JP6729279B2 - Water-soluble film and drug package - Google Patents

Description

The present invention relates to a water-soluble film (hereinafter, also 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 water-soluble film and the water-soluble film having excellent solubility in water, particularly cold water solubility, no significant difference in solubility in hard water or soft water, and solubility not affected by the region of use are used. The present invention relates to a drug package.

A PVA-based film is a film made of a water-soluble PVA-based resin that is a thermoplastic resin, and a hydrophobic film that is often used as a packaging film such as a polyethylene terephthalate film or a polyolefin film is a film. The physical properties and the feeling of touch are greatly different.

Further, conventionally, it has been proposed to make use of the water solubility of PVA-based resin to package various chemicals such as pesticides and detergents in a bag made of a PVA-based resin film (unit packaging), which has a wide range of uses. It is used.

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

JP, 2001-329130, A JP, 2004-161823, A

However, the water-soluble films disclosed in Patent Documents 1 and 2 above are excellent in water solubility and can be used as a drug package in which a liquid detergent or the like is packaged. The difference in solubility due to the above was not taken into consideration. In a word, water has soft water and hard water, and its solubility is different. For example, since the water-soluble film is dissolved in various areas such as soft water and hard water to dissolve the water-soluble film, it depends on the usage area. Was required to be changed appropriately, and further improvement was required in terms of production management and production efficiency.

Therefore, in the present invention, under such a background, the solubility in water, particularly the cold water solubility is excellent, there is no great difference in the solubility in hard water or soft water, and the solubility not affected by the region of use. It is an object of the present invention to provide a water-soluble film having the above and a drug package in which various drugs are packaged in the water-soluble film.

However, as a result of diligent research conducted by the present inventors in view of such circumstances, in a water-soluble film containing a PVA-based resin, in consideration of the influence of water that dissolves the water-soluble film, a dissolution time at 5° C. in hard water is considered. And a water-soluble film with a small difference in dissolution time at 5°C in soft water have excellent solubility in water, especially in cold water, and there is no significant difference in solubility between hard water and soft water. The present invention has been completed by finding that the water-soluble film has a solubility that is not affected by the usage area.

That is, the gist of the present invention relates to a water-soluble film containing the PVA-based resin (A), which satisfies the following [1] to [3].
[1] The dissolution time (T1) at 5° C. in hard water having a hardness of 120 mg/L or more specified by WHO (World Health Organization) standard is 180 seconds or less.
[2] The dissolution time (T2) at 5° C. in soft water having a hardness of less than 120 mg/L specified by WHO (World Health Organization) standards is 120 seconds or less.
[3] The difference (T1-T2) between the dissolution time (T1) and the dissolution time (T2) is 80 seconds or less.

Furthermore, the present invention also provides a medicine package comprising the water-soluble film.

In the present invention, "hard water" and "soft water" comply with the standards of WHO (World Health Organization), and the numerical value representing the amount of calcium and magnesium dissolved in 1000 mL of water is called "hardness". Water having a hardness of less than 120 mg/L is called "soft water", and water having a hardness of 120 mg/L or more is called "hard water".

The term "dissolution time at 5°C" means that a film sample is cut into a size of 3 cm x 5 cm, fixed on a jig, and then water (1 liter) is put into a 1 liter beaker and stirred by a stirrer ( The time (seconds) until the film is dissolved by immersing the film fixed on the jig in the water while maintaining the water temperature at 5° C. while the rotor length is 3 cm and the rotation speed is 200 to 300 rpm. Here, the term "dissolution" means that such a film becomes invisible, and the case where insoluble fine particles having a diameter of 1 mm or less are dispersed is also included in the meaning of "dissolution" in the present invention.

The water-soluble film of the present invention is excellent in solubility in water, particularly in cold water, has no great difference in solubility in hard water or soft water, and has solubility that is not affected by the region of use. Therefore, it can be used for various packaging applications, and is particularly useful for unit packaging applications for medicines and the like.

Hereinafter, the present invention will be specifically described.
The water-soluble film of the present invention is a water-soluble film containing the PVA-based resin (A) and satisfies the following [1] to [3].
[1] Dissolution time (T1) at 5° C. in hard water having a hardness of 120 mg/L or more defined by WHO (World Health Organization) is 180 seconds or less, preferably 170 seconds or less, and particularly preferably 160 seconds or less. To be.
[2] Dissolution time (T2) at 5° C. in soft water having a hardness of less than 120 mg/L specified by WHO (World Health Organization) is 120 seconds or less, preferably 110 seconds or less, and particularly preferably 100 seconds or less. To be.
[3] The difference (T1-T2) between the dissolution time (T1) and the dissolution time (T2) is 80 seconds or less, preferably 75 seconds or less, and particularly preferably 70 seconds or less.

