JPH0867786A - Water-base composition and laminate - Google Patents

Abstract

PURPOSE: To improve the stability, gas barrier properties, smell retention, and resistances to oil and chemicals and increase the concn. of a water- -base compsn. by compounding a specific water-base ethylene-vinyl alcohol copolymer dispersion with an inorg. oxide. CONSTITUTION: A water-base ethylene-vinyl alcohol copolymer (EVOH) dispersion having a solid content of 99.95-3wt.% is obtd. by mixing water with a solvent soln. of 100 pts.wt. EVOH having an ethylene content of 15-65mol% in the presence of 2-200 pts.wt. saponified ethylene-vinyl ester copolymer having an ethylene content of 10-70mol% and a degree of saponification of 80mol% or higher as the dispersion stabilizer to thereby reduce the particle size of the EVOH to 3μm or lower and then removing the solvent. The dispersion is compounded with 0.65-97wt.% inorg. oxide having a number average particle size of 3μm or lower to give a water-base compsn., which is applied to the surface of a substrate and dried and thermally treated at 30-180 deg.C for 5sec to 10min to form a coating film on the surface. Thus treated substrates are laminated to each other with an adhesive resin layer sandwiched between them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous composition containing an ethylene-vinyl alcohol copolymer aqueous dispersion and an inorganic oxide, and a food having a coating layer obtained by coating and drying the aqueous composition. The present invention relates to a laminate having excellent gas barrier properties, which is used for packaging films, containers and the like.

[0002]

2. Description of the Related Art Saponification products of ethylene-vinyl ester copolymers, particularly ethylene-vinyl alcohol copolymers (abbreviated as EVOH) obtained by saponifying ethylene-vinyl acetate copolymers, have a gas barrier property against oxygen and the like and a protective property. Fragrance and oil resistance
Since it has extremely excellent chemical resistance, it is suitable for use as a packaging film in various packaging fields, especially for molded products such as food packaging films, sheets and containers, and for protective coating of metal surfaces, paper, wood, etc. It is attracting attention as a material.

In particular, films, sheets, laminates, hollow containers and the like for food packaging, which are required to prevent the contents from being oxidized or to retain the scent, are required to have a high gas barrier property. Further, for vinyl chloride wallpaper, vinyl chloride leather, sheets, etc. made of soft vinyl chloride, a coating material for preventing bleeding of a plasticizer is required. Therefore, it is widely practiced that EVOH having excellent gas barrier property, aroma retaining property, and oil / chemical resistance is provided in the inner layer, the outer layer, or the intermediate layer to highly satisfy these required performances.

Generally, as a method of forming an EVOH layer, a method by melt extrusion or injection molding, a method of laminating an EVOH film, etc. are widely practiced.
On the other hand, a method of applying a solution of EVOH or an aqueous dispersion and drying it has been proposed. This method is noted because it is possible to form a film having a relatively thin film thickness and that a film having a complicated shape such as a hollow container can be easily formed.

However, in the method of applying a solution of EVOH, it is basically difficult to use a solution having a high concentration due to its high viscosity, and the solvent is an organic solvent such as dimethyl sulfoxide or a mixed solvent of a large amount of alcohol and water. In the process of forming a film, there is a problem in that the work environment is deteriorated due to volatilization of the organic solvent and an apparatus for collecting the organic solvent is required, which is economically disadvantageous. In contrast, EVOH
The method of applying the aqueous dispersion of is considered to be advantageous because the solvent is aqueous and is considered to be advantageous from the viewpoint of the above-mentioned working environment and economy.

As an aqueous dispersion of EVOH, a conventional E
What was obtained by emulsifying and dispersing VOH in the presence of an ordinary surfactant or an ordinary polymer protective colloid, for example, polyethylene oxide, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, etc. is disclosed in JP-A-54-101844 and JP-A-56- 61430 and the like. However, there is no description about blending an inorganic oxide here.

The incorporation of an inorganic filler such as montmorillonite or talc into an aqueous dispersion of EVOH is described in JP-A-6-57066. However, when an inorganic filler such as montmorillonite is blended, the gas barrier property is not sufficient under a high humidity of 90% RH or more, especially under 100% RH. This is clear from Comparative Examples 2 to 4 described later.

[0008]

The present invention was devised in order to solve the above-mentioned drawbacks of the prior art. It has excellent stability during storage or use and is capable of increasing the concentration. The gas barrier property of the film obtained by further coating and drying, especially under high humidity of 90% RH or more, especially 1
EVOH with excellent gas barrier properties under 00% RH
It is intended to provide an aqueous composition.

[0009]

The above objects are achieved by providing an aqueous composition comprising an EVOH aqueous dispersion and an inorganic oxide.

Hereinafter, the present invention will be described specifically. In the present invention, the EVOH aqueous dispersion is an aqueous dispersion containing EVOH as a dispersoid, and is preferably an aqueous dispersion containing EVOH as a dispersoid and EVOH having an ionic group as a dispersion stabilizer. An aqueous dispersion containing EVOH having a group as a dispersoid can be mentioned. Next, a suitable aqueous dispersion used in the present invention, that is, an aqueous dispersion containing EVOH as a dispersoid and EVOH having an ionic group as a dispersion stabilizer will be described.

