Technical Field
[0001] The present disclosure relates to a gas 5 barrier laminate and a
packaging bag.
Background Art
[0002] Laminates including a biaxial stretching polyethylene
terephthalate (PET) film as a base film having an excellent heat resistance
10 and an excellent toughness and a polyolefin film made of polyethylene,
polypropylene, or the like as a sealant layer are known (for example, refer
to Patent Literature 1).
Citation List
Patent Literature
15 [0003] [Patent Literature 1] Japanese Unexamined Patent Publication
No. 2017-178357
Summary of Invention
Technical Problem
[0004] Incidentally, in recent years, due to growing environmental
20 awareness caused by marine plastic waste problems and the like, there is
a demand for higher efficiency in separate collection and recycling of
plastic materials. That is, even in laminates for packaging in the related
art which have been devised to have a high performance by combining
various dissimilar materials, there is a demand for mono-materialization.
25 [0005] In order to realize mono-materialization in laminates, there is a
need to have constituent films made of the same material. For example,
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since polyethylene films, which are a kind of polyolefin films, are widely
used as packaging materials, it is expected to achieve monomaterialization
in polyethylene films. However, regarding basic
physical properties of polyethylene films, the films are characterized by
having a low melting point, being likely to be stretched 5 even at a low
temperature, and being likely to be deformed. Therefore, when an
inorganic oxide layer is formed by a method such as vapor deposition
with respect to a polyethylene film and high gas barrier properties are
imparted thereto, there are problems that the inorganic oxide layer on the
10 polyethylene film is likely to break during processing or after processing
so that high gas barrier properties cannot be retained. In addition, the
inorganic oxide layer provided on the polyethylene film is likely to break
particularly at the time of bending. Therefore, there is a demand for
development of a laminate which can retain high gas barrier properties
15 even after bending.
[0006] The present disclosure has been made in consideration of the
foregoing circumstances, and an object thereof is to provide a gas barrier
laminate which can maintain high gas barrier properties even after
bending while having a polyolefin-based film as a main constituent. In
20 addition, another object of the present disclosure is to provide a
packaging bag using the foregoing gas barrier laminate.
Solution to Problem
[0007] In order to achieve the foregoing objects, the present disclosure
provides a gas barrier laminate which has a structure having a base
25 material layer including a polyolefin, an undercoat layer, an inorganic
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oxide layer, a gas barrier adhesive layer, and a resin layer including a
polyolefin laminated therein in this order.
[0008] When an inorganic oxide layer is formed on a base material layer
including a polyolefin to impart gas barrier properties thereto, the
inorganic oxide layer which is thin, hard, and fragile is 5 likely to break on
the base material layer which is soft and likely to be stretched, and there
is a tendency that the gas barrier properties cannot be sufficiently
manifested. In contrast, according to the gas barrier laminate of the
present disclosure, since an undercoat layer for providing an inorganic
10 oxide layer is included on the base material layer, an inorganic oxide layer
can be uniformly formed on the undercoat layer, and occurrence of
breaking in the inorganic oxide layer caused by stretching of the base
material layer can be curbed. In addition, according to the gas barrier
laminate of the present disclosure, since a gas barrier adhesive layer is
15 included on the inorganic oxide layer, it is possible to obtain a gas barrier
laminate in which the gas barrier adhesive layer protects the inorganic
oxide layer and which can also endure a bending test as a packaging
material. When the layer provided on the inorganic oxide layer is an
adhesive layer having no gas barrier properties or a barrier layer having
20 no function of an adhesive, it is difficult to maintain high gas barrier
properties after a bending test. Since an adhesive layer having gas
barrier properties is provided on the inorganic oxide layer, breaking in the
inorganic oxide layer at the time of bending can be curbed, and for
instance, even when a minor break occurs in a part of the inorganic oxide
25 layer, the minor break can be filled with the gas barrier adhesive layer so
that degradation in gas barrier properties can be curbed. In addition, in
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the gas barrier laminate of the present disclosure, since both the base
material layer and the resin layer are layers including a polyolefin, monomaterialization
can be realized.
[0009] In the gas barrier laminate, a thickness of the gas barrier adhesive
layer may be equal to or larger than 50 times a thickness 5 of the inorganic
oxide layer. Since the gas barrier adhesive layer plays not only a role as
an adhesive But also a role as a protective coat layer, it can be used with
a thickness that is equal to or larger than 50 times with respect to the
inorganic oxide layer. Since the gas barrier adhesive layer has the
10 foregoing thickness, breaking in the inorganic oxide layer can be more
sufficiently curbed, and the gas barrier properties of the gas barrier
laminate can be further improved. In addition, since the gas barrier
adhesive layer has the foregoing thickness, cushioning properties of
alleviating an impact from the outside can be achieved, and thus the
15 inorganic oxide layer can be prevented from breaking due to an impact.
