JP2018104564A - Method of manufacturing water-soluble film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a water-soluble film capable of achieving water sealability, water solubility and curl alleviation, which are contradictory properties in a water-soluble film on which a heat treatment is conducted.SOLUTION: There is provided a method of manufacturing a water-soluble film containing a polyvinyl alcohol-based resin (A), by conducting following processes [I] and [II]. Process [I]: a process for film making a film making raw material containing a polyvinyl alcohol-based resin (A) and drying the same to obtain a film. Process [II]: a process for heat treating the film after drying at 95 to 135°C and then cooling the film to 40°C or less in 20 sec.SELECTED DRAWING: None

Description

  The present invention is a water-soluble film (hereinafter sometimes referred to as “PVA-based film”) containing a polyvinyl alcohol-based resin (hereinafter, polyvinyl alcohol may be abbreviated as “PVA”). More particularly, the present invention relates to a method for producing a water-soluble film that is excellent in solubility and curl resistance of a water-soluble film and also excellent in water sealability.

  A PVA film is a film made of a PVA resin having water solubility while being a thermoplastic resin. A hydrophobic film usually used for packaging films such as a polyethylene terephthalate film and a polyolefin film is a film of the same type. Various physical properties and feeling of touch are greatly different.

  Conventionally, taking advantage of the water-solubility of PVA-based resins, medicine packaging (unit packaging) in which various drugs such as agricultural chemicals and detergents are put in bags made of PVA-based resin films has been proposed and used for a wide range of applications. ing.

  As a water-soluble unit packaging bag used for such applications, for example, 5 to 30 parts by weight of a plasticizer, 1 to 10 parts by weight of starch, and 0.01 to 2 parts by weight of a surfactant are blended with 100 parts by weight of PVA. Water-soluble film (see, for example, Patent Document 1), 4 wt% aqueous solution viscosity at 20 ° C. is 10 to 35 mPs · s, average saponification degree 80.0 to 99.9 mol%, anionic group modification amount 1 to The plasticizer (B) is 20 to 50 parts by weight, the filler (C) is 2 to 30 parts by weight, and the surfactant (D) is 0.1 parts by weight per 100 parts by weight of the anionic group-modified PVA resin (A). A water-soluble film made of a resin composition containing 01 to 2.5 parts by weight (for example, see Patent Document 2) is known.

JP 2001-329130 A JP 2004-161823 A

The water-soluble films disclosed in Patent Documents 1 and 2 are excellent in water solubility, and can be used as a medicine package by packaging a liquid detergent or the like.
On the other hand, in film formation, there is concern about the occurrence of curling, and in order to prevent this, heat treatment at a high temperature is required.
However, when heat treatment at a high temperature is performed, it is considered that various physical properties such as water-sealing property and water-solubility are deteriorated because the PVA resin of the film is easily crystallized. For this reason, it is difficult to achieve both water sealability and water solubility, which are contradictory properties, and curl reduction, and there is room for further improvement in Patent Documents 1 and 2 described above.

  Therefore, in the present invention, in such a background, a water-soluble film produced by heat treatment is a method for producing a water-soluble film capable of achieving both water sealing properties and solubility, and curling reduction, which are opposite physical properties. It is intended to provide.

  However, as a result of intensive studies in view of such circumstances, the inventor of the present invention has made it possible to rapidly cool the water-soluble film after heat treatment in a short time in a method for producing a water-soluble film mainly composed of PVA-based resin. The present invention was completed by finding that a water-soluble film having excellent water resistance and curling resistance and water sealing properties can be obtained.

That is, the present invention provides a method for producing a water-soluble film containing a PVA-based resin (A), the method comprising the steps of [I] and [II] described below. The gist.
Step [I]: A step of forming a film-forming raw material containing the PVA-based resin (A) and drying it to obtain a film.
Step [II]: A step of cooling the film to 40 ° C. or less within 20 seconds after heat-treating the dried film at 95 to 135 ° C.

The water-soluble film of the present invention is a method for producing a water-soluble film containing a PVA-based resin (A), wherein the following steps [I] and [II] are sequentially performed. Therefore, the obtained water-soluble film is excellent in solubility and curling resistance, and also excellent in water sealability.
Step [I]: A step of forming a film-forming raw material containing the PVA-based resin (A) and drying it to obtain a film.
Step [II]: A step of cooling the film to 40 ° C. or less within 20 seconds after heat-treating the dried film at 95 to 135 ° C.

  In addition, when the moisture content of the film after drying is 6 to 25% by weight, the resulting water-soluble film is more excellent in solubility and curl resistance, and is also excellent in water sealability.

  Furthermore, when the heat treatment is performed for 1 to 120 seconds, the obtained water-soluble film is further excellent in solubility and curl resistance, and also in water sealability.

  And when the said PVA-type resin (A) is a manufacturing method of the water-soluble film containing an anionic group modified PVA-type resin, the obtained water-soluble film is further excellent in solubility.

  Moreover, when it is the manufacturing method of the said water-soluble film containing a plasticizer (B), when setting it as a chemical | medical agent package, a water-soluble film can be made flexible.

  Furthermore, if the content of the plasticizer (B) is 20 parts by weight or more with respect to 100 parts by weight of the PVA resin (A), a liquid such as a liquid medicine is packaged. Even in a packaged state, the toughness of the water-soluble film over time is not impaired, and the mechanical strength is improved.

