Gas-barrier multilayer film

Abstract

A gas-barrier multilayer film, wherein (A) a first inorganic thin film layer, (C) a gas-barrier resin composition layer, and (D) a second inorganic thin film layer are stacked in this order with or without intervention of other layers on at least one surface of a plastic film, the gas-barrier resin composition layer (C) is formed from a gas-barrier resin composition comprising (a) a gas-barrier resin including an ethylene-vinyl alcohol-based copolymer, (b) an inorganic layered compound, and (c) at least one additive selected from coupling agents and crosslinking agents, and the content of the inorganic layered compound (b) in the gas-barrier resin composition is from 0.1% by mass to 20% by mass based on 100% by mass in total of the gas-barrier resin (a), the inorganic layered compound (b), and the additive (c).

Claims

1. A gas-barrier multilayer film, wherein (A) a first inorganic thin film layer, (C) a gas-barrier resin composition layer, and (D) a second inorganic thin film layer are stacked in this order with or without intervention of other layers on at least one surface of a plastic film, the gas-barrier resin composition layer (C) is formed from a gas-barrier resin composition comprising (a) a gas-barrier resin consisting of an ethylene-vinyl alcohol copolymer, (b) an inorganic layered compound, and (c) at least one additive selected from the group consisting of coupling agents and crosslinking agents, and the content of the inorganic layered compound (b) in the gas-barrier resin composition is from 0.1% by mass to 7.0% by mass based on 100% by mass in total of the gas-barrier resin (a), the inorganic layered compound (b), and the additive (c), and the first inorganic thin film layer (A) and/or the second inorganic thin film layer (D) is a silicon oxide/aluminum oxide two-component inorganic oxide thin film, wherein the content of aluminum oxide is 20% by mass to 75% by mass.

2. The gas-barrier multilayer film according to claim 1, wherein the inorganic layered compound (b) is smectite.

3. The gas-barrier multilayer film according to claim 1, wherein the coupling agent is a silane coupling agent having at least one kind of organic functional group.

4. The gas-barrier multilayer film according to claim 1, wherein the cross-linking agent is a cross-linking agent for a group capable of forming a hydrogen bond.

5. The gas-barrier multilayer film according to claim 1, wherein the content of the additive (c) is from 0.3% by mass to 20% by mass based on 100% by mass in total of the gas-barrier resin (a), the inorganic layered compound (b), and the additive (c).

6. The gas-barrier multilayer film according to claim 1, which has (B) an anchor coating layer between the first inorganic thin film layer (A) and the gas-barrier resin composition layer (C).

7. The gas-barrier multilayer film according to claim 6, wherein an anchor coating agent composition for forming the anchor coating layer (B) comprises a silane coupling agent having at least one kind of organic functional group.

8. The gas-barrier multilayer film according to claim 7, wherein the content of the silane coupling agent in the anchor coating agent composition is from 0.1% by mass to 10% by mass based on 100% by mass of the anchor coating agent composition.

9. The gas-barrier multilayer film according to claim 8, wherein two or more repeating units are repeated where a multilayered structure comprising the anchor coating layer (B), the gas-barrier resin composition layer (C) and the second inorganic thin film layer (D) forms each of the units.

10. The gas-barrier multilayer film according to claim 7, wherein two or more repeating units are repeated where a multilayered structure comprising the anchor coating layer (B), the gas-barrier resin composition layer (C) and the second inorganic thin film layer (D) forms each of the units.

11. The gas-barrier multilayer film according to claim 6, wherein two or more repeating units are repeated where a multilayered structure comprising the anchor coating layer (B), the gas-barrier resin composition layer (C) and the second inorganic thin film layer (D) forms each of the units.

12. The gas-barrier multilayer film according to claim 1, which has a primer coating layer between the plastic film and the first inorganic thin film layer (A).

Description

EXAMPLES

(1) The present invention will be described in detail below by way of examples, but the present invention is not limited by the following examples, and modifications which do not depart from the gist of the present invention are allowed and embraced within the technical scope of the present invention.

(2) 1. Evaluation Methods

(3) 1-1. Preparation of Laminated Gas-Barrier Multilayer Film for Evaluation

(4) Laminated gas-barrier multilayer films for evaluation (they are henceforth sometimes referred to as laminated films for evaluation) were obtained by laminating a non-stretched polypropylene film (P1147 produced by Toyobo Co., Ltd.: 70 m in thickness) as a heat seal layer on the second inorganic thin film layer of each of the gas-barrier multilayer films Nos. 1 through 17 (the gas-barrier resin composition layers for Nos. 13 and 17) by the dry lamination process using a urethane-based two-component curable adhesive, followed by aging at 40 C. for four days. The thickness after desiccation of the adhesive layer formed by the urethane-based two-component curable adhesive was 3 m.