[0010] In the gas barrier laminate, an oxygen transmission rate of the gas
barrier adhesive layer may be 100 cc/m2∙day∙atm or lower. Accordingly,
the gas barrier properties of the gas barrier laminate can be further
improved, and degradation in gas barrier properties after bending can be
20 curbed even further. In addition, when a minor break occurs in the
inorganic oxide layer due to bending or the like and when the gas barrier
adhesive layer enters and fills a gap thereof, since the oxygen
transmission rate of the gas barrier adhesive layer is within the foregoing
range, degradation in gas barrier properties can be curbed even further.
25 [0011] In the gas barrier laminate, a logarithmic decrement on a surface
of the gas barrier adhesive layer measured at 30ºC using a rigid body
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pendulum-type physical property tester may be 0.1 or smaller. Since the
logarithmic decrement on a surface of the gas barrier adhesive layer is 0.1
or smaller, the gas barrier properties of the gas barrier laminate can be
further improved, and degradation in gas barrier properties after bending
can be curbed even further. It is conceivable that 5 when the logarithmic
decrement is low, since molecules on the surface of the gas barrier
adhesive layer are unlikely to move and gaseous molecules such as
oxygen are unlikely to pass therethrough, higher gas barrier properties
can be achieved.
10 [0012] In the gas barrier laminate, the gas barrier adhesive layer may be
a layer formed using an epoxy-based adhesive. Since it is easy to make
a dense film using an epoxy resin due to the molecular structure thereof,
a gas barrier adhesive layer formed using an epoxy-based adhesive is
likely to exhibit higher gas barrier properties. Particularly, a gas barrier
15 adhesive layer which is formed using an epoxy-based adhesive And of
which the logarithmic decrement is 0.1 or smaller is likely to exhibit far
superior gas barrier properties.
[0013] In the gas barrier laminate, the inorganic oxide layer may include
a silicon oxide. Since an inorganic oxide layer including a silicon oxide
20 is likely to curb deterioration in gas barrier properties due to stretching or
bending, degradation in gas barrier properties of the gas barrier laminate,
which uses a base material layer including a polyolefin and in which
deformation is likely to occur, is likely to be curbed.
[0014] In the gas barrier laminate, the resin layer may be a sealant layer.
25 A heat fusion temperature difference between the base material layer and
the sealant layer may be 10ºC or greater. Since a heat fusion
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temperature difference of 10ºC or greater is provided between the base
material layer and the sealant layer, it is easy to mold a gas barrier
laminate into a packaging bag or the like through heat sealing.
[0015] In the gas barrier laminate, a Tg difference between the undercoat
layer and the gas barrier adhesive layer may be 1005 ºC or smaller. Since
the Tg difference between the undercoat layer and the gas barrier
adhesive layer is limited to 100ºC or smaller, it is possible to curb
breaking in the inorganic oxide layer due to stress applied to the inorganic
oxide layer disposed between the undercoat layer and the gas barrier
10 adhesive layer at the time of heat sealing or at the time of processing of
the gas barrier laminate.
[0016] The foregoing gas barrier laminate may have a structure further
having a print layer laminated therein. In addition, the gas barrier
laminate may have a structure having the resin layer as a first resin layer
15 and further having a second resin layer, different from the first resin layer,
including a polyolefin laminated therein. When the gas barrier laminate
includes a print layer and includes no second resin layer, the print layer is
normally formed on a surface of the base material layer on a side opposite
to the undercoat layer.
20 [0017] When the gas barrier laminate includes the second resin layer, a
heat fusion temperature difference between two layers farthest away from
each other in three layers including the base material layer, the first resin
layer, and the second resin layer may be 10ºC or greater. Accordingly,
it is easy to mold a gas barrier laminate into a packaging bag or the like
25 through heat sealing.
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[0018] In addition, the present disclosure provides a packaging bag made
as a bag with the gas barrier laminate described above.
Advantageous Effects of Invention
[0019] According to the present disclosure, even when a polyolefinbased
film is adopted as a main constituent, it is possible 5 to provide a gas
barrier laminate which can maintain high gas barrier properties even after
bending. In addition, the present disclosure can provide a packaging
bag using the gas barrier laminate.
