JPH04304215A - Film - Google Patents

Abstract

PURPOSE:To prepare a flexible film without using any plasticizer by forming a vinyl alcohol polymer or vinyl ester polymer having a (poly)alkylene oxide side chain into a film. CONSTITUTION:A film is prepd. from a vinyl alcohol polymer having 0.1-30mol% structural units of formula I or II [wherein R<1> is H or CH3; R<2> is H or 1-4C alkyl; R<3> is an optionally branched 1-20C alkylene group; R<4> is H or 1-20C alkyl ; and (0) is a group of formula III or IV (wherein n is 1-500) which is bonded to R<3> at the side of 0], a degree of saponification of 50mol% or higher, and a degree of polymn. of 100 or higher or from a vinyl ester polymer having 0. 1-30mol% structural units of formula I or II, a degree of saponification lower than 50mol%, and a degree of polymn. of 100 or higher. The film is excellent in flexibility and resistant to cracking even under an absolute dry condition possibly because of the flexibility of the polyalkylene oxide units and hence is useful in the fields of packaging release material, and agriculture.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film useful for applications requiring flexibility, such as packaging films, release films, agricultural films, and films for industrial materials.

0002

[Prior Art] Polyvinyl alcohol films have outstanding mechanical strength, transparency, and printability, and are widely used for packaging, mold release, agriculture, industrial materials, water-soluble films, etc. It is used as a packaging film. In these fields, flexibility is often required for the film, but polyvinyl alcohol itself only yields a hard film in its dry state, and plasticizers (often glycerin is used) are added to improve flexibility. It was customary to do so. However, polyvinyl alcohol films that contain plasticizers have sufficient flexibility when they are first produced, but as they are used, the plasticizers evaporate, bleed, migrate, etc., and the film gradually becomes hard and brittle. It included the problem.

In order to improve this point, various proposals have been made to develop a polyvinyl alcohol film that does not require a plasticizer and is itself flexible. Among them, polyvinyl alcohol having a flexible (poly)alkylene oxide chain in its side chain is expected to have excellent flexibility, and many attempts have been made to synthesize it. For example, a method of reacting the hydroxyl group of polyvinyl alcohol with an epoxy compound, a method of reacting the hydroxyl group of polyvinyl alcohol with alkylene oxide, a method of copolymerizing vinyl acetate with polyoxyethylene acrylate, etc., and then saponifying it (JP-A-Show) 59-1
No. 55408), etc. However, due to the extreme reaction conditions of conventional methods, the reaction does not proceed uniformly in most cases, and as a result, the structure and composition of the resulting polymer may be non-uniform, or the side chains may There are problems such as cleavage of alkylene oxide and decomposition of polyvinyl alcohol, and the industrially useful side chains (
Polyvinyl alcohol containing poly()alkylene oxide has not been found, and therefore, at present, no industrially useful polyvinyl alcohol film that is flexible on its own has been obtained.

[0004] Furthermore, polyvinyl ester films are
The reality is that it is not used as a stand-alone film due to its brittleness. In order to improve this flexibility, a method of copolymerizing vinyl acetate and polyoxyethylene acrylate, etc. for polyvinyl ester polymers having (poly)alkylene oxide in the side chain (Japanese Patent Laid-Open No. 59-1
No. 55408) has been proposed, but there are problems such as the structure and composition of the obtained polymer being non-uniform due to the extreme reaction conditions, and industrially useful flexible polyvinyl ester films have not been produced. Not obtained.

[0005]

[Problems to be Solved by the Invention] The present invention provides a film made of a polyvinyl alcohol polymer having (poly)alkylene oxide in the side chain, which does not have the above-mentioned problems, and a polyvinyl alcohol polymer having (poly)alkylene oxide in the side chain. A film made of an ester polymer is provided.

[0006]

[Means for Solving the Problems] As a result of intensive studies to solve the above-mentioned problems, the present invention has been made as follows.
] A film made of a polyvinyl alcohol polymer containing the structural unit represented by [Chemical formula 1] or [Chemical formula 2] below By using
This solves the above problem.

