JP2005225940A - Gas barrier film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare a gas barrier film not depending on humidity, especially a gas barrier transparent film suitable for wrapping. <P>SOLUTION: This gas barrier film has a gas barrier layer produced from a polycarboxylic acid, and a polyamine and/or a polyol, wherein the degree of the cross linkage of the polycarboxylic acid is ≥40 %. The polycarboxylic acid is preferably polyacrylic acid, polymethacrylic acid, or the like. The film includes a film comprising a substrate film layer and a gas barrier layer laminated to the substrate film layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gas barrier film. More specifically, the present invention relates to a gas barrier film having a gas barrier layer formed from a polycarboxylic acid and a polyamine and / or polyol and having a gas barrier property that is not dependent on humidity.

  In order to store food and chemicals for a long period of time, it is effective to block invasion from the outside air of oxygen that promotes spoilage and deterioration by packaging, and for this reason, packaging with a packaging material with excellent gas barrier properties is performed. It is coming. In recent years, there has been a tendency for film packaging materials having excellent gas barrier properties used for this purpose to be particularly required to have transparency that can confirm the state of the contents.

  On the other hand, as a transparent gas barrier film, a film in which a deposited layer of silicon oxide or aluminum oxide is formed on a polymer resin film is known (see Patent Documents 1 and 2). However, these deposited layers are thin films with a thickness of several tens of nanometers, so factors such as the occurrence of pinholes due to the flatness of the surface of the substrate film, the occurrence of cracks during processing, and poor adhesion Therefore, the problem that the gas barrier property is extremely lowered is likely to occur.

  Further, in order to improve these drawbacks, studies have been made to provide an organic flexible coating layer on or under the inorganic thin film layer. For example, in Patent Document 3, an oxazoline group-containing water-soluble polymer layer is formed on the surface of a plastic film. It is proposed to provide a metal and / or metal oxide layer thereon, and Patent Document 4 proposes to provide a coating layer of polyvinyl alcohol having a saponification degree of 90% or more on the surface of the deposited film. Has been. However, it is difficult to sufficiently suppress the above-described drawbacks, and there is a problem that the gas barrier property is likely to deteriorate during the processing.

  On the other hand, as described in Non-Patent Document 1 and Non-Patent Document 2, it is known that the gas barrier property of the polymer itself is arranged by the Permacol value π or the free volume theory. Polyvinylidene chloride, polyacrylonitrile, polyvinyl alcohol, polyethylene / vinyl alcohol copolymer and the like are polymers having a particularly large permacol value and high gas barrier properties, and thus are suitably used for packaging materials.

  However, since polyvinylidene chloride and polyacrylonitrile contain a chlorine atom and a -CN group, adverse effects on the environment have recently become a problem during incineration.

  Polyvinyl alcohol and polyethylene / vinyl alcohol copolymer have extremely excellent gas barrier properties under a low humidity condition of about 50% RH, but the gas barrier properties are significantly reduced under a high humidity condition of about 80% RH. There is a drawback of doing.

In order to improve the gas barrier properties under such high humidity conditions, it is essential to devise measures to suppress the movement of the polymer and reduce the free volume existing between the polymer chains. There have been many attempts to apply a crosslinked polymer material that has been crosslinked. For example, Patent Document 5 discusses a material in which polycarboxylic acid and polyvinyl alcohol or saccharide are crosslinked, and Patent Document 6 studies a material in which saccharide and formyl compound are crosslinked. In these studies, gas barrier properties under high humidity have been improved by combining general-purpose compounds. However, there is no description / examination on what chemical structure the gas barrier properties are enhanced by. It is not what has been done.
JP 49-41469 A Japanese Patent Laid-Open No. 62-179935 Japanese Patent Laid-Open No. 11-179836 JP 2000-185375 A JP-A-8-41218 JP 2003-238734 A M. Salame, “Prediction of gas barrier properties of high polymers”, 1986, Polymer Engineering and Science, Vol. 26, No. 22, p. 1543-1546 JYPark, DRPoul, “Correlation and prediction of gas permeability in glassy polymer membrane materials via a modified free volume based group contribution method”, 1997, Journal of Membrane Science, 125, p. 23-39

  An object of the present invention is to solve the above-mentioned problems of conventional gas barrier films and to provide a film having excellent gas barrier properties that is not dependent on humidity.

  The film of the present invention showing excellent gas barrier properties without humidity dependency has a gas barrier layer formed from a polycarboxylic acid and a polyamine and / or polyol, and the degree of crosslinking of the polycarboxylic acid is 40% or more. Is the most important feature.

