Water-soluble film and packaging

Abstract

In addition to the long-period crystalline structure of the PVA molecules, the present invention also provides a water-soluble film that has excellent water solubility and is less likely to cause problems such as damage to packaging materials during storage / transportation by, for example, controlling the degree of phase separation between PVA and other components in the water-soluble film. The water-soluble film of the present invention is a water-soluble film containing a polyvinyl alcohol-based resin, wherein the water-soluble film is subjected to small-angle X-ray scattering (SAXS) measurement in a mixture of water and methanol at a volume ratio of 2:8, and the scattering vector value, i.e., the q value, obtained from the obtained scattering intensity distribution is 0.2 nm. ‑1 The scattering intensity is set to I(0.2), and the scattering vector value, i.e., the q value, is set to 0.5nm. ‑1 When the scattering intensity at the time is set to I(0.5), the intensity ratio of the scattering intensity I(0.5) to the scattering intensity I(0.2), that is, I(0.5) / I(0.2), is 0.05 to 0.5.

Description

Technical Field

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

[0002] In the related art, water-soluble films are used in a wide range of fields, such as packaging of various chemicals such as liquid detergents and pesticides, and seed tapes containing seeds, by utilizing their excellent solubility in water.

[0003] Polyvinyl alcohol resins (hereinafter sometimes referred to as "PVA") are mainly used as water-soluble films for the above-mentioned applications. Furthermore, water-soluble films whose water solubility is enhanced by adding various additives such as plasticizers or by using modified polyvinyl alcohol have been disclosed (for example, see Patent Document 1).

[0004] As a method for measuring the average separation distance between the crystal parts of the PVA molecules contained in the water-soluble film (hereinafter sometimes referred to as the "crystallization long period"), there is small-angle X-ray scattering (hereinafter sometimes referred to as "SAXS") measurement. In particular, SAXS measurement can also be performed when the water-soluble film is immersed in a solvent. Therefore, by performing SAXS measurement of the water-soluble film in water, it is also possible to grasp the structure of the crystallization long period based on the PVA molecules (hereinafter sometimes referred to as the "crystallization long period structure") (for example, refer to Patent Document 2).

[0005] Furthermore, the degree of phase separation between materials with different densities (the distance between phase-separated structures) can be understood from the scattering vector value (q value) in SAXS measurements. Generally, it is known that the greater the scattering intensity (I(q)) in the region with a small q value, the greater the degree of phase separation (see, for example, Non-Patent Document 1).

[0006] Previous technical literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-078166

[0009] Patent Document 2: WO2013 / 146147

[0010] Non-patent literature

[0011] Non-patent document 1: Sakurai et al. J. Appl. Cryst, 24679 (1991) Summary of the Invention

[0012] Technical issues to be solved by the invention

[0013] In recent years, products using water-soluble films containing PVA to package (contain) chemicals such as laundry detergents have been released. For these applications, the water-soluble films are required to dissolve quickly in water and release the contained chemicals, particularly in cold water, such as in winter.

[0014] In the previous method, by increasing the amount of the plasticizer added to the water-soluble film, the crystallinity of the water-soluble film is reduced, and the solubility of the water-soluble film in water (water solubility) is improved. However, in this method, the water solubility of the water-soluble film becomes higher, but the degree of the phase separation state between the plasticizer and the PVA becomes too large. Due to reasons such as the plasticizer oozing out of the water-soluble film, the adhesion between the water-soluble film and the reduction of the mechanical strength of the water-soluble film itself may cause problems such as the breakage of the packaging material during storage / transportation. Therefore, it is difficult to achieve a water-soluble film that can take into account both high water solubility and excellent storage / transportability.

[0015] The object of the present invention is to provide a water-soluble film having excellent water solubility and being less likely to cause problems such as damage to packaging materials during storage / transportation, for example, by controlling the degree of phase separation between PVA and other components in the water-soluble film in addition to the long-period crystalline structure of the PVA molecules.

[0016] Means for solving technical problems

[0017] As a result of repeated and intensive research, the present inventors have discovered that when SAXS measurements are performed on a water-soluble film in a mixture of water and methanol at a volume ratio of 2:8 (hereinafter sometimes referred to as "water-methanol"), the scattering vector value (q value) obtained from the obtained scattering intensity distribution is 0.5 nm. -1 The scattering intensity (I(0.5)) and q value are 0.2nm -1 The above object can be achieved by setting the intensity ratio (I(0.5) / I(0.2)) of the scattering intensity (I(0.2)) at 0.5 to 1.5 Å within a specific range. Based on this finding, the present inventors have conducted repeated studies and have completed the present invention.

[0018] That is, the present invention relates to the following [1] to [7].

[0019] [1] A water-soluble film comprising a polyvinyl alcohol-based resin, wherein:

[0020] The water-soluble film was subjected to small-angle X-ray scattering (SAXS) measurement in a mixture of water and methanol at a volume ratio of 2:8, and the scattering vector value (q value) obtained from the obtained scattering intensity distribution was 0.2 nm. -1The scattering intensity is set to I(0.2), and the scattering vector value (q value) is set to 0.5nm -1 When the scattering intensity at 0.5 is set to I(0.5), the intensity ratio of the scattering intensity I(0.5) to the scattering intensity I(0.2) (I(0.5) / I(0.2)) is 0.05 to 0.5;

[0021] [2] The water-soluble film according to [1] above, wherein

[0022] The water-soluble film further contains a plasticizer;

[0023] [3] The water-soluble film according to [2] above, wherein

[0024] The plasticizer is a polyol;

[0025] [4] The water-soluble film according to [3] above, wherein

[0026] The polyol comprises at least one selected from the group consisting of ethylene glycol, glycerol, diglycerol, propylene glycol, and diethylene glycol;

[0027] [5] A packaging body comprising:

[0028] A packaging material comprising the water-soluble film described in any one of [1] to [4] above; and

[0029] a medicine contained in the packaging material;

[0030] [6] The packaging body according to [5] above, wherein

[0031] The agent is a pesticide, a detergent or a fungicide;

[0032] [7] The packaging body according to [5] or [6] above, wherein:

[0033] The medicine is in liquid form.

