硅烷化聚氨酯预聚体的合成及其固化物的性能

在无溶剂条件下采用聚氨酯(PU)预聚体法合成端—NCO基PU,再与活性硅烷进行封端反应,制备了硅烷化聚氨酯(SPU)预聚体。考察了聚醚二元醇(PPG)的数均相对分子质量(Mn)、异氰酸酯种类、n(NCO)∶n(OH)和硅烷封端剂种类对SPU预聚体固化物(简称固化物)性能的影响。实验结果表明,通过改变PPG的Mn、异氰酸酯种类、n(NCO)∶n(OH)和硅烷封端剂种类可制备符合设计性能要求的SPU预聚体。室温下SPU预聚体固化得到无气泡、无针孔的均质胶膜,且其指干时间比PU短,固化物疏水性能提高;红外光谱表征结果表明,采用仲氨基硅烷(S IL-3)封端后,产物的—NCO基吸收峰消失。当采用Mn为4000的PPG与1,6-六亚甲基二异氰酸酯在n(NCO)∶n(OH)=1.80的条件下反应,再经SIL-3封端后得到的固化物拉伸强度为0.30M Pa,断裂伸长率为120%。

Preparation and Properties of Siloxane End-Capped Polyurethane

Isocyanate end-capped polyurethane(PU) was synthesized in absence of solvent and further reacted with active siloxane to prepare siloxane end-capped polyurethane(SPU) prepolymer.Effects of number average relative molecular mass(Mn) of polypropylene glycol(PPG),isocyanate types,n(NCO) ∶n(OH) and siloxane types on properties of cured SPU prepolymer resin(cured resin) were investigated.The cured resin films with hydrophobicity,free of bubbles,pinpricks and spots,can be obtained at room temperature.Tack-free time of the cured resin is shorter than that of PU resin.The IR absorption peak of isocyanate radical disappeared after end-capping reaction between PU and secondary amino siloxane(SIL-3).PPG(Mn 4 000) reacted with hexamethylene diisocyanate(HDI) at n(NCO) ∶n(OH) 1.80,and was end-capped with SIL-3 to produce SPU.Tensile strength and elongation at break of the cured resin are 0.30 MPa and 120%,respectively.