JPWO2008120600A1 - Gas barrier film - Google Patents

Abstract

(A) unsaturated nitrile having a proportion of 25 to 40% by weight of the inorganic compound vapor-deposited layer and the copolymer on at least one surface of the substrate made of the polyester film, and a proportion of the copolymer in the copolymer of 20 -30 wt% of (b) an unsaturated compound having a hydroxyl group and (c) one or more selected from the group consisting of unsaturated carboxylic acid ester, styrene, unsaturated carboxylic acid, unsaturated hydrocarbon and vinyl ester An excellent oxygen and oxygen gas layer composed of a main component composed of a copolymer of three components with an unsaturated compound as a monomer, and a gas barrier layer composed of a compound having an isocyanate group (curing agent) in sequence. Providing a gas barrier film that has both water-blocking performance and resistance to heat sterilization.

Description

  The present invention relates to a gas barrier film having excellent oxygen and water vapor barrier performance and resistance to heat sterilization treatment such as boil and retort treatment.

  Gas barrier films and packaging materials using the same are already well known. The material having the best gas barrier property is aluminum foil. However, an aluminum foil alone has a weak pinhole strength and cannot be used except for special applications. For this reason, it is almost used as an intermediate layer of a laminate film. The gas barrier property of an aluminum laminate film is very excellent. However, since this film is opaque, the contents cannot be seen, it is difficult to determine whether it has been reliably heat-sealed, or it cannot be used as a packaging material for foods that require cooking using a microwave oven.

  In addition, thermoplastic films such as polyester films and polyamide films are excellent in strength, transparency, and moldability, and thus are used in a wide range of applications as packaging materials. However, these thermoplastic resin films have high gas permeability such as oxygen and water vapor. For this reason, when used for packaging general foods, boiled foods, retort processed foods, etc., the food may be altered or deteriorated by long-term storage.

  In order to solve this problem, conventional materials that require gas barrier properties such as food packaging materials include polyolefin film, nylon film, polyethylene terephthalate film (hereinafter abbreviated as “PET”), etc., and vinylidene chloride (hereinafter referred to as “PVDC”). Films coated with an emulsion or the like (abbreviated as “)” have been used in many cases. A film in which a PVDC layer is formed by coating exhibits a high oxygen barrier property not only under a low humidity but also under a high humidity, and also has a high barrier property against water vapor. However, when the PVDC coated film is discarded by incineration, there is a risk of generation of chlorine gas due to chlorine in PVDC and generation of dioxins. Thus, since the PVDC coat film has a possibility of having a great adverse effect on the environment and the human body, it is strongly desired to shift to other materials.

  As a gas barrier material not containing chlorine, a polyvinyl alcohol (hereinafter abbreviated as “PVA”) film and a coated film coated with PVA or an ethylene-vinyl alcohol copolymer (hereinafter abbreviated as “EVOH”) are best known. It has been. PVA and EVOH have excellent oxygen gas barrier properties in a dry environment. On the other hand, these materials are (1) the humidity dependence of the barrier performance is very large, the barrier property is greatly impaired under high humidity conditions, (2) no water vapor barrier property, (3) in hot water There are problems such as easy dissolution, and (4) remarkable deterioration in gas barrier properties due to water absorption accompanying boil / retort treatment.

  Also, a vapor deposition film in which a vapor deposition film of an inorganic oxide such as aluminum oxide or silicon oxide is provided on one surface of a thermoplastic film such as a polyester film by using a physical vapor deposition method such as a vacuum vapor deposition method. Proposed. The gas barrier film having these inorganic oxide vapor-deposited thin film layers is transparent, and therefore has the contents visibility, and has the advantage that it can be used for cooking using a microwave oven. However, a film having a gas barrier coat layer made of an inorganic oxide vapor deposition layer has a hard gas barrier layer. For this reason, a crack and a pinhole generate | occur | produce in a gas barrier layer by bending, and there exists a problem that gas barrier property falls remarkably.

As a known technique that compensates for these disadvantages, an inorganic oxide vapor deposition layer is provided on a thermoplastic resin film, and a gas barrier layer is laminated on the vapor deposition layer by polymer coating to improve gas barrier properties and flexibility. A method is disclosed (for example, see Patent Documents 1 to 3).
JP 2004-35833 A JP 2002-307600 A JP-A-9-327882

  In the technique described in Patent Document 1, the barrier property under high humidity is improved by providing the gas barrier layer by crosslinking with an ester bond. In order to sufficiently advance the esterification and improve the gas barrier property of the film, it is necessary to react by heating to a high temperature. For this reason, there is a problem in productivity.

  In the technique described in Patent Document 2, a transparent coating layer containing a thermosetting epoxy resin and an organic curing agent is provided on an inorganic oxide thin film. When a hot water sterilization treatment such as a boil / retort treatment is performed, in the film having this laminated structure, the adhesion between the inorganic oxide layer and the transparent coating layer is significantly reduced. In other words, when such a film is used in a package for packaging food, the laminated film causes delamination due to hot water sterilization treatment such as boil and retort treatment. Cause problems.

  Furthermore, in the technique described in Patent Document 3, a primer layer composed of a primer agent is provided between the base film and the inorganic oxide vapor deposition layer. The film having such a laminated structure can exhibit strong adhesion between the inorganic oxide vapor deposition layer and the gas barrier layer when subjected to a hot water sterilization treatment such as a boil / retort treatment. However, there is a problem that the production cost increases due to an increase in production processes.

  The present invention has been made in view of the above problems, has no fear of environmental pollution due to halogens, is excellent in gas barrier properties such as oxygen and water vapor, and further, for hot water sterilization treatment such as boil and retort treatment Another object of the present invention is to provide a gas barrier film having resistance.