In the present invention, if the dissolution time (T1) of the above [1] is too long, dissolution of the drug in water will be delayed in the case of a drug package. The lower limit of the dissolution time (T1) is usually 20 seconds, and if it is too short, the package tends to be broken due to dew condensation or the like in the case of the chemical detergent package.

In the present invention, if the dissolution time (T2) of the above [2] is too long, the dissolution of the drug in water will be delayed in the case of a drug package. The lower limit of the dissolution time (T2) is usually 10 seconds, and if it is too short, the package tends to break due to dew condensation or the like when the package is formed into a chemical detergent.

In the present invention, when the difference (T1-T2) between the dissolution time (T1) and the dissolution time (T2) in [3] above is too large, the time taken for the drug to dissolve depends on the region of use in the case of a drug package. It will be changed, and the washability will be different. It should be noted that there is usually no problem that the difference (T1−T2) in the dissolution time is too small, but if the difference (T1−T2) becomes large as a negative value, there is a possibility that the washability will be different as in the above case.

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 resins.

The average degree of saponification 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%, and particularly It is preferably 90 to 97 mol %. When unmodified PVA is used as the PVA-based resin (A), its 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), its average saponification degree is preferably 80 mol% or more, particularly 85 to 99.9 mol%, and further 90 It is preferably ˜98 mol %. Furthermore, when an anionic group-modified PVA-based resin is used as the PVA-based resin (A), the average degree of saponification is preferably 85 mol% or more, and particularly 88 to 99 mol%, It is preferably 90 to 97 mol %. When the average degree of saponification is too small, the solubility of the water-soluble film in water tends to decrease with time depending on the pH of the drug to be packaged. If the average degree of saponification 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 be generally represented by a water-soluble viscosity, and the viscosity of a 4% by weight aqueous solution at 20° C. is preferably 5 to 50 mPa·s, and further 13 to 45 mPa·s. s, particularly 17 to 40 mPa·s is preferable. When unmodified PVA is used as the PVA-based resin (A), the 4% by weight aqueous solution viscosity of the unmodified PVA at 20° C. is preferably 5 to 50 mPa·s, and further 13 to 45 mPa·s. s, particularly 17 to 40 mPa·s is preferable. When a modified PVA-based resin is used as the PVA-based resin (A), the 4% by weight aqueous solution viscosity of the modified PVA-based resin at 20° C. is preferably 5 to 50 mPa·s, more preferably 13 to It is preferably 40 mPa·s, particularly 17 to 30 mPa·s. If the viscosity is too low, the mechanical strength of the water-soluble film as a packaging material tends to decrease, while if it is too high, the aqueous solution viscosity during film formation tends to be high and the productivity tends to decrease.

The average degree of saponification is measured according to JIS K 6726 3.5, and the viscosity of a 4% by weight 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, nonionic group-modified PVA-based resin, and the like. Above all, it is preferable to use the anionic group-modified PVA-based resin from the viewpoint of solubility in water. Examples of the type of anionic group include a carboxyl group, a sulfonic acid group, and a phosphoric acid group, but from the viewpoint of chemical resistance and stability over time, a carboxyl group, a sulfonic acid group, and particularly a carboxyl group is preferable. ..

In the present invention, the amount of modification 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 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, or the biodegradability tends to decrease, and it causes blocking. It tends to be easy and the practicality is reduced.

In the present invention, the above PVA-based resin (A) can be used alone, or an unmodified PVA and a modified PVA-based resin can be used in combination, and further, saponification degree, viscosity, modified species, modified amount. It is also possible to use two or more of the above, etc. Above all, in the present invention, the PVA-based resin (A) preferably contains a modified PVA-based resin. In particular, it is preferable to contain the anionic group-modified PVA-based resin, or to contain the anionic group-modified PVA-based resin and the unmodified PVA, and particularly to contain the anionic group-modified PVA-based resin and the unmodified PVA. It 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 preferred. If the content ratio 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 4% by weight aqueous solution viscosity at 20° C. of 5 to 50 mPa·s, and more preferably 8 to 45 mPa·s. It is particularly preferably 12 to 40 mPa·s, and particularly preferably 15 to 35 mPa·s. If the viscosity is too low, the mechanical strength of the water-soluble film as a packaging material tends to decrease, while if it is too high, the aqueous solution viscosity 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.

The unmodified PVA can be produced by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester compound.

Examples of such vinyl ester compounds include vinyl formate, vinyl acetate, vinyl trifluoroacetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl laurate, vinyl versatate, vinyl palmitate, vinyl stearate and the like. Can be mentioned. Of these, vinyl acetate is preferably used as the vinyl ester compound. The vinyl ester compounds may be used alone or in combination of two or more.

The modified PVA-based resin is a method of copolymerizing the vinyl ester-based compound and an unsaturated monomer copolymerizable with the vinyl ester-based compound and then saponifying, or a method of post-modifying the unmodified PVA. And the like.

