JP6351309B2 - Laminate - Google Patents

Description

  The present invention relates to a laminate that can block oxygen from entering from outside the packaging bag and further remove oxygen remaining in the packaging bag.

  Plastic films such as polyamide films are excellent in strength, transparency and moldability, and are therefore used in a wide range of applications as packaging materials. However, since these plastic films have a large gas permeability such as oxygen, when used for packaging general foods, retort processed foods, cosmetics, medical supplies, agricultural chemicals, etc., oxygen that has permeated the film during long-term storage, etc. The gas may cause alteration of the contents. Therefore, various oxygen barrier films are used for these packaging applications.

  For applications that need to be stored for a long period of time, various oxygen absorbents are used to remove trace amounts of oxygen in the packaging bag.

  As a method for imparting oxygen barrier properties to a plastic substrate, for example, Patent Document 1 discloses an oxygen barrier property in which a plastic substrate, an oxygen barrier layer, and a polymer layer containing a bivalent or higher metal compound are laminated. A method is described in which the laminate is heat treated in the presence of water.

  However, in the method of Patent Document 1, after an oxygen barrier layer is formed, pressure treatment using an autoclave is performed in water containing a metal compound, and it is difficult to carry out continuously, which increases productivity. It was inferior. In Patent Document 1, a solvent-based paint is applied on a plastic substrate and dried to form an undercoat layer, and then an aqueous paint is applied and dried to form an oxygen barrier layer. Therefore, the method of Patent Document 1 has problems in terms of economy and productivity, such as the need for explosion-proof equipment and the need for multiple coatings in order to use a solvent-based paint.

  As a technique combining an oxygen absorbent and an oxygen barrier film, for example, Patent Document 2 includes a polymer having a functional group such as a carboxyl group and a metal ion having a valence of 2 or more for neutralizing the carboxyl group. A laminate including an oxygen barrier layer and a layer containing an oxygen absorbent is disclosed. However, in Patent Document 2, in order to form an oxygen barrier layer, a step of preparing a solution containing a polymer having a functional group such as a carboxyl group, and a layer obtained by applying the solution to a substrate and drying the layer It is necessary to go through at least three steps: the step of forming the layer and the step of contacting the layer formed on the base material with a solution containing a metal ion having a valence of 2 or more, and there are many production steps, improving economy and productivity. There was room for.

JP 2004-322626 A JP 2006-334990 A

  An object of the present invention is to provide a laminate that solves the above problems, is excellent in productivity and economy, blocks oxygen that enters from outside the packaging bag, and can remove oxygen remaining in the packaging bag. There is to do.

  As a result of earnestly examining the above problems, the inventor of the present invention, in a laminate comprising a plastic substrate (I) and an oxygen barrier layer (II), a laminate comprising an oxygen absorbent contained in the plastic substrate (I), or In a laminate in which a layer comprising an oxygen absorbent is further provided on a laminate comprising a plastic substrate (I) and an oxygen barrier layer (II), the plastic substrate (I) is allowed to contain a metal compound and an oxygen barrier layer ( It has been found that by including a polycarboxylic acid in II), a laminated body capable of blocking oxygen entering from outside the packaging bag and further removing oxygen remaining in the packaging bag can be obtained. Reached.

That is, the gist of the present invention is as follows.
(1) A plastic substrate (I) including a metal-containing layer containing a metal compound and an oxygen absorbent, and an oxygen barrier layer (II) containing a polycarboxylic acid ,
The metal-containing layer is obtained by extruding a melt of a thermoplastic resin containing 0.1 to 70 mass% of a metal compound and mixed with the metal compound,
The metal-containing layer and the oxygen barrier layer are in contact,
After hydrothermal treatment at 95 ° C. for 30 minutes, the oxygen permeability in an atmosphere at 20 ° C. and a relative humidity of 65% is 0.01 to 16 ml / (m ² · day · MPa) ,
The plastic substrate (I) is stretched,
A laminate characterized by the above.
(2) A layer containing an oxygen absorbent was provided on a laminate comprising a plastic substrate (I) containing a metal-containing layer containing a metal compound and an oxygen barrier layer (II) containing a polycarboxylic acid. A laminate,
The metal-containing layer is obtained by extruding a melt of a thermoplastic resin containing 0.1 to 70 mass% of a metal compound and mixed with the metal compound,
The metal-containing layer and the oxygen barrier layer are in contact,
After hydrothermal treatment at 95 ° C. for 30 minutes, the oxygen permeability in an atmosphere at 20 ° C. and a relative humidity of 65% is 0.01 to 16 ml / (m ² · day · MPa) ,
The plastic substrate (I) is stretched,
A laminate characterized by the above.
(3) The laminate according to (1) or (2), further comprising a sealant layer.
(4) The laminate according to (3), wherein the sealant layer is disposed on the layer side containing the oxygen absorbent.
(5) The laminate according to any one of (1) to (4), wherein the plastic substrate (I) is a multilayer film, and at least one layer thereof is a metal-containing layer .
(6) A packaging bag comprising the laminate according to any one of (1) to (5).

ADVANTAGE OF THE INVENTION According to this invention, the laminated body which can interrupt | block the invasion of oxygen from the outside of a packaging bag, and can remove the oxygen which remains in a packaging bag can be provided.
Moreover, the plastic base material containing a metal compound in the present invention can be produced simply by adding the metal compound to the raw material of the plastic base material, and a conventional layer containing the metal compound is used as the base material. The process of apply | coating or processing a laminated body in hot water can be skipped. Therefore, a laminate can be obtained with a smaller number of processes than before, and therefore, industrial merit is extremely large from the viewpoint of productivity and cost.

Hereinafter, the present invention will be described in detail.
The laminate of the present invention comprises a plastic substrate (I) and an oxygen barrier layer (II), and the oxygen absorbent is contained in the plastic substrate (I), or the plastic substrate (I) and Any of the laminates comprising the gas barrier layer (II) provided with a layer containing an oxygen absorbent (hereinafter abbreviated as “oxygen absorbent containing layer”).

  Examples of the thermoplastic resin constituting the plastic substrate (I) include polyolefin resins such as polyethylene, polypropylene, and ionomer, polyamide resins such as polyamide 6, polyamide 66, polyamide 46, and polyamide 9T, polyethylene terephthalate, polyethylene isophthalate, and polyethylene naphthalate. Phthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, polyester resin such as polylactic acid, vinyl chloride, polystyrene resin, polycarbonate resin, polyarylate resin, ethylene-vinyl acetate copolymer, Examples thereof include an ethylene-vinyl alcohol copolymer or a mixture thereof. Of these thermoplastic resins, when a packaging bag is constructed, a polyamide resin is preferable because of excellent puncture strength and impact resistance, and a polyester resin is preferable because of excellent heat resistance and economy. .

  The thickness of the plastic substrate (I) can be appropriately selected according to the mechanical strength required for the obtained laminate. For reasons of mechanical strength and ease of handling, the thickness of the plastic substrate (I) is preferably 5 to 100 μm, and more preferably 10 to 30 μm. If the thickness of the plastic substrate (I) is less than 5 μm, sufficient mechanical strength cannot be obtained, and the piercing strength tends to deteriorate.

  The laminate of the present invention needs to contain a metal compound in the plastic substrate (I). The metal constituting the metal compound is not particularly limited as long as it is a metal element included in Group 1, Group 2, Group 12, Group 13 of the periodic table, and monovalent metals such as lithium, sodium, and potassium And metals having two or more valences such as magnesium, calcium, zinc, and aluminum. Among them, a metal having a high ionization tendency is preferable from the viewpoint of easy reaction with carboxylic acid, and a monovalent or divalent metal is preferable from the viewpoint of oxygen barrier properties. Specifically, lithium, sodium, potassium, magnesium, calcium, and zinc are preferable, and magnesium, calcium, and zinc are more preferable. The type of metal is not limited to one type, and may be two or more types.

