Patent ID: 7439300
Filing Date: 2008-10-21
Classification: C08F,C08J

Abstract:
1. A polyvinyl alcohol based polymer, which is one that satisfies one of the following conditions (1) to (4): (1) its polymerization degree is at least 800 but lower than 8000, its saponification degree is at least 99.0 mol %, and a difference between a temperature at which its temperature-programmed solubility in water becomes lower than 15 wt % and a temperature at which its temperature-programmed solubility in water becomes at least 90 wt % is 10° C. or less and wherein its temperature-programmed solubility in water is lower than 15 wt % at 80° C. and is at least 90 wt % at 90° C.; (2) its polymerization degree is at least 800 but lower than 8000, its saponification degree is at least 80.0 mol % but lower than 99.0 mol %, and a difference between a temperature at which its temperature-programmed solubility in water becomes lower than 15 wt % and a temperature at which its temperature-programmed solubility in water becomes at least 90 wt % is 20° C. or less and wherein its temperature-programmed solubility in water is lower than 15 wt % at 80° C. and is at least 90 wt % at 90° C.; (3) its polymerization degree is at least 120 but lower than 800, its saponification degree is at least 95.0 mol %, its temperature-programmed solubility in water is lower than 40 wt % at 50° C., and a difference between a temperature at which its temperature-programmed solubility in water becomes lower than 15 wt % and a temperature at which its temperature-programmed solubility in water becomes at least 90 wt % is 30° C. or less; and (4) its polymerization degree is at least 120 but lower than 800, its saponification degree is at least 80.0 mol % but lower than 95.0 mol %, and its temperature-programmed solubility in water is lower than 50 wt % at 20° C., wherein the temperature-programmed solubility in water denotes a numerical value that is determined by a formula of (S1/52)×100 (wt %), where S1 denotes an amount of a polyvinyl alcohol based polymer dissolved at a predetermined temperature when a predetermined amount of the polyvinyl alcohol based polymer is put into water whose temperature is 20° C. to prepare a suspension so that the predetermined amount corresponds to 4 wt % of the whole, and then temperature of the suspension is raised to the predetermined temperature at a rate of 0.8° C./min while the suspension is stirred, and S2 denotes the predetermined amount of the polyvinyl alcohol based polymer.