JP3346126B2 - Gas barrier film and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas barrier film and a method for producing the same, and more particularly, to a gas barrier film having gas barrier properties and moisture-proof properties under high humidity and a method for producing the same.

[0002]

2. Description of the Related Art In the field of packaging of foods and medicines, if oxygen or the like enters from the outside air, the contents cannot be stored for a long period of time due to deterioration of the contents. Therefore, a film having a gas barrier property capable of preventing entry of outside air. Is being developed.

[0003] Polymer Engineering and
According to Science, Vol. 20, No. 22, pp. 1543-1546 (December 1986), polyvinylidene chloride, polyvinylidene chloride,
Examples include polyacrylonitrile and polyvinyl alcohol. However, since polyvinylidene chloride contains a chlorine atom and polyacrylonitrile contains a -CN group, environmental problems at the time of disposal have been raised in recent years. Further, since polyvinyl alcohol contains an -OH group, the humidity dependence of gas barrier properties is large, and the gas barrier properties are significantly reduced at high humidity. Even an ethylene-vinyl alcohol copolymer in which the humidity dependence of polyvinyl alcohol has been improved, gas barrier properties at high humidity are not yet sufficient.

On the other hand, silicon oxide (JP-B-53-12953)
And aluminum oxide (JP-A-62-1799).
A film in which an inorganic substance such as No. 35 is vapor-deposited on the surface of a substrate has been developed. However, the formation of these films requires a very high cost due to the addition of a vapor deposition process, the lack of flexibility of the inorganic vapor-deposited film, the poor adhesion to the substrate, and the like, making it difficult to handle as a film. The problem has arisen.

As means for solving these problems, a film in which a base material is provided with a coating film composed of a metal oxide and polyvinyl alcohol (JP-A-56-4563, etc.) has been developed. As for the gas barrier property at the time, it is not yet at a satisfactory level. Further, a film having a gas barrier layer composed of an inorganic layered compound and a high hydrogen bonding compound (JP-A-6-93133, JP-A-7-41)
However, there is a great disadvantage in terms of productivity because long time drying or heat treatment is required in the process of forming a gas barrier layer to obtain a high barrier property, and deterioration of the gas barrier property after a durability test is reduced. large. Further, when a coating film is formed on an olefin-based resin base film, there is a problem that adhesion between the coating film and the film is poor and the film is easily peeled off.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional gas barrier film and to provide a gas barrier film having high gas barrier properties even under high humidity and a method for producing the same. is there.

[0007]

In order to achieve the above object, the present invention provides a coating film comprising a water-soluble polymer and an inorganic layered compound as main components on at least one surface of a thermoplastic resin base film. Wherein the atomic ratio (N / C) of nitrogen to carbon on the coating layer side surface (side A) of the substrate film is from 0.001 to 0.1. It consists of

[0008] A water-soluble polymer and an inorganic layered compound are mainly formed on the surface of a thermoplastic resin base film having an atomic ratio of nitrogen to carbon (N / C) of 0.001 to 0.1. And a method for producing a gas barrier film, characterized by applying and drying a coating agent.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a film comprising a water-soluble polymer and an inorganic layer compound on a film having a defined atomic ratio of nitrogen and carbon (N / C) on the film layer side of a base film. Thus, a gas barrier film having excellent gas barrier properties under high humidity, particularly excellent gas barrier properties after a durability test and adhesion of a coating film has been developed, and the effect thereof is extremely large.

In the present invention, the atomic ratio of nitrogen to carbon (N / C) on the surface (side A) of the substrate film on the coating layer side
Is required to be in the range of 0.001 to 0.1 in consideration of gas barrier properties, adhesion of the coating film, technical problems, and the like. It is more preferably in the range of 0.0015 to 0.08, particularly preferably in the range of 0.002 to 0.05. The value of N / C on the surface A can be determined by measuring an X-ray photoelectron spectroscopy (ESCA) spectrum. In order to determine the N / C value of the film on which the coating film is formed, the spectrum may be measured after removing the coating film by hot water treatment or sputtering, but the ESCA spectrum is measured while performing ion etching or the like. Examine the composition distribution from the surface to the depth direction,
A method is preferably used in which the depth at which the number of nitrogen atoms is maximized near the interface between the coating film and the base film is defined as the A surface, and N / C is determined from the spectrum at that depth. In the case where the maximum is not taken, a depth of 1/2 of the sum of the maximum value and the minimum value in the vicinity of the interface can be set as the A plane. Also, 2
A method of measuring the composition distribution in the depth direction using a secondary ion mass spectrometer (SIMS) to obtain N / C is also preferably used.

