Water-soluble film for medicine packaging and method for producing the same

Abstract

To provide a water-soluble film for medicine packaging which is obtained by subjecting a PVA resin to inflation film formation, prevents generation of bleed-out and sticking of a plasticizer, and has such flexibility as to facilitate vacuum molding processing.SOLUTION: A water-soluble film for medicine packaging is an inflation film formation film blended with a non-modified polyvinyl alcohol resin (A), a plasticizer (B) and a hydrazine compound (C), wherein with respect to 100 pts.mass of the polyvinyl alcohol resin (A), 16 to 30 pts.mass of the plasticizer (B) is blended, the plasticizer (B) contains 8 to 20 pts.mass of glycerol (B1) and 8 to 20 pts.mass of diglycerol (B2), and a moisture content of the film is 1 to 5 mass%.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a water-soluble film for packaging medicines and a method for producing the same. [Background technology]

[0002] Some chemicals, such as detergents and pesticides, are handled in a chemical storage bag in which a predetermined amount of the chemical is stored in a chemical packaging bag made of a water-soluble film. By putting the chemical storage bag into a predetermined amount of water, the water-soluble film dissolves and the stored chemical is dispersed or dissolved in the water, so that the chemical can be adjusted to a predetermined concentration, and the chemical is easy to handle. Many of these chemical packaging bags are made of a water-soluble film whose main component is polyvinyl alcohol resin. A method of manufacturing a chemical packaging bag by vacuum forming a water-soluble film is known.

[0003] For the production of a water-soluble film mainly composed of polyvinyl alcohol resin, there is an inflation film-forming method in which polyvinyl alcohol resin is melted and extruded. Since the crystal melting point of polyvinyl alcohol resin is very close to the thermal decomposition temperature, the inflation film-forming method in which polyvinyl alcohol resin is melted and extruded, which is performed with ordinary thermoplastic resin, generates coloring and unpleasant odors due to thermal decomposition. As a method capable of inflation film-forming polyvinyl alcohol resin without generating such coloring and unpleasant odors, the following Patent Document 1 proposes a method for producing a polyvinyl alcohol molded body, which includes a step of obtaining a polyvinyl alcohol resin composition by mixing a polyvinyl alcohol resin having an average polymerization degree of 300 to 2500, 0.3 to 15 parts by weight of a hydrazine compound relative to 100 parts by weight of the polyvinyl alcohol resin, and 1 to 20 parts by weight of a plasticizer relative to 100 parts by weight of the polyvinyl alcohol resin, and a step of inflation molding.

[0004] According to this manufacturing method, polyvinyl alcohol resin can be blown into a film without coloring or unpleasant odor. However, when vacuum forming is performed using the water-soluble film mainly composed of the obtained polyvinyl alcohol resin, depending on the shape of the mold, vacuum forming is difficult, and the water-soluble film does not follow the mold, so there is a risk of the drug being poured over. Furthermore, according to the study by the present inventor, it was found that if the plasticizer is increased to improve the flexibility of the water-soluble film, the plasticizer may bleed out on the surface, causing stickiness, and the water-soluble film may adhere to the manufacturing machine during production. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4689000 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a water-soluble film for pharmaceutical packaging, which has flexibility that makes it easy to process in a vacuum, even if the water-soluble film is composed mainly of a polyvinyl alcohol resin obtained by inflation film formation, and which is free from plasticizer bleed-out or stickiness, and which is unlikely to come into close contact with manufacturing machinery, etc. during production, and a method for producing the same. [Means for solving the problem]

[0007] The water-soluble film for pharmaceutical packaging that achieves the above-mentioned object is an inflation film containing an unmodified polyvinyl alcohol resin (A), a plasticizer (B), and a hydrazine compound (C), characterized in that 16 to 30 parts by mass of the plasticizer (B) are contained per 100 parts by mass of the polyvinyl alcohol resin (A), the plasticizer (B) contains 8 to 20 parts by mass of glycerin (B1) and 8 to 20 parts by mass of diglycerin (B2), and the moisture content of the film is 1 to 5% by mass.