  And when it is the manufacturing method of the said water-soluble film whose water content of a water-soluble film is 3 to 15 weight%, it comes to be excellent by mechanical strength and sealing performance.

Hereinafter, although it demonstrates in detail about the structure of this invention, these show an example of a desirable embodiment and are not specified by these content.
In the present invention, (meth) acryl means acryl or methacryl.

  This invention is a manufacturing method of the water-soluble film obtained by forming into a film forming raw material containing PVA-type resin (A). Hereinafter, various components of the film forming raw material will be described.

[PVA resin (A)]
Examples of the PVA resin (A) used as the film forming raw material of the present invention include unmodified PVA and modified PVA resin.

  The average degree of saponification of the PVA resin (A) used in the present invention is preferably 80 mol% or more, particularly 82 to 99.9 mol%, more preferably 85 to 98.5 mol%, particularly It is preferably 90 to 97 mol%. Moreover, when using unmodified PVA as PVA-type resin (A), it is preferable that the average saponification degree is 80 mol% or more, especially 82-99 mol%, Furthermore, 85-90 mol. % Is preferred. And when using modified PVA-type resin as PVA-type resin (A), it is preferable that the average saponification degree is 80 mol% or more, especially 85-99.9 mol%, Furthermore, 90 It is preferable that it is -98 mol%. Further, 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 88 to 99 mol%, 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. In addition, when the average saponification degree is too large, the solubility in water tends to be greatly reduced due to the heat history during film formation.

  In addition, the polymerization degree of the PVA resin (A) used in the present invention can be generally represented by an aqueous solution viscosity, and a 4 wt% aqueous solution viscosity at 20 ° C is preferably 5 to 50 mPa · s. It is preferably 13 to 45 mPa · s, particularly 17 to 40 mPa · s. When unmodified PVA is used as the PVA-based resin (A), the viscosity of the 4% by weight aqueous solution of unmodified PVA at 20 ° C. is preferably 5 to 50 mPa · s, and more preferably 13 to 45 mPa · s. s, particularly 17 to 40 mPa · s is preferable. And when using modified PVA-type resin as PVA-type resin (A), it is preferable that the 4 weight% aqueous solution viscosity in 20 degreeC of modified PVA-type resin is 5-50 mPa * s, Furthermore, 13- 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 as a packaging material tends to decrease. On the other hand, if the viscosity is too large, the aqueous solution viscosity during film formation tends to be high and productivity tends to decrease.

  In addition, said average saponification degree is measured based on JIS K 6726 3.5, and 4 weight% aqueous solution viscosity is measured according to JIS K 6726 3.1.2.

  Examples of the modified PVA resin used in the present invention include an anionic group-modified PVA resin, a cationic group-modified PVA, and a nonionic group-modified PVA resin. Among these, it is preferable to use an anionic group-modified PVA resin from the viewpoint of solubility in water. Examples of the anionic group include a carboxyl group, a sulfonic acid group, and a phosphoric acid group. From the viewpoint of chemical resistance and stability over time, a carboxyl group and a sulfonic acid group, particularly a carboxyl group is preferable. .

  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%, and particularly preferably 3 to 7 mol%. %. If the amount of modification is too small, the solubility in water tends to decrease, and if it is too large, the productivity of the PVA-based resin tends to decrease or the biodegradability tends to decrease, and also causes blocking. It tends to be easier.

  In the present invention, each of the above PVA resins (A) can be used alone, or a combination of unmodified PVA and modified PVA resin, and further, saponification degree, viscosity, modified species, modified amount. Two or more different types may be used in combination. Especially, in this invention, it is preferable that PVA-type resin (A) contains modified PVA-type resin. In particular, it preferably contains an anionic group-modified PVA-based resin, or preferably contains an anionic group-modified PVA and an unmodified PVA. And unmodified PVA.

  The content ratio (weight ratio) between the modified PVA resin and the unmodified PVA is preferably 95/5 to 60/40, particularly 94/6 to 70/30, more preferably 93/7 to 80/20. It is preferable that If the content weight ratio is too small, the solubility in water tends to decrease, and if it is too large, the sealing property tends to decrease.

  In the combined use of the modified PVA resin and unmodified PVA, the unmodified PVA preferably has a 4% by weight aqueous solution viscosity at 20 ° C. of 5 to 50 mPa · s, more preferably 8 to 45 mPa · s. In particular, it is preferably 12 to 40 mPa · s, more preferably 15 to 35 mPa · s. If the viscosity is too small, the mechanical strength of the water-soluble film as a packaging material tends to decrease. On the other hand, if the viscosity is too large, the aqueous solution viscosity during film formation tends to be high and productivity tends to decrease.

  Next, the PVA resin (A) used in the present invention is produced, for example, as follows.

  Unmodified PVA can be produced by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester compound according to a known method.

  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, and vinyl stearate. Can be mentioned. Of these, vinyl acetate is preferably used as the vinyl ester compound. The vinyl ester compounds may be used alone or in combination of two or more.

  The modified PVA resin is also a saponification method after copolymerizing the vinyl ester compound and an unsaturated monomer having a modifying group copolymerizable with the vinyl ester compound according to a known method, or It can be produced by a method of post-modifying unmodified PVA.