The thermoplastic resin base film used in the present invention is necessary mainly for imparting mechanical properties and processability of the film, and includes various commercially available thermoplastic resin films. Examples of the resin include olefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate, polybutylene terephthalate and polyethylene-2,6-naphthalate; amide resins such as nylon 6 and nylon 12; polyvinyl chloride; Copolymer or saponified product thereof, polystyrene, polycarbonate, polysulfone, polyphenylene oxide, polyphenylene sulfide, aromatic polyamide, polyimide, polyamideimide, cellulose, cellulose acetate,
Examples include polyvinylidene chloride, polyacrylonitrile, polyvinyl alcohol, and the like, and copolymers thereof. As the resin of the base film, from the viewpoints of transparency, gas barrier properties, etc., olefin resins such as polyethylene and polypropylene or polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,
Polyester resins such as 6-naphthalate are preferred.
Further, olefin resins such as polyethylene and polypropylene are preferable from the viewpoint of moisture resistance, and polypropylene is particularly preferable.

When polypropylene is used for the base film, a single-layer film composed of only a layer mainly composed of a polypropylene polymer is preferably used, but a resin layer (I layer) mainly composed of a polypropylene copolymer is preferably used. ) Is more preferably a polypropylene composite film formed by laminating at least one surface of a base layer (II layer) containing a polypropylene polymer as a main component.

The polypropylene copolymer (hereinafter abbreviated as PP-1) as a main component of the I layer includes ethylene and butene-1.
1 to 15 wt%, preferably 1 to 10 wt%, more preferably 1 to 6 wt%
Is a polypropylene copolymer copolymerized in the range described above. P
The melting point of P-1 is 135 to 1 in terms of the heat resistance of the film.
65 ° C is preferable, and 140 to 155 ° C is more preferable. From the viewpoint of compatibility with other resins, for example, ethylene /
A propylene copolymer and an ethylene / butene / propylene copolymer are preferred. Further, the melt flow index (MFI) of PP-1 is preferably from 0.1 to 1 g / min, more preferably from 0.2 to 0.6 g / min. As a resin constituting the I layer, PP-1 is preferably used, and it is more preferable to use a mixed resin of PP-1 and an ethylene copolymer. By using a mixed resin of PP-1 and an ethylene copolymer, there are few coarse protrusions on the surface of the I layer, a dense protrusion group is formed, and the moisture barrier properties as a gas barrier film is improved.

The ethylene copolymer (hereinafter abbreviated as ECP) to be mixed with PP-1 of the present invention is an ethylene-α-olefin copolymer, a copolymer of ethylene with vinyl acetate, an acrylate ester and an acrylate monomer. Coalescence and the like. Examples of the α-olefin monomer of the ethylene-α-olefin copolymer include propylene, butene-1, hexene-1, and octene-1, and propylene and butene-1 are particularly preferred. The copolymerization amount of the α-olefin is preferably from 10 to 30% by weight. In addition, the copolymerization amount of a copolymer of ethylene and vinyl acetate, an acrylate, or an acrylate monomer is preferably 15% by weight or less from the viewpoint of resin compatibility. Preferred as ECP are ethylene-butene-1 copolymer and ethylene-methyl methacrylate. ECP MFI
(Polyethylene resin method, temperature = 190 ° C)
2 g / min is preferable, and 0.2 to 1 g / min is more preferable. Since the surface of the I layer becomes rough and the moisture resistance deteriorates,
The resin mixing ratio of PP-1 to ECP is 95: 5 to 7 by weight.
5:25 is preferred, 92: 8 to 80:20 is more preferred, and 90:10 to 85:15 is particularly preferred.