Brief Description of Drawings
10 [0020] FIG. 1 is a schematic cross-sectional view illustrating a gas
barrier laminate according to an embodiment.
FIG. 2 is a schematic cross-sectional view illustrating the gas
barrier laminate according to another embodiment.
FIG. 3 is a schematic cross-sectional view illustrating the gas
15 barrier laminate according to another embodiment.
FIG. 4 is a schematic cross-sectional view illustrating the gas
barrier laminate according to another embodiment.
FIG. 5 is a schematic cross-sectional view illustrating the gas
barrier laminate according to another embodiment.
20 FIG. 6 is a perspective view illustrating an embodiment of a
packaging bag with a mouth plug.
FIG. 7 is a front view illustrating an embodiment of a tube
container.
Description of Embodiment
25 [0021] Hereinafter, a preferred embodiment of the present disclosure will
be described in detail with reference to the drawings depending on
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circumstances. In the drawings, the same reference signs are applied to
parts which are the same or corresponding, and duplicate description
thereof will be omitted. In addition, the dimensional ratios of the
drawings are not limited to the illustrated ratios.
[0022] 5
FIG. 1 is a schematic cross-sectional view illustrating a gas
barrier laminate according to an embodiment. A gas barrier laminate 10
illustrated in FIG. 1 includes a base material layer 1, an undercoat layer
2, an inorganic oxide layer 3, a gas barrier adhesive layer 4, and a resin
10 layer (first resin layer) 5 in this order. Both the base material layer 1 and
the first resin layer 5 include a polyolefin.
[0023] FIG. 2 is a schematic cross-sectional view illustrating the gas
barrier laminate according to another embodiment. A gas barrier
laminate 20 illustrated in FIG. 2 further includes a print layer 6 on an
15 outward side of a base material layer in the gas barrier laminate 10
illustrated in FIG. 1 (on a surface on a side opposite to the undercoat layer
2).
[0024] FIG. 3 is a schematic cross-sectional view illustrating the gas
barrier laminate according to another embodiment. A gas barrier
20 laminate 30 illustrated in FIG. 3 has a structure in which the print layer 6
and a second resin layer 7 are laminated on the outward side of the base
material layer in the gas barrier laminate 10 illustrated in FIG. 1 with an
adhesive layer 8 therebetween. The second resin layer 7 includes a
polyolefin.
25 [0025] FIG. 4 is a schematic cross-sectional view illustrating the gas
barrier laminate according to another embodiment. A gas barrier
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laminate 40 illustrated in FIG. 4 includes the first resin layer 5, the print
layer 6, the gas barrier adhesive layer 4, the inorganic oxide layer 3, the
undercoat layer 2, the base material layer 1, the adhesive layer 8, and the
second resin layer 7 in this order.
[0026] FIG. 5 is a schematic cross-sectional view illustrating 5 the gas
barrier laminate according to another embodiment. A gas barrier
laminate 50 illustrated in FIG. 5 has a structure in which the print layer
6, the adhesive layer 8, and the second resin layer 7 are laminated on an
outward side of the first resin layer 5 in the gas barrier laminate 10
10 illustrated in FIG. 1 (on a surface on a side opposite to the gas barrier
adhesive layer 4).
[0027] When a packaging bag or the like is produced using the gas barrier
laminate 10, 20, or 30, a function as a sealant layer can be imparted to the
first resin layer 5. When a packaging bag or the like is produced using
15 the gas barrier laminate 40 or 50, a function as a sealant layer can be
imparted to the second resin layer 7. Hereinafter, each of the layers will
be described.
[0028] [Base material layer 1]
The base material layer 1 is a film serving as a supporter and
20 includes a polyolefin. A content of a polyolefin in the base material
layer 1 may be 50 mass% or more, may be 80 mass% or more, or may be
100 mass% based on the total content of the base material layer 1. It is
preferable to use a polyolefin as a material of the base material layer 1
from a viewpoint of recycling efficiency. In addition, as the content of
25 a polyolefin in the base material layer 1 increases, the recycling efficiency
is further improved.
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[0029] The base material layer 1 may be constituted of a polyolefin film.
Examples of a polyolefin include a polyethylene (PE), a polypropylene
(PP), and a polybutene (PB). A polyolefin may be a polyethylene. In
addition, examples of a polyolefin include an acid-modified polyolefin
obtained by graft-modifying a polyolefin using an unsaturated 5 carboxylic
acid, an acid anhydride of an unsaturated carboxylic acid, an ester of an
unsaturated carboxylic acid, or the like.
