Mitsubishi Chemical Corporation

The Nippon Synthetic Chemical Industry Co., Ltd.

Yoshihito Yamauchi

Norihito Sakai

Shusaku Mandai

Takahiro Saka

Yusuke Muramatsu

Junki Fukuda

A method for producing a polyvinyl alcohol resin having an absorbance of not less than 0.2 at 280 nm, which includes: melt-kneading a polyvinyl alcohol resin material; extruding the resulting melt-kneaded polyvinyl alcohol resin into a sheet; cooling the resulting polyvinyl alcohol resin sheet; and pulverizing the cooled polyvinyl alcohol resin sheet. The method ensures a higher productivity and an excellent long-run property.

Method for producing polyvinyl alcohol resin

The present invention relates to a polyvinyl alcohol-based resin, wherein when the polyvinyl alcohol-based resin is made into a 0.1 wt % aqueous solution, an absorbance (X) at a wavelength of 320 nm in an ultraviolet absorption spectrum thereof is 0.3 or more, and a ratio (Y/X) of an absorbance (Y) at a wavelength of 380 nm to the absorbance (X) at a wavelength of 320 nm is 0.09 or more.

Polyvinyl alcohol-based resin, method for producing polyvinyl alcohol-based resin, dispersing agent and dispersing agent for suspension polymerization

An object of the present invention is to provide a PVA-based resin having a small distribution in degree of heat treatment in which the degree of heat treatment does not depend on a particle diameter. The polyvinyl alcohol-based resin of the present invention has an absorbance at 280 nm of 0.3 or more when being made to a 0.1 wt % aqueous solution and satisfies the following Formula (1): 0.9&#x2264;X/Y&#x2264;1.2 (in Formula (1), Xrepresents an absorbance at 320 nm of a 0.1 wt % aqueous solution of a polyvinyl alcohol-based resin having a particle diameter larger than 1000 &#x3bc;m and 1680 &#x3bc;m or less, and Yrepresents an absorbance at 320 nm of a 0.1 wt % aqueous solution of a polyvinyl alcohol-based resin having a particle diameter larger than 212 &#x3bc;m and 500 &#x3bc;m or less).

Poly(vinyl alcohol)-based resin, dispersing agent and dispersing agent for suspension

A packaging bag for packaging a melt-processable polyvinyl alcohol resin is formed from a film having a methanol vapor transmission rate of 0.5 to 1000 g/m&#xb7;day. A method of storing a melt-processable polyvinyl alcohol resin includes the step of sealingly packaging melt-processable polyvinyl alcohol resin particles with the use of the packaging bag formed from the aforementioned film. Where the melt-processable polyvinyl alcohol resin is packaged with the use of the packaging bag, therefore, an organic solvent remaining in the packaged polyvinyl alcohol resin can be released in the form of vapor to the outside through the packaging bag to dissipate, whereby the resulting polyvinyl alcohol resin has a reduced organic solvent concentration after storage thereof in the packaging bag. As a result, the melt-processable polyvinyl alcohol resin is improved in forming stability.

Packaging bag, and method for storing melt-processable polyvinyl alcohol resin with the use of the packaging bag

Acetoacetyl group-containing polyvinyl alcohol resin powder composition containing a C1 to C3 alcohol in an amount of 0.5 to 4 wt % is produced by allowing a powdery polyvinyl alcohol resin to react with diketene, washing the resulting acetoacetyl group-containing polyvinyl alcohol resin particles with the C1 to C3 alcohol to remove an unreacted portion of the diketene, and drying the intermediate acetoacetyl group-containing polyvinyl alcohol resin particles composition at a temperature of 40&#xb0; C. to 120&#xb0; C. at a pressure of not higher than 20 kPa after the washing. The acetoacetyl group-containing polyvinyl alcohol resin powder composition thus produced is highly soluble in water.

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Osaka, Japan

Yoshihito Yamauchi