Water-soluble film and packaging body

Abstract

Provided is a water-soluble film which has an excellent balance between fast solubility and mechanical properties and also has excellent sealing properties. A water-soluble film containing a polyvinyl alcohol-based resin (A) and a plasticizer (B), the content of the plasticizer (B) being 30 parts by mass or less per 100 parts by mass of the polyvinyl alcohol-based resin (A), the plasticizer (B) containing a polyol (b1) having a melting point of 80 DEG C or higher, and the polyol (b1) containing 20 mass% or more of xylitol.

Description

Technical Field

[0001] The present invention relates to a polyvinyl alcohol-based water-soluble film and a packaging body using the same. Background Art

[0002] Polyvinyl alcohol-based films are films made of water-soluble thermoplastic resins. Taking advantage of the water solubility of polyvinyl alcohol, they have long been used as water-soluble films in a wide range of fields. Specifically, they are used for pharmaceutical packaging, (hydraulic) transfer films, sanitary napkins / diapers and other sanitary products, ostomy bags and other waste management products, medical products such as blood-absorbing sheets, and temporary substrates such as seedling sheets / seed tapes / embroidery base fabrics.

[0003] Among them, water-soluble films are particularly used in unit packaging (individual packaging) due to their convenience, which saves the time of measuring the amount to be used and does not stain hands. They are attracting attention as packaging for chemicals such as laundry detergents and / or dishwashing detergents.

[0004] For example, as a water-soluble film having excellent mechanical properties, in particular, a water-soluble film that does not lose its tension over time even when a liquid such as liquid detergent is packaged and made into a package, and can form a good package, a water-soluble film has been proposed in which the amount of plasticizer is 25 parts by weight or more relative to 100 parts by weight of polyvinyl alcohol-based resin and two plasticizers with different melting points are used in combination (for example, see Patent Document 1).

[0005] Furthermore, as a water-soluble film that dissolves in both hot and cold water and can maintain transparency, a water-soluble film that contains a large amount of plasticizer and requires a compatibilizer has been proposed (for example, see Patent Document 2).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-95679

[0009] Patent Document 2: Japanese Patent Application No. 2016-503121 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] However, in pharmaceutical packaging, not only for laundry detergents and / or dishwashing detergents, but also for individually packaged cosmetics such as conditioners, shampoos, and facial cleansers, rapid film solubility with a small amount of water is required because stirring in water or hot water is not used. However, the films described in Patent Documents 1 and / or 2 above sometimes have difficulty meeting this requirement.

[0012] Therefore, under such circumstances, an object of the present invention is to provide a water-soluble film having an excellent balance between rapid solubility and mechanical properties and also excellent sealing properties.

[0013] Solutions for solving problems

[0014] However, in view of this situation, the present inventors conducted intensive studies and found that a water-soluble film having an excellent balance between rapid solubility and mechanical properties and also excellent sealing properties can be obtained by setting the content of the plasticizer (B) to 30 parts by mass or less relative to 100 parts by mass of the polyvinyl alcohol-based resin (A), the plasticizer (B) containing a polyol (b1) having a melting point of 80°C or higher, and the polyol (b1) containing a specific amount of xylitol.

[0015] That is, the gist of the present invention is as follows. [1]

[0017] A water-soluble film comprising a polyvinyl alcohol-based resin (A) and a plasticizer (B).

[0018] The content of the plasticizer (B) is 30 parts by mass or less relative to 100 parts by mass of the polyvinyl alcohol-based resin (A).

[0019] The plasticizer (B) contains a polyol (b1) having a melting point of 80° C. or higher, and the polyol (b1) contains 20% by mass or higher of xylitol. [2]

[0021] The water-soluble film according to [1], wherein the polyol (b1) contains xylitol and at least one other polyol. [3]

[0023] The water-soluble film according to [2], wherein the at least one other polyol in the polyol (b1) is a sugar alcohol. [4]

[0025] The water-soluble film according to any one of [1] to [3], wherein the plasticizer (B) further contains a polyol (b2) having a melting point of 50°C or lower. [5]

[0027] The water-soluble film according to [4], wherein a mass ratio (b1 / b2) of the polyol (b1) to the polyol (b2) is 0.5 to 10. [6]

[0029] The water-soluble film according to any one of [1] to [5], wherein the polyvinyl alcohol-based resin (A) contains unmodified polyvinyl alcohol (a1). [7]

[0031] The water-soluble film according to any one of [1] to [6], wherein the water content of the water-soluble film is 3 to 15% by mass. [8]

[0033] A package comprising the water-soluble film according to any one of [1] to [7]. [9]

[0035] A food packaging body comprising the packaging body described in [8] and food enclosed in the packaging body.

[10]

[0037] An external preparation package comprising the package according to [8] or [9], and an external preparation for skin and / or hair enclosed in the package.

[11]

[0039] An animal cleaning agent package, comprising the package according to any one of [8] to

[10] , and the animal cleaning agent enclosed in the package.

[0040] Effects of the Invention

[0041] The water-soluble film of the present invention has an excellent balance between rapid solubility and mechanical properties, and also has excellent sealing properties. DETAILED DESCRIPTION

[0042] In this specification, when expressed as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less", and also includes the meaning of "preferably greater than X" or "preferably less than Y".

[0043] Furthermore, when expressed as "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number), it also includes the meaning of "preferably greater than X" or "preferably less than Y".

[0044] Furthermore, “x and / or y (x, y are arbitrary structures)” means at least one of x and y, and has three meanings: only x, only y, and x and y.

[0045] Regarding the numerical ranges described in stages in this specification, the upper limit or lower limit of the numerical range in a certain stage can be arbitrarily combined with the upper limit or lower limit of the numerical range in other stages. In addition, in the numerical ranges described in this specification, the upper limit or lower limit of the numerical range can also be replaced with the value shown in the embodiments.

[0046] In addition, polyvinyl alcohol is sometimes abbreviated as "PVA", a film mainly composed of a polyvinyl alcohol resin is sometimes abbreviated as "PVA film", and a water-soluble film mainly composed of a polyvinyl alcohol resin is sometimes abbreviated as "PVA water-soluble film".