[0008] It is preferable that the plasticizer (B) is composed of the glycerin (B1) and the diglycerin (B2), since this allows both flexibility for easy vacuum forming and suppression of bleeding out of the plasticizer.

[0009] The polyvinyl alcohol resin (A) preferably has a degree of saponification of 80 to 96 mol % and an average degree of polymerization of 500 to 1200, since this can improve the solubility of the water-soluble film.

[0010] It is preferable that the blending ratio (B2 / B1) of the diglycerin (B2) to the glycerin (B1) is 0.4 to 2.5, since this can further prevent the water-soluble film from adhering to production machinery and the like during production.

[0011] The tensile modulus of the inflation film is preferably 250 MPa or less, since the film is flexible and has good processability.

[0012] A water-soluble film having a tensile modulus of elasticity of 250 MPa or less, such as the inflation film, has flexibility that allows easy vacuum forming and is suitable for vacuum forming.

[0013] The method for producing such a water-soluble film is a method for producing a water-soluble film by adding and mixing a plasticizer (B) containing glycerin (B1) and diglycerin (B2) and a hydrazine compound (C) to an unmodified polyvinyl alcohol resin (A) and forming the film by inflation film formation, and is characterized in that the amount of the glycerin (B1) is 8 to 20 parts by mass and the diglycerin (B2) is 8 to 20 parts by mass, and the amount of the plasticizer (B) is 16 to 30 parts by mass, per 100 parts by mass of the polyvinyl alcohol resin (A). Effect of the Invention

[0014] The water-soluble film for packaging medicinal products according to the present invention has flexibility that makes it easy to vacuum-form the medicinal product into a packaging bag, and does not bleed out plasticizer or become sticky, and the medicinal product can be easily formed into a packaging bag by vacuum forming. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The polyvinyl alcohol resin (hereinafter referred to as PVA resin) forming the water-soluble film for packaging medicines of the present invention (hereinafter simply referred to as the water-soluble film) is an unmodified PVA resin. As the unmodified PVA resin, those obtained by various known methods are used. For example, those obtained by saponifying fatty acid vinyl esters obtained by known polymerization methods such as bulk, solution, suspension, and emulsion of fatty acid vinyl esters by known methods are used. Here, examples of fatty acid vinyl esters used include vinyl acetate, vinyl formate, vinyl propionate, and vinyl butyrate. Vinyl acetate is particularly preferred from an industrial perspective. Two or more unmodified PVA resins thus obtained may be used in combination, or only one PVA resin may be used.

[0016] The saponification degree of the PVA resin is not particularly limited, and is usually 50 to 99.5 mol%, and can be appropriately selected depending on the use of the molded product, etc., but it is preferably 80 to 96 mol%, which makes it easy to adjust the solubility in water, and particularly preferably 80 to 93 mol%. Two or more PVA resins with the same or different saponification degrees may be used in combination, or only one PVA resin may be used. The saponification degree is measured in accordance with JIS K6726 (1994).

[0017] The average polymerization degree of the PVA resin is not particularly limited, but is usually 100 to 2000, and is preferably 500 to 1200, since it maintains the mechanical strength of the water-soluble film and is easy to form a film with a low melt viscosity when melted. If the average polymerization degree is less than 100, the mechanical strength of the water-soluble film tends to decrease, and if it exceeds 2000, the melt viscosity when melted tends to increase, making film formation difficult. Two or more PVA resins having the same or different average polymerization degrees may be used in combination, or only one PVA resin may be used.

