JP7381061B2 - Gas barrier laminate - Google Patents

Description

The present invention relates to a gas barrier laminate that exhibits excellent gas barrier properties.

Plastic films such as polyamide films have excellent strength, transparency, and moldability, and are therefore used in a wide range of applications as packaging materials. However, these plastic films have relatively high permeability to gases such as oxygen, so when they are used to package general foods, retort-processed foods, cosmetics, medical supplies, agricultural chemicals, etc., they tend to pass through the film during long-term storage. Gases such as oxygen may cause deterioration of the contents. For this reason, plastic films used in these packaging applications are required to have gas barrier properties, and in packaging foods containing moisture, gas barrier properties are also required under high humidity conditions.

As a method of imparting gas barrier properties to a plastic film, there is a method of laminating a gas barrier layer on the film. As the gas barrier layer, methods using a) a layer composed of a polycarboxylic acid polymer and a metal compound, and b) a vapor-deposited film of an inorganic oxide are known. The above a) is, for example, a gas barrier laminate in which a gas barrier layer (II) is laminated on a plastic base material (I), where the plastic base material (I) is a single-layer film, and the film layer A gas barrier laminate containing 0.1 to 70% by mass of a metal compound, the gas barrier layer (II) containing a polycarboxylic acid, and the polycarboxylic acid being an olefin-maleic acid copolymer. is known (Patent Document 1). As for b), for example, a laminated material using a transparent barrier film having a structure provided with an amorphous thin film of aluminum oxide is known (Patent Document 2).

Patent No. 5843988 Patent No. 3813287

However, the gas barrier laminate described in Patent Document 1 exhibits high barrier properties only after being subjected to hot water treatment at 95° C. for 30 minutes, for example, and requires hot water treatment under relatively severe conditions. ing. That is, in the prior art, it is difficult to obtain sufficient gas barrier properties before the hot water treatment or after the hot water treatment is performed under conditions where the hot water treatment temperature is low and the hot water treatment time is short.

Furthermore, in a gas barrier laminate such as that disclosed in Patent Document 1, no improvement in water vapor barrier properties is observed depending on the stacking of gas barrier layers. For this reason, for example, when a gas barrier laminate as disclosed in Patent Document 1 is manufactured using a polyamide film with low water vapor barrier properties and the contents such as liquid seasonings are stored for a long period of time, the antioxidant effect due to the gas barrier properties is Although this suppresses quality deterioration, the content may become more concentrated due to water evaporation, resulting in changes in taste and aroma during use. Therefore, there is a strong demand for the development of gas barrier films that also have water vapor barrier properties.

In the gas barrier laminate described in Patent Document 2, an amorphous thin film of aluminum oxide is used as the gas barrier layer, but such thin films of inorganic oxides inherently have low flexibility or flexibility. Therefore, it is difficult to follow the bending of the film. As a result, there is always a potential risk that cracks will occur in the thin film due to bending of the film. If cracks occur in the thin film, the barrier performance will deteriorate.

Therefore, the main object of the present invention is to provide a gas barrier laminate that exhibits excellent gas barrier properties and also has water vapor barrier properties even before hot water treatment and after hot water treatment at a relatively low temperature or for a short time. There is a particular thing. Furthermore, another object of the present invention is to provide a gas barrier laminate having excellent bending resistance.

As a result of extensive research in view of the problems of the prior art, the present inventor has discovered that polyvinylidene chloride can be used in a gas barrier laminate that has a metal compound in the film and uses a polycarboxylic acid compound in the gas barrier layer. The inventors have discovered that a film in which a layer containing a polymer is placed at a specific position can achieve the above object, and have completed the present invention.

That is, the present invention relates to the following gas barrier laminate.
1. A laminate comprising at least a polyvinylidene chloride copolymer-containing layer (III), a plastic base material (I), and a gas barrier layer (II),
(1) The plastic base material (I) contains a resin component and a metal compound, and the content of the metal compound is 0.1 to 20% by mass,
(2) The gas barrier layer (II) contains polycarboxylic acid and/or its anhydride, and is laminated on one surface of the plastic base material (I),
(3) The polyvinylidene chloride copolymer-containing layer (III) is laminated on the other surface of the plastic base material (I) on which the gas barrier layer (II) is laminated,
(4) In the oxygen permeability and water vapor permeability of the laminate,
(4-1) The oxygen permeability is 100 ml/( ^m2・day・MPa) or less at a temperature of 20°C and a relative humidity of 90% atmosphere,
(4-2) A gas barrier laminate having a water vapor permeability of 30 g/(m ² ·day) or less at a temperature of 40° C. and a relative humidity of 90%.
2. 2. The gas barrier laminate according to item 1, wherein the plastic substrate (I) includes a polyamide film.
3. 3. The gas barrier laminate according to item 1 or 2, wherein the gas barrier layer (II) further contains polyalcohol.
4. (A) Oxygen permeability and water vapor permeability after subjecting the laminate to hot water treatment at a temperature of 80°C for 30 minutes, (A1) Oxygen permeability at a temperature of 20°C and an atmosphere of 90% relative humidity is 50 ml/ ( ^m2・day・MPa) or less, and (A2) the water vapor permeability at a temperature of 40° C. and a relative humidity of 90% atmosphere is 30 g/( ^m2・day) or less,
(B) Oxygen permeability and water vapor permeability after subjecting the laminate to hot water treatment at a temperature of 120°C for 30 minutes, (B1) Oxygen permeability at a temperature of 20°C and an atmosphere of 90% relative humidity is 50 ml/ (m ² ·day · MPa) or less, and (B2) the water vapor permeability is 30 g / (m ² ·day) or less at a temperature of 40 ° C. and a relative humidity of 90% atmosphere.
The gas barrier laminate according to any one of items 1 to 3 above.
5. A laminate comprising at least a polyvinylidene chloride copolymer-containing layer (III), a plastic base material (I), and a gas barrier layer (II),
(1) The plastic base material (I) contains a resin component and a metal compound, and the content of the metal compound is 0.1 to 20% by mass,
(2) The gas barrier layer (II) contains polycarboxylic acid and/or its anhydride, and is laminated on one surface of the plastic base material (I),
(3) The polyvinylidene chloride copolymer-containing layer (III) is laminated on the other surface of the plastic base material (I) on which the gas barrier layer (II) is laminated,
(4) In the oxygen permeability and water vapor permeability of the laminate,
(4-1) The oxygen permeability is 50 ml/(m ² ·day · MPa) or less at a temperature of 20°C and a relative humidity of 90% atmosphere,
(4-2) A gas barrier laminate having a water vapor permeability of 30 g/(m ² ·day) or less at a temperature of 40° C. and a relative humidity of 90%.
6. A packaging material comprising the gas barrier laminate according to any one of items 1 to 5 above.
7. The packaging material according to item 6, which is used to seal contents.
8. At least a) polyvinylidene chloride copolymer-containing layer (III), b) a plastic base material (I) containing a resin component and a metal compound, and containing the metal compound in a content of 0.1 to 20% by mass, and c ) A method for producing a gas barrier laminate sequentially comprising a gas barrier layer (II), the method comprising:
(1) A step of applying a coating liquid for forming a gas barrier layer (II) containing a polycarboxylic acid and/or its anhydride on one surface of the plastic substrate (I),
(2) a step of applying a coating liquid for forming a polyvinylidene chloride copolymer-containing layer (III) on the other surface of the plastic base material (I);
(3) After the steps (1) and (2) above, a method for producing a gas barrier laminate, which comprises the step of stretching the laminate on which the coating film of both coating liquids has been formed.
9. A method for manufacturing the gas barrier laminate according to item 4, comprising:
A laminate including at least a polyvinylidene chloride copolymer-containing layer (III), a plastic base material (I), and a gas barrier layer (II) in this order,
(1) The plastic base material (I) contains a resin component and a metal compound, and the content of the metal compound is 0.1 to 20% by mass,
(2) The gas barrier layer (II) contains polycarboxylic acid and/or its anhydride, and is laminated on one surface of the plastic base material (I),
(3) The polyvinylidene chloride copolymer-containing layer (III) is laminated on the other surface of the plastic base material (I) on which the gas barrier layer (II) is laminated,
(4) In the oxygen permeability and water vapor permeability of the laminate,
(4-1) The oxygen permeability is 100 ml/( ^m2・day・MPa) or less at a temperature of 20°C and a relative humidity of 90% atmosphere,
(4-2) A gas barrier laminate characterized by including a step of hot water treatment of the laminate, which has a water vapor permeability of 30 g/(m ² ·day) or less at a temperature of 40°C and a relative humidity of 90%. How the body is manufactured.
10. The method for producing a gas barrier laminate according to item 8, further comprising the step of (4) subjecting the stretched laminate to hot water treatment.

According to the present invention, it has both gas barrier properties (especially oxygen barrier properties) and water vapor barrier properties, and furthermore, by performing hot water treatment at a relatively low temperature or for a short time, even better gas barrier properties (especially oxygen barrier properties) can be achieved. It is possible to provide a gas barrier laminate that exhibits both excellent water vapor barrier properties and good water vapor barrier properties. Furthermore, the present invention can also provide a gas barrier laminate that also has excellent bending resistance.

