The present invention relates to a coating agent and a gas barrier film.
Priority is claimed on Japanese Patent Application No. 2015-087705, filed on
April 22, 2015, and Japanese Patent Application No. 2015-179742, filed on September
11, 2015, the contents of which are incorporated herein by reference.
10
BACKGROUND ART
[0002]
Packing materials that are used to pack food, medicinal products, and the like
need to have a property of blocking the entrance of moisture, oxygen and other gases that
15 alter the contents (gas barrier property) in order to suppress the alteration, decomposition,
and the like of the contents and maintain the functions or properties of the contents.
Therefore, in the related art, packing materials having a gas barrier layer are
used as the packing materials.
[0003]
20 Hitherto, gas barrier layers have been provided on base materials such as films
or paper by sputtering methods, deposition methods, wet coating methods, printing
methods, or the like.
In addition, as gas barrier layers, metal foils or metal-deposited films made of
metal such as aluminum, water-soluble polymers such as polyvinyl alcohol and ethylene
25 vinyl alcohol copolymers, resin films made of resins such as polyvinylidene chloride,
2
composite films of the water-soluble polymers and inorganic layered minerals, and the
like are used (for example, refer to Patent Documents 1 to 5).
[0004]
However, in spite of the excellent gas barrier property, metal foils or
metal-deposited films have a variety of problems in that their opaqueness 5 disables the
confirmation of the contents, their poor stretching property causes cracks even when the
foils or films are stretched only several percentages and thus degrades the gas barrier
property, and the foils or films need to be treated as incombustible substances during
disposal after use.
10 Resin films made of polyvinylidene chloride exhibit a favorable gas barrier
property that does not depend on humidity, but the resin films include chlorine and are
thus likely to act as generation sources of harmful substances such as dioxin in the case
of disposal treatments and the like and tend to be unpopular as packing materials.
Resin films made of water-soluble polymers such as non-chlorine-based
15 polyvinyl alcohol and ethylene-vinyl alcohol copolymers exhibit a favorable gas barrier
property in low-humidity atmospheres, but the gas barrier property significantly depends
on humidity, and thus there is a defect in that an increase in humidity significantly
degrades the gas barrier property.
Resin films made of resins other than polyvinylidene chloride and water-soluble
20 polymers have a poorer gas barrier property compared with resin films of polyvinylidene
chloride or resin films of polyvinyl alcohol in low-humidity atmospheres.
Composite films of water-soluble polymers and inorganic layered minerals have
more favorable humidity dependency compared with the resin films made of
water-soluble polymers, but the effect is not sufficient, and there is a problem with the
25 degradation of adhesiveness to base materials.
3
[0005]
As gas barrier films which exhibit a favorable gas barrier property even in
high-humidity atmospheres and have excellent adhesiveness to base materials, the
following films are proposed.
(1) A gas barrier film which is a film of an aqueous dispersion 5 element including
a gas barrier polyurethane resin which has urethane groups and urea groups and in which
the concentration of the urethane groups and the concentration of the urea groups are
15% by weight or more, in which a diisocyanate component in the polyurethane resin is
constituted of at least one of xylylene diisocyanate and hydrogenated xylylene
10 diisocyanate (Patent Document 6).
(2) A gas barrier film having a coating film including a water-soluble polymer A,
a water-soluble or water-dispersible polyester-based urethane resin, and an inorganic
layered mineral having an average particle diameter of 5 mm or less and a thickness of
500 nm or less as principal components formed on at least one surface of a thermoplastic
15 resin base film (Patent Document 7).
In addition, in the gas barrier film (1), the addition of inorganic layered minerals
is proposed in order to improve the gas barrier property.
PRIOR ART DOCUMENTS
PATENT DOCUMENTS
20 [0006]
[Patent Document 1] Japanese Unexamined Patent Application, First
Publication No. 2001-287294
[Patent Document 2] Japanese Unexamined Patent Application, First
Publication No. H11-165369
25 [Patent Document 3] Japanese Unexamined Patent Application, First
4
Publication No. H6-93133
[Patent Document 4] Japanese Unexamined Patent Application, First
Publication No. H9-150484
[Patent Document 5] Japanese Patent No. 3764109
[Patent Document 6] Japanese 5 Patent No. 4524463
[Patent Document 7] Japanese Patent No. 3351208
SUMMARY OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
10 [0007]
However, in the gas barrier film (1), it is extremely difficult to satisfy both a
favorable gas barrier property and the adhesion strength to other materials or the
cohesion strength of coating films which are sufficient as packing materials. For
example, in a case in which the gas barrier film does not contain any inorganic layered
15 minerals, the gas barrier property becomes insufficient. In a case in which an inorganic
layered mineral is added to the gas barrier film, the gas barrier property improves to a
certain extent. However, in order to sufficiently improve the gas barrier property, it is
necessary to put in order, distribute, and arrange the inorganic layered mineral in coating
films, but the regular distribution and arrangement of the inorganic layered mineral
20 degrades the adhesion strength to other materials or the cohesion strength of coating
films.
In the gas barrier film (2), the gas barrier property in high-humidity atmospheres
or the adhesiveness between coating films and base films are favorable, but the cohesion
strength of coating films is poor. Therefore, in a case in which the gas barrier film is
25 used as a packing material by being attached to other films on coating films, there is a
5
problem in that the lamination strength becomes insufficient. In addition, curing agents
are used in order to develop sufficient adhesion strengths to base films, but the addition
of curing agents causes reactions to rapidly proceed, and thus there is a problem in that
the usable time is short and the performance is unstable.
5 [0008]
The present invention has been made in consideration of the above-described
circumstances, and an object of the present invention is to provide a coating agent which
exhibits an excellent gas barrier property even in high-humidity atmospheres, can be used
to form coating films having sufficient adhesion strength to other materials or sufficient
10 coating film cohesion strength as packing materials, and has a long usable time, and a gas
barrier film using the same.
MEANS FOR SOLVING THE PROBLEMS
[0009]
A coating agent according to a first aspect of the present invention includes, as
15 principal components: an aqueous polyurethane resin (A) including a polyurethane resin
having an acid group and a polyamine compound, a water-soluble polymer (B), an
inorganic layered mineral (C), and a compound (D) having an epoxy group.
[0010]
A mass ratio of the aqueous polyurethane resin (A) to the water-soluble polymer
20 (B) in a solid content may be 85/15 to 10/90.
[0011]
The water-soluble polymer (B) may be polyvinyl alcohol.
[0012]
The compound (D) having an epoxy group may not have an isocyanate group.
25 [0013]
6
A water solubility ratio of the compound (D) having an epoxy group at 25°C
may be 50 mass% or more.
[0014]
A gas barrier film according to a second aspect of the present invention includes
a base film formed of a plastic material and a coating film which is laminated 5 on at least
one surface of the base film, the coating film being formed of the coating agent according
to the above-described aspect.
[0015]
A coating agent according to a third aspect of the present invention includes, as
10 principal components: an aqueous polyurethane resin (A) including a polyurethane resin
having an acid group and a polyamine compound, a water-soluble polymer (B), an
inorganic layered mineral (C), and a silane coupling agent (E).
[0016]
A mass ratio of the aqueous polyurethane resin (A) to the water-soluble polymer
15 (B) in a solid content may be 85/15 to 10/90.
[0017]
The water-soluble polymer (B) may be polyvinyl alcohol.
[0018]
The inorganic layered mineral (C) may be water-swellable synthetic mica.
20 [0019]
The silane coupling agent (E) may not have an isocyanate group.
[0020]
The silane coupling agent (E) may have an epoxy group.
[0021]
25 A gas barrier film according to a fourth aspect of the present invention includes
7
a base film formed of a plastic material and a coating film which is laminated on at least
one surface of the base film, the coating film being formed of the coating agent according
to the above-described aspect.
Effects of Invention
5 [0022]
According to the above-described aspects of the present invention, it is possible
to provide a coating agent which exhibits an excellent gas barrier property even in
high-humidity atmospheres, can be used to form coating films having sufficient adhesion
strength to other materials or sufficient membrane cohesion strength as packing materials,
10 and has a long usable time, and a gas barrier film using the same.
EMBODIMENTS FOR CARRYING OUT THE INVENTION
[0023]
Hereinafter, coating agents and gas barrier films according to embodiments of
15 the present invention will be described. , Note that the present embodiments are simply
specific descriptions for better understanding of the present invention and, unless
particularly otherwise described, do not limit the present invention.
[0024]

20 A coating agent according to a first embodiment of the present invention
includes, as principal components: an aqueous polyurethane resin (A), a water-soluble
polymer (B), an inorganic layered mineral (C), and a compound (D) having an epoxy
group (hereinafter, also referred to as the “epoxy compound”).
[0025]
25 “Aqueous polyurethane resin (A)”
8
The aqueous polyurethane resin (A) includes a polyurethane resin having an acid
group (hereinafter, also referred to as the “acid group-containing polyurethane resin”)
and a polyamine compound.
When the coating agent includes the aqueous polyurethane resin (A), the
wettability of the coating agent according to the present embodiment 5 to base films
formed of a plastic material and the adhesion strength of coating films formed of the
coating agent according to the present embodiment to base films formed of a plastic
material are excellent. Furthermore, when the aqueous polyurethane resin (A) contains
the acid group-containing polyurethane resin and the polyamine compound, an oxygen
10 barrier property that is excellent even in high-humidity atmospheres is developed.
[0026]
The acid group in the acid group-containing polyurethane resin (anionic
self-emulsification-type polyurethane resin) constituting the aqueous polyurethane resin
(A) can be bonded to amino groups (primary amino groups, secondary amino groups,
15 tertiary amino groups, and the like) in the polyamine compound constituting the aqueous
polyurethane resin (A).
Examples of the acid group include a carboxyl group, a sulfonic acid group, and
the like. Generally, the acid group can be neutralized by a neutralizer (base) and may
form a salt with a base.
20 The acid group may be located at the terminal of the acid group-containing
polyurethane resin or located at a side chain, but is preferably located at least at a side
chain.
[0027]
The acid value of the acid group-containing polyurethane resin can be selected
25 in a range in which water solubility or water dispersibility can be imparted, and is
9
generally 5 to 100 mgKOH/g, preferably 10 to 70 mgKOH/g, and more preferably 15 to
60 mgKOH/g. In a case in which the acid value of the acid group-containing
polyurethane resin is less than the lower limit value of the above-described range (5
mgKOH/g), the water solubility or water dispersibility of the acid group-containing
polyurethane resin becomes insufficient, and there is a concern 5 that the uniform
dispersibility between aqueous polyurethane resins and other materials or the dispersion
stability of the coating agent may degrade. In a case in which the acid value of the acid
group-containing polyurethane resin exceeds the upper limit value of the above-described
range (100 mgKOH/g), there is a concern that the water resistance or gas barrier property
10 of coating films formed of the coating agent may degrade. When the acid value of the
acid group-containing polyurethane resin is in the above-described range (5 to 100
mgKOH/g), it is possible to avoid the degradation of the dispersion stability of the
coating agent and the degradation of the water resistance or the gas barrier property.
When the acid value of the acid group-containing polyurethane is 15 to 60
15 mgKOH/g, crosslinking reactions with polyamines more appropriately occur, and coating
films formed of the coating agent develop a particularly excellent oxygen barrier
property even in high-humidity atmospheres.