  As a result of intensive studies to solve the above problems, the present inventors have found that a gas barrier in which a vapor deposition layer composed of an inorganic compound and a gas barrier layer are sequentially laminated on at least one surface of a substrate made of a polyester film. The gas barrier layer comprises (a) an unsaturated nitrile having a proportion of 25 to 40% by weight in the copolymer and 20 to 30% by weight of (b) in the copolymer. 3 components of an unsaturated compound having a hydroxyl group and (c) one or more unsaturated compounds selected from the group consisting of unsaturated carboxylic acid ester, styrene, unsaturated carboxylic acid, unsaturated hydrocarbon and vinyl ester By forming a gas barrier film composed of a main agent composed of a copolymer as a monomer and a curing agent composed of a compound having an isocyanate group, the present invention Form was.

  According to the present invention, a gas barrier film having not only excellent oxygen barrier properties and water vapor barrier properties but also resistance to hot water sterilization treatment such as boil / retort treatment can be obtained. The gas barrier film of the present invention does not contain halogen such as chlorine. Furthermore, the gas barrier film of the present invention does not require heat treatment at a high temperature when forming the gas barrier layer. As a result, it is possible to provide a gas barrier film having the characteristics that it can be produced at low cost and has excellent production suitability because it does not go through a complicated production process. That is, according to the present invention, it is possible to provide a gas barrier film having a wide range of uses that are useful as a food packaging film that requires gas barrier properties and undergoes a boil-retort treatment process.

The present invention is described in detail below.
The gas barrier film of the present invention is a gas barrier film in which a vapor deposition layer composed of an inorganic compound and a gas barrier layer are sequentially laminated on at least one surface of a base material made of a polyester film, and the gas barrier layer includes: (A) an unsaturated nitrile having a proportion of 25 to 40% by weight in the copolymer, (b) an unsaturated compound having a hydroxyl group having a proportion of 20 to 30% by weight in the copolymer, and (c) It is composed of a copolymer having three components as monomers with one or more unsaturated compounds selected from the group consisting of unsaturated carboxylic acid esters, styrene, unsaturated carboxylic acids, unsaturated hydrocarbons and vinyl esters. And a curing agent composed of a compound having an isocyanate group.

  As described in the background art, a vapor deposition layer made of an inorganic compound has gas barrier properties but has defects such as pinholes and cracks. For this reason, the gas barrier performance is often incomplete. In this invention, a gas barrier layer is provided on the vapor deposition layer comprised with an inorganic compound. This gas barrier layer not only supplements the incomplete gas barrier property of the vapor deposition layer, but also functions as the gas barrier property inherent in the resin constituting the gas barrier layer. As a result, the gas barrier property is remarkably improved.

  Many resins having gas barrier properties contain polar groups in order to increase the cohesive strength of the polymer. For this reason, water absorption is often observed, making it difficult to develop resistance to hot water sterilization treatment. In the present invention, a gas barrier layer is formed using a resin composition having a specific composition for the purpose of imparting resistance to hot water sterilization treatment. This solves the problem of water absorption.

  That is, by synthesizing a resin used for forming the gas barrier layer from a plurality of monomers that express a specific function, gas barrier properties and resistance to hot water sterilization treatment can be expressed. Specifically, in the present invention, the above object can be achieved by copolymerizing a monomer for developing gas barrier properties and a monomer that adheres firmly to the inorganic oxide deposition layer and has resistance to hot water. it can.

[Base material]
In the gas barrier film of the present invention, the substrate is a polyester film. Examples of the polyester that can be used include homo- or polypolyalkylene arylates such as polyalkylene terephthalate (polyethylene terephthalate, polybutylene terephthalate, etc.), polyalkylene naphthalate (polyethylene-2,6-naphthalate, etc.), and liquid crystalline polyester. .

  The base film may be an unstretched film, but is usually stretched (uniaxial or biaxial). As the stretched film, a biaxially stretched film is usually used in many cases. As the stretching method, for example, a conventional stretching method such as roll stretching, roll stretching, belt stretching, tenter stretching, tube stretching, or a combination of these can be applied.

  Although there is no restriction | limiting in particular in the thickness of a base material, It is practical that it is about 1-100 micrometers, Preferably it is 5-50 micrometers, More preferably, it is about 10-30 micrometers.

[Deposition layer]
In the present invention, the vapor deposition layer is composed of an inorganic compound. Examples of the inorganic compound that can be used include a metal oxide layer and a metal nitride layer. Examples of the metal oxide include aluminum oxide, magnesium oxide, titanium oxide, tin oxide, indium oxide alloy, silicon oxide, silicon oxynitride, and mixed oxides thereof. Examples of the metal nitride include aluminum nitride, titanium nitride, and silicon nitride. Can be illustrated. Among these, aluminum oxide, silicon oxide, and silicon oxynitride are preferable as the inorganic compound from the viewpoint of processing cost of vapor deposition film, gas barrier performance, and the like.

  The vapor deposition of the inorganic compound is not particularly limited, and may be performed by a known method such as vapor deposition or sputtering.

[Gas barrier layer]
In the present invention, the gas barrier layer comprises (a) an unsaturated nitrile, (b) an unsaturated compound having a hydroxyl group, (c) an unsaturated carboxylic acid ester, styrene, an unsaturated carboxylic acid, an unsaturated hydrocarbon, and a vinyl ester. It is comprised with the main ingredient comprised by the copolymer which makes a monomer the three components with one or more unsaturated compounds selected from the group which consists of, and the hardening | curing agent comprised by the compound which has an isocyanate group. .

