JP7807987B2 - Gas barrier coating material and gas barrier laminate - Google Patents

Description

The present invention relates to a gas barrier coating material and a gas barrier laminate.

As a gas barrier material, a laminate in which an inorganic layer serving as a gas barrier layer is provided on a base layer is used.
However, this inorganic layer is vulnerable to friction and the like, and such gas barrier laminates may suffer cracks in the inorganic layer due to friction or stretching during post-processing such as printing or lamination, or when filling with contents, resulting in a decrease in gas barrier properties.
Therefore, laminates using an organic layer as a gas barrier layer are also used as gas barrier materials.

As a gas barrier material using an organic layer as the gas barrier layer, a laminate having a gas barrier layer formed from a mixture containing a polycarboxylic acid and a polyamine compound is known. Examples of technologies related to such gas barrier laminates include those described in Patent Documents 1 and 2.

Patent Document 1 (JP 2005-225940 A) discloses a gas barrier film having a gas barrier layer formed from a polycarboxylic acid and a polyamine and/or polyol, with the polycarboxylic acid having a degree of crosslinking of 40% or more. The document also states that such a gas barrier film has excellent gas barrier properties under high-humidity conditions, just as it does under low-humidity conditions.

Patent Document 2 (JP 2013-10857 A) discloses a film in which a mixture of polyamine and polycarboxylic acid is applied to at least one side of a plastic film substrate, with the mixture being a polyamine/polycarboxylic acid weight ratio of 12.5/87.5 to 27.5/72.5. The document also states that such a gas barrier film maintains excellent gas barrier properties, particularly oxygen blocking properties, even after boiling treatment, and also has excellent flexibility, transparency, moisture resistance, chemical resistance, etc.

Japanese Patent Application Laid-Open No. 2005-225940 JP 2013-10857 A

The technical level required for various properties of gas barrier materials is becoming increasingly higher. The present inventors have investigated conventional gas barrier materials such as those described in Patent Documents 1 and 2.
As a result, it has become clear that the gas barrier materials described in Patent Documents 1 and 2 require heating at high temperatures for a long period of time in order to crosslink the polycarboxylic acid and the polyamine, which may result in reduced productivity.
Furthermore, it has become clear that when the heating temperature for crosslinking polycarboxylic acid with polyamine or the heat treatment time is reduced in order to improve productivity, the proportion of amide bonds formed by crosslinking polycarboxylic acid with polyamine decreases, which may result in a decrease in the barrier properties of such gas barrier materials.
From these findings, the present inventors have found that there is room for improvement in conventional gas barrier materials from the viewpoint of improving productivity and barrier property in a balanced manner. Although many technologies have focused on improving barrier performance, no technology has been reported to date that improves barrier property and productivity in a balanced manner.

The present invention was made in consideration of the above circumstances, and provides a gas barrier coating material that achieves an improved balance between productivity and barrier properties through low-temperature, short-time heat treatment.

The present invention provides the following gas barrier coating material and gas barrier laminate.

[1]
A gas barrier coating material comprising a polycarboxylic acid, a polyamine compound, and a Zn compound,
The gas barrier coating material has a ratio of (the number of moles of Zn compounds in the gas barrier coating material)/(the number of moles of -COO- groups contained in polycarboxylic acid in the gas barrier coating material) of 0.40 or more and 0.70 or less.
[2]
The gas barrier coating material according to the above [1],
A gas barrier coating material that further contains a cross-linking agent.
[3]
The gas barrier coating material according to the above [2],
The gas barrier coating material, wherein the crosslinking agent comprises one or more compounds selected from the group consisting of epoxysilane compounds, carbodiimide compounds, and isocyanate compounds.
[4]
The gas barrier coating material according to any one of the above [1] to [3],
The gas barrier coating material, wherein the polycarboxylic acid comprises one or more compounds selected from the group consisting of polyacrylic acid, polymethacrylic acid, and a copolymer of acrylic acid and methacrylic acid.
[5]
The gas barrier coating material according to any one of the above [1] to [4],
The gas barrier coating material, wherein the polyamine compound comprises one or more compounds selected from the group consisting of polyallylamine, polyvinylamine, polyethyleneimine, and poly(trimethyleneimine).
[6]
The gas barrier coating material according to any one of the above [1] to [5],
The gas barrier coating material further comprises a polyphosphate compound or a salt thereof.
[7]
The gas barrier coating material according to the above [6],
The gas barrier coating material has a ratio of (the number of moles of P contained in the polyphosphate compound or its salt in the gas barrier coating material)/(the number of moles of COO- groups contained in the polycarboxylic acid in the gas barrier coating material) of 0.005 or more and 0.20 or less.
[8]
The gas barrier coating material according to any one of the above [1] to [7],
The gas barrier coating material has a ratio of (the number of moles of amino groups contained in the polyamine compound in the gas barrier coating material)/(the number of moles of -COO- groups contained in the polycarboxylic acid in the gas barrier coating material) of 0.40 or more and 0.70 or less.
[9]
A substrate layer and a gas barrier layer provided on at least one surface of the substrate layer,
A gas barrier laminate, wherein the gas barrier layer comprises a cured product of the gas barrier coating material according to any one of [1] to [8] above.
[10]
The gas barrier laminate according to the above [9],
The gas barrier laminate, wherein the thickness of the gas barrier layer is 0.05 μm or more and 10 μm or less.
[11]
The gas barrier laminate according to the above [9] or [10],
The gas barrier laminate further comprises an inorganic layer provided between the base layer and the gas barrier layer.
[12]
The gas barrier laminate according to the above [11],
a gas barrier laminate, wherein the inorganic layer is a vapor-deposited film provided on the base layer, or, if an intervening layer is present between the base layer and the inorganic layer, on the intervening layer, and is composed of one or more inorganic materials selected from the group consisting of silicon oxide, aluminum oxide, and aluminum.

The present invention makes it possible to provide a gas barrier material with an improved balance between productivity and barrier properties through low-temperature, short-time heat treatment.

1 is a cross-sectional view schematically illustrating an example of the structure of a gas barrier laminate according to an embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the drawings are schematic diagrams and do not correspond to the actual dimensional ratios.
In this specification, unless otherwise specified, the symbol "-" between numbers in a sentence indicates from above to below, and includes both values.
In this specification, (meth)acrylic means at least one of acrylic and methacrylic.
In this embodiment, the composition may contain each component either alone or in combination of two or more.

The gas barrier coating material of this embodiment is a gas barrier coating material containing a polycarboxylic acid, a polyamine compound, and a Zn compound, and the ratio (number of moles of Zn compounds in the gas barrier coating material) / (number of moles of -COO- groups contained in the polycarboxylic acid in the gas barrier coating material) in the gas barrier coating material is 0.40 or more and 0.70 or less.

The gas barrier coating material of this embodiment contains a polycarboxylic acid, a polyamine compound, and a Zn compound, thereby providing a gas barrier material with improved barrier properties, such as oxygen barrier property and water vapor barrier property, before and after retort processing. Furthermore, by incorporating a larger amount of Zn compound than conventionally contained in the gas barrier coating material, with the ratio (number of moles of Zn compound in the gas barrier coating material) / (number of moles of -COO- groups contained in the polycarboxylic acid in the gas barrier coating material) being 0.40 or more and 0.70 or less, a gas barrier material with improved barrier properties can be provided, even with heat treatment at a lower temperature and for a shorter time than conventional manufacturing methods.

In the gas barrier coating material of this embodiment, (the number of moles of Zn compounds in the gas barrier coating material)/(the number of moles of -COO- groups contained in the polycarboxylic acid in the gas barrier coating material) is 0.40 or more, preferably 0.41 or more, and more preferably 0.42 or more, from the viewpoint of further improving the gas barrier performance after retort treatment.
From the same viewpoint, (the number of moles of Zn compounds in the gas barrier coating material)/(the number of moles of -COO- groups contained in the polycarboxylic acid in the gas barrier coating material) is 0.70 or less, preferably 0.60 or less, and more preferably 0.50 or less.

