摘要： 以2,2,4-三甲基戊二醇-1,3单异丁酸酯(Texanol)和正十二烷基硫醇(n-DM)为链转移剂(CTA)制备苯丙乳液,系统地研究了CTA在苯丙乳液聚合过程中对聚合稳定性、单体转化率、粒径及其分布、相对分子质量及其分布、玻璃化转变温度(T_g)、最低成膜温度(MFT)、结构凝胶含量及胶膜的吸水率的影响。结果表明:在聚合体系中加入2%的Texanol和0.25%的n-DM时,在对聚合反应无影响的情况下,可使结构凝胶含量从原来的46.0%降为3.6%,聚合物质均相对分子质量从原来的2.28×10⁵降为0.88×10⁵,聚合物的T_g降低了3.9℃,乳液的MFT降低了4.9℃,涂膜的吸水率降低了约2%,涂膜的附着力从原来的3级提高至1级。

关键词: 链转移剂, 苯丙乳液, 结构凝胶控制, 相对分子质量及其分布

Abstract: In this paper, a styrene-acrylate latex with low intrinsic gel content was synthesized by emulsion copolymerization using 2,2, 4-trimethyl-1, 3-pentanediolmono(2-methylpropanoate)(Texanol and dodecyl mercaptan(n- DM) as chain transfer agent (CTA). The effects of the amount CTA on the properties of the emulsion, such as the stability, monomer conversion, particle size and distribution, minimum film forming temperature (MFT), glass transition temperature(Tg)molecular weight of the copolymer, intrinsic gel content and water absorption of coating film was investigated in detail. It was found that the gel content decreased from 46.0% to 3.6% weight-average molecular weight from 2. 28 x 10⁵ to 0.88×10⁵,and the T, of the copolymer reduced by 3.9 ℃, the MFT of emulsion lower by 4.9 ℃ and water absorption of coating film reduced about 2%, but the adhesion of the coating raised from the original grade 3 to grade, when Texanol amount was 2% and n-DM amount was 0.25% of the total amount of monomers.

Key words: chain transfer agent, styrene-acrylate latex, intrinsic gel controlling, molecular weight and distribution