Water-soluble film

Abstract

The present invention relates to a water-soluble film comprising a polysaccharide and a plasticizer, wherein the content of the plasticizer is 45%-85% by mass based on the mass of the water-soluble film.

Description

Water-soluble film

[0001] The present invention relates to a water-soluble film containing a polysaccharide, a pouch comprising the water-soluble film, a laminate comprising the water-soluble film and a support, and a coating agent for forming the water-soluble film.

[0002] Water-soluble films have been widely used in applications such as pouches for containing detergents, fragrances, medicines, etc., and demand for them is expanding due to their convenience. Known examples of water-soluble films include water-soluble films containing polysaccharides (see, for example, Patent Document 1).

[0003] Japanese Unexamined Patent Publication No. 60-58044

[0004] However, the water-soluble film disclosed in Patent Document 1 does not have sufficient mechanical strength, and when used in the form of a pouch, for example, breakage may occur during transportation.

[0005] Therefore, an object of the present invention is to provide a water-soluble film having excellent mechanical strength, a pouch comprising the water-soluble film, a laminate comprising the water-soluble film and a support, and a coating agent for forming the water-soluble film.

[0006] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the above problems can be solved, leading to the completion of the present invention. That is, the present invention includes the following preferred embodiments.

[0007] [1] A water-soluble film containing a polysaccharide and a plasticizer, wherein the content of the plasticizer is 45 to 85% by mass relative to the mass of the water-soluble film. [2] The water-soluble film according to [1], wherein the plasticizer is at least one selected from the group consisting of polyhydric alcohols, hydroxy acids, monosaccharides, and disaccharides. [3] The water-soluble film according to [1] or [2], wherein the plasticizer is at least one selected from the group consisting of glycerin, diglycerin, sorbitol, alkylene glycol, polyalkylene glycol, trimethylolpropane, erythritol, 2-methyl-1,3-propanediol, lactic acid, glucose, fructose, maltose, and trehalose. [4] The water-soluble film according to any one of [1] to [3], wherein the plasticizer is at least one selected from the group consisting of glycerin, ethylene glycol, sorbitol, and fructose. [5] The water-soluble film according to any one of [1] to [4], wherein the polysaccharide is at least one selected from the group consisting of carrageenan, alginic acid, guar gum, xanthan gum, pectin, hydroxyalkyl cellulose, alkyl cellulose, tamarind seed gum, agar, pullulan, locust bean gum, tara gum, and derivatives thereof. [6] The water-soluble film according to any one of [1] to [5], wherein the polysaccharide is at least one selected from the group consisting of carrageenan, alginic acid, guar gum, xanthan gum, tamarind seed gum, locust bean gum, tara gum, and derivatives thereof. [7] The water-soluble film according to any one of [1] to [6], wherein the content of the polysaccharide is 5 to 55% by mass relative to the mass of the water-soluble film. [8] The water-soluble film according to any one of [1] to [7], wherein the water-soluble film contains two or more types of the polysaccharide. [9] The water-soluble film according to any one of [1] to [8], wherein the toughness is 700 or more.

[10] The water-soluble film according to any one of [1] to [9], which dissolves in water at 10° C. within 1,000 seconds.

[11] The water-soluble film according to any one of [1] to

[10] , which is a coating film formed from a coating agent containing a polysaccharide and a plasticizer.

[12] A laminate comprising the water-soluble film according to any one of [1] to

[10] and a support, wherein the support is paper or film.

[13] A pouch comprising the water-soluble film according to any one of [1] to

[10] .

[14] The pouch according to

[13] , which contains therein at least one selected from the group consisting of a cleaning agent, a fabric softener, and a fragrance.

[15] A coating agent comprising a polysaccharide and a plasticizer, wherein the content of the plasticizer is 45 to 85% by mass relative to the mass of the solid content of the coating agent.

[0008] According to the present invention, it is possible to provide a water-soluble film having excellent mechanical strength, a laminate including the water-soluble film and a support, and a coating agent for forming the water-soluble film.

[0009] Hereinafter, embodiments of the present invention will be described in detail. Note that the following description is merely illustrative of embodiments of the present invention, and is not intended to limit the present invention to the following embodiments. Note that the upper and lower limits described in this specification can be arbitrarily combined to form a suitable numerical range.

[0010] [Water-soluble film] The water-soluble film of the present invention contains a polysaccharide and a plasticizer, and the content of the plasticizer is 45 to 85 mass% based on the mass of the water-soluble film. In this specification, mechanical strength means mechanical strength including "toughness", which is the product of the maximum stress (MPa) and the breaking elongation (%).

[0011] The present inventors have conducted further studies on the water solubility and strength of films and have unexpectedly found that, in a film containing a polysaccharide and a plasticizer, adjusting the plasticizer content to 45 to 85% by mass can improve the mechanical strength while maintaining water solubility. Although the reason for this effect is unclear, it is presumed that the polysaccharide and a specific amount of plasticizer form a high-order network, which allows both maximum stress and breaking elongation to be achieved at high levels.

[0012] <Polysaccharides> Polysaccharides refer to carbohydrates composed of 10 or more monosaccharides bonded together. Examples of polysaccharides include starch, chitin, chitosan, cellulose, hemicellulose, dextrin, gum arabic, carrageenan, alginic acid, guar gum, xanthan gum, pectin, hydroxyalkyl cellulose, alkyl cellulose, carboxyalkyl cellulose, tamarind seed gum, agar, pullulan, locust bean gum, tara gum, karaya gum, succinoglycan, and derivatives thereof. These polysaccharides may be used alone or in combination of two or more. Among these, from the viewpoint of ensuring the water solubility of the water-soluble film while further increasing its mechanical strength, the polysaccharide is preferably at least one selected from the group consisting of carrageenan, alginic acid, guar gum, xanthan gum, pectin, hydroxyalkyl cellulose, alkyl cellulose, tamarind seed gum, agar, pullulan, locust bean gum, tara gum, and derivatives thereof, more preferably at least one selected from the group consisting of carrageenan, alginic acid, guar gum, xanthan gum, tamarind seed gum, locust bean gum, tara gum, and derivatives thereof, even more preferably at least one selected from the group consisting of tamarind seed gum, carrageenan, and alginic acid, and particularly preferably contains tamarind seed gum.

[0013] In one embodiment of the present invention, from the viewpoint of achieving both excellent mechanical strength and low-temperature solubility, the polysaccharide is preferably at least one selected from the group consisting of guar gum, xanthan gum, tamarind seed gum, locust bean gum, tara gum, and derivatives thereof, and more preferably includes tamarind seed gum.

[0014] In one embodiment of the present invention, the number-average molecular weight (sometimes referred to as Mn) of the polysaccharide is preferably 5 kDa to 50,000 kDa, more preferably 7 kDa to 10,000 kDa, and even more preferably 10 kDa to 5,000 kDa, for example, 5 kDa to 3,000 kDa, 10 kDa to 1,000 kDa, or 15 kDa to 700 kDa. The weight-average molecular weight (sometimes referred to as Mw) of the polysaccharide is preferably 5 kDa to 150,000 kDa, more preferably 10 kDa to 50,000 kDa, and even more preferably 20 kDa to 30,000 kDa, for example, 30 kDa to 10,000 kDa, 50 kDa to 7,000 kDa, or 70 kDa to 5,000 kDa. When the Mn and / or Mw of the polysaccharide are within the above ranges, the water solubility, mechanical strength, and low-temperature solubility of the water-soluble film can be improved. When the polysaccharide is composed of two or more polysaccharides, the Mn of the polysaccharide is a weighted average of the Mn of the two or more polysaccharides. The same applies to the Mw.

[0015] Tamarind seed gum is a polysaccharide obtained from the seeds of tamarind (Tamarindus indica) and has a structure in which glucose is the main chain and xylose and galactose are bonded to the side chains. Commercially available tamarind seed gum, such as "Glyloid (registered trademark)" and "Glyate (registered trademark)" (manufactured by MP Gokyo Food & Chemical Co., Ltd.), and "TG120" (manufactured by Mitsubishi Chemical Corporation), may be used. The Mn of the tamarind seed gum is preferably 10 kDa to 3,000 kDa, more preferably 30 kDa to 1,000 kDa, and even more preferably 50 kDa to 500 kDa, and may be, for example, 100 kDa to 500 kDa. The Mw of the tamarind seed gum is preferably 10 kDa to 50,000 kDa, more preferably 30 kDa to 10,000 kDa, and even more preferably 50 kDa to 5,000 kDa, for example, 500 kDa to 4,500 kDa or 1,000 kDa to 4,000 kDa.

[0016] Carrageenan is a polysaccharide obtained from red algae and contains repeating units of D-galactose or 3,6-anhydro-D-galactose, as well as sulfate groups. Carrageenan is classified into κ (kappa) carrageenan, ι (iota) carrageenan, and λ (lambda) carrageenan. These may be used alone or in combination. Commercially available carrageenans include "GENUGEL carrageenan type JPE-126" (manufactured by Sansho Co., Ltd.), "GENUTINE VCS-J" (manufactured by Sansho Co., Ltd.), "MW210," "MV320," and "MW-952" (manufactured by Mitsubishi Chemical Corporation). The Mn of the carrageenan is preferably 5 kDa to 5,000 kDa, more preferably 10 kDa to 3,000 kDa, and even more preferably 20 kDa to 1,000 kDa, for example, 25 kDa to 500 kDa or 30 kDa to 200 kDa. The Mw of the carrageenan is preferably 5 kDa to 15,000 kDa, more preferably 10 kDa to 10,000 kDa, and even more preferably 20 kDa to 5,000 kDa, for example, 50 kDa to 2,000 kDa or 100 kDa to 1,000 kDa.