The ionic group of EVOH having an ionic group used as a dispersion stabilizer includes a group which dissociates in water and exhibits ionicity, that is, an anionic group, a chaotic group and an amphoteric group. From the viewpoint of the effect of stabilizing dispersion, an anionic group is preferable.

Examples of the anionic group include groups such as sulfonic acid, sulfonic acid salt, sulfuric acid ester, sulfuric acid ester salt, phosphoric acid, phosphoric acid salt, carboxylic acid and carboxylic acid salt, and these acids and bases are contained at the same time. It may be. A sulfonic acid, a carboxylic acid, or the base is preferable because of its excellent dispersion stabilizing effect, and a sulfonic acid or the base is particularly preferable.

Examples of the cationic group include groups such as amines and salts thereof, quaternary ammonium salts, phosphonium salts and sulfonium salts. Particularly, a quaternary ammonium salt is preferable because it has a large dispersion stabilizing effect. Examples of the amphoteric group include aminocarboxylic acid salts (betaine type), aminosulfonic acid salts (sulfobetaine type), aminosulfate salts (sulfate betaine type) and the like.

The content of the ionic group is appropriately selected within a range having a dispersion stabilizing effect, but from the viewpoint of the dispersion stabilizing effect, it is 0.0 with respect to the EVOH component unit in the ion-modified EVOH.
5 to 50 mol% is desirable. More preferably 0.1 to
30 mol%, especially 0.2 to 15 mol%, and even 0.2
-10 mol% is desirable. If it is less than 0.05 mol%, the effect of stabilizing dispersion is small, and if it exceeds 50 mol%, the water resistance and gas barrier property of the film obtained by coating and drying the aqueous dispersion become poor, which is not preferable. Ion-modified EVOH
There is no problem to include other units containing no ionic group in a range that does not significantly impair the dispersion stabilizing effect.

The composition of the EVOH component in the ion-modified EVOH is preferably such that the ethylene content is 10 to 70 mol% and the saponification degree is 80 mol% (the saponification degree in the present invention indicates the saponification degree of vinyl ester units) or more. . The preferred range of ethylene content is 12 mol% or more, more preferably 1
It is 5 mol% or more, and further 20 mol% or more. The upper limit is preferably 65 mol% or less, more preferably 60 mol% or less. The preferable degree of saponification is 90 mol% or more, and further 95 mol% or more. E of dispersoid
The ethylene content and the degree of saponification of VOH will be described later, but those close to it are preferable in terms of the particle dispersion stabilizing effect. More preferably, almost the same ethylene content and degree of saponification are desired. The degree of polymerization of the ion-modified EVOH is not particularly limited, but is preferably 100 or more from the viewpoint of the effect of stabilizing dispersion. The upper limit of the degree of polymerization is not particularly limited, but if it is too large, the solution viscosity is high and the dispersion performance is deteriorated, so that the value is usually 2000 or less. Here, the degree of polymerization of the ion-modified EVOH is determined from the intrinsic viscosity measured at 30 ° C. in a water / phenol mixed solvent (weight ratio 15/85) containing 1 mol / liter ammonium thiocyanate.

The vinyl ester can be copolymerized with ethylene such as vinyl formate, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl trifluoracetate acetate, vinyl pivalate, etc., and is vinyl alcohol by saponifying the copolymer. Although convertible monomers can be used, vinyl acetate is particularly preferred.

With respect to the structure of the ion-modified EVOH, a so-called random ionic group is preferably used, and there is no particular limitation on the production method thereof.

For example, a method of radically copolymerizing a monomer containing an ionic group with ethylene and a vinyl ester, and then saponifying the vinyl ester unit in the obtained copolymer to convert it into a vinyl alcohol unit, which is an EVOH polymer. A method of introducing an ionic group-containing component by addition reaction, or after adding an ionic group-containing component to an ethylene-vinyl ester copolymer, saponifying the vinyl ester unit in the copolymer to vinyl alcohol. Examples include a method of converting into units. The polymerization, saponification and addition reaction can be carried out by known methods.

As the ionic group-containing monomer copolymerizable with ethylene and vinyl ester, a radical homopolymerizable or radical copolymerizable monomer having an ionic group or a group convertible to an ionic group can be used. An example is shown below.

Ο Anionic group-containing monomer As the sulfonic acid anionic group-containing monomer, 2-
(Meth) acrylamido-2-methylpropane sulfonate sodium (meth) acrylamide sulfonate monomer, potassium styrene sulfonate such as styrene sulfonate monomer, sodium allyl sulfonate allyl sulfonate monomer, Further, vinyl sulfonates such as sodium vinyl sulfonate, ammonium salt monomers thereof, and acid monomers thereof may be mentioned. Also, these sulfonic acid esters can be used by converting the ester to a salt or acid after polymerization.