The polypropylene polymer (hereinafter abbreviated as PP-2) as a main component of the II layer is a crystalline polypropylene, and a homopolymer of propylene or an α-olefin such as ethylene or butene-1 having preferably 10 wt. % Or less, more preferably 6% by weight or less, particularly preferably 4w
Copolymers copolymerized at t% or less are also included. Preferably, it is a homopolymer of polypropylene. The MFI of PP-2 is preferably in the range of 0.1 to 1 g / min, more preferably 0.2 to 0.6 g / min. The isotactic index (II) is 95 since the crystallinity of the film can be increased and this is advantageous from the moisture-proof property of the film.
To 99.5%, more preferably 97 to 99.5%.
The range is 0%. In the production of the film, it is preferable that the end of the film is cut off and reused as a recovered material for the layer II constituting the present invention because the production cost of the film can be reduced. In this case, the mixture of the I-layer resin laminated on the polypropylene polymer of the present invention at 15 wt% or less is also included in the II-layer of the present invention.

In the present invention, the base film is unstretched,
Either uniaxial stretching or biaxial stretching may be used, but from the viewpoint of dimensional stability and mechanical properties, biaxially stretched one is particularly preferred. The structure of the base film is preferably an I layer / II layer or an I layer / II layer / I layer composite film, and more preferably an I layer / II layer composite film. In this case, a heat seal layer may be laminated so as to have I layer / II layer / heat seal layer. The total thickness of the base film is not limited, but is preferably 1 to 500 μm. In order to achieve both gas barrier properties and heat resistance, the thickness of the I layer is preferably from 0.2 to 5 μm, more preferably from 0.1 to 5 μm.
3 to 2.5 μm.

The wetting tension of the surface A of the present invention is 31 to 60 mN.
/ M, more preferably 35-60 mN / m, 40-55
mN / m is more preferred.

The base film of the present invention may contain a small amount of a heat stabilizer, an antioxidant, inorganic or organic particles, etc., if necessary. For example, as a heat stabilizer,
6-di-tert-butyl-4-methylphenol (BH
T) etc. is 0.5% by weight or less, and tetrakis- (methylene- (3,5-di-tert-butyl4-
Hydroxy-hydrocinnamate)) butane (“Irganox” 1010) or the like may be added at 0.1 wt% or less. Examples of the inorganic and organic particles include talc, kaolin, calcium carbonate, titanium oxide, silicon oxide, calcium fluoride, lithium fluoride, alumina, barium sulfate, zirconia, mica, calcium phosphate, and crosslinked polystyrene particles.

Surface roughness R of side A of the base film of the present invention
a is from 0.03 to 0.3 from the viewpoints of gas barrier properties and moisture-proof properties.
12 μm is preferred, and more preferably 0.03 to 0.1
0 μm, particularly preferably 0.04 to 0.08 μm. It is considered that the gas barrier property and the moisture-proof property are deteriorated because the coating film is shaved due to the contact between the film and the roll after the coating film formation. The surface roughness Ra of the surface A can be changed by mixing inorganic or organic particles into the base film or by changing the resin M
This can be achieved by changing the FI, and if the surface of the I layer
Change P-1 MFI, PP-1 MFI and ECP M
This can be achieved by changing the combination of FI or the mixing ratio. It is preferable not to add inorganic or organic particles to the I layer, and when it is added, particles having a particle size of 1 μm or less are preferable.

Further, these thermoplastic resin base films are preferably transparent. Light transmittance is 40
% Or more, more preferably 60% or more.

The water-soluble polymer which is one of the main components constituting the coating film in the present invention refers to a polymer which can be completely dissolved or finely dispersed in water at normal temperature, for example, polyvinyl alcohol and its derivatives. , Carboxymethylcellulose, cellulose derivatives such as hydroxyethylcellulose, starches such as oxidized starch, etherified starch, dextrin, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, or esters, salts and copolymers thereof, sulfoisophthalate Examples thereof include copolymers containing polar groups such as acids, vinyl polymers such as polyhydroxyethyl methacrylate and copolymers thereof, and polymers modified with functional groups such as carboxyl groups of these various polymers. Preferable are polyvinyl alcohol polymers and derivatives thereof, and particularly preferable are polyvinyl alcohol having a saponification degree of 75 mol% or more, polyvinyl alcohol in which 40 mol% or less of all hydroxyl groups are acetalized, and copolymers having a vinyl alcohol unit of 60 mol% or more. Polyvinyl alcohol. The polymerization degree of polyvinyl alcohol and its derivatives is preferably from 100 to 5000, and from 500 to 3
000 is more preferred.