[0047] Furthermore, the "main component" refers to a component that has a significant influence on the properties of the object, and the content of this component is usually 50% by mass or more, preferably 55% by mass or more, particularly preferably 60% by mass or more, and may also be 100% by mass in the object.

[0048] Hereinafter, the present invention will be described in detail.

[0049] A water-soluble film according to one embodiment of the present invention (hereinafter sometimes referred to as the "present water-soluble film") contains a PVA-based resin (A) and a plasticizer (B), wherein the content of the plasticizer (B) is 30 parts by mass or less relative to 100 parts by mass of the PVA-based resin (A), the plasticizer (B) contains a polyol (b1) having a melting point of 80°C or higher, and the polyol (b1) contains 20% by mass or more of xylitol.

[0050] Hereinafter, the components constituting the present water-soluble film will be described.

[0051] [PVA-based resin (A)]

[0052] The present water-soluble film is a water-soluble film with a PVA-based resin (A) as the main component. Here, "with a PVA-based resin (A) as the main component" means that, relative to the entire water-soluble film, the PVA-based resin (A) generally contains 50% by mass or more, preferably 55% by mass or more, and particularly preferably 60% by mass or more. When this content is too low, there is a tendency for the solubility in water and / or the mechanical properties of the film to decrease. The upper limit of this content is generally 99% by mass or less, preferably 95% by mass or less, and particularly preferably 90% by mass or less, from the perspective of shape stability over time.

[0053] It should be noted that "water-soluble film" refers to a film that dissolves in water at room temperature (20°C). In the present invention, the solubility of the film can be evaluated as follows. The water-soluble film is cut into a size of 3 cm × 5 cm, placed in a 1-liter beaker filled with water (1 liter), fixed with a fixture, and the water temperature is maintained at 20°C. While stirring with a stirrer (rotor length 3 cm, speed 750 rpm), the film is considered dissolved if no dispersion of insoluble particles with a diameter of 1 mm or more is visually observed.

[0054] Examples of the PVA-based resin (A) used in the present water-soluble film include unmodified PVA and / or modified PVA-based resins.

[0055] Unmodified PVA and modified PVA-based resins can be produced using a production method known in the relevant technical field, and can be produced, for example, as follows.

[0056] Unmodified PVA can be produced by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester compound.

[0057] Examples of the vinyl ester compound include vinyl formate, vinyl acetate, vinyl trifluoroacetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl laurate, vinyl versatate, vinyl palmitate, and vinyl stearate, with vinyl acetate being preferred. These vinyl ester compounds may be used alone or in combination of two or more.

[0058] The modified PVA-based resin can be produced by copolymerizing the aforementioned vinyl ester-based compound and an unsaturated monomer copolymerizable with the vinyl ester-based compound, followed by saponification.

[0059] Examples of the unsaturated monomer copolymerizable with the vinyl ester compound include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene; hydroxyl-containing α-olefins such as 3-butene-1-ol, 4-pentene-1-ol, and 5-hexene-1-ol, and their acylated derivatives; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, and undecenoic acid, and their salts, monoesters, and dialkyl esters; amides such as diacetone acrylamide, acrylamide, and methacrylamide; olefin sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid, and their salts; and N-vinyl pyrrolidone. These may be used alone or in combination of two or more.

[0060] Examples of modified PVA resins include those having primary hydroxyl groups in their side chains. Examples include those having 1 to 5 primary hydroxyl groups in their side chains, preferably 1 to 2, and particularly preferably 1. Furthermore, preferred are those having secondary hydroxyl groups in addition to primary hydroxyl groups. Examples of such modified PVA resins include those having hydroxyalkyl groups in their side chains and those having 1,2-diol structural units in their side chains. PVA-based resins having a 1,2-diol structural unit in the side chain can be produced, for example, by the following methods: (1) a method of saponifying a copolymer of vinyl acetate and 3,4-diacetoxy-1-butene, (2) a method of saponifying and decarbonating a copolymer of vinyl acetate and vinyl ethylene carbonate, (3) a method of saponifying and deketalizing a copolymer of vinyl acetate and 2,2-dialkyl-4-vinyl-1,3-dioxolane, (4) a method of saponifying a copolymer of vinyl acetate and glycerol monoallyl ether, etc.

[0061] From the perspective of solubility, the modified PVA-based resin used in the present water-soluble film is preferably a modified PVA-based resin modified with at least one hydrophilic group selected from anionic groups such as carboxyl groups, sulfonic acid groups, and phosphoric acid groups, and pyrrolidone ring groups. Among them, it is preferred to use a PVA-based resin modified with anionic groups. Examples of the anionic groups include carboxyl groups, sulfonic acid groups, and phosphoric acid groups. From the perspective of solubility stability over time, carboxyl groups and sulfonic acid groups are preferred, and carboxyl groups are particularly preferred.

[0062] The aforementioned carboxyl-modified PVA resin can be manufactured by any method. Examples of the manufacturing method include: (i) a method in which an unsaturated monomer having a carboxyl group is copolymerized with a vinyl ester compound and then saponified; (ii) a method in which a vinyl ester compound is polymerized in the presence of an alcohol and / or aldehyde or thiol having a carboxyl group as a chain transfer agent and then saponified.

[0063] Examples of the unsaturated monomer having a carboxyl group in the method (i) include ethylenically unsaturated dicarboxylic acids (maleic acid, fumaric acid, itaconic acid, etc.), ethylenically unsaturated dicarboxylic acid monoesters (maleic acid monoalkyl esters, fumaric acid monoalkyl esters, itaconic acid monoalkyl esters, etc.), ethylenically unsaturated dicarboxylic acid diesters (maleic acid dialkyl esters, fumaric acid dialkyl esters, itaconic acid dialkyl esters, etc.) [however, these diesters need to be converted into carboxyl groups by hydrolysis during the saponification of the copolymer], ethylenically unsaturated carboxylic acid anhydrides ( Monomers such as maleic anhydride, itaconic anhydride, etc.) or ethylenically unsaturated monocarboxylic acids ((meth)acrylic acid, crotonic acid, etc.), and salts thereof, are preferably used. Among them, maleic acid, monoalkyl maleate, dialkyl maleate, maleate salts, maleic anhydride, itaconic acid, monoalkyl itaconate, dialkyl itaconate, (meth)acrylic acid, etc. are preferably used. Maleic acid, monoalkyl maleate, dialkyl maleate, maleate salts, and maleic anhydride are particularly preferred, and monoalkyl maleate is further preferred. These can be used alone or in combination of two or more.

