JP2005081700A - Manufacturing method for gas barrier laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a gas barrier laminate (2) capable of industrially and continuously manufacturing the gas barrier laminate, which has higher gas barrier properties than before under a high humidity condition though a water soluble polymer is used, under a mild condition not bringing about the thermal deterioration of a plastic base material or a gas barrier layer ready to be formed. <P>SOLUTION: The gas barrier laminate (1) is manufactured by applying a coating agent (A) for forming the gas barrier layer at least to one side of a plastic film directly or applying the same to the coating layer of other coating agent (B) provided at least on one side of the plastic film and heat-treating the coated plastic film. This laminate (1) is fed through a moist heat treatment tank held to a high temperature and high humidity state with a temperature of 60-100°C and a relative humidity of 80% or above by spraying water containing a divalent or above metal compound along with steam under atmospheric pressure to be subjected to moist heat treatment. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a gas barrier laminate. Specifically, the present invention relates to a method for continuously industrially producing a gas barrier laminate having excellent gas barrier properties even under high humidity.

  Thermoplastic resin films such as polyamide film, polyester film, and polyolefin film are excellent in strength, transparency, and moldability, and are therefore used in a wide range of applications as packaging materials. However, since these thermoplastic resin films have large gas permeability such as oxygen, when used for packaging general foods, retort-treated foods, cosmetics, medical supplies, agricultural chemicals, etc., oxygen that has permeated the film during long-term storage, etc. The contents of the contents may be altered by the gas.

  Therefore, a laminated film in which a thermoplastic resin surface is coated with a polyvinylidene chloride (hereinafter abbreviated as PVDC) emulsion or the like to form a PVDC layer having a high gas barrier property has been widely used for food packaging and the like. However, since PVDC generates an organic substance such as acid gas during incineration, interest in the environment has increased in recent years, and a shift to other materials has been strongly desired.

  Polyvinyl alcohol (hereinafter abbreviated as PVA) as an alternative to PVDC does not generate toxic gas and has a high gas barrier property in a low humidity atmosphere. However, as the humidity increases, the gas barrier property decreases rapidly. It cannot be used for packaging foods. In addition, it cannot withstand storage in a humid environment.

As a method for coating a film with a liquid composition comprising a water-soluble polymer and exhibiting a high gas barrier property even under high humidity, an aqueous solution comprising a partially neutralized product of PVA or saccharide and polyacrylic acid or polymethacrylic acid is used. A method is proposed in which both polymers are crosslinked by an ester bond by coating and heat treatment (Patent Document 1: Japanese Patent Laid-Open No. 06-220221, Patent Document 2: JP 07-0102083, Patent Document 3: JP-A-07-205379, Patent Document 4: JP-A-07-266441, Patent Document 5: JP-A-08-041218, Patent Document 6: JP-A-10-237180, Patent Document 7: JP-A 2000-000931. No. publication etc.).
However, the method proposed in the above publication requires high-temperature and long-time heat treatment in order to develop a high level of gas barrier properties, and a large amount of energy is required during production, so the load on the environment is not small.
In addition, when heat treatment is performed at a high temperature for a long time, there is a risk of discoloration or decomposition of PVA or the like constituting the barrier layer, and deformation such as shrinkage or wrinkle occurs in the base material such as a plastic film on which the barrier layer is laminated. In addition, when the substrate is used as a packaging material due to thermal deterioration of the base material, bag breakage or the like due to insufficient strength or insufficient adhesion at a deformed portion is likely to occur, making it unsuitable for practical use. In order to prevent the deterioration of the plastic substrate, it is necessary to use a special heat-resistant film that can sufficiently withstand high-temperature heating as a substrate, but there are difficulties in terms of versatility and economy.
On the other hand, when the heat treatment temperature is low, it is necessary to perform the treatment for a very long time, which causes a problem that productivity is lowered.

  A method of obtaining a gas barrier laminate having a high gas barrier property even under high humidity while using a water-soluble polymer such as PVA by a heat treatment at a lower temperature or in a shorter time than before has been proposed (Patent Document 8: Japanese Patent Laid-Open No. 2001-323204, Japanese Patent Application Laid-Open No. 2001-323204, Japanese Patent Application Laid-Open No. 2002-020677, and Japanese Patent Application Laid-Open No. 2002-241671.

  The coating agent described in Patent Documents 8 to 10 uses a water-soluble polymer, but has a higher gas barrier than conventional coatings under high humidity at a lower temperature or in a shorter time than the coating agent described in Patent Documents 1 to 7. A gas barrier laminate having properties can be formed.

However, as described in Patent Documents 1 to 10, by heating, a hydroxyl group in PVA and COOH in polyacrylic acid or ethylene-maleic acid copolymer are esterified, or a metal cross-linked structure is introduced. However, there is a limit in improving the gas barrier property under high humidity. That is, the oxygen permeability did not decrease beyond a certain value even if the heating conditions were higher for a longer time, but when it increased, the reverse phenomenon occurred. It is considered that the plastic substrate and the barrier layer being formed were thermally deteriorated due to severe heating conditions. Further, the heating condition of high temperature and long time also causes coloring and curling of the plastic substrate and the barrier layer being formed, which is not preferable in this respect.
As a result of the above, today, further improvement of gas barrier properties under high humidity is being increasingly demanded, and it has not been possible to meet more stringent requirements simply by heating and curing the coating agent described in Patent Documents 1-10.