  The film of the present invention is excellent in gas barrier properties and transparency by using a material obtained by crosslinking a polymer having excellent transparency, and can be applied to packaging applications such as foods, pharmaceuticals, and electronic members. Further, by combining with a layer of metal, metal oxide, diamond-like carbon, etc., it can be used for packaging of electronic devices, plastic substrates used for liquid crystal displays, organic EL displays, electronic paper, solar cells, and the like. In addition, because it uses a polymer with a relatively high degree of crosslinking, it has excellent stability over time, and does not impair barrier properties even in high-humidity atmospheres, boil / retort treatment, etc. Is preferably used as a material for packaging. For the same reason, it is extremely excellent in processing durability and can be printed, coated with a protective layer, or laminated with other films in post-processing such as dry lamination, melt extrusion lamination, thermocompression lamination, etc. It can be applied to a wide range of uses by further processing such as combining these. In particular, when a non-halogen material is used, it has excellent environmental suitability that does not generate toxic gases and harmful substances even when incinerated.

The present invention will be described in detail below.
The gas barrier film of the present invention has a gas barrier layer formed from polycarboxylic acid and polyamine and / or polyol, and may be a laminated film or a single layer film. This gas barrier layer is a layer having a very dense structure containing a polycarboxylic acid, a polyamine and / or a polyol, and a reaction product of these polymers. By providing this layer, the gas barrier property of the film, particularly the oxygen barrier property, is provided. This is a significant improvement. Further, the gas barrier property is not dependent on humidity, and has a great feature in that it has excellent gas barrier property similar to that under low humidity conditions even under high humidity conditions.

<Polycarboxylic acid>
The polycarboxylic acid used for the gas barrier layer in the film of the present invention is a polymer having a carboxyl group at the side chain or terminal.

The polycarboxylic acid used in the present invention is not particularly limited as long as it has a carboxyl group at the side chain or terminal, and a polymer mainly composed of a repeating structure represented by the following formulas 1 and 2 is used. It can be used suitably. Here, in Formula 1, X represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Y represents any of a carboxyl group, a carboxylic acid ester, an amide group, and a carboxylate. In Formula 2, Z represents any of a carboxyl group, a carboxylic acid ester, an amide group, and a carboxylate. A, b, and c represent natural numbers of 0-4.
(Formula 1)

(Formula 2)

  Specific examples include polyacrylic acid, polymethacrylic acid, acrylic acid-methacrylic acid copolymer, polymaleic acid, carboxyl group-containing aliphatic polyamide, carboxyl group-containing aromatic polyamide, and the like. In view of the gas barrier property improving effect of these polymers, polyacrylic acid and a polypeptide having a carboxyl group are preferable, and polyacrylic acid, polyglutamic acid, and polyaspartic acid are more preferable. Since these polymers have a high proportion of polar functional groups (carboxyl groups, amide bonds) in the molecule and a strong packing force between molecules, they are considered to be suitable for gas barriers.

  Moreover, derivatives of these polymers are also applicable, and examples thereof include copolymers with other monomers, polycarboxylic acids modified with carboxyl groups such as amidated polycarboxylic acids and esterified polycarboxylic acids. As the other copolymerizable monomer, a monomer having a carboxyl group in the side chain is preferable, and in the case of polyacrylic acid, an acrylic monomer such as methacrylic acid can be applied. Or γ amino acids can be used. In addition, modification of the carboxyl group by esterification promotes the cross-linking reaction between the amino group of the polyamine and the hydroxyl group of the polyol, and when a process of forming a film by mixing the polyamine and the polycarboxylic acid in an aqueous solution is applied. For example, the gelation of the polymer due to the formation of a so-called nylon salt can be prevented, which is a useful embodiment. Specific examples of the ester include methyl ester, ethyl ester, 2-hydroxyethyl ester, and phenyl ester. Moreover, the compound which protected the carboxyl group in the molecule | numerator like polysuccinimide can also be used.

By changing the degree of neutralization of the polycarboxylic acid of the present invention, the micro structure and gas permeability of the gas barrier layer can be controlled. Here, the degree of neutralization refers to the conversion rate (0 to 100%) into a salt by neutralization of a carboxyl group. The salt refers to a compound obtained by substituting one or more dissociable hydrogen ions contained in an acid with a cation such as a metal ion or an ammonium ion. Na ⁺ salt, Li ⁺ salt, Mg ²⁺ salt, Zn ^{2 +} Salt, Al ³⁺ salt, Ca ²⁺ salt, NH ⁴⁺ salt and the like.