(5) 1-2. Method of Measuring Lamination Strength

(6) A laminated film for evaluation was cut into a size of 15 mm in width and 200 mm in length to form a specimen and the lamination strength (before a retort treatment) thereof was measured under conditions including a temperature of 23 C. and a relative humidity of 65% by using a TENSILON universal material testing instrument (TENSILON UMT-II-500 manufactured by Toyo Baldwin Co., Ltd.). Water was applied to between the gas-barrier multilayer film and a non-stretched polypropylene film and then the strength at the time of peeling the films at a peeling angle of 90 degrees was measured with a tensile speed adjusted to 200 mm/minute.

(7) On the other hand, a laminated film for evaluation was subjected to a retort treatment for 30 minutes that involved holding the film in water vapor having a temperature of 121 C. and a pressure of 0.2 MPa (2 kgf/cm.sup.2) and subsequently was dried at 40 C. for 24 hours, and then a specimen was cut from the resulting laminated film after the retort treatment in the same procedures as described above, followed by measurement of lamination strength (after a retort treatment).

(8) 1-3. Oxygen Permeability

(9) For a laminated film for evaluation, the oxygen permeability (before a retort treatment) was measured under an atmosphere represented by a temperature of 23 C. and a humidity of 65% RH by using an oxygen permeability analyzer (OX-TRAN 2/20 manufactured by MOCON) according to the electrolysis sensor method (appendix A) of JIS K7126-2.

(10) On the other hand, a laminated film for evaluation was subjected to a retort treatment for 30 minutes that involved holding the film in water vapor having a temperature of 121 C. and a pressure of 0.2 MPa (2 kgf/cm.sup.2) and subsequently was dried at 40 C. for 24 hours, and then the oxygen permeability (after a retort treatment) of the resulting laminated film after the retort treatment was measured in the same procedures as described above.

(11) 1-4. Water Vapor Permeability Measurement

(12) For a laminated film for evaluation, the water vapor permeability (before a retort treatment) was measured under an atmosphere represented by a temperature of 40 C. and a humidity of 100% RH by using a water vapor permeability analyzer (PERMATRAN-W 3/33MG manufactured by MOCON) according to the JIS K7129-B method. In the measurement, the laminated film for evaluation was humidity controlled with the film being placed so that water vapor would permeate from the plastic film side toward the gas-barrier resin composition layer side of the film.

(13) 2. Preparation

(14) 2-1. Preparation of Plastic Film

(15) Polyethylene terephthalate (PET) having an intrinsic viscosity of 0.62 (30 C., phenol/tetrachloroethane (mass ratio)=60/40) and containing 100 ppm of silica was preliminarily crystallized, then dried, subsequently extruded at 280 C. by using an extruder equipped with a T-shaped die, and then rapidly cooled and solidified on a drum having a surface temperature of 40 C., so that an amorphous sheet was obtained. Next, this amorphous sheet was four-fold stretched in the longitudinal direction at 100 C. between a heating roll and a chill roll, so that a uniaxially stretched PET film was obtained as a plastic film.

(16) 2-2. Preparation of Coating Liquid for Forming Primer Coating Layer

(17) 45.59 parts by mass of meta-xylylene diisocyanate (MXDI), 93.9 parts by mass of hydrogenated xylylene diisocyanate (hydrogenated XDI (1,3-bis(isocyanatemethyl)cyclohexane)), 24.8 parts by mass of ethylene glycol, 13.4 parts by mass of dimethylol propionic acid, and 80.2 parts by mass of methyl ethyl ketone as a solvent were mixed and then made to react at 70 C. for 5 hours under a nitrogen atmosphere. The resulting carboxyl group-containing urethane prepolymer solution was neutralized with 9.6 parts by mass of triethylamine at 40 C. This urethane prepolymer solution was dispersed in 624.8 parts by mass of water by HOMO-DISPER and then subjected to a chain elongation reaction using 21.1 parts by mass of 2-[(2-aminoethyl)amino]ethanol, followed by distillation of methyl ethyl ketone, thereby affording a polyurethane resin, dispersed in water, having a solid content of 25% by mass and an average particle diameter of 90 nm. The acid value of this resin was 26.9 mgKOH/g and the sum total of the urethane group concentration and the urea group concentration was 39.6% by mass. The resin was diluted with water, thereby forming an aqueous polyurethane resin dispersion with a solid content of 15% by mass.

(18) On the other hand, 466 parts by mass of dimethyl terephthalate, 466 parts by mass of dimethyl isophthalate, 401 parts by mass of neopentyl glycol, 443 parts by mass of ethylene glycol, and 0.52 parts by mass of tetra-n-butyl titanate were charged into a stainless steel autoclave equipped with a stirrer, a thermometer, and a partial refluxing condenser, followed by execution of a transesterification reaction from 160 C. to 220 C. over 4 hours. Subsequently, 23 parts by mass of fumaric acid was added and then the temperature was increased from 200 C. to 220 C. over 1 hour, so that an esterification reaction was performed. Subsequently, the temperature was raised to 255 C. and the pressure in the reaction system was reduced slowly, followed by execution of a reaction under a pressure of 26.7 Pa (0.2 mmHg) for 1 hour and 30 minutes. Then, 19 parts by mass of trimellitic anhydride was added and stirred at 220 C. under a nitrogen atmosphere for 1 hour, so that a copolymerized polyester resin was obtained. The resulting copolymerized polyester resin was pale yellow in color and transparent and had a weight average molecular weight of 12000.