[0017] Xanthan gum is a polysaccharide produced by fermenting starch with the bacterium Xanthomonas campestris. It has a glucose backbone and a side chain containing one glucuronic acid between two mannose units. Commercially available xanthan gums may be used, such as "Kimika Xanthan PH-R3EC" (manufactured by Kimika Co., Ltd.), "Echo Gum (registered trademark)" (manufactured by MP Gokyo Food & Chemical Co., Ltd.), "Soaxan," and "XG800" (manufactured by Mitsubishi Chemical Corporation). The Mn of xanthan gum is preferably 5 kDa to 50,000 kDa, more preferably 7 kDa to 10,000 kDa, and even more preferably 10 kDa to 5,000 kDa, and may be, for example, 10 kDa to 1,000 kDa or 15 kDa to 100 kDa. The Mw of xanthan gum is preferably 5 kDa to 150,000 kDa, more preferably 7 kDa to 50,000 kDa, and even more preferably 10 kDa to 30,000 kDa, for example, 10 kDa to 5,000 kDa, 30 kDa to 1,000 kDa, or 50 kDa to 500 kDa.

[0018] Guar gum is a polysaccharide obtained from the endosperm of guar beans (Cyamopsis tetragonoloba) and has a structure in which mannose is the main chain and galactose is bonded to the side chain. Commercially available guar gums may be used, such as "SUPERGEL CSA200 / 50" (manufactured by Sansho Co., Ltd.), "Guapak (registered trademark)" (manufactured by MP Gokyo Food & Chemical Co., Ltd.), and "RG100" (manufactured by Mitsubishi Chemical Corporation). The Mn of guar gum is preferably 5k to 20,000 kDa, more preferably 5k to 10,000 kDa, and even more preferably 7k to 5,000 kDa, and may be, for example, 10k to 1,000 kDa or 15k to 100 kDa. The Mw of the guar gum is preferably 5 kDa to 100,000 kDa, more preferably 5 kDa to 50,000 kDa, and even more preferably 7 kDa to 20,000 kDa, and may be, for example, 10 kDa to 5,000 kDa, 30 kDa to 1,000 kDa, or 50 kDa to 500 kDa.

[0019] Locust bean gum is a polysaccharide obtained from the seeds of carob (Celatonia siliqua) and has a structure in which mannose is the main chain and galactose is bound to the side chain. Commercially available locust bean gums may be used, such as "GENU (registered trademark) GUM type RL-200Z" (manufactured by Sansho Co., Ltd.), "Soarlocust A120," "MC1000," and "Soarlocust A200" (manufactured by Mitsubishi Chemical Corporation). The Mn of the locust bean gum is preferably 5 kDa to 50,000 kDa, more preferably 7 kDa to 10,000 kDa, and even more preferably 10 kDa to 5,000 kDa, and may be, for example, 15 kDa to 1,000 kDa or 20 kDa to 300 kDa. The Mw of the locust bean gum is preferably 5 kDa to 150,000 kDa, more preferably 10 kDa to 30,000 kDa, and even more preferably 15 kDa to 15,000 kDa, for example, 20 kDa to 5,000 kDa, 30 kDa to 1,000 kDa, or 50 kDa to 500 kDa.

[0020] Tara gum is a polysaccharide obtained from the seeds of tara (Caesalpinia spinosa) and has a structure in which mannose is the main chain and galactose is bound to the side chain. Commercially available tara gum products, such as "MT120" and "MT1000" (manufactured by Mitsubishi Chemical Corporation), may be used. The Mn of tara gum is preferably 5k to 10,000 kDa, more preferably 5k to 5,000 kDa, and even more preferably 10k to 1,000 kDa. The Mw of tara gum is preferably 5k to 30,000 kDa, more preferably 10k to 15,000 kDa, and even more preferably 15k to 10,000 kDa.

[0021] The Mn of the alginic acid is preferably 5k to 50,000 kDa, more preferably 7k to 10,000 kDa, and even more preferably 10k to 5,000 kDa, for example, 15 to 1,000 kDa or 20 to 300 kDa. The Mw of the alginic acid is preferably 5k to 150,000 kDa, more preferably 10k to 30,000 kDa, and even more preferably 15k to 15,000 kDa, for example, 20k to 5,000 kDa, 30k to 1,000 kDa, or 50k to 500 kDa. When the Mn and / or Mw of each of the above polysaccharides are within the above ranges, the water solubility, mechanical strength, and low-temperature solubility of the water-soluble film can be improved. The polysaccharides may also include polysaccharides of the same type but with different Mn and / or Mw. In addition, in this specification, the Mn and Mw of a polysaccharide can be determined by gel filtration HPLC, for example, by the method described in the Examples below.

[0022] Examples of hydroxyalkyl cellulose include hydroxyalkyl celluloses having 2 to 10 carbon atoms in the hydroxyalkyl group, such as hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, and hydroxyethyl methyl cellulose, preferably hydroxyalkyl celluloses having 2 to 6 carbon atoms in the hydroxyalkyl group. Examples of alkyl cellulose include alkyl celluloses having 2 to 10 carbon atoms in the alkyl group, such as methyl cellulose, ethyl cellulose, propyl cellulose, and butyl cellulose, and alkyl celluloses having 2 to 6 carbon atoms in the alkyl group. The hydroxyalkyl cellulose refers to cellulose in which one or more hydroxyl groups are modified with a hydroxyalkyl group, and the alkyl cellulose refers to cellulose in which one or more hydroxyl groups are modified with an alkyl group. The carbon numbers of the hydroxyalkyl group and the alkyl group refer to the carbon numbers of one hydroxyalkyl group and one alkyl group, respectively.

[0023] Derivatives of these polysaccharides include, for example, sodium salts, potassium salts, calcium salts, enzyme-treated products, acid hydrolysates, etherified products, carboxyl alkylated products, aminated products and their hydrochlorides, phosphates, esterified products, crosslinked products, and oxides. Polysaccharide A may be used singly or in combination of two or more.

[0024] In one embodiment of the present invention, the polysaccharide content is preferably 5 to 55% by mass, more preferably 10 to 53% by mass, even more preferably 15 to 52% by mass, 15 to 51% by mass, or 17 to 50% by mass, still more preferably 20% by mass or more but less than 50% by mass, or 25 to 49% by mass, particularly preferably 28 to 48% by mass or 29 to 47% by mass, especially preferably 30 to 45% by mass or 30 to 43% by mass, and especially even more preferably 31 to 40% by mass or 32 to 39% by mass, based on the mass of the water-soluble film. When the polysaccharide content is within the above range, the water solubility, mechanical strength, and low-temperature solubility of the water-soluble film can be improved.

[0025] In one embodiment of the present invention, the water-soluble film may contain two or more polysaccharides. When two or more polysaccharides are contained, the two or more polysaccharides can form a higher-order network through hydrogen bonding or the like, thereby improving the mechanical strength. The water-soluble film may preferably contain two or more or three or more polysaccharides, and may preferably contain five or fewer, more preferably four or fewer, polysaccharides.

[0026] In one embodiment of the present invention, when the water-soluble film contains two or more polysaccharides, from the viewpoint of increasing the mechanical strength while maintaining the water solubility of the water-soluble film, it preferably contains polysaccharide A and polysaccharide B different from polysaccharide A. Polysaccharide A is preferably at least one selected from the group consisting of carrageenan, alginic acid, guar gum, xanthan gum, pectin, hydroxyalkyl cellulose, alkyl cellulose, tamarind seed gum, agar, pullulan, locust bean gum, tara gum, and derivatives thereof, more preferably at least one selected from the group consisting of carrageenan, alginic acid, tamarind seed gum, locust bean gum, tara gum, and derivatives thereof, even more preferably at least one selected from the group consisting of carrageenan, alginic acid, tamarind seed gum, and derivatives thereof, and particularly preferably tamarind seed gum. Furthermore, polysaccharide B is a polysaccharide different from polysaccharide A, and is preferably at least one selected from the group consisting of carrageenan, alginic acid, guar gum, xanthan gum, hydroxyalkyl cellulose, alkyl cellulose, tamarind seed gum, locust bean gum, tara gum, and derivatives thereof, more preferably at least one selected from the group consisting of carrageenan, alginic acid, guar gum, xanthan gum, locust bean gum, tara gum, and derivatives thereof, and even more preferably at least one selected from the group consisting of carrageenan, guar gum, xanthan gum, locust bean gum, and derivatives thereof.

[0027] In one embodiment of the present invention, from the viewpoint of improving the mechanical strength of the water-soluble film, it is preferable that polysaccharide A is tamarind seed gum or a derivative thereof, and polysaccharide B is at least one selected from the group consisting of carrageenan, alginic acid, guar gum, xanthan gum, hydroxyalkyl cellulose, alkyl cellulose, tamarind seed gum, locust bean gum, tara gum, and derivatives thereof, and it is more preferable that polysaccharide A is tamarind seed gum or a derivative thereof, and polysaccharide B is at least one selected from the group consisting of carrageenan, alginic acid, guar gum, xanthan gum, locust bean gum, tara gum, and derivatives thereof. Furthermore, from the viewpoint of further improving the mechanical strength of the water-soluble film, it is more preferable that polysaccharide A is tamarind seed gum or a derivative thereof, and polysaccharide B is at least one selected from the group consisting of carrageenan, guar gum, xanthan gum, locust bean gum, and derivatives thereof; and from the viewpoint of achieving excellent low-temperature solubility and mechanical strength of the water-soluble film, it is particularly preferable that polysaccharide A is tamarind seed gum or a derivative thereof, and polysaccharide B is at least one selected from guar gum, xanthan gum, locust bean gum, and derivatives thereof.

