JPS62275145A - Water-soluble moistureproof film of polyvinyl alcohol - Google Patents

Abstract

PURPOSE:To obtain a water-soluble moistureproof film of PVA superior in waterproofness, by compounding pentaerythritol alone or its specific mixture to a PVA resin and producing a film by a casting process or a melt extrusion process in an aqueous system. CONSTITUTION:A film produced by a casting process or a melt extrusion process in an aqueous system after compounding a polyvinyl alcohol (PVA) resin with 5-20pts.wt. pentaerythritol alone or a mixture thereof which comprises pentaerythritol and its deriv. having chemical structures represented by formulae I and II and where the average degrees of substitution at X and Y on the basis of a hydroxyl radical are not more than 15mol%. In these formulae X represents a halogen element, a group of formula III or -O-NO2; R represents an alkyl; Y represents H, an alkyl or an acyl. As the above-mentioned pentaerythritol, pentaerythritols for industrial use, such as di- and tri-pentaerythritols, can be used.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a polyvinyl alcohol-based water-soluble film with excellent moisture resistance.

[Conventional technology and problems]

Conventionally, polyvinyl alcohol (hereinafter abbreviated as PVA)
has been widely used industrially because it is a water-soluble polymer. Particularly in the film field, it is often used as a water-soluble film and as a raw material for laminate films due to its excellent gas barrier properties. However, the biggest drawback of PVA film is that it has poor moisture resistance. This problem may limit the field of application of PVA films when they are used as packaging materials.

Various techniques have been published to solve these problems. Japanese Patent Publication No. 44-16214 discloses a technique for producing a film by reacting PVA and dextrin in the presence of a borate. However, with this technology,
Moisture resistance cannot be significantly improved, and the water-soluble performance is not sufficient for cold water. Further, the technique of terminally alkylated PVA is disclosed in Japanese Patent Publication No. 46-32506. This technology has insufficient moisture resistance at high humidity, and due to the crystalline nature of the material, its solubility in cold water is not sufficient. Further, Japanese Patent Publication No. 46-18258 discloses a technique for using PVA having a higher alcohol group at the end, but this technique also has problems for the reasons mentioned above.

On the other hand, a technology for manufacturing a film by adding pentaerythritol to PV8 was disclosed in Japanese Patent Application Laid-Open No. 58-83040.
Although disclosed in the above publication, this technique relates to a non-aqueous hot melt extrusion method of PVA, and is essentially different from the present invention. Even if this method were adopted, due to the nature of pentaerythritol, a dehydration reaction would occur if it was heated above its melting point. This causes foaming phenomenon in the film, making it impossible to obtain a satisfactory film.

Furthermore, even when polyethylene glycol, nonionic surfactants, polyacrylic acid, etc. were added to PVA, sufficient results were not obtained.

[Means for solving problems]

In order to address the above-mentioned problems, the inventors of the present invention have conducted intensive studies on water-soluble films with excellent moisture resistance, and have found that PV
By blending pentaerythritol alone or a mixture of pentaerythritol and a specific pentaerythritol derivative with A-based resin and forming a film using a casting method or a water-based melt extrusion method, a water-soluble film with excellent moisture resistance can be created. The present inventors have discovered that the present invention can be obtained, and have completed the present invention.

That is, the present invention provides pentaerythritol alone or pentaerythritol and the general formula (11
or (2) [However, Y - a hydrogen atom, an alkyl group, or an acyl group] A pentaerythritol-based mixture consisting of a pentaerythritol derivative having a chemical structure represented by: 5 to 20% by weight of a pentaerythritol-based mixture in which the amount of
The object of the present invention is to provide a polyvinyl alcohol-based water-soluble moisture-proof film, which is characterized in that it is formed by blending and forming a film by a casting method or an aqueous melt extrusion method.

The PVA-based resin used in the present invention includes not only commercially available fully saponified PVA and partially saponified PVA, but also
PVA-based derivatives such as acetoacetalized PVA and butyralized PVA, and PVA-based copolymers such as vinyl alcohol-vinyl alkyl ether copolymers and vinyl alcohol-allyl alcohol copolymers can also be used. In the case of PVA, a saponification degree of 80 mo1% or higher is suitable, and PVA derivatives and PVA
In the case of PVA-based copolymers, those in the water-soluble range are also used; however, in the case of PVA-based derivatives, acetalized P
Taking VA as an example, it depends on the alkyl chain length, but it is generally 8~
It is 30mo1%. In the case of PVA-based copolymers, the results are approximately the same. And the average alkyl chain length is 0.33~
A value of 4.00 is preferable, and if it is higher than that, problems may arise in water solubility.

