JP2021091202A - Gas barrier film - Google Patents

Abstract

To provide a gas barrier film having high resistance to a hot-water treatment and suppressed in the environmental load.SOLUTION: A gas barrier film 1 comprises a base material 10 made of polypropylene as a main component, a gas barrier layer 20 formed on a first surface 10a of the substrate, and a coating layer 30 formed on the gas barrier layer. In an infrared spectroscopy measurement of a first side, a ratio of a peak intensity I1 present at 1360 to 1390 cm-1 and a peak intensity I2 present at 1440-1480 cm-1 satisfies equation I1/I2≤1.65.SELECTED DRAWING: Figure 1

Description

The present invention relates to a gas barrier film and a method for producing a gas barrier film. The gas barrier film of the present invention is suitable for packaging foods, pharmaceuticals, precision electronic parts and the like.

In packaging materials used for packaging foods, non-foods, pharmaceuticals, etc., from the viewpoint of suppressing alteration of the contents and maintaining their functions and properties, oxygen, water vapor, and other gases that alter the contents that permeate the packaging material. Gas barrier properties that block 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, sputtering, or the like is known ( For example, see Patent Document 1.). These gas barrier films have transparency and gas blocking properties such as oxygen and water vapor.
As the base film, one made of polyethylene terephthalate (PET) is often used.

Japanese Unexamined Patent Publication 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.

Based on the above circumstances, an object of the present invention is to provide a gas barrier film having high resistance to hot water treatment and suppressing an environmental load, and a method for producing the same.

The present invention is a gas barrier film including a base material containing polypropylene as a main component, a gas barrier layer formed on the first surface of the base material, and a coating layer formed on the gas barrier layer.
In the gas barrier film, infrared spectrometry of the first surface, the peak intensity I1 present in 1360～1390Cm ^-1, the ratio of the peak intensity I2 present in 1440～1480Cm ^-1 is represented by the following formula (1) Fulfill.
I1 / I2 ≤ 1.65 ... (1)

According to 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 cross-sectional view of the gas barrier film which concerns on one 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 gas barrier layer 20, a coating layer 30, an adhesive layer 40, and a sealant layer 50.

The base material 10 has two or more resin layers containing polypropylene as a main component. The base material of the present embodiment has two resin layers, a base layer 11 and a surface layer 12 laminated on the base layer 11.
The base material 10 having two or more resin layers can be formed, for example, by coextrusion. The total thickness of the base material 10, which is the total of the base layer 11 and the surface layer 12, can be, for example, 3 to 200 μm, preferably 15 to 60 μm.

The resin used as a raw material for each layer of the base material 10 contains polypropylene as a main component from the viewpoint of easy availability, water vapor barrier property, and suppression of addition to the environment. Polypropylene may be a homopolymer, a random copolymer, a block copolymer, or a terpolymer. Homopolymers are polypropylenes consisting of elemental propylene alone. Random copolymers are polypropylenes in which propylene, which is the main monomer, and a comonomer of a different type from propylene are randomly copolymerized to form a homogeneous phase. Block copolymers are polypropylenes that form a heterogeneous phase when the main monomer, propylene, and the above-mentioned comonomer are copolymerized in a block-like manner or polymerized in a rubber-like manner. The terpolymer is polypropylene in which propylene, which is the main monomer, and two types of comonomer different from propylene are copolymerized. Any one of these polyolefin resins may be used alone, or two or more thereof may be blended and used. The raw material of the base layer 11 is preferably a homopolymer, a random copolymer, or a block copolymer. As the raw material of the surface layer 12, any one of a random copolymer, a block copolymer, and a terpolymer is preferable.

The gas barrier layer 20 is formed on the first surface 10a of the base material 10 made of the surface layer 12. The gas barrier layer 20 is a layer containing any one of metallic aluminum, aluminum oxide, and silicon oxide as a main component and exhibiting a barrier property against a predetermined gas such as oxygen and water vapor.
The gas barrier layer 20 can be either transparent or opaque, depending on the material selected.

The thickness of the gas barrier layer 20 can be appropriately determined based on the performance required for the gas barrier layer while considering the type, composition, forming method, etc. of the inorganic compound used, but can be generally in the range of 3 to 300 nm. If the film thickness is less than 3 nm, a uniform film may not be obtained or the film thickness may not be sufficient, making it difficult to secure the function as a gas barrier material. If the film thickness exceeds 300 nm, the flexibility of the film is lowered, and the thin film is likely to be cracked due to external factors such as bending and pulling after the film formation. Therefore, the thickness of the gas barrier layer 20 is more preferably in the range of 6 to 150 nm.