  The preferable degree of neutralization taking gas permeability into consideration varies greatly depending on the monomer type and ion type, and it is sufficient to select the optimum conversion rate in each case, but generally 3 to 50% is preferable, and 5 -40% is more preferable, and 5-20% is a more preferable neutralization degree. When the degree of neutralization is less than 3% or more than 50%, it is not preferable because it is difficult to sufficiently improve the gas barrier properties of the film under high humidity conditions. When the degree of neutralization is within the above range, the reason why the gas barrier property is high is that the salt concentration in the polymer is increased, the cohesive force between the polymer segments is increased due to the increase of electrostatic interaction, and the free volume is reduced. It is thought to be. The degree of neutralization of the polycarboxylic acid can be controlled by adding sodium hydroxide, lithium hydroxide, magnesium hydroxide, ammonium hydroxide or the like to the polycarboxylic acid aqueous solution.

  The weight average molecular weight of the polycarboxylic acid in the present invention is preferably 5,000 to 300,000. If the molecular weight of the polycarboxylic acid is too low, the gas barrier layer tends to be fragile, and those having a high molecular weight are not preferred from the viewpoint of synthesis.

<Polyamine>
The polyamine used for the gas barrier layer in the film of the present invention is a polymer having a primary or secondary amino group in the main chain, side chain or terminal. Specific examples of polyamines include aliphatic polyamines such as polyallylamine, polyvinylamine, branched polyethyleneimine, linear polyethyleneimine, poly (trimethyleneimine), amino groups in the side chain such as polylysine and polyarginine. Examples thereof include polyamides.

  In addition, derivatives of these polymers can be used, and examples thereof include copolymers with other monomers and acylated polyamines such as formylated polyamines and acetylated polyamines. Such acylation of an amino group is a preferred embodiment because it promotes a crosslinking reaction with a carboxyl group of a polycarboxylic acid. In addition, acylation of amino groups is useful to prevent gelation of polymers due to the formation of so-called nylon salts when applying the process of forming a film by mixing polyamine and polycarboxylic acid in an aqueous solution. It is a mode.

  The weight average molecular weight of the polyamine in the present invention is usually 5000 to 300,000, preferably 10,000 to 150,000. If the molecular weight of the polyamine is too low, the gas barrier layer tends to be fragile, and those having a high molecular weight are not preferred from the viewpoint of synthesis.

<Polyol>
The polyol used for the gas barrier layer in the film of the present invention is a polymer having a hydroxyl group at the terminal or side chain. Specific examples of polyols include ethylene glycol, glycerin, pentaerythritol, dipentaerythritol, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, saccharides, etc. Polyvinyl alcohol and saccharides having a high ratio in the molecule of hydroxyl groups that are functional groups are more preferable. From the same viewpoint, the degree of saponification of polyvinyl alcohol is preferably as high as possible, more preferably 95% or more, and still more preferably 98% or more. Moreover, a preferable average degree of polymerization is 200-2000. When it is smaller than this range, the coating film strength becomes weak, and when it is larger, the coating liquid viscosity becomes high, which is not preferable.

  Sugars include monosaccharides such as glucose, galactose, fructose, mannose, fucose, rhamnose, cururonic acid, glucosamine, sorbitol, arabinose, ribose, deoxyribose, maltose, lactose, sucrose, trehalose, maltotriose, meletose, stachyose, etc. Polysaccharides such as oligosaccharides, starches, celluloses, pullulan, dextrin, chitins and chitosans can be exemplified.

  Here, when polyol and polyamine are compared, polyol is superior in that it can be crosslinked at a relatively low reaction temperature, while polyamine requires a slightly higher temperature for crosslinking, but its gas barrier property is inferior to that of polyol. Furthermore, it is excellent in terms of good adhesion when post-processing such as printing on the surface, and can be used properly according to each application.

<Degree of crosslinking>
In the gas barrier layer of the present invention, the degree of crosslinking of the polycarboxylic acid is 40% or more, preferably 45% or more, more preferably 50% or more. The degree of crosslinking of the polycarboxylic acid refers to the polycarboxylic acid before the crosslinking reaction. The reaction rate of the total carboxyl group contained and the amino group in the polyamine or the hydroxyl group in the polyol is indicated by the following formula.
(Crosslinking degree of polycarboxylic acid) = [(mol number of carboxyl group in polycarboxylic acid reacted with amino group in polyamine) + (mol number of carboxyl group in polycarboxylic acid reacted with hydroxyl group in polyol) ] / (Number of moles of carboxyl groups in polycarboxylic acid before crosslinking reaction) × 100
Although the upper limit is not particularly limited, it is preferably 80% or less in consideration of cost performance.