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 is used as the following monomer. It is necessary to copolymerize the unsaturated monomer which it has. As the unsaturated monomer, for example, ethylene, propylene, isobutylene, α-octene, α-dodecene, olefins such as α-octadecene, 3-butene-1-ol, 4-penten-1-ol, 5- Derivatives of hydroxy group-containing α-olefins such as hexen-1-ol and 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. Examples thereof include salts, monoesters, amides such as dialkyl esters, diacetone acrylamide, acrylamide, and methacrylamide, olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid, and salts thereof. These can be used alone or in combination of two or more. The content of the copolymerizable monomer is usually 10 mol% or less.

The modified PVA-based resin also has a primary hydroxyl group in its side chain, and for example, the number of primary hydroxyl groups is usually 1 to 5, preferably 1 to 2, and particularly preferably 1. To be 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 its side chain and a PVA-based resin having a hydroxyalkyl group in its side chain. The PVA-based resin having a 1,2-diol structural unit in the side chain is, for example, (i) a method of saponifying a copolymer of vinyl acetate and 3,4-diacetoxy-1-butene, (ii) acetic acid. A method of saponifying and decarboxylating a copolymer of vinyl and vinyl ethylene carbonate, (iii) saponifying and decarboxylating a copolymer of vinyl acetate and 2,2-dialkyl-4-vinyl-1,3-dioxolane. It can be produced by a ketalization method, (iv) a method of saponifying a copolymer of vinyl acetate and glycerin monoallyl ether, or the like.

As a polymerization method for producing the PVA-based resin (A), for example, known polymerization methods such as a solution polymerization method, an emulsion polymerization method and a suspension polymerization method can be arbitrarily used, but usually methanol, ethanol or isopropyl is used. It is carried out by a solution polymerization method using a lower alcohol such as alcohol as a solvent. In the case of a modified PVA-based resin, as a method of charging a monomer in such solution polymerization, first, the total amount of the vinyl ester-based compound and, for example, a part of the unsaturated monomer having a carboxyl group described above are charged and polymerization is performed. It is possible to use any method such as a method of starting and adding the remaining unsaturated monomers continuously or in a divided manner during the polymerization period, a method of batch-charging the unsaturated monomer having a carboxyl group described above. it can.

As the polymerization catalyst, a known polymerization catalyst such as an azo catalyst such as azobisisobutyronitrile or a peroxide catalyst such as acetyl peroxide, benzoyl peroxide or lauroyl peroxide is appropriately selected according to the polymerization method. be able to. The polymerization reaction temperature 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 ethylate, or potassium methylate, or an alkali catalyst such as alcoholate can be used. It is also possible to use a catalyst. The amount of the saponification catalyst used is preferably 1 to 100 mmole equivalent 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) unsaturated monomer having a carboxyl group and a vinyl ester-based compound are copolymerized and then saponified. And (II) a method in which an alcohol, aldehyde, thiol or the like having a carboxyl group coexists as a chain transfer agent to polymerize the vinyl ester compound and then saponify.

As the vinyl ester compound in the method (I) or (II), the above 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 ethylenically unsaturated dicarboxylic acid (maleic acid, fumaric acid, itaconic acid, etc.), or ethylenically unsaturated dicarboxylic acid monoester (maleic acid). 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 Needs to be converted into a carboxyl group by hydrolysis during saponification of the copolymer. ], or monomers such as ethylenically unsaturated carboxylic acid anhydrides (maleic anhydride, itaconic anhydride, etc.), ethylenically unsaturated monocarboxylic acids ((meth)acrylic acid, crotonic acid, etc.), and those Examples include salt. Among them, maleic acid, maleic acid monoalkyl ester, maleic acid dialkyl ester, maleic acid salt, maleic anhydride, itaconic acid, itaconic acid monoalkyl ester, itaconic acid dialkyl ester, it is preferable to use (meth) acrylic acid, and the like. It is preferable to use maleic acid, maleic acid monoalkyl ester, maleic acid dialkyl ester, maleic acid salt, maleic anhydride, especially 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 effective, and examples thereof include compounds represented by the following general formulas (1) to (3).

Moreover, the salt of the compound represented by the said General formula (1)-(3) is also mentioned. Specific examples include mercaptoacetate, 2-mercaptopropionate, 3-mercaptopropionate, and 2-mercaptostearate. These compounds may be used alone or in combination of two or more.

Further, the method for producing the carboxyl group-modified PVA-based resin is not limited to the above-mentioned method, and for example, a PVA-based resin (partially saponified product or fully saponified product) with a hydroxyl group such as dicarboxylic acid, aldehyde carboxylic acid, or hydroxycarboxylic acid A method of post-reacting a carboxyl group-containing compound having a reactive functional group can also be carried out.