[0018] The viscosity of a 4% by weight aqueous solution of the PVA resin at 20°C is not particularly limited, but is preferably 3.0 to 55 mPa·s, more preferably 5.0 to 35 mPa·s, and even more preferably 5 to 20 mPa·s. Two or more PVA resins having the same or different 4% by weight aqueous solution viscosities may be used in combination, or only one type of PVA resin may be used. The 4% by weight aqueous solution viscosity is measured in accordance with JIS K6726 (1994).

[0019] The water-soluble film mainly composed of unmodified PVA resin contains 16 to 30 parts by mass of plasticizer (B) relative to 100 parts by mass of PVA resin, and this plasticizer (B) contains 8 to 20 parts by mass of glycerin (B1) and 8 to 20 parts by mass of diglycerin (B2). By adjusting the blending amount of plasticizer (B) in the water-soluble film and the contents of glycerin (B1) and diglycerin (B2) contained in the plasticizer (B) within the above range, it is possible to achieve the effect of imparting flexibility to the water-soluble film for easy vacuum forming while preventing adhesion between water-soluble films. If the plasticizer (B) is less than 15 parts by mass, it is not possible to impart flexibility to the water-soluble film for easy vacuum forming, and if it exceeds 30 parts by mass, the mechanical strength of the water-soluble film tends to decrease, and inconveniences such as the water-soluble film being easily attached to the manufacturing machine during production may occur. If the amount of glycerin (B1) or diglycerin (B2) is less than 8 parts by mass, the water-soluble film cannot be given flexibility that facilitates vacuum forming processing, while if the amount of glycerin (B1) or diglycerin (B2) exceeds 20 parts by mass, problems arise such as the plasticizer bleeding out of the water-soluble film, causing stickiness, or the water-soluble film easily coming into contact with manufacturing machinery, etc. during production.

[0020] The plasticizer (B) used in the present invention is preferably composed of glycerin (B1) and diglycerin (B2) since it can be produced without complicating the production equipment, but the plasticizer (B) may contain other plasticizers than glycerin (B1) and diglycerin (B2) as long as the blending amounts of the plasticizer (B), glycerin (B1) and diglycerin (B2) are within the above range and the above effect is achieved. Examples of other plasticizers include polyethylene glycol, monoacetin, pentaerythritol, polyhydric alcohols such as 2,3 butanediol and 1,3 butanediol, amides such as dimethylacetamide, dimethyl sulfoxide, dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, diacetin, triacetin, etc.

[0021] The blending ratio of glycerin (B1) and diglycerin (B2) in the plasticizer (B) is preferably 0.4 to 2.5, more preferably 1.0 to 2.5, and even more preferably 1.6 to 2.5, since the water-soluble film can be wound without any adhesion to rolls or blades during production. By adjusting the blending ratio of glycerin (B1) and diglycerin (B2) within the above range, it is possible to prevent the water-soluble film from adhering while imparting flexibility that is easy to vacuum mold to the water-soluble film. If B2 / B1 is less than 0.4, it is difficult to achieve both flexibility that is easy to vacuum mold and the effect of preventing the water-soluble film from adhering, and if it exceeds 2.5, it is difficult to impart flexibility that is easy to vacuum mold.

