JP7005894B2 - 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) in more detail. The present invention relates to a water-soluble film having little change in color over time even when a liquid such as a liquid detergent is packaged into a package.

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.

Then, conventionally, taking advantage of the water solubility of PVA-based resin, it has been proposed to package various chemicals such as pesticides and detergents in a bag made of a film of PVA-based resin (unit packaging), and it is widely used. It is used.

As a water-soluble unit packaging bag used for such an application, for example, 100 parts by weight of PVA is mixed with 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. A water-soluble film (see, for example, Patent Document 1), a 4% by weight aqueous solution viscosity at 20 ° C. of 10 to 35 mPs · s, an average saponification degree of 80.0 to 99.9 mol%, and an anionic group modification amount of 1 to 1 to With respect to 100 parts by weight of the 10 mol% anionic group-modified PVA resin (A), 20 to 50 parts by weight of the plasticizer (B), 2 to 30 parts by weight of the filler (C), and 0. A water-soluble film (for example, see Patent Document 2) made of a resin composition containing 01 to 2.5 parts by weight is known.

Japanese Unexamined Patent Publication No. 2001-329130 Japanese Unexamined Patent Publication No. 2004-161823

The water-soluble film disclosed in Patent Documents 1 and 2 is excellent in water solubility and can be used as a drug package by packaging a liquid detergent or the like. However, in order to improve the stability over time with respect to the detergent, It is desirable that the water-soluble film for packaging contains acid-modified PVA.
However, the water-soluble film using acid-modified PVA has a problem that it turns yellow over time when it comes into contact with a liquid detergent. In recent years, there has been a demand for a water-soluble film that is sensitive to changes in color as a package and has less yellowing over time.
Further, in the water-soluble film forming the package, the strength of the film itself is also important in consideration of the physical resistance to vacuum suction when forming the package and the tensile strength resistance when pressed against the package. It is a thing.

Therefore, in the present invention, under such a background, even when a liquid such as a liquid detergent is packaged to form a package, the water-soluble film has little change in color over time and is also excellent in film strength. It is an object of the present invention to provide a water-soluble film capable of forming a package, and further to provide a drug package in which various drugs are packaged in the water-soluble film.

However, as a result of diligent research in view of such circumstances, the present inventors have found that in a water-soluble film containing a PVA-based resin, the water-soluble film is immersed in a liquid detergent having a predetermined YI value for a predetermined period of time and left to stand. The present invention has been completed by finding that by reducing the change in color of the film before and after, even when a liquid such as a liquid detergent is packaged to form a package, the change in color over time is small. ..

That is, the gist of the present invention is a water-soluble film containing a PVA-based resin (A), in which the water-soluble film is immersed in a liquid detergent having a YI value of 40 to 70 in a 5% by weight aqueous solution. The difference (X2-X1) between the YI value (X ₂ ) of the film after being left at ₅₀ ° C. for 25 days and the YI value (X ₁ ) of the film before immersion is ₂ or less. It is a thing.

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

The water-soluble film of the present invention has little change in color over time even when a liquid such as a liquid detergent is packaged into a package, and has an excellent effect on film strength. It can be used for various packaging applications, and is particularly useful for unit packaging applications such as chemicals.

Hereinafter, the present invention will be specifically described.
The water-soluble film of the present invention is a water-soluble film containing a PVA-based resin (A). Then, in a state where the water-soluble film is immersed in a liquid detergent having a YI value of 40 to 70 in a 5% by weight aqueous solution, the YI value (X ₂ ) of the film after being left at 50 ° C. for 25 days and before immersion. The difference (X ₂ -X ₁ ) between the YI values (X ₁ ) of the film is 2 or less. The difference in YI values (X ₂ -X ₁ ) is preferably 1.9 or less, particularly preferably 1.85 or less, and further preferably 1.8 or less. If the difference in YI values (X ₂ -X ₁ ) is too large, the color change over time becomes large, and the object of the present invention cannot be achieved. It is better that there is no difference in the YI value, but the lower limit is usually about 0.01.