The method for forming the gas barrier layer 20 is not particularly limited, and examples thereof include a vacuum deposition method, a sputtering method, an ion plating method, an ion beam method, and a plasma vapor deposition method (CVD). The gas barrier layer may be formed densely by combining the above-mentioned method with a plasma assist method, an ion beam assist method, or the like to improve the barrier property and the adhesion.

The coating layer 30 mainly has a gas barrier property against oxygen. The coating layer 30 is formed by 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 water / alcohol mixed solution as a main component. For example, a coating agent is prepared by dissolving a water-soluble polymer in an aqueous (water or water / alcohol mixed) solvent and directly or preliminarily hydrolyzing the metal alkoxide. The coating layer 30 can be formed by applying this coating agent on the gas barrier layer 20 and then drying it.

Each component contained in the coating agent for forming the coating layer 30 will be described in detail.
Examples of the water-soluble polymer used in 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, any of so-called partially saponified PVA in which several tens of percent of acetic acid groups remain and 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 the general formula, M (OR) n (metal of M: Si, Al, alkyl group of _{R: CH 3,} C ₂ H _{5, etc.).} 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 of 3-isocyanatepropyltriethoxysilane, tris- (3-trimethoxysilylpropyl) isocyanurate, and the like.
The coating method is not limited, and conventionally known methods such as a dipping method, a roll coating method, a screen printing method, a spray method, and a gravure printing method, which are usually used, can be appropriately selected.

The thickness of the coating layer 30 can be appropriately determined based on the composition of the coating agent, coating conditions, and the like, and is not particularly limited. However, if the film thickness of the coating layer 30 after drying is 0.01 μm or less, the coating film may not be uniform 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 layer 30. Therefore, the suitable thickness of the coating layer 30 is, for example, in the range of 0.01 to 50 μm. The optimum thickness of the coating layer 30 is, for example, in the range of 0.1 to 10 μm.

The sealant layer 50 is a layer that is joined by heat fusion when forming a bag-shaped package or the like using the gas barrier film 1. Materials for the sealant layer 60 include polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methacrylate copolymer, ethylene-methacrylate copolymer, ethylene-acrylic acid copolymer, and ethylene-acrylic acid ester. Examples of resin materials such as polymers and their metal crosslinked products can be exemplified. The thickness of the sealant layer 60 is determined according to the purpose, but can be, for example, in the range of 15 to 200 μm.

The adhesive layer 40 joins the sealant layer 50 and the coating layer 30. By using the adhesive layer 40, the resin film to be the sealant layer 50 and the base material 10 on which the gas barrier layer 20 and the coating layer 30 are formed can be bonded by dry lamination. As the material of the adhesive layer 40, 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 30 to form a packaging material. When laminating, an extrusion laminating method may be used in which the sealant layer is formed directly on the coating layer 30 without using an adhesive.

In the first surface 10a of the base material 10, the intensity ratio of the peak intensity (I1) ^{existing at 1370 to 1380 cm -1} and the peak intensity (I2) existing at ^{1450 to 1460 cm -1 in infrared spectroscopic measurement is expressed by the formula (I2).} It is in the range of 1). That is, I1 is 1.65 times or less of I2. In this embodiment, this strength ratio is provided by the material properties of the surface layer 12 that constitutes the first surface 10a.
I1 / I2 ≤ 1.65 ... (1)

The value of the above formula (1) indicates the ratio of polypropylene to the resin component at the measurement point. I1 indicates the amount of polypropylene, and I2 indicates the sum of polyethylene and polypropylene. Therefore, the value of the formula (1) becomes larger in the homopolymer than in the copolymer or the terpolymer, and in the copolymer or the terpolymer, the value of the formula (1) becomes smaller as the components other than polypropylene increase.
The inventors have conducted various studies in constructing a gas barrier film using a base material containing polypropylene as a main component. As a result, on the first surface 10a on which the gas barrier layer 20 is formed, if the value of the formula (1) on the first surface 10a is 1.65 or less within the range containing polypropylene as the main component, the gas barrier layer is defective. It was found that the gas barrier layer was formed in a good condition without any problem, and that the cohesive force was excellent and the adhesion strength of the gas barrier layer was improved. The value of the formula (1) on the first surface 10a is preferably 1.30 to 1.60, more preferably 1.30 to 1.55. If it is 1.30 or less, the heat resistance is inferior and the gas barrier property is deteriorated. Further, when it is 1.60 or more, the cohesive force is inferior and the adhesion strength tends to decrease.
In the gas barrier film 1 of the present embodiment, as described above, the gas barrier layer exhibiting suitable gas barrier properties is well bonded to the base material while maintaining the composition of the monomaterial containing polypropylene as the main component and suppressing the environmental load. It is configured to be difficult to peel off.

