JPH0653773B2 - Polyvinyl alcohol film - Google Patents

Description

Detailed Description of the Invention A. TECHNICAL FIELD The present invention relates to a polyvinyl alcohol film. More specifically, it relates to a polyvinyl alcohol film having improved flexibility, good transparency, and excellent water resistance.

(However, the film in the present invention includes a sheet-like material having a thickness of 5 mm or less.) B. 2. Description of the Related Art Polyvinyl alcohol (hereinafter abbreviated as PVA) -based films obtained by polymerizing and saponifying vinyl esters, particularly vinyl acetate, have excellent printability and transparency in addition to their excellent mechanical properties. Due to its characteristics, it is widely used for packaging, mold release, agriculture, industrial materials, water-soluble film, etc., and is especially prized as a packaging film. Further, it has an excellent feature that it does not have an electrostatic property because it absorbs moisture in a normal use state, and that dust and the like are less likely to be attached due to static electricity and the appearance of the package is not deteriorated.
The PVA-based film softened with a suitable plasticizer (often used glycerin) is extremely supple, and the package collides with other things, and even if it is touched by a person, it is unpleasantly crispy or thirsty. Since no sound is generated and the texture is very good, we have succeeded in giving the package a high-class image.

Further, the PVA film has a property that it absorbs moisture in the air, and this water acts as a plasticizer for the PVA film. However, since the amount of moisture absorption changes according to the humidity in the air, the PVA film The system film alone has the property that the flexibility of the film changes depending on the humidity.
Especially under low humidity, there is a drawback that the amount of moisture absorption decreases and the material becomes hard and brittle. In addition, since the film tends to become hard even when the temperature decreases, the film becomes hard and brittle due to a synergistic effect at low humidity in winter, and when used as a packaging film, problems such as film cracking occur. Easier to do. Therefore, the PVA-based film cannot be used as a packaging film by itself.

In order to improve this point, conventionally, a method of adding a polyhydric alcohol such as glycerin as a plasticizer has been taken.
By adding an appropriate amount of a plasticizer, a PVA-based film which is sufficiently flexible even in the low humidity in winter and can be used is obtained, and has been widely put into practical use.

However, although the initial softening can be achieved by the addition of the plasticizer in this way, when it is used for a long period of time due to the problem that the content of the plasticizer decreases with time,
The plasticizer content decreased, and problems such as film cracking and cracking often occurred due to lack of flexibility in low humidity in winter. Although the cause of the decrease in the content of the plasticizer with time is not clear, bleeding of the plasticizer onto the film surface, volatilization, migration of the plasticizer due to contact between the film and the contents or other articles, etc. are considered.

In recent years, there has been a strong demand for improvement in the problem of the decrease in the plasticizer content of PVA-based films, and to develop a flexible PVA-based film without addition of a plasticizer and a PVA-based film in which the plasticizer content does not decrease with time. Was urgent.

Especially for film applications excluding the field of water-soluble film, for example, for general packaging film, excellent water resistance is required,
Therefore, as the PVA-based film, a highly saponified PVA having high crystallinity is used. However, since the highly saponified PVA has high crystallinity, compatibility with a plasticizer is insufficient, Also, the plasticizing effect of the plasticizer is weakened by the crystallinity. Therefore, a large amount of plasticizer is required to secure flexibility in low humidity in winter, and due to the poor compatibility of the plasticizer with the high saponification degree PVA, it is possible to repeatedly dry, heat and cool due to climate change. Therefore, it is considered that the bleeding of the plasticizer occurs, and the decrease in the content of the plasticizer is significantly suppressed.

Various attempts have been made in the past to solve this problem, but a satisfactory solution has not yet been found. For example, attempts to find plasticizers that are more compatible with high saponification degree PVA have not been successful,
The conventionally known polyhydric alcohol plasticizers are the best so far. In addition, in order to increase the compatibility with the plasticizer, the saponification degree is lowered, or a large amount of copolymerization modification is performed to make PV.
A method of disturbing the crystallinity of A can be considered. In this case, the compatibility with the plasticizer is certainly improved, but the crystallinity is disturbed, so that the water resistance of the PVA-based film is lost and the strength is also increased. It is impractical, such as a large decrease in.

