JP2021046626A - Barrier laminate - Google Patents

Abstract

To provide a barrier laminate excellent in a steam barrier property and a gas property, having a water resistance and excellent in economic efficiency even when the laminate is made up of a small number of layers.SOLUTION: The barrier laminate includes a paper substrate, and a resin layer and a protective layer provided in this order on at least one face of the paper substrate; the resin layer includes a water-suspensible polymer, a tabular inorganic compound having an aspect ratio of 100 or more and a cationic resin; and the protective layer has a contact angle of 50° or more to water.SELECTED DRAWING: None

Description

The present invention relates to a barrier laminate.

Conventionally, in order to impart water vapor barrier property and gas barrier property to a paper base material, a barrier laminate having a water vapor barrier layer and a gas barrier layer provided in this order on the paper base material has been known.

In Patent Document 1, in a paper barrier material in which a water vapor barrier layer and a gas barrier layer are provided in this order on a paper base material, the water vapor barrier layer contains a water vapor barrier resin and a water repellent, and the gas barrier layer. Describes a paper barrier material characterized by containing a water-soluble polymer and a surfactant.

International Publication No. 2017/170462

The paper barrier material described in Patent Document 1 is inferior in water resistance because the gas barrier layer contains a water-soluble polymer such as polyvinyl alcohol as a main component. Therefore, the paper barrier material described in Patent Document 1 is provided with a laminate layer in addition to the water vapor barrier layer and the gas barrier layer in order to ensure water resistance, and has a large number of layers and a large number of manufacturing man-hours. There was a problem.

The present invention has been made in view of the existence of the above problems, and provides a barrier laminate having excellent water vapor barrier property and gas barrier property, water resistance, and excellent economic efficiency even if the number of layers is small. The purpose is to do. In the present specification, the gas barrier property means a barrier property against gas other than water vapor, and particularly refers to a barrier property against oxygen. Further, the water vapor barrier property and the gas barrier property are also collectively referred to as a barrier property.

The present inventor provides a paper base material and a resin layer and a protective layer in this order on at least one surface of the paper base material, and the resin layer has a water-suspendable polymer and a predetermined aspect ratio. A barrier laminate containing a plate-like inorganic compound and a cationic resin and having a protective layer with a contact angle of 50 ° or more with water has excellent water vapor barrier properties and gas barrier properties even if the number of layers is small, and is water resistant. Found to have.
That is, the present invention relates to the following <1> to <11>.
<1> A barrier laminate comprising a paper base material and a resin layer and a protective layer in this order on at least one surface of the paper base material, wherein the resin layer is a water-suspendable polymer. A barrier laminate containing a plate-like inorganic compound having an aspect ratio of 100 or more and a cationic resin, and having a contact angle of the protective layer with water of 50 ° or more.
<2> The water-suspendable polymer in the resin layer is selected from the group consisting of an olefin / unsaturated carboxylic acid-based copolymer, a styrene / butadiene-based copolymer, and a styrene / acrylic-based copolymer. The barrier laminate according to <1>, which is more than a species.
<3> The barrier laminate according to <1> or <2>, wherein the plate-like inorganic compound in the resin layer is at least one selected from the group consisting of synthetic mica, bentonite, and kaolin.
<4> The barrier laminate according to any one of <1> to <3>, wherein the resin layer contains a plate-like inorganic compound in an amount of 0.1% by mass or more and 50% by mass or less.
<5> The barrier lamination according to any one of <1> to <4>, wherein the resin layer further contains 25 parts by mass or less of a water-soluble polymer with respect to 100 parts by mass of the water-suspended polymer. body.
<6> The barrier laminate according to <5>, wherein the water-soluble polymer in the resin layer is at least one selected from the group consisting of polyvinyl alcohol and modified polyvinyl alcohol.
<7> The barrier laminate according to any one of <1> to <6>, wherein the protective layer contains a water-suspendable polymer.
<8> A group in which the water-suspendable polymer in the protective layer is composed of an olefin / unsaturated carboxylic acid-based copolymer, a styrene / butadiene-based copolymer, a styrene / acrylic-based copolymer, and a biodegradable resin. The barrier laminate according to <7>, which is one or more selected from the above.
<9> The barrier laminate according to <7> or <8>, wherein the protective layer further contains 25 parts by mass or less of a water-soluble polymer with respect to 100 parts by mass of the water-suspended polymer.
<10> The barrier laminate according to any one of <1> to <9>, wherein the protective layer contains 0.1% by mass or more and 50% by mass or less of a plate-like inorganic compound.
<11> The barrier laminate according to <10>, wherein the plate-like inorganic compound in the protective layer is at least one selected from the group consisting of synthetic mica, bentonite, and kaolin.

According to the present invention, it is possible to provide a barrier laminate having excellent water vapor barrier property and gas barrier property, water resistance, and excellent economy even if the number of layers is small.

[Barrier laminate]
The barrier laminate of the present invention (hereinafter, also simply referred to as “barrier laminate”) is a barrier provided with a paper base material and a resin layer and a protective layer on at least one surface of the paper base material in this order. In a sex laminate, the resin layer contains a water-suspendable polymer, a plate-like inorganic compound having an aspect ratio of 100 or more, and a cationic resin, and the contact angle of the protective layer with water is 50 ° or more. is there.

The barrier laminate of the present invention comprises a resin layer containing a water-suspendable polymer, a plate-like inorganic compound having a predetermined aspect ratio, and a cationic resin on at least one surface of a paper substrate. It has been clarified that by providing the protective layer on the resin layer, it is possible to provide a barrier laminate having excellent water vapor barrier property and gas barrier property and water resistance even if the number of layers is small.
By providing a protective layer on the resin layer, it is possible to fill fine pores, cracks, etc. existing on the surface of the resin layer, and as a result, the plate-like inorganic compound having a high aspect ratio of the resin layer is used. It is presumed that the maze effect of increasing the moving distance of water vapor and the like is also exerted on gas, especially oxygen.