[0007]

[Chemical formula 1]

(However, R1: Hydrogen or a methyl group R2: Hydrogen or an alkyl group having 1 to 4 carbon atoms R3: An alkylene group having 1 to 20 carbon atoms which may have a branch R4: Hydrogen or an alkyl group having 1 to 4 carbon atoms 20 alkyl groups (X):
(OCH2CH2)n or (OC
H(CH3)CH2)n (where n=1 to 500) is shown respectively. )

[0009]

[Case 2]

(However, R1: Hydrogen or a methyl group R2: Hydrogen or an alkyl group having 1 to 4 carbon atoms R3: An alkylene group having 1 to 20 carbon atoms which may have a branch R4: Hydrogen or an alkyl group having 1 to 4 carbon atoms 20 alkyl groups R5:
Alkylene group (X) having 1 to 3 carbon atoms: represents (OCH2CH2)n or (OCH(CH3)CH2)n (where n=1 to 500) connected to R3 on the O side, respectively. )

The polyvinyl alcohol film of the present invention contains 0.1 to 30 mol% of a structural unit having a (poly)alkylene oxide represented by [Chemical Formula 1] or [Chemical Formula 2] above, and contains a vinyl ester. It consists of a polyvinyl alcohol polymer having a saponification degree of 50 mol% or more and a polymerization degree of 100 or more.

[Chemical formula 1] or [Chemical formula 2] (poly)
The structural unit having alkylene oxide will be explained below. (X) is (poly)ethylene oxide or (poly)propylene oxide connected to R3 on the O side, and copolymers of both are also used. Among these, (poly)alkylene oxide derived from ethylene oxide is preferred. The degree of polymerization n of the (poly)alkylene oxide is from 1 to 500 from the viewpoint of transparency and flexibility of the film, preferably from 5 to 500, more preferably from 5 to 300,
5-100 is most preferred. If the degree of polymerization n of the (poly)alkylene oxide is extremely small, the film using the polyvinyl alcohol polymer having the (poly)alkylene oxide in the side chain tends to become hard, which is not preferable. Furthermore, if the degree of polymerization n of the (poly)alkylene oxide exceeds 500, the film often becomes opaque, which is not preferable. R1 is hydrogen or a methyl group. R2 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and among these, hydrogen or a methyl group is preferable. R3 is an alkylene group having 1 to 20 carbon atoms which may have a branch, preferably an alkylene group having 1 to 5 carbon atoms, and most preferably an alkylene group having 1 to 3 carbon atoms. R4 is hydrogen or an alkyl group having 1 to 20 carbon atoms, preferably hydrogen or an alkyl group having 1 to 20 carbon atoms, more preferably hydrogen or an alkyl group having 1 to 5 carbon atoms, and most preferably hydrogen or a methyl group. preferable. R5 is an alkylene group having 1 to 3 carbon atoms, and among these, a methylene group having 1 carbon number is preferable.

[0013] In the polyvinyl alcohol polymer of the present invention, the (poly) compound represented by [Chemical formula 1] or [Chemical formula 2]
The content of the structural unit having alkylene oxide is 0.1 to 30 mol%, preferably 0.2 to 30 mol%.
Mol% is preferred, 0.5 to 30 mol% is more preferred, and 1 to 15 mol% is most preferred. If the content of the structural unit having (poly)alkylene oxide is less than 0.1 mol%, the film using the polyvinyl alcohol polymer having (poly)alkylene oxide in the side chain becomes hard, which is not preferable. In addition, if the content of the above structural unit exceeds 30 mol%, the film using the polyvinyl alcohol polymer will lose its original characteristics such as film toughness, and the characteristics of the present invention will not be sufficient. It no longer appears.

Furthermore, it has been found that a film with the best flexibility and transparency can be obtained when the following relational expression is satisfied regarding the content of structural units having (poly)alkylene oxide. The degree of polymerization n of the (poly)alkylene oxide is 5≦n≦100, and the content K (mol%) of structural units having the (poly)alkylene oxide is 1≦K
≦15, and 5≦n×K≦100.

The degree of saponification of the vinyl ester moiety of the polyvinyl alcohol polymer of the present invention is 50 mol% or more, preferably 70 mol% or more, and more preferably 98 mol% or more. A higher degree of saponification is preferred from the viewpoint of film strength and water solubility of the polyvinyl alcohol polymer. In the polyvinyl alcohol polymer of the present invention, unsaponified vinyl ester units include vinyl formate,
Vinyl acetate, vinyl propionate, vinyl pivalate,
Examples include vinyl ester units such as vinyl versatate, among which vinyl acetate units are industrially preferred.

