聚氨酯-环氧树脂-松香复合乳液的合成与表征

Synthesis and Characterization of Polyurethane-Epoxy Resin-Rosin Hybrid Emulsion

以聚已内酯二醇、甲苯二异氰酸酯、二羟甲基丙酸为基料,三羟甲基丙烷为交联剂,采用环氧树脂和松香对水性聚氨酯进行改性,制备出环氧树脂和松香改性的聚氨酯复合乳液.采用傅里叶变换红外光谱、粒度分析仪、凝胶渗透色谱、差示扫描量热仪等对乳液进行表征.结果表明:环氧树脂中的羟基与异氰酸酯基发生反应,生成了氨基甲酸酯基,同时环氧基进行了开环反应,接枝到聚氨酯分子上;松香中的羧基也参与了体系的反应,最终形成了环氧和松香改性水性聚氨酯;环氧树脂和松香含量增大,都会导致乳液粒径增大;改性后聚氨酯复合乳液的相对分子质量有一定程度的增大,达7.43×105;三羟甲基丙烷用量对剥离强度有显著影响,其用量以不超过2.7%为宜;改性后聚氨酯的相容性好,其胶膜分解温度高达260℃,说明采用该乳液制成的胶粘剂对多种复合薄膜具有较强的粘接能力.

Waterborne polyurethane （WPU） hybrid emulsions were prepared from polycaprolactone glycol （PCL）, tolylene diisocyanate （TDI） and dimethylolpropionic acid （DMPA）, with trimethylol-propane （TMP） as the crosslinking agent and with epoxy resin and rosin as the modification agents. The structures and properties of the products were then characterized by means of FTIR, particle size analysis, GPC and DSC. The results indicate that the preparation of WPU is due to the formation of urethane groups via the reaction between the hydroxyls in epoxy resin and the diisocyanate groups in TDI, to the ring-opening reaction, and to the participation of grafting of epoxy resin onto the polyurethane （PU） molecules via a ring-opening reaction, and to the participation of carboxyls in rosin in the reaction. Moreover, it is found that the average particle size of WPU hybrid emulsions increases with the contents of epoxy resin and rosin, that the relative molecular mass of the modified WPU is up to 7.43 × 10^5 , that the content of TMP should not be more than 2. 7% due to its great effect on the peeling strength of WPU film, that epoxy resin, PU and rosin all have good compatibil- ity after the modification, and that the decomposition temperature of the cast films is more than 260 ℃, revealing strong adhesion strength of the adhesive formulated by the modified WPU emulsion for various laminated package films.