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河北工业大学硕士学位论文 iGMA 型丙烯酸酯共聚树脂的合成及其粉末涂料制备型丙烯酸酯共聚树脂的合成及其粉末涂料制备 摘摘 要要 采用甲基丙烯酸缩水甘油酯(GMA)、 甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)作为共聚单体,偶氮二异丁腈(AIBN)作为引发剂,分别采用溶液聚合方法和分散聚合方法,合成出了符合粉末涂料用树脂性能指标要求的含有环氧基的聚丙烯酸酯树脂。溶液聚合所采用的溶剂为甲苯, 分散聚合所采用的分散介质为乙醇与去离子水的混合物(或者为乙二醇单甲醚与去离子水的混合物);分散聚合所采用的介质无毒无污染,可以循环利用,符合环保要求,并且可以自动与聚丙烯酸酯树脂分离,避免了大规模的溶剂脱除过程。对两种聚合方法的工艺条件进行了优化,利用动态差示扫描量热法对聚丙烯酸酯树脂固化体系进行了固化动力学研究。 本文着重考察了如何有效地控制聚丙烯酸酯树脂的分子量及其分布、玻璃化转变温度、环氧当量(EEW)以及不挥发物含量等性能指标,并且对粉末涂料的加工工艺及涂膜性能进行了初步的研究。通过红外光谱(IR)与核磁共振氢谱(1HNMR),对合成树脂的结构进行了表征;利用凝胶渗透色谱(GPC)对合成树脂的分子量及其分布进行了测定;利用差示扫描量热法(DSC)测定了合成树脂的玻璃化转变温度(Tg);利用盐酸-丙酮法测定了合成树脂的 EEW;利用 TA-2000 热分析仪考察了合成树脂的热稳定性;利用扫描电镜(SEM)和粒径分析仪对分散聚合产生的聚合物粒子的形态及粒径分布进行了表征;最后将自制的聚丙烯酸酯树脂与合适的固化剂及助剂配合,通过熔融挤出及静电喷涂,制备了聚丙烯酸酯粉末涂料涂膜,通过冲击器、光泽度计、划格器等仪器分别考察了涂膜的抗冲击性、光泽、附着力和铅笔硬度。 研究结果表明:采用溶液聚合时,当升温至溶剂的沸点时,采用半连续滴加的方法,制备的聚丙烯酸酯树脂性能较好,调整聚合温度和引发剂加入量可以有效控制树脂的分子量及其分布,可以将树脂的数均分子量从 14983 调整至 3922,分散指数在 1.60 左右;控制 GMA 的加入量可以有效地调整树脂的 EEW 在 450550g/eq 范围之内; 通过调整共聚单体中 MMA 与 BA 的比例可以控制树脂的 Tg在 4060;合成树脂的不挥发物含量不低于98.0%。进行分散聚合时,选择合适的醇水比可以使聚合体系稳定,形成的聚合物微球形状规则、大小均匀;通过对丙烯酸酯共聚物自沉淀现象的分析,推测其遵循齐聚物沉淀机理;合成树脂其它性能指标的控制与溶液聚合体系相似,测试结果也基本一致。对聚丙烯GMA 型丙烯酸酯共聚树脂的合成及其粉末涂料的制备 ii酸酯粉末涂料固化体系的固化动力学分析表明,四丁基溴化铵的效果要优于乙基三苯基溴化膦。利用合成的聚丙烯酸酯树脂,用羧基聚酯作为固化剂、配合适当的助剂,可以制备出加工性能优异的聚丙烯酸酯粉末涂料,其涂膜的正面抗冲击性通过 30cm、附着力达到 1级、铅笔硬度达到 4H、60 度光泽为 25.9,接近低光粉末涂料。 关键词:聚关键词:聚丙烯酸酯树脂,环氧基,粉末涂料,溶液聚合,分散聚合,固化动力学,静电喷涂 河北工业大学硕士学位论文 iiiSYNTHESIS OF GMA ACRYLIC TERPOLYMER RESIN AND PREPARATION OF POWDER COATING ABSTRACT Epoxy acrylic resins for powder coating were synthesized by solution polymerization and dispersion polymerization methods, respectively. Copolymerization using glycidyl methacrylate (GMA)、methyl methacrylate (MMA) and butyl acrylate (BA) as comonomers were initialized by azobisisobutronitrile (AIBN). For solution polymerization, the solvent was toluene and the media was mixture of ethanol-deionized water or 2-methoxyl ethanol-deionized water for dispersion polymerization. After the finish of dispersion polymerization, the terpolymer precipitated naturally as continuous falling of the medium temperature. This new method avoided the introduction of impurities into the synthesized resin and the process of distilling solvent. The used media could be recycled. The curing kinetics of acrylic powder coating systems were investigated by dynamic differential scanning calorimetry. In this study, the methods to control effectively the molecular weight and polydispersity indexes、the glass-transition temperature、the epoxy equivalent weight (EEW) and non volatile organic content of synthesized acrylic resins were studied in detail. The structure of the synthesized acrylic resin was investigated by infrared (IR) spectroscopy and 1HNMR. Molecular weight and polydispersity indexes of the resultant resin were determined by gel permeation chromatography (GPC). The EEW of acrylic resin was determined by titration analysis. The glass-transition temperature (Tg) was determined by differential scanning calorimetry (DSC). The thermostability of the synthesized acrylic resin was measured by thermogravimetry (TG). Diameter distributions and morphology of the GMA-MMA-BA terpolymer particles prepared by dispersion polymerization were characterized with the aid of submicron particle analyzer and scanning electron microscopy (SEM). The acrylic powder coatings were prepared by blending the synthesized resin、curing agents and suitable assistants. The properties of coating film were determined by impacter、vancometer and cross cut test. The study results showed that the synthesized resin which was prepared by dropwise GMA 型丙烯酸酯共聚树脂的合成及其粉末涂料的制备 iv method and at the boiling point of solvent in solution polymerization had a good general performance. The molecular weight and polydispersity could be controlled by adjusting polymerization temperature and the content of initiator effectively. The number average molecular weight of synthesized resin decreased from 14983 to 3922 and the polydispersity was about 1.60. The EEW of synthesized resin could be adjusted from 450g/eq to 550g/eq by the weight content of GMA in comonomers. The Tg of synthesized resin can be controlled from 40 to 60 by adjusting the MMA/BA ratio. The non volatile organic content of the synthesized resin was above 98.0%. If the ratio of ethanol to water in dispersion polymerization was suitable, the stability of polymerization will very well and the shape and uniform of the micro-spheres will keep well. The analysis of precipitating phenomena in dispersion polymerization showed the terpolymer maybe followed the mechanism of oligomer precipitating. The other properties of acrylic resin prepared by dispersion polymerization also can be controlled by the similar methods just like in solution polymerization. The results of curing kinetics showed that the tetrabutylammonium bromide had better catalytic effects than ethyl triphenyl phosphorus bromide. The acrylic powder coatings were prepared by blending the synthesized resin、carboxyl functional polyester and suitable assistants. In a good reci
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