The components contained in the gas barrier coating material of this embodiment will be described in detail below.

(Polycarboxylic acid)
The polycarboxylic acid contained in the gas barrier coating material of this embodiment has two or more carboxy groups in the molecule. Specific examples include homopolymers of α,β-unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, fumaric acid, crotonic acid, cinnamic acid, 3-hexenoic acid, and 3-hexenedioic acid, as well as copolymers thereof. Furthermore, copolymers of the above α,β-unsaturated carboxylic acids with esters such as ethyl esters, or olefins such as ethylene, may also be used.

Among these, homopolymers or copolymers of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, crotonic acid, and cinnamic acid are preferred, and one or more polymers selected from the group consisting of polyacrylic acid, polymethacrylic acid, and copolymers of acrylic acid and methacrylic acid are more preferred, at least one polymer selected from polyacrylic acid and polymethacrylic acid is even more preferred, and at least one polymer selected from a homopolymer of acrylic acid and a homopolymer of methacrylic acid is even more preferred.

In the present embodiment, polyacrylic acid includes both a homopolymer of acrylic acid and a copolymer of acrylic acid and another monomer. In the case of a copolymer of acrylic acid and another monomer, the polyacrylic acid contains, for example, 90% by mass or more, preferably 95% by mass or more, and more preferably 99% by mass or more of structural units derived from acrylic acid, based on 100% by mass of the polymer.
In the present embodiment, the term "polymethacrylic acid" refers to both a homopolymer of methacrylic acid and a copolymer of methacrylic acid and another monomer. In the case of a copolymer of methacrylic acid and another monomer, the polymethacrylic acid contains, for example, 90% by mass or more, preferably 95% by mass or more, and more preferably 99% by mass or more of structural units derived from methacrylic acid per 100% by mass of the polymer.

The polycarboxylic acid is a polymer obtained by polymerizing a carboxylic acid monomer. From the viewpoint of achieving an excellent balance between gas barrier properties and handleability, the molecular weight of the polycarboxylic acid is preferably 500 to 2,500,000, more preferably 5,000 to 2,000,000, more preferably 10,000 to 1,500,000, still more preferably 100,000 to 1,200,000, still more preferably 300,000 to 1,100,000, still more preferably 500,000 to 1,000,000, and still more preferably 600,000 to 900,000.
In this embodiment, the molecular weight of the polycarboxylic acid is a weight average molecular weight calculated as polyethylene oxide, and can be measured using gel permeation chromatography (GPC).

The polycarboxylic acid may be at least partially neutralized with a volatile base. Neutralizing the polycarboxylic acid with a volatile base can prevent gelation from occurring when the polycarboxylic acid is mixed with a Zn compound or a polyamine compound. Therefore, in order to prevent gelation, it is preferable to partially or completely neutralize the carboxy groups of the polycarboxylic acid with a volatile base. The neutralized product can be obtained by partially or completely neutralizing the carboxy groups of the polycarboxylic acid with a volatile base, that is, by partially or completely converting the carboxy groups of the polycarboxylic acid into carboxylates. This can prevent gelation when the polyamine compound or Zn compound is added.
The partially neutralized product can be prepared by adding a volatile base to an aqueous solution of a polycarboxylic acid polymer, and the desired degree of neutralization can be achieved by adjusting the ratio of the amount of polycarboxylic acid to the volatile base. In this embodiment, the degree of neutralization of the polycarboxylic acid with the volatile base is preferably 70 to 300 equivalent %, more preferably 90 to 250 equivalent %, and even more preferably 100 to 200 equivalent %, from the viewpoint of sufficiently suppressing gelation due to the neutralization reaction with the amino group of the polyamine compound.

As the volatile base, any water-soluble base can be used.
Examples of the volatile base include ammonia, morpholine, alkylamines, tertiary amines such as 2-dimethylaminoethanol, N-methylmorpholine, ethylenediamine, and triethylamine, aqueous solutions of these, and mixtures of these. From the viewpoint of obtaining good gas barrier properties, an aqueous ammonia solution is preferred.

(Polyamine Compound)
The gas barrier coating material of this embodiment contains a polyamine compound. By containing a polyamine compound, the barrier properties of the resulting gas barrier material can be improved.
The polyamine compound is a compound having two or more amino groups in the main chain, side chain, or terminal, and is preferably a polymer.Specific examples include aliphatic polyamines such as polyallylamine, polyvinylamine, polyethyleneimine, and poly(trimethyleneimine); polyamides having amino groups in the side chain, such as polylysine and polyarginine; and the like.Also, polyamines in which some of the amino groups have been modified may be used.
From the viewpoint of obtaining good gas barrier properties, the polyamine compound preferably contains one or more compounds selected from the group consisting of polyallylamine, polyvinylamine, polyethyleneimine, and poly(trimethyleneimine), more preferably contains polyethyleneimine, and even more preferably is polyethyleneimine.

From the viewpoint of achieving an excellent balance between gas barrier properties and handleability, the number average molecular weight of the polyamine compound is preferably from 50 to 2,000,000, more preferably from 100 to 1,000,000, even more preferably from 1,500 to 500,000, still more preferably from 1,500 to 100,000, still more preferably from 1,500 to 50,000, still more preferably from 3,500 to 20,000, still more preferably from 5,000 to 15,000, and still more preferably from 7,000 to 12,000.
In this embodiment, the molecular weight of the polyamine compound can be measured by a boiling point elevation method or a viscosity method.

In the gas barrier coating material of this embodiment, the ratio (number of moles of amino groups contained in the polyamine compound in the gas barrier coating material)/(number of moles of -COO- groups contained in the polycarboxylic acid in the gas barrier coating material) is preferably 0.40 or more, more preferably 0.43 or more, even more preferably 0.45 or more, even more preferably 0.50 or more, and even more preferably 0.53 or more, from the viewpoint of further improving the gas barrier performance after retort treatment.
From the same viewpoint, (the number of moles of amino groups contained in the polyamine compound in the gas barrier coating material)/(the number of moles of -COO- groups contained in the polycarboxylic acid in the gas barrier coating material) is preferably 0.70 or less, more preferably 0.65 or less, even more preferably 0.60 or less, and even more preferably 0.58 or less.
Although the details of the reason for this are not clear, it is thought that a gas barrier layer 103 having excellent gas barrier performance after retort treatment and a gas barrier laminate having the same can be obtained by forming a dense structure in a well-balanced manner of amide crosslinking by the amino groups that constitute the polyamine compound and metal crosslinking by Zn that constitutes the salt of polycarboxylic acid and Zn.

(Zn compound)
Specific examples of the Zn compound contained in the gas barrier coating material of this embodiment include zinc (Zn) oxide, hydroxide, halide, carbonate, phosphate, phosphite, hypophosphite, sulfate, sulfite, etc. From the viewpoint of water resistance, impurities, etc., at least one of zinc oxide and zinc hydroxide is preferred, and zinc oxide is more preferred.

In the gas barrier coating material of this embodiment, the ratio (number of moles of Zn compounds in the gas barrier coating material)/(number of moles of amino groups contained in the polyamine compound in the gas barrier coating material) is preferably 0.50 or more, more preferably 0.60 or more, even more preferably 0.70 or more, and even more preferably 0.75 or more, from the viewpoint of further improving the gas barrier performance after retort treatment.
From the same viewpoint, (the number of moles of Zn compounds in the gas barrier coating material)/(the number of moles of amino groups contained in the polyamine compound in the gas barrier coating material) is preferably 1.00 or less, more preferably 0.95 or less, and even more preferably 0.90 or less.