[0028] In one embodiment of the present invention, the combination of polysaccharide A / polysaccharide B is preferably tamarind seed gum / carrageenan, tamarind seed gum / xanthan gum, tamarind seed gum / guar gum, tamarind seed gum / locust bean gum, tamarind seed gum / starch, etc., from the viewpoint of maintaining the water solubility of the water-soluble film while further improving the mechanical strength, and more preferably tamarind seed gum / xanthan gum, tamarind seed gum / guar gum, tamarind seed gum / locust bean gum, etc. Furthermore, the combination of polysaccharide A / polysaccharide B-1 / polysaccharide B-2 is preferably tamarind seed gum / xanthan gum / guar gum, tamarind seed gum / xanthan gum / locust bean gum, etc., from the viewpoint of achieving both excellent mechanical strength and low-temperature solubility of the water-soluble film.

[0029] In one embodiment of the present invention, the Mn of polysaccharide A is preferably 5 kDa to 50,000 kDa, more preferably 7 kDa to 10,000 kDa, even more preferably 10 kDa to 5,000 kDa, for example, 5 kDa to 3,000 kDa, 10 kDa to 1,000 kDa, or 15 kDa to 700 kDa. The Mw of polysaccharide A is preferably 5 kDa to 150,000 kDa, more preferably 10 kDa to 50,000 kDa, even more preferably 20 kDa to 30,000 kDa, for example, 30 kDa to 10,000 kDa, 50 kDa to 7,000 kDa, or 70 kDa to 5,000 kDa. The Mn of polysaccharide B is preferably 5 kDa to 50,000 kDa, more preferably 7 kDa to 10,000 kDa, and even more preferably 10 kDa to 5,000 kDa, for example, 5 kDa to 1,000 kDa, 10 kDa to 500 kDa, or 15 kDa to 200 kDa. The Mw of polysaccharide B is preferably 5 kDa to 150,000 kDa, more preferably 10 kDa to 50,000 kDa, and even more preferably 20 kDa to 30,000 kDa, for example, 10 kDa to 10,000 kDa, 30 kDa to 5,000 kDa, or 50 kDa to 1,000 kDa. When the Mn and / or Mw of each polysaccharide is within the above range, the water solubility, mechanical strength, and low-temperature solubility of the water-soluble film can be further improved. When each polysaccharide is composed of two or more kinds of polysaccharides, the Mn of each polysaccharide is a weighted average of the Mn of the two or more kinds of polysaccharides, and the same applies to the Mw.

[0030] In one embodiment of the present invention, the content of polysaccharide A is preferably 2 to 50% by mass, more preferably 5 to 48% by mass, even more preferably 10 to 48% by mass, even more preferably 15 to 47% by mass, 16 to 46% by mass, or 17 to 45% by mass, even more preferably 20 to 44% by mass, particularly preferably 25 to 43% by mass or 30 to 43% by mass, and especially preferably 30 to 42% by mass, 32 to 42% by mass, or 35 to 41% by mass, based on the mass of the water-soluble film. When the content of polysaccharide A is within the above range, the water solubility, mechanical strength, and low-temperature solubility of the water-soluble film can be improved. The content of polysaccharide B is preferably 0.5 to 20% by mass, more preferably 1 to 15% by mass, and even more preferably 1.5 to 10% by mass or 3 to 9.5% by mass, based on the mass of the water-soluble film. When the content of polysaccharide B is within the above range, the water solubility, mechanical strength, and low-temperature solubility of the water-soluble film can be improved.

[0031] In one embodiment of the present invention, the content ratio (mass ratio) of polysaccharide A to polysaccharide B is preferably 99.9:0.1 to 50:50, more preferably 99.5:0.5 to 60:40, even more preferably 99:1 to 70:30, still more preferably 98:2 to 75:25, and particularly preferably 97:3 to 80:20, 97:3 to 85:15, or 96:4 to 87:13. When the content ratio of polysaccharide A to polysaccharide B is within the above range, the water solubility, mechanical strength, and low-temperature solubility of the water-soluble film can be improved.

[0032] <Plasticizer> The water-soluble film of the present invention contains 45 to 85% by mass of a plasticizer relative to the mass of the water-soluble film. By containing 45 to 85% by mass of a plasticizer, excellent mechanical strength can be achieved. In particular, toughness can be improved by increasing the breaking elongation while ensuring a high maximum stress. Furthermore, processability can be improved, such as facilitating film formation.

[0033] In the water-soluble film of the present invention, the plasticizer content is preferably 47 to 85% by mass, more preferably 48 to 85% by mass, 49 to 85% by mass, or 50 to 83% by mass, even more preferably more than 50% by mass but not more than 80% by mass, or 51 to 75% by mass, still more preferably 52 to 72% by mass or 53 to 71% by mass, particularly preferably 55 to 70% by mass or 57 to 70% by mass, and especially preferably 60 to 69% by mass or 61 to 68% by mass. When the plasticizer content is within the above range, the water-soluble film can maintain its water solubility while further improving its mechanical strength and processability.

[0034] In one embodiment of the present invention, the polysaccharide to plasticizer content ratio (mass ratio) is preferably 52:48 to 15:85, 51:49 to 15:85, or 50:50 to 17:83, more preferably 50:50 to 20:80, or 49:51 to 25:75, even more preferably 48:52 to 28:72, or 47:53 to 29:71, still more preferably 45:55 to 30:70, or 43:57 to 30:70, and particularly preferably 40:60 to 31:69, or 39:61 to 32:68. When the polysaccharide to plasticizer content ratio is within the above range, the water solubility of the water-soluble film can be maintained while further improving the mechanical strength and processability.

[0035] The plasticizer is preferably at least one selected from the group consisting of polyhydric alcohols, hydroxy acids, monosaccharides, and disaccharides. It can aggregate polysaccharide A by dehydration. Furthermore, it can form a high-order network by hydrogen bonding with the polysaccharide, thereby improving processability and further increasing the mechanical strength of the water-soluble film. One type of plasticizer may be used alone, or two or more types may be used in combination.

[0036] Examples of the polyhydric alcohol include glycerin, diglycerin, sorbitol, alkylene glycols (e.g., alkylene glycols having 2 to 10 carbon atoms, such as ethylene glycol, propylene glycol, and neopentyl glycol), polyalkylene glycols (e.g., diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols having a molecular weight of up to 400, and polypropylene glycols having a molecular weight of up to 400), trimethylolpropane, erythritol, xylitol, 2-methyl-1,3-propanediol, maltitol, mannitol, and pentaerythritol.

[0037] Examples of the hydroxy acid include lactic acid, glycolic acid, malic acid, and tartaric acid.

[0038] Examples of the monosaccharides include glucose, mannose, galactose, fructose, and xylose.

[0039] Examples of the disaccharides include maltose, trehalose, sucrose, and lactose.

[0040] Among these, from the viewpoint of increasing the mechanical strength while maintaining the water solubility of the water-soluble film, at least one selected from the group consisting of glycerin, diglycerin, sorbitol, alkylene glycol, trimethylolpropane, erythritol, 2-methyl-1,3-propanediol, lactic acid, glucose, fructose, maltose, and trehalose is preferred, and at least one selected from the group consisting of glycerin, ethylene glycol, sorbitol, and fructose is more preferred.

[0041] <Additives> The water-soluble film of the present invention may contain additives other than polysaccharides and plasticizers to the extent that the effects of the present invention are not impaired. Examples of additives include dispersants, moisture, antioxidants, UV absorbers, lubricants, colorants, preservatives, fillers, crosslinking agents, etc. One type of additive may be used alone, or two or more types may be used in combination.

[0042] Fillers refer to components that are incompatible with polysaccharides and plasticizers. When a water-soluble film contains a filler, it can form a high-order network by hydrogen bonding with the polysaccharides and plasticizers, thereby improving the stress of the resulting water-soluble film. Furthermore, when preparing a water-soluble film by coating, adding a filler to the coating agent increases the solids concentration, allowing the thickness of the coating film to be increased.

[0043] Examples of fillers include inorganic pigments such as kaolin, clay, engineered kaolin, delaminated clay, heavy calcium carbonate, light calcium carbonate, mica (swelling mica, synthetic mica, white mica (muscovite), sericite (sericite), phloxopite, biotite, fluorphlogopite (artificial mica), red mica, soda mica, vanadium mica, illite, zinc mica, paragonite, brittle mica, etc.), talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicates, bentonite (montmorillonite, beidellite, saponite, stevensite, hectorite, etc.), colloidal silica, and satin white, as well as solid, hollow, or core-shell organic pigments. These fillers may be used singly or in combination of two or more.

[0044] When the water-soluble film contains a filler, the total content of the filler relative to the mass of the water-soluble film is preferably 0.1 to 50 mass%, more preferably 0.5 to 35 mass%, even more preferably 1 to 30 mass%, even more preferably 1.5 to 20 mass%, even more preferably 2 to 18 mass%, even more preferably 2 to 15 mass%, even more preferably 2 to 10 mass%, and particularly preferably 2 to 6 mass%, from the viewpoint of improving the stress of the resulting water-soluble film. Also, from the viewpoint of increasing the thickness of the coating film, the total content of the filler is preferably 1 to 90 mass%, more preferably 5 to 80 mass%, even more preferably 10 to 75 mass%, even more preferably 20 to 70 mass%, even more preferably 30 to 65 mass%, even more preferably 40 to 60 mass%, even more preferably 42 to 58 mass%, and particularly preferably 45 to 55 mass%.

[0045] A dispersant may also be added separately to the coating agent used to produce the water-soluble film. The addition of a dispersant can improve the dispersibility of the filler. The dispersant is preferably a cationic polymer, and examples thereof include polyalkylene polyamines, polyamide compounds, polyamidoamine-epihalohydrin or formaldehyde condensation products, polyamine-epihalohydrin or formaldehyde condensation products, polyamide polyurea-epihalohydrin or formaldehyde condensation products, polyamine polyurea-epihalohydrin or formaldehyde condensation products, polyamidoamine polyurea-epihalohydrin or formaldehyde condensation products, polyamide polyurea compounds, polyamine polyurea compounds, polyamidoamine polyurea compounds, polyamide amine compounds, polyethyleneimine, polyvinylpyridine, amino-modified acrylamide compounds, polyvinylamine, polydiallyldimethylammonium chloride, and modified polyvinyl alcohol. The dispersant may be used alone or in combination of two or more. When the water-soluble film contains a dispersant, the content of the dispersant is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, and even more preferably 1 to 5% by mass, based on the mass of the water-soluble film.