Here, the difference between the YI values (X ₂ -X ₁ ) is measured as follows.
That is, in the water-soluble film, the YI value (X ₁ ) is measured using a spectrocolorimeter before immersing in the liquid detergent.
Next, the water-soluble film was immersed in a liquid detergent and left at 50 ° C. for 25 days, then the water-soluble film was taken out, and the adhering liquid was removed with a paper cloth (Kimwipe) at 23 ° C. × 50%. After adjusting the humidity under the RH condition, the YI value (X ₂ ) is measured in the same manner as above.
Then, the YI value (X ₁ ) is subtracted from the YI value (X ₂ ) to calculate the difference between the YI values (X ₂ -X ₁ ).

In the present invention, the liquid detergent includes, for example, a detergent containing dyes such as Acid Red 138, Polar Red RLS, Acid Yellow 203, Acid Blue 9, Blue No. 1, Blue No. 205, Green No. 3, and Turquoise P-GR. Specific examples thereof include liquid detergents such as "Perlux BABY" manufactured by Lakma (manufactured on December 14, 2014).

The water-soluble film of the present invention is produced, for example, as follows.
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 heat 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 13 to 45 mPa · s. s, particularly preferably 17 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 13 to 45 mPa · s. s, particularly preferably 17 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 13 to 50 mPa · s. It is preferably 40 mPa · s, particularly preferably 17 to 30 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-based resin, 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 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-based 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 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. In particular, it is preferably 12 to 40 mPa · s, and 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 the vinyl ester compound include vinyl formate, vinyl acetate, trifluoroacetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl laurate, vinyl versatic acid, vinyl palmitate, vinyl stearate and the like. Can be mentioned. Above all, it is preferable to use vinyl acetate as the vinyl ester compound. The vinyl ester compound may be used alone or in combination of two or more.

The modified PVA resin is a method of copolymerizing the vinyl ester compound with an unsaturated monomer copolymerizable with the vinyl ester compound and then saponifying the resin, or a method of post-modifying unmodified PVA. It can be manufactured by such means.

In the present invention, the following unsaturated monomer copolymerizable with the vinyl ester compound may be copolymerized, but in the case of obtaining a modified PVA resin, a modifying group may be 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) acetic acid. Methods for saponifying and decarbonizing a copolymer of vinyl and vinyl ethylene carbonate, (iii) saponifying 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 for producing 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 compound by coexisting an alcohol, an aldehyde, a thiol or the like having a carboxyl group as a chain transfer agent, and then keratinizing the 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 method (I) above 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 ethylenically unsaturated carboxylic acid anhydride (maleic anhydride, itaconic anhydride, etc.) or ethylenically unsaturated monocarboxylic acid ((meth) acrylic acid, crotonic acid, etc.), and theirs. Salt is mentioned. Among them, 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 are preferably used, and further. 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 mixed 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 reactive 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 sulfonic acid or a salt thereof with a vinyl ester compound and then saponifying the sulfonic acid, vinyl sulfonic acid or a salt thereof, 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 include a method for acetoacetic esterification, acetalization, urethanization, etherification, grafting, phosphoric acid esterification, and oxyalkylene formation of the unmodified PVA.

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 an alkyl ester of an ethylenically unsaturated carboxylic acid, an allyl ester of a saturated carboxylic acid, an α-olefin, an alkyl vinyl ether, an alkyl allyl ether, 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.

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. Only one type of plasticizer (B) can be used, or at least two types can be used in combination, but in particular, the toughness of the water-soluble film itself when at least two types are used as a package is used. It is preferable in that.

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. A polyhydric alcohol (b2) having a temperature of 50 ° C. or lower (hereinafter, may be abbreviated as a plasticizer (b2)) is tough during the production of water-soluble films and packages, and packaging for liquid detergents. It is preferable in terms of shape stability over time when it is made into a body.

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 the toughness 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 with 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 can be mentioned.