  Factors that determine the gas barrier properties of the thin film layer formed of the resin include cohesive energy density, free volume, crystallinity, orientation, and the like. These factors are often attributed to side chain functional groups in the polymer structure. That is, polymer chains containing functional groups capable of intermolecular interaction such as hydrogen bonding or electrostatic interaction in the structure tend to strongly aggregate using the interaction force as a driving force. As a result, the cohesive energy density and orientation are increased, the free volume is decreased, and the gas barrier property is improved. On the other hand, when the polymer structure contains a sterically bulky functional group, it is considered that the gas barrier property is lowered because the aggregation of the polymer is prevented and the free volume is increased. Furthermore, it can be considered that as the number of intermolecular interactions formed increases, the aggregation force increases and the driving force for reducing the free volume space increases, and as a result, the aggregation density of the polymer increases.

(Main ingredient: component (a))
As the unsaturated nitrile which is the component (a) of the main agent, acrylonitrile is preferable. Acrylonitrile has a nitrile group in its molecular structure, and has a strong ability to form hydrogen bonds because the nitrile group is a highly polarized functional group. That is, a gas barrier property is imparted to a coating film formed of a copolymer containing acrylonitrile as a constituent component due to a large contribution of the nitrile group of acrylonitrile. The gas barrier property expressed by the acrylonitrile content varies.

  The blending amount of the unsaturated nitrile is preferably 25 to 40% by weight in the copolymer, and more preferably 25 to 30% by weight. When the blending amount of the component (a) is less than 25% by weight, a sufficient number of hydrogen bonds are not formed in the coating film, and the gas barrier property is not sufficiently exhibited. On the other hand, when the blending amount of component (a) is more than 40% by weight, the solubility of the copolymer resin in the organic solvent is lowered, which not only prevents an increase in molecular weight during polymerization but also makes it difficult to form a paint. . Furthermore, it becomes impractical because the film-forming property of the coating film is lowered.

(Main agent: (component b))
As described above, it is preferable to increase the content of the component (a) in the copolymer from the viewpoint of improving the gas barrier property. However, polyacrylonitrile has a high glass transition temperature of about 300 ° C., and a high temperature is required to form a film. In order to solve this problem, means for copolymerizing the component (a) and the unsaturated compound is effective. Furthermore, in order to make it closely adhere to the inorganic oxide vapor deposition layer as in the present invention, and to form a crosslinked structure with the curing agent for the purpose of expressing the coating film strength and resistance to hot water treatment, the main resin is used. It is preferable to contain a hydroxyl group in the structure. That is, the component (b) of the main agent is an unsaturated compound having a hydroxyl group.

  Examples of the component (b) to be copolymerized with the component (a) include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxy Examples thereof include monomers of unsaturated compounds such as butyl methacrylate, 2-hydroxyvinyl ether, polyethylene glycol methacrylate, polypropylene glycol monoacrylate, and polypropylene glycol monomethacrylate. These unsaturated compounds having a hydroxyl group can be selected singly or in combination of two or more. Of these unsaturated compounds having a hydroxyl group, 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate is preferable because good polymerization stability is obtained and reactivity with an isocyanate group is good. Ethyl methacrylate is particularly preferred.

  In the copolymer, the film forming property and gas barrier property of the gas barrier layer vary depending on the content of the component (b). (B) 20-30 weight% in a copolymer is preferable, and, as for the compounding quantity of a component, 20-25% is more preferable. When the blending amount of the component (b) is less than 20% by weight, the plasticization of the copolymer resin is not sufficiently promoted and the film forming property is not sufficiently exhibited. Moreover, since there are few hydroxyl groups which contribute to hydrogen bond formation and reaction with a hardening | curing agent in copolymer resin, gas barrier property is not expressed. In addition, there is a problem that the coating strength is insufficient due to insufficient cross-linking structure. On the other hand, when the blending amount of the component (b) is more than 30% by weight, the glass transition point (temperature) of the copolymer resin is lowered, so that the film forming property is improved. However, since the number of hydroxyl groups in the copolymer resin increases, it is necessary to increase the blending amount of the curing agent, and the content of the component (a) in the gas barrier layer is also relatively decreased, so that the expression of gas barrier properties is insufficient. Become.

(Main ingredient (c) component)
In the present invention, the component (c) constituting the main agent is one or more unsaturated compounds in the group consisting of unsaturated carboxylic acid ester, styrene, unsaturated carboxylic acid, unsaturated hydrocarbon and vinyl ester.

  Examples of unsaturated carboxylic acid esters that can be used include methyl methacrylate, methyl acrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, Examples include isobutyl methacrylate, t-butyl acrylate, t-butyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate.

  Examples of the unsaturated carboxylic acid that can be used include acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid, and fumaric acid.

  Examples of other monomers that can be used include styrene, α-methylstyrene, butadiene, ethylene, and vinyl acetate.

  Among these (c) components, unsaturated carboxylic acid esters are preferred. Of unsaturated carboxylic acid esters, methyl methacrylate and methyl acrylate are particularly preferable, and methyl methacrylate is more preferable.

  The amount of component (c) is preferably 25 to 60% by weight in the copolymer, more preferably 30 to 55% by weight, and particularly preferably 40 to 50% by weight. When the blending amount of the component (c) is less than 25% by weight, the film forming property of the coating film is not sufficiently improved, and it becomes difficult to finish the coating film surface smoothly and transparently. . On the other hand, when the amount of the component (c) is more than 60% by weight, the relative amount of the component (a) and the component (b) in the copolymer resin decreases, and the gas barrier property is not sufficiently developed. Problems such as insufficient coating strength and hot water treatment resistance due to insufficient structure occur.