Note that the average degree of polymerization of these materials is not particularly limited.

In addition, in the present invention, industrial pentaerythritol including di- and tripentaerythritol can also be used as the pentaerythritol used, and the pentaerythritol derivative represented by the general formula (1)
is suitably a halogen element, R-CO- or -o-Now, and R represents an alkyl group, but the number of carbon atoms is not particularly limited. Moreover, Y shown in the general formula (2) is a hydrogen atom, an alkyl group, or an acyl group. Here again, the number of carbon atoms is not particularly limited. However, as a general tendency, as the number of carbon atoms increases, it is necessary to reduce the proportion of the pentaerythritol derivative in the pentaerythritol-based mixture.

In the case of a pentaerythritol-based mixture, it is desirable that the proportion of the pentaerythritol derivative in the mixture is such that the average degree of substitution of X and Y based on the hydroxyl group is 15 mo1% or less, and if it is out of this range, the moisture resistance will decrease significantly. .

Furthermore, the blending amount of pentaerythritol alone or a pentaerythritol-based mixture is 5% relative to the Pv^-based resin.
-20% by weight is suitable; below this range, sufficient moisture resistance cannot be obtained, and above this range, not only is sufficient moisture resistance not obtained, but the strength of the film is also reduced.

Each PVA resin used in the present invention has its own characteristics. When completely saponified PVA is used as a material, it is suitable when it is desired to dissolve it in hot water rather than in cold water.

Furthermore, if it is desired to quickly dissolve in cold water, it is appropriate to use a film made of partially saponified PVA. If the water-soluble film of the present invention is used for packaging acidic or alkaline substances, a film made of partially saponified PVA is not suitable, but a film made of PVA derivatives such as acetalized PVA and vinyl alcohol-vinyl alkyl ether is not suitable. It is desirable to use a water-soluble film made of a PVA-based copolymer such as a polymer.

The water-soluble film of the present invention has the contradictory properties of being water-soluble and moisture-proof.
This performance can be obtained by adding 5 to 20% by weight of pentaerythritol or the aforementioned pentaerythritol mixture to the PVA resin. When producing the water-soluble film of the present invention, there are no particular difficulties, and production is possible using conventional casting equipment for producing PVA films.

Furthermore, in producing the water-soluble film of the present invention, it is also possible to use an aqueous melt extrusion method. In this case, add 10 to 50% water to a blend of PVA resin and pentaerythritol or pentaerythritol mixture.
The water-soluble moisture-proof film of the present invention can be obtained by adding % by weight, making it uniform, and extruding it from a T-die at 100° C. or lower to form a film.

〔Effect of the invention〕

The water-soluble moisture-proof film of the present invention has contradictory properties of being water-soluble and moisture-proof. Furthermore, acetalized PVA etc. (7) pvA system mi
By using PVA-based copolymers such as PVA copolymers, vinyl alcohol-vinyl alkyl ether copolymers, etc., it is possible to use them as packaging materials that also have acid and alkali resistance, and their range of application is easily widened. You can imagine it.

〔Example〕

The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited only to these Examples.

Example 1 PVA (saponification degree 98.5 mo1%, average polymerization degree 5
Pentaerythritol was added to a 2% aqueous solution of P
It was added in an amount of 5% by weight based on VA and completely dissolved to create a homogeneous solution. Next, 10x10cm2
15 g of the above solution was poured onto a glass plate and dried by heating at a temperature of 95°C to obtain a film with a thickness of 20 microns.

Example 2 Pentaerythritol was added to a 2% by weight aqueous solution of partially saponified PVA (degree of saponification 88.0 mo1%, average degree of polymerization 1700) in an amount of 20% by weight based on the partially saponified PVA, and completely saponified PVA was added. to create a homogeneous solution. Next, on a 10 x 10 cm” glass plate,
15g of the above solution was poured and dried by heating at a temperature of 95°C to obtain a film with a thickness of 20 microns.

