【作者】 刘天亮；

【导师】 沈慧芳；

【作者基本信息】 华南理工大学 ， 化学工程， 2010， 硕士

【摘要】 随着人们环保意识的增强和国际、国内环保法规的日益严格和完善,要求涂料向低污染、高性能的方向发展。木器涂料与人们的生活息息相关,直接影响着人们的身体健康和生活水平,因此,水性木器涂料成为了研究热点。水性聚氨酯丙烯酸酯(PUA)以其优异的性能而成为高档木器涂料的重要研究方向。国内在TDI(甲苯二异氰酸酯)型聚氨酯水性涂料方面研究得较多,但TDI型聚氨酯木器涂料易黄变,不适用于高档木器涂料对耐黄变的要求,本研究主要开发用于高档木器涂料的高性能脂肪族PUA乳液。以异佛尔酮二异氰酸酯(IPDI)与聚醚二元醇N220、聚四氢呋喃醚二醇(PTMEG)为基本原料,采用逐步加成聚合法,三羟甲基丙烷(TMP)等为交联剂,先以1,4-丁二醇(BDO)扩链,后引入二羟甲基丙酸(DMPA)亲水基团,然后经三乙胺(TEA)中和,得聚氨酯预聚物。将聚氨酯预聚物高速剪切分散于水中,并以乙二胺(EDA)扩链,得到聚氨酯(PU)分散体。将甲基丙烯酸甲酯(MMA)预先分散于聚氨酯分散体中,然后以偶氮二异丁腈(AIBN)为引发剂引发聚合得到PUA复合乳液。首先研究了分别以聚醚多元醇N220、聚四氢呋喃醚二醇和聚碳酸酯二醇为多元醇单独使用,或以不同的比例复配使用合成了系列PUA复合乳液,较详细的对系列乳液及相应涂膜的性能进行了比较,最终确定了以PTMEG 50%替代N220为最佳方案。在PTMEG和N220各占50%复配使用的条件下,研究了预聚温度与时间、有机溶剂添加量、乳液聚合温度、-NCO/-OH摩尔比、三羟甲基丙烷交联剂的用量、DMPA亲水扩链剂用量、剪切乳化工艺等因素对聚氨酯水分散体及其性能的影响,确定了合成PUA复合乳液的最佳工艺和配方。预聚初期温度在60~65℃之间,后期保温温度在75℃左右;预聚时间7.5h;有机溶剂添加量15%;初NCO/OH摩尔比为10.5~11.0;总-NCO/-OH摩尔比为1.35; TMP用量为2.0%;分散温度20℃-30℃;采用直接分散法、后中和工艺,叶轮转速4000-5000r/min;PUA乳液聚合温度70℃-75℃;MMA添加量20%-30%。利用现代分析测试手段如红外光谱、凝胶渗透色谱、扫描电镜、示差扫描量热分析(DSC)对PUA乳液进行了表征。红外光谱分析表明,-NCO与-OH基团都很好的参与了反应,生成了氨基甲酸酯基团;对合成过程的凝胶渗透色谱跟踪分析表明,PU分子量的增大主要在胺扩链阶段,最终产品的分子量在105数量级;通过扫描电镜对胶膜断面进行了表征,未经交联改性的断面很光滑,而经改性后的断面就很粗糙。更多还原

【Abstract】 Due to the improvement of People’s awareness of environmental protection and international and domestic strict environmental regulations, coatings with low pollution and high performances have developed. Since wooden coatings have a very tight contact with people’s lives, they have become hot research topics. Especially polyurethane acrylate (PUA) has become an important type of wooden coatings for its outstanding performances. There are lots of research emphasized on Toluene diisocyanate (TDI) polyurethane water-based coatings in domestic, but TDI-based polyurethane wooden coating is easy to yellowing, which does not meet the demands of high-quality wooden coatings about the anti-yellowing. In this dissertation, the aliphatic PUA composite emulsion used as high-quality wooden coatings was mainly developed.Polyurethane prepolymer was synthesized via step polyaddition, based on isophorone diisocyanate (IPDI)、poly(propylene oxide) diol (N220) and PTMEG as raw materials, tri(hydroxymethyl) propane (TMP) as cross-linkers, 1,4-butanediol (BDO) as chain extender, dimethylol propionic acid (DMPA) as hydrophilic agent, and triethylamine (TEA) as neutralizer. Polyurethane dispersion (PUD) was obtained by dispersing PU prepolymer into water at a high speed of stirring with ethylenediamine (EDA) as another chain extender. Methyl methacrylate (MMA) was dispersed into PUD previously. Then polyurethane-acrylate (PUA) hybrid emulsions were synthesized by emulsion polymerization using 2, 2’-azobisisobutyronitril (AIBN) as initiator.Firstly polyurethane-acrylate (PUA) composite emulsions were synthesized based on poly(propylene oxide) diol (N220)、PTMEG、policarbonatediol (PCDL) alone or based on their blends at different ratio. The performances of emulsions and their corresponding films with different diol as raw materials were compared particularly. At last the optimal recipe was confirmed that the emulsions and films have the best performances with 50% PTMEG instead of poly (propylene oxide) diol (N220).When the mass ratio of PTMEG and N220 was 1:1, effects of amount of organic solvent, reaction time and temperature of pre-polymerization, temperature of emulsion polymerization, mole ratio of -NCO/-OH, content of cross-linker (tri(hydroxymethyl) propane)、content of hydrophilic chain extender (DMPA) and emulsification process on properties of waterborne polyurethane emulsions and their films were described and the optimal recipe and synthetic process were decided. The results showed that when the temperature of pre-polymerization was between 60℃~65℃and the time of pre-polymerization was 7.5h, the content of organic solvent was 15%, the preliminary mole ratio of -NCO/-OH was between 10.5~11.0 and the total mole ratio of NCO/OH was 1.35, the content of TMP was 2.0%, the temperature of Emulsification process was 20℃-30℃, the speed of impeller was between 4000-5000 r/min、using direct dispersion method and after-neutralization technology, the temperature of emulsion polymerization was 70℃-75℃, the amount of MMA was 20~30%, the emulsions and the corresponding films have best comprehensive properties.Modern instruments such as infrared spectroscopy (IR), gel permeation chromatography (GPC), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) etc. were used for tracing synthetic process and characterizing structures and properties of products. Infrared spectroscopy showed that -NCO and-OH groups were involved in the reaction to form the urethane groups; The analysis about tracing the synthetic process of PU by gel permeation chromatography showed that the increase of PU’s molecular weight quickly was happened mainly in the chain-extending stage when EDA was added, and the molecular weight of the final product was more than 105; Scanning electron microscopy was used in characterizing film’s break surface and results showed that section without cross-linking modification was smooth, and the modified section was very rough.更多还原