WO2021230319A1 - Gas barrier film - Google Patents

Abstract

This gas barrier film comprises: a substrate the main component of which is propylene and a first surface of which has a surface hardness of 150 Mpa or less; a gas barrier layer formed on the first surface; and a coating layer formed on the gas barrier layer.

Description

Gas barrier film

The present invention relates to a gas barrier film and a method for producing a gas barrier film.
This application claims priority based on Japanese Patent Application No. 2020-0854335 filed in Japan on May 14, 2020, the contents of which are incorporated herein by reference.

In packaging materials used for packaging foods, non-foods, pharmaceuticals, etc., from the viewpoint of suppressing deterioration of the contents and maintaining their functions and properties, oxygen, water vapor, and other gases that change the contents that permeate the packaging materials. A gas barrier property that blocks water vapor may be required.
As a packaging material having a gas barrier property, a gas barrier film using a metal foil such as aluminum, which is less affected by temperature, humidity, etc., as a gas barrier layer is known.

As another configuration of the gas barrier film, a film in which a vapor-deposited film of an inorganic oxide such as silicon oxide or aluminum oxide is formed on a base film made of a polymer material by vacuum vapor deposition or sputtering is known (). For example, refer to Patent Document 1). These gas barrier films have transparency and gas barrier properties such as oxygen and water vapor.
As the base film, a film made of polyethylene terephthalate (PET) is often used.

Japanese Patent Application Laid-Open No. 60-49934

In recent years, there has been an increasing demand for gas barrier films using polypropylene (PP) or polyethylene (PE) base films from the viewpoint of suppressing the burden on the environment. Patent Document 1 also describes that a PP base film can be used.
However, the inventor's study has revealed that a gas barrier film in which a barrier layer is simply formed on a PP base film does not actually have sufficient resistance to hot water treatment such as boiling and retort.

The present invention has been made in view of the above circumstances, and provides a gas barrier film having high resistance to hot water treatment and suppressed environmental load.

The first aspect of the present invention is a substrate containing propylene as a main component and having a surface hardness of 150 MPa or less on the first surface, a gas barrier layer formed on the first surface, and a coating formed on the gas barrier layer. It is a gas barrier film provided with a layer.

According to the above aspect of the present invention, it is possible to provide a gas barrier film having high resistance to hot water treatment and suppressing environmental load.

It is a schematic sectional drawing of the gas barrier film which concerns on one Embodiment of this invention. It is a schematic cross-sectional view of the gas barrier film which concerns on embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a schematic cross-sectional view of the gas barrier film 1 according to the present embodiment. The gas barrier film 1 includes a base material 10, a pretreatment layer 10a, a gas barrier layer 30, a coating layer 40, an adhesive layer 50, and a sealant layer 60.

The base material 10 is a resin film containing propylene as a main component. The base material 10 may be either an unstretched film or a stretched film. When a stretched film is used, the stretch ratio is not particularly limited.
The thickness of the base material 10 is not particularly limited. The base material 10 can be a single-layer film or a multilayer film in which films having different properties are laminated in consideration of the use of the packaging material and the like. Considering the processability when forming the gas barrier layer 30, the coating layer 40 and the like, the thickness of the base material 10 is practically preferably in the range of 3 to 200 μm, particularly preferably 6 to 30 μm.
Each layer formed on the base material 10 may be formed on both sides of the base material 10.

The base material 10 has a core layer 12 formed of a propylene homopolymer, and a first skin layer 11 and a second skin layer 13 sandwiching the core layer 12. The first skin layer 11 constitutes the first surface of the base material 10. The second skin layer 13 constitutes the second surface (the surface opposite to the first surface) of the base material 10.
In the base material 10, the hardness of the first surface on the side where the gas barrier layer 30 is formed is 150 MPa or less. Hardness can be measured with a nano indenter. The nano indenter can simultaneously measure the load (force) and displacement (pushing distance) when the sample is pushed by the indenter, obtain the load displacement curve, and measure the composite elastic modulus and hardness. When the surface hardness of the base material 10 exceeds 150 MPa, the high crystallinity of propylene makes it easy to peel off inside the base material after hot water treatment, and the adhesion tends to decrease. Further, when the crystallinity is high, the surface shape tends to be rough, and it is difficult to form a dense barrier layer.

The melting point (surface melting point) of the first surface is preferably 155 ° C. or lower. Propylene having a surface melting point of more than 155 ° C. has high crystallinity, so that it is easily peeled off inside the base material after hot water treatment, and the adhesion is apt to decrease. Further, when the crystallinity is high, the surface shape tends to be rough, and it is difficult to form a dense gas barrier layer.
The surface melting point can be measured by a differential scanning calorimeter (DSC measurement) using a sample obtained by cutting the surface layer. DSC measurement is a method of measuring the temperature difference between the sample and the reference material as a function of temperature while changing the temperature of the sample part and the reference material by a constant program. The glass transition temperature, melting point, and crystallization of the sample. The temperature, the amount of heat of fusion, etc. can be obtained.

The softening temperature (surface softening temperature) of the first surface is preferably 160 ° C. or lower. Propylene having a softening temperature of more than 160 ° C. has high crystallinity, so that it is easy to peel off inside the base material after hot water treatment, and the adhesion is apt to decrease. Further, when the crystallinity is high, the surface shape tends to be rough, and it is difficult to form a dense gas barrier layer.
The surface softening temperature can be measured by nanothermal analysis (nano TA). The nano TA is a device that raises the temperature of the sample surface by heating the cantilever of a scanning probe microscope (SPM), detects the height displacement of the cantilever due to the expansion and softening of the sample, and obtains the softening temperature.

