JP7085151B2 - Water-soluble film and drug packaging - Google Patents

Description

The present invention relates to a water-soluble film (hereinafter, may be referred to as PVA-based film) containing a polyvinyl alcohol-based resin (hereinafter, polyvinyl alcohol may be abbreviated as PVA) as a main component. More specifically, the present invention relates to a water-soluble film having excellent blocking resistance and reduced bleed-out of a plasticizer, particularly a water-soluble film for producing a drug package and a drug package using the same.

The PVA-based film is a film made of a PVA-based resin that is a thermoplastic resin but has water solubility, and the hydrophobic film that is usually often used for packaging films such as polyethylene terephthalate films and polyolefin films is a film. The various physical properties and the feel to the touch are greatly different.

Conventionally, it has been proposed to take advantage of the water solubility of PVA-based resin to package various chemicals such as pesticides and detergents in a bag made of a film of PVA-based resin (unit packaging), and use it for a wide range of applications. Has been done.

As a water-soluble unit packaging bag used for such an application, for example, 5 to 30 parts by weight of a plasticizer, 1 to 10 parts by weight of starch and 0.01 to 2 parts by weight of a surfactant are blended with 100 parts by weight of PVA. Water-soluble films are known (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2001-329130

The water-soluble film disclosed in Patent Document 1 is excellent in water solubility, and also has good blocking resistance and impact resistance. However, since such a water-soluble film mainly uses an alcohol-based plasticizer having a low melting point, there is a problem that the plasticizer bleeds out over time, and there is still room for improvement.

Therefore, in the present invention, under such a background, a water-soluble film having excellent blocking resistance and reduced bleed-out of the plasticizer, particularly a water-soluble film effective for packaging chemicals such as liquid detergents, and the water-soluble film. It is an object of the present invention to provide a drug package obtained by packaging various drugs with a film.

However, as a result of diligent research in view of such circumstances, the present inventors have obtained a combination of a polyhydric alcohol having a higher melting point and a polyhydric alcohol having a lower melting point as a plasticizer in a water-soluble film mainly composed of a PVA-based resin. It has been found that by containing a polyvalent alcohol having a low melting point in a larger amount than that of a polyhydric alcohol having a high melting point, a water-soluble film having excellent blocking resistance and reduced bleed-out of a plasticizer can be obtained. , The present invention has been completed.

That is, the gist of the present invention is a water-soluble film containing a PVA-based resin (A) and a plasticizer (B), and the content of the plasticizer (B) is the polyvinyl alcohol-based resin (A). The plasticizer (B) is a polyvalent alcohol (b1) having a melting point of 80 ° C. or higher and a polyvalent alcohol (b2) having a melting point of 50 ° C. or lower, which is 35 parts by weight or more with respect to 100 parts by weight . It relates to a water-soluble film contained and having a content ratio (b1 / b2) of the plasticizer (B) of 0.1 to 0.9 by weight.

Further, the present invention also provides a drug package made of the water-soluble film.

The water-soluble film of the present invention has excellent water solubility, does not cause blocking, and does not cause bleed-out of a plasticizer, and can be used for various packaging applications, especially for unit packaging of chemicals and the like. It is useful for.

Further, since the content of the plasticizer (B) is 35 parts by weight or more with respect to 100 parts by weight of the PVA-based resin (A), a film is formed over time when a liquid such as a liquid detergent is packaged into a package. Excellent mechanical strength without impairing tension.

When the PVA-based resin (A) contains unmodified PVA, it is more excellent in bleed-out resistance.

Further, when the polyhydric alcohol (b1) having a melting point of 80 ° C. or higher has four or more hydroxyl groups in one molecule, the compatibility with the PVA-based resin is excellent.

Further, when the polyhydric alcohol (b1) having a melting point of 80 ° C. or higher has a molecular weight of 150 or higher, the tension of the water-soluble film is more excellent.

When the number of hydroxyl groups in one molecule of the polyhydric alcohol (b2) having a melting point of 50 ° C. or less is 4 or less, the flexibility can be easily controlled near room temperature (25 ° C.). ..

Further, when the polyhydric alcohol (b2) having a melting point of 50 ° C. or lower has a molecular weight of 100 or less, the flexibility is more easily controlled.

When the water content of the water-soluble film is 3 to 15% by weight, the mechanical strength and the sealing property are improved.

Hereinafter, the present invention will be specifically described.
The water-soluble film of the present invention contains a PVA-based resin (A) and a plasticizer (B).
First, the PVA-based resin (A) used in the present invention will be described.
Examples of the PVA-based resin (A) used in the present invention include unmodified PVA and modified PVA-based resin.

The average saponification degree of the PVA-based resin (A) used in the present invention is preferably 80 mol% or more, particularly 82 to 99.9 mol%, further 85 to 98.5 mol%, particularly. It is preferably 90 to 97 mol%. When unmodified PVA is used as the PVA-based resin (A), the average saponification degree is preferably 80 mol% or more, particularly 82 to 99 mol%, and further 85 to 90 mol. % Is preferable. When a modified PVA-based resin is used as the PVA-based resin (A), the average saponification degree is preferably 80 mol% or more, particularly 85 to 99.9 mol%, and further 90. It is preferably ~ 98 mol%. Further, when an anionic group-modified PVA-based resin is used as the PVA-based resin (A), the average saponification degree is preferably 85 mol% or more, particularly 88 to 99 mol%, and further. It is preferably 90 to 97 mol%. If the average saponification degree is too small, the solubility of the water-soluble film in water tends to decrease over time depending on the pH of the drug to be packaged. If the average saponification degree is too large, the solubility in water tends to be significantly reduced due to the thermal history during film formation.

The degree of polymerization of the PVA-based resin (A) can generally be indicated by a water-soluble viscosity, and the viscosity of a 4 wt% aqueous solution at 20 ° C. is preferably 5 to 50 mPa · s, more preferably 10 to 45 mPa · s. s, particularly preferably 15 to 40 mPa · s. When unmodified PVA is used as the PVA-based resin (A), the viscosity of the 4% by weight aqueous solution of the unmodified PVA at 20 ° C. is preferably 5 to 50 mPa · s, more preferably 10 to 45 mPa · s. s, particularly preferably 15 to 40 mPa · s. When a modified PVA-based resin is used as the PVA-based resin (A), the viscosity of the modified PVA-based resin at 20 ° C. is preferably 5 to 50 mPa · s, more preferably 10 to 50 mPa · s. It is preferably 45 mPa · s, particularly preferably 15 to 40 mPa · s. If the viscosity is too small, the mechanical strength of the water-soluble film as a packaging material tends to decrease, while if it is too large, the viscosity of the aqueous solution during film formation tends to be high and the productivity tends to decrease.