[0030] A polyolefin is preferably a polypropylene from a viewpoint of a
retort treatment resistance. Here, a polypropylene may be a
10 homopolypropylene or a propylene copolymer. From a viewpoint of
adhesive properties and barrier properties, a coat layer such as an easily
adhesive layer including a propylene copolymer may be provided on a
lamination surface of the base material layer 1 (a surface on a side where
the undercoat layer 2 is laminated). The easily adhesive layer can be
15 provided between the base material layer 1 and the undercoat layer 2.
[0031] A density of a polyolefin included in the base material layer 1 may
be 0.900 g/cm3 or higher or may be 0.910 g/cm3 or higher. In addition,
when a polyolefin included in the base material layer 1 is a polyethylene,
the density thereof may be 0.930 g/cm3 or higher, may be 0.935 g/cm3 or
20 higher, or may be 0.945 g/cm3 or higher. If the density of a polyolefin
is 0.935 g/cm3 or higher, generation of creases due to stretching of the
base material layer 1 during roll processing is likely to be curbed, and
occurrence of breaking in the inorganic oxide layer 3 is likely to be
curbed. The base material layer 1 may include a polyolefin which is
25 biomass-derived or recycled.
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[0032] A constitution of the base material layer 1 may be a multilayer
constitution provided with a plurality of layers (films) respectively
including polyolefins having different densities. It is desirable that the
base material layer 1 be suitably multilayered in consideration of
processing suitability, a rigidity or a firmness, a heat 5 resistance, powder
removal at the time of transportation, and the like of a film constituting
the base material layer 1. A film constituting the base material layer 1
can be produced by suitably selecting and using a high-density
polyolefin, a medium-density polyolefin, a low-density polyolefin, or the
10 like. When the density of a film as the base material layer 1 is measured,
the density is preferably 0.900 g/cm3 or higher. In addition, each of the
layers may be laminated while varying the content of a slipping agent, an
anti-static agent, or the like therein. The base material layer 1 including
a plurality of layers may be laminated and made into a film through
15 extrusion coating, coextrusion coating, sheet molding, coextrusion blow
molding, or the like. The total thickness of the base material layer 1
including a plurality of layers is preferably approximately 10 to 100 μm
and is more preferably 15 to 50 μm.
[0033] The film constituting the base material layer 1 may be a stretched
20 film or may be a non-stretched film. However, from a viewpoint of an
impact resistance, a heat resistance, a water resistance, dimensional
stability, easily tearing properties, and the like, a film constituting the base
material layer 1 may be a stretched film. When the print layer 6 is
provided on the base material layer 1, there is an advantage that a
25 stretched film is likely to be printed. In addition, if the base material
layer 1 is a stretched film, a gas barrier laminate can be more favorably
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used for the purpose of performing boiling treatment. A stretching
method is not particularly limited, and any method, such as stretching by
inflation, uniaxial stretching, biaxial stretching, or the like, may be
adopted as long as a film having stable dimensions can be supplied.
[0034] In the base material layer 1, a thermal shrinkage 5 rate in a traveling
direction (MD direction) and a vertical direction (TD direction) after
heating at 100ºC for 15 minutes is preferably 3% or lower, more
preferably 2% or lower, and further preferably 1.5% or lower. If the
thermal shrinkage rate of the base material layer 1 is within the foregoing
10 range, generation of creases due to stretching of the base material layer 1
during roll processing is likely to be curbed, and occurrence of breaking
in the inorganic oxide layer 3 is likely to be curbed.
[0035] Here, the foregoing thermal shrinkage rate (%) is a value
calculated by the following expression.
15 Thermal shrinkage rate (%)={(length before heating−length after
heating)/length before heating}×100
A measurement procedure of the thermal shrinkage rate is as
follows.
(1) The base material layer 1 is cut out into 20 cm×20 cm to be
20 used as a measurement sample.
(2) A line of 10 cm is marked in the MD direction or the TD
direction of the measurement sample (length before heating).
(3) The measurement sample is heated at 100ºC for 15 minutes.
(4) The length of the marked line in the MD direction or the TD
25 direction is measured (length after heating).
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(5) The thermal shrinkage rate is calculated by the foregoing
expression.
[0036] A thickness of the base material layer 1 is not particularly limited.
The thickness can become 6 to 200 μm in accordance with the purpose.
