Water-soluble film for packaging liquid detergent and liquid detergent package

Abstract

To provide a water-soluble film for liquid detergent package, which can form an excellent package, without damaging temporal tension of a water-soluble film even in a state where a liquid detergent is packaged.SOLUTION: A water-soluble film for package containing polyalcohol (Y) formed by containing a polyvinyl alcohol-based resin (A) and a polyalcohol (X), in which when a content ratio of the polyalcohol (X) to a polyvinyl alcohol-based resin (A) is set to x wt.%, and a content ratio of the polyalcohol (Y) in the liquid detergent is set to y wt.%, the following formula (1) is satisfied. x>y (1).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a water-soluble film for packaging liquid detergent, containing a polyvinyl alcohol-based resin (hereinafter, polyvinyl alcohol may be abbreviated as PVA) as a main component. More specifically, the present invention relates to a water-soluble film for packaging liquid detergent, which can form a good package and does not lose tension of the water-soluble film over time even when the liquid detergent is packaged in the package, and a liquid detergent package using the same. [Background technology]

[0002] PVA-based films are made of PVA-based resins, which are thermoplastic resins that are water-soluble. Their physical properties and texture are significantly different from those of hydrophobic films that are commonly used for packaging, such as polyethylene terephthalate films and polyolefin films.

[0003] Taking advantage of the water solubility of PVA resin, a unit package of various chemicals such as pesticides and detergents has been proposed and used for a wide range of applications. For example, in a unit package of chemicals in which a liquid detergent is placed in a bag made of a PVA resin film, the liquid detergent usually contains about 20 to 30% by weight of polyhydric alcohol.

[0004] Known examples of water-soluble unit packaging bags used for such applications include a water-soluble film obtained by blending 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 with respect to 100 parts by weight of PVA (see, for example, Patent Document 1); and a water-soluble film made of a resin composition containing 20 to 50 parts by weight of a plasticizer (B), 2 to 30 parts by weight of a filler (C), and 0.01 to 2.5 parts by weight of a surfactant (D) with respect to 100 parts by weight of an anionic group-modified PVA-based resin (A) having a 4 wt % aqueous solution viscosity at 20°C of 10 to 35 mPa s, an average degree of saponification of 80.0 to 99.9 mol %, and an anionic group modification amount of 1 to 10 mol % (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2001-329130 A [Patent Document 2] JP 2004-161823 A Summary of the Invention [Problem to be solved by the invention]

[0006] The water-soluble films disclosed in the above Patent Documents 1 and 2 have excellent water solubility and can be used as pharmaceutical packages for packaging liquid detergents and the like. However, when the above water-soluble films are stored as packages, the water-soluble films lose their tension over time, and the packages may end up with poor appearance and feel. Therefore, there has been a demand for a water-soluble film that does not lose its tension over time and can form a good package. In addition, the tension of the water-soluble film is also thought to be affected by the relationship between the composition of the encapsulated liquid detergent and the composition of the water-soluble film, but Patent Documents 1 and 2 above do not take such relationship into consideration at all.

[0007] In view of this background, the present invention provides a water-soluble film for packaging liquid detergent, which can form a good package without losing the tension of the water-soluble film over time even when used to package liquid detergent, and a liquid detergent package in which liquid detergent is packaged in the water-soluble film. [Means for solving the problem]

[0008] However, in light of these circumstances, the present inventors conducted extensive research and discovered that, in a water-soluble film for packaging liquid detergent, which contains a PVA-based resin and a polyhydric alcohol, by making the content ratio of polyhydric alcohol to the PVA-based resin greater than the content ratio of polyhydric alcohol in the liquid detergent, it is possible to obtain a water-soluble film that can form a good package that does not lose its tension over time even when used to package liquid detergent.

[0009] That is, the gist of the present invention relates to a water-soluble film for packaging a liquid detergent containing a polyhydric alcohol (Y), which comprises a PVA-based resin (A) and a polyhydric alcohol (X), and is characterized in that when the content ratio of the polyhydric alcohol (X) to the PVA-based resin (A) is x% by weight and the content ratio of the polyhydric alcohol (Y) in the liquid detergent is y% by weight, the water-soluble film for packaging a liquid detergent satisfies the following formula (1): x>y (1)

[0010] Depending on the liquid detergent package, the tension of the water-soluble film forming the package may be lost over time. It is believed that the cause of this is that the components in the liquid detergent, mainly polyhydric alcohol, migrate into the water-soluble film, causing the water-soluble film to stretch and lose its tension. In contrast, in the present invention, by making the content ratio of polyhydric alcohol contained in the plasticizer in the water-soluble film higher than the content ratio of polyhydric alcohol in the liquid detergent, the polyhydric alcohol does not migrate from the liquid detergent to the water-soluble film, but conversely, the polyhydric alcohol migrates from the water-soluble film to the liquid detergent, causing the water-soluble film to shrink and maintaining the tension of the water-soluble film.

[0011] The present invention further provides a liquid detergent package in which a liquid detergent containing a polyhydric alcohol (Y) is packaged in the above water-soluble film for packaging a liquid detergent. Effect of the Invention

[0012] The water-soluble film for packaging liquid detergent of the present invention has excellent water solubility and is capable of forming a good package that does not lose its tension over time even when used to package liquid detergent, and is particularly useful for unit packaging of liquid detergent.

[0013] When the content (x) of the polyhydric alcohol (X) relative to the PVA resin (A) is 25% by weight or more, the water-soluble film can have a better tension.

[0014] When the content (y) of the polyhydric alcohol (Y) in the liquid detergent is 5 to 50% by weight, precipitation of the surfactant and deterioration of the cleaning performance are suppressed.

[0015] When the PVA resin (A) contains an anionic group-modified PVA resin, the solubility in water is improved.

[0016] When the water content of the water-soluble film is 3 to 15% by weight, the water-soluble film has good flexibility and can suppress the occurrence of blocking. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention will be specifically described below. The water-soluble film for packaging liquid detergent of the present invention contains a PVA-based resin (A) and a polyhydric alcohol (X). More specifically, the present invention relates to a water-soluble film for packaging liquid detergent (hereinafter sometimes referred to as PVA-based film) containing a PVA-based resin (A) and a polyhydric alcohol (X) and used for packaging a liquid detergent containing a polyhydric alcohol (Y). When the content ratio of the polyhydric alcohol (X) in the PVA resin (A) is x% by weight and the content ratio of the polyhydric alcohol (Y) in the liquid detergent is y% by weight, the following formula (1), preferably the following formula (2), particularly preferably the following formula (3), and even more preferably the following formula (4) is satisfied.

[0018] x>y (1) xy≧5 (2) 40≧xy≧8 (3) 30≧xy≧10 (4)

[0019] If the difference between x and y is too small, the tension of the water-soluble film will be lost over time, resulting in a poor appearance and feel.If the difference between x and y is too large, the water-soluble film will be subjected to too much tension, which may cause the bag to break.