The inorganic layered compound, which is another main component of the coating film, is an inorganic compound in which several ultrathin unit crystal layers are overlapped to form one layered particle, and a solvent is used. Those which swell and cleave at the same time are preferred. Among them, a clay compound having a swelling property in a solvent is particularly preferably used. The clay compound having a swelling property in a solvent according to the present invention is a clay compound having a property of coordinating, absorbing and swelling water between extremely thin unit crystal layers, and generally, Si ⁴⁺ is O
^2- coordinated layers forming a tetrahedral structure and Al ³⁺ , Mg
²⁺ , Fe ²⁺ , Fe ^3+, etc. are coordinated with O ²⁻ and OH ⁻ to form an octahedral structure in a one-to-one or two-to-one combination to form a layered structure. And may be natural or synthetic. Typical examples are kaolinite, halloysite, montmorillonite, vercurite, dickite, nacrite, antigorite, pyrophyllite, hectorite, beidellite, margarite, talc, tetrasilyl mica, muscovite and phlogopite. And chlorite. As the size of the layered compound, the average particle size is 5 μm or less, and the thickness is 500
nm or less is preferable.

In the present invention, the surface roughness parameter Rt / Ra of the coating film surface is preferably 20 or less, more preferably 15 or less, from the viewpoint of gas barrier properties. Rt is the maximum height and is the distance between the maximum peak and the deepest valley of the surface roughness curve. Gas barrier properties are worse
This is considered to be because the coating film surface is shaved due to contact with the roll when forming the coating film at high speed or contact between the films during winding. For details of the parameters, see "Method for measuring and evaluating surface roughness" by Jiro Nara (General Technology Center, 1
983).

In the present invention, the mixing ratio of the water-soluble polymer / layered compound is 10% by weight in order to achieve both strength (elongation, flexibility and pinhole properties) and gas barrier properties of the coating film.
It is preferably in the range of / 90 to 95/5.

In the present invention, the thickness of the coating film is not particularly limited.
10 μm is preferred, and 0.3 to 6 μm is particularly preferred.

The coating film may contain various additives as long as the gas barrier properties are not impaired. For example, antioxidants, weathering agents, heat stabilizers, lubricants, nucleating agents, ultraviolet absorbers, coloring agents and the like. Further, inorganic or organic particles may be contained as long as the transparency is not impaired. For example, talc, kaolin, calcium carbonate, titanium oxide, silicon oxide, calcium fluoride, lithium fluoride, alumina, barium sulfate, zirconia,
Mica, calcium phosphate, crosslinked polystyrene particles, and the like.

Further, a divalent or higher valent metal salt, a catalyst component and the like may be added in order to enhance the interaction between the layered compound and the polymer, between the polymers or between the layered compounds, etc. in forming the coating film. . It is desirable to use an acetate, a sulfate, a nitrate, or the like containing calcium, magnesium, aluminum, or the like because moisture resistance is improved. The amount is about 1 to 10000 ppm based on the coating film.

Next, a typical method for producing the gas barrier film of the present invention will be described, but the present invention is not limited thereto.

First, a base film is formed by a known method. For example, in the case of polypropylene, a resin as a raw material is prepared, supplied to an extruder, melted at a temperature of 230 to 280 ° C, passed through a filter, and extruded from a slit die. At this time, in the case of a composite film comprising the I layer and the II layer, each resin is supplied to a separate extruder and melted, and then, in a short tube or a die, the I layer / II layer or the I layer / II layer / I They are combined into a layer and extruded from a slit-shaped die. This is wound around a metal drum and cooled and solidified into a sheet to obtain an unstretched film. In this case, the temperature of the cooling metal drum is preferably set to 30 to 70 ° C. to crystallize the film. The unstretched film is biaxially stretched and biaxially oriented. As the stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used, and the sequential biaxial stretching method is particularly preferable in terms of moisture resistance. As the sequential biaxial stretching method, first, the unstretched film is heated to a temperature of 115 to 145 ° C, stretched 4 to 7 times in the longitudinal direction and cooled, and then guided into a tenter type stretching machine and heated to a temperature of 140 to 165 ° C. 5-10 in width direction
After stretching twice, it is obtained by performing a relaxation heat treatment at a temperature of 155 to 170 ° C. and then cooling.