[0064] In the method (ii) described above, compounds derived from mercaptans having a particularly large chain transfer effect are effective, and examples thereof include compounds represented by the following general formulas (1) to (3).

[0065]

[0066] [In the above general formula (1), n ​​is an integer from 0 to 5.]

[0067]

[0068] [In the above general formula (2), n is an integer of 0 to 5.

[0069] In addition, R1, R2, and R3 each represent a hydrogen atom or a lower alkyl group (optionally containing a substituent).]

[0070]

[0071] [In the above general formula (3), n is an integer from 0 to 20.]

[0072] In addition, salts of the compounds represented by the aforementioned general formulae (1) to (3) may also be mentioned. Specifically, examples thereof include thioglycolate, 2-mercaptopropionate, 3-mercaptopropionate, and 2-mercaptostearate. These compounds may be used alone or in combination of two or more.

[0073] It should be noted that, in addition to the aforementioned unsaturated monomers and vinyl ester compounds having a carboxyl group, other common monomers may be included and polymerized within a range that does not impair water solubility. Examples of such monomers include alkyl esters of ethylenically unsaturated carboxylic acids, allyl esters of saturated carboxylic acids, α-olefins, alkyl vinyl ethers, alkyl allyl ethers, (meth)acrylamide, (meth)acrylonitrile, styrene, and vinyl chloride. These monomers may be used alone or in combination of two or more.

[0074] In addition, the method for producing the aforementioned carboxyl-modified PVA-based resin is not limited to the aforementioned method. For example, a method in which a carboxyl-containing compound having a functional group reactive with a hydroxyl group, such as a dicarboxylic acid, aldehyde acid, or hydroxycarboxylic acid, is subjected to a post-reaction with a PVA resin (partially saponified or completely saponified).

[0075] In addition, when using a sulfonic acid-modified PVA-based resin modified with a sulfonic acid group, for example, it can be produced by a method of copolymerizing a copolymer component such as vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, or 2-acrylamide-2-methylpropanesulfonic acid with a vinyl ester compound and then saponifying it; or by subjecting vinyl sulfonic acid or its salt, 2-acrylamide-2-methylpropanesulfonic acid or its salt to a PVA-based resin through a Michael addition method.

[0076] On the other hand, examples of methods for post-modifying the unmodified PVA include methods of acetoacetyl esterification, acetalization, urethanization, etherification, grafting, phosphate esterification, and oxyalkylene esterification.

[0077] In the present water-soluble film, from the viewpoint of safety and stability, the PVA-based resin (A) preferably contains unmodified PVA (a1), particularly preferably contains unmodified PVA (a1) as the main component, and further preferably contains only unmodified PVA (a1).

[0078] The average saponification degree of the PVA-based resin (A) is preferably 80 mol% or higher, particularly preferably 82 to 99.9 mol%, further preferably 85 to 98.5 mol%, and particularly preferably 85 to 90 mol%. If the average saponification degree is too low, the solubility of the film in water tends to decrease. However, if the average saponification degree is too high, the water solubility also tends to decrease.

[0079] The average saponification degree is measured in accordance with JIS K 6726 3.5.

[0080] The polymerization degree of the PVA-based resin (A) can generally be expressed by the viscosity of an aqueous solution. The viscosity of a 4 mass % aqueous solution at 20° C. is preferably 1 to 60 mPa·s, particularly preferably 2 to 55 mPa·s, and further preferably 3 to 50 mPa·s.

[0081] Furthermore, as a PVA-based resin (A), from the viewpoint of solubility, the viscosity of a 4 mass % aqueous solution at 20°C is preferably 0.5 to 55 mPa·s, preferably 1 to 45 mPa·s, particularly preferably 2 to 30 mPa·s, further preferably 3 to 25 mPa·s, and particularly preferably 3 to 20 mPa·s.

[0082] In addition, as a PVA-based resin (A), from the viewpoint of mechanical properties, the viscosity of a 4% by mass aqueous solution at 20°C is preferably 5 to 60 mPa·s, particularly preferably 15 to 55 mPa·s, further preferably 17 to 53 mPa·s, particularly preferably 21 to 50 mPa·s, and further preferably 21.5 to 48 mPa·s.

[0083] If the viscosity is too low, the mechanical strength of the water-soluble film used as a packaging material tends to decrease. On the other hand, if it is too high, productivity tends to decrease or solubility tends to decrease.

[0084] The viscosity of the 4% by mass aqueous solution is measured in accordance with JIS K 6726 3.11.2.

[0085] When using unmodified PVA (a1), the average saponification degree of the unmodified PVA (a1) is preferably 80 mol% or more, particularly preferably 82 to 98.5 mol%, and even more preferably 85 to 90 mol%. If the average saponification degree is too low, the solubility of the water-soluble film in water tends to decrease. However, if the average saponification degree is too high, the solubility in water also tends to decrease.

[0086] When unmodified PVA (a1) is used, the viscosity of a 4% by mass aqueous solution of the unmodified PVA (a1) at 20°C is preferably 1 to 60 mPa·s, particularly preferably 2 to 55 mPa·s, and even more preferably 3 to 50 mPa·s. If the viscosity is too low, the mechanical strength of the water-soluble film used as a packaging material tends to decrease. If the viscosity is too high, the aqueous solution viscosity during film formation tends to increase, resulting in reduced productivity or decreased solubility.

[0087] The modification amount of the modified PVA resin is preferably 15 mol% or less, particularly preferably 10 mol% or less, further preferably 5 mol% or less, and particularly preferably 2 mol% or less. The lower limit is usually 0 mol%. If the modification amount is too high, the productivity of the PVA resin tends to decrease, the biodegradability tends to decrease, and the resin tends to cause blocking.

