JPH06329153A - Container - Google Patents

Abstract

PURPOSE:To provide a container which has an excellent gas barrier function and a retentive ability of the fragrance of the contents. CONSTITUTION:The basic material 11 constituting of a container is a laminate structure including a paper layer 12. The sealing layer of the innermost layer (inner face of the container) of the basic material 11 is made of either ethylene vinyl alcohol copolymer or its copolymer polyester and an inorganic oxide thin film is provided in the barrier layer 15 in the basic material 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a container, and more particularly to a container having both an excellent gas barrier property and an aroma retaining property.

[0002]

2. Description of the Related Art As a container for filling liquid foods such as fruit juices, alcoholic beverages, yogurt and the like, there is a container formed of a base material having various resin layers laminated around a paper layer. As the substrate, one having a polyolefin resin layer having a heat-fusible property on the outermost surface and the innermost surface in consideration of the container forming property has been used. Further, in order to prevent the contents from being oxidized and deteriorated, an aluminum foil layer was provided as a barrier layer in the substrate.

However, the polyolefin resin layer forming the inner surface of the container has a problem that the flavor component of the content is easily adsorbed, which deteriorates the flavor of the content filled and stored in the container. Moreover, since the base material is provided with the aluminum foil layer, it is difficult to dispose of the used container.

[0004]

In order to cope with this, a container using a resin layer with less adsorption of flavor components on the innermost surface, and a container with a barrier layer using a resin layer with low oxygen permeability have been developed. Has been done. For example, JP-A-63-39
No. 50, JP-A-63-321143, ethylene-
Paying attention to the non-adsorption property of the flavor component and the high gas barrier property in the vinyl alcohol copolymer (EVOH), polyethylene (PE) / paper / polyethylene (PE) / EVOH
A container using a 4-layer structure base material, PE / paper / EVOH /
A container using a base material having a four-layer structure of PE is disclosed.

However, EVOH has a property that its gas barrier property is deteriorated when it comes into contact with water vapor, so that the former container has a problem that it cannot maintain a high gas barrier property for a long period of time, and the latter container has a problem. In that case, the deterioration of the gas barrier property of the EVOH layer is prevented,
There is a problem that the PE layer on the inner surface adsorbs the flavor component.

Therefore, by combining the contents disclosed in JP-A-63-3950 and JP-A-63-321143, both the barrier layer and the innermost layer are EVOH layers.
A container using a base material having a layer structure of E / paper / EVOH / adhesive layer / EVOH has been developed. However, even in this container, due to the above-mentioned properties of EVOH, the EVO of the innermost layer is
EV as a barrier layer due to water vapor transmitted through the H layer
There is a problem that the gas barrier property of the OH layer gradually decreases. Therefore, the adhesive layer provided between the barrier layer and the innermost layer needs to have a three-layer structure such as an adhesive layer / PE / adhesive layer instead of a single layer, which increases the manufacturing cost. Was coming.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a container having a high gas barrier property and an excellent aroma retaining property of the contents.

[0008]

In order to achieve such an object, the present invention provides a paper layer, a polyolefin resin layer formed outside the paper layer, and an inorganic layer formed inside the paper layer. A base material comprising a barrier layer having an oxide thin film and a seal layer formed of either ethylene-vinyl alcohol copolymer or copolyester on the inside of the barrier layer, wherein the polyolefin resin layer is outside. This is a configuration in which the surface is made so that it becomes the surface.

[0009]

The base material forming the container has a laminated structure, and the innermost layer (the inner surface of the container) of the base material is a seal layer made of either ethylene-vinyl alcohol copolymer or copolyester. Therefore, it does not absorb the flavor component of the contents, and since the barrier layer located between the seal layer and the paper layer has a thin film of an inorganic oxide, excellent gas barrier properties are obtained, and further, The sealing layer is formed of ethylene-vinyl alcohol copolymer,
Even if the barrier layer comes into contact with the water vapor that has permeated the seal layer,
It has a stable gas barrier property without deteriorating its gas barrier property.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an example of the container of the present invention. In FIG. 1, a container 1 is a carton type container made by using a base material 11, and has a bottomed body portion 2,
It has a top portion 3 connected to the body portion 2.

FIG. 2 is a schematic sectional view of the base material 11 which constitutes the container 1. In FIG. 2, the substrate 11 includes a paper layer 12, a polyolefin resin layer 13 formed on one surface of the paper layer 12, a polysand layer 14 formed on the other surface of the paper layer 12, a barrier layer 15, It has a laminated structure including a seal layer 17 laminated on the barrier layer 15 via an adhesive layer 16. The polyolefin resin layer 13 constitutes the outer surface of the container 1, and the seal layer 17 constitutes the inner surface of the container 1.