The acid value of the acid group-containing polyurethane resin is measured
using a method according to JIS K 0070.
20 [0028]
From the viewpoint of the gas barrier property, the sum of the concentration of
urethane groups and the concentration of urea groups (urea groups) in the acid
group-containing polyurethane resin is preferably 15 mass% or more and more preferably
20 mass% to 60 mass%. In a case in which the sum of the concentration of urethane
25 groups and the concentration of urea groups is less than the lower limit value of the
10
above-described range (15 mass%), there is a concern that the gas barrier property of
coating films formed of the coating agent may become insufficient. In a case in which
the sum of the concentration of urethane groups and the concentration of urea groups
exceeds the upper limit value of the above-described range (60 mass%), there is a
concern that coating films formed of the coating agent may become 5 rigid and brittle.
When the sum of the concentration of urethane groups and the concentration of
urea groups (urea groups) in the acid group-containing polyurethane resin is in a range of
20 mass% to 60 mass%, a more favorable gas barrier property can be obtained while
maintaining the flexibility of coating films formed of the coating agent.
10 The concentration of urethane groups and the concentration of urea groups refer
to the proportion of the molecular weight of an urethane group (59 g/equivalent) or the
molecular weight of an urea group (a primary amino group (amino group): 58
g/equivalent and a secondary amino group (imino group): 57 g/equivalent) in the
molecular weight of the repeating constituent unit of the polyurethane resin. Note that
15 in a case in which two or more mixtures are used as the acid group-containing
polyurethane resin, the concentration of urethane groups and the concentration of urea
groups can be computed using the preparation bases of reaction components, that is, the
proportions of individual components used as bases.
[0029]
20 Generally, the acid group-containing polyurethane resin has at least a rigid unit
(a unit constituted of a hydrocarbon ring) and a short chain unit (for example, a unit
constituted of a hydrocarbon ring). That is, the repeating constituent unit of the acid
group-containing polyurethane resin is, generally, derived from a polyisocyanate
component, a polyhydroxy acid component, a polyol component, or a chain extender
25 component (particularly, at least a polyisocyanate component) and includes a
11
hydrocarbon ring (at least one of aromatic and non-aromatic hydrocarbon rings).
The proportion of units constituted of a hydrocarbon ring in the repeating
constituent unit of the acid group-containing polyurethane resin is generally 10 mass% to
70 mass%, preferably 15 mass % to 65 mass%, and more preferably 20 mass% to 60
mass%. In a case in which the proportion of units constituted of a hydrocarbon 5 ring in
the repeating constituent unit of the acid group-containing polyurethane resin is less than
the lower limit value of the above-described range (10 mass%), there is a concern that the
gas barrier property of coating films formed of the coating agent may become insufficient.
In a case in which the proportion of units constituted of a hydrocarbon ring in the
10 repeating constituent unit of the acid group-containing polyurethane resin exceeds the
upper limit value of the above-described range (70 mass%), there is a concern that
coating films formed of the coating agent may become rigid and brittle.
When the proportion of units constituted of a hydrocarbon ring in the repeating
constituent unit of the acid group-containing polyurethane resin is in a range of 20
15 mass% to 60 mass%, a more favorable gas barrier property can be obtained while
maintaining the flexibility of coating films formed of the coating agent.
[0030]
The number-average molecular weight of the acid group-containing
polyurethane resin can be appropriately selected and is preferably 800 to 1,000,000, more
20 preferably 800 to 200,000, and still more preferably 800 to 100,000. In a case in which
the number-average molecular weight of the acid group-containing polyurethane resin
exceeds the upper limit value of the above-described range (1,000,000), the viscosity of
the coating agent increases, which is not preferable. In a case in which the
number-average molecular weight of the acid group-containing polyurethane resin is less
25 than the lower limit value of the above-described range (800), there is a concern that the
12
gas barrier property of coating films formed of the coating agent may become
insufficient.
When the number-average molecular weight of the acid group-containing
polyurethane resin is in a range of 800 to 100,000, it is possible to suppress the viscosity
of the coating agent at a low level while maintaining the gas barrier 5 property, and thus
the application suitability further improves.
The number-average molecular weight of the acid group-containing
polyurethane resin is a standard polystyrene-equivalent value measured by gel
permeation chromatography (GPC).
10 [0031]
The acid group-containing polyurethane resin may be crystalline in order to
enhance the gas barrier property.
The glass transition temperature of the acid group-containing polyurethane resin
is preferably 100°C or higher, more preferably 110°C or higher, and still more preferably
15 120°C or higher. In a case in which the glass transition temperature of the acid
group-containing polyurethane resin is lower than 100°C, there is a concern that the gas
barrier property of coating films formed of the coating agent may become insufficient.
When the glass transition temperature of the acid group-containing polyurethane
resin is 120°C or higher, it is possible to form coating films that are particularly excellent
20 in terms of the gas barrier property.
The upper limit of the glass transition temperature of the acid group-containing
polyurethane resin is 200°C or lower, furthermore, 180°C or lower, and furthermore,
approximately 150°C or lower. Substantially, it is rarely possible for the acid
group-containing polyurethane resin satisfying the preferred ranges of the respective
13
items described above to have a glass transition temperature that is higher than the
above-described upper limit value (200°C).
When the upper limit of the glass transition temperature of the acid
group-containing polyurethane resin is 150°C or lower, it is possible to form coating
films that are particularly excellent in terms of 5 the flexibility.
Therefore, the glass transition temperature of the acid group-containing
polyurethane resin is preferably 100°C to 200°C, more preferably 110°C to 180°C, and
still more preferably 120°C to 150°C.
The glass transition temperature of the acid group-containing polyurethane resin
10 is measured by differential scanning calorimetry (DSC).
[0032]
The gas barrier property is developed by bonding the acid group in the acid
group-containing polyurethane resin and the polyamine compound, as a crosslinking
agent, in the aqueous polyurethane resin (A).
15 The polyamine compound constituting the aqueous polyurethane resin (A) is not
particularly limited as long as the polyamine compound is a compound which is bonded
to acid groups and is capable of improving the gas barrier property, and a variety of
compounds having two or more basic nitrogen atoms can be used.
The basic nitrogen atom is a nitrogen atom capable of being bonded to the acid
20 group in the acid group-containing polyurethane resin, and examples thereof include
nitrogen atoms in amino groups such as a primary amino group, a secondary amino
group, and a tertiary amino group.
The bond between the polyamine compound and the acid group in the acid
group-containing polyurethane resin may be an ionic bond (for example, the ionic bond
14
between a tertiary amino group and a carboxyl group) or a covalent bond (for example,
an amide bond or the like).
The polyamine compound is preferably a polyamine compound having at least
one amino group selected from the group consisting of primary amino groups, secondary
amino groups, and tertiary 5 amino groups.
[0033]
Specific examples of the polyamine compound include alkylene diamines,
polyalkylene polyamines, and the like. Examples of the alkylene diamines include
C2-10 alkylene diamines such as ethylenediamine, 1,2-propylene diamine, 1,3-propylene
10 diamine, 1,4-butanediamine, and 1,6-hexamethylenediamine and the like. Examples of
the polyalkylene polyamines include tetraalkylene polyamine, furthermore, silicon
compounds having a plurality of basic nitrogen atoms (including a nitrogen atom such as
an amino group) (silane coupling agents and the like), and the like. Examples of the
silicon compound include 2-[N-(2-aminoethyl)amino]ethyltrimethoxysilane,
15 3-[N-(2-aminoethyl)amine]propyltriethoxysilane, and the like.
[0034]
The amine value of the polyamine compound is preferably 100 to 1900
mgKOH/g, more preferably 150 to 1900 mgKOH/g, still more preferably 200 to 1900
mgKOH/g, particularly preferably 200 to 1700 mgKOH/g, and most preferably 300 to
20 1500 mgKOH/g. When the amine value of the polyamine compound is the lower limit
value of the above-described range (100 mgKOH/g) or more, the gas barrier property of
the aqueous polyurethane resin (A) is excellent. When the amine value of the
polyamine compound is the upper limit value of the above-described range (1900
mgKOH/g) or less, the water dispersion stability of the aqueous polyurethane resin is
25 excellent.
15
When the amine value of the polyamine compound is 300 to 1500 mgKOH/g,
crosslinking reactions with the acid group-containing polyurethane are more
appropriately caused, and coating films formed of the coating agent develop a
particularly excellent oxygen barrier property even in high-humidity atmospheres.
The amine value of the polyamine compound is measured 5 by the following
method.
[Method for measuring amine values]
A specimen is weighed to 0.5 to 2 g (the amount of the specimen is represented
by S g). Neutral ethanol (BDG neutral) (30 g) is added to and dissolved in the weighed
10 specimen. As an indicator, bromophenol Blue is added to the obtained solution, and
titration is carried out using 0.2 mol/L of an ethanolic hydrochloric acid solution (titer f).
A point in time at which the color of the solution turns into yellow from green is
considered as the end point, and the amine value is obtained using the titration amount
(AmL) at this time and Calculation Equation 1.
15 Calculation Equation 1:
Amine value=A´f´0.2´56.108/S [mgKOH/g]
[0035]
In the aqueous polyurethane resin (A), the content of the polyamine compound
is preferably an amount at which the molar ratio of the acid groups in the acid
20 group-containing polyurethane resin to the basic nitrogen atoms in the polyamine
compound (acid groups/basic nitrogen atoms) is 10/1 to 0.1/1 and more preferably an
amount at which the molar ratio is 5/1 to 0.2/1. When the acid groups/basic nitrogen
atoms is in the above-described range (10/1 to 0.1/1), crosslinking reactions between the
acid groups in the acid group-containing polyurethane and the polyamine compound are
25 appropriately caused, and coating films formed of the coating agent develop an excellent
16
oxygen barrier property even in high-humidity atmospheres.
When the groups/basic nitrogen atoms is 5/1 to 0.2/1, crosslinking reactions
between the acid groups in the acid group-containing polyurethane and the polyamine
compound are appropriately caused in particular, and coating films formed of the coating
agent develop a particularly excellent oxygen barrier property even 5 in high-humidity
atmospheres.
[0036]
The aqueous polyurethane resin (A) is generally formed in a state of being
dissolved or dispersed in an aqueous medium.
10 Examples of the aqueous medium include water, water-soluble or hydrophilic
organic solvents, and mixtures thereof. The aqueous medium generally refers to water
or a medium including water as a principal component. The content of water in the
aqueous medium is preferably 70 mass% or more and more preferably 80 mass% or
more.
15 When the content of water in the aqueous medium is 70 mass% or more, the
dispersion stability of the aqueous polyurethane resin (A) is excellent, and, when the
content is 80 mass% or more, the water-based polyurethane resin (A) obtains particularly
excellent dispersion stability and stable long-term performance.
Examples of the water-soluble or hydrophilic organic solvents include alcohols
20 such as methanol, ethanol, and isopropanol; ketones such as acetone and methyl ethyl
ketone; ethers such as tetrahydrofuran; cellosolves; carbitols; nitriles such as acetonitrile;
and the like.
The aqueous medium may or may not include a neutralizer (base) that
neutralizes the acid groups. Generally, a neutralizer is included in the aqueous medium.