The present inventor has ensured this water resistance and strength (that is, high crystallinity).
In order to solve the contradictory problem of good compatibility (i.e., low crystallinity) with the plasticizer, a method of mixing and using the highly crystalline PVA and the low crystalline PVA was considered, and earnestly studied.
However, as low crystalline PVA, PVA with low saponification degree
Alternatively, when various conventionally known highly modified PVA is used, the compatibility with the highly crystalline PVA (that is, the PVA having a high degree of saponification) is poor and the phase separation between the PVA-based polymers occurs to cause the film to become cloudy and transparent. In most cases, the sense was lost and the practicality was lost.

C. Problems to be Solved by the Invention Under such circumstances, the present invention provides a PVA-based film which is flexible by itself even without addition of a plasticizer, and in the case where a plasticizer is used in combination as needed, An object of the present invention is to provide a PVA-based film having substantially no deterioration with time.

D. Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has found that (a) the content of the structural unit [A] below is 0.5 to 50 mol%,
The content of [B] is 0 to 20 mol%, and the content of [C] is 50 to
19.5 parts by weight of polymer I having a content of 99.5 mol% and a content of [D] of 0 to 30 mol%, and (b) a content of the following structural unit [C] of 95 to 100 mol% and 50 to 9 of polymer II in which the content of [D] is 0 to 5 mol%
The PVA-based film, which is characterized by comprising 9 parts by weight, is a PVA-based film that is flexible by itself without adding a plasticizer, has good transparency, and has excellent water resistance, and if necessary. In the case of using a plasticizer in combination, since it is flexible by itself, it has an advantage that a smaller amount of plasticizer is required as compared with a conventional PVA film, and since the compatibility with the plasticizer is excellent, The present invention has been completed by discovering that the PVA-based film has substantially no decrease in the plasticizer content with time and is excellent in transparency and water resistance.

(However, R ¹ represents H or a hydrocarbon group having 1 to 10 carbon atoms.) (However, R ² represents H or a hydrocarbon group having 1 to 10 carbon atoms.) Used in the present invention, the above structural units [A] to
In the polymer I containing [D] and the polymer II containing structural units [C] and [D], the structural unit [B] is specifically allyl formate, allyl acetate, allyl propionate or the like. Specific examples of the structural unit [D] include vinyl formate, vinyl acetate, vinyl propionate and the like. Of these, the structural unit [B] is an allyl acetate unit, and the structural unit [D]
A vinyl acetate unit is a more preferable structural unit.

The polymer I is composed of structural units [A] to [D], and the content of [A] is 0.5 to 50 mol%, preferably 5 to 3
It is 0 mol%. If the content of [A] is too low, the effect of softening the film and the effect of preventing the content of the plasticizer from decreasing with time are insufficient. The contents of the structural units [B] and [D] of the polymer I are 20 mol% or less and 30 mol% or less, and more preferably 5 mol% as the sum of the contents of [B] and [D]. It is the following. When the contents of [B] and [D] are more than 20 mol% and 30 mol%, respectively,
This is not preferable because the solubility of the polymer I in water during film formation becomes poor and the film-forming property deteriorates.

The polymer II is a conventionally known PVA composed of the structural units [C] and [D] described above, but in the present invention, it is essential that the content of [C] is 95 mol% or more. When the content of [C] is less than 95 mol%, the water resistance of the PVA-based film obtained by using the polymers I and II is extremely poor and, for example, it is practically used as a general packaging film. It's something I can't get. In this sense, the content of [C] is more preferably 98 mol% or more.

Sum of contents of [B] and [D] of polymer I (denoted as X)
And the content of [D] of polymer II (denoted as Y) is preferably close. When X and Y are remarkably sluggish, the compatibility between the polymer I and the polymer II is deteriorated and the film tends to be turbid, resulting in poor transparency. Therefore, X
It is preferable that the difference between Y and Y does not exceed 10 mol%, more preferably 5 mol%.

The degree of polymerization of the polymer I is not particularly limited, but preferably 10
~ 2000. If the degree of polymerization is extremely low, a behavior similar to that of the plasticizer occurs, such as migration of polymer I in the obtained film, bleeding, transfer to other substances, etc., which is not preferable.

The polymerization degree of the polymer II is not particularly limited, but preferably 30
It is 0 or more. When the degree of polymerization is lower than this range, the strength of the film tends to decrease, which is not preferable.

