JP2003326652A - Laminated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated film which is excellent in gas barrier properties under high humidity and the property of bonding of a coating film to a base material, more specifically, excellent in heat sealability and water-vapor barrier properties. <P>SOLUTION: This laminated film, in which a barrier layer (layer B) and a heat seal layer (layer C) are formed at least on one side of a resin base layer (layer A) in this order, is characterized as follows: the layer B contains a water-soluble polymer and montmorillonite containing an exchangeable cation except a sodium ion; and the content of an element for forming the exchangeable cation except the sodium ion in the B layer is 0.1 wt.% or more. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film excellent in gas barrier property under high humidity and adhesion between a coating film and a substrate, and more particularly to a laminated film excellent in heat sealability. Is.

[0002]

[Prior Art] Some sweets (gum, chocolate, etc.)
After being placed in a paper box, cigarettes and cigarettes are wrapped in a transparent film (PVDC-coated polypropylene, etc.) based on a biaxially oriented polypropylene film with aroma and moisture-proof property so as not to impair the commercial value. . Since the contents of these overlapping packages often do not have sufficient strength, the heat-sealing conditions are generally lower temperature and lower pressure than soft packaging such as ordinary bags.

As a characteristic of the film to be used, a film having a gas barrier property capable of preventing entry of outside air is desired because it cannot be stored for a long period of time due to alteration of the contents when oxygen or the like enters from the outside air. There is.

Japanese Unexamined Patent Publication No. 7-24980 has been proposed as an overlap film which has improved heat sealability at low temperatures by using a petroleum resin or a terpene resin, but still has insufficient aroma retention and gas barrier properties. Met.

In addition, oxygen barrier property and water vapor barrier property,
A gas barrier film in which inorganic layered particles and a coating film of a water-soluble polymer are laminated for the purpose of improving the fragrance retaining property is disclosed in JP-A-11-3.
It is proposed in Japanese Patent No. 33967 and Japanese Patent Laid-Open No. 11-335988. The films described therein are excellent in oxygen barrier property, but still have insufficient water vapor barrier property, and there is a problem that the adhesion between the barrier coating film and the substrate is deteriorated under high humidity. It was

[0006]

In view of the above situation, the present invention is to provide a laminated film having excellent gas barrier properties under high humidity and excellent adhesion between a coating film and a substrate. Aims to provide a laminated film having excellent heat-sealing properties and water vapor barrier properties.

[0007]

In order to solve the above problems, the present invention has the following constitution. That is, according to the present invention, in a laminated film in which a barrier layer (B layer) and a heat seal layer (C layer) are applied in this order on at least one surface of a resin base material layer (A layer), the B layer is a layer other than Na ions. A montmorillonite containing an exchangeable cation and a water-soluble polymer, and the content of an element forming an exchangeable cation other than Na ion in the B layer is 0.1% by weight or more. The laminated film is the main point.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The laminated film of the present invention comprises a barrier layer (B layer) on at least one side of a resin substrate layer (A layer),
The heat seal layer (C layer) needs to be a film laminated in this order. Further, the B layer needs to contain montmorillonite containing an exchangeable cation other than Na ion and a water-soluble polymer.

Further, the content of the element forming an exchangeable cation other than Na ion in the B layer needs to be 0.1% by weight or more. Preferably, the potassium element content in the B layer is 0.1% by weight or more and 5% by weight or less. By setting it as the said range, the oxygen gas barrier property in high humidity and the adhesiveness of a coating film and a base material can be improved.

Montmorillonite is generally composed of a layer in which Si ⁴⁺ is coordinated with O ²⁻ to form a tetrahedral structure and Al ³⁺ ,
Mg ²⁺ , Fe ²⁺ , Fe ³⁺ , Li ^+, etc. are coordinated with O ²⁻ and OH ⁻ to form an octahedral structure, and the layers are combined in a 2: 1 relationship to form a plate-like structure. Clay mineral that has the property of coordinating and absorbing water between ultra-thin unit crystal layers, and is formed as one plate-like particle by stacking one or several plate-like ultra-thin unit crystal layers. Is.

Further, montmorillonite has water molecules between the layers.
Having an exchangeable cation (also called an interlayer cation) with
ing. As the exchangeable cation, Mg is generally²⁺,
Ca ²⁺, Na⁺, K⁺, H⁺, And so on. Natural
In the case of montmorillonite, Na is used as an exchangeable cation.
Na-ion type montmorillonite containing a lot of on, and C
For Ca ion type montmorillonite containing a lot of a ions
Broadly divided.

