JP2023027649A - Barrier laminate - Google Patents

Abstract

To provide a barrier laminate having excellent gas barrier properties and an improved appearance.SOLUTION: A barrier laminate has, on at least one side of a paper substrate, a first gas barrier layer, a second gas barrier layer and a heat seal layer in this order. The second gas barrier layer contains binder resin, laminar inorganic compound A with an aspect ratio of 150 or more, and inorganic compound B with an aspect ratio of 50 or less, and with an average particle size of 1 μm or less. The heat seal layer contains water-dispersible resin.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a barrier laminate using a paper substrate as a support.

Packaging materials in which gas barrier properties such as water vapor barrier properties and oxygen barrier properties are imparted to paper substrates have been conventionally used to prevent deterioration in the quality of contents in the packaging of foods, medical products, electronic parts, etc. ing.

As a method for imparting water vapor barrier properties and gas barrier properties to a paper base material, a method of laminating a synthetic resin film or metal foil having excellent gas barrier properties on the paper base material is generally used. However, materials in which a synthetic resin film or the like is laminated on a paper base material have problems from an environmental point of view because it is difficult to recycle the paper, synthetic resin, or the like after use.

Therefore, efforts have been made to develop barrier materials that do not need to be laminated with a synthetic resin film or the like. For example, Patent Literature 1 discloses a paper barrier packaging material in which a water vapor barrier layer and a gas barrier layer are provided on a paper substrate. The water vapor barrier layer contains kaolin having an average particle diameter of 5 μm or more and an aspect ratio of 10 or more in an amount of 50 to 100% by weight based on the total pigment, and the binder resin of the gas barrier layer is a polyvinyl alcohol resin.

Japanese Patent No. 5331265

In a paper barrier packaging material such as that disclosed in Patent Document 1, when producing a barrier laminate having a water vapor barrier layer and a gas barrier layer on a paper substrate, after coating and drying the water vapor barrier layer on the paper substrate, , applying and drying an oxygen barrier layer.
However, the production method as described above has problems such as deterioration in gas barrier properties and poor appearance.

The present invention has been made in view of the circumstances as described above. That is, an object of the present invention is to provide a barrier laminate having excellent gas barrier properties and improved appearance.

The present inventors have found that in a barrier laminate having a first gas barrier layer, a second gas barrier layer and a heat seal layer in this order on at least one surface of a paper substrate, the second gas barrier layer has an aspect ratio of A barrier laminate having excellent gas barrier properties and improved appearance is provided by using a layered inorganic compound of 150 or more and an inorganic compound having an aspect ratio and an average particle size of not more than specific values. I found

The present invention has been completed based on such findings. That is, the present invention has the following configurations.
[1] A barrier laminate having a first gas barrier layer, a second gas barrier layer and a heat seal layer in this order on at least one surface of a paper substrate, wherein the second gas barrier layer comprises a binder resin. and a layered inorganic compound A having an aspect ratio of 150 or more, and an inorganic compound B having an aspect ratio of 50 or less and an average particle size of 1 μm or less, and the heat seal layer contains a water-dispersible resin. Barrier laminate containing.
[2] The barrier laminate according to [1], wherein the first gas barrier layer is a water vapor barrier layer and the second gas barrier layer is an oxygen barrier layer.
[3] The barrier according to [1] or [2], wherein the binder resin contained in the second gas barrier layer is at least one selected from the group consisting of polyvinyl alcohol, modified products thereof, and polyurethane resins. sexual laminate.
[4] The binder resin contained in the second gas barrier layer contains at least one selected from the group consisting of polyvinyl alcohol and modified products thereof, and the mass ratio of the layered inorganic compound A to the inorganic compound B (A/ The barrier laminate according to any one of [1] to [3], wherein B) is 2/98 or more and 60/40 or less.
[5] The binder resin contained in the second gas barrier layer contains a polyurethane resin, and the mass ratio (A/B) of the layered inorganic compound A and the inorganic compound B is 10/90 or more and 80/20 or less. The barrier laminate according to any one of [1] to [3].
[6] The barrier laminate according to any one of [1] to [5], wherein the first gas barrier layer contains a water-suspendable polymer, a layered inorganic compound, and a cationic resin.
[7] The water-suspendable polymer contains at least one of an ethylene-acrylic copolymer, a styrene-butadiene-based copolymer, a styrene-acrylic copolymer and a biodegradable resin, [6 ].
[8] The barrier laminate according to [6] or [7], wherein the layered inorganic compound contained in the first gas barrier layer has an aspect ratio of 80 or more and a thickness of 120 nm or less.
[9] of [6] to [8], wherein the cationic resin contained in the first gas barrier layer is at least one selected from polyamine, modified polyamide, modified polyamidoamine, polyamide epichlorohydrin and polyethyleneimine; The barrier laminate according to any one of the above.
[10] The heat seal layer contains at least one resin selected from the group consisting of an ethylene/vinyl acetate copolymer, an ethylene/(meth)acrylic acid copolymer and a styrene/butadiene copolymer. , the barrier laminate according to any one of [1] to [9].
[11] The paper base material has a basis weight of 20 g/m ² or more and 500 g/m ² or less, a density of 0.5 g/cm ³ or more and 1.2 g/cm ^{3 or} less, and an Oken smoothness of The barrier laminate according to any one of [1] to [10], which is 5 seconds or more.
[12] The barrier laminate according to any one of [1] to [11], which has an oxygen permeability of 10 mL/(m ² ·day·atm) or less at 23°C and 50% RH.
[13] The barrier laminate according to any one of [1] to [12], which has a water vapor permeability of 10 g/(m ² ·day) or less at 40° C. and 90% RH.

ADVANTAGE OF THE INVENTION According to this invention, the barrier-property laminated body which generation|occurrence|production of a blister is suppressed, is excellent in water vapor|steam barrier property and oxygen barrier property, and the external appearance improved is provided.

1 is a schematic cross-sectional view showing the layer structure of a barrier laminate of the present invention; FIG.

Hereinafter, embodiments of the present invention will be specifically described. Although the constituent elements described below may be described based on representative embodiments and specific examples, the present invention is not limited to such embodiments. In the present specification, a numerical range represented by "-" means a range including the numerical values described before and after "-" as lower and upper limits. When numerical ranges are stated stepwise, the upper and lower limits of each numerical range can be combined arbitrarily. Also, in this specification, the term "gas barrier" means at least one of an oxygen barrier and a water vapor barrier.

[Barrier laminate]
The barrier laminate of this embodiment is a barrier laminate having a first gas barrier layer, a second gas barrier layer and a heat seal layer in this order on at least one surface of a paper substrate, contains a binder resin, a layered inorganic compound A having an aspect ratio of 150 or more, and an inorganic compound B having an aspect ratio of 50 or less and an average particle diameter of 1 μm or less, and the heat seal layer contains a water-dispersible resin.
According to the present embodiment, a barrier laminate with excellent gas barrier properties and improved appearance is provided. Furthermore, the present invention has the additional effects of excellent adhesion to the heat-seal layer and excellent heat-sealability. Although the mechanism that produces the effect is not clear, it is presumed as follows.
When drying the second gas barrier layer, since the first gas barrier layer has already been formed, it is difficult for the solvent component of the coating liquid for the second gas barrier layer to escape to the paper substrate side. Therefore, the solvent component of the second gas barrier layer coating liquid needs to escape as gas from the surface on which the heat seal layer is provided (hereinafter also referred to as the surface). Here, if the surface of the second gas barrier layer dries easily and the film is formed quickly, it is considered that the solvent component is difficult to escape from the surface of the second gas barrier layer, resulting in blisters. In addition, when blisters occur, not only does the appearance become poor, but the performance of the second gas barrier layer (for example, oxygen barrier properties when the second gas barrier layer is an oxygen barrier layer) is impaired, resulting in a loss of gas barrier properties. (oxygen barrier property) is also poor.
In the present embodiment, although the detailed reason is unknown, in addition to the layered inorganic compound A having an aspect ratio of 150 or more, the second gas barrier layer has an aspect ratio of 50 or less and an average particle diameter of 1 μm or less. The inclusion of a certain inorganic compound B inhibits the rapid formation of a film on the surface of the second gas barrier layer, and the addition of the inorganic compound B promotes the ease of escape of the solvent component in a gaseous state, resulting in blistering. It is considered that the appearance was improved as a result of suppressing the occurrence of In addition, since the inorganic compound B has an aspect ratio of 50 or less and an average particle size of 1 μm, it inhibits the film-forming properties during drying, but does not adversely affect the gas barrier properties after drying. It is believed that a laminate having excellent barrier properties can be obtained.
Furthermore, in the present embodiment, since the second gas barrier layer contains the inorganic compound B, the adhesion with the heat seal layer formed on the second gas barrier layer is improved due to the anchor effect, and the heat sealability is improved. It is possible to obtain a barrier laminate having excellent properties.
In addition, the effect of the present invention is not limited to the above mechanism.
Each layer constituting the barrier laminate of this embodiment will be described below.