The above average saponification degree is measured according to JIS K 6726 3.5, and the viscosity of the 4 wt% aqueous solution is measured according to JIS K 6726 3.11.2.

Examples of the modified PVA-based resin used in the present invention include anionic group-modified PVA-based resin, cationic group-modified PVA, and nonionic group-modified PVA-based resin. Above all, it is preferable to use an anionic group-modified PVA-based resin in terms of solubility in water. Examples of the type of anionic group include a carboxyl group, a sulfonic acid group, a phosphoric acid group and the like, but a carboxyl group, a sulfonic acid group, and particularly a carboxyl group are preferable in terms of chemical resistance and stability over time. ..

In the present invention, the modification amount of the anionic group-modified PVA-based resin is preferably 1 to 10 mol%, more preferably 2 to 9 mol%, particularly preferably 2 to 8 mol%, and particularly preferably. It is 3 to 7 mol%. If the amount of such modification is too small, the solubility in water tends to decrease, and if it is too large, the productivity of the PVA-based resin tends to decrease, the biodegradability tends to decrease, and blocking is caused. It tends to be easier and less practical.

In the present invention, the above-mentioned PVA-based resin (A) can be used alone, or the unmodified PVA and the modified PVA-based resin can be used in combination, and further, the degree of saponification, viscosity, modified species, and modified amount. It is also possible to use two or more types with different characteristics in combination. Above all, in the present invention, it is preferable that the PVA-based resin (A) contains a modified PVA-based resin in terms of water solubility. In particular, it is preferable to contain an anionic group-modified PVA-based resin, or it is preferable to contain an anionic group-modified PVA-based resin and unmodified PVA, and in particular, it contains an anionic group-modified PVA-based resin and unmodified PVA. Is preferable.

The content ratio (weight ratio) of the modified PVA resin and the unmodified PVA is preferably 95/5 to 60/40, particularly 94/6 to 70/30, and further 93/7 to 80/20. Is preferable. If the content is too small, the plasticizer tends to bleed out, and if it is too large, blocking tends to occur.

When the modified PVA-based resin and the unmodified PVA are used in combination, the unmodified PVA-based resin preferably has a viscosity of a 4% by weight aqueous solution at 20 ° C. of 5 to 50 mPa · s, more preferably 8 to 45 mPa. -S, particularly preferably 12 to 40 mPa · s, particularly preferably 15 to 35 mPa · s. If the viscosity is too small, the mechanical strength of the water-soluble film as a packaging material tends to decrease, while if it is too large, the viscosity of the aqueous solution during film formation tends to be high and the productivity tends to decrease.

Next, the water-soluble film of the present invention is produced, for example, as follows.

Unmodified PVA can be produced by saponifying a vinyl ester-based polymer obtained by polymerizing a vinyl ester-based compound.

Examples of such vinyl ester compounds include vinyl formate, vinyl acetate, trifluorovinyl acetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl laurate, vinyl versatic acid, vinyl palmitate, vinyl stearate and the like. Among them, vinyl acetate is preferably used as the vinyl ester compound. The vinyl ester compound may be used alone or in combination of two or more.

The modified PVA-based resin may be a method of copolymerizing the above vinyl ester-based compound with an unsaturated monomer copolymerizable with the vinyl ester-based compound and then saponifying the modified PVA-based resin, a method of post-modifying the unmodified PVA-based resin, or the like. Can be manufactured by

In the present invention, the following unsaturated monomer copolymerizable with the vinyl ester compound may be copolymerized, but when a modified PVA resin is obtained, a modifying group is used as the following monomer. It is necessary to copolymerize the unsaturated monomer having. Examples of the unsaturated monomer include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene, 3-butene-1-ol, 4-pentene-1-ol, and 5-. Hydroxy group-containing α-olefins such as hexen-1-ol and derivatives such as acylated products thereof, unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, and undecylenic acid, and the like thereof. Examples thereof include salts, monoesters, amides such as dialkyl esters, diacetone acrylamides, acrylamides and methacrylamides, olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid and methallyl sulfonic acid, or salts thereof. These can be used alone or in combination of two or more. The content ratio of the copolymerizable monomer is usually 10 mol% or less.

Further, the modified PVA-based resin has a primary hydroxyl group in the side chain, and examples thereof include those having a primary hydroxyl group of usually 1 to 5, preferably 1 to 2, and particularly preferably 1. Be done. In particular, it is preferable to have a secondary hydroxyl group in addition to the primary hydroxyl group, and examples thereof include a PVA-based resin having a 1,2-diol structural unit in the side chain and a PVA-based resin having a hydroxyalkyl group in the side chain. The PVA-based resin having a 1,2-diol structural unit in such a side chain is, for example, (i) a method for saponifying a copolymer of vinyl acetate and 3,4-diacetoxy-1-butene, (ii) acetate. A method for saponifying and decarbonizing a copolymer of vinyl and vinyl ethylene carbonate, (iii) Kenting and decarbonating a copolymer of vinyl acetate and 2,2-dialkyl-4-vinyl-1,3-dioxolane. It can be produced by a method of ketalization, (iv) a method of saponifying a copolymer of vinyl acetate and glycerin monoallyl ether, or the like.

As the polymerization method in the preparation of the PVA-based resin (A), for example, a known polymerization method such as a solution polymerization method, an emulsion polymerization method, or a suspension polymerization method can be arbitrarily used, but usually methanol, ethanol or isopropyl can be used. It is carried out by a solution polymerization method using a lower alcohol such as alcohol as a solvent. In the case of the modified PVA-based resin, as a method for charging the monomer in such solution polymerization, first, the entire amount of the vinyl ester-based compound and, for example, a part of the unsaturated monomer having a carboxyl group are charged and polymerized. Any method can be used, such as a method of starting and adding the remaining unsaturated monomer continuously or sequentially during the polymerization period, a method of collectively charging the unsaturated monomer having a carboxyl group, and the like. can.

As the polymerization catalyst, a known polymerization catalyst such as an azo catalyst such as azobisisobutyronitrile, a peroxide catalyst such as acetyl peroxide, benzoyl peroxide and lauroyl peroxide is appropriately selected depending on the polymerization method. be able to. The reaction temperature of the polymerization is selected from the range of 50 ° C. to the boiling point of the polymerization catalyst.

The saponification is carried out in the presence of a saponification catalyst by dissolving the obtained copolymer in alcohol. Examples of the alcohol include alcohols having 1 to 5 carbon atoms such as methanol, ethanol and butanol. These can be used alone or in combination of two or more. The concentration of the copolymer in alcohol is selected from the range of 20 to 50% by weight.

