JP2005178311A - Gas barrier film laminate, its manufacturing method, and packaging bag using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas barrier film laminate showing excellent adhesion between laminated films in case of a boil treatment, a retort treatment or the like, so-called hot water-resisting adhesion, and to provide a packaging bag using it. <P>SOLUTION: The film laminate comprising a laminate of at least 5 layers of a base film layer (B1)/ an adhesive layer (A1)/ a base film layer (B2)/ an adhesive agent layer (A2)/ a heat sealable resin layer, in this order, a gas barrier thin film layer of an inorganic oxide being vapor-deposited on either the surface of the base film layer (B1) on the adhesive layer (A1) side or the surface of the base film layer (B2) on the adhesive layer (A1) side, is characterized in that the laminate shows steam permeability (g/m<SP>2</SP>×day) of not more than 3.0, and steam permeability (g/m<SP>2</SP>×day) after hot water treatment at 120°C for 30 minutes is not more than 4.0. The manufacturing method of the gas barrier film laminate is characterized in that the wet tension of the surface of the base film to be subjected to the vapor deposition is not more than 45 mN/m before the vapor deposition. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gas barrier film laminate having excellent transparency and gas barrier properties. More specifically, the present invention relates to a gas barrier film laminate excellent in adhesion between laminated films when subjected to boil treatment or retort treatment, so-called hot water adhesion, a method for producing the film laminate, and a packaging bag using the same. Is.

  Conventionally, gas barrier film laminates obtained by laminating various gas barrier substrate films and heat-sealable resins have been used as packaging bags for preserved foods and the like. Among these, there are many cases where a sterilization treatment step by boil treatment or retort treatment is taken from the viewpoint of maintaining the quality of contents and extending shelf life. Particularly in retort applications, the outermost layer is a polyester film, the intermediate layer is an aluminum foil and a polyamide film, and a non-stretched polypropylene film is laminated as a heat-sealable resin layer, or the outermost layer is an aluminum metal-deposited polyester film, A three-layer structure in which a polyamide film is laminated on a layer and an unstretched polypropylene film is laminated on a heat-sealable resin layer has been preferably used. However, in the configuration using aluminum foil or aluminum vapor deposition film, there is a problem that the contents cannot be seen or cooking with a microwave oven is not possible. As a means to solve these problems, various transparent gas barrier films were used for the base film. Gas barrier film laminates have been proposed.

  Among them, a gas barrier film in which an inorganic oxide such as silicon oxide or aluminum oxide is vapor-deposited on a base film has a gas barrier property comparable to that of an aluminum vapor-deposited film, and is transparent, making it a foreign material produced by a metal detector. The amount of use has been increasing mainly in applications where inspection and cooking with a microwave oven are required.

In the gas barrier film deposited with these inorganic oxides, from the viewpoint of the film quality of the deposited film, the substrate film is generally improved in wettability by performing corona treatment on the planned deposition surface of the substrate film. In many cases, an inorganic oxide layer is vapor-deposited (see, for example, Patent Document 1).
Japanese Patent Publication No.53-12953

  However, in a packaging bag using an inorganic oxide gas barrier film that has been subjected to hydrophilic treatment such as corona treatment on the surface to be vapor-deposited of the base film in this way, if hot water treatment such as boil treatment or retort treatment is performed, There are often cases where the adhesion at the interface between the material and the deposited film is reduced, and when used as a packaging bag, there is a concern that it may cause a trouble of breaking the bag during transportation or storage.

  The present invention has been made against the background of the problems of the prior art. Even when hot water treatment such as boil treatment or retort treatment is carried out, the gas barrier laminate having little decrease in adhesion at the interface between the substrate and the deposited film, and It is an object to obtain a used packaging bag.