The barrier laminate of the present invention may be provided with a resin layer and a protective layer in this order on at least one surface of the paper base material, and the resin layer and the protective layer are also provided on the other surface. You may have them in order. Further, the barrier laminate of the present invention may be provided with a plurality of resin layers and protective layers in this order.

When the gas barrier laminate of the present invention is used for packaging foods, for example, it is preferable that the resin layer and the protective layer are provided in this order only on one surface of the paper base material. With such a configuration, when the barrier laminate of the present invention is heat-sealed, a bag-shaped package can be easily produced.

<Paper base material>
The paper base material used in the barrier laminate of the present invention is preferably paper that is generally used with plant-derived pulp as the main component, and more preferably wood pulp as the main component. preferable. Further, it is preferable that the paper contains pulp as a main component, which is easily dispersed in water by a mechanical dissociation action.
Specific examples thereof include bleached or unbleached kraft paper, high-quality paper, paperboard, liner paper, coated paper, single-gloss paper, glassin paper, graphan paper, etc. Among these, bleached or unbleached kraft paper and high-quality paper. , Single glossy paper is preferable.

(Canada Standard Water Separation (CSF))
The Canadian standard freshness (CSF) of the pulp constituting the paper substrate, measured in accordance with JIS P 811-2: 2012, is preferably 800 mL or less, more preferably 500 mL, from the viewpoint of improving the barrier property. And the lower limit thereof is not particularly limited.
The CSF of the pulp constituting the paper base material is measured according to JIS P 811-2: 2012 using the paper base pulp desorbed according to JIS P 820-1: 2012 as a sample.

(Degree of size by the Stekihito method)
The sizing degree (hereinafter, simply referred to as “sizing degree”) of the paper base material measured according to JIS P 8122: 2004 by the Stycht method is not particularly limited, but is preferably from the viewpoint of improving the barrier property. It is 1 second or more. The size of the paper substrate is determined by the type and content of internal sizing agents such as rosin, alkyl ketene dimer, alkenyl succinic anhydride, styrene-acrylic, higher fatty acid, and petroleum resin, and the type of pulp. It can be controlled by smoothing or the like. The content of the internal sizing agent is preferably 3 parts by mass or less with respect to 100 parts by mass of the pulp of the paper base material.

In addition to the internal sizing agent, other known internal additives may be added to the paper substrate. Examples of the internal additive include fillers such as titanium dioxide, kaolin, talc, and calcium carbonate, dry paper strength enhancer, wet paper strength enhancer, yield improver, pH adjuster, drainage improver, water resistance agent, and fabric softener. Examples include agents, antistatic agents, antifoaming agents, slime control agents, dyes, pigments and the like.

For paper-based paper making, a known wet paper machine (for example, a long net paper machine, a gap former type paper machine, a circular net type paper machine, a short net type paper machine, etc.) is appropriately selected and used. be able to. The paper layer formed by the paper machine is preferably conveyed by, for example, felt and dried by a dryer. A multi-stage cylinder dryer may be used as a pre-dryer before drying the dryer.

Further, the paper base material obtained as described above may be surface-treated with a calendar to make the thickness and profile uniform. As the calendar processing, a known calendar processing machine can be appropriately selected and used.

(Basis weight)
The basis weight of the paper substrate is not particularly limited, but is preferably 20 g / m ² or more, more preferably 30 g / m ² or more, still more preferably 40 g / m ² or more, and preferably 500 g / m ² or less. , More preferably 400 g / m ² or less, still more preferably 300 g / m ² or less, even more preferably 200 g / m ² or less, still more preferably 100 g / m ² or less.
The basis weight of the paper substrate is measured according to JIS P 8124: 2011.

(thickness)
The thickness of the paper substrate is preferably 5 μm or more, more preferably 10 μm or more, still more preferably 20 μm or more, and preferably 150 μm or less, more preferably 100 μm or less, still more preferably 75 μm or less.
The thickness of the paper substrate is measured according to JIS P 8118: 2014.

(density)
The density of the paper substrate is preferably 0.5 g / cm ³ or more, more preferably 0.6 g / cm ³ or more, and preferably 1.2 g / cm ³ or less, from the viewpoint of moldability. It is preferably 1.0 g / cm ³ or less.
The density of the paper base material is calculated from the basis weight and thickness of the paper base material obtained by the above-mentioned measuring method.

<Resin layer>
The resin layer contains a water-suspendable polymer, a plate-like inorganic compound having an aspect ratio of 100 or more, and a cationic resin.

(Water-suspendable polymer)
The water-suspendable polymer is a polymer that can be suspended in water, and it is easy to prepare a coating liquid using water as a dispersion medium when forming a resin layer on a paper substrate. To. Since the water-suspendable polymer functions as a binder in the formation of the resin layer, a resin layer containing a plate-like inorganic compound or the like can be formed on the paper substrate.
The water-suspendable polymer is preferably one or more selected from the group consisting of olefin / unsaturated carboxylic acid-based copolymers, styrene / butadiene-based copolymers, and styrene / acrylic-based copolymers.