The montmorillonite used in the present invention is
It is necessary that the montmorillonite contains exchangeable cations other than Na ions. Exchangeable cations other than Na ions include alkali metal ions other than Na ions, benzorukonium ions, alkyldimethylammonium ions, quaternized aminosilanes, and other quaternary cations.
Examples thereof include high grade alkyl ammonium ion or complex ion surfactants. These exchangeable cations can replace Na ions in montmorillonite.
In particular, replacement with K ions is preferable because the oxygen gas barrier property under high humidity and the adhesion between the coating film and the substrate can be improved.

The content of exchangeable cations other than Na ions in montmorillonite is preferably 10 meq or more per 100 g of montmorillonite. If the content of exchangeable cations other than Na ions is less than 10 (milliequivalent / 100 g), the montmorillonite may be inferior in the oxygen gas barrier property under high humidity and the adhesiveness between the coating film and the substrate.

The average particle size of montmorillonite is preferably 0.2 μm or less, more preferably 0.
If it is 1 μm or less, more preferably 0.05 μm or less, the adhesion is improved, and the average particle size is preferably 0.5 μm.
Or more, more preferably 1 μm or more, and further preferably 5
When it is at least μm, the gas barrier property is improved. Further, it is preferable that two or more kinds of montmorillonites having different average particle diameters are contained because these characteristics are compatible with each other.

Further, two or more kinds of montmorillonite having different exchangeable cations may be mixed. For example, Na-montmorillonite (montmorillonite having Na ions as interlayer ions) and K-montmorillonite (K
When using montmorillonite whose ion is an interlayer ion, the content of K-montmorillonite in montmorillonite is preferably 10 to 100% by weight, more preferably 90 to 100% by weight.

The water-soluble polymer used in the present invention is a water-soluble polymer. Specifically, it contains a polyvinyl alcohol polymer or a derivative thereof, a cellulose derivative such as carboxymethyl cellulose, hydroxyethyl cellulose, starches such as oxidized starch, etherified starch, dextrin, polyvinylpyrrolidone, and polar groups such as sulfoisophthalic acid. Copolymerized polyesters, vinyl polymers such as polyhydroxyethyl methacrylate or its copolymers, acrylic polymers, urethane polymers, ether polymers or carboxyl groups, amino groups, methylol groups of these various polymers Preferable examples include functional group-modified polymers. Above all,
A polyvinyl alcohol polymer or a derivative thereof is more preferable, and a polyvinyl alcohol having a saponification degree of 80 mol% or more and a copolymerized polyvinyl alcohol having a vinyl alcohol unit of 60 mol% or more are particularly preferable.

The degree of polymerization of the polyvinyl alcohol polymer or its derivative is not particularly limited, but it is 100.
-5000 are preferable, 200-2500 are more preferable, 400-1800 are especially preferable. Degree of polymerization is 10
If it is less than 0, the strength of the coating film may be insufficient, and if it exceeds 5000, the viscosity of the coating material when forming the coating film becomes too high, and a uniform coating film may not be formed.

The mixing ratio of montmorillonite in the layer B in the present invention is preferably 1 to 60% by weight, and 10 to 10% by weight.
50% is more preferable. When the mixing ratio of montmorillonite is within this range, both gas barrier properties and adhesiveness can be enhanced.

In the laminated film of the present invention, B
By setting the content of the potassium element in the layer to 0.1 to 5% by weight, the oxygen gas barrier property under high humidity and the adhesion between the coating film and the substrate can be enhanced.

The thickness of the layer B in the present invention is preferably 0.01 to 10 μm from the viewpoint of gas barrier properties.

The layer B used in the present invention may contain various additives in an amount of 30% or less by weight, as long as the gas barrier properties and transparency are not impaired. The various additives include antioxidants, weathering agents, heat stabilizers, lubricants, crystal nucleating agents, ultraviolet absorbers, colorants and the like. Also,
As long as the transparency and gas barrier properties are not impaired,
20% or less by weight of inorganic or organic particles may be contained. For example, calcium carbonate, titanium oxide, silicon oxide, calcium fluoride, lithium fluoride, alumina,
Examples thereof include barium sulfate, zirconia, calcium phosphate, and crosslinked polystyrene particles.

