WO2003060007A1

WO2003060007A1 - Polyvinyl alcohol film

Info

Publication number: WO2003060007A1
Application number: PCT/JP2002/013656
Authority: WO
Inventors: Tomoyoshi Mizutani
Original assignee: The Nippon Synthetic Chemical Industry Co., Ltd.
Priority date: 2002-01-11
Filing date: 2002-12-26
Publication date: 2003-07-24
Also published as: JP2003206380A; JP4338117B2; AU2002366981A1

Abstract

A polyvinyl alcohol film which comprises (A) a polyvinyl alcohol resin having a carboxy content of 1 to 10 mol% and (B) a polyvinyl alcohol resin whose 4 wt.% aqueous solution has a viscosity at 20°C of 1 to 10 mPa·s and which contains no carboxy group. The film is heat-sealable and gives a heat-sealed part with excellent water solubility.

Description

Akira Itoda Polyvinyl alcohol film Technical field

TECHNICAL FIELD The present invention relates to a polyvinyl alcohol-based film comprising a resin component containing a propyloxyl group-containing polyvinyl alcohol-based resin. More specifically, the present invention relates to a water-soluble polyvinyl alcohol-based film that can be heat-sealed without lowering the water-solubility. Background art

Traditionally, taking advantage of the water solubility of polyvinyl alcohol resin (hereinafter sometimes abbreviated as PVA), chemicals such as agricultural chemicals and detergents are packaged in bags made of PVA film (units). Packaging) has been proposed.

As a water-soluble unit packaging bag used for such purposes, the present applicant also disclosed in Japanese Utility Model Laid-Open No. 49-38680 an alkaline substance composed of a film containing a modified polyvinyl alcohol-based resin containing lipoxyl group as a main component. A water-soluble unit packaging bag is proposed. Japanese Patent Application Laid-Open No. H04-170405 also contains 1 to 10 mol% of a lipoxyl group, has a saponification degree of 80 mol% or more, and has a 4% by weight at 20 ° C. A water-soluble film of modified polyvinyl alcohol having an aqueous solution viscosity of 4.6 cps or more is described.

However, although the carboxyl group-containing PVA film is excellent in water solubility, the water solubility of the treated portion may be reduced by heat sealing treatment when a drug or the like is embedded. In other words, when the PVA film bag is filled with a drug or the like and the opening is sealed with heat seal, the crystallization of PVA is promoted, or the water solubility of the heat-sealed part decreases. And PV AThe original water solubility may not be fully exhibited. This suggests that the more the heat-sealed part is heated to ensure sufficient heat-sealing adhesiveness, the lower the water solubility.

Therefore, a PVA film that is excellent in both heat sealability (adhesive strength of the heat seal portion) and water solubility of the heat seal portion is desired.

In addition, if the unit packaging bag containing the alkaline substance is stored for a long period of time, saponification of the PVA film may progress due to contact with the alkaline substance, which may cause a problem that the water solubility decreases.

An object of the present invention is to provide a PVA film which is excellent in both heat sealability and water solubility of a heat seal portion.

It is a further object of the present invention to provide a water-soluble packaging material that is useful for packaging various chemicals, particularly alkaline substances, without decreasing the water solubility even if the alkaline substance is packaged for a long period of time. is there. Disclosure of the invention

The present inventor has conducted intensive studies in view of the above situation, and as a result, the viscosity of a 4% by weight aqueous solution at 20 ° C. of PVA containing 1 to 10 mol% of a lipoxyl group is 1 to 10 OmPa's. It has been found that a water-soluble polyvinyl alcohol-based film excellent in both heat sealability and water solubility of the heat seal portion can be obtained by blending with PVA which does not contain lipoxyl group.

Thus, the present invention relates to (A) a polyvinyl alcohol-based resin containing 1 to 10 mol% of a carboxyl group and (B) a 4% by weight aqueous solution at 20 ° C having a viscosity of 1 to 1 OmPa's. Provided is a polypinyl alcohol-based film made of a polyvinyl alcohol-based resin having no group.

