Patent Description:
In order to preserve the quality of foods and medications, it is necessary to block gases such as oxygen, nitrogen, carbon dioxide, and water vapor in the atmosphere and provide hermetic sealing. Among various types of resins, vinylidene chloride-based copolymer latexes are suitable for food and medication packaging applications because they display high barrier properties against water vapor and oxygen upon being applied onto a film.

In recent years, there has been demand for even higher gas barrier properties in such film applications. Although performing recoating of a latex so as to form a thicker barrier layer is effective for resolving this issue, conventional latexes have suffered from problems in terms of deterioration of coated surface external appearance and loss of transparency. Specifically, in a situation in which the surface tension of a latex water dispersion is not within an appropriate range, leveling failure may occur, an orange peel pattern may be formed during recoating, and foaming may occur in a film when shaping is performed at high temperature in order to shape a blister pack for a medication, for example.

A variety of studies have been conducted in light of the issues set forth above.

<CIT> discloses a latex comprising a vinylidene chloride copolymer obtainable by emulsion polymerizing <NUM> to <NUM> parts by mass of vinylidene chloride with <NUM> to <NUM> parts by mass of one or more other monomer(s) copolymerizable with vinylidene chloride, with the proviso that the total of vinylidene chloride and the other monomer(s) is <NUM> parts by mass, characterized in that the weight average molecular weight, Mw, of the copolymer is from <NUM>,<NUM> to <NUM>,<NUM>.

Patent Literature (PTL) <NUM> discloses compounding sodium dodecylbenzenesulfonate as an amphiphilic compound in an amount of <NUM> parts by mass relative to resin solid content when obtaining a vinylidene chloride copolymer latex by emulsion polymerization. However, foaming occurs during shaping and recoatability is unsatisfactory because a large amount of this amphiphilic compound is added with the aim of causing suitable progress of polymerization, and thus the effects in the present application are not achieved.

PTL <NUM> discloses the inclusion of a specific non-ionic amphiphilic compound as a defoamer in an amount of from <NUM> parts by mass to <NUM> parts by mass in a vinylidene chloride-based copolymer latex. However, coatability is unsatisfactory because too little of the compound is added.

PTL <NUM> discloses that in multilayer coating of a substrate with a polymer that includes <NUM> weight% or more of an anionic amphiphilic substance among all surfactant, the multilayer coating is performed with a vinylidene chloride-based copolymer that includes <NUM> weight% or more of a non-ionic amphiphilic substance interposed between layers. However, foaming occurs during shaping as a result of the water content and crystallinity being unsatisfactory, and thus the effects in the present application are not achieved.

PTL <NUM> discloses an example in which a hydroxyl group-containing radical polymerizable monomer is used and in which sodium dodecylsulfonate is used, but foaming occurs during shaping as a result of the water content being unsatisfactory, and thus the effects in the present application are not achieved.

Accordingly, an object of the present disclosure is to provide a water dispersion that has excellent coatability in recoating and that yields a uniform coating film without leveling failure, orange peel patterning, or the occurrence of foaming during film shaping.

As a result of diligent research aimed at solving problems such as set forth above, it was discovered that excellent coatability in recoating can be achieved and that a uniform coating film can be obtained without leveling failure, orange peel patterning, or foaming by compounding a specific amount of a specific amphiphilic compound with a halogenated vinyl polymer water dispersion.

Specifically, primary features of the present disclosure are as follows. A multilayer film comprising a layer obtained by applying a halogenated vinyl polymer water dispersion onto a base film formed of a polymer differing from the halogenated vinyl polymer,.

The halogenated vinyl polymer water dispersion may further comprise sodium pyrophosphate.

The halogenated vinyl polymer water dispersion may comprise more than <NUM> mass% of a nonionic amphiphilic compound relative to <NUM> mass% of resin solid content contained in the water dispersion.

The base film is preferably made of polyvinyl chloride.

The multilayer film may comprise two or more layers of the layer obtained by applying the halogenated vinyl polymer water dispersion, wherein at least one layer among the layers obtained by applying the halogenated vinyl polymer water dispersion may have a thickness of <NUM> or more, or even a thickness of <NUM> or more.

The multilayer film may have a water content of <NUM> mass% or less.

The the layer obtained by applying the halogenated vinyl polymer water dispersion optionally has a relative crystallinity of <NUM> or more as measured by a Fourier transform infrared spectrophotometer.

The invention also provides a blister pack for a medication comprising the multilayer film.

As a result of having the configuration set forth above, a halogenated vinyl polymer water dispersion according to the present disclosure has excellent coatability in recoating and can form a uniform coating film without leveling failure, orange peel patterning, or the occurrence of foaming during film shaping.

The following provides a detailed description of an embodiment of the present disclosure (hereinafter, referred to simply as the "present embodiment").

A halogenated vinyl polymer water dispersion of the present embodiment contains a halogenated vinyl polymer and also contains <NUM> mass% or more and less than <NUM> mass% or less, relative to <NUM> mass% of resin solid content, of an anionic amphiphilic compound that is sodium dodecylbenzene sulfonate. As a result, coatability in recoating is excellent, leveling failure and orange peel patterning have a low tendency to occur, and a uniform coating film can be obtained without the occurrence of foaming during film shaping.

The halogenated vinyl polymer water dispersion of the present embodiment may further contain more than <NUM> mass% of a non-ionic amphiphilic compound relative to <NUM> mass% of resin solid content.

The halogenated vinyl polymer water dispersion is preferably obtained through emulsion polymerization of monomer including at least a halogenated vinyl.

Note that in the present specification, the halogenated vinyl polymer water dispersion may also be referred to simply as a water dispersion. Also note that the resin solid content in the water dispersion of the present embodiment is the total amount of all solid resin contained in the water dispersion and may consist of just the halogenated vinyl polymer or may also include another resin component.

In the multilayer film of the present invention the halogenated vinyl polymer water dispersion comprises a vinylidene chloride polymer.

A halogenated vinyl polymer includes at least structural units derived from a halogenated vinyl and may further include a monomer that is copolymerizable with the halogenated vinyl.

Note that in the present specification, a monomer that is copolymerizable with the halogenated vinyl may also be referred to as a comonomer.

A halogenated vinyl may be a compound having a structure in which at least one hydrogen atom of a vinyl group has been replaced by a halogen atom. For example, a halogenated vinyl may be a compound in which one hydrogen atom of an ethylene structure has been replaced by a halogen atom or in which a plurality of hydrogen atoms of an ethylene structure have been replaced by halogen atoms. The halogen atom may be fluorine, chlorine, or bromine.