In order to solve the above-mentioned problems, the present inventors have intensively studied and, as a result, have completed the present invention. That is, in the present invention, (1) at least five layers of the base film layer (B1) / adhesive layer (A1) / base film layer (B2) / adhesive layer (A2) / heat-sealable resin layer are in this order. It is a laminated film and is either a surface of the base film layer (B1) on the adhesive layer (A1) side or a surface of the base film layer (B2) on the adhesive layer (A1) side. In a film laminate in which a gas barrier thin film layer made of an inorganic oxide is deposited on the surface, the laminate has a water vapor transmission rate (g / m ² · day) of 3.0 or less and 120 ° C. for 30 minutes. A gas barrier film laminate having a water vapor transmission rate (g / m ² · day) after hydrothermal treatment of 4.0 or less. A gas barrier film laminate, wherein the substrate film surface to be deposited has a wetting tension before deposition of 45 mN / m or less.
(2) The gas barrier film laminate according to (1), wherein the base film layer (B1) is a biaxially stretched polyester film and the base film layer (B2) is a biaxially stretched polyamide film.
(3) The gas barrier film laminate according to (1), wherein the inorganic oxide is a composite oxide of aluminum oxide and silicon oxide.
(4) A packaging bag produced by using the gas barrier film laminate according to (1) to (3).
(5) A method for producing a gas barrier film laminate, wherein, in the production of the gas barrier film laminate of (1), the wetting tension before vapor deposition of the base film surface to be vapor deposited is 45 mN / m or less.

  The gas barrier film laminate according to the present invention can provide a packaging material with little decrease in adhesion between laminated film layers, that is, excellent water-resistant adhesion even when a boil treatment or a retort treatment is performed. In other words, when the gas barrier film laminate of the present invention is used for a packaging bag, it can maintain excellent strength even after boil treatment or retort treatment, which is effective in preventing troubles such as delamination and bag breakage during transportation and storage. is there.

Hereinafter, the present invention will be described in detail.
The base film in the present invention is a film made of an organic polymer, which is a known method, for example, melt extrusion molding, and is stretched, heat-set, and cooled as necessary. Examples of organic polymers include polyester resins such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyamide resins such as nylon 6, nylon 66, nylon 12, and nylon MXD6, and polyolefins such as polyethylene, polypropylene, and ethylene-vinyl alcohol copolymer. These resins may be used, and may be used alone, in combination, or coextruded. These organic polymers may be added or coated with known additives such as ultraviolet absorbers, antistatic agents, plasticizers, lubricants, colorants and the like. As thickness of a base film, 3-300 micrometers is preferable, More preferably, it is the range of about 9-50 micrometers from the mechanical characteristic and economical efficiency as a packaging material. In addition, a biaxially stretched polyester film or a biaxially stretched polyamide film is preferable from the viewpoint of processability such as vapor deposition and bag making. In applications involving hot water treatment such as boil treatment and retort treatment, the base film layer (B1) is biaxial. A combination of a stretched polyester film and a base film layer (B2) having a biaxially stretched polyamide film is preferred. You may print on a base film by a well-known method as needed.

In the film laminate of the present invention, at least 5 layers of the base film layer (B1) / adhesive layer (A1) / base film layer (B2) / adhesive layer (A2) / heat-sealable resin layer are in this order. It is a laminated film and is either a surface of the base film layer (B1) on the adhesive layer (A1) side or a surface of the base film layer (B2) on the adhesive layer (A1) side. A gas barrier thin film layer made of an inorganic oxide is deposited on the surface, and the water vapor permeability (g / m ² · day) of the laminate is 3.0 or less, and after hydrothermal treatment at 120 ° C. for 30 minutes Has a water vapor permeability (g / m ² · day) of 4.0 or less.

The water vapor permeability (g / m ² · day) of the laminate is measured in accordance with the JIS K7129B method, and is preferably 2.0 or less before hydrothermal treatment, After 30 minutes of hot water treatment, it is preferably 3.0 or less. The film laminate of the present invention is characterized by a small increase in water vapor permeability after the hot water treatment, and the water vapor permeability increase is 3.0 or less even after the hot water treatment at 120 ° C. for 30 minutes. For this reason, when the gas barrier film laminate of the present invention is used in a packaging bag, excellent strength can be maintained even after boil treatment or retort treatment.

An example of an effective means for reducing the increase in water vapor permeability after the hydrothermal treatment of the film laminate of the present invention is that the wetting tension before vapor deposition of the deposited base film surface is 45 mN / m or less. It is.
In general, in order to improve the adhesion of inks, adhesives, inorganic thin films, etc., in polymer film printing, laminating, and vapor deposition, it is preferable that the wetting tension on the surface of the base film is somewhat high. As a method for improving the wetting tension of the film, corona treatment, plasma treatment, flame treatment and the like are generally performed, and corona treatment is preferably used from the viewpoint of treatment speed and economy. These treatment facilities are often installed in the latter half of the film production line so that in-line treatment is possible, and the wetting index of the polyethylene terephthalate resin film or nylon 6 resin film surface subjected to corona treatment depends on the treatment conditions. Although it depends, it will be about 50 mN / m or more.