Examples of the carboxylic acid anionic group-containing monomer include mono-, di-, and polycarboxylic acid vinyl monomers such as acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, and fumaric acid, and alkali metal salts and ammonium salts thereof. To be Also, these esters can be used because the ester group can be converted into its salt or acid after polymerization.

Ο Cationic group-containing monomer An amino group-containing (meth) acrylamide monomer such as aminopropyl acrylamide or methacrylamide, or an amino group-containing (meth) acrylate such as aminoethyl acrylate or methacrylate or a salt thereof has good polymerizability. preferable. Particularly, the quaternary salt thereof is preferable because the polymer is not colored. For example, trimethylacrylamidopropylammonium chloride, triethylmethacryloylethylammonium bromide and the like.

These monomers can be used alone or in combination.

As the addition reaction to EVOH, Michael addition reaction of an ionic group-containing vinyl monomer to its hydroxyl group, acetalization or ketalization with an ionic group-containing aldehyde or ketone, addition of an ionic group-containing epoxy compound, Examples thereof include addition of carboxylic acid anhydride and esterification with sulfuric acid. In addition, introduction of an ionic group-containing monomer having a low radical homopolymerizability such as maleic anhydride by a radical addition reaction may be mentioned.

Also, it is produced by subjecting an ethylene-vinyl ester copolymer to a radical addition reaction of a monomer having a low radical homopolymerizability such as maleic anhydride, and then saponifying to convert the vinyl ester unit into vinyl alcohol. It is also possible to do so.

EVOH, which is a dispersoid polymer, comprises ethylene and vinyl acetate, vinyl formate, vinyl propionate,
An ethylene-vinyl alcohol copolymer obtained by copolymerizing and saponifying vinyl esters such as vinyl benzoate, vinyl trifluoroacetate and vinyl pivalate, particularly vinyl acetate, having an ethylene content of 15 to 65 mol%, The saponification degree is preferably 90 mol% or more. If the ethylene content is less than 15 mol%, the stability of the aqueous dispersion will be poor, and if it exceeds 65 mol%, the gas barrier property will be poor, such being undesirable.

From the viewpoint of stability of the aqueous dispersion and gas barrier properties, the ethylene content is preferably 20 to 55 mol%. If the saponification degree is less than 90 mol%, the gas barrier property becomes insufficient, so it is necessary to use a gas having a saponification degree of 90 mol% or more. The higher the degree of saponification, the higher the gas barrier property, and it is preferably 95 mol% or more, and more preferably 97 mol% or more.

The EVOH having a dispersoid having an extremely low degree of polymerization is usually 40 because the strength of the formed film is unfavorably low.
0 or more, preferably 700 or more are used. The higher the degree of polymerization is, the more advantageous it is to use by coating as an aqueous dispersion, and usually, it can be used up to about 5000.
Here, the degree of polymerization of the dispersoid is determined from the intrinsic viscosity measured at 30 ° C. in a water / phenol mixed solvent (weight ratio 15/85). If necessary, 5 mol% or less of a copolymerizable monomer other than ethylene and vinyl ester may be copolymerized.

The amount of ion-modified EVOH used as a dispersion stabilizer is appropriately selected in consideration of the type and content of ionic groups, but is 2 to 2 per 100 parts by weight of EVOH of the dispersoid.
00 parts by weight, preferably 3 to 100 parts by weight, more preferably 5 to 50 parts by weight. If the amount is too small, the dispersion stability will be poor, and if it is too large, the gas barrier properties of the formed film will be extremely insufficient, which is not preferable.

There is no limitation on the method of dispersing EVOH which is a dispersoid using ion-modified EVOH as a dispersion stabilizer, and known methods can be used.

For example, a solution of EVOH, which is a dispersoid, is brought into contact with water, which is a non-solvent for EVOH, in the coexistence of an ion-modified EVOH, which is a dispersion stabilizer, and EVOH particles are mixed with 3 times.
An aqueous dispersion can be obtained by precipitating fine particles having a size of not more than μm, preferably not more than 2 μm, and most preferably not more than 1 μm, and then removing the solvent. Here, the diameter of the fine particles is the number average particle diameter.

The solid content concentration is preferably 10% by weight.
Or more, more preferably 15% by weight or more, most preferably 20
It is more than weight%. There is no particular upper limit to the solid content concentration, but if the concentration is too high, the storage stability of the aqueous dispersion may be somewhat poor.
The following is preferable, more preferably 50% by weight or less, and most preferably 40% by weight or less.

Examples of the solvent include methyl alcohol,
Ethyl alcohol, propyl alcohol, butyl alcohol and other monohydric alcohols, ethylene glycol, propylene glycol and other dihydric alcohols, glycerin and other 3
Dihydric alcohol, phenol, phenols such as cresol, amines such as ethylenediamine and trimethylenediamine, dimethylsulfoxide, dimethylacetamide,
N-methylpyrrolidone and the like, or hydrates thereof and the like can be used alone or in admixture of two or more. Particularly preferred solvents are alcohol-water mixed solvents such as water-methyl alcohol, water-normal propyl alcohol, water-isopropyl alcohol and the like.