In particular, in the present invention, a gas barrier layer (II) containing polycarboxylic acids is laminated on one side of a plastic base material (I) containing 0.1 to 20% by mass of a metal compound, and a polycarboxylic acid-containing gas barrier layer (II) is laminated on the other side of the plastic base material (I) containing 0.1 to 20% by mass of a metal compound. Also referred to as a vinylidene chloride copolymer-containing layer (hereinafter referred to as "PVDC layer"). ) (III) can reduce the amount of metal compounds eluted from the plastic base material (I) into water during hydrothermal treatment, and improve the reactivity between the gas barrier layer (II) and metal compounds. It becomes possible to do so. As a result, sufficient crosslinking reaction between the gas barrier layer (II) and the metal compound can proceed even under relatively mild hydrothermal conditions, resulting in stable and excellent results even after relatively low-temperature or short-term hydrothermal treatment. It becomes possible to develop gas barrier properties. In other words, excellent gas barrier properties can be obtained by reacting a sufficient amount of the metal compound with the gas barrier layer (II) without performing hot water treatment at high temperatures and for a long time as in the prior art.

At the same time, especially by laminating the PVDC layer (III), the film has not only excellent gas barrier properties but also water vapor barrier properties. Therefore, it can also be suitably used for applications requiring water vapor barrier properties.

Furthermore, the present invention does not need to rely on an inorganic oxide (or metal) thin film as a barrier layer, and therefore can exhibit high bending resistance. That is, the gas barrier laminate of the present invention can maintain high gas barrier properties even when bent. As a result, it becomes possible to provide packaging materials etc. with excellent durability.

The gas barrier laminate of the present invention has good gas barrier properties and water vapor barrier properties, and exhibits even better gas barrier properties when subjected to hot water treatment at a relatively low temperature or for a short time. Therefore, it can be used in a wide range of applications, such as packaging materials for foods, medicines, etc. that require hot water treatment. It is particularly suitable for packaging products that are easily altered or deteriorated by high-temperature or long-term hot water treatment, or products whose quality is affected by changes in moisture content. Furthermore, since the gas barrier properties exhibited by the gas barrier laminate of the present invention are effective even under high humidity, it can be suitably used as a packaging material for long-term storage in relatively harsh environments. can.

FIG. 1 is a schematic diagram showing the basic layer structure of the gas barrier laminate of the present invention.

1. Gas Barrier Laminate The gas barrier laminate of the present invention (the laminate of the present invention) is a laminate that includes at least a polyvinylidene chloride copolymer-containing layer (III), a plastic base material (I), and a gas barrier layer (II) in this order. There it is,
(1) The plastic base material (I) contains a resin component and a metal compound, and the content of the metal compound is 0.1 to 20% by mass,
(2) The gas barrier layer (II) contains polycarboxylic acid and/or its anhydride, and is laminated on one surface of the plastic base material (I),
(3) The polyvinylidene chloride copolymer-containing layer (III) is laminated on the other surface of the plastic base material (I) on which the gas barrier layer (II) is laminated,
(4) In the oxygen permeability and water vapor permeability of the laminate,
(4-1) The oxygen permeability is 100 ml/( ^m2・day・MPa) or less at a temperature of 20°C and a relative humidity of 90% atmosphere,
(4-2) It is characterized by a water vapor permeability of 30 g/(m ² ·day) or less in an atmosphere at a temperature of 40° C. and a relative humidity of 90%.

The basic structure of the laminate of the present invention is shown in FIG. In the laminate 10 of the present invention, a gas barrier layer 12 is laminated on one side of a plastic base material 11, and a polyvinylidene chloride copolymer-containing layer 13 is laminated on the other side. As described above, the laminate 10 of the present invention has a basic configuration of the PVDC layer 13/plastic base material 11/gas barrier layer 12. These layers may be laminated so as to be in direct contact with each other, or may be laminated with other layers (for example, an adhesive layer, etc.) interposed therebetween as necessary. In particular, in the present invention, it is preferable that the gas barrier layer 12 is laminated so as to be in direct contact with the plastic base material 11.

The laminate of the present invention has a basic structure of PVDC layer 13/plastic base material 11/gas barrier layer 12, and other layers may be laminated on the surface of PVDC layer 13 and/or gas barrier layer 12 as necessary. . Examples of other layers include a printing layer, an adhesive layer, a heat seal layer, a metal foil layer, and the like. Each layer constituting the laminate of the present invention will be explained below.

(1) Plastic base material (I)
The plastic base material (I) is characterized in that it contains a resin component (hereinafter also referred to as "resin component A") and a metal compound, and the content of the metal compound is 0.1 to 20% by mass.

As the resin component A, either a thermoplastic resin or a thermosetting resin can be used, but a thermoplastic resin can be particularly preferably used in the present invention. Thermoplastic resins are not particularly limited, and include, for example, a) polyolefin resins such as polyethylene and polypropylene, b) polyamide resins such as nylon 6, nylon 66, nylon 46, nylon MXD6, and nylon 9T, and c) polyethylene terephthalate and polyethylene isoplastic resins. d) Other resins (vinyl chloride resin, polystyrene resin, polycarbonate resin, arylate resin, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, etc.), e) mixtures of a) to d) above, and the like.

In the present invention, polyamide resins are preferred among thermoplastic resins, and nylon 6 is particularly preferred. Since the polyamide resin has a hydrophilic amide group, when the laminate of the present invention is subjected to moist heat treatment or hot water treatment, metal ions consisting of the metal compound in the plastic base material (I) quickly form the gas barrier layer (II). ), which reacts with polycarboxylic acid and undergoes ionic crosslinking, which can further strengthen the gas barrier properties.In addition, when the laminate of the present invention is used as a packaging material (particularly a packaging bag), it has superior puncture strength, Impact resistance etc. can be obtained. Polyamide resins can be used alone or in a mixture of two or more.

The content of resin component A in the plastic base material (I) can be set appropriately depending on the type of resin component used, but it is usually about 70 to 100% by mass, and particularly preferably 80 to 99% by mass. preferable. Further, when a polyamide resin is used as the resin component A, the content of the polyamide resin in the resin component A is generally 80 to 100% by mass, and preferably 90 to 99% by mass.

The metal constituting the metal compound is not particularly limited, and includes, for example, monovalent metals such as lithium, sodium, potassium, rubidium, and cesium, magnesium, calcium, zirconium, zinc, copper, cobalt, iron, nickel, and aluminum. Examples include metals having a valence of two or more. The type of metal is not limited to one type, and may be two or more types.

Among these, metals with a high ionization tendency are preferred because they easily react with the polycarboxylic acids constituting the gas barrier layer (II), and divalent metals are preferred from the viewpoint of gas barrier properties. Therefore, for example, it is preferably at least one of lithium, sodium, potassium, magnesium, calcium, and zinc, and particularly preferably at least one of magnesium, calcium, and zinc.

In the present invention, the metal compound is not particularly limited as long as it is a compound containing the above metal. For example, oxides, hydroxides, halides, inorganic acid salts (carbonates, hydrogen carbonates, phosphates, sulfates, etc.), organic acid salts (carboxylate (acetates, formates, stearates, etc.) citrate, malate, maleate), sulfonate, etc.). In the present invention, oxides or carbonates are particularly preferred in terms of exhibiting excellent gas barrier properties.

Among the above metal compounds, preferred examples include lithium carbonate, sodium hydrogen carbonate, magnesium oxide, magnesium carbonate, magnesium hydroxide, magnesium acetate, calcium oxide, calcium carbonate, calcium hydroxide, calcium chloride, calcium phosphate, calcium sulfate, and acetic acid. At least one of calcium, zinc acetate, zinc oxide, zinc carbonate, etc. can be mentioned.

From the viewpoint of gas barrier properties, divalent metal compounds are preferred, and it is particularly preferred to use at least one of a magnesium compound, a calcium compound, and a zinc compound. Therefore, for example, at least one of magnesium oxide, magnesium carbonate, magnesium hydroxide, magnesium acetate, calcium oxide, calcium carbonate, calcium acetate, zinc oxide, and zinc acetate can be suitably used. Moreover, from the viewpoint of transparency of the plastic base material (I), at least one of monovalent metal compounds and divalent metal compounds is preferable, and at least one of alkali metal compounds and alkaline earth metal compounds is more preferable. Therefore, for example, at least one of lithium carbonate, sodium hydrogen carbonate, magnesium oxide, magnesium carbonate, and magnesium hydroxide can be suitably used.

Although the form (property) of the metal compound is not limited, it is usually preferable that it be in the form of a powder. That is, it is preferable to adopt a structure in which particles of a metal compound are dispersed in the plastic base material (I).

The average particle size when using a powdered metal compound is not particularly limited, but it is usually about 0.001 to 10 μm, preferably 0.005 to 5 μm, and more preferably 0.01 to 2 μm. It is more preferable that the thickness is 0.05 to 1 μm, and the most preferable is 0.05 to 1 μm. From the standpoint of being able to reduce the haze of the plastic base material (I), it is preferable that the average particle size is small. On the other hand, when the average particle size is less than 0.001 μm, the surface area is large, making it easy to aggregate, and when coarse aggregates are scattered in the film, the mechanical properties of the base material may be deteriorated. On the other hand, a plastic substrate (I) containing a metal compound with an average particle size exceeding 10.0 μm tends to break more frequently during film formation, resulting in lower productivity.

The metal compound (particles) can be subjected to surface treatment (surface film forming treatment) if necessary. Thereby, dispersibility, weather resistance, wettability with thermoplastic resin, heat resistance, transparency, etc. can be improved. For the surface treatment, a known inorganic treatment or organic treatment can be employed. Examples of the inorganic treatment include treatment of forming alumina, silica, titania, zirconia, tin oxide, antimony oxide, zinc oxide, etc. on the surface of the metal compound particles. As an organic treatment, for example, a fatty acid compound, a polyol compound such as pentaerythritol, trimethylolpropane, an amine compound such as triethanolamine or trimethylolamine, a silicone compound such as a silicone resin, or an alkylchlorosilane is applied to the surface of the metal compound particle. Examples include processing to form.