Polypropylene or polyethylene can be used for the base material 10, and it can be a single layer or a multilayer. In the case of a multi-layer structure, adhesiveness and slipperiness are applied to the surface layer of at least one of the first surface (the surface on the side forming the gas barrier layer) and the second surface (the opposite surface on the side forming the gas barrier layer) of the base material 10. , Blocking resistance, heat sealability and other functionality can be imparted. The thickness of the surface layer can be several tens of nm to several μm, and is appropriately selected depending on the function. When polypropylene is used for the base material 10, a propylene homopolymer may be used for the first surface of the base material 10. However, in order to improve the gas barrier property when the gas barrier layer is formed and the adhesiveness to the base material, the composition of the surface layer on the first surface is HDPE (high density polyethylene) at a ratio of 0.1 to several tens of percent with respect to propylene. ), MDPE (medium density polyethylene) LDPE (low density polyethylene), LLDPE (linear low density polyethylene) and other polyethylene copolymers may be used. Further, it is possible to obtain a multimer obtained by copolymerizing at least one of an α-olefin resin such as 1-butene and a rubber component such as an elastomer at a ratio of 0.1 to several tens of percent with respect to propylene or ethylene. .. Further, each resin may be mixed and dispersed instead of copolymerization. PVA (polyvinyl alcohol) or EVOH (ethylene vinyl alcohol copolymer) may be used for the surface layer of the first surface and / or the second surface in order to further enhance the gas barrier property. When the base material 10 has a multi-layer structure, the material can be co-extruded using a plurality of screws to form a multi-layer film. The substrate 10 formed as described above cannot clearly confirm the boundary between the core layer and each skin layer even when observed with an optical microscope, but after appropriately dyeing, the cross section is subjected to a transmission electron microscope (TEM). The boundary of each layer can be confirmed by observing with.

The second skin layer 13 may be the same propylene homopolymer resin layer as the core layer 12, or the parameters may be controlled in the same manner as the first skin layer 11. When the material of the second skin layer 13 is the same as that of the core layer 12, the base material 10 is substantially composed of the core layer 12 and the first skin layer 11, and the core layer constitutes the second surface.
When the surface hardness of the second surface is 150 MPa or less, the surface softening temperature is 160 ° C or less, and the surface melting point is 155 ° C or less, when forming a gas barrier layer, a printing layer, etc. on the second surface side, dry laminating or extruded laminating Therefore, high adhesion can be obtained when the second base material 20 is bonded (see FIG. 2). The second base material 20 is not particularly limited as long as it is polyolefin-based, and a known film can be used.
Since the boundary between the core layer and each skin layer cannot be clearly confirmed even when the substrate 10 formed as described above is observed with an optical microscope, the cross section is subjected to a transmission electron microscope (TEM) after being appropriately stained. The boundary of each layer can be confirmed by observing with.

The skin layers 11 and 13 may contain additives that are not resin components. The additive can be appropriately selected from various known additives. Examples of additives include anti-blocking agents (AB agents), heat-resistant stabilizers, weather-resistant stabilizers, ultraviolet absorbers, lubricants, slip agents, nucleating agents, antistatic agents, anti-fog agents, pigments, dyes and the like. .. The AB agent may be either organic or inorganic. Any one of these additives may be used alone, or two or more thereof may be used in combination. Of the above, lubricants and slip agents are preferable from the viewpoint of processing suitability. The content of the additive in the base material 10 can be appropriately adjusted as long as the effect of the present invention is not impaired.
When these additives maintain a granular state in the base material 10, excessive protrusion onto the base material 10 causes minute defects in the gas barrier layer 30 and the coating layer 40. In the study of the inventor, it was found that the fine particles made of a material other than polypropylene protruding on the first surface have a smaller average particle size, and the smaller the number, the better the barrier property. An example of a predetermined value is 30 or less per ^{1 mm 2} for fine particles having an average particle diameter of 1 μm or more.
If the average particle size of the fine particles is 1 μm or more and the number of the fine particles exceeds 30, the barrier property may be deteriorated. Therefore, it is preferable that the average particle size is small and the number is small.
When the protruding height of the fine particles on the surface of the base material 10 is 1 μm or less, a barrier film with few defects can be formed, which is preferable. The number and height of the protruding fine particles can be adjusted by adjusting the composition of the skin layer and the processing conditions of the base material.

The pretreatment layer 10a is a coating layer made of any one of a thermoplastic resin, a thermosetting resin, an ultraviolet curable resin and the like, or a treatment of any one of corona treatment, plasma treatment, ion beam treatment, ozone treatment, flame treatment and the like. Can be a layer. By forming the pretreatment layer, it is possible to improve the barrier property by surface smoothness and impart adhesion. If the surface smoothness is high, a dense film can be formed, so that sufficient barrier properties can be obtained even if the film thickness of the gas barrier layer 30 is thin.
The pretreatment layer 10a has an effect of enhancing the adhesion between the base material 10 and the gas barrier layer 30, but may be omitted if the adhesion, the barrier property, etc. are sufficient.
When the pretreatment layer 10a is provided, the parameters of the first surface of the base material 10 can be measured by removing the pretreatment layer.