[0020] As a method for satisfying the above relationship between x and y, for example, there is a method in which the composition of the components in the water-soluble film and the composition of the components in the liquid detergent are taken into consideration for adjustment.

[0021] First, the PVA resin (A) contained in the PVA film used in the present invention will be described. The PVA resin (A) used in the present invention includes unmodified PVA and modified PVA resins.

[0022] The average saponification degree of the PVA-based resin (A) used in the present invention is preferably 80 mol% or more, particularly 82 to 99.9 mol%, further 85 to 98.5 mol%, and especially 90 to 97 mol%. If the average saponification degree is too small, the solubility of the water-soluble film tends to decrease over time depending on the pH of the drug to be packaged. If the average saponification degree is too large, the solubility in water tends to decrease significantly due to the heat history during film formation. Furthermore, in the present invention, particularly when unmodified PVA is used as the PVA-based resin (A), the average saponification degree is preferably 80 mol% or more, particularly 82 to 99 mol%, and even more preferably 85 to 90 mol%. On the other hand, when modified PVA-based resin is used as the PVA-based resin (A), the average saponification degree is preferably 80 mol% or more, particularly 85 to 99.9 mol%, and even more preferably 90 to 98 mol%. Furthermore, when an anionic group-modified PVA resin is used as the PVA resin (A), the average saponification degree is preferably 85 mol % or more, particularly preferably 88 to 99 mol %, and further preferably 90 to 97 mol %.

[0023] The degree of polymerization of the PVA-based resin (A) of the present invention can generally be represented by the viscosity of an aqueous solution, and the viscosity of a 4% by weight aqueous solution at 20°C is preferably 5 to 50 mPa·s, more preferably 10 to 45 mPa·s, and particularly preferably 15 to 40 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 the viscosity is too high, the aqueous solution viscosity during film formation tends to be high and productivity tends to decrease. The viscosity of a 4% by weight aqueous solution of unmodified PVA at 20°C is preferably 5 to 50 mPa·s, more preferably 10 to 45 mPa·s, and particularly preferably 15 to 40 mPa·s. On the other hand, the viscosity of a 4% by weight aqueous solution of modified PVA at 20°C is preferably 5 to 50 mPa·s, more preferably 10 to 45 mPa·s, and particularly preferably 15 to 40 mPa·s.

[0024] The average degree of saponification is measured in accordance with JIS K 6726 3.5, and the viscosity of a 4% by weight aqueous solution is measured in accordance with JIS K 6726 3.11.2.

[0025] The modified PVA resin may be a nonionic group modified PVA resin, a cationic group modified PVA resin, an anionic group modified PVA resin, etc. Among them, the modified PVA resin used in the present invention is preferably an anionic group modified PVA resin in terms of solubility. The type of anionic group may be, for example, a carboxyl group, a sulfonic acid group, a phosphoric acid group, etc., but in terms of chemical resistance and stability over time, a carboxyl group, a sulfonic acid group, and especially a carboxyl group are preferred.

[0026] In the present invention, the modification amount of the anionic group-modified PVA-based resin is preferably 1 to 10 mol%, more preferably 2 to 9 mol%, particularly preferably 2 to 8 mol%, and especially preferably 3 to 7 mol%. If the modification amount is too small, the solubility in water tends to decrease, while if the modification amount is too large, the productivity of the modified PVA-based resin tends to decrease, the biodegradability tends to decrease, and blocking tends to occur easily, resulting in reduced practical use.

[0027] In the present invention, the PVA resin (A) may be either an unmodified PVA or a modified PVA resin. An unmodified PVA and a modified PVA resin may be used in combination, or two or more resins having different saponification degrees, viscosities, modified species, and amounts may be used in combination. In particular, in the present invention, it is preferable that the PVA resin (A) contains a modified PVA resin, particularly an anionic group-modified PVA resin, from the viewpoint of chemical solution durability. It is also preferable that the PVA resin (A) contains an anionic group-modified PVA resin and an unmodified PVA from the viewpoint of the tension of the water-soluble film over time.

[0028] When a modified PVA resin and an unmodified PVA are used in combination, the content ratio (weight ratio) of the modified PVA resin to the unmodified PVA is preferably 95 / 5 to 60 / 40, particularly preferably 94 / 6 to 70 / 30, and further preferably 93 / 7 to 80 / 20. If the content ratio is too small, the plasticizer tends to bleed out, and if it is too large, blocking tends to occur.

[0029] In addition, when the modified PVA resin and unmodified PVA are used in combination, the unmodified PVA preferably has a 4 wt % aqueous solution viscosity of 5 to 50 mPa·s, more preferably 8 to 45 mPa·s, particularly 12 to 40 mPa·s, and even more preferably 15 to 35 mPa·s, at 20° C. If the viscosity is too low, the mechanical strength of the water-soluble film as a packaging material tends to decrease, whereas if it is too high, the aqueous solution viscosity during film formation tends to be high, resulting in reduced productivity.

[0030] The unmodified PVA can be produced by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester compound.

[0031] 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, etc., and it is preferable to use vinyl acetate. The above vinyl ester compounds may be used alone or in combination of two or more kinds.

[0032] The modified PVA resin can be produced by, for example, copolymerizing the vinyl ester compound with an unsaturated monomer copolymerizable with the vinyl ester compound and then saponifying the copolymer, or by post-modifying unmodified PVA.

[0033] In the present invention, the following unsaturated monomers copolymerizable with the vinyl ester compound may be copolymerized, but when a modified PVA resin is to be obtained, it is necessary to copolymerize an unsaturated monomer having a modifying group as the following monomer. Examples of unsaturated monomers include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene, hydroxyl group-containing α-olefins such as 3-buten-1-ol, 4-penten-1-ol, and 5-hexen-1-ol, and derivatives thereof such as acylated products, unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, and undecylenic acid, salts thereof, monoesters, or dialkyl esters thereof, amides such as diacetone acrylamide, acrylamide, and methacrylamide, olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid, or salts thereof, etc. These can be used alone or in combination of two or more kinds. The content of the copolymerizable monomer is usually 10 mol % or less.

[0034] The modified PVA resin may have a primary hydroxyl group in the side chain, for example, the number of primary hydroxyl groups is usually 1 to 5, preferably 1 to 2, and particularly preferably 1. In particular, it is preferable to have a secondary hydroxyl group in addition to the primary hydroxyl group, for example, a PVA resin having a 1,2-diol structural unit in the side chain, a PVA resin having a hydroxyalkyl group in the side chain, etc. Such a PVA resin having a 1,2-diol structural unit in the side chain can be produced, for example, by (i) a method of saponifying a copolymer of vinyl acetate and 3,4-diacetoxy-1-butene, (ii) a method of saponifying and decarbonating a copolymer of vinyl acetate and vinyl ethylene carbonate, (iii) a method of saponifying and deketalizing a copolymer of vinyl acetate and 2,2-dialkyl-4-vinyl-1,3-dioxolane, (iv) a method of saponifying a copolymer of vinyl acetate and glycerin monoallyl ether, etc.

