JPH09327882A - High adhesion, high barrier transparent laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate for practical use which has good transparency, high gas barrier properties, and adhesion free from deterioration in lamination strength. SOLUTION: In a laminate, a transparent primer layer 2, a thin inorganic oxide film layer 3 of 5-300nm thickness, and a gas barrier coat layer 4 are laminated in sequence on a transparent plastic material 1. The gas barrier coat layer 4 has a layer which is formed by a method in which a coating agent containing an aqueous solution or a water/alcohol mixed solution which contains an aqueous polymer and at least one selected from (a) one or more kinds of metal alkoxide and its hydrolyzate and (b) tin chloride as a main agent is applied and dried.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laminate for packaging used in the field of packaging foods, non-foods, pharmaceuticals and the like.

[0002]

2. Description of the Related Art In recent years, packaging materials used for packaging foods, non-foods, and the like are required to prevent deterioration of contents and maintain their functions and properties. It is necessary to prevent the influence of gas that alters the contents, and it is required to have a gas barrier property that blocks these gases. Further, when the contents are stored for a long period of time, it is required that the laminate strength is not deteriorated by the contents because the contents retain gas barrier properties and function as a packaging material. Therefore, conventionally, a packaging material using a metal foil made of a metal such as aluminum, which is less affected by temperature, humidity, and the like, as a gas barrier layer has been generally used.

However, a packaging material using a metal foil made of a metal such as aluminum has excellent gas barrier properties and little deterioration in laminate strength over time, but the contents cannot be seen through the packaging material. There was a problem that it had to be treated as an incombustible material when it was discarded after use and that it could not be used with a metal detector.

Accordingly, as a packaging material which overcomes these drawbacks, for example, US Pat.
A film formed by depositing an inorganic oxide such as silicon oxide, aluminum oxide, and tin oxide on a polymer film by a forming means such as a vacuum evaporation method or a sputtering method as described in -28017 and the like. Is being developed. These films are known to have transparency and gas barrier properties against oxygen, water vapor, etc., and are suitable as packaging materials having both transparency and gas barrier properties that cannot be obtained with metal vapor deposition films. .

[0005]

However, although the above-mentioned film is transparent, its gas barrier property is slightly worse than that of aluminum foil, etc., and if it is stored for a long time, the film and the inorganic oxide may be different depending on the contents. There is a problem that the adhesiveness between the thin film layers is weak and peels off from that portion, and the laminate strength is reduced.

That is, as the conditions for use as a packaging material, the transparency is such that the contents can be directly seen through, the high gas barrier property for blocking the gas or the like that affects the contents, and the contents over time. There is a demand for a material having high adhesiveness that does not deteriorate the laminate strength due to the influence, and at present, no packaging material satisfying all of these has been found.

Therefore, an object of the present invention is to provide a highly practical laminate having excellent transparency, high gas barrier properties, and excellent adhesion without deterioration of laminate strength.

[0008]

The present invention is to achieve the above object, and the invention of claim 1 provides a transparent primer layer having a thickness of 5 to 300 nm on at least one side of a substrate made of a transparent plastic material. A thin film layer made of an inorganic oxide,
In a structure in which gas barrier coating layers are sequentially laminated, the gas barrier coating layer comprises an aqueous polymer, (a) one or more metal alkoxides and hydrolysates thereof, or (b) tin chloride.
Is a layer formed by applying a coating agent containing an aqueous solution or a water / alcohol mixed solution as a main component containing at least one of the above, and drying by heating.

According to a second aspect of the invention, there is provided the strong adhesion high barrier transparent laminate according to the first aspect, wherein the transparent primer layer is a polyester resin or a mixture of the resin and a mixed resin.

According to a third aspect of the invention, the mixed resin is
(A) isocyanate resin, (b) epoxy resin,
(C) A strong adhesion high barrier transparent laminate according to claim 2, which is a mixture of one or more selected from melamine resins.

