环氧聚氨酯乳液的黏度和稳定性

采用聚酰胺对环氧树脂进行扩链后并进行阳离子化改性,共混入聚氨酯固化剂,用外加乳化剂进行相反转,制得了环氧聚氨酯乳液,研究了溶剂用量及溶剂配比、改性环氧树脂相对分子质量大小、水溶性及固化剂用量等对乳液黏度和稳定性的影响.实验发现:树脂体系中溶剂量存在一临界值为8.8%(质量分数,下同),当溶剂量高于8.8%时,较难发生相反转,制得的乳液不稳定;当溶剂用量低于8.8%时,能发生相反转,且乳液稳定性好;疏水性的二甲苯部分代替亲水性的乙二醇单丁醚,能显著降低改性环氧树脂的黏度和最终乳液的黏度.当聚酰胺用量为环氧树脂用量的6.0%~6.5%时,中和度达65%,改性环氧树脂水溶性较好;控制固化剂量为改性环氧树脂量的15.0%~20.0%时,制得的乳液稳定性好.

Viscosity and Stability of Epoxy-Polyurethane Emulsion

A kind of epoxy resin was chain-extended by polyamide,cationic-modified,blended with curing agent of polyurethane,and then emulsified by means of phase inversion.Thus,an epoxy-polyurethane emulsion was prepared.The viscosity and stability of the emulsion were then investigated with such different parameters as the solvent dosage and mixing ratio,the relative molecular mass of the modified epoxy resin,the water solubility and the curing agent dosage.It is found from experiments that the mass fraction of the solvent in resin has a critical value of 8.8%.When the solvent dosage is more than 8.8%,the phase inversion is difficult to occur and the prepared emulsion is unstable.On the contrary,this is possible when the dosage is less than 8.8%.Moreover,it is indicated that,as the water-soluble solvent of ethylene glycel mono-butyl ether is partly substituted by the hydrophobic solvent of xylene,the viscosities of the resin and the emulsion both greatly decrease,that the modified epoxy resin is easily soluble when the polyamide dosage is 6.0%~6.5% that of epoxy resin and the neutralization degree is 65%,and that the prepared emulsion is very stable in a curing agent dosage of 15.0%~20.0%.