≪Olefin / unsaturated carboxylic acid copolymer≫
The olefin / unsaturated carboxylic acid-based copolymer is a copolymer obtained by emulsion polymerization of an olefin monomer and an unsaturated carboxylic acid-based monomer.
Examples of the olefin monomer of the olefin / unsaturated carboxylic acid-based copolymer include ethylene and α-olefins such as propylene and butylene, and among these, ethylene is preferable.
The unsaturated carboxylic acid-based monomer of the olefin / unsaturated carboxylic acid-based copolymer includes an unsaturated carboxylic acid monomer and an ester monomer of an unsaturated carboxylic acid that forms a carboxylic acid by hydrolysis. Examples of the unsaturated carboxylic acid-based monomer of the olefin / unsaturated carboxylic acid-based copolymer include acrylic acid, methacrylic acid, crotonic acid, silicic acid, itaconic acid, fumaric acid, maleic acid, and butentricarboxylic acid. Unsaturated carboxylic acids and esters thereof; examples include unsaturated polycarboxylic acid alkyl esters having at least one carboxy group, such as itaconic acid monoethyl ester, fumaric acid monobutyl ester, maleic acid monobutyl ester.
The unsaturated carboxylic acid-based monomer constituting the olefin / unsaturated carboxylic acid-based copolymer may be used alone or in combination of two or more. The olefin / unsaturated carboxylic acid-based copolymer may be copolymerized with a small amount of an olefin and other monomers copolymerizable with the unsaturated carboxylic acid-based monomer.
Among these, the olefin / unsaturated carboxylic acid-based copolymer is preferably one or more selected from the group consisting of ethylene / acrylic acid-based copolymers and ethylene / methacrylic acid-based copolymers, and ethylene. / Acrylic acid copolymer, ethylene / methacrylic acid copolymer, ethylene / methyl acrylate copolymer, ethylene / methyl methacrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / ethyl methacrylate copolymer , Ethylene / butyl acrylate copolymer, and one or more selected from the group consisting of ethylene / butyl methacrylate copolymer, and more preferably ethylene / acrylate copolymer.

The content of the unsaturated carboxylic acid-based monomer unit of the olefin / unsaturated carboxylic acid-based copolymer is preferably 1 mol% or more, more preferably 10 mol% or more, and preferably 50 mol% or less. It is preferably 30 mol% or less. When the content of the unsaturated carboxylic acid-based monomer is within the above range, the dispersibility of the plate-like inorganic compound is excellent.

The weight average molecular weight of the olefin / unsaturated carboxylic acid-based copolymer is preferably 10,000 or more, more preferably 20,000 or more, and preferably 20,000 or more, from the viewpoint of viscosity and strength when applied to a paper substrate. It is 10 million or less, more preferably 5 million or less.

A commercially available product may be used as the olefin / unsaturated carboxylic acid-based copolymer, and examples thereof include "Zyxene (trade name)" manufactured by Sumitomo Seika Chemical Co., Ltd.

≪Styrene / butadiene copolymer≫
Examples of the styrene / butadiene copolymer include styrene / butadiene rubber (SBR) and modified styrene / butadiene rubber (modified SBR).
Examples of the modified styrene / butadiene rubber include acid-modified styrene / butadiene rubber (acid-modified SBR).
Commercially available products may be used as the styrene / butadiene copolymer, and examples thereof include "Nipol LX407S series (trade name)" and "Nipol LX407BP series (trade name)" manufactured by Zeon Corporation.

≪Styrene / acrylic copolymer≫
The styrene / acrylic copolymer is a copolymer obtained by emulsion-polymerizing a styrene-based monomer, an acrylic-based monomer, and other monomers copolymerizable with the styrene-based monomer, if necessary. Is. Examples of the styrene-based monomer include aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene, and chlorostyrene. Acrylic monomers include unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, crotonic acid, silicic acid, itaconic acid, fumaric acid, maleic acid, and butentricarboxylic acid, itaconic acid monoethyl ester, and fumaric acid. Unsaturated polycarboxylic acid alkyl esters with at least one carboxy group, such as acid monobutyl esters, maleic acid monobutyl esters, acrylamide propane sulfonic acids, acrylate sulfoethyl sodium salts, or methacrylate sulfopropyl sodium salts ( Meta) Examples thereof include acrylic sulfonic acid monomers or salts thereof. Examples of other monomers include alkyl (meth) acrylic acid (1 to 24 carbon atoms) ester.
Styrene is preferable as the styrene-based monomer. As the acrylic monomer, acrylic acid, methacrylic acid, itaconic acid, and fumaric acid are suitable.
Commercially available products may be used as the styrene / acrylic copolymer, and examples thereof include "Harville Series C-3 (trade name)" manufactured by Daiichi Paint Mfg. Co., Ltd. and "ACRONAL 4160" manufactured by BASF. Be done.

(Plate-shaped inorganic compound)
The plate-like inorganic compound has an aspect ratio of 100 or more, preferably 200 or more, more preferably 300 or more, and further preferably 500 or more. The larger the aspect ratio, the longer the moving distance of water vapor and gas becomes. Due to the maze effect, the water vapor barrier property and the gas barrier property can be improved. Further, the larger the aspect ratio, the more the amount of the plate-like inorganic compound added can be reduced. The upper limit of the aspect ratio is not particularly limited, but is preferably 10,000 or less from the viewpoint of availability, viscosity when forming the resin layer on the paper substrate, and the like.
The aspect ratio of the plate-shaped inorganic compound was determined by taking a magnified photograph of the cross section in the thickness direction parallel to the direction in which the resin layer was applied using an electron microscope, and the length of at least 30 plate-shaped inorganic compounds. The average length and average thickness are obtained by measuring the thickness and performing arithmetic averaging. Then, the value obtained by dividing the average length of the plate-shaped inorganic compound by the average thickness is defined as the aspect ratio of the plate-shaped inorganic compound.