[0088] In the present water-soluble film, the PVA-based resin (A) may be used alone or in combination of two or more unmodified PVAs or PVA-based resins differing in at least one of the degree of saponification, viscosity, type of modification, and amount of modification. From the perspective of ease of adjusting the dissolution rate and / or mechanical properties, it is preferred to use two or more in combination. For example, two or more unmodified PVAs may be used in combination, two or more modified PVA-based resins may be used in combination, or one or more unmodified PVAs and one or more modified PVA-based resins may be used in combination.

[0089] Among them, from the viewpoint of safety and stability, it is preferred to contain unmodified PVA, and from the viewpoint of facilitating adjustment of the balance between solubility and mechanical properties, it is preferred to use two or more unmodified PVAs in combination.

[0090] [Plasticizer (B)]

[0091] Examples of the plasticizer (B) used in the water-soluble film include glycerols such as glycerol, diglycerol, and triglycerol; alkylene glycols such as triethylene glycol, polyethylene glycol, polypropylene glycol, dipropylene glycol, and propylene glycol; trimethylolpropane; and sugar alcohols such as sorbitol, xylitol, maltitol, mannitol, and erythritol. These may be used alone or in combination of two or more.

[0092] The present water-soluble film contains a polyol (b1) having a melting point of 80° C. or higher as a plasticizer (B).

[0093] As the polyol (b1) having a melting point of 80°C or higher, most of sugar alcohols, monosaccharides and polysaccharides can be used, among which, for example, diols such as salicyl alcohol (83°C), catechol (105°C), resorcinol (110°C), hydroquinone (172°C), bisphenol A (158°C), bisphenol F (162°C), neopentyl glycol (127°C), triols such as phloroglucinol (218°C), erythritol (121°C), threonol ( Examples of the following include tetrahydric alcohols such as xylitol (88°C), pentaerythritol (260°C), pentahydric alcohols such as xylitol (92°C), arabitol (103°C), fucitol (153°C), glucose (146°C), and fructose (104°C), hexahydric alcohols such as mannitol (166°C), sorbitol (95°C), and inositol (225°C), octahydric alcohols such as lactitol (146°C), sucrose (186°C), and trehalose (97°C), and nonahydric or higher alcohols such as maltitol (145°C). These may be used alone or in combination of two or more. Note that the parentheses indicate the melting point.

[0094] In view of the tensile strength of the water-soluble film, the melting point is preferably 85°C or higher, particularly preferably 90°C or higher. The upper limit of the melting point is preferably 300°C or lower, particularly preferably 200°C or lower, and further preferably 100°C or lower.

[0095] The polyol (b1) used in the present water-soluble film contains 20% by mass or more of xylitol, preferably 30 to 100% by mass, particularly preferably 40 to 95% by mass, and further preferably 50 to 90% by mass.

[0096] The content of xylitol relative to the entire plasticizer (B) is preferably 10% by mass or more, particularly preferably 15 to 95% by mass, further preferably 20 to 80% by mass, and particularly preferably 25 to 70% by mass.

[0097] If the content of xylitol is too low, it tends to be difficult to adjust the balance between solubility and mechanical properties, while if it is too high, the mechanical properties and / or formability of the film tend to decrease.

[0098] The polyol (b1) may contain only xylitol, but preferably contains xylitol and at least one other polyol from the viewpoint of mechanical properties. Furthermore, from the viewpoint of safety and stability, the at least one other polyol in the polyol (b1) is preferably a sugar alcohol.

[0099] As a polyol other than xylitol, from the viewpoint of compatibility with the PVA-based resin (A), the number of hydroxyl groups in one molecule is preferably 4 or more, particularly preferably 5 to 10, and further preferably 6 to 8. Specifically, for example, sorbitol, sucrose, trehalose, etc. are preferred polyols.

[0100] From the viewpoint of toughness of the water-soluble film, the polyol (b1) preferably has a molecular weight of 150 or more, particularly preferably 160 to 500, and further preferably 180 to 400. Specific examples of preferred polyols include sorbitol and sucrose.

[0101] In addition, when two or more plasticizers (B) are used in combination in the present water-soluble film, from the perspective of mechanical properties, it is preferred to use a polyol (b2) having a melting point of 50°C or less. Examples of polyols (b2) having a melting point of 50°C or less include aliphatic alcohols, such as 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), dipropylene glycol (-39°C), tripropylene glycol, and diols such as polyethylene glycol with a molecular weight of 2000 or less; and trivalent or higher alcohols such as glycerol (18°C), diglycerol, and triethanolamine (21°C). Glycerol, propylene glycol, and dipropylene glycol are particularly preferred. These can be used alone or in combination of two or more. It should be noted that the parentheses indicate the melting point.

[0102] In view of the flexibility of the water-soluble film, the melting point is preferably 30°C or lower, more preferably 20°C or lower. The lower limit of the melting point is usually -80°C or higher, preferably -60°C or higher, particularly preferably -10°C or higher, and particularly preferably 0°C or higher.

[0103] Furthermore, the number of hydroxyl groups in one molecule of the polyol (b2) is preferably 4 or less, and particularly preferably 3 or less from the viewpoint of easy control of flexibility near room temperature (25°C). Specific examples thereof include glycerin and propylene glycol.

[0104] The polyol (b2) preferably has a molecular weight of 100 or less, particularly preferably 50 to 100, and further preferably 60 to 95, from the viewpoint of easy control of flexibility. Specific examples thereof include glycerin and propylene glycol.

[0105] The content of the plasticizer (B) is 30 parts by mass or less, preferably 1 to 28 parts by mass, more preferably 5 to 25 parts by mass, and particularly preferably 6 to 20 parts by mass, relative to 100 parts by mass of the PVA-based resin (A).

[0106] When the content of the plasticizer (B) is too large, blocking tends to occur easily, or it tends to be difficult to adjust the balance between mechanical properties and solubility.

[0107] The mass ratio (b1 / b2) of the polyol (b1) to the polyol (b2) is preferably 0.5 to 10, particularly preferably 0.8 to 8, further preferably 1 to 7, and particularly preferably 1.5 to 6.