The gas barrier coating material of this embodiment may contain components other than the above-mentioned components.
For example, the gas barrier coating material of this embodiment preferably further contains an ammonium carbonate salt. The ammonium carbonate salt is added to convert the Zn compound into a zinc ammonium carbonate complex, thereby improving the solubility of the Zn compound and preparing a homogeneous solution containing the Zn compound. By including the ammonium carbonate salt in the gas barrier coating material, the amount of Zn compound dissolved can be increased, and as a result, the gas barrier coating material containing the Zn compound can be made even more homogeneous.
Examples of carbonate-based ammonium salts include ammonium carbonate and ammonium hydrogen carbonate, with ammonium carbonate being preferred because it is easily volatile and unlikely to remain in the resulting gas barrier layer.
From the viewpoint of further improving the solubility of the Zn compound, the ratio (number of moles of carbonate-based ammonium salt in the gas barrier coating material)/(number of moles of Zn compound in the gas barrier coating material) is preferably 0.05 or more, more preferably 0.10 or more, even more preferably 0.25 or more, even more preferably 0.50 or more, and even more preferably 0.75 or more.
Furthermore, from the viewpoint of further improving the coatability as a gas barrier coating material, (the number of moles of carbonate-based ammonium salt in the gas barrier coating material)/(the number of moles of Zn compound in the gas barrier coating material) is preferably 10.0 or less, more preferably 5.0 or less, even more preferably 2.0 or less, and even more preferably 1.5 or less.

(Phosphorus compounds or salts thereof)
When the gas barrier layer of the gas barrier laminate described below is subjected to mass spectrometry, PO ^2- and/or PO ^3- are detected. In order to provide such a gas barrier layer, the gas barrier coating material of this embodiment preferably contains a phosphorus introduction source. More preferably, such a phosphorus introduction source contains a phosphorus compound or a salt thereof.
The phosphorus compound in the phosphorus compound or salt thereof contains one or more —P—OH groups in its molecular structure. The phosphorus compound may be incorporated into the mixture as a salt.
From the viewpoint of further improving the water vapor barrier property after retort treatment, the phosphorus compound preferably contains two or more -P-OH groups, more preferably three or more -P-OH groups. From the viewpoint of productivity, the number of -P-OH groups in the phosphorus compound may be, for example, 10 or less.

Specific examples of phosphorus compounds include phosphoric acid compounds, phosphorous acid compounds, phosphonic acid compounds, hypophosphorous acid compounds, polyphosphoric acid compounds, and derivatives thereof.
Specifically, polyphosphate compounds have a condensation structure of two or more phosphoric acids in the molecular structure, and examples thereof include diphosphate (pyrophosphate), triphosphate, and polyphosphate compounds in which four or more phosphoric acids are condensed.
Specific examples of the derivatives include esters of the above phosphorus compounds, such as phosphorylated starch and phosphate-crosslinked starch; halides, such as chlorides; anhydrides, such as tetraphosphorus decaoxide; and compounds having a structure in which a hydrogen atom bonded to a phosphorus atom is substituted with an alkyl group, such as nitrilotris(methylenephosphonic acid) and N,N,N',N'-ethylenediaminetetrakis(methylenephosphonic acid).

From the viewpoint of further improving the balance between barrier properties and productivity, the phosphorus compound is one or more compounds selected from the group consisting of phosphoric acid compounds, phosphorous acid compounds, hypophosphorous acid compounds, polyphosphoric acid compounds, phosphonic acid compounds, and salts thereof, and more preferably at least one compound selected from the group consisting of phosphoric acid compounds, phosphorous acid compounds, phosphonic acid compounds, and salts thereof.

Specific examples of the salt of the phosphorus compound include salts of monovalent metals such as sodium and potassium; and ammonium salts. From the viewpoint of barrier properties, the salt of the phosphorus compound is preferably an ammonium salt.
A specific example of such a compound is diammonium hydrogen phosphate.

(Polyphosphate compound or salt thereof)
Among the above phosphorus compounds or salts thereof, polyphosphate compounds or salts thereof are preferred as a source of phosphorus introduction, from the viewpoint of being able to impart water resistance in addition to the above-mentioned improvements in productivity and barrier properties.

Specific examples of the salt of the polyphosphate compound include salts of monovalent metals such as sodium and potassium, and ammonium salts. From the viewpoint of barrier properties, the salt of the polyphosphate compound is preferably an ammonium salt.
Specific examples of polyphosphate compounds or salts thereof include at least one selected from the group consisting of: oligomeric polyphosphates or salts thereof, such as oligomeric polyphosphates, oligomeric ammonium polyphosphates, oligomeric sodium polyphosphates, and oligomeric potassium polyphosphates; pyrophosphates or salts thereof, such as pyrophosphates, ammonium pyrophosphates, sodium pyrophosphates, and potassium pyrophosphates; tripolyphosphates or salts thereof, such as tripolyphosphates, ammonium tripolyphosphates, sodium tripolyphosphates, and potassium tripolyphosphates; and tetrapolyphosphates or salts thereof, such as tetrapolyphosphates, ammonium tetrapolyphosphates, sodium tetrapolyphosphates, and potassium tetrapolyphosphates. Among these, from the viewpoint of further improving the balance between the barrier properties and pot life of the gas barrier coating material, preferred are oligomeric polyphosphates or salts thereof, more preferably ammonium oligomeric polyphosphates. Here, in this specification, "oligomeric polyphosphates" refers to, for example, polyphosphates having a degree of polymerization of 5 or more and 100 or less.

In this embodiment, from the viewpoint of improving barrier properties, (the number of moles of P contained in the phosphorus compound or its salt in the gas barrier coating material) / (the number of moles of COO- groups contained in the polycarboxylic acid in the gas barrier coating material) or (the number of moles of P contained in the polyphosphate compound or its salt in the gas barrier coating material) / (the number of moles of COO- groups contained in the polycarboxylic acid in the gas barrier coating material) is preferably 0.005 or more, more preferably 0.007 or more, and even more preferably 0.010 or more. In phosphorus compounds containing one P atom in their chemical formula, such as phosphoric acid, the number of moles of P atoms and the number of moles of phosphorus compounds have the same meaning. Furthermore, in phosphorus compounds and polyphosphate compounds containing multiple P atoms in their chemical formula, the number of moles of P atoms is calculated by multiplying the number of moles of phosphorus compound or polyphosphate compound by the number of P atoms contained in the chemical formula.
Furthermore, from the viewpoint of barrier properties and productivity, the ratio (number of moles of P contained in the phosphorus compound or salt thereof in the gas barrier coating material)/(number of moles of COO-groups contained in the polycarboxylic acid in the gas barrier coating material) or (number of moles of P contained in the polyphosphate compound or salt thereof in the gas barrier coating material)/(number of moles of COO-groups contained in the polycarboxylic acid in the gas barrier coating material) is preferably 0.20 or less, more preferably 0.15 or less, even more preferably 0.12 or less, and even more preferably 0.10 or less.

(Surfactant)
In addition to improving the productivity and barrier properties as described above, the gas barrier coating material of this embodiment preferably further contains a surfactant from the viewpoint of suppressing repellency when applied as a gas barrier coating material.
The surfactant content is preferably 0.01 to 3% by mass, and more preferably 0.01 to 1% by mass, when the total solid content of the gas barrier coating material (the total amount of components remaining as solids when cured) is taken as 100% by mass. In this specification, the solid content of the gas barrier coating material refers to the components remaining as solids when the gas barrier coating material is cured.

Surfactants include, for example, anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. From the viewpoint of achieving good coatability, nonionic surfactants are preferred, polyoxyalkylene alkyl ethers are more preferred, and polyoxyethylene alkyl ethers are even more preferred.