[0046] Examples of crosslinking agents include tannic acid and its salts, tannins other than tannic acid, catechin, anthocyanin, gallic acid and its salts, phenols, and hydroquinone.

[0047] The content of the additive is not particularly limited as long as it does not interfere with the effects of the present invention, but is, for example, about 0 to 10% by mass, preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass, and even more preferably 0.1 to 1% by mass, relative to the mass of the water-soluble film.

[0048] In one embodiment of the present invention, the content of the polyvinyl alcohol-based resin in the water-soluble film of the present invention is preferably less than 30% by mass, more preferably 20% by mass or less, even more preferably 10% by mass or less, even more preferably 5% by mass or less, particularly preferably 1% by mass or less, especially preferably 0.1% by mass, and even 0% by mass. That is, it is preferably 0 to less than 30% by mass, more preferably 0 to 20% by mass, even more preferably 0 to 10% by mass, even more preferably 0 to 5% by mass, especially preferably 0 to 1% by mass, and especially preferably 0 to 0.1% by mass. The polyvinyl alcohol-based resin used in the present invention can be made from vinyl acetate containing petroleum-derived carbon, vinyl acetate containing biomass-derived carbon, or a mixture thereof. Alternatively, a polyvinyl alcohol-based resin whose apparent biomass ratio has been changed using a mass balance method may be used.

[0049] In one embodiment of the present invention, the total content of the polysaccharides and plasticizers contained in the water-soluble film is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, particularly preferably 95% by mass or more, and especially preferably 98% by mass or more, based on the mass of the water-soluble film. That is, it is preferably 30 to 100% by mass, more preferably 50 to 100% by mass, even more preferably 70 to 100% by mass, even more preferably 80 to 100% by mass, particularly preferably 90 to 100% by mass, especially more preferably 95 to 100% by mass, and especially preferably 98 to 100% by mass. When the total content of the polysaccharides and plasticizers contained in the water-soluble film is within the above range, the water solubility, mechanical strength, and low-temperature solubility of the water-soluble film can be further improved.

[0050] <Water-Soluble Film> The water-soluble film of the present invention has excellent mechanical strength because it contains the plasticizer in an amount of 45 to 85% by mass in addition to the polysaccharide. In this specification, "water-soluble" means that it is soluble in water, preferably having a solubility of 90% by mass or more in 90°C hot water. That is, a water-soluble film can be evaluated as water-soluble if, after adding the film to 90°C hot water and stirring for 5 minutes to dissolve the film, the amount of solids that do not pass through a filter (21 μm) is 10% by mass or less. The mass of the water-soluble film to be dissolved in 90°C hot water is 0.1 parts by mass per 100 parts by mass of 90°C hot water. The solubility of the water-soluble film in 90°C hot water is 90% by mass or more, preferably 95% by mass or more, and more preferably 98% by mass or more. When the solubility is above the lower limit, for example, residue is less likely to remain when the water-soluble film is dissolved in water. The upper limit of the solubility of the water-soluble film is 100% by mass. That is, the solubility of the water-soluble film is 90 to 100% by mass, preferably 95 to 100% by mass, and more preferably 98 to 100% by mass. The solubility of the water-soluble film can be adjusted to be equal to or higher than the above lower limit by, for example, appropriately adjusting the types and / or amounts of components contained in the water-soluble film.

[0051] In one embodiment of the present invention, the water-soluble film can achieve both high low-temperature solubility and high mechanical strength. Low-temperature solubility refers to the solubility of the water-soluble film at low temperatures (e.g., 10°C). In one embodiment of the present invention, the water-soluble film of the present invention can be dissolved in water at 10°C preferably within 1000 seconds. That is, when a water-soluble film measuring 30 mm long, 40 mm wide, and 50 μm thick is immersed in 500 mL of water at 10°C, the time required for complete dissolution is preferably within 1000 seconds, more preferably within 700 seconds, even more preferably within 600 seconds, and even more preferably within 500 seconds, and may be, for example, within 300 seconds or within 180 seconds. When the complete dissolution time of the water-soluble film in water at 10°C is equal to or less than the upper limit, the water-soluble film can be quickly dissolved even when dissolved in cold water for use. For example, in the case of a pouch containing the water-soluble film, this is preferable because the contents are quickly released even when dissolved in cold water for use. Furthermore, residue is less likely to remain. Note that there is no particular lower limit on the complete dissolution time, and the shorter the time required for complete dissolution, the better. The time required for complete dissolution of the water-soluble film in water at 10°C can be adjusted to the above upper limit or less by appropriately adjusting, for example, the types and / or amounts of components contained in the water-soluble film, the production conditions of the water-soluble film (drying conditions, etc.), etc. The time required for complete dissolution in water at 10°C can be determined, for example, by the method described in the Examples below.

[0052] The water-soluble film of the present invention can achieve both high levels of maximum stress and breaking elongation, and therefore has excellent toughness.In one embodiment of the present invention, the maximum stress of the water-soluble film is preferably 5 MPa or more, more preferably 10 MPa or more, even more preferably 15 MPa or more, even more preferably 20 MPa or more, particularly preferably 25 MPa or more, and particularly preferably 30 MPa or more, and may be, for example, 35 MPa, 40 MPa, 45 MPa, or 50 MPa or more.When the maximum stress of the water-soluble film is above the above-mentioned lower limit, the mechanical strength of the water-soluble film can be improved.The upper limit of the maximum stress of the water-soluble film is usually 150 MPa or less, preferably 140 MPa or less. That is, preferred ranges are 5 to 150 MPa, 10 to 150 MPa, 15 to 150 MPa, 20 to 150 MPa, 25 to 150 MPa, 30 to 150 MPa, 35 to 150 MPa, 40 to 150 MPa, 45 to 150 MPa, or 50 to 140 MPa.

[0053] In one embodiment of the present invention, the breaking elongation of the water-soluble film is preferably 10% or more, more preferably 25% or more, even more preferably 35% or more, even more preferably 40% or more, particularly preferably 50% or more, particularly more preferably 70% or more, especially more preferably 75% or more, and extremely preferably 80% or more or 85% or more, for example, 90% or more, 95% or more, or even 100% or more. When the breaking elongation of the water-soluble film is above the lower limit, the mechanical strength of the water-soluble film can be improved. The upper limit of the breaking elongation of the water-soluble film is usually 300% or less, preferably 200% or less. That is, preferred ranges are 10 to 150%, 25 to 150%, 35 to 150%, 40 to 150%, 50 to 150%, 70 to 150%, 75 to 150%, 80 to 150%, 85 to 150%, 90 to 150%, 95 to 150%, or 100 to 140%. The maximum stress and breaking elongation of the water-soluble film can be determined by a tensile test, for example, by the method described in the Examples below.

[0054] In one embodiment of the present invention, the toughness of the water-soluble film is preferably 700 or more, more preferably 900 or more, even more preferably 1100 or more, even more preferably 1200 or more, particularly preferably 1300 or more, particularly more preferably 1400 or more, particularly more preferably 1500 or more, and extremely preferably 1600 or more, for example, 1700 or more, 1800 or more, 1900 or more, 2000 or more, or 2200 or more. When the toughness of the water-soluble film is above the lower limit, the mechanical strength of the water-soluble film can be improved. The upper limit of the toughness is usually 4000 or less, preferably 3000 or less. That is, preferred ranges are 700 to 4000, 900 to 4000, 1100 to 4000, 1200 to 4000, 1300 to 4000, 1400 to 4000, 1500 to 4000, 1600 to 4000, 1700 to 4000, 1800 to 4000, 1900 to 4000, 2000 to 4000, or 2200 to 3000. The toughness of the water-soluble film can be determined by multiplying the maximum stress in a tensile test by the elongation at break.

[0055] The water-soluble film may be a single-layer film or a multi-layer film in which a plurality of the water-soluble films are laminated. From the viewpoints of water solubility, mechanical strength, low-temperature solubility, and production efficiency, a single-layer film is preferred.

[0056] In one embodiment of the present invention, the thickness of the water-soluble film is preferably 1 to 500 μm, more preferably 5 to 300 μm, even more preferably 10 to 150 μm, and even more preferably 20 to 110 μm. When the thickness of the water-soluble film is within the above range, the water-soluble film can have good water solubility, mechanical strength, and low-temperature solubility. The thickness of the water-soluble film can be determined, for example, using a thickness meter, and can be determined by the method described in the Examples below. Note that, when the water-soluble film is a multilayer film, the thickness of the water-soluble film refers to the thickness of one water-soluble film.

[0057] In one embodiment of the present invention, the water-soluble film of the present invention has excellent homogeneity without bleeding out of the plasticizer. The surface of the water-soluble film may be flat, or one or both sides of the water-soluble film may be textured, such as with an embossed or textured pattern, in order to prevent adhesion between products. Such textured processing can be performed using methods known in the art.

[0058] <Method for Producing Water-Soluble Film> The method for producing the water-soluble film of the present invention is not particularly limited, and the film can be produced by a method known in the art. For example, the water-soluble film can be produced by a method including: (1) a step of obtaining a coating liquid (coating agent) by stirring a polysaccharide, a plasticizer, a solvent, and optionally additives at a predetermined temperature, (2) a step of forming a coating film, and (3) a step of drying the coating film to form a dried coating film.