A halogenated vinyl may be a chlorinated monomer such as vinyl chloride, vinylidene chloride, <NUM>,<NUM>-dichloroethylene, trichloroethylene, or tetrachloroethylene, a fluorinated monomer such as vinyl fluoride, vinylidene fluoride, trifluoroethylene, or fluoroethylene, a brominated monomer such as vinyl bromide, vinylidene bromide, tribromoethylene, or tetrabromoethylene, or the like, for example. One of these halogenated vinyls may be selected for use, or two or more of these halogenated vinyls may be selected for use. Of these halogenated vinyls, chlorinated monomers excel in terms of ease of polymerization, and vinylidene chloride, in particular, excels in terms of barrier functionality.

Examples of monomers that are copolymerizable with the halogenated vinyl include acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, <NUM>-ethylhexyl acrylate, and <NUM>-hydroxyethyl acrylate, methacrylic acid esters such as methyl methacrylate and glycidyl methacrylate, nitriles such as acrylonitrile and methacrylonitrile, and unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, and maleic acid. One of these comonomers may be selected for use, or two or more of these comonomers may be selected for use. Of these comonomers, acrylic acid esters, methacrylic acid esters, methacrylonitrile, acrylonitrile, and acrylic acid are preferable, methyl acrylate, methyl methacrylate, methacrylonitrile, and acrylic acid are more preferable, and methyl acrylate and acrylic acid, in particular, are preferable in terms of flexibility of a coating film.

The halogenated vinyl polymer is preferably a copolymer including <NUM> mass% or more of structural units derived from a halogenated vinyl (for example, halogenated ethylene) relative to <NUM> mass% of the halogenated vinyl polymer. Barrier properties and film formability are excellent when the mass ratio of structural units derived from a halogenated vinyl (for example, halogenated ethylene) is within this range. This mass ratio is more preferably <NUM> mass% or more, even more preferably <NUM> mass% or more, even more preferably <NUM> mass% or more, even more preferably <NUM> mass% or more, and particularly preferably <NUM> mass% or more. Moreover, from a viewpoint of good film formability being displayed, this mass ratio is preferably <NUM> mass% or less, more preferably <NUM> mass% or less, and particularly preferably <NUM> mass% or less.

In terms of the mass ratio of the halogenated vinyl polymer in the water dispersion of the present embodiment, it is preferable that <NUM> mass% or more of the halogenated vinyl polymer as solid content is contained from a viewpoint of coatability, with <NUM> mass% or more being more preferable, <NUM> mass% or more being even more preferable, <NUM> mass% or more being even more preferable, and <NUM> mass% or more being particularly preferable from a viewpoint of even better coatability. Moreover, a mass ratio of <NUM> mass% or less is preferable, <NUM> mass% or less is more preferable, <NUM> mass% or less is even more preferable, and <NUM> mass% or less is particularly preferable.

The mass ratio of the halogenated vinyl polymer is a value that is measured by mass loss on drying and is measured by the following method. The mass ratio is measured using a SMART System <NUM> produced by CEM Corporation by dripping <NUM> to <NUM> of the water dispersion (for example, a latex) onto a glass fiber pad using a dropper, heating the water dispersion with a power of <NUM>%, and then calculating the solid content (mass%) by: (dry mass/mass of water dispersion) × <NUM>.

The halogenated vinyl polymer preferably has a particulate form in the water dispersion of the present embodiment.

The average particle diameter of the halogenated vinyl polymer is preferably <NUM> or more, more preferably <NUM> or more, even more preferably <NUM> or more, and particularly preferably <NUM> or more from a viewpoint of giving excellent surface smoothness when applied in the form of a film. Moreover, the average particle diameter is preferably <NUM> or less, more preferably <NUM> or less, and even more preferably <NUM> or less from a viewpoint of obtaining a good film.

The average particle diameter is a value that is measured by dynamic light scattering and is measured by the following method. The average particle diameter is measured by dispensing <NUM> cc to <NUM> cc of the halogenated vinyl polymer water dispersion that has been diluted by a factor of <NUM> with pure water into a glass cell (Cent Tube STS-<NUM> produced by Maruemu Corporation) and then performing measurement thereof by dynamic light scattering in an FPAR-<NUM> produced by Otsuka Electronics Co.

In the multilayer film of the present invention the anionic amphiphilic compound is sodium dodecylbenzene sulfonate.

An anionic amphiphilic compound is an amphiphilic compound that is ionized and displays anionic nature upon being dissolved in water. In the present specification, the term anionic refers to an amphiphilic substance in which a hydrophilic group portion thereof is ionized to form a negative ion in water as measured by H-NMR. Moreover, the term non-ionic refers to an amphiphilic substance having a hydroxyl group or ether bond in the structure thereof that does not undergo ion dissociation in water as measured by H-NMR.

The hydrophilicity index of the anionic amphiphilic compound is less than <NUM>.

An amphiphilic compound displays a suitable degree of hydrophobicity as a result of having a small hydrophilicity index. Consequently, the amphiphilic compound modifies the surface of the halogenated vinyl polymer (for example, particle surfaces) and has good compatibility with the halogenated vinyl polymer during drying. This causes the amphiphilic compound to be taken into the particles during drying, and enables formation of a coating film without bleeding at the surface. As a result, unevenness of surface tension has a low tendency to arise, and leveling failure has a low tendency to occur during recoating. Moreover, due to low water retention, evaporation of water in a film during drying can be promoted, and the water content in a formed coating film can be reduced, which makes it possible to inhibit foaming during film shaping. A lower hydrophilicity index makes it easier to obtain the effects described above, and thus a hydrophilicity index of <NUM> or less is preferable, and a hydrophilicity index of <NUM> or less is more preferable. Although no specific lower limit is set, the hydrophilicity index is preferably <NUM> or more, more preferably <NUM> or more, even more preferably <NUM> or more, and particularly preferably <NUM> or more when taking into account solubility in water of the amphiphilic compound and affinity thereof with the halogenated vinyl polymer.

The hydrophilicity index can be calculated by the following method.

Note that the molecular weight is determined by calculation based on constituent atoms of a substance that has been identified through subsequently described H-NMR measurement.

The term hydrophilic group refers to a group of atoms that forms a weak bond with a water molecule through electrostatic interaction or hydrogen bonding and that is stable in water.

