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Yuan Lei tells you | Waterborne Polyurethane Coatings

Release time:

2024-01-29 09:35

 

Yuan Lei tells you | Waterborne Polyurethane Coatings

 

waterborne polyurethane coating

 

Waterborne polyurethane coating is a kind of coating with waterborne polyurethane resin as the base material and water as the dispersion medium. Waterborne polyurethane coatings modified by crosslinking have good storage stabilityqualitative, coating mechanical properties, water resistance, solvent resistance and aging resistance, and similar to the performance of traditional solvent-based polyurethane coatings, is an important development direction of waterborne polyurethane coatings.





Development history of waterborne polyurethane

In 1967, polyurethane emulsion was industrialized for the first time.

In 1972, Bayer took the lead in using polyurethane water emulsion as a leather finishing agent and began mass production.

In 1975, a high-performance polyurethane emulsion was obtained.

Since the 1960 s, with the establishment of environmental protection laws and regulations in developed countries and the enhancement of environmental awareness, the trend of waterborne polyurethane coatings replacing traditional solvent-based polyurethane coatings has become more and more obvious.

After entering the 90 s, the development of waterborne polyurethane is very rapid.

Waterborne polyurethane first appeared in the US market in 1967.

Mass production was possible in 1972.

In the 1970 s and 1980 s, some waterborne polyurethane products in the United States, Germany, Japan and other countries have developed from the development and trial production stage to actual production and application. Their application fields have covered wood, construction, automobiles, airplanes and many other fields, and have attractive development prospects.








Characteristics of waterborne polyurethane

Waterborne polyurethane is a binary colloidal system with water as the medium, and polyurethane particles are dispersed in a continuous aqueous phase, which is also called water-based polyurethane or water-based polyurethane. Compared with solvent-based polyurethane, waterborne polyurethane has the advantages of no solvent odor and no pollution, as shown in the following table:

Performance Comparison of Waterborne and Solvent Based Polyurethane Coatings








 




Application of Waterborne Polyurethane Coatings

With the strengthening of people's awareness of environmental protection and the restrictions of environmental laws and regulations on the emission of volatile organic compounds (VOC), the research and development of waterborne polyurethane has been paid more and more attention.

Waterborne polyurethane coatings not only have the advantages of non-toxic, odorless, no pollution, not easy to burn, low cost, not easy to damage the coated surface, convenient construction, easy cleaning, etc., but also have the inherent high hardness and wear resistance of solvent-based polyurethane coatings. Excellent performance, so it has been widely used in many fields such as wood coatings, automotive coatings, architectural coatings, plastic coatings, paper coatings, and fabric and leather coatings.

Waterborne polyurethane wood coatings as the first to enter the market is bowling and stadium floor coatings, has been widely used in wood coatings industry.




 




Development history of wood coatings


 




Polyurethane wood coatings product characteristics

Waterborne polyurethane wood paint product characteristics:

Topcoat: with high abrasion resistance, good adhesion, no yellowing, good flexibility and other characteristics, diluted with water VOC ≈ 0.

Main physical and chemical properties and indicators:




 

 

synthetic process

The quality that can withstand pressure is tolerance. You must learn to bend down and accommodate, accept everything, and get everything.

 

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Defects of Waterborne Polyurethane Coatings

Compared with solvent paint, polyurethane water-dispersed water-based wood paint has incomparable advantages in saving energy and protecting the environment. It does not volatilize a large amount of VOC into the air, does not use organic solvent and uses water as diluent, thus saving energy. However, there are also some disadvantages. From the traditional concept, water-based wood paint dries slowly, has low hardness, easy stickiness and is easy to return in film performance compared with solvent-based wood paint, the fullness of the paint film is not as good as that of solvent-based wood paint.

Wood coating requirements are as low as possible in the construction of volatile organic solvents, quick drying, wear resistance, stain resistance, convenient construction. Waterborne polyurethane coatings meet precisely these requirements, in particular aliphatic polyurethane dispersions with water-dispersible polyisocyanates. Waterborne two-component polyurethane coatings.



Specific Examples

When the wetting agent w = 0.3%, co-solvent w = 5%, defoamer w = 0.02%, thickener w = 0.04%, the prepared waterborne polyurethane wood varnish coating has high gloss, hardness and good decorative performance, with gloss reaching 93.6, pendulum rod hardness 0.51, transparent without foam and good leveling. Cai Jiabin and others prepared a waterborne polyurethane wood coating, which was dried in 3.4kW microwave for 6min, which obviously accelerated the volatilization of water and reduced the side reaction of isocyanate and water.

 



Advantages after modification

 

Development Prospect of Waterborne Polyurethane

Although there are still many defects in waterborne polyurethane, with the increasing awareness of environmental protection, waterborne polyurethane coatings will enter a wide range of applications. From the current research, it can be seen that the development trend of waterborne polyurethane is as follows:

(1) In order to improve the water resistance, chemical resistance and weather resistance of the resin, the research on surface silicon modification and acrylic acid modification will be further developed.

(2) The sealing agent and crosslinking agent for waterborne thermosetting polyurethane will be the focus of research for a period of time in the future. The purpose is to improve the performance of the coating film after crosslinking and further reduce the curing temperature.

(3) waterborne polyurethane has been the lack of a variety of related special additives, with the expansion of market demand, water-based application of additives and the pace of commercialization will be further accelerated.

In a word, the research of waterborne polyurethane coatings is making a breakthrough in the direction of low cost, high performance and wide application fields. With the continuous emergence of new processes and technologies, waterborne polyurethane coatings will be further developed.

Tell, polyurethane, water-based, coatings, wood, performance, solvent-based, with, research, environmental protection

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