However, from a viewpoint of achieving an excellent 5 impact resistance
and excellent gas barrier properties, the thickness may be 9 to 50 μm or
may be 12 to 38 μm.
[0037] In the base material layer 1, from a viewpoint of improving the
adhesive properties with respect to the undercoat layer 2 or the inorganic
10 oxide layer 3, the lamination surface thereof may be subjected to various
kinds of preliminary treatment such as corona treatment, plasma
treatment, low-temperature plasma treatment, frame treatment, chemical
treatment, solvent treatment, and ozone treatment within a range not
impairing the barrier performance thereof, or may be provided with a coat
15 layer such as an easily adhesive layer.
[0038] The base material layer 1 may contain an additive agent such as a
filler, an anti-blocking agent, an anti-static agent, a plasticizer, a lubricant,
or an oxidation inhibitor. Regarding these additive agents, any one kind
may be used alone, or two or more kinds may be used together.
20 [0039] [Undercoat layer 2]
An undercoat layer (anchor coat layer) 2 is provided on a surface
where the inorganic oxide layer 3 of the base material layer 1 is laminated.
The undercoat layer 2 can exhibit effects, such as improvement in
adhesive performance between the base material layer 1 and the inorganic
25 oxide layer 3, improvement in smoothness on the surface of the base
material layer 1, and curbs on occurrence of breaking in the inorganic
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oxide layer 3 caused by stretching of the base material layer 1. Since
the smoothness is improved, the inorganic oxide layer 3 can be subjected
to uniform film formation with no defect, and thus high barrier properties
are likely to be manifested. The undercoat layer 2 can be formed using
a composition for forming an undercoat layer 5 (anchor coat agent).
[0040] Examples of a resin used in an anchor coat agent include an
acrylic resin, an epoxy resin, an acrylic urethane-based resin, a polyesterbased
polyurethane resin, and a polyether-based polyurethane resin.
From a viewpoint of a heat resistance and an interlayer adhesive strength,
10 it is preferable to adopt an acrylic urethane-based resin or a polyesterbased
polyurethane resin as a resin used in an anchor coat agent. The
undercoat layer 2 can be formed using an anchor coat agent including
these resins or components which form these resins through reaction.
[0041] A thickness of the undercoat layer 2 is not particularly limited.
15 However, it is preferably within a range of 0.01 to 5 μm, more preferably
within a range of 0.03 to 3 μm, and particularly preferably within a range
of 0.05 to 2 μm. If the thickness of the undercoat layer 2 is equal to or
larger than the foregoing lower limit value, there is a tendency that a more
sufficient interlayer adhesive strength can be achieved. On the other
20 hand, if it is equal to or smaller than the foregoing upper limit value, there
is a tendency that desired gas barrier properties are likely to be
manifested.
[0042] Regarding a method for coating the base material layer 1 with the
undercoat layer 2 thereon, a known coating method can be used without
25 any particular limitation, and examples thereof include an immersion
method (dipping method); and a method of using a spray, a coater, a
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printer, a brush, or the like. In addition, examples of kinds of coaters
and printers used in these methods and coating types thereof can include
a gravure coater of a direct gravure type, a reverse gravure type, a kiss
reverse gravure type, an offset gravure type, or the like; a reverse roll
coater; a micro-gravure coater; a chamber doctor-combined 5 coater; an airknife
coater; a dip coater; a bar coater; a comma coater; a die coater; and
the like.
[0043] Regarding a coating amount of the undercoat layer 2, mass per
square meter thereof after coating with an anchor coat agent and drying
10 is preferably 0.01 to 5 g/m2 and more preferably 0.03 to 3 g/m2. If mass
per square meter thereof after coating with an anchor coat agent and
drying is equal to or smaller than the foregoing lower limit, there is a
tendency that film formation becomes sufficient. On the other hand, if
it is equal to or smaller than the foregoing upper limit, there is a tendency
15 that the anchor coat agent is likely to be sufficiently dried and a solvent
is unlikely to remain.
[0044] A method for drying the undercoat layer 2 is not particularly
limited, and examples thereof can include a method of natural drying, a
method for performing drying in an oven set to a predetermined
20 temperature, and methods using dryers which belong to the foregoing
coaters, for example, an arch dryer, a floating dryer, a drum dryer, and an
infrared dryer. Moreover, drying conditions can be suitably selected
depending on the drying method. For example, in the method for
performing drying in an oven, it is preferable to perform drying at a
25 temperature of 60ºC to 100ºC for approximately one second to two
minutes.
