Study On The Influencing Factors Of The Limit Film Thickness Of Waterborne Two-component Polyurethane Coatings

The preparation process of this paper is free radical copolymerization.Hydroxyl acrylate aqueous dispersions with different hydroxyl content and different average particle diameters are prepared for experimental investigation.This article mainly explores the hydroxyl content and average particle size of aqueous hydroxyacrylic dispersion;the structure,-NCO content and molecular weight of isocyanate curing agent;the antifoaming agent,leveling agent and solvent in the additive are non-foaming to aqueous two-component polyurethane coatings.Effect of limiting film thickness.The experimental results are helpful to guide the better reduction of the apparent defects of the paint film in the complete coating formula,show the better fullness and decorative performance of the paint film;at the same time,it can guide the production,greatly improve the spraying efficiency in large-scale industrial production,and save cost.Regarding the factors that affect the non-foaming limit film thickness of waterborne two-component polyurethane coatings,the experimental results based on the experimental data are as follows:(1)The larger the hydroxyl content of the aqueous dispersion,the greater the non-foaming limit film thickness of waterborne two-component polyurethane coatings.When the hydroxyl content is similar,the larger the average particle size,the larger the non-foaming limit film thickness of the aqueous two-component polyurethane coating.(2)The stronger the relative reactivity of the R group on different types of isocyanate curing agents R-NCO,the larger the non-foaming limit film thickness of the aqueous two-component polyurethane coatings;the greater the-NCO content and molecular weight of the same type of isocyanate curing agents The larger the non-foaming limit film thickness of water-based two-component polyurethane coatings.And for the effect of the non-foaming limit film thickness of water-based two-component polyurethane coatings,the influence of molecular weight is higher than that of-NCO content.(3)The silicone-based defoamer in the additive can better improve the non-foaming limit film thickness of the paint film,and the defoamer without VOC(volatile organic compound)can better improve the non-foaming limit film of the paint film Thick;silicone-based surfactants can better increase the bubble-free limit film thickness of paint films,and VOC(volatile organic compound)-free leveling agents can better increase the bubble-free limit film thickness of paint films.(4)The solvent with lowermolecular weight and slower volatilization rate can better increase the non-foaming limit film thickness of the paint film.And for the effect of the non-foaming limit film thickness of water-based two-component polyurethane coatings,the effect of volatilization rate is higher than the effect of molecular weight.