The paper layer 12 constituting the base material 11 has a basis weight of 20.
About 0 to 500 g / m ² is preferable. The polyolefin resin layer 13 laminated on the paper layer 12 can be formed of a polyolefin resin such as polyethylene or polypropylene, particularly low density polyethylene, and its thickness is preferably about 10 to 50 μm.

The polysand layer 14 is a layer for heat-sealing the paper layer 12 and the barrier layer 15, and an adhesive polyolefin resin layer 15A constituting the barrier layer 15 described later.
While extruding the adhesive polyolefin resin on top,
It is formed by heat-sealing the paper layer 12. The thickness of such a polysand layer 14 is preferably about 15 to 50 μm.

The barrier layer 15 is an adhesive polyolefin resin layer 15 formed on one surface of the resin film 15B.
A and the inorganic oxide thin film 15C formed on the other surface of the resin film 15B have a three-layer laminated structure, and as described above, on the adhesive polyolefin resin layer 15A side, on the paper layer 12 via the polysand layer 14 It is stacked.

As the resin film 15B, polyester resin, polyvinyl alcohol resin, polyamide resin,
A film of polypropylene resin, polycarbonate resin, polystyrene resin or the like can be used. Further, these resin films are subjected to uniaxial or biaxial stretching treatment, corona discharge treatment, discharge treatment such as low temperature plasma treatment, silane coupling agent coating, primer coating, sand plast treatment, etc. It may be treated to improve the adhesiveness with the inorganic oxide thin film 15C. The thickness of the resin film 15B is preferably about 5 to 50 μm.

Adhesive polyolefin resin layer 15A formed on one surface of the resin film 15B as described above.
Is formed using the following adhesive polyolefin resin. That is, polyethylene, ethylene-α
Olefin copolymer, polypropylene, polybutene, polyα-olefins such as polyisobutylene, polydiolefins such as polybutadiene and polyisoprene, or
These copolymers and the like can be used. Further, ethylene and a carbonyl group based on a carboxylic acid, a carboxylic acid salt, a carboxylic acid anhydride, a carboxylic acid ester, a carboxylic acid amide or a carboxylic acid imide, an aldehyde, a ketone or the like, alone, or a cyano group, a hydroxy group, an ether group. , A copolymer with one or more ethylenically unsaturated monomers having a combination with an oxirane ring or the like can be used. More specifically, A. Ethylenically unsaturated carboxylic acids: acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, 5-norbornene 2,3-dicarboxylic acid, etc., B.I. Ethylenically unsaturated carboxylic anhydrides: maleic anhydride, citraconic anhydride, 5-norbornene 2,3-dicarboxylic anhydride, tetrahydrophthalic anhydride and the like, C.I. Ethylenically unsaturated ester: ethyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate, mono- or diethyl maleate, vinyl acetate, vinyl propionate, γ-hydroxymethacrylate propyl, β-hydroxyethyl acrylate, glycidyl acrylate, Glycidyl methacrylate, β-N-ethylaminoethyl acrylate, etc., D.I. Ethylenically unsaturated amides or imides: acrylamide, methacrylamide, maleimide, etc. E. Ethylenically unsaturated aldehydes or ketones: Ethylenically unsaturated monomers such as acrolein, methacrolein, vinyl methyl ketone, vinyl butyl ketone, etc. are used, preferably ethylenically unsaturated carboxylic acid or ethylenically unsaturated anhydrous carboxylic acid. Acid is used.

Adhesive polyolefin resin layer 15A formed of the adhesive polyolefin resin as described above.
Has a thickness of about 10 to 50 μm, preferably 15 to 30 μm
It is about m.

The inorganic oxide thin film 15C formed on the surface of the resin film 15B opposite to the surface on which the adhesive polyolefin resin layer 15A is formed is, for example, silicon oxide (SiO _x ) or aluminum oxide (Al ₂ It is composed of a thin film such as O ₃ ). The method for forming the inorganic oxide thin film 15C is not particularly limited, and there are a vacuum deposition method such as an ion beam method and an electron beam method, and a sputtering method.

The thickness of such an inorganic oxide thin film 15C is usually 20 nm or more, and preferably 30 to 150 nm, in order to obtain sufficient barrier properties. If the thickness of the inorganic oxide thin film 15C exceeds 150 nm, the inorganic oxide thin film 15C is likely to be cracked, the gas barrier property may be deteriorated, and the material cost becomes expensive, which is not preferable.