The degree of polymerization of the polyvinyl alcohol polymer of the present invention is 100 or more, preferably from 100 to 30,000, more preferably from 100 to 4,000, and from 300 to 30.
00 is most preferred. If the degree of polymerization is less than 100, the strength of the film will decrease, which is not preferable. Also,
If the degree of polymerization exceeds 30,000, the viscosity during film production will become too high, resulting in poor handling properties, which is not preferred. Here, the degree of polymerization is determined by measuring the intrinsic viscosity ([η], dl/g unit) of a completely saponified polyvinyl alcohol-based polymer in water at 30°C, and using the formula expressed by the following [Equation 1]. It was calculated based on the following.

[0017]

[Math 1]

Next, a film made of the polyvinyl ester polymer of the present invention will be explained. The polyvinyl ester polymer used in the film of the present invention is
] or [Chemical formula 2] Contains 0.1 to 30 mol% of a structural unit having a (poly)alkylene oxide, the degree of saponification of the vinyl ester is less than 50 mol%, and the degree of polymerization is 100.
These are the above polyvinyl ester polymers. The structural unit represented by [Chemical Formula 1] or [Chemical Formula 2], its content, and degree of polymerization are the same as those described in the column of the polyvinyl alcohol-based polymer above. The degree of saponification of the vinyl ester portion of the polyvinyl ester polymer of the present invention is less than 50 mol%, and is appropriately selected depending on the use of the film. For example, when hydrophilicity of the film is required, the saponification degree is 10 mol% or more and less than 50 mol%, preferably 20 mol%.
If less than 50 mol% is used, and the film is required to be hydrophobic, a saponification degree of 0 to 20 mol%, preferably 0 to 10 mol% is used. As the vinyl ester unit in the polyvinyl ester polymer used in the present invention, the vinyl ester units described in the section of the polyvinyl alcohol polymer described above are used.

Next, (poly) is added to the side chain used in the present invention.
A method for producing a polyvinyl alcohol polymer having alkylene oxide will be explained. (Poly) of the present invention
There are no particular restrictions on the method for producing polyvinyl alcohol polymers containing alkylene oxide, but (poly)
Examples include a method of reacting the epoxy ring of an epoxy compound having alkylene oxide in the molecule with the amino group of amino group-modified polyvinyl alcohol. Among epoxy compounds having (poly)alkylene oxide in the molecule, epoxy compounds having an epoxy ring at one end are preferred. Examples of such epoxy compounds include epoxy compounds represented by the following [Chemical formula 3].

[0020]

[Chemical formula 3]

(However, R3: An alkylene group having 1 to 20 carbon atoms which may have a branch. R4: Hydrogen or an alkyl group having 1 to 20 carbon atoms (X):
(OCH2CH2)n or (OC
H(CH3)CH2)n (where n=1 to 500) is shown respectively. )

Among the epoxy compounds represented by [Chemical formula 3] above, hydroxypolyoxyethylene glycidyl ether, methoxypolyoxyethylene glycidyl ether, ethoxypolyoxyethylene glycidyl ether,
Butoxypolyoxyethylene glycidyl ether, dodecyloxyethylene glycidyl ether, hydroxypolyoxypropylene glycidyl ether, methoxypolyoxypropylene glycidyl ether, ethoxypolyoxypropylene glycidyl ether, butoxypolyoxypropylene glycidyl ether, dodecyloxypropylene glycidyl ether, 2-epoxy -1-hydroxypolyoxyethyleneethane, 2-epoxy-1-methoxypolyoxyethyleneethane, 2-epoxy-1-
Hydroxypolyoxypropyleneethane, 2-epoxy-1-methoxypolyoxypropyleneethane, 3-epoxy-1-hydroxypolyoxyethylenepropane, 3
- Epoxy-1-methoxypolyoxyethylenepropane, 3-epoxy-1-hydroxypolyoxypropyleneethane, 3-epoxy-1-methoxypolyoxypropyleneethane, etc. introduce (poly)oxyalkylene into polyvinyl alcohol polymers. preferred from the viewpoint of reactivity.

[0023] Examples of the amino group-modified polyvinyl alcohol include polyvinyl alcohols having a primary amino group or a secondary amino group represented by [Chemical Formula 4] or [Chemical Formula 5] below.

[0024]

[C4]

(However, R1: Hydrogen or methyl group R2: Hydrogen or an alkyl group having 1 to 4 carbon atoms, respectively.)

[0026]

[C5]

(However, R1: Hydrogen or a methyl group R2: Hydrogen or an alkyl group having 1 to 4 carbon atoms R5: An alkylene group having 1 to 3 carbon atoms, respectively.)