The plate-like inorganic compound is not particularly limited as long as it has the above aspect ratio, but is preferably one or more selected from the group consisting of synthetic mica, bentonite, and kaolin, and more preferably synthetic mica. And one or more selected from the group consisting of kaolin.

From the viewpoint of improving the water vapor barrier property and the gas barrier property, the resin layer preferably contains a plate-like inorganic compound in an amount of 0.1% by mass or more, more preferably 1.0% by mass or more, and further preferably 2.0% by mass. From the viewpoint of production, the content is preferably 50% by mass or less, more preferably 40% by mass, still more preferably 30% by mass or less, still more preferably 20% by mass or less.

The content of the plate-like inorganic compound in the resin layer is preferably 5 parts by mass or more, more preferably 10 parts by mass with respect to 100 parts by mass of the water-suspendable polymer from the viewpoint of improving the water vapor barrier property and the gas barrier property. The above, and preferably 30 parts by mass or less, more preferably 25 parts by mass or less.

(Cationic resin)
When the resin layer contains a cationic resin, the dispersibility of the plate-like inorganic compound is improved, and the water vapor barrier property is greatly improved. The plate-shaped inorganic compound has a so-called card house structure in which the plate-shaped inorganic compounds are three-dimensionally connected to each other because the plate-shaped flat portion is easily charged anionic and the edge portion is easily charged cationically. It has been known. Due to this card house structure, the viscosity of the aqueous dispersion of the plate-like inorganic compound becomes very high. On the other hand, since the card house structure is easily broken when a force is applied by stirring or the like, the aqueous dispersion of the plate-like inorganic compound exhibits thixotropy. It is considered that when an appropriate cationic resin is added to the aqueous dispersion of the plate-shaped inorganic compound, the card house structure is destroyed by adsorbing the cationic resin on the anionically charged flat portion of the plate-shaped inorganic compound. Be done. As a result, it is presumed that the three-dimensional connection of the plate-shaped inorganic compounds is suppressed, the plate-shaped inorganic compounds are easily laminated in parallel with the plane of the paper substrate, and the water vapor barrier property is improved. Furthermore, it is estimated that the gas barrier property is also improved.

Examples of the cationic resin include polyamine resins, cation-modified polyamide resins (for example, amine-modified polyamide resins), polyamide epichlorohydrin resins, polyethyleneimine resins, polyalkylene polyamine resins, polyamide compounds, polyamideamine-epihalohydrins or formaldehyde condensation reactions. Products, Polyamine-Epihalohydrin or Formaldehyde Condensation Reaction Product, Polyamide Polyurea-Epihalohydrin or Formaldehyde Condensation Reaction Product, Polyamine Polyurea-Epihalohydrin or Formaldehyde Condensation Reaction Product, Polyamide Amine Polyurea-Epihalohydrin or Formaldehyde Condensation Reaction Product, Examples thereof include polyamide polyurea compounds, polyamine polyurea compounds, polyamideamine polyurea compounds and polyamideamine compounds, polyvinylpyridines, amino-modified acrylamide compounds, polyvinylamine resins, and polydialyldimethylammonium chlorides.
Among these, the cationic resin is preferably at least one selected from a polyamine resin, a cationically modified polyamide resin, and a polyethyleneimine resin, and more preferably a cationically modified polyamide resin.

The content of the cationic resin in the resin layer is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, based on 100 parts by mass of the water-suspendable polymer, from the viewpoint of improving the water vapor barrier property. It is more preferably 3 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass, still more preferably 10 parts by mass.

(Water-soluble polymer)
The resin layer may contain a water-soluble polymer from the viewpoint of improving the gas barrier property. In this case, the resin layer preferably contains 25 parts by mass or less of the water-soluble polymer with respect to 100 parts by mass of the water-suspendable polymer from the viewpoint of improving both the water vapor barrier property and the gas barrier property. More preferably, it contains 20 parts by mass or less.

Examples of the water-soluble polymer in the resin layer include polyvinyl alcohol, modified polyvinyl alcohol, starch and its derivatives, cellulose derivatives, polyvinylpyrrolidone, urethane resins, polyacrylic acid and salts thereof, casein, polyethyleneimine and the like. Among these, from the viewpoint of gas barrier property, the water-soluble polymer is preferably one or more selected from the group consisting of polyvinyl alcohol and modified polyvinyl alcohol, and more preferably modified polyvinyl alcohol.
Examples of the modified polyvinyl alcohol include ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and diacetone-modified polyvinyl alcohol. Among these, the modified polyvinyl alcohol is preferably one or more selected from the group consisting of ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, and acetoacetyl-modified polyvinyl alcohol, and ethylene-modified polyvinyl alcohol, It is more preferable that the amount is one or more selected from the group consisting of the carboxy-modified polyvinyl alcohol and the ethylene-modified polyvinyl alcohol.
The polyvinyl alcohol and the modified polyvinyl alcohol are preferably completely saponified or partially saponified. Completely saponified means that the degree of saponification is more than 96%.

A commercially available product may be used as the water-soluble polymer, and examples thereof include "Exevar (trade name)" manufactured by Kuraray Co., Ltd. as the modified polyvinyl alcohol.

In addition to the water-suspendable polymer, the plate-like inorganic compound, the cationic resin, and the water-soluble polymer, the resin layer contains a dispersant, a surfactant, and a defoamer other than the above-mentioned cationic resin as appropriate, if necessary. Foaming agents, wetting agents, dyes, color adjusting agents, thickeners and the like can be added.

<Protective layer>
The protective layer is not particularly limited as long as it has a film-forming property and the contact angle with water is 50 ° or more.