  Therefore, in the present invention, it has been found that the base film is preferably a base film formed without performing the above treatment. The wetting tension before deposition of the base film surface to be deposited varies depending on the material constituting the surface of the base film and the manufacturing method of the base film, but is a general method for forming a polymer film for packaging. It is preferable to form a film by a sequential biaxial stretching method. In this case, the wetting tension of the polyethylene terephthalate resin film surface can be about 38 to 42 mN / m, the wetting tension of the nylon 6 resin film surface can be about 38 to 42 mN / m, and the polypropylene resin film surface can be about 32 mN / m or less. .

  The inorganic oxide in this invention consists of metal oxides, such as magnesium, calcium, aluminum, titanium, silicon, germanium, zirconium, zinc, titanium, chromium, indium, tin, or these composites. The term “inorganic oxide” as used herein also includes an inorganic oxide which is not completely oxidized and lacks oxygen slightly, such as SiOx (x = 1.0 to 1.9). From the viewpoints of gas barrier properties and hygiene, silicon oxide or aluminum oxide is preferable, and from the viewpoint of transparency and bending resistance, a composite oxide of silicon oxide and aluminum oxide is particularly preferable.

  The film thickness of the gas barrier thin film made of an inorganic oxide in the present invention is preferably from 3 to 300 nm, and more preferably from 5 to 50 nm from the balance of transparency, gas barrier properties and bending resistance. When the film thickness is less than 5 nm, it is difficult to obtain a practical gas barrier property. Conversely, when the film thickness is 50 nm or more, transparency is impaired, or internal cracks in the thin film due to internal stress of the gas barrier thin film or peeling from the substrate. Therefore, the effect of improving the gas barrier property corresponding to the film thickness cannot be obtained, which is disadvantageous in terms of bending resistance and manufacturing cost.

  As a method for vapor-depositing a gas barrier thin film layer made of an inorganic oxide, a vacuum vapor deposition method, a physical vapor deposition method such as a sputtering method or an ion plating method, or a CVD (chemical vapor deposition method) is used. For example, in the vacuum deposition method, a coating system having a cooling function in a vacuum chamber equipped with an evacuation facility and a running system such as a film roll unwinding and winding mechanism, and evaporation for heating and evaporating the deposited material in the crucible. This is a method of laminating a gas barrier thin film layer made of an inorganic oxide continuously in the longitudinal direction of at least one side of a base film roll by a vacuum vapor deposition machine having a source, and an open / close shutter, a plasma pretreatment machine, a static elimination as required Equipment, a wrinkle removing roll, a vacuum gauge, a gas introduction port, a film thickness monitor, and the like may be provided.

  The deposition material such as metal or metal oxide, which is the raw material of the gas barrier thin film made of inorganic oxide, is placed in a crucible made of carbon or refractory metal and heated indirectly or directly by resistance heating, induction heating or electron gun. A substrate film that is evaporated and in close contact with the cooled coating drum passes through the vapor, whereby a gas barrier thin film is deposited on the film. Since resistance heating and induction heating heat the crucible, there is a concern that the material constituting the crucible may be mixed into the vapor deposition film, but the electron gun heating has the advantage that the vapor deposition material is directly heated and thus there are few impurities in the thin film. is there. In general, the melting point of the metal oxide is considerably higher than that of the metal. However, the electron gun heating does not have the restriction of the heat resistance of the crucible, so that the metal oxide is preferably used as the vapor deposition material. From the viewpoint of vapor deposition rate, material heating with an electron gun is preferable.

  The adhesive layer (A1) in the present invention is an adhesive layer for bonding the base film layer (B1) and the base film layer (B2), and an adhesive for dry lamination is mainly used. Two-component polyurethane adhesives are commonly used as adhesives for dry laminates for packaging materials for foods, beverages, etc., and main ingredients mainly composed of polyester polyol, polyether polyurethane polyol, polyester polyurethane polyether, and tolylene A curing agent mainly composed of polyisocyanate such as isocyanate, 4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate is combined and diluted with a solvent such as ethyl acetate for use. In order to accelerate the curing of the adhesive, aging is preferably performed at 40 ° C. for about 2 days after bonding. Currently, various adhesives for dry laminating are commercially available, but it is preferable to select for retort and for boil according to the application.

