JP7416030B2 - Water-soluble film and drug packaging - Google Patents

Description

The present invention relates to a water-soluble film (hereinafter sometimes referred to as a PVA-based film) containing a polyvinyl alcohol-based resin (hereinafter, polyvinyl alcohol may be abbreviated as PVA). The present invention relates to a water-soluble film that has good heat-sealability in the heat-sealed portion and has excellent productivity even at low heat-sealing temperatures when forming a package.

PVA-based film is a film made of PVA-based resin that is water-soluble even though it is a thermoplastic resin. Hydrophobic film, which is commonly used for packaging films such as polyethylene terephthalate film and polyolefin film, is They differ greatly in physical properties, texture, etc.

Taking advantage of the water solubility of PVA resin, drug packaging (unit packaging) in which various chemicals such as pesticides and cleaning agents are placed in bags made of PVA resin film has been proposed, and has been used in a wide range of applications. It is used.

A water-soluble unit packaging bag used for such purposes is, for example, made 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 to 100 parts by weight of PVA. A water-soluble film (for example, see Patent Document 1), a viscosity of a 4% aqueous solution at 20°C of 10 to 35 mPs·s, an average degree of saponification of 80.0 to 99.9 mol%, and an anionic group modification amount of 1 to For 100 parts by weight of 10 mol% anionic group-modified PVA resin (A), 20 to 50 parts by weight of plasticizer (B), 2 to 30 parts by weight of filler (C), and 0.0 parts by weight of surfactant (D). Water-soluble films made of resin compositions containing 0.01 to 2.5 parts by weight (for example, see Patent Document 2) are known.

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

However, the water-soluble films disclosed in Patent Documents 1 and 2 have excellent water solubility and can be used as drug packages by packaging liquid detergents, etc. However, the performance of the heat-sealed portion of the package was not considered.

When producing packaging, there is a process of heat-sealing the water-soluble film, and in order to increase the adhesiveness and strength of the heat-sealed part, it is usually done at a very high temperature of 150 to 200 degrees Celsius. I had to heat seal it. However, when heat-sealing, the higher the heat-sealing temperature, the better the adhesion and strength of the heat-sealed part, but on the other hand, heat-sealing at industrial high temperatures requires a large amount of energy. There are also concerns that the solubility of the heat-sealed portion may decrease, resulting in unmelted residue, so if possible, it is recommended to perform the heat-sealing process at a lower temperature than the conventional heat-sealing temperature to ensure good heat-sealing. There is a need for a water-soluble film with properties.

Therefore, in the present invention, when forming a package, the heat-sealing property is excellent, such as the adhesion and strength of the heat-sealed part even at a low heat-sealing temperature, and the productivity is excellent. The present invention provides a water-soluble film, and a drug package in which various drugs are packaged with the water-soluble film.

However, as a result of intensive research in view of such circumstances, the present inventors have found that water-soluble films containing PVA-based resins are heat-sealed at a relatively lower temperature than the normally used heat-sealing temperature. By increasing the breaking strength when peeled off without causing interfacial peeling of the sealed part, we have created a water-soluble film with good heat-sealability and excellent productivity, such as excellent adhesion and strength of the heat-sealed part. They discovered that this is the case and completed the present invention.

That is, the gist of the present invention is a water-soluble film containing a PVA resin (A), which is produced by laminating two water-soluble films that have been conditioned for one day in an environment of 23° C. and 40% RH. After heat-sealing once under the conditions of temperature 140℃, pressure 0.65MPa, time 1.5 seconds, and seal width 1.5mm, when left in an environment of 23℃ and 40% RH for 2 hours, heat sealing was confirmed. It relates to a water-soluble film which has a breaking strength (X1) of 11.0 N/15 mm or more when a portion is peeled off, and which does not peel off at the interface during such peeling, and also contains a PVA-based resin (A). Two water-soluble films that had been conditioned for one day in an environment of 23°C and 40% RH were stacked together, and the temperature was 145°C, the pressure was 0.65 MPa, the time was 1.5 seconds, and the seal width was 1. After heat-sealing once under the conditions of 5 mm, when left in an environment of 23 ° C. and 40% RH for 2 hours, the breaking strength (X2) when peeling off the heat-sealed portion is 11.5 N/15 mm or more, The present invention also relates to a water-soluble film that does not undergo interfacial peeling during such peeling.

Furthermore, the present invention also provides a drug package using the water-soluble film.

The water-soluble film of the present invention has good heat-sealing properties such as excellent adhesiveness and strength of the heat-sealed portion even at low heat-sealing temperatures when forming a package, and has excellent productivity. It can be used for various packaging purposes, and is particularly useful for unit packaging of drugs and the like.

The present invention will be explained in detail below.
The water-soluble film of the present invention is a water-soluble film containing a PVA-based resin (A), and two water-soluble films that have been conditioned for one day at 23°C and 40% RH are laminated together. After heat-sealing once under the conditions of temperature 140℃, pressure 0.65MPa, time 1.5 seconds, and seal width 1.5mm, when left in an environment of 23℃ and 40% RH for 2 hours, heat sealing was confirmed. The breaking strength (X1) when the part is peeled off is 11.0 N/15 mm or more, and there is no interfacial peeling during such peeling, and in particular, this breaking strength is rated 11 in that the package is difficult to tear. It is preferably from .5 to 100 N/15 mm, more preferably from 11.8 to 50 N/15 mm, particularly from 11.9 to 30 N/15 mm, particularly preferably from 12.0 to 20 N/15 mm.

Moreover, the water-soluble film of the present invention is a water-soluble film containing PVA-based resin (A), and two water-soluble films that have been conditioned for one day in an environment of 23° C. and 40% RH. After stacking and heat sealing once under the conditions of temperature 145 ° C, pressure 0.65 MPa, time 1.5 seconds, seal width 1.5 mm, when left in an environment of 23 ° C and 40% RH for 2 hours, The breaking strength (X2) when the heat-sealed part is peeled off is 11.5 N/15 mm or more, and there is no interfacial peeling during such peeling, and in particular, this breaking strength is such that the package is difficult to tear. , 12.0 to 100 N/15 mm, more preferably 12.5 to 50 N/15 mm, particularly 13.0 to 30 N/15 mm, particularly preferably 14.0 to 20 N/15 mm.