  In the present invention, the metal compound is a compound containing the above metal, and examples of the compound include oxides, hydroxides, halides, inorganic salts such as carbonates, bicarbonates, phosphates, sulfates, Examples thereof include carboxylate such as acetate, formate, stearate, citrate, malate, and maleate, and organic acid salt such as sulfonate, and is preferably an oxide or carbonate. . Moreover, you may use a metal simple substance as a metal compound.

  Among the above metal compounds, preferred examples include lithium carbonate, sodium hydrogen carbonate, magnesium oxide, magnesium carbonate, magnesium hydroxide, magnesium acetate, calcium oxide, calcium carbonate, calcium hydroxide, calcium chloride, calcium phosphate, calcium sulfate, acetic acid. Calcium, zinc acetate, zinc oxide, zinc carbonate, etc. can be mentioned. From the viewpoint of oxygen barrier properties, magnesium salts such as magnesium oxide, magnesium carbonate, magnesium hydroxide, magnesium acetate, calcium carbonate, calcium acetate, zinc oxide Divalent metal compounds such as zinc acetate are preferable. From the viewpoint of the transparency of the plastic substrate (I), monovalent compounds such as lithium carbonate and sodium hydrogen carbonate, magnesium oxide, magnesium carbonate, magnesium hydroxide, etc. Magnesium salts are preferred. These may be used alone or in combination.

  The metal compound is preferably in a powder form, and the average particle diameter is not particularly limited, but is preferably 0.001 to 10.0 μm, more preferably 0.005 to 5.0 μm, and 0 The thickness is more preferably 0.01 to 2.0 μm, and particularly preferably 0.05 to 1.0 μm. Since the haze of the plastic substrate (I) can be reduced, the metal compound preferably has a smaller average particle size. However, a metal compound having an average particle size of less than 0.001 μm has a large surface area, so that it easily aggregates, and coarse aggregates are scattered in the film, which may deteriorate the mechanical properties of the substrate. On the other hand, the plastic base material (I) containing a metal compound having an average particle size exceeding 10.0 μm tends to be broken when the film is formed, and the productivity tends to decrease.

  A metal compound can improve dispersibility, weather resistance, wettability with a thermoplastic resin, heat resistance, transparency, and the like by performing surface treatment such as inorganic treatment or organic treatment. Examples of the inorganic treatment include alumina treatment, silica treatment, titania treatment, zirconia treatment, tin oxide treatment, antimony oxide treatment, and zinc oxide treatment. Examples of the organic treatment include treatment using a fatty acid compound, a polyol compound such as pentaerythritol and trimethylolpropane, an amine compound such as triethanolamine and trimethylolamine, a silicone compound such as a silicone resin and alkylchlorosilane. .

  The content of the metal compound in the plastic substrate (I) is preferably 0.1 to 70% by mass, more preferably 0.1 to 50% by mass, and 0.2 to 20% by mass. More preferably, it is most preferably 0.2 to 5% by mass. From the viewpoint of haze, it is preferably less than 5% by mass. When the content of the metal compound in the plastic substrate (I) is 0.1 to 70% by mass, the obtained laminate can obtain excellent oxygen barrier properties. However, when the content of the metal compound in the plastic substrate (I) is less than 0.1% by mass, the cross-linked structure formed by reacting with the polycarboxylic acid in the oxygen barrier layer (II) is reduced. The resulting laminate may have a reduced oxygen barrier property. On the other hand, the plastic substrate (I) whose content exceeds 70% by mass has a high frequency of breakage during stretching during film formation, and the productivity tends to decrease, and the mechanical properties may also decrease.

  The method for incorporating the metal compound into the plastic substrate (I) is not particularly limited, and it can be blended at any point in the production process. For example, a method of adding a metal compound when polymerizing a thermoplastic resin constituting the plastic substrate (I), a method of kneading a thermoplastic resin and a metal compound with an extruder, a high concentration of the metal compound Examples thereof include a method (master batch method) in which a master batch mixed by kneading is prepared, and this is added to a thermoplastic resin and diluted. In the present invention, the master batch method is preferably employed.

  The laminate of the present invention contains an oxygen absorbent in the plastic substrate (I) or a layer separate from the plastic substrate (I) or oxygen barrier layer (II) containing the oxygen absorbent. It is necessary.

  As the oxygen absorbent, either an inorganic oxygen absorbent or an organic oxygen absorbent may be used.

  Examples of the inorganic oxygen absorbent include simple substances and compounds of transition metals such as manganese, iron, cobalt, nickel, copper, titanium, cerium, and ruthenium. Of these, oxygen-deficient oxides such as reduced iron, cerium, and titanium, and cobalt carboxylates such as cobalt naphthenate, cobalt stearate, and a carboxylate having 8 to 10 carbon atoms of cobalt are preferable. These may be used alone or in combination.

  The particle diameter of the inorganic oxygen absorbent is not particularly limited, but is preferably 10 nm to 10 μm from the viewpoint of dispersibility in the resin.

  The shape of the inorganic oxygen absorbent is not particularly limited, and examples thereof include granular, spherical, plate-like, columnar, cylindrical, powdery, granular and the like. Of these, powder and granules are preferred because of their large surface area and high oxygen absorption rate.

  Examples of the organic oxygen absorbent include organic compounds containing a carbon-carbon double bond, metaxylylenediamine polyamide resins, vitamins, erythorbic acid, and sodium erythorbate. These may be used alone or in combination.

  Examples of the organic compound containing a carbon-carbon double bond include metathesis polymers of cyclic olefins such as norbornene and cyclooctene, polyene monomers such as butadiene, isoprene, 2-ethylbutadiene, 2-butylbutadiene, chloroprene, and dicyclopentadiene, A homopolymer or a copolymer of one kind of these derivatives may be mentioned. Examples of the copolymer include random copolymers of two or more kinds of polyene monomers, or polyene monomers and other monomers, and block copolymers. Other monomers to be copolymerized with the polyene monomer include α-olefins having 2 to 20 carbon atoms, vinyl compounds such as styrene, vinyl toluene and vinyl acetate, and α and β unsaturated nitrile compounds such as acrylonitrile and methacrylonitrile. And α, β unsaturated carboxylic acids such as methyl (meth) acrylate and ethyl (meth) acrylate, and derivatives thereof. Among them, the carbon-carbon double bond is substantially present only in the main chain, and even when oxidized, it is difficult to generate a low molecular weight substance. From the viewpoint of preventing odor, 1,4-polybutadiene, 1,4-polyisoprene, Polychloroprene and polyoctenylene are preferable.

  In the organic compound having a carbon-carbon double bond, the content of the carbon-carbon double bond is preferably 0.001 equivalent / g (eq / g) or more, and 0.005 eq / g or more. Is more preferably 0.01 eq / g or more. When the content of the carbon-carbon double bond is less than 0.001 eq / g, the removal of oxygen in the packaging bag may be insufficient.

  The molecular weight of the organic compound having a carbon-carbon double bond is preferably 1000 to 500,000, more preferably 10,000 to 250,000, and more preferably 20,000 to 100,000, from the viewpoints of handling properties and dispersibility. preferable.