  In the present invention, the following unsaturated monomer copolymerizable with the vinyl ester compound may be copolymerized, but when obtaining a modified PVA resin, among the following monomers, the modified group It is necessary to copolymerize an unsaturated monomer having Examples of the unsaturated monomer include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, 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 acylated products thereof, unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, undecylenic acid, Examples thereof 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 methallyl sulfonic acid, and salts thereof. These may be used alone or in combination of two or more. In addition, the content rate of the said copolymerizable monomer is 10 mol% or less with respect to the sum total of the unsaturated monomer copolymerizable with a vinyl ester type compound normally.

  Examples of the modified PVA-based resin include those having 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. It is done. In particular, it is preferable to have a secondary hydroxyl group in addition to the primary hydroxyl group. Examples thereof include a PVA resin having a 1,2-diol structural unit in the side chain and a PVA resin having a hydroxyalkyl group in the side chain. The PVA resin having a 1,2-diol structural unit in the side chain is, for example, (i) a method of saponifying a copolymer of vinyl acetate and 3,4-diacetoxy-1-butene, and (ii) acetic acid. A method of saponifying and decarboxylating a copolymer of vinyl and vinyl ethylene carbonate, (iii) saponifying and depolymerizing 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 glyceryl monoallyl ether, or the like.

  As a polymerization method in the preparation of the PVA resin (A), for example, a known polymerization method such as a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method can be arbitrarily used. Usually, methanol, ethanol or isopropyl is used. It is carried out by a solution polymerization method using a lower alcohol such as alcohol as a solvent. In this solution polymerization, the monomer is charged in the case of a modified PVA resin. First, the whole amount of the vinyl ester compound and a part of the unsaturated monomer having a carboxyl group, for example, are charged, and polymerization is performed. Any method may be used such as a method of starting and adding the remaining unsaturated monomers continuously or in portions during the polymerization period, or a method of batch-feeding the unsaturated monomers having a carboxyl group. it can.

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

  The saponification is carried out in the presence of a saponification catalyst by dissolving the obtained copolymer in alcohol. As alcohol, C1-C5 alcohol, such as methanol, ethanol, a butanol, is mentioned, for example. These may be used alone or in combination of two or more. The concentration of the copolymer in the alcohol is selected from the range of 20 to 50% by weight.

  Examples of the saponification catalyst include alkali catalysts such as alkali metal hydroxides and alcoholates such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate, potassium methylate, and the like. It is also possible to use a catalyst. The saponification catalyst is preferably used in an amount of 1 to 100 mmol equivalents relative to 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 modified PVA resin can be produced by any method, for example, (I) saponification after copolymerization of an unsaturated monomer having a carboxyl group and a vinyl ester compound. And (II) a saponification method after polymerizing a vinyl ester compound in the presence of a carboxyl group-containing alcohol, aldehyde or thiol as a chain transfer agent.

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

  Examples of the unsaturated monomer having a carboxyl group in the method (I) include ethylenically unsaturated dicarboxylic acid (maleic acid, fumaric acid, itaconic acid, etc.), or ethylenically unsaturated dicarboxylic acid monoester (maleic acid). 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) It is necessary to change to a carboxyl group by hydrolysis during saponification of the copolymer. Or monomers such as ethylenically unsaturated carboxylic acid anhydrides (maleic anhydride, itaconic anhydride, etc.) or ethylenically unsaturated monocarboxylic acids ((meth) acrylic acid, crotonic acid, etc.), and Among them, maleic acid, maleic acid monoalkyl ester, maleic acid dialkyl ester, maleate, maleic anhydride, itaconic acid, itaconic acid monoalkyl ester, itaconic acid dialkyl ester, (meth) acrylic acid, etc. are used. It is preferable to use maleic acid, maleic acid monoalkyl ester, maleic acid dialkyl ester, maleate, maleic anhydride, especially maleic acid monoalkyl ester. These may be used alone or in combination of two or more.

  In the method (II), a compound derived from a thiol having a particularly large chain transfer effect is effective, and examples thereof include the following compounds.

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

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

  In the case of using a sulfonic acid-modified PVA resin modified with a sulfonic acid group, for example, vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, etc. A method of saponification after copolymerizing the above copolymerization component with a vinyl ester compound, Michael addition of vinyl sulfonic acid or its salt, 2-acrylamido-2-methylpropane sulfonic acid or its salt, etc. to PVA resin It can be manufactured by a method or the like.

  On the other hand, examples of a method for post-modifying the unmodified PVA include a method of converting the unmodified PVA into acetoacetate ester, acetalization, urethanization, etherification, grafting, phosphate esterification, and oxyalkylene.

  In addition to the unsaturated monomer having a carboxyl group and the vinyl ester compound, other general monomers may be contained in a range that does not impair water solubility. For example, alkyl esters of ethylenically unsaturated carboxylic acids, allyl esters of saturated carboxylic acids, α-olefins, alkyl vinyl ethers, alkyl allyl ethers, (meth) acrylamide, (meth) acrylonitrile, styrene, vinyl chloride. Etc. can be used. These may be used alone or in combination of two or more.

[Plasticizer (B)]
In the present invention, the PVA-based resin (A) is formed as a film-forming raw material to produce a water-soluble film. At that time, the plasticizer (B) is added to make the water-soluble film flexible. It is preferable at a point and it is more preferable to use the following 2 types of plasticizers (B) together.