(Contact angle with water)
The contact angle of the protective layer with water is 50 ° or more, preferably 55 ° or more, more preferably 60 ° or more, and the upper limit thereof is not particularly limited, but is preferably 150 ° or more from the viewpoint of water resistance and the like. It is as follows.
The contact angle of the protective layer with water is measured according to JIS R 3257: 1999.
The contact angle of the protective layer with water can be adjusted by adjusting the type and content of the resin in the protective layer.

(Water-suspendable polymer)
The protective layer preferably contains a water-suspendable polymer. The water-suspendable polymer facilitates the preparation of a coating liquid using water as a dispersion medium when forming a protective layer on the resin layer.
The water-suspendable polymer in the protective layer is selected from the group consisting of olefin / unsaturated carboxylic acid-based copolymers, styrene / butadiene-based copolymers, styrene / acrylic-based copolymers, and biodegradable resins. It is preferably one or more.

≪Olefin / unsaturated carboxylic acid copolymer≫
Examples of the olefin monomer of the olefin / unsaturated carboxylic acid-based copolymer include ethylene and α-olefins such as propylene and butylene, and among these, ethylene is preferable.
The unsaturated carboxylic acid-based monomer of the olefin / unsaturated carboxylic acid-based copolymer includes an unsaturated carboxylic acid monomer and an ester monomer of an unsaturated carboxylic acid that forms a carboxylic acid by hydrolysis. Examples of the unsaturated carboxylic acid-based monomer of the olefin / unsaturated carboxylic acid-based copolymer include acrylic acid, methacrylic acid, crotonic acid, silicic acid, itaconic acid, fumaric acid, maleic acid, and butentricarboxylic acid. Unsaturated carboxylic acids and esters thereof; examples include unsaturated polycarboxylic acid alkyl esters having at least one carboxy group, such as itaconic acid monoethyl ester, fumaric acid monobutyl ester, maleic acid monobutyl ester.
The unsaturated carboxylic acid-based monomer constituting the olefin / unsaturated carboxylic acid-based copolymer may be used alone or in combination of two or more. The olefin / unsaturated carboxylic acid-based copolymer may be copolymerized with a small amount of an olefin and other monomers copolymerizable with the unsaturated carboxylic acid-based monomer.

Among these, the olefin / unsaturated carboxylic acid-based copolymer in the protective layer is at least one selected from the group consisting of ethylene / acrylic acid-based copolymers and ethylene / methacrylic acid-based copolymers. Is preferable, ethylene / acrylate copolymer, ethylene / methacrylic acid copolymer, ethylene / methyl acrylate copolymer, ethylene / methyl methacrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / methacrylic acid. It is more preferably one or more selected from the group consisting of an ethyl copolymer, an ethylene / butyl acrylate copolymer, and an ethylene / butyl methacrylate copolymer, and an ethylene / acrylate copolymer is preferable. More preferred.

≪Styrene / butadiene copolymer≫
Examples of the styrene / butadiene copolymer in the protective layer include styrene / butadiene rubber (SBR) and modified styrene / butadiene rubber (modified SBR).
Examples of the modified styrene / butadiene rubber include acid-modified styrene / butadiene rubber (acid-modified SBR).

≪Styrene / acrylic copolymer≫
The styrene / acrylic copolymer is a copolymer obtained by emulsion-polymerizing a styrene-based monomer, an acrylic-based monomer, and other monomers copolymerizable with the styrene-based monomer, if necessary. Is. Examples of the styrene-based monomer include aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene, and chlorostyrene. Acrylic monomers include unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, crotonic acid, silicic acid, itaconic acid, fumaric acid, maleic acid, and butentricarboxylic acid, itaconic acid monoethyl ester, and fumaric acid. Unsaturated polycarboxylic acid alkyl esters with at least one carboxy group, such as acid monobutyl esters, maleic acid monobutyl esters, acrylamide propane sulfonic acids, acrylate sulfoethyl sodium salts, or methacrylate sulfopropyl sodium salts ( Meta) Examples thereof include acrylic sulfonic acid monomers or salts thereof. Examples of other monomers include alkyl (meth) acrylic acid (1 to 24 carbon atoms) ester.
Styrene is preferable as the styrene-based monomer. As the acrylic monomer, acrylic acid, methacrylic acid, itaconic acid, and fumaric acid are suitable.
Commercially available products may be used as the styrene / acrylic copolymer, and examples thereof include "Harville Series C-3 (trade name)" manufactured by Daiichi Paint Mfg. Co., Ltd. and "ACRONAL 4160" manufactured by BASF. Be done.

≪Biodegradable resin≫
The biodegradable resin is not particularly limited, and examples thereof include polylactic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, and 3-hydroxybutanoic acid / 3-hydroxyhexanoic acid copolymer. The barrier laminate using a paper base material can reduce the environmental load as compared with the barrier laminate using a thermoplastic resin, but it is a biodegradable resin as a water-suspendable polymer in the protective layer. By using the above, the environmental load can be further reduced.
Commercially available products may be used as the biodegradable resin, and examples thereof include "Randy PL series (trade name)" manufactured by Miyoshi Oil & Fat Co., Ltd. as polylactic acid.

(Water-soluble polymer)
The protective layer may contain a water-soluble polymer from the viewpoint of improving the gas barrier property. In this case, the protective layer preferably contains 25 parts by mass or less of the water-soluble polymer, more preferably 20 parts by mass or less, based on 100 parts by mass of the water-suspended polymer. When the content of the water-soluble polymer is within the above range, a barrier laminate having excellent water vapor barrier property and gas barrier property can be obtained while preventing a decrease in water resistance.