  The metaxylylenediamine-based polyamide resin is a polyamide resin containing a metaxylylenediamine monomer as a component. As the metaxylylenediamine-based polyamide resin, poly (metaxylylene adipamide) composed of metaxylylenediamine and adipic acid is preferable. Poly (metaxylylene adipamide) may be copolymerized with other monomers. Examples of the other monomer include diamines such as hexamethylene diamine, and dicarboxylic acids such as succinic acid and sebacic acid.

  Vitamins include tocopherol and ascorbic acid.

  When an organic antioxidant is mixed with a thermoplastic resin having a polar group such as polyamide 6, from the viewpoint of compatibility or dispersibility in the resin, a metaxylylenediamine polyamide resin, a carboxyl group, or a carboxylic acid is used. An organic compound having a carbon-carbon double bond into which a carboxyl group such as an anhydride group or carboxylate group or a polar group such as a hydroxyl group is introduced is preferred. As a method for introducing a carboxyl group into an organic compound having a carbon-carbon double bond, α, β-insoluble such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid and the like can be used. The method of introduce | transducing saturated carboxylic acid or those acid anhydrides by a well-known graft reaction, and the method of making it copolymerize are mentioned. As content of unsaturated carboxylic acid or its derivative (s), it is preferable to set it as 0.01-10 mass%. By setting the content in the above range, the acid-modified polyene polymer is well dispersed in the resin and oxygen is smoothly absorbed.

  The content of the oxygen absorbent is preferably 0.1 to 70% by mass and more preferably 0.1 to 50% by mass in the plastic substrate (I) or in the oxygen absorbent containing layer. preferable.

  The oxygen absorbent preferably contains an oxidation accelerator. Examples of the oxidation accelerator include transition metal catalysts, photocatalysts, radical generators, and the like.

  Examples of transition metal catalysts include cobalt salts. The content of the transition metal catalyst is preferably 1 to 50000 ppm, more preferably 5 to 10000 ppm in terms of metal element in the plastic substrate (I) or in the oxygen absorbent-containing layer. More preferably, it is 5000 ppm. When the content of the transition metal catalyst is less than 1 ppm, the effect of the addition may be insufficient. On the other hand, when the content of the transition metal catalyst exceeds 50000 ppm, the thermal stability of the resin to be dispersed is lowered, and the generation of decomposition gas and the generation of gels and blisters may become remarkable.

  Examples of the photocatalyst particles include titanium dioxide, tungsten oxide, zinc oxide, cerium oxide, strontium titanate, and potassium niobate particles. These are usually used in the form of a powder. Among these, titanium dioxide is preferable because it has a high photocatalytic function, is recognized as a food additive, and is safe and inexpensive.

  Examples of the radical generator include imide compounds. Examples of the imide compound include N-hydroxysuccinimide, N-hydroxymaleic imide, N-hydroxyhexahydrophthalic imide, N, N′-dihydroxycyclohexanetetracarboxylic diimide, N-hydroxyphthalic imide, N-hydroxy. Examples thereof include tetrabromophthalimide and N-hydroxytetrachlorophthalimide.

  In the present invention, the oxygen absorbent-containing layer may be provided on the gas barrier layer (II) or on the plastic substrate (I). The oxygen absorbent-containing layer may be a layer composed only of an oxygen absorbent, but from the viewpoint of suppressing a decrease in mechanical properties due to oxygen absorption, it may contain a thermoplastic resin other than the oxygen absorbent. preferable. As the thermoplastic resin, a known adhesive may be used in addition to the thermoplastic resin used for the plastic substrate (I). Known adhesives include rubber adhesives, acrylic adhesives, urethane adhesives, vinyl ether adhesives, ester adhesives, silicone adhesives, and the like. Among these, polyvinyl alcohol, poly (ethylene-vinyl alcohol), polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, and polyglycolic acid are preferable. The adhesive may be any of an aqueous type, a solvent type, a hot melt type, and a reactive type.

  The oxygen absorbent-containing layer may contain a known compatibilizer depending on the type of the oxygen absorbent and the thermoplastic resin used. Known compatibilizers include those of unsaturated hydrocarbons such as ethylene, propylene, isoprene, butadiene and styrene and unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, itaconic acid and their acid anhydrides. Examples thereof include polymers and polymers composed of unsaturated esters such as (meth) acrylic acid esters, vinyl compounds such as vinyl acetate, acrylonitrile, vinyl chloride and vinylidene chloride. Among them, styrene-diene block copolymers (styrene-isoprene-block copolymers, styrene-butadiene copolymers, styrene-isoprene-styrene block copolymers, etc.), styrene polymers such as hydrogenated products thereof, An ethylene-acrylic acid ester-maleic acid copolymer and an ethylene-propylene-maleic acid copolymer are preferred.

  For the thermoplastic resin used for the plastic substrate (I) and the oxygen absorbent-containing layer, if necessary, a thermal stabilizer is used as long as the performance of the plastic substrate (I) and the oxygen absorbent-containing layer is not adversely affected. 1 type or 2 types of various additives such as antioxidants, reinforcing materials, pigments, deterioration inhibitors, weathering agents, flame retardants, plasticizers, preservatives, ultraviolet absorbers, antistatic agents, and antiblocking agents The above may be added.

  The plastic substrate (I) may be a single-layer film or a multi-layer film. When the plastic substrate (I) is a multilayer film, it is necessary that at least one layer thereof contains a metal compound. Hereinafter, a layer containing a metal compound or a single layer film in the multilayer film is referred to as “metal-containing layer (M)”, and layers other than the “metal-containing layer (M)” in the multilayer film are referred to as “resin layer ( R) ".

  When the plastic substrate (I) is a multilayer film, as a structure of the obtained laminate, the oxygen barrier layer (II) and the metal-containing layer (M) of the plastic substrate (I) are in contact with each other. (R) / (M) / (II), (M) / (R) / (M) / (II), (II) / (M) / (R) / (M) / (II), etc. Is mentioned. In these configurations, the oxygen barrier layer (II) and the metal-containing layer (M) are in contact with each other, and the polycarboxylic acid in the oxygen barrier layer (II) and the metal compound in the metal-containing layer (M) are likely to react. Therefore, oxygen barrier properties can be obtained efficiently. Among these, in consideration of equipment for manufacturing and operability, the configuration of (R) / (M) / (II) is preferable.

  Also, the oxygen barrier layer (II) and the resin layer (R) of the plastic substrate (I) are in contact with each other, (M) / (R) / (II) and (R) / (M) / (R ) / (II), (II) / (R) / (M) / (R) / (II) and the like. Among these, the structure of (M) / (R) / (II) is preferable in consideration of equipment for manufacturing and operability.

  The thickness constitution ratio of the metal-containing layer (M) and the resin layer (R) constituting the multilayer film is not particularly limited, and the total thickness (Mt) of the metal-containing layer (M) and the total of the resin layer (R). The ratio of thickness (Rt) ((Rt) / (Mt)) is preferably 1/1000 to 1000/1, and the thickness control of each layer is easy, so 1/100 to 100/1. More preferably, it is more preferably 1/10 to 10/1.

  The said additive may be added also to the thermoplastic resin which comprises the resin layer (R).

  The laminate of the present invention needs to contain a polycarboxylic acid in the oxygen barrier layer (II). The polycarboxylic acid in the oxygen barrier layer (II) can exhibit oxygen barrier properties by reacting with the metal compound in the plastic substrate (I).

  The polycarboxylic acid in the present invention is a compound or polymer having two or more carboxyl groups in the molecule, and these carboxyl groups may form an anhydride structure. Specific examples of the polycarboxylic acid include 1,2,3,4-butanetetracarboxylic acid, polyacrylic acid, polymethacrylic acid, acrylic acid-methacrylic acid copolymer, acrylic acid-maleic acid copolymer, polymaleic acid Examples thereof include olefin-maleic acid copolymers such as ethylene-maleic acid copolymers, polysaccharides having carboxyl groups in the side chains such as alginic acid, polyamides containing carboxyl groups, and polyesters. The said polycarboxylic acid may be used independently and may be used together.

