环保水乳型功能胶乳的制备表征及其应用研究

【作者】 戎潜萍；

【导师】 朱爱萍；

【作者基本信息】 扬州大学 ， 高分子化学与物理， 2010， 硕士

【摘要】 调节丙烯酸酯类单体的种类及组分可以弹性设计聚丙烯酸酯胶乳（PA）的分子结构,乳胶膜从软到硬。乳胶膜具有优异的耐候性、耐水性、耐化学品性。在内外墙涂料、水性胶粘剂、纺织助剂等领域有着广泛的应用。为了进一步开拓聚丙烯酸酯胶乳的新用途,用其它性质的材料或者其它高分子材料对其化学改性,制备聚丙烯酸酯基复合胶乳是近年来研究较为热门的课题之一。本文分别研究三种体系的复合胶乳:第一种是无机纳米二氧化硅/聚丙烯酸酯杂化复合乳液,第二种是聚氨酯/聚丙烯酸酯复合胶乳（PUA）,第三种是聚丙烯酸酯接枝环氧树脂复合胶乳（EPA）。（1）纳米SiO₂具有优异的光、热、电、磁和机械性能等,制备含纳米SiO₂的PA胶乳,可望提高乳胶膜的耐热性、综合机械力学性能、防紫外线以及耐化学品性。但纳米SiO₂由于具有高表面能,在水介质中易聚集,制备稳定的SiO₂/聚合物复合乳液是较为困难的。因此,本文首先用油酸表面修饰纳米SiO₂（M-SiO₂）以引入可聚合的双键,同时提高纳米SiO₂在水相体系中的悬浮稳定性。然后在M-SiO₂表面进行乳液聚合,制备苯乙烯-丙烯酸丁酯-甲基丙烯酸甲酯共聚物/二氧化硅（PSBM-g-SiO₂）以及苯乙烯-甲基丙烯酸甲酯共聚物/二氧化硅（PSM-g-SiO₂）杂化复合乳液。重点研究了复合乳胶粒子的形貌、粒径大小及其分布和纳米二氧化硅含量对乳胶膜的热性能、流变性能、界面形貌的影响,揭示了复合乳胶粒子的形成机理。结果表明,纳米SiO₂与PSBM之间以化学键相连,粒子为规则的球形形貌,粒径在50-80nm,SiO₂的复合提高了PSBM的热分解温度。稳态粘度与动态模量取决于纳米SiO₂在PSBM聚合物基中的含量和分散均匀性。将PSM-g-SiO₂杂化纳米粒子填充到PBSA胶乳中,以制备填充性复合胶乳,考察了杂化纳米粒子的填充量对填充型复合PBSA的耐水性、粘度及对网格布的粘结强度的影响。结果表明填充有1 wt.%杂化纳米粒子的PSBA乳液的玻璃纤维的单根丝的节点强度最大,同时复合胶膜的耐水性能显著提高。（2）通过丙烯酸酯类的单体与聚氨酯（PU）乳液聚合的方法成功地制备了聚氨酯/聚丙烯酸酯（PUA）复合胶乳,采用衰减全反射傅立叶红外光谱法（ATR-FTIR）、透射电镜（TEM）、动态光散射（DLS）、热重（TGA）等技术对纳米复合胶乳的结构、尺寸和性能进行表征。结果表明,复合胶乳的表面为PU中的亲水基团,内部为PU中的疏水区域与PA形成的IPN结构,并揭示了复合胶乳的形成机理。与水性PU相比,复合乳胶膜的耐水性及耐热性显著提高。应用于聚氯乙烯（PVC）片材的聚偏二氯乙烯（PVDC）阻隔涂层的底涂剂,对比水性聚氨酯PVDC底涂剂,分析PVC片材表面PVDC涂层表面外观、剥离强度、性价比等参数,指出PUA复合胶乳是一种性能优异、价格低廉的新型水性PVDC底涂剂。（3）采用两种功能单体甲基丙烯酸（MAA）和丙烯酰胺（AM）及乳液聚合方法成功制备了高环氧树脂含量的环氧树脂接枝聚丙烯酸酯胶乳（EPA）,采用DSC、萃取法及铅笔硬度法对接枝共聚的乳胶膜进行结构与性能的表征。通过研究功能单体种类与用量对乳液聚合稳定性及胶乳贮存稳定性的影响,揭示接枝聚合机理。系统研究了EPA乳胶膜中环氧树脂的含量对交联度、玻璃化温度（Tg）、硬度以及交联固化后的乳胶膜的耐水性能的影响。结果表明,MAA和AM两种功能单体共同使用,使羧基（-COOH）、酰胺基（-CONH2）与环氧基团发生交联反应形成自交联结构,是制备高环氧树脂含量的EPA的关键因素,EPA接枝共聚胶乳中环氧树脂含量从10 wt.%⁶0 wt.%可调。共聚乳胶膜的自交联度、Tg和硬度随着环氧含量的增加而降低,而交联固化的胶乳膜耐水性能随环氧树脂量的增加而提高。更多还原