If the above-mentioned breaking strength (X1) or (X2) is less than the above-mentioned range, there is a risk that liquid detergent may leak out from the heat-sealed portion when used as a package.

In addition, in the present invention, "no interfacial peeling" means that two water-soluble films do not separate at the adhesive interface, and a part of the film itself is broken while one film is stuck to the other film. In such a case, the heat-sealed portion will be firmly adhered.

Here, the breaking strength at the time of peeling of the heat-sealed portion is measured in accordance with JIS K 7127 (1999). When measuring, the breaking strength is determined by the maximum point test force (N) measured at a tensile speed of 200 mm/min using "Autograph AG-Xplus" manufactured by Shimadzu Corporation (film width 15 mm, distance between chucks 50 mm). .

The water-soluble film of the present invention is produced, for example, as follows.
First, the PVA resin (A) used in the present invention will be explained.
Examples of the PVA resin (A) used in the present invention include unmodified PVA and modified PVA resin.

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

The degree of polymerization of the above PVA resin (A) can generally be expressed by water-soluble viscosity, and the viscosity of a 4% by weight aqueous solution at 20°C is preferably 5 to 50 mPa·s, more preferably 13 to 45 mPa·s. s, particularly preferably 17 to 40 mPa·s. Furthermore, when unmodified PVA is used as the PVA resin (A), the viscosity of a 4% aqueous solution of unmodified PVA at 20°C is preferably 5 to 50 mPa·s, more preferably 13 to 45 mPa·s. s, particularly preferably 17 to 40 mPa·s. When a modified PVA resin is used as the PVA resin (A), the viscosity of a 4% aqueous solution of the modified PVA resin at 20°C is preferably 5 to 50 mPa·s, more preferably 13 to 50 mPa·s. It is preferably 40 mPa·s, particularly 17 to 30 mPa·s. If the viscosity is too small, the mechanical strength of the water-soluble film used as a packaging material tends to decrease, while if it is too large, the viscosity of the aqueous solution during film formation tends to be high, leading to a decrease in productivity.

Note that the above average degree of saponification is measured according to JIS K 6726 3.5, and the 4% by weight aqueous solution viscosity is measured according to JIS K 6726 3.11.2.

Examples of the modified PVA resin used in the present invention include anionic group-modified PVA resin, cationic group-modified PVA resin, nonionic group-modified PVA resin, and the like. Among them, it is preferable to use an anionic group-modified PVA resin from the viewpoint of solubility in water. Examples of the types of anionic groups include carboxyl groups, sulfonic acid groups, phosphoric acid groups, etc., but carboxyl groups, sulfonic acid groups, and especially carboxyl groups are preferred from the viewpoint of chemical resistance and stability over time. .

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

In the present invention, each of the above PVA resins (A) can be used alone, or unmodified PVA and modified PVA resin can be used together, and furthermore, saponification degree, viscosity, modified species, modified amount It is also possible to use two or more types with different properties. Among these, in the present invention, it is preferable that the PVA-based resin (A) contains a modified PVA-based resin. In particular, it is preferable to contain an anionic group-modified PVA resin, or an anionic group-modified PVA resin and unmodified PVA, and it is particularly preferable to contain only an anionic group-modified PVA resin. .

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

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

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

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

Examples of such vinyl ester compounds include vinyl formate, vinyl acetate, vinyl trifluoroacetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl laurate, vinyl versatate, vinyl palmitate, vinyl stearate, and the like. Can be mentioned. Among them, it is preferable to use vinyl acetate as the vinyl ester compound. The above vinyl ester compounds may be used alone or in combination of two or more.

The modified PVA resin can be produced by copolymerizing the above vinyl ester compound and an unsaturated monomer copolymerizable with the vinyl ester compound and then saponifying it, or by post-modifying unmodified PVA. It can be manufactured by etc.

In the present invention, the following unsaturated monomers that can be copolymerized with the above vinyl ester compound may be copolymerized, but when obtaining a modified PVA resin, the following monomers may contain modified groups. It is necessary to copolymerize unsaturated monomers that have Examples of unsaturated monomers include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene, 3-buten-1-ol, 4-penten-1-ol, 5- Derivatives such as hydroxy group-containing α-olefins such as hexen-1-ol and their acylated products, unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, undecylenic acid, etc. Examples include salts, monoesters, dialkyl esters, amides such as diacetone acrylamide, acrylamide, and methacrylamide, olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and meta-allylsulfonic acid, or salts thereof. These can be used alone or in combination of two or more. Note that the content of the copolymerizable monomer is usually 10 mol% or less.

Examples of modified PVA-based resins include those having primary hydroxyl groups in their side chains, such as those having usually 1 to 5, preferably 1 to 2, and particularly preferably 1 primary hydroxyl group. It will be done. In particular, it is preferable to have a secondary hydroxyl group in addition to the primary hydroxyl group, such as a PVA-based resin having a 1,2-diol structural unit in the side chain, a PVA-based resin having a hydroxyalkyl group in the side chain, and the like. PVA resins having 1,2-diol structural units in their side chains can be produced by, for example, (i) a method of saponifying a copolymer of vinyl acetate and 3,4-diacetoxy-1-butene, (ii) acetic acid. A method for saponifying and decarboxylating a copolymer of vinyl and vinyl ethylene carbonate; (iii) a method for saponifying and decarboxylating a copolymer of vinyl acetate and 2,2-dialkyl-4-vinyl-1,3-dioxolane; It can be produced by a method of ketalization, (iv) a method of saponifying a copolymer of vinyl acetate and glycerin monoallyl ether, and the like.