The amounts of polymer I and polymer II used are 1 to 50 parts by weight, 50 to 99 parts by weight, preferably 5 to 40 parts by weight, and 60 to 95 parts by weight, respectively. When the amount of the polymer I used is small, the effect of softening the target film becomes insufficient, and when the plasticizer is used, the effect of preventing the decrease in the content of the plasticizer with time becomes insufficient. On the other hand, when the amount of the polymer I used is too large, the film becomes too soft, the water resistance is impaired, and the strength is remarkably reduced, which is not preferable.
Further, the polymer I alone can obtain only a film having low water resistance and low strength, and its practicality is not desired.

Polymers I and II do not undermine the compatibility of Polymers I and II,
In addition, it does not matter at all to contain a small amount of other components within a range not hindering the softening of the film which is the object of the present invention. As such a component, a method of copolymerizing a copolymerizable monomer can be considered. Examples of such a monomer include olefins such as ethylene, propylene, butylene, and α-hexene, (meth).
Unsaturated acids such as acrylic acid, crotonic acid, maleic acid (anhydrous), fumaric acid, itaconic acid, and their alkyl esters, alkali salts, (meth) acrylamides, N, N-
Dimethyl acrylamide, alkyl vinyl ether, 2-
Unsaturated sulfonic acids such as acrylamido-2-methylpropanesulfonic acid and allylsulfonic acid and alkali salts thereof, and cationic monovalent compounds such as trimethyl-2- (1- (meth) acrylamido-1,1-dimethylethyl) ammonium chloride , Vinyltrimethoxysilane, silyl group-containing monomers such as allyltriethoxysilane, isopropenyl acetate, isopropenyl alcohol, 2-methyl-
4-acetoxy-1-butene, 2-methyl-1-buten-4-ol, α-methylallyl acetate, α-methylallyl alcohol and the like can be mentioned.

The PV of the present invention comprising polymer I and polymer II as described above.
The A-type film is already sufficiently flexible by itself without using a plasticizer, but if higher flexibility is desired as in general packaging, various plastics can be used. It goes without saying that the agents can be appropriately used in combination.

As such, when higher flexibility is required, (a) the content of the structural unit [A] below is 0.5 to 50 mol%,
The content of [B] is 0 to 20 mol%, and the content of [C] is 50 to
19.5 parts by weight of polymer I having a content of 99.5 mol% and [D] of 0 to 30 mol%, (b) a content of structural unit [C] below of 95 to 100 mol% and [D] 50 to 9 of the polymer II having a content of 0 to 5 mol%.
9 parts by weight, and (c) 100 parts by weight of the sum of the weights of the polymers I and II,
A PVA-based film composed of 1 to 20 parts by weight of a plasticizer is preferable. In particular, a plasticizer is added to the weight of polymers I and II, 100
Those containing 2 to 15 parts by weight with respect to parts by weight are particularly suitable. When the amount of the plasticizer is too large, the film becomes too soft, and problems such as stickiness occur.

The plasticizer is not particularly limited and various known ones can be used, but polyhydric alcohol plasticizers are particularly preferable. Examples of polyhydric alcohol plasticizers include ethylene glycol, trimethylene glycol, tetramethylene glycol, glycerin, butanediol, diethylene glycol, triethylene glycol, trimethylolpropane, and the like. Of these, glycerin is most preferable because of its plasticizing effect, compatibility with the polymer, high boiling point, and the like.

The method for producing the polymer I is not particularly limited, but a method in which vinyl acetate and allyl acetate, or vinyl acetate and allyl alcohol are radically copolymerized and the resulting copolymer is saponified with an alkali catalyst is simple and preferable. . For the copolymerization, conventionally known methods such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization can be applied. As the polymerization catalyst, an azo-based catalyst, a peroxide-based catalyst, a redox-based catalyst, or the like is appropriately selected according to the polymerization method.

For the saponification reaction of the copolymer, conventionally known alkali catalyst or acid catalyst can be used for alcoholysis, hydrolysis and the like. Of these, the saponification reaction with a NaOH catalyst using methanol as a solvent is simple and most preferable.

The method for producing the polymer II is not particularly limited, but a method which is conventionally known as a method for producing PVA, in which vinyl acetate is radically polymerized and then saponified, is simple and preferable. The same method as the method for producing the polymer I is preferably used, except that vinyl acetate is polymerized alone.

