Water-soluble films and packaging

Abstract

To provide a water-soluble PVA film having good water sealability in addition to excellent water-solubility while keeping mechanical strength of a water-soluble PVA film, and a package using the same.SOLUTION: A water-soluble film of the present invention contains a polyvinyl alcohol-based resin. When a crystallinity index calculated using a diamond prism is Fd1 and a crystallinity index calculated using a germanium prism is Fg1, Fd1 and Fg1 satisfy 0.25≤Fd1≤0.65 and Fd1 / Fg1>1, when FT-IR measurement by an ATR method is performed to a first surface of the water-soluble film. Fd1 and Fg1 preferably satisfy Fd1 / Fg1≤1.5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a water-soluble film containing a water-soluble polyvinyl alcohol resin, which is suitable for use in packaging various medicines, and a package using the same. [Background technology]

[0002] Water-soluble films have been widely used in the past for a variety of applications, including packaging for various chemicals such as detergents and pesticides, as well as for packaging seeds and other items, and demand for these films is expanding due to their convenience.

[0003] As a water-soluble film for such applications, a PVA film containing polyvinyl alcohol (hereinafter sometimes referred to as PVA) as its main component is widely used. Various techniques have been proposed to improve the physical properties of this water-soluble film. For example, water-soluble films with improved water solubility have been proposed by blending various additives such as plasticizers or by using modified PVA (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-078166 Summary of the Invention [Problem to be solved by the invention]

[0005] The water-soluble film disclosed in Patent Document 1 has its crystallinity reduced and its water solubility increased by adjusting the amount of added plasticizer, etc., or by using modified PVA, etc. However, simply reducing the crystallinity of a water-soluble film reduces the mechanical strength of the film, which can cause pouches containing medicines, etc. to deform during storage or transportation, or in the worst case, break. Therefore, it is necessary for the water-soluble film to have a minimum necessary degree of crystallinity.

[0006] On the other hand, if the crystallinity is too high, in a continuous water sealing process carried out in the production of pouches and the like for packaging medicines, etc., in which water is applied to the surface of a film and then pressure-bonded to another film, if the line speed of the process is increased, the seal strength tends to decrease, and there is a possibility that productivity will deteriorate.

[0007] An object of the present invention is to provide a water-soluble PVA film that has excellent water solubility and good water-sealing properties while maintaining the mechanical strength of a water-soluble PVA film, and a package using the same. [Means for solving the problem]

[0008] As a result of extensive research, the present inventors have found that the above object can be achieved by adjusting the crystallinity index of a water-soluble film containing a polyvinyl alcohol-based resin in the vicinity of the film surface layer within a specific range. Based on this finding, the present inventors have conducted further research and have completed the present invention.

[0009] That is, the present invention relates to the following [1] to [9]. [1] A saponification degree of 94 mol% or less, a polymerization degree of 200 to 8000, and a modification amount of 5 mol% or less. Polyvinyl alcohol resin Plasticizer: 1 part by mass or more and 70 parts by mass or less A water-soluble film comprising: When the first surface of the water-soluble film is subjected to FT-IR measurement by the ATR method, the crystallinity index calculated using a diamond prism is Fd1, and the crystallinity index calculated using a germanium prism is Fg1, A water-soluble film, wherein Fd1 and Fg1 satisfy the following formulas: 0.25 ≦ Fd1 ≦ 0.65 (1) Fd1 / Fg1 > 1 (2) [2] The water-soluble film according to [1] above, wherein Fd1 and Fg1 satisfy the following formula: Fd1 / Fg1 ≦ 1.5 (3) [3] When the FT-IR measurement by the ATR method is performed on the second surface of the water-soluble film opposite to the first surface, the crystallinity index calculated using the diamond prism is Fd2 and the crystallinity index calculated using the germanium prism is Fg2, The water-soluble film according to the above [1] or [2], wherein Fd2 and Fg2 satisfy the following formula: 0.25≦ Fd2 ≦ 0.65 (4) Fd2 / Fg2 > 1 (5) [4] The water-soluble film according to [3] above, wherein Fd2 and Fg2 satisfy the following formula: Fd2 / Fg2 ≦ 1.5 (6) [5] The water-soluble film according to [3] or [4] above, wherein Fd1 and Fd2 satisfy the following formula: |Fd1-Fd2| ≦ 0.07 (7) [6] The water-soluble film according to any one of the above [3] to [5], wherein Fg1 and Fg2 satisfy the following formula: |Fg1-Fg2| ≦ 0.07 (8) [7] A package comprising a packaging material made of the water-soluble film according to any one of [1] to [6] above, and a drug contained in the packaging material. [8] The package described in [7] above, wherein the drug is a pesticide, a detergent or a disinfectant. [9] The package described in [7] or [8] above, wherein the drug is in liquid form. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a water-soluble PVA film that has excellent water solubility and good water-sealing properties while maintaining the mechanical strength of a water-soluble PVA film, and a package using the same. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an example of an infrared absorption spectrum of a film. [Figure 2] FIG. 1 is a diagram schematically illustrating the ATR method in infrared absorption spectrum measurement. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be specifically described below.

[0013] The water-soluble film of the present invention (hereinafter sometimes referred to as "PVA film") contains a polyvinyl alcohol-based resin. It is important that the crystallinity index calculated by analyzing one surface of the PVA film (also referred to as the "first surface") by FT-IR (Fourier transform infrared spectroscopy) satisfies the following formula: That is, when the crystallinity index Fd1 obtained by measuring the surface of the PVA film in FT-IR analysis using a diamond prism and the crystallinity index Fg1 obtained by measuring the surface of the PVA film in FT-IR analysis using a germanium prism are defined as Fd1 and Fg1, respectively, Fd1 satisfies the following formula: 0.25 ≦ Fd1 ≦ 0.65 (1) If Fd1 exceeds 0.65, the PVA film will not be sufficiently water-soluble. Fd1 is preferably 0.60 or less, more preferably 0.55 or less, even more preferably 0.5 or less, and particularly preferably 0.45 or less. If Fd1 is less than 0.25, the film may not have sufficient mechanical strength. Fd1 is preferably 0.3 or more, more preferably 0.35 or more, and even more preferably 0.4 or more. Additionally, in the present invention, it is important that Fd1 / Fg1 satisfies the following formula: Fd1 / Fg1 > 1 (2) If Fd1 / Fg1 is 1 or less, it is impossible to achieve both mechanical strength and good water sealing properties. Fd1 / Fg1 is preferably 1.04 or more, more preferably 1.06 or more, even more preferably 1.08 or more, and particularly preferably 1.10 or more.