(19) Next, a reactor equipped with a stirrer, a thermometer, a refluxing device, and a quantitative dropping device was charged with 75 parts by mass of the copolymerized polyester resin obtained above, 56 parts by mass of methyl ethyl ketone, and 19 parts by mass of isopropyl alcohol and heated at 65 C. with stirring, thereby dissolving the resin. After complete dissolution of the resin, a solution prepared by dissolving a mixture of 17.5 parts by mass of methacrylic acid and 7.5 parts by mass of ethyl acrylate and 1.2 parts by mass of azobisdimethylvaleronitrile in 25 parts by mass of methyl ethyl ketone was dropped into the completely dissolved copolymerized polyester resin solution at a rate of 0.2 mL/min, and stirring was continued for additional 2 hours after completion of the dropping. Subsequently, 300 parts by mass of water and 25 parts by mass of triethylamine were added to the resulting reaction solution and stirred for 1 hour, so that a dispersion of a grafted polyester was obtained. The temperature of the resulting dispersion was raised to 100 C. and thereby methyl ethyl ketone, isopropyl alcohol, and excess triethylamine were removed by distillation, so that an aqueous copolymerized polyester dispersion was obtained. The copolymerized polyester resin particles in the resulting dispersion were white in color and had an average particle diameter of 300 nm and a B type viscosity at 25 C. of 50 cps. This was diluted with water, thereby forming an aqueous copolymerized polyester resin dispersion with a solid content of 25% by mass.

(20) The aqueous polyurethane resin dispersion and the aqueous copolymerized polyester resin dispersion were mixed so that the ratio of the polyurethane resin to the copolymerized polyester resin might become polyurethane resin/polyester resin (mass ratio)=20/80, and then the mixture was diluted with water, thereby forming a coating liquid for primer coating layers, the liquid having a solid content of 10% by mass.

(21) 2-3. Preparation of Coating Liquid for Forming Anchor Coating Layer

(22) An isocyanate-based curing agent (TAKELAC (registered trademark) A-50, produced by Mitsui Chemicals, Inc.) was added to a urethane-based resin (TAKELAC (registered trademark) A525-S, produced by Mitsui Chemicals, Inc.) and a solid concentration was adjusted to 6.5% by mass using ethyl acetate as a solvent. To this was added an epoxy-based silane coupling agent (KBM403, produced by Shin-Etsu Chemical Co., Ltd.) so that the content thereof in a resin composition for anchor coating (100% by mass of the resin, the curing agent, and the silane coupling agent in total) might become 5% by mass, thereby affording a resin composition as a coating liquid for an anchor coating layer (a resin composition for anchor coating).

(23) 2-4. Preparation of Material of Gas-Barrier Resin Composition Layer

(24) <Preparation of Ethylene-Vinyl Alcohol-Based Copolymer Solution>

(25) To a mixed solvent of 20.996 parts by mass of purified water and 51 parts by mass of n-propyl alcohol (NPA) was added 15 parts by mass of an ethylene-vinyl alcohol copolymer (SG-525, produced by The Nippon Synthetic Chemical Industry Co., Ltd; a polymer prepared by saponifying an ethylene-vinyl acetate copolymer, ethylene content: 26 mol %; degree of saponification of vinyl acetate component: about 100%, (hereinafter, this may be abbreviated as EVOH)). Moreover, 13 parts by mass of an aqueous hydrogen peroxide solution (concentration: 30% by mass) and 0.004 parts by mass of iron sulfate (FeSO.sub.4) were added and heated up to 80 C. with stirring, followed by a reaction for about 2 hours. Following subsequent cooling of reaction solution, catalase was added so that its concentration might become 3000 ppm and residual hydrogen peroxide was removed, so that an approximately transparent ethylene-vinyl alcohol-based copolymer solution (EVOH solution) having a solid content of 15% by mass was obtained.

(26) <Preparation of Polyvinyl Alcohol Resin Solution>

(27) To 70 parts by mass of a mixed solvent made of 40% by mass of purified water and 60% by mass of n-propyl alcohol (NPA) was added and dissolved 30 parts by mass of completely saponified polyvinyl alcohol resin (Gosenol (registered trademark) NL-05, produced by The Nippon Synthetic Chemical Industry Co., Ltd.; degree of saponification: 99.5% or more), so that a transparent polyvinyl alcohol resin solution (PVA solution) having a solid content of 30% by mass was obtained.

(28) <Preparation of Inorganic Layered Compound Dispersion Liquid>

(29) Into 96 parts by mass of purified water was added with stirring 4 parts by mass of montmorillonite (Kunipia (registered trademark) F, produced by Kunimine Industries Co., Ltd.), an inorganic layered compound, which was then fully dispersed under a set pressure of 50 MPa by using a high pressure dispersion apparatus. Then, it was held at 40 C. for one day, thereby affording an inorganic layered compound dispersion liquid having a solid content of 4% by mass.

