封闭型异氰酸酯固化剂的合成及应用

Synthesis and application of blocked isocyanate curing agent

采用甲乙酮肟(MEKO)为封闭剂,与三苯基甲烷三异氰酸酯(TTI)反应,制备了封闭型三苯基甲烷三异氰酸酯(B-TTI)。探究了不同温度和不同时间下MEKO和TTI的反应程度。研究结果表明:50℃下MEKO与TTI的反应速率较快,封闭完成后体系内游离异氰酸根的含量降至0.05%以下,反应时间为4 h及以上时,产物储存性能较好;确定了解封温度为120℃左右,解封后会伴随着自聚反应的发生,解封后的产物可以与TTI进行快速固化反应;制备的B-TTI作为固化剂加入到TTI中,当m(B-TTI)∶m(TTI)=2∶10时,粘接效果较好,粘接强度可达4.76 MPa。

The blocked triphenylmethane triisocyanate(B-TTI)was prepared by reacting with triphenylmethane triisocyanate(TTI)using methyl ethyl ketoxime(MEKO)as blocking agent.The degree of reaction between MEKO and TTI at different temperatures and different time was explored.The research results showed that at 50℃,the reaction rate between MEKO and TTI was relatively fast.After the blocking was completed,the content of free isocyanates in the system decreased to below 0.05%.When the reaction time was 4 hours or more,the storage performance of the product was good.It was confirmed that the unblocking temperature was around 120℃,selfpolymerization reaction would occur after unblocking,and the products after unblocking could undergo rapid curing reaction with TTI.The prepared B-TTI was added as the curing agent to TTI,when m(B-TTI)∶m(TTI)=2∶10,the bonding effect was good,and the bonding strength could reach 4.76 MPa.