Ion-modified EVOH is a dispersoid EVO
It can be made to coexist in the H solution or in the non-solvent water, or both, but it is preferable to coexist in the EVOH solution.

The organic solvent in the solvent can be removed by an appropriate method such as an evaporation method, an extraction method or a dialysis method. It is desirable that the degree of removal is high, but a small proportion of the organic solvent may be left in consideration of economical efficiency.

As another method, after the EVOH of the dispersoid and the ion-modified EVOH of the dispersion stabilizer are dissolved by heating in a solvent system that dissolves at a high temperature but becomes insoluble at a low temperature,
A method of precipitating and dispersing as fine particles by cooling the solution can also be adopted. Then, the solvent is replaced with water to form an aqueous dispersion.

As a solvent system which dissolves at a high temperature and precipitates at a low temperature, the above-mentioned alcohols alone or a mixed solvent with water can be used.

Still another method is ion-modified EVO.
A method in which a solution of EVOH coexisting with H is brought into contact with a non-solvent or cooled to filter out particles precipitated and dispersed, and the particles are dispersed in water in the coexistence of ion-modified EVOH is also possible.

The preferred method for producing an aqueous dispersion in the present invention is to disperse EVOH in a dispersoid and EVOH having an ionic group as a dispersion stabilizer in a common solvent of them, for example, a mixed solvent of water-alcohol at a temperature of Dissolve at 50-75 ° C to give a solution, then cool (temperature -10-30 ° C), E
VOH particles are precipitated and dispersed (emulsified), and then under reduced pressure (temperature 10 to 30 ° C., pressure 10 to 150 mmH).
An example is a method of removing an alcohol in g) and further removing a desired amount of water to obtain an aqueous dispersion having a desired solid content concentration.

The EVOH having an ionic group is, as described above, an EVO in which an ionic group is randomly introduced.
Although H is preferable, EVOH having an ionic group at the terminal and optionally a crosslinkable group can also be used. Here, EVOH having an ionic group at the terminal is
For example, a compound having an active group such as an alcohol, an aldehyde or a thiol having a sulfonic acid group or a salt thereof, a carboxylic acid group or a salt thereof, an ammonium group or the like is allowed to coexist as a chain transfer agent, and ethylene and a vinyl ester are copolymerized. , Then saponifying vinyl ester units, and sulfonic acid groups or salts thereof at the end of EVOH,
It is produced by a method of introducing a compound containing a carboxylic acid group or a salt thereof, an ammonium group or the like by a chemical reaction. Among these methods, as a method of economically and efficiently introducing an ionic group at the terminal to obtain EVOH exhibiting excellent stability as an aqueous dispersion, a sulfonic acid group or a salt thereof, a carboxylic acid A method in which ethylene and a vinyl ester are copolymerized in the presence of a thiol containing a group or a salt thereof, an ammonium group, and the like and then saponified is preferable.

Next, another preferred aqueous dispersion used in the present invention, that is, an aqueous dispersion containing EVOH having an ionic group as a dispersoid will be described. In this case, the EVOH having an ionic group, particularly the EVOH having an ionic group introduced randomly, is preferably one having a sulfonic acid group or a salt thereof as the above-mentioned ionic group. When the EVOH having these ionic groups is used as the dispersoid, the suitable ethylene content, saponification degree and degree of polymerization are the same as the ethylene content, saponification degree and degree of polymerization of the EVOH used as the dispersoid.

In the present invention, EVO having an ionic group used as the above-mentioned dispersion stabilizer or dispersoid.
As H, a block or graft copolymer of an EVOH component and a component having an ionic group can also be used. In addition to the above-mentioned EVOH aqueous dispersion, an aqueous dispersion using a block or graft copolymer of an EVOH component and a polyvinyl alcohol component as a dispersion stabilizer or dispersoid, a block or graft copolymer of an EVOH component and a polyether component. It is also possible to use an aqueous dispersion in which is a dispersion stabilizer or dispersoid.

By mixing an inorganic oxide in the thus obtained aqueous dispersion, an aqueous composition having an excellent gas barrier property is obtained especially under high humidity of 90% RH or more, and especially under 100% RH. be able to. Examples of the inorganic oxide include silica, titanium oxide, alumina, iron oxide, zinc oxide, magnesium oxide, tin oxide, copper oxide, nickel oxide, tungsten oxide, zirconium oxide and the like. The size of these inorganic oxides is 3 μm or less, preferably 2 μm or less, and most preferably 1 μm or less in terms of number average particle diameter from the viewpoint of stability in standing in an aqueous dispersion and homogeneous mixing with EVOH. Is desirable.

The inorganic oxide may be added during the production of the EVOH aqueous dispersion or after the production thereof.
For more homogeneous mixing, it is preferable to add during production. It is considered that when added during the production, the inorganic oxide forms the core of the particles and EVOH forms the outer shell of the composite particles, so that the particles can be more homogeneously mixed. In obtaining an aqueous composition comprising an EVOH aqueous dispersion and the inorganic oxide,
The inorganic oxide is preferably in a water-based or alcohol-based colloidal state. The inorganic oxide may be used alone or in combination of two or more kinds.

