Technical Field
[0001] The present invention relates to a gas barrier laminate and a
packaging bag.
Background Art
[0002] In many fields such as foods, beverages, pharmaceuticals, and
10 chemicals, various packaging materials are used according to the
contents of each product. Packaging materials are required to have
properties for preventing transmission of oxygen, water vapor, and the
like (gas barrier properties), which cause degeneration of the contents.
[0003] In recent years, in view of growing environmental awareness
15 stemming from marine plastic debris problems and the like, the
momentum toward plastic reduction is building up. From the
viewpoint of reducing the amount of use of plastic materials, it has been
investigated to use paper instead of plastic materials in a variety of
fields. For example, in the following Patent Literature 1, a gas barrier
20 laminate in which barrier layers are laminated on paper is disclosed.
Citation List
Patent Literature
[0004] Patent Literature 1: Japanese Unexamined Patent Publication
No. 2020-69783
25 Summary of Invention
Technical Problem
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[0005] Since paper has crease retaining properties (also referred to as
dead holding properties), paper has a feature that processing is easy.
However, according to an investigation of the inventors of the present
invention, it has been found that in a case where packaging bags having
5 more acute-angled creases (pillow packaging, three-sided seal
packaging, and gusset packaging) are used, there is still room for
improvement from the viewpoint that cracks are generated in the barrier
layer so that the gas barrier properties are deteriorated.
[0006] Furthermore, from the viewpoint of the Law for Promotion of
10 Effective Utilization of Resources, it has been required to reduce the
amount of use of plastic materials even in gas barrier laminates.
[0007] The present invention was achieved in view of the
above-described circumstances, and it is an object of the invention to
provide a gas barrier laminate that has crease retaining properties, which
15 is a feature of paper, has sufficient gas barrier properties even after
being folded, and contributes to a reduction in the amount of use of
plastic materials, and to provide a packaging bag including this gas
barrier laminate.
Solution to Problem
20 [0008] The present invention provides a gas barrier laminate including:
a paper substrate; an anchor coat layer including a first polyolefin
having a polar group; a vapor-deposited layer; and an overcoat layer
including a second polyolefin having a polar group, in order, in which
the gas barrier laminate includes a layer including a polyvinyl
25 alcohol-based resin between the paper substrate and the anchor coat
layer or between the anchor coat layer and the vapor-deposited layer.
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[0009] A first polyolefin having a polar group may have at least one
selected from a carboxyl group, a salt of a carboxyl group, a carboxylic
acid anhydride group, and a carboxylic acid ester.
[0010] A second polyolefin having a polar group may have at least one
5 selected from a carboxyl group, a salt of a carboxyl group, a carboxylic
acid anhydride group, and a carboxylic acid ester.
[0011] The first polyolefin having a polar group may be a copolymer of
an acrylic acid ester and maleic anhydride.
[0012] The first polyolefin having a polar group may be an
10 ethylene-vinyl acetate copolymer.
[0013] The first polyolefin having a polar group may be an
ethylene-glycidyl methacrylate copolymer.
[0014] The second polyolefin having a polar group may be a copolymer
of an acrylic acid ester and maleic anhydride.
15 [0015] The second polyolefin having a polar group may be an
ethylene-vinyl acetate copolymer.
[0016] The second polyolefin having a polar group may be an
ethylene-glycidyl methacrylate copolymer.
[0017] A thickness of the anchor coat layer may be 1 m or more and 5
20 m or less.
[0018] A thickness of the layer including the polyvinyl alcohol-based
resin may be 1 m or more and 5 m or less.
[0019] A thickness of the vapor-deposited layer may be 30 nm or more
and 100 nm or less.
25 [0020] A thickness of the overcoat layer may be 2 m or more and 10
m or less.

CLAIMS
1. A gas barrier laminate comprising, in following order:
a paper substrate;
an anchor coat layer including a first polyolefin having a polar
5 group;
a vapor-deposited layer; and
an overcoat layer including a second polyolefin having a polar
group,
wherein the gas barrier laminate including a layer including a
10 polyvinyl alcohol-based resin between the paper substrate and the
anchor coat layer or between the anchor coat layer and the
vapor-deposited layer.
2. The gas barrier laminate according to claim 1, wherein the first
polyolefin having a polar group has at least one selected from a
15 carboxyl group, a salt of a carboxyl group, a carboxylic acid anhydride
group, and a carboxylic acid ester.
3. The gas barrier laminate according to claim 1 or 2, wherein the
second polyolefin having a polar group has at least one selected from a
carboxyl group, a salt of a carboxyl group, a carboxylic acid anhydride
20 group, and a carboxylic acid ester.
4. The gas barrier laminate according to claim 1, wherein the first
polyolefin having a polar group is a copolymer of an acrylic acid ester
and maleic anhydride.
5. The gas barrier laminate according to claim 1, wherein the first
25 polyolefin having a polar group is an ethylene-vinyl acetate copolymer.
6. The gas barrier laminate according to claim 1, wherein the first
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polyolefin having a polar group is an ethylene-glycidyl methacrylate
copolymer.
7. The gas barrier laminate according to any one of claims 1 to 6,
wherein the second polyolefin having a polar group is a copolymer of an
5 acrylic acid ester and maleic anhydride.
8. The gas barrier laminate according to any one of claims 1 to 6,
wherein the second polyolefin having a polar group is an ethylene-vinyl
acetate copolymer.
9. The gas barrier laminate according to any one of claims 1 to 6,
10 wherein the second polyolefin having a polar group is an
ethylene-glycidyl methacrylate copolymer.
10. The gas barrier laminate according to any one of claims 1 to 9,
wherein a thickness of the anchor coat layer is 1 m or more and 5 m
or less.
15 11. The gas barrier laminate according to any one of claims 1 to 10,
wherein a thickness of the layer including a polyvinyl alcohol-based
resin is 1 m or more and 5 m or less.
12. The gas barrier laminate according to any one of claims 1 to 11,
wherein a thickness of the vapor-deposited layer is 30 nm or more and
20 100 nm or less.
13. The gas barrier laminate according to any one of claims 1 to 13,
wherein a thickness of the overcoat layer is 2 m or more and 10 m or
less.