  When the polycarboxylic acid is a polymer, the weight average molecular weight is preferably 1000 to 1000000, more preferably 10000 to 150,000, and further preferably 15000 to 110000. If the weight average molecular weight of the polycarboxylic acid is too low, the resulting oxygen barrier layer (II) becomes brittle. On the other hand, if the molecular weight is too high, handling properties are impaired, and in some cases, an oxygen barrier layer (II The oxygen barrier layer (II) obtained by agglomeration in the coating liquid for forming a) may have an impaired oxygen barrier property.

  In the present invention, among the above polycarboxylic acids, polyacrylic acid and olefin-maleic acid copolymer, particularly ethylene-maleic acid copolymer (hereinafter sometimes abbreviated as “EMA”) are oxygen barrier properties. From the viewpoint of, it is preferably used. EMA is obtained by polymerizing maleic anhydride and ethylene by a known method such as solution radical polymerization. The maleic acid unit in the olefin-maleic acid copolymer tends to have a maleic anhydride structure in which the adjacent carboxyl group is dehydration-cyclized in a dry state, and opens to form a maleic acid structure when wet or in an aqueous solution. Therefore, in the present invention, unless otherwise specified, maleic acid units and maleic anhydride units are collectively referred to as maleic acid units. The maleic acid unit in EMA is preferably 5 mol% or more, more preferably 20 mol% or more, further preferably 30 mol% or more, and most preferably 35 mol% or more. . Moreover, it is preferable that the weight average molecular weights of EMA are 1000-1 million, It is more preferable that it is 3000-500000, It is further more preferable that it is 7000-300000, It is especially preferable that it is 10000-200000.

  In the present invention, the oxygen barrier layer (II) preferably contains a polyalcohol. By containing the polyalcohol, the polycarboxylic acid in the oxygen barrier layer (II) reacts with the polyalcohol in addition to reacting with the metal compound in the plastic substrate (I). Can be improved. Polyalcohol is a compound having two or more hydroxyl groups in the molecule. Examples of low molecular weight compounds include sugar alcohols such as glycerin and pentaerythritol, monosaccharides such as glucose, disaccharides such as maltose, and oligosaccharides such as galactooligosaccharide. Examples of the polymer compound include polysaccharides such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and starch. The said polyalcohol may be used independently and may be used together. The saponification degree of polyvinyl alcohol or ethylene-vinyl alcohol copolymer is preferably 95 mol% or more, and more preferably 98 mol% or more. Moreover, it is preferable that average polymerization degree is 50-2000, and it is more preferable that it is 200-1000.

  In the oxygen barrier layer (II), the polycarboxylic acid and the polyalcohol are preferably contained so that the molar ratio of OH group to COOH group (OH group / COOH group) is 0.01 to 20. More preferably, the content is 0.011 to 10, more preferably 0.02 to 5, and most preferably 0.04 to 2.

  In the present invention, the oxygen barrier layer (II) preferably contains polyacrylamide, polymethacrylamide or polyamine. By containing these compounds, the polycarboxylic acid in the oxygen barrier layer (II) reacts with these compounds in addition to reacting with the metal compound in the plastic substrate (I). Can be improved.

  The polyamine has two or more amino groups selected from primary and secondary as amino groups in the molecule. Specific examples thereof include polyallylamine, polyvinylamine, branched polyethyleneimine. And polysaccharides having an amino group in the side chain such as linear polyethyleneimine, polylysine and chitosan, and polyamides having an amino group in the side chain such as polyarginine. The weight average molecular weight of the polyamine is preferably 5,000 to 150,000. If the weight average molecular weight of the polyamine is too low, the resulting oxygen barrier layer (II) becomes fragile. On the other hand, if the molecular weight is too high, handling properties are impaired, and in some cases, an oxygen barrier layer (II) described later may be used. The oxygen barrier layer (II) obtained by agglomeration in the coating liquid for formation may have a impaired oxygen barrier property.

  The mass ratio of polyamine to polycarboxylic acid (polyamine / polycarboxylic acid) in the oxygen barrier layer (II) is preferably 12.5 / 87.5 to 27.5 / 72.5. If the mass ratio of the polyamine is lower than this, the crosslinking of the carboxyl group of the polycarboxylic acid becomes insufficient. Conversely, if the mass ratio of the polyamine is higher than this, the crosslinking of the amino group of the polyamine becomes insufficient. However, the resulting laminate may be inferior in oxygen barrier properties.

  The oxygen barrier layer (II) in the present invention may contain a crosslinking agent. By containing a crosslinking agent, oxygen barrier property can be improved. The content of the crosslinking agent in the oxygen barrier layer (II) is preferably 0.1 to 30 parts by mass and more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the polycarboxylic acid. Examples of the crosslinking agent include compounds having self-crosslinking properties and compounds having a plurality of functional groups that react with carboxyl groups in the molecule. When the oxygen barrier layer (II) contains a polyalcohol, it reacts with a hydroxyl group. A compound having a plurality of functional groups in the molecule may be used. Preferable examples of the crosslinking agent include isocyanate compounds, melamine compounds, urea compounds, epoxy compounds, carbodiimide compounds, zirconium salt compounds such as zirconium ammonium carbonate, metal alkoxides, and the like. These crosslinking agents may be used alone or in combination.

  A metal alkoxide is a compound containing a metal to which an alkoxy group is bonded, and an alkyl group substituted with a functional group having reactivity with a halogen or a carboxyl group may be bonded instead of a part of the alkoxy group. . Here, the metal includes atoms such as silica, aluminum, titanium, and zirconium, the halogen includes chlorine, iodine, bromine, and the like. The functional group having reactivity with a carboxyl group is an epoxy group. , Amino group, isocyanate group, ureido group and the like, and alkyl group includes methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group and the like. Examples of such compounds include tetramethoxysilane, tetraethoxysilane, chlorotriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, Alkoxysilane compounds such as 3-aminopropyltriethoxysilane, 3-ureidopropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, alkoxytitanium compounds such as tetraisopropoxytitanium and tetraethoxytitanium, alkoxy such as triisopropoxyaluminum Examples include aluminum compounds and alkoxyzirconium compounds such as tetraisopropoxyzirconium.

  These metal alkoxides must be partially or wholly hydrolyzed, partially hydrolyzed or condensed, fully hydrolyzed and partially condensed, or a combination of these. You can also.

  When the above metal alkoxide and polycarboxylic acid are mixed, it may be difficult for both to react and to be applied. Therefore, it is preferable to form a hydrolysis condensate in advance before mixing. As a method for forming the hydrolysis-condensation product, a method used in a known sol-gel method can be applied.

  In the oxygen barrier layer (II) in the present invention, a thermal stabilizer, an antioxidant, a reinforcing material, a pigment, and an anti-degradation agent are used as long as the oxygen barrier property and the adhesion to the plastic substrate (I) are not greatly impaired. , Weathering agents, flame retardants, plasticizers, mold release agents, lubricants, preservatives, antifoaming agents, wetting agents, viscosity modifiers, and the like may be added. Examples of the heat stabilizer, antioxidant, and deterioration inhibitor include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and the like. May be. Examples of the reinforcing material include clay, talc, wollastonite, silica, alumina, calcium silicate, sodium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, zeolite, montmorillonite, hydrotalcite, fluorine mica, Examples include metal fibers, metal whiskers, ceramic whiskers, potassium titanate whiskers, boron nitride, graphite, glass fibers, carbon fibers, fullerenes (C60, C70, etc.), carbon nanotubes, and the like.