When using a sulfonic acid-modified PVA-based resin modified with a sulfonic acid group, for example, vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, etc. Of a sulfonic acid or a salt thereof, which is copolymerized with a vinyl ester compound, and then saponified, vinyl sulfonic acid or a salt thereof, 2-acrylamido-2-methylpropane sulfonic acid or a salt thereof, etc. It can be produced by a method such as Michael addition to a resin.

On the other hand, examples of the method of post-modifying the unmodified PVA include a method of acetoacetic acid esterification, acetalization, urethanization, etherification, grafting, phosphoric acid esterification, and oxyalkyleneization of the unmodified PVA.

Incidentally, in addition to the above-mentioned unsaturated monomer having a carboxyl group, a vinyl ester compound, other general monomers may be contained in a range not impairing water solubility and 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 also (meth)acrylamide, (meth)acrylonitrile, styrene, 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 add the plasticizer (B) to the PVA-based resin (A) from the viewpoint of giving flexibility to the film in the case of a drug package. The plasticizer (B) may be used alone or in combination of at least two kinds, but in particular, when at least two kinds are used in combination, the strength of the film itself when used as a package is pointed out. Is preferred.

One type of such a plasticizer (B) is a polyhydric alcohol (b1) having a melting point of 80° C. or higher (hereinafter sometimes abbreviated as a plasticizer (b1)), and the other type has a melting point. A polyhydric alcohol (b2) having a temperature of 50° C. or lower (hereinafter sometimes abbreviated as a plasticizer (b2)), which is toughness during film production and packaging production, and a packaging body for a liquid detergent. It is preferable in terms of shape stability over time when the above is performed.

As the polyhydric alcohol (b1) having a melting point of 80° C. or higher, many sugar alcohols, monosaccharides and polysaccharides can be applied, but among them, for example, salicyl alcohol (83° C.) and catechol (105° C.). ), resorcinol (110° C.), hydroquinone (172° C.), bisphenol A (158° C.), bisphenol F (162° C.), neopentyl glycol (127° C.) and other dihydric alcohols, phloroglucinol (218° C.), etc. Trihydric alcohols such as trihydric alcohol, erythritol (121°C), threitol (88°C), pentaerythritol (260°C), xylitol (92°C), arabitol (103°C), fucitol (153°C), glucose (146°C). ), pentavalent alcohols such as fructose (104°C), mannitol (166°C), sorbitol (95°C), hexahydric alcohols such as inositol (225°C), lactitol (146°C), sucrose (186°C), trehalose. Examples thereof include octahydric alcohols such as (97° C.) and alcohols having 9 or more valences such as maltitol (145° C.). These can be used alone or in combination of two or more. In addition, the above () shows the melting point of each compound.
Among them, those having a melting point of 85° C. or higher, particularly 90° C. or higher are preferable in terms of 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, among the plasticizer (b1), it is preferable that the number of hydroxyl groups in one molecule is 4 or more from the viewpoint of compatibility with the PVA-based resin, further preferably 5 to 10, particularly preferably Is 6 to 8, and specific examples thereof include sorbitol, sucrose, trehalose and the like.

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, from the viewpoint of the toughness of the film. Specific examples thereof include sorbitol and sucrose.

On the other hand, as the polyhydric alcohol (b2) having a melting point of 50° C. or lower, most of aliphatic alcohols can be applied, and, for example, preferably ethylene glycol (-13° C.), diethylene glycol (-11° C.), 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 alcohol such as polyethylene glycol having a molecular weight of 2000 or less, glycerin (18° C.), diglycerin, triethanolamine (21° C.) or more Examples include alcohol. From the viewpoint of flexibility of the water-soluble film, those having a melting point of 30° C. or lower, particularly 20° C. or lower are preferable. The lower limit of the melting point is usually -80°C, preferably -10°C, particularly preferably 0°C. These can be used alone or in combination of two or more. In addition, the melting point of each compound is shown in the said ().

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

Further, in the present invention, the plasticizer (b2) preferably has a molecular weight of 100 or less, more preferably 50 to 100, particularly preferably 60 to 95, from the viewpoint of easy control of flexibility. Specific examples include glycerin and the like.

In the present invention, a plasticizer (b3) other than the above plasticizers (b1) and (b2) may be used in combination. 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, carboxylic acids such as stearic acid, oleic acid, linoleic acid, linolenic acid, sorbic acid, citric acid and adipic acid, cyclohexanone, etc. And amines such as monoethanolamine, triethanolamine, ethylenediamine, imidazole compound, and 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 25 parts by weight or more based on 100 parts by weight of the PVA-based resin (A), particularly 27 to 70 parts by weight, further 30 to 60 parts by weight. It is preferably in the range of 35 parts by weight, especially 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 with time when a liquid such as a liquid detergent is packaged to form a package. If the amount is too large, the mechanical strength tends to decrease.