[Paper substrate]
The paper substrate used in the present embodiment is not particularly limited as long as it is generally used paper having plant-derived wood pulp as a main component. Specific examples include bleached or unbleached kraft paper, woodfree paper, paperboard, liner paper, coated paper, single-glazed paper, glassine paper, and graphane paper. As the paper substrate, it is preferable to use paper containing pulp as a main component, which is easily dispersed in water by a mechanical disaggregation action.

The disaggregation freeness (freeness) of the paper substrate measured according to JIS P 8121:2012 is preferably 800 mL or less, more preferably 550 mL or less, from the viewpoint of improving barrier properties. Here, the disintegration freeness is the Canadian standard freeness measured by disintegrating the paper after papermaking in accordance with JIS P 8220-1:2012 in accordance with JIS P 8121:2012. It's about. A known method can be used for the method of beating the pulp in order to prepare the defibering freeness.

The sizing degree of the paper substrate is not particularly limited, but from the viewpoint of improving barrier properties, the Stockigt sizing degree according to JIS P 8122:2004 is preferably 1 second or more, more preferably 5 seconds or more. Although the upper limit of the Stockigt size degree is not particularly limited, it is, for example, 180 seconds or less. The sizing degree of the paper substrate depends on the type and content of internal sizing agents such as rosin, alkylketene dimer, alkenyl succinic anhydride, styrene/acrylic, higher fatty acid, and petroleum resin, the type of pulp, It can be controlled by smoothing processing or the like. Although the content of the internal sizing agent is not particularly limited, it is preferably in the range of about 0 to 3 parts by mass with respect to 100 parts by mass of the paper base pulp.

Known internal additives can be appropriately added to the paper substrate. Examples of internal additives include fillers such as titanium dioxide, kaolin, talc, and calcium carbonate, paper strength agents, retention aids, pH adjusters, drainage improvers, water resistance agents, softeners, antistatic agents, Antifoaming agents, slime control agents, dyes/pigments and the like can be mentioned.

In the papermaking of the paper substrate, a known wet paper machine (for example, a fourdrinier paper machine, a gap former paper machine, a cylinder paper machine, a short mesh paper machine, etc.) is appropriately selected and used. . A paper layer formed by a paper machine is transported by felt and dried by a dryer. A multi-stage cylinder dryer may be used as a pre-dryer before drying.

Further, the paper base material obtained as described above may be subjected to a surface treatment using a calendar to make the thickness and profile uniform. For calendering, a known calendering machine can be appropriately selected and used.

The basis weight of the paper substrate is not particularly limited, but is preferably 20-500 g/m ² , more preferably 30-400 g/m ² . The basis weight of the paper substrate is measured according to JIS P 8124:2011.
The density of the paper substrate is preferably 0.5 to 1.2 g/cm ³ , more preferably 0.6 to 1.0 g/cm ³ from the viewpoint of gas barrier properties. The density of the paper base is calculated from the thickness of the paper base measured in accordance with JIS P 8118:2014 and the basis weight.
The Oken smoothness of the paper substrate is preferably 5 seconds or more, more preferably 10 to 1000 seconds, from the viewpoint of the film forming properties of the coating layer. The Oken smoothness is measured according to JIS P 8155:2010.
Further, the paper substrate preferably has a 75° glossiness of 5% or more, more preferably 5 to 70%, from the viewpoint of printability. Furthermore, in a form in which the gas barrier layer and the heat seal layer are provided only on one side of the paper substrate, when printing on the other side of the paper substrate (the surface where the paper substrate is exposed), the 75 ° glossiness of the surface is , from the viewpoint of printability (printing appearance), it is preferably 15% or more, more preferably 25% or more. Moreover, glossiness is measured based on JIS P 8142:2005.

In one embodiment of the present invention, the barrier laminate preferably comprises a water vapor barrier layer and an oxygen barrier layer as gas barrier layers, the first gas barrier layer being a water vapor barrier layer and the second gas barrier layer being an oxygen barrier layer. It is preferably a barrier layer.
When the paper base material, the water vapor barrier layer, the oxygen barrier layer and the heat seal layer are laminated in this order, the water vapor barrier layer is already formed when the oxygen barrier layer is dried, so oxygen from the paper base material side Since the escape of the solvent (preferably water (vapor)) of the barrier layer coating liquid is suppressed, blisters are more likely to occur. Therefore, by configuring the oxygen barrier layer according to the present embodiment, the effect of the present invention is remarkable.
An example in which the first gas barrier layer is a water vapor barrier layer and the second gas barrier layer is an oxygen barrier layer will be described below.

[First gas barrier layer]
The first gas barrier layer is preferably a water vapor barrier layer. The water vapor barrier layer is a layer having a function of blocking permeation of water vapor, and preferably contains a water-suspendable polymer, a layered inorganic compound and a cationic resin.

(layered inorganic compound)
The form of the layered inorganic compound is tabular. A water vapor barrier layer is formed by preparing a mixed solution of a layered inorganic compound, a water-suspendable polymer and a cationic resin, and coating it on a paper substrate. In the water vapor barrier layer, the plate-shaped layered inorganic compounds are arranged in a state of being laminated almost parallel to the plane (surface) of the paper substrate. As a result, the area of the region where the layered inorganic compound does not exist is reduced in the planar direction of the paper substrate, thereby suppressing the permeation of water vapor. In addition, in the thickness direction of the paper substrate, since the plate-like layered inorganic compounds are arranged parallel to the plane of the paper substrate, water vapor in the water vapor barrier layer bypasses the layered inorganic compounds and permeates. As a result, permeation of water vapor is suppressed by the labyrinth effect. As a result, the water vapor barrier layer can exhibit excellent water vapor barrier properties.

The thickness of the layered inorganic compound is preferably 120 nm or less. The thickness of the layered inorganic compound is more preferably 100 nm or less, still more preferably 50 nm or less, and even more preferably 20 nm or less. The smaller the average thickness of the layered inorganic compound, the greater the number of laminated layers of the layered inorganic compound in the water vapor barrier layer, so that high water vapor barrier properties can be exhibited. Here, the thickness of the layered inorganic compound contained in the water vapor barrier layer is determined as follows. First, an enlarged photograph of the cross section of the water vapor barrier layer is taken using an electron microscope. At this time, the magnification is such that about 20 to 30 layered inorganic compounds are included in the screen. Next, the thickness of each layered inorganic compound in the screen is measured. Then, the average value of the obtained thicknesses is calculated to obtain the thickness of the layered inorganic compound.

The length of the layered inorganic compound is preferably 1 μm to 100 μm. When the length is 1 μm or more, the layered inorganic compound tends to be aligned parallel to the paper substrate. Further, when the length is 100 μm or less, there is little concern that part of the layered inorganic compound will protrude from the water vapor barrier layer. The length of the layered inorganic compound is more preferably 2 to 60 μm, still more preferably 3 to 30 μm. Here, the length of the layered inorganic compound contained in the water vapor barrier layer is obtained as follows. First, an enlarged photograph of the cross section of the water vapor barrier layer is taken using an electron microscope. At this time, the magnification is such that about 20 to 30 layered inorganic compounds are included in the screen. Next, the length of each layered inorganic compound in the screen is measured. Then, the average value of the obtained lengths is calculated and taken as the length of the layered inorganic compound. Note that the length of the layered inorganic compound is sometimes described in terms of particle size or average particle size.

The aspect ratio of the layered inorganic compound is preferably 80 or more. When the aspect ratio is 80 or more, it is possible to achieve a predetermined water vapor barrier property. The aspect ratio of the layered inorganic compound is more preferably 100 or more, still more preferably 200 or more, still more preferably 300 or more, and particularly preferably 500 or more. The higher the aspect ratio, the more the water vapor permeation is suppressed and the water vapor barrier properties are improved. Moreover, the amount of the layered inorganic compound added can be reduced as the aspect ratio increases. The upper limit of the aspect ratio is not particularly limited, and about 10000 or less is preferable from the viewpoint of the viscosity of the coating liquid. Here, the aspect ratio is a value obtained by dividing the average length of the layered inorganic compound obtained by the method described above, obtained by taking an enlarged photograph of the cross section of the water vapor barrier layer using an electron microscope, by its average thickness. be.

Specific examples of layered inorganic compounds include mica group, brittle mica group mica, synthetic mica (e.g., swelling mica, non-swelling mica), bentonite, kaolinite (kaolin mineral), pyrophyllite, talc, smectite. , vermiculite, chlorite, septe chlorite, serpentine, stilpnomelane, and montmorillonite.

Among the layered inorganic compounds, at least one selected from mica, bentonite, kaolin and talc is particularly preferable from the viewpoint of improving barrier properties. Examples of mica include synthetic mica, muscovite, sericite, flocopite, biotite, fluorine phlogopite (artificial mica), red mica, soda mica, vanadine mica, Examples include illite, chinmica, paragonite, and brittle mica. Bentonite includes montmorillonite. Kaolin is a clay formed by the weathering of rocks containing feldspar, and kaolinite is the main component. Talc is a mineral composed of magnesium hydroxide and silicate, also called talc.

The content of the layered inorganic compound is preferably 80% by mass or less, more preferably 60% by mass or less, even more preferably 40% by mass or less, and even more preferably 20% by mass or less, based on the total solid content of the water vapor barrier layer. . On the other hand, the content of the layered inorganic compound is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more. By increasing the aspect ratio and decreasing the thickness of the layered inorganic compound, it is possible to reduce the content of the layered inorganic compound and prevent the layered inorganic compound from falling off from the water vapor barrier layer.

