JP2015160329A - Laminate having excellent light shielding properties and gas barrier properties - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate having excellent productivity and economical efficiency, and excellent light shielding properties and gas barrier properties after hot water treatment.SOLUTION: This invention provides a laminate that comprises a gas barrier layer (II) comprising polycarboxylic acid and placed on plastic base material (I) comprising a metal compound of 0.1-70 mass%, and has a total light transmittance of 50% or less. This invention provides a laminate in which the plastic base material (I) may be a multilayer film, and a colorant is comprised in at least one layer of the multilayer film. This invention provides a laminate in which the plastic base material (I) is composed of polyamide resin or polyester resin, and the metal compound is one selected from Mg, Ca, and Zn. This invention provides a laminate in which after heat treatment for 30 minutes at 95°C, an oxygen permeability in an atmosphere of a relative humidity 65% at 20°C is 300 mL/(m/day/MPa) or less.

Description

  The present invention relates to a laminate excellent in light shielding properties and gas barrier properties after hydrothermal treatment.

  Conventionally, films with excellent light-shielding properties and gas barrier properties after hot water treatment are laminated with aluminum foil and aluminum vapor-deposited films and used as packaging materials for contents such as oil-containing foods, boiled / retort foods, and frozen foods. Has been. However, although aluminum foil and aluminum vapor-deposited film are excellent in gas barrier properties and light shielding properties, there is a problem that foreign matter contamination inspection cannot be performed by a metal detector.

  As a film having excellent light-shielding properties and gas barrier properties after hot water treatment, and capable of inspecting contamination, for example, Patent Document 1 discloses a film containing a white pigment, a polyalcohol polymer and a polycarboxylic acid polymer. And a gas barrier layer containing a metal compound and an overcoat layer containing a metal compound are disclosed. However, in the method disclosed in Patent Document 1, the overcoat layer is formed by applying and drying a solvent-based paint, and then the gas barrier layer is formed by applying and drying a water-based paint. 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 application in order to use a solvent-based paint.

JP 2012-016925 A

  The subject of this invention is providing the laminated body which was excellent in productivity and economical efficiency, and excellent in light-shielding property and the gas barrier property after a hot-water process, solving the said problem.

  As a result of intensive studies on the above problems, the present inventor has excellent productivity and economical efficiency, light shielding properties and hot water by laminating a gas barrier layer containing a polycarboxylic acid on a plastic substrate containing a metal compound. The present inventors have found that an excellent laminate can be provided after the treatment and have reached the present invention.

That is, the gist of the present invention is as follows.
(1) A gas barrier layer (II) containing a polycarboxylic acid is laminated on a plastic substrate (I) containing 0.1 to 70% by mass of a metal compound, and the total light transmittance is 50% or less. A laminate characterized by the following.
(2) The laminate according to (1), wherein the plastic substrate (I) is a multilayer film, and at least one layer contains a colorant.
(3) The laminate according to (1) or (2), wherein the thermoplastic resin constituting the plastic substrate (I) is a polyamide resin or a polyester resin.
(4) The laminated body according to any one of (1) to (3), wherein the metal constituting the metal compound is one selected from magnesium, calcium, and zinc.
(5) After hot water treatment at 95 ° C. for 30 minutes, the oxygen permeability in an atmosphere at 20 ° C. and 65% relative humidity is 300 mL / (m ² · day · MPa) or less (1 The laminated body in any one of (4).
(6) The laminate according to any one of (1) to (5), which is simultaneously or sequentially biaxially stretched.
(7) A packaging bag comprising the laminate according to any one of (1) to (6).

ADVANTAGE OF THE INVENTION According to this invention, the laminated body excellent in productivity and economical efficiency, and excellent in light-shielding property and the gas barrier property after a hot-water process can be provided.
That is, in the present invention, the plastic base material containing a metal compound 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 step of stacking can be omitted. 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 is obtained by laminating a plastic substrate (I) containing a metal compound and a gas barrier layer (II) containing a polycarboxylic acid.