(Manufacture of copolymer)
Said each component (a), (b), (c) is mix | blended and it is made to copolymerize using a well-known technique, and a copolymer is manufactured. The copolymer is dissolved in, for example, a propyl acetate-propylene glycol monomethyl ether-n-propyl alcohol mixed solution and mixed with a curing agent described later.

(Other additives)
A silane coupling agent may be added to the copolymer resin (main agent) coating liquid. The silane coupling agent has an organic functional group and a hydrolyzable functional group in the molecule, and has an effect of improving the adhesion between the inorganic substance and the organic substance. Therefore, when a silane coupling agent is added, the adhesion between the inorganic oxide vapor deposition layer and the gas barrier layer can be made strong enough to withstand the hot water sterilization treatment. Examples of silane coupling agents that can be used include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and the like. These silane coupling agents may be used alone or in combination of two or more.

  The addition amount of the silane coupling agent is preferably about 0.1 to 2 parts by weight with respect to 100 parts by weight of the sum of the main agent and the curing agent used for forming the gas barrier layer. In the case of an addition amount of 0.1 parts by weight or less, the effect of the silane coupling agent is thin and sufficient adhesion cannot be obtained. On the other hand, when more than 2 parts by weight is added, the silane coupling agent functions like a plasticizer in the gas barrier layer, so that the gas barrier property of the coating film is lowered.

  Further, the copolymer resin (main agent) coating liquid according to the present invention includes a heat stabilizer, an antioxidant, a reinforcing agent, a pigment, a deterioration preventing agent, a weathering agent, a flame retardant, and a plasticizer, as long as the characteristics are not impaired. , Mold release agents, lubricants and the like may be added.

  Examples of heat stabilizers, antioxidants and deterioration inhibitors that can be used include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and mixtures thereof.

  Examples of reinforcing agents that can be used include clay, talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, and oxidation. Examples include zinc, zeolite, hydrotalcite, metal fiber, metal whisker, ceramic whisker, potassium titanate whisker, boron nitride, graphite, glass fiber, and carbon fiber.

  An inorganic layered compound may be mixed in the copolymer resin (main agent) coating liquid according to the present invention. Preferable examples of the inorganic layered compound include montmorillonite, beidellite, saponite, hectorite, saconite, vermiculite, fluoric mica, muscovite, paragonite, phlogopite, leoprite, margarite, clintonite, anandite, etc. Swellable fluoromica or montmorillonite is particularly preferred. These inorganic layered compounds may be naturally occurring, artificially synthesized or modified, or those treated with an organic material such as an onium salt.

[Curing agent]
In this invention, a hardening | curing agent is used in order to bridge | crosslink with the copolymer resin which is a main ingredient. When the copolymer resin used as the main agent is applied alone, gas barrier properties are exhibited, but physical properties such as coating film strength and hot water treatment resistance cannot be obtained. Therefore, a compound having an isocyanate group that reacts with a hydroxyl group that the copolymer resin as the main agent has as a side chain is used as a curing agent. Since a crosslinked structure is generated by the addition of the crosslinking agent, a gas barrier layer having physical properties such as gas barrier properties, coating film strength, and hot water treatment resistance is formed. Examples of the compound having an isocyanate group include aromatic diisocyanates, araliphatic diisocyanates, alicyclic diisocyanates, and aliphatic diisocyanates.

  Examples of aromatic diisocyanates that can be used include m- or p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate (NDI), 4,4'-, 2,4'- or 2, Examples include 2'-diphenylmethane diisocyanate (MDI), 2,4- or 2,6-tolylene diisocyanate (TDI), 4,4'-diphenyl ether diisocyanate, and the like.

  Examples of the araliphatic diisocyanate that can be used include 1,3- or 1,4-xylylene diisocyanate (XDI), 1,3- or 1,4-tetramethylxylylene diisocyanate (TMXDI), and the like.

  Examples of the alicyclic diisocyanate that can be used include 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate; IPDI), 4,4 ′. -, 2,4'- or 2,2'-dicyclohexylmethane diisocyanate (hydrogenated MDI), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3- or 1,4-bis (Isocyanate methyl) cyclohexane (hydrogenated XDI) and the like can be exemplified.

  Examples of aliphatic diisocyanates that can be used include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-, 2,3- or 1,3- Examples include butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate.

  Furthermore, you may use the partial condensate of the isocyanate compound illustrated above, the compound etc. which have a hydroxyl group, 1 type of various derivatives, or these 2 or more types. For example, a wide range of diols from various low molecular weight diols to oligomers, and partial condensates with trifunctional or higher functional polyols as required.

  Considering the gas barrier property of the gas barrier layer formed by the cross-linking reaction product of the main agent and the curing agent composed of a copolymer, among these compounds having an isocyanate group, 1,3- or 1,4-xylylene diene Isocyanate (XDI) and its partial condensates are preferred. The three-dimensional structure of the crosslinked product greatly affects the gas barrier property. In order to develop gas barrier properties, it preferably has a xylylene diisocyanate skeleton. These compounds have a xylylene diisocyanate skeleton.

  The compounding amount of the curing agent is determined by the number of hydroxyl groups contained in the main copolymer resin (generally represented by OH number) and the number of isocyanate groups contained in the curing agent resin (generally represented by NCO ratio). It is a usual method to calculate so as to be equivalent. The present invention is no exception, but the effect of the invention is not lost even if the amount of the curing agent is increased or decreased by about 15% by weight of the main copolymer resin. When the blending amount of the curing agent is increased, a coating film excellent in coating film strength and water-resistant adhesion to the substrate film is formed.