The average degree of saponification of PVA (A) and PVA (B) contained in the film is preferably 80 to 97 mol%, whereby the film has The alkali resistance is improved. BEST MODE FOR CARRYING OUT THE INVENTION The PVA (A) containing a carboxyl group used in the present invention can be produced by any method. For example, (a) a method in which an unsaturated monomer having a hydroxyl group and a vinyl ester compound are polymerized and then genominated, (b) an alcohol having a hydroxyl group, or an alcohol having a hydroxyl group and an aldehyde Such as a method in which a vinyl ester compound is polymerized in the presence of a chain transfer agent containing a lipoxyl group, such as a compound having a functional group such as a thiol group or a thiol group, followed by genification, but is not limited thereto. is not. These methods will be described more specifically.

(a) A method of polymerizing an unsaturated monomer having a hydroxyl group and a vinyl ester compound followed by saponification

Examples of the monomer having a hydroxyl group include ethylenically unsaturated dicarboxylic acids (maleic acid, fumaric acid, itaconic acid, etc.), ethylenically unsaturated dicarboxylic acid monoesters (monoalkyl maleate, monoalkyl fumarate) Esters, monoalkyl esters of itaconic acid, etc.), ethylenically unsaturated dicarbonic acid diesters (dialkyl maleate, dialkyl fumarate, dialkyl fumarate, etc.) (However, these diesters are It is necessary to change to a carboxyl group by hydrolysis during saponification.], Ethylenically unsaturated carboxylic anhydrides (anhydrous maleic acid, itaconic anhydride, etc.), monomers such as (meth) acrylic acid, etc. And salts thereof, among which ethylenically unsaturated Power Rupon Sanmo monoester and salts thereof are preferably used.

In addition, when a lipoxyl group is introduced, there is a concern that the lactone ring is formed during the saponification reaction or during the drying, resulting in insolubilization. In addition, PVA (A) containing a lipoxyl group can be produced according to a method which is already known as a method for producing polyvinyl alcohol having good water solubility and, for example, 0.5 to 2. A method in which vinyl ester is copolymerized with maleic acid or maleic anhydride in an organic solvent in the presence of 0 molar equivalents of alcohol and saponified, Alkali metal (Na, etc.) of alkaline metal salts such as Na salt of lipoxyl group in PVA containing dilute metal (Ca, Mg, Cu, etc.) There are ways to do it.

(b) A method of polymerizing a vinyl ester compound in the presence of a carboxyl group-containing chain transfer agent such as a carboxyl group-containing alcohol, a carboxyl group-containing aldehyde, or a thiol-oxyl group-containing thiol, and then converting the vinyl ester-based compound to a genogen, the chain transfer agent used in the method. Particularly, a compound derived from a thiol having a large chain transfer effect is effective, and specific examples thereof include compounds represented by the following formulas (1) to (3) and salts thereof.

HS- (CH ₂ ¾-COOH (1)

COOH COOH HS— C- (CH ₂ tCR ₃ (2)

Ri R ₂

[In the general formulas (1) and (2), n represents 0 or an integer of 1 to 5, and R ₂ and R ₃ each represent a hydrogen atom or a lower alkyl group (which may contain a substituent). ]

CH ₃ (CH ₂ ) H-CH—COOH (3)

SH [In the general formula (3), n is 0 or an integer of 1 to 20. Representative examples of these thiol compounds include mercaptoacetic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, and 2-mercaptostearic acid.

Examples of the vinyl ester compound used in the above methods (a) and (b) include vinyl formate, vinyl acetate, vinyl trifluoroacetate, biel propionate, vinyl butyrate, vinyl caprate, vinyl laurate, and versatic. Examples thereof include vinyl acid, vinyl palmitate, and vinyl stearate, which are used alone or in combination. Practically, biel acetate is preferable.

Further, in the present invention, at the time of the polymerization, the unsaturated monomer having a propyloxyl group as described above and another monomer copolymerizable with the vinyl ester compound are used to reduce the water solubility of the obtained PVA. A small amount may be used as long as it is not damaged. The amount of other monomers to be used is usually 0 to 30 mol%, preferably 0.1 to 20 mol%, especially 0.1 to 10 mol%, based on all monomers. Specific examples of other monomers include alkylesters of ethylenically unsaturated monocarboxylic acids, such as methyl crotonate, ethyl crotonate, methyl sorbate, ethyl sorbate, alkyl oleate, (meth) acrylic acid Methyl, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, (meth) acrylic Decyl acid,

