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公开(公告)号：US11261270B2
公开(公告)日：2022-03-01
申请号：US16630282
申请日：2018-07-11
发明人： Takumi Takayama , Kazuhiko Maekawa , Christophe Detrembleur , Antoine Debuigne , Christine Jerome
摘要： A polyvinyl alcohol has a number-average molecular weight (Mn) from 4,400 to 440,000, a molecular weight distribution (Mw/Mn) from 1.05 to 1.70, a degree of saponification from 80 to 99.99 mol %, wherein the polyvinyl alcohol contains an end group represented by a formula (I) below, and a molar ratio (X) of the end group based on total monomer units and the number-average molecular weight (Mn) satisfy a formula (1) below. Such a polyvinyl alcohol has a narrow molecular weight distribution and a high number-average molecular weight with hue good. (In the formula, R1 denotes an optionally substituted aromatic group having a carbon number from 6 to 20, and R2 denotes a hydrogen atom, an alkyl group having a carbon number from 1 to 20, or an optionally substituted aromatic group having a carbon number from 6 to 20.) X·Mn/44≥0.5 (1)
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公开(公告)号：US10766978B2
公开(公告)日：2020-09-08
申请号：US16089483
申请日：2017-03-30
发明人： Takumi Takayama , Yusuke Amano , Kazuhiko Maekawa , Christophe Detrembleur , Antoine Debuigne , Christine Jerome
摘要： A polyvinyl alcohol is produced in a method comprising: a polymerization step comprising polymerizing vinyl ester monomers by controlled radical polymerization in the presence of a radical initiator and an organic cobalt complex to obtain a polymer solution containing a polyvinyl ester; an extraction step comprising extracting a cobalt complex from the polymer solution by contacting an aqueous solution containing a water-soluble ligand with the polymer solution; and a saponification step comprising saponifying the polyvinyl ester after the extraction step to obtain a polyvinyl alcohol. A method for producing a polyvinyl alcohol is thus provided that has a narrow molecular weight distribution and a high number-average molecular weight with good hue and further good solubility in water.
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