Photo-alignment copolymer, binder composition, binder layer, optical laminate, and image display device

A photo-alignment copolymer comprising:

• a repeating unit A including a photo-alignment group, wherein the repeating unit A is a repeating unit represented by Formula (A),
• in Formula (A), R1 represents a hydrogen atom or a methyl group, and R2, R3, R4, R5, and R6 each independently represent a hydrogen atom or a substituent, and among R2, R3, R4, R5, and R6, two adjacent groups may be bonded to form a ring, L1 in Formula (A) is a divalent linking group represented by any one of Formula (1), . . . , or Formula (10),
• in Formulae (1) to (10), *1 represents a bonding position with a carbon atom constituting a main chain in Formula (A), and *2 represents a bonding position with a carbon atom constituting a carbonyl group in Formula (A);
• a repeating unit B including a crosslinkable group which causes a crosslinking reaction by the action of at least one selected from the group consisting of light, heat, an acid, and a base;
• and
• a repeating unit C including a cleaving group which decomposes by the action of at least one selected from the group consisting of light, heat, an acid, and a base to produce a polar group,
• wherein the repeating unit C has the cleaving group on a side chain, and has a fluorine atom or a silicon atom on a side closer to a terminal than the cleaving group on the side chain, and
• a content of each of the repeating units with respect to a total of a content a of the repeating unit A, a content b of the repeating unit B, and a content c of the repeating unit C satisfies Expressions (W1) to (W3) by mass ratio,
• 0.03≤a/(a+b+c)≤0.75 (W1)
• 0.20≤b/(a+b+c)≤0.90 (W2)
• 0.03≤c/(a+b+c)≤0.70 (W3).