本文關(guān)鍵詞： 水性聚氨酯 乳化劑 內(nèi)外協(xié)同 耐水性　出處：《北京化工大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：水性聚氨酯(WPU)是一種以水作為分散介質(zhì)的聚氨酯乳液體系,相比于傳統(tǒng)的、以有機(jī)溶劑作為分散介質(zhì)的聚氨酯材料,WPU具有綠色無污染、安全可靠的優(yōu)點(diǎn),因此具有廣闊的發(fā)展前景。但是,以水作為分散介質(zhì),致使WPU膠膜的耐水性能下降,限制了WPU材料在各領(lǐng)域的應(yīng)用。因此,明確水性聚氨酯結(jié)構(gòu)與性能的關(guān)系,采用切實(shí)可行的新工藝、新方法,提高水性聚氨酯的耐水性,有助于拓展水性聚氨酯的應(yīng)用領(lǐng)域,改善聚氨酯材料生產(chǎn)和應(yīng)用環(huán)境。本文首先用自乳化法制備出IPDI型水性聚氨酯,探究了聚氨酯預(yù)聚體合成工藝對WPU的乳液性能及其所制得膠膜的耐水性與力學(xué)性能的影響,明確了水性聚氨酯結(jié)構(gòu)及其性能之間的關(guān)系。通過預(yù)聚體的不同合成工藝研究,發(fā)現(xiàn)一步法合成時(shí),制備的聚氨酯預(yù)聚體,乳化容易,乳化后可得到性能良好的聚氨酯乳液,同時(shí)膠膜的耐水性和力學(xué)性能優(yōu)良。然后通過一步法合成預(yù)聚體,研究了軟段含量、親水?dāng)U鏈劑加入量和后擴(kuò)鏈劑加入量對乳液和膠膜性能的影響,研究發(fā)現(xiàn),當(dāng)Ri=2.5-3.5, DMBA加入量為3.5%-4.7%,DETA的加入量為100%時(shí),可制得綜合性能優(yōu)異的IPDI型水性聚氨酯。其次,通過在水性聚氨酯的制備過程中加入高分子乳化劑,利用內(nèi)外協(xié)同效應(yīng)可以制備耐水性較強(qiáng)的水性聚氨酯,探究了不同的內(nèi)外乳化劑比例以及乳化時(shí)間對膠膜耐水性的影響,研究發(fā)現(xiàn)當(dāng)R1值為2.5,內(nèi)乳化劑添加量為3.6%,外乳化劑的添加量為0.5%,外乳化劑反應(yīng)時(shí)間為10min,DETA的加入量為100%時(shí),可獲得耐水性較好的膠膜,此時(shí)吸水率為4.1%,具有優(yōu)于傳統(tǒng)內(nèi)乳化法同等條件下制備的WPU材料的吸水率(為19.2%)。并對最優(yōu)耐水性配比下的聚氨酯材料的基本性能進(jìn)行了表征,發(fā)現(xiàn)此時(shí)膠膜的的力學(xué)性能及熱性能較傳統(tǒng)內(nèi)乳化型膠膜的性能基本無變化。最后,探究了內(nèi)外協(xié)同乳化法提高WPU耐水性的機(jī)理,原因可能有兩方面,一是外乳化劑的加入改善了水性聚氨酯的乳液性能,膠粒的粒徑降低,成膜時(shí)膠粒融合緊密,成膜后空隙較少,水分子難以侵入膠膜內(nèi)部,使膠膜耐水性提高；二是外乳化劑在膠膜干燥的過程中,會(huì)在表面能的驅(qū)使下運(yùn)動(dòng)到膠膜表面,對表面親水基團(tuán)進(jìn)行包埋,使膠膜表面與小水珠的接觸角增大,降低表面張力。
[Abstract]:Waterborne polyurethane (WPU) is a kind of polyurethane emulsion system with water as the dispersing medium. Compared with the traditional polyurethane material with organic solvent as the dispersing medium, WPU has the advantages of green, pollution-free, safe and reliable. Therefore, there is a broad prospect for development. However, the water resistance of WPU film decreases due to the use of water as dispersing medium, which limits the application of WPU materials in various fields. Therefore, the relationship between the structure and properties of waterborne polyurethane is clarified. It is helpful to expand the application field of waterborne polyurethane by adopting feasible new process and new method to improve the water resistance of waterborne polyurethane. In this paper, IPDI type waterborne polyurethane was prepared by self-emulsifying method. The effects of polyurethane prepolymer synthesis process on the emulsion properties of WPU and the water resistance and mechanical properties of the film were investigated. The relationship between the structure and properties of waterborne polyurethane was clarified. Through the study of the different synthesis process of the prepolymer, it was found that the polyurethane prepolymer prepared by one-step synthesis was easy to emulsify, and the polyurethane emulsion with good properties could be obtained after emulsification. The effects of the content of soft segment, the amount of hydrophilic chain extender and the amount of chain extender on the properties of emulsion and film were studied. When the content of DMBA is 3.5- 4.7DETA and the amount of DMBA is 3.5-4.7DETA, the waterborne polyurethane with excellent comprehensive properties can be prepared. Secondly, by adding polymer emulsifier in the preparation of waterborne polyurethane, Waterborne polyurethane with strong water resistance can be prepared by using internal and external synergistic effect. The effects of different internal and external emulsifier ratio and emulsifying time on the water resistance of the film were investigated. It was found that when the R1 value was 2.5, the amount of internal emulsifier was 3.6, the amount of external emulsifier was 0.5, and the addition of external emulsifier was 100 minutes, the film with better water resistance could be obtained. The water absorbency is 4.1, which is better than that of WPU prepared under the same conditions by traditional internal emulsification (19.2g). The basic properties of polyurethane under the optimum water-resistance ratio are characterized. It was found that the mechanical and thermal properties of the film had no change compared with that of the traditional internal emulsified film. Finally, the mechanism of internal and external synergistic emulsification to improve the water resistance of WPU was explored, which may be due to two reasons. One is that the addition of external emulsifier improves the emulsion performance of waterborne polyurethane, the particle size decreases, the particles are fused tightly, the void after film formation is less, water molecules are difficult to invade the film interior, and the water resistance of the film is improved. The other is that the external emulsifier will move to the surface of the film under the drive of the surface energy during the drying process of the film, and embed the hydrophilic group on the surface, so as to increase the contact angle between the surface of the film and the small water droplets and reduce the surface tension.
【學(xué)位授予單位】：北京化工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：O633.14;O648.23

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