[0034] Effects of the Invention

[0035] According to the present invention, there are provided a water-soluble film having excellent solubility in water (water-solubility) and which is less likely to cause problems such as damage to the packaging material during storage and transportation, and a package using the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A diagram schematically showing the crystal structure of a PVA molecule. DETAILED DESCRIPTION

[0037] Hereinafter, the present invention will be described in detail.

[0038] <Small-angle X-ray scattering measurement>

[0039] The water-soluble film of the present invention contains a polyvinyl alcohol resin (PVA). Hereinafter, the water-soluble film of the present invention may be referred to as a "PVA film". In addition, the PVA film of this embodiment preferably further contains other components (additives such as plasticizers) in addition to PVA.

[0040] The PVA film was subjected to SAXS measurement in a mixture of water and methanol (water-methanol) at a volume ratio of 2:8. The q value obtained from the X-ray scattering intensity distribution obtained by the SAXS measurement was 0.2 nm. -1 The scattering intensity is set to I(0.2), and the q value is set to 0.5nm -1 When the scattering intensity at the time is set to I(0.5), the intensity ratio of the scattering intensity I(0.5) to the scattering intensity I(0.2) (I(0.5) / I(0.2)) is 0.05 to 0.5.

[0041] Here, the measurement principle of SAXS measurement is that when the sample is irradiated with X-rays, the X-rays are scattered and interfered by the electrons around the atoms, and the diffraction caused by the scattering and interference is analyzed. SAXS measurement is an analytical method that measures the diffracted X-rays that appear in the small angle region of 2θ <10° and evaluates the structure of the substance. Generally, structures of a few nm to tens of nm in size can be evaluated. By using this diffraction information, it is possible to know the long-period crystalline structure of PVA molecules (structure based on the long-period crystalline structure of PVA molecules) and the degree of phase separation between the components contained in the PVA film.

[0042] When X-rays are incident on a regularly arranged material, they are scattered. The scattered X-rays interfere with each other, reinforcing each other in specific directions. According to the Bragg equation, where d is the lattice spacing, θ is the Bragg angle, and λ is the wavelength of the X-rays, the diffracted X-rays are observed only in directions that satisfy 2dsinθ = nλ.

[0043] According to the research of the present inventors, in PVA film, the q value is about 0.5nm. -1 Nearby, there are flaky crystals ( Figure 1 The diffraction peak of the repeating structure of the crystal part shown in FIG. 1 is about 0.2 nm. -1 Nearby, a repetitive structure originating from the lamellar crystals appears ( Figure 1 The diffraction peaks of the amorphous part are shown.

[0044] Therefore, when calculating the intensity ratio (I(0.5) / I(0.2)), a smaller value indicates a higher proportion of amorphous portions in the PVA molecules, and the water solubility of the PVA film tends to increase. On the other hand, if the intensity ratio is too small, the proportion of amorphous portions in the PVA molecules becomes too high, reducing the shape retention of the PVA film. This can easily lead to problems such as damage to packaging materials made of the PVA film during storage or transportation.

[0045] Furthermore, it is known that in the case of a PVA film containing PVA and other components other than PVA (additives such as plasticizers), generally, the greater the value of the scattering intensity (I(q)) in the region with a small q value, the greater the degree of phase separation (the interphase distance of the phase separation structure) as described above. According to the research of the present inventors, it is known that the degree of phase separation can be understood based on the intensity ratio of the two scattering intensities in the region with a small q value (particularly I(0.5) / I(0.2)).

[0046] Specifically, a smaller intensity ratio (I(0.5) / I(0.2)) indicates a greater scattering intensity at smaller q values, resulting in a greater degree of phase separation and a higher water solubility of the PVA film. On the other hand, if the intensity ratio is too small, the degree of phase separation becomes excessive, causing bleed-out of other components from the PVA film and potentially damaging the packaging material during storage or transportation.

[0047] Therefore, there is a preferred lower limit for the above-mentioned intensity ratio. On the other hand, if the above-mentioned intensity ratio is too large, the proportion of the crystalline portion in the PVA molecule becomes too high, and the degree of phase separation in the PVA film containing other components becomes too small, both of which tend to reduce the water solubility of the PVA film. Therefore, there is also a preferred upper limit for the above-mentioned intensity ratio.

[0048] Therefore, in the present invention, the intensity ratio (I(0.5) / I(0.2)) is set within the range of 0.05 to 0.5.

[0049] This structure optimizes the long-period crystal structure of the PVA molecules (i.e., the relationship between the crystalline and amorphous portions within the PVA molecules). Furthermore, when the PVA film contains other components, the degree of phase separation within the PVA film is also optimized. As a result, a PVA film with excellent water solubility is obtained, which is less susceptible to problems such as damage to packaging materials during storage and transportation.

[0050] The specific method of performing SAXS measurement is described below.

[0051] (SAXS measurement implementation method)

[0052] ·sample

[0053] The PVA film was cut into pieces of 2 cm x 1 cm in size without distinguishing between the width direction (TD) and the winding direction (MD) to prepare a plurality of samples.

[0054] First, the obtained sample is stored in a constant temperature and humidity chamber adjusted to 20°C-65%RH for 24 hours and the humidity is adjusted. Then, the sample is immersed in water methanol for 24 hours and swelled, and then 10 sheets are stacked together with water methanol in a measuring cell. In addition, regarding the structure of the cell, a polyimide film with a thickness of 7.5μm (manufactured by Chemplex, "Kapton film") is used as a window material on the incident light side and the reflected light side, and the interval between the window materials is set to about 1.5mm, which can seal the sample to be measured. By using this cell, the sample can be arranged in water methanol in the configuration of ordinary measurement in the following measuring device.

[0055] Measuring device

[0056] Nanoscale X-ray structure evaluation device (small-angle X-ray scattering measurement device: manufactured by Rigaku Corporation, "Nano Viewer")

[0057] Measurement conditions (transmission measurement)

[0058] X-rays: CuKα rays

[0059] Wavelength: 0.15418nm

[0060] Output: 40kV-20mA

[0061] First slit: φ0.4mm

[0062] Second slit: φ0.2mm

[0063] The third slit: φ0.45mm

[0064] Detector: Semiconductor two-dimensional detector (PILATUS-100K)

[0065] (Measurement area = 33.5 mm x 83.8 mm)

[0066] Pixel size: 0.172mm square

[0067] Camera length: 1004.51mm

[0068] Beam stopper diameter: 4mm

[0069] X-ray exposure time: 1 hour

[0070] Measurement mode: normal measurement

[0071] Ambient temperature: room temperature (22°C)

[0072] Data analysis

[0073] In SAXS measurements, scattered X-rays from structures such as the slits, air in the X-ray passage area, and water and methanol inside the cell overlap with scattered X-rays from the PVA film. Therefore, these scattered X-rays must be removed (corrected) as background.