The mass ratio of the anionic amphiphilic compound in the water dispersion of the present embodiment is <NUM> mass% or more and <NUM> mass% or less relative to <NUM> mass% of resin solid content contained in the water dispersion from a viewpoint of excellent recoatability during film coating of the water dispersion and inhibition of foaming during drying, and is preferably <NUM> mass% or less, and particularly preferably <NUM> mass% or less. Moreover, from a viewpoint of achieving good coatability, the mass ratio is preferably <NUM> mass% or more.

The non-ionic amphiphilic compound that can be used in the water dispersion of the present embodiment is an amphiphilic compound having a hydrophilic group such as a hydroxyl group or an ether bond (polyoxyethylene chain, etc.) that does not undergo ion dissociation in water.

Examples of non-ionic amphiphilic compounds include ester-type amphiphilic compounds, ether-type amphiphilic compounds, ester ether-type amphiphilic compounds, alkanol amide-type amphiphilic compounds, alkyl glycosides, and higher alcohols.

Examples of ester-type amphiphilic compounds include glyceryl laurate, glyceryl monostearate, sorbitan fatty acid esters, and sucrose fatty acid esters.

Examples of ether-type amphiphilic compounds include polyoxyethylene alkyl ethers such as pentaethylene glycol monododecyl ether and octaethylene glycol monododecyl ether.

Examples of ester ether-type amphiphilic compounds include polyoxyethylene glycerin fatty acid esters, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, sorbitan fatty acid ester polyethylene hexitan fatty acid esters, and sorbitan fatty acid ester polyethylene glycols.

Examples of alkanol amide-type amphiphilic compounds include lauric diethanolamide, oleic diethanolamide, stearic diethanolamide, and coconut diethanolamide.

Examples of alkyl glycosides include octyl glucoside, decyl glucoside, and lauryl glucoside.

Examples of higher alcohols include cetanol, stearyl alcohol, and oleyl alcohol.

One non-ionic amphiphilic compound may be used individually or two or more non-ionic amphiphilic compounds may be used as a mixture.

The non-ionic amphiphilic compound is preferably ammonium polyoxyethylene alkyl ether sulfate, polyoxyalkylene decyl ether, or polyoxyethylene oleyl ether.

The non-ionic amphiphilic compound preferably has a low critical micelle concentration (also referred to as CMC) as this results in excellent recoatability. The critical micelle concentration is preferably <NUM> mass% or less, more preferably <NUM> mass% or less, and even more preferably <NUM> mass% or less. Moreover, the critical micelle concentration is preferably <NUM> mass% or more, more preferably <NUM> mass% or more, even more preferably <NUM> mass% or more, and particularly preferably <NUM> mass% or more when solubility in water of the amphiphilic compound and affinity thereof with the halogenated vinyl polymer are taken into account.

The critical micelle concentration can be measured by the following method. First, the amphiphilic compound is dissolved in water in concentrations of <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass% , <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, and <NUM> mass% to prepare aqueous solutions, and then the surface tension of each of these aqueous solutions is measured by the Wilhelmy method. Measurement of surface tension is performed using an automatic surface tensiometer CBVP-Z (produced by Kyowa Interface Science Co. ) inside a constant temperature chamber of <NUM> and <NUM>% RH. When the determined surface tension is plotted for each concentration (mass%), the surface tension decreases with increasing concentration from the low concentration side but becomes a constant value beyond a certain concentration. The concentration (mass%) at this inflection point is taken to be the critical micelle concentration.

In a case in which the water dispersion contains a plurality of non-ionic amphiphilic compounds, a value for the critical micelle concentration of each component among the non-ionic amphiphilic compounds by itself is determined by the method described above, and then an average value calculated from the mass ratio of these components is taken to be the critical micelle concentration.

The mass ratio of the non-ionic amphiphilic compound is preferably more than <NUM> mass%, more preferably <NUM> mass% or more, even more preferably <NUM> mass% or more, even more preferably <NUM> mass% or more, and particularly preferably <NUM> mass% or more relative to <NUM> mass% of resin solid content in the halogenated vinyl polymer water dispersion from a viewpoint of coatability during film coating. Moreover, the mass ratio is preferably <NUM> mass% or less, and more preferably <NUM> mass% or less from a viewpoint of achieving good coatability.

Qualitative and quantitative analysis of the anionic amphiphilic compound and/or non-ionic amphiphilic compound is performed by the following method and can be performed by either of H-NMR or LC/MS.

Obtain concentrated dry material that has undergone the pre-treatment in (B) in the same manner as in "Analysis by H-NMR" described above, dilute by a factor of <NUM> to <NUM> through addition of methanol, and then perform measurement by LC/MS.

Device: UPLC produced by Waters Corporation/MS Synapt G2 produced by Waters Corporation
Used column: Candenza CD-C18HT (<NUM> I. × <NUM>) produced by Imtakt Corporation
Column temperature: <NUM>
Detection: PDA <NUM> to <NUM>
Flow rate: <NUM>/min
Mobile phase: A = <NUM> ammonium acetate aqueous solution, B = acetonitrile
Gradient:.

Characteristic m/z values are presented below.

After qualitative analysis, use at least three standard reagents of the detected amphiphilic compound that are of known concentrations, perform measurement thereof under the same conditions, and prepare a calibration curve from the peak area in a mass chromatogram for an m/z value that is characteristic of the target component. Use this calibration curve to quantify the emulsifier concentration in the sample solution. In the case of an unknown material, identify the material with reference to characteristic m/z values observed for various amphiphilic compounds.

The halogenated vinyl polymer water dispersion of the present embodiment may further contain sodium pyrophosphate. The term sodium pyrophosphate refers to a compound represented by a chemical formula Na<NUM>P<NUM>O<NUM>.

Addition of sodium pyrophosphate lowers the viscosity of the halogenated polymer water dispersion. As a result, leveling performance during coating improves. In particular, it is possible to prevent the formation of a ribbing pattern that may arise with a roll coater, bar coater, or the like and that acts as a cause of poor external appearance.

The mass ratio of the sodium pyrophosphate relative to <NUM> mass% of resin solid content in the halogenated vinyl polymer water dispersion is preferably <NUM> mass% or more, more preferably <NUM> mass% or more, even more preferably <NUM> mass% or more, and most preferably <NUM> mass% or more. Moreover, the upper limit is preferably <NUM> mass% or less, more preferably <NUM> mass% or less, and even more preferably <NUM> mass% or less. Setting this mass ratio as <NUM> mass% or more makes it possible to achieve the effect of lowering viscosity and also the effect of preventing the occurrence of poor external appearance such as a ribbing patterning.

