coating has a dry-film thickness (DFT) of greater than 50 μm, and a thin coating has a DFT of less than 50 μm. DFT ranges are based on a plethora of factors, including solids content, pigmentation and application parameters.

FIGURE 2. One major area of development in sustainable coatings is waterborne formulations, which present many benefits

One major area of research in the development of sustainable coatings products is waterborne technologies, which span numerous markets and have heightened popularity as a decorative coating opportunity (Figure 2). Waterborne coatings are a versatile option, compatible with many application methods and can be applied at a range of thicknesses and utilized on multiple substrates. The main difference between solvent-borne coatings and their waterborne analogs is the binder system. Solvent allows for resins to be solvated in the coating system and aids in additive and pigment dispersion, as well as coalescence. Waterborne systems mainly consist of dispersions of polymer particles and require a stable colloidal system. While waterborne coatings present a good opportunity as a low-VOC option, many still contain some level of solvent to help with surface tension and pigment dispersion, requiring further research to reduce solvents and regulated materials while balancing additional performance properties. For instance, some basecoats on plastic substrates can suffer from adhesion loss due to the high surface energy of water, reduced wet-out and a lack of solvent to etch the substrate. Several approaches can be used to address adhesion issues, such as resin innovation and formulation tools. Internal resin capability addresses these obstacles by utilizing chemistries to promote adhesion to diverse substrates, choosing surfactants to aid in reduction of surface tension, and fine-tuned crosslinking in both one-component and two-component coating systems. Additional formulation tools to replace solvents, such as flow additives, coalescents and wetting agents, assist in balancing the necessary properties of a waterborne system.

In addition to adhesion, appearance may be a concern with waterborne coatings. Solvent-borne basecoats achieve metallic flake orientation and a high metallic appearance due to the high volatility of solvents and the ability of solvents to disperse flake pigments. Waterborne basecoats can achieve high metallic finishes through careful choice of flake and passivation, rheology control and resin innovation. Even when flake orientation is achieved, it has been historically difficult to balance high metallic finishes and required performance attributes, such as hardness, with waterborne systems. In aqueous metallic basecoats, multiple resins are often utilized to balance both appearance and performance, and additional formulation tools to enhance rheological requirements for flake orientation and stability are utilized. Rheological effects are constantly being researched to overcome a wide range of obstacles, such as pigment dispersion, paint stability and pumpability, as well as application of emulsion-based systems.

 

Sustainable system integration

While many companies have been deeply involved in sustainable coatings innovations, the success of the industry’s transition, however, heavily depends on the effectiveness of total solutions training. Waterborne and high-solids, solvent-borne paint and coatings commonly have different physical properties than their traditional solvent-borne counterparts, which require additional considerations and equipment during processing. In order to reduce the impact on users adopting these technologies, a multi-step process should be developed for seamless conversion. This process includes assessing the raw material and application requirements for the specific paints or coatings being used, the type of equipment required for processing and full system training for the workers responsible for maintaining and applying the paint or coating.

For example, the raw materials that comprise a waterborne paint are very different from their traditional solvent-borne counterparts. This is largely due to the modification requirements and balancing material properties to meet specifications. With the increase in the preference for sustainable products, more waterborne raw-materials suppliers have emerged globally. However, until their supply level matches or exceeds those for traditional solvent-borne systems, suppliers will be forced to work with limited supply and extended lead times. Current suppliers are contributing to researching and developing raw materials for waterborne products, which leads to the higher price when compared with solvent-borne paint. Additionally, if a raw material is not registered in the country where it will be manufactured or used, the paint supplier must work with the purchaser to ensure that all raw materials are properly identified and registered. These factors considered, technological advancements with waterborne coatings are necessary for purchasers to consider and adopt to remain compliant with industry regulations and stay competitive.

Different chemistries and varying line equipment require training and safety precautions tailored to the specific coating technology and equipment being used. In order to provide training and recommendations for lines, it is essential to have a technical understanding of the equipment, its limitations, and how to handle it. The most effective way to accomplish this is to have a dedicated application facility to replicate the manufacturing lines of coatings end users. For example, to identify the appropriate equipment for each program, a mock trial line is set up. Once the coating-spray process and parameters are identified, a user line survey should be performed to evaluate compatibility and make improvement recommendations. In line with the principle of providing more convenience for users, a team should be established to evaluate paints and coatings in advance to increase recognition and trust from users.

Finally, suppliers must consider the different storage requirements associated with waterborne systems. Since waterborne paints are more susceptible to temperature and humidity fluctuations, they must be stored and shipped in containers that will not exceed the liquid temperature limits for water. While shipping and storing require important considerations, so does the disposal of waste. Temperatures beyond the required limits can cause severe quality issues, which can lead to unsalvageable inventory and capacity waste. This requires the use of insulated or cooled containers. All of these upgrades and development processes contribute to capital investments for both the supplier and the applicators. However, by realizing and addressing these areas early on in the transition, all of the parties in the supply chain can align for seamless conversion into the coating market’s sustainable future.

