Water-soluble film and package

Abstract

Provided is a water-soluble film that can balance water solubility and resistance to oxidative degradation. The water-soluble film of the present invention contains a polyvinyl alcohol resin, has a surface in which the proportion of carbonyl groups in the total carbon bonds obtained by X-ray photoelectron spectroscopy is 1 to 5% on at least one side, and has a total dissolution time in water at 10°C of 120 seconds or less.

Description

TECHNICAL FIELD

[0001] The present application relates to a water-soluble film suitable for packaging and the like of various agents, and a package using the same. BACKGROUND

[0002] Conventionally, a water-soluble film has been used in a wide range of fields such as packaging of liquid detergents, agricultural chemicals, and the like, and seed tapes containing seeds, by virtue of its water-solubility.

[0003] Among water-soluble films for such use, a film mainly using polyvinyl alcohol resin (hereinafter, sometimes referred to as PVA) has been proposed, which improves water-solubility by incorporating various additives such as plasticizers, or using modified polyvinyl alcohol (for example, Patent Literature 1).

[0004] In the above conventional method, water-solubility is improved by a method of reducing the crystallinity of PVA. However, in recent years, in packaging of liquid detergents and the like, which are in increasing demand, in the case of an agent having oxidizing properties, there has been a tendency for the water-soluble film to be susceptible to oxidative degradation on the inner side surface in contact with the agent. If oxidative degradation occurs, the strength of the water-soluble film decreases, and sometimes becomes a cause of breakage and the like.

[0005] Prior Art Documents

[0006] Patent Literature

[0007] Patent Literature 1: Japanese Patent Application Laid-Open No. 2017-078166 SUMMARY

[0008] Technical Problem to be Solved by the Invention

[0009] It is known that oxidative degradation particularly easily occurs from the carbonyl group (hereinafter, sometimes referred to as C=O) of PVA. Also, it is known that a structure is adopted in which a carbon-carbon double bond (hereinafter, sometimes referred to as C=C) is generated by dehydration reaction of the vinyl alcohol unit located next to the terminal aldehyde of PVA, starting from the terminal aldehyde of PVA, which further causes conjugated double bond structures, so-called polyene structures, generated by dehydration reaction in the adjacent vinyl alcohol unit. In the case where a large amount of such polyene structures exist on the surface of the water-soluble film, the hydrophobicity of the water-soluble film becomes high and the oxidative degradation resistance is improved. On the other hand, if the hydrophobicity of the water-soluble film is too high, the solubility of the film in cold water (cold water solubility) decreases. That is, there is a trade-off relationship between the cold water solubility and the oxidative degradation resistance of the water-soluble film. In the conventional water-soluble film, it is difficult to balance the cold water solubility and the oxidative degradation resistance of the film.

[0010] Therefore, an object of the present application is to provide a water-soluble film capable of balancing the cold water solubility and the oxidative degradation resistance.

[0011] means for solving technical problems

[0012] X-ray photoelectric spectrophotometry (hereinafter, sometimes referred to as XPS) is a method for quantifying the amount of elements present on the surface of thin films. In the case of water-soluble PVA thin films, XPS measurements can quantify elements such as fluorine (F) and silicon (Si) in addition to carbon (C) and oxygen (O).

[0013] Furthermore, it is possible to determine the bonding state and proportion of an element based on detailed XPS-based analysis of various elements. For example, it is possible to distinguish between carbon-carbon single bonds (hereinafter, sometimes referred to as CC) and C=O, and to determine the proportion of each bond in the total carbon bonds.

[0014] Based on the insights gained from the detailed analysis of various elements using XPS, the inventors conducted further in-depth research and discovered that by adjusting the proportion of carbonyl groups in the total carbon bonds within a specific range, obtained through X-ray photoelectron spectroscopy analysis of the surface portion of one or both sides of the water-soluble film, the aforementioned objective could be achieved. Based on this insight, the inventors conducted further research and completed the present invention.

[0015] That is, the present invention relates to the following: [1]

[0017] A water-soluble film containing polyvinyl alcohol resin, having at least one side having a surface with a carbonyl group content of 1 to 5% in total carbon bonds as determined by X-ray photoelectron spectrophotometry, and having a total dissolution time of less than 120 seconds in water at 10°C.

[0018] Furthermore, the present invention relates to the following: [2]

[0020] According to the water-soluble film described above [1], wherein,

[0021] On the surface of the total carbon bonds, the ratio of the carbon-carbon single bond ratio to the carbonyl group ratio (CC / C=O), obtained further by X-ray photoelectron spectrophotometry, is 10 to 50. [3]

[0023] According to the water-soluble film described in [1] or [2] above, wherein,

[0024] On the surface of the total carbon bonds, the carbon content of carbon is 50% to 70% and the oxygen content is 20% to 35% of all elements as determined by X-ray photoelectron spectrophotometry, and the carbon to oxygen ratio (C / O) is 1.5 to 3.5. [4]

[0026] The water-soluble film according to any one of the above [1] to [3], wherein

[0027] the surface having the proportion of the carbonyl group in the total carbon bond within the range is surface-modified; and [5]

[0029] The water-soluble film according to the above [4], wherein

[0030] The surface modification is based on any one of ultraviolet treatment, ozone treatment, corona treatment, and plasma treatment.

[0031] Further, the present application relates to the following: [6]

[0033] A package, wherein

[0034] The water-soluble film according to any one of the above [1] to [5] contains a medicament; [7]

[0036] The package according to the above [6], wherein

[0037] The medicament is a pesticide or a detergent; [8]

[0039] The package according to the above [6] or [7], wherein

[0040] The medicament is in a liquid form; and [9]

[0042] The package according to any one of the above [6] to [8], wherein

[0043] The medicament is contained in a manner that the surface having the proportion of the carbonyl group in the total carbon bond within 1 to 5% is in contact with the medicament.

[0044] Effects of the Invention

[0045] According to the present application, a water-soluble film capable of balancing cold water solubility and resistance to oxidative degradation can be provided. DETAILED DESCRIPTION

[0046] Hereinafter, the present application will be specifically described.