The method for obtaining an aqueous composition comprising EVOH and an inorganic oxide is not particularly limited, but for example, an EVOH solution prepared by dissolving it in an alcohol-water solvent at high temperature is mixed with an inorganic oxide dispersed in alcohol. Then, EVOH is precipitated in the form of fine particles by cooling and then the alcohol is removed, a method of removing the alcohol by mixing the EVOH solution described above into an aqueous dispersion of an inorganic oxide with stirring, and an EVOH aqueous dispersion. And a method of mixing the inorganic oxide aqueous dispersion with stirring.

The blending ratio of EVOH (resin solid content) and inorganic oxide in the aqueous composition of the present invention is EVOH.
In the range of 0.05 to 97% by weight of inorganic oxide, preferably 0.1 to 80% by weight, and more preferably 1 to 50% by weight with respect to the solid content concentration of 99.95 to 3% by weight. To be elected. When the proportion of the inorganic oxide is less than 0.05% by weight,
It is not preferable because the effect of improving the gas barrier property of the coating layer obtained by coating and drying the aqueous composition is low. On the other hand, 9
If the amount exceeds 7% by weight, the strength of the coating layer decreases, which is not preferable.

The aqueous composition of the present invention contains hydroxypropyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, carboxymethyl ethyl cellulose, for the purpose of improving the affinity between EVOH and the inorganic oxide.
A polymeric protective colloid such as polyethylene oxide, polyvinyl alcohol or pullulan may be blended in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the inorganic oxide. The composition is
Before or after atomizing the dispersoid EVOH,
It is more effective before being made into fine particles.

The aqueous composition of the present invention contains alkali metal compounds such as sodium hydroxide, sodium chloride, sodium acetate, sodium sulfate and sodium nitrate, calcium hydroxide, calcium chloride, calcium acetate and calcium sulfate for the purpose of decreasing the viscosity. , Alkaline earth metal compounds such as calcium nitrate, other electrolytes EVOH10
You may mix | blend 0.01-0.5 weight part with respect to 0 weight part. The compounding may be performed before or after atomizing the EVOH of the dispersoid.

The aqueous composition of the present invention is particularly useful as a coating material for forming a film having an excellent gas barrier property on a substrate, but by utilizing its excellent mechanical performance and chemical performance, it can be used in other applications. For example, it can be used in a wide range of applications, such as powder-mist drying to form fine-particle powders, and binders and vehicles for paints and adhesives.

It is possible to add usual surfactants and protective colloids to the aqueous composition of the present invention, if necessary, within a range not hindering the purpose of the present invention. In addition, aqueous dispersions of other resins, stabilizers against light or heat, pigments, lubricants, antifungal agents or ethylene glycol, glycerin,
A film-forming aid such as pentaerythritol may be added.

The method of applying the aqueous composition of the present invention onto the surface of a substrate includes discharge from a casting head, roll coating, air knife coating, gravure roll coating,
Examples are any means such as doctor roll coating, doctor knife coating, curtain flow coating, spraying, dipping, and brush coating. Dry the substrate coated in this way
Examples of the heat treatment method include a dry heat treatment method such as an infrared irradiation method and a hot air drying method. These infrared irradiation, hot air drying and the like may be used alone,
They can also be used together. The temperature of the drying / heat treatment is preferably 30 to 180 ° C, and the lower limit is preferably 50 ° C or higher, and most preferably 80 ° C or higher.
The drying / heat treatment time is preferably 5 seconds to 10 minutes, more preferably 1 to 5 minutes. Conditions during drying and heat treatment,
For example, the temperature may be increased or decreased, for example, the treatment may be performed at a low temperature at first and then the temperature may be gradually increased. By performing such drying and heat treatment, a film having an excellent gas barrier property is formed on the surface of the base material.

It is preferable to apply an adhesive agent to the surface of the base material in advance by a dry lamination method or the like, that is, to perform anchor coating. The dry lamination adhesive is not particularly limited as long as it has a sufficient interlayer adhesive force. For example, polyurethane-based and polyester-based adhesives for dry lamination can be mentioned. Further, the surface of the base material may be subjected to corona discharge treatment, sputtering treatment, high frequency treatment, fire treatment, chromic acid treatment, solvent etching treatment, or a combination of these.

Examples of the base material include the following. A film of a thermoplastic resin, for example, a biaxially stretched film containing a homopolymer of propylene as a main component, a homopolymer of ε-caprolactam and a diamine component such as hexamethylenediamine and metaxylylenediamine, and adipic acid as a main raw material. Biaxially stretched film containing nylon as the main component, biaxially stretched film containing ethylene glycol and terephthalic acid or naphthalene dicarboxylic acid as the main raw materials, polyester as the main component, and carbonic acid derivatives such as bisphenol A and phosgene as the main raw materials. A film made of polycarbonate, a biaxially stretched film made of polyvinylidene chloride obtained by copolymerizing vinyl chloride, acrylonitrile, (meth) acrylic acid ester, etc., with vinyl chloride as the main raw material, a homopolymer of styrene and styrene. Raw material and butadiene, acrylonitrile, biaxially oriented film of polystyrene by copolymerizing like, include rolling or biaxially oriented high density polyethylene film or the like.

