丙烯酸羟乙酯对丙烯酸酯改性水性聚氨酯性能的影响

Effect of Hydroxyethyl Acrylate on the Properties of Polyurethane-Acrylics Hybrid Latexes

以异佛尔酮二异氰酸酯、二羟甲基丙酸和聚丙醚二醇等为聚氨酯原料,丙烯酸丁酯、甲基丙烯酸甲酯、三羟甲基丙烷三丙烯酸酯为丙烯酸酯类单体,丙烯酸羟乙酯(HEA)为聚氨酯和聚丙烯酸酯间的偶联剂合成了丙烯酸酯改性水性聚氨酯(PU-AC)乳液.首先建立并验证了一种测定PU接枝率,即PU与丙烯酸酯发生接枝的部分占PU总数的百分比的方法,然后探讨了加入HEA后的反应温度和HEA用量对PU接枝率、PU-AC乳胶粒径、胶膜吸水率和交联度等性能的影响.随着HEA与PU预聚体反应温度和HEA用量的提高,体系中的最终残余NCO逐渐降低.当HEA用量低于其加入前体系中残余NCO量时,增加其用量使PU接枝率和PU-AC乳胶粒径逐渐增加;当HEA用量大于体系残余的NCO量后继续增加其用量对PU接枝率和PU-AC乳胶粒径的影响不大.胶膜吸水率随着HEA用量的增加而降低.

Polyurethane-acrylics （PU-AC） hybrid latexes were prepared using isophorone diisocyanate, dimethylol propanoic acid and polypropylene oxides of different molecular weights as main materials for PU component, and butyl acrylate, methyl methacrylate and a crosslinker, trihydroxymethyl propanetriacrylate （TMPTA） as main acrylic monomers. Hydroxyethyl acrylate （HEA） was used as the coupling agent between PU and AC. In a first step, a method for evaluation of PU grafting to AC polymers was proposed and verified through designed experiments. The influences of reaction temperature of HEA and NCO in PU prepolymer and of amount of added HEA on properties of the final latex and of the polymer, for instance, PU grafting, particle size and distribution in final PU-AC latex, polymer crosslinking and water adsorption of latex films, were explored. With increase in the reaction temperature between HEA and NCO, the final residual NCO gradually decreased. With increase in HEA amount relative to NCO, expressed as HEA/NCO in mole, the particle size and PU amount grafted to AC polymers both increased when the HEA/NCO was below 1.0; while both the particle size and PU amount grafted remained relatively constant when this ratio was above 1.0. Water adsorption of the latex films was in significant decrease with increasing HEA as the coupling agent.