The resin substrate layer (A used in the present invention
(Layer), for example, polyolefin such as polyethylene and polypropylene, polyethylene terephthalate,
Polybutylene terephthalate, polyethylene-2,6-
Polyester such as naphthalate, polyamide such as nylon 6 and nylon 12, polyvinyl chloride, ethylene vinyl acetate copolymer or saponified product thereof, polystyrene, polycarbonate, polysulfone, polyphenylene oxide, polyphenylene sulfide, aromatic polyamide, polyimide, polyamideimide, Films such as cellulose, cellulose acetate, polyvinylidene chloride, polyacrylonitrile, polyvinyl alcohol and the like, and copolymers thereof are included. From the viewpoints of transparency, gas barrier properties, etc., a film using polyester such as polyethylene terephthalate or polyolefin such as polyethylene or polypropylene is particularly preferable. A film using a polyolefin such as polyethylene or polypropylene is particularly preferable because it has excellent water vapor barrier properties.

Further, the layer A is made of crystalline polypropylene 7
Polypropylene in which 0% by weight or more and 95% by weight or less is mixed with 5% by weight or more and 30% by weight or less of one or more kinds selected from a petroleum resin substantially not containing a polar group and a terpene resin substantially not containing a polar group. It is particularly preferable that the film is a film because a higher water vapor barrier property can be obtained.

Before forming the B layer, the resin base material layer is more preferably subjected to surface treatment such as corona discharge treatment, flame treatment, or plasma treatment.

The film used for the resin base material layer may be unstretched, uniaxially stretched or biaxially stretched, but from the viewpoint of dimensional stability and mechanical properties, a biaxially stretched film is particularly preferable. In addition, the resin base material used may contain various additives. For example, antioxidants, weathering agents,
Examples include heat stabilizers, lubricants, crystal nucleating agents, ultraviolet absorbers, colorants, antistatic agents and the like. Further, inorganic or organic particles may be contained as long as the transparency is not impaired. For example, talc, kaolinite, calcium carbonate, titanium oxide, silicon oxide, calcium fluoride, lithium fluoride, alumina, barium sulfate, zirconia, mica, calcium phosphate, crosslinked polystyrene-based particles and the like. The average particle size of the particles is preferably 0.001 to 10 μm.
m, and more preferably 0.003 to 5 μm. The average particle size is 10,000 using a transmission microscope.
It is the particle diameter obtained by taking a photograph of up to 100,000 times and averaging the photographs.

The resin base material layer is preferably transparent. The light transmittance is preferably 40% or more, more preferably 60% or more. Further, the resin base material layer is preferably smooth. The thickness of the resin base material layer is not particularly limited, but is preferably 2 to 1000 μm.

Further, as the resin substrate layer, a film having heat sealability on at least one side may be used.

Further, since the adhesion of the B layer is improved,
It is more preferable that an anchor coat layer is formed on the A layer using an anchor treatment agent such as urethane resin, epoxy resin, or polyethyleneimine, and a barrier layer (B layer) is formed on the anchor coat layer. The thickness of the anchor coat layer is not particularly limited, but is preferably 0.1 to 0.3 μm.

In the present invention, the heat seal layer (C layer)
The material used for is not particularly limited as long as it is a thermoplastic material that exhibits adhesiveness with the barrier layer. Examples thereof include polyester resins, polyurethane resins, polyvinyl acetate resins, acrylic resins, styrene-butadiene rubber resins, and the like, and copolymers thereof.

As the polyester resin, specifically,
Examples include copolymers of dicarboxylic acids such as terephthalic acid and isophthalic acid, aliphatic carboxylic acids such as adipic acid and sebacic acid, and diols such as ethylene glycol, 1,4-butanediol, diethylene glycol and neopentyl glycol. To be These may be used alone or in combination of two or more.

Any acrylic resin may be used as long as it exhibits a sufficient adhesive force during heat sealing. For example, as the constituent monomer of the acrylic resin, for example, styrene, ethyl methacrylate, methyl methacrylate, acrylonitrile, methyl acrylate, ethyl acrylate, butyl acrylate, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, hydroxy. It can be arbitrarily selected from ethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, etc., including an acrylic component.

When an acrylic resin is used as a material for the heat-sealing layer, a curing agent may be used in combination to improve the adhesion to the polyester film as the base material. Examples of the curing agent include an aqueous emulsion of a polycarbodiimide resin containing a carbodiimide group. These may be used alone or in combination of two or more.

The material forming the heat seal layer is
In order to improve the adhesion to the barrier layer, it may be crosslinked with a curing agent such as isocyanate.
The curing agent may be used alone or in combination of two or more. The mixing amount of the curing agent is not particularly limited, but preferably the resin component 1 constituting the heat seal layer
The amount is preferably 1 to 20 parts by weight, more preferably 2 to 10 parts by weight, relative to 00 parts by weight. If the compounding amount of the curing agent is less than 1 part by weight, it is difficult to obtain the compounding effect of the curing agent, and if it is more than 20 parts by weight, the heat sealing start temperature becomes high.

