Disclosed are (1) an aqueous thermoplastic coating composition for coating plastics substrates, the composition consisting essentially of:
(A) an aqueous acrylic resin and
(B) a urethane resin emulsion,
the component (B) being a self-emulsifiable urethane emulsion prepared by subjecting a urethane prepolymer to reaction for chain extension by water and emulsification after or during neutralization of the urethane prepolymer with a tertiary amine, the urethane prepolymer consisting essentially of (i) an aliphatic and/or an alicyclic diisocyanate, (ii) a polyether diol and/or polyester diol both having a number-average molecular weight of about 500 to about 5000, (iii) a low-molecular weight polyhydroxyl compound and (iv) a dimethylolalkanoic acid in NCO/OH equivalent ratio of 1.1-1.9 : 1, the amount of the component (A) being about 1 to about 12% by weight and the amount of the component (B) being about 99 to about 88% by weight, based on the combined weight (calculated as solids) of the two components; and
(2) a two-coat coating method for coating a plastics substrate, the method comprising the steps of coating a plastics substrate with a base-coat composition containing a coloring pigment and/or metallic pigment, applying a clear coat composition to the cured or uncured coating for forming a transparent coating and curing the clear coating or the two coatings at the same time at a temperature lower than about 120°C, the method being characterized by the use of the aqueous thermoplastic coating composition as defined above in (1) as the base-coat composition.
公开了 (1) 一种用于涂覆塑料基材的
水性热塑性涂料组合物,该组合物主要由以下成分组成:
(A)
丙烯酸树脂水溶液和
(B) 聚
氨酯
树脂乳液、
成分(B)是一种可自乳化的聚
氨酯乳液,其制备方法是在聚
氨酯预聚物与叔胺中和之后或中和过程中,使聚
氨酯预聚物与
水发生链延伸反应并乳化、该聚
氨酯预聚物主要包括(i)脂肪族和/或脂环族二
异氰酸酯,(ii)聚醚二元醇和/或聚酯二元醇,二者的数均分子量约为 500 至约 5000,(iii)低分子量聚羟基化合物和(iv)二甲基醇烷酸,二者的 NCO/OH 当量比为 1.1-1.9∶1,组分(A)的量按重量计约为 1%至约 12%,组分(B)的量按重量计约为 99%至约 88%,以两种组分的总重量(以固体计算)为基础;和
(2) 用于涂覆塑料基材的双涂层涂覆方法,该方法包括以下步骤:用含有着色
颜料和/或
金属
颜料的基涂层组合物涂覆塑料基材,在固化或未固化的涂层上涂覆透明涂层组合物以形成透明涂层,并在低于约 120°C 的温度下同时固化透明涂层或两种涂层,该方法的特征在于使用如上文(1)中定义的
水性热塑性涂层组合物作为基涂层组合物。