Study On Preparation And Properties Of Thermoplastic Polyurethane Hot Melt Adhesive

It is much favor that thermoplastic polyurethane hot-melt adhesive is solid, easy packaging, transportation, storage, no solvent, no pollution, and production process has the advantages of simple operation, good flexibility, high adhesive strength, curing fast speed, and is suitable for high speed bonding from the production of the circulation, no pollution to the environment, so it is rapidly developed in the application. Seeking for high softening point, good thermal stability and high molecular weight of thermal plastic polyurethane hot melt adhesive becomes a hot research in the polyurethane industry.In this study,with polyester polyol adipic acid-1,4- polybutylene terephthalate(PBA) as soft segment, diisocyanate MDI, chain extender 1,4- butylene glycol as hard segment, dibutyltin dilaurate and triethylenediamine as catalyst, thermoplastic polyurethane hot melt adhesive was synthesized, which has reasonable molecular weight, high softening point, high adhesive strength and good heat thermal stability. Through studying on the synthesis process, isocyanate MDI, polyester polyol and chain extender content of thermoplastic polyurethane hot melt adhesive, it was discussed its composition, structure of soft and hard segments, isocyanate index(R) for the effect of polyurethane hot melt adhesive properties, and tested its molecular weight, softening point and adhesive strength. The results show that: the polyurethane prepolymer synthesis temperature at 70℃~75℃, reaction time about 2 hours, the chain extending reaction time about 30 minutes, aging temperature at 100~110℃ for 2~3 hours, when R is 1.02, the dosage of chain extender 1:0.7(polyol /BDO molar ratio), thermoplastic polyurethane hot melt adhesive was synthesized. Its molecular weight are Mn3.91?104 and Mw7.61?104, softening point is 139℃, adhesive strength is 25.66 MPa. Through testing GTA and adhesive strength, the results show that, polyurethane hot melt adhesive strength of polyesterpolyol is better, and the molecular weight of polyols higher, the synthesis polyurethane hot melt adhesive strength greater. In contrast to different kinds of chain extenders, its thermal stability order is butylene glycol, propylene glycol, ethylene glycol.