According to a fourth aspect of the present invention, the mixed resin is an isocyanate resin, and the mixing ratio of the polyester resin and the isocyanate resin is (OH group of polyester):
(NCO group of isocyanate) 1: 0.5 to 1:20
The strong adhesion high barrier transparent laminate according to claim 2, wherein

In a fifth aspect of the present invention, the inorganic oxide is aluminum oxide, silicon oxide, tin oxide, magnesium oxide, or a mixture thereof, and the strong adhesion high barrier transparent. It is a laminated body.

According to a sixth aspect of the present invention, the water-soluble polymer is
It is polyvinyl alcohol, It is characterized by the above-mentioned.
The strong-adhesion high-barrier transparent laminate according to any one of items 1 to 5.

According to a seventh aspect of the present invention, in the strongly adhering high barrier transparent laminate according to the first aspect, the metal alkoxide is tetratetoxysilane, triisopropoxyaluminum, or a mixture thereof. is there.

In the laminate of the present invention, a transparent primer layer comprising a polyester resin alone or a resin mixed with the resin and having excellent adhesion is provided on a transparent plastic substrate, and an inorganic oxide layer as a gas barrier layer, and further an aqueous layer. Polymer
A gas barrier obtained by applying a coating agent containing an aqueous solution or a water / alcohol mixed solution containing at least one of (a) one or more metal alkoxides and a hydrolyzate thereof or (b) tin chloride, and heating and drying. Since the coating layers are laminated one after another, it is transparent and has a high gas barrier property similar to that of aluminum foil, and it is possible to prevent deterioration of the laminate strength due to the contents.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view illustrating a strong adhesion high barrier transparent laminate of the present invention.

First, the strong adhesion high barrier transparent laminate of the present invention shown in FIG. 1 will be described. The substrate 1 in FIG. 1 is a film made of a transparent plastic material, on which a transparent primer layer 2, a thin film layer 3 made of an inorganic oxide, and a gas barrier coating layer 4 are sequentially laminated.

The above-mentioned substrate 1 is a transparent plastic material, and a transparent film is preferable in order to make the most of the transparency of the vapor-deposited thin film layer. For example, polyethylene terephthalate (PET), polyester films such as polyethylene naphthalate, polyolefin films such as polyethylene and polypropylene, polystyrene films, polyamide films, polyvinyl chloride films, polycarbonate films, polyacrylonitrile films, polyimide films, etc. are used, It may be stretched or unstretched, and one having mechanical strength and dimensional stability is preferable. These are processed into a film and used. Particularly, polyethylene terephthalate arbitrarily stretched in the biaxial direction is preferably used. In addition, various known additives and stabilizers, for example, an antistatic agent, an ultraviolet ray inhibitor, a plasticizer, a lubricant, and the like may be used on the surface of the substrate 1 in order to improve the adhesion to the thin film. Further, a corona treatment, a low-temperature plasma treatment, an ion bombardment treatment or a chemical treatment, a solvent treatment or the like may be applied as a pretreatment.

The thickness of the substrate 1 is not particularly limited, but is suitable as a packaging material, may be laminated with other layers, the transparent primer layer 2 and the inorganic oxide thin film layer 3, the gas barrier. Considering the workability when forming the coating layer 4, it can be said that the thickness is practically in the range of 3 to 200 μm and preferably 6 to 30 μm depending on the application.

In consideration of mass productivity, it is desirable to use a long film so that each layer can be continuously formed.

The transparent primer layer 2 of the present invention is provided on the base material 1 made of a transparent plastic material to enhance the adhesiveness when the thin film layer 3 made of an inorganic oxide is provided, and to laminate with the passage of time after filling the contents. The purpose is to prevent deterioration of strength.

In order to achieve the above object, the primer resin that can be used is a polyester resin alone or the resin and one or more kinds of mixed resin selected from isocyanate resin, epoxy resin and melamine resin. Must be a mixture of.