Japanese Patent Laid-Open No. 06-220221 Japanese Patent Application Laid-Open No. 07-102083 Japanese Patent Application Laid-Open No. 07-205379 Japanese Patent Application Laid-Open No. 07-266441 Japanese Patent Application Laid-Open No. 08-041218 Japanese Patent Laid-Open No. 10-237180 JP 2000-000931 A JP 2001-323204 A JP 2002-020677 A JP 2002-241671 A

  An object of the present invention is to provide a gas barrier laminate having a gas barrier property higher than that of a conventional one under a high humidity while using a water-soluble polymer, and a mild condition that does not cause thermal deterioration of a plastic substrate or a barrier layer that is being formed. Therefore, it is to manufacture industrially continuously.

  In the first invention, the coating agent for gas barrier layer formation (A) is applied directly on at least one surface of the plastic film or on the coating layer of another coating agent (B) provided on at least one surface of the plastic film. The gas barrier laminate (1) formed by coating and heat treatment was sprayed with water containing a metal compound having a valence of 2 or more together with water vapor under atmospheric pressure, at a temperature of 60 ° C. to 100 ° C. and a relative humidity of 80%. It is related with the manufacturing method of the gas-barrier laminated body (2) characterized by conveying in the high-temperature, high-humidity wet heat-treatment tank, and performing a wet heat treatment.

  In a second invention, the gas barrier layer-forming coating agent (A) contains a polyalcohol polymer and a polycarboxylic acid polymer, and the method for producing a gas barrier laminate according to the first invention About.

  A third invention relates to a method for producing a gas barrier laminate (2) according to the second invention, wherein a divalent or higher valent metal compound can react with a hydroxyl group or a carboxyl group.

  The fourth invention is characterized in that the divalent or higher valent metal compound contains one or more of divalent or higher metal hydroxides, carbonates, acetates and phosphates. The present invention relates to a method for producing a gas barrier laminate (2) according to the invention of 3.

  According to a fifth invention, the gas barrier laminate according to any one of the third to fourth inventions, wherein the divalent or higher valent metal is any one of Mg or Ca or a mixture thereof. The manufacturing method of (2).

  A sixth invention relates to a method for producing a gas barrier laminate (2) according to any one of the second to fifth inventions, wherein the polyalcohol polymer is polyvinyl alcohol or saccharide.

  The seventh invention provides the gas barrier laminate (2) according to any one of the second to sixth inventions, wherein the polycarboxylic acid polymer is a poly (meth) acrylic acid polymer. Regarding the method.

  The eighth invention is characterized in that the polycarboxylic acid polymer is a polymer formed by addition polymerization of a monomer having a dibasic acid having a carbon-carbon double bond as an essential component. The invention relates to a method for producing a gas barrier laminate (2) according to any one of the inventions.

  The ninth invention is characterized in that the polymer formed by addition polymerization of a monomer containing a dibasic acid having a carbon-carbon double bond as an essential component is an olefin-maleic acid copolymer or a polyitaconic acid polymer. The present invention relates to a method for producing a gas barrier laminate (2) according to an eighth invention.

  In a tenth aspect of the invention, the olefin-maleic acid copolymer is at least one selected from the group consisting of an ethylene-maleic acid copolymer, a methyl vinyl ether-maleic acid copolymer, and an isobutylene-maleic acid copolymer. The present invention relates to a method for producing a gas barrier laminate (2) according to the ninth invention.

  According to the present invention, a gas barrier laminate having a higher gas barrier property than conventional ones can be obtained industrially continuously under mild conditions that do not cause thermal deterioration of a plastic substrate or a barrier layer that is being formed.

Hereinafter, the present invention will be described with reference to the drawings.
FIG. 1 shows that a gas barrier laminate (1) is sprayed into a wet heat treatment tank under atmospheric pressure simultaneously with water vapor and water containing a metal compound having a valence of 2 or more, or alternately or completely independently of each other. And it is a conceptual diagram which shows the method of conveying the inside of the wet heat processing tank made into the hot and humid state, and obtaining a gas-barrier laminated body (2) continuously.

[Gas Barrier Laminate (1)]
In order to obtain the gas-barrier laminate (1), the following steps are performed.
(1) A gas barrier layer forming coating agent (A) described later is applied directly on a plastic film described later or on an anchor coating agent (B) layer provided on a plastic film described later.
For example, the coating agent (A) for forming a gas barrier layer obtained by mixing a polyalcohol polymer and an aqueous solution of a polycarboxylic acid polymer can be used to form a barrier layer having a desired thickness using various apparatuses. To coat. Examples of coating devices include air knife coaters, kiss roll coaters, metering bar coaters, gravure roll coaters, reverse roll coaters, dip coaters, die coaters, comma coaters, lip coaters, curtain coaters, and the like. It can also be used, or a plurality of devices can be combined.
The thickness of the barrier layer to be formed can be appropriately determined according to the application to be used, and is preferably 0.05 μm to 100 μm, more preferably 0.1 μm to 50 μm. A thickness of 3 μm to 10 μm is particularly preferable. If the thickness is less than 0.05 μm, it will be difficult to develop sufficient gas barrier properties. On the other hand, if the thickness exceeds 100 μm, it will be difficult to produce in the production process such as coating, and heating during drying and barrier layer formation will occur. The amount of energy required is too much.

(2) After coating the coating agent (A) for forming the gas barrier layer, the liquid medium in the coating agent (A), for example, moisture is evaporated and dried using various heating devices, and the coating for forming the gas barrier layer A water-soluble polymer in the agent (A) is reacted to form a barrier layer to obtain a gas barrier laminate (1). Examples of the various heating devices include devices such as an arch dryer, a straight bath dryer, a tower dryer, a drum dryer, and a floating dryer. These devices can be used alone, or a plurality of devices can be combined.