  The degree of crosslinking of the gas barrier layer of the present invention can be controlled by various methods such as heat, ultraviolet rays, and radiation. However, when crosslinking is performed by a heating process using a hot air oven or the like, the degree of crosslinking depends on the heating temperature and the heating time. Can be controlled. The heating temperature and heating time for achieving the desired degree of cross-linking are not greatly limited depending on the compound, catalyst, etc. used, but in order to make the degree of cross-linking 40% or higher, it is usually 0 at 100 to 220 ° C. In order to increase the degree of crosslinking to 50% or more, it is usually preferable to perform the heat treatment at 140 to 230 ° C. for about 1 to 90 minutes.

  The mixture of polycarboxylic acid and polyamine and / or polyol used for the gas barrier layer of the present invention shows excellent gas barrier properties under low humidity conditions (about 50% RH) even if the degree of crosslinking is low, but carboxyl group and amino group It is considered that the movement of the polymer chain is suppressed by the amide bond generated by the reaction of (1) and the ester bond generated by the reaction of the carboxyl group and the hydroxyl group, and a gas barrier property independent of humidity is developed. In the present invention, in particular, when the degree of crosslinking of the polycarboxylic acid and the humidity dependency of the gas barrier properties are repeatedly studied, when the degree of crosslinking is 40% or more, the gas barrier under high humidity conditions (about 80% RH). It has been found that the properties are significantly reduced.

<Mixing ratio of each composition>
Mixing of the carboxylic acid and the polyamine and / or polyol used in the gas barrier layer of the present invention includes: A: mole number of carboxyl groups in the polycarboxylic acid component, B: mole number of amino groups in the polyamine component, and C: in the polyol. When the number of moles of the hydroxyl group is used, it is usually preferable to perform mixing so that (A: (B + C)) = 100: 30 to 30: 100, but 100: 50 to 50: 100 is more preferable, and 100: It is more preferable to mix so that it may become 80-80: 100. If (A: (B + C)) is in the above range, the degree of crosslinking of the carboxyl group is increased, and the gas barrier property is improved further particularly under high humidity conditions.

<Lamination>
The film of the present invention may be a single-layer film consisting essentially only of a gas barrier layer, but may take the form of a laminated film in which a gas barrier layer is laminated on a substrate film (hereinafter referred to as a substrate layer). The material for forming the base material layer is not particularly limited, but representative examples include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate, nylon 6, and nylon. 12. Polyamide such as copolymer nylon and MXD nylon, polyvinyl chloride, ethylene vinyl acetate copolymer, polystyrene, polycarbonate, polysulfone, polyphenylene oxide, polyphenylene sulfide, aromatic polyamide, polyimide, polyamideimide, cellulose, cellulose acetate, etc. And these copolymers. Of course, polyvinylidene chloride, polyacrylonitrile, polyvinyl alcohol, ethylene-vinyl alcohol copolymer and the like already known as packaging materials can also be used to further improve the barrier property. Of these, polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, and polyamides such as nylon 6, nylon 12, and MXD nylon are preferable in terms of transparency and gas barrier properties.

  The base material layer may be a composite film composed of two or more layers of an inner layer and a surface layer. As the composite film, for example, a composite film that is substantially free of particles in the inner layer portion and provided with a layer containing particles in the surface layer portion, contains coarse particles in the inner layer portion, and fine particles in the surface layer portion. And a composite film in which the inner layer portion is a layer containing fine bubbles and the surface layer portion substantially does not contain bubbles. Further, the composite film may be a polymer of different types or the same type in the inner layer portion and the surface layer portion. This composite film may be obtained by bonding the films by various methods.

  The thickness of the base material layer is not particularly limited, and is appropriately selected depending on the application in which the film of the present invention is used. From the viewpoint of the mechanical strength and handling properties of the film, it is preferably 0.00. It is 1-500 micrometers, More preferably, it is 1-300 micrometers, More preferably, it is 10-200 micrometers.

  Furthermore, the base material layer is preferably transparent, and the light transmittance is preferably 60% or more, and more preferably 80% or more. The polymer film of the base material layer preferably has a smooth surface. For example, the preferable value of the center line average roughness of the surface is 0.5 μm or less, more preferably 0.2 μm or less, and still more preferably 0.1 μm or less.