The polyester resin is terephthalic acid, isophthalic acid, phthalic acid, methylphthalic acid, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, succinic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid. Acid sources such as hexahydrophthalic acid and reactive derivatives thereof, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol,
1,4-cyclohexanedimethanol, neopentyl glycol, isopentyl glycol, bishydroxyethyl terephthalate, hydrogenated bisphenol A, alkylene oxide adduct of hydrogenated bisphenol AA, trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, 2 Those produced by a known method from an alcohol raw material such as 1,2,4-trimethylpentane-1,3-diol can be used, but the invention is not particularly limited thereto.

The mixed resin added to the polyester resin is added to further improve the adhesiveness, and mainly acts as a crosslinking agent or a curing agent. In order to achieve this, as a mixed resin, isocyanate resins such as tolylene diisocyanate (TDI), xylene diisocyanate (XDI), and hexadiisocyanate (MDI), bisphenol A diglycine ether type epoxy and hydrogenated bisphenol type epoxy Epoxy resins, melamine resins, and mixtures of one or more of these. Among them, isocyanate resin (particularly, TDI) is preferred because it has the best adhesion.

The mixing ratio of the polyester resin and the mixed resin may be such that an isocyanate group, an epoxy group, an amino group or the like is contained in an equivalent amount or more with respect to the OH group or the COOH group of the polyester resin. For example, when a simple isocyanate resin is used as the mixed resin, the mixing ratio of the polyester resin and the isocyanate resin is (O
H group): (NCO group of isocyanate) 1: 0.5-
It is desirable that the range is 1:20. If it is less than the equivalent, poor curing and insufficient cross-linking will result in a problem in adhesion. However, adding too much is not preferable because the added resin does not react and adversely affects the remaining film. A well-known method can be used for the mixing method and is not particularly limited.

The organic solvent for dissolving the primer resin is not particularly limited as long as it can dissolve the resin, and examples thereof include esters such as ethyl acetate and butyl acetate, methyl ethyl ketone, methyl isobutyl ketone and the like. Aromatic hydrocarbons such as ketones, toluene and xylene may be used alone or in any combination.
Preferably, a mixture of toluene and methyl ethyl ketone is preferable from the viewpoint of coating film processing and odor.

Various additives such as 3 are added to the primer resin.
Hardening accelerators such as secondary amines, imidazole derivatives, metal salt compounds of carboxylic acids, quaternary ammonium salts, and quaternary borophonium salts, and antioxidants such as phenol-based, sulfur-based and phosphite-based antioxidants, leveling agents, and flow control agents It is also possible to add a catalyst, a crosslinking reaction accelerator, a filler and the like.

The thickness of the transparent primer layer 2 is not particularly limited as long as a coating film can be formed uniformly, but it is generally in the range of 0.01 μm to 1.0 μm, particularly preferably 0.
It is preferably in the range of 1 μm to 0.5 μm.

As a method for forming the transparent primer layer 2,
For example, a known printing method such as an offset printing method, a gravure printing method, or a silk screen printing method, or a known coating method such as roll coating, knife edge coating, or gravure coating can be used. The drying conditions may be generally used conditions.

The thin film layer 3 made of an inorganic oxide is made of a vapor deposited film of an inorganic oxide such as aluminum oxide, silicon oxide, tin oxide, magnesium oxide, or a mixture thereof.
Any material may be used as long as it has transparency and gas barrier properties such as oxygen and water vapor. However, the thin film layer 3 of the present invention is not limited to the above-mentioned inorganic oxide, but may be any material that meets the above conditions.

The optimum thickness of the thin film layer 3 varies depending on the type and composition of the inorganic compound used, but is generally 5
It is desirable to be within the range of -300 nm, and the value is appropriately selected. However, if the film thickness is less than 5 nm, a uniform film may not be obtained or the film thickness may not be sufficient, and the function as a gas barrier material may not be sufficiently achieved. When the thickness exceeds 300 nm, the thin film cannot maintain flexibility,
There is a possibility that the thin film may be cracked by external factors such as bending and pulling after film formation. Preferably, 10-1
It is in the range of 50 nm.

