【作者】 夏会华；

【导师】 许戈文；

【作者基本信息】 安徽大学 ， 化学工程， 2013， 硕士

【摘要】 水性聚氨酯以水代替有机溶剂作为分散介质,具有安全、节能、环保等优良性能,是近年来发展较为迅猛的新型绿色环保材料。水性聚氨酯是由柔性的软段链和刚性的硬段链交替连接而成的嵌段共聚物。软段由大分子多元醇(聚醚或聚酯多元醇)构成,硬段由多异氰酸酯和小分子扩链剂等构成。所以,聚氨酯的软段和硬段结构对水性聚氨酯的性能有着直接或间接的影响,在聚氨酯中,只有当刚性链段的内聚能足够大,才能彼此缔合在一起形成硬段,影响刚性链段内聚能的因素有二异氰酸酯、扩链剂和交联剂的种类和用量。本文主要探讨了二异氰酸酯、交联剂和小分子扩链剂的种类对水性聚氨酯乳液粒径、红外结构、耐热、力学以及耐水等性能的影响。(1)二异氰酸酯种类对水性聚氨酯性能的影响本章分别采用异佛尔酮二异氰酸酯(IPDI)、甲苯二异氰酸酯(TDI)、二苯基甲烷二异氰酸酯(MDI)、二环己基甲烷二异氰酸酯(HMDI),和聚醚二元醇(N210和N220)、二羟甲基丙酸、一缩二乙二醇为主要原料合成了一系列不同多异氰酸酯结构的水性聚氨酯。通过乳液粒径、红外、DMA、力学、硬度、耐水、耐酸碱等结构和性能的测试,研究了二异氰酸酯种类的变化对水性聚氨酯在上述结构和性能上的影响。着重研究了水性聚氨酯的N-H伸缩振动吸收峰的变化与不同结构二异氰酸酯之间的关系。研究结果表明,芳香族异氰酸酯相对于脂肪族异氰酸酯而言,合成的聚氨酯乳液粒径大,聚氨酯胶膜的拉伸强度和硬度较高,耐水耐酸碱腐蚀性能较好；从水性聚氨酯的N-H伸缩振动吸收峰的分峰结果可以看出,不同二异氰酸酯种类对水性聚氨酯体系的氢键作用力有较明显的影响,芳香族聚氨酯体系的氢键作用力强度比脂环族的大,分子链规整的体系氢键化程度较高,空间位阻使聚氨酯结构的氢键化程度降低；DMA测试表明,芳香族异氰酸酯分子中刚性芳环的存在以及生成的氨基甲酸酯键赋予聚氨酯较强的内聚力,导致玻璃化温度提高,故硬段Tg较脂肪族异氰酸酯要高。(2)交联剂种类对水性聚氨酯性能的影响本章采用异佛尔酮二异氰酸酯、聚醚二元醇(N210和N220)、二羟甲基丙酸和一缩二乙二醇为主要原料,分别以聚醚三元醇N330、蓖麻油(C.O)、三官能度的三羟甲基丙烷(TMP)、四官能度的季戊四醇(PER)为交联剂,合成了一系列水性聚氨酯,探讨了不同种类的交联剂对水性聚氨酯乳液的粒径、乳液的稳定性,对聚氨酯胶膜的力学性能、胶膜的耐水性能、胶膜的耐热性能及玻璃化转变温度等的影响。研究表明,交联后的水性聚氨酯乳液平均粒径有所增大；大分子交联剂形成的聚氨酯结构分子链段较为柔软,交联改性后的聚氨酯胶膜手感较好；适当的交联有利于提高聚氨酯的力学性能、耐热性能和耐水性能,交联密度过大反而会破坏这些性能；小分子交联剂使得聚氨酯硬段Tg向高温移动,大分子交联剂阻碍了硬段的聚集作用,使硬段Tg向低温移动。(3)小分子扩链剂种类对水性聚氨酯性能的影响本章主要采用具有不同碳链长度的直链型扩链剂、不同侧甲基团数目以及具有醚氧基团的小分子扩链剂制备了一系列水性聚氨酯。通过乳液粒径、红外结构以及耐水、拉伸性能测试对水性聚氨酯的性能进行了表征。研究结果表明,支链的增加有利于获得分布窄、粒径小的聚氨酯乳液,随着分子链规整度的提高,乳液粒径增大,分布变宽；直碳链的扩链剂随着碳链的增长,聚氨酯结构中硬链段密度减小,微相分离程度降低,聚氨酯胶膜的力学性能下降,断裂伸长率提高；醚键的存在增加了分子链的柔顺性,使得拉伸强度减小硬度降低；带侧基的扩链剂由于硬段规整度降低,聚氨酯的拉伸强度和硬度明显降低,且使聚氨酯体系的氢键作用力减弱,因此吸水率较高,耐水性能下降。更多还原