(30) <Additives>

(31) Cross-linking agent: zirconium oxydichloride (Zircosol (registered trademark) Zc-20, produced by Daiichi Kigenso Kagaku Kogyo Co., Ltd.; solid content: 20% by mass)

(32) Cross-linking agent: titanium lactate (ORGATIX (registered trademark) TC-310, produced by Matsumoto Fine Chemical Co., Ltd.; solid content: about 45% by mass)

(33) Silane coupling agent: 3-glycidoxypropyltriethoxysilane (KBE-403, produced by Shin-Etsu Chemical Co., Ltd.; solid content: 100% by mass)

(34) 2-5. Preparation of Coating Liquid for Forming Gas-Barrier Resin Composition Layer

Preparation Example 1

(35) To 62.30 parts by mass of a mixed solvent A (purified water:n-propyl alcohol (mass ratio)=40:60) was added 31.75 parts by mass of an EVOH solution, followed by fully stirring and mixing. In addition, to this solution was added 5.95 parts by mass of an inorganic layered compound dispersion liquid with high speed stirring. To 100 parts by mass of this dispersion liquid was added 3 parts by mass of a cation exchange resin, followed by stirring for one hour at such a stirring speed that no breakage of the ion exchange resin occurred, thereby removing cations, and then only the cation exchange resin was removed by filtration using a strainer.

(36) The dispersion liquid prepared by the above-described operations was subjected further to a dispersion treatment under a set pressure of 50 MPa using a high-pressure dispersion apparatus. To 97 parts by mass of the mixed liquid resulting from the dispersion treatment were added 0.75 parts by mass of a cross-linking agent (zirconium oxydichloride) as an additive, 0.9 parts by mass of purified water, and 1.35 parts by mass of NPA, followed by mixing and stirring, and then the resultant was filtered through a 255-mesh filter (opening: 60 m), so that coating liquid No. 1 having a solid content of 5% by mass for forming a gas-barrier resin composition layer was obtained.

Preparation Example 2

(37) Coating liquid No. 2 having a solid content of 5% by mass for forming a gas-barrier resin composition layer was obtained in the same manner as in Preparation Example 1 except for changing the used amounts of the mixed solvent A, the EVOH solution, and the inorganic layered compound dispersion liquid to 65.76 parts by mass of the mixed solvent A, 33.00 parts by mass of the EVOH solution, and 1.24 parts by mass of the inorganic layered compound dispersion liquid.

Preparation Example 3

(38) Coating liquid No. 3 having a solid content of 5% by mass for forming a gas-barrier resin composition layer was obtained in the same manner as in Preparation Example 1 except for changing the used amounts of the mixed solvent A, the EVOH solution, and the inorganic layered compound dispersion liquid to 64.00 parts by mass of the mixed solvent A, 32.36 parts by mass of the EVOH solution, and 3.64 parts by mass of the inorganic layered compound dispersion liquid.

Preparation Example 4

(39) Coating liquid No. 4 having a solid content of 5% by mass for forming a gas-barrier resin composition layer was obtained in the same manner as in Preparation Example 1 except for changing the used amounts of the mixed solvent A, the EVOH solution, and the inorganic layered compound dispersion liquid to 66.21 parts by mass of the mixed solvent A, 33.17 parts by mass of the EVOH solution, and 0.62 parts by mass of the inorganic layered compound dispersion liquid.

Preparation Example 5

(40) Coating liquid No. 5 having a solid content of 5% by mass for forming a gas-barrier resin composition layer was obtained in the same manner as in Preparation Example 1 except for changing the used amounts of the mixed solvent A, the EVOH solution, and the inorganic layered compound dispersion liquid to 60.67 parts by mass of the mixed solvent A, 31.15 parts by mass of the EVOH solution, and 8.18 parts by mass of the inorganic layered compound dispersion liquid.

Preparation Example 6

(41) Coating liquid No. 6 having a solid content of 5% by mass for forming a gas-barrier resin composition layer was obtained in the same manner as in Preparation Example 1 except for changing the additive to 0.15 parts by mass of a silane coupling agent (3-glycidoxypropyltriethoxysilane), and the used amounts of the purified water and the NPA to 1.14 parts by mass of the purified water and 1.71 parts by mass of the NPA.

Preparation Example 7

(42) Coating liquid No. 7 having a solid content of 5% by mass for forming a gas-barrier resin composition layer was obtained in the same manner as in Preparation Example 1 except for changing the additive to 0.33 parts by mass of a cross-linking agent (titanium lactate), and the used amounts of the purified water and the NPA to 1.07 parts by mass of the purified water and 1.60 parts by mass of the NPA.

Preparation Example 8

(43) Coating liquid No. 8 having a solid content of 5% by mass for forming a gas-barrier resin composition layer was obtained in the same manner as in Preparation Example 1 except for changing the used amounts of the mixed solvent A, the EVOH solution, and the inorganic layered compound dispersion liquid to 59.10 parts by mass of the mixed solvent A, 30.58 parts by mass of the EVOH solution, and 10.32 parts by mass of the inorganic layered compound dispersion liquid.