[0035] The copolymerization method for producing the PVA resin (A) may be any known polymerization method, such as solution polymerization, emulsion polymerization, suspension polymerization, etc., but is usually carried out by a solution polymerization method using a lower alcohol, such as methanol, ethanol, or isopropyl alcohol, as a solvent. In such solution polymerization, the monomers may be charged in the case of a modified PVA resin by first charging the entire amount of the vinyl ester compound and, for example, a part of the unsaturated monomer having a carboxyl group, initiating polymerization, and then adding the remaining unsaturated monomer continuously or in portions during the polymerization period, or by charging the unsaturated monomer having a carboxyl group all at once.

[0036] The polymerization catalyst can be appropriately selected from known polymerization catalysts such as azo catalysts such as azobisisobutyronitrile, and peroxide catalysts such as acetyl peroxide, benzoyl peroxide, lauroyl peroxide, etc., depending on the polymerization method. The polymerization reaction temperature is selected from the range of 50° C. to the boiling point of the polymerization catalyst.

[0037] The saponification is carried out by dissolving the obtained copolymer in alcohol in the presence of a saponification catalyst. Examples of the alcohol include alcohols having 1 to 5 carbon atoms, such as methanol, ethanol, and butanol. The concentration of the copolymer in the alcohol is selected from the range of 20 to 50% by weight.

[0038] As the saponification catalyst, for example, an alkali catalyst such as an alkali metal hydroxide or alcoholate such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate, or potassium methylate can be used, and an acid catalyst can also be used. The amount of the saponification catalyst used is preferably 1 to 100 millimolar equivalents relative to the vinyl ester compound. These saponification catalysts can be used alone or in combination of two or more kinds.

[0039] In the modified PVA resin, for example, a carboxyl group-modified PVA resin can be produced by any method, and examples of the method include (I) a method in which an unsaturated monomer having a carboxyl group is copolymerized with a vinyl ester compound and then saponified, and (II) a method in which a vinyl ester compound is polymerized in the coexistence of an alcohol, aldehyde, or thiol having a carboxyl group as a chain transfer agent, and then saponified.

[0040] As the vinyl ester compound in the method (I) or (II), those mentioned above can be used, but it is preferable to use vinyl acetate.

[0041] The unsaturated monomer having a carboxyl group in the above method (I) may, for example, be an ethylenically unsaturated dicarboxylic acid (maleic acid, fumaric acid, itaconic acid, etc.), an ethylenically unsaturated dicarboxylic acid monoester (maleic acid monoalkyl ester, fumaric acid monoalkyl ester, itaconic acid monoalkyl ester, etc.), or an ethylenically unsaturated dicarboxylic acid diester (maleic acid dialkyl ester, fumaric acid dialkyl ester, itaconic acid dialkyl ester, etc.) (however, it is necessary that these diesters are converted to a carboxyl group by hydrolysis during saponification of the copolymer). ], or ethylenically unsaturated carboxylic anhydrides (maleic anhydride, itaconic anhydride, etc.), or ethylenically unsaturated monocarboxylic acids ((meth)acrylic acid, crotonic acid, etc.), and their salts, among which maleic acid, maleic acid monoalkyl esters, maleic acid dialkyl esters, maleic acid salts, maleic anhydride, itaconic acid, itaconic acid monoalkyl esters, itaconic acid dialkyl esters, (meth)acrylic acid, etc. are preferably used, and further maleic acid, maleic acid monoalkyl esters, maleic acid dialkyl esters, maleic acid salts, maleic anhydride, and particularly maleic acid monoalkyl esters are preferably used. These can be used alone or in combination of two or more kinds.

[0042] In the above method (II), compounds derived from thiols, which have a particularly large chain transfer effect, are effective, and examples of such compounds include the compounds represented by the following general formulas (1) to (3).

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] Also included are salts of the compounds represented by the above general formulas (1) to (3), specifically, for example, mercaptoacetate, 2-mercaptopropionate, 3-mercaptopropionate, 2-mercaptostearate, etc. These compounds can be used alone or in combination of two or more.

[0047] In addition to the above-mentioned unsaturated monomers having a carboxyl group and vinyl ester compounds, other general monomers may be incorporated in the polymerization to the extent that water solubility is not impaired, and 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, and in addition, (meth)acrylamide, (meth)acrylonitrile, styrene, vinyl chloride, etc. These may be used alone or in combination of two or more kinds.

[0048] The method for producing the carboxyl group-modified PVA-based resin is not limited to the above-mentioned method. For example, a method in which a PVA-based resin (partially saponified or completely saponified product) is post-reacted with a carboxyl group-containing compound having a functional group reactive with a hydroxyl group, such as a dicarboxylic acid, an aldehyde carboxylic acid, or a hydroxycarboxylic acid, can also be used.

[0049] Furthermore, when a sulfonic acid-modified PVA-based resin modified with a sulfonic acid group is used, the resin can be produced by, for example, a method in which a copolymerization component such as vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, or 2-acrylamide-2-methylpropanesulfonic acid is copolymerized with a vinyl ester-based compound and then saponified, or a method in which vinyl sulfonic acid or a salt thereof, 2-acrylamide-2-methylpropanesulfonic acid or a salt thereof, or the like is subjected to Michael addition to a PVA-based resin.

[0050] On the other hand, methods for post-modifying the unmodified PVA include methods in which the unmodified PVA is converted into an acetoacetate, acetal, urethanized, etherified, grafted, phosphoric acid ester, or oxyalkylenated.

[0051] In the water-soluble film of the present invention, when the film is used to prepare a liquid detergent package, the PVA resin (A) contains a polyhydric alcohol (X) as a plasticizer in order to impart flexibility to the water-soluble film. Although only one type of polyhydric alcohol (X) can be used, it is preferable to use at least two types in combination.

[0052] One of the polyhydric alcohols (X) is a polyhydric alcohol (X1) (hereinafter, sometimes abbreviated as polyhydric alcohol (X1)) having a melting point of 80°C or higher, and the other is a polyhydric alcohol (X2) (hereinafter, sometimes abbreviated as polyhydric alcohol (X2)) having a melting point of 50°C or lower.

