水性聚氨酯是配制水性聚氨酯胶粘剂的基础物质和关键组分，它的性能直接决定胶粘剂的最终性能。根据粒子所带电荷种类，水性聚氨酯可分为阴离子，阳离子，非离子三种类型。水性聚氨酯的制备一般是先合成一定分子量的聚氨酯预聚体，然后在剪切力作用下将预聚体分散在水中。目前其制备方法以亲水单体扩链、自乳化法为主(所谓亲水单体扩链法)，即在聚氨酯预聚体的分子结构中引入亲水性扩链剂，所得聚合物无需外加乳化剂就能直接分散于水中形成水性聚氨酯。亲水单体扩链法的合成工艺有溶剂法、预聚物分散水中扩链法、熔融分散缩聚法等。
早在四、五十年代，水性聚氨酯已有少量的研究，但由于贮存稳定性差等原因，这项研究工作进展不大，直到1972年德国bayer公司正式将聚氨酯水分散液作为皮革涂料后，才开始迅速发展。据报道，1992年至1997年间水性聚氨酯的年平均增长率为8%。
我国从70年开始研究水性聚氨酯，近年来研究工作也十分活跃。研制工作具有以下特点：
(1)从产品结构来看，主要是乳液型，水溶性次之，胶乳型则不常见。
(2)从原料来看，多元醇主要用聚醚型，聚酯型次之，聚碳酸酯极少见。异氰酸酯的品种更少，只有tdi，hdi、mdi仅见报道。扩链剂多用醇类，胺类较少使用。
(3)从制备方法及种类来看，一般是自乳化，羧酸型、阴离子体系;外乳化，磺酸型，季铵盐型乳化体系较少;熔融分散，固体自发分散法等则未涉及。
(4)从理论与应用角度来看，着重应用开发，理论研究很少。
欲配制高性能水性聚氨酯胶粘剂，必须制备高性能水性聚氨酯。大多数水性聚氨酯主要是线性热塑性聚氨酯，由于其涂膜没有交联，分子量较低，因而耐水性，耐溶剂性，胶膜强度等性能还较差。为提高水性聚氨酯的性能，必须对其进行改性。
水性聚氨酯的改性
从水性聚氨酯的制备工艺过程来看，聚氨酯预聚体的分子结构对水性聚氨酯的性能有着决定性的影响。因此其改性主要应从预聚体上做文章，通过改变预聚体的分子结构，分子量大小等等因素而达到改性的目的，以得到高性能水性聚氨酯。
产品英文详情介绍
the aqueous polyurethane formulation is a critical component of the aqueous base material and a polyurethane adhesive, its performance directly determine the final adhesive performance. the electric charge particle type, aqueous polyurethane can be divided into anionic, cationic, nonionic three types. preparation of aqueous polyurethane is generally constant first synthesized molecular weight polyurethane prepolymer, and then under the action of shear forces prepolymer dispersed in water. in the current method of preparing a hydrophilic monomer chain, the main self-emulsification method (so-called chain hydrophilic monomer method), i.e. the introduction of a hydrophilic chain extenders in the polyurethane prepolymer the molecular structure of the resulting polymer without plus emulsifiers can be directly dispersed in water to form an aqueous polyurethane. synthesis of the hydrophilic monomer chain extension of solvent method, the prepolymer water dispersible chain extender, melt polycondensation method or the like dispersed. as early as the forties and fifties, waterborne polyurethane has a small study, but due to poor storage stability reasons, this study is not progress, until 1972 after the german company bayer formally aqueous polyurethane dispersions as leather coatings, only he began to develop rapidly. according to reports, from 1992 to 1997 the average annual growth rate of 8% water-based polyurethane. china began to study water-based polyurethane from 70 years, in recent years, research work is also very active. development work has the following characteristics: (1) from the product structure, mainly emulsion, water-soluble, followed by latex type is not common. (2) from the feed point of view, mainly used polyether polyols, polyester followed polycarbonate rare. less isocyanate species, only tdi, hdi, mdi only see reported. chain extender multi alcohols, amines less use. (3) the method of preparation and type of view, is generally self-emulsifying carboxylic acid type anionic systems; emulsification external less, sulfonic acid, quaternary ammonium salt type emulsifying system; molten dispersion, the solid dispersion method is not spontaneously directed . (4) the theoretical and practical point of view, focusing on application development, theory rarely. to prepare the aqueous polyurethane adhesive of high performance, high performance aqueous polyurethane must be prepared. most of the aqueous polyurethane predominantly linear thermoplastic polyurethane, without crosslinking the coating film due to its lower molecular weight, and thus properties of water resistance, solvent resistance, film strength is also poor. to improve the performance of waterborne polyurethane, which must be modified. modified waterborne polyurethane prepared from aqueous polyurethane process point of view, the molecular structure of the polyurethane prepolymer has a decisive influence on the performance of the aqueous polyurethane. thus it should be modified prepolymer on the main issue, by changing the molecular structure of the prepolymer, molecular size, among other factors to achieve the purpose of the modification, to obtain high performance aqueous polyurethane.
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