[0022] The water-soluble film according to the present invention is obtained by inflation film formation, and therefore contains a hydrazine compound (C) in order to suppress coloration and unpleasant odors caused by thermal decomposition of the PVA resin when the PVA resin is heated and melted. As the hydrazine compound (C), various compounds can be used, including hydrazine, hydrazine hydrate, hydrazine monohydrate or salt, formhydrazide, acetohydrazide, propionic acid hydrazide, lauric acid hydrazide, methyl carbazate, ethyl carbazate, semicarbazide hydrochloride, stearic acid hydrazide, salicylic acid hydrazide, p-hydroxybenzoic acid hydrazide, benzoic acid hydrazide, etc. dihydrazide, 1-naphthoic acid hydrazide, carbohydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanediohydrazide, hexadecanediohydrazide, terephthalic acid dihydrazide, isophthalic acid dihydrazide, 2,6 -Naphthoic acid dihydrazide, 4,4'-bisbenzenedihydrazide, 1,4-cyclohexanedihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, iminodiacetic acid dihydrazide, N,N'-hexamethylenebissemicarbazide, itaconic acid dihydrazide, ethylenediaminetetraacetic acid tetrahydrazide, citric acid trihydrazide, 1,2,3-benzenetrihydrazide, 1,4,5,8-naphthoic acid tetrahydrazide Compounds having a hydrazino group or a hydrazido group in the molecule, such as azide, nitriloacetic acid trihydrazide, cyclohexanetricarboxylic acid trihydrazide, pyromellitic acid tetrahydrazide, and N-aminopolyacrylamide, and hydrazine derivatives obtained by reacting the above hydrazine compounds with ketone compounds, such as carbohydrazide diacetone hydrazone and adipic acid dihydrazide diacetone hydrazone, can be used. Among these hydrazine compounds, water-soluble hydrazine compounds are preferred from the viewpoint of compatibility with PVA-based resins, and adipic acid dihydrazide and carbodihydrazide are particularly preferred.

[0023] The amount of the hydrazine compound (C) is 0.1 to 5.0 parts by mass, more preferably 0.5 to 2.0 parts by mass, based on 100 parts by mass of the PVA resin (A). If the amount of the hydrazine compound (C) is less than 0.1 part by mass, the effect of preventing coloration and unpleasant odors caused by thermal decomposition during inflation film formation tends to be insufficient, while if it exceeds 5.0 parts by mass, the hydrazine compound (C) may bleed out, impairing the appearance of the water-soluble film.

[0024] Thus, the water-soluble film according to the present invention is obtained by inflation film formation in which PVA resin is melt-extruded, and does not require a process of dissolving PVA in water in the film manufacturing process. Therefore, the water-soluble film according to the present invention has a moisture content of 1 to 5% by mass. When the water-soluble film has a moisture content of 1 to 5% by mass, more preferably 1.5 to 4% by mass, it is possible to prevent the water-soluble film from adhering while imparting flexibility that facilitates vacuum forming processing to the water-soluble film. This is a low moisture content for a water-soluble film mainly composed of PVA resin. Such a water-soluble film with a low moisture content, in combination with the above-mentioned plasticizer, can prevent adhesion between water-soluble films. The moisture content of the water-soluble film is measured using a Karl Fischer moisture measuring device in accordance with JIS K0068 (2001).

[0025] The thickness of the water-soluble film of the present invention is preferably 20 to 120 μm, more preferably 25 to 90 μm, and even more preferably 30 to 50 μm. Furthermore, it is preferable that the tensile modulus of the water-soluble film is 250 MPa or less, since the water-soluble film is flexible. The processability, particularly the processability in vacuum forming, is good, and the water-soluble film is suitable for vacuum forming. The lower limit of the tensile modulus is about 10 MPa. The tensile modulus was measured in accordance with JIS K 7127 (1999).

[0026] The water-soluble film of the present invention may contain other additives, such as an antiblocking agent (AB agent) and a lubricant, within the range that does not impair the physical properties of the film. Examples of the AB agent include zeolite, talc, hydrotalcite, quartz, alumina, titanium dioxide, clay, bentonite, hydrophobized silica, and glass beads. The amount of the AB agent is preferably 0.1 to 8.0 parts by mass, particularly 2.0 to 6.0 parts by mass, relative to 100 parts by mass of the PVA resin (A), since both the blocking prevention effect and the film-forming property can be achieved. As the lubricant, preferred are aliphatic carboxylic acids such as caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid, and sodium or potassium salts of these aliphatic carboxylic acids, more preferably sodium salts of aliphatic carboxylic acids, and particularly preferably sodium stearate. The amount of the lubricant to be blended is preferably 0.1 to 2.0 parts by mass, more preferably 0.1 to 1.0 part by mass, relative to 100 parts by mass of the PVA resin (A), since this can prevent adhesion between the water-soluble films after molding and adhesion to a heat seal bar, etc., when the water-soluble film is heat-sealed, and can prevent the lubricant from bleeding out from the water-soluble film. The water-soluble film of the present invention may further contain, as necessary, conventional additives such as colorants, fragrances, extenders, antifoaming agents, release agents, UV absorbers, surfactants, antibacterial agents, etc. However, these may be added within a range that does not impair the physical properties of the water-soluble film of the present invention.

