氨基硅氧烷改性水性聚氨酯及其乳胶膜的性能

以异佛尔酮二异氰酸酯、聚四氢呋喃二醇、二羟甲基丙酸和三羟甲基丙烷(TMP)等为原料合成了内交联的水性聚氨酯预聚体,用3-氨基丙基三乙氧基硅烷(KH550)进行封端改性,乳化后进一步水解缩合交联,得到了高交联度的水性聚氨酯。采用傅里叶变换红外光谱、热重分析和X射线衍射技术对水性聚氨酯的结构进行了表征,并测试了乳胶膜的力学性能和耐介质性。实验结果表明,合成预聚体的较佳条件:n(—NCO):n(—OH)=1.4、—COOH质量分数1.8%(基于水性聚氨酯)、TMP质量分数1.0%(基于水性聚氨酯);当KH550质量分数(基于水性聚氨酯)由0增至10.0%,乳胶膜的拉伸强度由18 MPa增至28 MPa,吸水率由17%降至8%,吸乙醇率由46%降至30%以下。表征结果显示,KH550上的—NH_2与水性聚氨酯的端—NCO发生反应,实现了化学改性;KH550使乳胶膜的耐热性明显提高;随KH550含量的增加,乳胶膜的结晶度下降。

Structure and Properties of Waterborne Polyurethane Modified with 3-Aminopropyltriethoxysilane and Its Films

Waterborne polyurethane (WPU) prepolymer was prepared by reaction of isophorone diisocyanate, polytetramethylene glycol, dimethylol propionic acid and trimethylol propane (TMP), and was further modified by 3-aminopropyltriethoxysilane (KH550) followed by successive emulsifying, hydrolysis,condensation and crosslinking to form highly crosslinked WPU. The films of WPU were prepared by casting emulsion on Teflon surface. Structure of WPU was characterized by means of FTIR, TG and XRD. The Mechanical properties and resistance to medium of the cast films were also measured quantitatively. Optimal reaction conditions were as follows: n (-NCO) : n (-OH) 1.4, w(-COOH) (based on WPU) 1.8% and w(TMP)(based on WPU) 1.0%. As w(KH550)(based on WPU) increased from 0 to 10.0%, the tensile strength of WPU film increased from 18 MPa to 28 MPa, water absorption decreased from 17% to 8%, ethanol absorption decreased from 46% to 30%. FTIR indicated that -NH_2 of KH550 reacted with -NCO of WPU. TG analysis indicated that KH550 improved thermal stability of WPU. XRD showed that crystallinity of WPU decreased with the increase of w(KH550).