[0108] When the polyol (b2) is used, the content thereof is preferably 1 to 20 parts by mass, particularly preferably 1.5 to 18 parts by mass, further preferably 2 to 15 parts by mass, and particularly preferably 2.5 to 10 parts by mass, relative to 100 parts by mass of the PVA-based resin (A).

[0109] If the content of the polyol (b2) is too low, the mechanical properties tend to be reduced, while if it is too high, the mechanical properties and / or moldability of the film tend to be reduced.

[0110] [filler]

[0111] Examples of the filler used in the present water-soluble film include organic fillers and / or inorganic fillers. Among them, organic fillers are preferably used.

[0112] The average particle size of the filler is preferably 0.1 to 50 μm, particularly preferably 1 to 35 μm. The average particle size of the filler is measured using a laser diffraction particle size distribution analyzer and calculated from the D50 value (particle size at 50% cumulative volume distribution) of the obtained cumulative volume distribution.

[0113] The organic filler used in the present water-soluble film refers to a granular substance (primary particle) composed of an organic compound and having any shape such as needles / rods, layers, scales, or spheres, or an aggregate of the granular substance (secondary particle).

[0114] As the organic filler, it is mainly selected from polymer compounds, for example, in addition to melamine resins, poly(methyl)acrylate resins, and polystyrene resins, biodegradable resins such as starch and polylactic acid can also be mentioned. These can be used alone or in combination of two or more. Among these, biodegradable resins such as poly(methyl)acrylate resins, polystyrene resins, and starch are preferred. From the viewpoint of dispersibility relative to PVA resin (A), starch is particularly preferred.

[0115] Examples of the starch include raw starch (corn starch, potato starch, sweet potato starch, wheat starch, cassava starch, sago starch, tapioca starch, sorghum starch, rice starch, bean starch, kudzu root starch, bracken starch, lotus seed starch, water chestnut starch, etc.), physically modified starch (α-starch, separated amylose, heat-moisture treated starch, etc.), enzyme-modified starch (hydrolyzed dextrin, enzyme-decomposed dextrin, amylose, etc.), chemically decomposed modified starch (acid-treated starch, hypochlorous acid-oxidized starch, dialdehyde starch, etc.), chemically modified starch derivatives (esterified starch, etherified starch, cationized starch, cross-linked starch, etc.). These can be used alone or in combination of two or more. Of these, raw starch is preferably used, and corn starch and rice starch are particularly preferably used, from the viewpoint of ease of acquisition and / or biodegradability.

[0116] The average particle size of the organic filler is preferably 5 to 50 μm, particularly preferably 10 to 40 μm, and even more preferably 15 to 35 μm. If the average particle size is too small, the film's blocking properties tend to increase. If it is too large, the fillers tend to aggregate, reducing dispersibility and causing pinholes during film molding or stretching.

[0117] The inorganic filler used in the present water-soluble film refers to particulate matter (primary particles) composed of an inorganic compound and having any shape such as needles, rods, layers, scales, or spheres, or aggregates of the particulate matter (secondary particles).

[0118] Examples of the inorganic filler include oxide-based inorganic compounds such as silica, diatomaceous earth, titanium dioxide, calcium oxide, magnesium oxide, aluminum oxide, barium oxide, germanium dioxide, tin oxide, and zinc oxide, and / or talc, clay, kaolin, mica, asbestos, gypsum, graphite, glass spheres, 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, hollow carbon spheres, 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, and potassium chromate. These can be used alone or in combination of two or more.

[0119] Among them, oxide-based inorganic compounds, silica, and talc are preferably used, titanium dioxide, silica, and talc are particularly preferably used, and silica is further preferably used.

[0120] The average particle size of the inorganic filler is preferably 1 to 20 μm, particularly preferably 2 to 15 μm, and even more preferably 3 to 10 μm. If the average particle size is too small, the film's blocking properties tend to increase, and the film's flexibility and / or toughness tend to decrease. If the average particle size is too large, the film's water-tightness tends to decrease.

[0121] The content of the filler is preferably 1 to 30 parts by mass, particularly preferably 2 to 25 parts by mass, and even more preferably 2.5 to 20 parts by mass per 100 parts by mass of the PVA-based resin (A). If the content is too low, the blocking property tends to increase, while if it is too high, the flexibility and / or toughness of the film tends to decrease.

[0122] In addition, from the perspective of the balance between the anti-blocking properties and the mechanical properties of the film, the content is preferably 10 parts by mass or less, particularly preferably 8 parts by mass or less, further preferably 0.1 to 6 parts by mass, and particularly preferably 0.5 to 5 parts by mass relative to 100 parts by mass of the PVA-based resin (A).

[0123] [Surfactant (D)]

[0124] The present water-soluble film may contain a surfactant (D) or the like as needed.

[0125] As surfactant (D), it is contained for the purpose of improving the peelability from the casting surface when manufacturing this water-soluble film, and nonionic surfactants, cationic surfactants, anionic surfactants etc. can be listed. For example, polyoxyethylene nonylphenyl ether, polyoxyethylene octyl nonyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyalkylene alkyl ether phosphate ester monoethanolamine salt, polyoxyethylene laurylamine ether, polyoxyethylene stearylamine ether and other polyoxyethylene alkylamine ethers etc. can be mentioned. Among them, from the viewpoint of manufacturing stability, polyoxyalkylene alkyl ether phosphate ester monoethanolamine salt and polyoxyethylene laurylamine ether are preferably used. These can be used alone or in combination of two or more. It is also preferred to use nonionic surfactants and anionic surfactants in combination.

[0126] The content of the surfactant (D) is preferably 0.1 to 5 parts by mass, particularly preferably 0.2 to 4.5 parts by mass, and even more preferably 0.3 to 4 parts by mass, relative to 100 parts by mass of the PVA-based resin (A). If the content is too low, the peelability between the casting surface of the film-forming apparatus and the resulting water-soluble film is reduced, tending to reduce productivity. If the content is too high, problems such as reduced adhesive strength during sealing when the water-soluble film is formed into a package tend to occur.

