Preparation Of Single-component Moisture-curing Polyurethane Automotive Sealant

Sealant is a kind of curing material which can fill the gap on the spot and bondseams in room temperature. Before curing, pasty sealant can be extruded to fill thegap. After curing, the sealant turns into elastomeric, playing the role of interfacialadhesion, anti-leakage, waterproof, dustproof, withstand vibration,displacement caused by expansion on heating and contraction oncooling,etc.Single-component moisture-curing polyurethane sealant consist ofisocyanate-terminated polyurethane prepolymer, filler and other additives,composedby reaction with moisture in the air and isocyanate curing. Since the technology forpreparing high quality single-componment polyurethane sealant in our country is farfrom the advanced technology in the world, this thesis focuxed on this technology.The specific contents are as follows:First of all, this thesis polyurethane prepolymers were synthesized andcharacterized.Via systematic research on the factors that influence the synthesis ofpolyurethane prepolymers (temperature, time, NCO content, catalyst selection andits dosage), we optimized the synthesis conditions,it was found that polyurethaneprepolymers based on diphenylmethane4,4’-diisocyanate (MDI) and mixture ofpolyether polyols, wherein the polyether polyols was compound by polyether dioland triol prepared from a certain proportion.We developed a process for polyurethane prepolymers with suitable viscosityand outstanding comprehensive performance, Polyurethane sealant was produced bymixing polyurethane prepolymer, fillers, plasticizer, carbon black and catalysts etc.The effect of filler, polyols, carbon black, fumed silica, catalyst etc on theperformance of polyurethane sealant. Tensile strength, elongation, tear strength,extrudabity and hardness etc were measured to evaluate its comprehensiveperformance. We developped the high-strength auto windscreen sealant(ZD-121), middle-strength auto windscreen sealant(ZD-122), the side and rear window glass sealant(ZD-131), and compared the properties in detail with relative products fromdomestic and foreign well-known manufacturers. It was found that these threemodels of sealant solved the problem of poor the mechanical properties and easingof bubbling which were ubiquitous in the same model of sealant that made at home.The comprehensive properties between it and the international leading level wereneck and neck.