The content of the metal compound in the plastic base material (I) is usually 0.1 to 20% by mass, particularly preferably 0.1 to 18% by mass, and more preferably 0.2 to 15% by mass. The content is more preferably 0.3 to 10% by mass, and most preferably 0.3 to 10% by mass. Further, from the viewpoint of haze, the content is preferably 5% by mass or less. When the content of the metal compound in the plastic base material (I) is 0.1 to 20% by mass, excellent gas barrier properties and mechanical properties can be obtained. On the other hand, if the content of the metal compound in the plastic base material (I) is less than 0.1% by mass, the ionic crosslinked structure formed by reaction with the polycarboxylic acids of the gas barrier layer (II) will decrease. , the desired gas barrier properties cannot be obtained. On the other hand, a plastic base material (I) having a content exceeding 20% by mass will break more frequently during stretching during film formation, and productivity will tend to decrease, and mechanical properties will also tend to decrease. Note that the content of the metal compound can be calculated based on the measurement results of the metal content measured by a plasma atomic emission spectrometer shown in Test Example 1 described later, for example.

The plastic base material (I) (especially thermoplastic resin) may contain, for example, heat stabilizers, antioxidants, reinforcing agents, pigments, deterioration inhibitors, etc. within the range that does not adversely affect the performance of the plastic base material (I). One or more of various additives such as weathering agents, flame retardants, plasticizers, preservatives, ultraviolet absorbers, antistatic agents, and antiblocking agents may be added as necessary. Furthermore, inorganic or organic lubricants other than metal compounds may be added for the purpose of improving the slip properties of the plastic base material (I), for example, silica can be suitably added as a lubricant. In addition, when these additives correspond to metal compounds, the content of the additives is included in the content of the metal compound.

The thickness of the plastic base material (I) is not particularly limited, and can be appropriately selected depending on, for example, the mechanical strength required of the resulting gas barrier laminate. In particular, for reasons such as mechanical strength and ease of handling, the thickness of the plastic base material (I) is usually preferably 5 to 100 μm, particularly preferably 10 to 30 μm. If the thickness of the plastic base material (I) is less than 5 μm, sufficient mechanical strength may not be obtained, and the puncture strength may be reduced.

(2) Gas barrier layer (II)
The gas barrier layer (II) contains polycarboxylic acid and/or its anhydride (in the present invention, both are collectively referred to as "polycarboxylic acids"), and contains one of the plastic base materials (I). layered on the surface.

The polycarboxylic acids contained in the gas barrier layer (II) play a role in developing gas barrier properties, particularly by reacting with the metal compound in the plastic base material (I).

Polycarboxylic acids are compounds having two or more carboxyl groups in the molecule or anhydrides thereof. In the case of anhydride, all the carboxyl groups may have an anhydride structure [-CO-O-CO-], or some of the carboxyl groups may have an anhydride structure. Furthermore, the polycarboxylic acids may be in the form of either a monomer or a polymer.

Specific examples of polycarboxylic acids include a) monomer compounds such as 1,2,3,4-butanetetracarboxylic acid, b) polyacrylic acid, polymethacrylic acid, acrylic acid-methacrylic acid copolymers, ( Homopolymers or copolymers of (meth)acrylic acid such as meth)acrylic acid-maleic acid copolymers, acrylic acid-maleic anhydride copolymers, d) polymaleic acid, ethylene-maleic acid copolymers, ethylene- Examples include olefin-maleic acid copolymers such as maleic anhydride copolymers, e) polysaccharides having carboxyl groups in side chains such as alginic acid, and f) polyamides or polyesters having carboxyl groups. These polycarboxylic acids can be used alone or in combination of two or more. Note that the above-mentioned "(meth)acrylic acid" is a general term for acrylic acid and methacrylic acid (the same applies hereinafter).

When the polycarboxylic acid is a polymer, its weight average molecular weight is not particularly limited, but is generally preferably from 1,000 to 1,000,000, particularly from 10,000 to 150,000. is more preferable, and among these, 15,000 to 110,000 is most preferable. If the weight average molecular weight of the polycarboxylic acids is too low, the resulting gas barrier layer (II) may become brittle. On the other hand, if the molecular weight is too high, handling properties will be impaired, and in some cases, it may aggregate in the coating liquid for forming the gas barrier layer (II), which will be described later, and the gas barrier properties of the resulting gas barrier layer (II) may be impaired. There is.

In the present invention, it is preferable to use an olefin-maleic acid copolymer as the polycarboxylic acid, and it is particularly preferable to use an ethylene-maleic acid copolymer (hereinafter also referred to as "EMA"). By using EMA, better gas barrier properties can be obtained. As the EMA itself, known or commercially available ones can be used. Moreover, those obtained by known manufacturing methods can also be used. Therefore, for example, a copolymer obtained by polymerizing maleic anhydride and ethylene by a method such as solution radical polymerization can also be used.

The maleic acid unit in EMA is preferably 5 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, and most preferably 35 mol% or more. . In addition, the maleic acid unit in the olefin-maleic acid copolymer tends to form a maleic anhydride structure in which adjacent carboxyl groups are dehydrated and cyclized in a dry state, and when wet or in an aqueous solution, the maleic acid unit opens to form a maleic acid structure. . Therefore, in the present invention, unless otherwise specified, maleic acid units and maleic anhydride units are collectively referred to as maleic acid units.

In addition, the weight average molecular weight of EMA is not particularly limited, but it may normally be about 1,000 to 1,000,000, preferably 3,000 to 500,000, more preferably 7,000 to 300. ,000, most preferably between 10,000 and 200,000.

The content of polycarboxylic acids in the gas barrier layer (II) is not particularly limited, and can be set appropriately depending on the type of polycarboxylic acids used, but is usually about 40 to 90% by mass, particularly 50 to 80% by mass. It is desirable to set it as %.

In addition to polycarboxylic acids, the gas barrier layer (II) in the laminate of the present invention may contain other components (particularly components that react with polycarboxylic acids to crosslink polycarboxylic acids). For example, the laminate of the present invention preferably contains polyalcohol or the like.

Higher gas barrier properties can be obtained by containing polyalcohol in the gas barrier layer (II). In other words, in addition to reacting with the metal compound in the plastic base material (I), the polycarboxylic acids in the gas barrier layer (II) can undergo an ester crosslinking reaction with the hydroxyl groups in the polyalcohol, thereby further improving gas barrier properties. can be improved.

Polyalcohol is a compound having two or more hydroxyl groups in the molecule, and as long as it is a compound, it may be either a low molecular compound or a high molecular compound (polymer). Examples include sugar alcohols such as glycerin and pentaerythritol, monosaccharides such as glucose, disaccharides such as maltose, and oligosaccharides such as galactooligosaccharides. Examples of the polymer compound include polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and polysaccharides such as starch. The above polyalcohols can be used alone or in combination of two or more.

When the polyalcohol is polyvinyl alcohol, ethylene-vinyl alcohol copolymer, etc., the degree of saponification is not limited, but it is usually preferably 95 mol% or more, more preferably 98 mol% or more. preferred. Further, the average degree of polymerization is preferably 50 to 2,000, more preferably 200 to 1,000. This makes it possible to obtain better gas barrier properties.

The content of polyalcohol is not limited, but especially the OH group contained in polyalcohol and the COOH group contained in polycarboxylic acids (in the case of anhydride, two [-CO-O-CO-] The molar ratio (OH group/COOH group) of (converted to COOH group) may be set to be 0.01 to 20, but it is particularly preferably set to 0.01 to 10. , more preferably from 0.02 to 5, and most preferably from 0.04 to 2. This makes it possible to obtain better gas barrier properties.

The gas barrier layer (II) may contain, for example, a heat stabilizer, an antioxidant, a reinforcing material, a pigment, an anti-deterioration agent, a weathering agent, as long as it does not significantly impair gas barrier properties, adhesion to the plastic substrate (I), etc. , a flame retardant, a plasticizer, a mold release agent, a lubricant, a preservative, an antifoaming agent, a wetting agent, a viscosity modifier, etc. may be added as necessary. In particular, examples of heat stabilizers, antioxidants, deterioration inhibitors, etc. include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, etc. May be used. Examples of reinforcing materials include clay, talc, wollastonite, silica, alumina, calcium silicate, sodium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, zeolite, montmorillonite, hydrotalcite, and fluorinated mica. , metal fibers, metal whiskers, ceramic whiskers, potassium titanate whiskers, boron nitride, graphite, glass fibers, carbon fibers, fullerenes (C60, C70, etc.), carbon nanotubes, and the like.

The thickness of the gas barrier layer (II) is not particularly limited, but is preferably 0.05 μm or more in order to more reliably obtain gas barrier properties of the gas barrier laminate. Although the upper limit of the thickness is not particularly limited, it is preferably about 5 μm from the viewpoint of economy and the like.

(3) Polyvinylidene chloride copolymer-containing layer (III)
The PVDC layer (III) is laminated on the other surface of the plastic base material (I) on which the gas barrier layer (II) is laminated, as shown in FIG.

By forming the PVDC layer (III), it is possible to effectively suppress the metal compound in the plastic base material (I) from leaching to the outside of the gas barrier laminate during hot water treatment. As a result, the reactivity between the metal compound and the gas barrier layer (II) increases, and excellent gas barrier properties can be stably obtained even during relatively low-temperature or short-time hot water treatment. Furthermore, by imparting the gas barrier properties and water vapor barrier properties of the PVDC layer (III) to the laminate, good barrier properties can be obtained even without hot water treatment.