  In the present invention, the thickness of the oxygen barrier layer (II) laminated on the plastic substrate (I) is preferably thicker than 0.05 μm in order to sufficiently enhance the oxygen barrier property of the laminate, from the economical viewpoint. Therefore, it is preferable that the thickness is less than 5.0 μm.

  The oxygen barrier layer (II) in the present invention can be formed by applying and drying an oxygen barrier layer (II) forming coating solution on the plastic substrate (I). Since the coating liquid is preferably aqueous from the viewpoint of workability, the polycarboxylic acid, polyalcohol and polyamine constituting the coating liquid are preferably water-soluble or water-dispersible, and water-soluble. It is more preferable that

  In the present invention, when an aqueous coating solution is prepared by mixing a polycarboxylic acid and a polyalcohol, it is preferable to add 0.1 to 20 equivalent% of an alkali compound with respect to the carboxyl group of the polycarboxylic acid. . Since polycarboxylic acid has high hydrophilicity when the content of carboxyl group is large, it can be made into an aqueous solution without adding an alkali compound. However, the oxygen barrier property of the obtained laminate can be significantly improved by adding an appropriate amount of an alkali compound. The alkali compound only needs to be capable of neutralizing the carboxyl group of the polycarboxylic acid, and the addition amount thereof is preferably 0.1 to 20 mol% with respect to the carboxyl group of the polycarboxylic acid.

  The coating liquid can be prepared by a known method using a melting pot equipped with a stirrer. For example, a polycarboxylic acid and a polyalcohol are separately made into aqueous solutions and mixed before coating. The method is preferred. At this time, if the alkali compound is added to the aqueous solution of the polycarboxylic acid, the stability of the aqueous solution can be improved.

  Moreover, in this invention, when mixing polycarboxylic acid and polyamine and preparing an aqueous coating liquid, in order to suppress gelatinization, it is preferable to add a base to polycarboxylic acid. The base is not particularly limited as long as it does not inhibit the oxygen barrier property of the obtained laminate, and examples thereof include inorganic substances such as sodium hydroxide and calcium hydroxide, and organic substances such as ammonia, methylamine and diethanolamine, and drying and heat treatment. Since it is easy to volatilize, ammonia is preferable. The addition amount of the base is preferably 0.6 equivalents or more, more preferably 0.7 equivalents or more, and further preferably 0.8 equivalents or more with respect to the carboxyl group of the polycarboxylic acid. . If the amount of base added is small, the coating solution may gel during coating, and it may be difficult to form the oxygen barrier layer (II) on the plastic substrate (I).

  The method of applying the oxygen barrier layer (II) forming coating liquid to the plastic substrate (I) is not particularly limited, and is an air knife coater, kiss roll coater, metering bar coater, gravure roll coater, reverse roll coater, dip. A coater, a die coater or the like, or a combination of these methods can be used.

  After the coating liquid for forming the oxygen barrier layer (II) is applied to the plastic substrate (I), the heat treatment may be performed immediately, and the formation of the dry film and the heat treatment may be performed at the same time. Heat treatment may be performed after moisture or the like is evaporated by hot air blowing or infrared irradiation to form a dry film. It is preferable to perform the heat treatment immediately after coating, unless there is a particular obstacle to the state of the oxygen barrier layer (II) and physical properties such as oxygen barrier properties. It does not specifically limit as a heat processing method, The method of heat-processing in dry atmosphere, such as oven, is mentioned. Considering shortening of the process, it is preferable to stretch the plastic substrate (I) after applying the oxygen barrier layer (II) forming coating solution. In any of the above cases, the plastic substrate (I) on which the oxygen barrier layer (II) is formed is preferably subjected to a heat treatment for 5 minutes or less in a heated atmosphere of 100 ° C. or higher.

  When the oxygen barrier layer (II) contains a polycarboxylic acid and a polyalcohol, it can be affected by the ratio, presence / absence of additive components, content thereof, etc. The heat treatment temperature is not generally known, but is preferably 100 to 300 ° C, more preferably 120 to 250 ° C, further preferably 140 to 240 ° C, and 160 to 220 ° C. It is particularly preferred. If the heat treatment temperature is too low, the cross-linking reaction between the polycarboxylic acid and the polyalcohol cannot be sufficiently progressed, and it may be difficult to obtain a laminate having sufficient oxygen barrier properties. If it is too high, the oxygen barrier layer (II) and the like may become brittle. The heat treatment time is preferably 5 minutes or less, more preferably from 1 second to 5 minutes, further preferably from 3 seconds to 2 minutes, and particularly preferably from 5 seconds to 1 minute. . If the heat treatment time is too short, the crosslinking reaction cannot proceed sufficiently, and it becomes difficult to obtain a laminate having oxygen barrier properties. On the other hand, if the heat treatment time is too long, productivity decreases.

  In addition, the oxygen barrier layer (II) forming coating solution applied to the plastic substrate (I) is irradiated with high energy rays such as ultraviolet rays, X-rays, and electron beams as necessary before and after the drying. May be applied. In such a case, a component that is crosslinked or polymerized by irradiation with high energy rays may be blended.

Since the laminate of the present invention has the above-described configuration, it has excellent oxygen barrier properties. The laminate subjected to hydrothermal treatment at 95 ° C. for 30 minutes was measured in an atmosphere at 20 ° C. and relative humidity of 65%. the oxygen ^{permeability, 300mL / (m 2 · day} · MPa) can be less, the oxygen permeability is preferably ^{0.01~300mL / (m 2 · day ·} MPa), 0.01 more preferably ~ 200 mL ^/ a (m 2 · day · MPa) , more preferably a ^{0.01~100mL / (m 2 · day ·} MPa).

The laminate of the present invention preferably has a tensile strength of 150 MPa or more, and more preferably 180 MPa or more. If the tensile strength is less than 150 MPa, the mechanical strength is not sufficient, and the piercing strength tends to decrease. In addition, the tensile elongation is preferably 60% or more, and more preferably 80% or more, from the same viewpoint as the tensile strength.

  The pinhole resistance of the laminate of the present invention is preferably 100 or less, more preferably 20 or less, in the 500 times repeated bending fatigue test at 5 ° C. atmosphere. Specifically, the pinhole resistance is Fed. Shown in MIL-B-131F. Test Method Std. In accordance with Method 2017 of 101C, a sample of 12 inches × 8 inches is gripped in a cylindrical shape with a diameter of 3.5 inches, with an initial gripping distance of 7 inches and a gripping distance of 1 inch at maximum bending, a so-called gel bot tester (manufactured by Rigaku Corporation) The number of pinholes generated after being bent 500 times at 5 ° C. was measured and evaluated.

  Regarding the transparency of the laminate of the present invention, the haze is preferably 70% or less, more preferably 50% or less, further preferably 30% or less, and particularly preferably 15% or less. Most preferably, it is 10% or less. However, this is not the case because transparency may not be required depending on the application.

  The laminate of the present invention can be produced by the following method.

  The plastic substrate (I) made of a single layer film is made of, for example, a thermoplastic resin mixed with a metal compound, heated and melted with an extruder and extruded into a film from a T-die, air knife casting method, electrostatic application It cools and solidifies on the cooling drum rotated by well-known casting methods, such as the casting method, and the film of the unstretched plastic base material (I) is obtained.

