Polyvinyl alcohol powder and method for producing same

Patent metadata

Field	Value
Publication number	US-2017190812-A1
Application number	US-201515315420-A
Country	US
Kind code	A1
Filing date	Jun 3, 2015
Priority date	Jun 4, 2014
Publication date	Jul 6, 2017
Grant date	—

Abstract

The present invention is characterized by being a polyvinyl alcohol powder having an average particle diameter of 100 to 2000 μm as measured by optical microscopic observation at a humidity of 65% RH and a temperature of 25° C., having a bulk specific gravity (g/ml) of a portion ranging from 500 to 1000 μm in particle diameter of more than 0.60 and less than 0.80, and having a content of the portion ranging from 500 to 1000 μm in particle diameter of 35 to 70% by mass. Accordingly, a polyvinyl alcohol powder is provided, that is good in anti-scattering property, superior in solubility in preparing an aqueous solution from the powder, and capable of reducing transport costs due to its large specific gravity.

First claim

1 . A polyvinyl alcohol powder having an average particle diameter of 100 to 2000 μm as measured by optical microscopic observation at a humidity of 65% RH and a temperature of 25° C., having a bulk specific gravity (g/ml) of a portion ranging from 500 to 1000 μm in particle diameter of more than 0.60 and less than 0.80, and having a content of the portion ranging from 500 to 1000 μm in particle diameter of 35 to 70% by mass.

2 . The polyvinyl alcohol powder according to claim 1 , having a viscosity-average degree of polymerization of 200 to 5000 and a degree of saponification of 50 to 99.99 mol %.

3 . A method for producing a polyvinyl alcohol powder, comprising:
an introduction step of introducing a saponification catalyst into a central portion of a flow path in which a saponification raw solution comprising a polyvinyl ester and an organic solvent flows, and a mixing step of mixing the saponification raw solution with the introduced saponification catalyst using a static mixer at a shear rate of 5 to 90 s −1 .

Assignees

• Kuraray Co

Inventors

• Horiguchi Junpei
• Tanaka Kazuyuki
• Funakoshi Junji

Classifications

• C08F16/06

  Polyvinyl alcohol {; Vinyl alcohol} · CPC title

• B01J4/001

  Feed or outlet devices as such, e.g. feeding tubes · CPC title

• B01J19/2415

  Tubular reactors · CPC title

• C08F216/06

  Polyvinyl alcohol {; Vinyl alcohol} · CPC title

• C08J2329/04

  Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids · CPC title