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

Patent metadata

Field	Value
Publication number	US-10815039-B2
Application number	US-201615777452-A
Country	US
Kind code	B2
Filing date	Dec 7, 2016
Priority date	Dec 18, 2015
Publication date	Oct 27, 2020
Grant date	Oct 27, 2020

Abstract

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/m2·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.

First claim

The invention claimed is:

1. A method of storing a melt-processable polyvinyl alcohol resin comprising:
providing a packaging bag comprising a film having
a methanol vapor transmission rate of 0.5 to 1000 g/m 2 ·day measured in conformity with Testing Methods for Determination of Water Vapor Transmission Rate of Moisture-Proof Packaging Materials—Dish Method specified in JIS Z0208,
a water vapor transmission rate of not higher than 1000 g/m 2 ·day measured at 40° C. at 90% RH in conformity with JIS Z0208, and
a thickness of 1 to 500 μm; and

sealingly packaging melt-processable polyvinyl alcohol resin particles in the packaging bag, the melt-processable polyvinyl alcohol resin particles comprising residual organic solvent;
wherein a material for the film is at least one selected from the group consisting of high-density polyethylene, medium-density polyethylene, low-density polyethylene, polypropylene, and polyester, and
wherein the packaging bag is capable of releasing the residual organic solvent evaporated from the melt-processable polyvinyl alcohol resin during its storage in the packaging bag.

2. The method according to claim 1 , wherein the melt-processable polyvinyl alcohol resin is a polyvinyl alcohol resin having a primary hydroxyl group-containing structural unit at its side chain.

3. The method according to claim 1 , wherein the structural unit having the primary hydroxyl group-containing structural unit at the side chain is a structural unit having a 1,2-diol structure at the side chain.

4. The method according to claim 1 , wherein the film has a multilayer structure including
a base layer,
a methanol vapor permeable film layer, and
a protective layer.

5. The method of claim 1 , wherein the packaging bag has a thickness of 10 to 2000 μm.

6. The method of claim 4 , wherein at least one of the base layer and the protective layer is craft paper.

7. The method of claim 1 , wherein the content of organic solvent in the melt-processable polyvinyl alcohol resin particles is 0.1 to 10 wt %.

Assignees

• Nippon Synthetic Chem Ind Co Ltd
• Mitsubishi Chem Corp

Inventors

• Yamauchi Yoshihito
• Sakai Norihito

Classifications

• B32B27/10 Primary

  of paper or cardboard · CPC title

• B32B2307/31

  Heat sealable · CPC title

• B32B29/002

  as the main or only constituent of a layer, which is next to another layer of the same or of a different material (next to a layer of a particular substance B32B9/06; next to a bituminous or tarry layer B32B11/06; next to a water-setting substance layer B32B13/08; next to a metal layer B32B15/12; next to a glass layer B32B17/065; next to a layer formed of natural mineral fibres or particles B32B19/046; next to a wood layer B32B21/06; next to a cellulosic plastic layer B32B23/06; next to a natural or synthetic rubber layer B32B25/06; next to a synthetic resin layer B32B27/10) · CPC title

• B32B27/36

  comprising polyesters · CPC title

• B32B27/40

  comprising polyurethanes · CPC title