In order to make the atomic ratio (N / C) of nitrogen and carbon on the surface A of the obtained substrate film within the range of the present invention, the surface A is subjected to a corona discharge treatment or a pressure reduction before the coating layer is formed. This is performed by performing a plasma treatment in a rare gas below. The atmosphere during the corona discharge treatment was nitrogen gas (oxygen concentration was 3 vol.
1% or less), carbon dioxide or a mixed gas of nitrogen / carbon dioxide is preferable, and a mixed gas of nitrogen / carbon dioxide (volume ratio = 9).
5/5 to 50/50) are more preferred. In addition, plasma treatment is performed while introducing a small amount of argon, helium, carbon dioxide gas or the like into a vessel having a degree of vacuum of about 10 ⁻² Pa, and performing a glow discharge from the electrode to which a high voltage is applied toward the surface A of the film. I do. At this time, carbon dioxide gas is preferred from the viewpoint of processing effect and economic efficiency. The processing strength is calculated from voltage × current / (electrode width × film running speed) (W · min / m ² ), but is preferably 5 to 400, more preferably 10 to 200, and still more preferably 20 to 100. Further, the anchor treatment may be performed using a known anchor treatment agent such as a urethane resin or an epoxy resin.

The method of applying the coating agent on the thermoplastic resin base film is not particularly limited, and an extrusion laminating method or a melt coating method may be used. However, since a thin film can be coated at a high speed, It is preferable to apply a gravure coat, a reverse coat, a spray coat, a kiss coat, a die coat or a metaling bar coat to a dispersion solution in which the components of the coating film are dispersed in various solvents. Either an off-line coating method or an in-line coating method may be used, but an off-line coating method is preferred from the viewpoint of gas barrier properties. In the case of a composite film composed of the I layer and the II layer, it is desirable that a coating film be formed on the surface of the I layer.

The method for drying the coating film is not particularly limited, and a hot roll contact method, a heat medium (air, oil, etc.) contact method, an infrared heating method, a microwave heating method, and the like can be used. Drying of the coating film
From the viewpoint of gas barrier properties, the drying is preferably performed in the range of 80 ° C. to 170 ° C., and the drying time is preferably 20 seconds or less.

The coating containing the components of the coating film is preferably a solution in which a water-soluble polymer is uniformly dissolved or dispersed in a solvent and the layered compound is uniformly dispersed or swelled. As the solvent, water or a mixed solution of water / lower alcohol is used, and a mixed solution of water / lower alcohol is preferably used from the viewpoint of gas barrier properties under high humidity, adhesiveness of a coating film, and productivity. The lower alcohol is an alcoholic compound having a linear or branched aliphatic group having 1 to 3 carbon atoms. For example, methanol, ethanol, n- or iso-propanol is preferably used. The mixing ratio of water / alcohol is 99/1 to 20/8 by weight.
0 is preferred.

In order to impart coating properties to the film, the mixed solvent may contain another water-soluble organic compound as the third component as long as the stability of the dispersion solution is maintained. Is also good. Examples of the water-soluble organic compound include alcohols such as methanol, ethanol, n- or iso-propanol, glycols such as ethylene glycol and propylene glycol, methyl cellosolve,
Glycol derivatives such as ethyl cellosolve and n-butyl cellosolve; polyhydric alcohols such as glycerin and wax; ethers such as dioxane; esters such as ethyl acetate; and ketones such as methyl ethyl ketone.
Further, the pH of the dispersion solution is from 2 to 11 in view of the stability of the solution.
Is preferred.

The method for adjusting the coating agent is not particularly limited,
A method in which a water-soluble polymer is uniformly dissolved in a solvent and then mixed with a solution in which the layered compound is uniformly dispersed is effectively used.

[0036]

[Evaluation method of characteristics] The evaluation method of characteristics used in the present invention is as follows.

(1) Gas Barrier Property (Oxygen Permeability) The oxygen permeability was measured using an oxygen permeability measuring device (OX-TRAN 2/20, manufactured by mocon) according to JIS K7126 B method. The measurement conditions are a temperature of 23 ° C. and a relative humidity of 80%.

(2) Gas barrier property after endurance test A sample (280 mm × 180 mm) subjected to 100 times of gelbo repetition (reciprocating motion cycle: 40 times / min) at 5 ° C. using a gelbo flex tester was subjected to the method described above. Gas barrier properties were measured.

(3) Moisture Proof (Water Vapor Permeability) According to JIS K7129 B method, using a moisture permeability measuring device (PERCONTRAN-W1A, manufactured by mocon), water vapor transmission under an atmosphere of 40 ° C. and 90% RH. The rate was measured.