The content of the layered inorganic compound is preferably 0.1 to 800 parts by mass with respect to 100 parts by mass of the water-suspendable polymer (binder) of the water vapor barrier layer. The content of the layered inorganic compound is more preferably 0.3 to 400 parts by mass, more preferably 1 to 200 parts by mass, and still more preferably 100 parts by mass of the water-suspendable polymer (binder) of the water vapor barrier layer. It is preferably 3 to 100 parts by weight, particularly preferably 5 to 50 parts by weight, most preferably 7 to 20 parts by weight. When the content of the layered inorganic compound is 0.1 part by mass or more with respect to 100 parts by mass of the water-suspendable polymer (binder) of the water vapor barrier layer, the water vapor barrier property is easily exhibited. Further, when the content of the layered inorganic compound is 800 parts by mass or less with respect to 100 parts by mass of the water-suspendable polymer (binder) of the water vapor barrier layer, part of the layered inorganic compound is less likely to be exposed from the layer surface. Therefore, the water vapor barrier property is less likely to deteriorate. Further, when the content of the layered inorganic compound is 800 parts by mass or less with respect to 100 parts by mass of the water-suspendable polymer of the water vapor barrier layer, when the first gas barrier layer is a water vapor barrier layer, the gas barrier layer The coatability of the resin is improved, and a uniform gas barrier layer is formed, so that the gas barrier property is also improved.

(cationic resin)
By adding a cationic resin to the water vapor barrier layer containing the layered inorganic compound, the water vapor barrier property is greatly improved.
Although the reason why the water vapor barrier properties are greatly improved by adding a cationic resin is not clear, the reason is as follows. Layered inorganic compounds are known to form a so-called card house structure, in which the planar portions of the flat plate form are easily charged anionically and the edge portions are cationic. there is Due to this card house structure, the aqueous dispersion of the layered inorganic compound has a very high viscosity. On the other hand, since the house-of-cards structure is destroyed by applying force such as stirring, aqueous dispersions of layered inorganic compounds exhibit thixotropic properties. Moreover, when the card house structure is destroyed, the layered inorganic compound is sterically aggregated.

When a suitable cationic resin is added to the aqueous dispersion of the layered inorganic compound, the card house structure is destroyed by the adsorption of the cationic resin on the anionic planar portion of the layered inorganic compound. As a result, the layered inorganic compound is suppressed from sterically aggregating, making it easier for the flat layered inorganic compound to stack parallel to the plane of the paper substrate, which is presumed to lead to improved water vapor barrier properties. there is

Specific examples of the cationic resin include polyamine, modified polyamide, modified polyamidoamine, polyamide epichlorohydrin, polyethyleneimine, polyalkylenepolyamine, polyamide compound, polyamidoamine/epihalohydrin or formaldehyde condensation reaction product, polyamine/epihalohydrin or formaldehyde. Condensation Reaction Products, Polyamide Polyurea/Epihalohydrin or Formaldehyde Condensation Reaction Products, Polyamine Polyurea/Epihalohydrin or Formaldehyde Condensation Reaction Products, Polyamidoamine Polyurea/Epihalohydrin or Formaldehyde Condensation Reaction Products, Polyamide Polyurea Compounds, Polyamine Polyurea compounds, polyamidoamine polyurea compounds and polyamidoamine compounds, polyvinylpyridine, amino-modified acrylamide compounds, polyvinylamine, polydiallyldimethylammonium chloride, and the like. Among these, at least one selected from polyamine, modified polyamide, modified polyamidoamine, polyamide epichlorohydrin and polyethyleneimine is preferable.

The cationic resin preferably has a surface charge of 0.1 to 10 meq/g, more preferably 0.1 to 5.0 meq/g. When the surface charge of the cationic resin is within the above range, the housed card structure can be destroyed, and the cationic resin can coexist appropriately with an anionic binder described later.

The surface charge of the cationic resin is measured by the method described below. First, a sample polymer is dissolved in water to obtain a solution with a polymer concentration of 1 ppm. Using a charge analyzer Mutek PCD-04 (manufactured by BTG), 0.001N sodium polyethylene sulfonate is added dropwise to the solution to measure the amount of charge.

The content of the cationic resin in the water vapor barrier layer may be appropriately determined according to the types of the layered inorganic compound and the water-suspendable polymer used in the water vapor barrier layer. With respect to 100 parts by mass of the inorganic compound, preferably 1 to 300 parts by mass, more preferably 1 to 250 parts by mass, still more preferably 10 to 150 parts by mass, particularly preferably 15 to 100 parts by mass, most preferably 20 to 50 parts by mass. part by mass.

The content of the cationic resin is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, with respect to 100 parts by mass of the water-suspendable polymer (binder) of the water vapor barrier layer. , more preferably 1 to 10 parts by mass.

(Water-suspendable polymer)
A water-suspendable polymer is a polymer that can be suspended in water, and when forming a coating film, it is easy to prepare a coating solution using water or an aqueous medium as a solvent. is. Therefore, the water vapor barrier layer is preferably formed by applying and drying a water-based coating liquid. As used herein, "aqueous" means containing 50% by mass or more, preferably 80% by mass or more of water (upper limit 100% by mass).
Since the water-suspendable polymer functions as a binder in forming a coating film, it is possible to form a coating film containing a layered inorganic compound or the like on a paper substrate. At least one of an ethylene-acrylic copolymer, a styrene-butadiene-based copolymer, a styrene-acrylic copolymer, and a biodegradable resin is contained as the polymer serving as the backbone of the water-suspendable polymer. is preferred, and an ethylene-acrylic copolymer is more preferred.

An ethylene-acrylic copolymer, which is a typical example of a water-suspendable polymer, will be described below. Examples of acrylic monomers constituting the ethylene-acrylic copolymer include (meth)acrylic acid and alkyl esters thereof.
The number of carbon atoms in the alkyl group of the ester portion of the (meth)acrylic acid alkyl ester is preferably 1 or more and 8 or less, more preferably 1 or more and 6 or less, and still more preferably 1 or more and 4 or less.
Here, (meth)acrylic acid means methacrylic acid and acrylic acid.
The acrylic monomer constituting the ethylene-acrylic copolymer may be of one type or two or more types in combination.

The ethylene-acrylic copolymer is a copolymer obtained by emulsion polymerization of ethylene and the above acrylic monomer. As acrylic monomers, acrylic acid, methacrylic acid, and the like are suitable. Ethylene-acrylic copolymers include ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer. polymer, ethylene/ethyl methacrylate copolymer, ethylene/butyl acrylate copolymer, and ethylene/butyl methacrylate copolymer, preferably one or more, ethylene/acrylic acid copolymer, Ethylene/methacrylic acid copolymer is more preferred. A small amount of monomers comprising other compounds copolymerizable with ethylene and acrylic monomers may be copolymerized in the copolymer.

Specific examples of the ethylene-acrylic copolymer include, for example, an aqueous dispersion of an ethylene-acrylic acid copolymer ammonium salt, Zaixen (registered trademark) AC (manufactured by Sumitomo Seika Co., Ltd., copolymerization ratio of acrylic acid : 20 mol %) and can be easily obtained and used.
In addition, as the ethylene-acrylic copolymer, MP4983R, MP4990R and MICHEM FLEX HS1279 manufactured by Michaelman Japan LLC. S, Zaixen (registered trademark) A manufactured by Sumitomo Seika Co., Ltd., Chemipearl S series manufactured by Mitsui Chemicals, Inc., and the like.

The ethylene-acrylic copolymer preferably has a content of acrylic monomer units of 1 to 50 mol %, more preferably 10 to 30 mol %. When the content of acrylic monomer units is within this range, excellent dispersibility is achieved.

The weight-average molecular weight of the ethylene-acrylic copolymer is preferably 10,000 to 10,000,000, more preferably 50,000 to 5,000,000, from the viewpoint of the viscosity of the coating liquid and the strength of the coating film.

Although the content of the ethylene-acrylic copolymer is not particularly limited, it is preferably 20% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more, in the total solid content of the water vapor barrier layer. It is preferably 70% by mass or more, most preferably 80% by mass or more.

(Styrene-butadiene copolymer)
Styrene-butadiene-based copolymers include styrene-based compounds such as styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene, and chlorostyrene, 1,3-butadiene, isoprene (2-methyl-1,3 -butadiene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and other butadiene-based compounds, and other compounds copolymerizable with these, obtained by emulsion polymerization. It is a copolymer. Styrene is suitable as the styrene compound, and 1,3-butadiene is suitable as the butadiene compound.

(Styrene-acrylic copolymer)
Styrene-acrylic copolymers are composed of styrene compounds such as styrene, α-methylstyrene, vinyl toluene, pt-butylstyrene, chlorostyrene, acrylic acid, methacrylic acid, (meth)acrylic acid esters, (meth) ) Emulsion polymerization of monomers composed of acrylic compounds such as acrylamidopropanesulfonic acid, sodium sulfoalkyl (meth)acrylate (where the number of carbon atoms in the alkyl group is 2 or more and 3 or less) and other compounds copolymerizable with these It is a copolymer obtained by Styrene is suitable as the styrene compound, and acrylic acid, methacrylic acid, acrylic acid ester, and methacrylic acid ester are suitable as the acrylic compound.