The polyvinylidene chloride copolymer contained in the PVDC layer (III) is a copolymer of 1,1-dichloroethylene (vinylidene chloride monomer) and a monomer copolymerizable with it, and contains 1,1-dichloroethylene. Those containing 50 to 99% by mass can be suitably used. 1,1-dichloroethylene (vinylidene chloride monomer) and monomers copolymerizable with it are not particularly limited, and include, for example, vinyl chloride, acrylonitrile, acrylic esters, methacrylic esters, and the like.

Known or commercially available polyvinylidene chloride copolymers can also be used. Moreover, those obtained by known manufacturing methods can also be used.

For example, by using a raw material containing a predetermined proportion of 1,1-dichloroethylene (vinylidene chloride monomer) and a monomer copolymerizable with it, and polymerizing it by an emulsion polymerization method, the above-mentioned copolymer is produced as a latex dispersed in a medium. Polymers can be obtained. The emulsion polymerization method can be carried out according to known conditions. The latex thus obtained or a liquid whose concentration has been adjusted can be used as a coating liquid for forming the PVDC layer (III). Furthermore, a film obtained by forming the coating solution described above can also be used as a film for the PVDC layer (III).

The molecular weight (weight average molecular weight) of the polyvinylidene chloride copolymer is not particularly limited, but is usually about 120,000 to 300,000, preferably 120,000 to 220,000. This makes it possible to form a PVDC layer (III) with better water vapor barrier properties.

The content of the polyvinylidene chloride copolymer in the PVDC layer (III) is not particularly limited, but is usually about 50 to 100% by mass, preferably 70 to 95% by mass. Therefore, the PVDC layer (III) may contain other components within a range that does not impede the effects of the present invention. For example, various additives such as anti-blocking agents, antioxidants, antistatic agents, ultraviolet absorbers, lubricants, and preservatives can be used as necessary.

The thickness of the PVDC layer (III) is not limited, but it is usually preferably about 0.5 to 3.5 μm, more preferably 0.7 to 3.0 μm, among which 1 The most preferable range is .0 to 2.0 μm. If the film thickness is less than 0.5 μm, the effect of suppressing elution of metal compounds, which is the objective of the present invention, may not be sufficiently achieved. On the other hand, if the film thickness exceeds 3.5 μm, the film forming property is reduced and the appearance of the film is likely to be impaired. Furthermore, if the film thickness becomes too high, the film tends to become hard, and pinhole resistance, bending resistance, etc. tend to deteriorate.

(4) Oxygen permeability and water vapor permeability The gas barrier laminate of the present invention has high gas barrier properties and high water vapor barrier properties. Furthermore, the hot water treatment causes a crosslinking reaction by the metal ions of the metal compound contained in the plastic base material (I), and as a result, desired gas barrier properties and water vapor barrier properties can be finally obtained. Here, in the present invention, the above-mentioned "hot water treatment" means treatment with hot water to complete the crosslinking reaction of the metal compound contained in the plastic base material (I) with metal ions, and is usually at 70°C. Although the treatment with hot water is referred to above, it is not limited thereto as long as the oxygen permeability can be particularly reduced.

Regarding the oxygen permeability of the gas barrier laminate of the present invention, the oxygen permeability under an atmosphere of a temperature of 20° C. and a relative humidity of 90% is usually required to be 100 ml/(m ² ·day · MPa) or less, It is preferably 80 ml/(m ² ·day · MPa) or less, and more preferably 50 ml/(m ² ·day · MPa) or less. The lower limit can be, for example, about 30 ml/(m ² ·day · MPa), but is not limited thereto.

In addition, the water vapor permeability of the gas barrier laminate of the present invention is required to be 30 g/(m ² ·day) or less at a temperature of 40° C. and a relative humidity of 90%, particularly 20 g /(m ² ·day) or less, and more preferably 15 g/(m ² ·day) or less. The lower limit can be, for example, about 5 g/(m ² ·day), but is not limited to this.

2. Physical properties of gas barrier laminate The laminate of the present invention is basically provided in the form of a sheet. The total thickness can be set as appropriate depending on the application, etc., and is usually set appropriately within the range of 5 to 50 μm, but preferably 10 to 35 μm.

In addition, since the PVDC layer (III) is particularly formed on the surface of the plastic base material, the laminate of the present invention is particularly suitable for the plastic base (I) when subjected to moist heat treatment or hot water treatment. It is possible to suppress the amount of metal compounds eluted from the metal compound. More specifically, when the laminate of the present invention is subjected to hot water treatment at 120°C for 30 minutes, the amount (reduction amount) of the metal compound eluted from the plastic base material (I) is usually 20% by mass or less. It is preferably at most 15% by mass, more preferably at most 10% by mass. If the amount of the metal compound to be eluted exceeds 20% by mass, the reactivity between the metal compound and the gas barrier layer (II) will decrease, and barrier properties will not be exhibited by low-temperature, short-time hydrothermal treatment.

The laminate of the present invention has oxygen permeability after hot water treatment at 80°C for 30 minutes and oxygen permeability after hot water treatment at 120°C for 30 minutes in an atmosphere at a temperature of 20°C and relative humidity of 90%. Both degrees are preferably 50 ml/(m ² ·day · MPa) or less, more preferably 30 ml/(m ² ·day · MPa) or less, and 20 ml/(m ² ·day · MPa) or less. Most preferably. Both oxygen permeabilities may be the same or different. Note that the lower limit value of both oxygen permeability can be, for example, usually about 0.01 ml/(m ² ·day · MPa), but is not limited to this. Therefore, for example, the amount can be about 0.5 ml/(m ² ·day · MPa).

The laminate of the present invention has a water vapor permeability after hot water treatment at 80°C for 30 minutes and a water vapor permeability after hot water treatment at 120°C for 30 minutes in an atmosphere at a temperature of 40°C and a relative humidity of 90%. Both degrees are preferably 30 g/(m ² ·day) or less, particularly preferably 20 g/(m ² ·day) or less, and among these, 15 g/(m ² ·day) or less is preferable. Most preferred. Both water vapor permeabilities may be the same or different. Note that the lower limit of both water vapor permeability can be, for example, usually about 1 g/(m ² ·day), but is not limited to this. Therefore, it can be set to about 5 g/(m ² ·day), for example.

Therefore, the present invention also includes a gas barrier laminate having the oxygen permeability and water vapor permeability after hot water treatment as described above. That is, it is a laminate that includes at least a polyvinylidene chloride copolymer-containing layer (III), a plastic base material (I), and a gas barrier layer (II) in this order, wherein (1) the plastic base material (I) contains a resin component and The gas barrier layer (II) contains a metal compound, and the content of the metal compound is 0.1 to 20% by mass; (2) the gas barrier layer (II) contains a polycarboxylic acid and/or an anhydride thereof; The polyvinylidene chloride copolymer-containing layer (III) is laminated on one side of the plastic base material (I), and the (3) polyvinylidene chloride copolymer-containing layer (III) is laminated on the other side of the plastic base material (I) on which the gas barrier layer (II) is laminated. (4) Regarding the oxygen permeability and water vapor permeability of the laminate, (4-1) the oxygen permeability at a temperature of 20°C and an atmosphere of 90% relative humidity is 50 ml/(m ² · (4-2) A gas barrier laminate having a water vapor permeability of 30 g/(m ² ·day) or less under an atmosphere of a temperature of 40° C. and a relative humidity of 90%. Included in the present invention. Such a gas barrier laminate particularly exhibits better oxygen barrier properties than the laminate before hot water treatment.

Although the tensile strength of the laminate of the present invention is not limited, it is particularly preferably 150 MPa or more, and more preferably 180 MPa or more. If the tensile strength is less than 150 MPa, the mechanical strength will not be sufficient and the puncture strength will tend to decrease. Although the tensile elongation is not limited, from the same viewpoint as the tensile strength, it is particularly preferably 60% or more, and more preferably 80% or more.

Regarding the bending resistance of the laminate of the present invention, the rate of increase in oxygen permeability and water vapor permeability after a 500-times repeated bending fatigue test in a 20°C atmosphere is preferably 40% or less, particularly 20% or less. It is more preferable. Specifically, in accordance with ASTM F 392, the permeability after repeated bending 500 times in a Gelbo Tester (manufactured by Tester Sangyo Co., Ltd.) in an atmosphere of 20°C x 65% RH is calculated as the permeability without a bending fatigue test. Evaluated by comparing with.

Regarding the transparency of the laminate of the present invention, the haze is usually preferably 30% or less, particularly preferably 20% or less, and most preferably 10% or less. However, this is not the case as transparency may not be required depending on the application.

3. Production of gas barrier laminate The method for producing the laminate of the present invention is not particularly limited, and examples include a) a method of obtaining a film from a sheet by molding a mixture that may constitute each layer, b) a method of obtaining a film from a sheet by molding a mixture that may constitute each layer; This can be carried out by forming and laminating each layer by either a method of forming a coating film using a coating solution, c) a method of combining the above a) and b), etc., but in the present invention, in particular, the resin component A and an unstretched film containing a metal compound as a precursor of the plastic base material (I), and the precursor or stretched film is coated with a coating liquid for forming a gas barrier layer (II) and a coating liquid for forming a PVDC layer (III). A method of coating and forming without using a primer layer can be suitably employed.

In the present invention, the stretching may be either uniaxial stretching or biaxial stretching, but biaxial stretching is particularly preferred. In the case of biaxial stretching, either sequential biaxial stretching or simultaneous biaxial stretching may be used. For example, an unstretched film coated with both coating solutions and dried is subjected to simultaneous biaxial stretching in the machine direction (MD) and transverse direction (TD) using a tenter-type simultaneous biaxial stretching machine. A gas barrier laminate can be obtained. For example, an unstretched film coated with both coating solutions and dried is stretched in the machine direction (MD), a gas barrier layer (II) and a PVDC layer (III) are formed by the method described above, and then a gas barrier layer (II) and a PVDC layer (III) are formed in the transverse direction (MD). TD), a sequentially biaxially stretched gas barrier laminate can be obtained.