As a method for producing the PVA-based film of the present invention, a method conventionally used as a method for producing a PVA-based film is preferably used. That is, using water as a solvent,
A casting method of casting on a drum or a belt and drying, a melt extrusion method of melt extruding a pellet impregnated with water, and the like can be applied. The film after film formation may or may not be heat-treated depending on the purpose. Further, stretching may be performed at all.

Due to its excellent flexibility, transparency and water resistance, the PVA film of the present invention is also used in the fields of mold release films of various plastics, food packaging films, agricultural films, industrial material films, etc. However, it is particularly preferably used for a general packaging film.

E. Actions and effects of the invention The PVA-based film of the present invention has excellent flexibility by itself, is excellent in transparency and water resistance, and when a plasticizer is used in combination, prevents the plasticizer content from decreasing with time. The reason for its excellent effect is not clear, but it is estimated as follows.

The polymer I used in the PVA-based film of the present invention is a flexible polymer which tends to be crystallized by the presence of the structural units [A] and [B] and [D]. Compared to the second ordinary PVA, it is a polymer that is more hygroscopic and has a higher moisture content even at low humidity, and since it has a large plasticizing effect due to moisture, it is advantageous for softening the film at low humidity. Thirdly, it has good compatibility with plasticizers, especially polyhydric alcohol plasticizers such as glycerin,
The presence of the polymer I can decrease the bleeding rate of the plasticizer, and fourthly, the presence of the structural unit [A] surprisingly improves the compatibility with the ordinary PVA (polymer II). There are things that are not damaged. Of these, the first and second
This point indicates the effect of softening the film, that is, the plasticizer addition amount can be reduced or the plasticizer can be eliminated as compared with the conventional plasticizer-added PVA film. The third point shows that even when a plasticizer is used, it is possible to prevent the plasticizer content from decreasing with time. The fourth point indicates that blending with ordinary PVA can be used, and this is extremely important in obtaining a PVA-based film having excellent transparency.

The film obtained by the polymer I alone is rich in flexibility, but lacks in practicality because it is impaired in water resistance and greatly deteriorates in strength. Therefore, the film of the present invention is flexible and tough. In order to obtain a PVA-based film having excellent transparency, good transparency, and excellent water resistance, as described in detail above, the specific polymer I and the specific polymer I described above are used. It is essential and essential to use the polymer II having a high degree of saponification and the plasticizer, if necessary, in the ratio of the above-mentioned specific amount.

By the way, Japanese Patent Publication No. 306485/1989 describes a synthetic fiber, a film or other molded article which is composed of PVA having a small amount of allyl alcohol unit alone or a mixture thereof with PVA. A film which is similar to the film at first glance is disclosed, however, the film described in Japanese Patent Publication No. 306485/1990 is easily dissolved in water at room temperature. It is a water-soluble film, in other words, a film that does not have water resistance.
The invention described in Japanese Patent Publication is different from the present invention in its purpose, and is completely different in the water resistance of the obtained PVA-based film, that is, in practicality when it is applied to a general packaging film or the like. Therefore, the invention described in this publication cannot attain the object of the present invention at all.

F. Examples The PVA film of the present invention will be described below with reference to examples, but the present invention is not limited to these. In addition, "parts" and "%" mean "parts by weight" and "% by weight" unless otherwise specified.

Example of Preparation Method of Polymer I A polymerization vessel was charged with 2400 parts of vinyl acetate, 310 parts of allyl acetate, and 301 parts of methanol, heated to 60 ° C. and replaced with nitrogen.
6.76 parts of 2,2'-azobisisobutyronitrile was added, and the mixture was polymerized at 60 ° C for 6 hours. The polymerization rate was 52.5%.

After the unreacted vinyl acetate monomer was driven out by introducing methanol vapor, a 50% methanol solution of the copolymer was obtained. While stirring this solution at 40 ° C., a saponification reaction was carried out by adding a methanol solution in which 1.4% of sodium hydroxide was dissolved in the solution to the copolymer. The obtained white gel was pulverized, thoroughly washed with methanol, and then dried to obtain a polymer I (polymer No. A) composed of the following structural units [A] to [D].

Polymer No. A was analyzed by ¹ H-NMR in DMSO-d ₆ ,
The contents of the structural units [A] to [D] were determined to be 9.9 mol%, 0.1 mol%, 88.2 mol% and 0.8 mol%, respectively. Polymer No. A was reacetated with a mixed system of acetic anhydride and pyridine, and the degree of polymerization was 710 (Nakajima formula: from the reduced viscosity ([η]) measured at 30 ° C. in acetone). (Calculated using).