(biodegradable resin)
Specific examples of biodegradable resins are not particularly limited, and include polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), 3-hydroxy Examples include butanoic acid/3-hydroxyhexanoic acid copolymer (PHBH). Among these, PBS and PLA are preferred, and PLA is more preferred. Compared to packaging materials using thermoplastic resins, packaging materials using paper substrates have the advantage of reducing the burden on the environment. By using a resin, the environmental load can be further reduced.

The water-suspendable polymer (binder) in the water vapor barrier layer is preferably anionic. Since the binder is anionic, the water vapor barrier property is further improved. As described above, the planar portion of the layered inorganic compound is anionic, but the surface becomes cationic when the cationic resin is adsorbed. Therefore, the affinity with the anionic binder is enhanced.
When the skeleton of the water-suspendable polymer does not have an anionic group, it is preferable to introduce an acid group by copolymerizing with a monomer having an acid group such as a carboxyl group.

The weight-average molecular weight of the water-suspendable polymer is preferably 10,000 to 10,000,000, more preferably 100,000 to 5,000,000, from the viewpoint of the viscosity of the coating liquid and the strength of the coating film.
The content of the water-suspendable polymer in the water vapor barrier layer is not particularly limited, but is preferably 20% by mass or more, more preferably 50% by weight or more, and still more preferably 60% by weight, based on the total solid content of the water vapor barrier layer. Above, more preferably 70% by mass or more, particularly preferably 80% by mass or more.

In addition to the water-suspendable polymer, layered inorganic compound, and cationic resin, the water vapor barrier layer may contain dispersants, surfactants, antifoaming agents, wetting agents, dyes, color-adjusting agents, and thickening agents as needed. It is possible to add thickeners and the like.

The thickness of the water vapor barrier layer is preferably 1 to 30 μm, more preferably 3 to 20 μm, from the viewpoint of water vapor barrier properties and the viewpoint of thinning the film thickness as a whole. From the same point of view, the coating amount of the water vapor barrier layer is preferably 1 to 30 g/m ² , more preferably 3 to 20 g/m ² as solid content.

[Second gas barrier layer]
The second gas barrier layer is preferably an oxygen barrier layer mainly having a function of blocking permeation of oxygen gas.
The second gas barrier layer contains a binder resin, a layered inorganic compound A having an aspect ratio of 150 or more, and an inorganic compound B having an aspect ratio of 50 or less and an average particle diameter of 1 μm or less.

(binder resin)
Binder resins contained in the oxygen barrier layer include, for example, polyvinyl alcohol, modified polyvinyl alcohol, starch and its derivatives, cellulose derivatives, polyvinylpyrrolidone, polyurethane resins, polyacrylic acid and its salts, casein, and polyethyleneimine. .
Among these, the binder resin contained in the oxygen barrier layer is preferably at least one selected from the group consisting of polyvinyl alcohol, modified products thereof, and polyurethane resins.

<Polyvinyl alcohol or modified product thereof (modified polyvinyl alcohol)>
Polyvinyl alcohol or its denatured product (denatured polyvinyl alcohol) is preferable because of its superior gas barrier properties. Polyvinyl alcohol includes fully saponified or partially saponified polyvinyl alcohol. Examples of modified polyvinyl alcohol include ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, and the like. As the modified polyvinyl alcohol, ethylene-modified polyvinyl alcohol is preferable from the viewpoint of oxygen barrier properties.
The degree of saponification of polyvinyl alcohol and its modified products is preferably high from the viewpoint of increasing the coating strength and from the viewpoint of reducing hygroscopicity. Specifically, the degree of saponification is preferably 90% or more, more preferably 93 % or more, more preferably 95% or more, still more preferably 97% or more (upper limit 100%). In this specification, the degree of saponification shall adopt the value measured by JISK6726:1994.
As polyvinyl alcohol and modified products thereof, either synthetic products or commercially available products may be used. Commercially available products include Exeval AQ-4104, RS-2117 and HR-3010 manufactured by Kuraray Co., Ltd.

<Polyurethane resin>
The polyurethane-based resin contained in the oxygen barrier layer is not particularly limited, and for example, it is more preferably one that can be prepared as one or more selected from the group consisting of polyurethane-based resin dispersions and emulsions, and polyurethane-based resins. It is more preferable that it can be prepared into a dispersion or emulsion, and it is particularly preferable that it can be prepared into a polyurethane-based resin dispersion.

The polyurethane resin contained in the oxygen barrier layer preferably contains at least one selected from the group consisting of structural units derived from meta-xylylene diisocyanate and structural units derived from hydrogenated meta-xylylene diisocyanate. When the polyurethane resin contains at least one of structural units derived from meta-xylylene diisocyanate and structural units derived from hydrogenated meta-xylylene diisocyanate, the structural units derived from meta-xylylene diisocyanate and The total content of structural units derived from hydrogenated meta-xylylene diisocyanate is preferably 50 mol % or more. Such a polyurethane-based resin exhibits high cohesive strength due to hydrogen bonding and, in the case of having constitutional units derived from meta-xylylene diisocyanate, the stacking effect between xylylene groups, and thus has excellent gas barrier properties. The above content can be identified using a known analytical technique such as ¹ H-NMR.

-Oxygen permeability-
The polyurethane-based resin contained in the oxygen barrier layer preferably has an oxygen permeability of 100 mL/(m ² ·day·atm) or less at 23° C. and 50% RH when converted into a sheet with a thickness of 25 μm, more preferably It is 50 mL/(m ² ·day·atm) or less, more preferably 25 mL/(m ² ·day·atm) or less, still more preferably 10 mL/(m ² ·day·atm) or less. In this specification, the oxygen permeability is measured using an oxygen permeability measuring device (OX-TRAN2/22 manufactured by MOCON) under conditions of 23° C. and 50% RH.

-Glass-transition temperature-
The glass transition temperature of the polyurethane-based resin contained in the oxygen barrier layer is preferably 150° C. or lower, more preferably 140° C. or lower, more preferably 135° C., from the viewpoint of improving the strength of the oxygen barrier layer and preventing blocking. The following are particularly preferred. Although the lower limit of the glass transition temperature of the polyurethane-based resin is not particularly limited, it is preferably 50°C or higher. The glass transition temperature is measured according to JIS K 7122:2012.

As the polyurethane-based resin, a synthetic product may be used, and examples thereof include polyurethane-based resins described in International Publication No. 2015/016069.
As the polyurethane-based resin, commercially available products may be used. )” and the like, specifically, Takelac WPB-341 is exemplified. Other commercially available products include "HPU W-003" (hydroxyl value: 235 mgKOH/g) manufactured by Dainichiseika Kogyo Co., Ltd.

The content of the binder resin is preferably 10 to 95% by mass, more preferably 20 to 90% by mass, still more preferably 30 to 85% by mass, based on the total solid content of the gas barrier layer.

(Layered inorganic compound A)
The oxygen barrier layer contains a layered inorganic compound A having an aspect ratio of 150 or more.
When the oxygen barrier layer contains the layered inorganic compound A, gas barrier properties, particularly oxygen barrier properties are improved, which is preferable.
The aspect ratio of the layered inorganic compound A is 150 or more, preferably 200 or more, more preferably 300 or more, and still more preferably 500 or more. The larger the aspect ratio, the more the permeation of oxygen is suppressed and the oxygen barrier property is improved. Moreover, the amount of the layered inorganic compound added can be reduced as the aspect ratio increases. The upper limit of the aspect ratio is not particularly limited, and about 10000 or less is preferable from the viewpoint of the viscosity of the coating liquid. Here, the aspect ratio refers to the average length of the layered inorganic compound A obtained by the above-described method in the first gas barrier layer obtained by taking an enlarged photograph of the cross section of the second gas barrier layer using an electron microscope. It is the value divided by the average thickness.

The thickness of the layered inorganic compound A is preferably 120 nm or less. The thickness of the layered inorganic compound is more preferably 100 nm or less, still more preferably 50 nm or less, and particularly preferably 20 nm or less. The thickness of the layered inorganic compound A is measured in the same manner as the thickness of the layered compound in the first barrier layer.

The length of the layered inorganic compound A is preferably 1 μm to 100 μm. When the length is 1 μm or more, the layered inorganic compound A tends to be aligned parallel to the paper substrate. Further, when the length is 100 μm or less, there is little concern that part of the layered inorganic compound A protrudes from the oxygen barrier layer. The length of the layered inorganic compound A is more preferably 2 to 60 μm, still more preferably 3 to 30 μm. Here, the length of the layered inorganic compound A contained in the oxygen barrier layer is measured in the same manner as the length of the layered compound in the first barrier layer. In addition, the length of the layered inorganic compound A may be described in terms of particle size or average particle size.

Specific examples of the layered inorganic compound A include mica group, brittle mica group mica, synthetic mica (e.g., swelling mica, non-swelling mica), bentonite, kaolinite (kaolin mineral), pyrophyllite, talc, Smectite, vermiculite, chlorite, septe chlorite, serpentine, stilpnomelane, montmorillonite, and the like.

