六甲氧基甲基三聚氰胺-多元醇-丙烯酸酯混杂聚合体系的研究

STUDIES ON HYBRID POLYMESIZATION OF HEXAMETHOXYMETHYL MELAMINE-POLYOL-ACRYLATE

六甲氧基甲基三聚氰胺 (HMMM) 多元醇 丙烯酸酯 酸催化剂混杂聚合体系在高温下同时进行缩聚和自由基聚合并表现出协同效应 .体系中的活泼亚甲基在HMMM的催化下被空气氧化成过氧化氢物 ;过氧化氢物在酸催化下分解成自由基进而引发自由基聚合反应 .研究结果表明 ,体系中存在固化加速的协同效应 ;同时体系中还存在热互补效应 ,丙烯酸酯的自由基聚合反应放出的热可以传递给缩聚反应 ,满足缩聚反应吸热的要求 .混杂聚合得到的高分子合金膜具有优良的机械性能和耐溶剂性能 ,这是由于在混杂聚合过程中形成了互穿聚合物网络 (IPN)结构 .使用潜酸催化剂作为酸的来源 ,可以提高体系的储存稳定性 ;交联 引发剂的使用可以拓宽它的使用范围 ;

Research on the novel hybrid polymerization system of hexamethoxymethyl melamine (HMMM)-polyolacrylate-acid has been reviewed. The hybrid system involves a condensation reaction of HMMM and free radical polymerization of acrylate, although there is no free radical initiator in the compositions. It is suggested that active methylene groups can be oxidized to the corresponding hydroperoxide through a charge transfer complex (CTC) between HMMM and O-2 in the air. Catalyzed by acid, the hydroperoxide decomposes rapidly, generates free radicals and then initiates the free radical polymerization. There are some synergetic effects between the radical polymerization and condensation reaction. First, the curing rate could be enhanced greatly. Secondly, DSC trace. of the hybrid polymerization system demonstrates that there is obvious energy compensation effect in the system. The released energy of the free radical polymerization of acrylate can be transferred to the endothermic condensation reaction of HMMM. Thirdly, the properties of cured film, such as mechanical properties and solvent-resistance, are greatly improved. It is demonstrated that the improvement is caused by the formation of polymer alloys with IPN (Interpenetrating polymer network) structure in-situ via dynamic mechanical thermal analysis ( DMTA) and transmission electron microscope (TEM) An addition, acrylate can adjust the viscosity of the formulation and reduce the use of volatile organic compound (VOC) To make the formulation more flexible, some new compounds containing very active methylene groups and hydroxyl group such as diethylene glycol allyl ether and diethylene glycol benzyl ether were synthesized and used as the crosslinker-initiators in the hybrid polymerization system. To increase the shelf-time of the formulation, latent acid catalysts trans-2-hydroxycyclohexyl-p-toluenesulfonate and pyridine p-toluenesulfonate, were used as the source of acid in the hybrid formulations. The application of hyperbranched polymers in hybrid polymerization system is under study. Consequently, the hybrid polymerization system of HMMM-polyol-acrylate-acid is promising to formulate a high curing rate, low solvent content, energy conservation and high quality coating.