  The metal constituting the metal compound contained in the plastic substrate (I) is not particularly limited, and monovalent metals such as lithium, sodium, potassium, rubidium and cesium, magnesium, calcium, zirconium, zinc, copper Bivalent or higher metal such as cobalt, iron, nickel, 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 gas barrier properties. Specifically, lithium, sodium, potassium, magnesium, calcium, and zinc are preferable, and magnesium, calcium, and zinc are more preferable. These may be used alone or in combination.

  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 and the like can be mentioned. From the viewpoint of gas barrier properties, magnesium oxide, magnesium carbonate, magnesium hydroxide, magnesium acetate, calcium carbonate, calcium acetate, zinc oxide divalent metal compound Is preferred. A metal compound may be used independently and may be used together.

  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. A metal compound having an average particle size of less than 0.001 μm is likely to aggregate because of its large surface area, and coarse aggregates may be scattered in the film, thereby reducing 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) needs to be 0.1 to 70% by mass, preferably 0.1 to 50% by mass, and 0.2 to 20% by mass. More preferably, it is 0.2-5 mass%. When the content of the metal compound in the plastic substrate (I) is 0.1 to 70% by mass, the resulting laminate can obtain excellent gas barrier properties. However, when the content of the metal compound in the plastic substrate (I) is less than 0.1% by mass, the crosslinked structure formed by reacting with the polycarboxylic acid in the gas barrier layer (II) is reduced and obtained. The film has a reduced gas barrier property. On the other hand, the plastic substrate (I) having a content exceeding 70% by mass has a high frequency of breakage during stretching during film formation, tends to reduce productivity, and mechanical properties.

  The total light transmittance of the laminate of the present invention is required to be 50% or less, preferably 30% or less, more preferably 15% or less, and further preferably 10% or less. In order to set the total light transmittance of the laminate to 50% or less, it is necessary to include a colorant in any layer of the laminate. Examples of the colorant include a pigment or a dye, and examples of the pigment include a white pigment and a black pigment. A colorant may be used in combination.

  Examples of the white pigment include titanium oxide, barium sulfate, zinc sulfide, and calcium carbonate. Among these, titanium oxide is preferable from the viewpoint of light shielding properties. The content of the white pigment in the plastic substrate (I) is preferably 5 to 40% by mass, and more preferably 15 to 30% by mass. Examples of black pigments include iron black, graphite, carbon black, polyaniline, and polypyrrole. The content of the black pigment in the plastic substrate (I) is preferably 2 to 25% by mass, and more preferably 5 to 20% by mass. Examples of other pigments include aluminum powder, brass, and copper powder.

  The colorant may be contained in the plastic substrate (I) or in the gas barrier layer (II). Another layer may be provided on one or both sides of the colored layer in order to prevent the colorant from being lost.

  The thermoplastic resin constituting the plastic substrate (I) includes polyolefin resins such as polyethylene, polypropylene and ionomer, polyamide resins such as polyamide 6, polyamide 66, polyamide 46, polyamide MXD6 and polyamide 9T, polyethylene terephthalate, polyethylene isophthalate. , Polyethylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, polylactic acid, etc. polyester resin, vinyl chloride, polystyrene resin, polycarbonate resin, polyarylate resin, ethylene-vinyl acetate Examples thereof include a polymer, 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. .

  For thermoplastic resins, in addition to the additives, if necessary, thermal stabilizers, antioxidants, reinforcing materials, deterioration inhibitors, weathering agents, as long as they do not adversely affect the performance of the plastic substrate (I). Various additives such as flame retardants, plasticizers, preservatives, ultraviolet absorbers, antistatic agents, and antiblocking agents may be added alone or in combination.

  A method for adding a metal compound, a colorant, and an additive to the thermoplastic resin is not particularly limited, and the thermoplastic resin can be blended at an arbitrary point in the manufacturing process. For example, a method of adding when polymerizing a thermoplastic resin constituting the plastic substrate (I), a method of kneading with a thermoplastic resin and an extruder, or a master batch mixed and kneaded at a high concentration is manufactured. The method of adding this to a thermoplastic resin and diluting it (masterbatch method) etc. are mentioned. In the present invention, the master batch method is preferably employed.

