A photopolymerization initiator is an acylphosphine oxide compound represented by Formula 1-1 or Formula 2-1. A polymerizable composition or an ink jet recording method is a polymerizable composition or an ink jet recording method in which the photopolymerization initiator is used. In addition, an acylphosphine oxide compound represented by Formula 1-1 or Formula 2-1 which can be preferably used as the photopolymerization initiator. In Formula 1-1 and Formula 2-1, A represents an m-valent group, L's each independently represent a single bond or a divalent linking group, R1's each independently represent an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, R2 and R3 each independently represent an alkyl group, an aryl group, or an alkoxy group, m represents an integer of 3 or more, n1's each independently represent an integer of 0 to 4, and n2's each independently represent an integer of 0 to 5.
光聚合
引发剂是由式 1-1 或式 2-1 表示的酰基氧化膦化合物。可聚合组合物或喷墨记录方法是使用了光聚合
引发剂的可聚合组合物或喷墨记录方法。此外,由式 1-1 或式 2-1 所代表的酰基氧化膦化合物最好可用作光聚合
引发剂。在式 1-1 和式 2-1 中,A 代表 m 价基团,L's 各自独立地代表单键或二价连接基团,R1's 各自独立地代表具有 1 至 8 个碳原子的烷基、具有 6 至 20 个碳原子的芳基、具有 1 至 8 个碳原子的烷氧基或具有 1 至 20 个碳原子的烷氧基、R2和R3各自独立地代表烷基、芳基或烷氧基,m代表3或更多的整数,n1各自独立地代表0至4的整数,n2各自独立地代表0至5的整数。