There are various methods for forming the thin film layer 3 made of an inorganic oxide on the transparent primer layer 2. The thin film layer 3 can be formed by an ordinary vacuum deposition method, but other thin film forming methods such as a sputtering method and an ion method. A plating method, a plasma vapor deposition method (CVD) or the like can also be used. However, in consideration of productivity, the vacuum deposition method is currently the most excellent. The heating means of the vacuum evaporation apparatus by the vacuum evaporation method is preferably an electron beam heating method, a resistance heating method, or an induction heating method. It is also possible to use a method or an ion beam assist method. Further, in order to increase the transparency of the vapor deposition film, reactive vapor deposition may be performed in which oxygen gas or the like is blown during vapor deposition.

The gas barrier coating layer 4 is provided on the inorganic oxide thin film layer 3 to provide a gas barrier property as high as that of an aluminum foil, and comprises a water-soluble polymer.
It comprises a coating agent mainly comprising an aqueous solution or a water / alcohol mixed solution containing at least one of (a) one or more metal alkoxides and hydrolysates or (b) tin chloride. A water-soluble polymer and tin chloride are mixed with water (water or water /
A solution obtained by coating a solution obtained by dissolving with a solvent or a solution obtained by directly treating a metal alkoxide directly or by preliminarily hydrolyzing the solution onto the inorganic oxide thin film layer 3 and drying by heating. It is.
Each component contained in the coating agent will be described in more detail.

Examples of the water-soluble polymer used in the coating agent in the present invention include polyvinyl alcohol, polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate and the like. In particular, when polyvinyl alcohol (hereinafter, referred to as PVA) is used as a coating agent for the laminate of the present invention, the gas barrier properties are most excellent. The PVA referred to here is generally obtained by saponifying polyvinyl acetate, and includes a range from so-called partially saponified PVA in which acetic acid groups remain to several tens% to complete PVA in which only a few% of acetic acid groups remain. However, there is no particular limitation.

Further, tin chloride is stannous chloride (SnCl ₂ ),
Stannic chloride (SnCl ₄ ) or a mixture thereof may be used, and either anhydrous or hydrated can be used.

Further, the metal alkoxide is represented by a general formula such as tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ], triisopropoxyaluminum [Al (O-2′-C ₃ H ₇ ) ₃ ], M (OR). _n (M: Si Ti Ti Al Zr or other metal, R: CH ₃
(An alkyl group such as C ₂ H ₅ ). Among them, tetraethoxysilane and triisopropoxyaluminum are preferable because they are relatively stable in an aqueous solvent after hydrolysis.

Each of the above-mentioned components can be added to the coating agent alone or in combination, and further, an isocyanate compound, a silane coupling agent, a dispersant or a stabilizer can be added as long as the gas barrier properties of the coating agent are not impaired. Well-known additives such as viscosity modifiers and colorants can be added.

For example, the isocyanate compound added to the coating agent has two or more isocyanate groups (NCO groups) in its molecule, and examples thereof include tolylene diisocyanate (hereinafter TDI) and triphenylmethane triisocyanate (hereinafter TTI). ), Tetramethylxylene diisocyanate (hereinafter TMXDI) and other monomers, and their polymers and derivatives.

As a method for applying the coating agent, conventionally known means such as a dipping method, a roll coating method, a screen printing method, a spray method and the like which are commonly used can be used. The thickness of the coating varies depending on the type of coating agent and processing conditions, but the thickness after drying is 0.01μ.
It is sufficient that the thickness is at least m, but if the thickness is at least 50 μm, cracks are likely to occur in the film, so that the thickness is preferably in the range of 0.01 to 50 μm.