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[0045] In place of the resins described above, a polyvinyl alcohol-based
resin can be used as the undercoat layer 2. A polyvinyl alcohol-based
resin need only have a vinyl alcohol unit established through
saponification of a vinyl ester unit, and examples thereof include a
polyvinyl alcohol (PVA), an ethylene-vinyl alcohol 5 copolymer (EVOH).
[0046] Examples of a PVA include resins in which a vinyl ester such as
a vinyl acetate, a vinyl formate, a vinyl propionate, a vinyl valeric acid, a
vinyl caprate, a vinyl laurate, a vinyl stearate, a vinyl pivalic acid, or a
vinyl versatic acid is polymerized alone and is subsequently saponified.
10 A PVA may be a denatured PVA subjected to copolymerization
denaturation or post-denaturation. For example, a denatured PVA can
be obtained by copolymerizing a vinyl ester and an unsaturated monomer
which can be copolymerized with a vinyl ester and saponifying them
thereafter. Examples of an unsaturated monomer which can be
15 copolymerized with a vinyl ester include olefins such as an ethylene, a
propylene, an isobutylene, an α-octene, an α-dodecene, and an α-
octadecene; hydroxy group-containing α-olefins such as a 3-butene-1-ol,
a 4-pentyne-1-ol, and a 4-hexene-1-ol; unsaturated acids such as an
acrylic acid, a methacrylic acid, a crotonic acid, a maleic acid, a maleic
20 anhydride, an itaconic acid, and an undecylenic acid; nitriles such as an
acrylonitrile and metaacrylonitrile; amides such as a diacetone
acrylamide, an acrylamide, and a methacrylamide; olefin sulfonic acids
such as an ethylene sulfonic acid, an allyl sulfonic acid, and a metaallyl
sulfonic acid; vinyl compounds such as an alkyl vinyl ether, a
25 dimethylallyl vinyl ketone, an N-vinylpyrrolidone, a vinyl chloride, a
vinyl ethylene carbonate, a 2,2-dialkyl-4-vinyl-1,3-dioxolane, a glycerin
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monoallyl ether, and a 3,4-diacetoxy-1-butene; a vinylidene chloride; a
1,4-diacetoxy-2-butene; and a vinylene carbonate.
[0047] A polymerization degree of a PVA is preferably 300 to 3,000. If
the polymerization degree is 300 or higher, the barrier properties are
likely to be improved. In addition, if it is 3,000 or lower, 5 degradation in
coating suitability due to an excessively high viscosity is likely to be
curbed. A saponification degree of a PVA is preferably 90 mol% or
higher, more preferably 95 mol% or higher, and further preferably 99
mol% or higher. In addition, the saponification degree of a PVA may be
10 100 mol% or lower or 99.9 mol% or lower. The polymerization degree
and the saponification degree of a PVA can be measured in conformity
with the method described in JIS K 6726 (1994).
[0048] An EVOH can be generally obtained by saponifying a copolymer
of an ethylene and an acid vinyl ester such as a vinyl acetate, a vinyl
15 formate, a vinyl propionate, a vinyl valeric acid, a vinyl caprate, a vinyl
laurate, a vinyl stearate, a vinyl pivalic acid, or a vinyl versatic acid.
[0049] A polymerization degree of an EVOH is preferably 300 to 3,000.
If the polymerization degree is 300 or higher, the barrier properties are
likely to be improved. In addition, if it is 3,000 or lower, degradation in
20 coating suitability due to an excessively high viscosity is likely to be
curbed. A saponification degree of vinyl ester components of an EVOH
is preferably 90 mol% or higher, more preferably 95 mol% or higher, and
further preferably 99 mol% or higher. In addition, the saponification
degree of an EVOH may be 100 mol% or lower or 99.9 mol% or lower.
25 The saponification degree of an EVOH can be obtained from a peak
surface area of hydrogen atoms included in a vinyl ester structure and a
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peak surface area of hydrogen atoms included in a vinyl alcohol structure
by performing nuclear magnetic resonance (1H-NMR) measurement.
[0050] An ethylene unit content of an EVOH is 10 mol% or higher, more
preferably 15 mol% or higher, further preferably 20 mol% or higher, and
particularly preferably 25 mol% or higher. In addition, 5 the ethylene unit
content of an EVOH is preferably 65 mol% or lower, more preferably 55
mol% or lower, and further preferably 50 mol% or lower. If the ethylene
unit content is 10 mol% or higher, the gas barrier properties or the
dimensional stability under high humidity can be favorably retained.