Hexadecyl (meth) acrylate, octyl decyl (meth) acrylate; aryl esters of saturated carboxylic acids, such as aryl stearate, aryl aryl laurate, fatty aryl coconut oil, aryl aryl octylate, aryl aryl butyrate, etc .; α-olefin , For example, ethylene, propylene, hi-hexene, _α -octene, a-decene, -dodecene, α-hexadecene, a-octadecene Alkylbier ethers such as propyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, dodecyl vinyl ether, tetradecyl vinyl ether, hexadecyl vinyl ether, octyl decyl vinyl ether, etc .; Alkylaryl ethers, such as propylaryl ether, butylaryl ether, hexylaryl ether, octylaryl ether, decylaryl ether, dodecylaryl ether, tetradecylaryl ether, hexadecylaryl ether, octadecyl And other vinyl compounds such as (meth) acrylamide, (meth) acrylonitrile, styrene, and pinyl chloride.

In carrying out the polymerization, the polymerization method is not particularly limited, and a known polymerization method may be used arbitrarily. Usually, a solution polymerization is carried out using an alcohol such as methanol, ethanol or isopropyl alcohol as a solvent. Of course, emulsion polymerization and suspension polymerization are also possible. As a method of charging the monomers in such solution polymerization, first, the total amount of the vinyl ester compound and a part of the unsaturated monomer having a carboxyl group are charged, polymerization is started, and the remaining epoxy resin is charged. Any method such as a method of adding the group-containing unsaturated monomer continuously or in a divided manner during the polymerization period, a method of charging all the monomers at once, or the like may be used. The polymerization reaction is carried out using a known radical polymerization catalyst such as azobisisobutyronitrile, acetyl peroxide, benzoyl peroxide, lauroyl peroxide and the like. The reaction temperature is selected from the range of 50 ° C. to the boiling point of the solvent.

The saponification of the obtained vinyl ester polymer can be carried out according to a known method. For example, saponification is performed by dissolving the obtained polymer in alcohol and in the presence of an alkali catalyst. Examples of the alcohol include methanol, ethanol, and butanol. The concentration of the polymer in the alcohol is selected from the range of 20 to 50% by weight. Alkali catalysts such as hydroxides and alcoholates of alkali metals such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate, and potassium methylate can be used as the genation catalyst. In some cases, it is also possible to use an acid catalyst. The amount of the saponification catalyst to be used is 1 to 100 mmole equivalent to the vinyl ester compound.

In addition to the above method, the carboxyl group-containing PVA (A) can be produced, for example, by a method in which an alkylene oxide is added to polyvinyl alcohol (a partially genated product or a completely saponified product).

The content of the lipoxyl group (the amount of modification with carboxylic acid) in the lipoxyl group-containing PVA (A) used in the present invention is 1 to 10 mol%, further 1 to 8 mol%, particularly 1 to 10 mol%. It is necessary to be 6 mol%, especially 1 to 5 mol%. If the content is less than 1% by mole, the water solubility of the film is reduced, and if it exceeds 10% by weight, sufficient film strength cannot be obtained.

The degree of genification of the carboxyl group-containing PVA (A) is not particularly limited, but is 88 to 99 mol%, more preferably 89 to 98 mol%, particularly 90 to 97 mol%, particularly 90 to 96 mol%. Is preferred. If the degree of saponification is less than 88 mol%, the water solubility of the film will decrease when the chemical is packaged in a film and stored for a long time, and if it exceeds 99 mol%, the water solubility of the film will decrease. In the direction.

Further, the viscosity of the carboxyl group-containing PVA (A) at 20 ° C in a 4% by weight aqueous solution should be 15 to 6 OmPa's (further 17 to 55 mPa's, particularly 18 to 5 OmPa-s, especially 20 to 45 mPa's). If the viscosity is less than 15 mPa's, the mechanical strength of the film tends to decrease. Conversely, if it exceeds 6 OmPa-s, the viscosity of the aqueous solution becomes too high, which is not preferable.

The non-carboxyl-containing PVA (B) used in conjunction with the above-mentioned lipoxyl group-containing PVA (A) includes any other than the PVA (A). As the PVA-based polymer, for example, unmodified PVA or PVA modified with a monomer other than the above-mentioned carboxyl group-containing monomer can be used. It is preferable to use unmodified PVA from the viewpoint of heat sealing properties.