Further, another layer may be laminated on the gas barrier coating layer 4. For example, a print layer or a heat seal layer. The printing layer is formed for practical use as a packaging bag, and various pigments are used for ink binder resins that have been conventionally used such as urethane-based, acrylic-based, nitrocellulose-based, rubber-based, and vinyl chloride-based. A layer composed of an ink to which an extender pigment and additives such as a plasticizer, a desiccant and a stabilizer are added,
Letters, patterns, etc. are formed. As a forming method, for example, a well-known printing method such as an offset printing method, a gravure printing method, or a silk screen printing method, or a well-known coating method such as a roll coat, a knife edge coat, or a gravure coat can be used. The thickness may be 0.1 to 2.0 μm.

The heat-sealing layer is used as an adhesive portion when forming a bag-like package, and includes polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene. A resin such as a methacrylic acid ester copolymer, an ethylene-acrylic acid copolymer, an ethylene-acrylic acid ester copolymer and a metal cross-linked product thereof is used. The thickness is determined according to the purpose, but is generally in the range of 15 to 200 μm. As a forming method, any of known methods such as a dry laminating method of laminating a film made of the above resin by a non-solvent laminating method, an extrusion laminating method in which the above resin is melted by heating and extruded in a curtain shape, and laminated Can be laminated by.

The strong adhesion high barrier transparent laminate of the present invention will be further described with reference to specific examples.

[0043]

【Example】

Example 1 A resin having the following composition was formed as a transparent primer layer 2 on one surface of a biaxially stretched polyethylene terephthalate (PET) film having a thickness of 12 μm as a substrate 1 by a gravure coating method. Resin: Polyester / isocyanate system Blending ratio: OH group (polyester) / NCO group (isocyanate) = 1/8 Thickness: 0.1 μm Dissolving solvent: Toluene / methyl ethyl ketone = 5/5 Next, resistance not shown on the transparent primer layer 2 The inorganic oxide thin film layer 3 was formed by vapor-depositing silicon oxide to a thickness of about 40 nm with a vacuum vapor deposition apparatus using a heating method. Further, a coating agent having the following composition was applied on it by a bar coater and dried in a dryer at 120 ° C. for 1 minute to give a thickness of 0.3.
A gas barrier coating layer 4 having a thickness of μm was formed to obtain a strong adhesion high barrier transparent laminate of the present invention. (Composition of coating agent) Tetraethoxysilane 10.4 g and hydrochloric acid (0.1
N) 89.6 g was added and hydrolyzed with a solid content of 3 wt% (converted to SiO ₂ ) which was stirred for 30 minutes to be hydrolyzed. 3 wt% polyvinyl alcohol water / isopropyl alcohol solution (water: isopropyl alcohol weight ratio 90:10). ) A mixture of liquid and liquid at a compounding ratio (wt%) of 60/40

Example 2 In Example 1, as the inorganic oxide thin film layer 3, metallic aluminum was evaporated by a vacuum vapor deposition apparatus using an electron beam heating system (not shown), and oxygen gas was introduced therein to obtain a 20 nm thick film. A strong adhesion high barrier transparent laminate of the present invention was similarly obtained except that an aluminum oxide thin film layer was formed.

Example 3 A strong adhesion high barrier transparent laminate of the present invention was obtained in the same manner as in Example 1, except that the following resin was used as the transparent primer layer 2. Resin: Polyester Thickness: 0.2 μm Dissolving solvent: Toluene / methyl ethyl ketone = 8/2

Example 4 A strong adhesion high barrier transparent laminate of the present invention was obtained in the same manner as in Example 1 except that the transparent primer layer 2 was changed to the following resin. Resin: Polyester / Epoxy Composition ratio: Polyester / Epoxy = 7/3 (weight ratio) Thickness: 0.2 μm Solvent: Toluene / Methyl ethyl ketone = 8/2

Comparative Example 1 A transparent laminated body was obtained in the same manner as in Example 1 except that the transparent primer layer 2 and the gas barrier coating layer 4 were not provided.

