| 摘要 |
<p>The present invention provides vinyl alcohol polymers containing the unit (I) and the unit (II) represented by the following formulae, having a content of the unit (I) from 10 to 99.99 mol% and a content of the unit (II) from 90 to 0.01 mol%, a diad syndiotacticity of not less than 55 mol% and an intrinsic viscosity of polyvinyl acetate obtained by acetylation of 0.7 dl/g, which is measured in benzene at 30 DEG C. <CHEM> wherein R<1> is a hydrogen atom or a hydrocarbon group, and each of R<2> and R<3> is a hydrocarbon group. Also provided is a process for producing vinyl alcohol polymers which comprises hydrolyzing, in the substantial absence of oxygen or in the presence of an antioxidant, homopolymers or copolymers of a vinyl ester represented by the following formula (III): <CHEM> wherein R<1>, R<2> and R<3> are the same as defined above; the above vinyl alcohol polymers comprising a vinyl alcohol unit represented by the formula (I) and a vinyl ester unit represented by the formula (II). Further provided are films and gels, comprising vinyl alcohol polymers having a syndiotacticity of not less than 55 mol%, which are excellent in water resistance, heat resistance, wet heat resistance, and durability. Still further provided is a process for producing shaped articles comprising vinyl alcohol polymers which comprises contacting a solution comprising vinyl alcohol polymers having a syndiotacticity of not less than 55 mol% with an aqueous solution containing an organic solvent in an amount of less than 50 wt%.</p> |