The content weight ratio (b1/b2) of the plasticizer (b1) and the plasticizer (b2) is preferably 0.1 to 5, more preferably 0.35 to 4.5, particularly It is preferably 0.4 to 4, more preferably 0.5 to 3.5, and particularly preferably 0.7 to 3. If the content ratio is too small, the water-soluble film tends to be too soft and blocking tends to occur. If it is too large, the water-soluble film tends to be too hard and the water-soluble film tends to be brittle even in a low humidity environment.

The content of the plasticizer (b1) and the plasticizer (b2) is 5 to 40 parts by weight of the plasticizer (b1), and further 8 to 10 parts by weight of the PVA-based resin (A). It is preferably 30 parts by weight, particularly 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.

When the amount of the plasticizer (b1) is too small, the water-soluble film tends to be too soft and blocking tends to occur. When the amount is too large, the water-soluble film tends to be too hard and the water-soluble film tends to become brittle even in a low humidity environment. is there. 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 tends to occur. There is.

Further, the total amount of the plasticizer (b1) and the plasticizer (b2) is preferably 70% by weight or more, further 80% by weight or more, and particularly 87% by weight or more, based on the entire plasticizer (B). In particular, it is preferably 90% by weight or more, more preferably 95% by weight or more. It is particularly preferable that the entire plasticizer (B) consists of the 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, if necessary, a filler (C), a surfactant (D) and the like can be further contained.

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

The inorganic filler preferably has an average particle size of 1 to 10 μm. If the average particle size is too small, the effect of dispersibility of the film in water tends to be small, and if it is too large, the film is There is a tendency that when it is stretched during molding, it becomes a pinhole or its appearance deteriorates.

Specific examples of the inorganic filler include, for example, talc, clay, silicon dioxide, diatomaceous earth, 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, dawsonite, 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, and further preferably 0.5 to 5 μm. is there. If the average particle size is too small, the cost tends to increase, and if it is too large, the water-soluble film tends to become pinholes when stretched during the molding process.

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 polymethyl (meth)acrylate resin, polystyrene resin, or starch is 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, potato starch, sweet potato starch, wheat starch, kissava starch, sago starch, tapioca starch, sorghum starch, rice starch, bean starch, kudzu starch, bracken starch, lotus starch, Hishi starch, etc.), physically modified starch (α-starch, fractionated amylose, heat-moisture treated starch, etc.), enzymatically modified starch (hydrolyzed dextrin, enzymatically degraded dextrin, amylose, etc.), chemically degraded starch (acid-treated starch, hypochlorous starch, etc.) Chloric acid-oxidized starch, dialdehyde starch, etc.), chemically modified starch derivatives (esterified starch, etherified starch, cationized starch, cross-linked starch, etc.) and the like. Among them, raw starch, particularly corn starch and rice starch, are preferably used 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 with respect to 100 parts by weight of the PVA-based resin (A). It is preferably part. If the content is too small, the blocking resistance tends to decrease, and if it is too large, the film tends to become pinholes when stretched during molding.

The surfactant (D) used in the present invention is contained for the purpose of improving the releasability from the cast surface during the production of the water-soluble film, and is usually a nonionic surfactant, a cationic surfactant, an anion. Surfactants may be mentioned. Examples of nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl nonyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmi Polyoxyethylene alkyl such as tate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyalkylene alkyl ether phosphate ester monoethanolamine salt, polyoxyethylene lauryl amino ether, polyoxyethylene stearyl amino ether Amino ether and the like can be mentioned, and they can be used alone or in combination of two or more. Among them, polyoxyalkylene alkyl ether phosphate ester monoethanolamine salt and polyoxyethylene lauryl amino 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). It is particularly preferably 0.5 to 2 parts by weight. If the content is too small, the peelability between the cast surface of the film-forming apparatus and the water-soluble film that has been formed tends to decrease, and productivity tends to decrease, and if the content is too large, the water-soluble film is used as a package. There is a tendency to cause inconvenience such as a decrease in adhesive strength at the time of heat sealing to be performed.

In the present invention, other water-soluble polymers (for example, sodium polyacrylate, polyethylene oxide, polyvinylpyrrolidone, dextrin, chitosan, chitin, methylcellulose, hydroxyethylcellulose, etc.) and within the range that does not impair the object of the invention, and It is also possible to add a fragrance, a rust preventive, a coloring agent, a bulking agent, an antifoaming agent, an ultraviolet absorber, liquid paraffins, a bitter component (for example, denatonium benzoate). 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. Such antioxidants include, for example, sodium sulfite, potassium sulfite, calcium sulfite, sulfite salts such as ammonium sulfite, tartaric acid, ascorbic acid, sodium thiosulfate, catechol, rongalite, and the like, among which sulfite salts, particularly sodium sulfite. Is preferred. 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, based on 100 parts by weight of the PVA-based resin (A).