As a result of further studies by the inventors, the overall characteristics of the base material 10 are further improved by adding the base layer 11 having a larger value of the formula (1) to the surface layer 12 including the first surface having the above characteristics. I found that. By laminating a layer having a larger value of the formula (1), that is, a layer having a higher proportion of polypropylene than the layer containing the first surface, the heat resistance of the base material 10 as a whole is improved. As a result, sufficient heat can be applied to the base material 10 when forming the coating layer 30, and the barrier performance of the coating layer 30 can be improved. Further, when the manufactured gas barrier film is subjected to hot water treatment such as retort treatment and boiling treatment, the base layer 11 suppresses the shrinkage of the surface layer 12, and the shrinkage causes cracks and the like in the gas barrier layer 20 to perform the gas barrier function. It preferably suppresses the decrease and the gas barrier layer 20 being easily peeled off from the base material 10.
The surface layer 12 of the base material 10 is made of HDPE (high density polyethylene), LDPE (low density polyethylene), LLDPE (linear low density polyethylene), etc., which have a low melting point of 0.1 to several tens of percent of the homopolymer of propylene. Polyethylene, α-olefin resin such as 1-butene, resin obtained by copolymerizing rubber components such as elastomer, or polyethylene resin and polypropylene resin are mixed at a predetermined ratio, and the base layer 11 uses a propylene homopolymer resin. However, it can be controlled by kneading with multiple screws and extruding a film (filming). Generally, polypropylene film has lower heat resistance than PET film, but by manufacturing as described above, the surface layer 12 constituting the surface is formed by the formula (1) while having a highly heat-resistant propylene homopolymer in the base layer 11. ), The base material 10 having excellent heat resistance can be realized.
From such a viewpoint, the value of the above formula (1) on the second surface 10b formed by the base layer 11 is preferably larger than the value of the first surface, and more preferably 1.65 or more.

In the base material 10, if the surface of the first surface 10a is smooth, defects of the formed gas barrier layer 20 are less likely to occur, which is preferable. The average surface roughness Sa can be used as an index of smoothness, and its value is preferably 10 nm or less. The average surface roughness Sa is measured at a site where fine particles, which will be described later, do not exist.

The base material 10 may contain an additive that is not a resin component. 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, UV absorbers, lubricants, slip agents, nucleating agents, antistatic agents, antifogging agents, pigments, and dyes. 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 on the first surface 10a causes minute defects in the gas barrier layer 20 and the coating layer 30. In the study of the inventor, it was found that microdefects are less likely to occur by setting the number and protrusion height of fine particles made of a material other than polypropylene protruding on the first surface to a predetermined value or less. An example of a predetermined value is 100 or less per square region having a side of 250 μm and an average protrusion length of 5 μm or less. However, if it means substantially the same content as this, the specific content of the index is It doesn't matter.
When the number of fine particles exceeds 100 and the average protrusion height exceeds 5 μm, the barrier property is lowered. Therefore, the number of fine particles should be 100 or less and the average protrusion height should be 5 μm or less.

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 20 is formed on the treated surface by an appropriate method on the first surface 10a of the base material 10 (first step). In the first step, before forming the gas barrier layer, a coating layer such as a thermoplastic resin, a thermosetting resin, or an ozone curable resin is formed on the first surface 10a in order to improve the barrier property and the adhesiveness. A pretreatment layer may be provided between the first surface 10a and the gas barrier layer 20 by performing pretreatment such as corona treatment, plasma treatment, ozone treatment, and flame treatment on one surface 10a. By providing the pretreatment layer, the adhesion between the base material 10 and the gas barrier layer 20 can be further improved.
Among the above-mentioned pretreatments, plasma treatments that can be performed in-line are preferable from the viewpoint of productivity. The plasma treatment is not particularly limited to glow discharge, ion beam, etc., and a magnet may be used to increase the plasma density. The gas used for the plasma treatment can be selected from one or more of oxygen, nitrogen and argon.