[0047] <XPS Measurement>

[0048] In the present application, the amount of elements on the surface of the water-soluble film is measured by XPS. XPS measurement is a method in which core electrons of atoms are excited by irradiating X-rays to the surface of a sample, and the kinetic energy of photoelectrons released therefrom is detected, thereby identifying and quantifying elements present on the surface of the sample, and analyzing the chemical bonding state. In XPS analysis, elements present at a depth of about 2 to 8 nm from the surface can be measured.

[0049] Also, in the XPS measurement, when the horizontal axis is set as the kinetic energy and the vertical axis is set as the intensity, a peak attributed to C1s can be obtained from photoelectrons originating from carbon atoms present on the surface of the sample. This peak is a peak obtained by synthesizing various peaks depending on the bonding state of the carbon atoms. The positions of these various peaks are determined depending on the bonding state of the carbon atoms. For example, C-C or carbon-hydrogen bond (hereinafter, sometimes referred to as C-H) shows a peak at a position of 285 eV, carbon-oxygen single bond (hereinafter, sometimes referred to as C-O) shows a peak at a position of 286.6 eV, carbon-nitrogen single bond (hereinafter, sometimes referred to as C-N) shows a peak at a position of 285.7 eV, C=O shows a peak at a position of 287.7 eV, ester bond (hereinafter, sometimes referred to as C(=O)-O) shows a peak at a position of 289.4 eV, carbonate bond (hereinafter, sometimes referred to as O-C(=O)-O) shows a peak at a position of 290 eV. The C1s peak obtained by synthesizing these peaks can be separated into each peak, for example, by automatic waveform separation fitting attached to the XPS analysis device. (Reference Patent Document: Japanese Patent Application Laid-Open No. 2007-302740)

[0050] The peaks attributed to the above-described each bond are obtained by detailed analysis (narrow scan) of C1s. Narrow scan is an analysis method in which a narrow range of energy range is scanned under high energy resolution conditions, and the chemical state of the element of the analysis object is determined from the peak position and the peak shape.

[0051] The water-soluble film of the present application is a water-soluble film in which the presence ratio of C=O in the total carbon bond on at least one surface is 1 to 5%. In the case where the presence ratio of C=O is less than 1%, the surface of the film is hydrophobic, and sufficient cold water solubility cannot be ensured. On the other hand, in the case where the ratio is more than 5%, the resistance to oxidative degradation is poor, and breakage or the like occurs.

[0052] The presence ratio of C=O is preferably 1.5% or more, more preferably 2.0% or more, and further preferably 2.5% or more. Also, the presence ratio of C=O is preferably 4.5% or less, further preferably 4.0% or less, and particularly preferably 3.5% or less.

[0053] In addition, the "proportion of C=O present in the total carbon bonds" is the proportion of the peak attributed to C=O in the CIs peak obtained by detailed analysis of the CIs peak by the above-described narrow scan and by the above-described automatic waveform separation fitting, and this proportion (%) is taken as the proportion of C=O present.

[0054] In the present application, the proportion of C=O present in the surface portion of 1 to 5% can be either one of the single surface or both surfaces of the water-soluble film, but in the case of the single surface, it is preferable to make this surface face the side where oxidative degradation is likely to occur at the time of manufacturing the packaging body. That is, in the case where the medicine or the like to be packaged has oxidizing properties, it is preferable to make the packaging body in which the surface portion of the water-soluble film having a proportion of C=O present of 1 to 5% is on the inside, and the surface portion of the water-soluble film having a proportion of C=O present of 1 to 5% contacts the medicine.

[0055] In the case of a packaging body using a water-soluble film in which three or more water-soluble films are used to package a medicine between the films, which has been increasing in use in recent years, it is preferable for the water-soluble film in which both surfaces of the film contact the medicine to have a proportion of C=O present in the surface portion of 1 to 5% on both surfaces.

[0056] As described above, in the water-soluble film of the present application, the proportion of C=O present in the surface of at least one surface is 1 to 5%, and further, from the viewpoint of oxidative degradation resistance, the ratio of the proportion of C-C present to the proportion of C=O present (hereinafter, sometimes referred to simply as C-C / C=O) in the surface obtained by X-ray photoelectron spectroscopy is preferably 10 to 50, and more preferably 10 to 20.

[0057] The proportion of C-C present is obtained in the same manner as the proportion of C=O present, by detailed analysis of the CIs peak by the above-described narrow scan and by the above-described automatic waveform separation fitting, and the proportion of the peak attributed to carbon-carbon single bonds in the CIs peak is taken as the proportion of C-C present. The value obtained by dividing the proportion of C=O present by the proportion of C-C present is taken as C-C / C=O.

[0058] Further, in the surface having a proportion of C=O present of 1 to 5%, from the viewpoint of cold water solubility, the proportion of carbon present in all elements obtained by XPS measurement is preferably 50 to 70%, the proportion of oxygen present is preferably 20 to 35%, and the ratio of carbon to oxygen is preferably 1.5 to 3.5.

[0059] Here, the cold water solubility refers to the solubility in water at a temperature of 10°C.

[0060] In the XPS measurement, almost all kinds of elements can be measured, but in the present application, the result of the XPS measurement of the surface of the film is quantified for the measured carbon, nitrogen, oxygen, fluorine, sodium, silicon, phosphorus and sulfur (hereinafter, these all elements measured are sometimes referred to as all elements measured), and the proportion of the carbon element and the proportion of the oxygen element with respect to the total amount thereof are respectively taken as the existence proportion of carbon and the existence proportion of oxygen.

[0061] In addition, generally, in the case where the surface of the PVA film is subjected to the XPS measurement, the measured elements are caused by the PVA, the plasticizer as described later, the additive and the like. That is, depending on the kind of the plasticizer, the additive material and the like contained in the PVA film, elements other than the above-mentioned carbon, nitrogen, oxygen, fluorine, sodium, silicon, phosphorus and sulfur can also be measured, but in the present application, the proportion of the carbon element and the proportion of the oxygen element with respect to the total amount of the above-mentioned all elements measured are respectively taken as the existence proportion (%) of carbon and the existence proportion (%) of oxygen.

[0062] Further, the ratio of carbon to oxygen (hereinafter, sometimes simply referred to as C / O) means the value obtained by dividing the existence proportion of oxygen by the above-mentioned existence proportion of carbon.