In the present invention, a resin composition containing the PVA-based resin (A) as described above, preferably a plasticizer (B), and optionally a filler (C) and a surfactant (D). 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. In forming such a film, for example, a method such as a melt extrusion method or a casting method can be adopted, and the casting method is preferable from the viewpoint of film thickness accuracy.

In the present invention, the casting method is carried out, for example, as follows.
As a dissolution method, usually, room temperature dissolution, high temperature dissolution, pressure dissolution and the like are adopted, and among them, high temperature dissolution and pressure dissolution are preferable from the viewpoint of less undissolved matter and excellent productivity.

The melting temperature is usually 80 to 100°C, preferably 90 to 100°C in the case of high temperature melting, and is 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, more preferably 3 to 10 hours. If the dissolution time is too short, undissolved substances tend to remain, and if it is too long, productivity tends to decrease.

In the melting step, examples of the stirring blades include paddles, full zones, Maxblends, twisters, anchors, ribbons and propellers.
Further, after the dissolution, the resulting PVA-based resin aqueous solution is subjected to defoaming treatment. Examples of the defoaming method include stationary defoaming, vacuum defoaming, and biaxial extrusion defoaming. To be Of these, stationary defoaming and biaxial extrusion defoaming are preferable.
The stationary defoaming temperature 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, the above-mentioned water is added to the PVA-based resin (A) (powder) to prepare a PVA-based resin aqueous solution, and preferably a plasticizer (B) and other compounds are added to the resin composition to prepare a resin composition. An aqueous dispersion or solution is obtained. Alternatively, water is added to the resin composition containing the PVA-based resin (A), preferably the plasticizer (B) and various compounds to obtain an aqueous dispersion or aqueous solution of the resin composition. The solid content concentration of such an aqueous dispersion or aqueous solution of the resin composition is preferably 10 to 50% by weight, particularly preferably 15 to 40% by weight, and further 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, or a die line occurs during the formation of the water-soluble film. Tend to do. Furthermore, if the temperature of the metal surface of the endless belt or the drum roll is too low, it tends to take time to dry, and if it is too high, foaming tends to occur during film formation.

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

The temperature of the discharge part in the aqueous dispersion or aqueous solution of the PVA-based resin composition is preferably 60 to 98°C, and 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 it is too high, foaming or the like tends to occur.

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

It is also possible to obtain a PVA-based film by casting an aqueous dispersion or aqueous solution of the resin composition on a plastic substrate such as a polyethylene terephthalate film or a polyethylene film or a metal substrate using an applicator and drying.

The thickness of the PVA-based film is appropriately selected depending on the application etc., 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 PVA 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 application etc., 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, slack and control of the film thickness tend to be difficult.

The length of the PVA-based film is appropriately selected depending on the application etc., but is preferably 500 to 20,000 m, more preferably 800 to 15,000 m, and particularly preferably 1,000 to 10,000 m. If the length is too short, it tends to be time-consuming to switch the film, and if it is too long, the appearance may be poor due to winding tightness and the weight may 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, embossed pattern or satin finish on one or both sides of the film. It is also preferable to give unevenness such as a pattern or a special engraving pattern.

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 concavo-convex 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, from the viewpoint 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 water content can be adjusted by appropriately setting the drying conditions and the humidity control conditions.
The water content is measured according to JIS K 67263.4, and the value of the volatile component obtained is taken 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 for the PVA-based film (water-soluble film) thus obtained to satisfy the above requirements [1] to [3]. To control such solubility in the above range, for example, (1) Examples thereof include a method of increasing the blending ratio of the modified PVA, (2) a method of reducing the modification amount of the anionic group of the anionic group-modified PVA-based resin, and (3) a combination of these methods. Above all, the method (1) is preferable because the above properties can be controlled while maintaining the 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 it is preferably wound around a core tube (S2) having a length corresponding to the 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 core tube (S1) projects from the end of the film roll by 1 to 50 cm.

The core tube (S2) has a cylindrical shape, and the material thereof can be appropriately selected from paper, metal, plastic, etc., but is preferably paper from the viewpoint of weight saving 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 equal to or longer than the PVA film width of the product, and is preferably equal to 50 cm longer.

When wound on the core tube (S2), the PVA-based film is slit into a desired width.
When making such a slit, a shear blade, a leather blade, or the like is used for slitting, but it is preferable to slit with a shear blade in terms of the smoothness of the slit cross section.

In the present invention, the obtained film roll is wrapped with a packaging film of a water vapor barrier resin, and the film is not particularly limited, but the water vapor permeability is 10 g/m ² /day (according to JIS Z 0208). (Measurement) The following can be used. Specific examples include, for example, high-density polyethylene, low-density polyethylene, polypropylene, polyester, polyvinylidene chloride-coated polypropylene, glass-deposited polyester, and other single-layer films, or laminated films of these, or split cloth, paper, non-woven fabric. And a laminated film thereof. 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.

