Diarylamine novolac resin

A polymer comprising:

• a unit structure (A) of Formula (1):
• (in Formula (1), each of Ar1 and Ar2 is a benzene ring or a naphthalene ring, each of R1 and R2 is a substituent of a hydrogen atom on the benzene ring or the naphthalene ring and is selected from the group consisting of a halogen group, a nitro group, an amino group, a hydroxy group, a C1-10 alkyl group, a C2-10 alkenyl group, a C6-40 aryl group, and a combination of the halogen group, the nitro group, the amino group, the hydroxy group, the alkyl group, the alkenyl group, and the aryl group, in which each of the alkyl group, the alkenyl group, and the aryl group is an organic group that optionally contains an ether bond, a ketone bond, or an ester bond;
• R3 is selected from the group consisting of a hydrogen atom, a C1-10 alkyl group, a C2-10 alkenyl group, a C6-40 aryl group, and a combination of the hydrogen atom, the alkyl group, the alkenyl group, and the aryl group, in which each of the alkyl group, the alkenyl group, and the aryl group is an organic group that optionally contains an ether bond, a ketone bond, or an ester bond;
• R4 is selected from the group consisting of a C6-40 aryl group and a heterocyclic group, in which each of the aryl group and the heterocyclic group is an organic group that is optionally substituted with a halogen group, a nitro group, an amino group, a C1-10 alkyl group, a C1-10 alkoxy group, a C6-40 aryl group, a formyl group, a carboxy group, or a hydroxy group;
• R5 is selected from the group consisting of a hydrogen atom, a C1-10 alkyl group, a C6-40 aryl group, and a heterocyclic group, in which each of the alkyl group, the aryl group, and the heterocyclic group is an organic group that is optionally substituted with a halogen group, a nitro group, an amino group, or a hydroxy group, R4 and R5 together with a carbon atom to which R4 and R5 are bound optionally form a ring, and each of n1 and n2 is independently an integer of 0 to 3).