Examples of nonionic surfactants include polyoxyalkylene alkyl aryl ethers, polyoxyalkylene alkyl ethers, polyoxyalkylene fatty acid esters, sorbitan fatty acid esters, silicone surfactants, acetylene alcohol surfactants, and fluorine-containing surfactants.

Examples of polyoxyalkylene alkylaryl ethers include polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, and polyoxyethylene dodecylphenyl ether.
Examples of polyoxyalkylene alkyl ethers include polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether and polyoxyethylene lauryl ether.
Examples of polyoxyalkylene fatty acid esters include polyoxyethylene oleate, polyoxyethylene laurate, and polyoxyethylene distearate.
Examples of sorbitan fatty acid esters include sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate.
An example of the silicone surfactant is dimethylpolysiloxane.
Examples of acetylene alcohol surfactants include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, and 3,5-dimethyl-1-hexyne-3-ol.
Examples of the fluorine-containing surfactant include fluorine alkyl esters.

(Crosslinking agent)
In addition to improving the productivity and barrier properties described above, the gas barrier coating material of this embodiment preferably further contains a crosslinking agent from the viewpoint of improving alkali resistance to alkaline liquids (e.g., alkaline detergents, etc.).

While known crosslinking agents can be used as such crosslinking agents, they preferably contain one or more compounds selected from the group consisting of epoxy silane compounds, carbodiimide compounds, and isocyanate compounds, and more preferably contain one or more compounds selected from the group consisting of epoxy silane compounds and carbodiimide compounds.

In the gas barrier coating material of this embodiment, the content of the crosslinking agent is preferably 0.010% by mass or more, and more preferably 0.015% by mass or more, when the total solid content of the gas barrier coating material is taken as 100% by mass. By having the content of the crosslinking agent be equal to or greater than the above lower limit, the alkali resistance of the gas barrier layer formed by the gas barrier coating material of this embodiment becomes more favorable.
The content of the crosslinking agent is preferably 2% by mass or less, more preferably 1% by mass or less, and even more preferably 0.05% by mass or less. By making the content of the crosslinking agent equal to or less than the upper limit, the productivity and barrier properties of the gas barrier coating material of this embodiment become more favorable.

The gas barrier coating material of this embodiment may contain additives other than the components described above. For example, various additives such as lubricants, slip agents, antiblocking agents, antistatic agents, antifogging agents, pigments, dyes, and inorganic or organic fillers may be added.

Furthermore, from the viewpoint of improving the coatability when applied as a gas barrier coating material, the solids concentration of the gas barrier coating material of this embodiment is preferably 0.5 to 15% by mass, more preferably 1 to 10% by mass, even more preferably 1 to 5% by mass, and even more preferably 1 to 3% by mass.

(Gas barrier laminate)
1 is a cross-sectional view schematically illustrating an example of the configuration of a gas barrier laminate according to an embodiment. The gas barrier laminate according to this embodiment comprises a base layer 101 and a gas barrier layer 103 provided on at least one surface of the base layer 101, and the gas barrier layer 103 contains a cured product of the gas barrier coating material.
In this case, the gas barrier laminate of this embodiment preferably further comprises an inorganic layer 102 provided between the base layer 101 and the gas barrier layer 103 .
The specific structure of each layer in the gas barrier laminate of this embodiment will be described in detail below.

(Gas Barrier Layer)
Specifically, the gas barrier layer 103 can be produced by applying and curing a gas barrier coating material. In this way, the gas barrier layer 103 in this embodiment can contain a cured product of the gas barrier coating material.
The gas barrier coating material of this embodiment can be obtained as follows.
First, a volatile base is added to a polycarboxylic acid to completely or partially neutralize the carboxyl groups of the polycarboxylic acid, and then a zinc compound and an ammonium carbonate salt are added to form metal salts of all or part of the carboxyl groups of the polycarboxylic acid neutralized with the volatile base and of the carboxyl groups of the polycarboxylic acid not neutralized with the volatile base.
Then, by further adding a polyamine compound, the gas barrier coating material of this embodiment is obtained. By mixing the polycarboxylic acid, the Zn compound, and optionally the carbonate-based ammonium salt and the polyamine compound in this manner, the formation of aggregates can be suppressed, and a more uniform gas barrier coating material can be obtained. This makes it possible to more effectively promote the dehydration condensation reaction between the -COO- group contained in the polycarboxylic acid and the amino group contained in the polyamine compound.

More details are as follows: In the following, an example will be described in which a volatile base and a carbonate-based ammonium salt are blended in a gas barrier coating material.
First, a solution in which the carboxy groups constituting the polycarboxylic acid are completely or partially neutralized is prepared.
A volatile base is added to a polycarboxylic acid to completely or partially neutralize the carboxyl groups of the polycarboxylic acid. Neutralizing the carboxyl groups of the polycarboxylic acid effectively prevents gelation that occurs when a Zn compound or a polyamine compound is added, due to the reaction between the carboxyl groups of the polycarboxylic acid and the amino groups of the Zn compound or the polyamine compound, and allows for the production of a more uniform gas barrier coating material.
Next, a Zn compound and a carbonate-based ammonium salt are added and dissolved, and the resulting Zn ions form a Zn salt with the -COO- group that constitutes the polycarboxylic acid. The -COO- group that forms a salt with the Zn ion refers to both the carboxyl group that has not been neutralized with the base and the -COO- group that has been neutralized with the base. In the case of a -COO- group that has been neutralized with a base, the Zn ion contained in the Zn compound is replaced and coordinated to form a Zn salt of the -COO- group. After the Zn salt is formed, a polyamine compound and, if a phosphorus compound or its salt is included, a phosphorus compound or its salt can be added to obtain a gas barrier coating material.

The gas barrier coating material produced in this manner is applied to the substrate layer 101, the inorganic layer 102, or an intermediate layer between the inorganic layer 102 and the gas barrier layer 103 formed on the inorganic layer 102, and then dried and cured to form the gas barrier layer 103. At this time, the -COO- groups constituting the polycarboxylic acid and the Zn of the Zn salt form metal bridges, and the amino groups constituting the polyamine form amide bridges, resulting in a gas barrier layer 103 with excellent gas barrier properties. A more detailed method for producing the gas barrier layer 103 will be described later.

From the viewpoint of improving the barrier properties, the thickness of the gas barrier layer 103 after drying and curing is preferably 0.05 μm or more, more preferably 0.07 μm or more, and even more preferably 0.1 μm or more.
From the viewpoint of reducing the overall thickness of the gas barrier laminate, the thickness of the gas barrier layer 103 after drying and curing is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 1 μm or less, and even more preferably 0.5 μm or less.

(Base material layer)
The base layer 101 may be a single layer or may be made up of two or more layers. The shape of the base layer 101 is not limited, and examples thereof include a sheet or film shape, a tray shape, a cup shape, a hollow body shape, and the like.

Any material can be used for the substrate layer 101, as long as it allows for stable formation of the inorganic layer 102 (described below) on the substrate layer 101 and allows for a gas barrier coating solution to be applied to the top of the inorganic layer 102. Examples of materials for the substrate layer 101 include organic materials such as thermosetting resins, thermoplastic resins, and paper; inorganic materials such as glass, porcelain, ceramics, silicon oxide, silicon oxynitride, silicon nitride, cement, aluminum, aluminum oxide, iron, copper, and stainless steel; and multilayer substrate layers made of a combination of organic materials or organic and inorganic materials. Among these, for example, for various film applications such as packaging materials and panels, plastic films made of at least one resin selected from the group consisting of thermosetting resins and thermoplastic resins, or organic materials such as paper, are preferred.

Thermosetting resins that can be used include known thermosetting resins, such as epoxy resin, unsaturated polyester resin, phenolic resin, urea-melamine resin, polyurethane resin, silicone resin, and polyimide.