  As a form of the laminated film of the present invention, a film composed of at least a base material layer, a gas barrier layer, a layer containing a metal and / or a metal oxide can be mentioned. Specifically, when the base material layer is A layer, the gas area layer is B layer, and the layer containing metal and / or metal oxide is C layer, the layer constitution is B // A, A // B // A, B // A // B layer structure consisting of a base material layer and a gas barrier layer, C // B // A, B // C // A, C // B // A // B // C, B // C // A // C // B layer structure further including a C layer (a layer containing a metal and / or metal oxide), B // C // B // A, C / Examples include a layer configuration in which gas barrier layers and C layers are alternately laminated on a base material layer, such as / B // C // B // A.

  Examples of the material used for the layer containing metal and / or metal oxide include aluminum, aluminum oxide, silicon oxide, and magnesium oxide, but are not particularly limited, and have a gas barrier property such as oxygen and water vapor. If it is.

  The optimum thickness of the metal and / or metal oxide layer varies depending on the type and configuration of the metal (oxide) used, but is preferably in the range of 10 to 500 nm. When the thickness is less than 10 nm, the film barrier may increase and the gas barrier property may deteriorate. On the other hand, when the thickness exceeds 500 nm, the thin film cannot maintain flexibility, and the thin film may be cracked due to bending, pulling, or the like, which may not be a preferable mode.

  In the present invention, there are various methods for forming a metal and / or metal oxide layer. For example, the metal and / or metal oxide layer can be formed by a vacuum deposition method, but is not particularly limited. A sputtering method, an ion plating method, etc. The usual thin film forming method can also be used. However, in consideration of productivity, the vacuum evaporation method is preferable, and it is more preferable to perform vacuum evaporation using the electron beam heating method as the heating means of the vacuum evaporation apparatus. In addition, in order to improve the adhesion with other layers and the denseness of the thin film, a plasma assist method or an ion beam assist method can be used. In addition, an inorganic film can be provided by a wet method such as a sol-gel method.

  The film of the present invention can be improved in function by laminating layers having various functions. Specifically, the surface hardness and the water resistance are improved by a layer containing a curable compound such as an acrylic compound, metal alkoxide, and epoxy compound, and a further gas barrier is provided by a gas barrier layer such as vinylidene chloride and diamond-like carbon (DLC). The improvement of property etc. can be illustrated.

  In particular, a laminated film structure including a DLC layer is a preferable aspect in designing an extremely high level gas barrier film. DLC has an amorphous structure in which a diamond structure (sp3), a graphite structure (sp2), a hydrocarbon polymer structure, etc. are mixed, and is an extremely excellent material in hardness, friction, wear, surface smoothness, and gas barrier properties. . DLC can be formed by various methods such as a PVD method, a CVD method, an ion plating method, and a sputtering method.

<Other ingredients>
The gas barrier layer in the film of the present invention is mainly composed of a polycarboxylic acid and a polyamine and / or polyol, but may contain components other than these. The concentration of these polymers in the gas barrier layer is preferably 40 to 100% by weight, more preferably 60 to 100% by weight, and particularly preferably 80 to 100% by weight based on the total weight of the layer constituent components. When the concentration of these polymers is less than 40% by weight, it is difficult to obtain an effect of improving gas barrier properties.

  Examples of components other than the gas barrier component that can be contained in the gas barrier layer in the film of the present invention include, for example, plasticizers, antioxidants, thermal stabilizers, lubricants, ultraviolet absorbers, weathering agents, colorants, surfactants. And usual additives such as leveling agents and antistatic aids. In addition, a binder polymer component can be added for the purpose of improving the flatness, mechanical properties, etc. of the gas barrier layer. The binder polymer is not particularly limited as long as it has good compatibility with the polymer to be used, and examples thereof include polyolefin, polyester, polyurea, polycarbonate, polyurethane, and polyacryl.

  In addition, inorganic or organic particles can be added as long as the gas barrier property and transparency are not significantly impaired. Typical examples include talc, kaolin, calcium carbonate, titanium oxide, silicon oxide, calcium fluoride, lithium fluoride, alumina, barium sulfate, zirconia, mica, calcium phosphate, and crosslinked polystyrene particles. Furthermore, other polymers can be contained.

  By adding or laminating an adhesive component to the gas barrier layer in the present invention, the adhesion between the gas barrier layer and the base material layer, or the adhesion between the gas barrier layer and the metal and / or metal oxide layer is made extremely excellent. Can do. Such an adhesive component is not particularly limited, and melamine compounds, epoxy compounds, urea compounds, and the like can be used.