Among the layered inorganic compounds A, at least one selected from mica, bentonite, kaolin and talc is particularly preferable from the viewpoint of improving barrier properties. Examples of mica include synthetic mica, muscovite, sericite, flocopite, biotite, fluorine phlogopite (artificial mica), red mica, soda mica, vanadine mica, Examples include illite, chinmica, paragonite, and brittle mica. Bentonite includes montmorillonite. Kaolin is a clay formed by the weathering of rocks containing feldspar, and kaolinite is the main component. Talc is a mineral composed of magnesium hydroxide and silicate, also called talc.

The content of the layered inorganic compound A is preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 30% by mass or less, and even more preferably 20% by mass or less, based on the total solid content of the oxygen barrier layer. Particularly preferably, it is 18% by mass or less. On the other hand, the content of the layered inorganic compound is preferably 1% by mass or more, more preferably 2% by mass or more, and still more preferably 3% by mass or more. By increasing the aspect ratio and decreasing the thickness of the layered inorganic compound A, it is possible to reduce the content of the layered inorganic compound, and to prevent the layered inorganic compound A from falling off from the oxygen barrier layer.

The content of the layered inorganic compound A is preferably 0.1 to 800 parts by mass with respect to 100 parts by mass of the binder resin of the oxygen barrier layer. The content of the layered inorganic compound A is more preferably 0.3 to 400 parts by mass, still more preferably 1 to 200 parts by mass, and even more preferably 3 to 100 parts by mass with respect to 100 parts by mass of the binder resin of the oxygen barrier layer. parts, particularly preferably 5 to 50 parts by weight, most preferably 7 to 25 parts by weight. When the content of the layered inorganic compound A is 0.1 parts by mass or more with respect to 100 parts by mass of the binder resin of the oxygen barrier layer, the oxygen barrier property is easily exhibited. Further, when the content of the layered inorganic compound A is 800 parts by mass or less with respect to 100 parts by mass of the binder resin of the oxygen barrier layer, a part of the layered inorganic compound A becomes difficult to be exposed from the layer surface. less likely to decline. Further, when the content of the layered inorganic compound A is 800 parts by mass or less with respect to 100 parts by mass of the binder resin of the oxygen barrier layer, when the second gas barrier layer is the oxygen barrier layer, the coating of the heat seal layer is Workability is improved and a uniform heat-seal layer is formed, resulting in improved gas barrier properties.

(Inorganic compound B)
The second gas barrier layer has an aspect ratio of 50 or less and an inorganic compound B having an average particle size of 1 μm or less. As described above, the inclusion of the inorganic compound B inhibits the rapid formation of the second gas barrier layer and suppresses the formation of blisters. In addition, since the second gas barrier layer contains the inorganic compound B, the adhesion between the second gas barrier layer and the heat seal layer is improved.

The aspect ratio of the inorganic compound B is 50 or less, preferably 45 or less, more preferably 40 or less, and still more preferably 35, from the viewpoint of suppressing the formation of blisters and improving the adhesion with the heat seal layer. It is below. The lower limit is not particularly limited as long as it is 1 or more, but from the viewpoint of gas barrier properties, it is preferably 3 or more, more preferably 10 or more, and still more preferably 20 or more.

The average particle size of the inorganic compound B is 1 μm or less, preferably 0.8 μm or less, more preferably 0.6 μm or less, from the viewpoint of suppressing the formation of blisters and improving the adhesion to the heat seal layer. , more preferably 0.4 μm, still more preferably 0.3 μm or less, and from the same viewpoint, preferably 0.05 μm or more, more preferably 0.10 μm or more, still more preferably 0.15 μm or more More preferably, it is 0.20 μm or more.
The average particle diameter of the inorganic compound B is measured in the same manner as the length of the layered compound in the first gas barrier layer.

The inorganic compound B is not particularly limited as long as it has the aspect ratio and average particle diameter described above, and various inorganic compounds used in conventional coating layers are exemplified. Specifically, various kaolins such as kaolin, calcined kaolin, structured kaolin and delaminated kaolin, talc, ground calcium carbonate (ground calcium carbonate), light calcium carbonate (synthetic calcium carbonate), calcium carbonate and other hydrophilic composite synthetic pigments with organic compounds, satin white, lithopone, titanium dioxide, silica, barium sulfate, calcium sulfate, alumina, aluminum hydroxide, zinc oxide, magnesium carbonate, silicates, colloidal silica, and the like.
Among these, kaolin is preferable from the viewpoint of suppressing the generation of blisters and the viewpoint of improving adhesion to the heat seal layer. The inorganic compound B may be used individually by 1 type, and may use 2 or more types together.

The content of the inorganic compound B in the second gas barrier layer is preferably 1% by mass or more, more preferably 3% by mass or more, from the viewpoint of suppressing blistering and improving the adhesion with the heat seal layer. It is preferably 5% by mass or more, still more preferably 10% by mass or more, still more preferably 15% by mass or more, and from the viewpoint of gas barrier properties (for example, oxygen barrier properties), preferably 90% by mass or less, more preferably is 70% by mass or less, more preferably 65% by mass or less, and even more preferably 60% by mass or less.

The content of the inorganic compound B in the second gas barrier layer is preferably 1 part by mass or more with respect to 100 parts by mass of the binder resin from the viewpoint of suppressing blistering and improving the adhesion with the heat seal layer. , more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, still more preferably 8 parts by mass or more, particularly preferably 20 parts by mass or more, and from the viewpoint of gas barrier properties (for example, oxygen barrier properties), It is preferably 500 parts by mass or less, more preferably 300 parts by mass or less, still more preferably 250 parts by mass or less, even more preferably 200 parts by mass or less, and particularly preferably 150 parts by mass or less.

The mass ratio (A/B) of the layered inorganic compound A and the inorganic compound B in the second gas barrier layer is preferably 2/98 or more, more preferably 4/96 or more, still more preferably 6/94 or more, and more preferably 6/94 or more. More preferably 7/93 or more, preferably 80/20 or less, more preferably 75/25 or less, and even more preferably 70/30 or less. When the above ratio is small, blistering tends to be suppressed, and when the above ratio is large, gas barrier properties (for example, oxygen barrier properties) tend to be excellent.
The preferable range of the mass ratio (A/B) of the layered inorganic compound A and the inorganic compound varies depending on the type of the binder resin. Although the reason for this is not clear, it is believed that it is preferable to increase the amount of the inorganic compound B in the case of a binder resin that facilitates film formation on the surface.

When the binder resin contained in the second gas barrier layer contains at least one selected from the group consisting of polyvinyl alcohol and modified products thereof, the mass ratio (A/B) between the layered inorganic compound A and the inorganic compound B is From the viewpoint of suppressing blistering and from the viewpoint of oxygen barrier properties, it is preferably 2/98 or more, more preferably 4/96 or more, still more preferably 6/94 or more, and even more preferably 7/93 or more, And it is preferably 60/40 or less, more preferably 45/55 or less, still more preferably 30/70 or less, and even more preferably 15/85 or less.
In addition, since polyvinyl alcohol and its modified products have a faster film formation speed than the polyurethane resin described later, the amount of the inorganic compound B can be increased compared to the case where the polyurethane resin is used as the binder resin. preferable.

When the binder resin contained in the second gas barrier layer contains a polyurethane-based resin, the mass ratio (A/B) of the layered inorganic compound A and the inorganic compound B is determined from the viewpoint of suppressing blistering and oxygen barrier properties. From the viewpoint of the /30 or less, more preferably 60/40 or less, and even more preferably 50/50 or less.

In addition to the binder resin, the layered inorganic compound A, and the inorganic compound B, the oxygen barrier layer contains a pigment, a dispersant, a surfactant, an antifoaming agent, a wetting agent, a dye, a tint modifier, and a thickening agent as needed. etc. can be added.

The thickness of the oxygen barrier layer is preferably 0.1-10 μm, more preferably 0.5-5 μm.
The coating amount of the oxygen barrier layer is preferably 0.1 to 10 g/m ² , more preferably 0.5 to 5 g/m ² as solid content.

[Heat seal layer]
In the present invention, the barrier laminate has a heat seal layer on the second gas barrier layer, and the heat seal layer contains a water-dispersible resin.
(Water-dispersible resin)
The water-dispersible resin is not particularly limited as long as it is a water-dispersible resin and can impart heat-sealing properties. Further, the water-dispersible resin may be a dispersion-type water-dispersible resin or an emulsion-type water-dispersible resin. One type of water-dispersible resin may be used alone, or two or more types may be used in combination.
In the barrier laminate of the present invention, since the heat seal layer contains a water-dispersible resin binder, the heat seal layer can be coated using a water-based coating liquid. It is preferable because the problem of volatile organic compounds) is suppressed.
Moreover, since the second gas barrier layer contains the inorganic compound B, the adhesion between the second gas barrier layer and the heat seal layer is excellent.