The stretching ratio in the case of stretching is not particularly limited, but in the case of uniaxial stretching, it is preferably 1.5 times or more, and particularly preferably 2 to 6 times. Furthermore, in the case of biaxial stretching, although not particularly limited, it is preferably 1.5 times or more in each direction (MD and TD), and particularly preferably 2 to 4 times. Further, the area magnification is usually preferably 3 times or more, particularly preferably 6 to 20 times, and most preferably 6.5 to 13 times. By setting the stretching ratio within the above range, it becomes possible to obtain a gas barrier laminate having better physical properties.

In the present invention, when biaxial stretching is employed, the following method can be suitably used by either simultaneous biaxial stretching or sequential biaxial stretching.

The first method (in the case of simultaneous biaxial stretching) is a method for producing a gas barrier laminate, which includes (1) forming a gas barrier layer (II) on one side of an unstretched film containing resin component A and a metal compound; Step of applying and drying a coating liquid (gas barrier layer (II) formation step), (2) Applying a coating liquid for forming a PVDC layer (III) on the opposite side of the unstretched film on which the gas barrier layer (II) is laminated. (3) a step of simultaneously biaxially stretching the unstretched film onto which both of the above coating solutions have been applied and dried (stretching step). , the laminate of the present invention can be suitably manufactured.

The second method (in the case of sequential biaxial stretching) is a method for manufacturing a gas barrier laminate, which includes the step of (1) stretching an unstretched film containing resin component A and a metal compound in the machine direction (MD); (first stretching step), (2) Apply and dry a coating liquid for forming a gas barrier layer (II) on one side of the longitudinally stretched film, and apply PVDC to the opposite side on which the gas barrier layer (II) is laminated. Step of applying and drying the coating liquid for layer (III) formation (coating film formation step), (4) Step of stretching the film coated with both coating liquids in the transverse direction (TD) (second stretching step) The laminate of the present invention can be suitably manufactured by a method including:

In particular, in the present invention, it is preferable to employ the first method (simultaneous biaxial stretching). The simultaneous biaxial stretching method can generally provide practical properties such as mechanical properties, optical properties, thermal dimensional stability, pinhole resistance, and bending resistance. On the other hand, in the sequential biaxial stretching method in which horizontal stretching is performed after longitudinal stretching, orientational crystallization of the film progresses during longitudinal stretching and the stretchability of the thermoplastic resin during horizontal stretching decreases, resulting in a reduction in the strength of the metal compound. When the blending amount is large, the frequency of film breakage tends to increase. Therefore, in the present invention, it is preferable to use a simultaneous biaxial stretching method. Therefore, the first method described above will be described below as a representative example of the method for manufacturing the laminate of the present invention.

(1a) Unstretched film The unstretched film used in the gas barrier layer (II) forming step is a precursor of the plastic base material (I), and is formed by forming a mixture containing a resin component (thermoplastic resin) and a metal compound into a sheet. Alternatively, it can be manufactured by molding into a film.

The method for preparing the above mixture is not particularly limited. For example, a) a method of adding a metal compound when synthesizing (polymerizing) a resin component (especially a thermoplastic resin), b) a method of kneading a resin component and a metal compound in an extruder, c) a method of adding a metal compound to a high Examples include a method (masterbatch method) in which a masterbatch is prepared by kneading and blending to a certain concentration, and this is added to a thermoplastic resin to dilute it. In the present invention, the masterbatch method is preferably employed because it is easy to adjust the content of the metal compound and has excellent operability.

The above-mentioned molding method is not particularly limited, and for example, known molding methods such as press molding, extrusion molding, and injection molding can be employed. For example, a mixture containing a resin component (thermoplastic resin) and a metal compound is heated and melted in an extruder, extruded into a film from a T-die, and then rotated by a known casting method such as an air knife casting method or an electrostatic application casting method. An unstretched film can be obtained by cooling and solidifying on a cooling drum. If the unstretched film is oriented, the stretchability may be lowered in a subsequent step, so it is preferable that the unstretched film is substantially amorphous and unoriented.

The types of thermoplastic resins, metal compounds, additives, etc. that can be used, their contents, etc. are the same as those shown in "1. Gas barrier laminate" above.

When polyamide resin is used as the thermoplastic resin, the resulting unstretched film is transferred to a water tank whose temperature is controlled not to exceed 80°C, and subjected to water immersion treatment for usually within 5 minutes, resulting in approximately 0.5 It is preferable to perform a moisture absorption treatment of ~15%.

(1b) Gas barrier layer (II) forming step In the gas barrier layer (II) forming step, a gas barrier layer (II) forming coating liquid is applied and dried on one side of an unstretched film containing a resin component and a metal compound.

The coating liquid for forming the gas barrier layer (II) can be prepared by dissolving or dispersing the components constituting the gas barrier layer (II) in a solvent.

As the solvent, various organic solvents can be used in addition to water. Examples of organic solvents include hydrocarbon solvents such as cyclohexane, n-hexane, and benzene; alcohol solvents such as methanol, ethanol, propanol, isopropyl alcohol, and isobutyl alcohol; ketone solvents such as acetone, ketone, and methyl ethyl ketone; methyl acetate; Examples include ester solvents such as ethyl acetate, isopropyl acetate, isobutyl acetate, and isopentyl acetate, and ether solvents such as ethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, and ethylene glycol monomethyl ether. Among these, at least one of water and a water-soluble organic solvent is preferable, and it is particularly preferable to use water. When water is used, the coating liquid is preferably in the form of an aqueous solution or an aqueous dispersion (that is, an aqueous coating liquid), and particularly contains at least a polycarboxylic acid (or at least one polyalcohol and a polycarboxylic acid). More preferably, it is in the form of an aqueous solution dissolved in water.

Further, when preparing a coating solution for forming the gas barrier layer (II), it is preferable to add an alkali compound in an amount of about 0.1 to 20 equivalent % based on the carboxyl group of the polycarboxylic acid. Polycarboxylic acids become more hydrophilic when the content of carboxyl groups is high, so they can be made into an aqueous solution without adding an alkali compound, but the gas barrier properties obtained can be improved by adding an appropriate amount of an alkali compound. The gas barrier properties of the laminate can be significantly improved. In this case, the alkali compound may be any one as long as it can neutralize the carboxyl group of the polycarboxylic acids, and examples thereof include sodium hydroxide. Further, the amount of the alkali compound added is not limited, but it is preferably set to about 0.1 to 20 mol % based on the carboxyl group of the polycarboxylic acid.

The coating solution for forming the gas barrier layer (II) can be prepared by a known method using, for example, a dissolving pot equipped with a stirrer. For example, a method is preferred in which polycarboxylic acids and polyalcohol are made into separate aqueous solutions and mixed before coating. At this time, if the alkali compound is added to the aqueous solution of polycarboxylic acids, the stability of the aqueous solution can be improved.

The method of applying the coating liquid for forming the gas barrier layer (II) is not particularly limited. For example, an air knife coater, a kiss roll coater, a metal ring bar coater, a gravure roll coater, a reverse roll coater, a dip coater, a die coater, or a combination of any of these can be used. These can be carried out using known or commercially available equipment.

After applying the coating liquid for forming the gas barrier layer (II), it may be dried naturally, but it is preferable to dry it by heating. The method of drying by heating is not particularly limited, and examples include methods of forming a gas barrier layer (II) as a dry film by evaporating moisture and the like by blowing hot air using a dryer or the like, or by irradiating infrared rays.

The drying temperature in the case of heat drying is not particularly limited, but is usually about 50 to 200°C, preferably 80 to 150°C, and more preferably 100 to 120°C. If the drying temperature is too low, it will take a long time to form a dry film and reduce productivity. On the other hand, if the drying temperature is too high, the plastic base material (I), gas barrier layer (II), etc. may become brittle.

In addition, when applying the coating liquid for forming the gas barrier layer (II), irradiation treatment with high-energy rays such as ultraviolet rays, X-rays, and electron beams may be performed as necessary before and after drying. . In such a case, a component that crosslinks or polymerizes when irradiated with high-energy rays may be appropriately blended.

(2) PVDC layer (III) formation process
In the PVDC layer (III) forming step, a coating solution for forming a PVDC layer (III) is applied to the other surface of the unstretched film and dried.

The coating liquid for forming the PVDC layer (III) can be prepared by dissolving or dispersing the components constituting the PVDC layer (III) in a solvent.

As the solvent, various organic solvents can be used in addition to water. Examples of organic solvents include hydrocarbon solvents such as cyclohexane, n-hexane, and benzene; alcohol solvents such as methanol, ethanol, propanol, isopropyl alcohol, and isobutyl alcohol; ketone solvents such as acetone, ketone, and methyl ethyl ketone; methyl acetate; Examples include ester solvents such as ethyl acetate, isopropyl acetate, isobutyl acetate, and isopentyl acetate, and ether solvents such as ethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, and ethylene glycol monomethyl ether. Among these, at least one of water and a water-soluble organic solvent is preferable, and it is particularly preferable to use water. When water is used, the coating liquid is preferably in the form of an aqueous solution or an aqueous dispersion (ie, an aqueous coating liquid).