In the present invention, a plasticizing agent (b3) other than the above-mentioned plasticizing agents (b1) and (b2) can be used in combination, and examples of the plasticizing agent (b3) include trimethylolpropane (58 ° C.) and diethylene glycol. Alcohols such as monomethyl ether, cyclohexanol, carbitol, polypropylene glycol, ethers such as dibutyl ether, carboxylic acids such as stearic acid, oleic acid, linoleic acid, linolenic acid, sorbic acid, citric acid, adipic acid, cyclohexanone, etc. Examples thereof include ketones, monoethanolamines, triethanolamines, ethylenediamines, amines such as imidazole compounds, amino acids such as alanine, 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 preferably 20 parts by weight or more, particularly 25 to 70 parts by weight, and further 30 to 60 parts by weight with respect to 100 parts by weight of the PVA-based resin (A). It is preferably parts by weight, particularly 35 to 50 parts by weight. If the content of the plasticizer (B) is too small, the toughness 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 weight ratio (b1 / b2) of the above-mentioned plasticizer (b1) and plasticizer (b2) is preferably 0.1 to 5, particularly 0.35 to 4.5, and further 0. It is preferably 4 to 4, particularly 0.5 to 3.5, and particularly preferably 0.7 to 3. If the content weight ratio is too small, the water-soluble film tends to be too soft, the sealing strength at low temperature tends to decrease, blocking tends to occur easily, and if it is too large, the water-soluble film tends to be hard. It tends to be too brittle and brittle even in low humidity environments.

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 tends to become brittle even in a low-humidity environment. be. 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 tends to be too soft and blocking is likely to occur. There is.

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 nonionic surfactants include polyoxyethylene nonylphenyl ether, polyoxyethylene octyl nonyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene sorbitan monolaurate, and polyoxyethylene sorbitan monopalmi. Polyoxyethylene alkyl such as tate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyalkylene alkyl ether phosphate ester monoethanolamine salt, polyoxyethylene laurylamino ether, polyoxyethylene stearylamino ether, etc. Amino ether and the like are mentioned, and one kind or two or more kinds are used in combination. 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 polyacrylate, 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. , Fragrance, rust preventive, colorant, bulking agent, defoaming agent, ultraviolet absorber, liquid paraffin, fluorescent whitening agent, bitterness component (for example, denatonium benzoate, etc.) and the like can be contained. 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 sulfites such as sodium sulfite, potassium sulfite, calcium sulfite, and ammonium sulfite, tartrate acid, ascorbic acid, sodium thiosulfite, catechol, and longalit, among which sulfites, 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), preferably a plasticizer (B), and if necessary, a filler (C), a surfactant (D), and the like. Then, 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 melt extrusion method or a casting method can be adopted, and the casting method is preferable in terms of film thickness accuracy.

In the present invention, when the above-mentioned casting 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 preferably a plasticizer (B) and other formulations are further added to disperse the resin composition in water. Obtain a liquid or aqueous solution. Alternatively, water is added to the resin composition containing the PVA-based resin (A), preferably 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 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 tend to occur when the water-soluble film is formed. There is. Furthermore, 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 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.

Alternatively, an applicator can be used to cast an aqueous dispersion or 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 30 to 110 μm, and particularly preferably 45 to 100 μm. If the thickness is too thin, the mechanical strength of the film tends to decrease, and if it is too thick, the dissolution rate in water tends to be slow, and the film forming efficiency also 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 perform uneven processing such as pear-skin pattern (fine uneven pattern), special engraving pattern, and the like.
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.

It is important that the PVA-based film (water-soluble film) thus obtained satisfies the above difference in YI value, and in order to control the difference in YI value within the above range, for example, (1) Unmodified PVA. Examples thereof include a method of increasing the content of the above, (2) a method of not applying high temperature heat treatment, and (3) a combination of these methods. Above all, it is preferable to include the method (1) in that the physical properties of the water-soluble film can be controlled while maintaining the physical properties of the water-soluble film.