  One type of the 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 has a melting point. It is a polyhydric alcohol (b2) (hereinafter sometimes abbreviated as a plasticizer (b2)) having a temperature of 50 ° C. or less. It is preferable in terms of shape stability over time when it is made into a body.

As the polyhydric alcohol (b1) having a melting point of 80 ° C. or higher, many of sugar alcohols, monosaccharides and polysaccharides can be applied. Among them, for example, salicyl alcohol (83 ° C.), catechol (105 ° C.) ), Resorcinol (110 ° C.), hydroquinone (172 ° C.), bisphenol A (158 ° C.), bisphenol F (162 ° C.), dipentyl glycol (127 ° C.) and the like, phloroglucinol (218 ° C.), 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 ), Pentahydric alcohols such as fructose (104 ° C.), mannitol (16 ° C), hexahydric alcohols such as sorbitol (95 ° C), inositol (225 ° C), octahydric alcohols such as lactitol (146 ° C), sucrose (186 ° C), trehalose (97 ° C), maltitol (145 ° C), etc. Of 9 or more alcohols. These may be used alone or in combination of two or more. In addition, the inside of said () shows melting | fusing point of each compound.
Among them, those having a melting point of 85 ° C. or higher, particularly 90 ° C. or higher are preferable from the viewpoint of the tensile strength of the water-soluble film. The upper limit of the melting point is preferably 300 ° C., particularly 200 ° C.

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

  In the present invention, the plasticizer (b1) preferably has a molecular weight of 150 or more, more preferably 160 to 500, and particularly preferably 180 to 400, in terms of toughness of the water-soluble film. Specific examples include sorbitol, sucrose, and the like.

  On the other hand, as the polyhydric alcohol (b2) having a melting point of 50 ° C. or lower, many of aliphatic alcohols are applicable. For example, 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 glycol having a molecular weight of 2000 or less, glycerin (18 ° C.), diglycerin, triethanolamine (21 ° C.) Examples include alcohol. And the thing whose melting | fusing point is 30 degrees C or less, especially 20 degrees C or less is preferable at the point of the softness | flexibility of a water-soluble film. In addition, the minimum of melting | fusing point is -80 degreeC normally, Preferably it is -10 degreeC, Most preferably, it is 0 degreeC. These may be used alone or in combination of two or more. In addition, the inside of said () shows melting | fusing point of each compound.

  Furthermore, in the present invention, among the plasticizers (b2), the number of hydroxyl groups in one molecule is 4 or less, particularly 3 or less because flexibility at room temperature (25 ° C.) can be easily controlled. Specifically, for example, glycerin and the like are preferable.

  In the present invention, the plasticizer (b2) preferably has a molecular weight of 100 or less, more preferably 50 to 100, and particularly preferably 60 to 95, in terms of easy flexibility control. Specifically, glycerol etc. are mentioned, for example.

  In the present invention, a plasticizer (b3) other than the plasticizers (b1) and (b2) may be used in combination. Examples of the plasticizer (b3) include trimethylolpropane (58 ° C.), diethylene glycol. Alcohols such as 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, cyclohexanone, etc. Ketones, 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 may be used alone or in combination of two or more.

  In this invention, it is preferable that content of a plasticizer (B) is 20 weight part or more with respect to 100 weight part of PVA-type resin (A), Especially 25-70 weight part, Furthermore, 30-60. Part by weight, in particular 35-50 parts by weight, is preferred. If the content of the plasticizer (B) is too small, the toughness of the water-soluble film tends to be deteriorated over time when a liquid such as a liquid medicine is packaged to form a package. In addition, when there is too much, it exists in the tendency for mechanical strength to fall.

  About said plasticizer (b1) and plasticizer (b2), it is preferable that the content weight ratio (b1 / b2) is 0.1-5, More preferably, it is 0.35-4.5, Most preferably It is 0.4 to 4, more preferably 0.5 to 3.5, particularly preferably 0.7 to 3. If the content ratio is too small, the water-soluble film tends to be too soft, the sealing strength at low temperature tends to decrease, and blocking tends to occur easily. If it is too large, the water-soluble film becomes hard. There is a tendency to become too much and tends to be brittle even in a low humidity environment.

Moreover, as content of said plasticizer (b1) and a plasticizer (b2), a plasticizer (b1) is 5-40 weight part with respect to 100 weight part of PVA-type resin (A), Furthermore, 8- The amount is preferably 30 parts by weight, particularly 10 to 25 parts by weight, and the plasticizer (b2) is preferably 5 to 40 parts by weight, more preferably 10 to 35 parts by weight, and particularly preferably 15 to 30 parts by weight.
If the amount of the plasticizer (b1) is too small, the water-soluble film tends to be too soft and blocking tends to occur. If the amount is too large, the water-soluble film tends to be too hard and tends to be brittle even in a low humidity environment. is there. Moreover, when there is too little plasticizer (b2), there exists a tendency for a water-soluble film to become hard too much, and there exists a tendency for it to become brittle also in a low-humidity environment, and when too much, a water-soluble film becomes too soft and tends to produce blocking. There is.

