A new transesterification catalyst comprises an epoxide and a non-acidic nucleophilic onium salt.
Coating compositions having hydroxyl functional resin components and carboxylic ester components adapted for curing by transesterification following application to a substrate are formulated with in-situ formed cure catalyst comprising a non-acidic nucleophile and an epoxide-to-product coatings that readily cure by transesterification. Such coatings include polyesters, polyepoxides, and polyacrylates are useful in formulating high solids coating and powder coatings having exceptional physical properties.
Extremely low-temperature cure coatings were obtained by transesterifying mixtures of polyols and polymeric esters having multiple activated ester linkages having the structure
wherein Rʹ is lower alkyl and Y is -OH and O-alkyl radicals. These coatings provide low-temperature cure coatings for paper, plastic, and wood in addition to metal substrates.
Such catalysts can be used in powder coatings compositions which comprise a hydroxyl functional binder having carboxylic ester functionality. Such resins include hydroxyl functional acrylic, hydroxyl functional polyester, ester functional polyesters and methyl succinate esters of bis phenol epoxides.
一种新型酯交换催化剂由
环氧化物和一种非酸性亲核鎓盐组成。
具有羟基官能
树脂成分和
羧酸酯成分的涂料组合物在涂抹到基材上后可通过酯交换反应固化,这种涂料组合物是用原位固化催化剂配制而成的,该催化剂由非酸性亲核物和
环氧化物组成,可生成易于通过酯交换反应固化的涂料。此类涂料包括聚酯、聚
环氧化物和聚
丙烯酸酯,可用于配制具有优异物理性能的高固体份涂料和粉末涂料。
通过酯交换多元醇和聚合酯混合物获得极低温固化涂料,这些混合物具有多个活化酯连接,其结构如下
其中 Rʹ 为低级烷基,Y 为-OH 和 O-烷基。除
金属基材外,这些涂料还可为纸张、塑料和木材提供低温固化涂料。
此类催化剂可用于粉末涂料组合物中,其中包括具有
羧酸酯官能团的羟基官能团粘合剂。此类
树脂包括羟基官能
丙烯酸树脂、羟基官能聚酯、酯官能聚酯和双
酚环氧化物甲基琥珀酸酯。