As the polymerization method for producing the PVA resin (A), any known polymerization method can be used, such as solution polymerization, emulsion polymerization, and suspension polymerization, but methanol, ethanol, or isopropyl is usually used. This is carried out by a solution polymerization method using a lower alcohol such as alcohol as a solvent. In the case of a modified PVA resin, the method for charging monomers in such solution polymerization is to first charge the entire amount of the vinyl ester compound and, for example, a portion of the unsaturated monomer having a carboxyl group, and then carry out the polymerization. Any method can be used, such as a method in which the remaining unsaturated monomer is added continuously or in parts during the polymerization period, or a method in which the unsaturated monomer having a carboxyl group is charged all at once. can.

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

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. These can be used alone or in combination of two or more. Further, the concentration of the copolymer in the alcohol is selected from the range of 20 to 50% by weight.

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; It is also possible to use catalysts. The saponification catalyst is preferably used in an amount of 1 to 100 millimole equivalents based on the vinyl ester compound. These saponification catalysts can be used alone or in combination of two or more.

The carboxyl group-modified PVA resin in the above-mentioned modified PVA resin can be produced by any method, for example, by copolymerizing (I) an unsaturated monomer having a carboxyl group and a vinyl ester compound, followed by saponification. and (II) a method in which a vinyl ester compound is polymerized in the presence of an alcohol, aldehyde, thiol, or the like having a carboxyl group as a chain transfer agent, and then saponified.

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

Examples of the unsaturated monomer having a carboxyl group in the method (I) above include ethylenically unsaturated dicarboxylic acids (maleic acid, fumaric acid, itaconic acid, etc.) or ethylenically unsaturated dicarboxylic acid monoesters (maleic acid, etc.). acid monoalkyl esters, fumaric acid monoalkyl esters, itaconic acid monoalkyl esters, etc.), or ethylenically unsaturated dicarboxylic acid diesters (maleic acid dialkyl esters, fumaric acid dialkyl esters, itaconic acid dialkyl esters, etc.) [However, these diesters needs to be converted into a carboxyl group by hydrolysis during saponification of the copolymer. ], or monomers such as ethylenically unsaturated carboxylic anhydrides (maleic anhydride, itaconic anhydride, etc.), or ethylenically unsaturated monocarboxylic acids ((meth)acrylic acid, crotonic acid, etc.), and their monomers. Salt is an example. Among them, it is preferable to use maleic acid, maleic acid monoalkyl ester, maleic acid dialkyl ester, maleic acid salts, maleic anhydride, itaconic acid, itaconic acid monoalkyl ester, itaconic acid dialkyl ester, (meth)acrylic acid, etc. It is preferable to use maleic acid, a maleic acid monoalkyl ester, a maleic acid dialkyl ester, a maleate salt, a maleic anhydride, and particularly a maleic acid monoalkyl ester. These can be used alone or in combination of two or more.

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

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

In addition, the method for producing the carboxyl group-modified PVA resin is not limited to the above method, but may include, for example, adding a hydroxyl group such as dicarboxylic acid, aldehyde carboxylic acid, or hydroxycarboxylic acid to PVA resin (partially saponified product or completely saponified product). It is also possible to carry out a method in which a carboxyl group-containing compound having a reactive functional group is post-reacted.

In addition, when using a sulfonic acid-modified PVA resin modified with a sulfonic acid group, examples thereof include vinylsulfonic acid, styrenesulfonic acid, allylsulfonic acid, metaallylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, etc. A method in which a copolymerization component of sulfonic acid or its salt is copolymerized with a vinyl ester compound and then saponified. It can be manufactured by a method of adding Michael to a resin.

On the other hand, examples of methods for post-modifying the unmodified PVA include methods of converting the unmodified PVA into acetoacetate, acetal, urethane, ether, grafting, phosphoric ester, and oxyalkylen.

In addition, in addition to the above-mentioned unsaturated monomers having carboxyl groups and vinyl ester compounds, other general monomers may be contained in the range that does not impair water solubility, and polymerization may be carried out by containing these monomers. Examples include alkyl esters of ethylenically unsaturated carboxylic acids, allyl esters of saturated carboxylic acids, α-olefins, alkyl vinyl ethers, alkyl allyl ethers, as well as (meth)acrylamide, (meth)acrylonitrile, styrene, and vinyl chloride. etc. can be used. These can be used alone or in combination of two or more.

In the present invention, it is preferable to incorporate a plasticizer (B) into the PVA resin (A) in order to impart flexibility to the water-soluble film when used as a drug package. The plasticizer (B) can be used alone or in combination of at least two types, but in particular, the use of at least two types in combination reduces the toughness of the water-soluble film itself when used as a packaging body. Further, it is preferable because it can be heat-sealed at low temperatures and the strength of the heat-sealed portion is high.

One type of plasticizer (B) is a polyhydric alcohol (b1) having a melting point of 80°C or higher (hereinafter sometimes abbreviated as plasticizer (b1)), and the other type is Polyhydric alcohol (b2) (hereinafter sometimes abbreviated as plasticizer (b2)) with a temperature of 50°C or less is required for toughness during the production of water-soluble films and packaging, and for packaging for liquid detergents. It is preferable in terms of shape stability over time when made into a body and heat sealability at low temperatures.

As the polyhydric alcohol (b1) having a melting point of 80°C or higher, many sugar alcohols, monosaccharides, and polysaccharides can be used, but among them, for example, salicyl alcohol (83°C), catechol (105°C ), dihydric alcohols such as resorcinol (110℃), hydroquinone (172℃), bisphenol A (158℃), bisphenol F (162℃), neopentyl glycol (127℃), phloroglucinol (218℃), etc. Trihydric alcohols, tetrahydric alcohols such as erythritol (121°C), threitol (88°C), pentaerythritol (260°C), xylitol (92°C), arabitol (103°C), fucitol (153°C), glucose (146°C) ), pentahydric alcohols such as fructose (104°C), hexahydric alcohols such as mannitol (166°C), sorbitol (95°C), inositol (225°C), lactitol (146°C), sucrose (186°C), trehalose Examples include octahydric alcohols such as (97°C), and alcohols of 9 or more hydric content such as maltitol (145°C). These can be used alone or in combination of two or more. The numbers in parentheses above indicate the melting point of each compound.
Among the above, those having a melting point of 85° C. or higher, particularly 90° C. or higher are preferred in terms of the tensile strength of the water-soluble film. Note that the upper limit of the melting point is preferably 300°C, particularly 200°C.