[0074] Therefore, correction is performed by separately calculating the scattered intensity caused by the above and subtracting it from the scattered intensity obtained by measuring the sample.

[0075] Moreover, based on the scattering intensity image measured by the two-dimensional detector, the scattering intensity relative to the scattering vector q is integrated along the azimuth direction, and the relationship between the scattering vector q and the one-dimensional distribution of the scattering intensity I(q) is derived, thereby obtaining the scattering intensity distribution (scattering curve).

[0076] ·Understanding of the degree of long-period crystal structure and phase separation

[0077] In the present invention, the q value is calculated to be 0.5 nm. -1 The scattering intensity (I(0.5)) and q value are 0.2nm -1 The value of the intensity ratio (I(0.5) / I(0.2)) of the scattering intensity (I(0.2)) at the time of scattering is obtained. Thus, in this embodiment, the crystalline long-period structure of the PVA molecules (that is, the relationship between the amount of the crystalline part and the amorphous part in the PVA molecules) and the degree of phase separation in the PVA film are understood.

[0078] The larger the above-mentioned intensity ratio is, the greater the proportion of the crystalline part in the PVA molecules is, and the smaller the degree of phase separation in the PVA film is. On the contrary, the smaller the intensity ratio is, the greater the proportion of the amorphous part in the PVA molecules is, and the greater the degree of phase separation in the PVA film is.

[0079] The value of the intensity ratio (I(0.5) / I(0.2)) is 0.05 to 0.5, preferably 0.1 to 0.5.

[0080] When the intensity ratio exceeds 0.5, the proportion of crystalline portions in the PVA molecules is relatively high, and the degree of phase separation in the PVA film is relatively low. Consequently, the PVA film is less likely to exhibit the excellent water solubility resulting from the amorphous portions in the PVA molecules and the phase separation.

[0081] On the other hand, when the above-mentioned strength ratio is less than 0.05, it means that the proportion of the amorphous part in the PVA molecules is too large and the degree of phase separation in the PVA film is too large. Due to the leakage of plasticizer to the outside of the PVA film, the adhesion between the PVA films and the reduction of the mechanical strength of the PVA film itself, problems such as damage to the packaging material may easily occur during storage / transportation.

[0082] In the present invention, it is important to control the above-mentioned parameter (I(0.5) / I(0.2)) within the above-mentioned range. Examples of methods for controlling these parameters include: adjusting the type of PVA (such as the degree of saponification, modification amount, and the unmodified PVA / modified PVA mixing ratio); adjusting the type, amount, and method of addition of the plasticizer; adjusting film production conditions (such as stock solution preparation conditions, roll temperature, and heat treatment conditions); or a combination of these methods.

[0083] <Polyvinyl alcohol resin>

[0084] The water-soluble film (PVA film) of the present invention contains a polyvinyl alcohol-based resin (PVA).

[0085] As PVA, a polymer produced by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester monomer can be used.

[0086] Examples of the vinyl ester monomer include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl 2,2-dimethylpropionate, and vinyl versatate. Among these, vinyl acetate is preferred as the vinyl ester monomer.

[0087] The vinyl ester polymer is not particularly limited, but is preferably a polymer obtained using only one or two or more vinyl ester monomers as monomers, and more preferably a polymer obtained using only one vinyl ester monomer as a monomer. Alternatively, the vinyl ester polymer may be a copolymer of one or two or more vinyl ester monomers and other monomers copolymerizable with the one or two or more vinyl ester monomers.

[0088] Examples of other monomers include ethylene; olefins having 3 to 30 carbon atoms such as propylene, 1-butene, and isobutylene; acrylic acid or its salts; acrylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadecyl acrylate; methacrylic acid or its salts; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate; acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetoneacrylamide, acrylamidopropanesulfonic acid or its salts, dimethylaminopropylacrylamide or its salts, N-methylolacrylamide or its derivatives Acrylamide derivatives such as biological products; methacrylamide derivatives such as methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid or its salts, dimethylaminopropylmethacrylamide or its salts, N-hydroxymethylmethacrylamide or its derivatives; N-vinylamides such as N-vinylformamide, N-vinylacetamide, and N-vinylpyrrolidone; vinyl ethers such as methyl vinyl ether, vinyl ethyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, dodecyl vinyl ether, and octadecyl vinyl ether; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride; propylene compounds such as allyl acetate and allyl chloride; maleic acid or its salts, esters, or anhydrides; itaconic acid or its salts, esters, or anhydrides; vinylsilyl compounds such as vinyltrimethoxysilane; isopropenyl acetate, etc.

[0089] Furthermore, the vinyl ester polymer may have structural units derived from one or two or more of the above-mentioned other monomers.

[0090] From the perspective of improving both the water solubility and mechanical strength of the PVA film, the proportion of structural units derived from other monomers in the vinyl ester polymer is not particularly limited. Based on the molar number of all structural units constituting the vinyl ester polymer, it is preferably 15 mol% or less, and more preferably 5 mol% or less.

[0091] Furthermore, one method of controlling the phase separation state in a PVA film is to adjust the types and ratios of structural units derived from other monomers in the vinyl ester polymer.

[0092] The degree of polymerization of PVA is not particularly limited, but is preferably within the following ranges. Specifically, from the perspective of maintaining sufficient mechanical strength of the PVA film, the lower limit of the degree of polymerization is preferably 200 or greater, more preferably 300 or greater, and even more preferably 500 or greater. On the other hand, from the perspective of improving the productivity of PVA or the productivity of the PVA film, 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.

[0093] Here, the degree of polymerization refers to the average degree of polymerization measured in accordance with JIS K 6726-1994. In this specification, the degree of polymerization is determined by the following formula based on the limiting viscosity [η] (unit: deciliter / g) measured in 30°C water after resaponification and purification of PVA.