Comparative Example 2 A transparent laminate was obtained in the same manner as in Example 1 except that the gas barrier coating layer 4 was not provided.

Comparative Example 3 A transparent laminated body was obtained in the same manner as in Example 1 except that the transparent primer layer 2 was not provided.

<Laminate> A linear low density polyethylene (LLDPE) film having a thickness of 50 μm is dry laminated on the inorganic oxide thin film layer side of the laminates of Examples and Comparative Examples via a two-component curing type urethane adhesive. Laminated by the method.

<Test 1> For Examples and Comparative Examples,
The transparency of the content was visually evaluated, and the water vapor permeability (g / m ² / day) was evaluated as the gas barrier property. Table 1 shows the results.

<Test 2> For the laminates of Examples and Comparative Examples, the laminate strength (gr / 15 mm) was measured by Tensilon as an evaluation of adhesion.
The measurement was carried out by a 180 ° peeling method with the substrate straightened. Table 1 shows the results.

<Test 3> A pouch with a four-way seal was prepared for the laminated products of the examples and the comparative examples, and a commercially available toothpaste powder 3 was used as the content.
It was filled with 0 g and stored in an atmosphere of 40 ° C.-90% RH for 1 month, after which the laminate strength (gr / 15 mm) was measured. The measuring instrument and the conditions were the same as in Test 2.
Table 1 shows the results.

[0054]

[Table 1]

In contrast to the Examples, the Comparative Examples are provided with the above-mentioned conditions for use as a package, and are transparent enough to allow the contents to be directly seen through, and gasses affecting the contents are blocked. Although the high gas barrier property and the high adhesiveness in which the laminate strength does not deteriorate due to the influence of the contents over time are not satisfied, the Examples can be said to satisfy all of them.

[0056]

As described above, according to the present invention, it is possible to obtain a versatile packaging material having excellent transparency and having a gas barrier property as high as that of an aluminum foil. Further, since it is excellent in initial adhesion and aging adhesion after filling contents, it can be said that it can be widely used in the packaging field.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a strong adhesion high barrier transparent laminate of the present invention.

[Explanation of symbols]

 1 transparent plastic substrate 2 transparent primer layer 3 inorganic oxide thin film layer 4 gas barrier coating layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B65D 65/40 B65D 65/40 D

Claims (7)

[Claims] 1. A structure in which a transparent primer layer, a thin film layer made of an inorganic oxide having a thickness of 5 to 300 nm, and a gas barrier coating layer are sequentially laminated on at least one surface of a substrate made of a transparent plastic material, and the gas barrier coating layer comprises: A coating agent containing an aqueous solution or a water / alcohol mixed solution containing at least one of an aqueous polymer and (a) at least one metal alkoxide and its hydrolyzate or (b) tin chloride as a main component is applied, and heated. A strong adhesion high barrier transparent laminate, which is a layer formed by drying. 2. The strong adhesion high barrier transparent laminate according to claim 1, wherein the transparent primer layer is a polyester resin or a mixture of the resin and a mixed resin. 3. The mixed resin is a mixture of one or more selected from (a) an isocyanate resin, (b) an epoxy resin, and (c) a melamine resin. The strong adhesion high barrier transparent laminate described. 4. The mixed resin is an isocyanate resin, and the mixing ratio of the polyester resin and the isocyanate resin is (OH group of polyester) :( N of isocyanate
The strong adhesion high barrier transparent laminate according to claim 2, wherein the CO group is 1: 0.5 to 1:20. 5. The strong adhesion high barrier transparent laminate according to claim 1, wherein the inorganic oxide is aluminum oxide, silicon oxide, tin oxide, magnesium oxide, or a mixture thereof. 6. The strong adhesion high barrier transparent laminate according to claim 1, wherein the water-soluble polymer is polyvinyl alcohol. 7. The metal alkoxide is tetratetoxysilane or triisopropoxyaluminum, or a mixture thereof.
The strong adhesion high barrier transparent laminate described.