[0014] The water-soluble film of the present invention contains a polyvinyl alcohol resin (PVA). When measuring the infrared absorption spectrum of a PVA molded product containing the film, it usually has a peak at 1140 cm -1An absorption peak is observed at this band. This peak is generally known as the crystallization band of PVA, and is one of the peaks derived from the stretching vibration of carbon bonds (C-C). It is known that this peak is observed intensified when the polymer molecular chains in the PVA molded product crystallize, causing the vibration phase to become aligned. The higher the crystallinity of the PVA molded product, the higher the relative intensity of this peak becomes. In the present invention, this 1140 cm -1 The intensity of the absorption peak at 1425 cm originates from the bending vibration of methylene (-CH2-) in the PVA main chain, which is said to be independent of the crystallinity. -1 The crystallinity index of the film itself can be obtained by calculating the intensity ratio of the absorption peak intensity observed in the film to that observed in the film. Specifically, 1140cm -1 and 1425 cm -1 The baseline of the infrared absorption spectrum at 1140 cm was drawn as shown in Figure 1. -1 and 1425 cm -1 The height of the peak top of each absorption peak is taken as the absorption peak intensity, and the height of the peak top of each absorption peak is taken as the absorption peak intensity. -1 The absorption peak intensity of 1425cm -1 The value obtained by dividing the absorption peak intensity by the absorption peak intensity is taken as the crystallinity index. It is well known that the crystallinity index value thus obtained is proportional to the crystallinity of the PVA film (for example, N.A. Peppas, Macromol. Chem., Vol. 178, p. 595 (1977), JP-A-6-138321). Since the crystallinity index value varies somewhat depending on the moisture absorption amount of the film, in the present invention, the film was stored in an environment of temperature: 24.0°C, relative humidity: 45.0% RH for 24 hours, and then FT-IR measurement was performed in this environment.

[0015] In this invention, FT-IR measurement is performed using the ATR method (attenuated total reflection spectroscopy). As shown in Figure 2, the ATR method is a type of reflection-type IR analysis in which a film is placed in close contact with an objective lens called an ATR prism, infrared light is irradiated obliquely onto the film from within the ATR prism, and the spectrum of the reflected light is measured. This method is characterized by obtaining a sharper spectrum with less noise than conventional reflection-type IR analysis. In this measurement method, infrared light is not only reflected by the film surface, but also by the infrared light that penetrates slightly from the prism side into the film, making it possible to obtain information about the film surface and surface layer. If the penetration depth of this infrared light is designated as d, its value can be expressed by the following equation: d= λ / 2Πn1× 1 / {sin 2 θ-(n2 / n1) 2} 0.5 (9) Here, n1 is the refractive index of the prism, n2 is the refractive index of the film, λ is the wavelength of the infrared light, and θ is the angle of incidence of the infrared light. As is clear from this formula, by using prisms with different refractive indices, it is possible to obtain infrared absorption spectra with reflections that penetrate to different depths.

[0016] In the present invention, diamond with n1 of 2.4 and germanium with n1 of 4.0 are used as prisms as shown in Figure 2. When these prisms are used, the incident angle is 45° and the wave number is 1140 cm -1 When calculating the penetration depth of infrared light into the film surface, the result is approximately 2 μm for diamond prisms and approximately 0.5 μm for germanium prisms, since the refractive index of PVA is 1.5. In other words, the crystallinity index when diamond prisms are used corresponds to the degree of crystallinity relatively deep inside the film, whereas the crystallinity index when germanium prisms are used corresponds to the degree of crystallinity near the surface of the film, in the very surface layer. In the above formula (2), Fd1 / Fg1 being greater than 1 indicates that the crystallinity of the very surface layer near the surface of the film is lower than the crystallinity of the relatively deep interior of the film. It is presumed that this fine control of the crystallinity of the interior and very surface layer of the film contributes to the development of good water sealing properties, which is one of the characteristics of the film of the present invention.

[0017] In the present invention, the upper limit of Fd1 / Fg1 is not necessarily limited, but from the viewpoint of achieving both mechanical strength and good water sealing properties of the film, it is preferable that the following formula (3) is satisfied. Fd1 / Fg1 ≦ 1.5 (3) If Fd1 / Fg1 exceeds 1.5, it may be impossible to achieve both mechanical strength and good water sealing properties. Fd1 / Fg1 is preferably 1.45 or less, more preferably 1.4 or less, even more preferably 1.35 or less, and particularly preferably 1.3 or less.

[0018] In the present invention, when the crystallinity index Fd2 of one surface (also referred to as the "first surface") of a PVA film and the opposing surface (also referred to as the "second surface") are determined by FT-IR analysis using a diamond prism, and the crystallinity index Fg2 is determined by FT-IR analysis using a germanium prism, it is preferable that Fd2 satisfies the following formula from the viewpoint of the water solubility of the film. 0.25≦ Fd2 ≦ 0.65 (4) When Fd2 is within the above range not only on one surface but also on the other surface opposite thereto, the water solubility of the PVA film can be maintained more optimally. If Fd2 exceeds 0.65, the PVA film may have insufficient water solubility. Fd2 is more preferably 0.60 or less, even more preferably 0.55 or less, particularly preferably 0.5 or less, and most preferably 0.45 or less. If Fd2 is less than 0.25, the film may not have sufficient mechanical strength. Fd2 is preferably 0.3 or more, more preferably 0.35 or more, and even more preferably 0.4 or more. Additionally, in the present invention, it is preferable that Fd2 / Fg2 satisfies the following formula: Fd2 / Fg2 > 1 (5) By having Fd2 / Fg2 in the above range not only on one surface but on both surfaces, it is possible to more optimally achieve both mechanical strength and good water sealing properties. Fd2 / Fg2 is more preferably 1.04 or more, even more preferably 1.06 or more, particularly preferably 1.08 or more, and most preferably 1.10 or more.