The gas barrier layer 30 is a composite component containing metallic aluminum, aluminum oxide, silicon oxide, silicon nitride, silicon carbide or any of them as a main component, and exhibits a barrier property against a predetermined gas such as oxygen and water vapor. Is. The gas barrier layer 30 may be transparent or opaque.

The thickness of the gas barrier layer 30 varies depending on the type, composition, and film forming method of the inorganic compound used, but is generally set appropriately within the range of 3 to 300 nm. If the thickness of the gas barrier layer 30 is less than 3 nm, a uniform film may not be obtained or the film thickness may not be sufficient, and the function as a gas barrier layer may not be sufficiently exhibited. If the thickness of the gas barrier layer 30 exceeds 300 nm, the gas barrier layer 30 becomes hard, and there is a possibility that the gas barrier layer 30 may be cracked and lose its barrier property due to external factors such as bending and pulling after film formation. The thickness of the gas barrier layer 30 is preferably in the range of 6 to 150 nm.

The method for forming the gas barrier layer 30 is not limited, and for example, a vacuum vapor deposition method, a plasma activated vapor deposition method, a sputtering method, an ion plating method, an ion beam vapor deposition method, a plasma vapor deposition (CVD) method, or the like can be used.

The coating layer 40 further enhances the barrier property of the gas barrier layer 30. As the coating layer 40, a coating layer such as a thermoplastic resin, a thermosetting resin, an ultraviolet curable resin, a metal alkoxide, or a water-soluble polymer can be used. In particular, metal alkoxides having excellent oxygen barrier properties and water-soluble polymers are preferable. It is formed using an aqueous solution containing a water-soluble polymer and one or more metal alkoxides or a hydrolyzate thereof, or a coating agent containing a mixed solution of water and an alcohol as a main component. For example, a coating agent is prepared by dissolving a water-soluble polymer in an aqueous (water or a mixture of water and alcohol) solvent and directly or preliminarily hydrolyzing the metal alkoxide. The coating layer 40 can be formed by applying this coating agent on the gas barrier layer 30 and then drying it.

Each component contained in the coating agent for forming the coating layer 40 will be described in more detail. Examples of the water-soluble polymer used for the coating agent include polyvinyl alcohol (PVA), polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate and the like. In particular, PVA is preferable because excellent gas barrier properties can be obtained. PVA is generally obtained by saponifying polyvinyl acetate. As the PVA, either a so-called partially saponified PVA in which several tens of percent of acetic acid groups remain, or a complete PVA in which only a few percent of acetic acid groups remain can be used. PVA in between the two may be used.

The metal alkoxide used in the coating agent is a compound represented by a general formula, M (OR) n (metal of M: Si, Al, alkyl group such as _{R: CH 3,} C ₂ H _5). Specific examples thereof include tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ] and triisopropoxyaluminum Al [OCH (CH ₃ ) ₂ ] ₃ . Examples of the silane coupling agent include those having an epoxy group such as 3-glycidoxypropyltrimethoxysilane, those having an amino group such as 3-aminopropyltrimethoxysilane, and mercapto groups such as 3-mercaptopropyltrimethoxysilane. Examples thereof include those having an isocyanate group such as 3-isocyanapropyltriethoxysilane, tris- (3-trimethoxysilylpropyl) isocyanurate and the like.

(Polycarboxylic acid polymer (A))
The polycarboxylic acid-based polymer is a polymer having two or more carboxy groups in the molecule. Examples of the polycarboxylic acid-based polymer include (co) polymers of ethylenically unsaturated carboxylic acids; copolymers of ethylenically unsaturated carboxylic acids and other ethylenically unsaturated monomers; alginic acid and carboxymethyl cellulose. , Pectin and the like, acidic polysaccharides having a carboxyl group in the molecule can be mentioned.
Examples of the ethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid.
Examples of the ethylenically unsaturated monomer copolymerizable with the ethylenically unsaturated carboxylic acid include saturated carboxylic acid vinyl esters such as ethylene, propylene and vinyl acetate, alkyl acrylates, alkyl methacrylates and alkyl itaconates. Kind, vinyl chloride, vinylidene chloride, styrene, acrylamide, acrylonitrile and the like.
These polycarboxylic acid-based polymers may be used alone or in combination of two or more.

Among the above, at least one polymerizable simple substance selected from the group consisting of acrylic acid, maleic acid, methacrylic acid, itaconic acid, fumaric acid and crotonic acid from the viewpoint of the gas barrier property of the obtained gas barrier film. Polymers containing structural units derived from merits are preferred, and weights comprising structural units derived from at least one polymerizable monomer selected from the group consisting of acrylic acid, maleic acid, methacrylic acid and itaconic acid. Coalescence is particularly preferred.
In such a polymer, the proportion of the structural unit derived from at least one polymerizable monomer selected from the group consisting of acrylic acid, maleic acid, methacrylic acid and itaconic acid is 80 mol% or more. Is preferable, and 90 mol% or more is more preferable (however, the total of all the constituent units constituting the polymer is 100 mol%).
The polymer may be a homopolymer or a copolymer.
When the polymer is a copolymer containing a structural unit other than the above-mentioned structural unit, the other structural unit may be, for example, an ethylenically unsaturated monomer copolymerizable with the above-mentioned ethylenically unsaturated carboxylic acid. Examples include structural units derived from.