Next, the above-mentioned coating agent is applied onto the gas barrier layer 20 and dried to form the coating layer 30 on the gas barrier layer (second step).
Further, when an adhesive to be the adhesive layer 40 is applied on the coating layer 30 and a resin film to be the sealant layer 50 is attached (third step), the gas barrier film 1 is completed.

The gas barrier film of the present 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 biaxially stretched polypropylene film A having a thickness of 20 μm was used. The polypropylene film A is a coextruded film having two layers, a base layer 11 and a surface layer 12.
The first surface of the polypropylene film A made of the surface layer 12 was subjected to corona treatment. In the vacuum apparatus, a mixture of silicon and silicon oxide was sublimated to form a gas barrier layer 20 (thickness 30 nm) made of silicon oxide by an electron beam vapor deposition method.

On the gas barrier layer 20, a coating agent obtained by mixing the following liquids (1) and (2) at a mass ratio of 6: 4 was applied and dried by a gravure coating method to form a coating layer 30 having a thickness of 0.4 μm. ..
Liquid (1): Hydrolyzed solution (2) _{having 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, an unstretched polypropylene film (thickness 70 μm) was laminated on the coating layer 30 by dry laminating using a two-component curable polyurethane adhesive to obtain a gas barrier film of Example 1.

(Example 2)
The gas barrier film of Example 2 was produced in the same manner as in Example 1 except that the vapor deposition material was aluminum and a gas barrier layer 20 having a thickness of 10 nm made of metallic aluminum was formed by an electron beam vapor deposition method.

(Example 3)
The gas barrier film of Example 3 was produced in the same manner as in Example 1 except that the vapor deposition material was aluminum and a gas barrier layer 20 having a thickness of 10 nm made of aluminum oxide was formed by an electron beam vapor deposition method under oxygen introduction.

(Example 4)
As the base material 10, a biaxially stretched polypropylene film B having a thickness of 20 μm was used. The polypropylene film B is a coextruded film having two layers, a base layer 11 and a surface layer 12, but is a film different from the polypropylene film B.
A gas barrier film of Example 4 was prepared in the same manner as in Example 1 except for the above.

(Example 5)
The gas barrier film of Example 5 was prepared in the same manner as in Example 2 except that the polypropylene film B was used as the base material 10.

(Example 6)
A gas barrier film of Example 6 was prepared in the same manner as in Example 3 except that the polypropylene film B was used as the base material 10.

(Example 7)
As the base material 10, a biaxially stretched polypropylene film C having a thickness of 20 μm was used. The polypropylene film C is a coextruded film having two layers, a base layer 11 and a surface layer 12, but is different from both the polypropylene films A and B.
A gas barrier film of Example 7 was prepared in the same manner as in Example 1 except for the above.

(Example 8)
A gas barrier film of Example 8 was prepared in the same manner as in Example 2 except that polypropylene film C was used as the base material 10.

(Example 9)
A gas barrier film of Example 9 was prepared in the same manner as in Example 3 except that polypropylene film C was used as the base material 10.

(Example 10)
As the base material 10, a biaxially stretched polypropylene film D having a thickness of 20 μm was used. The polypropylene film D is a coextruded film having two layers, a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to C.
A gas barrier film of Example 10 was prepared in the same manner as in Example 1 except for the above.

(Example 11)
The gas barrier film of Example 11 was prepared in the same manner as in Example 2 except that the polypropylene film D was used as the base material 10.

(Example 12)
A gas barrier film of Example 12 was prepared in the same manner as in Example 3 except that polypropylene film D was used as the base material 10.

(Example 13)
As the base material 10, a biaxially stretched polypropylene film E having a thickness of 20 μm was used. The polypropylene film E is a coextruded film having two layers, a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to D.
A gas barrier film of Example 13 was prepared in the same manner as in Example 1 except for the above.

(Example 14)
A gas barrier film of Example 14 was prepared in the same manner as in Example 2 except that polypropylene film E was used as the base material 10.

(Example 15)
A gas barrier film of Example 15 was prepared in the same manner as in Example 3 except that polypropylene film E was used as the base material 10.