Various molded articles (sheets, cups, bottles, etc.) other than the above films are also mentioned as preferable ones, and fiber aggregates (paper, non-woven fabric, woven cloth, fibrous casing, etc.), inorganic materials (cement, etc.) ), Metal, polyvinyl chloride resin wallpaper, photographic paper and the like.

The thickness of the coating after coating, drying and heat treatment of the aqueous composition of the present invention is preferably 0.5 to 15 μm, more preferably 1 to 10 μm, most preferably 2 to 6 μm. is there.

Further, there is no particular limitation on the constitution of the laminate containing the substrate and the film-forming layer comprising the aqueous composition of the present invention obtained by the above-mentioned method, and the laminate may be laminated by a conventionally known method to form a multilayer. be able to. Examples of these methods include an extrusion lamination method and a dry lamination method.

For laminating these layers, a usual method of laminating an adhesive resin layer between the layers is adopted. The adhesive resin is not particularly limited as long as it does not cause delamination at a practical stage, and is not particularly limited, for example, an unsaturated carboxylic acid or an anhydride thereof is an olefin polymer (for example, polyethylene, polypropylene,
Examples thereof include modified olefin-based polymers containing a carboxyl group, which are obtained by chemically (for example, addition ability or graft reaction) bonding to a polyolefin such as polybutene or a copolymer mainly composed of olefins. Specifically, one selected from maleic anhydride graft modified polyethylene, maleic anhydride graft modified polypropylene, maleic anhydride graft modified ethylene-ethyl acrylate copolymer, maleic anhydride graft modified ethylene-vinyl acetate copolymer or A mixture of the two may be mentioned. Further, glycidyl acrylate, a polymerizable unsaturated compound having a glycidyl group such as glycidyl methacrylate, a polymerizable unsaturated compound having a methacryloxypropyltrimethoxysilane group, a glycidyl group, a modified olefin polymer such as an alkoxysilane group. To be A plurality of these functional groups may be combined. Specifically, glycidyl modified polyethylene, glycidyl modified polypropylene, glycidyl modified ethylene-ethyl acrylate copolymer, glycidyl modified ethylene-vinyl acetate copolymer, alkoxysilane modified polyethylene, alkoxysilane modified polypropylene, alkoxysilane modified ethylene-vinyl acetate. One or a mixture of two selected from copolymers may be mentioned. In addition, polyester resins containing polyvalent carboxylic acids, polyhydric alcohols, and hydroxycarboxylic acids as constituent components can also be used as the adhesive resin.

When the dry laminating method is adopted,
The same dry laminating adhesive as described above can be used and is not particularly limited.

Containers (bags, cups, tubes, trays, bottles, etc.) composed of the laminates (films, sheets, etc.) produced by these methods are used for general food packaging,
Very suitable for pharmaceutical packaging and retort food packaging.

The present invention will be described below with reference to examples.
The present invention is not limited thereby.

[0061]

【Example】

Example 1 1.2 mol% of sodium 2-acrylamido-2-methylpropanesulfonate was random-copolymerized with EVOH to obtain an ion-modified EVOH having an ethylene content of 33 mol%, a saponification degree of 99.6 mol% and a polymerization degree of 800. 10% by weight
50% by weight of a mixed solvent of water / methyl alcohol = 50/50 (weight ratio) (hereinafter, simply referred to as “part”) has an ethylene content of 32.
Mol%, saponification degree 99.5 mol%, polymerization degree 1000 normal EVOH 28 parts, water 100 parts and methyl alcohol 1
The mixture was added to 00 parts and mixed, and dissolved by heating with stirring at 65 ° C.

After cooling this solution to 40 ° C., 50 parts of a methanol dispersion of 30% by weight of silica (average particle diameter 0.1 μm) was mixed with stirring. This mixed liquid was cooled to 5 ° C. with stirring to precipitate EVOH, and a composition containing EVOH and silica was obtained. The average particle size was 0.7 μm. Then, the composition was evaporated under reduced pressure at 20 ° C. with stirring to distill off methyl alcohol. Even in the process of distilling off methyl alcohol, almost no aggregation of particles was observed and the composition was stable, and an aqueous composition having an average particle diameter of 0.7 μm and a solid content concentration of 30% was obtained. Further, the storage stability was good, and almost no aggregation was observed in the storage test at 40 ° C. for 10 days.