Example 3 Acetoacecooled PVA (degree of acetoacetalization 2
Acetoacetalized PV of pentaerythritol was added to a 2% aqueous solution of 2.0 mo1%, average degree of polymerization 480).
It was added in an amount of 15% by weight based on A and completely dissolved to create a homogeneous solution. Next, 10 x 10c
15 g of the above solution was poured onto a glass plate having a diameter of 1.5 mm and was dried by heating at a temperature of 95° C. to obtain a film having a thickness of 20 μm.

Example 4 Butyralized PVA (butyralization degree 8 mo1%,
Pentaerythritol was added to a 2% by weight aqueous solution with an average degree of polymerization of 200) at a concentration of 10% by weight based on the butyralized PVA, and completely dissolved to create a uniform solution. Next, 15 g of the above solution was poured onto a 10 x 10 cm2 glass plate and dried by heating at a temperature of 95°C to obtain a film with a thickness of 20 microns.

Example 5 2 of vinyl alcohol-vinyl butyl ether copolymer (degree of etherification 10 mo1%, average degree of polymerization 1400)
Pentaerythritol (containing 4% by weight of dipentaerythritol and 2% by weight of tripentaerythritol) is added to the weight% aqueous solution in an amount of 15% by weight based on the vinyl alcohol-vinyl butyl ether copolymer, and completely dissolved. A homogeneous solution was created. Then 10 x 1
15 g of the above solution was poured onto a 0 am'' glass plate and dried by heating at a temperature of 95°C to obtain a film with a thickness of 20 microns.

Example 6 Vinyl alcohol-allyl alcohol copolymer (allyl alcohol 20 mo1%, average degree of polymerization 2200) 2
Pentaerythritol was added to the weight% aqueous solution in an amount of 15% by weight based on the vinyl alcohol-allyl alcohol copolymer, and completely dissolved to create a uniform solution. Next, 15 g of the above solution was poured onto a 10 x 10 cm glass plate and dried by heating at a temperature of 95°C to obtain a film with a thickness of 20 microns.

Example 7 Acetoacetalized PVA (degree of acetoacetalization 2
2.0 mo1%, average degree of polymerization 480) to 850 g of powder,
150 g of pentaerythritol was blended and mixed for 1 hour in a Blengu, and the mixture was transferred to a Nigu, and while stirring, 150 g of water was gradually added and stirred for 1 hour to form a uniform powder. This sample was put into an extruder connected to a T-die and formed into a film at a temperature of 95°C to obtain a film of 21 microns.

Next, it was dried at 100° C. for 10 minutes to obtain a sample film. The thickness of this film was 20 microns.

Example 8 PVA (saponification degree 98.5 mo1%, average polymerization degree 50
Partially chlorinated pentaerythritol (C1 = 8 mol %) was added to a 2 wt% aqueous solution of 0) at a ratio of 10% to PVA.
% by weight and completely melted to create a homogeneous solution. Next, 15 g of the above solution was poured onto a 10×10 cm 2 glass plate and dried by heating at a temperature of 95° C. to obtain a film with a thickness of 20 microns.

Example 9 Acetoacecooled PVA (degree of acetoacetalization 2
Partially acetylated pentaerythritol (degree of acetylation = 5 mol %) was added to a 2 wt % aqueous solution of 2.0 mol 1% (average polymerization degree 480) at a concentration of 10 wt % based on PVA, and completely dissolved. A homogeneous solution was created.

Next, 15 g of the above solution was poured onto a 10×10 cm 2 glass plate and dried by heating at a temperature of 95° C. to obtain a film with a thickness of 20 microns.

Example 10 PVA (saponification degree 98.5 mo1%, average polymerization degree 17
Partially nitroesterified pentaerythritol (degree of nitroesterification = 4mo1%) was added to a 2% aqueous solution of 00).
was added in an amount of 10% by weight based on PVA and completely dissolved to create a homogeneous solution.

Next, 15 g of the above solution was poured onto a 10 x 10 cm'' glass plate and dried by heating at a temperature of 95°C to obtain a film with a thickness of 20 microns.

Example 11 Partially formalized pentaerythritol (degree of formalization = 15 mo 1%) was added to a 2 wt% aqueous solution of PVA (saponification degree 98, 5 mo 1%, average polymerization degree 1700).
was added in an amount of 10% by weight based on PVA and completely dissolved to create a homogeneous solution. Then 10 x 1
15 g of the above solution was poured onto a 0 cm" glass plate and dried by heating at a temperature of 95°C to obtain a film with a thickness of 20 microns.