Preparation Example 9

(44) To 61.52 parts by mass of a mixed solvent A was added 32.40 parts by mass of an EVOH solution, followed by fully stirring and mixing. In addition, to this solution was added 6.08 parts by mass of an inorganic layered compound dispersion liquid with high speed stirring. To 100 parts by mass of this dispersion liquid was added 3 parts by mass of a cation exchange resin, followed by stirring for one hour at such a stirring speed that no breakage of the ion exchange resin occurred, thereby removing cations, and then only the cation exchange resin was removed by filtration using a strainer.

(45) The dispersion liquid prepared by the above-described operations was subjected further to a dispersion treatment under a set pressure of 50 MPa using a high-pressure dispersion apparatus. To 97 parts by mass of the mixed liquid resulting from the dispersion treatment were added 0.25 parts by mass of a cross-linking agent (zirconium oxydichloride) as additive, and 2.75 parts by mass of the mixed solvent A, followed by mixing and stirring, and then the resultant was filtered through a 255-mesh filter, so that coating liquid No. 9 having a solid content of 5% by mass for forming a gas-barrier resin composition layer was obtained.

Preparation Example 10

(46) To 65.02 parts by mass of a mixed solvent A was added 29.46 parts by mass of an EVOH solution, followed by fully stirring and mixing. In addition, to this solution was added 5.52 parts by mass of an inorganic layered compound dispersion liquid with high speed stirring. To 100 parts by mass of this dispersion liquid was added 3 parts by mass of a cation exchange resin, followed by stirring for one hour at such a stirring speed that no breakage of the ion exchange resin occurred, thereby removing cations, and then only the cation exchange resin was removed by filtration using a strainer.

(47) The dispersion liquid prepared by the above-described operations was subjected further to a dispersion treatment under a set pressure of 50 MPa using a high-pressure dispersion apparatus. To 97 parts by mass of the mixed liquid resulting from the dispersion treatment were added 2.50 parts by mass of a cross-linking agent (zirconium oxydichloride) as additive, and 0.50 parts by mass of the mixed solvent A, followed by mixing and stirring, and then the resultant was filtered through a 255-mesh filter, so that coating liquid No. 10 having a solid content of 5% by mass for forming a gas-barrier resin composition layer was obtained.

Preparation Example 11

(48) To 66.67 parts by mass of a mixed solvent A was added 33.33 parts by mass of an EVOH solution, followed by fully stirring and mixing. In addition, to 100 parts by mass of this dispersion liquid was added 3 parts by mass of a cation exchange resin, followed by stirring for one hour at such a stirring speed that no breakage of the ion exchange resin occurred, thereby removing cations, and then only the cation exchange resin was removed by filtration using a strainer.

(49) To 97 parts by mass of the mixed liquid obtained by the above-described were added 0.75 parts by mass of a cross-linking agent (zirconium oxydichloride) as additive, and 2.25 parts by mass of the mixed solvent A, followed by mixing and stirring, and then the resultant was filtered through a 255-mesh filter, so that coating liquid No. 11 having a solid content of 5% by mass for forming a gas-barrier resin composition layer was obtained.

Preparation Example 12

(50) To 78.17 parts by mass of a mixed solvent A was added 15.87 parts by mass of a polyvinyl alcohol resin solution (PVA solution), followed by fully stirring and mixing. In addition, to this solution was added 5.95 parts by mass of an inorganic layered compound dispersion liquid with high speed stirring. To 100 parts by mass of this dispersion liquid was added 3 parts by mass of a cation exchange resin, followed by stirring for one hour at such a stirring speed that no breakage of the ion exchange resin occurred, thereby removing cations, and then only the cation exchange resin was removed by filtration using a strainer.

(51) The dispersion liquid prepared by the above-described operations was subjected further to a dispersion treatment under a set pressure of 50 MPa using a high-pressure dispersion apparatus. To 97 parts by mass of the mixed liquid resulting from the dispersion treatment were added 0.75 parts by mass of a cross-linking agent (zirconium oxydichloride) as additive, and 2.25 parts by mass of the mixed solvent A, followed by mixing and stirring, and then the resultant was filtered through a 255-mesh filter, so that coating liquid No. 12 having a solid content of 5% by mass for forming a gas-barrier resin composition layer was obtained.

(52) 3. Preparation of Gas-Barrier Multilayer Film

Production Example 1

(53) The coating liquid for primer coating layers was charged into a temperature control tank linked to a fountain for discharging the liquid to a film surface and its temperature was controlled to 25 C. with stirring. A fountain was brought into contact with one side of the uniaxially stretched PET film, and a clean liquid resulting from the removal of foreign substances by filtration through a capsule filter with 30p holes made of polypropylene was applied to one side of the uniaxially stretched PET film at a discharge rate of 0.028 m.sup.3/min. Subsequently, a smooth bar with a diameter of 14 mm was attached to the surface of the liquid and the coating liquid was scraped so that the thickness of a primer coating layer after stretching might become 0.20 m. The coating rate (film formation rate) was adjusted to 150 m/min and the rotation speed of the bar associated with coatability was adjusted to 60 rpm (2.6 m/min in circumferential speed) in the same direction as the running direction of the film.