[Gas Barrier Laminate (2)]
According to the method described in detail below, the gas barrier laminate (1) is subjected to water vapor and water containing a divalent or higher metal compound at the same time, alternately with each other, or completely independent of each other under atmospheric pressure. Of the gas barrier laminate (1) by spraying it into the wet heat treatment tank and transporting it into a wet heat treatment tank having a temperature of 60 ° C. to 100 ° C. and a relative humidity of 80% or more. The gas barrier laminate (2) having the gas barrier property that has been remarkably improved can be obtained continuously.
That is, as shown in FIG. 1, the gas barrier laminate (1) is attached to the unwinding device 2, the gas barrier laminate (1) is unwound, and the unrolled gas barrier laminate (1) is divalent with water vapor. The water containing the above metal compound is sprayed, and is transported through a wet heat treatment tank having a temperature of 60 ° C. or higher and 100 ° C. or lower and a relative humidity of 80% or higher. The gas barrier laminate (2) can be continuously obtained by drying the moisture and winding it using the winding device 3.
Although not shown in FIG. 1, the gas barrier laminate (2) carried out from the wet heat treatment tank 1 can be washed with water containing no divalent or higher metal compound, dried, and wound up. . The cleaning method may be to transport the gas barrier laminate (2) in water that does not contain a divalent or higher metal compound, or water that does not contain a divalent or higher metal compound in the gas barrier laminate (2). You may spray it like a shower.
The obtained gas barrier laminate (1) may be immediately carried into the wet heat treatment tank 1 and wet heat treated without winding up the gas barrier laminate (1).

The temperature in the wet heat treatment tank in which water vapor and a metal compound having a valence of 2 or more are sprayed to form a high-temperature and high-humidity state is essential to be 60 ° C. or higher and 100 ° C. or lower, more preferably 80 ° C. or higher and 100 ° C. or lower. preferable. In order to obtain a high barrier property at 60 ° C. or lower, a long heat treatment is required. Moreover, since it is under atmospheric pressure, it does not exceed 100 ° C.
Moreover, it is essential that the relative humidity in the wet heat treatment tank is 80% or more, and more preferably 90% or more. Furthermore, there is no particular problem even in the state of partial condensation.

  The passage time of the wet heat treatment tank varies depending on the target gas barrier performance, but is preferably 1 second to 60 minutes, and more preferably 15 seconds to 30 minutes. If it is shorter than 1 second, sufficient metal crosslinking cannot be obtained and high barrier properties cannot be obtained. On the other hand, if it is 60 minutes or longer, it takes too much processing time and is not suitable for industrial production.

As shown in FIG. 1, it is industrially preferable to change the direction of the gas barrier laminate (1) a plurality of times using a direction changing means such as a roll when passing through the wet heat treatment tank. By repeating the direction change a plurality of times, even when transporting at a high speed, it can be retained in the wet heat treatment tank for a longer time, and the wet heat treatment time can be extended.
1 shows a case where the gas barrier laminate (1) is turned up and down, the direction turning as shown in FIGS.

The wet heat treatment tank includes one or more spray ports 6 for spraying water vapor and one or more spray ports 5 for spraying water containing a metal compound having a valence of 2 or more in order to create a hot and humid state inside. .
FIG. 1 shows a case where a plurality of spray ports 5 and spray ports 6 are provided in the upper portion and the side wall portion of the wet heat treatment tank 1.
The spray ports 5 and 6 may be attached anywhere as long as they are inside the wet heat treatment tank, but the spray port 5 is a divalent or higher metal compound dissolved in the water sprayed into the wet heat treatment tank. However, during continuous wet heat treatment of the gas barrier laminate (1), the gas barrier layer is incorporated into the gas barrier layer to form a metal bridge and improve the gas barrier property. It is more preferable to attach so that the water which has a metal compound more than bivalence may be sprayed to the side which forms the gas barrier layer of a body.
In addition, the inside of the wet heat treatment tank that has been sprayed with water vapor and water having a metal compound having a valence of 2 or more to be in a hot and humid state can be further heated using microwaves or the like.

  Examples of the drying device 4 include devices such as arch dryers, straight bath dryers, tower dryers, drum dryers, and floating dryers, or devices that combine them. If necessary, the obtained gas barrier laminate (2) It is a device that can be heated by blowing hot air or irradiating it with infrared rays for the purpose of drying the water inside.

〔water〕
The water containing a divalent or higher-valent metal compound used in the present invention will be described.
It is essential that the water to be sprayed used in the present invention contains a divalent or higher metal compound. That is, the divalent or higher valent metal compound (C) dissolved in the water sprayed into the wet heat treatment tank together with the water vapor is subjected to the wet heat treatment of the gas barrier laminate (1) to the gas barrier layer. Incorporated to form metal crosslinks to improve gas barrier properties and to exhibit excellent gas barrier properties even under high humidity.
It is preferable to contain the metal compound (C) described later as a metal ion concentration of 3 ppm to 3000 ppm, more preferably 10 ppm to 500 ppm, more preferably 20 ppm to 300 ppm, most preferably 30 ppm to 200 ppm. preferable.
When the metal ion concentration is less than 3 ppm, the amount of metal introduced into the gas barrier laminate (1) and contributing to crosslinking decreases, and almost no improvement in barrier properties can be expected. On the other hand, when the content exceeds 3000 ppm, the metal compound is likely to be deposited on the film surface after the wet heat treatment, and the surface is likely to become dirty. Therefore, a separate step of washing away the metal compound on the film surface after the wet heat treatment is required, which increases the number of steps, which is not preferable.

[Divalent or higher metal compound (C)]
The divalent or higher valent metal compound (C) used in the present invention will be described.
The metal compound (C) is a divalent or higher valent metal compound and can react with a carboxyl group or a hydroxyl group. Water acts on the formed gas barrier laminate (2), and the metal compound (C) contained in the hot water moves to the gas barrier laminate (2), resulting in the gas barrier layer forming coating agent (A). It is considered that a crosslinked structure is suitably formed by reacting with a carboxyl group or a hydroxyl group. The cross-linked structure generated here may be a coordinate bond as well as an ionic bond and a covalent bond.