(4) Atomic ratio of nitrogen to carbon (N / C) ESCA spectrometer (ESCA7, manufactured by Shimadzu Corporation)
50) and the excited X-ray MgKα 1.2 line (284.
6 eV), a nitrogen 1S orbital (N _1S ) spectrum and a carbon 1S orbital (C _1S ) spectrum were measured at a photoelectron escape angle of 90 °, and the number of nitrogen atoms on the A-plane was determined based on the integrated intensity ratio of each peak. The ratio of the number of carbon atoms was determined.

(5) Surface roughness (Ra), maximum height (R)
t) Measurement was performed using a high-precision thin film step measuring device ET-10 manufactured by Kosaka Laboratory. The measurement conditions were as follows, and the value was an average value of 20 measurements.

Stylus tip radius: 0.5 μm Stylus load: 5 mg Measurement length: 1 mm Cut-off: 0.08 mm

(5) Adhesion between Coating Film and Substrate 100 crosscuts of 1 mm ² were inserted into the coating film, and Nichiban “cellophane tape” was stuck thereon and strongly pressed with a finger. It was rapidly peeled off and evaluated in four steps based on the number of remaining coating films (A: 100, B: 80-9)
9, Δ: 50 to 79 ×: 0 to 49). (◎,）) were evaluated as good adhesiveness.

(6) Isotactic index (I
I) The sample was dried at 130 ° C for 2 hours. From now on, weight W (m
g) Take a sample, put into a Soxhlet extractor and boil, n
-Extraction with heptane for 12 hours. Next, the sample was taken out, sufficiently washed with acetone, dried at 130 ° C. for 6 hours, and then the weight W ′ (mg) was measured and determined by the following equation.

II = (W '/ W) × 100 (%)

(7) Melt flow index (MF)
I) JIS K-6758 polypropylene test method (230
C., 21.2 N).

[0047]

【Example】

 Example 1 First, a base film was formed by the following method.

As the resin constituting the layer I of the present invention, a polypropylene copolymerized with 3.2% by weight of ethylene (MFI =
0.45 g / min, melting point = 145 ° C., PP-1) and ethylene butene copolymer (MFI = 0.36 g / min, ECP) obtained by copolymerizing butene-1 with 15 wt%, and polypropylene alone as a resin constituting the II layer Combination (II
= 97.0%, MFI = 0.25 g / min, PP-
A resin prepared by mixing 2) with the composition shown in Table 1 was prepared, and these I-layer resin and II-layer resin were supplied to separate extruders.
Melted at a temperature of ℃ C, passed through a filter and
The layers were combined into a layer / II layer, extruded from a slit-shaped die, wound around a metal drum heated to a temperature of 40 ° C., and formed into a sheet. This sheet is heated to a temperature of 135 ° C., stretched 5 times in the longitudinal direction, cooled and then guided to a tenter type stretching machine, heated to a temperature of 165 ° C., stretched 9 times in the width direction, and then stretched in the width direction at a temperature of 165 ° C. Was given a heat treatment while giving 8% relaxation, and cooled to room temperature. Thereafter, a corona discharge treatment (treatment intensity = 60 W · min / m ² ) was performed in a mixed gas atmosphere of nitrogen / carbon dioxide gas (volume ratio 85/15) to obtain a substrate film. The total thickness of the film was 18 μm and the thickness of the I layer was 0.8 μm.

Next, a saponification degree of 98.
A water / isopropyl alcohol (hereinafter IPA) solution (weight ratio 90/50) is prepared so that polyvinyl alcohol (hereinafter abbreviated as PVA) having a polymerization degree of 5 mol% or more and a polymerization degree of 2400 becomes 5 wt%.
(A solution). Montmorillonite (Kunimine Kogyo Co., Kunipia-F) as a layered compound is 3w
It was dispersed in water so as to be t% (Solution B). Liquid A and liquid B are mixed so that the mixing ratio of PVA / montmorillonite becomes 50/50 by weight, and IPA is applied to all coating materials at 10 watts.
A coating agent was prepared so as to have a solid content concentration of 2.5% by weight and t%.

After applying the coating material on the base film by a reverse coater (coating speed: 60 m / min), the coating material is introduced into a hot-air drying dryer, dried at 120 ° C. under low tension for 10 seconds, and wound up. Was.

