Synthesis And Curing Of The Silyl-terminated Polyurethane

Polyurethane is a class of polymers which contains repeated carbamate in its main molecular chain.It is widely used in th field of adhesives for its excellent flexibility, wear resistance and good adhesion to the substrate and so on.The silicones have good ageing resistance as well as its long lifetime.Combination of the two can synthesis a kind of silylated polymers with excellent high temperature resistance,moisture proof,water proof,defoaming property,demoulding and physiological inertia,and some special variety with radiation resistance,oil resistance,solvent resistance and other characteristics.In this paper we discuss the synthesis and curing method of a new type sealant material.Use the polyether polyols and TDI as raw material to produce a kind of polyurethane prepolymer,which occurs a substitution reaction with some silane coupling agent, finally the silicon-modified polyurethane sealant with silicane as the terminal group is available.During the reaction process,we choose polyurethane polyols with different functionality,and compare each product with other.Use FTIR to analyse the products by difunctional,trifuntional polyurethane polyols and their mixtures,to find the differences of their functional groups.Test the rheological property of the polyurethane polyols in order to search the influence caused by different raw materials.This article also studies on curing behaviour of the silicon-modified polyurethane sealant.The curing formula including catalyst(butynorate), accelerator, fillers(calcium carbonate and silica),and toluene as solvent to reduce the viscosity when necessary.By changing the formula,we make analysis and comparison of a series of sealants on the curing time,tensile strength,shear strength,rheological property, ect.And try to seek some regularity.At the same time we study on the influencing factors including the environment temperature,humidity,surface treatment of fillers to find their effect.We find that as the ambient temperature and humidity increasing,the curing time of silicon-modified polyurethane sealant shortening.Using the calcium carbonate with surface treatment as filler could make sealant with better performance.With the increase of curing catalyst dosage,the tensile strength and hardness of the sealant first increased and then decreased,and the elongation rate keep increasing.