As the metal compound (C) capable of reacting with a carboxyl group,
Bivalent or higher metal halide, hydroxide, oxide, carbonate, phosphate, phosphite, hypophosphite, sulfate or sulfite (C1),
Zirconium complex salts, zirconium halides, zirconium salts of inorganic acids, zirconium salts of organic acids (C2) and the like can be mentioned, and metal compounds (C1) are preferred. As a bivalent or more metal compound (C), 1 type chosen from each group can also be used independently, 2 or more types in each group can also be used together, and 1 chosen from each group. More than one species can be used in combination.

As the metal compound (C1), metal hydroxides, oxides, carbonates, phosphates, phosphites, hypophosphites, sulfates, hydrochlorides, nitrates and the like of divalent or higher metals are preferable. One of these can be used, or two or more can be used in combination.
As a metal more than bivalence, Mg, Ca, Zn, Cu, Co, Fe, Ni, Al, or Zr is preferable, Mg and Ca are more preferable, and Mg is more preferable.
Examples of the Mg compound include MgO, Mg (OH) ₂ , MgSO ₄ , MgCl ₂ , MgCO ₃ , Mg (CH ₃ COOH) ₂ , Mg ₃ (PO ₄ ) ₂ , and the Ca compound includes CaO and Ca. _{(OH) 2, CaSO 4,} CaCl 2, CaCO 3, Ca (CH 3 COOH) 2, Ca 3 (PO 4) 2 and the like.
Examples of the metal compound contained in the water sprayed to wet-heat-treat the gas barrier laminate (1) include Mg (OH) ₂ , MgCO ₂ , Mg (CH ₃ COOH) ₂ , Mg ₃ (PO ₄ ) _2. And Mg compounds such as Ca (OH) ₂ , CaCO ₃ , Ca (CH ₃ COOH) ₂ , and Ca ₃ (PO ₄ ) ₂ are preferable. Mg (OH) ₂ , MgCO ₃ , and Ca (OH) ₂ and CaCO ₃ are more preferable.

  Examples of the metal compound (C2) include zirconium halides such as zirconium oxychloride, hydroxyzirconium chloride, zirconium tetrachloride and zirconium bromide, zirconium salts of mineral acids such as zirconium sulfate, basic zirconium sulfate and zirconium nitrate, and formic acid. Zirconium salt, zirconium salt of organic acid such as zirconium acetate, zirconium propionate, zirconium caprylate, zirconium stearate, ammonium zirconium carbonate, sodium zirconium sulfate, ammonium zirconium acetate, sodium zirconium oxalate, sodium zirconium citrate, zirconium ammonium citrate, etc. Zirconium complex salts are preferred, and ammonium zirconium carbonate is preferred. Examples of ammonium zirconium carbonate include “Zircosol AC-7” manufactured by Newtex Corporation.

As the metal compound contained in the water to be sprayed to wet heat treatment gas barrier laminate (1), when using _{Mg (OH) 2, MgCO 3} , Ca (OH) 2, CaCO 3,, these However, since these compounds have low solubility in water, they may be used in combination with other metal compounds such as sulfates such as Mg, Ca and Na, hydrochlorides, nitrates and the like.

[Gas barrier layer forming coating agent (A)]
The coating agent for forming a gas barrier layer (A) used in the present invention is not particularly limited as long as it is a coating agent that can form a layer having gas barrier properties, but a coating containing a polyalcohol polymer and a polycarboxylic acid polymer. Agents are preferred. When the coating agent is applied to a plastic film or the like and then heated, the hydroxyl group in the polyalcohol polymer and the carboxyl group in the polycarboxylic acid polymer undergo an esterification reaction to form a gas barrier layer.

  The polyalcohol polymer used in the present invention is an alcohol polymer having two or more hydroxyl groups in the molecule, and a polymer of PVA, saccharides and starches, and (meth) acrylic acid esters containing hydroxyl groups. Is included.

  PVA preferably has a saponification degree of 95% or more, more preferably 98% or more, and a number average polymerization degree of usually 300 to 1500.

  As the saccharide, monosaccharide, oligosaccharide and polysaccharide are used. These saccharides include sugar alcohols, various substitution products and derivatives, and cyclic oligosaccharides such as cyclodextrins. These saccharides are preferably soluble in water. Starch is contained in the polysaccharide, but starch used in the present invention includes wheat starch, corn starch, waxy corn starch, potato starch, tapioca starch, rice starch, sweet potato starch, sago starch, etc. In addition to unmodified starch, there are various modified starches. Examples of the modified starch include physically modified starch, enzyme-modified starch, chemically decomposed modified starch, chemically modified starch, and grafted starch obtained by graft polymerization of monomers on starch. Among these starches, processed starch that is soluble in water, such as roasted dextrin and the like, and reduced starch saccharified products obtained by alcoholating the reducing ends thereof are preferable. The starch may be a hydrated product. Moreover, these starches can be used individually or in combination of 2 or more types, respectively.

Examples of (meth) acrylic acid esters containing a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. , 3-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, glycerin (meth) acrylate, polyethylene glycol mono (meth) acrylate (preferably having a repetition of CH ₂ CH ₂ O units of 1 to 6) n = 1 to 6), hydroxyl-terminated urethane (meth) acrylates, and the like, which can be obtained by copolymerizing one or more of them. 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 2-hydroxybutyl ( (Meth) acrylate and glycerin (meth) acrylate are preferred, 2-hydroxyethyl (meth) acrylate and glycerin (meth) acrylate are more preferred, and glycerin (meth) acrylate is particularly preferred.