Example 12 Acetoacecooled PVA (degree of acetoacetalization 22
．． Partially acetoacetalized pentaerythritol (degree of acetoacetalization = 3 mo1%) was added to a 2 wt% aqueous solution of 0 mo1%, average polymerization degree 480) in an amount of 10 wt 1% based on the acetoacetalized PVA, and completely to create a homogeneous solution. Then 10 x 10
15 g of the above solution was poured onto a cn+2 glass plate and dried by heating at a temperature of 95°C to obtain a film with a thickness of 20 microns.

Example 13 PVA (saponification degree 98.5 mo1%, average polymerization degree 17
Partially butyric acid esterified pentaerythritol (degree of esterification = 4 mo1%) was added to a 2% aqueous solution of 00) by PV.
It was added in an amount of 15% by weight based on A, completely dissolved, and a uniform solution was created. Then 10 x 10cm
15 g of the above solution was poured onto the glass plate No. 2 and dried by heating at a temperature of 95° C. to obtain a film with a thickness of 20 microns.

Example 14 Acetoacecooled PVA (degree of acetoacetalization 2
2, 0mo 1%, average polymerization degree 480), partially caproic acid esterified pentaerythritol (esterification degree = 3mo 1%) was added to PVA at 15% by weight.
It was added in an amount of % by weight, completely dissolved, and a homogeneous solution was created. Next, 15 g of the solution was poured onto a 10 x 10 cm glass plate and dried by heating at a temperature of 95°C to obtain a film with a thickness of 20 microns.

Example 15 PVA (saponification degree 98.5 mo1%, average polymerization degree 17
Partially butyralized pentaerythritol (butyralization degree = 5 mo 1%) was added to a 2% aqueous solution of PVA
It was added in an amount of 10% by weight, completely dissolved, and a homogeneous solution was created. Next, 10 X 10cn+
15 g of the above solution was poured onto the glass plate No. 2 and dried by heating at a temperature of 95° C. to obtain a film with a thickness of 20 microns.

Comparative Example 1 A 2% by weight aqueous solution of PVA (saponification degree 98.51lIo1%, average degree of polymerization 500) was prepared, 15g of this solution was poured onto a 10 x 10cc glass plate, and the temperature was 9.
It was dried by heating at 5°C to obtain a film with a thickness of 20 microns.

Comparative Example 2 PVA (saponification degree 98.5 mo1%, average polymerization degree 1
A 2% aqueous solution of 700) was prepared, and 1 wt.
Glycerin was added to give 0% by weight to obtain a homogeneous solution. 15 g of this solution was poured onto a 10 x 10 cm2 glass plate and dried by heating at a temperature of 95°C.
A 20 micron thick film was obtained.

Comparative Example 3 A 2% by weight aqueous solution of partially saponified PVA (degree of saponification 88.4 mo1%, average degree of polymerization 1700) was prepared, and glycerin was added to the partially saponified PVA to make it 10% by weight, A homogeneous solution was obtained. 15g of this solution
Pour it onto a 10cm2 glass plate and heat it to a temperature of 9.
It was dried by heating at 5°C to obtain a film with a thickness of 20 microns.

Comparative Example 4 Acetoacecooled PVA (degree of acetoacetalization 2
A 2% by weight ice solution with 2.0 mo1% and an average degree of polymerization of 480) was prepared, and 15 g of this solution was poured onto a 10 x 10 cm glass plate and dried by heating at a temperature of 95°C to form a 20 micron thick film. Obtained.

Comparative Example 5 Vinyl alcohol-vinyl butyl ether copolymer, degree of etherification IQ mo1%, average degree of polymerization 1700)
Create a wt% aqueous solution and add 15g of this solution to 10 x 1
The mixture was poured onto a 0cm" glass plate and dried by heating at a temperature of 95°C to obtain a film with a thickness of 20 microns.

Comparative example 6 PVA (saponification degree 98.5 mo1%, average polymerization degree 50
0), 15% by weight of pentaerythritol is added, and ■
After mixing in Brengu for 1 hour, at 105°C under nitrogen atmosphere.
I let it dry for 1 hour. The moisture content of this blend was determined by Karl Fischer method and was 0.7% by weight.