[0094] Degree of polymerization Po = ([η] × 10 4 / 8.29) (1 / 0.62)

[0095] In the present invention, the saponification degree of PVA is not particularly limited, but is preferably 64 to 93 mol%. Adjusting the saponification degree of PVA within the range of 64 to 93 mol% facilitates achieving both water solubility and mechanical strength of the PVA film. The lower limit of the saponification degree is not particularly limited, but is more preferably 70 mol% or higher, and even more preferably 75 mol% or higher. On the other hand, the upper limit of the saponification degree is not particularly limited, but is more preferably 91 mol% or lower, and even more preferably 90 mol% or lower.

[0096] Here, the saponification degree of PVA refers to the ratio (mol %) of the molar number of vinyl alcohol units to the total molar number of structural units (typically vinyl ester monomer units) that can be converted to vinyl alcohol units by saponification and vinyl alcohol units.

[0097] The saponification degree of PVA can be measured in accordance with the description of JIS K 6726-1994.

[0098] The PVA film may contain a single type of PVA, or may contain two or more types of PVA having different polymerization degrees, saponification degrees, and modification degrees.

[0099] The upper limit of the content of PVA in the PVA film is not particularly limited, but is preferably 100% by mass. On the other hand, the lower limit of the content of PVA is not particularly limited, but is preferably 50% by mass, more preferably 80% by mass, and further preferably 85% by mass.

[0100] <Plasticizer>

[0101] The PVA film preferably contains a plasticizer. By including a plasticizer, the water solubility of the PVA film can be improved, mechanical properties (such as impact resistance) can be enhanced, and good process passability during secondary processing can be imparted.

[0102] In the present invention, it is considered that the value of the intensity ratio (I(0.5) / I(0.2)), which is used as an indicator for understanding the degree of phase separation in the PVA film, is greatly affected by the dispersion state of the plasticizer in the PVA film. Therefore, when a large amount of a plasticizer with low affinity for PVA is added, the degree of phase separation in the PVA film becomes excessive, and when a small amount of a plasticizer with high affinity for PVA is added, almost no phase separation occurs in the PVA film. Therefore, in any case, the above parameter is outside the range of 0.05 to 0.5. Therefore, it is preferable to add a plasticizer with appropriate affinity for PVA to the PVA film in an appropriate amount.

[0103] As the plasticizer, polyol is preferred. The affinity of the polyol with PVA can be easily adjusted by appropriately selecting the number of hydroxyl groups and the number of carbon atoms.

[0104] Specific examples of the polyol include ethylene glycol, glycerin, diglycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, trimethylolpropane, and sorbitol.

[0105] Among the above-mentioned plasticizers, ethylene glycol, glycerin, diglycerin, propylene glycol, and diethylene glycol are preferred because they have an appropriate affinity with PVA, and glycerin is more preferred.

[0106] The above-mentioned plasticizers may be used alone or in combination of two or more.

[0107] Furthermore, by adjusting the content of the plasticizer in the PVA film, the phase separation state in the PVA film can be controlled.

[0108] Although it varies depending on the primary structure of the PVA molecular chain, a PVA film containing a small amount of plasticizer is generally more susceptible to crystallization of the PVA molecules by heat treatment than a PVA film without plasticizer. It is inferred that this is because the mobility of the PVA molecules is increased by adding a small amount of plasticizer, thereby making it easier for the PVA molecules to adopt a more energy-stable crystal structure (i.e., the proportion of the crystal portion occupied by the PVA molecules increases), and it is easy to form a phase separation state between the crystal portion of the PVA molecules and the plasticizer. On the other hand, if the PVA film contains an excessive amount of plasticizer, it will hinder the crystallization of the PVA molecules. It is inferred that this is because the amount of plasticizer that interacts with the hydroxyl groups possessed by the PVA molecules becomes too much, and the interaction between the PVA molecules becomes weaker.

[0109] Furthermore, based on the above, it is inferred that in a PVA film containing an appropriate amount of plasticizer, the PVA molecules are properly crystallized, thereby balancing the proportions of the crystalline and amorphous parts in the PVA molecules, thereby imparting excellent water solubility and high mechanical strength to the PVA film.

[0110] The content of the plasticizer in the PVA film is not particularly limited, but is preferably 5 to 70 parts by mass, more preferably 7 to 50 parts by mass, and even more preferably 10 to 30 parts by mass, relative to 100 parts by mass of PVA. When the plasticizer content is within the above range, the degree of phase separation in the resulting PVA film and the ratio of the crystalline portion to the amorphous portion in the PVA molecules can be easily adjusted within appropriate ranges.

[0111] <Starch / Water-soluble Polymer>

[0112] The PVA film may contain at least one of starch and a water-soluble polymer other than PVA. The inclusion of at least one of starch and a water-soluble polymer other than PVA can improve the mechanical strength of the PVA film, maintain the moisture resistance of the PVA film during handling, or adjust the rate at which the PVA film softens due to water absorption.

[0113] Examples of starch 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 undergone etherification, esterification, oxidation, and the like. Processed starches are particularly preferred.

[0114] The content of starch in the PVA film is not particularly limited, but is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, relative to 100 parts by mass of PVA. If the content of starch is within the above range, the degradation of the process passability of the PVA film can be prevented or suppressed.

[0115] 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, polyvinyl pyrrolidone, cellulose, acetyl cellulose, acetylbutyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, sodium alginate, and the like.

[0116] The content of the water-soluble polymer other than PVA in the PVA film is not particularly limited, and is preferably less than 15 parts by mass, more preferably less than 10 parts by mass, relative to 100 parts by mass of PVA. If the content of the water-soluble polymer other than PVA is within the above range, the water solubility of the PVA film can be fully improved.

[0117] <Surfactant>

[0118] The PVA film preferably contains a surfactant. By containing a surfactant, the handleability of the PVA film and the peelability of the PVA film from the film-forming device during production can be improved.

[0119] The surfactant is not particularly limited, and for example, anionic surfactants, nonionic surfactants, and the like can be used.

[0120] Examples of the anionic surfactant include carboxylic acid-based surfactants such as potassium laurate; sulfate-based surfactants such as octyl sulfate; and sulfonic acid-based surfactants such as dodecylbenzenesulfonate.

[0121] Examples of the nonionic surfactant 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; alkylamine surfactants such as polyethylene glycol lauramide; alkylamide surfactants such as polyoxyethylene lauric acid amide; polypropylene glycol ether surfactants such as polyoxyethylene polyoxypropylene ether; alkanolamide surfactants such as lauramide diethanol and oleoyl diethanolamine; and propenyl phenyl ether surfactants such as polyoxyalkylene propenyl phenyl ether.