(54) Then, the film was led to a drying zone (tenter) and the solvent was volatilized and dried at a preheating temperature of 100 C. Subsequently, the film was 4.0-fold stretched in the transverse direction at a temperature of 120 C. and then was subjected to a heat setting treatment with 6% relaxation in the transverse direction within a heat setting zone set to 225 C. Although the treatment times at respective temperatures were 3 seconds for a preheating temperature of 100 C., 5 seconds for a stretching temperature of 120 C., and 8 seconds for a heat setting treatment temperature of 225 C., the treatment times are not limited thereto. Then, the film was cooled and its both edges were trimmed, so that a 12-m thick biaxially stretched PET film was formed continuously over 1000 m or more and thereby a mill roll was obtained. The resulting mill roll was slit over a width of 400 mm and a length of 1000 m and then was wound on a 3-inch paper sleeve, thereby affording a PET film with a primer coating layer.

(55) Then, a two-component inorganic oxide thin film layer of silicon oxide and aluminum oxide (the ratio of silicon oxide/aluminum oxide (mass ratio)=50/50) was formed as the first inorganic thin film layer on the primer coating layer surface of the PET film with the primer coating layer. Specifically, the formation of the two-component inorganic oxide thin film of silicon oxide (silicon dioxide) and aluminum oxide was performed by an electron beam vapor deposition process by using granular SiO.sub.2 (99.99% in purity) and Al.sub.2O.sub.3 (99.9% in purity) as large as about 3 mm to about 5 mm as vapor deposition sources (vapor deposition materials) and also using an EB (Electron Beam) gun as a heat source. The vapor deposition materials were charged in two separate portions without being mixed, the emission current of the EB gun was adjusted to 1.2 A, and then SiO.sub.2 and Al.sub.2O.sub.3 were heated on a time sequential basis so that the mass ratio of SiO.sub.2 to Al.sub.2O.sub.3 might become 50:50. At this time, the film feeding rate, the pressure in vapor deposition, and the temperature of the roll for chilling the film in vapor deposition were adjusted to 30 m/min, 110.sup.2 Pa, and 10 C., respectively. The thus-obtained first inorganic thin film layer was 27 nm in thickness.

(56) Then, the coating liquid for an anchor coating layer was applied onto the first inorganic thin film layer by a gravure roll coating method and then was dried, so that an anchor coating layer was formed. The thickness of the anchor coating layer after drying was 0.30 m.

(57) Subsequently, the coating liquid No. 1 for forming gas-barrier resin composition layer was applied onto the anchor coating layer by a gravure roll coating method and then was dried at 160 C., so that a gas-barrier resin composition layer was formed. The thickness of the gas-barrier resin composition layer after drying was 0.25 m.

(58) Subsequently, a two-component inorganic oxide thin film layer of silicon oxide and aluminum oxide (the proportion of silicon oxide/aluminum oxide (mass ratio)=50/50) was formed as the second inorganic thin film layer on the gas-barrier resin composition layer in the same procedures as for the above-described first inorganic thin film layer, so that a gas-barrier multilayer film No. 1 was obtained. The thickness of the second inorganic thin film layer was 27 nm.

Production Examples 2 Through 10

(59) Gas-barrier multilayer films No. 2 through 10 were produced in the same procedures as in Production Example 1 except for changing the coating liquid for forming gas-barrier resin composition layer to the coating liquid No. 2 through 10 for forming gas-barrier resin composition layer.

Production Example 11

(60) Gas-barrier multilayer film No. 11 was produced by further forming an anchor coating layer, a gas-barrier resin composition layer, and a second inorganic thin film layer in the same procedures as in Production Example 1 on the second inorganic thin film layer of the gas-barrier multilayer film No. 1 produced in Production Example 1.

Production Example 12

(61) Gas-barrier multilayer film No. 12 was produced by further forming an anchor coating layer, a gas-barrier resin composition layer, and a second inorganic thin film layer in the same procedures as in Production Example 1 on the second inorganic thin film layer (outermost layer) of the gas-barrier multilayer film No. 11 produced in Production Example 11.

Production Example 13

(62) Gas-barrier multilayer film No. 13 was produced in the same procedures as in Production Example 1 except that the second inorganic thin film layer was not formed.

Production Example 14

(63) Gas-barrier multilayer film No. 14 was produced in the same procedures as in Production Example 1 except that the gas-barrier resin composition layer was not formed.

Production Examples 15 and 16

(64) Gas-barrier multilayer films No. 15, 16 were produced in the same procedures as in Production Example 1 except for changing the coating liquid for forming gas-barrier resin composition layer to the coating liquid No. 11, 12 for forming gas-barrier resin composition layer.

Production Example 17

(65) Gas-barrier multilayer film No. 17 was produced in the same procedures as in Production Example 1 except that the film feeding speed was adjusted to 16 m/min in forming the first inorganic thin film layer so that the thickness of the first inorganic thin film layer became 50 nm, the pressure in vapor deposition was adjusted to 110.sup.2 Pa, the temperature of a roll for cooling the film in vapor deposition was adjusted to 10 C., and the second inorganic thin film layer was not formed.