Examples of the water-soluble polymer in the protective layer include polyvinyl alcohol, modified polyvinyl alcohol, starch and its derivatives, cellulose derivatives, polyvinylpyrrolidone, urethane resins, polyacrylic acids and salts thereof, casein, polyethyleneimine and the like. Among these, from the viewpoint of gas barrier property, the water-soluble polymer is preferably one or more selected from the group consisting of polyvinyl alcohol and modified polyvinyl alcohol, and more preferably modified polyvinyl alcohol.
Examples of the modified polyvinyl alcohol include ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and diacetone-modified polyvinyl alcohol. Among these, the modified polyvinyl alcohol is preferably one or more selected from the group consisting of ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, and acetoacetyl-modified polyvinyl alcohol, and ethylene-modified polyvinyl alcohol, It is more preferable that the amount is one or more selected from the group consisting of the carboxy-modified polyvinyl alcohol and the ethylene-modified polyvinyl alcohol.
The polyvinyl alcohol and the modified polyvinyl alcohol are preferably completely saponified or partially saponified. Completely saponified means that the degree of saponification is more than 96%.

(Plate-shaped inorganic compound)
The protective layer may contain a plate-like inorganic compound from the viewpoint of water vapor barrier property and gas barrier property. In this case, the protective layer preferably contains a plate-like inorganic compound in an amount of 0.1% by mass or more and 50% by mass or less, more preferably 1.0% by mass or more, still more preferably 2.0% by mass or more. Then, it is more preferably contained in an amount of 40% by mass or less, further preferably 30% by mass or less, still more preferably 20% by mass or less. By also containing the plate-like inorganic compound in the protective layer, a barrier laminate having more excellent water vapor barrier property and gas barrier property can be obtained.

The plate-like inorganic compound in the protective layer is preferably one or more selected from the group consisting of synthetic mica, bentonite, and kaolin, and more preferably one or more selected from the group consisting of synthetic mica and kaolin. is there.

The plate-like inorganic compound in the protective layer preferably has an aspect ratio of 100 or more, more preferably 200 or more, still more preferably 300 or more, and even more preferably 500 or more. The larger the aspect ratio, the more the movement of water vapor and gas is hindered, so that the water vapor barrier property and the gas barrier property can be improved. The upper limit of the aspect ratio is not particularly limited, but is preferably 10,000 or less from the viewpoint of availability, viscosity when applied onto the resin layer, and the like.

The protective layer may have the same composition as the resin layer or may have a composition different from that of the resin layer. When the protective layer has the same composition as the resin layer, it is not necessary to separately prepare a protective layer-imparting liquid for forming the protective layer, and the resin layer-imparting liquid for forming the resin layer is provided on the paper substrate. It is easy to manufacture because it only needs to be given (painted). By applying (coating) the resin layer-imparting liquid twice on the paper substrate, it is possible to fill the fine pores, cracks, etc. existing on the surface of the resin layer as described above, and as a result, the resin. Due to the plate-like inorganic compound with a high aspect ratio of the layers, the labyrinth effect of prolonging the movement of water vapor etc. is also exhibited in the gas, and even if the number of layers is small, it has excellent water vapor barrier properties and gas barrier properties, and has water resistance. A laminate can be provided.

In addition to the water-suspendable polymer, the water-soluble polymer, and the plate-like inorganic compound, the protective layer contains a dispersant, a surfactant, a defoaming agent, a wetting agent, a dye, and a color adjusting agent as needed. , Thickener and the like can be added.

[Manufacturing method of barrier laminate]
In the barrier laminate of the present invention, a resin layer and a protective layer are formed in this order on at least one surface of the paper substrate. The method for forming each layer is not particularly limited, but it is preferably formed by a coating method. Specifically, a resin layer coating liquid (resin layer paint) is applied onto a paper substrate, dried to form a resin layer, and then a protective layer coating liquid (protective layer paint) is applied. It is preferably dried and dried to form a protective layer.

When forming a plurality of coating layers on a paper substrate, the above method of sequentially forming coating layers is preferable, but the present invention is not limited to this, and a simultaneous multilayer coating method may be adopted. .. The simultaneous multi-layer coating method is a multi-layer coating method in which a plurality of types of coating liquids are separately discharged from a slit-shaped nozzle to form a liquid laminate, which is then coated on a paper substrate. This is a method of forming a working film at the same time.

The coating equipment for applying the coating liquid is not particularly limited, and known equipment may be used. Examples of the coating equipment include a blade coater, a bar coater, an air knife coater, a slit die coater, a gravure coater, a micro gravure coater, and a gate roll coater. In particular, for forming the resin layer, a coater that scrapes the coated surface, such as a blade coater, a bar coater, an air knife coater, and a slit die coater, is preferable because it promotes the orientation of the plate-like inorganic compound.

The drying equipment for drying the coating layer is not particularly limited, and known equipment can be used. Examples of the drying equipment include a hot air dryer, an infrared dryer, a gas burner, a hot plate, and the like. Further, the drying temperature may be appropriately set in consideration of the drying time and the like.

The solvent of the coating liquid for each layer is not particularly limited, and water or an organic solvent such as ethanol, isopropyl alcohol, methyl ethyl ketone or toluene can be used.
Among these, in the present invention, water is preferable as the dispersion medium of the coating liquid of each layer from the viewpoint of not causing the problem of the volatile organic solvent. That is, it is preferable that the resin layer coating liquid is a water-based composition for a resin layer, and the protective layer coating liquid is a water-based composition for a protective layer.