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 / day (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 polybropyrene, glass-deposited polyester, or a laminated film thereof, or a split cloth, paper, or non-woven fabric. A laminated film with 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 polybropyrene 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, the film roll is wrapped with a wrapping film of a steam barrier resin, and then a wrapping film made of an aluminum material is further wrapped. As such a film, an aluminum foil, an aluminum foil and a moisture-resistant plastic film are 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 vapor-deposited film and moisture-resistant plastic film (for example) For example, a laminated film of an alumina vapor-deposited polyester film and a polyethylene film), etc., and in the present invention, a laminated film of an aluminum foil and a polyolefin film, a laminated film of an aluminum vapor-deposited film and a polyolefin film is particularly useful, and particularly a stretched polypropylene film / A laminated film having a structure 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, protective pads having core tube through holes are attached to both ends of the film roll directly or after packaging. Can be done.
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, in order to protect the film roll from humidity, a desiccant may be separately enclosed, 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 desiccant, for example, calcium chloride, silica gel, molecular sieves, saccharides, particularly saccharides having high osmotic pressure, desiccants such as water-absorbent resins, or water-absorbing agents are 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, and these hygroscopic agents or water-absorbents can be applied to the above-mentioned moldable materials, polyester films, polyethylene films, polypropylene films, and Teflon ( Registered trademark) Examples include those sandwiched between thermoplastic resin films such as films.
Examples of commercially available sheet-like desiccants are "ID Sheet" manufactured by ID Co., Ltd., "Arrow Sheet" and "Zeo Sheet" manufactured by Shinagawa Kasei Co., Ltd., and "High Sheet Dry" manufactured by High Sheet Industry Co., Ltd. And so on.

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 drug, particularly 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 the drug contained, especially the liquid detergent, 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.

A known method can be adopted when a drug, particularly a liquid detergent, is packaged into a package using the water-soluble film of the present invention. 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.
Carboxyl group-modified PVA (A1): Viscosity of 4% aqueous solution at 20 ° C. 22 mPa · s, average saponification degree 94 mol%, modification amount with maleic acid monomethyl ester 2.0 mol%
Carboxyl group-modified PVA (A2): Viscosity of 4% aqueous solution at 20 ° C. 22 mPa · s, average saponification degree 96 mol%, modification amount by maleic acid monomethyl ester 4.0 mol%
Unmodified PVA (A3): 4% aqueous solution viscosity at 20 ° C., 18 mPa · s, average saponification degree 88 mol%

The following plasticizers were prepared.
・ Sorbitol (b1)
・ Glycerin (b2)
-Trimethylolpropane (b3)

< Reference example 1>
As the PVA-based resin (A), 90 parts of a carboxyl group-modified PVA (A1) having a 4% aqueous solution viscosity at 20 ° C. of 22 mPa · s, an average saponification degree of 94 mol%, and a modification amount of 2.0 mol% with maleic acid monomethyl ester. , 10 parts of unmodified PVA (A3) with a 4% aqueous solution viscosity of 18 mPa · s at 20 ° C. and an average saponification degree of 88 mol%, and 10 parts of trimethylolpropane (TMP) (b3) as a plasticizer (B). 16 copies of glycerin (GLY) (b2),
Eight parts of starch (average particle size 20 μm) as the filler (C), two parts of the polyoxyalkylene alkyl ether phosphoric acid ester monoethanolamine salt as the surfactant (D), and water are mixed and dissolved. , PVA aqueous solution (solid content concentration 25%) in which 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 rate of 0.350 m / min, and dried to obtain a PVA-based film (water-soluble film) having a thickness of 87 μm. Obtained.

The PVA film (water-soluble film) obtained above was measured and evaluated as follows.