As the saponification catalyst, for example, an alkali metal hydroxide such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethyllate, potassium methylate, or an alkali catalyst such as alcoholate can be used, and an acid can be used. It is also possible to use a catalyst. The amount of the saponification catalyst used is preferably 1 to 100 mmol equivalent with respect to the vinyl ester compound. These saponification catalysts can be used alone or in combination of two or more.

The carboxyl group-modified PVA-based resin in the modified PVA-based resin can be produced by any method. For example, (I) an unsaturated monomer having a carboxyl group and a vinyl ester-based compound are copolymerized and then saponified. (II) A method of polymerizing a vinyl ester-based compound by coexisting an alcohol, an aldehyde, a thiol or the like having a carboxyl group as a chain transfer agent, and then saponifying the vinyl ester compound.

As the vinyl ester compound in the method (I) or (II), the above-mentioned compounds can be used, but vinyl acetate is preferably used.

Examples of the unsaturated monomer having a carboxyl group in the above method (I) include an ethylenically unsaturated dicarboxylic acid (maleic acid, fumaric acid, itaconic acid, etc.) or an ethylenically unsaturated dicarboxylic acid monoester (malein). Acid monoalkyl ester, fumaric acid monoalkyl ester, itaconic acid monoalkyl ester, etc.), or ethylenically unsaturated dicarboxylic acid diester (maleic acid dialkyl ester, fumaric acid dialkyl ester, itaconic acid dialkyl ester, etc.) [However, these diesters Is required to change to a carboxyl group by hydrolysis during the saponification of the copolymer. ], Or a monomer such as an ethylenically unsaturated carboxylic acid anhydride (maleic anhydride, itaconic acid anhydride, etc.) or an ethylenically unsaturated monocarboxylic acid ((meth) acrylic acid, crotonic acid, etc.), and theirs. Examples thereof include maleic acid, maleic acid monoalkyl ester, maleic acid dialkyl ester, maleate, maleic anhydride, itaconic acid, itaconic acid monoalkyl ester, itaconic acid dialkyl ester, (meth) acrylic acid and the like. It is preferable to use maleic acid, maleic acid monoalkyl ester, maleic acid dialkyl ester, maleate, maleic anhydride, and particularly maleic acid monoalkyl ester. These can be used alone or in combination of two or more.

In the above method (II), a compound derived from a thiol having a particularly large chain transfer effect is particularly effective, and examples thereof include compounds represented by the following general formulas (1) to (3).

Further, salts of the compounds represented by the above general formulas (1) to (3) can also be mentioned. Specific examples thereof include mercaptoacetate, 2-mercaptopropionate, 3-mercaptopropionate, 2-mercaptostearate and the like. These compounds can be used alone or in combination of two or more.

The method for producing the carboxyl group-modified PVA-based resin is not limited to the above method, and for example, the PVA-based resin (partially saponified or completely saponified) is reactive with hydroxyl groups such as dicarboxylic acid, aldehyde carboxylic acid, and hydroxycarboxylic acid. It is also possible to carry out a method of post-reacting a carboxyl group-containing compound having a certain functional group.

When a sulfonic acid-modified PVA-based resin modified with a sulfonic acid group is used, for example, vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamide-2-methylpropane sulfonic acid, etc. A method of copolymerizing a copolymerized component of a sulfonic acid or a salt thereof with a vinyl ester compound and then saponifying it, a vinyl sulfonic acid or a salt thereof, a 2-acrylamide-2-methylpropanesulfonic acid or a salt thereof, and the like with PVA. It can be manufactured by a method of adding Michael to a based resin or the like.

On the other hand, examples of the method for post-modifying the unmodified PVA-based resin include methods for acetoacetic esterification, acetalization, urethanization, etherification, grafting, phosphoric acid esterification, and oxyalkylene formation of the unmodified PVA. Be done.

In addition to the unsaturated monomer having a carboxyl group and the vinyl ester compound, other general monomers may be contained in the polymer as long as the water solubility is not impaired, and the polymerization may be carried out. Examples of the body include alkyl esters of ethylenically unsaturated carboxylic acids, allyl esters of saturated carboxylic acids, α-olefins, alkyl vinyl ethers, alkyl allyl ethers, and (meth) acrylamide, (meth) acrylonitrile, styrene, and vinyl chloride. Etc. can be used. These can be used alone or in combination of two or more.

Generally, when unmodified PVA is used as the PVA-based resin (A), bleed-out of the plasticizer is likely to occur. Therefore, when the unmodified PVA is contained as the PVA-based resin (A) of the present invention, In particular, when only unmodified PVA is contained, the bleed-out can be significantly reduced by using a combination of the specific plasticizers described later and the content ratio thereof.

In the present invention, it is preferable to include the plasticizer (B) in the PVA-based resin (A) from the viewpoint of giving flexibility to the water-soluble film when it is used as a drug package. It is important not to use only one type of plasticizer (B), but to use at least two types in combination.

One of the plasticizers (B) is a polyhydric alcohol (b1) having a melting point of 80 ° C. or higher (hereinafter, may be abbreviated as a plasticizer (b1)), and the other has a melting point of 80 ° C. or higher. It is a polyhydric alcohol (b2) having a temperature of 50 ° C. or lower (hereinafter, may be abbreviated as a plasticizer (b2)).

As the polyhydric alcohol (b1) having a melting point of 80 ° C. or higher, most of sugar alcohols, monosaccharides and polysaccharides can be applied. Among them, for example, salicyl alcohol (83 ° C.) and catechol (105 ° C.). ), Resolsinol (110 ° C), Hydroquinone (172 ° C), Bisphenol A (158 ° C), Bisphenol F (162 ° C), Neopentylglycol (127 ° C) and other dihydric alcohols, Fluoroglucinol (218 ° C) and the like. Trihydric alcohols, erythritol (121 ° C), traytoll (88 ° C), tetrahydric alcohols such as pentaerythritol (260 ° C), xylitol (92 ° C), arabitol (103 ° C), fusitol (153 ° C), glucose (146 ° C). ° C), pentahydric alcohols such as fructose (104 ° C), hexahydric alcohols such as mannitol (166 ° C), sorbitol (95 ° C), inositol (225 ° C), lactitol (146 ° C), sucrose (186 ° C), trehalose. Examples thereof include octavalent alcohols such as (97 ° C.) and 9-valent or higher alcohols such as Martinol (145 ° C.). These can be used alone or in combination of two or more. The numbers in parentheses above indicate the melting points of each compound.
Among the above, those having a melting point of 85 ° C. or higher, particularly preferably 90 ° C. or higher, are preferable in terms of the tensile strength of the water-soluble film. The upper limit of the melting point is preferably 300 ° C, particularly preferably 200 ° C.

Further, in the present invention, it is preferable that the number of hydroxyl groups in one molecule of the plasticizer (b1) is 4 or more in terms of compatibility with the PVA-based resin, and more preferably 5 to 10 is particularly preferable. The number is 6 to 8, and specific examples thereof include sorbitol, sucrose, and trehalose.