The solid content of the coating liquid of each layer is not particularly limited and may be appropriately selected from the viewpoint of coatability and ease of drying, but is preferably 3% by mass or more, more preferably 5% by mass or more, still more preferably. It is 10% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, and further preferably 60% by mass or less.

^{The coating amount (after drying) of each layer is not particularly limited, but is preferably 1 g / m 2} from the viewpoint of obtaining a barrier laminate having excellent water vapor barrier property and gas barrier property, water resistance, and excellent economy. As described above, it is more preferably 2 g / m ² or more, further preferably 3 g / m ² or more, and the upper limit thereof is preferably 7 g / m ² or less.

[Physical characteristics of barrier laminate]
(Oxygen permeability)
The lower the oxygen permeability of the barrier laminate, the less oxygen is permeated. Specifically, it is preferably 100 cc / m ² · day · atm or less, more preferably 90 cc / m ² · day · atm or less, and further. It is preferably 75 cc / m ² , day, atm or less.
The oxygen permeability of the barrier laminate is measured at 23 ° C. and 50% RH using an oxygen permeability measuring device (OX-TRAN2 / 20 manufactured by MOCON).

(Water vapor permeability)
The lower the water vapor permeability of the barrier laminate, the more preferable it is that water vapor does not permeate. Specifically, it is preferably 100 g / m ² · day or less, more preferably 50 g / m ² · day or less, and further preferably 10 g. It is less than / m ^{2 · day.}
The water vapor permeability of the barrier laminate is measured in accordance with JIS Z 0208: 1976 by preparing a moisture permeable cup so that the protective layer of the barrier laminate is on the inside (Condition B: Temperature 40 ±). 0.5 ° C., relative humidity 90 ± 2%).

(Degree of size by the Stekihito method)
The degree of size of the barrier laminate measured according to JIS P 8122: 2004 is preferably 300 seconds or longer, more preferably 350 seconds or longer.

Since the barrier laminate of the present invention is excellent in water vapor barrier property and gas barrier property and has water resistance, it is suitably used as a packaging body for foods and the like that require water resistance.

Hereinafter, the features of the present invention will be described in more detail with reference to Examples and Comparative Examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed in a limited manner by the specific examples shown below. Unless otherwise specified, "parts" and "%" in Examples and Comparative Examples indicate "parts by mass" and "% by mass", respectively.

[Evaluation and analysis]
The barrier laminates of Examples and Comparative Examples were evaluated and analyzed as follows.

(Contact angle with water)
In accordance with JIS R 3257: 1999, using a dynamic water contact angle tester (1100 DAT manufactured by Fibro), 1 to 4 μL of distilled water was dropped onto the protective layer of the barrier laminate, and 0.1 seconds after the drop. Water contact angle was measured.

(Oxygen permeability)
The oxygen permeability of the barrier laminate was measured using an oxygen permeability measuring device (OX-TRAN2 / 20 manufactured by MOCON) under the conditions of 23 ° C. and 50% RH.

(Water vapor permeability)
The water vapor permeability of the barrier laminate was measured in accordance with JIS Z 0208: 1976 by preparing a moisture permeable cup so that the protective layer of the barrier laminate was on the inside (condition B: temperature 40 ± 0). .5 ° C, relative humidity 90 ± 2%).

(Degree of size by the Stekihito method)
The size of the barrier laminate was measured according to JIS P 8122: 2004.

[Example 1]
<Preparation of resin layer paint>
Water dispersion of plate-like inorganic compound (synthetic mica, "NTO-05 (trade name)" manufactured by Topy Industries, Ltd., aspect ratio: about 1000, thickness: about 5 nm, solid content: 6%) 30.0 parts While stirring, ethylene / acrylic acid copolymer (“Zyxen AC (trade name)” manufactured by Sumitomo Seika Co., Ltd., solid content: 29.2%, acrylic acid copolymerization ratio: 20 mL%, melting point: 80-95 ° C.) 34.3 parts was added, and the mixture was further stirred. To this, 1.7 parts of a cation-modified polyamide resin (“Sumirez Resin SPI-203 (50) H (trade name)” manufactured by Taoka Chemical Industry Co., Ltd., solid content 53%) was added and stirred. Further, 0.1 part of a 25% aqueous ammonia solution was added and stirred. Further, water was added and stirred so that the solid content concentration became 18% to prepare a resin layer coating material.
<Preparation of protective layer paint>
Ethylene / acrylic acid copolymer (“Zyxen AC (trade name)” manufactured by Sumitomo Seika Co., Ltd., solid content 29.2%, acrylic acid copolymerization ratio: 20 mL%, melting point: 80 to 95 ° C.) Water was added and stirred to bring the solid content concentration to 18%, and a protective layer coating material was prepared.
<Manufacturing of barrier laminate>
Apply the obtained resin layer paint to bleached kraft paper (basis weight: 50 g / m ² , thickness: 60 μm) using a Mayer bar so that the coating amount of the resin layer after drying is 6 g / m ^2. After coating, it was dried in a hot air dryer at 120 ° C. for 3 minutes. Further, the protective layer paint is applied onto the resin layer ^{using a Mayer bar so that the coating amount after drying is 5 g / m 2,} and then dried in a hot air dryer at 120 ° C. for 3 minutes to provide a barrier. A sex laminate was obtained. The evaluation and analysis results are shown in Table 1.

[Example 2]
A barrier laminate was obtained in the same manner as in Example 1 except that the resin layer paint of Example 1 was used as the protective layer paint. The evaluation and analysis results are shown in Table 1.