Polymers No. B to No. F were synthesized by a method similar to that of the polymer No. A. The degree of polymerization was adjusted by changing the amount of methanol used in the polymerization system. Table 1 shows the types of comonomers and the analysis results of the obtained polymer I.

Preparation Method of Polymer II Polymer II was synthesized in the same manner as the preparation method of Polymer I except that allyl acetate was not used. Obtained polymer No. G
Table 2 shows the analysis results of ~ L.

Example 1 30 parts of Polymer No. A and 70 parts of Polymer No. G were dissolved in 900 parts of water, and then 15 parts of glycerin was added. 70 this solution
The film is formed by casting on a rotating drum at ℃,
A film having a dry thickness of 75 μ was obtained. Table 3 shows the results of the visual determination of the transparency of this film. This film was heat-treated at 120 ° C. for 10 minutes, left in an atmosphere of 20 ° C. and 65% RH for 7 days, and then cut into a 5 cm square size, and transferred to a desiccator kept at 20 ° C. and 95% RH. . After standing in a desiccator for 1 day, the film surface was visually observed to observe the bleeding state of the plasticizer. The results are shown in Table 3.
Are also shown.

Examples 2 to 8 and Comparative Examples 1 to 5 Table 3 also shows the results of testing films of various compositions in the same manner as in Example 1.

It is clear from Table 3 that the film of the present invention has excellent transparency as well as the conventional PVA type film, has good compatibility with the plasticizer, and has a great effect of preventing bleeding of the plasticizer.

Example 9 A film which had been formed into a film and heat-treated in the same manner as in Example 1 was allowed to stand in an atmosphere of 20 ° C. and 40% RH for 7 days, and then subjected to a tensile test by an autograph. The results are shown in Table 4. Table 4 also shows the results of the same tests as the eyelids except that the amount of glycerin added was changed.

Autograph measurement conditions Examples 10 to 14 and Comparative Examples 6 to 8 Tensile tests were conducted on each of the films having different polymer compositions in the same manner as in Example 9 while changing the amount of glycerin added. The results are shown in Table 4.

From Table 4, the film of the present invention is more flexible (that is, has a lower Young's modulus and a higher elongation) when compared with the same amount of glycerin under low humidity, and conversely, the same degree of flexibility is obtained. It is clear that a small amount of glycerin is sufficient. This shows that the film of the present invention shown in the results of Examples 1 to 6 has an effect of suppressing bleeding of glycerin, and is more effective for preventing bleeding because the amount of glycerin added can be reduced. It shows that it becomes.

Even when the film of the present invention does not contain glycerin, or even when the film added with glycerin completely loses glycerin for some reason, the films of Comparative Examples 6 to 8 lose glycerin. It is clear from Table 4 that the film is soft and superior to the films of Comparative Examples 6 to 8.

Example 15 A film was heat treated in the same manner as in Example 1 except that the amount of glycerin was changed, and the heat-treated film was cut into 10 cm square pieces, and then a commercially available cotton cloth (12 cm square pieces, thickness 1 mm) It is sandwiched between two sheets. Further, sandwich the top and bottom of the cloth with a glass plate, make sure the cloth and the film are in close contact, and
1 day in an atmosphere of 95% RH, then 5 ° C, 30% RH
Placed on a flat surface with a 1 day cycle under. After a total of 10 days, the film was taken out and folded in half at 5 ° C. and 30% RH, and it was observed whether or not the film was broken. The results are shown in Table 5.

Examples 16 and 17, Comparative Example 9 The results of a similar test performed in parallel with Example 15 are shown in Table 5.
Are shown together with. From Table 5, it is clear that the film of the present invention is superior to the comparative example in the effect of retaining flexibility.

Example 18 A film subjected to film formation and heat treatment in the same manner as in Example 1 except that glycerin was not used was immersed in water at 20 ° C., and the temperature of water was increased at a rate of 1 ° C. per minute, The temperature of water at which the film was completely dissolved was visually determined. The results are shown in Table 6.

Example 19, Comparative Examples 10 and 11 A test was conducted in the same manner as in Example 18 except that the saponification degree of the polymer II used in Example 18 was changed. The results are also shown in Table 6. From Table 6, it is clear that the film of the present invention has excellent water resistance.

