Recommendations and prospects for VOC testing methods in coatings

China Paint Network
: In recent years, China frequently occurred large-scale persistent haze weather, about 1/4 of the land area, 600 million people affected, air pollution prevention and control work situation is serious. PM2.5 in ambient air mainly comes from two aspects: first, direct emissions, and second, secondary particulate matter. VoC, as an important secondary particulate matter, has a great influence on the formation and regional distribution of haze.
coating
is the key industry in the air pollution prevention and control plan, and its VOC emission is an important source of PM2.5. Increasing the control of VOC in coatings is very important for the prevention and control of air pollution, and how to define VOC in coatings and accurately determine its content is a subject that analysts have been studying and discussing.
the status quo of the 1 VOC
at present, there are many international definitions of VOC.
World Health Organization (WHO): Volatile organic compounds with a melting point below room temperature and a boiling point of 50 to 260 degrees C
International Organization for Standardization (ISO): Any organic liquid or solid that naturally evaporates at normal temperature and pressure in the environment

Volatile organic compounds with a boiling point of up to 250 degrees C at 101.3kPa standard pressure
China: At 101.3kPa standard pressure, any organic with an initial boiling point below or equal to 250 degrees C When
the VOC content was determined by gas chromatography, the markers of chromatography were used as hexyethyl disethylate with a boiling point of 251 degrees C or xylurane with a boiling point of 252.6 degrees C. As to whether the VOC definition of our country is more scientific and reasonable, it is still to be discussed and studied by our peers.
2 the status quo of VOC testing methods in
with the definition of VOC, there will inevitably be a need for VOC content test methods. At present, the opinions on VOC testing methods at home and abroad are relatively uniform, that is, under the prescribed conditions, the content of volatile organic compounds in the coating is measured. The concept of "conditions specified" here is broad, so this is one of the most important concerns in the industry. ISO11890 states that "the nature and quantity of compounds to be considered will depend on the field of coating application", i.e., for different applications of coating products, the determination of VOC content or its calculation methods and limit values should be determined by regulation or mutual agreement. In this regard, China's paint product standards and VOC measurement method standards have been in the forefront of the world.
In order to increase the proportion of china's national standards in the adoption of international standards and timely track international standards, so that China's basic standards in line with international standards, under the leadership of PetroChina (12.51, 0.00, 0.00%) and the Chemical Industry Federation, the Secretariat of the National Technical Committee for the Standardization of Coatings and Pigments In 2009, the organization completed the "VoC content determination in paint" series of 3 national standards, namely: GB/T23984-2009 "color paint and varnish low VOC
latex paint
Determination of the content of volatile organic compounds (VOC in tanks), GB/T23986-2009 Gas chromatography of the content of color paint and varnish volatile organic compounds (VOCs) and GB/T23985 -2009 Measured difference between color paint and varnish volatile organic compound (VOC) content, applicable to VOC content of 0.01% to 0.1%, 0.1% to 15%, >15% respectively three parts of the coating system. This series of national standards systematically improves and perfects the test standard system of VOC content in China's evaluation coatings, and makes China's paint VOC content testing technology into the ranks of the international advanced level.
In recent years, the National Technical Committee for the Standardization of Coatings and Pigments, in order to promote the low pollution of coatings in China, from the health considerations of maintaining the production, construction and use of coatings, from the maintenance of the living environment and natural ecology, put forward a series of standards, such as GB18582. -2008, GB24613-2009, GB24408-2009, GB24409-2009, GB24410-2009, etc. These standards limit the content of VOC in a variety of coatings, and establish a number of VOC testing methods, for the later development of other similar product standards or method standards laid a technical foundation.
3 VoC test methods in coatings outlook
With the development of China's coating technology and environmental protection regulations increasingly sound, more and more environmentally friendly coating products, VOC content in coatings will be lower and lower. At the same time, with the development of modern test equipment and instruments, coating detection technology is constantly updated, voC testing methods in coatings will have new requirements. In order to adapt to the future development, China also needs to constantly improve the VOC testing method standards, for all types of users in quality management, market supervision to provide a more scientific basis, so it is recommended to develop some more in line with the actual situation of the coating industry VOC content testing methods.
3.1 Establish a method for determining the VOC content released into the air by coating film - environmental cabin/gas chromatography coatings release VOCs into the air during production and construction, and cause harm to the environment and the health of production and construction personnel. When coatings are filmed, VOCs are released into the air during the drying process and for a period of time after drying, which continues to cause harm to the environment and consumer health. At present, the coating industry at home and abroad are basically using voC method to determine liquid coating products, and the coating film rear discharge VOC measurement method and standard has not been established. In this regard, China's environmental monitoring and building materials industry has developed a series of air quality or air purification standards, such as: GB/T2761-2006, GB/T11737-1989, JC/T1074-2008, HJ583-2010, HJ584-2010, etc., but these standards are the entire indoor environment voC content monitoring, but not as one of the indoor building materials products in the actual contribution of paint products in VOC independent analysis and testing, resulting in ordinary consumers often think that paint is the main culprit of indoor environmental pollution, which may have been misunderstood for many years. At present, a very small number of countries in the world have begun to use VOC release as a test of the environmental performance of coatings standards, the most representative of which is Finland "M1 certification", is also the world's most stringent and most stringent product certification standards.
For coating consumers, it may be more concerned about the VOC varieties and content released into the air after coating film, so it is necessary to develop a coating film release into the air VOC content measurement method - environmental cabin / gas chromatography.
3.2 Establish a method for determining the content of "inert VOC" in coatings - gas chromatography traditional coatings in the production and construction process, the need to add solvents or thinners, making it the main source of VOC in the coating industry. In environmentally friendly coatings (e.g. photo-curing coatings, high solids, solvent-free coatings, etc.) systems, reactive solvents, commonly known as "active thinners", such as shrinking glycerides or shrinking glyceroe ethers, phenols, etc. for solvent-free epoxy coatings, etc. Multi-official acrylics or methyl acrylics, vinyl esters, vinyl ethers, etc. used in radiation-cured coatings, high-hydroxy polyester or polyethers for high-solid coatings, low-relative molecular quality polyolefins, etc. The vast majority of these active thinners in the coating filming process will participate in the reaction, not released into the air, will not cause pollution to the environment, if still in accordance with the conventional VOC content of the test method to determine is obviously unscientific, not in line with technological progress. In view of this status quo, it is recommended to give those in the coating production and construction process, used to reduce the viscosity of the system or change certain properties of the product, but do not participate in the membrane reaction of volatile organic compounds named "inert VOC", such VOC will be released into the air during the coating filming process.
On January 26, 2015, the Ministry of Finance and the State Administration of Taxation jointly issued a "Notice on the Collection of Consumption Tax on Coatings", which caused widespread concern in the paint industry and bound to make the paint industry pay more attention to VOCs that actually evaporate into the air.