Study On The Stain Resistance Of Exterior Latex Coating

Exterior coating has become the main ornamental material by replacing ceramic tile which has many outstanding properties, like colorful , environment friendly, without peculiar smell, safety, easy to construction, good ventilation property and so on. It is researched that contamination is the most serious defect in short period. Inadequate stain resistance has become the biggest block in generalizing exterior coating in our country.This article chooses the most commonly used acrylic resin as emulsion, and researches the contamination mechanism and influence factors of exterior coating. It confects a series of formulations of high stain resistance latex paint by enhancing consistence and improving surface energy of paint film. It researches the consistence change rule with PVC and the relationship between consistence and stain resistance. The formulation has high consistence and stain resistance by controlling PVC, adding nano-material. Adding some suitable low surface energy additives can reduce the surface energy and water absorption of paint film, which reduces the blocking and enhances the stain resistance .It is tested that increasing the PVC can enhance stain resistance when PVC is less than CPVC, but the porosity would rapid rise which cause the poor stain resistance when PVC exceed CPVC. Increasing the consistence and hardness can improve the stain resistance by adding nano- SiO₂ and nano-TiO₂.It researches the effect on the dispersion of nano- SiO₂ and nano-TiO₂ of diffusion technique , pH and dispersant. It confirm the suitable dispersion condition which are ultrasonic diffusion technique, pH of 9 and 10 corresponding nano- SiO₂ and nano-TiO₂, and compounding the abio-electrolyte dispersant and organic-electrolyte.Modifying the nano-material with KH570 could make outstanding dispersion. Modified Nano-material could bring the superior stain resistance to latex paint than the un-modified. Adding nano- SiO₂ and nano-TiO₂ could improve the stain resistance by increasing consistence and hardness of latex paint with suitable dosage 1.5%. Adding suitable low surface energy addictives is another effective method to improve the stain resistance. BS45,BS1306,LD,FSP,9361 are such addictives. Fluoro-addictives has higher cost performance than those silicone addictives.By controlling the PVC and adding some suitable addictives could increase the consistence and reduce the surface energy , which is the effective method to improve the stain resistance of latex paint.