  The plastic substrate (I) may be a single-layer film or a multi-layer film. When the plastic substrate (I) is a single layer film, the metal compound needs to be contained in the single layer film in an amount of 0.1 to 70% by mass, and the plastic substrate (I) is a multilayer film. When it exists, it is necessary to contain 0.1-70 mass% in the at least 1 layer. Moreover, when a coloring agent contains in a multilayer film, a coloring agent may be contained only in one layer of a multilayer film, and may be contained in two or more layers.

  Hereinafter, in a multilayer film, a layer containing a metal compound that imparts gas barrier properties is a “metal compound layer (M)”, a layer containing a colorant is “colored layer (C)”, and a metal compound that imparts gas barrier properties And a layer containing the colorant in the same layer may be abbreviated as “metal compound / colored layer (MC)”, and a layer containing neither metal compound nor colorant may be abbreviated as “resin layer (R)”.

  When the plastic substrate (I) is a multi-layer film, the structure of the laminate is (M) / (R) / (II), (R) / (M) / (II), (MC ) / (R) / (II), (R) / (MC) / (II), (M) / (R) / (M) / (II), (R) / (M) / ( C) / (II), (M) / (R) / (M) / (C) / (II), (R) / (C) / (M) / (II), (R) / (C) / (M) / (C) / (II). Among these, from the viewpoint of gas barrier properties, a layer structure in which (M) and (II) are adjacent to each other is preferable. In consideration of gas barrier properties, light shielding properties, equipment for manufacturing and operability, (R) / (C) The configurations of / (M) / (II), (R) / (M) / (II), and (R) / (MC) / (II) are preferable.

  The composition ratio of the thickness of the metal compound layer (M), the resin layer (R), the colored layer (C), and the metal compound / colored layer (MC) constituting the multilayer film can be changed as necessary.

  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 gas barrier layer (II) constituting the laminate of the present invention needs to contain a polycarboxylic acid. The polycarboxylic acid in the gas barrier layer (II) can exhibit gas 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 gas barrier layer (II) becomes fragile. On the other hand, if the molecular weight is too high, the handling properties are impaired, and in some cases, the gas barrier layer (II) described later is used. The gas barrier layer (II) obtained by agglomeration in the coating liquid for forming may have a gas barrier property impaired.

  In the present invention, among the above polycarboxylic acids, polyacrylic acid and olefin-maleic acid copolymers, particularly ethylene-maleic acid copolymers (hereinafter sometimes abbreviated as EMA) are from the viewpoint of gas barrier properties. Are 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 gas barrier layer (II) preferably contains a polyalcohol. By containing the polyalcohol, the polycarboxylic acid in the gas barrier layer (II) reacts with the polyalcohol in addition to reacting with the metal compound in the plastic substrate (I), thereby improving the gas barrier property. be able to. 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 above polyalcohols may be used alone or in combination. 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.

  The polycarboxylic acid and the polyalcohol in the gas barrier layer (II) are preferably contained so that the molar ratio of OH group to COOH group (OH group / COOH group) is 0.01-20. It is more preferable to contain so that it may become 01-10, It is more preferable to contain so that it may become 0.02-5, It is most preferable to contain so that it may become 0.04-2.

  In the present invention, the gas barrier layer (II) preferably contains polyacrylamide, polymethacrylamide or polyamine. By containing these compounds, the polycarboxylic acid in the gas 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 gas barrier layer (II) becomes fragile. On the other hand, if the molecular weight is too high, handling properties are impaired, and in some cases, a gas barrier layer (II) described later is formed. Therefore, the gas barrier layer (II) obtained by agglomeration in the coating liquid may have a gas barrier property impaired.

  The mass ratio of polyamine to polycarboxylic acid (polyamine / polycarboxylic acid) in the gas 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 obtained laminate may be inferior in gas barrier properties.