[0127] It should be noted that, in the present water-soluble film, from the viewpoint of suppressing yellowing, it is further preferred to mix an antioxidant, within the scope not hindering the purpose of the invention. Examples of such antioxidants include sulfites such as sodium sulfite, potassium sulfite, calcium sulfite, ammonium sulfite, tartaric acid, ascorbic acid, sodium thiosulfate, catechol, and Rongalite. These can be used alone or in combination of two or more. Among them, sulfites are preferred, and sodium sulfite is particularly preferred. The amount of the antioxidant mixed is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, and particularly preferably 0.3 to 3 parts by mass relative to 100 parts by mass of the PVA-based resin (A).

[0128] Furthermore, the present water-soluble film may further contain fragrances, rust inhibitors, mildew inhibitors, colorants, extenders, defoaming agents, ultraviolet absorbers, fluorescent whitening agents, liquid paraffins, bittering ingredients (e.g., denatonium benzoate), etc., within a range not hindering the purpose of the invention (e.g., 5 parts by mass or less per 100 parts by mass of the PVA-based resin (A)). These may be used alone or in combination of two or more.

[0129] <Manufacturing of Water-Soluble Film>

[0130] The water-soluble film is prepared by blending the aforementioned PVA-based resin (A), plasticizer (B), and, if necessary, filler (C), surfactant (D), etc., dissolving or dispersing them in water to prepare a film-forming raw material. Film formation is then performed to form a water-soluble film. The following describes the steps for producing this water-soluble film.

[0131] [Dissolution process]

[0132] In the dissolving step, the PVA-based resin composition containing the aforementioned components is dissolved or dispersed in water to prepare an aqueous solution or aqueous dispersion serving as a film-forming raw material.

[0133] As a dissolution method for dissolving the PVA-based resin composition in water, ordinary temperature dissolution, high temperature dissolution, pressurized dissolution, etc. are generally used. Among them, high temperature dissolution is preferred from the viewpoint of less undissolved matter and excellent productivity.

[0134] The solid content concentration of the film-forming raw material is preferably 10 to 65% by mass, particularly preferably 12 to 50% by mass, and even more preferably 15 to 40% by mass. If the concentration is too low, the film productivity tends to decrease, while if it is too high, the viscosity becomes too high, degassing of the film-forming raw material takes time, or die lines tend to form during film formation.

[0135] The viscosity of the aqueous solution of the film-forming raw material is preferably 3,000 to 12,000 mPa·s, particularly preferably 4,000 to 11,000 mPa·s, and even more preferably 5,000 to 10,000 mPa·s. If the concentration is too low, film productivity may decrease or pinholes may form. If the concentration is too high, the viscosity may become too high, requiring time to degas the film-forming raw material, or a die line may form during film formation.

[0136] [Film forming process]

[0137] In the film forming step, the film forming raw material prepared in the dissolving step is formed into a film shape and, if necessary, dried to produce a water-soluble film.

[0138] For film formation, for example, a melt extrusion method and / or a casting method can be used. From the viewpoint of accuracy in film thickness, the casting method is preferred.

[0139] When the casting method is performed, for example, the aforementioned film-making raw material is discharged from a slit such as a T-slit die, cast on a casting surface such as a metal surface of an endless belt and / or a drum roller, a plastic substrate such as a polyethylene terephthalate film or polypropylene, and dried, thereby producing a water-soluble film.

[0140] In the film forming step, the present water-soluble film peeled from the casting surface or the like after drying is conveyed and wound up, and wound around a core tube to prepare a film roll.

[0141] The obtained film roll may be supplied as a product directly, but may also be supplied preferably in the form of a film roll cut into a film width of a desired size.

[0142] In this way, the present water-soluble film can be produced.

[0143] The thickness of the water-soluble film can be appropriately selected depending on the intended use, but is preferably 10 to 130 μm, particularly preferably 15 to 110 μm, and even more preferably 20 to 100 μm. If the thickness is too thin, the mechanical strength of the film tends to decrease, while if it is too thick, the dissolution rate in water tends to slow, and the film-forming efficiency tends to decrease.

[0144] The width of the water-soluble film can be appropriately selected depending on the intended use, but is preferably 300 to 5000 mm, particularly preferably 500 to 4000 mm, and even more preferably 600 to 3000 mm. If the width is too narrow, production efficiency tends to decrease, while if it is too wide, slack and / or film thickness control tends to become difficult.

[0145] The length of the water-soluble film can be appropriately selected depending on the intended use, but is preferably 100 to 20,000 m, particularly preferably 800 to 15,000 m, and even more preferably 1,000 to 10,000 m. If the length is too short, film replacement tends to be time-consuming and labor-intensive, while if it is too long, winding tightening tends to result in poor appearance and / or excessive weight.

[0146] In addition, the surface of the present water-soluble film may be smooth, but from the viewpoint of anti-blocking properties, slippage during processing, reduction of adhesion between products, and appearance, it is also preferred to pre-process one or both sides of the film with embossed patterns and / or fine concave-convex patterns, special engraved patterns, or other concave-convex processing.

[0147] Furthermore, from the perspective of mechanical strength and / or heat sealability, the water content of the present water-soluble film is preferably 3-15% by mass, particularly preferably 5-10% by mass, and even more preferably 6-8% by mass. If the water content is too low, the film becomes too hard, which can lead to reduced formability and / or impact resistance of the packaged product, or poor sealing. If the water content is too high, blocking can easily occur. Adjusting the water content to this range can be achieved by appropriately setting drying and / or humidity control conditions.

[0148] In addition, the said water content is measured based on JIS K 6726 3.4, and the value of the volatile matter obtained is made into the water content.

[0149] This water-soluble film is useful for various packaging applications, including unit packaging for various contents, (hydraulic) transfer films, sanitary products such as sanitary napkins and diapers, waste disposal products such as ostomy bags, medical products such as blood-absorbing sheets, and temporary substrates such as seedling sheets, seed tapes, and embroidery base fabrics. In particular, it is particularly suitable for unit packaging (individual packages) for various contents.

[0150] <Individual packaging>

[0151] An example of an embodiment of the present invention comprises an individual package containing a water-soluble film, and containing a cleaning agent or other contents. The individual package maintains its shape while stored, retaining its contents. Furthermore, during use, the individual package (water-soluble film) dissolves when exposed to water, allowing the contents to flow out of the package.

