Technical Field
[0001] The present invention relates to a gas 5 barrier laminate and a
packaging bag.
Background Art
[0002] In many fields such as foods, beverages, pharmaceuticals, and
chemicals, various packaging materials are used according to the contents
10 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
stemming from marine plastic debris problems and the like, the
15 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 laminate in
which barrier layers are laminated on paper is disclosed.
20 Citation List
Patent Literature
[0004] Patent Literature 1: Japanese Unexamined Patent Publication No.
2020-69783
Summary of Invention
25 Technical Problem
[0005] Since paper has crease retaining properties (also referred to as
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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
more acute-angled creases (pillow packaging, three-sided seal packaging,
and gusset packaging) are used, there is still room 5 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
Effective Utilization of Resources, it has been required to reduce the
10 amount of use of plastic materials even in gas barrier laminates.
[0007] The present invention was achieved in view of the abovedescribed
circumstances, and it is an object of the invention to provide a
gas barrier laminate that has crease retaining properties, which is a feature
of paper, has sufficient gas barrier properties even after being folded, and
15 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
[0008] The present invention provides a gas barrier laminate including:
a paper substrate; an anchor coat layer including a first polyolefin having
20 a polar group; a vapor-deposited layer; and an overcoat layer including a
second polyolefin having a polar group, in order.
[0009] The 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.
25 [0010] The second polyolefin having a polar group may have at least one
selected from a carboxyl group, a salt of a carboxyl group, a carboxylic
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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 ethylenevinyl
5 acetate copolymer.
[0013] The first polyolefin having a polar group may be an ethyleneglycidyl
methacrylate copolymer.
[0014] The second polyolefin having a polar group may be a copolymer
of an acrylic acid ester and maleic anhydride.
10 [0015] The second polyolefin having a polar group may be an ethylenevinyl
acetate copolymer.
[0016] The second polyolefin having a polar group may be an ethyleneglycidyl
methacrylate copolymer.
[0017] A thickness of the anchor coat layer may be 1 m or more.
15 [0018] A weight of paper may be 50% by mass or more based on the
entire gas barrier laminate.
[0019] The present invention also provides a packaging bag including
the above-described gas barrier laminate according to the present
invention.
20 [0020] The packaging bag may have a crease.
Advantageous Effects of Invention
[0021] According to the present invention, a gas barrier laminate that has
crease retaining properties, which is a feature of paper, has sufficient gas
barrier properties even after being folded, and contributes to a reduction
25 in the amount of use of plastic materials, and a packaging bag including
this gas barrier laminate can be provided.
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Brief Description of Drawings
[0022] FIG. 1 is a schematic cross-sectional view illustrating a gas
barrier laminate according to an embodiment of the present invention.
FIG. 2 is a perspective view illustrating a packaging bag
according to an embodiment of the 5 present invention.
Description of Embodiments
[0023] Hereinafter, embodiments of the present invention will be
described in detail with reference to the drawings as necessary.
However, the present invention is not intended to be limited to the
10 following embodiments.
[0024]
FIG. 1 is a schematic cross-sectional view illustrating a gas
barrier laminate according to an embodiment. A gas barrier laminate 10
according to an embodiment includes a paper substrate 1, an anchor coat
15 layer 2, a vapor-deposited layer 3, and an overcoat layer 4, in order. The
anchor coat layer 2 includes a first polyolefin having a polar group, and
the overcoat layer 4 includes a second polyolefin having a polar group.
[0025] [Paper substrate]
The paper substrate 1 is not particularly limited and may be
20 appropriately selected according to the use application of the packaging
bag to which the gas barrier laminate 10 is applied. The paper substrate
1 is not particularly restricted as long as it is a paper containing plantderived
pulp as a main component. Specific examples of the paper
substrate 1 include high-quality paper, special high-quality paper, coated
25 paper, art paper, cast coated paper, imitation vellum paper, kraft paper,
and glassine paper. The thickness of the paper substrate 1 may be, for
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example, 20 to 500 g/m2 or 30 to 100 g/m2.
[0026] The paper substrate 1 may be provided with at least a coat layer
on the side that is in contact with the anchor coat layer 2 that will be
described below. By providing a coat layer, the anchor coat layer 2 can
be prevented from sinking into the paper, and 5 the coat layer can
accomplish a role of a sealer embedding the surface unevenness of the
paper so that the anchor coat layer can be uniformly formed without
defects. In the coat layer, for example, various copolymers such as a
styrene-butadiene-based copolymer, a styrene-acrylic copolymer, and an
10 ethylene-vinyl acetate-based copolymer; a polyvinyl alcohol-based resin,
a cellulose-based resin, and paraffin (WAX) are used as binder resins, and
clay, kaolin, calcium carbonate, talc, and mica may be included as fillers.
[0027] The thickness of the coat layer is not particularly restricted;
however, the thickness may be, for example, 1 to 10 m or 3 to 8 m.
15 [0028] The weight of the paper is preferably 50% by mass or more, more
preferably 70% by mass or more, and even more preferably 80% by mass
or more, based on the entire gas barrier laminate. When the weight of
the paper is 50% by mass or more based on the entire gas barrier laminate,
the amount of use of plastic materials can be sufficiently reduced, the gas
20 barrier laminate can be said to be made of paper on the whole, and at the
same time, excellent recyclability is obtained.

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.
2. The gas barrier laminate according to claim 1, wherein the first
10 polyolefin having a polar group has at least one selected from a 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
15 carboxyl group, a salt of a carboxyl group, a carboxylic acid anhydride
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.
20 5. The gas barrier laminate according to claim 1, wherein the first
polyolefin having a polar group is an ethylene-vinyl acetate copolymer.
6. The gas barrier laminate according to claim 1, wherein the first
polyolefin having a polar group is an ethylene-glycidyl methacrylate
copolymer.
25 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
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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 5 of claims 1 to 6,
wherein the second polyolefin having a polar group is an ethyleneglycidyl
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.
10 11. The gas barrier laminate according to any one of claims 1 to 10,
wherein a weight of paper is 50% by mass or more based on the entire
gas barrier laminate.
12. A packaging bag comprising the gas barrier laminate according to
any one of claims 1 to 11.
15 13. The packaging bag according to claim 12, having a folding part.