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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