苯丙乳液合成反应条件优化

以苯乙烯、丙烯酸、丙烯酸丁酯、甲基丙烯酸甲酯等为单体,采用乳液聚合制备了苯丙乳液,研究了合成温度、引发剂用量、乳化剂用量、功能性单体丙烯酸用量等反应条件对苯丙乳液性能的影响,并探讨了丙烯酸单体对乳液耐酸碱稳定性的影响,确定了合成反应条件.结果表明,随着合成温度的提高,混合单体的转化率迅速增加,78℃时转化率最大(达到97.1%),而后随温度继续提高基本保持不变.混合单体转化率随过硫酸钾引发剂用量的增加呈现先增加后逐渐降低的趋势,当过硫酸钾与混合单体质量比为0.010时转化率最大,此时单体转化完全.此外,随着乳化剂用量增加,乳液的外观、钙离子稳定性、凝胶等性能都有所提高,但吸水率也相应增加.最佳合成反应条件为:合成温度为78℃,混合单体组成为15g苯乙烯、2g丙烯酸、18g丙烯酸丁酯、8g甲基丙烯酸甲酯,引发剂和乳化剂与单体质量比分别为0.010和0.035.得到的苯丙乳液在酸性条件下具有良好的稳定性.

Optimization of synthetic conditions of styrene acrylic emulsion

Styrene acrylic emulsion used in water-borne paints was prepared by emulsion poly- merization with styrene, acrylics acid, butyl acrylate and methyl methacrylate as the mono- mers. The reaction conditions such as reaction temperature, initiator dosage, emulsifier dosage, and functional monomer acrylic acid dosage on the performance of as-synthesized sty- rene acrylic emulsion were systematically studied. Moreover, the effect of acrylic acid monomer on the ability of as-synthesized styrene acrylic emulsion to resist acid attack and alkaline attack was explored, and the optimized reaction condition was established. Results indicate that with the increase of reaction temperature, the conversion rate of the mixed monomers increases rapidly and reaches the maximum of 97.1% at 78 C, then it remains nearly unchanged with further increase of reaction temperature. In the meantime, the conversion rate of the mixed monomers tends to rise initially but decline later with increasing dosage of potassium persulfate initiator. Particularly, the conversion rate reaches the maximum when the amount of potassium persulfate is 0.010 of the total mass of the mixed monomers, and in this case the mixed mono- mers are completely converted. Besides, with the increase of emulsifier dosage （mass ratio of e- mulsifier to monomer）, the appearance, stability against Ca2＋ , and gel performance of as-syn- thesized styrene acrylic emulsion tend to be improved to some extents, but its water absorptionincreases therewith. In terms of the optimized reaction condition, the reaction temperature is suggested as 78 C, the composition of the mixed monomers is suggested as 15 g styrene, 2 g acrylic acid, 18 g butyl acrylate, and 8 g methyl methacrylate, and the percentages of the initi- ator and emulsifier in relation to the mixed monomers are suggested as 0.010 and 0.035. Target styrene acrylic emulsion obtained under the optimized reaction condition exhibits good stability in acidic mediums.