The polymer that forms the skeleton of the water-dispersible resin is not particularly limited, but polyolefin resins (polyethylene, polypropylene, etc.), ethylene/vinyl acetate copolymers, vinyl chloride resins, styrene resins, styrene/butadiene copolymers. coalescence, styrene/unsaturated carboxylic acid copolymer (e.g., styrene/(meth)acrylic acid copolymer), styrene/acrylic copolymer (e.g., styrene/(meth)acrylate copolymer), Acrylic resin obtained from at least one monomer selected from the group consisting of (meth)acrylic acid and (meth)acrylic ester, acrylonitrile/styrene copolymer, acrylonitrile/butadiene copolymer, ABS Resin, AAS-based resin, AES-based resin, vinylidene chloride-based resin, polyurethane-based resin, poly-4-methylpentene-1 resin, polybutene-1 resin, vinylidene fluoride-based resin, vinyl fluoride-based resin, fluorine-based resin, Polycarbonate resin, polyamide resin, acetal resin, polyphenylene oxide resin, polyester resin (polyethylene terephthalate, polybutylene terephthalate, etc.), polyphenylene sulfide resin, polyimide resin, polysulfone resin, polyethersulfone resin, poly Arylate resin, olefin/unsaturated carboxylic acid copolymer (ethylene/acrylic acid copolymer, ethylene/methacrylic acid copolymer), biodegradable resin (polylactic acid, polybutylene succinate, polybutylene succinate adipate , polybutylene adipate terephthalate, 3-hydroxybutanoic acid/3-hydroxyhexanoic acid copolymer), modified products thereof, and the like. These may be used individually by 1 type, and may use 2 or more types together.
Among these, the water-dispersible resin is preferably a polyolefin resin, an ethylene copolymer, or a styrene/butadiene copolymer from the viewpoint of heat sealability and adhesion.
Polyethylene and polypropylene are preferable as the polyolefin resin.
Examples of ethylene copolymers include ethylene/vinyl acetate copolymers, ethylene/aliphatic unsaturated carboxylic acid copolymers, and ethylene/aliphatic unsaturated carboxylic acid ester copolymers. Copolymers and ethylene/aliphatic unsaturated carboxylic acid copolymers are preferred.
The water-dispersible resin is more preferably an ethylene copolymer, a styrene/butadiene copolymer, an ethylene/vinyl acetate copolymer, an ethylene/aliphatic unsaturated carboxylic acid copolymer, a styrene/butadiene copolymer. Polymers are more preferred, ethylene/vinyl acetate copolymers and ethylene/aliphatic unsaturated carboxylic acid copolymers are even more preferred, and ethylene/aliphatic unsaturated carboxylic acid copolymers are particularly preferred.

<Styrene-butadiene-based copolymer>
Styrene-butadiene-based copolymers include styrene-based compounds such as styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene, and chlorostyrene, 1,3-butadiene, isoprene (2-methyl-1,3 -butadiene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and other butadiene-based compounds, and other compounds copolymerizable with these, obtained by emulsion polymerization. It is a copolymer. Styrene is suitable as the styrene compound, and 1,3-butadiene is suitable as the butadiene compound.

<Ethylene/vinyl acetate copolymer>
The ethylene/vinyl acetate copolymer is a copolymer obtained by copolymerizing at least ethylene and vinyl acetate, and optionally other monomers may be further copolymerized. The content of structural units derived from other monomers is preferably 30% by mass or less, more preferably 10% by mass or less, still more preferably 3% by mass or less, and even more preferably 1% by mass or less of the total copolymer. be.
In the ethylene/vinyl acetate copolymer, the proportion of ethylene in the total monomers constituting the copolymer is preferably 5% by mass or more, more preferably 10% by mass or more, from the viewpoint of heat seal strength, and , preferably 40% by mass or less, more preferably 30% by mass or less.
Further, the glass transition temperature of the ethylene/vinyl acetate copolymer is preferably 30° C. or lower, more preferably 20° C. or lower, still more preferably 10° C. or lower, and preferably -30° C. or higher, more preferably - It is 20°C or higher, more preferably -10°C or higher.

As the ethylene/vinyl acetate copolymer, either a synthetic product or a commercial product may be used. S-400HQ, S-401HQ, S-408HQE, S-450HQ, S-455HQ, S-456HQ, S-460HQ, S-467HQ, S-470HQ, S-480HQ, S-510HQ, S-520HQ, S- 752, S-755, Showa Denko Polysol AD-2, AD-5, AD-6, AD-10, AD-11, AD-14, AD-56, AD-70, AD-92, Japan Aquatex EC1200, EC1400, EC1700, EC1800, MC3800 manufactured by Coating Resin Co., Ltd., and the like.

<Ethylene/aliphatic unsaturated carboxylic acid copolymer>
Examples of the ethylene/aliphatic unsaturated carboxylic acid copolymers include ethylene/acrylic acid copolymers and ethylene/methacrylic acid copolymers.
The ethylene/acrylic acid copolymer and the ethylene/methacrylic acid copolymer may be blended in the heat seal layer as an ionomer. That is, at least when producing the heat seal layer, it is preferable to use an ionomer as a raw material, and after production, the heat seal layer is an ethylene-acrylic acid copolymer or an ethylene-methacrylic acid copolymer in the form of an ionomer. It does not have to contain coalescence.
Here, ionomer is a general term for synthetic resins that use the cohesive force of cations to aggregate polymers. All aggregated synthetic resins correspond to ionomers.
Examples of cations include metal ions, ammonium ions (NH ₄ ⁺ ), and organic ammonium ions.
Examples of metal ions include alkali metal ions such as lithium ions (Li ⁺ ), sodium ions (Na ⁺ ) and potassium ions (K ⁺ ); alkaline earth metal ions such as magnesium ions (Mg ²⁺ ) and calcium ions (Ca ²⁺ ); ions, zinc ions (Zn ²⁺ ), copper ions (Cu ²⁺ ) and other transition metal ions, and the like. Among these, the sodium ion is preferable as the metal ion from the viewpoint of availability and the like.
The ethylene/aliphatic unsaturated carboxylic acid copolymer is preferably an ethylene/(meth)acrylic acid copolymer ionomer, a metal salt of an ethylene/methacrylic acid copolymer, a metal salt of an ethylene/acrylic acid copolymer It is more preferably a salt, an ammonium salt of an ethylene/acrylic acid copolymer, more preferably a metal salt of an ethylene/acrylic acid copolymer, an ammonium salt of an ethylene/acrylic acid copolymer, and an ethylene/acrylic acid copolymer. Ammonium salts of acid copolymers are even more preferred.

The copolymerization ratio of (meth)acrylic acid in the ethylene/(meth)acrylic acid copolymer is preferably 1 mol % or more, more preferably 10 mol % or more, and preferably 50 mol, from the viewpoint of heat sealability. % or less, more preferably 30 mol % or less.

As the ethylene/(meth)acrylic acid copolymer, either a synthetic product or a commercial product may be used. Commercial products include MP4983R, MP4990R and MICHEM FLEX HS1279. S, Zaixen (registered trademark) A manufactured by Sumitomo Seika Co., Ltd., Zaixen (registered trademark) AC, Chemipearl S series manufactured by Mitsui Chemicals, Inc., and the like.

<Ethylene/aliphatic unsaturated carboxylic acid ester copolymer>
Examples of the ethylene/unsaturated aliphatic carboxylic acid ester copolymer include ethylene/acrylic acid ester copolymers and ethylene/methacrylic acid ester copolymers. As acrylic acid esters and methacrylic acid esters, esters with aliphatic alcohols having 1 to 8 carbon atoms such as methanol and ethanol are preferably used. Among the ethylene/aliphatic unsaturated carboxylic acid ester copolymers, ethylene/methyl acrylate copolymer, ethylene/ethyl acrylate copolymer, or ethylene/methyl methacrylate copolymer is preferable from the viewpoint of versatility. .

The ethylene copolymer may be a multicomponent copolymer obtained by copolymerizing three or more monomers. Examples of the multicomponent copolymer include copolymers obtained by copolymerizing at least three types of monomers selected from ethylene, aliphatic unsaturated carboxylic acid esters, and acid anhydrides.

Among these, ethylene/unsaturated aliphatic carboxylic acid copolymers are preferred as ethylene copolymers. An ethylene/unsaturated carboxylic acid copolymer is preferable because it has excellent heat-sealing properties.
The content of the water-dispersible resin binder in the solid content of the heat seal layer is preferably 50% by mass or more, more preferably 55% by mass or more, and preferably 100% by mass or less.

In addition to the above water-dispersible resin, the heat seal layer may optionally contain pigments, silane coupling agents, lubricants, dispersants, surfactants, antifoaming agents, dyes, color modifiers, thickeners, etc. can be added.

The thickness of the heat seal layer is preferably 0.1-10 μm, more preferably 0.5-5 μm. The coating amount of the heat seal layer is preferably 0.1 to 10 g/m ² , more preferably 0.5 to 5 g/m ² as a solid content.

As described above, it is preferable to use the first gas barrier layer as the water vapor barrier layer and the second gas barrier layer as the oxygen barrier layer. can also be used as the water vapor barrier layer.
In this case, for example, the first gas barrier layer comprises a binder resin and a layered inorganic compound A, and the second gas barrier layer comprises a layered inorganic compound, a cationic resin, a water-suspendable polymer, and an inorganic A layered inorganic compound A having an aspect ratio of 150 or more is used as the layered inorganic compound that contains the compound B and is contained in the water vapor barrier layer, which is the second gas barrier layer.