The inorganic oxide thin film 15C may be, for example, a mixture of silicon monoxide and silicon dioxide, a mixture of silicon oxide and aluminum oxide, or the like. The adhesive layer 16 can be formed by suitably using an isocyanate adhesive. Examples of the isocyanate-based adhesive include a polyester polyurethane-based adhesive and a two-component curing type adhesive in which a polyether polyurethane-based adhesive is used as a main component and a curing agent such as tolylene diisocyanate and xylene diisocyanate is added to this main component. .
The thickness of the adhesive layer 16 is about 1 to 10 g / m ² , preferably about ² to 5 g / m ² .

The seal layer 17 is formed of either an ethylene-vinyl alcohol copolymer or a copolyester. All of these resins have excellent fragrance retaining performance.

Here, the copolyester is an amorphous to low crystalline saturated polyester resin having a glass transition temperature of 40 ° C. or higher, and is a dialcohol component such as ethylene glycol, propylene glycol, 1,4-cyclohexanedimethanol. And a dicarboxylic acid component such as an aliphatic dicarboxylic acid such as adipic acid or sebacic acid or an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid or diphenyldicarboxylic acid. Specifically, by co-condensation polymerization of a combination of ethylene glycol and terephthalic acid, ethylene glycol and isophthalic acid and terephthalic acid, 1,4-cyclohexanedimethanol and ethylene glycol and terephthalic acid, propylene glycol and isophthalic acid and terephthalic acid, etc. In addition to the resulting polyester resin or ethylene glycol and terephthalic acid as basic raw materials, trivalent carboxylic acids such as trimellitic acid are used as part of the acid component, and trimethylol is used as part of the alcohol component. Examples include polyester resins obtained by using a trivalent alcohol such as propane, or by using a trivalent carboxylic acid and a trivalent alcohol in a part of the acid component and a part of the alcohol component. To be

The copolyester is not preferable because the aroma-retaining performance of the copolyester decreases when the content of the aliphatic dicarboxylic acid component in the acid component is 10% by weight or more. The thickness of the seal layer 17 is preferably about 5 to 100 μm, and the base material 1
The total thickness of 1 is preferably about 300 to 1000 μm.

Here, the barrier layer 15 is the seal layer 17
Is formed from an ethylene-vinyl alcohol copolymer,
The barrier property does not deteriorate even if it contacts the water vapor from the contents that have gradually passed through the sealing layer 17. Therefore, the combination of the constituent resins of the barrier layer 15 and the seal layer 17 makes it possible to obtain the seal layer 17 and the barrier layer 15
The gas barrier property of the base material 11 is maintained in a high state for a long period of time without providing a water vapor barrier layer between and.
Therefore, in the base material used in the present invention, the barrier layer 15 and the seal layer 17 can be laminated by the single-layer adhesive polyolefin resin layer 16 as described above.
The adhesive polyolefin-based resin layer 16 may, of course, have a three-layer structure composed of adhesive polyolefin-based resin layer / polyolefin-based resin layer / adhesive polyolefin-based resin layer. Also, a two-layer structure composed of a polyolefin resin layer / adhesive polyolefin resin layer may be used.

The container 1 using such a substrate 11 can be formed by a known means such as a heat sealing method or an ultrasonic sealing method. Next, the present invention will be described in more detail with reference to experimental examples. (Experimental example) -Preparation of sample 1 First, low density polyethylene resin (Mirason 16 manufactured by Mitsui Petrochemical Industry Co., Ltd.) was applied to one side of paper having a basis weight of 340 g / m ^2.
sp) was extruded and laminated to form a polyethylene resin layer (thickness 20 μm) to prepare a two-layer base material sheet.

On the other hand, a barrier layer is composed of a biaxially stretched polyester film (Rack Barrier H, 12 μm thick manufactured by Mitsubishi Kasei Co., Ltd.) having a vapor-deposited thin film (thickness 50 nm) of silicon oxide (SiO ₂ ) on one surface. It is used as a resin film, and an isocyanate adhesive (Lx703 / KR-90 manufactured by Dainippon Ink and Chemicals, Inc.) is applied to the silicon oxide thin film side of this resin film to form an adhesive layer (3 μm).
m) Next, a coextruded film of ethylene-vinyl alcohol copolymer and low density polyethylene (MJF manufactured by Dainippon Resin Co., Ltd., thickness 60 μm) was laminated on this adhesive layer to form a seal layer. Then, an adhesive polyolefin resin (Nucrel N-1108C manufactured by Mitsui DuPont Polychemical Co., Ltd.) is extruded and laminated on the other surface of the resin film to form an adhesive polyolefin resin layer having a thickness of 15 μm, and the barrier. A laminated sheet having a layer and a sealing layer was prepared.