Further, in the present invention, the plasticizer (b1) preferably has a molecular weight of 150 or more, more preferably 160 to 500, and particularly preferably 180 to 400, in terms of tension of the water-soluble film. Specifically, for example, sorbitol, sucrose and the like are preferable.

On the other hand, as the polyhydric alcohol (b2) having a melting point of 50 ° C. or lower, most aliphatic alcohols can be applied, and for example, ethylene glycol (-13 ° C.), diethylene glycol (-11 ° C.), and the like are preferable. Triethylene glycol (-7 ° C), propylene glycol (-59 ° C), tetraethylene glycol (-5.6 ° C), 1,3-propanediol (-27 ° C), 1,4-butanediol (20 ° C) , 1,6-Hexanediol (40 ° C), tripropylene glycol, dihydric alcohols such as polyethylene glycol having a molecular weight of 2000 or less, trihydric or higher such as glycerin (18 ° C), diglycerin, triethanolamine (21 ° C). Alcohol can be mentioned. In terms of the flexibility of the water-soluble film, a film having a melting point of 30 ° C. or lower, particularly preferably 20 ° C. or lower is preferable. The lower limit of the melting point is usually −80 ° C., preferably −10 ° C., and particularly preferably 0 ° C. These can be used alone or in combination of two or more. The numbers in parentheses above indicate the melting points of each compound.

Further, in the present invention, it is easy to control the flexibility near room temperature (25 ° C.) when the number of hydroxyl groups in one molecule of the plasticizer (b2) is 4 or less, particularly 3 or less. Preferably, specifically, for example, glycerin and the like are suitable.

Further, in the present invention, the plasticizer (b2) preferably has a molecular weight of 100 or less, more preferably 50 to 100, and particularly preferably 60 to 95, in terms of easy control of flexibility. Specifically, for example, glycerin and the like are suitable.

In the present invention, a plasticizer (b3) other than the above-mentioned plasticizers (b1) and (b2) can be used in combination, and examples of the plasticizer (b3) include trimethylolpropane (58 ° C.) and diethylene glycol. Alcohols such as monomethyl ether, cyclohexanol, carbitol, polypropylene glycol, ethers such as dibutyl ether,
Carboxy acids such as stearate, oleic acid, linoleic acid, linolenic acid, sorbic acid, citric acid, adipic acid, ketones such as cyclohexanone, amines such as monoethanolamine, triethanolamine, ethylenediamine, imidazole compounds, alanine, Examples thereof include amino acids such as glycine, aspartic acid, glutamic acid, histidine, lysine and cysteine. These can be used alone or in combination of two or more.

In the present invention, the content of the plasticizer (B) is 35 parts by weight or more , particularly 35 to 70 parts by weight, and further 35 to 60 parts by weight with respect to 100 parts by weight of the PVA-based resin (A). In particular, it is preferably 35 to 50 parts by weight. If the content of the plasticizer (B) is too small, the tension of the water-soluble film tends to be impaired over time when a liquid such as a liquid detergent is packaged into a package. If it is too much, the mechanical strength tends to decrease.

The content ratio (b1 / b2) of the plasticizer (b1) and the plasticizer (b2) is preferably 0.1 to 0.9 by weight, particularly 0.15 to 0.8. Further, it is preferably 0.2 to 0.7, particularly preferably 0.25 to 0.6. If the content is too small, the water-soluble film tends to be too soft and blocking tends to occur, and if it is too large, the water-soluble film tends to be too hard and the plasticizer tends to bleed out. be.

As for the contents of the plasticizer (b1) and the plasticizer (b2), the amount of the plasticizer (b1) is 5 to 40 parts by weight, and further 8 to 8 to 100 parts by weight of the PVA-based resin (A). It is preferably 30 parts by weight, particularly preferably 10 to 25 parts by weight, and the plasticizer (b2) is preferably 5 to 40 parts by weight, more preferably 10 to 35 parts by weight, and particularly preferably 15 to 30 parts by weight.
If the amount of the plasticizer (b1) is too small, the water-soluble film tends to be too soft and blocking tends to occur, and if it is too large, the water-soluble film tends to be too hard and becomes brittle even in a low-humidity environment. Tend. Further, if the amount of the plasticizer (b2) is too small, the water-soluble film tends to be too hard and tends to be brittle even in a low-humidity environment, and if it is too large, the water-soluble film becomes too soft and blocking is likely to occur. Tend to be.

Further, the total amount of the plasticizer (b1) and the plasticizer (b2) is preferably 70% by weight or more, more preferably 80% by weight or more, and particularly 87% by weight or more with respect to the entire plasticizer (B). In particular, it is preferably 90% by weight or more, more preferably 95% by weight or more. Particularly preferably, the entire plasticizer (B) is composed of only the above-mentioned plasticizer (b1) and the plasticizer (b2). If the total amount of the plasticizers (b1) and (b2) is too small, the mechanical strength tends to decrease.

In the present invention, a filler (C), a surfactant (D) and the like can be further contained, if necessary.

The filler (C) used in the present invention is contained for the purpose of blocking resistance, and specific examples thereof include inorganic fillers and organic fillers, with organic fillers being preferred. The average particle size is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm. The average particle size can be measured by, for example, a laser diffraction type particle size distribution measuring device or the like.

The average particle size of the inorganic filler is preferably 1 to 10 μm, and if the average particle size is too small, the effect of dispersibility of the water-soluble film in water tends to be small, and if it is too large. When the water-soluble film is molded and stretched, it tends to become pinholes or deteriorate in appearance.

Specific examples of the inorganic filler include talc, clay, silicon dioxide, diatomaceous soil, kaolin, mica, asbestos, gypsum, graphite, glass balloon, glass beads, calcium sulfate, barium sulfate, ammonium sulfate, calcium sulfite, calcium carbonate. , Whisker-like calcium carbonate, magnesium carbonate, dosonite, dolomite, potassium titanate, carbon black, glass fiber, alumina fiber, boron fiber, processed mineral fiber, carbon fiber, carbon hollow sphere, bentonite, montmorillonite, copper powder, sodium sulfate, Potassium sulfate, zinc sulfate, copper sulfate, iron sulfate, magnesium sulfate, aluminum sulfate, potassium aluminum sulfate, ammonium nitrate, sodium nitrate, potassium nitrate, aluminum nitrate, ammonium chloride, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, sodium phosphate , Potassium chromate, calcium citrate and the like. These can be used alone or in combination of two or more.

The organic filler preferably has an average particle size of 0.5 to 20 μm, more preferably 0.5 to 10 μm, particularly preferably 0.5 to 7 μm, still more preferably 0.5 to 5 μm. be. If the average particle size is too small, the cost tends to be high, and if it is too large, pinholes tend to occur when the water-soluble film is stretched during molding.