Thermoplastic resins that can be used include known thermoplastic resins. Examples include polyolefins (polyethylene, polypropylene, poly(4-methyl-1-pentene), poly(1-butene), etc.), polyesters (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyamides (nylon-6, nylon-66, polymetaxylene adipamide, etc.), polyvinyl chloride, polyimide, ethylene-vinyl acetate copolymers or saponified products thereof, polyvinyl alcohol, polyacrylonitrile, polycarbonate, polystyrene, ionomers, fluororesins, and mixtures thereof.

Among these, from the viewpoint of improving transparency, one or more resins selected from the group consisting of polypropylene, polyethylene terephthalate (PET), polyethylene naphthalate, polyamide, polyimide, and polybutylene terephthalate are preferred.
Furthermore, from the viewpoint of excellent pinhole resistance, tear resistance, heat resistance, etc., one or more resins selected from the group consisting of polyamide, polyethylene terephthalate, and polybutylene terephthalate are preferred. From the same viewpoint, the base layer 101 is preferably a layer containing one or more resins selected from the group consisting of polyamide, polyethylene terephthalate, and polybutylene terephthalate, and more preferably a layer of one or more of these resins.

Furthermore, if a hygroscopic material such as polyamide is used for the base layer 101, the base layer 101 in the gas barrier laminate will absorb moisture and swell, which can easily reduce the gas barrier performance under high humidity, after retort treatment, and when filled with acidic contents. However, in this embodiment, even when a hygroscopic material is used for the base layer 101, the gas barrier performance of the gas barrier laminate under high humidity and after retort treatment can be effectively prevented from decreasing.

Alternatively, the substrate layer 101 may be formed by stretching a film made of a thermosetting resin or a thermoplastic resin at least in one direction, preferably in two axial directions.
From the viewpoint of excellent transparency, rigidity, and heat resistance, the base layer 101 is preferably a biaxially stretched film formed from one or more thermoplastic resins selected from the group consisting of polypropylene, polyethylene terephthalate, polyethylene naphthalate, polyamide, polyimide, and polybutylene terephthalate, and more preferably a biaxially stretched film formed from one or more thermoplastic resins selected from the group consisting of polyamide, polyethylene terephthalate, and polybutylene terephthalate.

The surface of the base layer 101 may be coated with polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, acrylic resin, urethane resin, or the like.
Furthermore, the base layer 101 may be subjected to a surface treatment in order to improve adhesion to the gas barrier layer 103. Specifically, the surface of the base layer 101 facing the gas barrier layer 103 may be subjected to a surface activation treatment such as corona treatment, flame treatment, plasma treatment, or primer coating treatment.

From the viewpoint of obtaining good film properties, the thickness of the substrate layer 101 is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and is preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 300 μm or less.

(Inorganic layer)
The gas barrier laminate of this embodiment preferably further includes an inorganic layer 102 provided between the base layer 101 and the gas barrier layer 103 .
Examples of inorganic materials that make up the inorganic layer 102 include metals, metal oxides, metal nitrides, metal fluorides, and metal oxynitrides that can form thin films having barrier properties.
Examples of inorganic materials constituting the inorganic material layer 102 include one or more selected from the group consisting of simple substances, oxides, nitrides, fluorides, and oxynitrides of elements from Group 2A of the periodic table, such as beryllium, magnesium, calcium, strontium, and barium; transition elements from the periodic table, such as titanium, zirconium, ruthenium, hafnium, and tantalum; elements from Group 2B of the periodic table, such as zinc; elements from Group 3A of the periodic table, such as aluminum, gallium, indium, and thallium; elements from Group 4A of the periodic table, such as silicon, germanium, and tin; and elements from Group 6A of the periodic table, such as selenium and tellurium.
In this embodiment, the group names of the periodic table for the inorganic layer 102 are shown in the old CAS format.

Furthermore, among the above inorganic substances, one or more inorganic substances selected from the group consisting of silicon oxide, aluminum oxide, and aluminum are preferred, with aluminum oxide being more preferred, as they have an excellent balance of barrier properties, cost, and the like.
The silicon oxide may contain silicon monoxide and silicon suboxide in addition to silicon dioxide.

The inorganic layer 102 is formed from the above-mentioned inorganic material. The inorganic layer 102 preferably includes an aluminum oxide layer made of aluminum oxide, since it has an excellent balance between barrier properties, cost, and the like.
The inorganic layer 102 may be composed of a single inorganic layer or may be composed of multiple inorganic layers. Furthermore, when the inorganic layer 102 is composed of multiple inorganic layers, the inorganic layers may be of the same type or different types.

From the viewpoint of a balance between improved barrier properties and improved ease of handling, the thickness of the inorganic layer 102 is, for example, 1 nm or more, preferably 4 nm or more, and is, for example, 1000 nm or less, preferably 500 nm or less, more preferably 100 nm or less, even more preferably 50 nm or less, even more preferably 30 nm or less, even more preferably 15 nm or less, and even more preferably 10 nm or less.
Here, the thickness of the inorganic layer 102 can be determined from an image observed using, for example, a transmission electron microscope or a scanning electron microscope.

The method for forming the inorganic layer 102 is not limited, and the inorganic layer 102 can be formed on one or both sides of the substrate layer 101 by, for example, vacuum deposition, ion plating, sputtering, chemical vapor deposition, physical vapor deposition (CVD), plasma CVD, sol-gel, or the like. Among these, film formation under reduced pressure by sputtering, ion plating, chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma CVD, or the like is preferred. This is expected to improve the surface smoothness of the inorganic layer 102 and reduce pores by rapidly reacting with chemically active molecular species containing silicon, such as silicon nitride or silicon oxynitride. To rapidly carry out these bonding reactions, it is desirable for the inorganic atoms or compounds to be chemically active molecular or atomic species.
In order to improve the balance between the barrier properties of the gas barrier laminate and productivity, the inorganic layer 102 is preferably a vapor-deposited film.

From the perspective of improving the balance between the barrier properties and productivity of the gas barrier laminate, the inorganic layer 102 is a vapor-deposited film provided on the base layer 101, or, if an intervening layer is present between the base layer 101 and the inorganic layer 102, on such an intervening layer. The inorganic layer 102 is composed of one or more inorganic materials selected from the group consisting of silicon oxide, aluminum oxide, and aluminum, and is preferably composed of aluminum oxide.

(Undercoat layer)
An undercoat layer may be provided between the substrate layer 101 and the inorganic layer 102, but it is preferable not to provide an undercoat layer, as the gas barrier coating material in this embodiment has sufficient barrier properties even without an undercoat layer and productivity is improved by omitting the process of providing an undercoat layer.

When an undercoat layer is provided, from the viewpoint of improving adhesion between the substrate layer 101 and the inorganic layer 102, examples of materials for the undercoat layer include one or more selected from the group consisting of polyurethane resin, polyester resin, oxazoline resin, and (meth)acrylic resin.

Examples of polyurethane resins include various polyurethane resins, polyurethane polyurea resins, and prepolymers thereof. Specific examples of such urethane resins include reaction products of diisocyanate components such as tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, and dicyclohexyl diisocyanate with diol components such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, bisphenol, polyester diol, polyether diol, polycarbonate diol, and polyethylene glycol; and reaction products of urethane prepolymers having isocyanate groups at their terminals with amino compounds, aminosulfonates, polyhydroxycarboxylic acids, bisulfites, and the like.

Examples of polyester resins used in the undercoat layer include various polyester resins and their modified products. Specific examples of such polyester resins include reaction products of polycarboxylic acid components such as terephthalic acid, phthalic acid, isophthalic acid, trimellitic acid, pyromellitic acid, 2-sulfoisophthalic acid, 5-sulfoisophthalic acid, adipic acid, sebacic acid, succinic acid, and dodecanedioic acid with diol components such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, and bisphenol, as well as modified products with acrylic resins, epoxy resins, etc.