As a material for forming the heat seal layer, it is preferable to add fine particles as an anti-blocking agent for preventing blocking, in addition to the resin as the main constituent material as described above. The fine particles include PMM
At least one kind of fine particles selected from A resin fine particles, silica fine particles, acrylic resin fine particles, and colloidal silica is preferable. The amount of the fine particles to be compounded is not particularly limited, but is preferably 0.1 to 1 part by weight, and more preferably 0.2 to 100 parts by weight of the resin as the main constituent material.
˜0.8 parts by weight, particularly preferably 0.4 to 0.6 parts by weight. If the amount of the fine particles is less than 0.1 part by weight, the effect of the compounding is insufficient, and if it exceeds 1 part by weight, the transparency of the film tends to decrease. The above antiblocking agents may be used alone or in combination of two or more.

The material constituting the heat seal layer may contain waxes in order to improve the slip property of the surface of the heat seal layer. Examples of the waxes include plant waxes typified by carnauba wax, animal waxes typified by lanolin, mineral oil waxes typified by ozokerite, artificial waxes including peat wax, and aliphatic typified by stearyl alcohol. It is selected from alcohol. The blending amount of the above waxes is not particularly limited, but it is preferably 0.2 to 2 parts by weight with respect to 100 parts by weight of the resin which is the main constituent material. If the compounding amount of waxes is less than 0.2 parts by weight, the effect of compounding is insufficient, and if it exceeds 2 parts by weight, heat sealability may be impaired.

The glass transition temperature or melting point of the thermoplastic material mainly constituting the heat seal layer is preferably 40.
℃ or more and 120 ℃ or less, more preferably 50 ℃ or more 1
It is preferably 00 ° C or lower. If the glass transition temperature or the melting point is less than 40 ° C, the film blocking phenomenon easily occurs when the heat-sealing films of the present invention are stacked or formed into a roll, and if it exceeds 120 ° C, heat sealing is performed. In some cases, the possible temperature range becomes higher, and the heat sealing processing speed becomes slower.

The thickness of the heat seal layer is not particularly limited, but it is preferably 0.5 μm or more and 3 μm or less, more preferably 1 μm or more and 3 μm or less in a dry state. When it exceeds 3 μm, the viscosity of the raw material forming the heat-sealing layer as a coating material becomes high and the coatability deteriorates. If the thickness is less than 0.5 μm, the heat seal strength may be insufficient, limiting the use.

Further, it is preferable to further provide an anchor coat layer between the barrier layer and the heat seal layer since the transparency of the laminated film is increased and the adhesion between the heat seal layer and the barrier layer is improved. As the anchor coat layer, a known anchor coat agent can be used as in the anchor coat layer between the barrier layer and the resin base material layer.

The laminated film of the present invention is preferably provided with an antistatic layer. The antistatic layer can be formed using a general antistatic agent. Examples of the antistatic agent include cationic, anionic, amphoteric and nonionic surfactants. The antistatic layer is
For example, the above antistatic agent may be added in an amount of 0.01 g / m 2 in a dry state.
Can be formed by coating on the ² or 1.0 g / m ² or less and so as to heat-seal layer (C layer). Further, instead of forming the antistatic layer, the heat seal layer may be formed by incorporating an antistatic agent in the heat seal agent.

The haze of the laminated film of the present invention is preferably 20% or less, and more preferably 3% or less for overlapping applications. If the haze exceeds 20%, it becomes difficult to confirm the color and shape of the content when used as a transparent packaging material.

The laminated film of the present invention is 40 ° C., 90%
From the viewpoint of gas barrier properties, it is preferable that the water vapor permeability under the RH environment is 2.0 g / m ² · d or less.

The temperature of the laminated film of the present invention is 40
A peel strength of 0.5 (N / cm) or more at the interface between the layer A and other layers at a temperature of 90 ° C and a humidity of 90% is excellent in airtightness when used as a packaging material for foods and drugs. It is preferable because it provides a packaging material with high reliability in storage stability.

