| The two-component waterborne polyurethane coating(2K-WPU)based on hydroxypolyacrylate aqueous dispersion(HAD)exhibits excellent chemical resistance and has become a hot spot for research and application.However,the present HAD has defects including low solidity and high viscosity,low hardness of 2K-WPU film,poor transparency,and poor stain resistance,which limits the promotion and application of 2K-WPU.In view of this,the article reported the methods to improve the performance of 2K-WPU coatings by adding high steric monomers,optimizing the dispersion process,adding organic fluorine and silicone monomers,which to solve the above problems.The HADs were prepared and the influence of dispersion process and macrocyclic monomer on the viscosity of HAD were studied,and found that the particle sizes of HAD prepared by the dispersion process of one-time water layer emulsification were smaller and the stability is better than those of the continuous addition water or resin dispersion process.Adding macrocyclic high steric hindrance monomer could achieve good viscosity reduction effect.When styrene was selected as the high steric hindrance monomer and under optimized process conditions,an aqueous dispersion with a solid content of 45% and a viscosity of 540 m Pa · s could be prepared.The influence of the ratios of hard and soft monomers and coating application technologies on the hardness and transparency of the coating film were investigates,and it was found that the hardness of the coating film increased,and the adhesion and flexibility deteriorated as the ratios of m(MMA)/ m(BA)increased,accompanying with the light transmittance of the coating film decreased slowly.And also found the light transmittance of 2K-WPU film decreased rapidly when the ratio of m(MMA)/ m(BA)exceeded 9.4.As the amount of SR-10 increased,the hardness of the coating film increased first and then decreased,and the film transparency first became better and then worsened.When the amount of 3wt% SR-10 was added,the film reached the highest hardness and light transmittance because the dispersion displayed good hydrophilic.When the application solid content became small,the transmittance and hardness of the coating film increased first and then decreased.The high curing temperature needed to cooperate with the coating film with low application solid content to offer good transparency.By combining the above processes,a 2K-WPU coating film with a coating film hardness of up to 2H and a light transmittance of 94% could be obtained.HAD were modified by the copolymerization of vinyl monomer hexafluorobutyl acrylate and octafluoropentyl methacrylate and the blending of hexafluorobutanol and octafluoropentanol,influence of organic fluoromonomer on the dispersion stability and resistance and stain resistance of 2K-WPU coating film wear were studied.It was found that the increase in the amount of hexafluorobutanol and octafluoropentanol monomer had hardly effect on the viscosity of the aqueous dispersion and the storage stability.The 0.45wt% octafluoropentanol modified coating film displayed excellent the wear resistance and stain resistance with 83 ° of the static water contact angle of the coating film and 0.014 g of the mass wear.Used octafluoropentanol,diphenyldihydroxysilane and 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane(H1)blending modified 2K-WPU,it was found that the coating film containing fluorosilicone monomer H1 had good hydrophobicity and oleophobicity,and the water contact angle of the coating film reached 83 °,which had good wear resistance,stain resistance and performance stability under light,because the coating film simultaneously carried the fluorine silicon elements. |
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