Such a film is also preferably subjected to an antistatic treatment from the viewpoint of preventing foreign matter from entering, and the antistatic agent may be kneaded into the film or may be coated on the surface. In the case of kneading, about 0.01 to 5% by weight of the resin is used, and in the case of surface coating, about 0.01 to 1 g/m ^{2 of} an antistatic agent 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 packaging film of a water vapor barrier resin, and then a packaging film made of an aluminum material is further wrapped. Examples of such a film include an aluminum foil, a laminate of an aluminum foil and a moisture resistant plastic film. Film (for example, laminated film of aluminum foil and polyethylene film), laminated film of aluminum vapor deposition film and moisture resistant plastic film (for example, laminated film of aluminum vapor deposited polyester film and polyethylene film), laminated film of alumina vapor 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 mentioned, 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 are particularly useful, and particularly a stretched polypropylene film/ A laminated film having a constitution of polyethylene film/aluminum foil/polyethylene film, a laminated film having a constitution of stretched polypropylene film/low density polyethylene film/aluminum foil, and the like are useful.
For packaging, the inner packaging film of water vapor barrier resin and the outer packaging film made of an aluminum material may be sequentially packaged, and the extra portion in the width direction may be pushed into the core tube.

In the film roll of the present invention, in order to prevent foreign matters such as scratches and dust on the ends from adhering to the film roll directly or after packaging with a packaging film, core tube through holes are provided at both ends of the film roll. A protective pad can be attached.
As 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 foam, woven fabric, and non-woven fabric. In addition, a desiccant may be separately enclosed in order to protect the film roll from humidity, or it may be laminated or mixed in the protective pad.
The material of the protective pad is advantageously plastic, 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 high osmotic pressure saccharides, desiccants such as water-absorbent resin or water-absorbing agent natural celluloses, synthetic celluloses, A hygroscopic layer obtained by dispersing, impregnating, coating and drying in a moldable material such as glass cloth or non-woven fabric, or the above-mentioned moldable material or polyester film, polyethylene film, polypropylene film, Teflon Examples include sandwiched between thermoplastic resin films such as (registered trademark) films.
Examples of commercially available sheet desiccants include "IDY SHEET" manufactured by ID Co., Ltd., "Arrow Sheet", "Zeo Sheet" manufactured by Shinagawa Kasei Co., Ltd., and "HISHEET DRY" manufactured by High Sheet Industry Co., Ltd. Etc.

The film roll packaged by such means is supported by providing brackets (supporting plates) on both end protrusions of the core tube or by mounting the both end protrusions on a gantry so that the film roll is kept in the air without being grounded. Storage and transportation are preferably performed in a floating state. Brackets are used when the film width is relatively small, and pedestals 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 four sides of the bracket are larger than the diameter of the film roll.

Then, a pair of brackets are vertically arranged and fitted to the core tube projecting portions at both ends of the film roll so as to face each other, and are fitted to the film roll. For the fitting, a hollow hole slightly larger than the core tube diameter may be provided in the central portion of the bracket, or a U-shaped hollow may be formed from the upper portion to the central portion of the bracket so that the core tube can be easily inserted.

The film roll supported by the brackets is stored in a carton such as a cardboard box for storage and transportation.However, when using a rectangular bracket to facilitate the storage work, it is necessary to cut off the four corners. preferable.
In addition, it is advantageous to fix the pair of brackets with a binding tape so that they do not wobble. At that time, the side surface (thickness portion) of the bracket has the same width as the tape width so that the tape does not move or loosen. It is also practical to place a groove to prevent tape misalignment.

When storing or transporting the packaged film roll, it is desirable to avoid extreme high and low temperatures, 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 the like, and is particularly useful for unit packaging applications for drugs and the like. The drug is not particularly limited and may be alkaline, neutral or acidic, and the drug may have any shape such as granules, tablets, powders, powders, liquids, etc. Agents for use in solution or dispersion are preferred, especially 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 from 1 to 10% by weight, more preferably from 0.1 to 7% by weight, and the film is excellent in water solubility without gelation or insolubilization.
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 is one in which a drug, especially a liquid detergent, is enclosed 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 water-soluble film package is usually 10 to 120 μm, preferably 15 to 110 μm, and more preferably 20 to 100 μm. The amount of the contained liquid detergent is usually 5 to 50 mL, preferably 10 to 40 mL.

The surface of the drug package of the present invention is usually smooth. However, from the viewpoints of blocking resistance, slipperiness during processing, reduction of adhesion between products (packaging bodies), and appearance, the outer surface of the packaging body (water-soluble film) has an embossed pattern, a fine uneven pattern, a special engraving pattern. It is also possible to use those which have been subjected to uneven processing such as. In addition, the medicine package of the present invention in which the liquid detergent is packaged retains the shape in which the liquid detergent is included during storage. Then, during use (during washing), the package (water-soluble film) comes into contact with water, so that the package is dissolved and the liquid detergent contained therein flows out from the package.