[0027] The method for blending the above-mentioned PVA resin (A), plasticizer (B), hydrazine compound (C), and other additives is not particularly limited. For example, the PVA resin (A), plasticizer (B), hydrazine compound (C), and other additives may be separately charged into a molding machine and mixed, or a dry blend of the PVA resin (A), plasticizer (B), hydrazine compound (C), and other additives may be previously charged into a molding machine and melt-mixed.

[0028] The water-soluble film according to the present invention is produced by an inflation film-forming method. As described above, this film-forming method is a method in which the unmodified PVA resin (A), the plasticizer (B) containing glycerin (B1) and diglycerin (B2), the hydrazine compound (C) and other additives are mixed in predetermined amounts, heated to 180 to 235°C and melted, and the melt is extruded into a tube shape from a circular die, cooled with gas outside the tube shape, air is blown into the tube shape, and the tube shape is expanded and taken up at high speed to obtain a tubular water-soluble film of a predetermined thickness. This tubular water-soluble film may be sandwiched between a pair of left and right rolls, folded into a sheet shape, and wound up as a tubular sheet, or the overlapping portion may be cut with a blade or the like to wind up a single sheet of water-soluble film.

[0029] The method for adjusting the moisture content of the water-soluble film obtained by such an inflation film-forming method is not particularly limited, but a small amount of water may be added when the mixture containing the PVA resin (A) and the plasticizer (B) is heated and melted, or the water-soluble film may be moistened in the process from extrusion of the melt to winding up the water-soluble film, or these methods may be combined. Also, the moisture content may be adjusted by drying the water-soluble film that has been previously moistened by these methods.

[0030] The water-soluble film thus obtained is flexible and suitable for forming into a drug packaging bag by vacuum forming. The method of this vacuum forming is not particularly limited, but for example, the water-soluble film is made to follow the inner wall surface of a cavity of a predetermined volume formed in a mold to form a water-soluble film with a depression of a predetermined volume, and then the depression is filled with a predetermined amount of drug, and then a predetermined surface of the water-soluble film located on the periphery of the cavity of the mold is overlapped with another water-soluble film, and the two are attached and sealed by heat sealing or the like to produce the drug packaging bag. In addition, the depth of the drug packaging bag can be appropriately adjusted within a range that can withstand deep drawing. The method of attaching two water-soluble films may be heat sealing, sealing by applying water, or bonding using an adhesive or the like. When bonding, pressure may be applied to the overlapping portion of the two water-soluble films to bond them. Since the water-soluble film of the present invention has excellent suitability for vacuum forming, even if the mold is a complex shape or a deep drawing mold, the water-soluble film can easily follow the mold and a good drug packaging bag can be formed, which is preferable. If the suitability for vacuum forming is poor, the water-soluble film will have difficulty conforming to the mold, and there is a risk of problems such as overflow of the drug when a predetermined amount of drug is filled. The chemicals to be filled in the recesses of the water-soluble film may be liquid detergent, powder detergent, agricultural chemicals, or the like. EXAMPLES

[0031] Examples of the present invention will be described in detail below, but the scope of the present invention is not limited to these examples.

[0032] (Unmodified polyvinyl alcohol resin (unmodified PVA resin)) The average polymerization degree, saponification degree, and 4% by mass aqueous solution viscosity at 20° C. (hereinafter referred to as 4% by mass viscosity) of each of the two types of PVA resins (A-1, A-2) used as the unmodified PVA resins are shown in Table 1 below.