10 On the other hand, if the ethylene unit content is 65 mol% or lower, the
gas barrier properties can be enhanced. The ethylene unit content of an
EVOH can be obtained by an NMR method.
[0051] When a polyvinyl alcohol-based resin is used as the undercoat
layer 2, examples of a method for forming the undercoat layer 2 include
15 coating using a polyvinyl alcohol-based resin solution and multilayer
extrusion.
[0052] [Inorganic oxide layer 3]
Examples of a constituent material of the inorganic oxide layer 3
include inorganic oxides such as an aluminum oxide, a silicon oxide, a
20 magnesium oxide, and a tin oxide. From a viewpoint of transparency
and barrier properties, an inorganic oxide may be selected from the group
consisting of an aluminum oxide, a silicon oxide, and a magnesium oxide.
In addition, from a viewpoint of excellent tensile stretchability at the time
of processing, it is preferable that the inorganic oxide layer 3 be a layer
25 using a silicon oxide. When the inorganic oxide layer 3 is used, high
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barrier properties can be achieved with an extremely thin layer within a
range not affecting the recycling efficiency of a gas barrier laminate.
[0053] An O/Si ratio of the inorganic oxide layer 3 is desirably 1.7 or
greater. If the O/Si ratio is 1.7 or greater, a proportion of the content of
a metal Si is restricted so that favorable transparency 5 is likely to be
obtained. In addition, the O/Si ratio is preferably 2.0 or smaller. If the
O/Si ratio is 2.0 or smaller, an inorganic oxide layer can be prevented
from becoming excessively hard due to high crystallinity of a SiO, and
thus a favorable tensile resistance can be achieved. Accordingly, when
10 the gas barrier adhesive layer 4 is laminated, occurrence of cracking in
the inorganic oxide layer 3 can be curbed. In addition, the base material
layer 1 may shrink due to heat at the time of boiling treatment even after
being molded into a packaging bag, since the O/Si ratio is 2.0 or smaller,
the inorganic oxide layer is likely to follow the shrinkage, and thus
15 degradation in barrier properties can be curbed. From a viewpoint of
more sufficiently achieving these effects, the O/Si ratio of the inorganic
oxide layer 3 is preferably 1.75 or greater and 1.9 or smaller and more
preferably 1.8 or greater and 1.85 or smaller.
[0054] The O/Si ratio of the inorganic oxide layer 3 can be obtained by
20 an X-ray photoelectron spectroscopy (XPS). For example, the O/Si
ratio thereof can be measured using X-RAY PHOTOELECTRON
SPECTROSCOPY ANALYZER (manufactured by JEOL LTD., trade
name: JPS-90MXV) as a measurement device and non-monochromatic
MgKα (1253.6 eV) as an X‐ray source with an X-ray output of 100 W
25 (10 kV-10 mA). Relative sensitivity factors of 2.28 for O1s and 0.9 for
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Si2p can be respectively used for quantitative analysis for obtaining an
O/Si ratio.
[0055] A film thickness of the inorganic oxide layer 3 is preferably 10
nm or larger and 50 nm or smaller. If the film thickness is 10 nm or
larger, sufficient gas barrier properties can be achieved. 5 In addition, if
the film thickness is 50 nm or smaller, occurrence of cracking caused by
deformation due to internal stress of a thin film can be curbed, and
degradation in gas barrier properties can be curbed. If the film thickness
is 50 nm or smaller, increase in cost caused by increase in amounts of
10 materials used and a prolonged film formation time is likely to be curbed,
which is preferable from a viewpoint of economic aspect. From a
viewpoint similar to that described above, the film thickness of an
inorganic oxide layer is more preferably 20 nm or larger and 40 nm or
smaller.
15 [0056] For example, the inorganic oxide layer 3 can be formed through
vacuum film formation. Regarding vacuum film formation, a physical
vapor deposition method or a chemical vapor deposition method can be
used. Examples of a physical vapor deposition method can include a
vacuum vapor deposition method, a sputtering method, and an ion plating
20 method, but it is not limited to thereto. Examples of a chemical vapor
deposition method can include a thermal CVD method, a plasma CVD
method, and a photo-CVD method, but it is not limited to thereto.