[0063] In the case where the existence proportion of carbon is less than 50% or in the case where it exceeds 70%, both tend to decrease the cold water solubility. The existence proportion of carbon in all elements is more preferably 52.5 to 67.5%, and further preferably 55 to 65%.

[0064] In the case where the existence proportion of oxygen is less than 20%, it tends to decrease the cold water solubility, and in the case where it exceeds 35%, it tends to decrease the oxidation degradation resistance. The existence proportion of oxygen in all elements is more preferably 22.5 to 32.5%, and further preferably 25 to 30%.

[0065] Further, in the case where C / O is less than 1.5 or in the case where it exceeds 3.5, it tends to deteriorate the oxidation degradation resistance. C / O is more preferably 1.7 to 3.3, and further preferably 1.9 to 3.1.

[0066] In addition, in the case where the existence proportion of C=0 in the water-soluble film of the present application is 1 to 5% in one surface, the existence proportions of the elements other than carbon and oxygen, that is, nitrogen, fluorine, sodium, silicon, phosphorus, sulfur elements, are 0.1 to 30% in total.

[0067] In the water-soluble film of the present application, the existence proportion of C=0 in at least one surface of the surface is 1 to 5%, but it is further preferable to satisfy both of the following:

[0068] (1) From the viewpoint of the oxidation degradation resistance, C-C / C=0 of the surface is 10 to 50, and more preferably 10 to 20; and

[0069] (2) From the viewpoint of cold water solubility or resistance to oxidative degradation, the proportion of carbon present in all of the elements of the surface is 50 to 70%, and the proportion of oxygen present is 20 to 35%, and the ratio of carbon to oxygen (C / O) is 1.5 to 3.5.

[0070] In the present application, it is important to adjust the proportion of C=O present in the surface of the water-soluble film, and further, as necessary, the proportions of C-C / C=O, carbon present, oxygen present, C / O, within the above-mentioned ranges. With regard to the method, for example, the proportion present of C=O within the above-mentioned range can be adjusted by, for example, controlling the treatment conditions of UV treatment, ozone treatment, corona treatment, plasma treatment, and the like, and treating the surface of the film; or applying a liquid medicine containing a surfactant to the surface of the film; adding an appropriate surfactant to a PVA film; adjusting the humidity atmosphere during the process of volatilizing the solvent at the time of manufacturing the PVA film.

[0071] For example, as described later, if the drying temperature is increased or the humidity at the time of drying is decreased during the process of volatilizing the solvent, the proportion of C=O present tends to decrease, and thus the proportion of C=O present can be accurately controlled by appropriately adjusting the drying temperature and the humidity.

[0072] Further, in the case where the surface of the film is subjected to corona treatment, if the amount of corona discharge is increased, the proportion of C=O present tends to increase. This tendency is considered to be the same in other surface treatment methods such as UV treatment, ozone treatment, plasma treatment, and the like, and the proportion of C=O present can be adjusted by adjusting the amount of discharge in each treatment.

[0073] From the viewpoint of manufacturing cost, solvent treatment, and the like, it is preferable that the surface of the film be treated by a method such as UV treatment, ozone treatment, corona treatment, plasma treatment, and the like.

[0074] The total dissolution time when the water-soluble film of the present application is immersed in water at 10°C is 120 seconds or less. By having a total dissolution time of 120 seconds or less, it is possible to suitably use the film as a packaging film for pharmaceuticals and the like. The total dissolution time is preferably 90 seconds or less, more preferably 60 seconds or less, and further preferably 45 seconds or less. On the other hand, the lower limit of the total dissolution time is not particularly limited, and in a water-soluble film having a total dissolution time that is too short, there tends to be an increase in the occurrence of blocking between films, a decrease in film strength, and the like, caused by moisture absorption from the atmosphere. Therefore, the total dissolution time is preferably 5 seconds or more, more preferably 10 seconds or more, further preferably 15 seconds or more, and particularly preferably 20 seconds or more.

[0075] The total dissolution time when the water-soluble film is immersed in water at 10°C can be measured as follows. In the total dissolution time measurement, deionized water was used as the water.

[0076] <1> The water-soluble film was left in a constant temperature and humidity chamber adjusted to 20°C - 65% RH for 16 hours or more to adjust the humidity.

[0077] <2> After cutting a 40 mm long by 35 mm wide rectangle from the humidity-adjusted water-soluble film, the sample was fixed between two 50 mm by 50 mm plastic plates with a 35 mm long by 23 mm wide rectangular opening in the length direction of the sample and the opening in the approximate center of the width direction of the sample.

[0078] <3> 300 mL of deionized water was added to a 500 mL beaker, and the water was stirred at 280 rpm using a magnetic stirrer with a 3 cm long rod, and the water temperature was adjusted to 10°C.

[0079] <4> While taking care not to contact the rod of the magnetic stirrer, the sample fixed to the plastic plates in <2> above was completely immersed in the deionized water in the beaker.

[0080] <5> The time from the start of immersion in the deionized water until the sample pieces dispersed in the deionized water were completely gone as observed with the naked eye was measured.

[0081] The complete dissolution time measured by the above method depends on the thickness of the sample, but in this specification, the complete dissolution of the sample of the above size is set as the complete dissolution time regardless of the thickness.

[0082] <Polyvinyl alcohol resin>

[0083] The water-soluble film of the present application contains PVA. As the PVA, a polymer produced by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester monomer can be used. As the vinyl ester monomer, for example, vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl 2,2-dimethylpropionate, and vinyl versatate, etc. can be mentioned, among which, vinyl acetate is preferred.

[0084] The above vinyl ester polymer is preferably a polymer obtained by using only one or two or more kinds of vinyl ester monomers as the monomer, and more preferably a polymer obtained by using only one kind of vinyl ester monomer as the monomer. It can be a copolymer of one or two or more kinds of vinyl ester monomers and other monomers copolymerizable therewith.