The solvent in the water dispersion of the present embodiment may be just water or may include water and another solvent (for example, a film forming agent such as <NUM>,<NUM>,<NUM>-trimethyl-<NUM>,<NUM>-pentanediol, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol diethyl ether, ethylene glycol mono-<NUM>-ethylhexyl ether, dibutyl phthalate, dioctyl phthalate, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, or methanol, etc.). In a case in which another solvent is included, the other solvent is preferably <NUM> parts by mass or less relative to <NUM> parts by mass of resin solid content.

The mass ratio of resin solid content contained in the water dispersion among <NUM> mass% of the water dispersion of the present embodiment is preferably <NUM> mass% or more, and more preferably <NUM> mass% or more. This mass ratio is even more preferably <NUM> mass% or more.

Moreover, the mass ratio of the halogenated vinyl polymer relative to <NUM> mass% of resin solid content contained in the water dispersion is preferably <NUM> mass% or more, more preferably <NUM> mass% or more, and even more preferably <NUM> mass%.

The following describes characteristics of the halogenated vinyl polymer water dispersion of the present embodiment.

The surface tension of the water dispersion of the present embodiment is preferably <NUM> mN/m or more, more preferably <NUM> mN/m or more, and even more preferably <NUM> mN/m or more. Measurement of surface tension can be performed by the plate method using an automatic surface tensiometer CBVP-Z (produced by Kyowa Interface Science Co. ) inside a constant temperature chamber of <NUM> and <NUM>% RH.

When the surface tension is within any of the ranges set forth above, the water dispersion can be uniformly applied onto the surface of a base film or the surface of an anchor coating layer on a base film, and a coating film is compactly formed, and thus has a low tendency for defects to form at an interface and displays barrier properties. Moreover, foaming is less likely to occur even during high-temperature shaping.

The following describes film formation failure.

A ribbing pattern is a surface defect having a periodic ridge shape (striated/ribbed shape) that forms along a direction in which a base film is travelling at a coated surface. Leveling failure refers to a phenomenon in which irregularities in a coating film that are formed during application remain and in which the coating film does not become smooth. Orange peel patterning refers a coating film that has a wave-like pattern or surface irregularities resembling the skin of a citrus fruit (orange, etc.) after application and drying.

Foaming during film shaping refers to a phenomenon in which excess water that has been taken into a post-drying coating film is vaporized from inside of the coating film during shaping, leading to the occurrence of foaming and poor external appearance after shaping. The shaping method is not specifically limited and may be vacuum forming, pressure forming, pressing, or the like. Poor external appearance readily occurs when a conventional halogenated vinyl polymer water dispersion is recoated and is subsequently shaped. For example, poor external appearance has readily occurred when a film coated with a thickness such that resin solid content is <NUM>/m<NUM> or more has been shaped at <NUM> or higher. A layer formed through application of the water dispersion of the present embodiment has a low tendency for foaming to occur and also has a low tendency for poor external appearance to arise, and thus makes it possible to obtain a shaped product (for example, a blister pack) having good external appearance even in a case in which pressing is performed at <NUM> to <NUM> or vacuum forming is performed at <NUM> to <NUM>, for example.

A multilayer film of the present embodiment includes a layer obtained by applying a halogenated vinyl polymer water dispersion onto a base film formed of polyvinyl chloride, polyester, polyamide or polypropylene, wherein the halogenated vinyl polymer water dispersion comprises: a vinylidene chloride polymer; and <NUM> mass% or more and <NUM> mass% or less, relative to <NUM> mass% of resin solid content contained in the water dispersion, of an anionic amphiphilic compound, wherein the anionic amphiphilic compound is sodium dodecylbenzene sulfonate. The base film is preferably a multilayer film formed of polyvinyl chloride, polyester, polyamide or polypropylene.

Note that in the present specification, the layer obtained by applying the halogenated vinyl polymer water dispersion of the present embodiment may also be referred to as a water dispersion layer.

The base film is made of polyvinyl chloride, polyester, polyamide, or polypropylene. In general, the thickness of a base film (also referred to as a substrate in the present specification) for which a film made of polyvinyl chloride is used is normally <NUM> to <NUM>, though this may vary depending on the base film that is used.

The multilayer film is not limited to being composed of only the water dispersion layer, and a layer of a copolymer, other than a halogenated polymer, that is functionally adjusted with a highly polymerizable monomer as a main component can be combined (for example, stacked) with the water dispersion layer.

When the halogenated vinyl polymer water dispersion of the present embodiment is applied onto the base film that is a constituent of the multilayer film, the water dispersion can be directly applied onto the base film so as to form the water dispersion layer, but it is preferable that the surface of the base film is activated in advance of application in order to improve close adherence of the base film and the water dispersion layer.

The method of activation of the surface of the base film may be a method in which the base film is subjected to corona discharge treatment, plasma discharge treatment, strong acid treatment, electron beam treatment, ultraviolet light treatment, flame treatment, or the like in order to introduce a hydrophilic component such as a hydroxyl group, a carboxyl group, an ester group, an ether bond, an amino group, an imino group, an amide group, or a sulfuric acid group at the surface of the base film.

Another example of a method for improving close adherence of the base film and the water dispersion layer in the multilayer film of the present embodiment is a method in which an anchor coating agent is applied onto the surface of the base film, is dried to form an anchor coating layer, and then the halogenated vinyl polymer water dispersion is applied.

The anchor coating agent that is applied onto the surface of the base film may be an anchor coating agent including one or more selected from a polyacrylic-based resin, a polyurethane-based resin, an isocyanate-based resin, a polyester-based resin, an oxazoline-based resin, and a carboimide-based resin, and is preferably an anchor coating agent selected from a polyacrylic-based resin, a polyurethane-based resin, and an isocyanate-based resin. No specific limitations are placed on the form of the anchor coating agent, and the anchor coating agent may be in the form of a solution that contains an organic solvent, an aqueous solution, or an aqueous emulsion.

Application of the anchor coating agent can be performed by any method that is typically adopted in the field of film coating. For example, gravure coating such as direct gravure coating or reverse gravure coating, roll coating, bar coating, doctor knife coating, or air knife coating may be used.

After application, drying treatment can be performed by a commonly known method such as infrared drying or heated drying by hot-air drying or hot-roll drying at <NUM> to <NUM>.