[0122] Such surfactants may be used alone or in combination of two or more. Among the above-mentioned surfactants, there are no particular limitations on the surfactants, as they have excellent effects on reducing surface anomalies during the manufacture of PVA films. A nonionic surfactant is preferred, an alkanolamide surfactant is more preferred, and a dialkanolamide (e.g., diethanolamine) of an aliphatic carboxylic acid (e.g., a saturated or unsaturated aliphatic carboxylic acid having 8 to 30 carbon atoms) is further preferred.

[0123] The lower limit of the content of the surfactant in the PVA film is not particularly limited, and is preferably more than 0.01 mass parts, more preferably more than 0.02 mass parts, and more preferably more than 0.05 mass parts, relative to PVA100 mass parts. On the other hand, the upper limit of the content of the surfactant is not particularly limited, and is preferably less than 10 mass parts, more preferably less than 1 mass part, more preferably less than 0.5 mass parts, and especially preferably less than 0.3 mass parts, relative to PVA100 mass parts. If the content of the surfactant is within the above range, the PVA film during manufacture becomes better from the peelability of the film forming apparatus, and is difficult to produce the problems such as the generation of the agglomeration of the PVA film each other. In addition, it is difficult to produce the problems such as the oozing out of the surfactant to the PVA film surface or the deterioration of the PVA film appearance caused by the aggregation of the surfactant.

[0124] <Other ingredients>

[0125] In addition to plasticizers, starch, water-soluble polymers other than PVA, and surfactants, the PVA film may also contain ingredients such as moisture, antioxidants, ultraviolet absorbers, lubricants, cross-linking agents, colorants, fillers, preservatives, mildew inhibitors, and other polymer compounds within the scope that does not hinder the effects of the present invention.

[0126] The ratio of the total mass of PVA, plasticizer, starch, water-soluble polymers other than PVA, and surfactant to the total mass of the PVA film is not particularly limited, but is preferably 60 to 100 mass %, more preferably 80 to 100 mass %, and even more preferably 90 to 100 mass %.

[0127] In addition, the PVA film may contain 100% by mass of PVA.

[0128] Furthermore, among the above components, components that can phase separate from PVA include, in addition to the plasticizer, starch, water-soluble polymers other than PVA, surfactants, fillers, and other polymer compounds.

[0129] <Water-soluble film>

[0130] In the water-soluble film (PVA film) of the present invention, the total dissolution time when immersed in deionized water at 10°C is not particularly limited, and is preferably within the following range. That is, the upper limit of the total dissolution time is preferably within 150 seconds, more preferably within 90 seconds, further preferably within 60 seconds, and particularly preferably within 45 seconds. The PVA film whose upper limit of the total dissolution time is within the above range completes dissolution relatively early, and is therefore suitable for use as a film for packaging (packaging material) of medicines, etc. On the other hand, the lower limit of the total dissolution time is not particularly limited, and is preferably more than 5 seconds, more preferably more than 10 seconds, further preferably more than 15 seconds, and particularly preferably more than 20 seconds. In this way, if the PVA film has a not too short total dissolution time, it is difficult to produce problems such as the generation of agglomeration (adhesion) between the PVA films caused by the absorption of water in the atmosphere or the reduction of the mechanical strength of the PVA film itself.

[0131] This characteristic can be appropriately obtained by setting the value of the intensity ratio (I(0.5) / I(0.2)) within the above range.

[0132] The total dissolution time when a PVA film is immersed in deionized water at 10° C. can be measured as follows.

[0133] <1> The PVA film was placed in a constant temperature and humidity chamber adjusted to 20° C. and 65% RH for 16 hours or more to adjust the humidity.

[0134] <2> After cutting out a rectangular sample of 40 mm in length and 35 mm in width from the humidified PVA film, fix it between two 50 mm × 50 mm plastic plates with a rectangular window of 35 mm in length and 23 mm in width, so that the length direction of the sample is parallel to the length direction of the window (hole) and the sample is located approximately in the center of the width direction of the window.

[0135] <3> 300 mL of deionized water was added to a 500 mL beaker, and the mixture was stirred at 280 rpm using a magnetic stirrer equipped with a 3 cm long rod, while the water temperature was adjusted to 10°C.

[0136] <4> Be careful not to come into contact with the magnetic stirrer bar while placing the <2> The sample fixed on the plastic plate was immersed in deionized water in a beaker.

[0137] <5> The time from immersion in deionized water to complete disappearance of the sample immersed in deionized water was measured.

[0138] The thickness of the PVA film is not particularly limited, and is preferably within the following range. That is, the upper limit of the thickness is preferably 200 μm or less, more preferably 150 μm or less, further 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, further preferably 15 μm or more, and particularly preferably 20 μm or more. Since the thickness within the above range is not too large, the secondary processability of the PVA film can be appropriately prevented from deteriorating. On the other hand, since the thickness is not too small, sufficient mechanical strength can be maintained in the PVA film. In particular, in the present invention, the value of the strength ratio (I (0.5) / I (0.2)) is set within the above range, so even a PVA film with a relatively small thickness can maintain high mechanical strength.

[0139] Alternatively, the thickness of the PVA film may be measured at any 10 locations (for example, any 10 locations on a straight line drawn along the longitudinal direction of the PVA film) and the average value of the measured thicknesses may be determined as the thickness of the PVA film.

[0140] <Method for producing water-soluble film>

[0141] The method for producing the water-soluble film (PVA film) of the present invention is not particularly limited, and for example, any of the following methods can be used.

[0142] As a method for producing a PVA film, there can be mentioned a method of producing a film by adding a solvent, an additive, etc. to a homogenized film-forming solution to PVA by a cast film method, a wet film method (discharging into a poor solvent), a dry-wet film method, a gel film method (a method of temporarily cooling and gelling the film-forming solution, and then extracting and removing the solvent), or a combination of the above methods; a melt extrusion film method or an inflation molding method in which a film is produced by extruding a film-forming solution obtained by using an extruder or the like from a T-die or the like. Among the above methods, the cast film method and the melt extrusion film method are preferably used as the method for producing a PVA film. If the cast film method and the melt extrusion film method are used, a homogeneous PVA film can be obtained with high productivity.