[0085] As other monomers copolymerizable with such a vinyl ester monomer, for example, there can be mentioned ethylene; olefins having 3 to 30 carbon atoms such as propylene, 1-butene, isobutene, and the like; acrylic acid or a salt thereof; acrylic esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, and the like; methacrylic acid or a salt thereof; methacrylic esters such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, and the like; acrylamide derivatives such as acrylamide, N-methyl acrylamide, N-ethyl acrylamide, N,N-dimethyl acrylamide, diacetone acrylamide, acrylamidopropyl sulfonic acid or a salt thereof, dimethylaminopropyl acrylamide or a salt thereof, N-hydroxymethyl acrylamide or a derivative thereof, and the like; methacrylamide derivatives such as methacrylamide, N-methyl methacrylamide, N-ethyl methacrylamide, methacrylamidopropyl sulfonic acid or a salt thereof, dimethylaminopropyl methacrylamide or a salt thereof, N-hydroxymethyl methacrylamide or a derivative thereof, and the like; N-vinyl amides such as N-vinyl formamide, N-vinyl acetamide, N-vinyl pyrrolidone, and the like; vinyl ethers such as methyl vinyl ether, vinyl ethyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, octadecyl vinyl ether, and the like; vinyl cyanides such as acrylonitrile, methacrylonitrile, and the like; halogenated ethylenes such as chloroethylene, vinylidene chloride, fluoroethylene, vinylidene fluoride, and the like; propenyl compounds such as allyl acetate, allyl chloride, and the like; maleic acid or a salt, ester, or anhydride thereof; itaconic acid or a salt, ester, or anhydride thereof; vinyl silyl compounds such as vinyltrimethoxysilane, and the like; isopropenyl acetate, and the like. The above-mentioned vinyl ester polymer can have structural units derived from one or more than two of these other monomers.

[0086] From the viewpoint of water solubility and film strength of the obtained water-soluble film, the proportion of structural units derived from the above-mentioned other monomers in the above-mentioned vinyl ester polymer is preferably 15 mol% or less, more preferably 5 mol% or less, based on the total number of moles of all structural units constituting the vinyl ester polymer.

[0087] From the viewpoint of the strength of the film, the polymerization degree of the PVA is preferably 200 or more, more preferably 300 or more, and further preferably 500 or more. On the other hand, from the viewpoint of the productivity of the PVA, the productivity of the water-soluble film, and the like, the polymerization degree is preferably 8,000 or less, more preferably 5,000 or less, and further preferably 3,000 or less. Here, the polymerization degree refers to the average polymerization degree measured according to the description of JIS K 6726-1994, and the limiting viscosity [η] (unit: deciliter / g) measured in water at 30°C after resaponification and purification of the PVA is calculated from the following formula.

[0088] Po = ([η] x 10 4 / 8.29) (1 / 0.62)

[0089] In the present application, the saponification degree of the PVA is preferably 64 to 99.99 mol%. By adjusting the saponification degree within this range, it is easy to balance the water-solubility and the mechanical physical properties of the film. The saponification degree is more preferably 70 mol% or more, and further preferably 75 mol% or more. On the other hand, the saponification degree is more preferably 99.95 mol% or less, and further preferably 99.92 mol% or less. Here, the saponification degree of the PVA refers to the proportion (mol%) of the number of moles of the vinyl alcohol unit with respect to the total number of moles of the structural unit (typically, a vinyl ester monomer unit) of the PVA that can be converted into the vinyl alcohol unit by saponification. The saponification degree of the PVA can be measured in accordance with the description of JIS K 6726-1994.

[0090] The water-soluble film in the present application can use one PVA as the PVA, or two or more kinds of PVA having different polymerization degrees, saponification degrees, or modification degrees, or the like can be mixedly used.

[0091] In the present application, the content ratio of the PVA in the water-soluble film is not particularly limited, and is preferably 50 mass% or more, more preferably 80 mass% or more, and further preferably 85 mass% or more.

[0092] <Plasticizer>

[0093] The water-soluble film of the present application is hard in the absence of a plasticizer, and the mechanical physical properties such as impact strength, processability during secondary processing, and the like can sometimes become problematic. In order to prevent these problems, it is preferable to contain a plasticizer in the water-soluble film of the present application. As the preferable plasticizer, polyhydric alcohols can be given, and specifically, for example, polyhydric alcohols such as ethylene glycol, glycerol, diglycerol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane, sorbitol, and the like can be given. These plasticizers can be used singly or in combination of two or more. Among these plasticizers, from the viewpoint of not easily exuding to the surface of the film and the like, ethylene glycol or glycerol is preferable, and glycerol is more preferable.

[0094] The content of the plasticizer in the water-soluble film is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more, relative to 100 parts by mass of the PVA contained in the water-soluble film. Also, the amount of the plasticizer is preferably 70 parts by mass or less, more preferably 50 parts by mass or less, and further preferably 40 parts by mass or less. If the amount of the plasticizer is less than 1 part by mass, the improvement effect on the mechanical physical properties such as impact strength can sometimes be insufficient. On the other hand, if the content exceeds 70 parts by mass, the film becomes excessively soft and the handleability can sometimes be reduced, or exudation to the surface of the film can occur.

[0095] <Starch / Water-soluble Polymer>

[0096] In order to impart mechanical strength to the water-soluble film, maintain the moisture resistance during handling of the film, or adjust the speed of softening caused by absorption of water during dissolution of the film, and the like, a starch and / or a water-soluble polymer other than PVA can be contained in the film of the present application.

[0097] As the starch, for example, natural starches such as corn starch, potato starch, sweet potato starch, wheat starch, rice starch, tapioca starch, sago starch, and the like; processed starches to which etherification processing, esterification processing, oxidation processing, and the like have been applied, and the like can be given, and processed starches are particularly preferable.

[0098] The content of the starch in the water-soluble 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 the PVA. If the amount of the starch is more than 15 parts by mass, the processability can possibly be deteriorated.

[0099] As the water-soluble polymer other than PVA, for example, dextrin, gelatin, animal glue, casein, shellac, gum arabic, polyacrylamide, 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, sodium alginate, and the like can be given.

[0100] The content of the water-soluble polymer other than PVA in the water-soluble 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. If the content is more than 15 parts by mass, the water-solubility of the water-soluble film can be insufficient.

[0101] <Surfactant>

[0102] In the film formation of the water-soluble film, a surfactant is preferably added to the water-soluble film from the viewpoint of improving the operability thereof and the releasability of the self-film device at the time of manufacturing the water-soluble film. Furthermore, by adding an appropriate surfactant to the water-soluble film, the presence ratio of C=O on the surface of the water-soluble film of the present application and further the presence ratio of C-C / C=O, carbon, oxygen, C / O, as needed, can be set within a desired range. As the kind of surfactant, anionic surfactants, nonionic surfactants, and the like can be exemplified.