Claims (18)

[Claims] (A) The content of the structural unit [A] below is from 0.5 to
50 mol%, the content of [B] is 0 to 20 mol%, the content of [C] is 50 to 99.5 mol%, and the content of [D] is 0 to 30.
1 to 50 parts by weight of the polymer I which is mol%, and (b) a polymer in which the content of the following structural unit [C] is 95 to 100 mol% and the content of [D] is 0 to 5 mol%. II 50 to 9
9 parts by weight of polyvinyl alcohol film. (However, R ¹ represents H or a hydrocarbon group having 1 to 10 carbon atoms.) (However, R ² represents H or a hydrocarbon group having 1 to 10 carbon atoms.) 2. The content of the structural unit [C] of the polymer II is 98-10.
The polyvinyl alcohol film according to claim 1, which is 0 mol%. 3. The polyvinyl alcohol film according to claim 1, wherein the sum of the contents of the structural units [A] and [C] of the polymer I is 95 mol% or more. 4. When the sum of the contents of the structural units [B] and [D] of the polymer I is X mol% and the content of the structural unit [D] of the polymer II is Y mol%, | XY The polyvinyl alcohol film according to claim 1, wherein | ≦ 10. 5. The content of the structural unit [A] of the polymer I is 5 to 3
The polyvinyl alcohol film according to claim 1, which is 0 mol%. 6. The polyvinyl alcohol film according to claim 1, wherein the polymer I has a degree of polymerization of 10 to 2000, and the polymer II has a degree of polymerization of 300 or more. 7. A structural unit [B] wherein R ¹ is a methyl group,
The polyvinyl alcohol film according to claim 1, wherein R ² of the structural unit [D] is a methyl group. 8. A polyvinyl alcohol film according to claim 1, which comprises 5 to 40 parts by weight of the polymer I and 60 to 95 parts by weight of the polymer II. 9. (a) The content of the following structural unit [A] is 0.5 to
50 mol%, the content of [B] is 0 to 20 mol%, the content of [C] is 50 to 99.5 mol%, and the content of [D] is 0 to 30.
1 to 50 parts by weight of the polymer I which is mol%, and (b) a polymer in which the content of the following structural unit [C] is 95 to 100 mol% and the content of [D] is 0 to 5 mol%. II 50 to 9
9 parts by weight, and (c) 100 parts by weight of the sum of the weights of the polymers I and II,
A polyvinyl alcohol-based film comprising 1 to 20 parts by weight of a plasticizer. (However, R ¹ represents H or a hydrocarbon group having 1 to 10 carbon atoms.) (However, R ² represents H or a hydrocarbon group having 1 to 10 carbon atoms.) 10. The content of structural unit [C] of polymer II is 98.
The polyvinyl alcohol-based film according to claim 9, wherein the polyvinyl alcohol-based film has a content of 100 mol%. 11. The polyvinyl alcohol film according to claim 9, wherein the sum of the contents of the structural units [A] and [C] of the polymer I is 95 mol% or more. 12. When the sum of the content of the structural units [B] and [D] of the polymer I is X mol% and the content of the structural unit [D] of the polymer II is Y mol%, | X−Y | The polyvinyl alcohol film according to claim 9, wherein ≦ 10. 13. The content of the structural unit [A] of the polymer I is 5 to 5.
The polyvinyl alcohol film according to claim 9, which is 30 mol%. 14. A polyvinyl alcohol film according to claim 9, wherein the polymer I has a degree of polymerization of 10 to 2000, and the polymer II has a degree of polymerization of 300 or more. 15. The polyvinyl alcohol film according to claim 9, wherein R ¹ of the structural unit [B] is a methyl group, and R ² of the structural unit [D] is a methyl group. 16. A plasticizer in an amount of 1 to 20 parts by weight based on 5 to 40 parts by weight of polymer I, 60 to 95 parts by weight of polymer II, and 100 parts by weight of the total weight of polymers I and II. The polyvinyl alcohol film according to claim 9. 17. The polyvinyl alcohol film according to claim 9, wherein the plasticizer is a polyhydric alcohol plasticizer. 18. The polyhydric alcohol plasticizer is glycerin, and the glycerin is contained in an amount of 2 to 15 parts by weight based on 100 parts by weight of the total weight of the polymers I and II.
The polyvinyl alcohol film according to the item.