[Barrier laminate]
FIG. 1 is a schematic cross-sectional view showing the layer structure of a barrier laminate 10 of the present invention. A first gas barrier layer 2 , a second gas barrier layer 3 and a heat seal layer 4 are present in this order on one side of a paper base material 1 . Preferably, the first gas barrier layer 2 is a water vapor barrier layer and the second gas barrier layer is an oxygen barrier layer.

The barrier laminate of this embodiment has excellent water vapor barrier properties and oxygen barrier properties.
Specifically, water vapor permeability at 40° C. and 90% RH is preferably 20 g/(m ² ·day) or less, more preferably 10 g/(m ² ·day) or less, still more preferably 5 g/(m 2 ·day) or less. (m ² ·day) or less, more preferably 4 g/(m ² ·day) or less.

Specifically, the oxygen barrier property is preferably 10 mL/(m ² ·day·atm) or less, more preferably 6 mL/(m ² ·day·atm) or less in oxygen permeability at 23°C and 50% RH. More preferably, it is 3 mL/(m ² ·day·atm) or less.

[Method for producing barrier laminate]
The barrier laminate of this embodiment has a first gas barrier layer, a second gas barrier layer, and a heat seal layer in this order on a paper substrate.
After the first gas barrier layer coating liquid is applied onto the paper base material and dried, the second gas barrier layer forming coating liquid is applied and dried, and further, the heat seal layer coating liquid is applied and dried. It is preferable to apply the coating liquid and dry it.
In addition, as described above, the method is not limited to the method of sequentially forming the coating layers, and a simultaneous multi-layer coating method may be used. Simultaneous multi-layer coating method involves ejecting multiple types of coating liquids from separate slit-shaped nozzles to form a liquid laminate, which is then applied to a paper substrate to achieve multiple layers of coating. It is a method of forming a working film at the same time.

The solvent for the coating liquid is not particularly limited, and water or an organic solvent such as ethanol, isopropyl alcohol, methyl ethyl ketone or toluene can be used. It is more preferable to use a volatile organic solvent together as needed, and it is further preferable that the solvent of the coating liquid is water.

The solid content concentration of the coating liquid is not particularly limited, and may be appropriately selected according to the viscosity that can be applied, but from the viewpoint of facilitating drying, it is preferably 3% by mass or more, more preferably 5% by mass. Above, more preferably 10% by mass or more, preferably 90% by mass or less, more preferably 70% by mass or less, even more preferably 50% by mass or less, and even more preferably 45% by mass or less.

Examples of methods for applying the coating liquid include bar coating, blade coating, squeeze coating, air knife coating, roll coating, gravure coating, transfer coating, etc. Fountain coaters and slit die coaters are used. A coating machine such as may be used.
Coating equipment for applying a coating liquid to a paper substrate by the simultaneous multilayer coating method is a simultaneous multilayer slide curtain method or simultaneous multilayer slide bead method coating equipment that can perform the simultaneous multilayer coating method. Use

The drying equipment for drying the coating layer is not particularly limited, and known equipment can be used. Examples of drying equipment include hot air dryers, infrared dryers, gas burners, and hot plates.

The barrier laminate of the present embodiment can be suitably used as a packaging material for foods, medical products, electronic parts, etc., by taking advantage of the excellent water vapor barrier properties, gas barrier properties, and heat-sealing properties described above.

EXAMPLES The barrier laminate of the present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these. "Parts" and "%" in Examples and Comparative Examples indicate "parts by mass" and "% by mass", respectively, unless otherwise specified.

Raw materials used in Examples and Comparative Examples are as follows.
(1) Paper substrate Single gloss paper: manufactured by Oji F-Tex, blending ratio of hardwood pulp: 100% by mass, basis weight: 50 g/m ² , thickness: 60 μm, density: 0.83 g/cm ³ , sizing degree: 9 second, Oken type smoothness of one side: 499 seconds, Oken type smoothness of the other side: 15 seconds, 75° glossiness of coated surface: 7%, 75° glossiness of non-coated surface: 29%
(2) Layered inorganic compound, layered inorganic compound A
Synthetic mica: swelling mica, particle size 6.3 μm, aspect ratio about 1000, thickness about 5 nm, product name: NTO-05, manufactured by Topy Industries, Ltd., solid content 6% aqueous dispersion (3) Inorganic compound B
Kaolin: engineered kaolin, average particle size 0.26 μm, aspect ratio about 33, product name: Contour Xtreme, manufactured by Imerys (4) Inorganic compound B′ (inorganic compound for comparative example)
Kaolin: engineered kaolin, average particle size 10 μm, aspect ratio about 100, thickness about 100 nm, product name: Varisurf HX, manufactured by Imerys (4) cationic resin modified polyamide resin: solid content 53%, product name: SPI203 (50) H, manufactured by Taoka Chemical Co., Ltd., surface charge 0.4 meq / g
(5) Water-suspendable polymer Ethylene-acrylic copolymer: self-emulsifying ethylene-acrylic acid copolymer emulsion, solid content 29.2%, copolymerization ratio of acrylic acid 20 mol%, product name: Zaixen AC , Sumitomo Seika Co., Ltd. (6) Binder resin Modified polyvinyl alcohol: Ethylene-modified polyvinyl alcohol, fully saponified type (degree of saponification 98.5%), Product name: Exeval AQ-4104, Kuraray Co., Ltd. Polyurethane emulsion : Polyurethane resin, product name: Takelac WPB-341, manufactured by Mitsui Chemicals, Inc., solid content concentration 30% by mass
(7) Water-dispersible resin for heat seal layer Aqueous dispersion of ethylene/acrylic acid copolymer (manufactured by Michael Mann, product name: MICHEM FLEX HS1279.S, solid content: 42.0%)

<Example 1>
An aqueous dispersion of a layered inorganic compound (swelling mica, particle size 6.3 μm, aspect ratio about 1000, thickness about 5 nm, solid content 6%, product name: NTO-05, manufactured by Topy Industries, Ltd.), While stirring, 34.3 parts of a self-emulsifying ethylene/acrylic acid copolymer emulsion (solid content: 29.2%, product name: Zaixen AC, manufactured by Sumitomo Seika Co., Ltd.) was added and stirred. 0.9 part of modified polyamide resin (solid content: 53%, product name: SPI203(50)H, surface charge: 0.4 meq/g, manufactured by Taoka Chemical Co., Ltd.) was added thereto and stirred. Further, 0.2 part of 25% aqueous ammonia solution was added and stirred. Furthermore, diluted water was added to adjust the solid content concentration to 18%, thereby preparing a coating solution for a water vapor barrier layer, which is the first gas barrier layer.
Ethylene-modified polyvinyl alcohol (fully saponified type, product name: Exeval AQ-4104, manufactured by Kuraray Co., Ltd.) in 100 parts of an aqueous solution with a solid content of 15%, an aqueous dispersion of layered inorganic compound A (swelling mica, particle size 6 .3 μm, aspect ratio of about 1000, thickness of about 5 nm, solid content of 6%, product name: NTO-05, manufactured by Topy Industries, Ltd.) was added in 25 parts, and inorganic compound B (engineered kaolin, average particle size of 0.3 μm) was added. 26 μm, aspect ratio of about 33, product name: Contour Xtreme, manufactured by Imerys) was dispersed in water, and 2.7 parts of an aqueous dispersion having a solid content of 55% was added. A coating solution for an oxygen barrier layer (solid concentration: 10%).
Single gloss paper (manufactured by Oji F-Tex, hardwood pulp blending ratio: 100% by mass, basis weight: 50 g/m ² , thickness: 60 μm, density: 0.83 g/cm ³ , sizing degree: 9 seconds, one side Oken type smoothness: 499 seconds, Oken type smoothness of the other surface: 15 seconds), the above coating liquid for water vapor barrier layer is applied using a Meyer bar, and heated at 120 ° C. for 1 minute. It was dried to form a water vapor barrier layer (first gas barrier layer, coating weight: 5 g/m ² , thickness: 4 µm). Furthermore, on the water vapor barrier layer, the oxygen barrier layer coating solution was applied using a Meyer bar, dried at 120 ° C. for 1 minute, and the oxygen barrier layer (second gas barrier layer, coating amount: 2 g /m ² , thickness: 1 μm). Furthermore, on the oxygen barrier layer, an aqueous dispersion of ethylene-acrylic acid copolymer (manufactured by Michaelman, "MICHEM FLEX HS1279.S (trade name)", solid content: 42.0%) is applied as a heat seal layer coating material. ) was applied using a Meyer bar so that the coating amount of the heat seal layer after drying was 3 g / m ² (thickness: 3 μm), and then dried at 120 ° C. for 1 minute to form the heat seal layer. to obtain a barrier laminate.

<Example 2>
A barrier laminate was obtained in the same manner as in Example 1, except that the amount of the aqueous dispersion of engineered kaolin blended in the oxygen barrier layer coating solution was changed to 32.4 parts.