  As the melamine compound, a compound obtained by reacting methylol melamine derivative obtained by condensing melamine and formaldehyde with ether such as methyl alcohol, ethyl alcohol, isopropyl alcohol or the like as a lower alcohol, and a mixture thereof are preferable. Examples of the methylol melamine derivative include monomethylol melamine, dimethylol melamine, trimethylol melamine, tetramethylol melamine, pentamethylol melamine, hexamethylol melamine and the like.

  Specific examples of the epoxy compound include polyepoxy compounds, diepoxy compounds, and monoepoxy compounds. Examples of the polyepoxy compound include sorbitol, polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris (2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, trimethylolpropane. And polyglycidyl ether. Examples of the diepoxy compound include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and polypropylene glycol diglycidyl. Examples include ether and polytetramethylene glycol diglycidyl ether. Examples of the monoepoxy compound include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, and phenyl glycidyl ether.

  Examples of urea compounds include dimethylol urea, dimethylol ethylene urea, dimethylol propylene urea, tetramethylol acetylene urea, 4-methoxy-5-dimethylpropylene urea dimethylol, and the like.

  The blending amount of the various adhesive components is preferably about 0.1 to 10% by weight with respect to all components of the gas barrier layer.

  Although the thickness of the gas barrier layer in the film of this invention is not specifically limited, 0.05-500 micrometers is preferable from the point of gas barrier property, and 0.1-100 micrometers is more preferable. This is because when the thickness of the gas barrier layer is less than 0.05 μm, it is difficult to obtain a desired gas barrier property, and when it exceeds 500 μm, the gas barrier layer may be easily broken.

In addition, the gas barrier layer in the film of the present invention exhibits a very excellent gas barrier property having no humidity dependency by allowing a polycarboxylic acid having a good gas barrier property to interact with and react with a polyamine and / or polyol. In particular, it has excellent oxygen barrier properties, and the oxygen permeability of the film under conditions of humidity 50% RH and 80% RH is usually 20 cc · μm / m ² · day · atm or less, preferably 10 cc · μm / m ² · day. · atm or less, more preferably ^{5cc · μm / m 2 · day} · atm , more preferably not more than ^{2cc · μm / m 2 · day} · atm. In order to reduce the oxygen permeability under conditions of humidity 50% RH and 80% RH to 20 cc or less, the degree of crosslinking between the polycarboxylic acid and the polyamine and / or polyol constituting the gas barrier layer is set to at least 40% or more, and 2 cc In order to achieve the following, the degree of crosslinking is preferably at least 50% or more.

<Production method>
Next, the method for producing a gas barrier film having a gas barrier layer according to the present invention will be described by taking as an example the case of a laminated film comprising a base film layer and a gas barrier layer.

  The gas barrier film of the present invention can be produced, for example, by applying a coating solution in which polycarboxylic acid and polyamine are dissolved on a substrate film layer, followed by drying and heat treatment. Before applying the coating liquid, if necessary, the coated surface of the base film layer may be subjected to corona discharge treatment in air or other various atmospheres. Moreover, you may give the anchor process using anchor processing agents, such as a urethane resin and an epoxy resin. The heat treatment is performed in order to completely remove the solvent and to crosslink the polycarboxylic acid and the polyamine and / or polyol, but usually 100 to 240 ° C./several seconds to several hours, preferably 130 to 230 ° C./several seconds to several tens of minutes, More preferably, conditions of about 150 to 230 ° C. and several seconds to several tens of minutes are applied. When the temperature and the heat treatment time are smaller than the above ranges, the degree of crosslinking becomes insufficient.

  The method of applying the coating liquid is not particularly limited, but for the reason that thin film coating can be performed at high speed, a coating liquid in which polycarboxylic acid and polyamine are dissolved in water or various solvents, gravure coating, A method of applying by reverse coating, spray coating, kiss coating, die coating, or metering bar coating is preferred. When a biaxially stretched film of polyester such as polyethylene terephthalate or polyolefin such as polypropylene is used as the base film, it can also be applied in-line, and the longitudinal direction during the film production process by the normal sequential biaxial stretching method can be used. Applying after stretching is preferable because drying, heat treatment and transverse stretching are performed in the tenter.

Next, although this invention is demonstrated based on an Example, this invention is not necessarily limited to this.
In the following examples and comparative examples, the method for measuring the characteristics and the method for evaluating the effects are as follows.