  Furthermore, the total amount of the plasticizer (b1) and the plasticizer (b2) is preferably 70% by weight or more, more preferably 80% by weight or more, and particularly 87% by weight or more with respect to the entire plasticizer (B). In particular, it is preferably 90% by weight or more, more preferably 95% by weight or more. Particularly preferred is the case where the entire plasticizer (B) consists solely of the plasticizer (b1) and the plasticizer (b2). If the total amount of the plasticizers (b1) and (b2) is too small, the mechanical strength tends to decrease.

  Furthermore, in the present invention, it is usually preferable to further contain a filler (C), a surfactant (D) and the like in the film forming raw material.

[Filler (C)]
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. Among them, organic fillers are preferable. Moreover, as an average particle diameter, it is preferable that it is 0.1-50 micrometers, and also it is preferable that it is 0.5-40 micrometers. In addition, the said average particle diameter can be measured with a laser diffraction type particle size distribution measuring apparatus etc., for example.

  Such an inorganic filler preferably has an average particle diameter of 1 to 10 μm. If the average particle diameter is too small, the effect of dispersibility of the water-soluble film in water tends to be small. When the water-soluble film is molded, it tends to become a pinhole when it is stretched, or the appearance may be deteriorated.

  Specific examples of the inorganic filler include, for example, talc, clay, silicon dioxide, diatomaceous earth, kaolin, mica, asbestos, gypsum, graphite, glass balloon, glass beads, calcium sulfate, barium sulfate, ammonium sulfate, calcium sulfite, and calcium carbonate. , Whisker-like calcium carbonate, magnesium carbonate, dosonite, dolomite, potassium titanate, carbon black, glass fiber, alumina fiber, boron fiber, processed mineral fiber, carbon fiber, carbon hollow sphere, bentonite, montmorillonite, copper powder, sodium sulfate, Potassium sulfate, zinc sulfate, copper sulfate, iron sulfate, magnesium sulfate, aluminum sulfate, potassium aluminum sulfate, ammonium nitrate, sodium nitrate, potassium nitrate, aluminum nitrate, ammonium chloride, sodium chloride Potassium, potassium chloride, magnesium chloride, calcium chloride, sodium phosphate, potassium chromate, calcium citrate. These may be used alone or in combination of two or more.

  As an organic filler, it is preferable that the average particle diameter is 0.5-50 micrometers, More preferably, it is 1-40 micrometers, Most preferably, it is 2-30 micrometers, More preferably, it is 3-25 micrometers. If the average particle size is too small, the cost tends to be high, and if it is too large, the water-soluble film tends to become a pinhole when stretched by molding.

  Examples of the organic filler include starch, melamine resin, polymethyl (meth) acrylate resin, polystyrene resin, biodegradable resin such as polylactic acid, and the like. As the organic filler, in particular, a biodegradable resin such as polymethyl (meth) acrylate resin, polystyrene resin, and starch is preferably used. These may be used alone or in combination of two or more.

  Examples of the starch include raw starch (corn starch, potato starch, sweet potato starch, wheat starch, kissava starch, sago starch, tapioca starch, sorghum starch, rice starch, bean starch, kudzu starch, bracken starch, lotus starch, Castor starch, etc.), physically modified starch (α-starch, fractionated amylose, wet heat-treated starch, etc.), enzyme-modified starch (hydrolyzed dextrin, enzyme-degraded dextrin, amylose, etc.), chemically modified starch (acid-treated starch, hypochlorous acid) Chloric acid oxidized starch, dialdehyde starch, etc.), chemically modified starch derivatives (esterified starch, etherified starch, cationized starch, crosslinked starch, etc.) and the like. Of these, raw starch, especially corn starch and rice starch are preferably used from the viewpoint of availability and economy. These may be used alone or in combination of two or more.

  About content of the said filler (C), it is preferable that it is 1-30 weight part with respect to 100 weight part of PVA-type resin (A), Furthermore, 2-25 weight part, Especially 2.5-20 weight part. Part. If the content is too small, the blocking resistance tends to decrease, and if the content is too large, the water-soluble film tends to become pinholes when stretched by molding.

[Surfactant (D)]
The surfactant (D) used in the present invention is contained for the purpose of improving the peelability from the cast surface during the production of a water-soluble film, and is usually a nonionic surfactant, a cationic surfactant, an anion. Surfactant is mentioned. Nonionic surfactants include, for example, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl nonyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan mono Polyoxyethylene such as palmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyalkylene alkyl ether phosphate monoethanolamine salt, polyoxyethylene lauryl amino ether, polyoxyethylene stearyl amino ether An alkylamino ether etc. are mentioned, It uses 1 type or in combination of 2 or more types. Of these, polyoxyalkylene alkyl ether phosphate monoethanolamine salt and polyoxyethylene lauryl amino ether are preferable in terms of production stability. These may be used alone or in combination of two or more.

  About content of this surfactant (D), it is preferable that it is 0.01-3 weight part with respect to 100 weight part of PVA-type resin (A), Furthermore, 0.1-2.5 weight part, In particular, the amount is preferably 0.5 to 2 parts by weight. When the content is too small, the peelability between the cast surface of the film forming apparatus and the formed water-soluble film tends to decrease, and the productivity tends to decrease. When the content is too large, the water-soluble film is used as a package. There is a tendency to cause inconveniences such as a decrease in seal strength at the time of sealing.