When an oxazoline resin is used in the undercoat layer, the undercoat layer is preferably composed of an oxazoline-based resin composition containing an oxazoline group-containing aqueous polymer, an aqueous (meth)acrylic resin, and an aqueous polyester resin.

From the viewpoint of obtaining good adhesion, the thickness of the undercoat layer is preferably 0.001 μm or more, more preferably 0.005 μm or more, even more preferably 0.01 μm or more, even more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and even more preferably 0.2 μm or more.
From an economical viewpoint, the thickness of the undercoat layer is preferably 1.0 μm or less, more preferably 0.6 μm or less, and even more preferably 0.5 μm or less, and may be, for example, 0.4 μm or less, or, for example, 0.3 μm or less.

(Adhesive layer)
The gas barrier laminate may further be provided with an adhesive layer.
The adhesive layer is provided, for example, between the gas barrier layer 103 and an upper layer of the gas barrier layer 103. When the upper layer is formed from a plurality of layers, an adhesive layer may be provided between the plurality of layers. Here, the upper layer of the gas barrier layer 103 refers to a layer laminated on the surface of the gas barrier layer 103 opposite the surface facing the inorganic layer 102.
The adhesive layer may contain any known adhesive. Examples of adhesives include laminating adhesives composed of organic titanium resins, polyethyleneimine resins, urethane resins, epoxy resins, acrylic resins, polyester resins, oxazoline group-containing resins, modified silicone resins, alkyl titanates, polyester polybutadienes, etc., as well as one-component and two-component polyols and polyisocyanates, water-based urethanes, ionomers, etc. Alternatively, aqueous adhesives whose main raw materials are acrylic resins, vinyl acetate resins, urethane resins, polyester resins, etc. may be used.
Furthermore, other additives such as a curing agent and a silane coupling agent may be added to the adhesive depending on the application of the gas barrier laminate 100. When the gas barrier laminate is intended for use in hot water treatment such as retort, from the viewpoint of heat resistance and water resistance, a dry lamination adhesive such as a polyurethane adhesive is preferred, and a solvent-based two-component curing polyurethane adhesive is more preferred.

(Method for producing gas barrier laminate)
In this embodiment, the method for manufacturing the gas barrier laminate 100 includes, for example, a step of preparing a base material layer 101, a step of forming an inorganic layer 102 on the base material layer 101, and a step of forming a gas barrier layer 103 on top of the base material layer 101 on which the inorganic layer 102 has been formed.

The process of forming the inorganic layer 102 on the substrate layer 101 can use, for example, the method for forming the inorganic layer 102 described above.

The process of forming the gas barrier layer 103 includes, for example, a step of applying a gas barrier coating material to the inorganic layer 102 and then drying it to obtain a coating layer, and a step of heating the coating layer to cause a dehydration condensation reaction between the carboxyl groups contained in the polycarboxylic acid and the amino groups contained in the polyamine compound, thereby forming the gas barrier layer 103 having an amide bond.

The method for applying the gas barrier coating material to the inorganic layer 102 is not limited, and conventional methods can be used. Examples include coating methods using known coating machines such as a Mayer bar coater, air knife coater, direct gravure coater, gravure offset coater, arc gravure coater, gravure reverse coater, and jet nozzle type gravure coater, reverse roll coater such as a top feed reverse coater, bottom feed reverse coater, and nozzle feed reverse coater, five-roll coater, lip coater, bar coater, bar reverse coater, and die coater.

The drying and heat treatment may be carried out after drying, or may be carried out simultaneously.
The drying and heat treatment methods are not limited as long as they achieve the effects of the present invention, and may be any method capable of curing the gas barrier coating material and heating the cured gas barrier coating material. Examples include convective heat transfer using ovens, dryers, etc., conductive heat transfer using heated rolls, etc., radiative heat transfer using electromagnetic waves such as infrared, far-infrared, and near-infrared heaters, and internal heat generation using microwaves, etc. From the perspective of manufacturing efficiency, devices capable of both drying and heat treatment are preferred for use in drying and heat treatment. Specifically, hot air ovens are preferred because they can be used for various applications such as drying, heating, and annealing, and heated rolls are preferred because of their excellent heat conduction efficiency to the film. Alternatively, the methods used for drying and heat treatment may be combined as appropriate. Specifically, a hot air oven and a heated roll may be used in combination. For example, drying the gas barrier coating material in a hot air oven and then heat treatment with a heated roll shortens the heat treatment process, which is preferable from the perspective of manufacturing efficiency. Alternatively, it is preferable to perform drying and heat treatment using only a hot air oven.

The heat treatment conditions are, for example, a heat treatment temperature of 80 to 180°C and a heat treatment time of 1 second to 5 minutes, preferably a heat treatment temperature of 90 to 160°C and a heat treatment time of 10 seconds to 3 minutes, more preferably a heat treatment temperature of 100 to 150°C and a heat treatment time of 15 seconds to 2 minutes, and even more preferably a heat treatment temperature of 110 to 140°C and a heat treatment time of 30 to 90 seconds. Furthermore, as described above, the use of a heating roll in combination enables heat treatment in a short time.
In order to effectively promote the dehydration condensation reaction between the -COO- group contained in the polycarboxylic acid and the amino group contained in the polyamine compound, it is important to adjust the heat treatment temperature and heat treatment time according to the coating amount of the gas barrier coating material.

When the gas barrier coating material is dried and heat-treated, the carboxyl groups of the polycarboxylic acid react with the polyamine and Zn compound, forming covalent bonds and ionic crosslinks, forming a gas barrier layer 103 that maintains good gas barrier properties even after retort processing.

In this embodiment, the gas barrier laminate has excellent gas barrier performance and can be suitably used, for example, as a packaging material, particularly as a food packaging material for contents that require high gas barrier properties, as well as a variety of other packaging materials for medical, industrial, and everyday miscellaneous uses.

The gas barrier laminate of this embodiment can also be suitably used, for example, as a vacuum insulation film; a sealing film for sealing electroluminescence elements, solar cells, etc., which require high barrier performance.

In this embodiment, specific examples of the laminate structure including the gas barrier laminate are shown below.
(Layer Structure Example 1) Base material layer 101 (PET base material)/gas barrier layer 103/adhesive layer/polyolefin layer (Layer Structure Example 2) Base material layer 101 (PET base material)/inorganic material layer 102 (alumina vapor-deposited layer)/gas barrier layer 103/adhesive layer/polyolefin layer (Layer Structure Example 3) Base material layer 101 (PET base material)/inorganic material layer 102 (alumina vapor-deposited layer)/gas barrier layer 103/adhesive layer/polyamide layer/adhesive layer/polyolefin layer Here, by including a polyolefin layer composed of a polyolefin such as polyethylene, polypropylene, poly(4-methyl-1-pentene), or poly(1-butene) in the laminate structure, the gas barrier laminate can have good pinhole resistance, tear resistance, heat resistance, etc., while further suppressing deterioration in gas barrier performance under high humidity and after retort treatment.

The above describes embodiments of the present invention with reference to the drawings, but these are merely examples of the present invention, and various configurations other than those described above can also be adopted.

The present embodiment will be described in detail below with reference to examples and comparative examples. Note that the present embodiment is not limited in any way to the descriptions of these examples.