[0103] As the anionic surfactant, for example, carboxylic acid types such as potassium laurate; sulfates such as octyl sulfate; sulfonic acid types such as dodecylbenzenesulfonate; and the like can be exemplified.

[0104] As the nonionic surfactant, for example, alkyl ether types such as polyoxyethylene lauryl ether, polyoxyethylene oleyl ether; alkyl phenyl ether types such as polyoxyethylene octyl phenyl ether; alkyl ester types such as polyoxyethylene laurate; alkyl amine types such as polyethylene glycol dodecanamide; alkyl amide types such as polyoxyethylene lauramide; polypropylene glycol ether types such as polyoxyethylene polyoxypropylene ether; alkanolamide types such as lauramide diethanol, oleoyl diethanolamine; and propenyl phenyl ether types such as polyoxyalkylene propenyl phenyl ether; and the like can be exemplified.

[0105] The surfactant can be used singly or in combination of two or more.

[0106] The surfactant in the present application has a tendency to aggregate on the surface of the film rather than to be uniformly dispersed in the water-soluble film, and the effect is obtained by a small amount of addition, and thus is preferable. Therefore, a surfactant having an appropriate affinity with PVA is preferably selected. A surfactant having too high affinity with PVA has a tendency to be uniformly dispersed, and a surfactant having too low affinity with PVA forms droplets in the film by phase separation, and easily reduces the transparency of the film or easily exudes to the surface of the film.

[0107] Furthermore, a surfactant having an appropriate affinity with PVA tends to easily aggregate on the surface of the PVA film at the time of film formation. Therefore, the presence ratio of C=O on the surface of the film and the like can be controlled by adjusting the kind and amount of the surfactant.

[0108] As an example of the surfactant having an appropriate affinity with PVA, a nonionic surfactant is preferable, and more preferably an alkanolamide-type surfactant, and further preferably a dialkanolamide of a fatty acid (e.g., a saturated or unsaturated fatty acid having 8 to 30 carbon atoms, etc.) (e.g., diethanolamide, etc.). Also, a dialkanolamide containing a small amount of a corresponding alkanolamine is easy to adjust the dispersion state of the surfactant in the water-soluble film, and thus is suitable for use.

[0109] From the viewpoints of the film-forming property and the peelability of the obtained film, the content of the surfactant in the water-soluble film is preferably 0.01 parts by mass or more, more preferably 0.02 parts by mass or more, and further preferably 0.05 parts by mass or more, relative to 100 parts by mass of PVA. On the other hand, from the viewpoints of bleeding to the surface of the obtained film and aggregation of the surfactant, the content of the surfactant is preferably 10 parts by mass or less, more preferably 1 part by mass or less, further preferably 0.5 parts by mass or less, and particularly preferably 0.3 parts by mass or less. If the content is less than 0.01 parts by mass, the film-forming property tends to be poor. Also, the peelability of a self-film device at the time of manufacturing the PVA film tends to be reduced, or agglomerates tend to be generated between the films. On the other hand, if the content is more than 10 parts by mass, bleeding to the surface of the film and deterioration of the appearance of the film due to aggregation of the surfactant tend to occur.

[0110] <Other Components>

[0111] The water-soluble film of the present application can contain, in addition to the plasticizer, the starch, the water-soluble polymer other than PVA, and the surfactant, components such as moisture, an antioxidant, an ultraviolet absorber, a lubricant, a crosslinking agent, a coloring agent, a filler, a preservative, a mold inhibitor, and other polymer compounds, within a range not impairing the effects of the present application. The total of the respective amounts of PVA, the plasticizer, the starch, the water-soluble polymer other than PVA, and the surfactant is preferably in the range of 60 to 100% by mass, more preferably in the range of 80 to 100% by mass, and further preferably in the range of 90 to 100% by mass, relative to the total mass of the water-soluble film of the present application.

[0112] From the viewpoint of the secondary processability of the obtained film, the thickness of the water-soluble film of the present application 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. Also, from the viewpoint of the mechanical strength of the water-soluble film, the thickness of the water-soluble film 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. In addition, the thickness of the water-soluble film can be measured at any 10 points (for example, at any 10 points on a straight line drawn along the length direction of the PVA film) and the average value thereof can be taken as the thickness of the water-soluble film.

[0113] <Method for producing water-soluble film>

[0114] In the present application, the method for producing the water-soluble film is not particularly limited, and the film can be produced by any method, such as a method in which a film-forming raw solution in which a solvent, an additive, or the like is added to PVA and homogenized is cast onto a support such as a metal roll or a metal belt, heated to remove the solvent, and cured to form a film; a wet film-forming method (discharge into a poor solvent); a dry-wet film-forming method; a gel film-forming method (a method in which a film-forming raw solution is temporarily cooled and gelled, and then the solvent is extracted and removed to obtain a PVA film); or a combination thereof; a melt extrusion film-forming method in which a film-forming raw solution obtained using an extruder or the like is extruded from a T die or the like to produce a film; or a blow molding method. Among these, the cast film-forming method and the melt extrusion film-forming method are preferable because they can produce a homogeneous film at a high production rate. Hereinafter, the cast film-forming method or the melt extrusion film-forming method for producing the water-soluble film will be described.

[0115] In the case where the water-soluble film is produced by the cast film-forming method or the melt extrusion film-forming method, the above-described film-forming raw solution is cast onto a support such as a metal roll or a metal belt in a film shape, heated to remove the solvent, and cured to form a film. The cured film is peeled from the support, dried as necessary by a drying roll, a drying furnace, or the like, further heat-treated as necessary, and wound, whereby a long water-soluble film in a roll shape can be obtained.

[0116] The concentration of volatile components of the above-described film-forming raw solution (the concentration of volatile components such as a solvent removed due to volatilization or evaporation at the time of film formation) is preferably in the range of 50 to 90% by mass, and more preferably in the range of 55 to 80% by mass. If the concentration of volatile components is less than 50% by mass, the viscosity of the film-forming raw solution becomes high, and sometimes it is difficult to produce a film. On the other hand, if the concentration of volatile components exceeds 90% by mass, the viscosity becomes low and the uniformity of the thickness of the obtained film is easily impaired.