The number average molecular weight of the polycarboxylic acid-based polymer is preferably in the range of 2,000 to 10,000,000, more preferably 5,000 to 1,000,000. If the number average molecular weight is less than 2,000, the obtained gas barrier film cannot achieve sufficient water resistance, and moisture may deteriorate the gas barrier property and transparency, or whitening may occur. On the other hand, if the number average molecular weight exceeds 10,000,000, the viscosity of the coating agent when forming the film 25 becomes high, and the coatability may be impaired.
The number average molecular weight is a polystyrene-equivalent number average molecular weight determined by gel permeation chromatography (GPC).

When the coating agent containing the polycarboxylic acid polymer (A) as a main component is applied and dried to form the A film and then the B film is formed, the polycarboxylic acid polymer is one of the carboxy groups. The portion may be neutralized with a basic compound in advance. By neutralizing a part of the carboxy group of the polycarboxylic acid polymer in advance, the water resistance and heat resistance of the A film can be further improved.
As the basic compound, at least one basic compound selected from the group consisting of a polyvalent metal compound, a monovalent metal compound and ammonia is preferable.
As the polyvalent metal compound, the compound exemplified in the description of the polyvalent metal compound (B) described later can be used. Examples of the monovalent metal compound include sodium hydroxide, potassium hydroxide and the like.

Various additives can be added to the coating agent containing the polycarboxylic acid polymer (A) as the main component, and a cross-linking agent, a curing agent, a leveling agent, a defoaming agent, and an anti-blocking agent can be added as long as the barrier performance is not impaired. , Antistatic agents, dispersants, surfactants, softeners, stabilizers, film-forming agents, thickeners and the like.

The solvent used for the coating agent containing the polycarboxylic acid-based polymer (A) as a main component is preferably an aqueous medium. Aqueous media include water, water-soluble or hydrophilic organic solvents, or mixtures thereof. Aqueous media usually contain water or water as the main component.
The content of water in the aqueous medium is preferably 70% by mass or more, more preferably 80% by mass or more.
Examples of the water-soluble or hydrophilic organic solvent include alcohols such as methanol, ethanol and isopropanol, ketones such as acetone and methyl ethyl ketone, ethers such as tetrahydrofuran, cellosolves, carbitols, and ditrils of acetonitrile. Can be mentioned.

(Multivalent metal compound (B))
The polyvalent metal compound is not particularly limited as long as it is a compound that reacts with the carboxyl group of the polycarboxylic acid-based polymer to form a polyvalent metal salt of the polycarboxylic acid. For example, zinc oxide particles, magnesium oxide particles, magnesium methoxydo, copper oxide, calcium carbonate and the like can be mentioned. These may be used alone or in admixture of a plurality. Zinc oxide is preferable from the viewpoint of the oxygen barrier property of the oxygen barrier film.

Zinc oxide is an inorganic material capable of absorbing ultraviolet rays, and the average particle size of zinc oxide particles is not particularly limited. However, from the viewpoint of gas barrier property, transparency, and coating suitability, the average particle size is preferably 5 μm or less, more preferably 1 μm or less, and particularly preferably 0.1 μm or less. The

When a coating agent containing the polyvalent metal compound (B) as a main component is applied and dried to form a B film, if necessary, in addition to the zinc oxide particles, as long as the effect of the present invention is not impaired, Various additives may be contained. Examples of such additives include resins that are soluble or dispersible in the solvent used for the coating agent, dispersants that are soluble or dispersible in the solvent used for the coating agent, surfactants, softeners, stabilizers, and film-forming agents. , Thickener and the like may be contained.
Among the above, it is preferable to contain a resin that is soluble or dispersible in the solvent used for the coating agent. This improves the coatability and film-forming property of the coating agent. Examples of such resins include alkyd resins, melamine resins, acrylic resins, urethane resins, polyester resins, phenol resins, amino resins, fluororesins, epoxy resins, isocyanate resins and the like.
Further, it is preferable to contain a dispersant that is soluble or dispersible in the solvent used for the coating agent. This improves the dispersibility of the polyvalent metal compound. As such a dispersant, an anionic surfactant or a nonionic surfactant can be used. Examples of the surface active agent include (poly) carboxylate, alkyl sulfate ester salt, alkylbenzene sulfonate, alkylnaphthalene sulfonate, alkyl sulphosuccinate, alkyldiphenyl ether disulfonate, alkyl phosphate, aromatic phosphorus. Acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, polyoxyethylene alkyl ester, alkylallyl sulfate ester salt, polyoxyethylene alkyl phosphate ester, sorbitan alkyl ester, glycerin fatty acid ester, sorbitan fatty acid ester, citrus fatty acid ester , Polyethylene glycol fatty acid ester, polyoxyethylene sorbitan alkyl ester, polyoxyethylene alkyl allyl ether, polyoxyethylene derivative, polyoxyethylene sorbitol fatty acid ester, polyoxy fatty acid ester, polyoxyethylene alkylamine and other various surfactants. .. These surfactants may be used alone or in combination of two or more.