  The polycarboxylic acid polymer used in the present invention is a (co) polymer having two or more carboxyl groups in the molecule. In addition to a (meth) acrylic acid polymer, an olefin-maleic acid copolymer, itacon It is formed by addition polymerization of a monomer having a dibasic acid having a carbon-carbon double bond as an essential component, such as an acid (co) polymer, a citraconic acid (co) polymer, a fumaric acid (co) polymer ( Co) polymers can be exemplified.

The olefin-maleic acid copolymer used in the present invention is obtained by copolymerizing maleic anhydride and a vinyl monomer by a known method such as solution radical polymerization.
Examples of the copolymerizable olefin monomer include alkyl vinyl ethers having 3 to 30 carbon atoms such as methyl vinyl ether and ethyl vinyl ether, and olefins having 2 to 30 carbon atoms such as ethylene, propylene, and isobutylene. It can also be used. In addition to these olefin monomers, (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate and butyl (meth) acrylate, vinyl esters such as vinyl formate and vinyl acetate, Styrene, p-styrene sulfonic acid or a mixture thereof can also be used. Of these, alkyl vinyl ethers, lower olefins, and the like are preferable in terms of improving gas barrier properties.
Examples of suitable vinyl polymers include methyl vinyl ether-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, etc., among which ethylene-maleic anhydride copolymer is A high gas barrier property can be obtained, and is most preferable.

  The component ratio of the vinyl monomer and maleic acid in the resulting polymer varies depending on the monomer charge ratio and reaction conditions during copolymerization. In the present invention, 10 moles of maleic acid units are used as the olefin-maleic acid copolymer. It is essential to contain at least%. The maleic acid unit in the polymer reacts with the alcohol unit in the aforementioned polyalcohol polymer to form a cross-linked structure, thereby exhibiting a high gas barrier property. When the maleic acid unit in the olefin-maleic acid copolymer is less than 10 mol%, the crosslink density is low, so that the gas barrier property is hardly exhibited.

  Preferred polymers include one or a mixture of methyl vinyl ether-maleic acid copolymer, ethylene-maleic acid copolymer, and isobutylene-maleic acid copolymer.

  The maleic acid unit in the olefin-maleic acid copolymer containing a maleic acid unit used in the present invention is likely to have a maleic anhydride structure in which the adjacent carboxyl group is dehydrocyclized in a dry state, while wet or in an aqueous solution. In the present invention, the ring-opening facilitates the formation of a maleic acid structure. However, in the present invention, these ring-closing and ring-opening are not distinguished and are described as maleic acid.

  The poly (meth) acrylic acid polymer used in the present invention is a polymer of acrylic acid and methacrylic acid, and contains two or more carboxyl groups, and the carboxylic acid polymer and carboxylic acid polymer part thereof. This is a general term including neutralized products. Specifically, it is polyacrylic acid, polymethacrylic acid, a copolymer of acrylic acid and methacrylic acid, or a mixture of two or more thereof, and a partially neutralized product thereof. Moreover, the copolymer of acrylic acid and methacrylic acid, those methyl ester, and ethyl ester can also be used in the range soluble in water. Among these, a homopolymer of acrylic acid or methacrylic acid or a copolymer of both is preferable, and a homopolymer of acrylic acid or a copolymer with acrylic acid, in which acrylic acid is a dominant amount, has oxygen gas barrier properties. Therefore, it is particularly suitable. The number average molecular weight of the poly (meth) acrylic acid polymer is not particularly limited, but is preferably in the range of 2,000 to 250,000.

  The partially neutralized product of poly (meth) acrylic acid can be obtained by partially neutralizing the carboxyl group of poly (meth) acrylic acid with an alkali (that is, forming a carboxylate). Examples of the alkali include alkali metal hydroxides such as sodium hydroxide, lithium hydroxide, and potassium hydroxide, and ammonium hydroxide. The partially neutralized product can be usually obtained by adding an alkali to an aqueous solution of poly (meth) acrylic acid and allowing it to react. Therefore, this partially neutralized product is an alkali metal salt or an ammonium salt. This alkali metal salt contributes to the film formation of the present invention as a structure having a monovalent metal ion. If a partially neutralized product of poly (meth) acrylic acid is used, it is possible to suppress coloring of the molded product due to heat. It is also preferable to use a mixture of poly (meth) acrylic acid and a partially neutralized product of poly (meth) acrylic acid.

  In order to obtain a partially neutralized product of poly (meth) acrylic acid, a desired degree of neutralization can be achieved by adjusting the amount ratio of poly (meth) acrylic acid and alkali. The degree of neutralization of the partially neutralized poly (meth) acrylic acid is preferably selected based on the degree of oxygen gas barrier property of the gas barrier film as the final product. When the degree of neutralization becomes higher than a certain level, the oxygen gas barrier property tends to decrease.

The degree of neutralization can be determined by the formula: degree of neutralization (%) = (N / N ₀ ) × 100. Here, N is the number of moles of neutralized carboxyl groups in 1 g of partially neutralized polycarboxylic acid, and N ₀ is the number of moles of carboxyl groups in 1 g of polycarboxylic acid before partial neutralization.

  When poly (meth) acrylic acid (A) contains a partially neutralized product of poly (meth) acrylic acid, the degree of neutralization of poly (meth) acrylic acid (A) and polyalcohol polymer (B) Affects the rate of ester crosslinking reaction. Specifically, when the degree of neutralization is preferably 20% or less, the rate of ester cross-linking reaction between poly (meth) acrylic acid (A) and polyalcohol polymer (B) is large, which is advantageous from the viewpoint of film production rate. It is. When the degree of neutralization exceeds 20%, the rate of the ester crosslinking reaction between the poly (meth) acrylic acid (A) and the polyalcohol polymer (B) decreases. More preferably, when the degree of neutralization of the partially neutralized product of poly (meth) acrylic acid is 15% or less, it is compared with the case of using an unneutralized product within a wide range of the mixing ratio of both polymer components. Thus, the rate of the ester crosslinking reaction is large, which is advantageous from the viewpoint of the production rate of the film. From the viewpoint of oxygen gas barrier properties, the degree of neutralization of the partially neutralized poly (meth) acrylic acid is preferably 20% or less, more preferably 15% or less.