[Manufacture of coating layer]
A predetermined amount of the copolymer resin (main agent) solution and a curing agent are blended and dissolved in a solvent to obtain a coating solution for the gas barrier layer. Solvents that can be used include toluene, xylene, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, dimethylformamide, dimethylacetamide, methanol, ethanol, water and the like.

  In the present invention, the blending ratio of the main agent and the curing agent constituting the gas barrier layer is not particularly limited, but if the amount of the curing agent is too small, the crosslinking reaction occurring between the main agent and the coating agent becomes insufficient. Not only does the curing fail, but the coating strength does not sufficiently develop, and the resistance to hot water treatment and the adhesion to the substrate are insufficient. Moreover, when there are too many compounding quantities of a hardening | curing agent, it not only becomes a cause which produces blocking, but it may produce inconvenience in post-processing etc. because an excess isocyanate compound transfers to another layer.

  There is no restriction | limiting in particular as a method of manufacturing the gas barrier layer concerning this invention, It can manufacture by the method according to a base film. For example, printing methods such as offset printing method, gravure printing method, silk screen printing method, roll coating method, dip coating method, bar coating method, die coating method, knife edge coating method, gravure coating method, kiss coating method, spin coating method The coating liquid may be coated using a method such as a combination of these.

  The thickness of the gas barrier layer provided on the vapor deposition layer is preferably 0.1 to 3 μm, more preferably 0.2 to 2 μm. When the thickness of the gas barrier layer is 0.1 μm or more, the gas barrier property can be sufficiently improved, the workability during coating can be improved, and a gas barrier layer free from defects such as film breakage and repellency can be formed. On the other hand, when the thickness of the gas barrier layer is 3 μm or less, the solvent is sufficiently dried even when the drying conditions at the time of coating are low temperature and for a short time, so that the film does not deform such as curling, and the manufacturing cost is reduced. It is preferable because it does not cause problems such as soaring.

  In the gas barrier film of the present invention, a resin layer may be provided on the gas barrier layer. The resin layer is, for example, polyethylene, linear polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid, ester copolymer, ethylene-acrylic acid copolymer, ethylene- It is formed of a plastic material such as an acrylic ester polymer and a metal cross-linked product thereof. The thickness is appropriately determined according to the purpose, but is generally in the range of 15 to 200 μm.

  As a method for forming the resin layer, a dry laminate method in which a film-like material made of the above plastic material is bonded using a two-component reaction curable adhesive, a non-solvent laminate method in which a non-solvent adhesive is bonded, Any of the extrusion laminating methods and the like in which a plastic material is heated and melted, extruded into a curtain shape, and bonded can be formed by a known laminating method.

  In the present invention, when a gas barrier layer is formed and laminated on the vapor deposition layer by coating, it is preferably dried at a temperature of 70 ° C or higher, more preferably 90 ° C or higher, although it depends on the solvent used in the coating solution. . When the drying temperature is lower than 70 ° C., the coating film is not sufficiently dried, and it becomes difficult to obtain a film having sufficient gas barrier properties. Moreover, an aging process can also be performed on the wound intermediate product for the purpose of sufficiently proceeding the crosslinking reaction between the main agent and the curing agent. The crosslinking reaction further proceeds by the aging treatment, and sufficient coating strength, gas barrier properties, resistance to hot water treatment, and the like are exhibited.

  The gas barrier film of the present invention can be used in various fields that require gas barrier properties. It is particularly suitable for use as a packaging material for retort.

  EXAMPLES Examples will be given below to describe the present invention in detail, but the present invention is not limited to the examples. In the examples, “parts” means “parts by weight” unless otherwise specified.

[Characteristic evaluation method]
The characteristics of the gas barrier film of the present invention were evaluated using the following evaluation methods.

(1) Haze The haze of the sealable film prepared in the examples and comparative examples was measured according to the method of JIS K 7105 (1981 version) using a direct reading type haze meter (HGM-20P manufactured by Suga Test Instruments). did.

(2) Oxygen permeability (O2TR)
Oxygen permeability is measured at a temperature of 23 ° C. and a humidity of 0% RH using an oxygen permeability measuring device (model name, Oxytran (registered trademark) (OXTRAN 2/20)) manufactured by MOCON, USA. The measurement was made based on the B method (isobaric method) described in JIS K7126 (2000 edition). The measurement was performed twice, and the average value of the two measured values was used as the value of oxygen permeability in each of the examples and comparative examples. The results of two test pieces for each of the examples and comparative examples were used as oxygen permeability values.

(3) Water vapor transmission rate (MVTR)
Water vapor transmission rate is measured using a water vapor transmission rate measuring device (model name: Permatran (registered trademark) W3 / 31) manufactured by MOCON, USA under conditions of a temperature of 40 ° C. and a humidity of 90% RH. Then, it was measured based on the method B (infrared sensor method) described in JIS K7129 (2000 version). Moreover, the measurement was performed twice and the average value of the two measured values was used as the value of the water vapor transmission rate in each example and comparative example. The results of two test pieces for each example and comparative example were taken as the value of water vapor transmission rate.

(4) Retort resistance evaluation Two laminated films (15 cm square) prepared in Examples and Comparative Examples were prepared. Two laminated films were overlapped so that the surface of the sealant film faced, and the ends of the three sides were heat sealed using a heat sealer. Next, 100 g of tap water was added as the contents, and the end of the remaining one side was heat-sealed to produce a 15 cm square package. One package was prepared for each example and comparative example. Next, the package was retorted (120 ° C., 30 minutes) using an autoclave SR-240 manufactured by Tommy Seiko Co., Ltd. After the treatment, the package was broken and the tap water was drained. After drying overnight at room temperature, the oxygen transmission rate and the water vapor transmission rate were measured in accordance with the above-mentioned methods to obtain the barrier property value after the retort treatment.