<Example 3>
A barrier laminate was obtained in the same manner as in Example 1, except that the amount of the aqueous dispersion of engineered kaolin blended in the oxygen barrier layer coating solution was changed to 54 parts.

<Example 4>
100 parts of polyurethane emulsion (solid content concentration 30% by mass, product name: Takelac WPB-341, manufactured by Mitsui Chemicals, Inc.), inorganic compound B (engineered kaolin, average particle size 0.26 μm, aspect ratio about 33, product Name: Contour Xtreme, manufactured by Imerys Co.) was dispersed in water, and 5.5 parts of an aqueous dispersion having a solid content of 55% was added and stirred. To this, an aqueous dispersion of layered inorganic compound A (swelling mica, particle size 6.3 μm, aspect ratio about 1000, thickness about 5 nm, solid content 6%, product name: NTO-05, manufactured by Topy Industries, Ltd.) 100 parts were added and stirred. Furthermore, dilution water was added so that the solid content concentration was 10% by mass to obtain a coating solution for an oxygen barrier layer, which is the second gas barrier layer. The polyurethane resin of the polyurethane emulsion had a solubility of 10 g/L or less in water at 25°C. Further, ¹ H-NMR measurement was performed on the polyurethane emulsion A, and it was found that 50 mol % or more of meta-xylylenediisocyanate-derived structural units were contained in the polyisocyanate-derived structural units. Also, the oxygen permeability at 23° C. and 50% RH when converted to a sheet with a thickness of 25 μm was 2.0 mL/(m ² ·day·atm).
A barrier laminate was obtained in the same manner as in Example 1, except that this coating liquid was used as the coating liquid for the oxygen barrier layer.

<Example 5>
A barrier laminate was obtained in the same manner as in Example 4, except that the amount of the aqueous dispersion of engineered kaolin blended in the oxygen barrier layer coating solution was changed to 16.4 parts.

<Example 6>
A barrier laminate was obtained in the same manner as in Example 4, except that the amount of the aqueous dispersion of engineered kaolin blended in the oxygen barrier layer coating solution was changed to 54.5 parts.

<Comparative Example 1>
A barrier laminate was obtained in the same manner as in Example 1, except that the aqueous dispersion of engineered kaolin, which is the inorganic compound B, was not added to the oxygen barrier layer coating solution.

<Comparative Example 2>
A barrier laminate was obtained in the same manner as in Example 4, except that the aqueous dispersion of engineered kaolin, which is the inorganic compound B, was not blended in the oxygen barrier layer coating liquid.

<Comparative Example 3>
Except that the inorganic compound B blended in the oxygen barrier layer was changed from Contour Xtreme to Varisurf HX (engineered kaolin, average particle size 10 μm, aspect ratio about 100, manufactured by Imerys), which is the inorganic compound B′ for comparison. A barrier laminate was obtained in the same manner as in Example 2.

<Comparative Example 4>
Inorganic compound B blended in the oxygen barrier layer was changed from Contour Xtreme to Varisurf HX (engineered kaolin, average particle size 10 μm, aspect ratio about 100, manufactured by Imerys), which is inorganic compound B′ for comparison. A barrier laminate was obtained in the same manner as in Example 5.

(Evaluation method)
(1) Water vapor transmission rate The water vapor transmission rate of the barrier laminate conforms to JIS Z 0208: 1976 (cup method) B method (temperature 40 ± 0.5 ° C., relative humidity 90 ± 2%). Measurements were taken with the paper substrate of the body inside. Incidentally, as a standard of water vapor permeability, if it is 10 g/(m ² ·day) or less, it is practical as a water vapor barrier layer.

(2) Oxygen Permeability Using an oxygen permeability measuring device (OX-TRAN2/22 manufactured by MOCON), measurements were made under conditions of 23° C.-50% RH and 23° C.-85% RH. As a standard of oxygen permeability, if it is 10 mL/(m ² ·day·atm) or less under the conditions of 23° C.-50% RH, it is practical as a gas barrier layer.

(3) Appearance Evaluation The barrier laminate was cut into A4 size, and the surface of the coating layer was visually observed to check for swelling due to blisters.
A: No blister B: 1 to 2 blister C: 3 or more blister

(4) Cellophane tape was sufficiently attached to the surface of the coating layer of the cellopic barrier laminate, and how it was peeled off vigorously was examined. In addition, in a barrier laminate having excellent adhesion between the first gas barrier layer, the second gas barrier layer and the heat seal layer, which are coating layers, and adhesion between the paper substrate and the coating layer, No peeling was observed, and the paper substrate was torn.
A: The paper base material was torn and peeled off over the entire surface of the cellophane tape. B: The paper base material was torn and peeled off at a portion of the cellophane tape. C: The paper base material was not torn and was peeled off from the coating layer.

(5) Heat-sealability The barrier laminates of each example were stacked so that the heat-seal layers were in contact with each other. Using a heat press tester, the laminate was heat-sealed under the conditions of 160° C., 2.0 kgf/cm ² and 1 second to produce a laminate. This laminate was cut to prepare a rectangular measurement sample having a width of 15 mm.
The resulting sample was pulled by hand and peeled off to examine how it was torn.
A: The paper substrate was torn and peeled off C: The paper substrate was not torn and peeled off from the coating layer

As is clear from Table 1, all of the barrier laminates of Examples 1 to 6 were excellent in water vapor barrier properties and oxygen barrier properties. In addition, a good appearance was obtained without occurrence of poor appearance due to the occurrence of blisters. Furthermore, the heat-sealing property was excellent, and the adhesion of the heat-sealing layer was high, and peeling of the coating layer was not confirmed in the seropic test. On the other hand, the barrier laminates of Comparative Examples 1 and 2, in which the inorganic compound B was not used, had a poor appearance due to the occurrence of blistering, and were also inferior in oxygen barrier properties. In the test, peeling of the coating layer was confirmed. In the barrier laminates of Comparative Examples 3 and 4, in which an inorganic compound having an aspect ratio of more than 50 and an average particle diameter of more than 1 μm was used as the inorganic compound B′, blistering occurred and the seropic test showed no Although peeling of the coating layer was suppressed to some extent, an increase in oxygen permeability (decrease in oxygen barrier properties) was observed as compared with Examples.

1 paper substrate 2 first gas barrier layer (for example, water vapor barrier layer)
3 Second gas barrier layer (e.g., oxygen barrier layer)
4 heat seal layer 10 barrier laminate

Claims (13)

A barrier laminate having a first gas barrier layer, a second gas barrier layer and a heat seal layer in this order on at least one surface of a paper substrate,
The second gas barrier layer contains a binder resin, a layered inorganic compound A having an aspect ratio of 150 or more, and an inorganic compound B having an aspect ratio of 50 or less and an average particle size of 1 μm or less,
The heat seal layer contains a water-dispersible resin,
Barrier laminate. 2. The barrier laminate according to claim 1, wherein the first gas barrier layer is a water vapor barrier layer and the second gas barrier layer is an oxygen barrier layer. 3. The barrier laminate according to claim 1, wherein the binder resin contained in the second gas barrier layer is at least one selected from the group consisting of polyvinyl alcohol, modified products thereof, and polyurethane resins. The binder resin contained in the second gas barrier layer contains at least one selected from the group consisting of polyvinyl alcohol and modified products thereof, and the mass ratio (A/B) of the layered inorganic compound A and the inorganic compound B is , 2/98 or more and 60/40 or less. The binder resin contained in the second gas barrier layer contains a polyurethane resin, and the mass ratio (A/B) of the layered inorganic compound A and the inorganic compound B is 10/90 or more and 80/20 or less. The barrier laminate according to any one of Items 1 to 3. The barrier laminate according to any one of Claims 1 to 5, wherein the first gas barrier layer contains a water-suspendable polymer, a layered inorganic compound, and a cationic resin. 7. The water-suspendable polymer according to claim 6, wherein the water-suspendable polymer contains at least one of an ethylene/acrylic copolymer, a styrene/butadiene copolymer, a styrene/acrylic copolymer and a biodegradable resin. barrier laminate. 8. The barrier laminate according to claim 6, wherein the layered inorganic compound contained in the first gas barrier layer has an aspect ratio of 80 or more and a thickness of 120 nm or less. The cationic resin contained in the first gas barrier layer is at least one selected from polyamine, modified polyamide, modified polyamidoamine, polyamide epichlorohydrin and polyethyleneimine, according to any one of claims 6 to 8. A barrier laminate as described. 3. The heat seal layer contains at least one resin selected from the group consisting of ethylene/vinyl acetate copolymer, ethylene/(meth)acrylic acid copolymer and styrene/butadiene copolymer. 10. The barrier laminate according to any one of 1 to 9. The paper substrate has a basis weight of 20 g/m ² or more and 500 g/m ² or less, a density of 0.5 g/cm ³ or more and 1.2 g/cm ³ or less, and an Oken smoothness of 5 seconds or more. The barrier laminate according to any one of claims 1 to 10, wherein The barrier laminate according to any one of claims 1 to 11, which has an oxygen permeability of 10 mL/(m ² ·day · atm) or less at 23°C and 50% RH. The barrier laminate according to any one of claims 1 to 12, which has a water vapor permeability of 10 g/(m ² ·day) or less at 40°C and 90% RH.

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