Example 1
(1) Preparation of Gas Barrier Coating Material Polyacrylic acid (manufactured by Toagosei Co., Ltd., product name: AC-10H, weight average molecular weight: 800,000) was mixed with 10% by mass of aqueous ammonia (manufactured by Wako Pure Chemical Industries, Ltd.) and purified water so that the ammonia concentration was 250 equivalent % relative to the carboxyl groups of the polyacrylic acid to obtain an aqueous solution of ammonium polyacrylate with a concentration of 7.29% by mass.
Next, zinc oxide (manufactured by Kanto Chemical Co., Inc.) and ammonium carbonate were added to the resulting aqueous ammonium polyacrylate solution, and the mixture was stirred to prepare a mixed solution (A). The amount of zinc oxide added was such that the ratio (number of moles of zinc oxide in the gas barrier coating material) / (number of moles of -COO- groups contained in polyacrylic acid in the gas barrier coating material) (hereinafter also referred to as "ZnO/PAA") was the value shown in Table 1. The amount of ammonium carbonate added was such that the ratio (number of moles of carbonate-based ammonium salt in the gas barrier coating material) / (number of moles of zinc oxide in the gas barrier coating material) was 1.5.
Next, purified water was added to polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., product name: SP-200, number average molecular weight: 10,000) to obtain a 10% polyethyleneimine aqueous solution.
Next, the mixed solution (A) and the polyethyleneimine aqueous solution were mixed in a ratio such that the ratio of (the number of moles of amino groups contained in the polyethyleneimine in the gas barrier coating material)/(the number of moles of -COO- groups contained in the polyacrylic acid in the gas barrier coating material) (hereinafter also referred to as "PEI/PAA") was the value shown in Table 1 to prepare a mixed solution (B).
Furthermore, purified water was added to the mixed solution (B) so that the solid content concentration of the mixed solution (B) became 1.5% by mass, and the mixture was stirred until a uniform solution was obtained. After that, a surfactant (polyoxyethylene lauryl ether, manufactured by Kao Corporation, trade name: Emulgen 120) was mixed in so that the concentration of the solid content of the mixed solution (B) became 0.3% by mass, thereby preparing a gas barrier coating material.

Example 2
Gas barrier coating materials were prepared in accordance with Example 1, except that the amount of zinc oxide added was changed so that the ZnO/PAA ratio would be the value shown in Table 1.

(Comparative Examples 1 and 2)
Gas barrier coating materials were prepared in accordance with Example 1, except that the amount of zinc oxide added was changed so that the ZnO/PAA ratio would be the value shown in Table 1.
In this case, ZnO/PAA being 0 means that zinc oxide was not added.

Example 3
Polyacrylic acid (manufactured by Toagosei Co., Ltd., product name: AC-10H, weight average molecular weight: 800,000), 10 mass % aqueous ammonia (manufactured by Wako Pure Chemical Industries, Ltd.), and purified water were mixed so that the ammonia concentration was 250 equivalent % relative to the carboxyl groups of the polyacrylic acid, thereby obtaining an aqueous ammonium polyacrylate solution with a concentration of 7.29 mass %.
Next, zinc oxide (manufactured by Kanto Chemical Co., Inc.) and ammonium carbonate were added to the obtained aqueous ammonium polyacrylate solution, and the mixture was stirred to prepare a mixed solution (A). The amount of zinc oxide added was such that the ZnO/PAA ratio was as shown in Table 1. The amount of ammonium carbonate added was such that the ratio (moles of carbonate-based ammonium salt in the gas barrier coating material)/(moles of zinc oxide in the gas barrier coating material) was 1.5.
Next, purified water was added to polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., product name: SP-200, number average molecular weight: 10,000) to obtain a 10% polyethyleneimine aqueous solution.
Furthermore, purified water was added to diammonium hydrogen phosphate ((NH ₄ ) ₂ HPO ₄ manufactured by Kanto Chemical Co., Inc.) to prepare a 10% by mass diammonium hydrogen phosphate solution.
Next, the mixed solution (A), the polyethyleneimine aqueous solution, and the diammonium hydrogen phosphate solution as a phosphorus introduction source were mixed in a ratio such that PEI/PAA was the value shown in Table 1, and (the number of moles of P contained in the phosphorus compound or its salt in the gas barrier coating material)/(the number of moles of -COO- groups contained in the polyacrylic acid in the gas barrier coating material) (hereinafter also referred to as "P/PAA") was the value shown in Table 1, to prepare mixed solution (B).
Furthermore, purified water was added to the mixed solution (B) so that the solid content concentration of the mixed solution (B) became 1.5% by mass, and the mixture was stirred until a uniform solution was obtained. After that, a surfactant (polyoxyethylene lauryl ether, manufactured by Kao Corporation, trade name: Emulgen 120) was mixed in so that the concentration of the solid content of the mixed solution (B) became 0.3% by mass, thereby preparing a gas barrier coating material.

Example 4
Gas barrier coating materials were prepared in accordance with Example 3, except that the amount of diammonium hydrogen phosphate solution added was changed so that the P/PAA values shown in Table 1 were obtained.

Example 5
Low-polymerized ammonium polyphosphate (manufactured by Amada Co., Ltd., product number: water-soluble ammonium polyphosphate flame retardant NNA20, P ₂ O ₅ content 59%) was added to purified water to prepare a 25% by mass low-polymerized ammonium polyphosphate solution.
Gas barrier coating materials were prepared in accordance with Example 3, except that the above-mentioned low-polymerized ammonium polyphosphate solution was used as the phosphorus introduction source instead of the above-mentioned diammonium hydrogen phosphate solution, and mixed in a ratio such that (the number of moles of P contained in the polyphosphate compound or its salt in the gas barrier coating material) / (the number of moles of -COO- groups contained in the polyacrylic acid in the gas barrier coating material) (hereinafter also referred to as "P/PAA") was the value shown in Table 1.

(Examples 6 and 7)
Gas barrier coating materials were prepared in accordance with Example 5, except that the amount of low-polymerized ammonium polyphosphate solution added was changed so that the P/PAA ratio would be the value shown in Table 1.

(Example 8)
A gas barrier coating material was prepared in accordance with Example 6, except that the amount of zinc oxide added was changed so that the ZnO/PAA ratio would be the value shown in Table 1, and an epoxy silane compound (manufactured by Shin-Etsu Silicones Co., Ltd., product number: KBM-403) was mixed as a crosslinking agent into the mixed liquid (B) so that the amount was 0.020 mass % relative to the solid content of the mixed liquid (B).

Example 9
A gas barrier coating material was prepared in accordance with Example 8, except that a carbodiimide compound (manufactured by Nisshinbo Chemical Inc., product number: Carbodilite SV-02) was used as the crosslinking agent instead of epoxysilane.

Example 10
A gas barrier coating material was prepared in accordance with Example 8, except that an isocyanate compound (manufactured by Mitsui Chemicals, Inc., product number: Takenate (registered trademark) WD726) was used as the crosslinking agent instead of epoxysilane.

Example 11
A gas barrier coating material was prepared in accordance with Example 8, except that the amount of low-polymerized ammonium polyphosphate solution added was changed so that the P/PAA would be the value shown in Table 1, and the amount of crosslinking agent added was changed to 0.015 mass%.

[Preparation of gas barrier laminate]
(Preparation of Gas Barrier Laminate 1)
A 12 μm thick biaxially oriented polyethylene terephthalate film (PET12, manufactured by Unitika Ltd.) was used as the substrate, and the gas barrier coating material obtained in each Example and Comparative Example was applied to its corona-treated surface using a Mayer bar so that the coating thickness after drying would be 0.3 μm. This was then heat-treated in a hot air dryer at 130°C for 60 seconds. This resulted in a gas barrier laminate 1.

(Preparation of Gas Barrier Laminate 2)
A 12 μm-thick biaxially oriented polyethylene terephthalate film (PET12, manufactured by Unitika Ltd.) was used as a substrate. Aluminum was heated and evaporated on the corona-treated surface using high-frequency induction heating, followed by deposition while introducing oxygen, to form a 7 nm-thick aluminum oxide film. This resulted in an aluminum oxide-deposited PET film. The water vapor permeability of this aluminum oxide-deposited PET film was 1.5 g/( ^m² ·24 h).
Next, a gas barrier coating material was applied onto the vapor deposition layer using a Mayer bar so that the coating thickness after drying would be 0.3 μm, and the coating material was heat-treated using a hot air dryer at 130°C for 60 seconds to obtain a gas barrier laminate 2.