When the laminated film of the present invention is used as a packaging material, the laminated film may be used alone,
It may be laminated with other materials. The other material is not particularly limited as long as it is a commonly used material, and paper, aluminum, a metal such as silicon or an oxide thereof, a non-woven fabric,
Resin films and the like can be mentioned. Here, as the resin film, an unstretched or biaxially stretched film, a coextrusion film, a coating film, a vapor deposition film, a melt extrusion resin, etc. are used, and the raw material thereof is a polyolefin such as polyethylene or polypropylene, polyethylene terephthalate, polybutylene. Polyester such as terephthalate and polyethylene-2,6-naphthalate, polyamide such as nylon 6 and nylon 12, polyvinyl chloride,
Polyvinylidene chloride, polyvinyl acetate or saponified product thereof, ethylene vinyl acetate copolymer or saponified product thereof,
Polystyrene, aromatic polyamide, ionomer resin,
Examples thereof include polycarbonate, polysulfone, polyphenylene oxide, polyphenylene sulfide, polyimide, polyamide imide, cellulose, cellulose acetate, polyacrylonitrile, and copolymers thereof. The laminated structure is not particularly limited, and a printed layer, an adhesive layer, and an anchor layer may be provided between the laminated film of the present invention and another material.

Next, a typical production method of the laminated film of the present invention will be described, but the production method is not limited to the following.

The method for forming the coating film of the barrier layer (B layer) on the resin substrate layer is not particularly limited, but the constituents of the coating film can be applied to various solvents in that thin film coating can be performed at high speed. The dispersed solution is preferably subjected to gravure coating, reverse coating, spray coating, kiss coating, comma coating, die coating, knife coating, air knife coating or metalling bar coating. The resin base material layer is subjected to adhesion promoting treatment before coating, for example, in air, nitrogen gas, nitrogen /
It is more preferable to perform a corona discharge treatment under a mixed gas of carbon dioxide gas and other atmospheres, a plasma treatment under reduced pressure, a flame treatment, an ultraviolet treatment and the like. In addition, urethane resin,
It is more preferable to perform anchor treatment using an anchor treatment agent such as epoxy resin or polyethyleneimine.

When a biaxially stretched film of a polyester such as polyethylene terephthalate or a polyolefin such as polypropylene is used as the resin substrate layer, an off-line coat for coating after the biaxially stretched film forming process and a biaxially stretched film forming process Either method of in-line coating to coat inside may be used. When using an in-line coat, it is preferable to perform the coating before the film is heat-set. Here, heat setting means to crystallize the stretched film by heat-treating the film while keeping it at a temperature higher than the stretching temperature and lower than the melting point of the film. Therefore, since "before heat setting" means "before heat treatment", it is preferable to coat the film either unstretched, immediately after uniaxial stretching in the longitudinal direction or transverse direction, and immediately after biaxial stretching. Coating on the film immediately after uniaxial stretching is more preferable, and it is particularly preferable that the film is further stretched uniaxially or more and then heat-set.

As a method for drying the coating film forming the B layer, a hot roll contact method, a heat medium (air, oil, etc.) contact method, an infrared heating method, a microwave heating method, etc. can be used. Drying the coating film
From the viewpoint of gas barrier properties, 60 ° C. to 180 ° C. for offline coating and 80 ° C. for in-line coating.
It is preferably carried out within the range of 250 ° C., and the drying time is 1 to 60 seconds, preferably 3 to 30 seconds.

The coating material for forming the layer B is preferably a solution in which montmorillonite particles are uniformly dispersed or swollen in a solvent and a water-soluble polymer is uniformly dissolved. As the solvent, water or a water / lower alcohol mixed solution can be used, but it is more preferable to use a water / lower alcohol mixed solution.

The solid content concentration of the coating material for forming the layer B is 2.5 from the viewpoint of productivity such as viscosity of the coating material and drying efficiency.
% Or more is preferable. When using a low-concentration coating agent of less than 2.5%, a method of adding a low-boiling solvent having a high affinity for water and having high volatility to the solvent of the coating agent, and drying the coating film at a temperature higher than the boiling point of water. The method of performing is used.

Further, in order to improve the coating property, another water-soluble organic compound may be contained as the third component in the mixed solvent as long as the stability of the dispersion solution is maintained. Examples of the water-soluble organic compound include alcohols such as methanol, ethanol, n-propanol and isopropanol, glycols such as ethylene glycol and propylene glycol, glycol derivatives such as methyl cellosolve, ethyl cellosolve and n-butyl cellosolve, glycerin and wax. Polyhydric alcohols such as ethers, ethers such as dioxane, esters such as ethyl acetate,
Examples include ketones such as methyl ethyl ketone. Also,
The pH of the coating agent is preferably 2 to 11 from the viewpoint of solution stability.