When the coating agent containing the polyvalent metal compound (B) as a main component contains an additive, the mass ratio of the polyvalent metal compound to the additive (polyvalent metal compound: additive) is 30 :. It is preferably in the range of 70 to 99: 1, and preferably in the range of 50:50 to 98: 2. The

Examples of the solvent used for the coating agent containing the polyvalent metal compound (B) as a main component include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol and dimethylsul. Examples thereof include foxide, dimethylformamide, dimethylacetamide, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, dioxane, tetrahydrofuran, ethyl acetate and butyl acetate. In addition, these solvents may be used alone or in combination of two or more.
Among these, methyl alcohol, ethyl alcohol, isopropyl alcohol, toluene, ethyl acetate, methyl ethyl ketone and water are preferable from the viewpoint of coatability. Further, from the viewpoint of manufacturability, methyl alcohol, ethyl alcohol, isopropyl alcohol and water are preferable.

When a coating agent in which a polycarboxylic acid-based polymer (A) and a polyvalent metal compound (B) are mixed is applied and dried to form a polyvalent metal salt film of the polycarboxylic acid, the above-mentioned polycarboxylic acid-based Using the polymer (A), the above-mentioned polyvalent metal compound (B), and water or alcohol as a solvent, a resin or dispersant that can be dissolved or dispersed in the solvent, and an additive if necessary are mixed. A polycarboxylic acid polyvalent metal salt film can be formed by applying and drying the mixture as a coating agent by a known coating method.

There are no restrictions on the coating agent application method, and conventionally known methods such as a commonly used dipping method, roll coating method, screen printing method, spray method, and gravure printing method can be appropriately selected.

The thickness of the coating layer 40 varies depending on the composition of the coating agent, the coating conditions, and the like, and is not particularly limited. However, if the film thickness of the coating layer 40 after drying is 0.01 μm or less, a uniform coating film may not be obtained and sufficient gas barrier properties may not be obtained. If the film thickness after drying exceeds 50 μm, cracks are likely to occur in the coating film 40. Therefore, the suitable thickness of the coating layer 40 is, for example, in the range of 0.01 to 50 μm. The optimum thickness of the coating layer 40 is, for example, in the range of 0.1 to 10 μm.

The sealant layer 60 is a layer bonded by heat fusion when forming a bag-shaped package or the like using the gas barrier film 1. As the material of the sealant layer 60, polyethylene, polypropylene, an ethylene-vinyl acetate copolymer, an ethylene-methacrylate copolymer, an ethylene-methacrylate copolymer, an ethylene-acrylic acid copolymer, and an ethylene-acrylic acid ester can be used. Examples of resin materials such as polymers and their metal crosslinked products can be exemplified. The thickness of the sealant layer 60 is appropriately determined, and is, for example, in the range of 15 to 200 μm.

The adhesive layer 50 joins the sealant layer 60 and the coating layer 40. By using the adhesive layer 50, the resin film to be the sealant layer 60 and the base material 10 on which the gas barrier layer 30 and the coating layer 40 are formed can be bonded by dry lamination. As the material of the adhesive layer 50, a two-component curable polyurethane-based adhesive can be exemplified.
A printing layer, an intervening film, a sealant layer, or the like can be laminated on the coating layer 4 to form a packaging material.

A method for producing the gas barrier film 1 of the present embodiment having the above configuration will be described.
First, the gas barrier layer 30 is formed on one surface of the base material 10 (first step). At this time, the pretreatment layer 10a may be formed on the base material 10 as needed.
Next, the above-mentioned coating agent is applied onto the gas barrier layer 30 and dried to form a coating layer 40 on the gas barrier layer (second step).
Further, when an adhesive is applied on the coating layer 40 and the resin film to be the sealant layer 60 is attached (third step), the gas barrier film 1 is completed.

The gas barrier film of this embodiment will be further described with reference to Examples and Comparative Examples. The present invention is not limited to the specific contents of Examples and Comparative Examples.

(Example 1)
As the base material 10, a polypropylene film (thickness 20 μm) having a core layer 12 and a first skin layer 11 was used.
The first skin layer 11 is formed of a resin made of a copolymer of polyethylene and propylene. The first surface has a surface hardness of 96.3 MPa, a surface melting point of 135 ° C., and a surface softening temperature of 125.8 ° C., and fine particles do not protrude (0 pieces / mm ² ).
The core layer 12 is made of a resin made of propylene homopolymer. The second surface has a surface hardness of 218.2 MPa, a surface melting point of 165 ° C., and a surface softening temperature of 231.8 ° C.
A mixture of silicon and silicon oxide was sublimated in a vacuum apparatus, and a gas barrier layer 30 (thickness 30 nm) made of silicon oxide (SiOx) was formed on the first skin layer 11 by an electron beam vapor deposition method.

A coating agent obtained by mixing the following liquids (1) and (2) at a mass ratio of 6: 4 was applied onto the gas barrier layer 30 by a gravure coating method and dried to form a coating layer 40 having a thickness of 0.4 μm. ..
Liquid (1): Hydrolyzed solution (2) _{with a solid content of 3 wt% (SiO 2} equivalent) obtained by adding 89.6 g of hydrochloric acid (0.1N) to 10.4 g of tetraethoxysilane and stirring for 30 minutes to hydrolyze. 3 wt% water / isopropyl alcohol solution of polyvinyl alcohol (water: isopropyl alcohol weight ratio 90:10)

Finally, using a two-component curable polyurethane adhesive, an unstretched polypropylene film (thickness 70 μm) is bonded onto the coating layer 40 by dry laminating to provide a sealant layer 60, and the gas barrier film of Example 1 is obtained. Obtained.

