Preparation Of PE-g-MAH Hot Melt Adhesives And Mechanism Of Action Of Tackifiers In It

Hot-melt adhesives(HMAS)for steel-plastic composite pipes is a bond resin which can bond polyolefin plastic and wire/steel strip metal layers well,its most important property is the bonding strength between metal and polyethylene resin layer.How to prepare a bond resin with high peel strength is a problem that the industry has always wanted to solve.It is found that the Hot-melt adhesives with better market-oriented adhesives are mostly maleic anhydride(MAH)grafted polyethylene(PE-g-MAH)Hot-melt adhesives,and the modified PE-g-MAH grafted adhesive can be used as the main component of the hot melt adhesive.The research on PE-g-MAH graft has been reported in a large number of literature here and abroad.It has been widely used and studied in Hot-melt adhesives,pressure sensitive adhesives,compatibilizer and so on.However,there are different studies on the influencing factors,but few studies can systematically study the impact of their influencing factors.In this paper,orthogonal experiments are designed to optimize the preparation of high-performance PE-g-MAH grafts.The effects of reaction temperature and initiator concentration on the properties of Hot-melt adhesives were systematically studied,and the influencing factors of peel strength test methods were studied and improved.The optimum test conditions were determined by designing orthogonal experiments.The results showed that the peeling strength was affected by two factors: grafting ratio and melting index of products.Grafting ratio affects the number of polar groups and surface tension,melt index affects melt fluidity and coating,and these two factors interact with each other.The peeling strength must be the result of these two factors.When measuring peel strength,the coating method,hot-pressing temperature and adhesives layer thickness may affect the internal structure of the adhesive layer,resulting in inaccurate peel strength data.Tackifier is a kind of small molecule with weak polarity,which is widely used as auxiliary agent in various adhesives or rubber elastomer.It can improve the wettability of adhesives and make them fully in contact with each other.So as to improve the peel strength.Industrial preparation of hot melt adhesive to add tackifier is mostly just to adjust the viscosity,The mechanism of how the tackifier in the PE-g-MAH Hot-melt adhesives affects the peeling strength of the adhesive is hardly studied.Hot-melt adhesives were prepared by blending tackifiers with different softening points in PE-g-MAH grafts,and the mechanism of the effect of the tackifiers on the peel strength of Hot-melt adhesives was studied through a series of tests.The effect of tackifiers on the properties of Hot-melt adhesives was compared.The research result indicated that the HMAS with tackifier has higher T-peel strength than those without in a certain SP range.The addition of tackifier reduced the crystallinity and shrinkage of HMAS.Hot melt with higher softening point of tackifier resin has higher melt index.Analysis of the results of the study:Tackifiers solidify in advance during the cooling process,hinder the movement of PE-g-MAH molecular chains,increased the viscosity of hot melt adhesives,thereby reducing the crystallinity and shrinkage of hot melt adhesives and maintaining the interface integrity.Increased the peel strength of hot melt adhesives on metal surfaces.