The method for adjusting the coating material for forming the layer B is not particularly limited, but there is a method in which montmorillonite is uniformly dispersed in a solvent and then mixed with a solution in which a water-soluble polymer is uniformly dissolved in the solvent. Used effectively. It is preferable that the water-soluble polymer and montmorillonite are extremely uniformly dispersed in the coating agent. In particular, montmorillonite may have secondary agglomeration in the dispersion liquid, so after dispersing montmorillonite in a solvent, a shearing force, a shear mixer with a shear stress, a homomixer, a jet agitator, a ball mill, a kneader, a sand mill. A method of performing mechanical forced dispersion treatment using a device such as a triple roll is preferably used. For example, montmorillonite is uniformly dispersed in water at a concentration of several% by weight, and then dispersed using a homomixer or the like, and mixed with an aqueous solution of a water-soluble polymer uniformly dispersed in water at a concentration of several% by weight. A method in which the dispersion treatment is performed again later and the concentration is adjusted by adding a lower alcohol and water is preferably used. Further, the coating material may contain a crosslinking agent, particles and the like.

The method of forming the heat-sealing layer is not particularly limited, but a method of forming the heat-sealing layer by hot melt coating on the laminated film in which the barrier layer is previously formed on the film, or a method of forming the barrier layer on the laminated film in advance is formed. A method of providing a heat seal layer by coating a coating liquid in which the constituent components of the heat seal layer are dissolved / dispersed in a solvent. For example, the components of the heat seal layer may be coated on the substrate as an emulsion. The solvent for dissolving / dispersing the components constituting the heat-sealing layer may be appropriately selected depending on the material used, and examples thereof include organic solvents and water, and a mixture thereof may be used. Further, the molding conditions for forming the heat-sealing layer by using the co-extrusion method, the molding method, the coating method and the coating conditions when the heat-sealing layer is separately formed are not particularly limited, and generally used methods and conditions. Can be used.

In the present invention, the heat seal layer may be formed only on the barrier layer, or may be formed on both surfaces of the resin base material layer on which the barrier layer is not applied.

In the present invention, the heat-sealing layer is preferably formed on the entire surface on which the heat-sealing layer is formed, but may be formed only on a portion necessary for suitability as a packaging material. When the heat seal layer is partially formed, a method such as gravure printing using a general gravure printing machine can be used as a method for forming the heat seal layer.

The heat seal layer preferably has a heat seal strength of 20 g / 15 mm width or more. When the heat-sealing strength is less than 20 g / 15 mm width, the packaging suitability of the packaging material using the heat-sealable film of the present invention tends to decrease.

[0056]

EXAMPLES <Characteristic Evaluation Method> The characteristic evaluation method used in the present invention is as follows.

(1) Heat-sealing property Based on the measuring method of JIS K7-125, heat-sealing was performed under heat-sealing conditions, temperature of 100 ° C., pressure of 0.5 kg / cm ² , and sealing time of 1 second. Heat seal strength is
It was measured at a pulling speed of 300 mm / min and a pulling angle of 90 °.

(2) Water vapor barrier property According to JIS K-6782, the water vapor permeability was measured using a water vapor transmission rate measuring device (PERMATRAN, manufactured by MOCON). The measurement conditions are a temperature of 40 ° C. and a relative humidity of 90% RH.

(3) Gas Barrier Property The oxygen permeability was measured according to ASTM D-3985 using an oxygen permeability measuring device (OX-TRAN2 / 20, manufactured by MOCON). The measurement conditions are a temperature of 23 ° C. and a relative humidity of 80% RH.

(4) Adhesion between Coating Film and Substrate, Moisture-Resistant Peel Strength First, the laminated film of the present invention (referred to as OPP) and the unstretched polypropylene film (CPP, manufactured by Toray Synthetic Film Co., Ltd.) T3501, 50 μm) polyurethane adhesive (Dainippon Ink and Co., Ltd. "Dick Dry" LX-401A, SP-60, compounding ratio LX-4
01A: SP-60 = 10: 1, diluting solvent: ethyl acetate, drying temperature: 70 ° C., drying time: 30 seconds, coating amount: active ingredient of coating agent: 2.0 g / m 2 dry), and dry laminated, and 40 ° C. 48 Time aging. Next, a film having a width of 15 mm in the film width (TD) direction and a length of 10 cm in the longitudinal direction (MD) is sampled, and is sampled at 40 in a constant temperature and constant humidity tank.
Humidification and aging for 48 hours at 90 ° C. and 90% RH. Immediately after the completion of aging, the peel resistance of CPP and OPP was measured with a tensile tester (Autograph IM-100 type manufactured by Shimadzu Corporation).