[0033] [Table 1]

[0034] The additives listed below were added to the unmodified PVA resin shown in Table 1 in the amounts shown in Table 2. (Additives) Plasticizer (B): Glycerin (B1) Diglycerin (B2) Hydrazine Compound (ADY(C)): Adipic Dihydrazide Anti-blocking agent (AB agent): Zeolite (average particle size 3.0 μm) Lubricant: Sodium stearate

[0035] [Table 2]

[0036] The ingredients shown in Table 2 were mixed and blown into a film under the following conditions to obtain a tubular water-soluble film. (Inflation film forming conditions) Film making machine: Blown film making machine Die: Annular die for blown film production Cylinder temperature: 180~235℃ Die temperature: 185℃ Film winding speed: 15.0 m / min Blow ratio: 2.2 The tubular water-soluble film was sandwiched between a pair of rolls, folded into a sheet, humidified to adjust the moisture content of the film, and the overlapping portion was cut with a super steel blade FBC4009G (manufactured by Shinko Co., Ltd.: product name) to wind up a sheet of water-soluble film with a thickness of 40 μm. The moisture content of the resulting water-soluble film was measured by the method described below. The results are shown in Table 3. (Method of measuring moisture content) The moisture content of the resulting water-soluble film was measured using a Karl Fischer method moisture meter AQV-2200s (product name, manufactured by Hiranuma Sangyo Co., Ltd.).

[0037] The tensile modulus of each water-soluble film was measured by the method described below. Film test pieces were prepared with the machine direction (MD) during film production as the length direction. The degree of adhesion of each water-soluble film was also evaluated by the sensory test method described below. The measurement results of the tensile modulus of each water-soluble film and the results of the film adhesion sensory test are shown in Table 3 below. (Method for measuring tensile modulus) The measurement was performed using a tension tester AGS-1kN (manufactured by Shimadzu Corporation: product name) in accordance with JIS K 7127 (1999). The measurement conditions were as follows. Measurement environment: 23℃, 50% RH Film test piece: width 15mm x length 150mm Chuck distance: 100mm Tensile test speed: 300 mm / min (tensile direction: length direction of film) (Sensory test method for adhesion of water-soluble film) During inflation film production, a tubular water-soluble film is sandwiched between a pair of rolls on the left and right, folded into a sheet, and cut with a super steel blade FBC4009G (manufactured by Koshin Co., Ltd.: product name) to wind up a single sheet of water-soluble film. When the water-soluble film was able to be wound up without any adhesion to the rolls or blades, it was rated as film adhesion ◎, when there was little adhesion and it could be wound up, it was rated as film adhesion 〇, and when there was adhesion and it could not be wound up, it was rated as film adhesion ×.

[0038] Furthermore, each of the obtained water-soluble films was subjected to vacuum forming processing under the following conditions, and the suitability for vacuum forming processing was evaluated by the following sensory test method. The results are also shown in Table 3. (Vacuum forming processing conditions) Furthermore, each of the obtained water-soluble films was subjected to vacuum forming processing under the following conditions, and the suitability for vacuum forming processing was evaluated by the following sensory test method. The results are also shown in Table 3. (Vacuum forming processing test method) A cavity with a circular vacuum suction hole with a diameter of 1 mm at the bottom (opening area 2200 mm 2A mold having a box-shaped cavity with rounded corners and a depth of 25 mm was prepared, and refill ink (oil-based pigment) (Fujisey: product name) was applied in a circle with a diameter of 5 mm from the center to the vacuum suction holes at the four corners of the bottom. Next, a water-soluble film with a thickness of 40 μm formed by the above-mentioned method was set in a stretched state without wrinkles or sagging. The water-soluble film was heated at about 90° C. for 1 second, and the water-soluble film was made to conform to the cavity, forming a water-soluble film for the bottom with a depression. About 10 seconds after the start of vacuum drawing, the vacuum drawing was stopped, and the film was removed from the cavity. (Sensory test method for suitability for vacuum forming processing) The above-mentioned vacuum forming test was carried out, and the area of ​​the ink transferred to the water-soluble film was measured. The area of ​​the ink transferred to the water-soluble film relative to the area on which the ink was applied was calculated as the transfer rate. A transfer rate of 60% or more to the water-soluble film was rated as suitable for vacuum forming, and a transfer rate of 59% or less to the water-soluble film was rated as unsuitable for vacuum forming.