As the polyvinylidene chloride copolymer, any known or commercially available one may be used, as explained in "1. Gas barrier laminate" above. Moreover, those obtained by known manufacturing methods (for example, emulsion polymerization method, etc.) can also be used. In this case, in the emulsion polymerization method, the polyvinylidene chloride copolymer can be obtained in the form of latex, but the latex or a liquid with its concentration adjusted can also be used as the coating liquid for forming the PVDC layer (III). . In this case, the average particle size of the polyvinylidene chloride copolymer in the coating solution for forming the PVDC layer (III) is usually preferably 0.05 to 0.5 μm, particularly 0.07 to 0.3 μm. It is more preferable. By adjusting the particle size to such a particle size, the storage stability and coating properties of the latex can be further improved.

In addition, within a range that does not impede the effects of the present invention, the coating liquid for forming the PVDC layer (III) may contain pigments, antioxidants, antistatic agents, ultraviolet absorbers, lubricants, preservatives, fillers, etc. as necessary. One or more types of additives such as agents can be added. For example, for the purpose of increasing the weight, at least one filler such as heavy or soft calcium carbonate, mica, talc, kaolin, gypsum, clay, barium sulfate, alumina, silica, magnesium carbonate, etc. can be blended. The total amount of these additives is preferably in the range of about 0.001 to 2.0 parts by mass based on 100 parts by mass of PVDC.

The coating solution for forming the PVDC layer (III) can be prepared by a known method using, for example, a dissolving pot equipped with a stirrer. For example, the concentration of the polyvinylidene chloride copolymer in the coating liquid in this case is not particularly limited, but can be appropriately set, for example, in a range of about 5 to 60% by mass.

The method of applying the coating liquid for forming the PVDC layer (III) is not particularly limited. For example, an air knife coater, a kiss roll coater, a metal ring bar coater, a gravure roll coater, a reverse roll coater, a dip coater, a die coater, or a combination of any of these can be used. These can be carried out using known or commercially available equipment.

After applying the coating solution for forming the PVDC layer (III), it may be dried naturally, but it is preferable to dry it by heating. The method of drying by heating is not particularly limited, and examples include methods of forming a PVDC layer (III) as a dry film by evaporating water and the like by blowing hot air using a dryer or the like, or by irradiating infrared rays.

The drying temperature in the case of heat drying can be set appropriately depending on the presence or absence of additive components and their content, but is usually about 50 to 160°C, particularly preferably 80 to 140°C, and more preferably 100 to 120°C. It is more preferable that the temperature is ℃. If the drying temperature is too low, it will take a long time to form a dry film and reduce productivity. On the other hand, if the heat treatment temperature is too high, the plastic base material (I) may become brittle or a bumping phenomenon may occur due to the rapid temperature rise of the coating solution for forming the PVDC layer (III), making it impossible to obtain a uniform film. There is.

Furthermore, when applying the coating liquid for forming the PVDC layer (III), irradiation with high-energy rays such as ultraviolet rays, X-rays, and electron beams may be performed as necessary before and after drying. In such a case, a component that is crosslinked or polymerized by high-energy ray irradiation may be included.

(3) Stretching process In the stretching process, the unstretched film coated with both of the above-mentioned coating solutions and dried is stretched. That is, the laminate of the present invention can be suitably obtained by the so-called in-line coating method. By using the in-line coating method, it is possible to perform the heat treatment necessary for film stretching and heat setting, and the heat treatment of the gas barrier layer (II) and PVDC layer (III) simultaneously and at a relatively high temperature. performance and productivity. On the other hand, when heat treatment is performed to form the gas barrier layer (II) and PVDC layer (III) on the stretched film (using the so-called offline coating method), the stretched film that has been heat-treated in the stretching process is further coated. Because the plastic base material (I) is exposed to the heat treatment, the amount of heat received by the plastic base material (I) becomes excessive, causing it to become brittle, and there is a risk that its strength and elongation, pinhole resistance, bending resistance, etc. may decrease. In addition, when applying the coating solution for forming the PVDC layer (III) to the stretched film, the metal compounds in the stretched film migrate to the PVDC layer (III) side, and the polyester contained in the gas barrier layer (II) Carboxylic acids and the metal compound in the plastic base material (I) become difficult to react, and gas barrier performance may deteriorate.

Although the stretching ratio of the film is not limited, it is preferably 1.5 times or more in each of the machine direction (MD) and the transverse direction (TD), and particularly preferably 2 to 4 times. Further, the area magnification is usually preferably 3 times or more, particularly preferably 6 to 20 times, and most preferably 6.5 to 13 times. By setting the stretching ratio within the above range, it is possible to obtain a gas barrier laminate with better mechanical properties.

Regarding the temperature conditions in the stretching step, for example, when performing simultaneous biaxial stretching as described above, it is usually preferable to stretch in a temperature range of about 100 to 250°C (preferably 150 to 200°C). By controlling the temperature within such a range, the film of the present invention can be manufactured more reliably. These temperatures can be set and controlled, for example, while being preheated in a preheating zone of the stretching device.

The film that has undergone the stretching process is heat-set at a temperature of 150 to 300°C in the tenter where the stretching process was carried out, and if necessary, the film is stretched in the longitudinal direction and/or in the range of 0 to 10%, preferably 2 to 6%. Lateral relaxation treatment is applied. In order to reduce the heat shrinkage rate, it is desirable not only to optimize the temperature and time of the heat-setting time, but also to perform the heat-relaxation treatment at a temperature lower than the maximum temperature of the heat-setting treatment.

In the in-line coating method preferred in the present invention, the heat treatment for heat fixing the film is mainly the heat treatment for the gas barrier layer (II) and the PVDC layer (III).

The heat treatment temperature for the gas barrier layer (II) can be appropriately set depending on, for example, the presence or absence of additive components and their content, but it is usually about 120 to 300°C, particularly preferably about 160 to 250°C, and more preferably about 180 to 250°C. More preferably, the temperature is between 220°C and 220°C. If the heat treatment temperature is too low, for example, the ester crosslinking reaction between polycarboxylic acids and polyalcohol may not proceed sufficiently, and ions of the metal compound of the plastic base material (I) may be formed during the subsequent hot water treatment. The crosslinking reaction may not proceed sufficiently, and it may be difficult to obtain a laminate having sufficient gas barrier properties. On the other hand, if the heat treatment temperature is too high, the laminate may become brittle.

Further, the heat treatment time may normally be 5 minutes or less, but it is particularly preferably 1 second to 5 minutes, more preferably 3 seconds to 2 minutes, and more preferably 5 seconds to 1 minute. is most preferable. If the heat treatment time is too short, the crosslinking reaction cannot proceed sufficiently, making it difficult to obtain a laminate having gas barrier properties. On the other hand, if the heat treatment time is too long, productivity will decrease.

The heat treatment temperature for the PVDC layer (III) can be appropriately set depending on, for example, the presence or absence of additive components and their content, but it is usually about 120 to 300°C, particularly preferably about 160 to 250°C, and more preferably about 180 to 250°C. More preferably, the temperature is between 220°C and 220°C. If the heat treatment temperature is too low, the film-forming properties of the PVDC layer (III) will be insufficient, and there is a risk that the gas barrier properties and water vapor barrier properties will decrease, and the adhesion to the plastic substrate (I) will decrease. On the other hand, if the heat treatment temperature is too high, the laminate may become brittle.

The heat treatment time may normally be 5 minutes or less, preferably 1 second to 5 minutes, particularly preferably 3 seconds to 2 minutes, and most preferably 5 seconds to 1 minute. preferable. If the heat treatment time is too short, the film-forming properties of the PVDC layer (III) will be insufficient, and there is a risk that the gas barrier properties and water vapor barrier properties will decrease, and the adhesion to the plastic substrate (I) will decrease. On the other hand, if the heat treatment time is too long, productivity may decrease.

The gas barrier laminate of the present invention may be subjected to surface treatment such as corona discharge treatment, if necessary. Further, the gas barrier laminate of the present invention may be subjected to an aging treatment at a relatively low temperature, usually about 40 to 60° C., for about 24 to 96 hours, if necessary.

The gas barrier laminate of the present invention can be made into various laminate films by laminating a sealant layer or the like as necessary.

The resin used for forming the sealant layer is not particularly limited, and includes, for example, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, polyethylene/polypropylene copolymer, and ethylene-vinyl acetate copolymer. Polyethylene, which has high heat-sealing strength and the strength of the material itself, Polyolefin resins such as polypropylene and polyethylene/polypropylene copolymers are preferred. These resins may be used alone or may be melt-mixed with other resins. Further, these resins may be subjected to acid modification or the like.

Methods for forming the sealant layer on the gas barrier laminate are not limited, and include, for example, a) a method of laminating a film or sheet made of a sealant resin onto the gas barrier laminate via an adhesive; b) a method of laminating a sealant resin on the gas barrier laminate; Examples include a method of extrusion lamination into a gas barrier laminate. In the former method, the film or sheet made of the sealant resin may be in an unstretched state or in a stretched state at a low magnification, but for practical purposes it is preferably in an unstretched state.

The thickness of the sealant layer is not particularly limited, but it is usually preferably about 20 to 100 μm, particularly preferably 40 to 70 μm.

In the present invention, the laminate obtained as described above may be further subjected to a step (4) of hot water treatment. Thereby, oxygen barrier properties etc. can be further improved. Regarding hot water treatment, the laminate obtained as described above is usually subjected to the hot water treatment in the form of a package (such as a package with the contents sealed). Alternatively, it is also possible to adopt either a method in which the packaged product is treated with hot water prior to use, or a method in which the laminate obtained as described above is treated with hot water in the form of a film. can. The conditions for the hot water treatment are not limited, but it is preferable to follow the hot water treatment method described in "4. Use of gas barrier laminate" below.