[0117] Herein, the "volatile component concentration" in the present specification means the concentration of volatile components calculated from the following formula.

[0118] Volatile matter rate of the film forming solution (mass %) = {(Wa - Wb) / Wa} x 100

[0119] (In the formula, Wa represents the mass (g) of the film forming solution, and Wb represents the mass (g) of the film forming solution dried for 16 hours at 105°C of Wa (g).)

[0120] The method of adjusting the film forming solution is not particularly limited, and for example, a method in which PVA and additives such as a plasticizer, a surfactant, and the like are dissolved in a dissolving tank or the like; a method in which PVA in a water-containing state is melt-kneaded using a single screw or a twin screw extruder, and melt-kneaded together with a plasticizer, a surfactant, and the like; and the like can be given.

[0121] The film of the film forming solution that is slurred onto the support is heated and dried on the support and in the subsequent drying step to be solidified, but the drying conditions at this time greatly affect the surface state of the film. For example, if the drying temperature is set to a high temperature, the drying speed becomes fast, and thus the surfactant is not easily aggregated on the surface of the film, and the existence ratio of the carbonyl group in the total carbon bond on the surface of the film and the like are affected. Also, if the humidity of the atmosphere at the time of drying the film of the film forming solution is lowered, the hydrophobic group tends to be easily aggregated on the surface of the film, and on the contrary, in the case where the humidity is high, the hydrophilic group tends to be easily aggregated.

[0122] Therefore, adjusting the drying conditions at the time of film formation is also one of the methods of controlling the existence ratio of C=O on the surface of the film and the like.

[0123] The drying conditions at the time of film formation affect the production speed of the film, and it is possible that the use of raw materials such as a surfactant will be limited. Therefore, in order to make the existence ratio of C=O on the surface of the film within the range of the present application, it is preferable to not only adjust the drying conditions at the time of film formation, but also to use a method of performing surface modification to the manufactured film as described later in combination.

[0124] The surface temperature of the first drying roller or the first drying belt (hereinafter, sometimes referred to as the first drying roller or the like) that is the support for the film forming solution to be slurred is preferably 50 to 110°C. In the case where the surface temperature is less than 50°C, the water solubility and the productivity of the film tend to be lowered. In the case where it exceeds 110°C, film surface abnormalities such as bubbling tend to easily occur, and the crystallinity tends to be lowered and the mechanical strength of the film tends to be lowered. The above-mentioned surface temperature is more preferably 60 to 105°C.

[0125] It is possible to uniformly blow hot air having a wind speed of 1 to 10 m / sec to the entire area of the non-contact surface side of the film of the film forming solution while heating the film of the film forming solution on the first drying roller or the like, and adjust the drying speed. From the viewpoints of the drying efficiency, the uniformity of drying, and the like, the temperature of the hot air blown to the non-contact surface side is preferably 50 to 150°C, and more preferably 70 to 120°C.

[0126] From the viewpoint of easily adjusting the proportion of the presence of C=0 on the surface of the film within the range of the present application, the moisture content in the hot air is preferably 4 to 90 g / m 3 More preferably, 5 to 70 g / m 3 Further preferably, 6 to 50 g / m 3 .

[0127] The film peeled from the first drying roll or the like is preferably dried to a volatile matter content of 5 to 50 mass% on a subsequent support (hereinafter, sometimes referred to as a drying roll or the like, and in the case of two or more, sometimes referred to as a second drying roll, a third drying roll, or a second drying belt, a third drying belt, in order). After drying to a volatile matter content within the preferable range, peeling is performed, and further drying is performed as necessary. The drying method is not particularly limited, and in addition to a method in which the film is brought into contact with a drying roll or the like, a method in which a drying oven is used can be given. In the case where drying is performed using a plurality of drying rolls or the like, one side surface and the other side surface of the film are brought into contact with the second drying roll alternately, which homogenizes both surfaces, and is therefore preferable. For example, the number of the second drying roll and the like after the first drying roll is preferably three or more, more preferably four or more, and further preferably five to thirty. The temperature after the drying oven, the second drying roll, or the second drying belt is preferably 40°C or higher and 110°C or lower. The upper limit of the temperature after the drying oven, the second drying roll, or the second drying belt is more preferably 100°C, and more preferably 95°C. If the temperature after the drying oven, the second drying roll, or the second drying belt is too high, the cold water solubility of the film can decrease. On the other hand, the lower limit of the temperature after the drying oven, the second drying roll, or the second drying belt is more preferably 45°C, and further preferably 50°C. If the temperature after the drying oven, the second drying roll, or the second drying belt is too low, the mechanical strength of the film can decrease.

[0128] The obtained water-soluble film can be further subjected to heat treatment as necessary. By performing heat treatment, the strength, water solubility, and the like of the film can be adjusted. The temperature of the heat treatment is preferably 60°C or higher and 135°C or lower. The heat treatment temperature is more preferably 130°C or lower. If the heat treatment temperature is too high, the amount of heat applied is too much, and the cold water solubility can decrease.

[0129] The water-soluble film thus produced is subjected to humidity conditioning, cutting of both end portions (ear portions), and the like as necessary, wound in a roll shape on a cylindrical core, and subjected to moisture-proof packaging to become a product.

[0130] The volatile matter content of the water-soluble film finally obtained by the above series of processes is preferably within the range of 1 to 5 mass%, and more preferably within the range of 2 to 4 mass%.

[0131] As described above, the water-soluble film subjected to surface modification is one of the preferred embodiments of the present application. The method of surface modification is not particularly limited, and is preferably any one of ultraviolet treatment, ozone treatment, corona treatment, and plasma treatment, among which corona treatment is more preferred because of its superior treatment speed, safety, and ease of adjusting the degree of treatment.

[0132] From the viewpoint of resistance to oxidative degradation and damage such as discoloration and perforation of the film, the conditions of corona treatment are preferably in the range of 150 to 400 W-min / m 2 , more preferably in the range of 180 to 350 W-min / m 2 , and further preferably in the range of 200 to 300 W-min / m 2 . In addition, the discharge amount is calculated by the following formula (1).