  In addition, the plastic substrate (I) composed of a multilayer film, for example, heat-melts a thermoplastic resin mixed with a metal compound in the extruder A, and heat-melts the thermoplastic resin in the extruder B, respectively. By superposing two types of melted resins in a die, for example, extruding a film having a two-layer structure of metal-containing layer (M) / resin layer (R) from a T-die, and cooling and solidifying in the same manner as above, It can be obtained in a stretched state.

  By including the metal compound in the plastic substrate (I) by such a method, the step of laminating the layer containing the metal compound, which has been conventionally performed, on the substrate can be omitted.

  The oxygen barrier layer (II) is formed by applying the oxygen barrier layer (II) forming coating solution to the obtained single-layer or multi-layer unstretched film by the method described above, and a tenter type simultaneous biaxial stretching machine. Thus, a simultaneous biaxially stretched laminate can be obtained by performing simultaneous biaxial stretching in the machine direction (MD) and the transverse direction (TD). In addition, after the obtained unstretched film is stretched to MD, the oxygen barrier layer (II) forming coating solution is applied by the above-described method to form the oxygen barrier layer (II), and then the TD is stretched. Thus, a laminated body sequentially biaxially stretched can be obtained. If the unstretched film is oriented, the stretchability may be lowered in a later step. Therefore, it is preferable that the unstretched film is substantially amorphous and non-oriented.

  When using a polyamide resin as the thermoplastic resin, transfer the unstretched film to a water tank whose temperature is adjusted so as not to exceed 80 ° C., and subject it to a water immersion treatment within 5 minutes and a moisture absorption treatment of 0.5 to 15%. Is preferred.

  In addition, the stretching ratio of the film is preferably 1.5 times or more in the case of uniaxial stretching, and also in the case of longitudinal and lateral biaxial stretching, it is preferably 1.5 times or more in the vertical and horizontal directions. Usually, it is preferably 3 times or more, more preferably 6 to 20 times, and even more preferably 6.5 to 13 times. When the draw ratio is in this range, a laminate having excellent mechanical properties can be obtained.

  The film that has undergone the stretching process is heat-set at a temperature of 150 to 300 ° C. in the tenter that has been subjected to the stretching process, and is 0 to 10%, preferably 2 to 6% as necessary. Alternatively, MD relaxation treatment is performed. In order to reduce the heat shrinkage rate, it is desirable not only to optimize the temperature and time of the heat setting time, but also to perform the heat relaxation process at a temperature lower than the maximum temperature of the heat setting process.

  The stretching method is not particularly limited, but it is preferable to use a simultaneous biaxial stretching method. In general, the simultaneous biaxial stretching method can have practical characteristics such as mechanical characteristics, optical characteristics, thermal dimensional stability, and pinhole resistance. In addition, in the sequential biaxial stretching method in which the transverse stretching is performed after the longitudinal stretching, the orientation crystallization of the film proceeds during the longitudinal stretching, and the stretchability of the thermoplastic resin during the transverse stretching is reduced, thereby blending the metal compound. When the amount is large, the breaking frequency of the film tends to increase. For this reason, in this invention, it is preferable to perform a water absorption process and to take the simultaneous biaxial stretching method.

  The laminated body of this invention can also be processed in the humidified atmosphere after manufacturing a laminated body for the purpose of improving oxygen barrier property. By the humidification treatment, the action of the metal compound of the plastic substrate (I) and the polycarboxylic acid of the oxygen barrier layer (II) can be further promoted. In such humidification treatment, the laminate may be left in an atmosphere of high temperature and high humidity, or the laminate may be directly contacted with high temperature water. Humidification conditions vary depending on various purposes, but when left in an atmosphere of high temperature and high humidity, a temperature of 30 to 130 ° C. and a relative humidity of 50 to 100% are preferable. Also when making it contact with high temperature water, the temperature of about 30-130 degreeC (100 degreeC or more is under pressure) is preferable. The humidifying treatment time varies depending on the treatment conditions, but generally a range of several seconds to several hundred hours is selected.

  The laminate of the present invention may be subjected to a surface treatment such as a corona discharge treatment as necessary.

  A sealant layer may be further laminated on the laminate of the present invention.

  The resin used as the sealant is low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, polyethylene / polypropylene copolymer, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-acrylic acid. / Methacrylic acid copolymer, ethylene-acrylic acid / methacrylic ester copolymer, polyvinyl acetate resin, etc., polyethylene, polypropylene, polyethylene / polypropylene copolymer, etc. with high heat seal strength and material strength The polyolefin resin is preferred. These resins may be used alone, or may be copolymerized or melt-mixed with other resins, or may be further acid-modified.

  Examples of a method for forming a sealant layer in a laminate include a method of laminating a film or sheet made of a sealant resin on a laminate via an adhesive, a method of extrusion laminating a sealant resin to a laminate, and the like. . In the former method, the film or sheet made of the sealant resin may be in an unstretched state or in a stretched state at a low magnification, but practically preferably in an unstretched state.

  Although the thickness of a sealant layer is not specifically limited, It is preferable that it is 20-100 micrometers, and it is more preferable that it is 40-70 micrometers.

  In the present invention, when the oxygen absorbent-containing layer is provided, the sealant layer is preferably provided on the oxygen absorbent-containing layer. By arranging in this way, oxygen entering from outside the packaging bag can be blocked and oxygen remaining in the packaging bag can be absorbed, so that deterioration of the contents due to oxygen can be prevented more effectively. .

  A packaging bag can be produced using the laminate of the present invention, and this packaging bag is, for example, a food / beverage product, fruit, juice, drinking water, liquor, cooked food, marine product, frozen food, meat product, Contents such as boiled foods, rice cakes, liquid soups, seasonings, other various foods and beverages, liquid detergents, cosmetics, and chemical products can be filled and packaged.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to these Examples.

1. Measuring method

(1) Thickness of each layer The laminate was allowed to stand for 2 hours or more in an environment of 23 ° C. and 50% RH, and then the film cross-section was observed with a scanning electron microscope (SEM) to measure the thickness of each layer.

(2) Oxygen permeability After the laminate was hydrothermally treated at 95 ° C. for 30 minutes, it was left in an environment of 23 ° C. and 50% RH for 2 hours or more, and then an oxygen barrier measuring instrument (OX manufactured by Mocon Co., Ltd.) -TRAN 2/20) was used to measure oxygen permeability in an atmosphere at a temperature of 20 ° C. and a relative humidity of 65%. The unit is mL / (m ² · day · MPa).

(3) Contents preservation evaluation In a three-sided bag (outside dimension: MD200 mm × TD150 mm, seal width: 10 mm) made of a laminate, citric acid 1 mass%, glucose 5 mass%, glycine 0.3 mass%, vitamin C 0 200 mL of an aqueous solution containing 1% by mass was charged, subjected to a retort treatment (hot water shower type) at 120 ° C. for 30 minutes, and then stored in a dark environment of 40 ° C. × 90% RH for 3 months. After storage, the absorbance at 430 nm was measured for the model solution using a spectrophotometer.

2. Raw materials The raw materials used in the following examples and comparative examples are as follows.
(1) Thermoplastic resin for construction of plastic substrate (I) PA6: Polyamide 6 resin (A1030BRF, manufactured by Unitika Ltd., relative viscosity 3.0)

(2) Metal compound / MgO: Magnesium oxide (Puremag FNM-G average particle size 0.4 μm, manufactured by Tateho Chemical Co., Ltd.)

(3) Metal compound master chip It was obtained by kneading 85 parts by mass of polyamide 6 resin and 15 parts by mass of magnesium oxide.