FIGURE 3. A standard lifecycle assessment will highlight the stages that contribute waste of energy, materials or potential sources of environmental impact

Lifecycle assessment

A very effective way for studying the environmental impact of a coating is to perform a lifecycle assessment (LCA). An LCA analyzes the impact at all stages through a paint’s lifetime that impact the environment — from raw material extraction to disposal, as depicted in Figure 3 [ 10]. While it is important to minimize the effects from start to finish, VOC emissions are being targeted the most aggressively in new regulations. In order to better understand how formulation modifications impact the VOC emissions, companies should perform LCAs on their coating materials.

One example of how an LCA is useful in re-formulating paints is shown in Figure 4. This is a comparison of three waterborne basecoats in both red and blue and their influence on greenhouse-gas emissions, ozone depletion and smog production. By doing a side-by-side comparison, we are able to see that by reducing VOCs even by 20%, smog is reduced by almost half of that of the original formulation. Even more, reducing the waterborne basecoat VOCs to 55% shows the greatest impact on environmental pollution.

FIGURE 4. This lifecycle assessment compares three waterborne basecoats, looking at the
environmental impact of varying levels of VOC content

As global trends and consumer demand encourage companies to develop sustainable solutions, it is the responsibility of industry leaders to not only meet the demand, but to pave the way for the entire industry to follow by providing full-service solutions. The road to sustainability begins by developing a fundamental understanding of what changes are necessary. By beginning with the fundamental chemistry required to provide solutions and tracking the changes through lifecycle assessments, great strides can be made.

Building an effective platform to achieve the adoption of more sustainable coatings requires analysis of the total coatings process — from raw materials and the suppliers, to application methods and the modification of production lines. Looking at the total picture and planning ahead are the keys to preparing users and the industry for the implementation of regulations like the 13 th Five-Year Plan. Innovations will continue to improve in order to support the goal of a more sustainable future.

Edited by Mary Page Bailey

 

References

1. The People’s Republic of China, Compilation and Translation Bureau, The 13 th Five-Year Plan for Economic and Social Development of the People’s Republic of China, Central Compilation and Translation Press, 2016.

2. Shaffer, K., Powder Coatings Advanced for Edge Corrosion Protection, Technical paper presented at Coatings World 2019.

3. Schoff, C., Flow Behavior of High Solids Coatings, Proceedings of the Fourteenth Water-borne and Higher-solids Coatings Symposium, pp. 252-277, 1987.

4. U.S. EPA Office of Research and Development, Guide to Cleaner Technologies: Organic Coating Replacements (EPA/625/R-94/006), Washington, D.C., 1994.

5. Kansas Small Business Environmental Assistance Program (KSBEAP), Environmentally Conscious Painting, Wichita, Kan.,1996.

6. Linn, D., Innovation Drives Compact Paint Process for Waterborne Automotive OEM Coatings, Paint & Coatings Industry, Vol. 27, No. 11, November 2011.

7. Waterborne Industrial Coatings, CoatingsTech, Vol. 14, No. 10, October 2017.

8. Eddy, D., A Cure for Improving the Performance of Surface Finishes: UV Coatings are Ideal for Meeting Volume Requirements in the Consumer Products Market while Enhancing the Hardness and Flexibility of Parts, Metal Finishing, Vol. 104, No. 3, March 2006.

9. Schwalm, R., “UV Coatings: Basics, Recent Developments and New Applications,” Elsevier, 2007.

10. Fink, J.K., “Polymer Waste Management — 1.4.6 Life Cycle Assessment,” John Wiley & Sons, pp. 10, 2018.

Acknowledgements

The authors would like to thank Marchers Liu, Hongyi Sun, Eric Lama and the Color Design Studio of PPG Industries for their valuable input.

Authors

Madison J. Sloan is a global strategic account manager at PPG (msloan@ppg.com). She works in the consumer electronics division of the Industrial Coatings segment. Her work revolves around the development and integration of sustainable coatings into the consumer electronics market. Prior to her current role, she worked in the research and development segment of PPG developing coatings for consumer electronics. Sloan holds B.S. and M.S. degrees in chemistry. While earning her M.S., Sloan conducted research on biomimetic devices for the degradation of industrial waste-stream components.

 

 

L. Elise Matolyak is a senior research chemist at PPG (matolyak@ppg.com). She began her career at PPG in 2017 after earning her Ph.D. in macromolecular science and engineering from Case Western Reserve University. Matolyak’s work focuses on waterborne coatings and structure-property relationships with an emphasis on design for regulatory needs. Her work has spanned many business sectors, such as industrial, electronic materials and automotive.

 

 

Rebecca Chen is a marketing and project executive at PPG (rebecca.chen@ppg.com). She works in the consumer electronics division of the Industrial Coatings segment and has six years of experience within that industry. Her work revolves around discovering low-VOC, environmentally friendly coating solutions. She also specializes in marketing communication and product promotion. Chen received her M.B.A. from Tongji University’s School of Economics and Management (Shanghai, China).

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