Therefore, the present invention also includes a manufacturing method that uses a laminate having the same physical properties as the laminate obtained in steps (1) to (3) above as a starting material and includes a step of treating the same with hot water. . That is, it is a laminate that includes at least a polyvinylidene chloride copolymer-containing layer (III), a plastic base material (I), and a gas barrier layer (II) in this order, and (1) the plastic base material (I) contains a resin component and a metal (2) the gas barrier layer (II) contains a polycarboxylic acid and/or its anhydride, and the content of the metal compound is 0.1 to 20% by mass; (I), and (3) the polyvinylidene chloride copolymer-containing layer (III) is laminated on the other surface of the plastic substrate (I) on which the gas barrier layer (II) is laminated. (4) Regarding the oxygen permeability and water vapor permeability of the laminate, (4-1) the oxygen permeability at a temperature of 20°C and an atmosphere of 90% relative humidity is 100 ml/(m ² ·day・MPa) or less, and (4-2) hot water treatment of a laminate characterized by having a water vapor permeability of 30 g/(m ² ·day) or less under an atmosphere of a temperature of 40° C. and a relative humidity of 90%. The present invention includes a method for producing a gas barrier laminate characterized by including the steps.

By this manufacturing method, the oxygen barrier properties and the like of the laminate used as the starting material can be further strengthened. That is, the above-mentioned step of hot water treatment can be a step of reducing oxygen permeability by hot water treatment, and the reduction amount is, for example, 5 ml/(m ² · day · MPa) or more ( In particular, it is sufficient if the amount can be reduced within a range of 10 to 100 ml/(m ² ·day · MPa), but the present invention is not limited thereto.

4. Use of gas barrier laminate The laminate of the present invention can be used for various purposes, and in particular, it can be suitably used as a packaging material by taking advantage of its gas barrier properties and water vapor barrier properties. In particular, it can be used as a material for constructing a bag (packaging bag).

More specifically, it can be preferably used as a material for constructing a packaging bag for sealing contents. Furthermore, it can be suitably used as a closed packaging bag to be subjected to hot water treatment, such as a retort pouch. That is, the hot water treatment can be suitably carried out in the state of a packaged product in which the contents are sealed in a package formed from the laminate of the present invention.

Here, the conditions for the hot water treatment are not particularly limited, and can be set within a range that allows desired oxygen permeability (gas barrier properties) to be achieved. For example, the temperature (water temperature) of hot water treatment is usually about 30 to 130 degrees Celsius (under pressure if it is 100 degrees Celsius or higher), preferably 60 degrees Celsius or more and less than 100 degrees Celsius, especially 70 to 95 degrees Celsius. is most preferable. Further, the time for the hot water treatment can be appropriately set depending on the treatment temperature, etc., usually within a range of about 1 second to 100 hours, but is not limited thereto.

The form of the bag is not particularly limited, and includes, for example, a two-sided bag, a three-sided bag, a three-sided zippered bag, a gassho bag, a gusset bag, a bottom gusset bag, a stand bag, a stand zipper bag, a two-sided bag, and a four-sided pillar flat bottom gusset bag. , side seal bags, bottom seal bags, etc.

Such packaging bags are suitable for, for example, food and beverages, fruits, juices, drinking water, alcohol, cooked foods, seafood paste products, frozen foods, meat products, boiled foods, rice cakes, liquid soups, seasonings, etc. Various contents such as various food and beverages, liquid detergents, cosmetics, and chemical products can be filled and packaged.

Examples and comparative examples will be shown below to explain the features of the present invention more specifically. However, the scope of the present invention is not limited to the examples.

A. Regarding raw materials used The raw materials used in each example and comparative example are as follows.
(1) Plastic base material (I) Thermoplastic resin for composition a) Nylon 6 resin: Nylon 6 resin (“A1030BRF” manufactured by Unitika, relative viscosity 3.0 (25°C))
b) _SiO2- containing master chip: nylon 6 resin containing 6% by mass of silica (“A1030QW” manufactured by Unitika, relative viscosity 2.7 (25°C))

(2) Metal compound for plastic base material (I) composition a) MgO: Magnesium oxide (“PUREMAG FNM-G” manufactured by Tateho Chemical Industry Co., Ltd., average particle size 0.4 μm)
b) CaCO ₃ : Calcium carbonate (“VIgot15” manufactured by Shiraishi Kogyo Co., Ltd., average particle size 0.5 μm)
c) ZnO: Zinc oxide (“FINEX-50” manufactured by Sakai Chemical Industry Co., Ltd., average particle size 0.02 μm)

(3) Polycarboxylic acid component of coating liquid for forming gas barrier layer (II) a) EMA aqueous solution:
Ethylene-maleic acid copolymer (weight average molecular weight 60,000) and sodium hydroxide were added to water, dissolved by heating, and then cooled to room temperature. Neutralized aqueous EMA solution with a solid content of 15% by mass. (Denoted as "EMA" in Table 1)
b) PAA aqueous solution:
Prepared using polyacrylic acid ("A10H" manufactured by Toagosei Co., Ltd., weight average molecular weight 200,000, 25% aqueous solution) and sodium hydroxide, 10 mol% of the carboxyl groups of polyacrylic acid was sodium hydroxide. An aqueous solution of polyacrylic acid (PAA) with a solid content of 15% by mass, neutralized by (Denoted as “PAA” in Table 1)

(4) Other resin components of the coating liquid for forming gas barrier layer (II) a) PVA aqueous solution:
Polyvinyl with a solid content of 15% by mass, prepared by adding polyvinyl alcohol ("Poval 105" manufactured by Kuraray Co., Ltd., degree of saponification 98-99%, average degree of polymerization about 500) to water, heating and dissolving, and cooling to room temperature. Alcohol (PVA) aqueous solution. (Denoted as “PVA” in Table 1)
b) EVOH aqueous solution:
An ethylene-vinyl alcohol copolymer (EVOH) aqueous solution with a solid content of 10% by mass in which an ethylene-vinyl alcohol copolymer ("Exeval AQ-4105" manufactured by Kuraray Co., Ltd.) is dissolved. (Denoted as “EVOH” in Table 1)

(5) Coating liquid for forming polyvinylidene chloride copolymer resin-containing layer (III) a) Polyvinylidene chloride copolymer resin 1
Asahi Kasei Saran Latex L536B (solid concentration 49% by mass) (denoted as "L536B" in Table 1)
b) Polyvinylidene chloride copolymer resin 2
Asahi Kasei Saran Latex L549B (solid concentration 48% by mass) (denoted as "L549B" in Table 1)
c) Polyvinylidene chloride copolymer resin 3
Asahi Kasei Saran Latex L509 (solid content concentration 50% by mass) (denoted as "L509" in Table 1)

B. About Examples and Comparative Examples
Example 1
Nylon 6 resin, a SiO ₂ -containing master chip, and magnesium oxide were mixed such that the content of magnesium oxide was about 0.5% by mass and the content of silica was about 1.5% by mass. This mixture was put into an extruder and melted in a cylinder at 270°C. The melt was extruded into a sheet form through a T-die orifice, brought into close contact with a rotating drum cooled to 10° C., and rapidly cooled to obtain an unstretched film with a thickness of 150 μm. The obtained unstretched film was sent to a 50° C. hot water bath and subjected to water immersion treatment for 2 minutes.
Next, the EMA aqueous solution and the PVA aqueous solution were mixed so that the mass ratio (solid content) of EMA and PVA was 70/30 to form a gas barrier layer (II) forming coating liquid with a solid content of 10% by mass. Obtained. This coating liquid was applied to one side of the unstretched film that had been subjected to the water immersion treatment by an air knife coating method, and then dried for 30 seconds using an infrared irradiator at a temperature of 110°C.
In the unstretched film coated with the gas barrier layer (II) forming coating liquid, apply the PVDC layer (III) forming coating liquid to the opposite side to which the gas barrier layer (II) forming coating liquid was applied. A coating liquid made of polyvinylidene chloride copolymer resin 1 was applied by an air knife coating method, and dried for 30 seconds using an infrared irradiator at a temperature of 110°C.
The ends of the unstretched film, in which the coating liquid for forming the gas barrier layer (II) and the coating liquid for forming the PVDC layer (III) were laminated on both sides, were held in the clips of a tenter type simultaneous biaxial stretching machine. It was stretched 3.3 times in the MD and TD at ℃. Thereafter, heat treatment was performed at 210°C for 4 seconds with a TD relaxation rate of 5%, and the mixture was slowly cooled to room temperature. ) and a 1.5 μm polyvinylidene chloride resin copolymer layer (III) was obtained.

Examples 2 to 11 and Comparative Examples 1 to 5
Example 1 except that the type and content of the metal compound in the thermoplastic resin film (I), the composition and coating thickness of the gas barrier layer (II) and PVDC (III) were changed as described in Table 1. A laminate was obtained in the same manner.

Example 12
A laminate was obtained in the same manner as in Example 1, except that the PVDC layer (III) was formed not before stretching but after slow cooling of the stretched film. To form the PVDC layer (III), apply a coating solution for forming PVDC (III) using an air knife coating method to the opposite side on which the gas barrier layer (II) is laminated, and then apply it using an infrared irradiation machine at a temperature of 110°C. A drying process was performed for 30 seconds.

Comparative example 6
After obtaining a laminate in the same manner as in Comparative Example 1, a vapor deposited film of aluminum oxide having a thickness of 300 Å was formed on the opposite surface of the gas barrier layer (II) by a known vacuum vapor deposition method.

Test example 1
Regarding the samples (laminates) obtained in each example and comparative example, the following physical properties were measured according to the respective measurement methods. The results are shown in Table 1.

(1) Thickness of each layer After leaving the obtained gas barrier laminate in an environment with a temperature of 23°C and a relative humidity of 50% RH for 2 hours or more, a cross-section of the film was observed using a scanning electron microscope (SEM), and each layer was The thickness was measured.