Examples of such organic fillers include starch, melamine-based resins, polymethyl (meth) acrylate-based resins, polystyrene-based resins, and biodegradable resins such as polylactic acid. As the organic filler, a biodegradable resin such as a polymethyl (meth) acrylate resin, a polystyrene resin, or a starch is particularly preferably used. These can be used alone or in combination of two or more.

Examples of the above-mentioned starch include raw starch (corn starch, horse bell starch, sweet potato starch, wheat starch, kissaba starch, sago starch, tapioca starch, morokoshi starch, rice starch, bean starch, kudzu starch, warabi starch, hass starch, etc. Hishi starch, etc.), physically modified starch (α-starch, fractionated amylose, wet heat treated starch, etc.), enzyme-modified starch (hydrolyzed dextrin, enzymatically degraded dextrin, amylose, etc.), chemically degraded modified starch (acid-treated starch, hypoa) Examples thereof include chloric acid oxidized starch, dialdehyde starch, etc.), chemically modified starch derivatives (esterified starch, etherified starch, cationized starch, crosslinked starch, etc.) and the like. Above all, it is preferable to use raw starch, especially corn starch and rice starch, from the viewpoint of easy availability and economy. These can be used alone or in combination of two or more.

The content of the filler (C) is preferably 1 to 30 parts by weight, more preferably 2 to 25 parts by weight, and particularly 2.5 to 20 parts by weight, based on 100 parts by weight of the PVA-based resin (A). It is preferably a part. If the content is too small, the blocking resistance tends to decrease, and if it is too large, pinholes tend to occur when the water-soluble film is stretched during molding.

The surfactant (D) used in the present invention is contained for the purpose of improving the peelability from the cast surface during the production of a water-soluble film, and is usually a nonionic surfactant, a cationic surfactant, or an anion. Surfactants can be mentioned. Examples of the nonionic surfactant include polyoxyethylene nonylphenyl ether, polyoxyethylene octyl nonyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene sorbitan monolaurate, and polyoxyethylene sorbitan mono. Polyoxyethylene such as palmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyalkylene alkyl ether phosphate monoethanolamine salt, polyoxyethylene laurylamino ether, polyoxyethylene stearylamino ether, etc. Examples thereof include alkylamino ethers, which are used alone or in combination of two or more. Among them, polyoxyalkylene alkyl ether phosphoric acid ester monoethanolamine salt and polyoxyethylene laurylamino ether are preferable from the viewpoint of production stability. These can be used alone or in combination of two or more.

The content of the surfactant (D) is preferably 0.01 to 3 parts by weight, more preferably 0.1 to 2.5 parts by weight, based on 100 parts by weight of the PVA-based resin (A). In particular, it is preferably 0.5 to 2 parts by weight. If the content is too small, the peelability between the cast surface of the film-forming device and the film-formed water-soluble film tends to decrease, and the productivity tends to decrease. If the content is too large, the water-soluble film is used as a package. There is a tendency to cause inconveniences such as a decrease in adhesive strength at the time of sealing.

In the present invention, other water-soluble polymers (for example, sodium polyacrylic acid, polyethylene oxide, polyvinylpyrrolidone, dextrin, chitosan, chitin, methylcellulose, hydroxyethylcellulose, etc.) and other water-soluble polymers are used as long as the object of the invention is not impaired. It is also possible to contain a fragrance, a rust preventive, a colorant, a bulking agent, an antifoaming agent, an ultraviolet absorber, liquid paraffins, a fluorescent whitening agent, a bitter taste component (for example, denatonium benzoate, etc.) and the like. These can be used alone or in combination of two or more.

Further, in the present invention, it is preferable to add an antioxidant from the viewpoint of suppressing yellowing. Examples of such antioxidants include sodium sulfite, potassium sulfite, calcium sulfite, ammonium sulfite and other sulfites, tartrate acid, ascorbic acid, sodium thiosulfite, catechol, longalit and the like, and among them, sodium sulfite, particularly sodium sulfite. Is preferable. The blending amount is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, and particularly preferably 0.3 to 3 parts by weight with respect to 100 parts by weight of the PVA-based resin (A).

In the present invention, as described above, a resin composition comprising a PVA-based resin (A) and a plasticizer (B), and if necessary, a filler (C), a surfactant (D) and the like is obtained. The resin composition is dissolved or dispersed with water to prepare a film-forming raw material, and the film is formed into a PVA-based film. For such film formation, for example, a method such as a melt extrusion method or a flow casting method can be adopted, and the flow casting method is preferable in terms of film thickness accuracy.

In the present invention, when the above-mentioned hypersalivation method is performed, for example, it is performed as follows.
As the dissolution method, normal temperature dissolution, high temperature dissolution, pressure dissolution and the like are usually adopted, and among them, high temperature dissolution and pressure dissolution are preferable because there are few undissolved substances and the productivity is excellent.
The melting temperature is usually 80 to 100 ° C., preferably 90 to 100 ° C. in the case of high temperature melting, and usually 80 to 130 ° C., preferably 90 to 120 ° C. in the case of pressure melting. The dissolution time is usually 1 to 20 hours, preferably 2 to 15 hours, and more preferably 3 to 10 hours. If the dissolution time is too short, undissolved substances tend to remain, and if the dissolution time is too long, productivity tends to decrease.

Further, in the melting step, examples of the stirring blade include a paddle, a full zone, a max blend, a twister, an anchor, a ribbon, a propeller, and the like.
Further, after dissolution, a defoaming treatment is performed on the obtained PVA-based resin aqueous solution, and examples of such defoaming methods include static defoaming, vacuum defoaming, and biaxial extrusion defoaming. Be done. Of these, static defoaming and biaxial extrusion defoaming are preferable.
The temperature for static defoaming is usually 50 to 100 ° C., preferably 70 to 95 ° C., and the defoaming time is usually 2 to 30 hours, preferably 5 to 20 hours.

In the casting method, for example, water is added to the PVA-based resin (A) (powder) to make a PVA-based resin aqueous solution, and then the plasticizer (B) and other formulations are added to form an aqueous dispersion or a resin composition. Obtain an aqueous solution. Alternatively, water is added to the resin composition containing the PVA-based resin (A), the plasticizer (B), and various formulations to obtain an aqueous dispersion or aqueous solution of the resin composition. The solid content concentration of the aqueous dispersion or aqueous solution of the resin composition is preferably 10 to 50% by weight, particularly preferably 15 to 40% by weight, and more preferably 20 to 35% by weight. If the concentration is too low, the productivity of the water-soluble film tends to decrease, and if it is too high, the viscosity becomes too high, it takes time to defoam the dope, and die lines are generated when the water-soluble film is formed. Tend to do. Further, if the temperature of the metal surface of the endless belt or drum roll is too low, it tends to take a long time to dry, and if it is too high, it tends to foam during film formation.

