羟基单体对丙烯酸酯聚合物乳液及其乳胶粉性能的影响

通过添加功能单体甲基丙烯酸－β－羟丙酯（HPMA）和甲基丙烯酸（MAA）制备软核硬壳的丙烯酸酯聚合物乳液及其可再分散乳胶粉。重点讨论羟基单体HPMA用量对软核硬壳丙烯酸酯乳液和乳胶粉再分散液的成膜性、再分散稳定性和耐水性等性能的影响。实验结果表明，HPMA添加量为1.2%左右时，在保证再分散稳定性的同时，制备得到的丙烯酸酯原乳液和可再分散乳胶粉的成膜性好，耐水性达到最优；吸光度测试显示HPMA添加量小于等于1.2%时，乳胶粉再分散稳定性好，分散度高达90%，吸光度平均变化小于10%；差示扫描量热（DSC）测试显示丙烯酸酯聚合物乳液胶膜有6 ℃和30 ℃两个玻璃化转变温度（Tg），乳胶粒子具有软核硬壳结构；扫描光学显微镜（SEM）测试显示原乳液和乳胶粉再分散液成膜性能优异，合成的原乳液在成膜的过程中发生了微相分离，进一步说明合成的乳液具有软核硬壳结构；傅立叶转换红外线光谱（FTIR）显示丙烯酸酯聚合物乳胶粉与原乳液红外谱图基本吻合，说明在一定的干燥条件下，喷雾干燥前后乳胶粒的化学结构不发生明显的变化。

Influence of Hydroxy-Functional Monomer on Properties of Acrylate latex and Its Redispersible polymer Powder

Acrylate latex with the configuration of soft core and hard shell were synthesized by emulsion polymerization with hydroxy-functional monomers 2-hydroxy propylmethacrylate (HPMA) and Methacrylic Acid (MAA ). The effect of the amount of HPMA on the film forming ability, redispersibility and water resistance of“mother”emulsion and redispersible emulsion were emphatically discussed. The experimental results show when the amount of HPMA is 1.2%, film forming ability and water resistance of the acrylate emulsion and its redispersible polymer powder are optimal, and the redispersibility of redispersible polymer powder almost remains stable. Absorbance of redispersible emulsion illustrates that when the amount of HPMA is equal or lesser than 1.2%, the redispersibility is excellent (the dispersity is no less than 90% and the average change of the absorbance is less than 10%). DSC shows the film of“mother”emulsion has two glass transition temperature, core is 6 ℃ and shell is 30 ℃, and the emulsion has the configuration of soft-core and hard-shell. SEM shows the“mother”emulsion and redispersible emulsion both have a good film forming ability, and it also indicates that microphase separation occurs in the film-forming process of “mother”emulsion, which also proves that the emulsion has the configuration of soft-core and hard-shell. FTIR shows that the configuration of acrylate emulsion and its redispersible polymer powder are similar, that is to say the structure of emulsion polymer is unchanged during the spray-drying process. And it is available to dry self-crosslingking acrylate emulsion into powder by spray drying.