What is waterborne polyurethane coating

Polyurethane coating is a new type of coating developed after 1960. It has excellent adhesion, chemical resistance, decorative properties and excellent wear resistance. It is a kind of high-grade and durable synthetic resin coating.Polyurethane coating more than nitrocellulose paint, acrylic paint, epoxy paint, oil paint, natural resin paint, become the third largest variety of paint, the output of alkyd resin paint, phenolic resin paint.It is widely used in the protection and decoration of national defense, aerospace, transportation, home appliances, wooden furniture, instruments and meters, interior decoration, etc.

At present, polyurethane coatings account for about 7%-8% of the total number of coatings in China, mainly including wood furniture paint, floor paint, automobile repair paint, anticorrosive paint and special paint.

Polyurethane coatings are divided into solvent-based and non-solvent-based, non-solvent-based including waterborne polyurethane, powder polyurethane, solvent-free coatings.

Waterborne polyurethane coating is based on waterborne polyurethane with water as the dispersing medium.In order to obtain stable polyurethane emulsion, there are two preparation methods, namely external emulsification method and internal emulsification method.External emulsification method is in the presence of solvent, the hydrophobic polyurethane resin through chain extension to add emulsifier (alkyl sulfonate, quaternary ammonium salt, etc.), in water high speed stirring forced emulsification and dispersion, and then remove the solvent to get polyurethane emulsion.Or the end-NCO based prepolymer is emulsified by adding emulsifier in water, and then the solvent is removed.External emulsification is seldom used.Internal emulsification involves the introduction of hydrophilic groups into polyurethane molecular chains.At present, there are three types that are widely used, namely, single component, two component and improved type.

(1) one component waterborne polyurethane coating

First, the prepolymer is synthesized from water-soluble polyether diol (such as polyethylene glycol or EO and PO copolymer containing 10%-40% ethylene oxide blocks), and then the film is formed by sealing -NCO and thermal reaction.

(2) two-component waterborne polyurethane coating

The mechanism is that the evaporation rate of water is much higher than the reaction rate of -NCO and -OH and H2O. Although the system has too much water, the reaction of -NCO and -OH is still the main reaction.

(3) improved waterborne polyurethane coating

Polymerization of acrylate monomers in aqueous dispersion of polyurethane is the main way to produce this kind of coatings.

UV-curable waterborne polyurethane coatings are prepared by introducing double bonds into the molecular structure of dispersions and adding photoinitiators. During construction, they are cured by electron beam or UV light.

Waterborne polyurethane is a kind of polyurethane particles dispersed in water swelling, particle size is mostly 0101μm-015μm, smaller than acrylic emulsion.At present, waterborne polyurethane has anionic type, cationic type and non - free

Three types of sub-type, because of the low content of volatile organic compounds, in the industrial waterborne paint, building paint, material coating, waterborne glue and other fields have a great space for development.

With the progress of society, the development of science and technology, the improvement of people's awareness of environmental protection and the promotion of the development of environmental protection products, polyurethane has been used more and more for people to develop environmental protection products because of its excellent performance.

Amber Zhang Ms.

Foreign trade 

Zhejiang Ruico Advanced Materials Co., Ltd. (Stock No.873233)

Add: No.188, Liangshan Road, Linghu Town, Nanxun District, Huzhou City, Zhejiang Province, China 313018

Phone: +86 (572) 2903236

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Website: www.ruicoglobal.com 

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