[Other coating agents (B)]
Another coating agent (B) can be used in order to ensure and improve the adhesiveness of the plastic film which is a base material, and a barrier layer. Therefore, the other coating agent (B) is also referred to as an anchor coating agent (AC agent), and a layer formed from the other coating agent (B) is also referred to as an anchor coating layer (AC layer).

  The other coating agent (B) is formed from various polymers such as urethane, polyester, acrylic, and epoxy, and is not particularly limited, but a urethane coating agent containing a polyol component and a polyisocyanate is preferable.

As the polyol component used for forming the AC agent layer, a polyester polyol is preferable. Examples of polyester polyols include polyester polyols obtained by reacting polyvalent carboxylic acids or their dialkyl esters or mixtures thereof with glycols or mixtures thereof.
Examples of the polyvalent carboxylic acid include aromatic polyvalent carboxylic acids such as isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid, and aliphatic polyvalent carboxylic acids such as adipic acid, azelaic acid, sebacic acid, and cyclohexanedicarboxylic acid.
Examples of the glycol include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, neopentyl glycol, and 1,6-hexanediol.

  The number average molecular weight of these polyester polyols is preferably from 1,000 to 100,000, more preferably from 3,000 to 50,000, and even more preferably from 10,000 to 40,000.

As the polyisocyanate used for forming the AC agent layer,
For example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'- Diphenylmethane diisocyanate, 3,3′-dimethyl-4,4′-biphenylene diisocyanate, 3,3′-dimethoxy-4,4′-biphenylene diisocyanate, 3,3′-dichloro-4,4′-biphenylene diisocyanate, Aromatic polyisocyanates such as 1,5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate,
Tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, hydrogenated xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, Aliphatic polyisocyanates such as 4,4′-dicyclohexylmethane diisocyanate, 3,3′-dimethyl-4,4′-dicyclohexylmethane diisocyanate,
It contains terminal isocyanate groups obtained by reaction with polyfunctional polyisocyanate compounds such as isocyanurates, burettes and allophanates derived from the above polyisocyanate monomers, or trifunctional or higher functional polyol compounds such as trimethylolpropane and glycerin. A polyfunctional polyisocyanate compound etc. can be mentioned. A trifunctional isocyanurate which is a trimer of hexamethylene diisocyanate (hereinafter also referred to as HMDI) is preferable.

  The weight ratio of polyester polyol to polyisocyanate is preferably 10:90 to 99: 1, more preferably 30:70 to 90:10, and even more preferably 50:50 to 85:15.

  The thickness of the AC agent layer can be appropriately determined according to the application to be used, but is preferably 0.01 μm to 10 μm, more preferably 0.01 μm to 5 μm, and 0.01 μm. A thickness of ˜1 μm is particularly preferred. When the thickness is less than 0.01 μm, it is difficult to develop adhesiveness. On the other hand, when the thickness exceeds 10 μm, it is likely to cause difficulty in a production process such as coating.

[Plastic film]
The plastic substrate used in the present invention is a film-like substrate such as a film-like substrate produced from a thermoformable thermoplastic resin by means of extrusion molding, injection molding, blow molding, stretch blow molding or draw molding. It is preferable that
Further, the plastic substrate may be composed of a single layer, or may be composed of a plurality of layers by, for example, simultaneous melt extrusion or other lamination.

  Examples of the thermoplastic resin constituting the plastic substrate include olefin copolymers, polyesters, polyamides, styrene copolymers, vinyl chloride copolymers, acrylic copolymers, polycarbonates, and the like. Polymers, polyesters and polyamides are preferred.

Olefin-based copolymers include low-, medium- or high-density polyethylene, linear low density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene-copolymer, ionomer, ethylene-vinyl acetate copolymer. Coalesce, ethylene-vinyl alcohol copolymer, etc.
Examples of polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate / isophthalate, polyethylene naphthalate,
Examples of polyamides include polyamides such as nylon 6, nylon 6,6, nylon 6,10, and metaxylylene adipamide;
Examples of the styrene copolymer include polystyrene, styrene-butadiene block copolymer, styrene-acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer (ABS resin), and the like.
Examples of the vinyl chloride copolymer include polyvinyl chloride, vinyl chloride-vinyl acetate copolymer,
Examples of the acrylic copolymer include polymethyl methacrylate and methyl methacrylate / ethyl acrylate copolymer.
These thermoplastic resins may be used alone or in combination of two or more.

  Next, the present invention will be described more specifically with reference to examples. In the examples, “parts” and “%” represent “parts by weight” and “% by weight”, respectively.

<Oxygen permeability>
Each laminate was sprayed with water containing a metal compound having a valence of 2 or more together with water vapor, and was transferred to a wet and heat-treated tank under various conditions. Using -TRAN TWIN, oxygen permeability at 25 ° C. and 80% RH was determined. Specifically, oxygen gas and nitrogen gas (carrier gas) humidified at 25 ° C. and 80% RH were used. The oxygen permeability (ml / m ² · 24Hr · 1 atm) was indicated as “◯” when less than 3 ml, “Δ” when more than 3 ml but less than 10 ml, and “×” when more than 10 ml.