Furthermore, in the present invention, the number of hydroxyl groups in one molecule of the plasticizer (b1) is preferably 4 or more in terms of compatibility with the PVA resin, more preferably 5 to 10, and particularly preferably. is 6 to 8, and specific examples include sorbitol, sucrose, trehalose, and the like.

Furthermore, in the present invention, the plasticizer (b1) preferably has a molecular weight of 150 or more, more preferably 160 to 500, particularly preferably 180 to 400, from the viewpoint of the toughness of the water-soluble film. Specifically, suitable examples include sorbitol and sucrose.

On the other hand, as the polyhydric alcohol (b2) having a melting point of 50°C or less, many aliphatic alcohols are applicable, 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℃), tripropylene glycol, dihydric alcohols such as polyethylene glycol with a molecular weight of 2000 or less, trihydric alcohols such as glycerin (18℃), diglycerin, triethanolamine (21℃), etc. Alcohol is an example. In terms of flexibility, the water-soluble film preferably has a melting point of 30°C or lower, particularly 20°C or lower. The lower limit of the melting point is usually -80°C, preferably -10°C, particularly preferably 0°C. These can be used alone or in combination of two or more. The numbers in parentheses above indicate the melting point of each compound.

Furthermore, in the present invention, it is preferable that the number of hydroxyl groups in one molecule of the plasticizer (b2) is 4 or less, particularly 3 or less, since flexibility near room temperature (25°C) can be easily controlled. Preferably, specifically, for example, glycerin or the like is suitable.

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

In the present invention, a plasticizer (b3) other than the above-mentioned plasticizers (b1) and (b2) can also be used in combination, and such plasticizers (b3) include, for example, trimethylolpropane (58°C), diethylene glycol Alcohols such as monomethyl ether, cyclohexanol, carbitol, polypropylene glycol, ethers such as dibutyl ether, carboxylic acids such as stearic acid, oleic acid, linoleic acid, linolenic acid, sorbic acid, citric acid, adipic acid, cyclohexanone, etc. , 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.

In the present invention, the content of the plasticizer (B) is preferably 20 parts by weight or more, particularly 25 to 70 parts by weight, and more preferably 30 to 60 parts by weight, based on 100 parts by weight of the PVA resin (A). It is preferably 35 to 50 parts by weight, especially 35 to 50 parts by weight. If the content of the plasticizer (B) is too small, the toughness of the water-soluble film tends to deteriorate over time when a liquid such as a liquid detergent is packaged into a package. Note that if the amount is too large, mechanical strength tends to decrease.

Regarding the above plasticizer (b1) and plasticizer (b2), the content ratio (b1/b2) is preferably 0.1 to 5, more preferably 0.35 to 4.5, particularly preferably It is 0.4 to 4, more preferably 0.5 to 3.5, particularly preferably 0.7 to 3. If the content weight ratio is too small, the water-soluble film tends to become too soft, the sealing strength at low temperatures tends to decrease, and blocking tends to occur more easily, while if it is too large, the water-soluble film becomes too hard. It tends to become too soft and brittle in low humidity environments.

Furthermore, the content of the plasticizer (b1) and plasticizer (b2) is 5 to 40 parts by weight, more preferably 8 to 40 parts by weight, per 100 parts by weight of the PVA resin (A). It is preferably 30 parts by weight, especially 10 to 25 parts by weight, and the plasticizer (b2) is preferably 5 to 40 parts by weight, more preferably 10 to 35 parts by weight, especially 15 to 30 parts by weight.
If the plasticizer (b1) is too small, the water-soluble film becomes too soft and blocking tends to occur, and if it is too large, the water-soluble film tends to become too hard and becomes brittle in a low humidity environment. be. In addition, if the plasticizer (b2) is too small, the water-soluble film tends to become too hard and becomes brittle in low humidity environments, while if it is too large, the water-soluble film becomes too soft and tends to cause blocking. There is.

Furthermore, the total amount of plasticizer (b1) and plasticizer (b2) is preferably 70% by weight or more, more preferably 80% by weight or more, particularly 87% by weight or more with respect to the entire plasticizer (B). , particularly preferably 90% by weight or more, more preferably 95% by weight or more. Particularly preferred is the case where the plasticizer (B) as a whole consists only of the above-mentioned plasticizer (b1) and plasticizer (b2). If the total amount of such plasticizers (b1) and (b2) is too small, mechanical strength tends to decrease.

In the present invention, a filler (C), a surfactant (D), etc. can be further contained as necessary.

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

It is preferable that such an inorganic filler has an average particle diameter of 1 to 10 μm; if the average particle diameter is too small, the effect of dispersing the water-soluble film in water tends to be small; if it is too large, When a water-soluble film is stretched during molding, it tends to form pinholes and its appearance deteriorates.

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, and calcium carbonate. , whiskered calcium carbonate, magnesium carbonate, dawsonite, dolomite, potassium titanate, carbon black, glass fiber, alumina fiber, boron fiber, processed mineral fiber, carbon fiber, carbon hollow sphere, bentonite, montmorillonite, copper powder, sodium sulfate, Potassium sulfate, zinc sulfate, copper sulfate, iron sulfate, magnesium sulfate, aluminum sulfate, potassium aluminum sulfate, ammonium nitrate, sodium nitrate, potassium nitrate, aluminum nitrate, ammonium chloride, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, sodium phosphate , potassium chromate, calcium citrate, and the like. These can be used alone or in combination of two or more.