25 [0037]
17
The aqueous polyurethane resin (A) may have a form of an aqueous solution in
which a polyurethane resin is dissolved in the aqueous medium or a form of a water
dispersion element in which a polyurethane resin is dispersed in the aqueous medium.
In the water dispersion element, the average particle diameter of dispersed
particles (polyurethane resin particles) is not particularly limited, but is 5 preferably 20 nm
to 500 nm, more preferably 25 nm to 300 nm, and still more preferably 30 nm to 200 nm.
In a case in which the average particle diameter of dispersed particles exceeds the upper
limit value of the above-described range (500 nm), there is a concern that the uniform
dispersibility between the dispersed particles and other materials, the dispersion stability
10 of the coating agent may degrade, and the gas barrier property of coating films formed of
the coating agent may become insufficient.
In a case in which the average particle diameter of the dispersed particles is less
than the lower limit value of the above-described range (20 nm), it is not possible to
expect an effect of further improving the dispersion stability of the coating agent or the
15 gas barrier property of coating films formed of the coating agent. In addition, it is
substantially difficult to obtain the above-described dispersion element.
When the average particle diameter of the aqueous polyurethane resin (A) is 30
nm to 200 nm, the dispersion stability of the coating agent is favorable, and coating films
having an excellent gas barrier property and, furthermore, an excellent appearance
20 transparency can be formed.
The average particle diameter is a value measured using a fiber-optics particle
analyzer with auto-sampler (manufactured by Otsuka Electronics Co., Ltd., FPAR-10) in
a state of a concentration of the solid contents of 0.03 to 0.3 mass% (diluted with water).
[0038]
25 As the aqueous polyurethane resin (A), commercially available compounds may
18
be used or compounds manufactured using well-known manufacturing methods may be
used.
The method for manufacturing the aqueous polyurethane resin (A) is not
particularly limited, and ordinary techniques for turning polyurethane resins to be
aqueous such as an acetone method or a prepolymer method are used. 5 In urethanization
reactions, urethanization catalysts such as amine-based catalysts, tin-based catalysts, or
lead-based catalysts may be used as necessary.
For example, the acid group-containing polyurethane resin can be prepared by
reacting a polyisocyanate compound, a polyhydroxy acid, and, as necessary, at least one
10 of a polyol component and a chain extender component in an inert organic solvent such
as ketones such as acetone, ethers such as tetrahydrofuran, and nitriles such as
acetonitrile. More specifically, a prepolymer having an isocyanate group at the terminal
is obtained by reacting a polyisocyanate compound, a polyhydroxy acid, and a polyol
component in an inert organic solvent (particularly, a hydrophilic or water-soluble
15 organic solvent), the prepolymer is neutralized with a neutralizer and dissolved in an
aqueous medium or is dispersed and then reacted with a chain extender component added
so as to remove the organic solvent, whereby an aqueous solution or water dispersion
element of the acid group-containing polyurethane resin can be prepared.
A polyamine compound is added to the aqueous solution or water dispersion
20 element of the acid group-containing polyurethane resin obtained as described above and
is heated as necessary, whereby the aqueous polyurethane resin (A) in a form of an
aqueous solution or a water dispersion element can be prepared. In the case of heating,
the heating temperature is preferably 30°C to 60°C.
[0039]
25 “Water-soluble polymer (B)”
19
The “water-soluble polymer” refers to a polymer that is soluble in water.
Solution mentioned herein refers to a state in which polymers as a solute are dispersed in
water as a solvent at a molecular chain level and form a homogeneous system. More
specifically, solution refers to a state in which the intermolecular force between a
polymer chain and a water molecule becomes stronger than the intermolecular 5 force
between the molecular chains of a polymer chain, the entanglement of polymer chains is
dissociated, and the polymer chains are uniformly dispersed in water.
[0040]
The water-soluble polymer (B) is not particularly limited as long as the
10 water-soluble polymer is a compound capable of intruding between the unit crystal layers
of the inorganic layered mineral (C) described below and being coordinated (intercalated)
to the inorganic layered mineral.
Specific examples of the water-soluble polymer (B) include polyvinyl alcohol
resins such as polyvinyl alcohol and derivatives thereof; vinyl-based copolymers such as
15 polyvinyl pyrrolidone, polyacrylic acid, polymethacrylic acid, esters thereof, salts thereof,
copolymers thereof, polyhydroxyethyl methacrylate, and copolymers thereof; cellulose
derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; starches such as
oxidized starch, etherified starch, and dextrin; copolymerized polyesters having a polar
group such as sulfoisophthalic acid; urethane-based polymers, functional group-modified
20 polymers in which the carboxyl groups of a variety of the polymers described above are
modified, and the like.
When the coating film cohesion strength is taken into account, the degree of
polymerization of the water-soluble polymer (B) is preferably 200 or more.
[0041]
25 The number of types of the water-soluble polymer (B) in the coating agent may
20
be one or more.
The water-soluble polymer (B) preferably includes at least one polyvinyl alcohol
resin selected from the group consisting of polyvinyl alcohol-based polymers and
derivatives of polyvinyl alcohol-based polymers and particularly preferably includes a
polyvinyl alcohol resin having a degree of saponification of 95% or more 5 and a degree of
polymerization of 300 or more. The degree of polymerization of the polyvinyl alcohol
resin is preferably 300 to 2400 and particularly preferably 450 to 2000.
As the degree of saponification or the degree of polymerization increases, the
hygroscopic swellability of the polyvinyl alcohol resin becomes poorer, and a more
10 favorable gas barrier property is exhibited. When the degree of saponification of the
polyvinyl alcohol resin is less than 95%, there is a concern that a sufficient gas barrier
property cannot be obtained. In addition, when the degree of polymerization of the
polyvinyl alcohol resin is less than 300, there is a concern that the gas barrier property
and the coating film cohesion strength may degrade. On the other hand, in a case in
15 which the degree of polymerization exceeds 2400, the viscosity of the coating agent
increases, it is difficult to uniformly mix the coating agent with other components, and
there is a concern that degradation of the gas barrier property or the adhesion strength
may be caused.
When the degree of polymerization of the polyvinyl alcohol resin is 450 to 2000,
20 the gas barrier property and the coating film cohesion strength are excellent, and the
viscosity of the coating agent can also be decreased, and thus the application suitability
further improves.
[0042]
“Inorganic layered mineral (C)”
25 The “inorganic layered mineral” refers to an inorganic compound in which
21
extremely thin unit crystal layers are overlaid with each other so as to form one layered
particle.
The inorganic layered mineral (C) is preferably a compound that swells and/or
cleaves in water, and, among these compounds, clay compounds having swellability in
water are particularly preferred. More specifically, the inorganic layered 5 mineral (C) is
preferably a clay compound which coordinates water between extremely thin unit crystal
layers and has a property of water absorption and/or swelling. The above-described
clay compound is generally a compound in which layers in which Si4+ is coordinated to
O2- and a tetrahedral structure is constituted and layers in which Al3+, Mg2+, Fe2+, Fe3+,
10 and the like are coordinated to O2- and OH- and an octahedral structure is constituted are
bonded to each other in a ratio of 1/1 or 2/1 and are overlaid with each other, thereby
forming a layered structure. This clay compound may be a natural compound or a
synthesized compound.
[0043]
15 Typical examples of the inorganic layered mineral (C) include hydrous silicates
such as phyllosilicate minerals, and examples thereof include kaolinite-based clays
minerals such as halloysite, kaolinite, endelite, dickite, and nacrite; antigorite-based clay
minerals such as antigorite and chrysotile; smectite-based clay minerals such as
montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite, and stevensite;
20 vermiculite-based clay minerals such as vermiculite; mica or mica-based clay minerals
such as muscovite, phlogopite, margarite, tetrasilicic mica, and teniolite; and the like.
These inorganic layered minerals (C) can be used singly or two or more inorganic
layered minerals can be used in combination.
Among these inorganic layered minerals (C), smectite-based clay minerals such
25 as montmorillonite and mica-based clay minerals such as water-swellable mica are
22
particularly preferred.
[0044]
Regarding the size of the inorganic layered mineral (C), it is preferable that the
average particle diameter be 10 mm or less and the thickness be 500 nm or less. When
the average particle diameter and the thickness are respectively the 5 above-described
upper limit values (10 mm for the average particle diameter and 500 nm for the thickness)
or less, it becomes easy for the inorganic layered mineral (C) to be uniformly arrayed in
coating films formed of the coating agent, and the gas barrier property and the coating
film cohesion strength increases.
10 The inorganic layered mineral (C) particularly preferably includes at least
water-swellable synthetic mica having an average particle diameter of 1 to 10 mm and a
thickness of 10 to 100 nm. The water-swellable synthetic mica has a high miscibility
with the aqueous polyurethane resin (A) and the water-soluble polymer (B) and contains
fewer impurities than natural mica. Therefore, in a case in which water-swellable
15 synthetic mica is used as the inorganic layered mineral (C), the degradation of the gas
barrier property or a decrease in the coating film cohesion force arising from impurities is
not easily caused. In addition, water-swellable synthetic mica has fluorine atoms in the
crystal structure and thus also contributes to the humidity dependency of the gas barrier
property of coating films formed of the coating agent being suppressed at a low level.
20 Additionally, water-swellable synthetic mica has a higher aspect ratio than other
water-swellable inorganic layered minerals and thus causes a labyrinth effect to more
effectively work and contributes to the particularly favorable development of the gas
barrier property of coating films formed of the coating agent.
In a case in which the average particle diameter is less than 1 mm, the gas barrier
23
property of coating films degrades. In a case in which the average particle diameter is
more than 10 mm, the cohesion strength of coating films decreases, and additionally,
appearance unevenness is easily caused. For particles having an average particle
diameter of 1 mm or more and a thickness of 10 nm or less, it is difficult to maintain the
shape, and substantially, it is not easy to use such particles. In a 5 case in which the
thickness is more than 500 nm, uniform application is not possible, and the gas barrier
property degrades.
[0045]
“Epoxy compound (D)”
10 The epoxy compound (D) can be used without any particular limitation as long
as the epoxy compound is a compound having an epoxy group. For example, the epoxy
compound may be a monofunctional epoxy compound having one epoxy group or a
multifunctional epoxy compound having two or more epoxy groups. In addition, a
combination thereof may be used.
15 [0046]
Examples of the monofunctional epoxy compound include silane coupling
agents having an epoxy group such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,
3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane,
3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropylethyldiethoxysilane.
20 Examples of the monofunctional epoxy compound other than the silane coupling agents
having an epoxy group include phenyl glycidyl ether, 2-ethylhexyl glycidyl ether, ethyl
diethylene glycol glycidyl ether, dicyclopentadiene glycidyl ether, and 2-hydroxyethyl
glycidyl ether. These monofunctional epoxy compounds may be used singly or two or
more monofunctional epoxy compounds may be used in combination.
