一种热敏胶膜的制备及其性质

Preparation and Properties of a Thermo-sensitive Latex Film

通过三步法制备一种具有疏水内核、亲水外壳的聚合物微胶粒。首先,通过乳液聚合制备得到甲基丙烯酸丁酯与异丁烯酸甲酯共聚物(p(BMA-MMA))乳液。然后,在适当控制的条件下,利用一种氧化还原引发体系将p(BMA-MMA)微胶粒的表面引入一层聚甲基丙烯酸缩水甘油酯(p-GMA)外壳。最后,将外壳层的部分环氧基团转化为季铵盐,从而形成一种亲水性的外壳。这种核-壳型固体粒子能在水中再分散并形成稳定的乳状液,无须借助分散剂、乳化剂或其他添加剂的帮助。利用这种核-壳乳液制备的乳液薄膜与水的接触角为16°(25℃),而经150℃短时间处理后的接触角超过90°,表明完全由亲水性转变成疏水性。此外,乳液薄膜在加热处理前很容易被中性水从基板上冲洗掉,但在加热处理后不能被洗掉。当在乳液薄膜中加入一种在830nm有最大吸收的红外染料后,薄膜对830nm激光敏感,并经曝光、中性水显影后可形成阴图型图像。

Polymer particles with hydrophobic core and hydrophilie shell were prepared via a three-step method. Firstly, poly （ butyl methaerylate-co-methyl methacrylate ） （ p-（ BMAMMA） ） latex was prepared through emulsion polymerization. Secondly, a shell of poly （ glycidyl methacrylate） （ p-GMA ） was introdueed around the p-（BMA-MMA） particles by using a redox initiation system under kinetieally controlled conditions.Finally, part of the epoxy groups existing in the shell was converted into quaternary ammonium salts, resulting in an ionic hydrophilic shell. The core-shell particles could be redispersed in water to form a stable emulsion. The contact angle of the core-shell latex film with water was around 16°at 25℃ , which became larger than 90° after the film was heated at 150℃ for a short period of time. This showed that the latex film was completely switched from hydrophilicity to hydrophobicity by the action of heat. Additionally, the latex film before heat treatment could be easily washed away from the substrate with neutral water, but it could no longer be removed after the heat treatment. When an IR dye with the maximum absorption at 830nm was incorporated into the film, it became sensitive to LD laser emitting at 830nm and gave negative image after exposed by LD laser and developed with neutral water. This showed that the latex film might find uses in chemical-free thermal laser imaging applications.