(Example 2)
As the substrate 10, the parameters of the first skin layer 11, the surface hardness 87.5MPa, surface melting 130 ° C., the surface softening temperature 114.5 ° C., polypropylene film silica fine particles are projected two / mm ² (thick A gas barrier film of Example 2 was prepared in the same manner as in Example 1 except that 20 μm) was used.

(Example 3)
As the substrate 10, the parameters of the first skin layer 11, the surface hardness 130.5MPa, surface melting 125 ° C., the surface softening temperature 104.0 ° C., polypropylene film silica fine particles are projected two / mm ² (thick A gas barrier film of Example 3 was prepared in the same manner as in Example 1 except that 20 μm) was used.

(Example 4)
As the base material 10, the parameters of the first skin layer 11 are a polypropylene film having a surface hardness of 108.6 MPa, a surface melting point of 146 ° C., a surface softening temperature of 141.0 ° C., and 3 silica fine particles / mm ² protruding (thickness). A gas barrier film of Example 4 was prepared in the same manner as in Example 1 except that 20 μm) was used.

(Example 5)
As the base material 10, the parameters of the first skin layer 11 are a polypropylene film having a surface hardness of 121.4 MPa, a surface melting point of 146 ° C., a surface softening temperature of 151.0 ° C., and 3 silica fine particles / mm ² protruding (thickness). A gas barrier film of Example 5 was prepared in the same manner as in Example 1 except that 20 μm) was used.

(Example 6)
Except for the fact that a polypropylene film (thickness 20 μm) having the same parameters as in Example 1 of the first skin layer 11 was used as the base material 10 except that the number of protrusions of the silica fine particles was 2 / mm ^2. The gas barrier film of Example 6 was produced in the same manner as in Example 1.

(Example 7)
Except for the fact that a polypropylene film (thickness 20 μm) having the same parameters as in Example 1 of the first skin layer 11 was used as the base material 10 except that the number of protrusions of the silica fine particles was 5 / mm ^2. The gas barrier film of Example 7 was produced in the same manner as in Example 1.

(Example 8)
Except for the fact that a polypropylene film (thickness 20 μm) having the same parameters as in Example 1 of the first skin layer 11 was used as the base material 10 except that the number of protrusions of the silica fine particles was 12 / mm ^2. The gas barrier film of Example 8 was produced in the same manner as in Example 1. On the surface of the skin layer, 12 silica fine particles / mm ^{2 were} observed.

(Example 9)
Except for the fact that a polypropylene film (thickness 20 μm) having the same parameters as in Example 1 of the first skin layer 11 was used as the base material 10 except that the number of protrusions of the silica fine particles was 23 / mm ^2. The gas barrier film of Example 9 was produced in the same manner as in Example 1.

(Example 10)
A pretreatment layer made of an acrylic urethane resin having a thickness of 50 nm adjusted so that the NCO / OH ratio of the hydroxyl group-containing acrylic resin and the isocyanate curing agent is 1.0 is provided on the first skin layer 11. The gas barrier film of Example 10 was prepared in the same manner as in Example 1 except that the thickness of the gas barrier layer 30 was 15 nm.

(Example 11)
The gas barrier film of Example 11 was produced in the same manner as in Example 1 except that the first skin layer 11 was subjected to glow discharge with Ar gas to provide a pretreatment layer having a modified surface chemical bond state.

(Example 12)
The same as in Example 1 except that HMDSO (hexamethyldisiloxane) was introduced into the vacuum apparatus instead of the gas barrier layer 30 described above to form a gas barrier layer (thickness 30 nm) made of SiOxCy by the plasma CVD method. The gas barrier film of Example 12 was prepared.

(Example 13)
_{Except for the fact that SiH 4} , NH ₃ , and N ₂ were introduced into the vacuum apparatus in place of the gas barrier layer 30 described above to form a gas barrier layer (thickness 30 nm) made of SiNx by the plasma CVD method. The gas barrier film of Example 13 was prepared in the same manner.

(Example 14)
Example 14 is an example having a second skin layer 13. The parameters of the second skin layer 13 were the same as those of the first skin layer 11 of Example 1. That is, the parameters on the second surface are the same as the parameters on the first surface.
The same as in Example 1 except that a biaxially stretched polypropylene film (thickness 20 μm) was bonded to the second skin layer side as a base material 20 by dry laminating using a two-component curable polyurethane adhesive. A gas barrier film of Example 14 was obtained (see FIG. 2).

(Example 15)
The gas barrier film of Example 15 was produced in the same manner as in Example 1 except that the thickness of the gas barrier layer 30 made of SiOx was 20 nm.

(Example 16)
The gas barrier film of Example 16 is the same as in Example 1 except that the gas barrier layer 30 is a gas barrier layer (thickness: 10 nm) made of AlOx having a film density of 1.8 g / cm ^{3 and a hydrogen concentration of 29.7 at%.} Was produced.

(Example 17)
The gas barrier film of Example 16 is the same as that of Example 10, except that the gas barrier layer 30 is a gas barrier layer (thickness: 10 nm) made of AlOx having a film density of 1.8 g / cm ^{3 and a hydrogen concentration of 29.7 at%.} Was produced.