The thickness of the obtained film is 0.5 μm.
Table 2 shows other characteristics. A film having excellent gas barrier properties, moisture-proof properties, and coating film adhesion was obtained.

Examples 2 and 3 Films were obtained in the same manner as in Example 1 except that the composition of the base film was changed as shown in Table 1. A film having excellent gas barrier properties, moisture-proof properties and adhesiveness was obtained.

Example 4 A film was prepared in the same manner as in Example 1 except that the surface treatment method for the base film was changed to a corona discharge treatment (treatment intensity = 60 W · min / m ² ) in a nitrogen gas atmosphere. Obtained. A film having excellent gas barrier properties, moisture-proof properties and adhesiveness was obtained.

Example 5 Polypropylene homopolymer (II = 97.0%, MFI
= 0.25 g / min, PP-2) was prepared, supplied to an extruder, melted at a temperature of 260 ° C., and extruded from a slit die through a filtration filter in the same manner as in Example 1. To obtain a film. A film having excellent gas barrier properties, moisture-proof properties and adhesiveness was obtained.

Comparative Example 1 A film was obtained in the same manner as in Example 1 except that the surface treatment was not performed on the base film. No film was formed, and gas barrier properties and adhesion of the film were poor.

Comparative Example 2 A film was obtained in the same manner as in Example 1 except that the surface treatment of the substrate film was changed to a corona discharge treatment in the atmosphere (treatment intensity = 60 W · min / m ² ). The gas barrier properties and the adhesion of the coating film after the durability test were poor.

[0057]

[Table 1] The surface treatment method for the surface A is as follows. Method a is a corona discharge treatment (treatment intensity = 60 W · min / m) in a mixed gas atmosphere of nitrogen / carbon dioxide (volume ratio 85/15).
² ), method b is a corona discharge treatment in a nitrogen gas atmosphere (treatment intensity = 60 W · min / m ² ), and method c is a corona discharge treatment in air (treatment intensity = 60 W · min / m ² ). .

[0058]

[Table 2]

[0059]

The film obtained by the present invention has a gas barrier property under high humidity, a gas barrier property after a durability test, and an adhesive property between a coating film and a base film, and thus can be used as any packaging material. be able to.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-41685 (JP, A) JP-A-6-93133 (JP, A) JP-A-3-93542 (JP, A) JP-A-61- 225049 (JP, A) JP-A-53-71182 (JP, A) JP-B-56-18381 (JP, B1) JP-B-6-47277 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J ^7/ 04-7/06 B32B 27/00-27/42

Claims (8)

(57) [Claims] 1. A film in which a coating film containing a water-soluble polymer and an inorganic stratiform compound as a main component is formed on at least one surface of a thermoplastic resin base film, and the coating film layer side surface of the base film ( A gas barrier film wherein the atomic ratio (N / C) of nitrogen to carbon (A side) is 0.001 to 0.1. 2. The gas barrier film according to claim 1, wherein the base film is made of an olefin resin. 3. A polypropylene composite comprising a base film and a resin layer (I layer) mainly composed of a polypropylene copolymer laminated on at least one surface of a base layer (II layer) mainly composed of a polypropylene polymer. 3. The gas barrier film according to claim 1, wherein the film is a film, and the coating layer is formed on a surface of the I layer. 4. 4. A resin layer (I layer) comprising a mixed resin of a polypropylene copolymer and an ethylene copolymer, wherein the mixing ratio of both is 95: 5 to 75:25 by weight. The gas barrier film according to claim 3. 5. An atomic ratio of nitrogen to carbon (N / C) of 0.5.
A method for producing a gas barrier film, comprising applying and drying a coating agent containing a water-soluble polymer and an inorganic layered compound as main components on the surface of a thermoplastic resin base film having a thickness of 001 to 0.1. 6. The method according to claim 5, wherein the base film is an olefin resin. 7. A polypropylene composite comprising a base film and a resin layer (I layer) mainly composed of a polypropylene copolymer laminated on at least one surface of a base layer (II layer) mainly composed of a polypropylene polymer. The method for producing a gas barrier film according to claim 5, wherein the film is a film, and the coating layer is formed on the surface of the I layer. 8. The resin layer (I layer) is made of a mixed resin of a polypropylene copolymer and an ethylene copolymer, and the mixing ratio of both is 95: 5 to 75:25 by weight. A method for producing the gas barrier film according to claim 7.