(Example 16)
A gas barrier film of Example 16 was prepared in the same manner as in Example 1 except that a polypropylene film A having a thickness of 15 μm was used as the base material 10.

(Example 17)
A gas barrier film of Example 17 was prepared in the same manner as in Example 2 except that the base material was the same as that of Example 16.

(Example 18)
A gas barrier film of Example 18 was prepared in the same manner as in Example 3 except that the base material was the same as that of Example 16.

(Example 19)
A gas barrier film of Example 19 was prepared in the same manner as in Example 1 except that a polypropylene film A having a thickness of 40 μm was used as the base material 10.

(Example 20)
A gas barrier film of Example 20 was prepared in the same manner as in Example 2 except that the base material was the same as that of Example 19.

(Example 21)
A gas barrier film of Example 21 was prepared in the same manner as in Example 3 except that the base material was the same as that of Example 19.

(Example 22)
As the base material 10, a biaxially stretched polypropylene film F having a thickness of 20 μm was used. The polypropylene film F is a coextruded film having two layers, a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to E.
A gas barrier film of Example 22 was prepared in the same manner as in Example 1 except for the above.

(Example 23)
As the base material 10, a biaxially stretched polypropylene film G having a thickness of 20 μm was used. The polypropylene film G is a coextruded film having two layers, a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to F.
A gas barrier film of Example 23 was prepared in the same manner as in Example 1 except for the above.

(Example 24)
As the base material 10, a biaxially stretched polypropylene film H having a thickness of 20 μm was used. The polypropylene film H is a coextruded film having two layers, a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to G.
A gas barrier film of Example 24 was prepared in the same manner as in Example 1 except for the above.

(Example 25)
As the base material 10, a biaxially stretched polypropylene film I having a thickness of 20 μm was used. The polypropylene film I is a coextruded film having two layers, a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to H.
A gas barrier film of Example 25 was prepared in the same manner as in Example 1 except for the above.

(Example 26)
A gas barrier film of Example 26 was prepared in the same manner as in Example 1 except that the base material was subjected to plasma treatment with Ar gas as a pretreatment to continuously form silicon oxide.

(Example 27)
As a pretreatment, the base material was provided with an acrylic urethane resin layer 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 was 1.0 as a pretreatment. Except for this, the gas barrier film of Example 27 was prepared in the same manner as in Example 1.

(Example 28)
As the base material 10, a biaxially stretched polypropylene film J having a thickness of 20 μm was used. The polypropylene film J is a coextruded film having two layers, a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to I.
A gas barrier film of Example 28 was prepared in the same manner as in Example 1 except for the above.

(Example 29)
As the base material 10, a biaxially stretched polypropylene film K having a thickness of 20 μm was used. The polypropylene film K is a coextruded film having two layers, a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to J.
A gas barrier film of Example 29 was prepared in the same manner as in Example 1 except for the above.

(Example 30)
As the base material 10, a biaxially stretched polypropylene film L having a thickness of 20 μm was used. The polypropylene film L is a coextruded film having two layers, a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to K.
A gas barrier film of Example 30 was prepared in the same manner as in Example 1 except for the above.

(Comparative Example 1)
As the base material 10, a biaxially stretched polypropylene film M having a thickness of 20 μm was used. The polypropylene film M is a coextruded film having at least two layers of a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to L.
A gas barrier film of Comparative Example 1 was prepared in the same manner as in Example 1 except for the above.

(Comparative Example 2)
A gas barrier film of Comparative Example 2 was prepared in the same manner as in Example 3 except that the polypropylene film M was used as the base material 10.

(Comparative Example 3)
As the base material 10, a biaxially stretched polypropylene film N having a thickness of 20 μm was used. The polypropylene film N is a coextruded film having at least two layers of a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to M.
A gas barrier film of Comparative Example 3 was prepared in the same manner as in Example 1 except for the above.

(Comparative Example 4)
A gas barrier film of Comparative Example 4 was prepared in the same manner as in Example 3 except that polypropylene film N was used as the base material 10.

(Comparative Example 5)
As the base material 10, a biaxially stretched polypropylene film O having a thickness of 20 μm was used. The polypropylene film O is a coextruded film having at least two layers of a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to N.
A gas barrier film of Comparative Example 5 was prepared in the same manner as in Example 1 except for the above.

(Comparative Example 6)
A gas barrier film of Comparative Example 6 was prepared in the same manner as in Example 3 except that polypropylene film O was used as the base material 10.