<Evaluation method>
(1) Oxygen permeability According to JIS K-7126 (1999), using an oxygen permeability measuring device (Modern Control, OX-TRAN100), 20 ° C., 50% RH, and 20 ° C., 80%. The oxygen transmission rate of the laminated film was measured by RH.
(2) Crosslinking degree of polycarboxylic acid The carboxyl group, carboxylate, ester group, and amide group after crosslinking treatment were quantified by solid NMR method, and the crosslinking degree was calculated by the following formula.
(Crosslinking degree of polycarboxylic acid) = [(amount of ester group) + (amount of amide group)] / [(amount of carboxyl group) + (amount of carboxylate salt) + (amount of ester group) + (amount of amide group)] × 100
NMR was measured under the following conditions.
Equipment: CMX-300 (Chemagnetics)
Measurement nucleus: ¹³ C
Measurement nuclear frequency: 75.497791MHz
Spectrum width: 30.030kHz
Pulse width: 1.5μsec
Pulse mode: Gated decoupling mode Pulse repetition time: 200s
Temperature: Room temperature (about 22 ° C)
Sample rotation speed: 5.0 kHz
(Examples 1-12)
Polyethylene terephthalate (hereinafter abbreviated as PET) containing 0.015% by weight of colloidal silica having an average particle size of 0.4 μm and 0.005% by weight of colloidal silica having an average particle size of 1.5 μm (Intrinsic viscosity 0.63 dl / g) The chips were sufficiently vacuum dried at 180 ° C., then supplied to a melt extruder, melted at 285 ° C., extruded from a T die die, and cast on a casting drum at 30 ° C. to produce an unstretched sheet. This unstretched sheet was stretched 3.0 times in the longitudinal direction with a roll group heated to 90 ° C. to obtain a uniaxially stretched film. The film was guided to a 90 ° C. preheating zone while holding both ends of the film with clips, and then stretched 3.3 times in the width direction in a 100 ° C. heating zone. Further, a heat treatment for 12 seconds was performed in a heat treatment zone at 220 ° C. while performing a relaxation treatment of 3% continuously to complete the crystal orientation, thereby obtaining a biaxially stretched PET film having a thickness of 25 μm.

  Further, an aqueous solution containing 10% by weight of solid content, 85% by weight of purified water, and 5% by weight of isopropyl alcohol containing the polycarboxylic acid, polyamine and polyol shown in Table 1 was prepared, and a coating liquid for forming a gas barrier layer was prepared. did. For the polycarboxylic acid solution, NaOH was added so that the degree of neutralization was 5%. The biaxially stretched PET film was used as a base film, and the coating solution was applied to the surface by a Mayer bar method, dried at 140 ° C. for 2 minutes, and then heat-treated under the heat treatment conditions shown in Table 1 to obtain a thickness of 1 A coating film (gas barrier layer) of .5 μm was formed to produce a laminated film having a gas barrier layer. The obtained laminated film had a total thickness of 26.5 μm and a gas barrier layer thickness of 1.5 μm, and was excellent in transparency. As shown in Table 1, these gas barrier films exhibited excellent oxygen barrier properties without humidity dependency.

(Examples 13 to 15)
A metal oxide vapor deposition film was formed on a biaxially stretched PET film layer having a thickness of 25 μm obtained in the same manner as in Examples 1-12. That is, in Example 13, a silica layer having a thickness of about 40 nm was formed by vacuum deposition using SiO as a deposition source. In the case of Example 14, vapor deposition was performed by a reactive vapor deposition method in which oxygen gas was introduced using aluminum as a vapor deposition source to form an alumina layer having a thickness of 50 nm. In Example 15, CO and H ₂ were used as a carbon source, and a film was formed by a plasma CVD method to form a DLC layer having a thickness of 20 nm.

  Next, in the same manner as in Example 1, the coating liquid shown in Table 1 was used, and the gas barrier layer formed from polycarboxylic acid, polyamine, and polyol was applied to the surface of the PET base film on which the metal oxide or DLC was laminated. The provided laminated film was produced. The obtained laminated film had a total thickness of 26.5 μm, a gas barrier layer thickness of 1.5 μm, a vapor deposition layer of 20 to 50 nm, and was excellent in transparency. As shown in Table 1, these films exhibited excellent oxygen barrier properties without humidity dependency.

