Abstract:

In order to further reduce the water content in the UV-curable aqueous oligomers, the water-diluted polyurethane acrylate (WPUA) oligomer was synthesized using toluene diisocyanate as hard segment, polyether polyol and polyethyleneglycol as soft segments, dimethylol propionic acid (DMPA) as hydrophilic reactant, hydroxyl propyl acrylate and pentaerythritol triacrylate as end-capping reagent, and triethylamine as neutralizer. The solid contents of the oligomer were about 80%. The influence of types and molecular weight of soft segments, the molar ratio of -NCO/-OH, the addition sequence and amount of DMPA, and the amount of inner crosslinking agent and COOH on the viscosity and film properties of UV-curable oligomer was investigated. The prepared products were characterized by UV curing, tensile strength tests, FTIR, GPC and other analysis. The results showed that the COOH content was not only the factor influencing the viscosity of the oligomer. The diols of small molecular weight, the value of n(-NCO):n(-OH) between 1.7 and 1.8, DMPA concentration in hard segments or soft segments, and 15% of trimethylolpropane were more favorable to reduced viscosity. An optimum synthesis result was obtained when the pencil hardness was H, the bending flexibility was 2 mm, the fastest curing time was 2 s, the largest tensile strength was 11.88 MPa, and the largest elongation was 21.4%. More than 60% of water content was reduced by the waterborne UV-curable coatings as compared with similar products sold in the market. Thus, this UV-curable WPUA can be apply to reduce both the humidity and time requirements.

Key words: waterborne UV-curable, high solid content, water-diluted, polyurethane acrylate, viscosity, synthesis, aqueous solution

摘要：

为了进一步提高水性UV光固化树脂的固含量,以甲苯二异氰酸酯为硬段,聚醚二元醇及聚乙二醇为软段,二羟甲基丙酸(DMPA)为亲水性物质,丙烯酸羟丙酯和季戊四醇三丙烯酸酯为封端剂,三乙胺为中和剂等,合成了固含量约为80%的水稀释型聚氨酯丙烯酸酯预聚物,探讨了软段类型及软段的相对分子质量、-NCO/-OH物质的量比、DMPA的加料顺序及加入量、内交联剂含量、COOH含量等因素对聚氨酯丙烯酸酯的黏度、涂膜性能的影响,同时对制备的产品进行光固化、拉伸强度、红外光谱(FTIR)和凝胶渗透色谱(GPC)分析。结果表明,COOH含量并不是决定预聚物黏度的唯一因素,小分子量的二醇、n(-NCO):n(-OH)在1.7~1.8、DMPA集中在硬段或软段、15%三羟甲基丙烷更有利于降低黏度,而制备的漆膜性能良好,硬度可达H,柔韧性2 mm,最快固化时间2 s,最大拉伸强度11.88 MPa,最大断裂伸长率达21.4%。制得的水性UV光固化涂料的水分减少了目前市面上同类产品的60%以上,降低了涂装时对湿度和干燥时间的要求。

关键词: 水性UV光固化, 高固体份, 水稀释型, 聚氨酯丙烯酸酯, 黏度, 合成, 水溶液