A known method can be used for packaging a drug, especially a liquid detergent, into a package using the water-soluble film of the present invention. For example, (1) heat sealing method, (2) water sealing method, (3) glue sealing method and the like can be mentioned. Among them, (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 thereof is not exceeded.
In the examples, "part" and "%" mean weight basis.

The following were prepared as PVA-based resins.
Carboxyl group-modified PVA (A1): 4% aqueous solution viscosity 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): 4% aqueous solution viscosity 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%

<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% of maleic acid monomethyl ester was used. , 10% of unmodified PVA (A3) having a 4% aqueous solution viscosity at 20° C. of 18 mPa·s and an average saponification degree of 88 mol%, 20 parts of sorbitol (b1) and glycerin (b2) as a plasticizer (B). 20 parts, 8 parts starch (average particle size 20 μm) as the filler (C), 2 parts polyoxyalkylene alkyl ether phosphate monoethanolamine salt as the surfactant (D) and water are mixed and dissolved. Treatment was performed to obtain a PVA aqueous solution (solid content concentration 25%) in which starch was dispersed.
The obtained PVA aqueous solution was degassed at 80°C and cooled to 40°C. The PVA aqueous solution was cast 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 89 μm. Obtained.
The obtained PVA film (water-soluble film) was measured as follows.

(Dissolution time at 5°C in hard water)
"HEPAR (hardness about 1849 mg/L, magnesium 119 mg/L, calcium 549 mg/L)" was used as hard water, and the film sample was cut into a size of 3 cm x 5 cm and fixed to a jig. Next, water (1 liter) was put into a 1 liter beaker, and the film fixed on the jig was immersed in the water while stirring (rotor length 3 cm, rotation speed 200 to 300 rpm) with a stirrer while keeping the water temperature at 5°C. It was dipped and the time (seconds) until the film was dissolved was measured. As a standard for "dissolution", the case where no dispersion of insoluble fine particles having a diameter of 1 mm or more was observed was defined as dissolution.

(Dissolution time at 5°C in soft water)
The measurement was performed by performing the same operation as the measurement of the dissolution time at 5° C. in the hard water, except that deionized water was used as the soft water.

(8% tensile elastic 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 being left for 24 hours under a condition of 23° C. and 50% RH humidity before measurement, a PVA-based film was used in this environment, using an autograph AG-X Plus manufactured by Shimadzu Corporation, and a pulling speed of 200 mm/ The elastic modulus was measured in minutes, and the measured value at an elongation of 8% was used (film width 15 mm, chuck distance 50 mm).

<Examples 2-6, Comparative Examples 1-2>
A PVA-based film (water-soluble film) was obtained in the same manner as in Example 1 except that the changes were made as shown in Table 1.
The PVA-based films (water-soluble films) of Examples 2 to 6 and Comparative Examples 1 and 2 thus obtained were evaluated in the same manner as in Example 1.

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

From the results of Table 1 above, in the above-mentioned Examples, there is no great difference in cold water solubility between hard water and soft water, and the solubility is excellent, so that the region to be used is not limited. On the other hand, in the comparative example, there is a large difference in solubility due to the difference in water, and the solubility changes depending on the region where it is used. It had to be examined.

The water-soluble film of the present invention is excellent in solubility in water, particularly in cold water, has no great difference in solubility in hard water or soft water, and has solubility that is not affected by the region of use. Therefore, it can be used for various packaging applications, and is particularly useful for unit packaging applications of medicines and the like, especially liquid detergents.

Claims (8)

A water-soluble film containing a polyvinyl alcohol-based resin (A), which satisfies the following [1] to [3].
[1] The dissolution time (T1) at 5° C. in hard water having a hardness of 120 mg/L or more specified by WHO (World Health Organization) standard is 180 seconds or less.
[2] The dissolution time (T2) at 5° C. in soft water having a hardness of less than 120 mg/L specified by WHO (World Health Organization) standards is 120 seconds or less.
[3] The difference (T1-T2) between the dissolution time (T1) and the dissolution time (T2) is 80 seconds or less. The water-soluble film according to claim 1, further comprising a plasticizer (B). The water-soluble film according to claim 2, wherein the content of the plasticizer (B) is 25 parts by weight or more based on 100 parts by weight of the polyvinyl alcohol resin (A). The water-soluble film according to any one of claims 1 to 3, wherein the polyvinyl alcohol-based resin (A) contains an anionic group-modified polyvinyl alcohol-based resin and an unmodified polyvinyl alcohol-based resin. The water-soluble film according to any one of claims 1 to 4, 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 5, which is used for drug packaging. A drug package comprising the water-soluble film according to claim 1 and a liquid detergent packaged therein. 8. The drug package according to claim 7, wherein the liquid detergent has a pH value of 6 to 12 when dissolved or dispersed in water and a water content of 15% by weight or less.