[0133] Discharge amount (W-min / m 2 ) = output (W / m) / treatment speed (m / min) (1)

[0134] <Use>

[0135] The water-soluble film of the present application has excellent balance between cold water solubility and resistance to oxidative degradation, and can be suitably used for various uses of water-soluble films. As such water-soluble films, for example, there can be mentioned a film for packaging a medicament, a base film for hydraulic transfer, a base film for embroidery, a release film for artificial marble molding, a film for packaging seeds, and a film for a bag for storing dirt, and the like. Among these, from the viewpoint of more significantly exerting the effects of the present application, the water-soluble film of the present application is preferably used as a film for packaging a medicament, and more preferably as a film for packaging a medicament having oxidizing properties.

[0136] As the kind of medicament in the case where the water-soluble film of the present application is used as a film for packaging a medicament, there can be mentioned a pesticide, a detergent (including a bleaching agent), a disinfectant, and the like. The physical properties of the medicament are not particularly limited, and can be acidic, neutral, or alkaline. Furthermore, a boron-containing compound can be contained in the medicament. The shape of the medicament can be any one of powder, block, gel, and liquid. The packaging method is not particularly limited, and is preferably a method of packaging (preferably, sealing) the medicament in unit packages. By packaging the medicament using the film of the present application as a film for packaging a medicament, a package of the present application can be obtained.

[0137] Example

[0138] Hereinafter, the present application will be specifically described by way of examples, but the present application is not limited by the following examples in any way. In addition, the evaluation items and methods employed in the following examples and comparative examples are as follows.

[0139] (1) Measurement conditions of X-ray photoelectron spectroscopy (XPS)

[0140] The film was cut into a size of 5 mm x 5 mm and disposed on a measurement base via a conductive double-sided tape. At the time of measurement, both sides of the film were measured. As for XPS, each sample was measured under the following measurement conditions.

[0141] Measurement device: Ohi Quantera SXM (ULVAX-PHI. INC.)

[0142] Analysis software: Multi Pack vet9.0 (ULVAX-PHI. INC.)

[0143] X-ray source: Monochromatic AlKα (1486.6 eV)

[0144] X-ray beam diameter: 100 μmφ (25 W, 15 kV)

[0145] Measurement range: 100 μm x 300 μm

[0146] Signal capture angle: 45°

[0147] Charging neutralization conditions: Neutralizing electron gun, Ar + Ion gun

[0148] Vacuum degree: 1 x 10 -6 Pa

[0149] In addition, in the following examples and comparative examples, the following elements were measured.

[0150] Measured elements: C1s, N1s, O1s, F1s, Na1s, Si2p, P2p, S2p

[0151] The obtained spectrum was analyzed to find the existence ratio of C1s and O1s.

[0152] Further, the obtained C1s peak was automatically fitted using the above analysis software to find the existence ratio of the bonding state of carbon C-C and C=O.

[0153] (2) Evaluation of cold water solubility (total dissolution time of water-soluble film in water at 10°C)

[0154] The total dissolution time of the water-soluble film in deionized water at 10°C was found by the method.

[0155] (3) Evaluation of resistance to oxidative degradation

[0156] Two pieces of a water-soluble film of 11 cm x 16 cm were cut out, and a bag (10 cm x 15 cm) was prepared by sealing three sides (sealing width: 5 mm). After 35 g of a liquid bleach containing sodium percarbonate as a main component was put in the bag, the remaining one side was heat-sealed to seal, thereby obtaining a package having a medicine inside. The outside of the obtained package was wrapped with a film in which polyethylene was laminated on the surface of aluminum (hereinafter, referred to as an aluminum-laminated film), and heat-sealed to seal, thereby preparing a double-layered package.

[0157] As an acceleration test for a long-term storage test, the above double-layered package was left in a thermostat at 40°C for 3 weeks, and the coloring of the water-soluble film was evaluated by the naked eye according to the following standards.

[0158] A: No coloring was observed

[0159] B: Slightly colored yellow

[0160] C: Clearly colored yellow

[0161] <Example 1>

[0162] A film-forming solution having a volatile matter rate of 60 mass% was prepared by adjusting a PVA (saponification degree: 88 mol%, polymerization degree: 1700) obtained by saponifying polyvinyl acetate, 100 parts by mass, glycerin as a plasticizer, 20 parts by mass, lauryl amide diethanol (containing 10 mass% of diethanolamine laurate as an impurity) as a surfactant, 0.05 parts by mass, and water. The liquid obtained by filtering the film-forming solution was discharged in a film shape on a first drying roll whose surface temperature was adjusted to 100°C, and the entire non-contact surface of the first drying roll was sprayed with hot air of 85°C having a moisture content of 24.9 g / m 3 2 at a speed of 5 m / sec and dried. Subsequently, the film of the film-forming solution was peeled from the first drying roll, and the other surface different from the surface in contact with the first drying roll was brought into contact with the surface of a subsequent first drying roll (hereinafter, referred to as a second drying roll) and dried. Thereafter, the film was dried in such a manner that one side surface and the other side surface of the film of the film-forming solution were brought into contact with six drying rolls including the second drying roll (hereinafter, referred to as a third drying roll, a fourth drying roll, and the last drying roll as a seventh drying roll) in turn alternately, thereby obtaining a film. The surface temperature of the second drying roll and the subsequent drying rolls was 90°C. The obtained film was further subjected to heat treatment by bringing both surfaces into contact with a plurality of heat treatment rolls having a surface temperature of 90°C for 30 seconds, and wound on a polyvinyl chloride pipe, thereby obtaining a water-soluble film (thickness: 35 μm, length [flow direction of the film]: 1200 m).

[0163] The results of measurement by XPS of both sides of the obtained water-soluble film were as follows: the proportion of the presence of carbonyl (C=0) in the total carbon bond of one film surface was 1.6%, the ratio of the proportion of the presence of carbonyl to the proportion of the presence of carbon-carbon single bond (C-C / C=0) was 29.5, the proportion of the presence of carbon among all elements was 70.8%, likewise, the proportion of the presence of oxygen was 28.3%, and the ratio of carbon to oxygen (C / O) was 2.5. Also, the proportion of the presence of carbonyl (C=0) in the total carbon bond of the other film surface was 1.3%, the ratio of the proportion of the presence of carbonyl to the proportion of the presence of carbon-carbon single bond (C-C / C=0) was 45.7, the proportion of the presence of carbon among all elements (C proportion of presence) was 73.3%, likewise, the proportion of the presence of oxygen (0 proportion of presence) was 24.7%, and the ratio of carbon to oxygen (C / O) was 3.0.

