Green coatings: a trend that is becoming the rule rather than the exception

JCT CoatingsTech, Jan, 2008 by Ravi Joshi, Theodore Provder, Konnie Kustron

In recent years, many leading paint and coatings manufacturers have been trying to meet the growing consumer demand for safer and healthier products enabled by strict environmental regulations and government legislations. As a result, there is a growing need in the coatings industry for what is referred to as "green coatings." Several independent certifying agencies (1-7) have evolved over the last 10 years to support this task. These organizations have established their own environmental performance standards and evaluation criteria. Based upon those, these organizations certify a consumer product as eco-friendly or "green." In further support of this movement, in November 2006, the Green Chemistry Research and Development Act of 2005 (H.R. 1215) was passed by the U.S. House of Representatives. (8-11) The bill has been referred to the Committee on Commerce, Science, and Transportation and must be now approved by the U.S. Senate. (8-11) This bill will certainly foster an increasing recognition of green chemistry practices when passed into law. All of the above indicate that the trend towards developing "green" coatings will soon become the rule rather than the exception. This significant need for innovation is mainly driven by continuing regulatory requirements and increasing consumer eco-consciousness.

The goal of this article is to review the impact of government regulations as innovative drivers for a paradigm shift in the paint and coatings market. This analysis is divided into six parts. Subsequent to the introduction, in order to put green coatings in appropriate perspective, a sequential historical overview of the development of coatings technology with respect to environmental regulations is provided. The next section describes how paint and coatings companies responded to the implemented government regulations. This is followed by a section which provides an overview of independent organizations that certify a coating as "green." The following section summarizes current initiatives by the government for a green revolution and discusses the international scenario and sustainability issues of green coatings. Lastly, the final section focuses on the future of green technology.

HISTORICAL OVERVIEW

Paint and coatings technology can be classified as one of the oldest technologies in the history of mankind. (12-13) A historical review (12-13) shows that the Egyptians and many of the ancient Asian and European cultures used to mix raw natural pigments (for example, turmeric) with plant oil or egg-yolk for decorative as well as protective purposes.

Extensive literature reviews (12-16) show that the business of paint manufacturing began in the U.S. in early 1900s. In general, a paint formulation incorporates (1) pigments and/or extenders to impart color, opacity, and sometimes a few other properties such as corrosion resistance; (2) binders (to disperse pigments or extenders), considered as the "engine" of coatings mainly contributing to physical, mechanical, and chemical properties; (3) additives, added in a relatively small amount of the total formulation, which significantly affects the final performance properties; and (4) solvent, which makes a paint or a coating flow over a substrate and once the paint film is formed, evaporates; thus, may contribute towards volatile organic compounds (VOCs). (12-16)

Prior to 1960, there were few regulations or laws that specified or restricted the use of toxic substances or the amount of volatile organic solvents in formulating paints. For example, lead pigments that are toxic in nature and hazardous to human health, were used without any regulations or mandated limits in commercial paint manufacturing until 1960. (17) Another example involves VOC levels: when a gallon of paint was used to coat a surface, approximately 900 grams of VOCs were released into the atmosphere. (18) When exposed to sunlight, these VOCs contributed to the formation of smog. These compounds have been defined by the Environmental Protection Agency (EPA) (19) to include "any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions." (19)

The above and many more similar examples started to raise concerns about product safety, health, and environmental friendliness. Those fears generated a need to develop regulatory standards for consumer paints. In 1978, the Consumer Product Safety Commission (CPSC) (17) came into action and issued a regulation to restrict the use of lead pigment in commercial paint manufacturing. Prior to this in 1966, Rule 66 was promulgated by the Los Angeles Air Pollution Control Department (LAAPC) regarding VOC emissions. (20) Rule 66 was among the first regulations in the country regarding VOC emissions. (20) Since the passing of Rule 66, the federal government enacted the Clean Air Act in 1967 and established the Environmental Protection Agency (EPA). (19) The purpose of the law was to regulate the use of "toxic air pollutants which were hazardous to human health or the environment." (19) The Clean Air Act was amended in 1977 and again in 1990. (19) From the coatings industry perspective, by enacting the Clean Air Act, the government tightened the limits on the use of VOCs in paint formulations. In the second major amendment to the Clean Air Act, the Federal government "included a list of 189 toxic air pollutants for which emissions must be reduced." (19) Further, the law stated that the EPA had to publish a list of source categories within a year after the law was passed. The list of source categories (19) was based upon the source's emission levels of the toxic air pollutants. The list included "the major sources emitting 10 tons/year of any pollutant or 25 tons/year of any combination of those pollutants." (19) This directory also included geographical area sources. Any area source, whether large or small (such as a dry cleaning business), was included in the list. The EPA also issued "Maximum Achievable Control Technology" (MACT) standards for each listed source category according to a prescribed schedule. (19) These standards were based on the "best demonstrated control technology or practices within the regulated industry." The law also mandated that all controls had to be achieved within 10 years of its enactment. The law granted an extension of six years for meeting MACT requirements to "companies that voluntarily reduced emission according to certain conditions." (19) The EPA also classified a list of compounds that were exempted from the Clean Air Act or VOC regulations. (17) These compounds, even though they are carbon-based, have been exempted based upon their "negligible reactivity" towards smog or ozone formation. This list is known as the "VOC-exempt list" and can be found on the EPA website. (19)