Provided is lithographic printing plates and processes for preparing the lithographic printing plates having excellent printing durability, staining resistance and staining resistance over time.
A lithographic printing plate precursor comprising: a substrate; a photosensitive layer provided on the substrate; and an extra layer optionally provided between the substrate and the photosensitive layer; wherein the photosensitive layer or the extra layer adjacent to the substrate contains (A) a copolymer; and wherein the copolymer (A) comprises: (a1) a repeating unit having a structure represented by formula (a1-1) below in a side chain, and (a2) a repeating unit having at least one of the structures represented by formulae (a2-1) to (a2-6) below in a side chain. L1 represents a single bond, a divalent aromatic group containing 6 to 14 carbon atoms, —C(═O)—O—, or —C(—0)═NR2— (wherein R2 represents a hydrogen atom, alkyl or aryl). Z1 represents methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, cyclohexane-1,4-diyl, 1,2-phenylene, 1,3-phenylene, 1,4-phenylene, 1,2-naphthalene, 1,5-naphthalene and a linking group composed of two or more of these divalent linking groups linked through —O— or —S—, wherein a hydrogen atoms in these divalent linking groups may be replaced by substituents. R1 represents a hydrogen atom, alkyl, aryl, heterocyclyl, sulfo, alkylsulfonyl and arylsulfonyl. R21, R22 and R23 each independently represent a hydrogen atom, halogen atom or C1-8 alkyl.