[0143] Hereinafter, the case where a PVA film is produced by using a cast film forming method or a melt extrusion film forming method will be described.

[0144] Examples of the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane, ethylenediamine, and diethylenetriamine. Among these solvents, water is preferred from the perspective of low environmental load and ease of recycling. These solvents may be used alone or in combination of two or more.

[0145] The method for adjusting the film-forming stock solution is not particularly limited. For example, any method can be used, including: dissolving PVA in a solvent in a dissolution tank, then adding other components and homogenizing; or supplying a mixture of PVA, solvent, and plasticizer to an extruder and melting it, then adding other additives. Of these methods, the latter method is preferred because it facilitates appropriate adjustment of the phase separation state of the resulting PVA film.

[0146] In the latter method, the maximum shear rate of the extruder is not particularly limited, but is preferably 10 to 300 s. -1 The upper limit of the maximum shear rate is more preferably 200s -1 Below, more preferably 150s -1 On the other hand, the lower limit of the maximum value of the shear rate is more preferably 12s -1 More than 15s is more preferred -1 If the maximum shear rate is within the above range, the dispersibility of other components (such as plasticizers and other additives) other than PVA relative to PVA becomes sufficiently high, and the long-period crystal structure of PVA molecules and the phase separation state in the PVA film become good.

[0147] When a PVA film is produced using a cast film method or a melt extrusion film method, a film-forming stock solution containing PVA, a solvent, and, if necessary, additives such as a plasticizer is first prepared. When the film-forming stock solution contains additives, the ratio of the additives to the PVA in the film-forming stock solution is substantially equal to the ratio of the additives to the PVA in the PVA film.

[0148] Next, the film-forming stock solution is poured (supplied) onto a rotating support such as a metal roller or metal belt in a film-like form. This forms a liquid film of the film-forming stock solution on the support. The liquid film is heated on the support to remove the solvent, thereby solidifying and forming a thin film.

[0149] The cured long film (PVA film) is peeled from the support, dried by passing through a drying roll, a drying oven, etc. as needed, further subjected to heat treatment as needed, and wound into a roll.

[0150] During the drying process (solvent removal process) of the liquid coating that has been drooled onto the support, and the subsequent drying process of the PVA film, the PVA crystallizes during the heating and drying period. In particular, heating is performed in an area with a high moisture content, thereby increasing the mobility of the PVA molecular chains, causing crystallization and increasing the degree of crystallinity. Therefore, the degree of crystallization of the PVA can be controlled by the drying speed in the drying process. For example, if the drying speed is increased, crystal growth is hindered, and the degree of crystallinity tends to decrease. On the other hand, if the drying speed is slowed down, crystal growth is promoted, and the degree of crystallinity tends to increase. Furthermore, if the applied heat is increased, the degree of crystallinity of the PVA tends to increase, and the water solubility of the PVA film tends to decrease. Furthermore, in this embodiment, by controlling the degree of crystallization of the PVA, the phase separation state in the PVA film can also be adjusted.

[0151] The drying speed can be adjusted by the support temperature, the contact time with the support, the temperature and amount of hot air, the temperature of the drying roller and the drying furnace, and the like.

[0152] The volatile fraction (the concentration of volatile components such as solvents removed by volatilization or evaporation during film formation) of the film-forming stock solution is not particularly limited, but is preferably 50 to 90% by mass, and more preferably 55 to 80% by mass. If the volatile fraction is within the above range, the viscosity of the film-forming stock solution can be adjusted within the preferred range, thereby improving the film-forming properties of the PVA film (liquid coating) and making it easier to obtain a PVA film with a uniform thickness. Furthermore, an appropriate volatile fraction of the film-forming stock solution allows for proper crystallization of the PVA on the support, making it easier to achieve a good phase separation state in the PVA film.

[0153] Here, the "volatile content of the membrane-forming stock solution" in this specification refers to a value obtained by the following formula.

[0154] Volatile fraction of film-forming stock solution (mass %) = {(Wa-Wb) / Wa} × 100

[0155] Wherein Wa represents the mass (g) of the film-forming stock solution, and Wb represents the mass (g) of the film-forming stock solution after drying Wa (g) in an electric drying machine at 105°C for 16 hours.

[0156] The surface temperature of the support on which the film-forming stock solution is drooled is not particularly limited, but is preferably 50 to 110°C, more preferably 60 to 100°C, and even more preferably 65 to 95°C. If the surface temperature is within the above range, the drying of the liquid coating proceeds at an appropriate rate, thereby making it easy to adjust the long-period crystalline structure of the PVA molecules. In other words, the crystallinity of the PVA will neither become extremely high nor extremely low, so the degree of phase separation between the PVA and the plasticizer and other additives in the PVA film is likely to be appropriate. Furthermore, the drying of the liquid coating proceeds at an appropriate rate, thereby preventing the time required for drying the liquid coating from being excessively long, preventing a decrease in the productivity of the PVA film, and making it difficult for abnormalities such as bubbles to form on the surface of the PVA film.

[0157] While heating the liquid coating on the support, hot air at a speed of 1 to 10 m / s can be evenly blown across the entire non-contact surface of the liquid coating. This allows for adjustment of the drying rate of the liquid coating. The temperature of the hot air blown to the non-contact surface is not particularly limited, but is preferably 50 to 150°C, more preferably 70 to 120°C. When the hot air temperature falls within this range, the drying efficiency and uniformity of the liquid coating can be further improved.

[0158] The PVA film is preferably dried (solvent removed) on the support to a volatile content of 5 to 50% by mass, and then peeled from the support and further dried as needed.

[0159] The drying method is not particularly limited, and examples thereof include a method of passing the mixture through a drying furnace and a method of contacting the mixture with a drying roll.

[0160] When drying a PVA film using multiple drying rollers, it is preferable to alternately contact one side and the other side of the PVA film with the drying rollers. This allows for uniform crystallinity and phase separation of the PVA on both sides of the PVA film. The number of drying rollers is not particularly limited, but is preferably three or more, more preferably four or more, and even more preferably 5 to 30.