25 [0047]
24
Examples of the multifunctional epoxy compound include hydroquinone
diglycidyl ether, resorcinol diglycidyl ether, ethylene glycol diglycidyl ether,
polyethylene glycol diglycidyl ether, cyclohexene diol diglycidyl ether, cyclohexane
dimethanol diglycidyl ether, dicyclopentadiene diol diglycidyl ether, sorbitol
polyglycidyl ether, polyglycerol polyglycidyl ether, trimethylolpropane 5 triglycidyl ether,
pentaerythritol tetraglycidyl ether, phenol novolac-type epoxy resins, cresol novolac-type
epoxy resins, epoxidized polybutadiene, and the like. These multifunctional epoxy
compounds may be used singly or two or more multifunctional epoxy compounds may
be used in combination.
10 [0048]
The epoxy compound (D) is preferably the silane coupling agent having an
epoxy group or the multifunctional epoxy compound since it is possible to form a
complicated and strong crosslinking structure.
The multifunctional epoxy compound is preferably a tri- or higher-functional
15 epoxy compound since it is possible to form a complicated and strong crosslinking
structure.
The epoxy equivalent of the epoxy compound (D) is preferably 300 g/eq or less
and more preferably 250 g/eq or less. When the epoxy equivalent is the upper limit
value of the above-described range (300 g/eq) or less, a high crosslinking density can be
20 obtained.
When the epoxy equivalent is 250 g/ or less, coating films which are crosslinked
at a higher density and have strong adhesiveness can be obtained.
[0049]
The epoxy compound (D) is preferably a compound not having an isocyanate
25 group. In a case in which the epoxy compound (D) has an isocyanate group, rapid
25
reactions with components in the coating agent are caused, and there is a concern that the
usable time may be shortened.
[0050]
The epoxy compound (D) is preferably water-dispersible or water-soluble.
When the epoxy compound (D) is water-dispersible or water-soluble, 5 it is possible to
favorably mix the epoxy compound (D) and other components, and consequently, coating
films having a favorable barrier property in which cissing or unevenness is not caused
can be obtained.
The water solubility ratio of the epoxy compound (D) at 25°C is preferably 50
10 mass% or more, more preferably 60 mass% or more, and still more preferably 70 mass%
or more. The upper limit of the water solubility ratio is not particularly limited and may
be 100 mass%. When the water solubility ratio is the above-described lower limit value
(50 mass%) or more, it is possible to more favorably mix the epoxy compound (D) and
other components, and consequently, coating films having a favorable barrier property in
15 which cissing or unevenness is not caused can be obtained.
When the water solubility ratio of the epoxy compound is 60 mass% or more, in
addition to the favorable barrier property, highly transparent coating films having no
unevenness can be obtained, and, when the water solubility ratio is 70 mass% or more,
particularly highly transparent coating films can be obtained.
20 [0051]
The water solubility ratio refers to a value obtained by expressing in percentage
the amount (parts by mass) of the epoxy compound (D) that is dispersed or dissolved and
thus moves into water when 10 parts by mass of the epoxy compound is added to 90
parts by mass of water and is measured using the following method.
25 (Method for measuring water solubility ratio)
26
Water (90 g) and the epoxy compound (D) (10 g) are injected into a separating
funnel, are stirred for five minutes, and are left to stand for 20 minutes. After that, the
epoxy compound (D) that does not move into water (that is not dissolved in water and is
phase-separated from water) is collected, the mass (g) of the epoxy compound (D) that
does not move into water is measured, and the water solubility ratio 5 (%) is computed
using the following equation.
Water solubility ratio=[(X-Y)/X]´100
Here, X represents the mass of the epoxy compound (D) injected into the
separating funnel (=10 g), and Y represents the mass (g) of the epoxy compound (D)
10 collected from the separating funnel (not dissolved in water and phase-separated from
water).
[0052]
Generally, the coating agent according to the present embodiment includes the
aqueous medium described above.
15 The coating agent according to the present embodiment may further include a
variety of additives as necessary as long as the gas barrier property or the strength
suitable for laminated films for packing is not impaired.
Examples of the additives include an antioxidant, a weathering agent, a thermal
stabilizer, a lubricant, a crystal nucleus agent, an ultraviolet absorbent, a plasticizer, an
20 antistatic agent, a coloring agent, a filler, a surfactant, and the like.
[0053]
“Content fractions of individual components”
In the coating agent, the mass ratio of the aqueous polyurethane resin (A) to the
water-soluble polymer (B) in the solid content (aqueous polyurethane resin
25 (A)/water-soluble polymer (B)) is preferably 85/15 to 10/90, more preferably 75/25 to
27
20/80, and particularly preferably 70/30 to 25/75.
In a case in which the aqueous polyurethane resin (A)/water-soluble polymer (B)
is more than 85/15, there is a concern that unevenness may be caused during the
application of the coating agent. Unevenness during the application of the coating agent
leads to the deterioration of appearances or the degradation of the barrier 5 property. In a
case in which the aqueous polyurethane resin (A)/water-soluble polymer (B) is less than
10/90, the wettability to base films deteriorates, cissing and unevenness are easily caused
during application, and there is a concern that the generation of cissing and unevenness
may degrade the barrier property. When the aqueous polyurethane resin
10 (A)/water-soluble polymer (B) is in a predetermined range (85/15 to 10/90), the
wettability of the coating agent to base films is favorable, it is possible to evenly apply
the coating agent, and coating films having a favorable appearance or barrier property
can be formed.
When the aqueous polyurethane resin (A)/water-soluble polymer (B) is 75/25 to
15 20/80, highly transparent coating films having a favorable barrier property and,
furthermore, no unevenness can be obtained, and, when the aqueous polyurethane resin
(A)/water-soluble polymer (B) is 70/30 to 25/75, particularly highly transparent coating
films can be obtained.
[0054]
20 The content (solid content) of the inorganic layered mineral (C) in the coating
agent is preferably 5 mass% or more and 60 mass% or less, more preferably 7 mass% or
more and 45 mass% or less, and particularly preferably 10 mass% or more and 30 mass%
or less of the total solid content in the coating agent. When the content of the inorganic
layered mineral (C) is in the above-described range (5 mass% or more and 60 mass% or
25 less), it is possible to effectively exhibit the barrier property in high-humidity
28
environments while maintaining the cohesion strength of coating films formed of the
coating agent.
When the content of the inorganic layered mineral (C) is 7 mass% or more and
45 mass% or less, the balance between the coating film cohesion strength and the barrier
property in high-humidity environments is superior. When the content 5 of the inorganic
layered mineral (C) is 10 mass% or more and 30 mass% or less, the balance between the
membrane cohesion strength and the barrier property in high-humidity environments is
particularly excellent.
[0055]
10 The content (solid content) of the epoxy compound (D) in the coating agent is
preferably 0.5 mass% or more and 30 mass% or less, more preferably 1 mass% or more
and 25 mass% or less, and particularly preferably 3 mass% or more and 20 mass% or less
of the total solid content in the coating agent. When the content of the epoxy compound
(D) is in the above-described range (0.5 mass% or more and 30 mass% or less), it is
15 possible to sufficiently enhance the cohesive force of coating films formed of the coating
agent and the adhesion strength to base films while maintaining favorable wettability to
base films.
When the content (solid content) of the epoxy compound (D) in the coating
agent is 1 mass% or more and 25 mass% or less, the balance between the barrier property
20 and cohesive force of coating films formed of the coating agent and the adhesion strength
to base films is superior. When the content (solid content) of the epoxy compound (D)
in the coating agent is 3 mass% or more and 20 mass% or less, the balance between the
barrier property and cohesive force of coating films formed of the coating agent and the
adhesion strength to base films is particularly excellent.
25 [0056]
29
The total content (solid content) of the aqueous polyurethane resin (A), the
water-soluble polymer (B), the inorganic layered mineral (C), and the epoxy compound
(D) in the coating agent is preferably 85 mass% or more, more preferably 90 mass% or
more, and particularly preferably 95 mass% or more of the total solid content in the
coating agent. The upper limit of the total content is not particularly 5 limited and may be
100 mass%.
[0057]
The viscosity of the coating agent at 23°C is preferably 10 mPa×s to 80 mPa×s
and more preferably 10 mPa×s to 50 mPa×s.
10 When the viscosity is in a range of 10 mPa×s to 80 mPa×s, coating agents having
favorable applicability in which cissing or unevenness is not caused are obtained.
When the viscosity is in a range of 10 mPa×s to 50 mPa×s, flat coating films that are
uneven only to a small extent can be formed.
The viscosity is a value measured using an E-type viscometer.
15 [0058]
The coating agent according to the present embodiment can be prepared by
mixing the aqueous polyurethane resin (A), the water-soluble polymer (B), the inorganic
layered mineral (C), the epoxy compound (D), if necessary, additives, an additional
aqueous medium, and the like. The mixing order of the respective components is not
20 particularly limited.
The epoxy compound (D) may be mixed together with other components or be
added immediately before the application of the coating agent to base films.
[0059]
“Exerting effects”
30
The coating agent according to the present embodiment includes the aqueous
polyurethane resin (A) containing the polyurethane resin having acid groups and the
polyamine compound, the water-soluble polymer (B), the inorganic layered mineral (C),
and the epoxy compound (D), and thus it is possible to form coating films exhibiting an
excellent gas barrier property even in high-humidity atmospheres. 5 In addition, the
coating films are excellent in terms of the adhesion strength or coating film cohesion
strength to other materials (for example, base films or thermally fused layers described
below). Therefore, when the coating film and other films are attached to each other so
as to produce packing materials, sufficient lamination strength can be obtained.
10 Therefore, when gas barrier films having coating films formed of the coating
agent according to the present embodiment are used as packing materials, it is possible to
enhance the quality-maintaining property of contents.
It is considered that the epoxy group reacts with hydroxyl groups in the aqueous
polyurethane resin (A) or the water-soluble polymer (B) and thus exhibits favorable
15 adhesiveness to base films formed of plastic materials. In addition, it is considered that
reaction products of the aqueous polyurethane resin (A), the water-soluble polymer (B),
and the epoxy compound (D) are strong and capable of improving the cohesion strength
of coating films formed of the coating agent.
[0060]
20 Furthermore, the coating agent according to the present embodiment has a long
usable time.
In the conventional art, curing agents having isocyanate groups are frequently
used in order to exhibit adhesion strength between coating films formed of coating agents
including aqueous polyurethane resins as a principal component and base films.
25 However, in a case in which a curing agent having isocyanate groups is used, the coating
31
agent needs to be a two-liquid-type coating agent that is added immediately before the
application since the usable time after the addition of the curing agent to the coating
agent is short.
The epoxy group slowly reacts in the coating agent, and a majority of the epoxy
compound (D) reacts after the application of the coating agent. 5 Therefore, it is
considered that the usable time of the coating agent after the addition of the epoxy
compound (D) is long.
Therefore, even in a case in which the coating agent according to the present
embodiment is a one-liquid-type coating agent, the performance of gas barrier films to be
10 obtained is not easily affected by the time taken from the preparation of the coating agent
to the formation of coating films, and gas barrier films having favorable performance
stability can be manufactured. Therefore, it is possible to stabilize the performance of
coating films formed of the coating agent or simplify blending facilities.
[0061]
15
A gas barrier film according to a second embodiment of the present invention
includes a base film formed of a plastic material and a coating film which is laminated on
at least one surface of the base film and is formed of the coating agent according to the
first embodiment of the present invention.
