Kuraray Co., Ltd.

Shigeki Takada

Hitoshi Maruyama

Sadahiko Shiraga

Naoki Fujiwara

Tatsuya Oshita

Yukiatsu Komiya

Taku Tanaka

Ken Yuki

Kazutoshi Terada

Goki Uehara

Syuichi Kanao

Naoki Kawakami

Kanenori Ito

Yoshiki Takeda

Nobuhisa Senda

Kazunari Igarashi

Saahiko Shiraga

A vinyl alcohol polymer composition (II) is produced by a process of providing a reaction liquid comprising a solution containing a vinyl carboxylate polymer and, a first metal alkoxide (I) having at least one functional group and/or an oligomer (I) having at least one functional group obtained from said metal alkoxide (I); a step of simultaneously effecting (a) saponification of said vinyl carboxylate polymer and (b) reaction in which at least part of the functional groups of said metal alkoxide (I) and/or said oligomer (I) participates, thereby obtaining a vinyl alcohol polymer composition (I); and a step of preparing a solution (A) containing said vinyl alcohol polymer composition (I), followed by adding to the solution (A) a second metal alkoxide (II) and/or an oligomer (II) obtained from the metal alkoxide (II) or another solution (B) containing the metal alkoxide (II) and/or the oligomer (II) derived from the metal alkoxide (II), to prepare an intermediate product solution (C), and then removing the solvent from said solution (C). The vinyl alcohol polymer composition obtained by the above process has excellent gas-barrier properties, in particular excellent gas-barrier properties under high-humidity conditions. The vinyl alcohol polymer composition is suitably usable as a coating agent having good storage stability and little uneven applicability, and as gas-barrier material, in particular laminate having excellent gas-barrier properties under high-humidity conditions.

Process for producing vinyl alcohol polymer compositions

Provided is a method for producing gas barrier film, in which the coating film produced has excellent, oxygen gas barrier properties and is influenced little by moisture. The method comprises extruding a polyvinyl alcohol which contains not more than 19 mol % of &agr;-olefin units with not more than 4 carbon atoms, onto a substrate film, then stretching it at least 3-fold and subjecting it to heat treatment at a temperature not lower than 120&deg; C.

Method for producing gas barrier film

A water-soluble polyvinyl alcohol coating agent for a film contains from 3 to 19 mol % of &agr;-olefin units, wherein each said &agr;-olefin unit contains up to 4 carbon atoms. The polyvinyl alcohol coating agent can be coated on a polyolefin, a polyester or a polyamide substrate film to form a laminate film. A method for producing the laminate film comprises applying an aqueous solution of the coating agent to the substrate film, followed by drying the coating.

Coating agent for film, laminate and method for producing it

There is disclosed a process for producing a vinyl resin by suspension polymerization of a vinyl compound in the presence of a suspending agent (A) which comprises using a polymerization vessel equipped with a reflux condenser and adding a polyvinyl alcohol (B) having a degree of hydrolysis of at most 85 mol % in an amount of 0.001 to 0.5 part by weight based on 100 parts by weight of said vinyl compound when a polymerization conversion is in the range of 30 to 90%. According to the present invention, there is provided a process for producing a vinyl resin having a high bulk density, which is excellent in anti-foaming effect against the dry foam being generated in the middle to latter period of the suspension polymerization in a polymerization vessel equipped with a reflux condenser which is excellent in productivity.

Process for producing vinyl resin

A vinyl compound is polymerized under suspension polymerization conditions by polymerizing the vinyl compound in a suspension polymerization medium containing, as the suspending agent, from 0.02 to 0.2 parts by weight of a polyvinyl alcohol polymer (A) having a degree of hydrolysis ranging from 60 to 95 mol % and a terminal mercapto group, based on 100 parts by weight of the vinyl compound. In another aspect of the invention, the suspending agent is a combination of said polyvinyl alcohol polymer (A) and a polyvinyl ester (B) having a degree of hydrolysis less than 60 mol %. The weight ratio of the two polymeric suspending agents (A)/(B) ranges from 40/60 to 95/5.

Suspending agent for suspension polymerization of vinyl compound

The present invention is to provide a suspending agent for suspension polymerization of a vinyl compound which comprises a polyvinyl alcohol polymer (A) having a degree of hydrolysis of at least 60 mol % and a mercapto group at an end thereof; and furthermore a suspending agent for suspension polymerization of a vinyl compound which comprises a polyvinyl alcohol polymer (A) having a degree of hydrolysis of at least 60 mol % and a mercapto group at an end thereof and a polyvinyl ester polymer (B) having a degree of hydrosis of less than 60 mol %, weight ratio of component (A)/component (B) being 40/60 to 95/5. The suspending agent for suspension polymerization of a vinyl compound of the present invention has an excellent less-foaming effect and an effect of giving uniform and porous vinyl polymer granules.

Process for suspension polymerization of vinyl compound

There are disclosed a secondary suspending agent for suspension polymerization of a vinyl compound (vinyl chloride, etc.) which comprises an aqueous dispersion comprising as the dispersoid, a polyvinyl ester having a degree of hydrolysis of 60 mol% or less, an average degree of polymerization of 4000 or more and an average particle diameter of 100 .mu.m or less; a suspension stabilizing agent comprising 5 to 70% by weight of the secondary suspending agent (PVA, etc.) and 30 to 95% by weight of a water-soluble high molecular compound having a degree of polymerization of 500 or more, the agent being used for suspension polymerization of a vinyl compound; and a process for producing a vinyl polymer (PVC, etc.) comprising suspension polymerizing a vinyl compound by the use of the above suspension stabilizing agent. Both the agents are well suited for producing vinyl polymer granules enhanced in absorption rate of plasticizer, bulk density, removality of residual monomer and porosity.

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Kurashiki, Japan

Shigeki Takada