[0019] In the present invention, the upper limit of Fd2 / Fg2 is not necessarily limited, but from the viewpoint of achieving both mechanical strength and good water sealing properties of the film, it is preferable that the following formula (6) is satisfied. Fd2 / Fg2 ≦ 1.5 (6) If Fd2 / Fg2 exceeds 1.5, it may be difficult to achieve both mechanical strength and good water sealing properties. Fd2 / Fg2 is more preferably 1.45 or less, even more preferably 1.4 or less, particularly preferably 1.35 or less, and most preferably 1.3 or less.

[0020] In the present invention, the relationship between Fd1 and Fd2 is not necessarily limited, but from the viewpoint of being able to suppress the occurrence of curling of the film, it is preferable that the following formula (7) be satisfied. |Fd1-Fd2| ≦ 0.07 (7) This formula indicates that, in the present invention, it is preferable that the difference in crystallinity index between the surface layer, including the relatively deep interior portion, of one side of the film and that of the other side is not too large. If the difference between Fd1 and Fd2 exceeds 0.07, problems such as film curling tend to occur during secondary processing of the film. The difference between the crystallinity indexes Fd1 and Fd2, determined by measurements of FT-IR analysis using a diamond prism on one surface and the other surface of the film, is more preferably 0.06 or less, even more preferably 0.05 or less, and particularly preferably 0.04 or less.

[0021] In the present invention, the relationship between Fg1 and Fg2 is not necessarily limited, but from the viewpoint of being able to suppress the occurrence of curling of the film, it is preferable that the following formula (8) be satisfied. |Fg1-Fg2| ≦ 0.07 (8) This formula indicates that in the present invention, it is preferable that the difference in crystallinity index between the extreme surface layer near one film surface and that of the other film is not too large. If the difference in crystallinity index between Fg1 and Fg2 exceeds 0.07, problems such as film curling tend to occur during secondary processing of the film. The difference between the crystallinity indexes Fg1 and Fg2, determined by measurements of FT-IR analysis using a germanium prism on one surface and the other surface of the film, is more preferably 0.06 or less, even more preferably 0.05 or less, and particularly preferably 0.04 or less.

[0022] In the present invention, it is important to control the crystallinity index of the water-soluble PVA film within the above-mentioned ranges at the outermost surface layer and inward in the thickness direction. Since the crystalline structure of a PVA film is affected by various factors in the film composition and production process, methods for controlling the crystallinity index include, for example, adjusting the type of polyvinyl alcohol resin (such as the degree of saponification, the amount of modification, and the blend ratio of unmodified PVA / modified PVA), adjusting the amount of plasticizer added, adjusting film production conditions (such as the surface temperature of the roll support and heat treatment conditions), or a combination of these.

[0023] <Polyvinyl alcohol resin> The water-soluble film of the present invention contains a polyvinyl alcohol resin (PVA). As the PVA, a polymer produced by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester monomer can be used. Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate, etc. Among these, vinyl acetate is preferred as the vinyl ester monomer.

[0024] The vinyl ester polymer is preferably a polymer obtained using only one or more vinyl ester monomers as the monomer, more preferably a polymer obtained using only one vinyl ester monomer as the monomer, and may also be a copolymer of one or more vinyl ester monomers with other monomers copolymerizable therewith.

[0025] Examples of other monomers include ethylene; olefins having 3 to 30 carbon atoms such as propylene, 1-butene, and isobutene; acrylic acid or its salts; acrylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadecyl acrylate; methacrylic acid or its salts; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, methacrylic acid, and the like. Methacrylic acid esters such as i-propyl acrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate; acrylamides such as acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetone acrylamide, acrylamidopropanesulfonic acid or a salt thereof, acrylamidopropyldimethylamine or a salt thereof, and N-methylolacrylamide or a derivative thereof; methacrylamide derivatives such as methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid or a salt thereof, methacrylamidepropyldimethylamine or a salt thereof, and N-methylolmethacrylamide or a derivative thereof; N-vinylamides such as N-vinylformamide, N-vinylacetamide, and N-vinylpyrrolidone; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, and stearyl vinyl ether; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; maleic acid or a salt, ester, or acid anhydride thereof; itaconic acid or a salt, ester, or acid anhydride thereof; vinylsilyl compounds such as vinyltrimethoxysilane; and isopropenyl acetate. The vinyl ester polymer may have structural units derived from one or more of these other monomers.

[0026] Generally, the crystallization of PVA tends to proceed more slowly as the proportion of structural units derived from other monomers in the vinyl ester polymer increases. Therefore, the crystallinity index of the PVA film can be adjusted by copolymerizing these other monomers appropriately. The proportion of structural units derived from other monomers in the vinyl ester polymer is not necessarily limited, but is preferably 15 mol % or less, and more preferably 5 mol % or less, based on the number of moles of all structural units constituting the vinyl ester polymer.

[0027] Generally, the crystallization of PVA tends to proceed more slowly as the degree of polymerization increases. Therefore, in the present invention, the degree of polymerization of PVA is not particularly limited, but is preferably within the following range. That is, the lower limit of the degree of polymerization is preferably 200 or more, more preferably 300 or more, and even more preferably 500 or more, from the viewpoints of suppressing excessive crystallization and ensuring sufficient mechanical strength of the PVA film. On the other hand, the upper limit of the degree of polymerization is preferably 8,000 or less, more preferably 5,000 or less, and even more preferably 3,000 or less, from the viewpoints of promoting appropriate crystallization and improving the productivity of PVA and PVA film.