(4) Oxygen absorber, oxidation accelerator, Bu-MA: maleic acid-modified polybutadiene (Rincon 131 MA10 manufactured by Clay Valley)
MXD6: poly (metaxylylene adipamide) (Mitsubishi Gas Chemical Company, MI = 2, S6007)
StCo: Cobalt stearate (II) (manufactured by Kanto Chemical Co., Inc.)
CeOx: cerium oxide reduced powder (Mitsui Metal Mining Co., Ltd., average particle size 5 μm)

(5) Oxygen absorbent master chip / Oxygen absorbent master chip 1
It was obtained by kneading 100 parts by mass of polyamide 6 resin, 100 parts by mass of Bu-MA, and 2 parts by mass of StCo.
・ Oxygen absorbent master chip 2
It was obtained by kneading 100 parts by mass of polyamide 6 resin, 100 parts by mass of MXD6, and 2 parts by mass of StCo.
・ Oxidizing absorbent master chip 3
It was obtained by kneading 100 parts by mass of polyamide 6 resin and 34 parts by mass of CeOx.

(6) Adhesive LX-500 (60% ethyl acetate solution of aliphatic polyester, manufactured by Dainippon Ink & Chemicals) 150 parts by mass and KR-90S (90% ethyl acetate solution of aliphatic polyisocyanate, Dainippon Ink) It was obtained by mixing and stirring 10 parts by mass of Chemical Industries, Ltd.

(7) Oxygen Absorbent-Containing Adhesive LX-500 150 parts by mass and CeOx 40 parts by mass were dispersed with a bead mill whose inside was replaced with nitrogen gas, and then mixed and stirred with KR-90S 10 parts by mass.

(8) Polycarboxylic acid component / EMA aqueous solution:
EMA (weight average molecular weight 60000) and sodium hydroxide were added to water, dissolved by heating and then cooled to room temperature. 10 mol% of the carboxyl group of EMA was neutralized with sodium hydroxide, solid content 15 Mass% EMA aqueous solution.
-PAA aqueous solution:
10 mol% of the carboxyl group of polyacrylic acid prepared with polyacrylic acid (A10H, manufactured by Toagosei Co., Ltd., number average molecular weight 200000, 25 wt% aqueous solution) and sodium hydroxide was neutralized with sodium hydroxide. An aqueous polyacrylic acid (PAA) solution having a solid content of 15% by mass.

(9) Other resin component / PVA aqueous solution of oxygen barrier layer forming coating solution:
Polyvinyl alcohol (Polyal 105 manufactured by Kuraray Co., Ltd., saponification degree 98 to 99%, average polymerization degree about 500) was added to water, dissolved by heating, and then cooled to room temperature. PVA) aqueous solution.

(10) Sealant / CPP: Unstretched polypropylene film (RXC-22 manufactured by Mitsui Chemicals, Inc., thickness 50 μm)

Example 1
The polyamide 6 resin and the metal compound master chip were mixed so that the magnesium oxide content was 0.5 mass%. This mixture was charged into an extruder and melted in a 270 ° C. cylinder. The melt was extruded into a sheet form from a T-die orifice, was brought into close contact with a rotating drum cooled to 10 ° C., and rapidly cooled to obtain an unstretched polyamide film having a thickness of 150 μm. The obtained unstretched film was sent to a 50 ° C. hot water tank and subjected to a water immersion treatment for 2 minutes.
Next, an EMA aqueous solution and a PVA aqueous solution are mixed so that the mass ratio (solid content) of PVA and EMA is 5/5 to obtain a coating solution for forming an oxygen barrier layer having a solid content of 10% by mass. It was. This coating solution was applied to one side of an unstretched film that had been subjected to water immersion treatment, and then dried.
The end of the film was held by a clip of a tenter simultaneous biaxial stretching machine, and stretched at 180 ° C. to MD and TD by 3.3 times. Thereafter, the relaxation rate of TD was set to 5%, and heat treatment was performed at 210 ° C. for 4 seconds, gradually cooled to room temperature, the coated surface was subjected to corona treatment, and a polyamide film having a thickness of 15 μm was formed to have a thickness of 0.3 μm. A laminate in which an oxygen barrier layer was laminated (hereinafter abbreviated as “laminate A”) was obtained.
The oxygen barrier layer of the obtained laminate A was subjected to corona treatment, and an oxygen absorbent adhesive was applied after drying to 5 g / m ² and dried for 10 seconds with a hot air dryer at 80 ° C. Subsequently, the adhesive layer and the corona-treated surface of the sealant were bonded together with a nip roll heated to 80 ° C. This was packaged in an aluminum bag and then aged at 40 ° C. for 72 hours to obtain a laminate comprising polyamide film / oxygen barrier layer / oxygen absorbent-containing adhesive layer / sealant.

Example 2
Polyamide film / oxygen barrier layer / oxygen absorber contained, in the same manner as in Example 1, except that the oxygen barrier forming coating solution was PAA instead of EMA, and the ratio of PVA to PAA was 3/7 A laminate comprising an adhesive layer / sealant was obtained.

Example 3
A coating solution for forming an oxygen barrier layer was prepared as follows.
That is, polyacrylic acid (PAA) having a number average molecular weight of 200,000 and polyvinyl alcohol (manufactured by Kuraray Co., Ltd., PVA-105) were dissolved in distilled water so as to have a mass ratio of 97: 3. Next, aqueous ammonia was added to neutralize 1.5 mol% of the carboxyl groups of polyacrylic acid. In this manner, a polymer aqueous solution having a solid content concentration of 10% by mass in the aqueous solution and containing polyacrylic acid and polyvinyl alcohol was obtained. Next, 68.4 parts by mass of tetramethoxysilane (TMOS) is dissolved in 82.0 parts by mass of methanol, and then 13.6 parts by mass of γ-glycidoxypropyltrimethoxysilane is dissolved. 13 parts by mass and 12.7 parts by mass of 0.1N hydrochloric acid were added to prepare a sol, which was subjected to hydrolysis and condensation reaction at 10 ° C. for 1 hour with stirring. The obtained sol was diluted with 185 parts by mass of distilled water and then quickly added to 634 parts by mass of the polymer aqueous solution under stirring to obtain a solution.
A laminate comprising polyamide film / oxygen barrier layer / oxygen absorber-containing adhesive layer / sealant was prepared in the same manner as in Example 1 except that the solution prepared by the above method was used as a coating solution for forming an oxygen barrier layer. Obtained.

Example 4
The polyamide 6 resin and the oxygen absorbent master chip 1 were mixed so that the content of Bu-MA was 10% by mass and the content of StCo was 0.2% by mass. This mixture was put into an extruder and melted in a 260 ° C. cylinder. The melt was extruded into a sheet form from a T-die orifice, and brought into close contact with a rotating drum cooled to 10 ° C. and rapidly cooled to obtain an unstretched film containing an oxygen absorbent having a thickness of 150 μm. The obtained unstretched polyamide film was sent to a 50 ° C. hot water tank and subjected to a water immersion treatment for 2 minutes.
The end of the film was held by a clip of a tenter simultaneous biaxial stretching machine, and stretched at 180 ° C. to MD and TD by 3.3 times. Then, the relaxation rate of TD was set to 5%, heat treatment was performed at 210 ° C. for 4 seconds, the mixture was gradually cooled to room temperature, and both sides were subjected to corona treatment to obtain a stretched film containing an oxygen absorbent having a thickness of 15 μm.
It applied to the obtained stretched film so that an adhesive might become 5 g / m < ² > after drying, and it was made to dry for 10 second with a 80 degreeC hot air dryer. Subsequently, the adhesive layer and the oxygen barrier layer of the laminate A were bonded together with a nip roll heated to 80 ° C. Thereafter, the adhesive was applied to the other surface of the stretched film containing the oxygen absorbent so as to be 5 g / m ² after drying, and dried for 10 seconds with a hot air dryer at 80 ° C. Subsequently, the adhesive layer and the corona-treated surface of the sealant were bonded together with a nip roll heated to 80 ° C. This was packaged with an aluminum bag and then aged at 40 ° C. for 72 hours to obtain a laminate comprising polyamide film / oxygen barrier layer / adhesive layer / oxygen absorbent-containing layer / adhesive layer / sealant.

