大分子不饱和单体法合成具有核壳结构的丙烯酸酯/聚氨酯乳液及表征

Synthesis and Characterization of Core-shell Acrylic/polyurethane Emulsion with Unsaturated Macromolecule Monomer Method

采用丙烯酸酯(AC)对水性聚氨酯(WPU)进行改性,合成了接枝型丙烯酸酯/聚氨酯(PUA)复合乳液。随着共聚物中丙烯酸酯质量分数的增加,乳液外观由透明变为不透明,乳液粒径随之增大、分布变宽。TEM显示,PUA乳胶粒子呈现清晰的核壳结构,且形态规整,粒径分布在60～120 nm之间。FTIR测试表明,随着丙烯酸酯质量分数的增加,聚氨酯(PU)硬段氢键化作用先增强后减弱,硬段的有序度逐渐降低。DSC分析表明,当AC的质量分数低于75%时,PU、聚丙烯酸酯(PA)两组分相容性较好,只出现一个玻璃化转变温度,并且随着PA质量分数的增加逐渐升高。PA质量分数的增加,使胶膜的最大热失重速率从363℃提高至412℃,吸水率从11.3%降低至5.7%,弹性模量从16.4 MPa提高至47.6 MPa,拉伸强度从9.0 MPa提高至23.7 MPa,断裂伸长率从365%提高至408%,同时乳液的粘度下降,干燥时间变短,胶膜的附着力变好。

Acrylic/polyurethane（PUA） hybrid emulsion has been prepared by water-borne polyurethane（WPU） modified with acrylic resin.A method for adding different mass fraction of acrylic（AC） into polyurethane（PU） polymers is proposed and verified through designed experiments.With increasing the polyacrylate（PA） mass fraction in the copolymer,the appearance of the emulsion changes from transparent to opacity,in the meantime,the particle size is increased.The TEM result reveals that PUA latex particles present clear core-shell structure and regular shape,and the size distribution is within the range of 60~120 nm.The results of FTIR indicate that the hydrogen bonding effect of PU hard segment first increased and then decreased,while the ordering of hard segment decreased with increasing the AC mass fraction.Compatibility and degree of mixing were developed under 75%AC added in copolymers.With increasing PA mass fraction,one glass transition temperature existed in the copolymers before the content of AC arrived 75%.Thermogravimetric analysis（TGA） shows that the temperatures for the maximal thermal mass-loss rate rose from 363 ℃ to 412 ℃,and water absorption for samples decreased from 11.3% to 5.7% with the increase of AC fraction.Additionally,the elasticity modulus of PUA was raised from 16.4 to 47.6 MPa,while the tensile strength was increased from 9.0 to 23.7 MPa,and the elongation at break changed from 365% to 408%.Furthermore,the composite latex viscosity is decresed,and the drying time is shortened,while glue film adhesion force becomes better.