A urethane-based anchor coating agent (AD335A / CAT10, Toyo Morton Co., Ltd.) was applied to the primer-treated surface of a biaxially oriented polypropylene film (film thickness 20 μm, Tokyo Cellophane Paper Co., Ltd.) as a substrate using this aqueous composition.
Was applied and then applied by the air knife coating method and dried and heat-treated at 110 ° C. for 5 minutes to obtain a multilayer film. Then, the multilayer film (EVOH layer thickness 3 μm
m) oxygen barrier property (Modern Control)
OX-TRAN 10 / 50A of company, measurement condition is 2
When measured at 0 ° C. and 100% RH, the oxygen permeation amount was 8.2 cc / m 2 · day · atm, which showed good barrier properties as a food packaging material (hereinafter, the oxygen permeation amount measurement conditions and units). Are the same). Further, from the coating of the aqueous composition and the observation of the surface and the cross section of the dried layer with an optical microscope (magnification: 10 times), no silica aggregates or local aggregates were found.

Comparative Example 1 A multilayer film was prepared and measured in the same manner as in Example 1 except that the silica dispersion was not added in Example 1. The oxygen transmission rate (20 ° C, 100% RH) was 23.
The gas barrier property was 0, which was lower than that of Example 1.

Comparative Examples 2 to 4 In Example 1, 50 parts by weight of an aqueous dispersion of 30% by weight montmorillonite instead of 50 parts by weight of a 30% by weight silica dispersion in methanol (Comparative Example 2) and 30% by weight talc were added. A multilayer film was obtained under the same conditions as in Example 1 except that 50 parts of the aqueous dispersion (Comparative Example 3) and 50 parts of the 30% by weight aqueous dispersion of mica (Comparative Example 4) were used. The oxygen transmission rate (20 ° C, 100% RH) of these multilayer films is 1
6.3 (Comparative Example 2), 18.4 (Comparative Example 3), 19.1
It was (Comparative Example 4).

Example 2 0.3% by mole of potassium 2-acrylamido-2-methylpropanesulfonate was randomly copolymerized with EVOH. Ethylene content 22% by mole, saponification degree 99.6% by mole, polymerization degree 600. / Ethyl alcohol = 40/60
50 parts of mixed solvent (concentration 10%) of ethylene of 27 mol%, saponification degree of 99.4 mol%, polymerization degree of 900 EVOH water / ethyl alcohol = 40/60 mixed solvent (concentration of 10%) 140 The mixture was added to the above parts and mixed, and heated and stirred at 70 ° C. to dissolve. This solution was cooled to 8 ° C. under stirring to precipitate particles, to obtain a dispersion liquid. The average particle size was 0.5 μm. Next, this dispersion was evaporated under reduced pressure at 25 ° C. with stirring to distill off ethyl alcohol. Average particle size is 0.5μ
m and a solid content concentration of 26% were obtained.

Next, 19 parts of silica was added to a vessel equipped with a stirrer so that a water dispersion having a concentration of 20% by weight was added, followed by stirring to prepare a silica colloid. Then, silica colloid was added to the above aqueous dispersion with stirring to obtain an aqueous composition having an average particle size of 0.4 μm and a solid content concentration of 23%. The storage stability was good.

The oxygen permeability (20 ° C., 100% RH) of the multilayer film obtained by coating and drying this aqueous composition on a substrate in the same manner as in Example 1 was 10.5, which was good as a food packaging material. It showed a good barrier property.

Example 3 Sodium allylsulfonate was randomly copolymerized with EVOH at 0.8 mol% to give an ethylene-modified EV having an ethylene content of 25 mol%, a saponification degree of 99.3 mol% and a polymerization degree of 400.
1900 parts of water was added to 250 parts of OH to prepare a dissolved solution. 20 was prepared in this solution as in Example 2.
2500 parts by weight of silica colloid were added. A high-speed stirrer was immersed in this solution, and the content of ethylene was 27 mol% and the degree of saponification was 99.6 mol% while stirring at 5000 rpm.
Normal EVOH with a degree of polymerization of 1100 dissolved in a mixed solvent of water / isopropyl alcohol = 30/70, concentration 10%
The solution was added dropwise to 5000 parts to precipitate particles to obtain a composition. The average particle size was 0.9 μm.

Next, this composition was evaporated under reduced pressure at 20 ° C. to remove isopropyl alcohol and the average particle size was 0.9.
An aqueous composition having a thickness of μm and a solid content concentration of 21% was obtained. It was a stable aqueous composition with almost no particle enlargement during the vacuum distillation process.

The multilayer composition obtained by coating and drying this aqueous composition on a substrate in the same manner as in Example 1 had an oxygen transmission rate (20 ° C., 100% RH) of 13.3, which was good as a food packaging material. It showed a good barrier property. No silica aggregates or local agglomerates were found in the coated and dried layer of the aqueous composition.

EXAMPLE 4 Sodium 2-methacrylamido-2-methylpropanesulfonate was added and introduced by a Michael addition reaction to the hydroxyl group of EVOH. The ethylene content was 33 mol%, the saponification degree was 99.6 mol%, and the polymerization degree was 1000. Using 300 parts of EVOH as a dispersion stabilizer, an ordinary EVOH 10 having an ethylene content of 33 mol%, a saponification degree of 99.5 mol% and a polymerization degree of 1010
00 parts and 10000 parts of a mixed solvent of water / methyl alcohol = 100/100 were mixed and dissolved by heating.