[0152] Examples of the contents contained in the individual packages include: animal foods (primary products) such as meat, fish, shellfish, eggs, milk, and oils; cereals such as rice, wheat, soybeans, adzuki beans, and corn; various seeds and fruits such as almonds, walnuts, and peanuts; plant foods (primary products) such as potatoes, beans, vegetables, fruits, mushrooms, oils, and seaweed; and secondary products (processed foods, alternative foods); external preparations for skin and / or hair such as body washes, hair washes (shampoos), skin preparations (e.g., shaving creams, moisturizing lotions, etc.), and hair preparations (conditioners, conditioners, etc.); oral preparations such as toothpaste; pesticides such as disinfectants, herbicides, and fertilizers; dishwashing detergents; clothing agents such as laundry detergents and fabric softeners; and animal preparations such as animal cleaning detergents and animal cleaning agents (shampoos, conditioners, etc.). These may be used alone or in combination of two or more.

[0153] The contents may be in the form of a liquid, a solid, or a gel. Liquids are liquid at 20°C, while solids may be in the form of granules, tablets, or powders. The form of the contents can be appropriately selected depending on the intended use. For example, in food packaging, solids (granules, tablets, or powders) are preferably enclosed, while in packaging for external preparations for skin and / or hair, liquids and / or granules or powders are preferably enclosed. The pH of the contents may be alkaline, neutral, or acidic.

[0154] The present water-soluble film has an excellent balance between rapid solubility and mechanical properties, as well as excellent sealing properties. Therefore, it is preferably used for packaging food, external preparations for skin and / or hair, and animal detergents in addition to laundry detergents and / or dishwashing detergents. In particular, it is suitable for unit packaging applications (individual packages) of these.

[0155] When using this water-soluble film to form an independent package, known methods can be used. For example, there are methods of filling the bag-shaped film with contents through another process, methods of using an automatic filling machine, particularly a pillow-shaped method, to simultaneously form the bag and fill the contents, etc. However, methods can also be used in which the film is temporarily vacuum-formed, an appropriate amount of contents is filled into the bag, and another film is laminated and sealed from above. It should be noted that the sealing of the bag and / or the sealing of the film during vacuum forming can be any of heat sealing, water sealing, and adhesive sealing, among which heat sealing is preferred from the perspective of versatility.

[0156] The dimensions (volume, length, width, thickness) of the individual package obtained as described above can be appropriately selected, and the volume of the contents can also be appropriately selected.

[0157] For example, the volume of the individual package is appropriately selected to be generally 1 to 20 mL, more preferably 3 to 12 mL, and particularly preferably 5 to 10 mL.

[0158] The thickness of the individual package is usually 0.5 to 60 mm, preferably 5 to 50 mm, and more preferably 10 to 40 mm.

[0159] The length of the individual package is usually 10 to 60 mm, preferably 15 to 50 mm, and more preferably 20 to 40 mm.

[0160] The width of the individual package is usually 10 to 60 mm, preferably 15 to 50 mm, and more preferably 20 to 40 mm.

[0161] The shape of the individual package can be appropriately selected and is not particularly limited. For example, it may be a substantially cubic shape, a substantially spherical shape, a substantially flattened spherical shape, a substantially teardrop shape, etc., and may have a plurality of partitions.

[0162] The number of the plurality of partitions in the package can be appropriately selected depending on the type of contents, etc., and is not particularly limited. For example, it is 2 to 10 partitions, preferably 3 to 8 partitions, and more preferably 4 to 6 partitions. Furthermore, it is preferred that each of the plurality of partitions package a different type of content.

[0163] The surface of the packaging body is generally smooth, but from the perspective of anti-blocking, slippage during processing, reduced adhesion between products (independent packaging bodies), and appearance, the outer surface of the packaging body (water-soluble film) may be subjected to embossing patterns and / or fine concave-convex patterns, special engraving patterns, and other concave-convex processing.

[0164] Example

[0165] Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the following Examples unless it exceeds the gist of the present invention.

[0166] In addition, in an example, "part" and "%" are a mass basis.

[0167] As material components of the water-soluble film, the following substances were prepared.

[0168] [PVA-based resin (A)]

[0169] Unmodified PVA resin (a1): 4% aqueous solution viscosity at 20°C 5 mPa·s, average saponification degree 88 mol%

[0170] Unmodified PVA resin (a2): 4% aqueous solution viscosity at 20°C 22 mPa·s, average saponification degree 88 mol%

[0171] Unmodified PVA resin (a3): 4% aqueous solution viscosity at 20°C 40 mPa·s, average saponification degree 88 mol%

[0172] [Plasticizer (B)]

[0173] Plasticizer (b1): xylitol, sorbitol

[0174] Plasticizer (b2): glycerol

[0175] [Other additives]

[0176] Starch (average particle size 20 μm)

[0177] <Example 1>

[0178] 100 parts of unmodified PVA resin (a2) as PVA-based resin (A), 7.8 parts of xylitol as plasticizer (b1), 6.5 parts of sorbitol, 2.5 parts of glycerin as plasticizer (b2), 0.8 parts of starch as filler and water are mixed and dissolved to obtain a PVA aqueous solution (solid content concentration 25%) in which starch is dispersed.

[0179] The obtained PVA aqueous solution was degassed at 80° C. and cooled to 40° C. The PVA aqueous solution was cast onto a polypropylene film and dried in a 10 m drying chamber (60-80° C.) at a speed of 2-4 m / min to obtain a water-soluble film with a thickness of 79 μm and a moisture content of 7%.

[0180] The obtained water-soluble film was evaluated by the following method. The results are shown in Table 1 below.

[0181] <Solubility>

[0182] 1. Dissolution evaluation method and evaluation criteria

[0183] [Evaluation method]

[0184] The water-soluble film obtained above was allowed to stand for more than 4 days under humidity conditions of 23°C and 50% RH before measurement, then cut into pieces of 3.5 cm × 3.5 cm in size, placed in a 1-liter beaker filled with water (1 liter), and fixed with a jig. While stirring with a stirrer (rotor length 3 cm, rotation speed 750 rpm) while maintaining the water temperature at 20°C, the case where the above film was completely separated into two pieces was recorded as "melting", and the time required for melting was evaluated based on the following criteria.