[0161] The temperature of the drying furnace or drying roller is not particularly limited, but is preferably 40 to 110°C. The upper limit of the temperature of the drying furnace or drying roller is more preferably 100°C or lower, further preferably 90°C or lower, and particularly preferably 85°C or lower. On the other hand, the lower limit of the temperature of the drying furnace or drying roller is more preferably 45°C or higher, further preferably 50°C or higher. When the temperature of the drying furnace or drying roller is within this range, it is easier to adjust the balance between the proportion of the crystalline portion and the proportion of the amorphous portion in the PVA molecules.

[0162] The dried PVA film may be subjected to a heat treatment as needed, thereby adjusting the mechanical strength, water solubility, birefringence, and other properties of the PVA film.

[0163] The heat treatment temperature is not particularly limited, but is preferably 60 to 135° C. The upper limit of the heat treatment temperature is more preferably 130° C. or lower. When the heat treatment temperature is within this range, the amount of heat applied to the PVA film is appropriate, preventing the PVA from becoming excessively crystallized.

[0164] The water-soluble film thus produced is subjected to humidity control treatment, cutting of both ends (ear parts) of the film, etc. as needed, and then wound into a roll on a cylindrical core and moisture-proof packaged to obtain a product.

[0165] The volatile content of the PVA film finally obtained through a series of treatments is not particularly limited, but is preferably 1 to 5% by mass, more preferably 2 to 4% by mass.

[0166] <Purpose>

[0167] The water-soluble film (PVA film) of the present invention has an excellent balance between water solubility and mechanical strength, and can be suitably used in various film applications to which general water-soluble films are applied.

[0168] Examples of applications for the film include pharmaceutical packaging films, base films for hydraulic transfer printing, embroidery substrate films, release films for artificial marble molding, seed packaging films, and waste collection bag films. Among these films, the effects of the present invention are more significantly achieved, and therefore the water-soluble film of the present invention is preferably used as pharmaceutical packaging film.

[0169] When the water-soluble film of the present invention is used as a film for packaging pharmaceuticals, examples of the pharmaceuticals include agricultural chemicals, detergents (including bleaching agents), and fungicides.

[0170] The physical properties of the drug are not particularly limited and may be acidic, neutral, or alkaline.

[0171] Furthermore, the medicament may contain a boron-containing compound.

[0172] The form of the medicine may be any of powder, block, gel, and liquid, but liquid is preferred.

[0173] The packaging method is not particularly limited, but a unit packaging method in which the drug is packaged (preferably sealed) in unit amounts is preferred.

[0174] The package of the present invention can be obtained by applying the water-soluble film of the present invention to a film for packaging pharmaceuticals. In other words, the package of the present invention comprises a packaging material (capsule) composed of the water-soluble film of the present invention and a pharmaceutical contained in the packaging material.

[0175] The water-soluble film of the present invention has an intensity ratio (I(0.5) / I(0.2)) of 0.05 to 0.5, resulting in excellent water solubility, low adhesion, and high mechanical strength. Consequently, the packaging material of the present invention dissolves rapidly in water under cold conditions, such as winter, effectively releasing the contained pharmaceutical agent. Furthermore, the packaging of the present invention is less susceptible to damage to the packaging material during storage and transportation.

[0176] Example

[0177] The present invention will be described in detail below by way of examples, etc. However, the present invention is not limited to the following examples. The evaluation items and evaluation methods used in the following examples and comparative examples are as follows.

[0178] (1) Small-angle X-ray scattering (SAXS) measurements and calculation of the intensity ratio of scattered light

[0179] Under the above conditions, the prepared water-soluble film was subjected to small-angle X-ray scattering measurement, and the scattering vector value (q value) was read as 0.2 nm from the obtained scattering intensity distribution. -1 The scattering intensity and q value at 0.5nm -1 The scattering intensity values ​​at , and their ratio were calculated.

[0180] (2) Full dissolution time of PVA film

[0181] The total dissolution time of the PVA film in deionized water at 10°C was calculated using the above method.

[0182] (3) Transport test

[0183] First, two samples cut from a PVA film into a size of 50 mm x 70 mm were stacked and heat-sealed on three sides to prepare a packaging material.

[0184] About 35 g of detergent was added to the obtained packaging material, and the upper portion (opening) of the packaging material was heat-sealed to seal the packaging body. Thus, a package was produced.

[0185] The detergent composition is 8% by mass of monoethanolamine, 24% by mass of dodecylbenzenesulfonic acid, 20% by mass of oleic acid, 24% by mass of lauryl alcohol ethoxylate, 9% by mass of propylene glycol, 9% by mass of diethylene glycol, and 6% by mass of water.

[0186] Next, 100 of the obtained packages were placed in a 45 L polyethylene bag, which was then placed in a corrugated cardboard box (320 cm x 335 cm x 325 cm). A cushioning material was placed in the gap between the polyethylene bag and the corrugated cardboard box.

[0187] Then, the corrugated cardboard boxes containing the packages were piled on a truck and transported back and forth 10 times between Okayama Prefecture and Tokyo.

[0188] The packages after transport were observed, and the total number of packages with observed damage and obvious deformation was investigated.

[0189] <Example 1>

[0190] First, a film-forming stock solution was prepared by mixing 100 parts by mass of PVA (saponification degree 88 mol%, viscosity-average degree of polymerization 1700) obtained by saponifying polyvinyl acetate, 20 parts by mass of polyethylene glycol (PEG) with an average molecular weight of 500 as a plasticizer, 0.1 parts by mass of lauramide diethanol as a surfactant, and water. The volatile content of the film-forming stock solution was 68% by mass.

[0191] Next, a single screw extruder was used with a maximum shear rate of 18s -1 Under the following conditions, the film-forming stock solution was discharged from a T-die in the form of a film onto the first drying roller (surface temperature of 80°C) serving as a support, forming a liquid coating on the first drying roller. On the first drying roller, hot air at 85°C was blown at a speed of 5 m / s over the entire surface of the liquid coating that was not in contact with the first drying roller, drying it. Thus, a PVA film was obtained.

[0192] Next, the PVA film was peeled from the first drying roller, dried by alternating one side and the other side of the PVA film with the drying rollers. The film was then wound onto a cylindrical core in a roll. The surface temperature of the drying rollers from the second drying roller onward was set to approximately 75°C. The resulting PVA film had a thickness of 35 μm and a width of 1200 mm.

[0193] As a result of SAXS measurement of the obtained PVA film, I(0.5) / I(0.2) was 0.15.