The organic filler preferably has an average particle diameter 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. be. If the average particle diameter is too small, the cost tends to increase, and if it is too large, pinholes tend to form when the water-soluble film is stretched during molding.

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

Examples of the above 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, arrowroot 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 modified starch (acid-treated starch, chlorate oxidized starch, dialdehyde starch, etc.), chemically modified starch derivatives (esterified starch, etherified starch, cationized starch, crosslinked starch, etc.). Among them, it is preferable to use raw starch, particularly corn starch and rice starch, from the viewpoint of availability and economy. These can be used alone or in combination of two or more.

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

The surfactant (D) used in the present invention is contained for the purpose of improving releasability from the cast surface during production of a water-soluble film, and is usually a nonionic surfactant, a cationic surfactant, or an anionic surfactant. Examples include surfactants. Nonionic surfactants include, for example, polyoxyethylene nonylphenyl ether, polyoxyethylene octyl nonyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmi polyoxyethylene alkyl such as tate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyalkylene alkyl ether phosphate monoethanolamine salt, polyoxyethylene lauryl amino ether, polyoxyethylene stearyl amino ether, etc. Examples include amino ethers, which may be used singly or in combination of two or more. Among these, polyoxyalkylene alkyl ether phosphate monoethanolamine salt and polyoxyethylene lauryl amino ether are preferred from the viewpoint of production stability. These can be used alone or in combination of two or more.

The content of the surfactant (D) is preferably 0.01 to 3 parts by weight, more preferably 0.1 to 2.5 parts by weight, based on 100 parts by weight of the PVA resin (A). In particular, it is preferably 0.5 to 2 parts by weight. If this content is too small, the peelability between the cast surface of the film forming device and the formed water-soluble film tends to decrease, leading to a decrease in productivity, while if it is too large, it becomes difficult to use the water-soluble film as a packaging material. This tends to cause problems such as a decrease in adhesive strength during sealing.

In addition, in the present invention, other water-soluble polymers (for example, sodium polyacrylate, polyethylene oxide, polyvinylpyrrolidone, dextrin, chitosan, chitin, methylcellulose, hydroxyethylcellulose, etc.) and It is also possible to contain fragrances, rust preventives, colorants, fillers, antifoaming agents, ultraviolet absorbers, liquid paraffins, optical brighteners, bitter components (for example, denatonium benzoate, etc.), and the like. These can be used alone or in combination of two or more.

Further, in the present invention, it is preferable to incorporate 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. is preferred. The blending amount is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, particularly preferably 0.3 to 3 parts by weight, based on 100 parts by weight of the PVA resin (A).

In the present invention, as described above, a resin composition comprising a PVA resin (A), preferably further a plasticizer (B), and optionally further a filler (C), a surfactant (D), etc. This resin composition is dissolved or dispersed using water to prepare a film forming raw material, and a film is formed into a PVA film. In forming such a film, for example, a method such as a melt extrusion method or a casting method can be employed, and the casting method is preferable from the viewpoint of accuracy of film thickness.

In the present invention, the above 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, and among these, high temperature dissolution and pressurized dissolution are preferable because they have less undissolved matter and are excellent in productivity.
The melting temperature is usually 80 to 100°C, preferably 90 to 100°C in the case of high temperature melting, and usually 80 to 130°C, preferably 90 to 120°C in the case of pressure melting. The dissolution time is usually 1 to 20 hours, preferably 2 to 15 hours, and more preferably 3 to 10 hours. If the dissolution time is too short, undissolved substances tend to remain, and if the dissolution time is too long, productivity tends to decrease.

Further, in the melting step, examples of stirring blades include paddles, full zones, max blends, twisters, anchors, ribbons, propellers, and the like.
Furthermore, after dissolving, the resulting PVA resin aqueous solution is subjected to defoaming treatment, and examples of such defoaming methods include stationary defoaming, vacuum defoaming, twin-screw extrusion defoaming, etc. It will be done. Among these, static defoaming and twin-screw extrusion defoaming are preferred.
The temperature for static defoaming is usually 50 to 100°C, preferably 70 to 95°C, and the defoaming time is usually 2 to 30 hours, preferably 5 to 20 hours.

In the casting method, for example, the above-mentioned water is added to the PVA resin (A) (powder) to obtain a PVA resin aqueous solution, and preferably a plasticizer (B) and other ingredients are added to form the resin composition. Obtain an aqueous dispersion or solution. Alternatively, water is added to a resin composition containing a PVA resin (A), preferably a plasticizer (B), and various other compounds to obtain an aqueous dispersion or solution of the resin composition. The solid content concentration of the aqueous dispersion or solution of such a resin composition is preferably 10 to 50% by weight, particularly preferably 15 to 40% by weight, and more preferably 20 to 35% by weight. If the concentration is too low, the productivity of the film tends to decrease, and if it is too high, the viscosity becomes too high, requiring time for defoaming of the dope, and die lines tend to occur when forming a water-soluble film. There is. Furthermore, if the temperature of the metal surface of the endless belt or drum roll is too low, drying tends to take a long time, and if it is too high, foaming tends to occur during film formation.

The above aqueous dispersion or aqueous solution is passed through a slit such as a T-die and cast onto a cast surface such as the metal surface of an endless belt or drum roll or the surface of a plastic base material such as polyethylene terephthalate film, dried, and as needed. The PVA film of the present invention can be obtained by further heat treatment.
For example, it can be performed under the following film forming conditions.

The temperature at the discharge part of the aqueous dispersion or solution of the PVA resin composition is preferably 60 to 98°C, particularly 70 to 95°C. If the temperature is too low, drying time tends to be long and productivity tends to decrease, while if it is too high, foaming etc. tend to occur.

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

Furthermore, a PVA film can also be obtained by casting an aqueous dispersion or solution of the resin composition onto a plastic or metal substrate such as a polyethylene terephthalate film or a polyethylene film using an applicator and drying it.

