酮肼交联及硅烷偶联水性聚氨酯的成膜机理及其性能研究

用二乙醇胺(DEA)和双丙酮丙烯酰胺(DAAM)按Michael加成反应机理合成了一种新的聚氨酯扩链剂DDP(N-[(1,1-二甲基-2-乙酰基)乙基]-β-二羟乙氨基丙酰胺).以异佛尔酮二异氰酸酯(IPDI)、聚四氢呋喃二醇(PTMG1000)、二羟甲基丙酸(DMPA)、三羟甲基丙烷(TMP)等为主要原料,在用γ-氨基丙基三乙氧基硅烷(KH550)封端改性聚氨酯的基础上,采用自制含酮羰基二元醇N-[(1,1-二甲基-2-乙酰基)乙基]-β-二羟乙氨基丙酰胺(DDP)和1,4-丁二醇(BDO)作为扩链剂,制备了侧链含酮羰基的聚氨酯乳液.通过外加己二酸二酰肼(ADH),制得室温自交联乳液.利用衰减全反射红外光谱(ATR-FTIR)和核磁共振波谱(NMR)对扩链剂(DDP)和涂膜结构进行表征,ATR-FTIR和NMR测试证实了DDP的生成并参与反应合成了聚氨酯及乳液成膜时酮肼交联反应的发生.研究了n(—NHNH2)/n(—CO—)、n(NCO)/n(OH)、DDP含量对聚氨酯涂膜性能的影响.结果表明,在己二酸二酰肼(ADH)的用量为0时,涂膜的吸水率随DDP含量的增加而增大;n(NCO)/n(OH)1.40时,聚氨酯难以乳化并且乳液稳定性变差;在最佳配比n(—NHNH2)/n(—CO—)=1,n(NCO)/n(OH)=1.40的条件下,DDP%从0增大到7.22%时,涂膜的吸水率从39.36%降低到18.92%同时表现出很好的耐溶剂性能,交联度从51.49%上升至90.23%,拉伸强度从20.09MPa增大到28.26MPa,硬度达2H.热失重分析(TGA)表明酮肼交联结构的引入提高了涂膜的热稳定性.

FILM-FORMING MECHANISM AND PROPERTIES OF KETONE HYDRAZINE CROSSLINKED AND SILANE COUPLED WATERBORNE POLYURETHANE

A new crosslinker for polyurethane,DDP(N-[(1,1-dimethyl-2-acetyl)ethyl]-βdihydroxyethylamino propanamide),was synthesized by Michael reaction between diethanolamine(DEA) and diacetone acrylamide(DAAM).Self-crosslinkable aqueous polyurethane emulsion containing active keto groups was obtained using isophorone isocyanate(IPDI),poly(tetramethylene oxide)(PTMG1000),dimethylol propionic acid(DMPA) and trimethylol propane(TMP) as main materials,both dihydroxyketon N[(1,1-dimethyl-2-acetyl)ethyl]-β-dihydroxyethylamino propanamide(DDP) and 1,4-butanediol(BDO) as chain expanders,γ-aminopropyltriethoxysilane(KH550) as end capping agent and then adipic acid dihydrazide(ADH) was added into the emulsion.The structures of the crosslinker DDP and films were characterized by ATR-FTIR and NMR.The tests results confirm the formation and reaction of DDP.The result of ATR-FTIR also shows that the crosslinking reaction between ketone group and the hydrazine group has happened during the film curing.The effects of n(—NHNH2)/n(—CO—),n(NCO)/n(OH) and DDP content on the properties of the films were studied.The results show that,water absorption of polyurethane films without adipic dihydrazide(ADH) increases with the increase of DDP content;it is difficult to emulsify polyurethane polymer and the stability of the emulsion is deteriorated significantly in the case of n(NCO)/n(OH)﹥ 1.40.Under the optimal ratios(n(—NHNH2)/n(—CO—) = 1,n(NCO)/n(OH) = 1.40),when DDP content increases from 0% to 7.22%,water absorption of the films decreases from 39.36% to 18.92% also with higher performance in solvent resistance,crosslinking degree increases from 51.49% to 90.23%,tensile strength increases from 20.09 MPa to 28.26 MPa,pencil hardness is 2H.Thermogravimetic analysis(TGA) indicates that the Ketone-Hydrazide crosslinking structure can improve thermal stability of the films.