(5) Haze Suga Tester Co., Ltd. Direct Read Haze Computer HGM-
Turbidity was measured by irradiating light from the surface on which the coating film was formed using 2DP.

(6) Cation exchange capacity clay handbook of montmorillonite 2nd edition (edited by The Japan Clay Society) 681-6
It was measured by the method described on page 84, "II Analysis / Test Edition 6. Analysis Method of Soil Clay Minerals 6.9 Ion Exchange Capacity Measurement".

(7) Exchangeable Cation Content of Montmorillonite Clay Handbook 2nd Edition (edited by The Japan Clay Society) 371-3
P. 72 Dry montmorillonite 100 g of which cation leaching amount was measured by the method described in "II Analysis and Test 1. Clay Minerals Analysis Method g. Ion Chromatography"
Na ion, K ion, and other various cations contained in the above were calculated as equivalents.

(8) Content of potassium element in coating film An amount necessary for measurement is cut out from the laminated film to obtain a measurement sample. After measuring the weight of the measurement sample, 10
The coating film was peeled from the substrate by immersing in water at 0 ° C., and the amount of potassium element was measured by using atomic absorption spectrometry. The substrate from which the coating film has been peeled off is dried and the weight is measured, and the weight of the coating film in the measurement sample is subtracted from the weight before the coating film is peeled off,
The content of potassium element in the coating film was calculated.

Example 1 As montmorillonite, montmorillonite having an average particle diameter of 1.0 μm (“Kunipia” manufactured by Kunimine Industries Co., Ltd., “Kunipia” -F, cation exchange capacity of 100 meq / 100 g) was dispersed in water to prepare an A1 liquid having a solid content concentration of 3% by weight. made. After adding potassium chloride whose amount of potassium is 1 times the cation exchange capacity of montmorillonite to the A1 solution to exchange some of the Na ions in the layers with K ions, the Na ions are replaced with K ions and discharged into the aqueous solution. To remove the residue, the solution was filtered using a filter paper, and the residue was washed with 1 liter of purified water for 5 g of montmorillonite solid content to prepare K-montmorillonite M1.

K-montmorillonite M1 was redispersed using water to a solid content concentration of 4% by weight to prepare an A2 solution. When the K ion leaching amount of montmorillonite in the A2 solution was measured, it was 81.1 meq / 100 g, and when the K ion leaching amount of montmorillonite in the A1 liquid was measured, it was 2.3 meq / 100 g.
The results are summarized in Table 1.

Next, the liquid A2 was further subjected to a mechanical dispersion treatment by a homomixer (rotation speed 3500 rpm) so as to eliminate the agglomerates of particles, to prepare the liquid A3.

As a water-soluble polymer, polyvinyl alcohol having a saponification degree of 98.0 mol% and a polymerization degree of 500 (hereinafter referred to as PV
Abbreviated as OH), water as a solvent, and a solid content concentration of 6.7
A B1 solution of weight% was prepared. Liquid B1 was dispersed again using a homomixer to prepare liquid B2.

Liquid A3 and liquid B2 were mixed in a weight ratio of liquid A3: liquid B2 = 42: 58, dispersed by a homomixer, and further 20 wt.% Of isopropyl alcohol (hereinafter referred to as IPA) was added to all solvents. %, And a coating material for the barrier layer was prepared so that the solid content concentration was 4.5% by weight.

As a heat-sealing agent, a polyvinyl acetate-modified resin ("Life Bond" Type H manufactured by Nieei Kako Co., Ltd.)
C-35), a solvent (mixture of water and isopropyl alcohol (hereinafter IPA) (mixing ratio is 1: 1 by volume)).
Were mixed to prepare an emulsion having a solid content concentration of 30% by weight.

Biaxially stretched polypropylene film treated by corona discharge as a resin base material ("Trefan" BO manufactured by Toray Industries, Inc.)
Type YB22, thickness 22μm), using a gravure coater (coating speed 150m / min), urethane adhesive (manufactured by Takeda Yakuhin Co., Ltd., main ingredient "Takelac" A3210,
Hardener "Takenate" A3070) was diluted with ethyl acetate and applied so that the film thickness after drying would be 0.2 μm, and it was introduced into a hot air drying dryer at 70 ° C. under low tension,
After drying for 5 seconds, an anchor coat layer was provided. After that, the coating material for the barrier layer is applied to the anchor coat surface so that the film thickness after drying is 0.5 μm, introduced into a hot-air drying dryer and dried at 120 ° C. for 10 seconds under low tension to be laminated. I made a film. Further, a urethane-based adhesive layer similar to the anchor layer between the resin base material and the barrier layer is provided in the same manner as the anchor layer, and the heat-sealing coating material is formed thereon to a film thickness of 1.0 μm. Thus, it was introduced into a hot air dryer and dried under low tension at 110 ° C. for 10 seconds to prepare a laminated film. The properties of the obtained laminated film are shown in Table 2. As shown in Table 2, the laminated film was excellent in water vapor barrier property, gas barrier property, adhesiveness, heat seal property and transparency.

