| abstract |
A water soluble resin composition containing a (vinyl alcohol)-(vinylamine) copolymer having units represented by the formulae (I) and (II) (hereinafter referred to as vinyl alcohol units (I) and vinylamine units (II)) and a cross linker having functional groups capable of reacting with amino groups, wherein when an aqueous solution containing the water soluble resin composition is prepared to be an aqueous solution having a concentration of the copolymer of 10 mass %, the viscosity (the viscosity measured in accordance with ISO 3219 at 25° C.) after the aqueous solution is held at 60° C. for 3 hours, increase by at least 0.2 time and at most 50 times, based on the viscosity immediately after the preparation: |