The thickness of the PVA film is appropriately selected depending on the intended use, but is preferably 10 to 120 μm, more preferably 30 to 110 μm, and particularly preferably 45 to 100 μm. If the thickness is too thin, the mechanical strength of the film tends to decrease, while if it is too thick, the dissolution rate in water tends to be slow, and the film forming efficiency also tends to decrease.

The width of the PVA film is appropriately selected depending on the intended use, 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, production efficiency tends to decrease, while if it is too wide, it tends to be difficult to control slack and film thickness.

The length of the PVA-based film is appropriately selected depending on the use and the like, but it 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, switching between films tends to be time-consuming, while if it is too long, the winding tends to be too tight, resulting in poor appearance and excessive weight.

The surface of the PVA film may be plain, but from the viewpoint of anti-blocking properties, slipperiness during processing, reduced adhesion between products, and appearance, an embossed pattern may be formed on one or both sides of the PVA film. It is also preferable to apply an uneven finish such as a satin pattern (fine uneven pattern), a special engraved pattern, or the like.
In such uneven processing, the processing temperature is usually 60 to 150°C, preferably 80 to 140°C. The processing pressure is usually 2 to 8 MPa, preferably 3 to 7 MPa. The processing time depends on the processing pressure and film forming speed, but is usually 0.01 to 5 seconds, preferably 0.1 to 3 seconds.
Further, if necessary, a cooling treatment may be performed after the roughening treatment in order to prevent unintended stretching of the film due to heat.

Furthermore, in the present invention, the moisture content of the obtained PVA film (water-soluble film) is preferably 3 to 15% by weight, particularly 5 to 14% by weight, from the viewpoint of mechanical strength and sealing properties. More preferably, it is 6 to 13% by weight. If the water content is too low, the film tends to become too hard, and if it is too high, blocking tends to occur. Adjustment to such a moisture content can be achieved by appropriately setting drying conditions and humidity control conditions.
Note that the moisture content is measured in accordance with JIS K 6726 3.4, and the obtained volatile content value is defined as the moisture content.

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

It is important that the PVA film (water-soluble film) obtained in this way satisfies at least one of the above breaking strength (X1) and breaking strength (X2), and in order to control the breaking strength within the above range, For example, (1) the total amount of plasticizer (B) is relatively small and the proportion of plasticizer (b2) is high; (2) the total amount of plasticizer (B) is relatively large and the proportion of plasticizer (b1) is increased; ), etc. Among these, method (2) above is preferred in that the physical properties of the water-soluble film can be controlled while maintaining the various physical properties.

In the present invention, the obtained PVA-based film can be made into a film roll by winding it around a core tube (S1). Although the obtained film roll can be supplied as a product as it is, it is preferably wound around a core tube (S2) of a length commensurate with the desired film width and supplied as a film roll.

The core tube (S1) for winding up the film has a cylindrical shape, 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 3 to 30 cm, more preferably 10 to 20 cm.
The thickness of the core tube (S1) is preferably 1 to 30 mm, more preferably 2 to 25 mm.
The length of the core tube (S1) needs to be longer than the width of the film, and preferably protrudes from the end of the film roll by 1 to 50 cm.

The core tube (S2) is cylindrical, and its material can be selected from paper, metal, plastic, etc., but paper is preferred from the viewpoint of weight reduction and handling.
The inner diameter of the core tube (S2) is preferably 3 to 30 cm, more preferably 10 to 20 cm.
The thickness of the core tube (S2) is preferably 1 to 30 mm, more preferably 3 to 25 mm.
The length of the core tube (S2) may be equal to or longer than the width of the PVA film of the product, and is preferably equal to or 50 cm longer.

When winding up the core tube (S2), the PVA film is slit to a desired width.
Such slitting is performed using a shear blade, a razor blade, or the like, and it is preferable to slit with a shear blade in view of the smoothness of the slit cross section.

In the present invention, the obtained film roll is packaged with a packaging film made of a water vapor barrier resin, but such a film is not ^particularly limited. Measurement) The following can be used. Specific examples include single-layer films such as high-density polyethylene, low-density polyethylene, polypropylene, polyester, polyvinylidene chloride-coated polypropylene, and glass-deposited polyester, or laminated films thereof, or split cloth, paper, and nonwoven fabrics. Examples include laminated films with. Examples of the laminated film include a laminated film of glass-deposited polyester and polyethylene, a laminated film of polyvinylidene chloride coated polypropylene and polyethylene, and the like.

It is also preferable that such a film is subjected to antistatic treatment in order to prevent contamination of foreign matter, and the antistatic agent may be kneaded into the film or coated on the surface. In the case of kneading, an antistatic agent is used in an amount of about 0.01 to 5% by weight based on the resin, and in the case of surface coating, an amount of about 0.01 to 1 g/m ² is used.
As the antistatic agent, for example, alkyl diethanolamine, polyoxyethylene alkylamine, higher fatty acid alkanolamide, sorbitan fatty acid ester, etc. are used.

Next, the film roll is wrapped with a packaging film made of water vapor barrier resin, and then wrapped with a packaging film made of an aluminum material. films (for example, a laminated film of aluminum foil and polyethylene film), a laminated film of an aluminum vapor-deposited film and a moisture-resistant plastic film (for example, a laminated film of an aluminum-deposited polyester film and a polyethylene film), a laminated film of an alumina-deposited film and a moisture-resistant plastic film (for example, a laminated film of an aluminum-deposited polyester film and a polyethylene film), For example, a laminated film of an alumina-deposited polyester film and a polyethylene film), etc. In the present invention, a laminated film of an aluminum foil and a polyolefin film, a laminated film of an aluminum-deposited film and a polyolefin film are particularly useful, and especially a stretched polypropylene film/ A laminate film having a structure of polyethylene film/aluminum foil/polyethylene film, a laminate film having a structure of stretched polypropylene film/low density polyethylene film/aluminum foil, etc. are useful.
In packaging, the inner packaging film made of a water vapor barrier resin and the outer packaging film made of an aluminum material are sequentially wrapped, and the excess portion in the width direction is pushed into the core tube.