[0053] As the polyhydric alcohol (X1) having a melting point of 80° C. or higher, many sugar alcohols, monosaccharides, and polysaccharides can be used. Among them, for example, dihydric alcohols such as salicyl alcohol (83° C.), catechol (105° C.), resorcinol (110° C.), hydroquinone (172° C.), bisphenol A (158° C.), bisphenol F (162° C.), and neopentyl glycol (127° C.), trihydric alcohols such as phloroglucinol (218° C.), erythritol (121° C.), threitol (88° C.), and the like can be used. ℃), tetrahydric alcohols such as pentahydric alcohols such as xylitol (92 ° C), arabitol (103 ° C), fucitol (153 ° C), glucose (146 ° C), fructose (104 ° C), etc., hexahydric alcohols such as mannitol (166 ° C), sorbitol (95 ° C), inositol (225 ° C), etc., octahydric alcohols such as lactitol (146 ° C), sucrose (186 ° C), trehalose (97 ° C), etc., and nonahydric or higher alcohols such as maltitol (145 ° C). These can be used alone or in combination of two or more kinds. The numbers in parentheses indicate the melting points. Among the above, from the viewpoint of the tensile strength of the water-soluble film, those having a melting point of 85° C. or more, particularly 90° C. or more are preferred. The upper limit of the melting point is preferably 300° C., particularly 200° C.

[0054] Furthermore, in the present invention, the polyhydric alcohol (X1) preferably has 4 or more hydroxyl groups in one molecule in terms of compatibility with the PVA resin (A), more preferably 5 to 10 hydroxyl groups, and particularly preferably 6 to 8 hydroxyl groups in one molecule. Specific examples of suitable polyhydric alcohols include sorbitol, sucrose, and trehalose.

[0055] In the present invention, the polyhydric alcohol (X1) preferably has a molecular weight of 150 or more, more preferably 160 to 500, and particularly preferably 180 to 400, from the viewpoint of tension of the water-soluble film. Specific examples of suitable polyhydric alcohols include sorbitol and sucrose.

[0056] On the other hand, examples of the polyhydric alcohol (X2) having a melting point of 50°C or less include aliphatic alcohols, such as, 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 alcohols such as polyethylene glycols having a molecular weight of 2000 or less, and trihydric or higher alcohols such as glycerin (18°C), diglycerin, and triethanolamine (21°C). These can be used alone or in combination of two or more kinds. The parentheses indicate the melting point. In terms of the flexibility of the water-soluble film, it is preferable that the melting point is 30°C or less, particularly 20°C or less. The lower limit of the melting point is usually -80°C, preferably -10°C, and particularly preferably 0°C.

[0057] Furthermore, in the present invention, among the polyhydric alcohols (X2), those having 4 or less hydroxyl groups, particularly 3 or less hydroxyl groups in one molecule are preferred in that the flexibility at around room temperature (25° C.) can be easily controlled. Specifically, for example, glycerin is preferred.

[0058] In the present invention, the polyhydric alcohol (X2) preferably has a molecular weight of 100 or less, more preferably 50 to 100, and particularly preferably 60 to 95, in order to easily control flexibility. Specifically, for example, glycerin is suitable.

[0059] In the present invention, a plasticizer (X3) other than the polyhydric alcohols (X1) and (X2) can be used in combination, and examples of such plasticizers (X3) include alcohols such as trimethylolpropane (58°C), diethylene glycol monomethyl ether, cyclohexanol, carbitol, and 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, ketones such as cyclohexanone, amines such as monoethanolamine, triethanolamine, ethylenediamine, and imidazole compounds, 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.

[0060] In the present invention, the content (x) of the polyhydric alcohol (X) relative to the PVA-based resin (A) is preferably 25% by weight or more, particularly 27-70% by weight, more particularly 30-60% by weight, and even more particularly 35-50% by weight. If the content of the polyhydric alcohol (X) is too low, the tension of the water-soluble film tends to be lost over time when the liquid detergent is packaged in the package. If the content is too high, the mechanical strength tends to decrease.

[0061] Furthermore, the content ratio (X1 / X2) of the above polyhydric alcohol (X1) and polyhydric alcohol (X2) is preferably 0.1 to 5 by weight, particularly 0.2 to 4.5, further preferably 0.5 to 4, and particularly preferably 0.7 to 3. If the content ratio is too small, the water-soluble film tends to be too soft and tends to be prone to blocking, whereas if the content ratio is too large, the water-soluble film tends to be too hard and tends to be brittle in a low-humidity environment.

[0062] The content of the polyhydric alcohol (X1) and the polyhydric alcohol (X2) is preferably 5 to 40 parts by weight, more preferably 8 to 30 parts by weight, and particularly preferably 10 to 25 parts by weight of the polyhydric alcohol (X1), and preferably 5 to 40 parts by weight, more preferably 10 to 35 parts by weight, and particularly preferably 15 to 30 parts by weight of the polyhydric alcohol (X2), relative to 100 parts by weight of the PVA resin (A). If the amount of polyhydric alcohol (X1) is too small, the water-soluble film tends to be too soft and prone to blocking, whereas if the amount is too large, the water-soluble film tends to be too hard and prone to brittleness in a low-humidity environment. If the amount of polyhydric alcohol (X2) is too small, the water-soluble film tends to be too hard and prone to brittleness in a low-humidity environment, whereas if the amount is too large, the water-soluble film tends to be too soft and prone to blocking.

[0063] Furthermore, the total amount of the polyhydric alcohol (X1) and the polyhydric alcohol (X2) is preferably 70% by weight or more, more preferably 80% by weight or more, particularly preferably 87% by weight or more, even more preferably 90% by weight or more, and even more preferably 95% by weight or more, based on the total amount of the polyhydric alcohol (X). It is particularly preferable that the entire polyhydric alcohol (X) is composed only of the polyhydric alcohol (X1) and the polyhydric alcohol (X2). If the total amount of the polyhydric alcohols (X1) and (X2) is too small, the mechanical strength tends to decrease.

[0064] In the present invention, a filler (B), a surfactant (C), and the like may further be contained, if necessary.

[0065] The filler (B) used in the present invention is contained for the purpose of blocking resistance, and specific examples include inorganic fillers and organic fillers, among which organic fillers are preferred. The average particle size is preferably 0.1 to 20 μm, and more preferably 0.5 to 15 μm. The average particle size can be measured, for example, by a laser diffraction type particle size distribution measuring device.

[0066] Such inorganic fillers preferably have an average particle size of 1 to 10 μm. If the average particle size is too small, the water-soluble film tends to have less dispersibility in water, whereas if the average particle size is too large, pinholes tend to form when the water-soluble film is stretched during molding and processing, or the appearance tends to deteriorate.

[0067] Specific examples of inorganic fillers include talc, clay, silicon dioxide, diatomaceous earth, kaolin, mica, asbestos, gypsum, graphite, glass balloons, 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 spheres, bentonite, montmorillonite, copper powder, sodium sulfate, potassium sulfate, zinc sulfate, copper sulfate, iron sulfate, magnesium sulfate, aluminum sulfate, aluminum potassium 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, etc. These may be used alone or in combination of two or more.