[0028] Here, the degree of polymerization means the average degree of polymerization measured in accordance with the description of JIS K 6726-1994. In this specification, the degree of polymerization is calculated from the intrinsic viscosity [η] (unit: deciliter / g) measured in water at 30°C after resaponifying and purifying PVA, using the following formula (10): Degree of polymerization Po = ([η]×10 4 / 8.29) (1 / 0.62) (10)

[0029] Generally, the crystallization of PVA tends to proceed more easily as the saponification degree increases. Therefore, although the saponification degree of PVA is not necessarily limited in the present invention, it is preferably 64 to 95 mol%. By adjusting the saponification degree of PVA within this range, the crystallization of the PVA film can be moderately advanced, making it easier to achieve both good water solubility and suppressed adhesion between films. The lower limit of the saponification degree is more preferably 70 mol% or more, and even more preferably 75 mol% or more. Meanwhile, the upper limit of the saponification degree is more preferably 94 mol% or less, and even more preferably 93 mol% or less.

[0030] Here, the degree of saponification of PVA refers to the ratio (mol %) of the number of moles of vinyl alcohol units to the total number of moles of structural units (typically vinyl ester monomer units) that can be converted into vinyl alcohol units by saponification and vinyl alcohol units. The degree of saponification of PVA can be measured in accordance with the description of JIS K 6726-1994.

[0031] The PVA film may contain one type of PVA alone, or may contain two or more types of PVA that differ from each other in degree of polymerization, degree of saponification, degree of modification, and the like.

[0032] The upper limit of the PVA content in the PVA film is preferably 100% by mass or less, while the lower limit of the PVA content is preferably 50% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more.

[0033] <Plasticizer> PVA films that do not contain plasticizers are generally hard films, which can easily cause problems such as breakage during film formation and secondary processing. Furthermore, the feel of the film is also poor, so it is preferable for PVA films to contain a plasticizer. The inclusion of a plasticizer can impart flexibility equivalent to that of other plastic films.

[0034] Examples of plasticizers include polyhydric alcohols such as ethylene glycol, glycerin, diglycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane, and sorbitol. These plasticizers may be used alone or in combination of two or more. Among these, ethylene glycol or glycerin is preferred as the plasticizer, and glycerin is more preferred, because it is less likely to bleed out onto the surface of the PVA film.

[0035] In general, adding an appropriate amount of plasticizer to PVA promotes crystallization. This is thought to be because the addition of plasticizer increases the mobility of PVA molecules, making them more likely to adopt an energetically stable crystalline or constrained amorphous structure. On the other hand, PVA films containing excessive amounts of plasticizer tend to inhibit the progression of crystallization. This is thought to be because the amount of plasticizer interacting with the hydroxyl groups of the PVA molecules increases, weakening the interactions between PVA molecules. The lower limit of the plasticizer content in the PVA film is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of PVA. Meanwhile, the upper limit of the plasticizer content is preferably 70 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less, per 100 parts by mass of PVA. When the plasticizer content is within the above range, it becomes easy to control the crystallinity index of the PVA film, and in addition, it is possible to sufficiently obtain the effect of improving mechanical properties such as impact strength. Furthermore, it is possible to suitably prevent or suppress the PVA film from becoming too flexible, which reduces handleability, or problems such as bleeding out to the surface.

[0036] <Starch / Water-soluble polymer> The PVA film may contain a water-soluble polymer other than starch and / or PVA, which can impart mechanical strength to the PVA film, improve the moisture resistance of the PVA film during handling, or adjust the rate at which the PVA film softens due to water absorption during dissolution.

[0037] Examples of starches include natural starches such as corn starch, potato starch, sweet potato starch, wheat starch, rice starch, tapioca starch, and sago starch; and processed starches that have been subjected to etherification, esterification, oxidation, etc., with processed starches being particularly preferred.

[0038] The starch content in the PVA film is preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, relative to 100 parts by mass of PVA. When the starch content is within the above range, deterioration of the processability of the PVA film can be prevented or suppressed.

[0039] Examples of water-soluble polymers other than PVA include dextrin, gelatin, glue, casein, shellac, gum arabic, polyacrylic acid amide, sodium polyacrylate, polyvinyl methyl ether, a copolymer of methyl vinyl ether and maleic anhydride, a copolymer of vinyl acetate and itaconic acid, polyvinylpyrrolidone, cellulose, acetyl cellulose, acetyl butyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and sodium alginate.

[0040] The content of the water-soluble polymer other than PVA in the PVA film is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, relative to 100 parts by mass of PVA. When the content of the water-soluble polymer other than PVA is within the above range, the water solubility of the PVA film can be sufficiently increased.

[0041] <Surfactant> The PVA film preferably contains a surfactant, which can improve the handling properties of the PVA film and the peelability of the PVA film from the film-forming device during production. The surfactant is not particularly limited, and for example, anionic surfactants, nonionic surfactants, etc. can be used.

[0042] Examples of anionic surfactants include carboxylic acid surfactants such as potassium laurate; sulfate ester surfactants such as octyl sulfate; and sulfonic acid surfactants such as dodecylbenzenesulfonate.

[0043] Examples of nonionic surfactants include alkyl ether surfactants such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether; alkyl phenyl ether surfactants such as polyoxyethylene octylphenyl ether; alkyl ester surfactants such as polyoxyethylene laurate; alkyl amine surfactants such as polyoxyethylene lauryl amino ether; alkyl amide surfactants such as polyoxyethylene lauric acid amide; polypropylene glycol ether surfactants such as polyoxyethylene polyoxypropylene ether; alkanolamide surfactants such as lauric acid diethanolamide and oleic acid diethanolamide; and allyl phenyl ether surfactants such as polyoxyalkylene allyl phenyl ether.

[0044] Such surfactants may be used alone or in combination of two or more. As the surfactant, nonionic surfactants are preferred because they are excellent in reducing surface abnormalities during the production of a PVA film, alkanolamide surfactants are more preferred, and dialkanolamides (e.g., diethanolamides) of aliphatic carboxylic acids (e.g., saturated or unsaturated aliphatic carboxylic acids having 8 to 30 carbon atoms) are even more preferred.

