Patent ID: 7141638

Claim:
A vinyl alcohol polymer comprising units from a polyoxyalkylene group-containing monomer of the following formula (I): wherein R 1 represents an alkyl group having 1 or 2 carbon atoms; R 2 represents a hydrogen atom, or an alkyl group having from 1 to 4 carbon atoms, wherein: when the viscosity of an aqueous 8 wt. % solution of the vinyl alcohol polymer is measured with a BL-type viscometer at a rotor speed of 60 rpm, the ratio of the viscosity η1 thereof at 60° C. to the viscosity η2 thereof at 40° C., η1/η2 is at least 0.8; when R 2 is a hydrogen atom, then a product of the viscosity-average degree of polymerization P, of the vinyl alcohol polymer and a content S (mol %), of polyoxyalkylene group-containing monomer units relative to all monomer units of the vinyl alcohol polymer, P×S, and a number n of the oxyalkylene repeating units in the polyoxyalkylene group-containing monomer unit satisfies the following numerical formulae (1) to (4): n>− 0.047 P×S+ 25 (1), n<− 0.044 P×S+ 58 (2), P×S> 5 (3), 15<n≦50 (4); when R 2 is an alkyl group having from 1 to 4 carbon atoms, then the number n of oxyalkylene repeating units in the polyoxyalkylene group-containing monomer unit satisfies the following numerical formula (5): 1≦n≦100 (5).