After 48 hours, an attempt was made to form a film at a temperature of 220° C. using a melt extrusion method, but a foaming phenomenon assumed to be caused by the dehydration reaction of pentaerythritol was observed, and a film could not be obtained.

Comparative Example 7 PVA (saponification degree 98.5 mo1%, average polymerization degree 50
Pentaerythritol was added to a 2% aqueous solution of PV
It was added in an amount of 25% by weight based on A and completely dissolved to create a homogeneous solution. Then 10 x 10cm
15 g of the above solution was poured onto a glass plate and dried by heating at a temperature of 95°C to obtain a film with a thickness of 20 microns.

Comparative Example 8 Partially formalized pentaerythritol (degree of formalization = 20 mo 1%) was added to a 2 wt % aqueous solution of PVA (saponification degree 98, 5 mo 1%, average polymerization degree 1700) so that the amount was 10 wt % based on PVA. was added to completely dissolve and create a homogeneous solution. Next, 10x10cl
15 g of the above solution was poured onto a No. 112 glass plate and dried by heating at a temperature of 95° C. to obtain a film with a thickness of 20 microns.

Comparative Example 9 PVA (saponification degree 98.5 mo1%, average polymerization degree 50
Partially chlorinated pentaerythritol (CI = 5 mo1%) was added to a 2% aqueous solution of
It was added in an amount of % by weight, completely dissolved, and a homogeneous solution was created. Next, 15 g of the above solution was poured onto a 10×10 cmz glass plate and dried by heating at a temperature of 95° C. to obtain a film with a thickness of 20 microns.

The films prepared in Examples 1 to 12 and Comparative Examples 1 to 9 were evaluated for water solubility, moisture resistance, acid resistance, alkali resistance, and heat sealability using the test methods shown below.

The evaluation results are shown in Table 1.

As is clear from Table 1, Examples 1 to 12 showed superior results compared to the comparative examples.

Test method> (1) Water-soluble The film was cut into 2×2CIIIz and heated at 10°C.

The water solubility was confirmed by putting it into water at 30°C and 50°C.

(2) Moisture-proofing Put 5 g of anhydrous calcium carbonate in a glass petri dish with a diameter of 38 mm and a depth of 50 mm, seal the opening with a film, and leave it under conditions of 40°C and 80% relative humidity to allow water to vaporize. The weight increase due to permeation was measured. Then, the amount of weight increase after 24 hours per 1% was calculated.

(3) 90g of ion-exchanged water adjusted to pH=3.0 with acid-resistant hydrochloric acid
30 g of pulp powder was added to make a uniform pancake-like material, into which a film was introduced, both sides of the film were brought into complete contact, and left at 40 DEG C. and 80% relative humidity. After 20 days, the film was collected and its water solubility at 10°C was confirmed.

(4) Add 3 parts of ion-exchanged water to 70 g of anhydrous alkali-resistant powdered sodium carbonate.
A wet powder was prepared by adding 0 g of the powder, and a film was placed in the powder, and both sides of the film were brought into complete contact with each other, and the film was left at 40° C. and a relative humidity of 80%.

After 20 days, the film was collected and its water solubility at 10°C was confirmed.

(5) Heat-sealability The product was sealed at 140° C. for 1 second using a heat sealer, and the condition was confirmed.

Claims (1)

[Claims] 1. Pentaerythritol alone or pentaerythritol and the general formula (1
) or (2) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) [However, There are chemical formulas, tables, etc. ▼ [However, Y = hydrogen atom, alkyl group, or acyl group] A pentaerythritol-based mixture consisting of a pentaerythritol derivative with the chemical structure represented by 5 to 20% by weight of a pentaerythritol mixture with an average degree of substitution of 15 mol% or less
1. A polyvinyl alcohol-based water-soluble moisture-proof film, characterized in that it is formed by blending and forming a film by a casting method or an aqueous melt extrusion method. 2. The polyvinyl alcohol resin is a polyvinyl alcohol derivative such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, or acetalized polyvinyl alcohol, or a polyvinyl alcohol copolymer such as a vinyl alcohol-vinyl alkyl ether copolymer. The polyvinyl alcohol-based water-soluble moisture-proof film according to claim 1, which is one or more types.