PVA (B) containing no carboxylic group can be produced according to the above-mentioned PVA (A) containing a carboxyl group. The 4% by weight aqueous solution viscosity of such PVA (B) at 20 ° C. must be 1 to 1 OmPa's (further 2 to 9 mPa's, particularly 3 to 8 mPa's, particularly 3 to 7 mPa's). When the viscosity is less than lmPa's or more than 1 OmPa's, the effect of improving the heat sealability cannot be sufficiently obtained.

Although the saponification degree of PVA (B) is not particularly limited, it is preferably 65 to 95 mol% (further 70 to 94 mol%, particularly 75 to 92 mol%, particularly 80 to 90 mol%). If the saponification degree is less than 65 mol%, the water solubility of the obtained PVA film tends to decrease, and if it exceeds 95 mol%, the water solubility tends to decrease.

The above content ratio (A / B) of PVA (A) and PVA (B) is not particularly limited as long as the content of PVA (A) is larger than the content of PVA (B), but the alkali resistance In view of this, it is preferable that the ratio is 80Z20 to 95Z5, more preferably 81Z19-946, particularly 82Z18 to 93Z7, particularly 83Z17 to 92Z8 (weight ratio). If the content ratio A / B is less than 80 to 20, the water solubility of the PVA film decreases when the alkaline drug is stored in a packaging bag for a long time. If the AZB ratio exceeds 95 Z5, the effect of improving the heat sealability cannot be sufficiently obtained.

Further, in the present invention, the content ratio of PVA (A) and (B) is adjusted within the above range in consideration of each degree of saponification, so that PVA contained in the polyvinyl alcohol-based film is adjusted. The average degree of saponification is 80-97 mol% (further 81-97 mol%, especially 82-96 mol%, especially 83-9 6

9

(6 mol%) is very preferable. By setting the saponification degree to such a value, the water solubility does not decrease even if the alkaline substance is packaged for a long time, and it is useful for packaging the alkaline substance. It is possible to obtain a polyvinyl alcohol-based film.

Here, the average degree of genification is a degree of genification measured in accordance with JIS 672 6 using a polyvinyl alcohol-based film containing PVA (A) and (B) as a sample.

The polyvinyl alcohol-based film of the present invention comprises PVA (A) and (B) as described above, and the film comprises PVA (A) and

It is obtained by forming a film of the blend of (B). In the film formation, a known method can be employed without any particular limitation.

For example, a casting method can be adopted, and water is added to a blend (powder) of PVA (A) and (B) to a concentration of 10 to 50% by weight (and even 15 to 35% by weight). %) Of an aqueous solution of a blend, and, if necessary, a surfactant and Z or a plasticizer, and then cast onto a surface of a metal roll having a surface temperature of about 90 to 100 ° C. By drying, a film containing PVA (A) and (B) can be obtained. Usable surfactants include ordinary surfactants, such as polyoxyethylene nonylphenyl ether, polyoxyethylene octyl nonyl ether, polyexylene dodecyl finyl ether, and polyxylene ethylenealkylaryl.

Alkylene alkyl ether phosphate ester monoethanolamine salt, polyoxetylene lauryl amino ether, polyoxyethylene stearyl 6

10 Lumino ether. The amount of surfactant used depends on the blend

The amount is 0.1 to 10 parts by weight, and more preferably 0.3 to 5 parts by weight, based on 100 parts by weight. As the plasticizer, an ordinary plasticizer can be used, and examples thereof include glycerin, diglycerin, polyethylene glycol, polypropylene dalicol, and trimethylolpropane. The amount of the plasticizer used is 1 to 40 parts by weight, and more preferably 3 to 35 parts by weight, based on 100 parts by weight of the blend.

The thickness of the polyvinyl alcohol-based film of the present invention varies depending on the application and cannot be stated unconditionally.For example, in applications such as drug packaging, it is 10 to 80 m (more preferably 15 to 60 ir, especially 20 to 40 m) is preferred. If the thickness is less than 10, the mechanical strength of the film decreases, and if it exceeds 80 m, the water solubility of the film decreases and the efficiency during film formation decreases.

