Vinyl alcohol polymer, aqueous solution, coating agent, ink jet recording material, thermal recording material and base paper for release paper containing same

A vinyl alcohol polymer, comprising a monomer unit represented by formula (1):

• wherein:
• X represents a direct bond, a divalent hydrocarbon group, or a divalent organic group having an oxygen atom or a nitrogen atom;
• R1 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;
• R2 represents an alkoxyl group, an acyloxyl group or a group represented by OM, wherein M represents a hydrogen atom, an alkali metal or an ammonium group;
• R3 and R4 each independently represent a hydrogen atom or an alkyl group, wherein hydrogen atoms included in the alkyl group, the alkoxyl group and the acyloxyl group represented by R1 to R4 are unsubstituted or substituted with a substituent having an oxygen atom or a nitrogen atom;
• R5 represents a hydrogen atom or a methyl group;
• m is an integer of 0 to 2;
• and
• n is an integer of 6 to 20,
• wherein in a case where R1 to R5 are each present in a plurality of number, a plurality of R1s are each independently as defined above, a plurality of R2s are each independently as defined above, a plurality of R3s are each independently as defined above, a plurality of R4s are each independently as defined above, and a plurality of R5s are each independently as defined above,
• and inequalities (I), (II), and (III) are satisfied:
• 370≦P×S≦6,000 (I)
• 200≦P≦4,000 (II)
• 0.1≦S≦10 (III);
• wherein:
• P represents a viscosity average degree of polymerization of the vinyl alcohol polymer;
• and
• S represents a percentage content (mol %) of the monomer unit.