The above water dispersion or aqueous solution is passed through a slit such as a T-die, poured onto a cast surface such as a metal surface of an endless belt or a drum roll or a surface of a plastic substrate such as a polyethylene terephthalate film, dried, and if necessary. Further heat treatment can be performed to obtain the PVA-based film of the present invention.
For example, it can be carried out under the following film forming conditions.

The temperature of the discharge portion in the aqueous dispersion or aqueous solution of the PVA-based resin composition is preferably 60 to 98 ° C, particularly 70 to 95 ° C. If the temperature is too low, the drying time tends to be long and the productivity tends to decrease, and if the temperature is too high, foaming or the like tends to occur.

At the time of film formation, the film formation speed is preferably 3 to 80 m / min, particularly preferably 5 to 60 m / min, and more preferably 8 to 50 m / min.
Further, the heat treatment can be performed by a thermal roll, but other examples include floating and far-infrared ray treatment. In particular, it is preferable to use a heat roll in terms of productivity. The heat treatment temperature is preferably 50 to 150 ° C., particularly preferably 70 to 130 ° C., and the heat treatment time is preferably 1 to 60 seconds, particularly 3 to 50 seconds, and further. Is preferably 5 to 40 seconds.

Further, an applicator can be used to cast an aqueous dispersion or an aqueous solution of the resin composition onto a plastic substrate such as a polyethylene terephthalate film or a polyethylene film or a metal substrate and dry it to obtain a PVA-based film.

The thickness of the PVA-based film is appropriately selected depending on the intended use and the like, but is preferably 10 to 120 μm, more preferably 15 to 110 μm, and particularly preferably 20 to 100 μm. If the thickness is too thin, the mechanical strength of the PVA-based film tends to decrease, and if it is too thick, the dissolution rate in water tends to be slow, and the film forming efficiency tends to decrease.

The width of the PVA-based film is appropriately selected depending on the intended use and the like, but is preferably 300 to 5000 mm, more preferably 500 to 4000 mm, and particularly preferably 800 to 3000 mm. If the width is too narrow, the production efficiency tends to decrease, and if it is too wide, it tends to be difficult to control the slack and the film thickness.

The length of the PVA-based film is appropriately selected depending on the intended use and the like, but is preferably 500 to 20000 m, more preferably 800 to 15000 m, and particularly preferably 1000 to 10000 m. If the length is too short, it tends to take time and effort to switch the film, and if it is too long, the appearance is poor due to winding and the weight tends to be too heavy.

The surface of the PVA-based film may be plain, but from the viewpoints of blocking resistance, slipperiness during processing, reduction of adhesion between products, and appearance, an embossed pattern is formed on one or both sides of the PVA-based film. It is also preferable to apply uneven processing such as pear-skin pattern, special engraving pattern, etc.
In such uneven processing, the processing temperature is usually 60 to 150 ° C, preferably 80 to 140 ° C. The processing pressure is usually 2 to 8 MPa, preferably 3 to 7 MPa. The processing time is usually 0.01 to 5 seconds, preferably 0.1 to 3 seconds, although it depends on the processing pressure and the film forming speed.
Further, if necessary, a cooling treatment may be performed after the uneven processing treatment in order to prevent unintended stretching of the film due to heat.

Further, in the present invention, the water content of the obtained PVA-based film (water-soluble film) is preferably 3 to 15% by weight, particularly 5 to 14% by weight, in terms of mechanical strength and sealing property. Further, it is preferably 6 to 13% by weight. If the water content is too low, the film tends to be too hard, and if it is too high, blocking tends to occur. The adjustment to such a water content can be achieved by appropriately setting drying conditions and humidity control conditions.
The water content is measured in accordance with JIS K 6726 3.4, and the obtained volatile content is used as the water content.

In the present invention, the film formation is preferably performed in an environment of, for example, 10 to 35 ° C, particularly 15 to 30 ° C. The humidity is usually 70% RH or less.

In the present invention, the obtained PVA-based film can be wound into a core tube (S1) to form a film roll. The obtained film roll can be supplied as a product as it is, but preferably, it is wound around a core tube (S2) having a length corresponding to a film width of a desired size and supplied as a film roll.

The core tube (S1) for winding the film has a cylindrical shape, and the material thereof can be appropriately selected from metal, plastic and the like, but metal is preferable in terms of robustness and strength.
The inner diameter of the core tube (S1) is preferably 3 to 30 cm, more preferably 10 to 20 cm.
The wall thickness of the core tube (S1) is preferably 1 to 30 mm, more preferably 2 to 25 mm.
The length of the core tube (S1) needs to be longer than the width of the film, and it is preferable that the length of the core tube (S1) protrudes from the end of the film roll by 1 to 50 cm.

Further, the core tube (S2) has a cylindrical shape, and the material thereof can be appropriately selected from paper, metal, plastic and the like, but paper is preferable in terms of weight reduction and handling.
The inner diameter of the core tube (S2) is preferably 3 to 30 cm, more preferably 10 to 20 cm.
The wall thickness of the core tube (S2) is preferably 1 to 30 mm, more preferably 3 to 25 mm.
The length of the core tube (S2) may be a length equal to or longer than the PVA-based film width of the product, and is preferably the same to 50 cm longer.

When winding on the core tube (S2), the PVA-based film is slit to a desired width.
The slit is slit by using a shear blade, a leather blade, or the like, but it is preferable to slit by a shear blade from the viewpoint of smoothness of the slit cross section.

In the present invention, the obtained film roll is wrapped in a packaging film made of a water vapor barrier resin, and the film is not particularly limited, but has a moisture permeability of 10 g / ^m 2.24 hr (according to JIS Z 0208). Measurement) The following can be used. Specific examples include, for example, a single-layer film such as high-density polyethylene, low-density polyethylene, polypropylene, polyester, polyvinylidene chloride-coated polypropylene, glass-deposited polyester, or a laminated film thereof, or a split cloth, paper, or non-woven fabric. Laminated film and the like can be mentioned. Examples of the laminated film include a laminated film of glass-deposited polyester and polyethylene, a laminated film of polyvinylidene chloride-coated polypropylene and polyethylene, and the like.

It is also preferable to carry out antistatic treatment on such a film from the viewpoint of preventing foreign matter from entering, and the antistatic agent may be kneaded into the film or coated on the surface. In the case of kneading, an antistatic agent of about 0.01 to 5% by weight is used with respect to the resin, and in the case of surface coating, an antistatic agent of about 0.01 to 1 g / m ² is used.
As the antistatic agent, for example, alkyldiethanolamine, polyoxyethylenealkylamine, higher fatty acid alkanolamide, sorbitan fatty acid ester and the like are used.