The thickness of the anchor coating layer is preferably <NUM> to <NUM> for surface smoothness and for retaining close adherence of the base film and the anchor coating layer. In order to increase close adherence with the base film, it is preferable that activation of the base film surface described above is performed, formation of an anchor coating layer is then performed, and then the halogenated vinyl polymer water dispersion is applied.

In the film of the present embodiment, two or more layers of the water dispersion layer described above may be provided. Two or more water dispersion layers may be provided consecutively or may be provided with another layer in-between. Note that in the present specification, a layer formed through recoating of the halogenated vinyl polymer water dispersion is considered to be a single layer. When two or more water dispersion layers are provided consecutively, this means that water dispersion layers having different constituent components are stacked.

The water dispersion layer described above is preferably stacked on at least part of at least one surface of the base film and is more preferably stacked on the entirety of at least one surface of the base film.

In the multilayer film of the present embodiment, the water dispersion layer described above is preferably provided on at least one surface of the base film, and is more preferably provided on both surfaces of the base film.

The thickness of the water dispersion layer is preferably <NUM> or more, more preferably <NUM> or more, even more preferably <NUM> or more, even more preferably <NUM> or more, even more preferably <NUM> or more, even more preferably <NUM> or more, even more preferably <NUM> or more, even more preferably <NUM> or more, and particularly preferably <NUM> or more from a viewpoint of barrier properties. The upper limit is preferably <NUM>,<NUM> or less, more preferably <NUM> or less, even more preferably <NUM> or less, even more preferably <NUM> or less, even more preferably <NUM> or less, and particularly preferably <NUM> or less from a viewpoint of film formability and impact resistance, and may be <NUM> or less, or <NUM> or less.

The dry coating film thickness of the water dispersion layer is preferably <NUM> or more, more preferably <NUM> or more, even more preferably <NUM> or more, even more preferably <NUM> or more, even more preferably <NUM> or more, even more preferably <NUM> or more, even more preferably <NUM> or more, even more preferably <NUM> or more, and particularly preferably <NUM> or more from a viewpoint of barrier properties. Although no particular upper limit is set, the thickness is preferably <NUM>,<NUM> or less, more preferably <NUM> or less, even more preferably <NUM> or less, even more preferably <NUM> or less, even more preferably <NUM> or less, even more preferably <NUM> or less, and particularly preferably <NUM> or less from a viewpoint of film formability and impact resistance, and may be <NUM> or less.

Although a larger thickness provides the film with better barrier properties against water vapor and oxygen, foaming is more likely to occur because of uneven heating during shaping of the film by blister shaping or the like. Moreover, the blister shaped product becomes harder, which makes it difficult to press out a medication, and also suffers from deepening of slight yellow coloration and loss of external appearance. In the case of the halogenated vinyl polymer water dispersion of the present embodiment, the trade-offs described above have a low tendency to occur as a result of inclusion of a specific amphiphilic compound, and thus it is possible to obtain a film and shaped product excelling in terms of foaming, ease of pressing out, and external appearance with a thickness that gives suitable barrier properties.

The thickness of the dry coating film described above is measured by the following method.

The multilayer film obtained through application of the water dispersion of the present embodiment is cleaved using a microtome (RM2245 produced by Leica), is then observed using an electron microscope (TM4000plus produced by Hitachi, Ltd. ), and the thickness of the dry coating film of the water dispersion layer is measured.

The post-drying coating film mass of the halogenated vinyl polymer in the water dispersion layer is preferably <NUM>/m<NUM> or more, more preferably <NUM>/m<NUM> or more, even more preferably <NUM>/m<NUM> or more, further preferably <NUM>/m<NUM> or more, further preferably <NUM>/m<NUM> or more, particularly preferably <NUM>/m<NUM> or more, and especially preferably <NUM>/m<NUM> or more from a viewpoint of barrier properties. The upper limit is preferably <NUM>,<NUM>/m<NUM> or less, more preferably <NUM>,<NUM>/m<NUM> or less, even more preferably <NUM>/m<NUM> or less, particularly preferably <NUM>/m<NUM> or less, especially preferably <NUM>/m<NUM> or less, and extremely preferably <NUM>/m<NUM> or less from a viewpoint of film formability and impact resistance.

In a case in which the water dispersion layer described above is provided in plurality, the thickness and coating film mass of each layer may be the same or different.

The water content of the multilayer film of the present embodiment is preferably <NUM> mass% or less, more preferably <NUM> mass% or less, even more preferably <NUM> mass% or less, even more preferably <NUM> mass% or less, even more preferably <NUM> mass% or less, even more preferably <NUM> mass% or less, and particularly preferably <NUM> mass% or less. A lower water content is preferable because this reduces the likelihood of foaming occurring during heated shaping of the multilayer film obtained through application of the water dispersion of the present embodiment and results in the film having excellent transparency. Although a lower limit is not set for the water content since the effects described above improve as the water content decreases, a lower limit of <NUM> mass% or more is preferable as a realistic range. The water content referred to herein is a moisture value measured by the Karl Fischer method.

The water content is measured by the following method.

Using a measurement unit MKC-<NUM>, a water vaporizer ADP-<NUM>, and a control unit MCU-<NUM> produced by Kyoto Electronics Manufacturing Co. , at least <NUM> minutes of purging is performed by causing nitrogen to flow into the ADP-<NUM> at a flow rate of <NUM>/min, <NUM> ± <NUM> of the multilayer film coated with the halogenated vinyl polymer is then placed on a sample board, <NUM> minutes of purging is performed at <NUM>, and then measurement is performed at <NUM>. The sample is replaced in order to repeat these operations three times, and an average value of the three measurements is taken to be the water content.

The relative crystallinity (CI value) of the water dispersion layer as measured by a Fourier transform infrared spectrophotometer (total reflection measurement method) is preferably <NUM> or more, more preferably <NUM> or more, even more preferably <NUM> or more, even more preferably <NUM> or more, even more preferably <NUM> or more, even more preferably <NUM> or more, even more preferably <NUM> or more, and particularly preferably <NUM> or more. The strength of the water dispersion layer in the multilayer film increases as this value increases, and, as a result, it becomes harder for a trace amount of water contained in the multilayer film to swell during heated shaping, it becomes harder for visible bubbles to grow, and excellent external appearance is achieved. Although an upper limit is not specifically set for this value because the effects described above improve as the value increases, an upper limit of <NUM> or less is preferable, and an upper limit of <NUM> or less is more preferable as a realistic range.

The relative crystallinity (CI value) is measured by the following method.

