封闭型异氰酸酯交联剂的制备及其固化行为的研究

THE PREPARATION AND THE CURING BEHAVIOR OF BLOCKED ISOCYANATE CROSSLINKERS

合成了 5种封闭型的异氰酸酯交联剂。用动态扭辨分析 ( TBA)测定交联剂与聚丙烯酸酯固化的宏观性能 ,固化分为两阶段。用 in Situ FT- IR研究了固化反应的分子机构 ,得出第一阶段是封闭的小分子脱去后 ,异氰酸根向聚丙烯酸酯上的羟基转移的固化反应 ;第二阶段是解封后的氰酸根向氨基甲酸片段上的氢转移的深度固化反应。用计算机模拟得到了交联剂分子的最低能量构象图 ,提出了封闭型 TDI交联剂由于空间位阻效应而发生了三官能团式的交联固化反应。

Five blocked tolunene diisocyanate(TDI) crosslinkers were obtained in this article. The curing behavior of these crosslinkers with polyacrylate was studied by TBA in dynamic mechanical angle, we find out the curing process is divided into two steps. Associated with datum from in Situ FT IR at molecular level, the first step is the reaction of deblocked NCO and hydroxy in polyacrylate and at second step the deblocked NCO can attack the hydrogen in to form the deep curing. The computer modeling was induced to get the lowest energy geometry of the crosslinker molecule. We discover that the NH CO space hindered effect in themolecule that causes the type of three group crosslinking curing in blocked TDI crosslinker.