[0068] 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 even more preferably 0.5 to 5 μm. If the average particle size is too small, the cost tends to be high, and if it is too large, pinholes tend to form when the water-soluble film is stretched during molding and processing.

[0069] 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. In particular, biodegradable resins such as polymethyl (meth)acrylate-based resins, polystyrene-based resins, and starch are preferably used. These may be used alone or in combination of two or more.

[0070] Examples of the starch include raw starch (corn starch, potato starch, sweet potato starch, wheat starch, kissaba starch, sago starch, tapioca starch, sorghum starch, rice starch, bean starch, kudzu starch, bracken starch, lotus starch, water chestnut starch, etc.), physically modified starch (α-starch, fractionated amylose, moist heat treated starch, etc.), enzyme modified starch (hydrolyzed dextrin, enzymatically decomposed dextrin, amylose, etc.), chemically decomposed modified starch (acid treated starch, hypochlorite oxidized starch, dialdehyde starch, etc.), chemically modified starch derivatives (esterified starch, etherified starch, cationized starch, crosslinked starch, etc.). These can be used alone or in combination of two or more kinds. Among them, raw starch, especially corn starch and rice starch, are preferably used from the viewpoints of availability and economy.

[0071] The content of the filler (B) is preferably 1 to 30 parts by weight, more preferably 2 to 25 parts by weight, and particularly preferably 2.5 to 20 parts by weight, based on 100 parts by weight of the PVA resin (A). If the content is too low, blocking resistance tends to decrease, while if the content is too high, pinholes tend to form when the water-soluble film is stretched during molding.

[0072] The surfactant (C) used in the present invention is contained for the purpose of improving the peelability from the cast surface during the production of a water-soluble film, and includes nonionic surfactants, cationic surfactants, anionic surfactants, etc. For example, nonionic surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylnonyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyalkylene alkyl ether phosphate monoethanolamine salt, polyoxyethylene lauryl amino ether, polyoxyethylene stearyl amino ether, etc., are included, and one or more of them are used in combination. Among them, polyoxyalkylene alkyl ether phosphate monoethanolamine salt and polyoxyethylene lauryl amino ether are preferred in terms of production stability.

[0073] The content of the surfactant (C) is preferably 0.01 to 3 parts by weight, more preferably 0.1 to 2.5 parts by weight, and particularly preferably 0.5 to 2 parts by weight, based on 100 parts by weight of the PVA resin (A). If the content is too low, the peelability between the casting surface of the film-forming device and the water-soluble film formed tends to decrease, leading to a decrease in productivity, whereas if the content is too high, problems such as a decrease in adhesive strength during sealing when the water-soluble film is used as a package tend to occur.

[0074] In the present invention, it is also possible to further contain other water-soluble polymers (e.g., sodium polyacrylate, polyethylene oxide, polyvinylpyrrolidone, dextrin, chitosan, chitin, methylcellulose, hydroxyethylcellulose, etc.), fragrances, rust inhibitors, colorants, bulking agents, defoamers, ultraviolet absorbers, fluorescent brighteners, liquid paraffins, bitter components (e.g., denatonium benzoate, etc.), etc., within the scope of the invention. These can be used alone or in combination of two or more kinds.

[0075] In the present invention, it is preferable to add an antioxidant from the viewpoint of suppressing yellowing. Examples of such antioxidants include sulfites such as sodium sulfite, potassium sulfite, calcium sulfite, and ammonium sulfite, tartaric acid, ascorbic acid, sodium thiosulfate, catechol, and Rongalite, among which sulfites, particularly sodium sulfite, are preferred. The amount of such an antioxidant added 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, per 100 parts by weight of the PVA resin (A).

[0076] In the present invention, a PVA resin composition containing the PVA resin (A) and polyhydric alcohol (X), and further containing a filler (B) and a surfactant (C) as required, is obtained as described above, and the PVA resin composition is dissolved or dispersed in water to prepare a film-forming raw material, which is then formed into a PVA film (water-soluble film). For the film formation, for example, a melt extrusion method or a casting method can be used, and the casting method is preferred from the viewpoint of the accuracy of the film thickness.

[0077] In the present invention, the casting method is carried out, for example, as follows. As the dissolution method, normal temperature dissolution, high temperature dissolution, pressurized dissolution, etc. are usually adopted, among which high temperature dissolution and pressurized dissolution are preferred from the viewpoints of small amount of undissolved matter and excellent productivity. The dissolution temperature is usually 80 to 100° C., preferably 90 to 100° C. in the case of high-temperature dissolution, and usually 80 to 130° C., preferably 90 to 120° C. in the case of pressure dissolution. The dissolution time is usually 1 to 20 hours, preferably 2 to 15 hours, and more preferably 3 to 10 hours. If the dissolution time is too short, undissolved materials tend to remain, and if it is too long, productivity tends to decrease.

[0078] In the dissolving step, examples of the stirring blades include a paddle, a full zone, a max blend, a twister, an anchor, a ribbon, and a propeller. Further, after dissolution, the obtained PVA-based resin aqueous solution is subjected to a defoaming treatment, and examples of such a defoaming method include static defoaming, vacuum defoaming, twin-screw extrusion defoaming, etc. Among them, static defoaming and twin-screw extrusion defoaming are preferred. The temperature for the static defoaming is usually 50 to 100° C., preferably 70 to 95° C., and the defoaming time is usually 2 to 30 hours, preferably 5 to 20 hours.

[0079] In the casting method, for example, water is added to PVA resin (A) (powder) to obtain a PVA resin aqueous solution, and polyhydric alcohol (X) and other ingredients are added to obtain an aqueous dispersion or solution of a PVA resin composition. Alternatively, water is added to a PVA resin composition containing PVA resin (A), polyhydric alcohol (X) and various ingredients to obtain an aqueous dispersion or solution of a PVA resin composition. The solid content concentration of the aqueous dispersion or solution of the PVA resin composition is preferably 10 to 50% by weight, particularly 15 to 40% by weight, and more preferably 20 to 35% by weight. If the concentration is too low, the productivity of the water-soluble film tends to decrease, and if the concentration is too high, the viscosity becomes too high, which requires a long time to defoam the dope and tends to cause die lines during the formation of the water-soluble film. Furthermore, if the temperature of the metal surface of the endless belt or drum roll is too low, it tends to take a long time to dry, and if it is too high, it tends to cause foaming during the film formation.

[0080] The above-mentioned aqueous dispersion or solution is passed through a slit in a T-die or the like, cast onto a casting surface such as the metal surface of an endless belt or drum roll, or the surface of a plastic substrate such as a polyethylene terephthalate film, dried, and further heat-treated as necessary to obtain the PVA-based film (water-soluble film) of the present invention. For example, the film formation can be performed under the following film formation conditions.