(Comparative Example 7)
As the base material 10, a biaxially stretched polypropylene film P having a thickness of 20 μm was used. The polypropylene film P is a coextruded film having at least two layers of a base layer 11 and a surface layer 12, but is different from any of polypropylene films A to O.
A gas barrier film of Comparative Example 7 was prepared in the same manner as in Example 1 except for the above.

(Comparative Example 8)
A gas barrier film of Comparative Example 8 was prepared in the same manner as in Example 3 except that the polypropylene film P was used as the base material 10.

(Comparative Example 9)
As the base material 10, a biaxially stretched polypropylene film Q having a thickness of 20 μm was used. The polypropylene film Q is a coextruded film having at least two layers of a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to P.
A gas barrier film of Comparative Example 9 was prepared in the same manner as in Example 1 except for the above.

(Comparative Example 10)
A gas barrier film of Comparative Example 10 was prepared in the same manner as in Example 3 except that polypropylene film Q was used as the base material 10.

(Comparative Example 11)
As the base material 10, a biaxially stretched polypropylene film R having a thickness of 20 μm was used. The polypropylene film R is a coextruded film having at least two layers of a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to Q.
A gas barrier film of Comparative Example 11 was prepared in the same manner as in Example 1 except for the above.

(Comparative Example 12)
A gas barrier film of Comparative Example 12 was prepared in the same manner as in Example 3 except that the polypropylene film R was used as the base material 10.

(Comparative Example 13)
As the base material 10, a biaxially stretched polypropylene film S having a thickness of 20 μm was used. The polypropylene film S is a coextruded film having at least two layers of a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to R.
A gas barrier film of Comparative Example 13 was prepared in the same manner as in Example 1 except for the above.

(Comparative Example 14)
A gas barrier film of Comparative Example 14 was prepared in the same manner as in Example 3 except that the polypropylene film S was used as the base material 10.

(Comparative Example 15)
As the base material 10, a biaxially stretched polypropylene film T having a thickness of 20 μm was used. The polypropylene film T is a coextruded film having at least two layers of a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to S.
A gas barrier film of Comparative Example 15 was prepared in the same manner as in Example 1 except for the above.

(Comparative Example 16)
A gas barrier film of Comparative Example 16 was prepared in the same manner as in Example 3 except that the polypropylene film T was used as the base material 10.

(Comparative Example 17)
As the base material 10, a biaxially stretched polypropylene film U having a thickness of 20 μm was used. The polypropylene film U is a coextruded film having at least two layers of a base layer 11 and a surface layer 12, but is different from any of the polypropylene films A to T.
A gas barrier film of Comparative Example 17 was prepared in the same manner as in Example 1 except for the above.

(Comparative Example 18)
A gas barrier film of Comparative Example 18 was prepared in the same manner as in Example 3 except that the polypropylene film U was used as the base material 10.

(Comparative Example 19)
A gas barrier film of Comparative Example 19 was produced in the same manner as in Example 2 except that the polypropylene film U was used as the base material 10.

The evaluation items and measurement methods in each Example and Comparative Example are shown below.
(Infrared spectroscopic measurement of the first and second surfaces)
Using a Fourier transform infrared spectrophotometer FT / IR-4000 (manufactured by JASCO Corporation), this was performed on both sides in the thickness direction of each base material before preparation of the gas barrier film. The measurement conditions and the like are as follows.
Measurement conditions: ATR method Prism: Ge
Resolution: 4 cm ^-1
Total number of times: 64
When the above measurement is performed using the produced gas barrier film, a cross section of the gas barrier film can be formed by cutting, and the base layer and the surface layer can be measured using this cross section.

(Surface measurement on the first surface)
Using each base material before production, the following contents were carried out.
・ Average surface roughness Sa
The average surface roughness Sa was calculated by measuring a randomly selected range of 1 μm × 1 μm from the first surface 10a using a scanning probe microscope. The measurement was performed at a site where no fine particles were present.
-Number of fine particles and protrusion height The surface of the first surface 10a was observed using a laser microscope, and the number and protrusion height of the fine particles per unit area were measured. The observation magnification was 50 times. The number per unit area was measured in a randomly selected range of 257 μm × 259 μm (0.067 mm ² ) and two areas of the same size adjacent to the right side, and used as the arithmetic mean value of the three areas. The protrusion height was the arithmetic mean value of all the fine particles counted in the three areas.