【Abstract】 Waterborne polyurethane uses water instead of organic solvent as dispersion medium,with the excellent performance of safety、energy conservation、environmental protection etc.,it becomes one of the new green materials which develop more and more rapidly in recent years.Waterborne polyurethane is a block copolymer made of the flexible soft chain segment and the rigid hard chain segment.The soft segment consists of polyether glycol or polyester polyol,the hard segment consists of the isocyanate and small molecule chain extender, et al.Thus,the structure of soft and hard segments affect the performance of waterborne polyurethane directly or indirectly.In the structure of polyurethane, the rigid chains form the hard segment by the cohesive energy.There are several factors that can affect the cohesive energy of the rigid chain segments, such as the kind and amount of diisocyanate、the chain extender and the crosslinker. This paper mainly discusses the affect of the type of diisocyanate、crosslinking agent and small molecule chain extender on the performance such as emulsion particle size、 infrared structure, hea、mechanical and water resistant of waterborne polyurethane.(1)The affect of diisocyanate type on the performance of waterborne polyurethaneThis chapter respectively used isophorone diisocyanate (IPDI). toluene diisocynate(TDI)、diphenyl methane diisocyanate (MDI)、dicyclohexylmethane diisocyanate (HMDI), and polyether glycol(N210and N220)、dimethylolpropionic acid、diethylene glycol as the main raw material for synthesising a series of water-based polyurethane.Structure and performance test of emulsion particle size、 infrared、DMA、mechanics、hardness、water resistant、acid and alkali resistant were made,the type of diisocyanate on the structure and properties of waterborne polyurethane was studied.This chapter mainly focused on the relationship between N-H stretching vibration absorption peak and the structure of diisocyanate.The research results showed that the aromatic isocyanate with respect to the aliphatic isocyanate,the polyurethane emulsions had a larger particle size, the polyurethane films had higher tensile strength and hardness,better water resistance and corrosion resistance;from the peak split results of the N-H telescopic vibration absorption peak, different kind of diisocyanate had an obvious effect on the hydrogen bonding of waterborne polyurethane systems, the hydrogen bonding strength of aromatic polyurethane system was stronger than that of aliphatic isocyanate, high degree of molecular chain structured system had a higher hydrogen bonding degree, stereo-hindrance effect could reduce the degree of hydrogen bonding; DMA tests showed that, polyurethane synthesised of aromatic isocyanate has a strong cohesion because of the exist of the rigid aromatic ring as well as the resulting carbamate key,resulting in the rise of the glass transition temperature, so the glass transition temperature of the hard segment was higher than polyurethane synthesised of aliphatic isocyanate.(2) The affect of crosslinking agent type on the performance of waterborne polyurethaneThis chapter used isophorone diisocyanate、polyether glycol(N210and N220)-. dimethylolpropionic acid、diethylene glycol as the main raw materials, then respectively added polyether triol N330、castor oil (C.O.)、 trimethylolpropane (TMP)、pentaerythritol (PER) as the crosslinking agent, synthesised a series of waterborne polyurethane.Discussed the effect of crosslinking agent type on the particle size and stability of the emusions, the mechanical properties、 the water resistance、the heat resistance and the glass transition temperature of the films.The study showed that the average particle diameter of the crosslinking aqueous polyurethane emulsion had increased; polyurethane structure of molecular chains formed of macromolecular crosslinking agent was relatively soft, the crosslinked polyurethane films felt good; suitable crosslinking could improve the mechanical properties、heat resistance and water resistance of polyurethane, over cross-linking could destroy these performances; small molecular cross-linking agents made the glass transition temperature of the hard segment higher,while macromolecular crosslinking agents hindered the gather of rigid chains,making the glass transition temperature of the hard segment lower. (3) The affect of small molecule chain extender type on the performance of waterborne polyurethaneIn this chapter, series of WPU were synthesized using several types of chain-extender agents, such as straight-chain type chain extenders with different length of carbon chain, chain extenders with different numbers of side methyl group, and chain extenders with ether oxygen groups. Prepared WPUs were characterized through tests of particle size、infrared spectrum、thermostability、water resistance and tensile property;as for straight carbon chain of the chain extender, with the increase of carbon chain, hard segments in the polyurethane structure density decreased, the degree of micro-phase separation reduces,making the mechanical properties of the polyurethane film declined, the flexibility of the molecular chain increased; the existence of ether bond increased the flexible of molecular chains,thus decreasing the tensile strength and hardness, improving the elongation at break;the chain extender with side groups, due to the lower tacticity of hard segment,the tensile strength and hardness of the polyurethane was significantly reduced, and the hydrogen bonding of the polyurethane system was weakened, therefore water absorption increased, water resistant performance declined.更多还原