[0059] The solids concentration of the coating solution is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, and indicates the total mass of components other than the solvent (e.g., polysaccharides, plasticizers, additives, etc.) relative to the mass of the coating solution.

[0060] The temperature at which the polysaccharide, plasticizer, solvent, and, if necessary, additives are stirred is usually 15 to 100° C., preferably 30 to 98° C. The stirring method is not particularly limited, and stirring can be carried out by a conventionally known method.

[0061] The solvent is not particularly limited, but water, ethanol, methanol, 1-propanol, 2-propanol, etc. are preferred because they easily dissolve polysaccharides and are easy to dry afterwards.

[0062] The coating film can be formed, for example, by applying the coating liquid to a substrate, such as a polyolefin (e.g., polyethylene, polypropylene, etc.), a polyester (e.g., polyethylene terephthalate, etc.), a polyamide (e.g., nylon 6, nylon 66, etc.), a fluororesin (e.g., Teflon (registered trademark)), or a metal plate.

[0063] Examples of a method for applying the coating liquid to a substrate or the like include known methods such as spin coating, extrusion, bar coating, applicator, etc. Examples of coaters that can be used include blade coaters, bar coaters, roll coaters, gravure coaters, reverse gravure coaters, comma coaters, air knife coaters, reverse roll coaters, curtain coaters, spray coaters, size press coaters, and gate roll coaters.

[0064] The solvent is then removed by drying or the like to form a dried coating film. Drying methods include natural drying, ventilation drying, heat drying, and reduced pressure drying. Conventional dryers can be used, including steam heaters, gas heaters, infrared heaters, electric heaters, hot air heaters, microwaves, and cylinder dryers. The dried coating film is a water-soluble film.

[0065] Alternatively, the water-soluble film can be produced by a melt extrusion film-forming method in which a film-forming solution obtained using an extruder or the like is extruded through a T-die or the like to form a film, or by an inflation molding method.

[0066] After forming the water-soluble film on the substrate, the substrate can be removed to obtain the water-soluble film. Alternatively, the substrate may be used as is without being peeled off. When the substrate is not peeled off, a laminate including the substrate (support) and the water-soluble film can be obtained. When peeling off is required, it is preferable that a release agent is applied to the coating surface.

[0067] [Laminate] The present invention also encompasses a laminate comprising a support and a water-soluble film containing a polysaccharide and a plasticizer, the plasticizer content of which is 45 to 85% by mass relative to the mass of the solids content (components other than the solvent) of the coating agent. The support is preferably paper or film. In this embodiment, the laminate of the present invention has excellent mechanical strength because it includes, in addition to the polysaccharide, a water-soluble film containing the plasticizer in an amount of 45 to 85% by mass relative to the mass of the solids content of the coating agent.

[0068] In a laminate containing a water-soluble film and a support, examples of the support include paper or film (hereinafter also referred to as "support film").

[0069] When the support is paper, examples of the paper include kraft paper, one-side glossy kraft paper, one-side glossy bleached kraft paper, bleached kraft paper, unbleached kraft paper, fine paper, medium-quality paper, coated paper, one-side glossy paper, construction paper, glassine paper, graphene paper, parchment paper, synthetic paper, white cardboard, manila cardboard, milk carton base paper, cup base paper, ivory paper, silver paper, tissue paper, paperboard, rayon paper, wax paper, liner paper, etc. The basis weight of the paper is 20 to 400 g / m from the viewpoint of suitability for packaging applications. ２ It is preferable that the density is 25 to 150 g / m ２ From the viewpoint of suitability for use as a flexible packaging material, which will be described later, the basis weight of the paper is 30 to 100 g / m ２ More preferably, it is 40 to 70 g / m ２ The basis weight of the paper is measured in accordance with JIS P 8124:2011.

[0070] The above-mentioned paper can generally be produced by papermaking a stock containing pulp, fillers, and various auxiliaries. Examples of pulp include chemical pulps such as bleached hardwood kraft pulp (LBKP), bleached softwood kraft pulp (NBKP), unbleached hardwood kraft pulp (LUKP), unbleached softwood pulp (NUKP), and sulfite pulp; mechanical pulps such as stone-ground pulp and thermomechanical pulp; wood fibers such as deinked pulp and recycled paper pulp; and non-wood fibers obtained from kenaf, bamboo, hemp, etc. These can be used alone or in combination of two or more. Among these, chemical pulp from wood fibers and mechanical pulp are preferred, and chemical pulp is more preferred, from the viewpoints of reducing the possibility of foreign matter being mixed into the base paper and the possibility of discoloration over time when recycled after use, achieving good printing due to high brightness, and increasing the useful value (especially when used as a packaging material). Materials other than pulp can also be used as the secondary paper material as long as they do not impair the effects of the present invention. Examples of such materials include synthetic fibers such as rayon and nylon.

[0071] Examples of fillers include white carbon, talc, kaolin, clay, heavy calcium carbonate, light calcium carbonate, titanium oxide, zeolite, and synthetic resin fillers. These can be used alone or in combination of two or more. Examples of various auxiliaries include aluminum sulfate, various anionic, cationic, nonionic, or amphoteric retention aids, drainage aids, paper strength agents, and internal sizing agents, which can be used alone or in combination of two or more. Optionally, dyes, fluorescent whitening agents, pH adjusters, defoamers, pitch control agents, slime control agents, and additives consisting of two or more of these can also be used.

[0072] The method for producing paper is not particularly limited, and paper can be produced, for example, according to the following procedure. First, a stock is prepared by mixing a pulp slurry with a filler and various auxiliaries. The pulp slurry can be prepared by beating pulp in the presence of water. The pulp beating method and beating device are not particularly limited, and known beating methods and beating devices can be used. The pulp content in the stock is not particularly limited. For example, it is 60% by mass or more but less than 100% by mass relative to the total mass of the stock. Next, the prepared stock is made into paper by an acidic, neutral, or alkaline papermaking method using a known Fourdrinier former, on-top hybrid former, gap former, or the like. Multiple sheets of wet paper obtained after dewatering are stacked as necessary, and one or more sheets of wet paper are pressed and dried to obtain paper. In this case, if multiple wet paper sheets are not stacked, a single-layer paper is obtained, and if multiple wet paper sheets are stacked, a multi-layer paper is obtained. When multiple wet papers are stacked, adhesive may be applied to the surface of the wet paper (the surface on which other wet papers are stacked).

[0073] The paper surface may be treated with various chemicals. Examples of such chemicals include oxidized starch, hydroxyethyl etherified starch, enzyme-modified starch, polyacrylamide, polyvinyl alcohol, surface sizing agents, water-resistant agents, water-retention agents, thickeners, and lubricants. These may be used alone or in combination. Furthermore, these chemicals may be used in combination with pigments. Examples of pigments include inorganic pigments such as kaolin, clay, engineered kaolin, delaminated clay, ground calcium carbonate, light calcium carbonate, mica, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicates, colloidal silica, and satin white, as well as organic pigments such as solid, hollow, and core-shell pigments. These may be used alone or in combination.

[0074] The method for treating the surface of paper is not particularly limited, and can be performed using a known coating device such as a rod metering size press, a pond type size press, a gate roll coater, a spray coater, a blade coater, or a curtain coater.

[0075] When the support is a film, examples of the film include films (polyolefin films such as polyethylene, polypropylene, and norbornene-based polymers; polyvinyl alcohol films; polyethylene terephthalate (PET) films; poly(meth)acrylic acid ester films; cellulose ester films such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polylactic acid films; ethylene-vinyl alcohol copolymer films, etc.), sheets, etc.

[0076] The average thickness of the paper or film used as the support is, for example, about 1 to 500 μm, or about 10 to 300 μm.

[0077] In the laminate, the water-soluble film may be a single layer or multiple layers. When the water-soluble film is a multiple layer, the layers may be the same or different from each other. The laminate may also include any layer. The laminate may have one or more layers selected from the group consisting of a barrier layer, a protective layer, and a heat-sealing layer at any location in the layer structure. When the laminate has a protective layer and / or a heat-sealing layer, it is preferable that the layer is disposed as the outermost layer of the laminate.

[0078] The barrier layer may be a gas barrier layer or a water vapor barrier layer, and such barrier layers are known in the art. Examples of barrier layers include resin layers and metal foils, and more specific examples include resin layers containing polyvinyl alcohol, ethylene-vinyl alcohol copolymers, and / or polyvinylidene chloride, layers containing polysaccharides and plasticizers but not corresponding to the water-soluble film of the present invention, aluminum foils, aluminum vapor-deposited films (aluminum vapor-deposited on a substrate such as polyethylene, polypropylene, nylon, polyethylene terephthalate, or ethylene-vinyl alcohol copolymer), alumina vapor-deposited films (alumina vapor-deposited on a substrate such as polyethylene, polypropylene, nylon, polyethylene terephthalate, or ethylene-vinyl alcohol copolymer), and silica vapor-deposited films (silica vapor-deposited on a substrate such as polyethylene, polypropylene, nylon, polyethylene terephthalate, or ethylene-vinyl alcohol copolymer).

[0079] The protective layer is a layer that, by being present as at least a part of the outermost layer of the laminate, can reduce the influence of the surrounding environment on the components present below the protective layer (deterioration of the components). Therefore, the protective layer may have one or more functions selected from the group consisting of barrier properties, oil resistance, solvent resistance, heat resistance, abrasion resistance, impact resistance, weather resistance, and light resistance. By covering the entire outermost layer of the laminate with the protective layer, the above functions can be more effectively exhibited. Examples of the protective layer include a resin layer, a paper layer, and a metal foil.