In order to prevent scratches on the ends and adhesion of foreign matter such as dust to the film roll of the present invention, protective pads having core tube through holes are attached to both ends of the film roll either directly or after packaging. I can do it.
The practical shape of the protective pad is a disc-shaped sheet or film, depending on the film roll. In order to enhance the protective effect, it is preferable to add a cushioning function such as foam, woven fabric, non-woven fabric, etc. Further, in order to protect the film roll from humidity, a desiccant may be separately enclosed, or may be laminated or mixed in the protective pad.
The material for the protective pad is advantageously plastic, and specific examples thereof include polystyrene, polyethylene, polypropylene, polyester, polyvinyl chloride, and the like.

In addition, for the protective pad containing a desiccant, for example, desiccant or water-absorbing agents such as calcium chloride, silica gel, molecular sieves, sugars, particularly sugars with high osmotic pressure, water-absorbing resins, natural celluloses, synthetic celluloses, etc. Moisture-absorbing layers are obtained by dispersing, impregnating, coating and drying moldable materials such as glass cloth and non-woven fabrics, and use these moisture-absorbing agents or water-absorbing agents as moldable materials, polyester films, polyethylene films, polypropylene films, Teflon films, etc. Examples include those sandwiched between thermoplastic resin films such as (registered trademark) film.
Examples of commercially available sheet 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 Industries Co., Ltd. etc.

The film roll packaged by such means is supported by providing brackets (support plates) on the protruding parts at both ends of the core tube or by placing the protruding parts at both ends on a stand, so that the film roll can be suspended in the air without touching the ground. It is preferable to store and transport it in a floating state. Brackets are used when the width of the film is relatively small, and frames are used when the width of the film is relatively large.
The bracket is made of a plywood board or a plastic board, and its size may be as long as the four sides of the bracket are larger than the diameter of the film roll.

Then, a pair of brackets are arranged and fitted to the core tube protrusions at both ends of the film roll so as to face each other, and are mounted on the film roll. For fitting, a hole slightly larger than the diameter of the core tube may be provided in the center of the bracket, or a U-shaped hole may be formed from the top of the bracket to the center so that the core tube can be easily inserted.

Film rolls supported by brackets are stored and transported in cartons such as cardboard boxes, but when using rectangular brackets, it is recommended to cut off the four corners of the brackets to facilitate storage operations. preferable.
Also, in order to prevent the above pair of brackets from wobbling, it is advantageous to fix them both with binding tape, and at that time, to prevent the tape from moving or loosening, attach the side surface (thickness part) of the bracket to the same width as the tape. It is also practical to provide a groove to prevent tape slippage.

When storing or transporting packaged film rolls, it is desirable to avoid extreme high or low temperatures, low humidity, or high humidity conditions; specifically, temperatures of 10 to 30°C and humidity of 40 to 75% RH are preferable. .

The thus obtained water-soluble film of the present invention is useful for various packaging applications, among others, it is useful for unit packaging of drugs and the like. The drug is not particularly limited and may be alkaline, neutral, or acidic, and the drug may be in any form such as granules, tablets, powder, powder, or liquid. Dissolved or dispersed agents are preferred and are particularly useful in packaging liquid detergents.
Note that the above pH value is measured in accordance with JIS K 3362 8.3. Moreover, the moisture content is measured according to JIS K 3362 7.21.3.

As a liquid detergent, the pH value when dissolved or dispersed in water is preferably 6 to 12, particularly preferably 7 to 11, and the water content is preferably 15% by weight or less, particularly 0. The content is preferably 0.1 to 10% by weight, more preferably 0.1 to 7% by weight, and the film does not gel or become insolubilized, resulting in excellent water solubility.

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

The drug package of the present invention usually has a smooth surface. However, from the viewpoints of blocking resistance, slipperiness during processing, reduced adhesion between products (packaging bodies), and appearance, embossed patterns, fine unevenness patterns, and special engraved patterns are required on the outer surface of the packaging body (water-soluble film). , etc. may be applied. Moreover, the drug package of the present invention, in which a liquid detergent is packaged, maintains the shape containing the liquid detergent during storage. During use (washing), the package (water-soluble film) comes into contact with water, causing the package to dissolve and the contained liquid detergent to flow out from the package.

When packaging drugs, especially liquid detergents, into packages using the water-soluble film of the present invention, known methods can be employed. Examples include (1) a heat sealing method, (2) a water sealing method, and (3) a glue sealing method, among which the (1) heat sealing method is advantageous in terms of seal strength.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.
In addition, "parts" and "%" in the examples mean weight basis.

The following PVA resins were prepared.
・Carboxyl group-modified PVA (A1): 4% aqueous solution viscosity at 20°C 22 mPa·s, average saponification degree 96 mol%, amount of modification by maleic acid monomethyl ester 4.0 mol%
・Carboxyl group-modified PVA (A2): 4% aqueous solution viscosity at 20°C 22 mPa・s, average saponification degree 99 mol%, amount of modification by maleic acid monomethyl ester 4.0 mol%

<Example 1>
As the PVA resin (A), 100 parts of carboxyl group-modified PVA (A1) having a viscosity of a 4% aqueous solution at 20°C of 22 mPa·s, an average saponification degree of 96 mol%, and an amount of modification by maleic acid monomethyl ester of 4.0 mol%. , as a plasticizer (B), 10 parts of sorbitol (b1) and 25 parts of glycerin (b2), as a filler (C), 8 parts of starch (average particle size 20 μm), as a surfactant (D), polyoxy Two parts of alkylene alkyl ether phosphate monoethanolamine salt and water were mixed and subjected to dissolution treatment to obtain a PVA aqueous solution (solid content concentration 25%) in which starch was dispersed.
The resulting PVA aqueous solution was defoamed at 80°C and cooled to 40°C. The PVA aqueous solution was cast onto a polyethylene terephthalate film, passed through a 3 m drying chamber (105°C) at a speed of 0.350 m/min, and dried to form a PVA film (water-soluble film) with a thickness of 89 μm. Obtained.
The obtained PVA film (water-soluble film) was measured and evaluated as follows.