The surface of the film may be plain, or one or both surfaces of the film may be provided with an embossed pattern, satin pattern, or the like. The polyvinyl alcohol-based film of the present invention contains other water-soluble polymers (sodium polyacrylate, polyethylene oxide, polybierpyrrolidone, dextrin, chitosan, chitin, etc.) as long as the object of the present invention is not impaired. Ordinary additives such as methylcellulose, hydroxyethylcellulose, starch, etc., a protective agent, a coloring agent, and a filler (for example, inorganic fillers such as titanium oxide and talc) may be blended.

The thus obtained polyvinyl alcohol-based film of the present invention is useful for various packaging applications and the like, but is especially useful for unit packaging of drugs and the like. In the case of unit packaging using the PVA film of the present invention, the drug is not particularly limited. However, since the film is water-soluble, it is suitable for packaging a drug to be used after being dissolved or dispersed in water. The drug may be alkaline, neutral, or acidic. Particularly, the pH when dissolved or dispersed in water PT / JP02 / 13656

The effect of the present invention can be sufficiently exerted even when the drug has a value of 11 or more. The shape of the drug may be any of granules, tablets, powders, powders, and the like, and in some cases, may be liquid. Specific examples of the chemical include powdered stone, synthetic detergents, pesticides, bactericides, deodorants, insecticides, and the like. In particular, the film of the present invention is suitable for unit packaging of detergents and agricultural chemicals.

In packaging a drug using the polyvinyl alcohol-based film of the present invention, a) a method of packaging the drug after previously forming the film into a bag, and a method of packaging a drug directly with the film. And the like.

Next, the present invention will be described in more detail with reference to examples. In the examples, “%” and “parts” are based on weight unless otherwise specified.

Example 1

Carboxyl group-containing PVA (A) having 2 mol% modified with monomethyl maleate and having a saponification degree of 96.0 mol% and a 4% by weight aqueous solution in 20 having a viscosity of 28 mPa's is 85 parts, and the degree of genification is 8 8 A 4% by weight aqueous solution at 20 ° C. at 20 ° C. Unmodified PVA (B) having a viscosity of 5 mPa's 15 parts of a blend was dissolved in water to obtain a 25% aqueous solution. After mixing 20 parts of glycerin and 1.0 part of polyoxyethylene nonyl phenyl ether to 100 parts, the mixture was cast on a metal roll surface having a surface temperature of about 94 ° C, dried, and dried. A polyvinyl alcohol-based film of the present invention having a thickness of 30 / m was obtained. The average saponification degree of the film was 95 mol% as measured according to JIS K6 726.

The following evaluation was performed on the obtained polyvinyl alcohol-based film.

(Heat seal strength)

2 Under a 3 ° C, 50% RH atmosphere, use a heat sealer (YS S type heat sealer manufactured by Yasuda Seiki Seisaku-Sho, Ltd.) to make the upper crimping section 200 ° C and the lower crimping section 1 The obtained two polyvinyl alcohol-based films were heat-sealed under the conditions of 00 ° C, pressure of about 2 MPa, and 0.5 seconds, and the heat-sealing strength (N / 15 mm) was measured. The tensile speed at the time of measuring the heat seal strength was 200 mm / min.

(Solubility of heat-sealed part)

Heat-sealing is performed in the same manner as above, and a part of the obtained heat-sealed part is used as a sample (3 cm X lcm) in a 1000 ml 1 volume beaker containing 1000 ml water (20 ° C). While stirring with a stirrer (500 rpm), the time required for the sample to dissolve was examined by visual observation, and evaluated according to the following criteria.

溶解 Dissolves in less than 3 minutes

△ dissolves in less than _{3 to} 6 minutes

X · · · Does not dissolve after 6 minutes

(Water solubility in alkaline packaging)

A three-side sealed bag (10 cm x 5 cm) was prepared from the obtained polyvinyl alcohol-based film, and 20 g of a 1% aqueous sodium carbonate solution (pH = ll) was added to the bag as an alkaline substance. After heat sealing, leave it at 40 ° C and 70% RH for 2 weeks, then take a 3 cm x 3 cm piece of film from the bag containing the alkaline substance and put it in 1000 cc of water (20 (° C) in a 1000 ml beaker and stirred with a magnetic stirrer (approximately 500 rpm) in an atmosphere of 20 ° C and 65% RH until the film pieces completely dissolve. (S) was examined. In addition, the bag before the alkaline substance was put (before standing) was separately tested for solubility in the same manner.