[0081] The temperature of the discharge section for the aqueous dispersion or solution of the PVA-based resin composition is preferably 60 to 98° C., particularly 70 to 95° C. If the temperature is too low, the drying time tends to be long and the productivity tends to decrease, whereas if the temperature is too high, foaming and the like tends to occur.

[0082] In the film formation, the film formation speed is preferably 3 to 80 m / min, particularly preferably 5 to 60 m / min, and further preferably 8 to 50 m / min. The heat treatment can be performed using a heated roll, but other methods include floating and far-infrared treatment. In particular, using a heated roll is preferable from the viewpoint of productivity. The heat treatment temperature is preferably 50 to 150°C, and more preferably 70 to 130°C, and the heat treatment time is preferably 1 to 60 seconds, and more preferably 3 to 50 seconds, and even more preferably 5 to 40 seconds.

[0083] Alternatively, an aqueous dispersion or solution of the PVA-based resin composition can be cast onto a plastic substrate such as a polyethylene terephthalate film or a polyethylene film or onto a metal substrate using an applicator, and then dried to obtain a PVA-based film (water-soluble film).

[0084] The thickness of the PVA-based film is appropriately selected depending on the application, etc., but is preferably 10 to 120 μm, more preferably 15 to 110 μm, and particularly preferably 20 to 100 μm. If the thickness is too thin, the mechanical strength of the PVA-based film tends to decrease, while if the thickness is too thick, the dissolution rate in water tends to decrease, and the film formation efficiency also tends to decrease.

[0085] 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, it tends to become difficult to control the slackness and film thickness.

[0086] 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 take time and effort to switch the PVA-based film, and if it is too long, it tends to become too heavy and have a poor appearance due to tight winding.

[0087] The surface of the PVA-based film may be plain (smooth); however, from the viewpoints of blocking resistance, slipperiness during processing, reduced adhesion between products, and appearance, it is also preferable to provide one or both sides of the PVA-based film with an uneven surface treatment such as an embossed pattern, a fine uneven pattern, or a special engraved design. In such uneven processing, the processing temperature is usually 60 to 150° C., and preferably 80 to 140° C. The processing pressure is usually 2 to 8 MPa, and preferably 3 to 7 MPa. The processing time, which depends on the processing pressure and the film-forming speed, is usually 0.01 to 5 seconds, and preferably 0.1 to 3 seconds. If necessary, after the unevenness processing, a cooling treatment may be carried out in order to prevent unintended stretching of the PVA film due to heat.

[0088] In the present invention, the water content of the obtained PVA film (water-soluble film) is preferably 3 to 15% by weight, particularly 5 to 14% by weight, and more preferably 6 to 13% by weight, from the viewpoints of mechanical strength and sealing property. If the water content is too low, the PVA film tends to become too hard, and if it is too high, blocking tends to occur easily. The water content can be adjusted to such a level by appropriately setting the drying conditions and humidity control conditions. The moisture content is measured in accordance with JIS K 6726 3.4, and the obtained value of the volatile matter is regarded as the moisture content.

[0089] In the present invention, the film formation is preferably carried out in an environment of, for example, 10 to 35° C., particularly 15 to 30° C. The humidity is usually 70% RH or less.

[0090] In the present invention, the obtained PVA-based film can be wound around a core tube (S1) to form a film roll. The obtained film roll can be supplied as a product as it is, but is preferably wound around a core tube (S2) having a length corresponding to the width of the PVA-based film of the desired size and supplied as a film roll.

[0091] The core tube (S1) around which the PVA film is wound is cylindrical and its material can be appropriately selected from metal, plastic, etc., but metal is preferable in terms of robustness and strength. The inner diameter of the core tube (S1) is preferably from 3 to 30 cm, and more preferably from 10 to 20 cm. The wall thickness of the core tube (S1) is preferably from 1 to 30 mm, and more preferably from 2 to 25 mm. The length of the core tube (S1) must be longer than the width of the PVA film, and it is preferable that it protrudes from the end of the film roll by 1 to 50 cm.

[0092] The core tube (S2) is cylindrical and may be made of any material such as paper, metal, plastic, etc., but is preferably made of paper in terms of light weight and ease of handling. The inner diameter of the core tube (S2) is preferably from 3 to 30 cm, and more preferably from 10 to 20 cm. The wall thickness of the core tube (S2) is preferably from 1 to 30 mm, and more preferably from 3 to 25 mm. The length of the core tube (S2) may be equal to or greater than the width of the PVA film of the product, and is preferably equal to or 50 cm longer.

[0093] When being wound around the core tube (S2), the PVA film is slit to a desired width. For such slitting, a shear blade or a razor blade is used, but it is preferable to use a shear blade in terms of smoothness of the slit cross section.

[0094] In the present invention, the obtained film roll is wrapped in a wrapping film made of a water vapor barrier resin. The type of such a film is not particularly limited, but it is preferable that the film has a moisture permeability of 10 g / m 2 ·24hr (measured according to JIS Z 0208) or less can be used. Specific examples include single layer films of high density polyethylene, low density polyethylene, polypropylene, polyester, polyvinylidene chloride coated polypropylene, glass vapor deposition polyester, etc., or laminated films of these, or laminated films with split cloth, paper, nonwoven fabric, etc. Examples of laminated films include laminated films of glass vapor deposition polyester and polyethylene, and laminated films of polyvinylidene chloride coated polypropylene and polyethylene, etc.

[0095] It is preferable to treat such a film with an antistatic agent in order to prevent the inclusion of foreign matter. The antistatic agent may be kneaded into the film or coated on the surface. In the case of kneading, the amount is about 0.01 to 5% by weight relative to the resin, and in the case of surface coating, the amount is 0.01 to 1 g / m 2 A certain degree of antistatic agent is used. As the antistatic agent, for example, alkyldiethanolamine, polyoxyethylene alkylamine, higher fatty acid alkanolamide, sorbitan fatty acid ester, etc. are used.

[0096] Next, it is preferable to wrap the film roll in a packaging film made of a water vapor barrier resin, and then further wrap it in a packaging film made of an aluminum material. Examples of such films include aluminum foil, laminated films of aluminum foil and moisture-resistant plastic film (for example, a laminated film of aluminum foil and polyethylene film), laminated films of aluminum vapor-deposited film and moisture-resistant plastic film (for example, a laminated film of aluminum vapor-deposited polyester film and polyethylene film), laminated films of alumina vapor-deposited film and moisture-resistant plastic film (for example, a laminated film of alumina vapor-deposited polyester film and polyethylene film), and the like. In the present invention, laminated films of aluminum foil and polyolefin film and laminated films of aluminum vapor-deposited film and polyolefin film are particularly useful, and laminated films having a composition of oriented polypropylene film / polyethylene film / aluminum foil / polyethylene film and laminated films having a composition of oriented polypropylene film / low-density polyethylene film / aluminum foil are particularly useful. For packaging, the product is sequentially wrapped in an inner film made of a water vapor barrier resin and an outer film made of an aluminum material, and the excess portion in the width direction is then pushed into the core tube.