(66) The configurations and evaluation results of the prepared gas-barrier multilayer films Nos. 1 through 17 are shown in Tables 1, 2 and 3. The examples shown in Tables 1 and 2 are the example of the present invention, and the examples shown in Table 3 correspond to the comparative example.

(67) TABLE-US-00001 TABLE 1 Gas-barrier multilayer film No. 1 2 3 4 5 6 7 8 Primer layer Present Present Present Present Present Present Present Present First Composition (mass ratio) 50/50 50/50 50/50 50/50 50/50 50/50 50/50 50/50 inorganic (Al.sub.2O.sub.3/SiO.sub.2) thin film Thickness (nm) 27 27 27 27 27 27 27 27 layer (A) Re- Anchor Anchor Resin composition Urethane- Urethane- Urethane- Urethane- Urethane- Urethane- Urethane- Urethane- peat- coating coating based based based based based based based based ing layer (B) agent resin adhesive adhesive adhesive adhesive adhesive adhesive adhesive adhesive unit composition Silane Kind Epoxy-based Epoxy-based Epoxy-based Epoxy-based Epoxy-based Epoxy-based Epoxy-based Epoxy-based coupling Added 5 5 5 5 5 5 5 5 agent amount (% by mass) Thickness (m) 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Gas- Gas-barrier Copolymer EVOH EVOH EVOH EVOH EVOH EVOH EVOH EVOH barrier resin Inorganic Kind Montmorillonite Montmorillonite Montmorillonite Montmorillonite Montmorillonite Montmorillonite Montmorillonite Montmorillonite resin composition layered Added 4.6 1.0 2.8 0.5 6.3 4.6 4.6 8.0 compo- compound amount sition (% by mass) layer (C) Crosslinking Kind Zirconium Zirconium Zirconium Zirconium Zirconium Titanium Zirconium agent oxydichloride oxydichloride oxydichloride oxydichloride oxydichloride lactate oxydichloride Added 3.0 3.0 3.0 3.0 3.0 3.0 3.0 amount (% by mass) Coupling Kind Silane agent coupling agent containing isocyanate group Added 3.0 amount (% by mass) Thickness (m) 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Second Composition (mass ratio) 50/50 50/50 50/50 50/50 50/50 50/50 50/50 50/50 inorganic (Al.sub.2O.sub.3/SiO.sub.2) thin film Thickness (nm) 27 27 27 27 27 27 27 27 layer (D) Number of lamination of repeating units 1 1 1 1 1 1 1 1 Number of layers (not including plastic film) 5 5 5 5 5 5 5 5 Before retort Lamination strength (N/15 mm) 4.8 6.0 5.4 5.7 4.2 4.5 4.0 4.0 treatment Oxygen permeability 0.4 0.9 0.5 1.0 0.7 0.4 0.6 1.0 (ml/m.sup.2dMPa) Water vapor permeability (g/m.sup.2d) 0.07 0.09 0.07 0.10 0.09 0.07 0.08 0.10 After retort Lamination strength (N/15 mm) 3.2 4.0 3.6 3.8 3.0 3.0 2.8 2.5 treatment Oxygen permeability 0.8 1.8 1.0 1.8 1.7 0.8 1.0 1.9 (ml/m.sup.2dMPa) Water vapor permeability (g/m.sup.2d) 0.15 0.18 0.15 0.20 0.17 0.15 0.16 0.17

(68) TABLE-US-00002 TABLE 2 Gas-barrier multilayer film No. 9 10 11 12 Primer layer Present Present Present Present First Composition (mass ratio) 50/50 50/50 50/50 50/50 inorganic (Al.sub.2O.sub.3/SiO.sub.2) thin film Thickness (nm) 27 27 27 27 layer (A) Repeating unit Anchor Anchor Resin composition Urethane- Urethane- Urethane- Urethane- coating coating based based based based layer (B) agent resin adhesive adhesive adhesive adhesive composition Silane Kind Epoxy-based Epoxy-based Epoxy-based Isocyanate- coupling based agent Added 5 5 5 5 amount (% by mass) Thickness (m) 0.3 0.3 0.3 0.3 Gas- Gas-barrier Copolymer EVOH EVOH EVOH EVOH barrier resin Inorganic Kind Montmorillonite Montmorillonite Montmorillonite Montmorillonite resin composition layered Added 4.7 4.3 4.6 4.6 composition compound amount layer (C) (% by mass) Crosslinking Kind Zirconium Zirconium Zirconium Zirconium agent oxydichloride oxydichloride oxydichloride oxydichloride Added 1.0 10.0 3.0 3.0 amount (% by mass) Coupling Kind agent Added amount (% by mass) Thickness (m) 0.25 0.25 0.25 0.25 Second Composition (mass ratio) 50/50 50/50 50/50 50/50 inorganic (Al.sub.2O.sub.3/SiO.sub.2) thin film Thickness (nm) 27 27 27 27 layer (D) Number of lamination of repeating units 1 1 2 3 Number of layers (not including plastic film) 5 5 8 11 Before retort Lamination strength (N/15 mm) 3.8 6.1 4.8 4.7 treatment Oxygen permeability 0.4 1.1 0.1 0.04 (ml/m.sup.2dMPa) Water vapor permeability (g/m.sup.2d) 0.07 0.12 0.02 0.008 After retort Lamination strength (N/15 mm) 2.2 4.5 3.2 3.3 treatment Oxygen permeability 0.7 2.0 0.7 0.3 (ml/m.sup.2dMPa) Water vapor permeability (g/m.sup.2d) 0.15 0.20 0.10 0.08