Next, it is preferable to wrap the film roll with a wrapping film made of a steam barrier resin, and then further wrap the wrapping film made of an aluminum material. Such films include aluminum foil, aluminum foil and a moisture-resistant plastic film. Laminated film (for example, laminated film of aluminum foil and polyethylene film), laminated film of aluminum vapor-deposited film and moisture-resistant plastic film (for example, laminated film of aluminum-deposited polyester film and polyethylene film), laminated film of alumina-deposited film and moisture-resistant plastic film (For example, a laminated film of an alumina vapor-deposited polyester film and a polyethylene film) and the like are particularly useful in the present invention, a laminated film of an aluminum foil and a polyolefin film, and a laminated film of an aluminum vapor-deposited film and a polyolefin film, particularly a stretched polypropylene film. A laminated film having a composition of / polyethylene film / aluminum foil / polyethylene film, a laminated film having a structure of stretched polypropylene film / low density polyethylene film / aluminum foil, and the like are useful.
For packaging, the inner wrapping film made of steam barrier resin and the outer wrapping film made of aluminum material may be sequentially wrapped, and the excess portion in the width direction may be pushed into the core tube.

In order to prevent scratches on the edges and adhesion of foreign substances such as dust to the film roll of the present invention, core tube through holes are provided at both ends of the film roll directly on the film roll or after being wrapped with a wrapping film. A protective pad can be attached.
As for the shape of the protective pad, a disk-shaped sheet or film is practical according to the film roll. In order to make the protective effect remarkable, it is preferable to add a cushioning function such as a foam, a woven fabric, or a non-woven fabric. Further, a desiccant may be separately enclosed in order to protect the film roll from moisture, or may be laminated or mixed in the protective pad.
Plastic is advantageous as the material of the protective pad, and specific examples thereof include polystyrene, polyethylene, polypropylene, polyester, polyvinyl chloride and the like.

Further, as the protective pad containing the above-mentioned desiccant, for example, calcium chloride, silica gel, molecular sieves, saccharides, particularly saccharides having high osmotic pressure, desiccants such as water-absorbent resins, or water-absorbents can be used as natural celluloses, synthetic celluloses, etc. A moisture-absorbing layer that has been dispersed, impregnated, and applied to a moldable material such as glass cloth or non-woven fabric, or these dryers or water-absorbents can be applied to the above-mentioned moldable material, polyester film, polyethylene film, polypropylene film, Teflon ( Registered trademark) Examples include those sandwiched between thermoplastic resin films such as films.
Examples of commercially available sheet desiccants include "ID Sheet" manufactured by ID, "Arrow Sheet" and "Zeo Sheet" manufactured by Shinagawa Kasei Co., Ltd., and "High Sheet Dry" manufactured by High Sheet Industry Co., Ltd. ..

The film roll packaged by such means is supported by providing brackets (support plates) on the protrusions at both ends of the core tube or placing the protrusions at both ends on a pedestal, and is supported in the so-called air without touching the ground. It is preferable that it is stored and transported in a floating state. Brackets are used when the film width is relatively small, and mounts are used when the film width is relatively large.
The bracket is made of a veneer plate or a plastic plate, and its size may be such that the four sides of the bracket are larger than the diameter of the film roll.

Then, a pair of brackets are arranged and fitted upright on the core tube protrusions at both ends of the film roll so as to face each other, and are provided on the film roll. The fitting may be provided with a hollow hole slightly larger than the diameter of the core tube in the center of the bracket, or may be hollowed out in a U shape from the upper part to the center of the bracket so that the core tube can be easily inserted.

Film rolls supported by brackets are stored and transported in cartons such as cardboard boxes, but when using rectangular brackets, the four corners may be cut off to facilitate storage work. preferable.
Further, it is advantageous to fix the pair of brackets with a binding tape so that they do not wobble, and the side surface (thickness portion) of the brackets has the same width as the tape so that the tape does not move or loosen at that time. It is also practical to provide a tape misalignment prevention groove to some extent.

When storing or transporting the packaged film roll, it is desirable to avoid extremely high and low temperature, low humidity and high humidity conditions, specifically, the temperature is 10 to 30 ° C and the humidity is 40 to 75% RH. ..

The water-soluble film of the present invention thus obtained is useful for various packaging applications, and particularly useful for unit packaging applications such as chemicals. The drug is not particularly limited and may be alkaline, neutral or acidic, and the shape of the drug may be any of granules, tablets, powders, powders, liquids and the like, but particularly in water. Drugs that are dissolved or dispersed are preferred, and are particularly useful for packaging liquid detergents.

As the liquid detergent, the pH value when dissolved or dispersed in water is preferably 6 to 12, particularly preferably 7 to 11, and the water content is preferably 15% by weight or less, particularly 0. It is preferably 1 to 10% by weight, more preferably 0.1 to 7% by weight, and the film does not gel or insolubilize and has excellent water solubility.
The pH value is measured according to JIS K 3362 8.3. The water content is measured according to JIS K 3362 7.21.3.

<Drug packaging>
The drug package of the present invention comprises a liquid detergent contained in a package made of a water-soluble film. The size of the drug package is usually 10 to 50 mm in length, preferably 20 to 40 mm. The thickness of the film of the package made of the water-soluble film is usually 10 to 120 μm, preferably 15 to 110 μm, and more preferably 20 to 100 μm. The amount of liquid detergent contained is usually 5 to 50 mL, preferably 10 to 40 mL.

The drug package of the present invention usually has a smooth surface. However, in terms of blocking resistance, slipperiness during processing, reduction of adhesion between products (packages), and appearance, embossed patterns, fine uneven patterns, and special engraved patterns on the outer surface of the package (water-soluble film). , Etc. may be subjected to uneven processing. Further, the drug package of the present invention in which the liquid detergent is packaged retains the shape containing the liquid detergent during storage. Then, during use (during washing), the package (water-soluble film) comes into contact with water, so that the package dissolves and the contained liquid detergent flows out of the package.

When the water-soluble film of the present invention is used to wrap a liquid detergent into a package, a known method can be adopted. For example, (1) a method of heat-sealing, (2) a method of water-sealing, (3) a method of glue-sealing, and the like can be mentioned. Among them, the (2) water-sealing method is versatile and advantageous.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.
In the example, "part" and "%" mean the weight standard.