The amino group content used is preferably 0.1 to 30 mol%. The degree of saponification of the amino group-modified polyvinyl alcohol is 50 mol% or more, and 7
0 mol% is preferred, and 98 mol% or more is most preferred. The degree of polymerization of the amino group-modified polyvinyl alcohol is appropriately selected depending on the intended use of the film made of the polyvinyl alcohol polymer having (poly)alkylene oxide in the side chain. The method for producing amino group-modified polyvinyl alcohol is described in Industrial Chemistry Magazine, volume 59, page 658 (1
956), vol. 60, p. 353, p. 1188 (1957
), JP-A-56-113292, JP-A-62-749
Olefins having a substituent capable of producing a primary amino group or a secondary amino group by the method described in No. 02, an olefinically unsaturated monomer having a primary amino group or a secondary amino group, or hydrolysis, etc. Examples include a method in which a sexually unsaturated monomer and vinyl acetate are copolymerized and then saponified. Specifically, examples include a method in which vinyl acetamide, methyl vinyl acetamide and vinyl acetate are copolymerized and then saponified, and allylamine and vinyl acetate are copolymerized and then saponified. It may have a functional group other than the amino group used in the present invention. Examples of such functional groups include long-chain alkyl groups, silane groups, sulfonic acid groups, carboxyl groups, and quaternary ammonium salts. The reaction may also be carried out under solid-liquid homogenization in which PVA does not dissolve even under a homogeneous solution. Further, if necessary, a catalyst such as an acid such as formic acid, acetic acid, or hydrochloric acid, or an alkali such as trimethylamine, triethylamine, pyridine, imidazole, or 2-methylimidazole may be added without any problem.

The reaction between the epoxy ring of the epoxy compound having (poly)alkylene oxide in the molecule and the amino group of amino group-modified polyvinyl alcohol is carried out in a solvent such as water, dimethyl sulfoxide, or N-methyl-2-pyrrolidone. . Among the above solvents, water or dimethyl sulfoxide is preferred. The molar ratio of the amino group in the amino group-modified polyvinyl alcohol to the epoxy compound is 0.1 to
100 is preferable, and 1-50 are more preferable. The concentration of the amino group-modified polyvinyl alcohol in the solvent is adjusted to about 0.01 to 50% by weight, preferably 1 to 30% by weight when the reaction is carried out by homogenizing the solution. Reaction temperature is 0-3
00°C is preferable, and 30 to 200°C is more preferable. The reaction time is preferably 0.01 to 200 hours, and 0.5 to 1
00 hours is more preferred. The obtained polyvinyl alcohol polymer is purified by a conventionally known method.

Next, a method for producing a polyvinyl ester polymer having (poly)alkylene oxide in its side chain will be explained. There are no particular limitations on the method for producing the polyvinyl ester having (poly)alkylene oxide of the present invention, but the polyvinyl ester having (poly)alkylene oxide in the side chain and having a saponification degree of 50 mol% or more obtained by the above method Obtained by re-esterifying an alcohol-based polymer. Re-esterification (poly) in the side chain
This is carried out by reacting a polyvinyl alcohol-based polymer containing alkylene oxide and having a degree of saponification of 50 mol% or more with an organic acid such as acetic anhydride or acetyl chloride. At this time, a reaction aid such as pyridine or triethylamine may be added, or the polyvinyl alcohol polymer may be dissolved in a solvent such as dimethyl sulfoxide or acetic acid, and the reaction may be carried out in a homogeneous solution. There is no particular restriction on the charging ratio of the polyvinyl alcohol polymer to the organic acid, but the ratio of the organic acid to 1 g of the polyvinyl alcohol polymer is 0.1.
The amount is appropriately selected from the range of 1 to 30 g, preferably 1 to 30 g, depending on the degree of saponification of the desired polyvinyl ester polymer. The reaction temperature is preferably 0 to 300°C, and 50 to 2
00°C is more preferable. 0.01 to 200 hours is preferable, and 1.0 to 100 hours is more preferable. In addition, when performing the above-mentioned re-esterification, it is preferable to seal with an inert gas such as nitrogen. The obtained polyvinyl ester polymer is purified by a conventionally known method.

The method for producing the polyvinyl alcohol film and polyvinyl ester film of the present invention is not particularly limited, and includes conventionally known methods of casting an aqueous solution or organic solvent solution onto a belt or drum, melt extrusion molding, Inflation molding, wet film forming, etc. are used as appropriate. Further, the film after molding may be heat-treated or stretched.