[Production of copolymer]
Copolymers used in the following Examples and Comparative Examples are blended in the proportions (% by weight) shown in Table 1 for each monomer of acrylonitrile (AN), 2-hydroxyethyl methacrylate (2-HEMA) and methyl methacrylate (MMA). And obtained by copolymerization by a known technique. The obtained copolymer resin was dissolved in a mixed solvent of propyl acetate, propylene glycol monomethyl ether and n-propyl alcohol to obtain copolymer resins a to h having a solid content concentration of 30% by weight. In addition, Table 1 shows the mixing ratio of the monomers of each copolymer resin and the appearance of the obtained paint.

Example 1
(Base material)
As a base material provided with a vapor deposition layer, Barrierox (registered trademark) 1011HG manufactured by Toray Film Processing Co., Ltd., in which an aluminum oxide layer was provided on one surface of a biaxially stretched polyethylene terephthalate film by vapor deposition, was used.

(Coating solution)
Copolymer resin a 10.0 parts, Dainippon Ink Chemical Co., Ltd. isocyanate curing agent Dick Dry X-75 2.5 parts, methyl ethyl ketone 28.1 parts are stirred for 30 minutes and a gas barrier layer having a solid content concentration of 12% by weight Coating solution 1 for use was prepared.

(Manufacture of gas barrier layer)
On the aluminum oxide layer of the base material, the coating liquid 1 was applied using a wire bar, dried at 120 ° C. for 30 seconds, and a gas barrier layer was provided so that the coating amount after drying was 0.5 g / m ² . . Thus, the gas barrier film 1 was produced.

(Manufacture of resin layer)
Toyo Morton Co., Ltd. dry laminate adhesive AD-503 20 parts, Toyo Morton Co., Ltd. curing agent CAT-10 1 part, and ethyl acetate 20 parts were weighed and stirred for 30 minutes to a solid content concentration of 19% by weight. An adhesive solution for dry lamination was prepared.

  This adhesive solution was applied to the gas barrier layer surface of the obtained gas barrier film 1 with a wire bar and dried at 80 ° C. for 45 seconds to form a 3.5 μm adhesive layer.

  Next, unstretched polypropylene film ZK93K manufactured by Toray Film Processing Co., Ltd. as a sealant film was laminated on the adhesive layer so that the corona-treated surface faced the adhesive layer, and was bonded using a hand roller. This laminated film was aged in an oven heated to 40 ° C. for 2 days to obtain a laminated film 1.

(Example 2)
Copolymer resin b 10.0 parts, Dai Nippon Ink Chemical Co., Ltd. isocyanate curing agent Dick Dry X-75 2.5 parts, methyl ethyl ketone 22.3 parts are stirred for 30 minutes and a gas barrier layer having a solid content concentration of 14% by weight A coating solution 2 was prepared. A gas barrier film 2 and a laminated film 2 were obtained in the same manner as in Example 1 except that this coating liquid 2 was used to form a gas barrier layer.

(Example 3)
Copolymer Resin c 10.0 parts, Dainippon Ink & Chemicals, Inc. isocyanate curing agent Dick Dry X-75 2.5 parts, methyl ethyl ketone 22.3 parts are stirred for 30 minutes and a gas barrier layer having a solid content concentration of 14% by weight A coating solution 3 was prepared. A gas barrier film 3 and a laminated film 3 were obtained in the same manner as in Example 1 except that this coating liquid 3 was used to form a gas barrier layer.

Example 4
Copolymer resin d 10.0 parts, Dai Nippon Ink Chemical Co., Ltd. isocyanate curing agent Dick Dry X-75 2.5 parts, methyl ethyl ketone 28.1 parts are stirred for 30 minutes and a gas barrier layer having a solid content concentration of 12% by weight A coating solution 4 was prepared. A gas barrier film 4 and a laminated film 4 were obtained in the same manner as in Example 1 except that this coating liquid 4 was used to form a gas barrier layer.

(Example 5)
Copolymer resin e 10.0 parts, Dainippon Ink & Chemicals, Inc. isocyanate curing agent Dick Dry X-75 2.5 parts, methyl ethyl ketone 28.1 parts are stirred for 30 minutes and a gas barrier layer having a solid content concentration of 12% by weight A coating solution 5 was prepared. A gas barrier film 5 and a laminated film 5 were obtained in the same manner as in Example 1 except that this coating liquid 5 was used to form a gas barrier layer.

(Example 6)
Copolymer resin f 10.0 parts, Dainippon Ink & Chemicals Co., Ltd. isocyanate curing agent Dick Dry X-75 2.5 parts, methyl ethyl ketone 28.1 parts are stirred for 30 minutes and a gas barrier layer having a solid content concentration of 12% by weight A coating solution 6 was prepared. A gas barrier film 6 and a laminated film 6 were obtained in the same manner as in Example 1 except that a gas barrier layer was formed using this coating solution 6.

(Example 7)
Copolymer resin a 10.0 parts, Dainippon Ink and Chemicals Co., Ltd. isocyanate curing agent Dick Dry X-75 2.1 parts (the curing agent content is reduced by 15% compared to Example 1), methyl ethyl ketone 26. 0 parts was stirred for 30 minutes to prepare a coating solution 7 for a gas barrier layer having a solid content concentration of 12% by weight. A gas barrier film 7 and a laminated film 7 were obtained in the same manner as in Example 1 except that this coating liquid 7 was used to form a gas barrier layer.

