Design And Application Of Environment - Friendly Building Latex

Study on styrene-acrylic emulsion is a larger number of systems in emulsion polymerization As non-crosslinked emulsion, styrene-acrylic emulsion has a very wide range of uses, but still has some flaw in application. For elastic exterior wall was not resistant to stain, a complex latexes (PUA) with polyurethane shell-styrene-acrylate core were successfully synthesized. Since waterborne polyurethane resin was easily film-forming, strong bonding, and finished products felt full, soft texture, with non-combustible, non-toxic, non-polluting advantages. Water and oil repellent performance degradation ills which caused by polyurethane hydrophilic groups could be eliminated by adding fluorine-containing resins. Besides that, fluorinated polyurethane could provide excellent surface properties. For interior latex paint peeling and fading, epoxy resin was grafted to styrene-acrylate which could greatly improve the performance of interior latex paint. Because epoxy resin had excellent chemical stability, adhesion and so on. It’s necessary for latex requirements to use post-polymerization and conversion technologies to obtain ultra-low VOC content of acrylic latex.(1) Fluorine-containing polyurethane-acrylic latex (FPUA):For contradiction against the elastic did not stain resistant, a complex latexes with fluorine containing polyurethane shell-styrene-acrylate core (FPUA) were successfully synthesized in this chapter. FPUA film-forming substances in water-borne coatings for exterior wall had excellent mechanical properties,weather resistance and stain resistance. The results showed that, when the ratio of main monomer BA and St was300:200, the resulting elastic styrene-acrylic latex could meet the mechanical properties of elastic emulsion paint for exterior wall, but lack of stain resistant; For elastic acrylic latex film with the shortcomings of low tensile strength, poor stain resistance, styrene-acrylic latex was modified by water-based PU. When PU content was7%, the prepared PUA latex film of the core-shell structure had excellent tensile strength and elongation; Based on the PUA, graft copolymer shell must have content of fluorine-containing monomer (6%), which could effectively improve the water contact angle of the latex film;Preparation of aqueous film-forming substances to FPUA elastic coatings had excellent stain resistant.(2) Epoxy resin (E-20) modified styrene-acrylic elastic latex (EPA):In this chapter we used epoxy resin modified styrene-acrylic latex (EPA) to synthesis the solid content of10%E-20of the EPA latex. Studied epoxy equivalent on particle size and distribution of EPA latex particles, on the performance of the heat resistance of EPA latex film, on the type of crosslinking agent for weatherability and mechanical properties of crosslinked latex film, and also on the application of EPA latex. The results showed that, by seed emulsion polymerization, when the seed concentration was7%, the ratio of anionic emulsifier to non-ionic emulsifiers was2:1, the initial initiator concentration was62.5%, the prepared EPA latex whose epoxy resin solids content was10%had no gel, good stability, high monomer conversion; By the test results of water resistance, acid and alkali resistance, crosslink density and mechanical properties, diethylene triamine was the ideal EPA curing agent and had the optimal performance; Contrast E-51, E-20modified EPA latex of higher molecular weight, better heat resistance, penetration and adhesion, was ideal for interior paint film-forming substances.(3) Ultra-low VOC content of acrylic latex (SA):In this chapter, emulsifier complex system and the amount of initiator which were optimized by research group were used to prepare stable styrene-acrylic latex by seed emulsion polymerization. And headspace gas chromatography method was established for the determination of the residual monomer concentration. The results showed that, the headspace gas chromatography method was established for the determination of concentration of BA、St, and got fBA=1.2fsi=0.7by internal standard method, and showed a good linear relationship; After the monomer addition was completed, the process of insulation and heating up contributed to reduce residual monomer concentration, and also had an impact on particle size distribution of latex. Tert-butyl hydroperoxide and ascorbic acid redox system to reduce the residual monomer content is better than t-butyl hydroperoxide and sodium formaldehyde sulfoxylate system. The molar ratio of t-butyl hydroperoxide and ascorbic acid had an effect on the concentration of residual monomers and latex morphology; It’s effective method to reduce the residual butyl acrylate concentration in latex by adding hydrazine hydrately.