20 [0062]
Examples of the plastic material constituting the base film include olefin-based
resins such as polyethylene, polypropylene, and poly C2-10 olefins such as
propylene-ethylene copolymers; polyester-based resins such as polyethylene
terephthalate and polybutylene terephthalate; polyamide-based resins such as aliphatic
25 polyamides such as nylon 6 and nylon 66 and aromatic polyamides such as
32
polymetaxylylene adipamide; vinyl-based resins such as polystyrene, polyvinyl acetate,
ethylene-vinyl acetate copolymers, polyvinyl alcohol, and ethylene-vinyl alcohol
copolymers; acrylic resins such as homo or copolymers of (meth)acrylic monomers such
as polymethyl methacrylate and polyacrylonitrile; cellophane, and the like. These resins
can be used singly or two or more resins can be used 5 in combination.
[0063]
Examples of the base film include monolayer films constituted of a single resin,
monolayer or laminated films for which a plurality of resins is used, and the like. In
addition, laminated base materials obtained by laminating the above-described resin on
10 another base material (metal, wood, paper, ceramic, or the like) may be used.
The base film is preferably a polyolefin-based resin film (particularly, a
polypropylene film or the like), a polyester-based resin film (particularly, a polyethylene
terephthalate-based resin film), a polyamide-based resin film (particularly, a nylon film),
or the like.
15 [0064]
The base film may be a non-stretched film or a monoaxial or biaxial stretched
oriented film.
In order to improve the wettability to the coating agent and the bonding strength
to the coating film, a surface treatment such as a corona treatment or a low-temperature
20 plasma treatment may be carried out on a surface of the base film on which the coating
film formed of the coating agent is laminated (a surface coated with the coating agent).
On the surface of the base film on which the coating film formed of the coating
agent is laminated, an anchor coat or undercoat treatment may be carried out.
[0065]
25 The thickness of the base film is not particularly limited, is appropriately
33
selected depending on the costs or usages in consideration of suitability as packing
materials or the lamination suitability of coating films, and is practically 3 mm to 200 mm,
preferably 5 mm to 120 mm, and more preferably 10 mm to 100 mm.
[0066]
The coating film formed of the coating agent according 5 to the present
embodiment can be formed by applying the coating agent according to the first
embodiment of the present invention on a single surface (one surface) or both surfaces of
the base film so as to form a coat made (formed) of the coating agent and drying the coat.
As the method for applying the coating agent, well-known wet-type coating
10 methods can be used. Examples of the wet-type coating methods include roll coating,
gravure coating, reverse coating, die coating, screen printing, spray coating, and the like.
As the method for drying the coat formed of the coating agent, it is possible to
used well-known drying methods such as hot-air drying, hot-roll drying, and infrared
irradiation.
15 [0067]
The thickness of the coating film formed of the coating agent according to the
first embodiment of the present invention, that is, the thickness of the coat formed of the
coating agent after drying is set depending on required gas barrier properties, but is
preferably 0.1 mm to 5 mm, preferably 0.2 mm to 2 mm, and more preferably 0.3 mm to 1
20 mm. When the thickness of the coating film made of the coating agent is the lower limit
value of the above-described range (0.1 mm) or more, a sufficient gas barrier property can
be easily obtained. When the thickness of the coating film made of the coating agent is
the upper limit value of the above-described range (5 mm) or less, it is easy to form
uniformly coated surfaces, and drying loads or manufacturing costs can be suppressed.
34
When the thickness of the coating film is in a range of 0.3 mm to 1 mm, the
balance among the gas barrier property, the addition of drying, and the manufacturing
costs is superior.
[0068]
The gas barrier film according to the second embodiment 5 of the present
invention may further have a printing layer, an undercoat layer, an overcoat layer, a
light-shielding layer, an adhesive layer, a heat-sealable thermally fused layer, and other
functional layers as necessary.
In a case in which the gas barrier film according to the present embodiment has
10 a heat-sealable thermally fused layer, this thermally fused layer is disposed on at least
one outermost layer of the gas barrier film. When the gas barrier film has the thermally
fused layer, the gas barrier film can be sealed by thermal sealing.
The thermally fused layer can be laminated on, for example, a laminate obtained
by forming a coating film on a single surface or both surfaces of the base film using the
15 coating agent according to the first embodiment of the present invention using a
well-known adhesive such as a polyurethane-based adhesive, a polyester-based adhesive,
or a polyether-based adhesive and a well-known dry lamination method, extrusion
lamination method, or the like.
[0069]
20 “Exerting effects”
In the gas barrier film according to the second embodiment of the present
invention, a coating film formed of the coating agent including the aqueous polyurethane
resin (A) including the polyurethane resin having an acid group and the polyamine
compound, the water-soluble polymer (B), the inorganic layered mineral (C), and the
25 epoxy compound (D) is laminated on at least one surface of the base film formed of a
35
plastic material.
This coating film, as described above, exhibits an excellent gas barrier property
even in high-humidity atmospheres and is excellent in terms of the adhesion strength or
coating film cohesion strength to other materials (for example, the base film or the
thermally 5 fused layer).
Therefore, the gas barrier film according to the present embodiment is excellent
in terms of the gas barrier property in high-humidity atmospheres and has sufficient
adhesion strength or coating film cohesion strength as packing materials. Therefore,
when the gas barrier film according to the present embodiment is used as packing
10 materials, it is possible to enhance the quality-maintaining property of contents.
[0070]
The gas barrier film according to the present embodiment is useful as packing
materials for, for example, food which needs to avoid moisture and oxygen such as dried
food, sweets, bread, and delicacies and medicinal products such as disposable body
15 warmers, tablets, medicinal powder, fomentation, and adhesive skin patches.
In addition, the gas barrier film according to the present embodiment can be
used in packing fields in which a favorable gas barrier property and transparency which
enables the identification of contents are required.
[0071]
20
A coating agent according to a third embodiment of the present invention
includes, as principal components: an aqueous polyurethane resin (A), a water-soluble
polymer (B), an inorganic layered mineral (C), and a silane coupling agent (E).
[0072]
25 In the present embodiment and a fourth embodiment described below, “aqueous
36
polyurethane resin (A)”, “water-soluble polymer (B)”, and “inorganic layered mineral
(C)” are the same compounds and components as the compounds and components
described in the first embodiment and the second embodiment, and descriptions
regarding a variety of parameters such as the compositional ratios are also identical
thereto, and thus the compounds and components will be given the same 5 reference sign
(the same name) and will not be described again.
Hereinafter, the coating agent according to the third embodiment and a gas
barrier film according to the fourth embodiment in which the “silane coupling agent (E)”
is used instead of the “compound (D) having an epoxy group” in the first embodiment
10 and the second embodiment will be described.
[0073]
“Silane coupling agent”
As the silane coupling agent (E), ordinarily used compounds can be used, and
examples thereof include compounds having alkoxy groups and organic reactive groups
15 bonded to silicon atoms.
Alkoxy groups in the silane coupling agent (E) hydrolyze and thus generate
silanol groups and exhibit interaction effects such as reactions, adsorption, and the like
between the silanol groups and inorganic compounds. In the coating agent according to
the third embodiment of the present invention, the inorganic layered mineral (C) and the
20 silane coupling agent (E) interact with each other, thereby improving the cohesion
strength of coating films formed of the coating agent. In addition, organic reactive
groups in the silane coupling agent (E) react with organic components such as the
urethane resin (A) and the water-soluble polymer (B), thereby improving the adhesion
strength of coating films formed of the coating agent to base films formed of a plastic
25 material. Therefore, the inclusion of the silane coupling agent (E) enhances the
37
cohesion strength of coating films formed of the coating agent and improves the adhesive
force between the coating films and base films or other base materials, whereby it is
possible to enhance the practical strength as packing materials.
[0074]
Examples of the silane coupling agent (E) include compounds 5 represented by
RSiX3 (here, R represents an organic reactive group, and X represents an alkoxy group).
Examples of the organic reactive groups include reactive groups having an
amino group, a (meth)acryl group, an epoxy group, a vinyl group, a mercapto group, an
isocyanate group, an isocyanurate group, or the like. The (meth)acryl group refers to
10 both an acryl group and a methacryl group.
Examples of the alkoxy groups include a methoxy group, an ethoxy group, and
the like.
[0075]
As the silane coupling agent (E), compounds in which organic reactive groups
15 are reactive with components in the coating agent are preferably used. Examples of
silane coupling agents having a vinyl group include vinyltrimethoxysilane,
vinyltriethoxysilane, and the like. Examples of silane coupling agents having an epoxy
group include 2(3,4-epoxycyclohexyl)ethyltrimethoxysilane,
3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane,
20 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylethyldiethoxysilane, and
the like. Examples of silane coupling agents having an amino group include
3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane,
N-2(aminoethyl)-3-aminopropyltrimethoxysilane,
N-2(aminoethyl)-3-aminopropylmethyldimethoxysilane, and the like. Examples of
25 silane coupling agents having a mercapto group include
38
3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and the
like. Examples of silane coupling agents having a (meth)acryl group include
3-acryloxypropyltrimethoxysilane and the like. Examples of silane coupling agents
having an isocyanate group include 3-isocyanatepropyltriethoxysilane and the like.
Examples of silane coupling agents having an isocyanurate 5 group include
tris-(trimethoxysilylpropyl)isocyanurate and the like. These silane coupling agents may
be used singly or two or more silane coupling agents may be used in combination.
[0076]
The silane coupling agent (E) is preferably a compound not having an
10 isocyanate group.
In a case in which the silane coupling agent (E) has an isocyanate group, rapid
reactions with components in the coating agent are caused, and there is a concern that the
applicability may be adversely affected.
[0077]
15 The silane coupling agent (E) is preferably a compound having an epoxy group.
The epoxy group has a favorable reactivity with hydroxyl groups in the aqueous urethane
resin (A) or the water-soluble polymer (B), and thus the adhesion strength of coating
films formed of the coating agent to base films are particularly strongly exhibited.
[0078]
20 Generally, the coating agent according to the third embodiment of the present
invention includes the aqueous medium described in the first embodiment and the second
embodiment.
The coating agent according to the third embodiment of the present invention
may further include a variety of additives as necessary as long as the gas barrier property
25 or the strength suitable for laminated films for packing is not impaired.
39
Examples of the additives include an antioxidant, a weathering agent, a thermal
stabilizer, a lubricant, a crystal nucleus agent, an ultraviolet absorbent, a plasticizer, an
antistatic agent, a coloring agent, a filler, a surfactant, and the like.
[0079]
“Content fractions of individual 5 components”
In the coating agent, the mass ratio of the aqueous polyurethane resin (A) to the
water-soluble polymer (B) in the solid content (aqueous polyurethane resin
(A)/water-soluble polymer (B)) is preferably 85/15 to 10/90, more preferably 75/25 to
20/80, and particularly preferably 70/30 to 25/75.
10 In a case in which the aqueous polyurethane resin (A)/water-soluble polymer (B)
is more than 85/15, there is a concern that unevenness may be caused during the
application of the coating agent. Unevenness during the application of the coating agent
leads to the deterioration of appearances or the degradation of the barrier property. In a
case in which the aqueous polyurethane resin (A)/water-soluble polymer (B) is less than
15 10/90, the wettability of the coating agent to base films deteriorates, cissing and
unevenness are easily caused during the application of the coating agent, and there is a
concern that the generation of cissing and unevenness may degrade the barrier property.