[0057] In the foregoing vacuum film formation, a resistance heating-type
vacuum vapor deposition method, an electron beam (EB) heating-type
25 vacuum vapor deposition method, an induction heating-type vacuum
vapor deposition method, a sputtering method, a reactive sputtering
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method, a dual magnetron sputtering method, a plasma chemical vapor
deposition method (PECVD method), or the like is particularly preferably
used. However, in consideration of productivity, a vacuum vapor
deposition method is the most excellent method at present. Regarding
a heating means in the vacuum vapor deposition method, 5 it is preferable
to use any type of an electron beam heating type, a resistance heating
type, and an induction heating type.
[0058] [Gas barrier adhesive layer 4]
The gas barrier adhesive layer 4 exhibits effects of causing the
10 inorganic oxide layer 3 and the first resin layer 5 to adhere to each other,
protecting the inorganic oxide layer 3, and preventing breaking in the
inorganic oxide layer 3 at the time of bending.
[0059] In addition, the gas barrier adhesive layer 4 is a layer having gas
barrier properties. Since the gas barrier adhesive layer 4 is provided,
15 gas barrier properties of a gas barrier laminate can be improved. An
oxygen transmission rate of the gas barrier adhesive layer 4 is preferably
150 cc/m2∙day∙atm or lower, more preferably 100 cc/m2∙day∙atm or lower,
further preferably 80 cc/m2∙day∙atm or lower, and particularly preferably
50 cc/m2∙day∙atm or lower. Since the oxygen transmission rate is within
20 the foregoing range, gas barrier properties of a gas barrier laminate can
be sufficiently improved, and for instance, even when a minor break
occurs in the inorganic oxide layer 3, the gas barrier adhesive layer 4 can
enter and fill a gap thereof so that degradation in gas barrier properties
can be curbed.
25 [0060] The gas barrier adhesive layer 4 is formed using an adhesive
which can manifest gas barrier properties after curing. Examples of an
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adhesive used for forming the gas barrier adhesive layer 4 include an
epoxy-based adhesive And a polyester/polyurethane-based adhesive.
Specific examples of an adhesive which can manifest gas barrier
properties after curing include “MAXIVE” manufactured by
MITSUBISHI GAS CHEMICAL COMPANY, 5 INC. and “Paslim”
manufactured by DIC CORPORATION.

CLAIMS
[Claim 1] A gas barrier laminate which has a structure having a base
material layer comprising a polyolefin, an undercoat layer, an inorganic
oxide layer, a gas barrier adhesive layer, and a resin layer comprising a
polyolefin laminated therein 5 in this order.
[Claim 2] The gas barrier laminate according to claim 1,
wherein a thickness of the gas barrier adhesive layer is equal to or
larger than 50 times a thickness of the inorganic oxide layer.
[Claim 3] The gas barrier laminate according to claim 1 or 2,
10 wherein an oxygen transmission rate of the gas barrier adhesive
layer is 100 cc/m2∙day∙atm or lower.
[Claim 4] The gas barrier laminate according to any one of claims 1
to 3,
wherein a logarithmic decrement on a surface of the gas barrier
15 adhesive layer measured at 30ºC using a rigid body pendulum-type
physical property tester is 0.1 or smaller.
[Claim 5] The gas barrier laminate according to any one of claims 1
to 4,
wherein the gas barrier adhesive layer is a layer formed using an
20 epoxy-based adhesive.
[Claim 6] The gas barrier laminate according to any one of claims 1
to 5,
wherein the inorganic oxide layer comprises a silicon oxide.
[Claim 7] The gas barrier laminate according to any one of claims 1
25 to 6,
wherein the resin layer is a sealant layer, and
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wherein a heat fusion temperature difference between the base
material layer and the sealant layer is 10ºC or greater.
[Claim 8] The gas barrier laminate according to any one of claims 1
to 7,
wherein a Tg difference between the undercoat 5 layer and the gas
barrier adhesive layer is 100ºC or smaller.
[Claim 9] The gas barrier laminate according to any one of claims 1
to 8 has a structure further having a print layer laminated therein.
[Claim 10] The gas barrier laminate according to any one of claims 1
10 to 9 comprising a structure having the resin layer as a first resin layer and
further having a second resin layer, different from the first resin layer,
comprising a polyolefin laminated therein.
[Claim 11] The gas barrier laminate according to claim 10,
wherein a heat fusion temperature difference between two layers
15 farthest away from each other in three layers comprising the base material
layer, the first resin layer, and the second resin layer is 10ºC or greater.
[Claim 12] A packaging bag made as a bag with the gas barrier
laminate according to any one of claims 1 to 11.