There is described a low number average molecular weight (MN<10 kD) and high glass transition temperature (>75° C.) copolymer (optionally a solid grade oligomer (SGO)) that comprises (a) at least 20 wt-% of itaconate functional monomer(s), (b) not more than 40% of a hydrophilic monomer, preferably an acid functional monomer(s) in an amount sufficient to achieve an acid value from 65 to 325 mg KOH per g of solid polymer; (c) optionally not more than 70% of other monomers not being either (a) or (b), having a max content of vinyl aromatic monomer(s) of 40 wt-% and/or max content of methacrylate(s) of 40 wt-%; where the weight percentages of monomers (a), (b) and (c) are calculated as a proportion of the total amount of monomers in the copolymer being 100%.
低平均分子量(MN75° C.)共聚物(可选固体级低聚物 (SGO)),该共聚物包含 (a) 至少 20 wt-% 的
衣康酸酯官能团单体,(b) 不超过 40% 的亲
水性单体,最好是酸官能团单体,其用量足以使每克固体聚合物的酸值达到 65 至 325 毫克 KOH;(c) 不属于(a)或(b)的其他单体不超过 70%,其中
乙烯基芳香族单体的最大含量为 40 wt-%,和/或
甲基丙烯酸酯的最大含量为 40 wt-%;其中单体(a)、(b)和(c)的重量百分比是按共聚物中单体总量占 100%的比例计算的。