When the aqueous polyurethane resin (A)/water-soluble polymer (B) is in a
predetermined range (85/15 to 10/90), the wettability of the coating agent to base films is
20 favorable, it is possible to evenly apply the coating agent, and coating films having a
favorable appearance or barrier property can be formed.
When the aqueous polyurethane resin (A)/water-soluble polymer (B) is 75/25 to
20/80, evenly highly transparent coating films having a favorable barrier property can be
obtained, and, when the aqueous polyurethane resin (A)/water-soluble polymer (B) is
25 70/30 to 25/75, particularly highly transparent coating films can be obtained.
40
[0080]
The content (solid content) of the inorganic layered mineral (C) in the coating
agent is preferably 5 mass% or more and 60 mass% or less, more preferably 7 mass% or
more and 45 mass% or less, and particularly preferably 10 mass% or more and 30 mass%
or less of the total solid content in the coating agent. When the content 5 of the inorganic
layered mineral (C) is in the above-described range (5 mass% or more and 60 mass% or
less), it is possible to effectively exhibit the barrier property in high-humidity
environments while maintaining the cohesion strength of coating films formed of the
coating agent.
10 When the content of the inorganic layered mineral (C) is 7 mass% or more and
45 mass% or less, the balance between the coating film cohesion strength and the barrier
property in high-humidity environments is superior. When the content of the inorganic
layered mineral (C) is 10 mass% or more and 30 mass% or less, the balance between the
coating film cohesion strength and the barrier property in high-humidity environments is
15 particularly excellent.
[0081]
The content (solid content) of the silane coupling agent (E) in the coating agent
is preferably 0.5 mass% or more and 30 mass% or less, more preferably 1 mass% or
more and 25 mass% or less, and particularly preferably 3 mass% or more and 20 mass%
20 or less of the total solid content in the coating agent. When the content of the silane
coupling agent (E) is in the above-described range (0.5 mass% or more and 30 mass% or
less), it is possible to sufficiently enhance the cohesive force of coating films formed of
the coating agent and the adhesion strength of the coating agent to base films while
maintaining the favorable wettability of the coating agent to base films.
25 When the content (solid content) of the silane coupling agent (E) in the coating
41
agent is 1 mass% or more and 25 mass% or less, the balance between the barrier property
and cohesive force of coating films formed of the coating agent and the adhesion strength
to base films is superior. When the content (solid content) of the silane coupling agent
(E) in the coating agent is 3 mass% or more and 20 mass% or less, the balance between
the barrier property and cohesive force of coating films formed of the 5 coating agent and
the adhesion strength to base films is particularly excellent.
[0082]
The total content (solid content) of the aqueous polyurethane resin (A), the
water-soluble polymer (B), the inorganic layered mineral (C), and the silane coupling
10 agent (E) in the coating agent is preferably 85 mass% or more, more preferably 90
mass% or more, and particularly preferably 95 mass% or more of the total solid content
in the coating agent. The upper limit of the total content is not particularly limited and
may be 100 mass%.
[0083]
15 The viscosity of the coating agent at 23°C is preferably 10 mPa×s to 80 mPa×s
and more preferably 10 mPa×s to 50 mPa×s.
When the viscosity is in a range of 10 mPa×s to 80 mPa×s, coating agents having
favorable applicability in which cissing or unevenness is not caused are obtained.
When the viscosity is in a range of 10 mPa×s to 50 mPa×s, flat coating films that are
20 uneven only to a small extent can be formed.
The viscosity is a value measured using an E-type viscometer.
[0084]
The coating agent according to the present embodiment can be prepared by
mixing the aqueous polyurethane resin (A), the water-soluble polymer (B), the inorganic
42
layered mineral (C), the silane coupling agent (E), if necessary, additives, an additional
aqueous medium, and the like. The mixing order of the respective components is not
particularly limited.
The silane coupling agent (E) may be mixed together with other components or
be added immediately before the application of the coating agent 5 to base films.
[0085]
“Exerting effects”
The coating agent according to the present embodiment includes the aqueous
polyurethane resin (A) containing the polyurethane resin having acid groups and the
10 polyamine compound, the water-soluble polymer (B), the inorganic layered mineral (C),
and the silane coupling agent (E), and thus it is possible to form coating films exhibiting
an excellent gas barrier property even in high-humidity atmospheres. In addition, the
coating films are excellent in terms of the adhesion strength or coating film cohesion
strength to other materials (for example, base films or thermally fused layers described
15 below). Therefore, when the coating agent and other films are attached to each other so
as to produce packing materials, sufficient lamination strength can be obtained.
Therefore, when gas barrier films having coating films formed of the coating
agent according to the present embodiment are used as packing materials, it is possible to
enhance the quality-maintaining property of contents.
20 [0086]
Furthermore, the coating agent according to the present embodiment has a long
usable time.
In the conventional art, curing agents having isocyanate groups are frequently
used in order to exhibit the adhesion strength between coating films formed of coating
25 agents including aqueous polyurethane resins as a principal component and base films.
43
However, in a case in which a curing agent having isocyanate groups is used, the coating
agent needs to be a two-liquid-type coating agent that is added immediately before the
application since the usable time after the addition of the curing agent to the coating
agent is short.
The silane coupling agent (E) has a longer usable time in the 5 co-presence of the
aqueous polyurethane resin (A), the water-soluble polymer (B), and the inorganic layered
mineral (C) than other curing agents. Therefore, it is possible to produce the coating
agent as a one-liquid-type coating agent that is added together with other components.
Even in a case in which the coating agent is produced as a one-liquid-type coating agent,
10 the performance of gas barrier films to be obtained is not easily affected by the time
taken from the preparation of the coating agent to the formation of coating films, and gas
barrier films having favorable performance stability can be manufactured. Therefore, it
is possible to stabilize the performance of coating films formed of the coating agent or
simplify blending facilities.
15 [0087]

A gas barrier film according to a fourth embodiment of the present invention
includes a base film formed of a plastic material and a coating film which is laminated on
at least one surface of the base film and is formed of the coating agent according to the
20 third embodiment of the present invention.
[0088]
Examples of the plastic material constituting the base film include olefin-based
resins such as polyethylene, polypropylene, and poly C2-10 olefins such as
propylene-ethylene copolymers; polyester-based resins such as polyethylene
25 terephthalate and polybutylene terephthalate; polyamide-based resins such as aliphatic
44
polyamides such as nylon 6 and nylon 66 and aromatic polyamides such as
polymetaxylylene adipamide; vinyl-based resins such as polystyrene, polyvinyl acetate,
ethylene-vinyl acetate copolymers, polyvinyl alcohol, and ethylene-vinyl alcohol
copolymers; acrylic resins such as homo or copolymers of (meth)acrylic monomers such
as polymethyl methacrylate and polyacrylonitrile; cellophane, and the like. 5 These resins
can be used singly or two or more resins can be used in combination.
[0089]
Examples of the base film include monolayer films constituted of a single resin,
monolayer or laminated films for which a plurality of resins is used, and the like. In
10 addition, laminated base materials obtained by laminating the above-described resin on
another base material (metal, wood, paper, ceramic, or the like) may be used.
The base film is preferably a polyolefin-based resin film (particularly, a
polypropylene film or the like), a polyester-based resin film (particularly, a polyethylene
terephthalate-based resin film), a polyamide-based resin film (particularly, a nylon film),
15 or the like.
[0090]
The base film may be a non-stretched film or a monoaxial or biaxial stretched
oriented film.
In order to improve the wettability to the coating agent and the bonding strength
20 to the coating film, a surface treatment such as a corona treatment or a low-temperature
plasma treatment may be carried out on a surface of the base film on which the coating
film formed of the coating agent is laminated (a surface coated with the coating agent).
On the surface of the base film on which the coating film formed of the coating
agent is laminated, an anchor coat or undercoat treatment may be carried out.
25 [0091]
45
The thickness of the base film is not particularly limited, is appropriately
selected depending on the costs or usages in consideration of suitability as packing
materials or the lamination suitability of coating films, and is practically 3 mm to 200 mm,
preferably 5 mm to 120 mm, and more preferably 10 mm to 100 mm.
5 [0092]
The coating film formed of the coating agent according to the third embodiment
of the present invention can be formed by applying the coating agent according to the
third embodiment of the present invention on a single surface (one surface) or both
surfaces of the base film so as to form a coating made of the coating agent (formed of the
10 coating agent) and drying the coating.
As the method for applying the coating agent, well-known wet-type coating
methods can be used. Examples of the wet-type coating methods include roll coating,
gravure coating, reverse coating, die coating, screen printing, spray coating, and the like.
As the method for drying the coat formed of the coating agent, it is possible to
15 used well-known drying methods such as hot-air drying, hot-roll drying, and infrared
irradiation.
[0093]
The thickness of the coating film formed of the coating agent according to the
third embodiment of the present invention, that is, the thickness of the coat formed of the
20 coating agent after drying is set depending on required gas barrier properties, but is
preferably 0.1 mm to 5 mm, preferably 0.2 mm to 2 mm, and more preferably 0.3 mm to 1
mm. When the thickness of the coating film made of the coating agent is the lower limit
value of the above-described range (0.1 mm) or more, a sufficient gas barrier property can
be easily obtained. When the thickness of the coating film made of the coating agent is
46
the upper limit value of the above-described range (5 mm) or less, it is easy to form
uniformly coated surfaces, and drying loads or manufacturing costs can be suppressed.
When the thickness of the coating film is in a range of 0.3 mm to 1 mm, the
balance among the gas barrier property, the addition of drying, and the manufacturing
5 costs is superior.
[0094]
The gas barrier film according to the fourth embodiment of the present invention
may further have a printing layer, an undercoat layer, an overcoat layer, a light-shielding
layer, an adhesive layer, a heat-sealable thermally fused layer, and other functional layers
10 as necessary.
In a case in which the gas barrier film according to the present embodiment has
a heat-sealable thermally fused layer, this thermally fused layer is disposed on at least
one outermost layer of the gas barrier film. When the gas barrier film has the thermally
fused layer, the gas barrier film can be sealed by thermal sealing.
15 The thermally fused layer can be laminated on, for example, a laminate obtained
by forming a coating film on a single surface or both surfaces of the base film using the
coating agent according to the third embodiment of the present invention using a
well-known adhesive such as a polyurethane-based adhesive, a polyester-based adhesive,
or a polyether-based adhesive and a well-known dry lamination method, extrusion
20 lamination method, or the like.
[0095]
“Exerting effects”
In the gas barrier film according to the fourth embodiment of the present
invention, a coating film formed of the coating agent including the aqueous polyurethane
25 resin (A) including the polyurethane resin having an acid group and the polyamine
47
compound, the water-soluble polymer (B), the inorganic layered mineral (C), and the
silane coupling agent (E) is laminated on at least one surface of the base film formed of a
plastic material.
This coating film, as described above, exhibits an excellent gas barrier property
even in high-humidity atmospheres and is excellent in terms of the adhesion 5 strength or
coating film cohesion strength to other materials (for example, the base film or the
thermally fused layer).
Therefore, the gas barrier film according to the present embodiment is excellent
in terms of the gas barrier property in high-humidity atmospheres and has sufficient
10 adhesion strength or coating film cohesion strength as packing materials. Therefore,
when the gas barrier film according to the present embodiment is used as packing
materials, it is possible to enhance the quality-maintaining property of contents.