(Example 18)
The gas barrier film of Example 17 was prepared in the same manner as in Example 11 except that the gas barrier layer 30 was a gas barrier layer (thickness 10 nm) made of AlOx having a film density of 1.8 g / cm ^{3 and a hydrogen concentration of 29.7 at%.} bottom.

(Example 19)
The same as in Example 1 except that the gas barrier layer 30 is a gas barrier layer (thickness 6 nm) made of AlOx having a film density of 2.6 g / cm ^{3 and a hydrogen concentration of 17.5 at% formed by a plasma activated vapor deposition method.} The gas barrier film of Example 17 was prepared.

(Example 20)
The same procedure as in Example 10 except that the gas barrier layer 30 is a gas barrier layer (thickness 6 nm) made of AlOx having a film density of 2.6 g / cm ^{3 and a hydrogen concentration of 17.5 at% formed by a plasma activated vapor deposition method.} The gas barrier film of Example 17 was prepared.

(Example 21)
The same as in Example 11 except that the gas barrier layer 30 is a gas barrier layer (thickness 6 nm) made of AlOx having a film density of 2.6 g / cm ^{3 and a hydrogen concentration of 17.5 at% formed by a plasma activated vapor deposition method.} The gas barrier film of Example 17 was prepared.

(Comparative Example 1)
As the base material, a polypropylene film (thickness 20 μm) in which the material of the first skin layer 11 was the same as that of the core layer 12 was used. As a result, the parameters of the first skin layer 11 were a surface hardness of 218.2 MPa, a surface melting point of 165 ° C., and a surface softening temperature of 231.5 ° C., which were the same as those of the second surface.
In other respects, a gas barrier film of Comparative Example was prepared in the same manner as in Example 1.

(Comparative Example 2)
A gas barrier film of Comparative Example 2 was prepared in the same manner as in Comparative Example 1 except that an AlOx film having a film density of 2.4 g / cm ^{3 and a hydrogen concentration of 26.5 at% was formed as the gas barrier layer 30.}

(Comparative Example 3)
Except for the fact that a polypropylene film (thickness 20 μm) having the same parameters as in Example 1 of the first skin layer 11 was used as the base material 10 except that the number of protrusions of the silica fine particles was 35 / mm ^2. A gas barrier film of Comparative Example 3 was prepared in the same manner as in Example 1.

(Comparative Example 4)
Except for the fact that a polypropylene film (thickness 20 μm) having the same parameters as in Example 16 of the first skin layer 11 was used as the base material 10 except that the number of protrusions of the silica fine particles was 35 / mm ^2. A gas barrier film of Comparative Example 4 was prepared in the same manner as in Example 16.

The surface hardness of the base material according to each example was measured by "TI Premier" manufactured by Bruker. The hardness was calculated by applying a load and unloading an indenter to the outermost layer of the substrate of each example at 20 ° C. at a speed of 100 nm / sec.

The softening temperature of the base material according to each example was measured using SPM (MPF-3D-SA) manufactured by Oxford Instruments. The cantilever was brought into contact with the substrate and heated, and the cantilever was lifted by thermal expansion of the surface accompanying the temperature rise, and then the peak of the displacement in which the cantilever was lowered by softening was determined as the softening temperature.

The evaluation items and measurement methods in each Example and Comparative Example are shown below.
(Evaluation of gas barrier layer adhesion after hot water treatment)
Two gas barrier films of each example were laminated with the sealant layers facing each other, and the three sides were joined by heat fusion to prepare a pouch (packaging container) of each example. After filling the pouches of each example with water as a content, one open side was sealed by heat fusion. Then, as hot water treatment, retort sterilization treatment (121 ° C. for 30 minutes) was performed.
After hot water treatment, a test piece was cut out from the part that was in contact with the contents of the pouch of each example in accordance with JIS K 6854-2 and JIS K 6854-3, and the Orientech Tencilon universal testing machine RTC-1250 was used. The peel strength of the gas barrier layer 30 measured using the above was measured as an index of adhesion. Two types of measurement, T-shaped peeling and 180 ° peeling, were performed under normal conditions (Dry) and measurement site wetness (Wet), respectively. If the base material was broken before peeling, it was regarded as "base material cut". "Out of base material" means that the base material and the gas barrier layer are sufficiently in close contact with each other.

(Evaluation of gas barrier performance immediately after production and after hot water treatment)
Immediately after the pouches of each example prepared by the above procedure and after hot water treatment, the pouches are opened and the oxygen permeability (OTR) of the gas barrier film (unit: cc / m ² · day · atm, measurement conditions: 30 ° C. -70% RH), and water vapor transmission rate (WVTR) ^{(unit: g} / m 2 · day, measurement conditions: 40 ℃ -90% RH) were evaluated.
The OTR was measured using OX-TRAN2 / 22 manufactured by mocon, and the WVTR was measured using PERMATRAN-W3 / 34 manufactured by mocon.
The results are shown in Tables 1 and 2.

(Evaluation of film density and hydrogen concentration of gas barrier layer)
The density of the AlOx film of the gas barrier layer 30 was calculated from the measurement by RBS (Rutherford backscattering analysis) -ERDA (recoil particle detection). The element composition ratio in the depth direction was measured from RBS for elements other than hydrogen and ERDA for hydrogen, and the film density was calculated by dividing the mass of each element ratio by the AlOx film thickness.