Barrier layer coating film (layer B) of this laminated film
When the content of potassium element contained in is analyzed,
It was 0.5% by weight.

Example 2 To the A1 liquid of Example 1, potassium chloride having a potassium amount twice that of the cation exchange capacity of montmorillonite was added to exchange a part of Na ions in the layers with K ions. In order to remove Na ions replaced with K ions and discharged into the aqueous solution, filtration was performed using a filter paper, and the residue was washed with 1 liter of purified water for 5 g of montmorillonite solid content to prepare K-montmorillonite M2. A coating film was formed in the same manner as in Example 1 to prepare a laminated film. The properties of the obtained laminated film are shown in Table 2. As shown in Table 2, the laminated film was excellent in water vapor barrier property, gas barrier property, adhesiveness, heat seal property and transparency. When the content of potassium element contained in the B layer of this laminated film was analyzed, it was 1.1% by weight.

Comparative Example 1 A laminated film was prepared in the same manner as in Example 1 except that the interlayer ions of montmorillonite were not replaced with K ions. The properties of the obtained laminated film are shown in Table 2. Table 2
As shown in (1), there was a problem in gas barrier property and moisture resistance adhesion.

The content of potassium element contained in the coating film of this laminated film was analyzed and found to be 0.03% by weight.

Comparative Example 2 A laminated film having a barrier layer formed in the same manner as in Example 1 except that the heat seal layer was not provided was prepared. The heat-sealing property of the laminated film was similarly tested, but the film could not be sealed because the adhesive property was not developed.

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[Table 1]

[0078]

[Table 2]

[0079]

EFFECT OF THE INVENTION The laminated film obtained by the present invention is not only excellent in heat-sealing property, water vapor barrier property and gas barrier property even under high humidity, but also has high adhesion between the coating film and the substrate even under high humidity. Since it has, it can be used for many purposes as a packaging material.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F100 AC03B AC03K AK01A AK01B                       AK02A AK07A AK21B AL05A                       AR00B AR00C CA23B EJ65                       GB15 JA11A JB09B JD01B                       JD02 JD04 JK06 JL12 JL12C                       YY00 YY00A

Claims (9)

[Claims] 1. In a laminated film in which a barrier layer (B layer) and a heat seal layer (C layer) are formed in this order on at least one surface of a resin substrate layer (A layer), the B layer is an exchange other than Na ion. Of montmorillonite containing a water-soluble cation and a water-soluble polymer, and the content of an element forming an exchangeable cation other than Na ion in the B layer is 0.1.
A laminated film which is characterized in that the content is at least wt%. 2. The content of exchangeable cations other than Na ions in montmorillonite is 10 (milliequivalent / 100 g).
The laminated film according to claim 1, which is as described above. 3. The laminated film according to claim 1, wherein the exchangeable cation other than Na ion is K ion. 4. The potassium element content in the B layer is 0.1.
The laminated film according to any one of claims 1 to 3, wherein the content is from 5% by weight to 5% by weight. 5. The laminated film according to claim 1, wherein the water-soluble polymer is polyvinyl alcohol or its derivative. 6. The laminated film according to claim 1, wherein an anchor coat layer is laminated between the A layer and the B layer. 7. The layer A comprises, in 70% by weight or more and 95% by weight or less of crystalline polypropylene, at least one selected from petroleum resins substantially free of polar groups and terpene resins substantially free of polar groups. The laminated film according to any one of claims 1 to 6, which is a polypropylene film mixed in an amount of 5% by weight or more and 30% by weight or less. 8. The laminated film according to claim 1, which has a water vapor permeability of 2.0 g / m ² · d or less under an environment of 40 ° C. and 90% RH. 9. A under the environment of 40 ° C. and 90% RH
The peel strength at the interface between the layer and other layers is 0.5 N
/ Cm or more, The laminated film according to any one of claims 1 to 8.