Preparation And Properties Of Polyurethane Adhesive For PE/Book Binding

Polyurethane adhesive has excellent shear strength, impact properties, lfexibility, lowtemperature performance, which is an important component of polyurethane resin and hasbeen widely used in many ways. The paper studied the preparation and properties oftwo-component polyurethane adhesive for PE and UV/moisture dual curable polyurethanehot melt bookbinding adhesive.With polyester polyol, isocyanate mixture（MDI/TDI）, chain extender （1,2-propanediol）as the material, prepolymer was prepared by bulk polymerization. Prepolymer wasdissolved in ethylacetate, then added acertain amount of tackifier and curing agent, thetwo-component polyurethane adhesive was prepared, which had good adhesive propertieson corona treated PE（polyethylene）. The influence of R（NCO/OH）, isocyanate, thefunctional polyol, hard segment, catalyst, the proportion of polyether were discussedrespectively, all products were characterized by Fourier Transformed-Infrared spectroscopy（FT-IR） and Differential Scanning Calorimeter （DSC）.The results showed that the prepolymer’s relative molecular mass can reach90000¹10000g.mol^-1, the two-component polyurethane adhesive had good strength, when m （crystalline polyester polyol）: m （non-crystalline polyester polyols） was80:20to60:40, m （MDI）: m （TDI） was90:10to60:40, R （NCO/OH） was0.95to0.97, and theamount of catalyst was0.01%, adding4%PTMEG to the soft segment and hard segmentcontent was14%, the mass fraction of polyester polyol XCP-2325was2%. Thetwo-component PU adhesive had a good performance of operation, the viscosity of theproduct can reach22mPa.s, the initial180°peel strength2.3N.（25mm）^-1", final180°peelstrength41N·（25mm）^-1 when the solid content of the solvent-ethyl acetate was12%, together with a tackiifer and a curing agent.At present, the hot melt bookbinding adhesives were mainly EVA hot melt adhesiveand polyurethane hot melt adhesive. The flexibility of EVA hot melt adhesive is not good, itis easy to be fragmentary in low temperature, and soften in high temperature. The initialstrength of polyurethane hot melt adhesive is low, it will impact the bookbinding speed. Inorder to solve these problems, the light curing system was introduced to themoisture-curing polyurethane systems to enhance the initial strength, and a UV/moisturedual curable polyurethane hot melt bookbinding adhesive was prepared. With polyester polyol, isocyanate, hydroxyl-containing acrylate and photoinitiator asraw materials, a UV/moisture-cuirng polynrethane hot melt bookbonding adhesive wasprepared. Effect of homemade polyester polyol, n（C=C）: n（NCO）, photo-initiator, UVirradiation time was discussed, all products were characterized by FourierTransformed-Infrared spectroscopy （FT-IR） and Differential Scanning Calorimeter （DSC）,the performance of adhesive were tested with dynamic mechanical analysis（DMA）.The results showed that35%homemade polyester polyol was added to soft segment,n （C=C）: n （NCO） was40:60,1.5%。of819as a photoinitiator, UV （irradiation intensityof100W/cm） irradiation time was30s, the initial strength of adhesive was good, and thenAfter5days of the moisture curing, the adhesive had good performance. Adding30%MDIinto adhesive, which can effectively improve the adhesive’s degree of crosslinking and thetensile strength of adhesive. Its melt viscosity was7800mPa.s at120°C5the initial strengthof4.2MPa after UV irradiation, the ultimate tensile strength of12.1MPa atfer moisturecuring, elongation at break was400%, the hardness of83A. The product had beensuccessfully tested, the properties of product conformed to the requirements of application.