  On the other hand, the adhesive layer (A2) can be roughly divided into two depending on the method of forming the heat sealant resin layer. There are a method of forming a heat-sealable resin layer as a sealant film by a dry lamination method and a method of forming a heat sealable resin layer by an extrusion lamination method. In the former, the above-mentioned dry laminating adhesive is mainly used. In the latter, an adhesive generally called an anchor coat agent is used for the adhesive layer (A2). As an anchor coating agent, various organic titanium-based, isocyanate-based, polyethyleneimine, polybutadiene-based, and the like are commercially available. For the boil treatment application, a two-component isocyanate system excellent in hot water resistance is preferable. It is preferably used after being diluted to a low concentration of about 5% with a solvent such as ethyl acetate and aging at 40 ° C. for about 2 days after bonding to accelerate the curing of the adhesive.

  The heat-sealable resin layer of the present invention is preferably a sealant film made of polypropylene, low-density polyethylene, linear low-density polyethylene, high-density polyethylene, ethylene vinyl acetate copolymer, or the like in the case of the dry laminating method described above. It is done. In the case of the extrusion lamination method, it is desirable to apply an anchor coating agent to the base film and melt-extrude the heat-sealable resin thereon for lamination. As the resin to be melt-extruded, low density polyethylene, linear low density polyethylene, high density polyethylene, polypropylene, ethylene vinyl acetate copolymer, ionomer, ethylene acrylic acid copolymer, and the like are used. In the extrusion lamination method, the heat-sealable resin may be further melt-extruded and laminated in two steps (tande-murami), or a sealant film may be laminated (sand lamination) on the melt-extruded resin. The thickness of the heat sealable resin layer is preferably about 10 to 100 μm.

EXAMPLES Next, although this invention is demonstrated concretely using an Example and a comparative example, this invention is not limited to these Examples. The following evaluation methods were used for measuring each characteristic.
(Oxygen barrier property: oxygen permeability)
It is oxygen permeability (ml / m ² · day · MPa) measured based on JIS K 7126B method using MOCON OX-TRAN 2/20 type. The measurement conditions were a temperature of 23 ° C. and a humidity of 65% RH.

(Water vapor barrier property: water vapor permeability)
Water vapor permeability (g / m ² · day) measured according to JIS K7129B method using a PERMATRAN W-3 / 31 type manufactured by MOCON. The measurement conditions were a temperature of 40 ° C. and a humidity of 90% RH.

(Lamination strength)
The laminate sample was cut into a test piece having a width of 15 mm and a length of 150 mm, peeled off in advance at the adhesive interface between the base film layer (B1) and the base film layer (B2), and the peeled both ends of the tensile tester. The average value of the tensile load when it was held with a gripping tool and pulled while being peeled T-shaped at a pulling speed of 200 mm / min was defined as the laminate strength (N / 15 mm). Further, the peeled surface was observed by a staining method and the peeled interface was identified.

(Retort processing)
A packaging bag having an inner size of 15 cm square was prepared from the gas barrier film laminate, filled with 200 cc of water, degassed and sealed, and treated with a shower type retort treatment machine at 120 ° C. for 30 minutes. For the evaluation of oxygen barrier properties and water vapor barrier properties, take out from the retort processing machine after cooling down, remove the filling water from the packaging bag, and store the sample sheet cut into single sheets in a temperature and humidity environment of the same conditions as the measurement conditions for 24 hours or more After that, the above gas barrier measurement was performed. For measurement of the laminate strength, the laminate strength was taken out from the retort processor after the temperature was lowered, the filling water was taken out from the packaging bag, the test piece was cut out in accordance with the laminate strength measurement method, and the laminate strength measurement was carried out.

(Wet tension)
The wetting tension (mN / m) was measured according to JIS K 6768 (1999).

(Example 1)
A composite oxide of silicon oxide and aluminum oxide is applied to the non-corona-treated surface of a biaxially stretched nylon film (product name: N1100-15 μm, manufactured by Toyobo Co., Ltd.) that has been corona-treated on one side using a wind-up type vacuum vapor deposition machine. A gas barrier nylon film having a thin film deposited thereon was produced. The wetting tension of the non-corona treated surface was 40 mN / m. Next, the vapor-deposited surface of the gas barrier nylon film and the corona-treated surface of the biaxially stretched polyester film (manufactured by Toyobo Co., Ltd., trade name E5100-12 μm) are combined with an adhesive / curing agent for dry lamination (manufactured by Toyo Morton Co., Ltd.). The product was laminated by a dry laminating method using a trade name TM-250HV / CAT-RT86). Subsequently, the nylon film surface of this laminate and a corona-treated surface of an unstretched polypropylene film (Toyobo Co., Ltd., trade name: P1153-60 μm) were similarly laminated by a dry laminating method. Aging was performed at 40 ° C. for 3 days to produce a gas barrier film laminate. The evaluation results of the obtained gas barrier film laminate are shown in Table 1.

