影响阴离子聚丙烯酸羟基树脂包覆HDI缩二脲乳胶粒粒径的因素

Factors influencing HDI biuret particle size coated by anionic polyacrylic hydroxyl resin

采用转相法制备了阴离子聚丙烯酸羟基树脂包覆HDI缩二脲乳胶粒.用TEM观察了包覆乳胶粒形态结构,分析了影响包覆乳胶粒粒径的影响因素.结果表明,乳胶粒呈现明显的核-壳结构,HDI缩二脲被聚丙烯酸羟基树脂包覆.聚丙烯酸羟基树脂分子量越大、溶剂极性越强,乳胶粒粒径越小.增加苯乙烯用量,乳胶粒粒径随之先减小后增加,苯乙烯质量分数为10%时粒径最小.乳胶粒粒径随羟基含量的增加而增大.当羟值为60mg KOH·g-1时,乳胶粒粒径随着丙烯酸含量的增加而减小;当羟值在90mg KOH·g-1以上时,降低丙烯酸含量有利于乳液粒径的减小.降低聚丙烯酸链间的氢键作用力,增加羟基和HDI缩二脲间的氢键作用力,能获得粒径小而均匀的包覆粒子.

HDI biuret particle coated by anionic polyacrylic hydroxyl resin was prepared by using phaseinversion technique. The morphology of composite particle was investigated by TEM. The effects of molecule mass of polyacrylic resin, the nature of solvent, styrene （ST） content, hydroxyl value and acid value on composite particle size （D） were discussed. The result indicated that composite particle had a clear core-shell structure, with hydrophobic HDI biuret as core and acrylic resin as shell. D decreased with the increase of Mn. Using methyl amyl ketone as solvent, composite particles had bimodal particle size distribution; while using methoxypropyl acetate as solvent, composite particles had a single small particle size distribution. With the increase of ST content, D decreased first, and then increased. D reached minimum when ST content in initial monomers was 10%. D increased with the increase of hydroxyl value （HV）. When HV was 60 mg KOH·g^-1, D decreased with the increase of acid value. While HV was above 90 mg KOH·g^-1, D increased with the increase of acid value. It was concluded that a small composite particle with narrow distribution could be obtained, by decreasing the hydrogen bond force among acrylic hydroxyl chains and increasing the hydrogen bond force between acrylic hydroxyl chain and HDI biuret.