  In the present invention, other water-soluble polymers (for example, sodium polyacrylate, polyethylene oxide, polyvinyl pyrrolidone, dextrin, chitosan, chitin, methylcellulose, hydroxyethylcellulose, etc.) , Fragrances, rust inhibitors, colorants, extenders, antifoaming agents, ultraviolet absorbers, liquid paraffins, fluorescent brighteners, bitterness components (for example, denatonium benzoate, etc.), and the like can also be included. These may be used alone or in combination of two or more.

  Moreover, in this invention, it is preferable to mix | blend antioxidant from the point of yellowing suppression. Examples of such antioxidants include sulfites such as sodium sulfite, potassium sulfite, calcium sulfite and ammonium sulfite, tartaric acid, ascorbic acid, sodium thiosulfate, catechol, Rongalite, etc. Among them, 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, and particularly preferably 0.3 to 3 parts by weight with respect to 100 parts by weight of the PVA resin (A).

<Method for producing water-soluble film>
This invention is a manufacturing method of the water-soluble film which contains PVA-type resin (A) and performs the following process [I] and [II] in order.
Step [I]: A step of forming a film-forming raw material containing the polyvinyl alcohol-based resin (A) and drying it to obtain a film.
Step [II]: A step of cooling the film to 40 ° C. or less within 20 seconds after heat-treating the dried film at 95 to 135 ° C.
That is, the present invention is characterized in that a water-soluble film before heat treatment is obtained by the step [I], and the film is rapidly cooled in a short time after the heat treatment in the subsequent step [II].
First, the step [I] will be described in order.

  The film-forming raw material in the step [I] is mainly composed of the PVA resin (A), preferably a plasticizer (B), and if necessary, a filler (C), a surfactant (D) and the like. It can be obtained by dissolving it in an aqueous solution or aqueous dispersion. Here, the main component means a component that greatly affects the properties of the water-soluble film, and the content of the component is usually 30% by weight or more of the entire film-forming raw material excluding water, preferably 50%. % By weight or more.

  Moreover, it is preferable that the solid content density | concentration of this film forming raw material is 10 to 50 weight%, It is especially preferable that it is 15 to 40 weight%, Furthermore, it is preferable to be 20 to 35 weight%. If the concentration is too low, the productivity of the water-soluble film tends to decrease. If the concentration is too high, the viscosity becomes too high, and it takes time to defoam the dope. Tend to.

As the dissolution method, normal temperature dissolution, high temperature dissolution, pressure dissolution and the like are usually employed. Among them, high temperature dissolution and pressure dissolution are preferable from the viewpoint of few undissolved materials and excellent productivity.
When the dissolution temperature is high-temperature dissolution, it is usually 80 to 100 ° C., preferably 90 to 100 ° C., and when it is dissolved under pressure, it is usually 80 to 130 ° C., preferably 90 to 120 ° C.
As dissolution time, it is 1 to 20 hours normally, Preferably it is 2 to 15 hours, More preferably, it is 3 to 10 hours. If the dissolution time is too short, undissolved products tend to remain, and if the dissolution time is too long, productivity tends to decrease.

In the melting step, examples of the stirring blade include paddle, full zone, max blend, twister, anchor, ribbon, and propeller.
Furthermore, after the dissolution, defoaming treatment is performed on the obtained film forming raw material. Examples of such defoaming methods include stationary defoaming, vacuum defoaming, and biaxial extrusion defoaming. . Of these, stationary defoaming and biaxial extrusion defoaming are preferable.
The temperature for stationary 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.
A water-soluble film before heat treatment is obtained by forming this film-forming raw material.

  In forming the film, for example, a method such as a melt extrusion method or a casting method can be employed, and the casting method is preferable in terms of film thickness accuracy.

In the casting method, the film-forming raw material is passed through a slit such as a T-die, and cast onto a cast surface such as a metal surface of an endless belt or a drum roll or a plastic substrate surface such as a polyethylene terephthalate film, and then dried. Thus, a pre-heat treatment film can be obtained.
For example, it can be performed under the following film forming conditions.

  The temperature of the film forming raw material in the discharge part 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. If the temperature is too high, foaming or the like tends to occur.

  In film formation, the film formation speed is preferably 3 to 80 m / min, particularly 5 to 60 m / min, more preferably 8 to 50 m / min.

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

  Moreover, the film-forming raw material can be cast on a plastic substrate such as a polyethylene terephthalate film or a polyethylene film or a metal substrate using an applicator and dried to obtain a pre-heat treatment film.

  Moreover, although drying can also be performed with a hot roll, a floating, a far-red process, etc. are mentioned other than that. In particular, it is preferable in terms of productivity to carry out with a hot roll. The drying temperature is preferably 50 to 150 ° C., particularly 70 to 130 ° C., more preferably 80 to 120 ° C., and the drying time is preferably 60 to 900 seconds. Is preferably 90 to 700 seconds, more preferably 120 to 400 seconds.

Moreover, it is preferable that the water content of the water-soluble film before heat treatment is usually 6 to 25% by weight, particularly 8 to 20% by weight, and more preferably 10 to 15% by weight.
In the present invention, the moisture content is measured in accordance with JIS K 6726 3.4, and the obtained volatile content is defined as the moisture content.