【Abstract】 The polyacrylate latex （PA） of molecular structure was designed changeably by varying the types and component of acrylic monomers. And thus the latex film from soft to hard with distinct weather-resistant, water-resistant and chemical resistant. The PA latex has been widely used in interior and exterior wall coating, water-based adhesive, textile auxiliaries and other fields. In resent years, it is one of the more popular subjects of preparing polyacrylate complex latex with other properties of materials and other polymer materials to modify PA latex by chemical method to develop the novel application. Three kinds of complex latex system were studied in this paper, the first is inorganic nano-silica/polyacrylate hybrid complex latex, the second is polyurethane/ polyacrylate complex latex （PUA）, and the third is epoxy graft polyacrylate complex latex （EPA）.Nano silica exhibits attractive thermal, optical, electrical, magnetic and mechanical properties. Preparation of nano-SiO₂ in the PA latex expected to improve the heat resistance, comprehensive mechanical properties, UV and chemical resistance. However, due to the large surface and strong aggregation of nanosilica, the synthesis of stable nanosilica/polymer complex latex is difficult. Thus, nanosilica particles were modified by oleic acid （M-SiO₂） in order to introduce the polymerization active vinyl groups and improve the suspension stability of nano-SiO₂ in aqueous solution. Then, emulsion polymerization was done in the presence of M-SiO₂ nanoparticles to obtain styrene-n-butyl acrylate-methyl methacrylate copolymer/silica （PSBM-g-SiO₂） and styrene-methyl methacrylate copolymer/silica （PSM-g-SiO₂） complex nanoparticles. The morphology, size and size distribution of the complex latex particles and the effect of silica content in latex film on the thermal behavior, rheological behavior and interfacial morphology were investigated in detail. A reasonable mechanism for the preparation of nanoscale complex latex was described. The results indicated that the chemical bond was formed between PSBM and nanosilica, the complex particles had a regular spherical morphology with a diameter ranging from 50 to 80 nm, the addition of nanosilica could improve the pyrolyze temperature of PSBM. The steady viscosity and dynamic modulus were strongly dependent on the content and distribution of nanosilica in PSBM matrix. The obtained PSM-g-SiO₂ complex nanoparticles were subsequently filled in the poly （n-butyl acrylate-styrene） （PBSA） latex to preparation of composite latex. The effect of hybrid nanoparticle filling on the water resistant, viscosity and the adhesive strength of the fibre glass gridding cloth was studied. The result showed that the node strength/monofilanment of the fibre glass gridding cloth coated with the PBSA latex filled with 1.0 wt.% complex nanoparticles demonstrated greatest improvement. Moreover, the water-resistance property of complex latex film was enhanced distinctively.（2） Polyurethane/polyacrylate（PUA） complex emulsion was prepared by emulsion polymerization of acrylate monomers and water-based polyurethane. The structure, size and property of the complex latex were characterization by Attenuated total reflectance FTIR spectroscopic （ATR-FTIR）, Transmission electron microscope （TEM）, Dynamic light scattering （DLS） and Thermal gravimetric analysis （TGA）. The results indicated that the surface of the complex latex is hydrophilic moieties of PU, while the interior of the latex is IPN structure formed by the hydrophobic domain of PU and PA. A reasonable mechanism for the preparation of the complex latex was given. In comparison with that of water-based PU, the water resistance and heat resistance of PUA films were improved. The resulting latex was then applied in pre-adhesive of Polyvinylidene Chloride （PVDC） to endue the barrier property of Polyvinyl Chloride （PVC） sheets. The appearance, peel strength of PVDC from PVC sheet, and performance price ratio of PUA complex latex are better as compared with the water-based PU pre-adhesive. Therefore, PUA complex latex is a novel pre-adhesive for PVDC with high performance in properties and low cost. （3） Epoxy-g-polyacrylate （EPA） latex with a high content of epoxy resin was prepared by emulsion polymerization with using two kind of functional monomers methacrylic acid （MAA） and acrylamide （AM）, and the structure and property of graft copolymerization latex films were characterization by differential scanning calorimetry （DSC）, cross linking degrees, water absorption and pencil hardness, respectively. The effect of the type and amount of functional monomers on polymerization stability and storage stability was investigated and the mechanism of graft polymerization was revealed. The effect of epoxy resin content in EPA latex film on the cross-linking degrees, glass transition temperature （Tg）, rigidity and water resistant was discussed in detail. The results indicated that the usage of the MAA and AM functional monomers at the same time to make carboxyl group （-COOH） amide group （-CONH2） cross linking react with epoxy group and form self cross linking structure is the important factor to the prepare EPA with high content of epoxy resin. The epoxy resin content of graft copolymerization EPA latex ranges from 10 wt.% to 60 wt.%. The self-crosslinking degrees, Tg and rigidity of copolymerization latex films decreased with increasing epoxy resin content, while the water resistant increased with increasing epoxy resin content after the latex film was cured.更多还原