Example 5
Change the oxygen absorbent master chip 1 to the oxidized absorbent master chip 2 and mix them so that the MXD6 content is 10% by mass and the StCo content is 0.2% by mass. A laminate comprising polyamide film / oxygen barrier layer / adhesive layer / oxygen absorbent-containing layer / adhesive layer / sealant was obtained in the same manner as in Example 4 except that charging was performed.

Example 6
The polyamide 6 resin and the metal compound master chip were mixed so that the magnesium oxide content was 50 parts by mass. This mixture was put into an extruder A and melt-extruded at 260 ° C. On the other hand, polyamide 6 resin was put into extruder B and melt extruded at 260 ° C.
Two types of resins melted in the extruder A and the extruder B are overlapped in a die, and a sheet having a two-layer structure of a metal-containing layer (M) / resin layer (R) is extruded from a T die, and a surface temperature of 20 An unstretched multi-layer film having a thickness of 150 μm, which is (M) / (R) = 20/130 μm, was obtained by closely adhering to a cooling roll at ° C. The obtained unstretched multilayer film was sent to a 50 ° C. hot water tank and subjected to water immersion treatment for 2 minutes.
Next, the coating liquid prepared in the same manner as in Example 1 was applied to the metal-containing layer (M) surface of the unstretched multilayer film and then dried.
In the same manner as in Example 1, a plastic substrate having a thickness of 15 μm comprising a metal-containing layer (M) having a thickness of 2 μm and a resin layer (R) having a thickness of 13 μm by simultaneous biaxial stretching and heat treatment ( A laminate (hereinafter abbreviated as “laminate B”) in which an oxygen barrier layer having a thickness of 0.3 μm was laminated on the metal-containing layer (M) of I) was obtained.
The laminate B produced by the above method is changed to the laminate A, the oxygen absorbent master chip 1 is changed to the oxidized absorbent master chip 3, and mixed so that the CeOx content is 25% by mass, A laminate comprising polyamide film / oxygen barrier layer / adhesive layer / oxygen absorbent-containing layer / adhesive layer / sealant was obtained in the same manner as in Example 4 except that it was introduced into an extruder.

Example 7
A nylon 6 resin, a metal compound master chip, and an oxygen absorbent-containing master chip 2 have a magnesium oxide content of 0.5 mass%, an MXD6 content of 10 mass%, and a StCo content of 0.2 mass%. It mixed so that it might become. This mixture was put into an extruder and melted in a cylinder at 280 ° C. The melt was extruded into a sheet form from a T-die orifice, and brought into close contact with a rotating drum cooled to 10 ° C. and rapidly cooled to obtain an unstretched polyamide film containing an oxygen absorbent having a thickness of 150 μm. The obtained unstretched film was sent to a 50 ° C. hot water tank and subjected to a water immersion treatment for 2 minutes.
Next, an EMA aqueous solution and a PVA aqueous solution are mixed so that the mass ratio (solid content) of PVA and EMA is 5/5 to obtain a coating solution for forming an oxygen barrier layer having a solid content of 10% by mass. It was. This coating solution was applied to one side of an unstretched film that had been subjected to water immersion treatment, and then dried.
The end of the film was held by a clip of a tenter simultaneous biaxial stretching machine, and stretched at 180 ° C. to MD and TD by 3.3 times. Thereafter, the relaxation rate of TD was set to 5%, heat treatment was performed at 210 ° C. for 4 seconds, gradually cooled to room temperature, the coated surface was subjected to corona treatment, and a polyamide film containing an oxygen absorbent having a thickness of 15 μm was obtained. A laminate in which an oxygen barrier layer having a thickness of 0.3 μm was laminated was obtained.
The surface opposite to the oxygen barrier layer of the obtained laminate was subjected to corona treatment, applied so that the adhesive was 5 g / m ² after drying, and dried with a hot air dryer at 80 ° C. for 10 seconds. Subsequently, the adhesive layer and the corona-treated surface of the sealant were bonded together with a nip roll heated to 80 ° C. This was packaged with an aluminum bag and then aged at 40 ° C. for 72 hours to obtain a laminate comprising oxygen barrier layer / oxygen absorbent-containing polyamide film / adhesive layer / sealant.

Comparative Example 1
A laminate was obtained in the same manner as in Example 1 except that an adhesive containing no oxygen absorbent was used instead of the oxygen absorbent adhesive.

Comparative Example 2
A laminate was obtained in the same manner as in Example 1 except that polyamide 6 resin was used instead of the metal compound master chip.

Comparative Example 3
A laminate was obtained in the same manner as in Example 1 except that the oxygen barrier layer-forming coating solution was not applied.

Comparative Example 4
A laminate was obtained in the same manner as in Example 5 except that polyamide 6 resin was used instead of the oxygen absorbent master chip 1.

  Table 1 shows the structures of the laminates obtained in Examples and Comparative Examples, and the evaluation results.

All of the laminates of Examples 1 to 7 were excellent in oxygen barrier properties and had a small absorbance for 6 months.
Since the laminates of Comparative Examples 1 and 4 did not use an oxygen absorbent, the absorbance at 6 months was large.
Since the laminate of Comparative Example 2 did not contain a metal compound in the plastic substrate, the oxygen barrier property was poor and the absorbance at 6 months was also large.
Since the laminated body of Comparative Example 3 was not provided with an oxygen barrier layer, the oxygen barrier property was poor and the absorbance at 6 months was also large.

Claims (6)

A plastic substrate (I) including a metal-containing layer containing a metal compound and an oxygen absorbent, and an oxygen barrier layer (II) containing a polycarboxylic acid ,
The metal-containing layer is obtained by extruding a melt of a thermoplastic resin containing 0.1 to 70 mass% of a metal compound and mixed with the metal compound,
The metal-containing layer and the oxygen barrier layer are in contact,
After hydrothermal treatment at 95 ° C. for 30 minutes, the oxygen permeability in an atmosphere at 20 ° C. and a relative humidity of 65% is 0.01 to 16 ml / (m ² · day · MPa) ,
The plastic substrate (I) is stretched,
A laminate characterized by the above. A laminate in which a layer containing an oxygen absorbent is provided on a laminate comprising a plastic substrate (I) including a metal-containing layer containing a metal compound and an oxygen barrier layer (II) containing a polycarboxylic acid. There,
The metal-containing layer is obtained by extruding a melt of a thermoplastic resin containing 0.1 to 70 mass% of a metal compound and mixed with the metal compound,
The metal-containing layer and the oxygen barrier layer are in contact,
After hydrothermal treatment at 95 ° C. for 30 minutes, the oxygen permeability in an atmosphere at 20 ° C. and a relative humidity of 65% is 0.01 to 16 ml / (m ² · day · MPa) ,
The plastic substrate (I) is stretched,
A laminate characterized by the above. Furthermore, the sealant layer was provided, The laminated body of Claim 1 or 2 characterized by the above-mentioned. The laminate according to claim 3, wherein the sealant layer is disposed on the layer side containing the oxygen absorbent. The laminate according to any one of claims 1 to 4, wherein the plastic substrate (I) is a multilayer film, and at least one layer thereof is a metal-containing layer . A packaging bag comprising the laminate according to any one of claims 1 to 5.