(Explanation of Table 1) 1) The coating solution was prepared by mixing a 10% by weight aqueous solution of polycarboxylic acid and a 10% by weight aqueous solution of polyamine and / or polyol. In the case of a combination of polycarboxylic acid and polyamine, a coating solution was prepared so as to contain 5.0 equivalents of ammonia of the amount of carboxyl groups of the polycarboxylic acid in order to suppress gelation due to salt formation. 2) The mixing ratio was such that the number of moles of carboxyl groups contained in the polycarboxylic acid and the number of moles of amino groups contained in the polyamine or the number of moles of hydroxyl groups contained in the polyol were as shown in Table 1. 3) Oxygen permeability unit (cc / m ² · day · atm)
(Compound used)
Polyacrylic acid (Wako Pure Chemical Industries, Ltd. acrylic acid 25% aqueous solution Mn150000)
Polyaspartic acid (polysuccinimide obtained by heating L aspartic acid in a nitric acid catalyst at 230 ° C. for 8 hours, hydrolyzed with 1N sodium hydroxide aqueous solution at 30 ° C. for 3 hours, and neutralized with hydrochloric acid was used. Mw: 60000)
Polyallylamine (Nittobo Polyallylamine PAA-10C)
Polyvinylamine (Polmylated polyvinylamine obtained by radical polymerization of N-vinylformamide was hydrolyzed with 1N aqueous sodium hydroxide solution at 100 ° C. for 6 hours.)
Polyethyleneimine (polyoxazoline obtained by polymerizing 2-oxazoline in the presence of methyl psulfonate at 80 ° C. for 5 hours and hydrolyzed with 1N sodium hydroxide at 100 ° C. for 3 hours was used.)
Polyvinyl alcohol (Polyvinyl alcohol NL-05 saponification degree 98% or more by Nippon Synthetic Chemical)
Soluble starch (soluble starch manufactured by Wako Pure Chemical Industries, Ltd.)
(Comparative Examples 1-5)
A laminated film was produced in the same manner as in Examples 1 to 12 except that the composition and heat treatment conditions shown in Table 2 were applied. The obtained laminated film had a total thickness of 26.5 μm and a gas barrier layer thickness of 1.5 μm. As shown in Table 2, these gas barrier films had poor oxygen barrier properties under high humidity conditions.

(Comparative Examples 6-8)
In the same manner as in Examples 13-15, a film in which a silica layer, an alumina layer, and a DLC layer were laminated on a biaxially stretched polyester film was prepared, and the oxygen permeability was evaluated (see Table 2).

  Since the film of the present invention is excellent in gas barrier properties and transparency, it is used in packaging applications such as foods, pharmaceuticals, and electronic materials, packaging applications such as electronic devices, liquid crystal displays, organic EL displays, electronic paper, solar cells, and the like. It can be used for plastic substrates. In particular, it is excellent in stability over time and does not impair barrier properties even in a high humidity atmosphere, boil / retort treatment, etc., and thus is preferably used as a material for packaging foods and chemicals that require long-term storage. In addition, it is extremely excellent in processing durability, and can be printed, coated with a protective layer, laminated with other films in post-processing such as dry lamination, melt extrusion lamination, thermocompression lamination, or a combination of these. It can be applied to a wide range of uses by further processing.

Claims (10)

A gas barrier film having a gas barrier layer formed from a polycarboxylic acid and a polyamine and / or polyol, and having a polycarboxylic acid crosslinking degree of 40% or more. The gas barrier film according to claim 1, wherein the polycarboxylic acid mainly comprises a repeating structure represented by the following formula.

(X represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and Y represents a carboxyl group, a carboxylic acid ester, an amide group, or a carboxylate salt.) The gas barrier film according to claim 1, wherein the polycarboxylic acid mainly comprises a repeating structure represented by the following formula.

(Z represents any of a carboxyl group, a carboxylic acid ester, an amide group, and a carboxylate, and a, b, and c represent natural numbers of 0 to 4.) The gas barrier film according to any one of claims 1 to 3, wherein an oxygen permeability measured under a humidity of 80% RH is 20 cc / m ² · day · atm or less. The gas barrier film according to any one of claims 1 to 4, wherein the polycarboxylic acid is either polyacrylic acid or a carboxyl group-containing polyamino acid. The gas barrier film according to claim 5, wherein the polyamino acid is polyaspartic acid or polyglutamic acid. The gas barrier film according to any one of claims 1 to 6, wherein the polyamine contains at least one selected from polyethyleneimine, polyvinylamine, and polyallylamine. The gas barrier film according to any one of claims 1 to 7, wherein the polyol contains polyvinyl alcohol and / or saccharide. The gas barrier film according to claim 1, wherein a layer containing a metal and / or a metal oxide is provided. The gas barrier film according to any one of claims 1 to 9, wherein a layer containing diamond-like carbon is provided.