[0164] The total dissolution time (cold water solubility) of the film was 88 seconds, and the result of the evaluation of the resistance to oxidative degradation was A.

[0165] The composition of the film-forming solution, the film-forming conditions, the results of XPS analysis of the obtained water-soluble film, and the evaluation results are summarized in Table 1. In addition, the side in contact with the first drying roll was referred to as surface 1, and the side opposite thereto was referred to as surface 2.

[0166] <Example 2>

[0167] The PVA was changed to a methyl maleate (MA) modified PVA (saponification degree: 99 mol%, polymerization degree: 1700, MA modification degree: 5 mol%) obtained by saponifying polyvinyl acetate, and otherwise, a water-soluble film was obtained in the same manner as in Example 1. The results of XPS analysis of the water-soluble film, the total dissolution time (cold water solubility), and the result of the evaluation of the resistance to oxidative degradation are shown in Table 1.

[0168] <Examples 3 and 4>

[0169] A part of the film obtained in Example 2 was discharged, and both sides thereof were treated using a corona treatment device at 250 W minute / m 2 (Example 3) and 350 W minute / m 2 (Example 4), and then wound. The results of XPS analysis of the water-soluble film, the total dissolution time (cold water solubility), and the result of the evaluation of the resistance to oxidative degradation are shown in Table 1.

[0170] <Example 5>

[0171] The amount of the surfactant was set to 0.2 parts by mass, and otherwise, a water-soluble film was obtained in the same manner as in Example 1. The results of XPS analysis of the water-soluble film, the total dissolution time (cold water solubility), and the result of the evaluation of the resistance to oxidative degradation are shown in Table 1.

[0172] <Comparative Example 1>

[0173] A part of the film obtained in Example 1 was subjected to treatment on both sides using a corona treatment device under conditions of 410 W • min / m 2 , and then was wound up. The results of XPS analysis, full dissolution time (cold water solubility), and oxidative degradation resistance evaluation of the water-soluble film are shown in Table 1.

[0174] <Comparative Example 2>

[0175] The surfactant was changed to polyoxyethylene dodecyl ether (condensation degree of polyoxyethylene was in the range of 1 to 10 centered on 4), and otherwise, a water-soluble film was obtained in the same manner as in Example 1. The results of XPS analysis, full dissolution time (cold water solubility), and oxidative degradation resistance evaluation of the water-soluble film are shown in Table 1.

[0176] <Comparative Example 3>

[0177] The PVA was changed to PVA obtained by saponification of polyvinyl acetate (saponification degree was 99 mol%, and polymerization degree was 1700), and otherwise, a water-soluble film was obtained in the same manner as in Example 1. The results of XPS analysis, full dissolution time (cold water solubility), and oxidative degradation resistance evaluation of the water-soluble film are shown in Table 1.

[0178] <Comparative Example 4>

[0179] The surface temperature of the 1st drying roll was changed to 115°C, the moisture content contained in the hot air blown to the entire non-contact surface of the 1st drying roll was changed to 0.5 g / m 3 , and the surface temperature of the 2nd drying roll and the drying rolls subsequent thereto was changed to 115°C, and otherwise, a water-soluble film was obtained in the same manner as in Example 1. The results of XPS analysis, full dissolution time (cold water solubility), and oxidative degradation resistance evaluation of the water-soluble film are shown in Table 1.

[0180]

[0181] From the above results, it was found that the water-soluble film of the present application is excellent in the balance between cold water solubility and oxidative degradation resistance. Therefore, the water-soluble film of the present application can be suitably used for various uses of water-soluble films, such as a film for pharmaceutical packaging, a base film for hydraulic transfer, a base film for embroidery, a release film for artificial marble molding, a film for seed packaging, and a film for dirt storage bag, and the like. Among these, the water-soluble film of the present application is more suitably used as a film for pharmaceutical packaging, and in particular, can be used as a film for packaging of pesticides, detergents (including bleaching agents), and the like, which have oxidizing properties.

Claims

1. A water-soluble film comprising a polyvinyl alcohol resin and a surfactant, having on at least one side a surface having a carbonyl group content of 1 to 5% in total carbon bonds as determined by X-ray photoelectron spectrophotometry, and having a total solubility time in water at 10°C of less than 120 seconds, wherein the degree of saponification of the polyvinyl alcohol resin is 64 to 99.99 mol%, and the surfactant is selected from at least one of alkylamine, alkylamide, or alkanolamide surfactants.

2. The water-soluble film according to claim 1, wherein, On the surface of the total carbon bonds, the ratio of the carbon-carbon single bond ratio to the carbonyl group ratio (C-C / C=O), obtained further by X-ray photoelectron spectrophotometry, is 10 to 50.

3. The water-soluble film according to claim 1 or 2, wherein, On the surface of the total carbon bonds, the carbon content of carbon is 50% to 70% and the oxygen content is 20% to 35% of all elements as determined by X-ray photoelectron spectrophotometry, and the carbon to oxygen ratio (C / O) is 1.5 to 3.

5.

4. The water-soluble film according to claim 1 or 2, wherein, The surfaces in which the proportion of carbonyl groups in the total carbon bonds is present within the range are surface modified.

5. The water-soluble film according to claim 4, wherein, The surface modification is based on any one of the following methods: ultraviolet treatment, ozone treatment, corona treatment, and plasma treatment.

6. A packaging body, wherein, The water-soluble film according to any one of claims 1 to 5 contains a pharmaceutical agent.

7. The packaging body according to claim 6, wherein, The agent is a pesticide or detergent.

8. The packaging body according to claim 6 or 7, wherein, The medicine is in liquid form.

9. The packaging body according to claim 6 or 7, wherein, The agent is contained in a manner in which the presence of carbonyl groups in the total carbon bonds is 1 to 5% on the surface in contact with the agent.

Images