[Preparation of test film]
(Preparation of Test Film 1)
An ester-based adhesive (9 parts by mass of a polyurethane-based adhesive (Mitsui Chemicals, Inc., product name: Takelac A525S), 1 part by mass of an isocyanate-based curing agent (Mitsui Chemicals, Inc., product name: Takenate A50), and 7.5 parts by mass of ethyl acetate) was applied to one side of a 70 μm-thick unstretched polypropylene film (manufactured by Mitsui Chemicals, Inc., product name: RXC-22). Next, the barrier surface (the surface coated with the gas barrier coating material) of the gas barrier laminate 1 obtained in each Example and Comparative Example was bonded to the adhesive-coated side of the unstretched polypropylene film, thereby obtaining a test film 1 before retort treatment.

(Preparation of Test Film 2)
An ester-based adhesive (9 parts by mass of a polyurethane-based adhesive (Mitsui Chemicals, Inc., product name: Takelac A525S), 1 part by mass of an isocyanate-based curing agent (Mitsui Chemicals, Inc., product name: Takenate A50), and 7.5 parts by mass of ethyl acetate) was applied to one side of a 70 μm-thick unstretched polypropylene film (manufactured by Mitsui Chemicals, Inc., product name: RXC-22). Next, the barrier surface (the surface coated with the gas barrier coating material) of the gas barrier laminate 2 obtained in each Example and Comparative Example was bonded to the adhesive-coated side of the unstretched polypropylene film, thereby obtaining a test film 2 before retort treatment.

(Preparation of Test Film 3)
An ester-based adhesive (9 parts by mass of a polyurethane-based adhesive (manufactured by Mitsui Chemicals, Inc., product name: Takelac A525S), 1 part by mass of an isocyanate-based curing agent (manufactured by Mitsui Chemicals, Inc., product name: Takenate A50), and 7.5 parts by mass of ethyl acetate) was applied to both sides of a 15 μm-thick nylon film (manufactured by Unitika Ltd., product name: Emblem ONBC). Next, the barrier surface (the surface coated with the gas barrier coating material) of the gas barrier laminate 2 obtained in each Example and Comparative Example and a 60 μm-thick unstretched polypropylene film (manufactured by Mitsui Chemicals Tocello, Inc., product name: RXC-22) were bonded to both sides of the nylon film to which the adhesive had been applied, respectively, to obtain a test film 3 before retort treatment.

[Evaluation method]
(Retort processing (filled with water))
The test films 1 to 3 obtained in the above [Preparation of test films] before retort treatment were folded back so that the unstretched polypropylene film was on the inner surface, and two sides were heat-sealed to form a bag. Then, 70 mL of water was added as the contents, and the other side was heat-sealed to form a bag. This was subjected to retort treatment in a high-temperature, high-pressure retort sterilizer at 130°C for 30 minutes. After retort treatment, the water in the contents was drained, and test films 1 to 3 after retort treatment (filled with water) were obtained.

(Oxygen permeability [mL/( ^m2・day・MPa)])
The oxygen transmission rates of Test Films 1 and 2 obtained by the above method before retort treatment and Test Films 1 to 3 after retort treatment (filled with water) were measured using an OX-TRAN2/21 manufactured by Mocon Co., Ltd. in accordance with JIS K 7126 at a temperature of 20°C and a humidity of 90% RH. The results are shown in Table 1. In the table, oxygen transmission rate [mL/( ^m2 ·day·MPa)] is referred to as OTR.

(Water vapor permeability [g/( ^m2・day)])
Test films 1-2 before retort treatment and test films 1-3 after retort treatment (filled with water) obtained by the above-mentioned method were stacked with the unstretched polypropylene film facing the inside, and the gas barrier laminate film was folded back and heat-sealed on three sides to form a bag. Calcium chloride was then placed inside the bag, and the other side was heat-sealed to create a bag with a surface area of 0.01 ^m2 . The bag was left at 40°C and 90% RH for 300 hours, and the water vapor transmission rate was measured based on the weight difference. The results are shown in Table 1. In the table, water vapor transmission rate [g/( ^m2 ·day)] is referred to as WVTR.

(Laminate film immersion test)
Test films 1 to 3 obtained in the above "Preparation of Test Films" were folded over so that the unstretched polypropylene film was on the inside and heat-sealed to form a bag. The bag-shaped test film was immersed in alkaline detergent JOY (registered trademark) (manufactured by P&G) diluted 10 times with tap water. After one week, the test film was visually inspected to evaluate the occurrence of delamination. The results are shown in Table 1.
A: No delamination occurred B: Delamination occurred

As can be seen from Table 1, in each Example, a gas barrier material with a better balance between productivity and barrier properties could be obtained by heat treatment at a lower temperature for a shorter period of time than in each Comparative Example.
Furthermore, the addition of a polyphosphate compound could further improve the water vapor permeability.
Furthermore, the addition of a crosslinking agent improved the alkali resistance of the laminate film.

100 Gas barrier laminate 101 Base layer 102 Inorganic layer 103 Gas barrier layer

Claims (11)

A gas barrier coating material comprising a polycarboxylic acid, a polyamine compound, a Zn compound , and a crosslinking agent ,
The gas barrier coating material has a ratio of (the number of moles of Zn compounds in the gas barrier coating material)/(the number of moles of -COO- groups contained in polycarboxylic acid in the gas barrier coating material) of 0.40 or more and 0.70 or less. The gas barrier coating material according to claim 1 ,
The gas barrier coating material, wherein the crosslinking agent comprises one or more compounds selected from the group consisting of epoxysilane compounds, carbodiimide compounds, and isocyanate compounds. The gas barrier coating material according to claim 1 or 2 ,
The gas barrier coating material, wherein the polycarboxylic acid comprises one or more compounds selected from the group consisting of polyacrylic acid, polymethacrylic acid, and a copolymer of acrylic acid and methacrylic acid. The gas barrier coating material according to claim 1 or 2 ,
The gas barrier coating material, wherein the polyamine compound comprises one or more compounds selected from the group consisting of polyallylamine, polyvinylamine, polyethyleneimine, and poly(trimethyleneimine). The gas barrier coating material according to claim 1 or 2 ,
The gas barrier coating material further comprises a polyphosphate compound or a salt thereof. The gas barrier coating material according to claim 5 ,
The gas barrier coating material has a ratio of (the number of moles of P contained in the polyphosphate compound or salt thereof in the gas barrier coating material)/(the number of moles of -COO- groups contained in the polycarboxylic acid in the gas barrier coating material) of 0.005 or more and 0.20 or less. The gas barrier coating material according to claim 1 or 2 ,
The gas barrier coating material has a ratio of (the number of moles of amino groups contained in the polyamine compound in the gas barrier coating material)/(the number of moles of -COO- groups contained in the polycarboxylic acid in the gas barrier coating material) of 0.40 or more and 0.70 or less. A substrate layer and a gas barrier layer provided on at least one surface of the substrate layer,
A gas barrier laminate, wherein the gas barrier layer comprises a cured product of the gas barrier coating material according to claim 1 or 2 . The gas barrier laminate according to claim 8 ,
The gas barrier layer has a thickness of 0.05 μm or more and 10 μm or less. The gas barrier laminate according to claim 8 ,
The gas barrier laminate further comprises an inorganic layer provided between the base layer and the gas barrier layer. The gas barrier laminate according to claim 10 ,
a gas barrier laminate, wherein the inorganic layer is a vapor-deposited film provided on the base layer, or, when an intervening layer is present between the base layer and the inorganic layer, on the intervening layer, and is composed of one or more inorganic materials selected from the group consisting of silicon oxide, aluminum oxide, and aluminum.