[YI value (X ₁ ) and (X ₂ ) of water-soluble film]
In the water-soluble film obtained above, the YI value was measured using an ultraviolet-visible near-infrared photometer (“UV-3100PC” manufactured by Shimadzu Corporation) before immersing in a liquid detergent. Was taken as the YI value (X ₁ ).
Next, the water-soluble film is immersed in a liquid detergent and left in the liquid detergent at 50 ° C. for 25 days, then the water-soluble film is taken out, the adhering liquid is removed with a paper cloth (Kimwipe), and 23 ° C. × After adjusting the humidity at 50% RH, the YI value was measured in the same manner as above, and this was taken as the YI value (X ₂ ).
Then, the YI value (X ₁ ) was subtracted from the above YI value (X ₂ ) to calculate the difference between the YI values (X ₂ -X ₁ ).
The liquid detergent used above was a liquid detergent of "Perlux BABY" manufactured by Lakma (manufactured on December 14, 2014), and the YI value of the 5% solution was 57.

[8% tensile modulus of water-soluble film]
Using the PVA-based film obtained above, the tensile strength was measured according to JIS K 7127 (1999). That is, after leaving the PVA-based film under the conditions of 23 ° C. and 50% RH humidity control for 24 hours before the measurement, the PVA-based film was subjected to a tensile speed of 200 mm / using the Autograph AG-X Plus manufactured by Shimadzu Corporation. The elastic modulus was measured in minutes, and the measured value at the elongation of 8% was used (film width 15 mm, chuck distance 50 mm).

<Examples 1 to 3 , Comparative Example 1>
In Reference Example 1, the same procedure was performed except that the changes were made as shown in Table 1, and the PVA-based film (PVA-based film)
Water-soluble film) was obtained.
The obtained PVA-based films (water-soluble films) of Examples 1 to 3 and Comparative Example 1 were evaluated in the same manner as in Reference Example 1.

The evaluation results of Examples and Comparative Examples are shown in Table 1 below.

From the results in Table 1 above, in the above-mentioned Examples, the difference in YI value is 2 or less, the color change is small even with time, and the package is good, and the film strength is also improved. It was excellent. On the other hand, in the comparative example, the difference in YI value was large and the change in color was large. The film strength was also inferior. From these results, it can be seen that when the water-soluble film of the example is used and, for example, a liquid detergent is packaged to form a package, there is little change over time and a good package is obtained.

The water-soluble film of the present invention is a water-soluble film having little change in color over time even when a liquid such as a liquid detergent is packaged into a package, and has an excellent effect on film strength. It can be used for various packaging applications, and is particularly useful for unit packaging applications such as chemicals, especially liquid detergents.

Claims (7)

A water-soluble film containing a polyvinyl alcohol-based resin (A) and a plasticizer (B).
The polyvinyl alcohol-based resin (A) contains an anionic group-modified polyvinyl alcohol-based resin (a1) and an unmodified polyvinyl alcohol (a2).
Anion-modified polyvinyl alcohol-based resin (a1) and unmodified polyvinyl alcohol (a1)
The weight ratio (a1) / (a2) of 2) is 80 / 20-60 / 40, and
The plasticizer (B) contains a polyhydric alcohol (b1) having a melting point of 80 ° C. or higher and a polyhydric alcohol (b2) having a melting point of 50 ° C. or lower.
Multivalent alcohol (b1) having a melting point of 80 ° C. or higher and polyhydric alcohol having a melting point of 50 ° C. or lower
The content weight ratio (b1) / (b2) of all (b2) is 0.35 to 5.
The YI value (X2) of the film after the water-soluble film was immersed in a liquid detergent having a YI value of 40 to 70 in a 5 wt% aqueous solution and left at 50 ° C. for 25 days, and the YI of the film before immersion. A water-soluble film characterized in that the difference (X2-X1) of the value (X1) is 2 or less. The content of the plasticizer (B) is 2 with respect to 100 parts by weight of the polyvinyl alcohol-based resin (A).
The water-soluble film according to claim 1, wherein the amount is 0 parts by weight or more. The water-soluble film according to claim 1 or 2, 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 3, wherein the unmodified polyvinyl alcohol (a2) has a viscosity of a 4% by weight aqueous solution of 12 to 50 mPa · s. The water-soluble film according to any one of claims 1 to 4, which is used for drug packaging. A drug package comprising the liquid detergent packaged in the water-soluble film according to any one of claims 1 to 5. 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.