[0194] Furthermore, the complete dissolution time of the obtained PVA film was measured and found to be 34 seconds.

[0195] Furthermore, a transport test was conducted on packages produced from the obtained PVA films. As a result, 5 packages were damaged after transport.

[0196] <Example 2 and Comparative Example 1>

[0197] A PVA film was obtained in the same manner as in Example 1 except that the amounts of polyethylene glycol used for preparing the film-forming stock solution were changed to 10 parts by mass and 40 parts by mass, respectively.

[0198] <Comparative Example 2>

[0199] The maximum shear rate of the extruder during film formation was adjusted to 7s -1 A PVA film was obtained in the same manner as in Example 1 except for the above. In addition, the maximum value of the shear rate was adjusted by changing the groove depth and the rotation speed of the extruder screw.

[0200] <Comparative Example 3>

[0201] A PVA film was obtained in the same manner as in Example 1 except that the surface temperature of the first drying roller discharging the film-forming stock solution was changed to 40°C and the temperature of the hot air blown to the surface of the liquid coating not in contact with the first drying roller was changed to 45°C.

[0202] <Example 3>

[0203] A PVA film was obtained in the same manner as in Example 1 except that the plasticizer used for preparing the film-forming stock solution was changed from polyethylene glycol to glycerol.

[0204] <Example 4 and Comparative Example 4>

[0205] A PVA film was obtained in the same manner as in Example 3 except that the amounts of glycerol used in preparing the film-forming stock solution were changed to 10 parts by mass and 2 parts by mass, respectively.

[0206] <Example 5 and Example 6>

[0207] The PVA used to prepare the film-forming solution was changed to maleic anhydride (MAn)-modified PVA (saponification degree of 98 mol%, polymerization degree of 1700, modification amount of 2 mol%) and sodium acrylamide-2-methylpropanesulfonate (AMPS)-modified PVA (saponification degree of 88 mol%, polymerization degree of 1700, AMPS modification amount of 2 mol%), respectively. Except for this, a PVA film was obtained in the same manner as Example 4.

[0208] <Example 7>

[0209] A PVA film was obtained in the same manner as in Example 5 except that the addition of plasticizer was omitted when preparing the film-forming stock solution, the surface temperature of the first drying roller that discharges the film-forming stock solution was changed to 40°C, and the temperature of the hot air blown onto the non-contact surface of the liquid coating with the first drying roller was changed to 45°C.

[0210] Table 1 shows the evaluation results of the obtained films.

[0211]

[0212] As shown in Table 1, the PVA films of the Examples, whose strength ratio (I(0.5) / I(0.2)) was within the range of 0.05 to 0.5, exhibited excellent water solubility and mechanical strength. In contrast, the PVA films of the Comparative Examples, which did not meet these conditions, exhibited poor water solubility or mechanical strength.

Claims

1. A water-soluble film comprising a polyvinyl alcohol-based resin, wherein: The water-soluble film was subjected to small-angle X-ray scattering measurement in a mixture of water and methanol at a volume ratio of 2:

8. The scattering vector value, i.e., the q value, obtained from the obtained scattering intensity distribution was 0.2 nm. -1 The scattering intensity is set to I(0.2), and the scattering vector value, i.e., the q value, is set to 0.5nm. -1 When the scattering intensity is set to I(0.5), the intensity ratio of the scattering intensity I(0.5) to the scattering intensity I(0.2), that is, I(0.5) / I(0.2), is 0.05 to 0.5, The water-soluble film contains a plasticizer, and the plasticizer is a polyol. The content of the plasticizer is 10 to 30 parts by mass relative to 100 parts by mass of the polyvinyl alcohol resin. Small-angle X-ray scattering measurements are performed as follows: The samples were prepared as follows: Cut the water-soluble film into 2 cm × 1 cm pieces regardless of the width direction or the winding direction to prepare multiple samples. First, the obtained sample is stored in a constant temperature and humidity chamber adjusted to 20°C-65% RH for 24 hours to adjust the humidity. Then, the sample is immersed in water-methanol for 24 hours to swell, and then 10 sheets are stacked together with water-methanol in a measurement cell. In addition, regarding the structure of the cell, a polyimide film with a thickness of 7.5 μm is used as the window material on the incident light side and the reflected light side, and the spacing between the window materials is set to 1.5 mm, which can seal the sample to be measured. By using this cell, the sample can be arranged in water-methanol using the configuration of the normal measurement in the following measurement device. The polyimide film is "Kapton film" manufactured by Chemplex. The measuring device is: Nanoscale X-ray structure evaluation device, which is a small-angle X-ray scattering measurement device: Rigaku Corporation's "Nano Viewer" Measurement conditions X-rays: CuKα rays Wavelength: 0.15418nm Output: 40kV-20mA First slit: φ0.4mm Second slit: φ0.2mm The third slit: φ0.45mm Detector: Semiconductor two-dimensional detector, PILATUS-100K Measuring area = 33.5 mm × 83.8 mm Pixel size: 0.172mm square Camera length: 1004.51mm Beam stopper diameter: 4mm X-ray exposure time: 1 hour Measurement mode: normal measurement Ambient temperature: 22°C Data analysis was performed as follows: In small-angle X-ray scattering measurements, scattered X-rays from the slit, air present in the X-ray passage portion, and water and methanol present inside the cell overlap with scattered X-rays from the water-soluble film. Therefore, the scattered X-rays from these sources need to be removed as background, i.e., corrected. Correction is performed by calculating the scattered intensity caused by the above separately and subtracting it from the scattered intensity obtained by measuring the sample. Based on the scattering intensity image measured by the two-dimensional detector, the scattering intensity relative to the scattering vector q is integrated along the azimuth direction, and the relationship between the scattering vector q and the one-dimensional distribution of the scattering intensity I(q) is derived, thereby obtaining the scattering intensity distribution, that is, the scattering curve.

2. The water-soluble film according to claim 1, wherein The polyol includes at least one selected from the group consisting of ethylene glycol, glycerol, diglycerol, propylene glycol, and diethylene glycol.

3. A packaging body, comprising: A packaging material consisting of the water-soluble film according to claim 1 or 2; and The medicine is contained in the packaging material.

4. The packaging body according to claim 3, wherein The medicament is a pesticide, a detergent or a fungicide.

5. The packaging body according to claim 3 or 4, wherein The medicine is in liquid form.

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