On November 13, China Ministry of Industry and Information Technology issued “Limit of Harmful Substances in Wood Coatings” and other 8 compulsory approval and publicity in accordance with national standards in chemical industry. The new national standard will put forward higher requirements for VOCs emission of polyurethane coatings, adhesives and other industries. On November 13-15, at the “Fifth Scientific Research and Technology Exchange Conference of Waterborne Polyurethane” hosted by China Polyurethane Industry Association, experts in the industry believed that with the continuous improvement of environmental protection requirements such as VOC emission, the waterborne polyurethane will have a positive and new development market. 

A professor in Anhui University of China, said that at present, the proportion of waterborne polyurethane in polyurethane industry in China is very small. In 2018, the output of polyurethane in China is about 11 million tons (equivalent to pure solid content), and the output of waterborne polyurethane is about 100000 tons, including 30000 tons of equivalent pure solid content. However, waterborne polyurethane is a very important product. In recent years, due to the improvement of environmental protection requirements and awareness, China's waterborne polyurethane industry has developed rapidly, with the growth rate far exceeding the overall polyurethane industry. From the initial leather coating to textile coating, synthetic leather slurry, wood coating, industrial coating, automobile coating, polyurethane condom, the application field of waterborne polyurethane has been expanding and the technical level has been continuously improving.

Strict environmental supervision has opened up a new development space for waterborne polyurethane materials. It is necessary to strengthen the source control and accelerate the use of water-based coatings with low VOCs content instead of solvent based coatings, including coatings for automobile manufacturing, steel containers, wooden furniture, engineering machinery, electronic products manufacturing, and water-based adhesives for soft furniture.

In the announcement of 8 compulsory national standards for the chemical industry issued by China Ministry of Industry and Information Technology, 5 standards, i.e. the Limit of Volatile Organic Compounds in Adhesives, the Limit of Harmful Substances in Industrial Protective Coatings, the Limit of Harmful Substances in Building Wall Coatings, the Limit of Harmful Substances in Wood Coatings and the Limit of Harmful Substances in Vehicle Coatings, are all related to the polyurethane industry. "These mandatory standards are not far from being formally implemented. These measures are also intended to further limit VOCs emissions in the chemical industry, and will also bring new development opportunities to polyurethane waterborne materials. " Han Baole, Deputy Secretary General of China Polyurethane Industry Association, said.

Cui Yanjun, deputy director of the special committee for waterborne materials of Polyurethane Association, said that there are many kinds of waterborne polyurethane products, including adhesives, coatings and leather resins. With the introduction of mandatory standards, a number of enterprises will face transformation and upgrading. Taking coating enterprises as an example, it is estimated that 70% - 80% of the enterprises can meet the new national standard to be implemented, and 20% - 30% of the enterprises are not up to the standard, so they must meet the policy requirements through environmental protection upgrading such as water-based.
 
However, at present, the development of waterborne polyurethane also faces some technical problems to be solved.  Solvent is still used in most of the production processes of water-based polyurethane dispersion at present, resulting in the problem of solvent recycling. How to reduce the amount of organic solvent and realize the green production without solvent through the research and development of new synthesis process and raw materials is an important research topic in the development of waterborne polyurethane materials.

In the synthesis process of waterborne polyurethane, solvents are used to help dissolve reactants, reduce the viscosity of prepolymer and help dispersion. The synthesis of waterborne polyurethane requires high performance of solvent. The solvent must be inert and miscible with water. It has good dissolving ability for reactants and products, and its boiling point should be within a certain range. At present, acetone and other solvents are needed in the synthesis of waterborne polyurethane, which are inflammable and explosive dangerous goods, and are limited in the process of production and transportation. Therefore, it is urgent to develop new nontoxic and safe solvents.

Although the VOC emission of waterborne polyurethane is low in the process of application, it often produces more waste gas and residue in the process of synthesis and use than solvent products. How to reduce the discharge of "three wastes" is also an important issue in front of the waterborne polyurethane industry.

Among the four water-based resins, epoxy, acrylic, alkyd and polyurethane, polyurethane has certain advantages in performance, but its application proportion is still low. In fact, China's waterborne polyurethane materials research time is relatively long, there are many good technologies. At present, the main problem is the lack of high-end raw materials. For example, the high-end curing agent, special polyol, aliphatic isocyanate and other raw materials required for water-based materials, due to the high technical threshold, many of them are foreign patented technologies, which restrict the development of the industry. We have a large market for downstream applications, so we have a rapid development, but at present, we lack of Chinese brands. Most of our polyurethane brands are concentrated in the upstream.
The industry needs to further carry out more basic research on the film-forming mechanism of waterborne polyurethane dispersion, and improve the corresponding supporting systems, including equipment and additives, etc.
 
OKCHEM Verified Suppliers in Polyurethane and Coatings:

QINGYUAN JIAXIN PAINT CO. LTD

Ningyang ZhongWei Chemical

Hangzhou Ruijiang Performance Material Science Co., Ltd

Hebei Guanlang Biotechnology Co., Ltd.

Guangxi Bluestar Dahua Chemical Co., Ltd.

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