Example 2

In Example 1, as PVA (A), 5 A polyvinyl alcohol-based film was obtained in the same manner as described above, except that a polyvinyl alcohol-based film was used which had a denaturation ratio of 96% by mole and a viscosity of 4 mol% aqueous solution at 20 ° C. of 23 mPa's. The average saponification degree of the film was 95 mol%.

Example 3

In the same manner as in Example 1, except that PVA (A) was modified by 2 mol% with itaconic acid, the saponification degree was 94 mol%, and the viscosity of a 4% by weight aqueous solution at 20 ° C was 28 mPa-s. A polyvinyl alcohol-based film was obtained and similarly evaluated. The average saponification degree of the film was 93 mol%.

Example 4

A polyvinyl alcohol-based film was prepared in the same manner as in Example 1, except that unmodified PVA having a saponification degree of 80 mol% and a 4% by weight aqueous solution viscosity at 20 ° C. of 5 mPa · s was used as PVA (B). Was obtained and evaluated similarly. The average saponification degree of the film was 94 mol%.

Example 5

A polyvinyl alcohol-based film was prepared in the same manner as in Example 1, except that unmodified PVA having a saponification degree of 90 mol% and a 4% by weight aqueous solution viscosity at 20 ° C. of 7 mPa · s was used as PVA (B). Obtained and evaluated similarly. The average saponification degree of the film was 95 mol%.

Example 6

A polyvinyl alcohol-based film was obtained in the same manner as in Example 1 except that the content ratio (A / B) of PVA (A) and PVA (B) was changed to 83Z17, and the same evaluation was performed. The average saponification degree of the film was 95 mol%.

Example 7 A polyvinyl alcohol-based film was obtained in the same manner as in Example 1 except that the content ratio (A / B) of PVA (A) and PVA (B) was changed to 988, and the same evaluation was performed. The average saponification degree of the film was 95 mol%.

Example 8

In Example 1, PVA (A) was used, which was modified with 2% by mole of maleic acid and had a saponification degree of 88% by mole and a 4% by weight aqueous solution viscosity at 20 ° C of 28 mPa-s. The unmodified PVA having a saponification degree of 73 mol%, a 4% by weight aqueous solution at 20 ° C and a viscosity of 5 mPa's was used, and the content ratio (AZB) of PVA (A) and PVA (B) was 80 Except that the ratio was set to / 20, a poly (vinyl alcohol) -based film was obtained in the same manner, and evaluation was performed in the same manner. The average saponification degree of the film was 85 mol%.

Comparative Example 1

A polyvinyl alcohol-based film was obtained in the same manner as in Example 1 except that an unmodified PVA having a viscosity of 0.5 mPa's in a 4% by weight aqueous solution at 20 ° C. was used as the PVA (B), and evaluation was similarly performed. Was.

Comparative Example 2

A polyvinyl alcohol-based film was obtained in the same manner as in Example 1, except that unmodified PVA having a viscosity of 15 mPa's of a 4% by weight aqueous solution at 20 ° C was used as PVA (B), and evaluation was similarly performed. .

Table 1 shows the evaluation results of the examples and the comparative examples. table 1

Industrial applicability

The polyvinyl alcohol-based film of the present invention is excellent in both heat-sealing properties and water-solubility of the heat-sealed part, and is useful for various packaging applications. In particular, powdered stones, synthetic detergents, pesticides, bactericides, and disinfectants It is most suitable for unit packaging, which packs chemicals such as odorants and insecticides and puts them in water.

Claims

The scope of the claims

1. (A) Polyvinyl alcohol-based resin containing 1 to 10 mol% of lipoxyl groups and (B) Viscosity of 4% by weight aqueous solution at 20 ° C is 1 to 10 mPa's and does not contain lipoxyl groups Polyvinyl alcohol-based film made of polyvinyl alcohol-based resin.

2. The polyvinyl alcohol according to claim 1, wherein the average degree of saponification of the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B) contained in the polyvinyl alcohol-based film is 80 to 97 mol%. —Le-based films.

3. The method according to claim 1, wherein the content ratio (A / B) of the polyvinyl alcohol resin (A) and the polyvinyl alcohol resin (B) is 80/20 to 95/5 (weight ratio). The polyvinyl alcohol-based film according to the above item.