  The thickness of the water-soluble film before heat treatment is appropriately selected depending on the use and the like, but is preferably 10 to 130 μm, more preferably 15 to 120 μm, and particularly preferably 20 to 110 μm. If the thickness is too thin, the mechanical strength of the water-soluble film tends to decrease, and if it is too thick, the dissolution rate in water tends to be slow, and the film-forming efficiency tends to decrease.

Thus, a water-soluble film before heat treatment can be obtained through the step [I]. The obtained water-soluble film before heat treatment is then subjected to step [II]. In the present invention, concavo-convex processing such as an embossed pattern, fine concavo-convex pattern, special engraving pattern, and other steps may be performed before and / or after step [II].
Next, step [II] will be described.

  In general, when a water-soluble film is heat-treated, curling resistance is improved, but physical properties such as solubility and water-sealability are lowered. Therefore, the present invention is characterized in that the film after drying is heat-treated and then rapidly cooled in a short time in order to obtain a water-soluble film having excellent curl resistance, solubility and water sealability.

  Examples of the heat treatment of the film include (1) a method of contacting with a heat roll, (2) a method of passing through a heat chamber (floating, far-red treatment, etc.), etc., among others, (1) contacting with a heat roll. It is preferable in terms of productivity to carry out by the method. The heat treatment temperature is 80 to 135 ° C., particularly preferably 85 to 130 ° C., and the heat treatment time is preferably 1 to 120 seconds, particularly 3 to 110 seconds, and more preferably 5 to 5 seconds. Preferably it is 100 seconds.

  In the present invention, it is necessary to rapidly cool the heat-treated film below a predetermined temperature.

  That is, the water-soluble film after heat treatment is cooled to 40 ° C. or less, preferably 20 ° C. or less within 20 seconds, preferably within 15 seconds. Here, the lower limit of the time is usually 1 second, and the lower limit of the temperature of the film is usually 5 ° C.

  Examples of the cooling include (3) a method of contacting the cooling roll, (4) a method of passing the cooling chamber, and the like. Is preferable. As surface temperature of a cooling roll, it is 0-20 degreeC, and it is especially preferable that it is 5-15 degreeC.

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

The water content of the water-soluble film is preferably 3 to 15% by weight, particularly 5 to 14% by weight, and more preferably 6 to 13% by weight in terms of mechanical strength and sealability. . If the moisture content is too low, the film tends to be 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.
In addition, the said moisture content is measured based on JISK67263.4, and let the value of the obtained volatile matter be a moisture content.

  Thus, the water-soluble film obtained by the production method of the present invention is excellent in solubility and curl resistance and excellent in water sealability, and can be provided in various forms. The use thereof is not particularly limited, but is particularly useful for various packaging applications and the like, and particularly useful for unit packaging applications of drugs and the like, particularly liquid drugs. There is no restriction | limiting in particular as a chemical | medical agent, Any of alkaline, neutral, and acidic may be sufficient, and the shape of a chemical | medical agent may be any shapes, such as a granule, a tablet, powder, a powder, and a liquid. In particular, it is useful for packaging a liquid drug such as a liquid detergent used by dissolving or dispersing in water.

As the liquid drug, 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. 0.1 to 10% by weight, more preferably 0.1 to 7% by weight, and the film is excellent in water solubility without gelation or insolubilization.
The pH value is measured according to JIS K 3362 8.3. The water content is measured according to JIS K 3362 7.21.3.

<Drug package>
The drug package is formed by enclosing a liquid drug in a package made of a water-soluble film. When transporting or storing, the liquid medicine is held in its shape. During use (during washing, etc.), the package made of a water-soluble film dissolves in contact with water and is contained. The drug flows into the water and diffuses, and the drug comes into contact with the object to exert its medicinal effect.

  As said liquid chemical | medical agent, the liquid chemical | medical agent used for various washing | cleaning, disinfection, surface finishing, etc., such as washing of clothes, washing | cleaning of tableware, etc. is mention | raise | lifted. Specific examples include liquid detergents, softeners, fragrance finishes, bleaching / bactericidal agents, and the like, and among these, it is preferable to use them for liquid detergents.

  The size of the medicine package is usually 10 to 50 mm in length, preferably 20 to 40 mm. Moreover, the thickness of the film of the packaging body which consists of a water-soluble film is 10-120 micrometers normally, Preferably it is 15-110 micrometers, More preferably, it is 20-100 micrometers. The amount of the liquid medicine to be included is usually 5 to 50 mL, preferably 10 to 40 mL.

  The above-mentioned drug package has an embossed pattern on the outer surface of the package (water-soluble film) in terms of blocking resistance, slipperiness during processing, reduced adhesion between products (package), and appearance. It is preferable that the surface is subjected to uneven processing such as a fine uneven pattern or a special engraving pattern, but may be smooth.

  When obtaining a pharmaceutical package, water-soluble films are stacked and sealed, and for such seals, a water seal using water is used in addition to a heat seal that seals at least one water-soluble film heated and softened. For example, a glue seal using glue, and the like, and a method using a water seal using water is versatile and advantageous.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded.
In the examples, “parts” and “%” mean weight basis.