[Example 3]
In the preparation of the resin layer coating material and the protective layer coating material, each of the resin layer coating material and the protective layer coating material of Example 2 was prepared with ethylene-modified polyvinyl alcohol (PVA, "Excelval AQ-4104 (trade name)" manufactured by Kuraray Co., Ltd.). 20 parts of saponified type, solid content: 10%) were added, water was added so that the solid content concentration became 15%, and the mixture was stirred to obtain a resin layer paint and a protective layer paint, respectively. A barrier laminate was obtained in the same manner as in Example 2 except that the coating amount after drying was 3 g / m ^2. The evaluation and analysis results are shown in Table 1.

[Example 4]
In the preparation of resin layer paint, an aqueous dispersion of a plate-like inorganic compound (synthetic mica, "NTO-05 (trade name)" manufactured by Topy Industry Co., Ltd., aspect ratio: about 1000, thickness: about 5 nm, solid content: 6%) 140 parts, acid-modified SBR (“Nipol LX407S12 (trade name)” manufactured by Nippon Zeon Co., Ltd., solid content: 47.3%) 90 parts, and acid-modified SBR (Nippon Zeon Co., Ltd.) with stirring. 10 parts of "Nipol LX407BP-6 (trade name)", solid content: 53%) was added, and the mixture was further stirred. To this, 5 parts of a cation-modified polyamide resin (“Sumirez Resin SPI-203 (50) H (trade name)” manufactured by Taoka Chemical Industry Co., Ltd., solid content 53%) was added and stirred. Further, 0.3 part of a 25% aqueous ammonia solution was added and stirred. Further, water was added and stirred so that the solid content concentration became 20% to prepare a resin layer coating material, and a barrier laminate was obtained in the same manner as in Example 1. The evaluation and analysis results are shown in Table 1.

[Example 5]
Examples in the preparation of the protective layer paint, except that the ethylene / acrylic acid copolymer was changed to polylactic acid (“Randy PL-3000 (trade name)” manufactured by Miyoshi Oil & Fat Co., Ltd., solid content: 40%). A barrier laminate was obtained in the same manner as in 1. The evaluation and analysis results are shown in Table 1.

[Comparative Example 1]
A barrier laminate was obtained in the same manner as in Example 1 except that the protective layer paint was not applied. The evaluation and analysis results are shown in Table 1.

[Comparative Example 2]
A barrier laminate was obtained in the same manner as in Example 1 except that the resin layer paint was not applied. The evaluation and analysis results are shown in Table 1.

[Comparative Example 3]
In the preparation of protective layer paint, ethylene / acrylic acid copolymer was used as ethylene-modified polyvinyl alcohol (PVA, "Excelval AQ-4104 (trade name)" manufactured by Kuraray Co., Ltd., completely saponified type, solid content: 10%). Barrier lamination was carried out in the same manner as in Example 1 except that the solid content concentration was changed to 10% and the protective layer ^{was coated so that the coating amount of the protective layer after drying was 0.5 g / m 2.} I got a body. The evaluation and analysis results are shown in Table 1.

[Comparative Example 4]
In the preparation of resin layer paints, plate-like inorganic compounds are used from synthetic mica to sericite (“KF1325 (trade name)” manufactured by Chuo Kaolin Co., Ltd., aspect ratio: 20 to 30 (catalog value), average particle size: 13 μm ( A barrier laminate was obtained in the same manner as in Example 1 except that the value was changed to (catalog value)). The evaluation and analysis results are shown in Table 1.

As can be seen from Table 1, according to the barrier laminate of this example, even if the number of layers is small, the barrier laminate is excellent in water vapor barrier property and gas barrier property, has water resistance, and is excellent in economy. Provided.

Claims (11)

A barrier laminate having a paper base material and a resin layer and a protective layer in this order on at least one surface of the paper base material.
The resin layer contains a water-suspendable polymer, a plate-like inorganic compound having an aspect ratio of 100 or more, and a cationic resin.
A barrier laminate having a protective layer with a contact angle of 50 ° or more with water. The water-suspendable polymer in the resin layer is at least one selected from the group consisting of olefin / unsaturated carboxylic acid-based copolymers, styrene / butadiene-based copolymers, and styrene / acrylic-based copolymers. The barrier laminate according to claim 1. The barrier laminate according to claim 1 or 2, wherein the plate-like inorganic compound in the resin layer is at least one selected from the group consisting of synthetic mica, bentonite, and kaolin. The barrier laminate according to any one of claims 1 to 3, wherein the resin layer contains 0.1% by mass or more and 50% by mass or less of a plate-like inorganic compound. The barrier laminate according to any one of claims 1 to 4, wherein the resin layer further contains 25 parts by mass or less of a water-soluble polymer with respect to 100 parts by mass of the water-suspended polymer. The barrier laminate according to claim 5, wherein the water-soluble polymer in the resin layer is at least one selected from the group consisting of polyvinyl alcohol and modified polyvinyl alcohol. The barrier laminate according to any one of claims 1 to 6, wherein the protective layer contains a water-suspendable polymer. The water-suspendable polymer in the protective layer is selected from the group consisting of olefin / unsaturated carboxylic acid-based copolymers, styrene / butadiene-based copolymers, styrene / acrylic-based copolymers, and biodegradable resins. The barrier laminate according to claim 7, which is one or more of the above-mentioned ones. The barrier laminate according to claim 7 or 8, wherein the protective layer further contains 25 parts by mass or less of a water-soluble polymer with respect to 100 parts by mass of the water-suspending polymer. The barrier laminate according to any one of claims 1 to 9, wherein the protective layer contains 0.1% by mass or more and 50% by mass or less of a plate-like inorganic compound. The barrier laminate according to claim 10, wherein the plate-like inorganic compound in the protective layer is at least one selected from the group consisting of synthetic mica, bentonite, and kaolin.