An IRAffinity-<NUM> produced by Shimadzu Corporation is set to a resolution of <NUM>-<NUM> and is used to irradiate the coated surface of vinylidene chloride with infrared light and perform measurement by the ATR method.

Chlorine is known to cause C-C dipole moment strengthening through conformation change as crystallization progresses, resulting in stronger absorption at <NUM>-<NUM>. This is exploited by joining from <NUM>-<NUM> to <NUM>-<NUM> on the IR chart in a linear form and then taking a ratio of peak heights determined by <NUM>-<NUM> (C-C bonds of polyvinylidene chloride)/<NUM>-<NUM> (CH bonds of polyvinylidene chloride skeleton) to be the relative crystallinity (CI value).

The method by which the halogenated vinyl polymer water dispersion is applied onto the base film to form the water dispersion layer can be a method that is typically adopted in the field of film coating. Examples of application methods that may suitably be used include gravure coating such as direct gravure coating, roll coating such as two-roll beat coating and bottom-feed three-roll reverse coating, doctor knife coating, air knife coating, die coating, bar coating, dip coating, and spray coating. In terms of good productivity and enabling simple formation of the water dispersion layer, it is preferable to adopt gravure coating, roll coating, or air knife coating, and more preferable to adopt gravure coating. The amount of the water dispersion that is applied during application is not specifically limited and varies depending on the desired thickness of the water dispersion layer. A desired water dispersion layer can be formed by performing application and drying once or repeatedly a plurality of times. By setting the applied amount such that drying is not insufficient and such that solvent does not remain, it is possible to cause effective display of film properties. Examples of drying methods that can be used include, but are not specifically limited to, a method using natural drying, a method of drying in an oven set to a specific temperature, and a method of drying using a dryer accompanying a coater, an arch dryer, a flotation dryer, a drum dryer or an infrared dryer. The drying conditions can be selected as appropriate depending on the drying method, but in the case of drying in an oven, for example, drying is preferably performed for approximately <NUM> second to <NUM> minutes at a temperature of <NUM> to <NUM>.

The water dispersion layer may contain <NUM> parts by mass to <NUM> parts by mass of a wax relative to <NUM> parts by mass of the halogenated vinyl polymer. This amount is preferably <NUM> parts by mass to <NUM> parts by mass, and more preferably <NUM> parts by mass to <NUM> part by mass in terms of balance of crystallization rate and expression of barrier properties. Just one type of wax may be included, or a wax composition formed of two or more types of waxes may be included. In a case in which a wax (or wax composition) is included, the wax (or wax composition) can be added to the halogenated vinyl polymer water dispersion prior to formation of the water dispersion layer. The addition of a wax gives effects of improving sliding properties and preventing blocking. The type of wax is not specifically limited and can be a natural or synthetic wax. For example, polyolefin wax, paraffin wax, carnauba wax, beeswax, Chinese wax, ozokerite, montanic acid wax, or an esterified product of any thereof can be used individually or in a composition in which it is contained as a main component. Of these waxes, it is preferable to use polyolefin wax. Since the addition of a wax to a vinylidene chloride copolymer facilitates progression of crystallization and thereby causes initial physical properties to change, the mass ratio of the wax is preferably adjusted in accordance with the form of the water dispersion layer in the film.

In a case in which the water dispersion layer is provided as a layer other than a surface layer, it is preferable that the water dispersion layer is a layer that does not contain a wax. In a case in which a wax is not included, hardening of the coating film proceeds gradually, and the film has good impact resistance.

The multilayer film of the present embodiment can be used as a blister pack and, in particular, is preferably used as a blister pack for a medication.

When the multilayer film is used as a film for a blister pack, a halogenated polymer having barrier properties, other than that according to the present disclosure, may be used in combination therewith.

In the multilayer film of the present embodiment, a general-purpose resin film for shape retention may be laminated between any of the base film, the anchor coating layer, and the water dispersion layer. The laminated film is not specifically limited and may, for example, be polyethylene, polypropylene, or polyester having a thickness of <NUM> to <NUM>, for example.

The following describes characteristics of the multilayer film of the present embodiment.

The oxygen transmission rate of the multilayer film of the present embodiment is, for example, preferably less than <NUM><NUM>/m<NUM>. day under conditions of <NUM> and <NUM> MPa air pressure in the case of a film that is obtained by coating a stretched polyvinyl chloride film of <NUM> in thickness with the halogenated vinyl polymer water dispersion.

The water vapor transmission rate of the multilayer film of the present embodiment is, for example, preferably less than <NUM>/m<NUM>. day under conditions of <NUM> and <NUM>% humidity in the case of a film that is obtained by coating a stretched polyvinyl chloride film of <NUM> in thickness with the halogenated vinyl polymer water dispersion.

The following provides a more specific description of the present disclosure through examples. However, the present disclosure is not limited to these examples. Note that when referring simply to "parts" or "%" in the examples and comparisons, this represents "parts by mass" or "mass%" unless clearly indicated otherwise. Also note that evaluations of physical properties were performed by methods described further below.

A pressure-resistant reactor having a glass lining was charged with <NUM> parts of pure water, <NUM> parts of sodium D-araboascorbate, and <NUM> parts of sodium alkyl diphenyl ether sulfonate, with the final additive amount of monomer taken to be <NUM> parts. The contents of the pressure-resistant reactor were subjected to degassing under stirring and were then held at a temperature of <NUM>. A feedstock monomer mixture having a composition mass ratio of VDC/MA/AA = <NUM>/<NUM>/<NUM> was prepared in a separate vessel. A single addition of <NUM> parts of the feedstock monomer mixture was performed with respect to the pressure-resistant reactor, and polymerization was performed until the internal pressure dropped. Next, continuous metered injection of the remaining <NUM> parts of the monomer mixture was performed. Concurrently thereto, continuous metered injection was performed for an initiator having <NUM> parts of t-butyl hydroperoxide dissolved in <NUM> parts of pure water, a reductant having <NUM> parts of sodium D-araboascorbate dissolved in <NUM> parts of pure water, and an emulsifier having <NUM> parts of sodium alkyl diphenyl ether disulfonate dissolved in <NUM> parts of pure water. During the above, the contents were held at <NUM> under stirring, and the reaction was caused to proceed until the internal pressure sufficiently dropped.