This solution was cooled to 15 ° C. with stirring to precipitate particles to obtain a dispersion liquid. Next, this dispersion was evaporated under reduced pressure to remove methyl alcohol. An aqueous dispersion having an average particle diameter of 0.8 μm and a solid content concentration of 22% was obtained.

Then, in the same manner as in Example 2, an aqueous composition containing 6000 parts of a colloid of silica of 20% by weight was obtained, and a similar multilayer film was prepared, and measurement and observation were performed. Oxygen permeability (20 ℃, 100% RH) is 1
At 2.0, it shows good barrier properties as a food packaging material,
No silica aggregates or local agglomerates were found in the coated and dried layer of the aqueous composition.

Example 5 An aqueous composition containing a silica colloid was prepared in the same manner as in Example 1 except that ion-modified EVOH in which sodium itaconate was randomly copolymerized with EVOH at 5.8 mol% was used. Get, make a similar multilayer film,
Measurement and observation were performed. Oxygen permeation rate (20 ℃, 100
% RH) was 14.8, which showed a good barrier property as a food packaging material, and no silica aggregates or local aggregates were found in the layer coated with the aqueous composition and dried.

Example 6 Ion having an ethylene content of 34 mol% in which 0.5 mol% of sodium 2-acrylamido-2-methylpropanesulfonate was randomly copolymerized with EVOH, a saponification degree of 99.4 mol% and a polymerization degree of 1100. 50 parts of modified EVOH in water /
It was added to 600 parts of a mixed solvent of methyl alcohol = 30/70 and mixed, and dissolved by heating with stirring at 65 ° C.

The solution was cooled to 10 ° C. with stirring to precipitate particles to obtain a dispersion liquid. Average particle size is 0.6 μm
Met. Next, this dispersion was evaporated under reduced pressure with stirring to distill off methyl alcohol. Even in the process of distilling off methyl alcohol, almost no particle aggregation is observed, and it is stable, and the ion-modified EVOH has an average particle size of 0.6 μm and a solid content concentration of 27%.
An aqueous dispersion of was obtained. It also has good storage stability at 40 ° C.
In the 10-day storage test, almost no aggregation was observed.

On the other hand, 15 parts of finely divided alumina oxide was added to a vessel equipped with a stirrer so that an aqueous dispersion having a concentration of 10% by weight was added, and the mixture was stirred to prepare a colloid of alumina oxide.

Then, a colloid of alumina oxide was added to the above aqueous dispersion of ion-modified EVOH with stirring to obtain an aqueous composition having an average particle diameter of 0.9 μm and a solid content concentration of 20%. The storage stability was good. Using this aqueous composition, a multilayer film was obtained in the same manner as in Example 1. The oxygen permeation amount (20 ° C., 100% RH) was 14.1 and showed good barrier properties as a food packaging material. Further, no aggregates or local aggregates of alumina oxide were found on the surface and cross section of the layer coated and dried with the aqueous composition.

Example 7 An aqueous composition having an average particle size of 0.7 μm and a solid content concentration of 20% was obtained by the same procedure as in Example 6 except that titanium oxide was used instead of alumina oxide of Example 6. . The storage stability was good. Using this aqueous composition, a multilayer film was obtained in the same manner as in Example 1. The oxygen transmission rate (20 ° C., 100% RH) was 12.9, indicating good barrier properties as a food packaging material. No aggregates or local agglomerates of titanium oxide were found in the surface and cross section of the layer coated and dried with the aqueous composition.

[0081]

As described above, according to the present invention, an aqueous composition having a high solid content concentration, which is excellent in stability during use, can be obtained, and since it is aqueous, there is no problem of environmental pollution. The film formed by coating and drying on various base materials has advantages, and has excellent gas barrier properties, particularly under high humidity of 90% RH or more, and especially under 100% RH, and aroma retention and It has oil and chemical resistance and is useful for various packaging.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jin Hiroto 1621 Sakata, Kurashiki City, Okayama Prefecture Kuraray Co., Ltd.

Claims (4)

[Claims] 1. An aqueous composition comprising an ethylene-vinyl alcohol copolymer aqueous dispersion having an ethylene content of 15 to 65 mol% and an inorganic oxide. 2. An ethylene content of 10 having an ionic group.
A modified ethylene-vinyl ester copolymer saponification product having a saponification degree of 80 mol% or more as a dispersion stabilizer,
An aqueous composition comprising an aqueous dispersion containing an ethylene-vinyl alcohol copolymer having an ethylene content of 15 to 65 mol% as a dispersoid, and an inorganic oxide. 3. An ethylene content having an ionic group of 15 to
An aqueous composition comprising an aqueous dispersion of an ethylene-vinyl alcohol copolymer at 65 mol% and an inorganic oxide. 4. A laminate having a coating layer obtained by applying the aqueous composition according to any one of claims 1 to 3 to a substrate and drying the composition.