(Example 8)
Copolymer resin a 10.0 parts, Dainippon Ink & Chemicals, Inc. isocyanate curing agent Dick Dry X-75 2.88 parts (the curing agent content is increased by 15% compared to Example 1), methyl ethyl ketone 30. 12 parts were stirred for 30 minutes to prepare a coating solution 8 for a gas barrier layer having a solid content concentration of 12% by weight. A gas barrier film 8 and a laminated film 8 were obtained in the same manner as in Example 1 except that this coating liquid 8 was used to form a gas barrier layer.

(Comparative Example 1)
Without providing a gas barrier coat layer on the deposited layer of Barrier Rocks (registered trademark) 1011HG manufactured by Toray Film Processing Co., Ltd. (this is referred to as a gas barrier film 9), an overcoat layer is provided in the same manner as in Example 1, A laminated film 9 was obtained.

(Comparative Example 2)
Copolymer Resin g 10.0 parts, Dai Nippon Ink Chemical Co., Ltd. isocyanate curing agent Dick Dry X-75 2.5 parts, methyl ethyl ketone 25.5 parts stirred for 30 minutes, gas barrier layer with a solid content concentration of 12% by weight A coating solution 9 was prepared. A gas barrier film 10 and a laminated film 10 were obtained in the same manner as in Example 1 except that a gas barrier layer was formed using this coating solution 9.

(Comparative Example 3)
Copolymer Resin h 10.0 parts, Dainippon Ink & Chemicals Co., Ltd. isocyanate curing agent Dick Dry X-75 2.5 parts, methyl ethyl ketone 25.5 parts are stirred for 30 minutes and a gas barrier layer having a solid content concentration of 12% by weight A coating solution 10 was prepared. A gas barrier film 11 and a laminated film 11 were obtained in the same manner as in Example 1 except that a gas barrier layer was formed using this coating solution 10.

(Comparative Example 4)
Copolymer Resin i 10.0 parts, Dainippon Ink & Chemicals Co., Ltd. isocyanate curing agent Dick Dry X-75 2.5 parts, methyl ethyl ketone 25.5 parts are stirred for 30 minutes and a gas barrier layer having a solid content concentration of 12% by weight A coating solution 11 was prepared. A gas barrier film 12 and a laminated film 12 were obtained in the same manner as in Example 1 except that a gas barrier layer was formed using this coating solution 11.

(Comparative Example 5)
Copolymer resin j 10.0 parts, Dai Nippon Ink Chemical Co., Ltd. isocyanate curing agent Dick Dry X-75 2.5 parts, methyl ethyl ketone 25.5 parts stirred for 30 minutes, gas barrier layer with a solid content concentration of 12% by weight A coating solution 12 was prepared. A gas barrier film 13 and a laminated film 13 were obtained in the same manner as in Example 1 except that a gas barrier layer was formed using this coating solution 12.

(Comparative Example 6)
Copolymer resin k 10.0 parts, Dainippon Ink & Chemicals Co., Ltd. isocyanate curing agent Dick Dry X-75 2.5 parts, methyl ethyl ketone 25.5 parts stirred for 30 minutes, gas barrier layer with a solid content concentration of 12% by weight A coating solution 13 was prepared. A gas barrier film 14 and a laminated film 14 were obtained in the same manner as in Example 1 except that a gas barrier layer was formed using this coating solution 13.

Using the gas barrier films and laminated films of Examples 1 to 8 and Comparative Examples 1 to 6 obtained above, the characteristics were evaluated by the above evaluation method. The results are shown in Table 2. Table 2 also shows the configurations of the gas barrier films and laminated films of Examples 1 to 8 and Comparative Examples 1 to 6.

(Comparison between Examples 1-8 and Comparative Example 1)
Compared with the film of Comparative Example 1 in which no gas barrier layer is formed on the vapor deposition layer, the gas barrier films 1 to 8 and the laminated films 1 to 8 of Examples 1 to 8 are both untreated and after retorting. It can be seen that both the gas barrier property (O2TR) and the water vapor transmission rate (MVTR) are improved. In particular, it can be seen that the laminated films 1 to 8 provided with a gas barrier layer having a specific resin composition maintain very excellent oxygen barrier properties even after retorting.

(Comparison between Examples 1-8 and Comparative Examples 2, 3)
In the resin composition forming the gas barrier layer, the copolymer resin g used in Comparative Example 2 does not contain an acrylonitrile component that greatly contributes to the gas barrier properties of the coating film. The copolymer resin h used in Comparative Example 3 contains only 20% by weight of an acrylonitrile component as an unsaturated nitrile that greatly contributes to the gas barrier properties of the coating film. Therefore, the gas barrier films 10 and 11 of Comparative Examples 2 and 3 show little or no improvement in gas barrier properties compared to the gas barrier films 1 to 8 of Examples 1 to 8. That is, in order to express a high gas barrier property, it turns out that it is necessary to contain unsaturated nitrile (acrylonitrile) by a specific mixing | blending as a copolymerization component.

(Comparison between Examples 1-8 and Comparative Example 4)
In the resin composition for forming the gas barrier layer, the copolymer resin i used in Comparative Example 4 contains 50% by weight of an acrylonitrile component as an unsaturated nitrile. Therefore, the solubility of the copolymer polymer was greatly reduced, and the paint was suspended. The gas barrier layer formed of the copolymer resin i having such properties has high haze and lacks practicality as a packaging material. That is, if the blending amount of unsaturated nitrile (acrylonitrile) is greatly increased as a copolymerization component in order to exhibit high gas barrier properties, a problem arises from the viewpoint of transparency. For this reason, it turns out that it is necessary to contain unsaturated nitrile (acrylonitrile monomer) by specific mixing | blending.