  The gas barrier layer (II) in the present invention may contain a crosslinking agent. By containing a cross-linking agent, gas barrier properties can be enhanced. The content of the crosslinking agent in the gas 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 a compound having self-crosslinking property and a compound having a plurality of functional groups that react with a carboxyl group in the molecule. When the gas barrier layer (II) contains a polyalcohol, it reacts with a hydroxyl group. A compound having a plurality of functional groups in the molecule may also 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 silicon, aluminum, titanium, and zirconium, the halogen includes chlorine, iodine, bromine, and the like, and 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 gas barrier layer (II) in the present invention, as long as the gas barrier property and the adhesion to the plastic substrate (I) are not greatly impaired, a thermal stabilizer, an antioxidant, a reinforcing material, a deterioration preventing agent, a weathering agent, 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 gas barrier layer (II) laminated on the plastic substrate (I) is preferably thicker than 0.05 μm in order to sufficiently enhance the gas barrier property of the laminate, from the viewpoint of economy. Preferably it is thinner than 5.0 μm.

  The gas barrier layer (II) in the present invention can be formed by applying and drying a gas 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 gas 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 gas barrier properties of the obtained laminate. Examples thereof include inorganic substances such as sodium hydroxide and calcium hydroxide, and organic substances such as ammonia, methylamine, and diethanolamine. Ammonia is preferable because it easily volatilizes. 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 the base added is small, the coating solution may gel during coating, making it difficult to form the gas barrier layer (II) on the plastic substrate (I).

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

  After the coating liquid for forming the gas barrier layer (II) is applied to the plastic substrate (I), heat treatment may be performed immediately to form a dry film and heat treatment at the same time. Heat treatment may be performed after moisture or the like is evaporated by spraying or infrared irradiation to form a dry film. It is preferable to perform the heat treatment immediately after the coating unless there is a particular obstacle to the state of the gas barrier layer (II) and physical properties such as gas 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 gas barrier layer (II) forming coating solution. In any of the above cases, it is preferable that the plastic substrate (I) on which the gas barrier layer (II) is formed is subjected to a heat treatment for 5 minutes or less in a heated atmosphere of 100 ° C. or higher.

  When the gas barrier layer (II) contains a polycarboxylic acid and a polyalcohol, it can be affected by their ratio, presence / absence of additive components, content thereof, and the like. The heat treatment temperature cannot be generally specified, 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 sufficiently proceed, and it may be difficult to obtain a laminate having sufficient gas barrier properties, while it is too high. In addition, the gas 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 gas barrier properties. On the other hand, if it is too long, productivity decreases.

  The coating liquid for forming the gas barrier layer (II) 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. 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 gas barrier properties. The laminate subjected to hydrothermal treatment at 95 ° C. for 30 minutes is oxygen measured in an atmosphere of 20 ° C. and 65% relative humidity. the ^{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 ^{200mL / (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 laminate of the present invention can be produced by the following method.

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

  In addition, the plastic substrate (I) made of a multi-layered film is obtained by, for example, heating and melting a thermoplastic resin mixed with a metal compound and a colorant in the extruder A, and heating and melting the thermoplastic resin in the extruder B. Then, two kinds of melted resins are superposed in a die, a two-layer film is extruded from a T die, and cooled and solidified in the same manner as described above to obtain an unstretched state.

  For the obtained single-layer or multi-layer unstretched film, the gas barrier layer (II) forming coating solution is applied by the above-described method to form the gas barrier layer (II), and the tenter type simultaneous biaxial stretching machine is used. Thus, a simultaneous biaxially stretched laminate can be obtained by performing simultaneous biaxial stretching in the machine direction (MD) and the transverse direction (TD). Further, after stretching the obtained unstretched film to MD, the gas barrier layer (II) is formed by applying the gas barrier layer (II) forming coating solution by the above-described method, and then stretching the TD. A laminate that is successively 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 where the stretching process has been performed, and is 0 to 10%, preferably 2 to 6% as necessary. Alternatively, a TD relaxation process 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.

  In addition, the plastic film (I) having a multi-layer structure includes a metal compound layer (M), a resin layer (R), a colored layer (C), and a metal compound / colored layer (MC), if necessary. It may be produced by forming and stretching in the same manner as a film and laminating them via an adhesive.

  The laminated body of this invention can also be processed in the humidified atmosphere after manufacturing a laminated body for the purpose of improving gas barrier property. By the humidification treatment, the action of the metal compound of the plastic substrate (I) and the polycarboxylic acid of the gas 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.