As the gas barrier film according to each embodiment, by using a base material having a surface hardness of 150 MPa or less, the decrease in oxygen permeability and water vapor permeability due to hot water treatment is suppressed, and oxygen after hot water treatment is suppressed. And the barrier property of water vapor was excellent. The adhesion between the base material and the sealant after the hot water treatment was also good. Further, the effect was better when the melting point was 155 ° C. or lower, the softening temperature was 160 ° C. or lower, and the number of fine particles having an average particle diameter of 1 μm or more was 30 particles / mm ^{2 or less.}

On the other hand, the gas barrier film of the comparative example used a base material having a surface hardness of the first surface exceeding 150 MPa, a softening temperature of more than 160 ° C., and a melting point of more than 155 ° C., and therefore was treated with hot water as compared with the examples. Later adhesion was inferior.

Although one embodiment and the examples of the present invention have been described above, the specific configuration is not limited to this embodiment, and changes and combinations of configurations within a range not deviating from the gist of the present invention are also included. ..

Further, in the gas barrier film of the present invention, a print layer may be provided at an appropriate position. Further, an intervening film may be attached on the coating layer to impart desired physical properties such as pinhole resistance, cold resistance, heat resistance, bag drop resistance, and tear resistance to the gas barrier film.

Further, in the gas barrier film of the present invention, the adhesive layer and the sealant layer are not essential. That is, the adhesive layer and the sealant layer may be provided as necessary in consideration of the specific use of the gas barrier film and the like.
The gas barrier film of the present invention is particularly suitable for packaging foods, pharmaceuticals, precision electronic components, etc., but is not limited thereto.

1 Gas barrier film 10 Base material 10a Pretreatment layer 11 First skin layer 12 Core layer 13 Second skin layer 20 Second base material 30 Gas barrier layer 40 Coating layer 50 Adhesive layer 60 Sealant layer

Claims (16)

1. A base material containing propylene as a main component and having a surface hardness of 150 MPa or less on the first surface,
   The gas barrier layer formed on the first surface and
   The coating layer formed on the gas barrier layer and
   To prepare
   Gas barrier film.
2. In the base material, the surface hardness of the second surface opposite to the first surface is 150 MPa or less.
   The gas barrier film according to claim 1.
3. A base material containing propylene as the main component and having a surface softening temperature of 160 ° C or lower on the first surface,
   The gas barrier layer formed on the first surface and
   The coating layer formed on the gas barrier layer and
   To prepare
   Gas barrier film.
4. In the base material, the surface softening temperature of the second surface opposite to the first surface is 160 ° C. or lower.
   The gas barrier film according to claim 3.
5. A base material containing propylene as a main component and having a surface melting point of 155 ° C. or lower on the first surface,
   The gas barrier layer formed on the first surface and
   The coating layer formed on the gas barrier layer and
   To prepare
   Gas barrier film.
6. In the base material, the surface melting point of the second surface opposite to the first surface is 155 ° C. or lower.
   The gas barrier film according to claim 5.
7. The oxygen permeability at 30 ° C. and 70% RH is ² cc / m 2 · day or less, and the water vapor transmission rate at 40 ° C. 90% RH is 2 g / m ² · day or less.
   The gas barrier film according to any one of claims 1 to 6.
8. The base material contains fine particles having an average particle diameter of 1 μm or more, and has an average particle diameter of 1 μm or more.
   The number of the fine particles protruding from the first surface is 30 or less per ^{1 mm 2.}
   The gas barrier film according to any one of claims 1 to 7.
9. A pretreatment layer made of any of a thermoplastic resin, a thermosetting resin, and an ultraviolet curable resin is provided between the first surface and the gas barrier layer.
   The gas barrier film according to any one of claims 1 to 8.
10. The gas barrier layer contains any one of aluminum, aluminum oxide, silicon oxide, silicon oxide containing carbon, and silicon nitride as a main component.
    The gas barrier film according to any one of claims 1 to 9.
11. The coating layer comprises one or more alkoxides or hydrolysates thereof, water-soluble polymers, polyvalent metal compounds, and polyvalent metal salts of carboxylic acids.
    The gas barrier film according to any one of claims 1 to 10.
12. Further comprising a heat-sealable sealant layer, the sealant layer is bonded to the coating layer by an adhesive layer.
    The gas barrier film according to claim 1.
13. A second base material is bonded to the second surface side of the base material.
    The gas barrier film according to any one of claims 2, 4 and 6.
14. After hot water treatment at 121 ° C for 30 minutes,
    The peel strength of the base material and the gas barrier layer in accordance with JIS K 6854-2 and JIS K 6854-3 is 1.0 N / 15 mm or more.
    The gas barrier film according to any one of claims 1 to 13.
15. After hot water treatment at 121 ° C for 30 minutes,
    The oxygen permeability at 30 ° C. and 70% RH is ² cc / m 2 · day or less, and the water vapor transmission rate at 40 ° C. 90% RH is 2 g / m ² · day or less.
    The gas barrier film according to any one of claims 1 to 13.
16. At least one of the aluminum oxide film density of the gas barrier layer formed on the first surface of the base material is 2.0 g / cm ³ or more and the hydrogen concentration contained in the film is 29 at% or less.
    The gas barrier film according to any one of claims 1 to 15.

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