(2) Oxygen permeability The oxygen permeability of the obtained gas barrier laminate before and after hot water treatment was measured using an oxygen barrier measuring device (product name: OX-TRAN 2/20, manufactured by Mocon Co., Ltd.) at a temperature of 20°C and Measurements were made in an atmosphere with relative humidity of 90%. As a pretreatment for measurement, a gas barrier laminate before hot water treatment, or a gas barrier laminate after hot water treatment in which attached water droplets were wiped off by hot water treatment under conditions of 80°C x 30 minutes or 120°C x 30 minutes. The body was left in an environment with a temperature of 20° C. and a relative humidity of 90% RH for 2 hours or more, and then measurements were taken. The unit is "ml/( ^m2・day・MPa)".

(3) Water vapor permeability The water vapor permeability of the obtained gas barrier laminate before and after hot water treatment was determined using a water vapor barrier measuring device (product name "PERMATRAN-W 3/33" manufactured by Mocon) at a temperature of 40°C and Measurements were made in an atmosphere with relative humidity of 90%. As a pretreatment for measurement, a gas barrier laminate before hot water treatment, or a gas barrier laminate after hot water treatment in which attached water droplets were wiped off by hot water treatment under conditions of 80°C x 30 minutes or 120°C x 30 minutes. The body was left in an environment with a temperature of 20° C. and a relative humidity of 90% RH for 2 hours or more, and then measurements were taken. The unit is "g/(m ² ·day)".

(4) Metal content in the film and amount of reduction After heating the gas barrier laminate before and after hot water treatment at 120°C for 30 minutes in a mixed acid of nitric acid and sulfuric acid, remove the insoluble portion with a mixed acid of perchloric acid and hydrofluoric acid. The mixture was heated in a container to completely dissolve it. The metal concentration in this solution was measured using a plasma atomic emission spectrometer (product name "iCAP6500Duo" manufactured by Thermo Fisher Scientific), the metal content in the film was calculated, and the reduction rate of the metal content was calculated using the following formula. Calculated based on.
Metal content reduction rate (%) = [(MA-MB)/MA] x 100
MA: Metal content in the film before hot water treatment (mass%)
MB: Metal content (mass%) in the film after hot water treatment at 120°C for 30 minutes

(5) Flexibility The obtained gas barrier laminate was treated with hot water at 120°C for 30 minutes and attached water droplets were wiped off. %RH for 2 hours, and then bent 500 times in a gelbo tester (manufactured by Tester Sangyo Co., Ltd.) at 20°C x 65% RH in accordance with ASTM F 392 (440 degrees bending at 90 mm plus 65 mm linear motion). After repeating certain conditions), the oxygen permeability and water vapor permeability were measured in the same manner as in (2) and (3) above, and the rate of increase in each permeability was calculated according to the following formula. When the increase rate was 20% or less, it was marked as "○", and when it exceeded 20%, it was marked as "x".
Transmittance increase rate (%) = [(PA-PB)/PA] x 100
PA: Transmittance after 500 bends PB: Transmittance before 500 bends

As is clear from the results in Table 1, in Examples 1 to 12, a gas barrier layer containing polycarboxylic acid ( II) is laminated and a PVDC layer (III) is laminated on the other side, so it not only has excellent oxygen gas barrier properties and water vapor barrier properties before hot water treatment, but also allows hot water treatment at relatively low temperatures and in a short time. It can be seen that even after this process, a gas barrier laminate having both good oxygen gas barrier properties and water vapor barrier properties can be obtained. In particular, when comparing Example 1 and Example 12, the oxygen permeability after hot water treatment of Example 1, in which the PVDC layer (III) was laminated by the in-line coating method, was lower than that of Example 12, and it had better gas barrier properties. I can also see that.

On the other hand, in Comparative Example 1, since the PVDC layer (III) was not formed, the oxygen permeability before the hot water treatment was high and the oxygen barrier property was low. It can also be seen that the amount of metal flowing out due to the hot water treatment increased, so the oxygen permeability was high even after the hot water treatment at a relatively low temperature and in a short time.
In Comparative Example 2, the amount of metal compound contained in the plastic base material (I) was less than the range defined by the present invention, so the oxygen permeability after the hot water treatment was high.
In Comparative Example 3, since the gas barrier layer (II) did not contain polycarboxylic acid, the resulting laminate had a high oxygen permeability after hot water treatment.
In Comparative Example 4, since the gas barrier layer (II) was not formed, the obtained laminate had a high oxygen permeability after the hot water treatment.
In Comparative Example 5, the PVDC layer (III) was not laminated on the other surface of the plastic substrate (I) on which the gas barrier layer (II) was laminated, so the oxygen permeation of the resulting laminate after hot water treatment was The degree was high.
Comparative Example 6 had low oxygen permeability and water vapor permeability, but the desired performance could not be maintained because the oxygen permeability and water vapor permeability decreased after bending.

Claims (8)

A laminate including, in order, at least a polyvinylidene chloride copolymer-containing layer (III), a plastic base material containing a polyamide film (I), and a gas barrier layer (II),
(1) The plastic base material (I) contains a resin component and a metal compound, and the content of the metal compound is 0.1 to 20% by mass,
(2) The gas barrier layer (II) contains polycarboxylic acid and/or its anhydride, and is laminated on one surface of the plastic base material (I),
(3) The polyvinylidene chloride copolymer-containing layer (III) is laminated on the other surface of the plastic base material (I) on which the gas barrier layer (II) is laminated,
(4) In the oxygen permeability and water vapor permeability of the laminate,
(4-1) Oxygen permeability is 100 ml/(m ² · day · MPa) or less at a temperature of 20 ° C. and a relative humidity of 90% atmosphere,
(4-2) A gas barrier laminate having a water vapor permeability of 30 g/(m ² ·day) or less at a temperature of 40° C. and a relative humidity of 90%. The gas barrier laminate according to claim 1 , wherein the gas barrier layer (II) further contains polyalcohol. (A) Oxygen permeability and water vapor permeability after subjecting the laminate to hot water treatment at a temperature of 80°C for 30 minutes. (A2) the water vapor permeability at a temperature of 40°C and an atmosphere of 90% relative humidity is 30 g/(m ^{2 ·} day) or less,
(B) The oxygen permeability and water vapor permeability after the laminate was subjected to hot water treatment at a temperature of 120°C for 30 minutes, (B1) The oxygen permeability at a temperature of 20°C and an atmosphere of 90% relative humidity was 50ml/( ^m2・day・MPa) or less, and (B2) the water vapor permeability at a temperature of 40° C. and a relative humidity of 90% atmosphere is 30 g/( ^m2・day) or less,
The gas barrier laminate according to claim 1 or 2 . A laminate including, in order, at least a polyvinylidene chloride copolymer-containing layer (III), a plastic base material containing a polyamide film (I), and a gas barrier layer (II),
(1) The plastic base material (I) contains a resin component and a metal compound, and the content of the metal compound is 0.1 to 20% by mass,
(2) The gas barrier layer (II) contains polycarboxylic acid and/or its anhydride, and is laminated on one surface of the plastic base material (I),
(3) The polyvinylidene chloride copolymer-containing layer (III) is laminated on the other surface of the plastic base material (I) on which the gas barrier layer (II) is laminated,
(4) In the oxygen permeability and water vapor permeability of the laminate,
(4-1) The oxygen permeability is 50 ml/(m ² ·day · MPa) or less at a temperature of 20°C and a relative humidity of 90% atmosphere,
(4-2) A gas barrier laminate having a water vapor permeability of 30 g/(m ² ·day) or less at a temperature of 40° C. and a relative humidity of 90%. A packaging material comprising the gas barrier laminate according to any one of claims 1 to 4 . Packaging material according to claim 5 , used for sealing contents. At least a) polyvinylidene chloride copolymer-containing layer (III), b) a plastic base material (I) containing a resin component and a metal compound, and containing the metal compound in a content of 0.1 to 20% by mass, and c ) A method for producing a gas barrier laminate sequentially comprising a gas barrier layer (II), the method comprising:
(1) A step of applying a coating liquid for forming a gas barrier layer (II) containing a polycarboxylic acid and/or its anhydride on one surface of the plastic substrate (I),
(2) a step of applying a coating liquid for forming a polyvinylidene chloride copolymer-containing layer (III) on the other surface of the plastic base material (I);
(3) After the steps (1) and (2) above, a method for producing a gas barrier laminate, which comprises the step of stretching the laminate on which the coating film of both coating liquids has been formed. A method for manufacturing the gas barrier laminate according to claim 3 , comprising:
A laminate including, in order, at least a polyvinylidene chloride copolymer-containing layer (III), a plastic base material containing a polyamide film (I), and a gas barrier layer (II),
(1) The plastic base material (I) contains a resin component and a metal compound, and the content of the metal compound is 0.1 to 20% by mass,
(2) The gas barrier layer (II) contains polycarboxylic acid and/or its anhydride, and is laminated on one surface of the plastic base material (I),
(3) The polyvinylidene chloride copolymer-containing layer (III) is laminated on the other surface of the plastic base material (I) on which the gas barrier layer (II) is laminated,
(4) In the oxygen permeability and water vapor permeability of the laminate,
(4-1) Oxygen permeability is 100 ml/(m ² · day · MPa) or less at a temperature of 20 ° C. and a relative humidity of 90% atmosphere,
(4-2) Water vapor permeability is 30 g/(m ² ·day) or less at a temperature of 40°C and a relative humidity of 90%,
A method for producing a gas barrier laminate, comprising the step of subjecting the laminate to hot water treatment.