Prior to the examples, the following were prepared as PVA-based resins.
Carboxyl group-modified PVA (A1):
4% aqueous solution viscosity at 20 ° C. 22 mPa · s, average degree of saponification 94 mol%,
Amount modified with maleic acid monomethyl ester 2.0 mol%
-Unmodified PVA (A2):
4% aqueous solution viscosity at 20 ° C. 18 mPa · s, average saponification degree 88 mol%

<Example 1>
As PVA-based resin (A), 90 parts of carboxyl group-modified PVA (A1) having a modification amount of 2.0 mol% with maleic acid monomethyl ester, 10 parts of unmodified PVA (A2) having an average saponification degree of 88 mol%, 20 parts of sorbitol and 20 parts of glycerin as plasticizer (B), 8 parts of starch (average particle size 20 μm) as filler (C), polyoxyalkylene alkyl ether phosphate monoester as surfactant (D) 2 parts of ethanolamine salt and water were mixed and dissolved to obtain a film-forming raw material (solid content concentration 22%) in which starch was dispersed.
The obtained film forming raw material was defoamed at 80 ° C. and cooled to 40 ° C. The film-forming raw material was cast on a polyethylene terephthalate film (thickness: 125 μm, width: 300 mm) at a thickness of 630 μm and a width of 200 mm, and in a 3 m drying chamber (105 ° C.) at a speed of 0.350 m / min. It was passed through and dried to obtain a water-soluble film (F0) having a thickness of 89 μm before heat treatment.
The obtained pre-heat-treatment water-soluble film (F0) was attached to a 300 mm × 210 mm SUS frame with four sides fixed, and heat-treated by placing it in a hot air dryer set at 105 ° C. for 60 seconds, immediately thereafter The PVA film (F1) (water-soluble film) was obtained by quenching for 15 seconds with an iron plate cooled to 14 ° C. and cooling the film temperature to 30 ° C. or lower.
About the obtained PVA-type film (F1) (water-soluble film), it measured and evaluated as follows.

[Water sealability]
(Preparation of measurement specimen)
After adjusting the humidity of the PVA film to 23 ° C. and 40% RH for 24 hours, the PVA film is 50 mm so that one side is parallel to the MD direction (flow direction) from the center in the width direction of the PVA film. A film was cut into a square shape of × 50 mm to obtain a PVA film (α). Further, the PVA film is cut out from the center in the width direction of the PVA film so that the side parallel to the MD direction (flow direction) is a rectangle of 70 mm and the side parallel to the TD direction (width direction) is 15 mm. A film (β) was obtained.

(Measurement of peel strength)
The PVA film (α) cut out to 50 mm × 50 mm is placed on a 30 cm square glass plate with the cast surface facing upward, and a PVA system with a cotton swab (manufactured by Justeo Co., Ltd .: antibacterial swab) sufficiently containing water. Water was applied to the film (α) in a circle having a diameter of 1 cm. Then, the cast surface side of the PVA film (β) cut out to another 15 mm × 70 mm was placed on the PVA film (α) after 5 seconds from being wetted with water, and a weight of 85 g was slowly added. 2 sheets of PVA film were adhered to each other.
After this is left for 10 seconds, the lower PVA film (α) is fixed to the substrate glass, and a spring alone is attached to the end face of the upper PVA film (β), and pulled upward at a speed of 2 mm / second. Thus, peel strength (g / 15 mm) was measured. The measurement was performed in an environment of 23 ° C. and 40% RH.

  The peel strength of the water-sealed portion of the obtained PVA-based film of Example 1 was 100 g / 15 mm, and a sufficient peel strength was obtained.

<Comparative Example 1>
In Example 1, it carried out similarly except not having performed cooling processing, and obtained PVA system film (F ') (water-soluble film).
The obtained PVA film (F ′) (water-soluble film) was measured and evaluated in the same manner as in Example 1.

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

  The water-soluble film obtained by the production method of the present invention is excellent in solubility and curl resistance and excellent in water sealability, and can be used for various packaging applications. Useful for unit packaging applications.

Claims (8)

It is a manufacturing method of the water-soluble film containing a polyvinyl alcohol-type resin (A), Comprising: It performs in order of the following process [I] and [II], The manufacturing method of the water-soluble film characterized by the above-mentioned.
Step [I]: A step of forming a film-forming raw material containing the polyvinyl alcohol-based resin (A) and drying it to obtain a film.
Step [II]: A step of cooling the film to 40 ° C. or less within 20 seconds after heat-treating the dried film at 95 to 135 ° C.   The method for producing a water-soluble film according to claim 1, wherein the moisture content of the dried film is 6 to 25% by weight.   The method for producing a water-soluble film according to claim 1 or 2, wherein the heat treatment is performed for 1 to 120 seconds.   The method for producing a water-soluble film according to any one of claims 1 to 3, wherein the polyvinyl alcohol resin (A) contains an anionic group-modified polyvinyl alcohol resin.   It contains a plasticizer (B), The manufacturing method of the water-soluble film as described in any one of Claims 1-4 characterized by the above-mentioned.   Content of a plasticizer (B) is 20 weight part or more with respect to 100 weight part of polyvinyl alcohol-type resin (A), The water-soluble film as described in any one of Claims 1-5 characterized by the above-mentioned. Manufacturing method.   The water content of a water-soluble film is 3 to 15 weight%, The manufacturing method of the water-soluble film as described in any one of Claims 1-6 characterized by the above-mentioned.   It uses for a medicine packaging, The manufacturing method of the water-soluble film as described in any one of Claims 1-7 characterized by the above-mentioned.