[0097] In order to prevent scratches on the ends of the film roll of the present invention and adhesion of foreign matter such as dirt, protective pads having core tube through holes can be attached to both ends of the film roll directly or after wrapping the film roll in a wrapping film. The protective pad is practically in the form of a disk-shaped sheet or film that matches the film roll. To enhance the protective effect, it is better to add a cushioning function such as a foam, woven fabric, or nonwoven fabric. Also, to protect the film roll from moisture, a desiccant can be enclosed separately, or laminated or mixed into 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.

[0098] Examples of the protective pad containing the desiccant include those in which a desiccant or water absorbent such as calcium chloride, silica gel, molecular sieves, sugars, particularly sugars with high osmotic pressure, or water-absorbent resin is dispersed, impregnated, coated and dried in a moldable material such as natural celluloses, synthetic celluloses, glass cloth, or nonwoven fabric to form a moisture-absorbing layer, and those in which the desiccant or water absorbent is sandwiched between the above-mentioned moldable materials or thermoplastic resin films such as polyester film, polyethylene film, polypropylene film, or Teflon (registered trademark) film. Examples of commercially available sheet-type desiccants include "ID Sheet" manufactured by ID Co., Ltd., "Arrow Sheet" and "Zeo Sheet" manufactured by Shinagawa Kasei Co., Ltd., and "Hi Sheet Dry" manufactured by Hi Sheet Kogyo Co., Ltd.

[0099] The film roll wrapped by such a means is preferably stored or transported in a so-called suspended state, supported by providing brackets (support plates) on both end protrusions of the core tube or by placing the end protrusions on a stand, without touching the ground. Brackets are used when the width of the film is relatively small, and stands are used when the width of the film is relatively large. The bracket is made of plywood or plastic plate, and its size is sufficient as long as all four sides are larger than the diameter of the film roll.

[0100] A pair of brackets are arranged upright facing each other on the core tube protruding portions at both ends of the film roll, and are fitted to the film roll. The fitting may be performed by providing a hole in the center of the bracket that is slightly larger than the diameter of the core tube, or by hollowing out a U-shape from the top to the center of the bracket to make it easier to insert the core tube.

[0101] The film roll supported by the brackets is stored or transported in a carton such as a cardboard box, and when a rectangular bracket is used, it is preferable to cut off the four corners to facilitate storage operations. In addition, to prevent the pair of brackets from wobbling, it is advantageous to secure the two together with binding tape. At that time, it is also practical to provide a tape slippage prevention groove of approximately the same width as the tape on the side (thickness) of the bracket to prevent the tape from moving or loosening.

[0102] When storing or transporting the wrapped film roll, it is desirable to avoid extremely high or low temperatures and low or high humidity conditions. Specifically, a temperature of 10 to 30° C. and a humidity of 40 to 75% RH are preferable.

[0103] <Liquid detergent> Thus, a water-soluble film for packaging liquid detergent is obtained. In the present invention, when the content ratio of polyhydric alcohol (X) relative to the PVA resin (A) is x% by weight and the content ratio of polyhydric alcohol (Y) in the liquid detergent is y% by weight, it is necessary that the above formula is satisfied.

[0104] The content (x) of the polyhydric alcohol (X) in the PVA resin (A) is preferably 25% by weight or more, particularly 27-70% by weight, further 30-60% by weight, and especially 35-50% by weight. The content (y) of the polyhydric alcohol (Y) in the liquid detergent is preferably 5-50% by weight, further 10-45% by weight, and especially 15-35% by weight. If the content (y) is too small, the surfactant tends to precipitate, and if it is too high, the cleaning properties tend to decrease.

[0105] Here, the polyhydric alcohol (Y) in the liquid detergent typically includes dihydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, 1,2-pentanediol, 1,2-hexanediol, 1,6-hexanediol, etc., trihydric alcohols such as glycerin, tetrahydric alcohols such as erythritol and pentaerythritol, hexahydric alcohols such as sorbitol, etc., and the content of the polyhydric alcohol (Y) mentioned above is the total amount of these polyhydric alcohols.

[0106] Furthermore, in addition to the above-mentioned polyhydric alcohols, which mainly act as stabilizers, liquid detergents often contain other ingredients such as solvents such as water and monohydric alcohols, surfactants such as soaps and fatty acid salts, dispersants, sequestering agents, fragrances, enzymes, water softeners, fluorescent brightening agents, colorants, bleaches, foam regulators, anti-redeposition agents, and pH adjusters.

[0107] The liquid detergent preferably has a pH value of 6 to 12 when dissolved or dispersed in water, and more preferably 7 to 11. The liquid detergent also preferably has a water content of 15% by weight or less, and more preferably 0.1 to 10% by weight, and even more preferably 0.1 to 7% by weight, which prevents the water-soluble film from gelling or becoming insoluble and provides excellent water solubility. The pH value is measured in accordance with JIS K 3362 8.3. The water content is measured in accordance with JIS K 3362 7.21.3.

[0108] <Liquid detergent packaging> The liquid detergent package of the present invention is a package made of a water-soluble film and contains a liquid detergent. The size of the liquid detergent package is usually 10 to 50 mm in length, preferably 20 to 40 mm. The thickness of the package made of a water-soluble film is usually 10 to 120 μm, preferably 15 to 110 μm, more preferably 20 to 100 μm. The amount of the liquid detergent contained is usually 5 to 50 mL, preferably 10 to 40 mL.

[0109] The liquid detergent package of the present invention has a smooth surface. Furthermore, in terms of blocking resistance, slipperiness during processing, reduced adhesion between products (packages), and appearance, the outer surface of the package (water-soluble film) may be unevenly processed, such as with an embossed pattern, a fine uneven pattern, or a specially engraved pattern. The liquid detergent package of the present invention maintains its shape containing the liquid detergent during storage. When used (during washing), the package (water-soluble film) comes into contact with water, causing the package to dissolve and the liquid detergent contained therein to flow out of the package.

[0110] In the present invention, when the liquid detergent is packaged using the water-soluble film for packaging a liquid detergent to form a liquid detergent package, a known method can be adopted, such as (1) a heat sealing method, (2) a water sealing method, or (3) a glue sealing method, among which (2) a water sealing method is versatile and advantageous. EXAMPLES

[0111] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples as long as it does not depart from the gist of the present invention. In the examples, "parts" and "%" are by weight.