(Comparison between Example 5 and Comparative Example 5)
In the resin composition for forming the gas barrier layer, the copolymer resin e used in Example 5 and the copolymer resin j used in Comparative Example 5 have a blending ratio of an acrylonitrile component which is an unsaturated nitrile in the composition of the copolymer resin, Although equal, copolymer resin j has a large compounding ratio of 2-hydroxyethyl methacrylate, which is an unsaturated compound having a hydroxyl group, and accordingly, it is necessary to increase the compounding ratio of isocyanate which is a partner of the crosslinking reaction. That is, when the isocyanate content is small, the hydroxyl group in the copolymer resin remains unreacted (cross-linked), so the hydrophilicity increases, and the water-resistant adhesion between the inorganic compound layer decreases. That is, it is for preventing that retort resistance falls. However, in doing so, the proportion of unsaturated nitriles (acrylonitrile) in the resin forming the gas barrier layer is reduced, leading to a reduction in gas barrier properties. Further, since the number of cross-linking points is increased, the coating film is hardened, and the degree of deterioration of the gas barrier property accompanying the retort treatment is increased. In other words, an unsaturated compound having a hydroxyl group (2-hydroxyethyl methacrylate monomer), which is one of the copolymerization components, is a specific compound in order to exhibit high gas barrier properties and reduce deterioration of gas barrier properties associated with retort processing. It turns out that it is necessary to contain.

(Comparison between Example 5 and Comparative Example 6)
In the resin composition for forming the gas barrier layer, the copolymer resin e used in Example 5 and the copolymer resin k used in Comparative Example 6 have a compounding ratio of an acrylonitrile component which is an unsaturated nitrile in the composition of the copolymer resin, Although equal, copolymer resin k has a small compounding ratio of 2-hydroxyethyl methacrylate, which is an unsaturated compound having a hydroxyl group, and accordingly, there are few crosslinking points due to reaction with isocyanate which is the partner of the crosslinking reaction. For this reason, not only does the gas barrier property not sufficiently develop due to the small number of hydroxyl groups contributing to hydrogen bond formation and reaction with the curing agent in the copolymer resin, but not a sufficient cross-linked structure and insufficient coating strength. It turns out that the deterioration degree of the barrier property accompanying a retort process also becomes large. In other words, an unsaturated compound having a hydroxyl group (2-hydroxyethyl methacrylate monomer), which is one of the copolymerization components, is a specific compound in order to exhibit high gas barrier properties and reduce deterioration of gas barrier properties associated with retort processing. It turns out that it is necessary to contain.

(Comparison of Examples 1, 7, and 8)
The gas barrier films 1, 7, and 8 produced by the methods described in Examples 1, 7, and 8 all use the copolymer resin a as the copolymer resin that forms the gas barrier layer. Comparing the characteristics, the transparency of the film, the initial gas barrier property, and the gas barrier property after the retort treatment all show excellent performance. Compared with the coating agent 1 for the gas barrier layer used for the production of the gas barrier film 1, the coating agent 7 reduces the blending amount of the curing agent by 15%, and the coating agent 8 increases the blending amount of the curing agent by 15%. ing. It turns out that the compounding quantity of a hardening | curing agent has not exerted any bad influence regarding transparency, gas barrier property, and retort resistance. It is considered that the degree of cross-linking between the copolymer resin a and the curing agent varies with the change in the amount of the curing agent, but it is understood that no significant deterioration in characteristics occurs in the above increase / decrease range.

  As is clear from the results of the above Examples and Comparative Examples, in the gas barrier film of the present invention, a gas barrier layer was formed using a copolymer polymer polymerized at a specific blending ratio. As a result, a gas barrier film having high transparency, high barrier properties against oxygen and water vapor, and excellent retort resistance could be obtained.

The gas barrier film of the present invention has not only excellent oxygen barrier properties and water vapor barrier properties, but also resistance to hot water sterilization treatment such as boil and retort treatment. ADVANTAGE OF THE INVENTION According to this invention, gas barrier property is requested | required and the gas barrier property film with a wide use use which is useful also as a film for food packaging which passes through a boil retort processing process can be provided.

Claims (8)

A gas barrier film in which a vapor deposition layer composed of an inorganic compound and a gas barrier layer are sequentially laminated on at least one surface of a substrate made of a polyester film,
The gas barrier layer comprises (a) an unsaturated nitrile having a proportion of 25 to 40% by weight in the copolymer and (b) an unsaturated compound having a hydroxyl group of 20 to 30% by weight in the copolymer. And (c) a monomer comprising three components of one or more unsaturated compounds selected from the group consisting of unsaturated carboxylic acid esters, styrene, unsaturated carboxylic acids, unsaturated hydrocarbons and vinyl esters. A gas barrier film composed of a main agent composed of a polymer and a curing agent composed of a compound having an isocyanate group.   2. The gas barrier film according to claim 1, wherein the component (a) of the main agent forming the gas barrier resin layer is acrylonitrile.   The gas barrier film according to claim 1 or 2, wherein the component (b) of the main agent forming the gas barrier resin layer is 2-hydroxyethyl methacrylate.   The gas barrier film according to any one of claims 1 to 3, wherein the component (c) of the main agent forming the gas barrier resin layer is methyl methacrylate.   The gas barrier film according to any one of claims 1 to 4, wherein component (c) of the main agent forming the gas barrier resin layer is contained in an amount of 25 to 60% by weight in the copolymer.   The gas barrier film according to claim 1, wherein the inorganic compound forming the vapor deposition layer is a metal oxide.   The gas barrier film according to claim 6, wherein the metal oxide is at least one selected from the group consisting of aluminum oxide, silicon oxide, and silicon oxynitride. A packaging material for retort using the gas barrier film according to any one of claims 1 to 7.