[Production Example 1]
As a polymer (A), polyvinyl alcohol (manufactured by Unitika Chemical Co., Ltd., UF040G, saponification degree 98.4%, average polymerization degree 400) is dissolved in pure water to obtain a solid content of 10%. 1 equivalent of sodium hydroxide was added and stirred at 70 ° C. for 3 hours to obtain an aqueous solution. The saponification degree of the polyvinyl alcohol obtained by this operation was 99.9%.
Separately, an ethylene-maleic acid alternating copolymer (manufactured by ALDRICH, weight average molecular weight 100,000) is used as the polymer (B), and 10 mol% of hydroxylation relative to the carboxyl group of the ethylene-maleic acid alternating copolymer. It melt | dissolved in the water containing sodium, and it was set as the aqueous solution of 10% of solid content.
The polymer (A) aqueous solution and the polymer (B) aqueous solution were mixed and stirred so that the solid content ratio of each polymer was 30/70, and a gas barrier layer forming coating agent (1) solution having a solid content of 10% was obtained. .

[Production Example 2]
Using 25% aqueous solution of polyacrylic acid (Wako Pure Chemical Industries, Ltd. (8000-12000 centipoise at 30 ° C., weight average molecular weight 150,000)) as polymer (C), partially neutralized with sodium hydroxide to 10% The mixture was neutralized and diluted with pure water to obtain a solid content of 10%.
In the same manner as in Production Example 1, the polymer (A) aqueous solution and the polymer (C) aqueous solution were mixed and stirred so that the solid content ratio of each polymer was 30/70, and the coating for forming a gas barrier layer having a solid content of 10%. Agent (2) solution was obtained.

[Production Example 3]
As a polymer (D), a separable four-necked flask was equipped with a temperature control regulator, a cooling tube, and a stirring device, charged with 70 parts of pure water, heated to 80 ° C. and purged with nitrogen in the reaction vessel, and then glycerin methacrylate from the dropping tube. (Hereinafter GLM) (Nippon Yushi Co., Ltd., “Blemmer GLM”) 30 parts, pure water 20 parts, azo compound (Wako Pure Chemical Industries, Ltd. “V-50”) 0.3 parts 1 hour It was dripped over. After completion of the dropwise addition, the reaction was further continued for 3 hours. After completion of the polymerization, 179.7 parts of pure water was added with sufficient stirring to obtain a polyglycerol methacrylate aqueous solution having a solid content of 10% by weight.
In the same manner as in Production Example 1, the polymer (D) aqueous solution and the polymer (B) aqueous solution are mixed and stirred so that the solid content ratio of each polymer is 30/70, and stirred to form a 10% solid content gas barrier layer coating. Agent (3) solution was obtained.

[Production Example 4]
As a polymer (E), a separable four-necked flask was equipped with a temperature control regulator, a cooling tube, and a stirring device, charged with 89.7 parts of pure water, heated to 80 ° C. and purged with nitrogen in the reaction vessel. 2 parts of methacrylate (hereinafter referred to as GLM) (manufactured by NOF Corporation, “Blemmer GLM”), 18 parts of acrylic acid (hereinafter referred to as AA), 25 parts of pure water, “V” manufactured by Wako Pure Chemical Industries, Ltd. −50 ”) 0.24 part was added dropwise over 1 hour, and after completion of the addition, the reaction was continued for 3 hours to obtain a GLM-AA copolymer aqueous solution having a solid content of 15%.
Using an aqueous polymer (E) solution, 5 mol% of the carboxyl groups were neutralized with sodium hydroxide and diluted with pure water to obtain a coating agent (4) solution for forming a gas barrier layer having a solid content of 10 wt%.

[Production Example 5] AC agent Polyester (manufactured by Toyobo Co., Ltd., Byron 200 (Tg 67 ° C.), Mn = 17000) was dissolved in a toluene / MEK mixed solvent. To this solution, polyisocyanate (manufactured by Sumitomo Chemical Co., Ltd., Sumidur 3300) was adjusted so that the weight ratio of polyester to polyisocyanate was 60/40 to obtain a mixed solution. Dibutyltin laurate 1% MEK solution, MEK and ethyl acetate were mixed with this mixed solution to obtain an anchor coat composition (= an anchor coat layer forming composition) having a solid content of about 14%.

[Production Example 6]
Using a gravure coater, apply the anchor coating agent obtained in Production Example 5 to one side of a stretched PET film (thickness 12 μm, melting point 264 ° C.), and introduce the solvent into the drying chamber controlled at 80 ° C. Then, an anchor coat layer of 0.2 μm was formed.
Next, the coating agent (1) for forming the gas barrier layer obtained in Production Example 1 was applied onto the formed anchor coat layer, introduced into a drying chamber controlled at 90 ° C., water was removed, and then the temperature was increased to 160 ° C. Baking was performed by passing through a controlled baking chamber for 2 minutes to obtain a gas barrier laminate (1-1) which was insoluble in hot water and had a gas barrier layer having a thickness of 2.2 μm.

[Production Example 7] to [Production Example 9]
In the same manner as in Production Example 6 except that gas barrier layer-forming coating materials (2) to (4) were used instead of the gas barrier layer-forming coating agent (1) used in Production Example 6, a gas barrier laminate ( 1-2) to (1-4) were obtained.

[Production Example 10]
Using a gravure coater, the gas barrier layer-forming paint (1) obtained in Production Example 1 was applied to one surface of a stretched nylon 6 film (thickness 15 μm, melting point 220 ° C.) and controlled at 90 ° C. After removing water by introducing it into a gas barrier laminate (1) having a gas barrier layer having a thickness of 2.2 μm which is insoluble in hot water and baked in a baking chamber controlled at 160 ° C. for 2 minutes. -5) was obtained.