The following PVA-based resins were prepared.
Unmodified PVA (A1): 4% aqueous solution viscosity at 20 ° C. 22 mPa · s, average saponification degree 88 mol%
Unmodified PVA (A2): 4% aqueous solution viscosity at 20 ° C. 5 mPa · s, average saponification degree 88 mol%
Carboxyl group-modified PVA (A3): Viscosity of 4% aqueous solution at 20 ° C. 22 mPa · s, average saponification degree 94 mol%, modification amount by maleic acid monomethyl ester 2.0 mol%
Unmodified PVA (A4): 4% aqueous solution viscosity at 20 ° C., 18 mPa · s, average saponification degree 88 mol%

<Example 1>
65 parts of unmodified PVA (A1), 35 parts of unmodified PVA (A2), 10 parts of sorbitol (b1) and 30 parts of glycerin (b2) as plasticizer (B) as PVA-based resin (A). , 8 parts of starch (average particle size 20 μm) as the filler (C), 2 parts of the polyoxyalkylene alkyl ether phosphate monoethanolamine salt as the surfactant (D), and water are mixed for dissolution treatment. Then, a PVA aqueous solution (solid content concentration 25%) in which the ester was dispersed was obtained.
The obtained PVA aqueous solution was defoamed at 80 ° C. and cooled to 40 ° C. The PVA aqueous solution was poured onto a polyethylene terephthalate film, passed through a 3 m drying chamber (105 ° C.) at a speed of 0.350 m / min, and dried to obtain a PVA-based film (water-soluble film) having a thickness of 87 μm. rice field.
The PVA-based film obtained above was evaluated as follows. The evaluation results are shown in Table 1.

[Blocking resistance]
The PVA-based film was cut into 150 mm squares, 50 sheets were stacked, a 2 kg weight of 150 mm square was placed on the PVA-based film, and the film was left at 23 ° C. × 40% RH for 1 week. Then, the state when the PVA-based film was taken out was visually observed and evaluated according to the following criteria.
○ ・ ・ ・ No blocking was observed, and the film was peeled off the moment it was lifted.
×: Blocking was observed, and the film could not be peeled off just by lifting it.

[Bleed-out resistance]
The PVA-based film was cut into 1 m squares and left for 1 week under the conditions of 23 ° C. × 50% RH. Then, the state when the PVA-based film was taken out was visually observed and evaluated according to the following criteria.
○ ・ ・ ・ No bleed out was confirmed.
×: Bleedout of solids and liquids was confirmed.

< Reference Examples 1 to 3 , Comparative Examples 1 to 2>
In Example 1, a PVA-based film (water-soluble film) was obtained in the same manner except that the changes were made as shown in Table 1.
The obtained PVA-based film (water-soluble film) was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Further, the PVA-based films of Examples 1 , Reference Examples 1 to 3 and Comparative Example 2 obtained above were evaluated as follows (tension evaluation of the PVA-based film of the drug package). The evaluation results are shown in Table 2.

[Evaluation of PVA-based film tension in drug packaging]
With respect to the PVA-based film obtained above, a drug package was produced by the following procedure using a package manufacturing machine manufactured by Angel.
That is, a PVA-based film (bottom film) is fixed on a mold (molded package: length 45 mm, width 42 mm, height 30 mm) at the bottom of the device, and a PVA-based film (top) is also fixed at the top of the device. The film) was fixed. The bottom film was heated for 10 seconds with a dryer that generates hot air at 90 ° C., and the bottom film was vacuum formed into a mold. After that, 20 mL of liquid detergent (containing 5.4% glycerin, 22.6% propylene glycol, 10.4% water) packaged in "Ariel Power Gel Ball" manufactured by P & G was put into a molded PVA film. did. 1.5 g of water was applied to the top film, and the top film and the bottom film were pressure-bonded. After crimping for 30 seconds, the vacuum was released to obtain a drug package. Then, after adjusting the humidity in an environment of 23 ° C. and 40% RH for 2 hours, the height (X1 mm) of the drug package when it was naturally self-supporting was measured and found to be 31 mm.
Subsequently, after the drug package was prepared, it was left in an environment of 40 ° C. and 65% RH for 1 week, then left in an environment of 23 ° C. and 50% RH for 1 hour, and then naturally self-sustaining. The height (X2 mm) of the drug package was measured, and the tension of the PVA-based film of the drug package was evaluated by the value calculated by the following formula (X3 mm). The smaller the value of X3, the better the tension of the PVA-based film.
(Equation) X3 = X1-X2

From the results in Table 1 above, in the examples, by increasing the content of the polyhydric alcohol having a lower melting point than that of the polyhydric alcohol having a high melting point as a plasticizer, the blocking resistance and the bleed-out resistance were excellent. In contrast to the water-soluble film, in the comparative example, two types of plasticizers are used in the same amount, or only one type of plasticizer is used, which results in bleed-out resistance and blocking resistance. Nothing was obtained that satisfied both sexes.

Further, from the results in Table 2 above, the water-soluble film of the example in which the plasticizer has a specific composition and a specific content has excellent mechanical strength, and is in a state of being a package in which a liquid such as a liquid detergent is packaged. However, it can be seen that the water-soluble film is capable of forming a good package without impairing the tension of the water-soluble film over time.

The water-soluble film of the present invention is a water-soluble film having excellent water solubility, excellent blocking resistance, and reduced bleed-out of a plasticizer, and is particularly a water-soluble film capable of forming a good package. It can be used for various packaging applications, and is particularly useful for unit packaging applications such as chemicals.

Claims (7)

A water-soluble film containing a polyvinyl alcohol-based resin (A) and a plasticizer (B), wherein the polyvinyl alcohol-based resin (A) contains unmodified polyvinyl alcohol, and the plasticizer (B). The content is 35 to 50 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol-based resin (A) , and the plasticizer (B) has a melting point of 80 ° C. or higher and the number of hydroxyl groups in one molecule is 6 to 8. It contains a polyvalent alcohol (b1) having a molecular weight of 180 to 400 and a polyhydric alcohol (b2) having a melting point of 50 ° C. or lower, and the content ratio (b1 / b2) of the plasticizer (B) is a weight ratio. And 0. A water-soluble film having a value of 2 to 0.9, wherein the water-soluble film does not contain dipropylene glycol as the plasticizer (B) . The water-soluble film according to claim 1, wherein the polyhydric alcohol (b2) having a melting point of 50 ° C. or lower has 4 or less hydroxyl groups in one molecule. The water-soluble film according to claim 1 or 2 , wherein the polyhydric alcohol (b2) having a melting point of 50 ° C. or lower has a molecular weight of 100 or less. The water-soluble film according to any one of claims 1 to 3 , wherein the water-soluble film has a water content of 3 to 15% by weight. The water-soluble film according to any one of claims 1 to 4 , which is used for drug packaging. The drug package according to any one of claims 1 to 5 , wherein the liquid detergent is packaged in the water-soluble film. The drug package according to claim 6 , wherein the liquid detergent has a pH value of 6 to 12 and a water content of 15% by weight or less when dissolved or dispersed in water.