Two-component PU (polyurethane) coating and preparation method thereof

Abstract

The invention discloses a two-component PU (polyurethane) coating. Firstly, castor oil is used for cross-linking prepolymers: a multifunctional group structure in the castor oil can cross-link the polymers to a certain extent, the cross-linking degree of the polymers is increased, so that the interaction force among molecular chains is increased, motion of the molecular chains is hindered, water molecules can hardly enter the molecular chains to enable the polymers to swell, and the water absorption of a film is reduced; meanwhile, the castor oil is a triglyceride of fatty acid, the film has the good hydrophobicity due to long nonpolar fatty acid chains in molecules of the castor oil, and the water absorption is further reduced; besides, ester groups in the castor oil have higher cohesive energy, so that the tensile strength of the film can be enhanced; ethyl cellulose has better heat resistance and thermoplasticity, has good compatibility with PU and can improve the comprehensive performance of the prepolymers; then blending modification is performed on the PU prepolymers and polysilsesquioxane.

Description

technical field [0001] The invention relates to a coating, in particular to a two-component polyurethane coating and a preparation method thereof. Background technique [0002] Water-based polyurethane emulsion has the advantages of adjustable hardness, excellent adhesion and flexibility, and is widely used in the fields of coatings, adhesives and inks. At present, the relatively mature anionic water-based polyurethane is synthesized mainly through the synthesis of polyurethane molecular chains. The hydrophilic group is introduced into the segment and internally emulsified. After film formation, it has certain hygroscopicity, and the mechanical properties, water resistance and solvent resistance of film formation are poor. Usually, cross-linking modification and compound modification can be used to improve the water resistance and mechanical properties of the film; [0003] In order to improve the mechanical properties, water resistance and other properties of polyurethane,...

AI Technical Summary

Problems solved by technology

[0002] Water-based polyurethane emulsion has the advantages of adjustable hardness, excellent adhesion and flexibility, and is widely used in the fields of coatings, adhesives and inks. At present, the relatively mature anionic water-based polyurethane is synthesized mainly through the synthesis of polyurethane molecular chains. The hydrophilic group is introduced into the segment to emulsify internally, and the film has a certain degree of hygroscopicity, and the mechanical properties, water resistance and solvent resistance of the film are poor.