[0080] The heat-sealing layer may be any layer known in the art. The heat-sealing layer is preferably a resin layer having heat-sealing properties. The heat-sealing layer preferably contains a water-dispersible resin and, optionally, additives. Examples of water-dispersible resins include polyolefin resins, styrene / acrylic copolymers, acrylic resins such as ethylene-(meth)acrylic acid copolymers, ethylene-vinyl acetate copolymers, polyester resins, rubber-based resins, urethane resins, polyamide resins, and combinations thereof. Examples of optional additives include lubricants such as paraffin wax, carnauba wax, and polyolefin waxes, pigments such as silica and kaolin, and combinations thereof. The heat-sealing layer may have barrier properties, in which case it can function as both a heat-sealing layer and a barrier layer. When the support is a film having barrier or protective properties, the film can also function as a barrier or protective layer.

[0081] Specific layer configurations of the laminate of the present invention, which includes a water-soluble film and a support and may have any layer (barrier layer, protective layer, heat seal layer), include, for example, the following configurations. Note that the following configurations are each described starting from the layer that will become the outermost layer (the layer on the opposite side to the layer that comes into contact with the contents) when used as, for example, a packaging material. Water-soluble film / paper or support film or metal foil, Gas barrier layer or water vapor barrier layer / water-soluble film / paper or support film or metal foil, Water vapor barrier layer / gas barrier layer / water-soluble film / paper or support film or metal foil, Gas barrier layer / water vapor barrier layer / water-soluble film / paper or support film or metal foil, Protective layer / water-soluble film / paper or support film or metal foil, Protective layer / gas barrier layer or water vapor barrier layer / water-soluble film / paper or support film or metal foil, Protective layer / water vapor barrier layer / gas barrier layer / water-soluble film / paper or support film or metal foil, Protective layer / gas barrier layer / water vapor barrier layer / water-soluble film / paper or support film or metal foil, Protective layer / water-soluble film / gas barrier layer or water vapor barrier layer / paper or support film or metal foil, Protective layer / water-soluble film / gas barrier layer / water vapor barrier layer / paper or support film or metal foil, Protective layer / water-soluble film / gas barrier layer / water vapor barrier layer / paper or support film or metal foil, Protective layer / gas barrier layer or water vapor barrier layer / water soluble film / paper or support film or metal foil / gas barrier layer or water vapor barrier layer, Protective layer / water vapor barrier layer / gas barrier layer / water soluble film / paper or support film or metal foil / gas barrier layer or water vapor barrier layer, Protective layer / gas barrier layer / water vapor barrier layer / water soluble film / paper or support film or metal foil / gas barrier layer or water vapor barrier layer, Protective layer / water vapor barrier layer / gas barrier layer / water soluble film / paper or support film or metal foil / gas barrier layer / water vapor barrier layer, Protective layer / water vapor barrier layer / gas barrier layer / water soluble film / paper or support film or metal foil / water vapor barrier layer / gas barrier layer, Protective layer / water vapor barrier layer / gas barrier layer / water soluble film / paper or support film or metal foil / water vapor barrier layer / gas barrier layer,protective layer / gas barrier layer / water vapor barrier layer / water-soluble film / paper or support film or metal foil / water vapor barrier layer / gas barrier layer; a layer configuration in which a heat seal layer is provided on the side opposite to the outermost layer in the above layer configuration; a layer configuration in which a heat seal layer is provided in place of a protective layer in the above layer configuration, for example, heat seal layer / water-soluble film / paper or support film or metal foil; a layer configuration in which an adhesive layer is provided in one or more locations between each layer in the above layer configuration, for example, heat seal layer / adhesive layer / water-soluble film / paper or support film or metal foil.

[0082] More specific examples of the layer structure include the following: Water-soluble film / paper, LLDPE / water-soluble film / paper, LLDPE / adhesive layer / water-soluble film / paper, LDPE / water-soluble film / paper, LDPE / adhesive layer / water-soluble film / paper, HDPE / water-soluble film / paper, HDPE / adhesive layer / water-soluble film / paper, CPE (non-oriented polyethylene) / water-soluble film / paper, CPE (non-oriented polyethylene) / adhesive layer / water-soluble film / paper, Polyethylene formed from polyethylene emulsion / water-soluble film / paper, Polyethylene formed from polyethylene emulsion / adhesive layer / water-soluble film / paper, Uniaxially oriented polyethylene / water-soluble film / paper, Uniaxially oriented polyethylene / adhesive layer / water-soluble film / paper, Biaxially oriented polyethylene / water-soluble film / paper, Biaxially oriented polyethylene / adhesive layer / water-soluble film / paper, Polypropylene / water-soluble film / paper, Polypropylene / adhesive layer / water-soluble film / paper, Uniaxially oriented polypropylene / water-soluble film / paper, Uniaxially oriented polypropylene / adhesive layer / water-soluble film / paper, Biaxially oriented polypropylene / water-soluble film / paper, Biaxially oriented polypropylene / adhesive layer / water-soluble film / paper, PLA / water-soluble film / paper, PLA / adhesive layer / water-soluble film / paper, PHA / water-soluble film / paper, PHA / adhesive layer / water-soluble film / paper, PHBH / water-soluble film / paper, PHBH / adhesive layer / water-soluble film / paper, PCL / water-soluble film / paper, PCL / adhesive layer / water-soluble film / paper, PBAT / water-soluble film / paper, PBAT / adhesive layer / water-soluble film / paper, PBS / water-soluble film / paper, PBS / adhesive layer / water-soluble film / paper.

[0083] <Method for Producing Laminate> The method for producing the laminate of the present invention is not particularly limited, and it can be produced by a method known in the art. The laminate of the present invention can be produced, for example, by a method including the same steps (1) to (3) as those described in the method for producing a water-soluble film above. The coating film in the laminate may be a single layer or multiple layers. By repeatedly coating a support with a coating liquid (coating agent) and removing the solvent, it is also possible to produce a multilayer laminate containing any layers in any stacking order.

[0084] The laminate of the present invention can also be produced by integrating a water-soluble film produced by, for example, a melt extrusion film-forming method, in which a film-forming solution (water-soluble film-forming material) obtained using an extruder or the like is extruded through a T-die or the like, or an inflation molding method, with a support. The integration method is not limited, and examples include a method of applying water to the surface of the water-soluble film and adhering the coated surface to the support, a method of integrating the water-soluble film and the support by thermocompression bonding, a method of integrating the water-soluble film and the support via a pressure-sensitive adhesive or adhesive, and an inflation method in which the water-soluble film-forming material and the support (film) material are co-extruded. When integrating by thermocompression bonding, the conditions may be appropriately selected depending on the type of polysaccharide contained in the water-soluble film and the type and amount of plasticizer, if any. For example, integration can be achieved by compression bonding at a temperature of 100 to 200°C and a pressure of 0.1 to 30 MPa for 0.1 to 10 seconds. When integrating via a pressure-sensitive adhesive or adhesive, such pressure-sensitive adhesives or adhesives are known in the art. The laminate of the present invention can also be produced as a multi-layer laminate by laminating a plurality of water-soluble films obtained by melt extrusion film formation, inflation molding or the like onto a support by a known method.

[0085] When the laminate contains a plurality of water-soluble films, it may contain a combination of a water-soluble film produced by coating and a water-soluble film produced by a melt extrusion film forming method, an inflation molding method, or the like.

[0086] [Pouch] The present invention encompasses a pouch comprising the water-soluble film of the present invention. Because the pouch of the present invention comprises the water-soluble film, it has high water solubility and excellent mechanical strength. Furthermore, in a preferred embodiment of the present invention, the pouch of the present invention can achieve both high low-temperature solubility and high mechanical strength.

[0087] In one embodiment of the present invention, the pouch of the present invention dissolves in water at 10°C preferably within 2000 seconds, more preferably within 1500 seconds, even more preferably within 1000 seconds, even more preferably within 700 seconds, particularly preferably within 600 seconds, and especially preferably within 500 seconds. There is no particular lower limit to the dissolution time, and shorter dissolution times are preferable. The solubility of the pouch in water at 10°C (low-temperature solubility) can be adjusted to below the upper limit by, for example, appropriately adjusting the type and / or amount of components contained in the water-soluble film constituting the pouch; the manufacturing conditions of the pouch (e.g., the amount of water applied, temperature, and pressure during water sealing, the temperature and pressure during heat sealing), etc. The solubility of the pouch in water at 10°C can be determined, for example, by the method described in the Examples below.

[0088] The film contained in the pouch may be a monolayer film or a multilayer film. When the pouch comprises (or is composed of) a monolayer film, the monolayer film is the water-soluble film. When the pouch comprises (or is composed of) a multilayer film, the multilayer film may be a laminate of a plurality of the water-soluble films, or may be a laminate of the water-soluble film and another water-soluble film other than the water-soluble film. From the viewpoint of improving the water solubility, mechanical strength, and low-temperature solubility of the pouch, it is preferable that the pouch be composed of a monolayer or multilayer water-soluble film, and further from the viewpoint of production efficiency, it is more preferable that the pouch be composed of a monolayer water-soluble film.

[0089] The pouch is not particularly limited as long as it is capable of packaging a substance (preferably a content), and may be sealed or partially open. The pouch may be, for example, a two-sided pouch, a three-sided pouch, a flat pouch, a standing pouch, a gusset pouch, a bottom gusset pouch, a twin pouch, a spout pouch, a side-seal pouch, a bottom-seal pouch, or the like, or may be in the form of a container, a cup, or the like. In one embodiment of the present invention, the pouch may be partially open, but is preferably sealed. In such an embodiment, the pouch more preferably contains a content and is sealed.

[0090] [Method for manufacturing pouch] The method for manufacturing the pouch of the present invention from a water-soluble film is not particularly limited, and it can be manufactured by a method known in the art. The pouch of the present invention can be manufactured, for example, by a method including a step of sealing one or more sheets of water-soluble film to form a bag. Furthermore, a pouch containing a content can be manufactured, for example, by a method including a step of pouring the content into a film formed into a bag shape and sealing the pouring opening.