  The laminate of the present invention can be made into various laminated films by laminating a resin layer such as a sealant.

  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.

  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. Measurement Method (1) Average Particle Size A cumulative percent value of 50% in a particle size distribution (volume distribution) curve measured with a laser particle size analyzer “Microtrac HRA” (manufactured by Nikkiso Co., Ltd.) was determined. A sample for measuring the average particle diameter was prepared by adding 50 g of isopropanol to 0.5 g of the metal compound and performing ultrasonic dispersion treatment for 3 minutes.

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

(3) Total light transmittance The total light transmittance (Tt) of the laminate was measured according to JIS K 7136 using a Nippon Denshoku haze meter (NDH 4000).

(4) Oxygen permeability After the obtained 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 measurement made by Mokon The oxygen permeability was measured using a chamber (OX-TRAN 2/20) in an atmosphere at a temperature of 20 ° C. and a relative humidity of 65%. The unit is mL / (m ² · day · MPa).

2. Raw materials The raw materials used in the following examples and comparative examples are as follows.
(1) Thermoplastic resin PA6: Polyamide 6 resin (A1030BRF, manufactured by Unitika Ltd., relative viscosity 3.0)
PET: Polyethylene terephthalate resin (UT-CBR intrinsic viscosity 0.62 manufactured by Unitika)

(2) Metal compound / MgO: Magnesium oxide (Puremag FNM-G average particle size 0.4 μm, manufactured by Tateho Chemical Co., Ltd.)
-CaCO ₃ : Calcium carbonate (Vigot 15 average particle size 0.5 μm, manufactured by Shiroishi Kogyo Co., Ltd.)
ZnO: Zinc oxide (FINEX-50 average particle size 0.02 μm, manufactured by Sakai Chemical Industry Co., Ltd.)

(3) Colorant / TiO ₂ : Titanium oxide (manufactured by Titanium Industry Co., Ltd., KRONOS titanium oxide KR-310, rutile type, average particle size 0.35 μm)
CB: carbon black (manufactured by Mitsubishi Carbon Black, HCF # 2650, average particle size 13 nm)
· _Al 2 _{O 3:} Aluminum oxide (Nippon Light Metal Co., SA32, the average particle diameter of 1.5 [mu] m)

(3) Metal compound master chip A metal compound master chip was prepared by kneading 20 parts by mass of a metal compound and 80 parts by mass of a thermoplastic resin in accordance with Examples and Comparative Examples.
In addition, about the metal compound master chip used for Example 4, 5, 14, 15 and Comparative Examples 5 and 10, it was set as the compounding ratio of 80 mass parts of magnesium oxide and 20 mass parts of polyamide 6 resin.

(4) Colorant master chip A colorant master chip was prepared by kneading 20 parts by mass of a colorant and 80 parts by mass of a thermoplastic resin according to Examples and Comparative Examples.

(5) Gas barrier layer (II) forming coating solution / coating solution A
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 A mass% EMA aqueous solution was prepared and prepared by adding polyvinyl alcohol (Poval 105, Kuraray Co., Ltd., saponification degree 98 to 99%, average polymerization degree about 500) to water, dissolving by heating, and then cooling to room temperature. A polyvinyl alcohol (PVA) aqueous solution having a solid content of 15% by mass was prepared. And the EMA aqueous solution with PVA aqueous solution is mixed so that mass ratio (solid content) of PVA and EMA may be 50/50, and coating liquid A for gas barrier layer (II) formation with a solid content of 10 mass% Got.
・ Coating fluid B
A gas barrier layer having a solid content of 15% by mass (polyvinyl alcohol (Poval 105, Kuraray Co., Ltd., saponification degree: 98 to 99%, average polymerization degree: about 500) prepared by adding to water, dissolving by heating and cooling to room temperature. II) A forming coating solution B was obtained.