(Example 2)
A composite oxide of silicon oxide / aluminum oxide is applied to the non-corona-treated surface of a biaxially stretched polyester film (trade name E5100-12 μm, manufactured by Toyobo Co., Ltd.) that has been subjected to corona treatment on one side using a winding-type vacuum vapor deposition machine A gas barrier polyester film having a thin film deposited thereon was produced. A vapor-deposited surface of a gas barrier polyester film and a biaxially stretched nylon film (trade name N1200-12 μm, manufactured by Toyobo Co., Ltd.) subjected to double-side corona treatment are used as an adhesive / curing agent for dry lamination (manufactured by Toyo Morton Co., Ltd.) No. TM-250HV / CAT-RT86) was laminated by a dry laminating method. Subsequently, the nylon film surface of this laminate and the corona-treated surface of an unstretched polypropylene film (Toyobo Co., Ltd., trade name: P1153-60 μm) were similarly laminated by a dry laminating method. Aging was performed at 40 ° C. for 3 days to produce a gas barrier film laminate. The evaluation results of the obtained gas barrier film laminate are shown in Table 1.

(Comparative Example 1)
A gas barrier film laminate was prepared in the same manner as in Example 1 except that vapor deposition was performed on a biaxially stretched nylon film that had been subjected to double-sided corona treatment instead of the biaxially stretched nylon film that had been subjected to single-sided corona treatment. The evaluation results of the obtained gas barrier film laminate are shown in Table 1.
(Comparative Example 2)
A gas barrier film laminate was produced in the same manner as in Example 2 except that vapor deposition was performed on the corona-treated surface of the biaxially stretched polyester film that had been subjected to single-sided corona treatment. The evaluation results of the obtained gas barrier film laminate are shown in Table 1.

  The gas barrier film laminate of the present invention and a packaging bag using the same are excellent in transparency and gas barrier properties, and particularly excellent in boil treatment and retort treatment, for example, soup, pickles, boiled salmon and wild vegetables, etc. It is possible to provide a packaging material suitable for filling and packaging a so-called water heavy bag.

It is explanatory drawing which shows the laminated structural example of the gas barrier film laminated body of this invention. It is explanatory drawing which shows the laminated structural example of the gas barrier film laminated body of this invention.

Explanation of symbols

1 Base film layer (B1)
2 Adhesive layer (A1)
3 Base film layer (B2)
4 Adhesive layer (A2)
5 Heat seal resin layer 6 Inorganic oxide layer

Claims (5)

It is a film laminate in which at least 5 layers of base film layer (B1) / adhesive layer (A1) / base film layer (B2) / adhesive layer (A2) / heat-sealable resin layer are laminated in this order. And a gas barrier made of an inorganic oxide on either the surface of the base film layer (B1) on the adhesive layer (A1) side or the surface of the base film layer (B2) on the adhesive layer (A1) side. Film laminate formed by depositing a conductive thin film layer, the water vapor permeability (g / m ² · day) of the laminate is 3.0 or less, and the water vapor permeability after hydrothermal treatment at 120 ° C. for 30 minutes (G / m < ² > * day) is 4.0 or less, The gas barrier film laminated body characterized by the above-mentioned.   The gas barrier film laminate, wherein the base film layer (B1) is a biaxially stretched polyester film and the base film layer (B2) is a biaxially stretched polyamide film.   The gas barrier film laminate, wherein the inorganic oxide comprises a composite oxide of aluminum oxide and silicon oxide.   A bag made using the gas barrier film laminate according to any one of claims 1 to 3.   It is a film laminate in which at least 5 layers of base film layer (B1) / adhesive layer (A1) / base film layer (B2) / adhesive layer (A2) / heat-sealable resin layer are laminated in this order. And a gas barrier made of an inorganic oxide on either the surface of the base film layer (B1) on the adhesive layer (A1) side or the surface of the base film layer (B2) on the adhesive layer (A1) side. A method for producing a gas barrier film laminate, wherein the wet tension before vapor deposition of the base film surface to be deposited is 45 mN / m or less in the method for producing a film laminate in which a conductive thin film layer is deposited.

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