[0045] The lower limit of the surfactant content in the PVA film is preferably 0.01 parts by mass or more, more preferably 0.02 parts by mass or more, and even more preferably 0.05 parts by mass or more, per 100 parts by mass of PVA. Meanwhile, the upper limit of the surfactant content is preferably 10 parts by mass or less, more preferably 1 part by mass or less, even more preferably 0.5 parts by mass or less, and particularly preferably 0.3 parts by mass or less, per 100 parts by mass of PVA. When the surfactant content is within the above range, the PVA film is easily releasable from the film-forming device during production, and problems such as adhesion between PVA films (hereinafter sometimes referred to as "blocking") are less likely to occur. Furthermore, problems such as surfactant bleeding out onto the surface of the PVA film and deterioration of the appearance of the PVA film due to surfactant aggregation are less likely to occur.

[0046] <Other ingredients> The PVA film may contain components such as water, antioxidants, ultraviolet absorbers, lubricants, crosslinking agents, colorants, fillers, preservatives, antifungal agents, and other polymer compounds in addition to plasticizers, starch, water-soluble polymers other than PVA, and surfactants, as long as the effects of the present invention are not impaired. The proportion of the total mass of PVA, plasticizer, starch, water-soluble polymer other than PVA, and surfactant to the total mass of the PVA film is preferably 60 to 100 mass%, more preferably 80 to 100 mass%, and even more preferably 90 to 100 mass%.

[0047] <Water-soluble film> The PVA film of the present invention is not particularly limited in the time required for complete dissolution when immersed in deionized water at 10°C, but the following range is preferred. That is, the upper limit of the complete dissolution time is preferably 150 seconds or less, more preferably 90 seconds or less, even more preferably 60 seconds or less, and particularly preferably 45 seconds or less. PVA films having an upper limit of the complete dissolution time within the above range dissolve relatively quickly, and are therefore suitable for use as packaging (packaging) films for pharmaceuticals and the like. On the other hand, the lower limit of the complete dissolution time is preferably 5 seconds or more, more preferably 10 seconds or more, even more preferably 15 seconds or more, and particularly preferably 20 seconds or more. PVA films having a lower limit of the complete dissolution time within the above range are less likely to suffer from problems such as blocking between PVA film layers due to absorption of moisture in the atmosphere and a decrease in mechanical strength.

[0048] The time required for complete dissolution of a PVA film when it is immersed in deionized water at 10° C. can be measured as follows. <1> The PVA film is placed in a thermo-hygrostat adjusted to 20°C and 65% RH for 16 hours or more to condition the humidity. <2> A rectangular sample measuring 40 mm long and 35 mm wide is cut out from the conditioned PVA film, and then sandwiched and fixed between two 50 mm x 50 mm plastic plates with rectangular windows (holes) measuring 35 mm long and 23 mm wide so that the length of the sample is parallel to the length of the windows and the sample is positioned approximately in the center of the width of the windows. <3> 300 mL of deionized water is placed in a 500 mL beaker, and the water temperature is adjusted to 10°C while stirring at 280 rpm using a magnetic stirrer equipped with a 3 cm long bar. <4> the above <2> The sample fixed to the plastic plate in step 1 is immersed in deionized water in a beaker, taking care not to let it come into contact with the bar of the rotating magnetic stirrer. <5> The time (seconds) from when the sample pieces were immersed in deionized water until they completely disappeared was measured.

[0049] The thickness of the PVA film is not particularly limited, but is preferably in the following range. That is, the upper limit of the thickness is preferably 200 μm or less, more preferably 150 μm or less, even more preferably 100 μm or less, and particularly preferably 50 μm or less. On the other hand, the lower limit of the thickness is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and particularly preferably 20 μm or more. A thickness in the above range is not too large, so that deterioration of the secondary processability of the PVA film can be suitably prevented, while not being too small, so that sufficient mechanical strength can be ensured for the PVA film. The thickness of the PVA film can be determined by measuring the thickness at any 10 points (for example, any 10 points on a line drawn in the length direction of the PVA film) and averaging the measured values.

[0050] <Method of manufacturing water-soluble film> The method for producing the water-soluble film (PVA film) of the present invention is not particularly limited, and any of the following methods can be used, for example. Examples of such methods include a method in which a film-forming solution obtained by adding a solvent, additives, etc. to PVA to homogenize it is used for film formation, such as a casting method, a wet film-forming method (discharging into a poor solvent), a dry-wet film-forming method, a gel film-forming method (a method in which the film-forming solution is cooled to gel, and then the solvent is extracted and removed), or a combination of these methods; and a melt extrusion method or inflation molding 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. Among these, the casting method and the melt extrusion method are preferred as methods for producing PVA films. These methods allow for the production of homogeneous PVA films with good productivity. Hereinafter, the case where a PVA film is produced by a casting film-forming method or a melt extrusion film-forming method will be described.

[0051] When a PVA film is produced by a casting method or a melt extrusion method, a film-forming solution containing PVA, a solvent, and, if necessary, an additive such as a plasticizer is first prepared. When the film-forming solution contains additives, the ratio of the additives to the PVA in the film-forming solution is substantially equal to the ratio of the additives to the PVA in the PVA film described above. Next, the membrane-forming solution is poured (supplied) in the form of a film onto a rotating support such as a metal roll or a metal belt. This forms a liquid coating of the membrane-forming solution on the support. The liquid coating is heated on the support to remove the solvent, solidifying it into a film. Examples of methods for heating the liquid coating include a method of raising the temperature of the support itself using a heat medium, or a method of blowing hot air onto the surface of the liquid coating opposite the surface that is in contact with the support. The solidified long film (PVA film) is peeled off from the support, dried as needed using a drying roll, a drying oven, or the like, further heat-treated as needed, and wound up into a roll.

[0052] During the drying process (solvent removal process) of the liquid coating cast onto the substrate, and the subsequent drying process of the PVA film, PVA crystallizes while being heated. The rate of crystallization is affected by the proportion of structural units derived from other monomers, the degree of polymerization, the degree of saponification, and the plasticizer content, as well as the moisture content of the PVA, temperature, and draw (tensile elongation in the flow direction). Draw is thought to be the result of oriented crystallization caused by tension on the PVA molecular chains. Typically, PVA film drying proceeds by volatilization of volatiles from the open film surface that is not in contact with the support or drying rolls. Therefore, during the drying process, a concentration distribution of volatiles such as water occurs across the thickness of the film, which results in a distribution of the crystallinity index across the thickness depending on the temperature and drawing conditions at each time. This distribution of the crystallinity index can be adjusted by the support temperature, contact time with the support, hot air temperature and amount, drying roll and drying oven temperature, etc. Therefore, by appropriately adjusting the above factors, the water-soluble PVA film of the present invention can be obtained.