In the film of the present invention, a polyvinyl alcohol polymer having a (poly)alkylene oxide chain in the side chain or the polyvinyl ester polymer alone can provide a sufficiently flexible and excellent film. Other polymeric compounds such as ordinary polyvinyl alcohol and starch, polyhydric alcohol plasticizers such as glycerin, etc.
There is no problem in adding a slip property imparting agent, a release agent, etc.

[0033]

[Function] In the film made of a polyvinyl alcohol polymer having (poly)alkylene oxide in the side chain of the present invention, since the polyvinyl alcohol polymer has (poly)alkylene oxide, it has excellent flexibility and Demonstrates the inherent hydrophilicity and toughness of polyvinyl alcohol.

Furthermore, in the film of the present invention made of a polyvinyl ester polymer having (poly)alkylene oxide in the side chain, since the polyvinyl ester polymer has polyalkylene oxide, it has excellent flexibility and Demonstrates the inherent lipophilic properties of polyvinyl ester and excellent dimensional stability at room temperature.

[0035] Compared to conventional films made of polyvinyl alcohol polymers and polyvinyl ester polymers, which are easily cracked when completely dry, the film of the present invention, which is made of polyvinyl alcohol polymers and polyvinyl ester polymers, is easily cracked when completely dry. A film with a structure having (poly)alkylene oxide in its chains has properties that are extremely resistant to cracking even when it is completely dry.

[0036]

[Examples] The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these in any way. In the following, "parts" and "%" mean "parts by weight" and "% by weight", respectively, unless otherwise specified. Synthesis Example 1 Synthesis example of a polymer having a polyalkylene oxide chain In the structural unit represented by [Chemical formula 4] above, R1=H,
Amino group-modified polyvinyl alcohol containing 3 mol% of structural units where R2=CH3, saponification degree of 99.9 mol% and polymerization degree of 2000 (units other than the structural unit having an amino group and the vinyl alcohol unit are vinyl acetate units). The same applies to Example 2 below.) 100g of water 1900g
g, heated at 90°C, and stirred to dissolve. After the amino group-modified polyvinyl alcohol was dissolved, 457.5 g of methoxypolyoxyethylene glycidyl ether (degree of polymerization of ethylene oxide, n=25) was added, and the reaction was carried out at 90°C. Six hours after the start of the reaction, stirring is stopped, the reaction solution is poured into a large amount of acetone, the polymer is reprecipitated, thoroughly washed, and dried to produce a polyvinyl alcohol-based polymer (hereinafter referred to as polyvinyl alcohol-based polymer containing a structural unit having polyethylene oxide). , abbreviated as polymer [A]) was obtained. Polymer [A
] According to the 1H-NMR spectrum, the content of structural units having polyalkylene oxide was 1.2 mol%. The degree of saponification of the polymer [A] was 99.9 mol%, and the degree of polymerization was 1950. Hereinafter, polymers [B] to [E] were synthesized using the same method. The results are summarized in Table 1.

[0037] Also, 100 parts of polymer [D] was added to 1 part of acetic anhydride.
600 parts, and after adding 40 parts of pyridine, 10
The mixture was stirred at 5°C for 24 hours. The obtained reaction product was poured into distilled water, the resulting precipitate was thoroughly washed with water, and dried under vacuum at 50°C to obtain a polyalkylene oxide-containing structural unit containing 80 mol% and a saponification degree of 0. mole%,
A polyvinyl ester polymer [F] having a polymerization degree of 1450 was obtained.

Furthermore, 100 parts of polymer [E] was added to 160 parts of acetic acid.
After adding 139 parts of acetic anhydride and 40 parts of pyridine, the mixture was stirred at 80°C for 24 hours. The obtained reaction product was poured into distilled water, the resulting precipitate was thoroughly washed with water, and 5
By drying under vacuum at 0° C., a polyvinyl ester polymer [G] containing 3.1 mol % of structural units having polypropylene oxide, a saponification degree of 44 mol %, and a polymerization degree of 940 was obtained.

[0039]

[Table 1]

Example 1 An 8% aqueous solution of polymer [A] was prepared, cast on a rotating drum at 70° C., and dried to obtain a film with a thickness of 40 μm. The flexibility of this film was evaluated by touch. A 10 x 10 cm bag was made from this film, two balls of wool (each weighing 40 g) were placed inside, and the bag was sealed with a heat sealer. After being left at room temperature for 4 months, the temperature was 8℃ and the humidity was 43%RH.
The film was dropped onto concrete from a height of 10 m in an environment of Separately, heat the film to 120°C.
After heat-treating for 10 minutes at
On the day of the test, the temperature was 4°C and the humidity was 39% RH (referred to as the dry-wet repeated test). The results are shown in Table 2.