[0091] Methods for sealing a water-soluble film include a method of sealing by applying water to the film surface and adhering the coated surface (also called water sealing), a method of sealing by thermocompression bonding (also called heat sealing), a method of sealing with an adhesive, etc. Heat sealing is preferred from the viewpoint of not requiring an additional agent, and water sealing is preferred from the viewpoint of not requiring heat.

[0092] In one embodiment of the present invention, the water-soluble film has high adhesive strength due to moisture, and therefore can be suitably used for water sealing. In another embodiment of the present invention, the water-soluble film has high water-sealing properties and low heat-sealing properties. The low heat-sealing properties make it difficult for the film to adhere to the roll when the film is produced by a roll-to-roll method, effectively preventing damage during production. Furthermore, the high water-sealing properties allow the produced water-soluble film to be simply and easily formed into a pouch using moisture.

[0093] [Uses of the Pouch] The pouch of the present invention has excellent water solubility and mechanical properties. Furthermore, in a preferred embodiment of the present invention, the pouch of the present invention has excellent low-temperature solubility, and is therefore particularly suitable for use in applications where it is dissolved in cold water. Therefore, the pouch of the present invention preferably contains at least one selected from the group consisting of a cleaning agent, a fabric softener, and a fragrance. There are no particular limitations on the physical properties of the contents, and they may be acidic, neutral, or alkaline. Furthermore, the form of the contents may be any of powder, block, gel, and liquid.

[0094] [Packaging Material] The water-soluble film of the present invention can be used as a packaging material comprising the water-soluble film. In this embodiment, the packaging material contains a polysaccharide and a plasticizer, and the content of the plasticizer is 45 to 85% by mass relative to the mass of the water-soluble film, resulting in high water solubility (preferably high low-temperature solubility) and excellent mechanical strength. The water-soluble film constituting the packaging material is preferably similar to the water-soluble film described above in the [Water-soluble Film] section, and preferably has similar solubility and mechanical strength. Furthermore, the packaging material preferably has similar solubility and mechanical strength to the pouch described above in the [Pouch] section.

[0095] The packaging material is a film used for packaging, and may include a thin film, a thick film, etc., and may be in the form of a container, a cup, a tube, a tray, a bottle, etc. In one embodiment of the present invention, the packaging material may contain a substance therein, similar to the above-mentioned pouch, preferably at least one selected from the group consisting of a cleaning agent, a fabric softener, and a fragrance.

[0096] The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0097] Approximately 20 μg of each polysaccharide used in the Examples and Comparative Examples was subjected to gel filtration HPLC under the following conditions to measure the weight-average molecular weight (Mw) and number-average molecular weight (Mn). The measurement solvent was selected from water or dimethyl sulfoxide (DMSO) in consideration of the solubility of each polysaccharide.

[0098] (Gel filtration HPLC conditions) Eluent: 0.1 M aqueous sodium nitrate Column: One TSK GEL α-M column used Column temperature: 40°C Flow rate: 1 mL / min Sample concentration: 0.1 w / v% Sample preparation: The sample was dissolved by stirring at 80°C for 2.5 hours, and then stirred at 90°C for an additional 30 minutes. Filtration filter: 0.45 μm PP filter (Whatman) Injection volume: 100 μL Standard: PEO / PEG Measurement time: 18 minutes Solution delivery section: GPC-101 (Shodex) Detector: RI or

[0099] Eluent: 5 mM Na nitrate / DMSO Column: One TSK GEL α-M column used Column temperature: 60°C Flow rate: 0.8 mL / min Sample concentration: 0.2 w / v% Sample preparation: The sample was dissolved by stirring at 60°C for 1 hour, followed by further stirring at 65°C for 2.5 hours. Filtration: 0.45 μm PP filter (Whatman) Injection volume: 100 μL Standard: PMMA-R, Y, G Measurement time: 18 minutes Solution delivery section: GPC-101 (Shodex) Detector: RI

[0100] Preparation of Water-Soluble Film Example 1 5 g of tamarind seed gum (weight average molecular weight 3,700 kDa, number average molecular weight 429 kDa; Glyloid (registered trademark) 6C, MP Gokyo Food & Chemical Co., Ltd.) as a polysaccharide was added to water and heated and stirred at 95°C for 2 hours to obtain a 4% aqueous solution. 5 g of glycerin as a plasticizer was added to this to prepare a coating liquid. The coating liquid was applied to a polyethylene terephthalate film using a bar coater and dried with hot air at 60°C for 1 hour. The resulting dried coating film was peeled off from the polyethylene terephthalate film substrate to obtain a film with a thickness of approximately 50 μm.

[0101] Examples 2 to 5 Films were obtained in the same manner as in Example 1, except that the amounts of tamarind seed gum and glycerin were changed to those shown in Table 1.

[0102] Examples 6 to 8 Films were obtained in the same manner as in Example 1, except that ethylene glycol was used as a plasticizer instead of glycerin, and each component was added in the amount shown in Table 1.

[0103] Examples 9 to 11 Films were obtained in the same manner as in Example 1, except that fructose was used as a plasticizer instead of glycerin, and each component was added in the amount shown in Table 1.

[0104] Examples 12 to 17 Films were obtained in the same manner as in Example 1, except that when adding tamarind seed gum as polysaccharide A, κ-carrageenan (weight-average molecular weight 826 kDa, number-average molecular weight 48 kDa; GENUGEL carrageenan type JPE-126, manufactured by Sansho Co., Ltd.) as polysaccharide B was added in addition to tamarind seed gum, and the components were added in the amounts shown in Table 1.

[0105] Example 18 A film was obtained in the same manner as in Example 1, except that when adding tamarind seed gum as polysaccharide A, xanthan gum (weight-average molecular weight 92 kDa, number-average molecular weight 16 kDa; Kimika Xanthan PH-R3EC, manufactured by Kimika Co., Ltd.) as polysaccharide B was added in addition to tamarind seed gum, and the components were added in the amounts shown in Table 1.

[0106] Example 19 A film was obtained in the same manner as in Example 1, except that when adding tamarind seed gum as polysaccharide A, guar gum (weight average molecular weight 93 kDa, number average molecular weight 17 kDa; SUPERGEL CSA200 / 50, manufactured by Sansho Co., Ltd.) as polysaccharide B was added in addition to tamarind seed gum, and the components were added in the amounts shown in Table 1.

[0107] Example 20 A film was obtained in the same manner as in Example 1, except that when adding tamarind seed gum as polysaccharide A, locust bean gum (weight-average molecular weight 96 kDa, number-average molecular weight 26 kDa; GENU (registered trademark) GUM type RL-200Z, manufactured by Sansho Co., Ltd.) was added as polysaccharide B in addition to tamarind seed gum, and the components were added in the amounts shown in Table 1.

[0108] Example 21 A film was obtained in the same manner as in Example 1, except that when tamarind seed gum was added as polysaccharide A, xanthan gum (weight average molecular weight 92 kDa, number average molecular weight 16 kDa; Kimika Xanthan PH-R3EC, manufactured by Kimika Co., Ltd.) as polysaccharide B-1 and guar gum (weight average molecular weight 93 kDa, number average molecular weight 17 kDa; SUPERGEL CSA200 / 50, manufactured by Sansho Co., Ltd.) as polysaccharide B-2 were added in addition to the tamarind seed gum, and the respective components were added in amounts shown in Table 1.

[0109] Example 22 A film was obtained in the same manner as in Example 1, except that when tamarind seed gum was added as polysaccharide A, xanthan gum (weight average molecular weight 92 kDa, number average molecular weight 16 kDa; Kimika Xanthan PH-R3EC, manufactured by Kimika Co., Ltd.) as polysaccharide B-1 and locust bean gum (weight average molecular weight 96 kDa, number average molecular weight 26 kDa; GENU (registered trademark), GUM type RL-200Z, manufactured by Sansho Co., Ltd.) as polysaccharide B-2 were added in addition to tamarind seed gum, and the respective components were added in amounts shown in Table 1.

[0110] Examples 23 to 26 Films were obtained in the same manner as in Example 1, except that κ-carrageenan (weight average molecular weight 826 kDa, number average molecular weight 48 kDa; GENUGEL carrageenan type JPE-126, manufactured by Sansho Co., Ltd.) was used as the polysaccharide instead of tamarind seed gum, and each component was added in the blending amount shown in Table 1.

[0111] Example 27 A film was obtained in the same manner as in Example 1, except that ι-carrageenan (weight average molecular weight 688 kDa, number average molecular weight 32 kDa; GENUTINE VCS-J, manufactured by Sansho Co., Ltd.) was used as a polysaccharide instead of tamarind seed gum, and each component was added in the blending amount shown in Table 1.

[0112] Example 28 A film was obtained in the same manner as in Example 1, except that tara gum (weight average molecular weight 352 kDa, number average molecular weight 118 kDa; Spinogum D, manufactured by Sansho Co., Ltd.) was used as the polysaccharide instead of tamarind seed gum, and each component was added in the amount shown in Table 1.

[0113] Example 29 A film was obtained in the same manner as in Example 1, except that guar gum (weight average molecular weight 93 kDa, number average molecular weight 17 kDa; SUPERGEL CSA200 / 50, manufactured by Sansho Co., Ltd.) was used as the polysaccharide instead of tamarind seed gum, and each component was added in the blending amount shown in Table 1.

[0114] Comparative Examples 1 and 2 Films were obtained in the same manner as in Example 1, except that the amounts of tamarind seed gum and glycerin were changed to those shown in Table 1.

[0115] Comparative Example 3 A film was obtained in the same manner as in Example 1, except that ethylene glycol was used as a plasticizer instead of glycerin, and each component was added in the amount shown in Table 1.