[0112] The following PVA-based resins were prepared: Carboxyl group-modified PVA (A1): 4% aqueous solution viscosity at 20°C 22 mPa s, average degree of saponification 96 mol%, modification amount with maleic acid monomethyl ester 4.0 mol% Carboxyl group-modified PVA (A2): 4% aqueous solution viscosity at 20°C 22 mPa s, average degree of saponification 94 mol%, modification amount with maleic acid monomethyl ester 2.0 mol% Unmodified PVA (A3): 4% aqueous solution viscosity at 20°C is 18 mPa·s, average degree of saponification is 88 mol% Unmodified PVA (A4): 4% aqueous solution viscosity at 20°C: 22 mPa·s, average degree of saponification: 88 mol% Unmodified PVA (A5): 4% aqueous solution viscosity at 20°C: 5 mPa·s, average degree of saponification: 88 mol%

[0113] The following polyhydric alcohols were prepared: Sorbitol (X1) Glycerin (X2) Trimethylolpropane (X3)

[0114] <Example 1> [Preparation of PVA-based film] 100 parts of carboxyl-modified PVA (A1) as the PVA-based resin (A), 20 parts of sorbitol (X1) and 20 parts of glycerin (X2) as the polyhydric alcohol (X) serving as the plasticizer, 8 parts of starch (average particle size 20 μm) as the filler (B), 2 parts of polyoxyalkylene alkyl ether phosphate ester monoethanolamine salt as the surfactant (C), and water were mixed and dissolved to obtain a PVA aqueous solution (solid concentration 25%) in which starch was dispersed (content ratio of polyhydric alcohol to PVA-based resin: 40%). The resulting PVA aqueous solution was degassed at 80° C. and cooled to 40° C. The PVA aqueous solution was cast onto a polyethylene terephthalate film and dried by passing through a 3 m drying chamber (105° C.) at a speed of 0.350 m / min to obtain a PVA-based film (water-soluble film) with a thickness of 94 μm.

[0115] [Preparation of liquid detergent packaging] The PVA film obtained above was used to produce a package using an Engel packaging machine according to the following procedure. That is, a PVA-based film (bottom film) was fixed on the mold (package to be molded: length 45 mm, width 42 mm, height 30 mm) at the bottom of the above-mentioned manufacturing machine, and a PVA-based film (top film) was also fixed to the top of the device. The bottom film was heated for 10 seconds with a dryer generating hot air at 90 ° C., and the bottom film was vacuum molded into the mold. Then, 20 mL of liquid detergent (containing 5.4% glycerin, 22.6% propylene glycol, and 10.4% water (content of polyhydric alcohol in liquid detergent: 28%)) packaged in P&G's "Ariel Power Gel Ball" was poured into the molded PVA-based film. 1.5 g of water was applied to the top film, and the top film and bottom film were pressed together. After pressing for 30 seconds, the vacuum was released to obtain a package. The obtained packages were evaluated as follows, and the evaluation results are shown in Table 1.

[0116] (Evaluation of tension of water-soluble film) The package obtained above was conditioned for 2 hours in an environment of 23°C and 40% RH, and the height (αmm) of the package when placed in a naturally self-supporting orientation was measured and found to be 30 mm. Next, after the package was prepared, it was left for 1 week in an environment of 40°C and 65% RH, and then left for 1 hour in an environment of 23°C and 50% RH, and the height (βmm) of the package when placed in a naturally self-supporting orientation was measured, and the tension of the water-soluble film of the package was evaluated based on the value (γmm) calculated by the following formula. The smaller the γ value, the better the tension evaluation of the water-soluble film. (Formula) γ=α-β

[0117] <Examples 2 to 12, Comparative Examples 1 to 2> The same procedure as in Example 1 was carried out except for the changes shown in Tables 1 and 2 to obtain a PVA-based film (water-soluble film). For the obtained PVA-based film (water-soluble film), a package was produced in the same manner as in Example 1, and further evaluations were performed in the same manner as in Example 1. The evaluation results are shown in Tables 1 and 2.

[0118] [Table 1]

[0119] [Table 2]

[0120] From the above results, in the case of the package using the water-soluble film of the Example, the content ratio (x) of the polyhydric alcohol relative to the PVA resin in the water-soluble film is greater than the content ratio (y) of the polyhydric alcohol in the liquid detergent, and in such a case, the tension of the water-soluble film was evaluated as good over time even in the package state. In contrast, in the case of the package using the water-soluble film of the Comparative Example, the content ratio (x) was smaller, and therefore the tension evaluation was also poor.

[0121] In the above embodiment, specific embodiments of the present invention are shown, but the above embodiment is merely illustrative and should not be interpreted as being limiting. Various modifications that are obvious to those skilled in the art are intended to be within the scope of the present invention. [Industrial Applicability]

[0122] The water-soluble film for packaging liquid detergent of the present invention has excellent water solubility and is capable of forming a good package that does not lose its tension over time even when used to package liquid detergent, and is useful for unit packaging of liquid detergent.

Claims

1. A water-soluble film for packaging a liquid detergent containing a polyhydric alcohol (Y), comprising a polyvinyl alcohol-based resin (A) and a polyhydric alcohol (X), the polyhydric alcohol (X) contains a polyhydric alcohol (X1) having a melting point of 80 to 300°C and a polyhydric alcohol (X2) excluding propylene glycol having a melting point of -80 to 50°C, the polyhydric alcohol (X) does not contain dipropylene glycol, the content ratio (X1 / X2) of the polyhydric alcohol (X1) to the polyhydric alcohol (X2) is 1 to 5 by weight, and the total amount of the polyhydric alcohol (X1) and the polyhydric alcohol (X2) is 87% by weight or more based on the entire polyhydric alcohol (X); the content (x) of the polyhydric alcohol (X) relative to the polyvinyl alcohol-based resin (A) is 25 to 70% by weight, The water-soluble film for packaging a liquid detergent is characterized in that the content (y) of the polyhydric alcohol (Y) in the liquid detergent is 5 to 50% by weight, the content of the polyhydric alcohol (X) relative to the polyvinyl alcohol-based resin (A) is x% by weight, and the content of the polyhydric alcohol (Y) in the liquid detergent is y% by weight, whereby the following formula (1) is satisfied: x ≧ y (1)

2. The water-soluble film for packaging a liquid detergent according to claim 1, which satisfies the following formula (2): x-y≧5 (2)

3. 3. The water-soluble film for packaging a liquid detergent according to claim 1, wherein the polyvinyl alcohol-based resin (A) contains an anionic group-modified polyvinyl alcohol-based resin.

4. 4. The water-soluble film for packaging a liquid detergent according to claim 1, wherein the water-soluble film has a water content of 3 to 15% by weight.

5. A liquid detergent package comprising a liquid detergent containing a polyhydric alcohol (Y) packaged in the water-soluble film for packaging a liquid detergent according to any one of claims 1 to 4.

6. 6. The liquid detergent package according to claim 5, 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.

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