[Breaking strength (X1) and (X2) when the heat-sealed part is peeled off]
Breaking strength was measured in accordance with JIS K 7127 (1999). The measurements were performed as follows.
That is, two water-soluble films that had been conditioned for one day in an environment of 23°C and 40% RH were superimposed, and the temperature was 140°C, the pressure was 0.65 MPa, the time was 1.5 seconds, and the seal width was 1.5 mm. After heat-sealing once, the heat-sealed part was left unapplied for 2 hours at 23°C and 40% RH, and then the tensile speed was adjusted using Autograph "AG-Xplus" manufactured by Shimadzu Corporation. Breaking strength (X1) was determined from the maximum point test force (N) measured at 200 mm/min (film width 15 mm, distance between chucks 50 mm).
Further, in the above measurement, the same procedure was performed except that the heat sealing temperature was changed to 145° C., and the breaking strength (X2) was determined from the maximum point test force (N).

[Peeling condition when the heat-sealed part is peeled off]
After confirming the above-mentioned breaking strengths (X1) and (X2), the edges of the heat-sealed portions were visually observed, and the peeling state was evaluated based on the following criteria.
○: Two films remain in the heat-sealed area (cohesive failure).
×: A state in which the film is one piece at the heat-sealed part (interfacial peeling).

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

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

From the results in Table 1 above, in the above example, even at a relatively low heat-sealing temperature, the rupture strength when the heat-sealed portion was peeled off was high, and there was no interfacial peeling during peeling. , the water-soluble film had excellent adhesiveness and strength, whereas the comparative example had poor heat-sealing properties, such as low breaking strength and interfacial peeling. From these results, when the water-soluble film of the example is used to package, for example, liquid detergent, it is possible to obtain a good package without the risk of bag breakage from the heat-sealed portion. Recognize.

The water-soluble film of the present invention is a water-soluble film that has good heat-sealability and excellent productivity, such as excellent adhesiveness and strength of the heat-sealed part even at low heat-sealing temperatures when forming a package. It can be used for various packaging purposes, and is particularly useful for unit packaging of drugs, etc., and especially liquid detergents.

Claims (7)

A water-soluble film containing a polyvinyl alcohol resin (A) and a plasticizer (B) , wherein the polyvinyl alcohol resin (A) has a ratio of modified polyvinyl alcohol resin/unmodified polyvinyl alcohol of 100/0 to 60. /40 weight ratio, the modified polyvinyl alcohol resin is an anionic group-modified polyvinyl alcohol with a 4% aqueous solution viscosity of 5 to 50 mPa·s at 20°C and a modification amount of 1 to 10 mol%. and the plasticizer (B) contains a polyhydric alcohol (b1) having a melting point of 80°C or higher and a polyhydric alcohol (b2) having a melting point of 50°C or lower, and the polyhydric alcohol (b2) The weight ratio (b1/b2) of the polyhydric alcohol (b1) to the polyhydric alcohol (b1) is 0.1 to 5, and two water-soluble films that have been conditioned for one day in an environment of 23 ° C. and 40% RH are laminated. After heat-sealing once under the conditions of temperature 140℃, pressure 0.65MPa, time 1.5 seconds, and seal width 1.5mm, when left in an environment of 23℃ and 40% RH for 2 hours, heat sealing was confirmed. A water-soluble film characterized by a breaking strength (X1) of 11.0 N/15 mm or more when peeled off, and no interfacial peeling during such peeling (provided that it contains a copolymer unit consisting of a maleic acid group) (Excluding the film prepared in the proportions of 100 parts by weight of sodium carboxylate base-modified polyvinyl alcohol resin in an amount of 4 mol %, 25 parts by weight of glycerin, and 8 parts by weight of sorbitol). A water-soluble film containing a polyvinyl alcohol resin (A) and a plasticizer (B) , wherein the polyvinyl alcohol resin (A) has a ratio of modified polyvinyl alcohol resin/unmodified polyvinyl alcohol of 100/0 to 60. /40 weight ratio, the modified polyvinyl alcohol resin is an anionic group-modified polyvinyl alcohol with a 4% aqueous solution viscosity of 5 to 50 mPa·s at 20°C and a modification amount of 1 to 10 mol%. and the plasticizer (B) contains a polyhydric alcohol (b1) having a melting point of 80°C or higher and a polyhydric alcohol (b2) having a melting point of 50°C or lower, and the polyhydric alcohol (b2) The weight ratio (b1/b2) of the polyhydric alcohol (b1) to the polyhydric alcohol (b1) is 0.1 to 5, and two water-soluble films that have been conditioned for one day in an environment of 23 ° C. and 40% RH are laminated. After heat sealing once under the conditions of temperature 145℃, pressure 0.65MPa, time 1.5 seconds, and seal width 1.5mm, when left in an environment of 23℃ and 40% RH for 2 hours, heat sealing was confirmed. A water-soluble film characterized by a breaking strength (X2) of 11.5 N/15 mm or more when peeled off, and no interfacial peeling during such peeling (provided that it contains a copolymer unit consisting of a maleic acid group) (Excluding the film prepared in the proportions of 100 parts by weight of sodium carboxylate base-modified polyvinyl alcohol resin in an amount of 4 mol %, 25 parts by weight of glycerin, and 8 parts by weight of sorbitol). 3. The water-soluble film according to claim 1 , wherein the content of the plasticizer (B) is 20 parts by weight or more based on 100 parts by weight of the polyvinyl alcohol resin (A). The water-soluble film according to any one of claims 1 to 3, characterized in that the water content of the water-soluble film is 3 to 15% by weight. The water-soluble film according to any one of claims 1 to 4, which is used for drug packaging. A drug package comprising a liquid detergent packaged with the water-soluble film according to any one of claims 1 to 5 . 7. The drug package according to claim 6 , 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.