[0096]
The gas barrier film according to the present embodiment is useful as packing
15 materials for, for example, food which needs to avoid moisture and oxygen such as dried
food, sweets, bread, and delicacies and medicinal products such as disposable body
warmers, tablets, medicinal powder, fomentation, and adhesive skin patches.
In addition, the gas barrier film according to the present embodiment can be
used in packing fields in which a favorable gas barrier property and transparency which
20 enables the identification of contents are required.
Examples
[0097]
Hereinafter, the embodiments of the present invention will be more specifically
described using examples and comparative examples. However, the present invention is
25 not limited to the following examples.
48
Hereinafter, materials used in individual examples described below will be
described.
[0098]

“Aqueous polyurethane 5 resin (A)”
(A1): An aqueous polyurethane resin containing a polyurethane resin having
acid groups and a polyamine compound, an aqueous polyurethane dispersion
“TAKELAC (registered trademark) WPB-341” manufactured by Mitsui Chemicals, Inc.
[0099]
10 “Water-soluble polymer (B)”
(B1): A polyvinyl alcohol having a degree of saponification of 98% to 99% and
a degree of polymerization of 500 (trade name: POVAL PVA-105, manufactured by
Kuraray Co., Ltd.)
(B2): Carboxymethyl cellulose (CMC)
15 [0100]
“Inorganic layered mineral (C)”
(C1): Water-swellable synthetic mica (trade name: SOMASIF (registered
trademark) MEB-3, manufactured by Co-op Chemical Co., Ltd.)
(C2): Sodium hectorite (trade name: NHT-sol B2, manufactured by Topy
20 Industries Limited.)
[0101]
“Epoxy compound (D) and comparative product of epoxy compound (D)”
(D1): Sorbitol polyglycidyl ether (trade name: DENACOL (registered
trademark) EX-614, manufactured by Nagase ChemteX Corporation, tetra- or
25 higher-functional, water solubility ratio: 78%)
49
(D2): Polyglycerol polyglycidyl ether (trade name: DENACOL EX-521,
manufactured by Nagase ChemteX Corporation, tetra- or higher-functional, water
solubility ratio: 100%)
(D3): 3-Glycidoxypropyltriethoxysilane (trade name: KBE-403, manufactured
by Shin-Etsu Silicone Co., Ltd., monofunctional, water solubility 5 ratio: 100%)
(D4): Resorcinol diglycidyl ether (trade name: DENACOL EX-201,
manufactured by Nagase ChemteX Corporation, bifunctional, water solubility ratio: 0%)
(D5): Trimethylolpropane polyglycidyl ether (trade name: DENACOL EX-321,
manufactured by Nagase ChemteX Corporation, bi- or trifunctional, water solubility
10 ratio: 27%)
(D6): 3’,4’-Epoxycyclohexyl 3,4-epoxycyclohexane carboxylate (trade name:
CELLOXIDE (registered trademark) 2021P, manufactured by Daicel Corporation,
bifunctional, water solubility ratio: 0%)
Comparative product: Isocyanate-based compound (trade name: TAKENATE
15 (registered trademark) WD-725 manufactured by Mitsui Chemicals, Inc.)
[0102]
“Silane coupling agent (E) and comparative product of silane coupling agent
(E)”
(E1): 3-Glycidoxypropyltriethoxysilane (trade name: KBE-403, manufactured
20 by Shin-Etsu Silicone Co., Ltd.)
(E2): 2-(3,4-Epoxycyclohexyl)ethyltrimethoxysilane (trade name: KBE-303,
manufactured by Shin-Etsu Silicone Co., Ltd.)
(E3): Tris-(trimethoxysilyl)triisocyanurate (trade name: KBM-9659,
manufactured by Shin-Etsu Silicone Co., Ltd.)
25 (E4): 3-Mercaptopropyltrimethoxysilane (trade name: KBM-803, manufactured
50
by Shin-Etsu Silicone Co., Ltd.)
Comparative product: Isocyanate-based curing agent (trade name: TAKENATE
(registered trademark) WD-725, manufactured by Mitsui Chemicals, Inc.)
[0103]
<5 Examples 1 to 15>
First, the aqueous polyurethane resin (A) and the water-soluble polymer (B)
were blended with each other according to the types and the compounding ratio (mass%)
shown in Tables 1 and 2, next, the inorganic layered mineral (C) was added thereto, and,
after that, the mixture was diluted with ion exchange water and isopropanol so that the
10 content of isopropanol was 10 mass% of the entire aqueous medium and the
concentration of the solid contents was 8.2 mass%. To the obtained diluted substance,
the epoxy compound (D) was added according to the types and the compounding ratio
(mass%) shown in Tables 1 and 2, thereby preparing coating agents of Examples 1 to 15.
Here, the compounding ratio refer to the proportions of the respective components in the
15 entire solid content in terms of the solid content, which will also be the case below.
[0104]
Gas barrier films were obtained in the following order using the coating agents
of Examples 1 to 15 which had been just prepared (immediately after the addition of the
epoxy compound (D)).
20 The coating agent was applied onto a corona-treated surface of a biaxial
stretched polypropylene film (trade name: U-1, thickness: 20 mm, manufactured by
Mitsui Chemicals Tohcello. Inc.) which was a base film using a gravure printer and was
dried so as to form a coating film, thereby obtaining a gas barrier film.
The thicknesses of the formed coating films were confirmed and measured using
25 an electronic microscope and were found to be all 0.6 mm.
51
[0105]
After the preparation, the coating agents of Examples 1 to 15 were stored at
23°C for one week. Coating films were formed on a corona-treated surface of a base
film in the same manner as described above using the coating agents that had been stored
for one week, thereby obtaining 5 gas barrier films.
[0106]

First, the aqueous polyurethane resin (A) and the water-soluble polymer (B)
were blended with each other according to the types and the compounding ratio (mass%)
10 shown in Table 3, next, the inorganic layered mineral (C) was added thereto, and, after
that, the mixture was diluted with ion exchange water and isopropanol so that the content
of isopropanol was 10 mass% of the entire aqueous medium and the concentration of the
solid contents was 8.2 mass%. To the obtained diluted substance, the epoxy compound
(D) or the comparative product of the epoxy compound (D) was added according to the
15 types and the compounding ratio (mass%) shown in Table 3, thereby preparing coating
agents of Comparative Examples 1 to 5.
[0107]
Gas barrier films were obtained in the following order using the coating agents
of Comparative Examples 1 to 5 which had been just prepared (immediately after the
20 addition of the epoxy compound (D) or the comparative product of the epoxy compound
(D)).
The coating agent was applied onto a corona-treated surface of a biaxial
stretched polypropylene film (trade name: U-1, thickness: 20 mm, manufactured by
Mitsui Chemicals Tohcello. Inc.) which was a base film using a gravure printer and was
25 dried so as to form a coating film, thereby obtaining a gas barrier film.
52
The thicknesses of the formed coating films were confirmed and measured using
an electronic microscope and were found to be all 0.6 mm.
[0108]
After the preparation, the coating agents of Comparative Examples 1 to 5 were
stored at 23°C for one week. Coating films were formed on a corona-5 treated surface of
a base film in the same manner as described above using the coating agents that had been
stored for one week, thereby obtaining gas barrier films.
[0109]

10 (1) Oxygen gas barrier property
For the gas barrier films of Examples 1 to 15 and Comparative Examples 1 to 5,
the oxygen permeation rate (cm3/(m2×day×MPa)) in an atmosphere of 20°C and 80%RH
was measured using an oxygen permeation rate measurement instrument (trade name:
OXTRAN-2/20, manufactured by MOCON Inc.).
15 The evaluation results are shown in Tables 1 to 3. The oxygen permeation
rates of the gas barrier films obtained by the application of the coating agent to which the
epoxy compound (D) or the comparative product of the epoxy compound (D) had been
just added are shown in the “initial oxygen permeation rate” row, and the oxygen
permeation rates of the gas barrier films obtained by the application of the coating agent
20 to which the epoxy compound (D) or the comparative product of the epoxy compound
(D) had been added and then stored for one week are shown in the “oxygen permeation
rate after 1W storage” row.
[0110]
(2) Lamination strength
25 A 30 mm-thick non-stretched polypropylene film (trade name: CPP GLC,
53
manufactured by Mitsui Chemicals Tohcello. Inc.) was laminated on a coated surface
side (coating film side) of the gas barrier film obtained in each of Examples 1 to 15 and
Comparative Examples 1 to 5 through a polyester urethane-based adhesive (trade name:
TAKELAC A-969, TAKENATE A-5, manufactured by Mitsui Chemicals, Inc.) by a dry
lamination process and was cured at 50°C for 48 hours, thereby obtaining 5 a laminate
film.
The laminate film was cut into a 15 mm-wide strip-shaped piece, and the gas
barrier film was 90° peeled off from the non-stretched polypropylene film using a tensile
tester Tensilon at a rate of 300 mm/minute, and the lamination strength (N/15 mm) was
10 measured.
The evaluation results are shown in Tables 1 to 3.
The lamination strengths of the gas barrier films obtained by the application of
the coating agent to which the epoxy compound (D) or the comparative product of the
epoxy compound (D) had been just added are shown in the “initial lamination strength”
15 row, and the lamination strengths of the gas barrier films obtained by the application of
the coating agent to which the epoxy compound (D) or the comparative product of the
epoxy compound (D) had been added and then stored for one week are shown in the
“lamination strength after 1W storage” row.
[0111]
20 [Table 1]
54
[0112]
[Table 2]
55
[0113]
[Table 3]
56
[0114]
The results of Tables 1 to 3 show that, in the gas barrier films of Examples 1 to
15, the coating film formed of the coating agent including the aqueous polyurethane resin
(A) containing the polyurethane resin having acid groups and the polyamine 5 compound,
the water-soluble polymer (B), the inorganic layered mineral (C), and the epoxy
compound (D) as the principal components was laminated, and thus the oxygen barrier
property in an atmosphere of 20°C and 80%RH and the lamination strength were both
excellent. In addition, even after one-week storage from the addition of the epoxy
10 compound (D), the oxygen barrier property and the lamination strength were maintained.
From these results, it could be confirmed that the usable times of the coating agents of
Examples 1 to 15 were long.
57
From the comparison between Examples 1 and 13 to 15 in which the
compositions of the coating agents were identical to each other except for the types of the
epoxy compound (D), it could be confirmed that, in a case in which the water solubility
ratio of the epoxy compound (D) was 50 mass% or more, superior oxygen barrier
properties could be obtained compared with a case in which the water solubility 5 ratio was
less than 50 mass%.
Among them, particularly, in the gas barrier films of Examples 1 to 8 and 12 in
which the polyvinyl alcohol was used as the water-soluble polymer (B), the compound
having a water solubility ratio of 50 mass% or more was used as the epoxy compound
10 (D), and the mass ratios of the aqueous polyurethane resin (A) to the water-soluble
polymer (B) in the solid content was in a range of 85/15 to 10/90, the oxygen barrier
property after one-week storage from the addition of the epoxy compound (D) were 60
cm3/(m2×day×MPa) or less, and the lamination strengths were 1.3 N/15 mm or more,
which are favorable values.