[0185] [Evaluation Criteria]

[0186] ◎(Excellent)···Dissolves in less than 40 seconds.

[0187] ○ (very good)···Dissolves in 40 seconds to less than 60 seconds.

[0188] △(Good)···Dissolves in 60 to 300 seconds.

[0189] × (poor)···Does not melt even after more than 300 seconds.

[0190] 2. Complete dissolution evaluation method and evaluation criteria

[0191] [Evaluation method]

[0192] The water-soluble film obtained above was allowed to stand for more than 4 days under humidity conditions of 23°C and 50% RH before measurement, then cut into pieces of 3.5 cm × 3.5 cm in size, placed in a 1-liter beaker filled with water (1 liter), and fixed with a jig. While stirring with a stirrer (rotor length 3 cm, rotation speed 750 rpm) while maintaining the water temperature at 20°C, the film was recorded as "completely dissolved" if no dispersion of insoluble particles with a diameter of 1 mm or more was observed. The time required for complete dissolution was evaluated based on the following criteria.

[0193] [Evaluation Criteria]

[0194] ◎(Excellent)···Completely dissolved in less than 90 seconds.

[0195] ○ (very good)···Completely dissolved in 90 seconds to less than 150 seconds.

[0196] △ (good)···Completely dissolved in 150 to 300 seconds.

[0197] × (poor)···Not completely dissolved even after more than 300 seconds.

[0198] <Mechanical Properties>

[0199] [Evaluation method]

[0200] The water-soluble film obtained above was used to measure tensile strength and tensile elongation in accordance with JIS K 7127. Specifically, the film was allowed to stand for at least 4 days under controlled humidity conditions of 23°C and 50% RH before measurement. The film was then measured for tensile strength and tensile elongation using an Autograph AG-IS (manufactured by Shimadzu Corporation) at a tensile speed of 200 mm / min (film width 10 mm, chuck distance 50 mm). These measured values ​​were evaluated based on the following criteria.

[0201] [Evaluation Criteria]

[0202] ○ (very good)···The tensile strength is 25 MPa or more, and the tensile elongation exceeds 300%.

[0203] Δ (good)···The tensile strength is 25 MPa or more, and the tensile elongation is 200 to 300%.

[0204] × (poor)···The tensile strength is 0 to less than 25 MPa and / or the tensile elongation is less than 200%.

[0205] <Sealing>

[0206] [Evaluation method]

[0207] [Breaking strength when peeling off the heat-sealed part]

[0208] The breaking strength was measured in accordance with JIS K 7127 (1999) as follows. Specifically, two sheets of water-soluble film, conditioned for one day at 23°C and 50% RH, were stacked and heat-sealed once at 150°C, 0.2 MPa, 0.5 seconds, and a seal width of 2 mm. The sheets were then allowed to stand for 2 hours at 23°C and 50% RH without applying a load to the heat-sealed portion. The breaking strength was then determined from the maximum point test force (N) measured at a tensile speed of 200 mm / min using an Autograph "AG-Xplus" manufactured by Shimadzu Corporation (film width 15 mm, distance between chucks 50 mm).

[0209] [Evaluation Criteria]

[0210] ○ (Very good)···The breaking strength is 5N / 15mm or more, and cohesive failure occurs in the heat-sealed portion.

[0211] × (poor)···The breaking strength was less than 5 N / 15 mm, and interfacial peeling occurred in the heat-sealed portion.

[0212] <Examples 2 to 4, Comparative Examples 1 to 4>

[0213] A 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 obtained water-soluble film was evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

[0214] [Table 1]

[0215]

[0216] As shown in the results of Table 1, the water-soluble films of Examples 1 to 4, which meet the compositions specified in the present invention, exhibit excellent mechanical properties, rapid dissolution, and sealing properties, making them suitable for packaging applications. Furthermore, these effects demonstrate that the films are suitable for food packaging, packaging for external preparations for skin and / or hair, and animal cleaning applications.

[0217] In contrast, the water-soluble films of Comparative Examples 1 to 4, which did not satisfy the compositions specified in the present invention, were inferior in at least one of mechanical properties and solubility.

[0218] The above embodiments show specific aspects of the present invention, but the above embodiments are merely illustrative and are not to be construed as limiting. Various modifications obvious to those skilled in the art are to be considered within the scope of the present invention.

[0219] Industrial applicability

[0220] The water-soluble film of the present invention has an excellent balance between rapid solubility and mechanical properties and also has excellent sealing properties, and can be used for various packaging applications, and is particularly suitable for unit packaging applications (individual packages) for various contents.

Claims

1. A water-soluble film comprising a polyvinyl alcohol-based resin A and a plasticizer B. in, The content of the plasticizer B is 30 parts by mass or less relative to 100 parts by mass of the polyvinyl alcohol-based resin A. The plasticizer B contains a polyol b1 having a melting point of 80° C. or higher, and the polyol b1 contains 20% by mass or higher of xylitol.

2. The water-soluble film according to claim 1, wherein The polyol b1 contains xylitol and at least one other polyol.

3. The water-soluble film according to claim 2, wherein The at least one other polyol in the polyol b1 is a sugar alcohol.

4. The water-soluble film according to any one of claims 1 to 3, wherein The plasticizer B further contains a polyol b2 having a melting point of 50° C. or less.

5. The water-soluble film according to claim 4, wherein The mass ratio b1 / b2 of the polyol b1 to the polyol b2 is 0.5 to 10.

6. The water-soluble film according to any one of claims 1 to 5, wherein The polyvinyl alcohol-based resin A contains unmodified polyvinyl alcohol a1.

7. The water-soluble film according to any one of claims 1 to 6, wherein The water content of the water-soluble film is 3 to 15% by mass. 8 . A package comprising the water-soluble film according to claim 1 . 9 . A food package comprising the package according to claim 8 and a food packaged in the package. 10 . An external preparation package comprising the package according to claim 8 or 9 and an external preparation for skin and / or hair enclosed in the package. 11 . An animal cleaning agent package comprising the package according to claim 8 and the animal cleaning agent enclosed in the package.

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