The polymerization yield was <NUM>%. Since the polymerization yield was almost <NUM>%, the copolymer composition was almost equal to the charging ratio. The particle diameter of a vinylidene chloride-based copolymerized resin latex obtained in this manner was <NUM>. The obtained latex was subjected to steam stripping in order to remove unreacted monomer and was then adjusted to a pH of <NUM> using <NUM>% sodium pyrophosphate. Thereafter, pure water was used to adjust the solid content to <NUM>% to <NUM>%, and then sodium dodecylbenzenesulfonate <NUM>% aqueous solution was used to add <NUM> parts of sodium dodecylbenzenesulfonate relative to resin solid content in the latex.

A halogenated water dispersion was produced by the same method as in Example <NUM> with the exception that sodium dodecylbenzenesulfonate <NUM>% aqueous solution was changed to dialkyl sulfosuccinate salt <NUM>% aqueous solution.

A halogenated water dispersion was produced by the same method as in Example <NUM> with the exception that sodium dodecylbenzenesulfonate <NUM>% aqueous solution was changed to an <NUM>% aqueous solution prepared by mixing sodium alkylsulfonate and dialkyl sulfosuccinate salt in a mass ratio of <NUM>:<NUM>.

A halogenated water dispersion was produced by the same method as in Example <NUM> with the exception that sodium dodecylbenzenesulfonate <NUM>% aqueous solution was changed to sodium palmitate <NUM>% aqueous solution.

A halogenated water dispersion was produced by the same method as in Example <NUM> with the exception that sodium dodecylbenzenesulfonate <NUM>% aqueous solution was changed to ammonium polyoxyethylene alkyl ether sulfate <NUM>% aqueous solution.

A halogenated water dispersion was produced by the same method as in Example <NUM> with the exception that sodium dodecylbenzenesulfonate <NUM>% aqueous solution was changed to polyoxyalkylene decyl ether <NUM>% aqueous solution.

A halogenated water dispersion was produced by the same method as in Example <NUM> with the exception that sodium dodecylbenzenesulfonate <NUM>% aqueous solution was changed to polyoxyalkylene decyl ether <NUM>% aqueous solution having a different critical micelle concentration to in Reference Example <NUM>.

A halogenated water dispersion was produced by the same method as in Example <NUM> with the exception that sodium dodecylbenzenesulfonate <NUM>% aqueous solution was changed to polyoxyethylene oleyl ether <NUM>% aqueous solution.

A halogenated water dispersion was produced by the same method as in Example <NUM> with the exception that sodium dodecylbenzenesulfonate <NUM>% aqueous solution was changed to sodium alkylsulfonate <NUM>% aqueous solution.

A halogenated water dispersion was produced by the same method as in Example <NUM> with the exception that sodium dodecylbenzenesulfonate <NUM>% aqueous solution was changed to sodium alkyl diphenyl ether disulfonate <NUM>% aqueous solution.

A halogenated water dispersion was produced by the same method as in Example <NUM> with the exception that the additive amount of sodium dodecylbenzenesulfonate <NUM>% aqueous solution was changed to <NUM> parts.

A halogenated water dispersion was produced by the same method as in Example <NUM> with the exception that sodium dodecylbenzenesulfonate <NUM>% aqueous solution was changed to polyoxyethylene oleyl ether <NUM>% aqueous solution, and the amount thereof was changed to <NUM> parts.

A #<NUM> Mayer rod was used to apply an acrylic urethane-based anchor coating agent Emurdur <NUM> A (produced by BASF Corporation) as a primer onto a stretched polyvinyl chloride film of <NUM> in thickness that had undergone corona discharge treatment such that the post-drying coating film weight was <NUM>/m<NUM>, and then <NUM> seconds of drying treatment was performed at <NUM> in a hot-air circulation dryer. The vinylidene chloride-based copolymerized resin latex obtained in Example <NUM> was applied onto this film by a Mayer rod such as to have a post-drying coating film thickness of <NUM> and was subjected to <NUM> seconds of drying treatment with drying conditions of a temperature of <NUM> and an air speed of <NUM>/s in a hot-air circulation dryer.

A specimen was produced by the same method as in Example <NUM> with the exception that application was performed such as to give a post-drying coating film thickness of <NUM>.

A specimen was produced by the same method as in Example <NUM> with the exception that recoating was performed such as to give a post-drying coating film thickness of <NUM>.

A stretched polyvinyl chloride film of <NUM> was used by itself without being coated by a vinylidene chloride-based copolymerized resin latex.

Production was performed by the same method as in Example <NUM> with the exception that polymerization was performed such that VDC/MAN/MMA/AA = <NUM>/<NUM>/<NUM>/<NUM>.

A vinyl chloride sheet coated with a vinylidene chloride-based copolymer that was produced by the same method as in Example <NUM> was left at rest for <NUM> hours inside a constant temperature chamber of <NUM> and <NUM>% RH, and was then used as a specimen.

A specimen was produced by the same method as in Example <NUM> with the exception that the drying temperature was set as <NUM>.

Samples obtained in the examples, reference examples, and comparative examples were used to perform the following evaluations. The results are shown in Tables <NUM> to <NUM>.

A #<NUM> Mayer rod was used to apply an acrylic urethane-based anchor coating agent Emurdur <NUM> A (produced by BASF Corporation) as a primer onto a stretched polyvinyl chloride film of <NUM> in thickness that had undergone corona discharge treatment such that the post-drying coating film weight was <NUM>/m<NUM>, and then <NUM> seconds of drying treatment was performed at <NUM> in a hot-air circulation dryer. A vinylidene chloride-based copolymerized resin latex obtained in an example, reference example, or comparative example was applied onto this film by a Mayer rod such as to have a post-drying coating film weight for one application of <NUM>/m<NUM> to <NUM>/m<NUM>, was subjected to <NUM> seconds of drying treatment with a temperature of <NUM> and an air speed of <NUM>/s by a hot-air circulator inside a constant temperature and constant humidity tank of <NUM> and <NUM>% RH, and was recoated until the post-drying coating film weight was <NUM>/m<NUM> to <NUM>/m<NUM>.

The film was cut out as a square shape of <NUM>-square using scissors and placed at rest on a metal tray that was loaded into a vacuum dryer DP32 (produced by Yamato Scientific Co. ) adjusted to <NUM>. The film was then heated for <NUM> minutes and was vacuum heated at a degree of vacuum of -<NUM> kPa or more using a vacuum pump PX-<NUM> (produced by Yamato Scientific Co. ) in a state in which the temperature was held at <NUM>. The film that had been vacuum heated was removed and then visually judged. The evaluation standard was set as the following four levels using a film coated with Comparative Example <NUM> under the same conditions as a comparison.