[Production Example 11]
Gas barrier laminate (1-6) in the same manner as in Production Example 10 except that the gas barrier layer forming coating agent (2) was used instead of the gas barrier layer forming coating agent (1) used in Production Example 10. Got.

[Example 1]
Wet heat treatment was performed using the wet heat treatment apparatus shown in FIG.
After attaching the gas barrier laminate (1-4) obtained in Production Example 9 to the unwinding device 2 in FIG. 1, continuously transporting the laminate into the wet heat treatment tank and continuously performing the wet heat treatment The moisture in the gas barrier laminate was removed by passing through the drying device 4 set at 110 ° C. in 1 minute, and the take-up device 3 obtained a take-up gas barrier laminate (2-4). At this time, water vapor having a pressure of 2.7 atm and a temperature of 130 ° C. was sprayed from the spray port 6 to the wet heat treatment tank. The water containing the divalent or higher metal compound sprayed into the wet heat treatment tank from the spray port 5 together with water vapor contains 100 ppm of CaCO ₃ and Ca (OH) ₂ in total, and the temperature in the wet heat treatment tank is 90 ° C. The relative humidity was 100% and the wet heat treatment time was 30 minutes.

[Example 2]
Using the gas barrier laminate (1-1) obtained in Production Example 6 instead of the gas barrier laminate (1-4) obtained in Production Example 9 in Example 1, the temperature in the wet heat treatment tank was set to 90. A gas barrier laminate (2-1) was obtained in the same manner as in Example 1 except that the temperature, the relative humidity was 90%, and the wet heat treatment time was 60 minutes.

[Example 3] to [Example 5]
Instead of the gas barrier laminate (1-4) obtained in Production Example 9 in Example 1, the gas barrier laminate (1-3) obtained in Production Example 8 and the gas barrier laminate obtained in Production Example 10, respectively. Body (1-5), using the gas barrier laminate (1-6) obtained in Production Example 11,
A gas barrier laminate (2-3) and a gas barrier laminate (2) were prepared in the same manner as in Production Example 1 except that the temperature in the wet heat treatment tank was 90 ° C., the relative humidity was 100%, and the wet heat treatment time was 30 minutes. -5) A gas barrier laminate (2-6) was obtained.

[Example 6]
Using the gas barrier laminate (1-2) obtained in Production Example 7 instead of the gas barrier laminate (1-4) obtained in Production Example 9 in Example 1, the temperature in the wet heat treatment tank was set to 95. A gas barrier laminate (2-2) was obtained in the same manner as in Example 1 except that the temperature, the relative humidity was 100%, and the wet heat treatment time was 15 minutes.

[Comparative Example 1], [Comparative Example 2]
The gas barrier laminate (1-1) obtained in Production Example 6 and the gas barrier laminate (1-5) obtained in Production Example 10 were used as they were without any wet heat treatment.

  Table 2 shows the results of measuring the oxygen permeability of the obtained gas barrier laminate.

One of the aspects of the manufacturing method of the gas-barrier laminated body of this invention is shown. One of the other aspects of the manufacturing method of the gas-barrier laminated body of this invention is shown. One of the other aspects of the manufacturing method of the gas-barrier laminated body of this invention is shown.

Explanation of symbols

1: Humidity heat treatment tank 2: Unwinding device 3: Winding device 4: Drying device 5: Spraying port for water containing a metal compound having a valence of 2 or more 6: Steam spraying port 7: Gas barrier laminate (1)
8: Gas barrier laminate (2)

Claims (10)

The gas barrier layer-forming coating agent (A) is applied directly on at least one surface of the plastic film or on the coating layer of another coating agent (B) provided on at least one surface of the plastic film, and heat-treated. The gas barrier laminate (1) is sprayed with water containing a divalent or higher metal compound together with water vapor under atmospheric pressure, and is in a high temperature and high humidity state at a temperature of 60 ° C. or higher and 100 ° C. or lower and a relative humidity of 80% or higher. A method for producing a gas barrier laminate (2), comprising carrying out a wet heat treatment by transporting through a wet heat treatment tank. The method for producing a gas barrier laminate according to claim 1, wherein the gas barrier layer forming coating agent (A) contains a polyalcohol polymer and a polycarboxylic acid polymer. The method for producing a gas barrier laminate (2) according to claim 2, wherein the divalent or higher-valent metal compound can react with a hydroxyl group or a carboxyl group. The gas barrier laminate according to claim 2 or 3, wherein the divalent or higher valent metal compound contains at least one of a divalent or higher valent metal hydroxide, carbonate, acetate, and phosphate. 2) Production method. The method for producing a gas barrier laminate (2) according to any one of claims 3 to 4, wherein the divalent or higher-valent metal is any one of Mg and Ca or a mixture thereof. The method for producing a gas barrier laminate (2) according to any one of claims 2 to 5, wherein the polyalcohol polymer is polyvinyl alcohol or saccharide. The method for producing a gas barrier laminate (2) according to any one of claims 2 to 6, wherein the polycarboxylic acid polymer is a poly (meth) acrylic acid polymer. The gas barrier laminate according to any one of claims 2 to 6, wherein the polycarboxylic acid polymer is a polymer obtained by addition polymerization of a monomer having a dibasic acid having a carbon-carbon double bond as an essential component. Manufacturing method of body (2). 9. The polymer obtained by addition polymerization of a monomer containing a dibasic acid having a carbon-carbon double bond as an essential component is an olefin-maleic acid copolymer or a polyitaconic acid polymer. A method for producing a gas barrier laminate (2). The olefin-maleic acid copolymer is at least one selected from the group consisting of an ethylene-maleic acid copolymer, a methyl vinyl ether-maleic acid copolymer, and an isobutylene-maleic acid copolymer. The manufacturing method of the gas-barrier laminated body (2) of Claim 9.

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