(69) TABLE-US-00003 TABLE 3 Gas-barrier multilayer film No. 13 14 15 16 17 Primer layer Present Present Present Present Present First Composition (mass ratio) 50/50 50/50 50/50 50/50 50/50 inorganic (Al.sub.2O.sub.3/SiO.sub.2) thin film Thickness (nm) 27 27 27 27 50 layer (A) Re- Anchor Anchor Resin composition Urethane- Urethane- Urethane- Urethane- Urethane- peat- coating coating based based based based based ing layer (B) agent resin adhesive adhesive adhesive adhesive adhesive unit compo- Silane Kind Epoxy-based Epoxy-based Epoxy-based Epoxy-based Epoxy-based sition coupling Added 5 5 5 5 5 agent amount (% by mass) Thickness (m) 0.3 0.3 0.3 0.3 0.3 Gas- Gas- Copolymer EVOH EVOH PVH EVOH barrier barrier Inorganic Kind Montmorillonite Montmorillonite Montmorillonite resin resin layered Added 4.6 4.6 4.6 compo- compo- compound amount sition sition (% by mass) layer (C) Crosslinking Kind Zirconium Zirconium Zirconium Zirconium agent oxydichloride oxydichloride oxydichloride oxydichloride Added 3.0 3.0 3.0 3.0 amount (% by mass) Coupling Kind agent Added amount (% by mass) Thickness (m) 0.25 0.25 0.25 Second Composition (mass ratio) 50/50 50/50 50/50 inorganic (Al.sub.2O.sub.3/SiO.sub.2) thin film Thickness (nm) 27 27 27 layer (D) Number of lamination of repeating units 1 Number of layers (not including plastic film) 4 4 5 4 4 Before retort Lamination strength (N/15 mm) 5.2 7.5 3.0 2.5 5.4 treatment Oxygen permeability 4 10 6 6 2 (ml/m.sup.2dMPa) Water vapor permeability (g/m.sup.2d) 0.6 1.9 1.6 1.7 0.3 After retort Lamination strength (N/15 mm) 4.0 5.0 1.4 Delamination 4.2 treatment Oxygen permeability 0 21 18 6 (ml/m.sup.2dMPa) Water vapor permeability (g/m.sup.2d) 1.8 3.2 3.1 1.0

(70) Gas-barrier multilayer films Nos. 1 through 12 satisfy the requirements of the present invention. These films exhibited high lamination strength and low values of oxygen permeability and water vapor permeability even after a retort treatment. In particular, the gas-barrier multilayer films Nos. 11 and 12, in which the number of lamination of repeating units is two or more, are particularly superior in oxygen permeability and water vapor permeability after a retort treatment.

(71) While gas-barrier multilayer film No. 13 is one not having a second inorganic thin film layer, gas-barrier multilayer film No. 14 is one not having a gas-barrier resin composition layer, and gas-barrier multilayer film No. 15 is one in which the gas-barrier resin composition does not contain an inorganic layered compound, these all exhibit high values in both oxygen permeability and water vapor permeability. Gas-barrier multilayer film No. 16, which is the case where the gas-barrier resin in the gas-barrier resin composition is polyvinyl alcohol (PVA), exhibited high values in oxygen permeability and water vapor permeability before a retort treatment and the gas-barrier multilayer film and the non-stretched polypropylene film were peeled from each other during the retort treatment. Although gas-barrier multilayer film No. 17 has been increased in the thickness of the first inorganic thin film layer instead of having no second inorganic thin film layer, oxygen permeability and water vapor permeability comparable to those of the present invention can be obtained because it does not have a configuration in which a gas-barrier resin composition layer is sandwiched by a first inorganic thin film layer and a second inorganic thin film layer.

INDUSTRIAL APPLICABILITY

(72) According to the present invention, there can be obtained a gas-barrier multilayer film having superior gas-barrier properties against oxygen and water vapor, being high in interlayer adhesion power, and being superior in lamination strength. In particular, a gas-barrier multilayer film can be obtained which is a small decrease in gas-barrier properties and interlayer adhesion power even through retort treatment and which is suitable for various applications and high in practicality. Moreover, a gas-barrier multilayer film is formed which is superior in production stability and with which uniform characteristics can be obtained easily.

(73) The gas-barrier film of the present invention can be widely used not only in foods packaging for retort but also for applications for packaging for various, such as foods, medicaments, and industrial products, as well as industrial applications, such as solar batteries, electronic papers, organic EL devices, and semiconductor devices.