Examples 2 to 5, Comparative Example 1 Tests were carried out in exactly the same manner as in Example 1 except that the polymer was changed. The results are shown in Table 2.

Comparative Example 2 A test was carried out in exactly the same manner as in Example 1, except that polyvinyl alcohol with a degree of polymerization of 1750 and a degree of saponification of 99.9 mol % was used, and glycerin was added in an amount of 15% based on the polyvinyl alcohol. The results are shown in Table 2.

Comparative Example 3 A test was conducted in the same manner as in Example 1 using polyvinyl alcohol containing 30% oxyethylene groups obtained by the method described in Example 1 of JP-A-1-158016. The results are also shown in Table 2.

[0044]

[Table 2]

1) ○: Flexible ×: Hard 2) Degree of polymerization: 1750, degree of saponification: 99.9 mol% 3) Degree of polymerization: 1750, degree of saponification: 99.9 mol% 15% glycerin was added to polyvinyl alcohol. 4) JP-A-1-158016 Modified polyvinyl alcohol obtained by the method described in Example 1.

Example 6 Using an 8% ethanol solution of polymer [F], 7
It was cast on a rotating drum at 0° C. and dried to obtain a film with a thickness of 55 μm. This film was folded in half to test whether the film would break. The results are shown in Table 3.

Example 7, Comparative Example 4 Tests were carried out in exactly the same manner as in Example 6, except that the polymer and solvent were changed to a 3:1 mixed solvent of ethanol and water. The results are shown in Table 3.

Comparative Example 5 A test was carried out in exactly the same manner as in Example 6 except that the polymer was changed. The results are shown in Table 3.

[0049]

[Table 3]

1) Degree of polymerization: 1750, degree of saponification: 0 mol% 2) Degree of polymerization: 1640, degree of saponification: 45 mol%

[
0051

[Effects of the Invention] The film made of the polyvinyl alcohol polymer having (poly)alkylene oxide in the side chain of the present invention has extremely excellent flexibility, probably due to the flexibility of (poly)alkylene oxide. At the same time, it also has the hydrophilicity and toughness that polyvinyl alcohol inherently has. It also doesn't crack easily even when completely dry. Taking advantage of these characteristics, it is extremely useful for applications such as packaging films, release films, agricultural films, and films for industrial materials. Furthermore, the method for producing a polyvinyl alcohol polymer having (poly)alkylene oxide in the side chain of the present invention can be carried out under relatively mild conditions, and side reactions such as decomposition of the polyvinyl alcohol polymer do not occur. Therefore, its industrial significance is great.

Furthermore, the film made of the polyvinyl ester polymer having (poly)alkylene oxide in the side chain of the present invention has extremely excellent flexibility, probably due to the flexibility of polyalkylene oxide. It also has the inherent oiliness and dimensional stability at room temperature that polyvinyl ester has. It also doesn't crack easily even when completely dry. Taking advantage of these characteristics, it is extremely useful for applications such as packaging films, release films, agricultural films, and films for industrial materials.

Claims (2)

[Claims] Claim 1: Contains 0.1 to 30 mol% of the structural unit represented by the following [Chemical formula 1] or [Chemical formula 2], and has a saponification degree of 50
A film made of a polyvinyl alcohol polymer having a mol% or more and a polymerization degree of 100 or more. [Formula 1] (However, R1: Hydrogen or a methyl group R2: Hydrogen or an alkyl group having 1 to 4 carbon atoms R3: An alkylene group having 1 to 20 carbon atoms which may have a branch R4: Hydrogen or a carbon number 1 ~20 alkyl groups (X):
(OCH2CH2)n or (OC
H(CH3)CH2)n (where n=1 to 500) is shown respectively. ) [Formula 2] (wherein, R1: hydrogen or methyl group R2: hydrogen or alkyl group having 1 to 4 carbon atoms R3: alkylene group having 1 to 20 carbon atoms which may have a branch R4: hydrogen or carbon number 1-20 alkyl group R5:
Alkylene group (X) having 1 to 3 carbon atoms: represents (OCH2CH2)n or (OCH(CH3)CH2)n (where n=1 to 500) connected to R3 on the O side, respectively. ) [Claim 2] [Chemical formula 1] or [Chemical formula 2] according to claim 1
A film made of a polyvinyl ester polymer containing 0.1 to 30 mol% of the structural unit represented by the formula, and having a saponification degree of less than 50 mol% and a polymerization degree of 100 or more.