Thermosetting composition with photo-alignment property, alignment layer, substrate with alignment layer, retardation plate, and device

An alignment layer comprising a copolymer including a photo-dimerization structure of a photo-alignment group of a photo-alignment constitutional unit represented by the following formula (1) and a cross-linking structure of a thermal cross-linking group of a thermal cross-linking constitutional unit represented by the following formula (2):

• (in the formula (1), X represents a photo-alignment group, L1 represents a divalent linking group or a single bond, R1 represents a hydrogen atom or a monovalent organic group, and k represents 1 to 5;
• in the formula (2), Y represents a thermal cross-linking group, L2 represents a divalent linking group or a single bond, R2 represents a hydrogen atom or a monovalent organic group, and 1 represents 1 to 5).

An alignment layer comprising a copolymer including a photo-isomerization structure of a photo-alignment group of a photo-alignment constitutional unit represented by the following formula (1) and a cross-linking structure of a thermal cross-linking group of a thermal cross-linking constitutional unit represented by the following formula (2):

• (in the formula (1), X represents a photo-alignment group, L1 represents a divalent linking group or a single bond, R1 represents a hydrogen atom or a monovalent organic group, and k represents 1 to 5;
• in the formula (2), Y represents a thermal cross-linking group, L2 represents a divalent linking group or a single bond, R2 represents a hydrogen atom or a monovalent organic group, and 1 represents 1 to 5).