Example 1
A polyamide 6 resin, a metal compound master chip, and a colorant master chip were blended and mixed so that the magnesium oxide content was 0.1 mass% and the titanium oxide content was 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, brought into close contact with a rotating drum cooled to 10 ° C., and rapidly cooled to obtain an unstretched plastic substrate (I) 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, after apply | coating the coating liquid A to the single side | surface of the unstretched film which performed the water immersion process, it 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, a relaxation rate of TD was set to 5%, heat treatment was performed at 210 ° C. for 4 seconds, and the mixture was gradually cooled to room temperature. A plastic substrate (I) having a thickness of 15 μm was formed on a gas barrier layer (II ) Was obtained.

Examples 2-10, Comparative Examples 1-4
An unstretched film in the same manner as in Example 1 except that the polyamide 6 resin, the metal compound master chip, and the colorant master chip were appropriately used so that the contents of the metal compound and the colorant described in Table 1 were obtained. And was subjected to water treatment.
Thereafter, in the same manner as in Example 1, the coating liquid described in Table 1 was applied to an unstretched film, dried, and then simultaneously biaxially stretched to obtain a laminate.
In Example 10, the polyethylene terephthalate resin (PET) was used as the thermoplastic resin, and the conditions were further changed as follows. That is, an unstretched film was produced at a cylinder temperature of 280 ° C., and the obtained unstretched film was not subjected to water immersion treatment. Moreover, the temperature in simultaneous biaxial stretching was 90 degreeC, and the temperature of heat processing was 230 degreeC.

Comparative Example 5
An unstretched polyamide base film was prepared in the same manner as in Example 1 except that the polyamide 6 resin, the metal compound master chip, and the colorant master chip were mixed so as to have the configuration of the metal-containing layer shown in Table 1. Obtained and subjected to water treatment.
Thereafter, in the same manner as in Example 1, coating solution A was applied to an unstretched film, dried, and then simultaneously biaxially stretched. However, the film broke during stretching, and a laminate could not be obtained. .

Example 11
The polyamide 6 resin, the metal compound master chip, and the colorant master chip were mixed so that the magnesium oxide content was 0.1 mass% and the titanium oxide content was 5 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 resin melted in extruder A and extruder B are overlapped in a die, and a metal compound / colored layer (MC) / resin layer (R) two-layer sheet is extruded from the T die, and the surface The film was brought into close contact with a cooling roll at a temperature of 20 ° C. to obtain an unstretched multi-layer film having a thickness of 150 μm with (M) / (R) = 50/100 μm. The obtained unstretched multilayer film was sent to a 50 ° C. hot water tank and subjected to water immersion treatment for 2 minutes.
Thereafter, in the same manner as in Example 1, the coating liquid A was applied to the surface of the metal compound layer (M) of the unstretched multilayer film, dried, and then simultaneously biaxially stretched to form a metal compound / colored layer having a thickness of 5 μm. A gas barrier layer (II) having a thickness of 0.3 μm is formed on the metal compound / colored layer (MC) of the plastic substrate (I) having a thickness of 15 μm, which is composed of (MC) and a resin layer (R) having a thickness of 10 μm. A laminated body was obtained.

Examples 12-20, Comparative Examples 6, 7, 9
An unstretched film was obtained in the same manner as in Example 11 except that a polyamide 6 resin, a metal compound master chip, and a colorant master chip were appropriately used so that the composition shown in Table 2 was obtained. did.
Thereafter, in the same manner as in Example 11, the coating liquid described in Table 1 was applied to an unstretched film, dried, and then simultaneously biaxially stretched to obtain a laminate.
In Example 20, the polyethylene terephthalate resin (PET) was used as the thermoplastic resin, and the conditions were further changed as follows. That is, an unstretched film was produced at a cylinder temperature of 280 ° C., and the obtained unstretched film was not subjected to water immersion treatment. Moreover, the temperature in simultaneous biaxial stretching was 90 degreeC, and the temperature of heat processing was 230 degreeC.