A #<NUM> Mayer rod was used to apply an acrylic urethane-based anchor coating agent Emurdur <NUM> A (produced by BASF Corporation) as a primer onto a stretched polyvinyl chloride film of <NUM> in thickness that had undergone corona discharge treatment such that the post-drying coating film weight was <NUM>/m<NUM>, and then <NUM> seconds of drying treatment was performed at <NUM> and <NUM>/s in a hot-air circulation dryer. A vinylidene chloride-based copolymerized resin latex obtained in an example, reference example, or comparative example was applied onto this film by a Mayer rod such as to have a post-drying coating film weight for one application of <NUM>/m<NUM> to <NUM>/m<NUM>, and was subjected to <NUM> seconds of drying treatment with a temperature of <NUM> and an air speed of <NUM>/s by a hot-air circulator inside a constant temperature and constant humidity tank of <NUM> and <NUM>% RH so as to produce a coated film.

This film was visually judged. The evaluation standard was set as the following four levels using a film coated with Comparative Example <NUM> under the same conditions as a comparison. The evaluation standard for coatability is illustrated in <FIG>.

This film was visually judged. The evaluation standard was set as the following four levels using a film coated with Comparative Example <NUM> under the same conditions as a comparison. The evaluation standard for recoatability is illustrated in <FIG>.

A #<NUM> Mayer rod was used to apply an acrylic urethane-based anchor coating agent Emurdur <NUM> A (produced by BASF Corporation) as a primer onto a stretched polyvinyl chloride film of <NUM> in thickness that had undergone corona discharge treatment such that the post-drying coating film weight was <NUM>/m<NUM>, and then <NUM> seconds of drying treatment was performed at <NUM> in a hot-air circulation dryer. A vinylidene chloride-based copolymerized resin latex obtained in an example, reference example, or comparative example was applied onto this film by a Mayer rod (note that Mayer rods of different numbers were used) such as to have a post-drying coating film weight for one application of <NUM>/m<NUM> to <NUM>/m<NUM>, was subjected to <NUM> seconds of drying treatment under drying conditions of a temperature of <NUM> and an air speed of <NUM>/s in a hot-air circulation dryer, and was recoated until the post-drying coating film weight was <NUM>/m<NUM> to <NUM>/m<NUM>.

The oxygen transmission rate of the film was measured as an evaluation of barrier properties. After performing sufficient moisture control of the coated film at room temperature with a relative humidity of <NUM>%, an OX-TRAN <NUM> (produced by Modern Control Inc. ) was used to measure the oxygen transmission rate at <NUM> and <NUM>% relative humidity.

The water vapor transmission rate of the film was also measured as an evaluation of barrier properties. After performing sufficient moisture control of the coated film at room temperature with a relative humidity of <NUM>%, a PERMATRAN-W <NUM>/<NUM> (produced by Modern Control Inc. ) was used to measure the water vapor transmission rate at <NUM> and <NUM>% relative humidity.

In addition, a large rotary microtome OSK 97LF506 (produced by Ogawa Seiki Co. ) was used to cut the coated film and produce a slice, and then a microscope KH-<NUM> (produced by Hirox) was used to observe a cross-section of the slice and measure the film thickness.

An amphiphilic compound was dissolved in water in concentrations of <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass% , <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, <NUM> mass%, and <NUM> mass% to prepare aqueous solutions, and then the surface tension of each of these aqueous solutions was measured by the Wilhelmy method. Measurement of surface tension was performed using an automatic surface tensiometer CBVP-Z (produced by Kyowa Interface Science Co. ) inside a constant temperature chamber of <NUM> and <NUM>% RH. When the determined surface tension was plotted for each concentration (mass%), the surface tension decreased with increasing concentration from the low concentration side but became a constant value beyond a certain concentration. The concentration (mass%) at this inflection point was taken to be the critical micelle concentration.

Measurement of surface tension was performed by the plate method using an automatic surface tensiometer CBVP-Z (produced by Kyowa Interface Science Co. ) inside a constant temperature chamber of <NUM> and <NUM>% RH.

A multilayer film obtained in an example or comparative example was cleaved using a microtome (RM2245 produced by Leica), was then observed using an electron microscope (TM4000plus produced by Hitachi, Ltd. ), and the thickness of the dry coating film of the water dispersion layer was measured.

Using a measurement unit MKC-<NUM>, a water vaporizer ADP-<NUM>, and a control unit MCU-<NUM> produced by Kyoto Electronics Manufacturing Co. , at least <NUM> minutes of purging was performed by causing nitrogen to flow into the ADP-<NUM> at a flow rate of <NUM>/min, <NUM> ± <NUM> of a multilayer film coated with a halogenated vinyl polymer was then placed on a sample board, <NUM> minutes of purging was performed at <NUM>, and then measurement was performed at <NUM>. The sample was replaced in order to repeat these operations three times, and an average value of the three measurements was taken to be the water content.

An IRAffinity-<NUM> produced by Shimadzu Corporation was set to a resolution of <NUM>-<NUM> and was used to irradiate a coated surface of vinylidene chloride with infrared light and perform measurement by the ATR method.

Chlorine is known to cause C-C dipole moment strengthening through conformation change as crystallization progresses, resulting in stronger absorption at <NUM>-<NUM>. This was exploited by joining from <NUM>-<NUM> to <NUM>-<NUM> on the IR chart in a linear form and then taking a ratio of peak heights determined by <NUM>-<NUM> (C-C bonds of polyvinylidene chloride)/<NUM>-<NUM> (CH bonds of polyvinylidene chloride skeleton) to be the relative crystallinity (CI value).

Examples <NUM>, <NUM> and <NUM> in Table <NUM> are Reference Examples not according to the invention.

Examples <NUM> and <NUM> in Table <NUM> are Reference Examples not according to the invention.

Claim 1:
A multilayer film comprising a layer obtained by applying a halogenated vinyl polymer water dispersion onto a base film formed of a polymer differing from the halogenated vinyl polymer,
wherein the halogenated vinyl polymer water dispersion comprises:
a vinylidene chloride polymer; and
<NUM> mass% or more and <NUM> mass% or less, relative to <NUM> mass% of resin solid content contained in the water dispersion, of an anionic amphiphilic compound, wherein the anionic amphiphilic compound is sodium dodecylbenzene sulfonate, and
wherein the base film is made of polyvinyl chloride, polyester, polyamide, or polypropylene.