15 [0115]
On the other hand, in Comparative Example 1 in which the isocyanate-based
curing agent was used instead of the epoxy compound (D) for the coating agent, the
oxygen barrier property and the lamination strength after one-week storage from the
addition of the curing agent were significantly degraded compared with the initial values.
20 In Comparative Examples 2 to 5 in which the coating agents lacking any of the
aqueous polyurethane resin (A) containing the polyurethane resin having acid groups and
the polyamine compound, the water-soluble polymer (B), the inorganic layered mineral
(C), and the epoxy compound (D) were used, any of the oxygen barrier properties and the
lamination strengths were insufficient.
25 [0116]
58

First, the aqueous polyurethane resin (A) and the water-soluble polymer (B)
were blended with each other according to the types and the compounding ratio (mass%)
shown in Tables 4 to 6, next, the inorganic layered mineral (C) was added thereto, and,
after that, the mixture was diluted with ion exchange water and isopropanol 5 so that the
content of isopropanol was 10 mass% of the entire aqueous medium and the
concentration of the solid contents was 8.2 mass%. To the obtained diluted substance,
the silane coupling agent (E) was added according to the types and the compounding
ratio (mass%) shown in Tables 4 to 6, thereby preparing coating agents of Examples 16
10 to 29. Here, the compounding ratio refer to the proportions of the respective
components in the entire solid content in terms of the solid content, which will also be
the case below.
[0117]
Gas barrier films were obtained in the following order using the coating agents
15 of Examples 16 to 29 which had been just prepared (immediately after the addition of the
silane coupling agent (E)).
The coating agent was applied onto a corona-treated surface of a biaxial
stretched polypropylene film (trade name: U-1, thickness: 20 mm, manufactured by
Mitsui Chemicals Tohcello. Inc.) which was a base film using a gravure printer and was
20 dried so as to form a coating film, thereby obtaining a gas barrier film.
The thicknesses of the formed coating films were confirmed and measured using
an electronic microscope and were found to be all 0.6 mm.
[0118]
After the preparation, the coating agents of Examples 16 to 29 were stored at
25 23°C for one week. Coating films were formed on a corona-treated surface of a base
59
film in the same manner as described above using the coating agents that had been stored
for one week, thereby obtaining gas barrier films.
[0119]

First, the aqueous polyurethane resin (A) and the water-5 soluble polymer (B)
were blended with each other according to the types and the compounding ratio (mass%)
shown in Table 6, next, the inorganic layered mineral (C) was added thereto, and, after
that, the mixture was diluted with ion exchange water and isopropanol so that the content
of isopropanol was 10 mass% of the entire aqueous medium and the concentration of the
10 solid contents was 8.2 mass%. To the obtained diluted substance, the silane coupling
agent (E) or the comparative product of the silane coupling agent (E) was added
according to the types and the compounding ratio (mass%) shown in Table 6, thereby
preparing coating agents of Comparative Examples 6 to 10.
[0120]
15 Gas barrier films were obtained in the following order using the coating agents
of Comparative Examples 6 to 10 which had been just prepared (immediately after the
addition of the silane coupling agent (E) or the comparative product of the silane
coupling agent (E)).
The coating agent was applied onto a corona-treated surface of a biaxial
20 stretched polypropylene film (trade name: U-1, thickness: 20 mm, manufactured by
Mitsui Chemicals Tohcello. Inc.) which was a base film using a gravure printer and was
dried so as to form a coating film, thereby obtaining a gas barrier film.
The thicknesses of the formed coating films were confirmed and measured using
an electronic microscope and were found to be all 0.6 mm.
25 [0121]
60
After the preparation, the coating agents of Comparative Examples 6 to 10 were
stored at 23°C for one week. Coating films were formed on a corona-treated surface of
a base film in the same manner as described above using the coating agents that had been
stored for one week, thereby obtaining gas barrier films.
5 [0122]

(1) Oxygen gas barrier property
For the gas barrier films of Examples 16 to 29 and Comparative Examples 6 to
10, the oxygen permeation rate (cm3/(m2×day×MPa)) in an atmosphere of 20°C and
10 80%RH was measured using an oxygen permeation rate measurement instrument (trade
name: OXTRAN-2/20, manufactured by MOCON Inc.).
The evaluation results are shown in Tables 4 to 6. The oxygen permeation
rates of the gas barrier films obtained by the application of the coating agent to which the
silane coupling agent (E) or the comparative product of the silane coupling agent (E) had
15 been just added are shown in the “initial oxygen permeation rate” row, and the oxygen
permeation rates of the gas barrier films obtained by the application of the coating agent
to which silane coupling agent (E) or the comparative product of the silane coupling
agent (E) had been added and then stored for one week are shown in the “oxygen
permeation rate after 1W storage” row.
20 [0123]
(2) Lamination strength
A 30 mm-thick non-stretched polypropylene film (trade name: CPP GLC,
manufactured by Mitsui Chemicals Tohcello. Inc.) was laminated on a coated surface
side (coating film side) of the gas barrier film obtained in each of Examples 16 to 29 and
25 Comparative Examples 6 to 10 through a polyester urethane-based adhesive (trade name:
61
TAKELAC A-969, TAKENATE A-5, manufactured by Mitsui Chemicals, Inc.) by a dry
lamination process and was cured at 50°C for 48 hours, thereby obtaining a laminate
film.
The laminate film was cut into a 15 mm-wide strip-shaped piece, and the gas
barrier film was 90° peeled off from the non-stretched polypropylene film 5 using a tensile
tester Tensilon at a rate of 300 mm/minute, and the lamination strength (N/15 mm) was
measured.
The evaluation results are shown in Tables 4 to 6. The lamination strengths of
the gas barrier films obtained by the application of the coating agent to which the silane
10 coupling agent (E) or the comparative product of the silane coupling agent (E) had been
just added are shown in the “initial lamination strength” row, and the lamination
strengths of the gas barrier films obtained by the application of the coating agent to
which the silane coupling agent (E) or the comparative product of the silane coupling
agent (E) had been added and then stored for one week are shown in the “lamination
15 strength after 1W storage” row.
[0124]
[Table 4]
62
[0125]
[Table 5]
63
[0126]
[Table 6]
64
[0127]
The results of Tables 4 to 6 show that, in the gas barrier films of Examples 16 to
29, the coating film formed of the coating agent including the aqueous polyurethane resin
(A) containing the polyurethane resin having acid groups and the polyamine 5 compound,
the water-soluble polymer (B), the inorganic layered mineral (C), and the silane coupling
agent (E) as the principal components was laminated, and thus the oxygen barrier
property in an atmosphere of 20°C and 80%RH and the lamination strength were both
excellent. In addition, even after one-week storage from the addition of the silane
10 coupling agent (E), the oxygen barrier property and the lamination strength were
maintained. From these results, it could be confirmed that the usable times of the
coating agents of Examples 16 to 29 were long.
65
Particularly, in the gas barrier films of Examples 16 to 23 in which the polyvinyl
alcohol was used as the water-soluble polymer (B), the water-swellable synthetic mica
was used as the inorganic layered mineral (C), the silane coupling agent including epoxy
groups was used as the silane coupling agent (E), and the mass ratios of the aqueous
polyurethane resin (A) to the water-soluble polymer (B) in the solid 5 content was in a
range of 85/15 to 10/90, the oxygen barrier property after one-week storage from the
addition of the silane coupling agent was 80 cm3/(m2×day×MPa) or less, and the
lamination strengths were 1.5 N/15 mm or more, which are favorable values.
From the comparison between Examples 17, 28, and 29 in which the
10 compositions of the coating agents were identical to each other except for the types of the
silane coupling agent (E), it could be confirmed that, in a case in which the silane
coupling agent including epoxy groups was used as the silane coupling agent (E),
superior lamination strengths could be obtained compared with a case in which other
silane coupling agents were used.
15 [0128]
On the other hand, in Comparative Example 6 in which the isocyanate-based
curing agent was used instead of the silane coupling agent (E) for the coating agent, the
oxygen barrier property and the lamination strength after one-week storage from the
addition of the curing agent were significantly degraded compared with the initial values.
20 In Comparative Examples 7 to 10 in which the coating agents lacking any of the
aqueous polyurethane resin (A) containing the polyurethane resin having acid groups and
the polyamine compound, the water-soluble polymer (B), the inorganic layered mineral
(C), and the silane coupling agent (E) were used, any of the oxygen barrier properties and
the lamination strengths were insufficient.
25 Industrial Applicability
66
[0129]
The coating agent of the present invention has a long usable time and is thus
capable of providing gas barrier films having favorable performance stability in the case
of being laminated as coating films.
In addition, the gas barrier film of the present invention exhibits 5 an excellent gas
barrier property even in high-humidity atmospheres and, additionally, has sufficient
adhesion strength of coating film cohesion strength as packing materials.
Therefore, when the gas barrier film according to the present embodiment is
used as packing materials, it is possible to enhance the quality-maintaining property of
10 contents.

CLAIMS
1. A coating agent, comprising, as principal components:
an aqueous polyurethane resin (A) including a polyurethane resin having an acid
group and a polyamine 5 compound;
a water-soluble polymer (B);
an inorganic layered mineral (C); and
a compound (D) having an epoxy group.
10 2. The coating agent according to Claim 1,
wherein a mass ratio of the aqueous polyurethane resin (A) to the water-soluble
polymer (B) in a solid content is 85/15 to 10/90.
3. The coating agent according to Claim 1 or 2,
15 wherein the water-soluble polymer (B) is polyvinyl alcohol.
4. The coating agent according to any one of Claims 1 to 3,
wherein the compound (D) having an epoxy group does not have an isocyanate
group.
20
5. The coating agent according to any one of Claims 1 to 4,
wherein a water solubility ratio of the compound (D) having an epoxy group at
25°C is 50 mass% or more.
25 6. A gas barrier film, comprising:
68
a base film formed of a plastic material; and
a coating film which is laminated on at least one surface of the base film, the
coating film being formed of the coating agent according to any one of Claims 1 to 5.
7. A coating agent, comprising, as principal 5 components:
an aqueous polyurethane resin (A) including a polyurethane resin having an acid
group and a polyamine compound;
a water-soluble polymer (B);
an inorganic layered mineral (C); and
10 a silane coupling agent (E).
8. The coating agent according to Claim 7,
wherein a mass ratio of the aqueous polyurethane resin (A) to the water-soluble
polymer (B) in a solid content is 85/15 to 10/90.
15
9. The coating agent according to Claim 7 or 8,
wherein the water-soluble polymer (B) is polyvinyl alcohol.
10. The coating agent according to any one of Claims 7 to 9,
20 wherein the inorganic layered mineral (C) is water-swellable synthetic mica.
11. The coating agent according to any one of Claims 7 to 10,
wherein the silane coupling agent (E) does not have an isocyanate group.
25 12. The coating agent according to any one of Claims 7 to 11,
69
wherein the silane coupling agent (E) has an epoxy group.
13. A gas barrier film, comprising:
a base film formed of a plastic material; and
a coating film which is laminated on at least one surface of 5 the base film, the
coating film being formed of the coating agent according to any one of Claims 7 to 12.
Dated this the 17th day of October 2017.