[0053] The volatile content of the film-forming solution (the concentration of volatile components such as solvents removed by volatilization or evaporation during film formation) is preferably 50 to 90% by mass, more preferably 55 to 80% by mass. When the volatile content is within this range, the viscosity of the film-forming solution can be adjusted to a suitable range, improving the film-forming properties of the PVA film (liquid coating) and facilitating the production of a PVA film with a uniform thickness. Furthermore, because the volatile content of the film-forming solution is appropriate, PVA crystallization on the support proceeds appropriately, making it easier to adjust the crystallinity index and its distribution.

[0054] Here, the "volatile content of the film-forming solution" in this specification refers to a value calculated by the following formula. Volatile content of film-forming solution (mass%) ={(Wa-Wb) / Wa}×100 (11) In the formula, Wa represents the mass (g) of the membrane-forming solution, and Wb represents the mass (g) of the membrane-forming solution Wa (g) after drying it in an electric dryer at 105°C for 16 hours.

[0055] The method for preparing the film-forming solution is not particularly limited, and examples thereof include a method in which PVA and additives such as a plasticizer and a surfactant are dissolved in a dissolution tank or the like, and a method in which water-containing PVA is melt-kneaded together with additives such as a plasticizer and a surfactant using a single-screw or twin-screw extruder.

[0056] The film-forming solution typically passes through the die lip of a die such as a T-die and is cast in the form of a film onto a support such as a metal roll or belt. As mentioned above, on the support, the solvent evaporates from the surface of the cast film that is not in contact with the support (hereinafter sometimes referred to as the "free surface"), while it does not substantially evaporate from the surface that is in contact with the support (hereinafter sometimes referred to as the "touch surface"). This results in a distribution of solvent concentration that is low on the free surface side and high on the touch surface side along the thickness of the film. Therefore, solidification of the PVA proceeds first from the free surface side. As the PVA solidifies, it also crystallizes. PVA crystallization is difficult if the solvent concentration is too high or too low. While this depends on the primary structure of the PVA molecule, it is most likely to occur when the volatile content of the spun PVA film is in the range of 20-60% by mass. The crystallization rate increases with increasing temperature, but the solvent evaporation rate also increases with increasing temperature. Therefore, to efficiently promote crystallization deep into the film while suppressing crystallization in the very surface of the PVA film, it is important to control the temperature of the support, the contact time with the support, the ambient temperature near the free surface, and the vapor pressure of the solvent. Since the PVA film of the present invention has a low degree of crystallinity in the very surface layer compared to the degree of crystallinity in the relatively deeper portions of the film, it is only necessary to select conditions that suppress crystallization in the surface layer while promoting crystallization in the relatively deeper portions of the film.For example, in the early stages of drying when the volatile content in the surface layer is decreasing, rapid drying conditions such as increasing the drying temperature can be adopted to reduce the moisture content in the surface layer before crystallization progresses, and from the middle to late stages of drying when crystallization progresses in the relatively deeper portions of the film, conditions can be adopted to promote crystallization by drying slowly at a relatively low temperature.

[0057] The surface temperature of the support onto which the film-forming solution is poured is preferably 70 to 130° C., more preferably 80 to 120° C., and even more preferably 85 to 115° C. When the surface temperature is within the above range, drying of the liquid coating and crystallization of the outermost surface layer of the film proceed at an appropriate speed, making it easier to obtain the PVA film of the present invention.

[0058] While the liquid coating is heated on the support, hot air may be blown uniformly over the entire area of ​​the non-contact side of the liquid coating at a speed of 1 to 10 m / sec. The temperature of the hot air blown onto the non-contact side is preferably 60 to 160°C, more preferably 70 to 140°C. The humidity of the hot air is preferably in the range of 20 to 90% RH, more preferably 30 to 80% RH, and even more preferably 40 to 80% RH. When the temperature and humidity of the hot air blown onto the non-contact side are within the above ranges, the PVA film of the present invention is more easily obtained.

[0059] The PVA film is dried (solvent removed) on the support preferably until the volatile content is 5 to 50% by mass, and then peeled off from the support and further dried as necessary. The drying method is not particularly limited, and examples thereof include a method of passing the material through a drying oven and a method of contacting the material with a drying roll. When drying a PVA film using multiple drying rolls, it is preferable to alternately contact one surface of the PVA film with the drying rolls. This allows the difference in the crystallinity index of PVA on both sides of the PVA film to be controlled. In this case, the number of drying rolls is preferably 3 or more, more preferably 4 or more, and even more preferably 5 to 30.

[0060] The temperature of the drying oven or drying roll is preferably 30 to 100°C. The upper limit of the temperature of the drying oven or drying roll is more preferably 110°C or lower, even more preferably 100°C or lower, and particularly preferably 95°C or lower. On the other hand, the lower limit of the temperature of the drying oven or drying roll is more preferably 45°C or higher, and even more preferably 50°C or higher. By keeping the temperature of the drying oven or drying roll within the above upper and lower limits, it becomes easier to obtain a PVA film having the effects of the present invention. If the temperature is outside the above upper and lower limits, Fd1 and Fd2 tend to be large, and it may be difficult to obtain the film of the present invention.

[0061] The dried PVA film can be further heat-treated as needed, which allows adjustment of the properties of the PVA film, such as mechanical strength, water solubility, and birefringence. The heat treatment temperature is preferably 60 to 125°C. The upper limit of the heat treatment temperature is more preferably 120°C or lower. By setting the heat treatment temperature within the above range, it becomes easier to obtain a PVA film having the effects of the present invention. If the heat treatment temperature exceeds the above range, the difference in crystallinity index between the extreme surface layer and the relatively deep interior of the PVA film becomes too small, which may make it difficult to obtain the PVA film of the present invention.

