聚氨酯-丙烯酸酯复合乳液的合成与表征

以甲苯二异氰酸酯(TDI-80)、聚醚二元醇(N210)、二羟甲基丙酸(DMPA)、甲基丙烯酸羟乙酯(HEMA)、己二酸二酰肼(ADH)和二丙酮丙烯酰胺(DAAM)等为原料,采用原位乳液聚合法,先制得水性聚氨酯(PU)预聚物,然后加入引发剂进行自由基聚合,分别得到无交联型PUA-1、合成交联型PUA-2和室温交联型PUA-3 3种水性聚氨酯-丙烯酸酯复合乳液(PUA),并用这3种乳液配制了清漆.探讨了DMPA、HEMA、ADH和DAAM加入量对乳液和涂膜性能的影响.研究结果表明,当DMPA中的COOH、HEMA、ADH和DAAM的含量(占PU的质量分数,下同)分别为2.5%、1.44%、3.5%和2.0%~3.0%时,乳液和涂膜性能较好.通过粒径和透射电镜(TEM)分析发现,PUA-1胶粒的平均粒径在40~50nm之间,粒子呈规则球形;PUA-2胶粒的平均粒径在90~100nm之间,核壳间形成互穿网状交联结构,胶粒形态偏离球形,与PUA-1相比,粒径增大,粒径分布变宽;PUA-3胶粒的平均粒径在30~40nm之间,壳层分子与核内分子的互穿部分呈无规状态,胶粒形态非常不规则,但粒径分布比较均匀.由PUA-3配制的清漆的耐水性、耐干热性及耐粘污性都很好,但涂膜干燥速度很慢.

Preparation and Characterization of Polyurethane-Acrylate Hybrid Emulsion

Aqueous polyurethane(PU) prepolymers were synthesized by emulsion polymerization in situ,with to-luene diisocyanate(TDI-80),polyether binary alcohol(N210),dimethylol propionic acid(DMPA), hydroxyl ethyl methacrylate(HEMA),adipic dihydrazide(ADH) and diacetone acrylamide(DAAM) as the materials.Three kinds of aqueous polyurethane-acrylate(PUA) hybrid emulsions marked as PUA-1(free cross-linking),PUA-2(synthesized cross-linking) and PUA-3(cross-linking at ambient temperature) were synthesized after the free radical polymerization by adding initiator,which were then used to prepare three kinds of varnishes.The effects of the dosages of DMPA,HEMA,ADH and DAAM on the properties of emulsions and films were finally investigated.It is found that,when the mass fraction of COOH in DMPA and the mass fractions of HEMA,ADH and DAAM in PU are respectively 2.5%,1.44%,3.5% and 2.0%~3.0%,the emulsions and films are all of good properties.Moreover,the results obtained by particle size analyzer and TEM show that(1) the average particle sizes of PUA-1,PUA-2 and PUA-3 are respectively 40~50 nm,90~100 nm and 30~40 nm;(2) PUA-1 particles are regular sphericities in shape,while PUA-2 particles are irregular sphericitis with interpenetrating polymer network between the core and the shell;(3) as compared with PUA-1,PUA-2 is of larger particle size and wider particle size distribution;(4) PUA-3 is of very irregular particle shape,uniform particle size distribution and disorganized interpenetrating network between the shell and the core.Furthermore,in the three kinds of vanishes,the one prepared from PUA-3 is of the best water resistance,dry-heat resistance and stain resistance but is of the longest drying time for the film.