[0039] [Table 3]

[0040] As is clear from Tables 2 and 3, the tensile modulus of the water-soluble films No. 1 to No. 6 within the scope of the present invention was 250 MPa or less, the films did not adhere to each other, and they were suitable for vacuum forming. In particular, No. 1, No. 3, and No. 5 had B2 / B1 ratios of 1.8 to 1.9, which are within the range of 1.6 to 2.5, and the water-soluble films could be wound up without adhering to rolls or blades at all, and the film adhesion was particularly good. On the other hand, No. 7, in which only glycerin (B1) was blended as the plasticizer (B) at 30 parts by mass per 100 parts by mass of the unmodified PVA resin, * In the example, the water-soluble film is adhered to the surface and the blending amount is 18 parts by mass. * The water-soluble film of No. 9 lacked suitability for vacuum forming. In addition, the plasticizer (B) was only diglycerin (B2) in an amount of 18 parts by mass per 100 parts by mass of unmodified PVA resin. *The water-soluble film had a tensile modulus of 363 MPa, exceeding 250 MPa, making it hard and unsuitable for vacuum forming processing. [Industrial Applicability]

[0041] The water-soluble film for packaging medicines according to the present invention can be suitably used as a packaging bag for detergents (liquid and powder), agricultural chemicals, and the like.

Claims

1. An inflation film comprising an unmodified polyvinyl alcohol resin (A), a plasticizer (B), and a hydrazine compound (C), The water-soluble film for packaging medicines is characterized in that the plasticizer (B) is blended in an amount of 16 to 30 parts by mass per 100 parts by mass of the polyvinyl alcohol resin (A), the plasticizer (B) contains 8 to 20 parts by mass of glycerin (B1) and 8 to 20 parts by mass of diglycerin (B2), and the moisture content of the film is 1 to 5% by mass.

2. 2. The water-soluble film for packaging medicines according to claim 1, wherein the plasticizer (B) comprises the glycerin (B1) and the diglycerin (B2).

3. 2. The water-soluble film for packaging medicines according to claim 1, wherein the polyvinyl alcohol resin (A) has a degree of saponification of 80 to 96 mol % and an average degree of polymerization of 500 to 1,200.

4. 2. The water-soluble film for packaging medicines according to claim 1, wherein a blending ratio (B2 / B1) of said diglycerin (B2) to said glycerin (B1) is 0.4 to 2.

5.

5. 2. The water-soluble film for packaging medicines according to claim 1, wherein the tensile modulus of the inflation film is 250 MPa or less.

6. 6. The water-soluble film for packaging medicines according to claim 5, wherein the inflation film is for vacuum forming processing.

7. A method for producing a water-soluble film by adding and mixing a plasticizer (B) containing glycerin (B1) and diglycerin (B2) and a hydrazine compound (C) to an unmodified polyvinyl alcohol resin (A), and forming the resulting film by inflation film formation, comprising: The method for producing a water-soluble film for packaging medicines is characterized in that the polyvinyl alcohol resin (A) contains 8 to 20 parts by mass of the glycerin (B1) and 8 to 20 parts by mass of the diglycerin (B2), and the plasticizer (B) is added in an amount of 16 to 30 parts by mass relative to 100 parts by mass of the polyvinyl alcohol resin (A).

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