[0062] The PVA film produced in this manner may be further subjected to humidity conditioning treatment, cutting of both ends (edges) of the film, etc., as necessary, and then wound into a roll on a cylindrical core and packaged in a moisture-proof manner to become a finished product.

[0063] The volatile content of the PVA film finally obtained through a series of treatments is not necessarily limited, but is preferably 1 to 5 mass %, more preferably 2 to 4 mass %.

[0064] <Application> The water-soluble film (PVA film) of the present invention has an excellent balance of mechanical strength, water solubility, and water-sealing properties between films, and can be suitably used in various film applications in which general water-soluble films are used. Examples of such film applications include pharmaceutical packaging films, hydraulic transfer base films, embroidery substrate films, release films for artificial marble molding, seed packaging films, and films for waste collection bags. Among these, the water-soluble film of the present invention is preferably applied to pharmaceutical packaging films, since the effects of the present invention are more pronounced.

[0065] When the water-soluble film of the present invention is applied to a film for packaging medicines, the types of medicines include, for example, agricultural chemicals, detergents (including bleaching agents), disinfectants, and the like. The physical properties of the drug are not particularly limited, and it may be acidic, neutral, or alkaline. The agent may also contain a boron-containing compound.

[0066] The drug may be in any form, such as powder, block, gel, or liquid. The packaging form is not particularly limited, and a unit packaging form in which a unit amount of drug is packaged (preferably sealed) is preferred. The water-soluble film of the present invention is applied to a drug packaging film to package a drug, thereby obtaining a package of the present invention. In other words, the package of the present invention includes a packaging material (capsule) made of the water-soluble film of the present invention and a drug encapsulated in the packaging material.

Example

[0067] The present invention will be specifically described below with reference to examples and the like, but the present invention is not limited to the following examples. The evaluation items and methods of the water-soluble PVA film are as follows.

[0068] <Dissolution time of PVA film> The dissolution time (seconds) when the PVA film was immersed in deionized water at 10°C was measured by the above method.

[0069] <Calculation of crystallization index by FT-IR measurement> As described above, since the value of the crystallinity index varies slightly depending on the moisture absorption amount of the film, in the present invention, the film was stored for 24 hours in an environment of temperature: 24.0°C, relative humidity: 45.0%RH, and measured with an FT-IR installed in a room of the same environment. The measurement was performed on both sides of the film under the following conditions.

[0070] Measuring device: NICOLET is 10 (manufactured by Thermo Fisher) Measurement conditions: One-time reflection ATR method, incident angle 45° Resolution: 4.0 cm -1 Number of integrations: 32 times Measurement temperature: 24.0°C (environmental temperature) Measurement humidity: 45.0%RH (environmental relative humidity) Prism: Diamond or germanium

[0071] The IR spectra of both sides of the PVA film were measured by FT-IR, and the crystallinity index was calculated by the above method.

[0072] <Sealability> For the evaluation of sealability at high speed, the evaluation at a low temperature where it is more difficult to adhere was carried out. Preliminary adjustment: Two rectangular test pieces measuring approximately 30 cm in the film direction (MD) and approximately 10 cm in the transverse direction (TD) were cut out of the PVA film for each sample and kept in an environment of 10°C and 35% RH for at least 16 hours. Film Lamination: One pre-conditioned film was placed on a table at 10°C and 35% RH, and the four corners of the film were secured with adhesive tape. Another film was then placed on top of it, and both ends of the 10 cm side were secured with adhesive tape. The free end was passed through an ESIPROOF proofing roller using a 140 / 10 anilox roller. 0.5 mL of deionized water was poured onto the doctor blade of the ESIPROOF proofing roller, and the roller was pulled at a speed of approximately 7.5 cm / s to bond the two films together. The roller was not pulled all the way to the edge of the film, leaving an unbonded portion at the edge for placement in the tensile tester chuck. Three 25 mm-wide strip specimens were cut from the bonded PVA film in the MD. Seal Strength Measurement: After lamination, the specimens were left for 10 minutes, then placed in a tensile tester and peeled in accordance with the T-peel test method based on JIS K6854-3:1999. The average of the three peel strengths was recorded as the adhesive strength. The measurement conditions for this test were a pulling speed of 254 mm / min.

[0073] <Carl> A water-soluble PVA film was cut into a 20 cm x 20 cm piece and stored for 24 hours in an environment of 24.0°C temperature and 45.0% RH relative humidity while hanging by a clip. When the film was placed on a horizontal surface, the curling at the edge of the film was evaluated according to the following criteria. Note that the surface of the film in contact with the horizontal surface was considered to be the outer surface of the curled film if the film curled. Evaluation criteria: ◯: No curl was observed at any edge, or the angle between the horizontal plane and the edge of the film was visually small, at 45° or less. △: Slight curl was observed at one of the edges. Here, "slight curl" means that the angle between the horizontal plane and the edge of the film was more than 45° and less than 180° when visually observed. An angle of 180° or more between the horizontal plane and the edge of the film means that the edge of the film is curled and comes into contact with the PVA film in the center. ×: Curling was observed at either end, where the angle between the plane and the film edge exceeded 180°; in other words, the film edge was cylindrical.

[0074] <Transportation Test> Two 50 x 70 mm samples were cut from the PVA film, stacked, and water-sealed on three sides to create a pouch. Approximately 35 g of detergent was placed in the resulting pouch, and the top (mouth) of the pouch was water-sealed to seal it, creating a package. The detergent composition was 8% by mass monoethanolamine, 24% by mass dodecylbenzenesulfonic acid, 20% by mass oleic acid, 24% by mass lauryl alcohol ethoxylate, 9% by mass propylene glycol, 9% by mass diethylene glycol, and 6% by mass water. Next, 100 of the resulting packages were packed into 45L polyethylene bags, which were then placed in a cardboard box (320 x 335 x 325cm). The gap between the polyethylene bag and the cardboard box was filled with cushioning material. The cardboard box containing the packages was then loaded onto a truck, and a transportation test was conducted, with 10 round trips between Okayama Prefecture and Tokyo. After transportation, the packages were visually inspected to determine the total number of packages that were torn and packages that were clearly deformed.