Example 21
The polyamide 6 resin and the metal compound master chip were mixed so that the content of magnesium oxide was 5% 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. Further, the polyamide 6 resin and the colorant master chip were mixed so that the content of titanium oxide was 5% by mass. This mixture was put into an extruder C and melt-extruded at 260 ° C.
Three types of resin each melted in extruders A, B, and C are stacked in a die, and a sheet having a three-layer structure of a metal compound layer (M) / colored layer (C) / resin layer (R) is formed into a T die. Then, the film was brought into close contact with a cooling roll having a surface temperature of 20 ° C. to obtain an unstretched multilayer film having a thickness of 150 μm with (M) / (C) / (R) = 50/50/50 μm.
Thereafter, in the same manner as in Example 11, the coating liquid A was applied to an unstretched film, dried, and simultaneously biaxially stretched to obtain a laminate.

Example 22, Comparative Example 8
Except for using the polyamide 6 resin, the metal compound master chip and the colorant master chip as appropriate so as to have the composition shown in Table 2, the thickness after stretching was set to the thickness shown in Table 1. In the same manner as in Example 21, an unstretched film was obtained and subjected to water immersion treatment.
Thereafter, in the same manner as in Example 11, the coating liquid A was applied to an unstretched film, dried, and simultaneously biaxially stretched to obtain a laminate.

Example 23
The polyamide 6 resin and the metal compound master chip were mixed so that the magnesium oxide content was 5% by mass, and the metal compound layer (M) in which the gas barrier layer (II) was laminated was obtained in the same manner as in Example 1. . Next, the polyamide 6 resin and the colorant master chip were mixed so that the content of titanium oxide was 5% by mass, and an unstretched film was obtained in the same manner as in Example 1.
The unstretched film was not coated, and was biaxially stretched in the same manner as in Example 1 to obtain a laminate composed of the metal compound layer (M) and the colored layer (C).
Thereafter, a PET film (product name: PET-12, manufactured by Unitika Ltd.) is laminated as a resin layer (R) on the metal compound layer side of the laminate composed of the metal compound layer (M) and the colored layer (C) to obtain a metal compound. A laminate comprising the layer (M), the colored layer (C), and the resin layer (R) was obtained.

Comparative Example 10
Except that the polyamide 6 resin, the metal compound, and the colorant master chip were mixed so that the magnesium oxide content was 80% by mass and the titanium oxide content was 10% by mass, A stretched film was obtained and immersed in water.
Thereafter, in the same manner as in Example 11, the coating liquid A was applied to an unstretched film, dried, and then simultaneously biaxially stretched to obtain a laminate, but the metal-containing layer (M) was cohesive fractured during stretching. However, a uniform film could not be obtained.

  The structure of the laminated body obtained by the Example and the comparative example and its evaluation result are shown to Table 1,2.

In all the laminates of Examples 1 to 23, the total light transmittance was 50% or less, and the oxygen transmittance was 300 mL / (m ² · day · MPa) or less.

In the laminates of Comparative Examples 1 and 6, since the metal compound was not blended in the plastic substrate (I), the oxygen permeability exceeded 300 mL / (m ² · day · MPa).
In the laminates of Comparative Examples 2, 3, 7, and 8, the colorant was not contained or the content thereof was low, so that the total light transmittance exceeded 50%.
Since the laminated bodies of Comparative Examples 4 and 9 did not contain polycarboxylic acid in the gas barrier layer (II), the oxygen permeability exceeded 300 mL / (m ² · day · MPa).

Claims (7)

A gas barrier layer (II) containing a polycarboxylic acid is laminated on a plastic substrate (I) containing 0.1 to 70% by mass of a metal compound, and the total light transmittance is 50% or less. Laminated body. The laminate according to claim 1, wherein the plastic substrate (I) is a multilayer film and contains a colorant in at least one layer. The laminate according to claim 1 or 2, wherein the thermoplastic resin constituting the plastic substrate (I) is a polyamide resin or a polyester resin. The metal which comprises a metal compound is 1 type chosen from magnesium, calcium, and zinc, The laminated body in any one of Claims 1-3 characterized by the above-mentioned. The oxygen permeability under an atmosphere of 20 ° C and 65% relative humidity after hot water treatment at 95 ° C for 30 minutes is 300 mL / (m ² · day · MPa) or less. The laminated body in any one of. The laminate according to any one of claims 1 to 5, which is simultaneously or sequentially biaxially stretched. A packaging bag comprising the laminate according to any one of claims 1 to 6.