[0116] Comparative Examples 4 and 5 Films were obtained in the same manner as in Example 1, except that fructose was used as a plasticizer instead of glycerin, and each component was added in the amounts shown in Table 1.

[0117] Comparative Examples 6 to 8 Films were obtained in the same manner as in Example 1, except that κ-carrageenan (weight average molecular weight 826 kDa, number average molecular weight 48 kDa; GENUGEL carrageenan type JPE-126, manufactured by Sansho Co., Ltd.) was used as a polysaccharide instead of tamarind seed gum, sorbitol was used as a plasticizer instead of glycerin, and each component was added in the blending amount shown in Table 1.

[0118] Comparative Examples 9 to 11 Films were obtained in the same manner as in Example 1, except that t-carrageenan (weight average molecular weight 688 kDa, number average molecular weight 32 kDa; GENUTINE VCS-J, manufactured by Sansho Co., Ltd.) was used as a polysaccharide instead of tamarind seed gum, sorbitol was used as a plasticizer instead of glycerin, and each component was added in the amount shown in Table 1.

[0119] Comparative Examples 12 and 13 Films were obtained in the same manner as in Example 1, except that sodium alginate (weight-average molecular weight 104 kDa, number-average molecular weight 43 kDa; Kimica Algin I-8, Kimica Co., Ltd.) was used as a polysaccharide instead of tamarind seed gum, sorbitol was used as a plasticizer instead of glycerin, and each component was added in the amount shown in Table 1.

[0120] <Comparative Example 14> A film was obtained in the same manner as in Example 1, except that xanthan gum (weight average molecular weight 92 kDa, number average molecular weight 16 kDa; Kimika Xanthan PH-R3EC, manufactured by Kimika Co., Ltd.) was used as the polysaccharide instead of tamarind seed gum, and each component was added in the amount shown in Table 1.

[0121] The thickness of the water-soluble films prepared in the Examples and Comparative Examples was measured using a micrometer. The thickness was measured at five or more random points on the film, and the average value was taken as the film thickness. The thickness of each water-soluble film is shown in Table 1.

[0122]

[0123]

[0124] Evaluation of Water-Soluble Films <Water Solubility of Films> The films prepared in the examples were added to hot water at 90°C, and the films were dissolved by stirring for 5 minutes. The amount of solids that did not pass through a filter (21 µm) was measured and evaluated according to the following evaluation criteria. The mass of the added film was 0.1 parts by mass relative to 100 parts by mass of hot water at 90°C. The case where the amount of solids was 10% by mass or less was evaluated as A, and the case where the amount was more than 10% by mass was evaluated as B.

[0125] <Complete Dissolution Time in Cold Water (Low-Temperature Solubility)> The films prepared in the Examples and Comparative Examples were cut into 30 mm x 40 mm rectangles and sandwiched between slide mounts. A 600 ml glass beaker containing 500 ml of distilled water was placed in a separate thermostatic bath adjusted to 10°C, and the water was stirred at 400 rpm using a 5 cm rotor. After the distilled water in the beaker reached 10°C, the slide mount was immersed in the stirred water. The dissolution state of the film was visually observed, and the time (seconds) until the film was completely dissolved was measured and evaluated according to the following evaluation criteria. When a film with a thickness other than 50 μm was used, the time was converted to a value for a film thickness of 50 μm according to the following formula: Converted complete dissolution time (seconds) = [50 / film thickness (μm)] ２ x Sample complete dissolution time (seconds) A was given when the converted complete dissolution time was less than 600 seconds, B when it was 600 seconds or more but less than 1500 seconds, and C when it was 1500 seconds or more.

[0126] <Film Toughness> The films prepared in the Examples and Comparative Examples were stored for 7 days under an environment of 23°C and 50% RH, and then five test pieces with a width of 10 mm and a length of 120 mm were cut out. For each test piece, the maximum stress and breaking elongation were measured using an autograph (apparatus name: AG-5000B, Shimadzu Corporation) at a chuck distance of 70 mm and a pulling speed of 500 mm / min, and the average value was calculated. The value of the maximum stress x the breaking elongation was taken as the toughness of the film.

[0127] The evaluation results are shown in Table 2.

[0128]

[0129] As shown in Table 2, the films prepared in Examples 1 to 29 were water-soluble films, and it was confirmed that they had higher mechanical strength than those of Comparative Examples 1 to 14. Therefore, the water-soluble films of the present invention have excellent mechanical strength.

[0130] Preparation and Evaluation of Pouches Water was applied to the obtained water-soluble films, and the coated surfaces were bonded together to prepare pouches, and the film's sealing property, pouch compression test, and pouch water solubility were evaluated. The pouches prepared in the Examples and Comparative Examples had high compressive strength and excellent mechanical strength. Furthermore, since the pouches prepared in the Examples and Comparative Examples were made of water-soluble films, they reflected the physical properties of the water-soluble films and had excellent solubility at low temperatures. Furthermore, the water-soluble films that constitute the pouches had good sealing properties.

[0131] Preparation of Laminate Example 30 5 g of tamarind seed gum (Greate®) and 5 g of fructose were added to pure water to a total concentration of 25% by mass, and the mixture was heated and stirred at 90°C for 1 hour to obtain a dissolved coating solution. The resulting coating solution was cooled to 25°C and applied to a paper substrate (80 gsm bleached kraft paper) using a bar coater to a coating thickness of 9 μm after application (hereinafter sometimes simply referred to as "coating thickness"). The wet coating film on the substrate was dried in a hot air dryer at 80°C for 30 minutes. The same coating solution was applied again to a thickness of 22 μm, and the coating was dried in a hot air dryer at 80°C for 30 minutes to obtain a laminate comprising a substrate and a coating film.

[0132] Examples 31 to 34 and Comparative Examples 15 to 17 Laminates including a support and a coating film were obtained in the same manner as in Example 30, except that the materials and production conditions shown in Table 3 below were used.

[0133] <Coating Film Thickness> The coating film thickness was calculated using the following formulas: Coating film thickness [μm] = Concentration of coating liquid [mass %] × Thickness of coating liquid [μm] / 100 Concentration of coating liquid [mass %] = {(Mass of coating liquid [g] - Mass of water contained in coating liquid [g]) / Mass of coating liquid [g]} × 100 The total thickness of the coating film when coating was performed twice was calculated by substituting "thickness of coating liquid" in the above formulas with "total thickness of coating liquid."

[0134] <Flexibility> The laminate was folded with the coated side facing inward. A 2 kg rubber roller was rolled back and forth once from one end of the folded area (crease) to the other to create a crease. Toluene colored with food coloring was applied to a 10 cm area of ​​the crease on the coated side, and then the back side (uncoated side) was checked for bleed-through (small red spots or full coloring of the coated surface). If no bleed-through was found, the same procedure was repeated to check for bleed-through. The maximum number of folds without bleed-through was defined as flexibility [times], with a maximum value of 5. The higher this value, the better the mechanical strength of the coating layer and the less likely it is to crack when bent.

[0135] [Oxygen Transmission Rate (OTR)] The oxygen transmission rate (cc / m) of the laminate was measured using an oxygen transmission rate measuring device (OXYSENSE MODEL 8101e manufactured by Systech Illinois) under the following conditions: ２ The oxygen pressure was measured at 1.0 atm. The oxygen pressure was 1.0 atm. The oxygen supply humidity was 50% RH at 23°C, the carrier gas humidity was 50% RH at 23°C, the carrier gas flow rate was 10 mL / min, and the carrier gas pressure was 1.0 atm.

[0136] The evaluation results are shown in Table 3.

Claims

1. A water-soluble film comprising a polysaccharide and a plasticizer, the content of the plasticizer being 45 to 85% by mass relative to the mass of the water-soluble film.

2. The water-soluble film according to claim 1, wherein the plasticizer is at least one selected from the group consisting of polyhydric alcohols, hydroxy acids, monosaccharides, and disaccharides.

3. The water-soluble film according to claim 1, wherein the plasticizer is at least one selected from the group consisting of glycerin, diglycerin, sorbitol, alkylene glycol, polyalkylene glycol, trimethylolpropane, erythritol, 2-methyl-1,3-propanediol, lactic acid, glucose, fructose, maltose, and trehalose.

4. The water-soluble film according to claim 1, wherein the plasticizer is at least one selected from the group consisting of glycerin, ethylene glycol, sorbitol and fructose.

5. The water-soluble film according to claim 1, wherein the polysaccharide is at least one selected from the group consisting of carrageenan, alginic acid, guar gum, xanthan gum, pectin, hydroxyalkyl cellulose, alkyl cellulose, tamarind seed gum, agar, pullulan, locust bean gum, tara gum, and derivatives thereof.

6. The water-soluble film according to claim 1, wherein the polysaccharide is at least one selected from the group consisting of carrageenan, alginic acid, guar gum, xanthan gum, tamarind seed gum, locust bean gum, tara gum, and derivatives thereof.

7. The water-soluble film according to claim 1, wherein the content of the polysaccharide is 5 to 55% by mass based on the mass of the water-soluble film.

8. The water-soluble film according to claim 1, comprising two or more types of said polysaccharides.

9. The water-soluble film according to claim 1, which has a toughness of 700 or more.

10. The water-soluble film according to claim 1, which dissolves in water at 10° C. within 1,000 seconds.

11. The water-soluble film according to claim 1, which is a coating film formed from a coating agent containing a polysaccharide and a plasticizer.

12. A laminate comprising the water-soluble film according to claim 1 and a support, wherein the support is paper or film.

13. A pouch comprising the water-soluble film of claim 1.

14. The pouch of claim 13, further comprising at least one selected from the group consisting of cleaning agents, fabric softeners, and fragrances therein.

15. A coating agent comprising a polysaccharide and a plasticizer, the content of the plasticizer being 45 to 85% by mass relative to the mass of the solid content of the coating agent.

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