[0075] Example 1 First, a film-forming solution was prepared by blending 100 parts by mass of PVA (saponification degree 88 mol%, viscosity average polymerization degree 1700) obtained by saponifying polyvinyl acetate, 10 parts by mass of glycerin as a plasticizer, 0.1 parts by mass of lauric acid diethanolamide as a surfactant, and water. The volatile content of the film-forming solution was 68% by mass. Next, the film-forming solution was extruded from the T-die onto a first drying roll (surface temperature 95°C) in the form of a film, forming a liquid film on the first drying roll. On the first drying roll, hot air at 95°C was blown at a speed of 5 m / s onto the entire surface of the liquid film that was not in contact with the first drying roll, thereby drying the film. This produced a PVA film. The dried PVA film (dried to a moisture content of 27% by mass) was then peeled off from the first drying roll and dried by alternately contacting one side of the PVA film with each drying roll, after which it was wound up into a roll on a cylindrical core. The surface temperature of the second drying roll and subsequent rolls was set to approximately 65°C. The resulting PVA film had a thickness of 35 μm and a width of 1200 mm. The time required for complete dissolution of the obtained PVA film at 10°C was measured using the above method. The IR spectrum of the obtained PVA film was then measured using FT-IR, and the crystallinity index was calculated. Furthermore, the seal strength and curl of the PVA film were evaluated. Additionally, a transport test was conducted using the obtained film. The results are shown in Table 1.

[0076] <Example 2> A PVA film was obtained in the same manner as in Example 1, except that the PVA used to prepare the film-forming solution was changed to maleic acid monomethyl ester (MMM)-modified PVA (saponification degree 90 mol%, polymerization degree 1700, MMM modification amount 5 mol%). The complete dissolution time at 10°C, crystallinity index, seal strength, and curl of the obtained PVA film were evaluated. In addition, a transportation test was conducted using the obtained PVA film. The results are shown in Table 1.

[0077] Example 3 A PVA film was obtained in the same manner as in Example 2, except that after drying, only one side of the PVA film was heat-treated by contacting it with a metal roll with a surface temperature of 120°C for 30 seconds. The PVA film was evaluated for its complete dissolution time at 10°C, crystallinity index, seal strength, and curl. In addition, a transportation test was conducted using the obtained PVA film. The results are shown in Table 1.

[0078] Example 4 A PVA film was obtained in the same manner as in Example 1, except that the PVA used to prepare the film-forming solution was changed to a PVA modified with acrylamido-2-methylpropanesulfonate sodium (AMPS) (saponification degree 88 mol%, polymerization degree 1700, AMPS modification amount 2 mol%). The complete dissolution time at 10°C, crystallinity index, seal strength, and curl of the obtained PVA film were evaluated. In addition, a transportation test was conducted using the obtained PVA film. The results are shown in Table 1.

[0079] <Comparative Example 1> A PVA film was obtained in the same manner as in Example 2, except that the surface temperature of the second drying roll and subsequent rolls was changed to 80°C. The time to complete dissolution at 10°C, the crystallinity index, the seal strength, and the curl of the obtained PVA film were evaluated. In addition, a transportation test was carried out using the obtained PVA film. The results are shown in Table 1.

[0080] <Comparative Example 2> A PVA film was obtained in the same manner as in Example 1, except that the surface temperature of the first drying roll was changed to 80°C and the surface temperatures of the second drying roll and subsequent rolls were changed to 75°C. The PVA film obtained was evaluated for its complete dissolution time at 10°C, crystallinity index, seal strength, and curl. The results are shown in Table 1. A transportation test was not performed because the seal strength was low.

[0081] <Comparative Example 3> The PVA film obtained in Example 1 was heat-treated on each side using two heat-treatment rolls with a surface temperature set to 130°C. The PVA film obtained was evaluated for the time to complete dissolution at 10°C, the crystallinity index, seal strength, and curl. The results are shown in Table 1. Because the seal strength was low, a transportation test was not performed.

[0082] The evaluation results of the water-soluble film obtained are shown in Table 1.

[0083] [Table 1]

Claims

1. A water-soluble film containing a polyvinyl alcohol resin having a degree of saponification of 94 mol% or less, a degree of polymerization of 200 to 8000, and a modification amount of 5 mol% or less, and 1 part by mass or more and 70 parts by mass or less of a plasticizer, When the first surface of the water-soluble film is subjected to FT-IR measurement by the ATR method, the crystallinity index calculated using a diamond prism is Fd1, and the crystallinity index calculated using a germanium prism is Fg1, A water-soluble film, wherein Fd1 and Fg1 satisfy the following formula: 0.25 ≦ Fd1 ≦ 0.65 (1) Fd1 / Fg1 > 1 (2)

2. 2. The water-soluble film according to claim 1, wherein Fd1 and Fg1 satisfy the following formula: Fd1 / Fg1 ≦ 1.5 (3)

3. When the FT-IR measurement by the ATR method is performed on a second surface of the water-soluble film opposite to the first surface, the crystallinity index calculated using the diamond prism is Fd2 and the crystallinity index calculated using the germanium prism is Fg2, 3. The water-soluble film according to claim 1, wherein Fd2 and Fg2 satisfy the following formula: 0.25≦Fd2≦0.65 (4) Fd2 / Fg2 > 1 (5)

4. 4. The water-soluble film according to claim 3, wherein Fd2 and Fg2 satisfy the following formula: Fd2 / Fg2 ≦ 1.5 (6)

5. 5. The water-soluble film according to claim 3, wherein Fd1 and Fd2 satisfy the following formula: |Fd1-Fd2| ≦ 0.07 (7)

6. 6. The water-soluble film according to claim 3, wherein Fg1 and Fg2 satisfy the following formula: |Fg1-Fg2| ≦ 0.07 (8)

7. A package comprising a packaging material made of the water-soluble film according to any one of claims 1 to 6 and a drug contained in the packaging material.

8. 8. The package of claim 7, wherein the agent is a pesticide, a detergent, or a disinfectant.

9. 9. The package of claim 7 or 8, wherein the medicament is in liquid form.

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