(Evaluation of gas barrier layer adhesion immediately after fabrication)
A test piece was cut out from the gas barrier film of each example in accordance with JIS K 6854-2 and JIS K 6854-3, and the peel strength of the gas barrier layer 20 measured using the Orientec Tencilon universal testing machine RTC-1250 was adjusted. It was measured as an index of. Two types of measurement, T-shaped peeling and 180 ° peeling, were performed under normal conditions (Dry) and measurement site wetness (Wet), respectively.

(Evaluation of gas barrier layer adhesion after hot water treatment)
Two gas barrier films of each example were laminated with the sealant layers 50 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 the contents, 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 portion 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 gas barrier layer 20 measured using RTC-1250. The peel strength 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.

(Evaluation of gas barrier performance immediately after production and after hot water treatment)
After immediately and hydrothermal treatment produced a pouch of each example was produced by the steps mentioned above, the oxygen permeability of the gas barrier film by opening the pouch (OTR) ^{(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 configurations of Examples and Comparative Examples are shown in Tables 1 and 2, respectively, and the evaluation results of Examples and Comparative Examples are shown in Tables 3 to 5, respectively.

In each of the gas barrier films of the examples, high adhesion between the base material 10 and the gas barrier layer 20 was maintained after the hot water treatment. Further, even after the hot water treatment, the oxygen permeability was 5.0 cc / m ² · day or less and the water vapor transmission rate was 2.0 g / m ² · day, showing good gas barrier performance.

On the other hand, the gas barrier films of Comparative Examples 9 to 19 in which the value of the formula (1) on the first surface exceeded 1.65 had low adhesion between the gas barrier layer 20 after the hot water treatment and the base material.
In Comparative Examples 1 to 8 in which the values of the formulas (1) on the first surface and the second surface were both less than 1.65, both OTR and WVTR decreased after the hot water treatment. It is considered that this is because the base material was shrunk by the hot water treatment and the gas barrier layer 20 and the coating layer 30 were damaged.

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 printing 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, an adhesive layer or a sealant layer is 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.

1 Gas barrier film 10 Base material 10a First surface 10b Second surface 11 Base layer 12 Surface layer 20 Gas barrier layer 30 Coating layer 40 Adhesive layer 50 Sealant layer

Claims (10)

A base material containing polypropylene as the main component and
A gas barrier layer formed on the first surface of the base material and
The coating layer formed on the gas barrier layer and
With
Wherein the first surface infrared spectrometry, the peak intensity I1 present in 1360～1390Cm ^-1, the ratio of the peak intensity I2 present in 1440～1480Cm ^-1 satisfies the following formula (1), a gas barrier film.
I1 / I2 ≤ 1.65 ... (1) The base material is
The surface layer constituting the first surface and
It has a base layer constituting the second surface opposite to the first surface, and has.
The value of the formula (1) in the infrared spectroscopic measurement of the second surface is larger than the value of the formula (1) on the first surface.
The gas barrier film according to claim 1. Fine particles made of a material other than polypropylene project on the first surface.
The number of the fine particles is 100 or less per region of 250 μm on a side.
The average protruding height of the fine particles is 5 μm or less.
The gas barrier film according to claim 1. The average surface roughness Sa of the first surface is 10 nm or less.
The gas barrier film according to claim 1. The gas barrier layer contains any one of aluminum, aluminum oxide, silicon oxide, and silicon oxide containing carbon as a main component.
The gas barrier film according to claim 1. The coating layer contains one or more alkoxides or hydrolysates thereof and a water-soluble polymer.
The gas barrier film according to claim 1. A heat-sealing sealant layer is further provided, and the sealant layer is bonded to the coating layer by an adhesive layer.
The gas barrier film according to claim 1. Oxygen permeability is 3.0 cc / m ² · day or less, and water vapor transmission rate is 1.5 g / m ² · day or less.
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 claim 1. After hot water treatment at 121 ° C for 30 minutes,
Oxygen permeability is 5.0 cc / m ² · day or less, and water vapor transmission rate is 2.0 g / m ² · day or less.
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 claim 1. A pretreatment layer composed of a thermoplastic resin, a thermosetting resin, an ultraviolet curable resin, and a plasma treatment is provided between the first surface and the gas barrier layer.
The gas barrier film according to claim 1.

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