Next, while adhering the adhesive polyolefin resin (Nucrel N-1108C manufactured by Mitsui DuPont Polychemical Co., Ltd.) to the surface of the base material sheet where the paper layer is exposed, the above laminated sheet is adhered. The base polyolefin resin layer was heat-welded to obtain a base material. 1 using this substrate
A carton type container (Sample 1) filled with 000 cc of orange juice was prepared. In this carton container, the end face in the body direction is processed by the skive hemming method on the content side so that the cross section of the base material does not touch, and then the part where the polyolefin and seal layer are bonded is framed and bonded by hot air. The obtained product was filled with orange juice using a filling and packaging machine, and then the seal layers were heated with hot air to seal and mold. · As for creating a seal layer forming resin sample 2, ethylene - except for using instead copolyesters of the vinyl alcohol copolymer (manufactured by Mitsui Du Pont Polychemical Co. sealer PT8307) is the same manner as Sample 1 above To prepare a container (Sample 2). -Preparation of sample 3 As a resin film for forming a barrier layer, a biaxially stretched polyester film (manufactured by Toyo Metallizing Co., Ltd.) 10 having a vapor-deposited thin film of aluminum oxide (thickness 50 nm).
Sample 1 above except that 11 MG, thickness 12 μm) was used.
A container (Sample 3) was prepared in the same manner as in. -Preparation of sample 4 As a resin film for forming a barrier layer, a biaxially stretched polyester film (manufactured by Toyo Metallizing Co., Ltd.) 10 having a vapor-deposited thin film of aluminum oxide (thickness 50 nm).
11 MG, thickness 12 μm), and as a resin for forming the seal layer, a copolyester (Sealer PT8307 manufactured by Mitsui DuPont Polychemical Co., Ltd.) was used instead of the ethylene-vinyl alcohol copolymer.
A container (Sample 4) was prepared in the same manner as in Sample 1 above. ・ Preparation of comparative sample Adhesive polyolefin resin (Mitsui Petrochemical Co., Ltd.)
Admale F300) was used as an intermediate layer for three-layer coextrusion with an ethylene-vinyl alcohol copolymer (Eval E manufactured by Kuraray Co., Ltd.) to obtain an ethylene-vinyl alcohol copolymer layer (barrier layer, 15 μm) and an adhesive layer ( 15μ
m) and an ethylene-vinyl alcohol copolymer layer (seal layer, 30 μm) were formed.

On the other hand, low density polyethylene resin (Mirason 16sp manufactured by Mitsui Petrochemical Co., Ltd.) was extruded and laminated on both sides of a paper having a basis weight of 340 g / m ² to form a polyethylene resin layer (thickness 20 μm). A three-layer base material sheet was prepared.

The above laminated sheet was dry laminated on one polyethylene resin layer side of this substrate sheet to obtain a substrate. Using this substrate, a carton type container (comparative sample) filled with 1000 cc of orange juice was prepared.

Each container (Sample 1) prepared as described above
.About.4 and comparative samples), the gas barrier properties and the aromatic properties of the orange juice as the content were evaluated as follows. The results are shown in Table 1. (Gas barrier property) A carton stored at 40 ° C. for 1 month was prepared using Modern Control Oxytran.
The oxygen permeability per container was measured at room temperature, RH 95%, and normal pressure. (Aroma of contents) 1 at 40 ℃
After storing for 4 days, it was opened and evaluated by a sensory test.

[0031]

[Table 1] As shown in Table 1, the container of the present invention has both excellent gas barrier property and aroma retention performance, but the comparative sample is
Although both the gas barrier layer and the seal layer were formed of an ethylene-vinyl alcohol copolymer and had good fragrance retention, deterioration of the gas barrier property was observed.

[0032]

As described in detail above, according to the present invention, the seal layer which is the innermost layer (inner surface of the container) of the base material constituting the container is either an ethylene-vinyl alcohol copolymer or a copolyester. Since the container has a high aroma retaining property of the contents, and the barrier layer existing between the paper layer and the seal layer has a thin film of an inorganic oxide, it has excellent gas barrier properties. Even when applied to a container and further laminating a barrier layer and a seal layer via a single adhesive layer, the gas barrier property of the barrier layer does not deteriorate due to water vapor from the contents, and the container is It has a stable gas barrier property and aroma retention performance.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a container of the present invention.

FIG. 2 is a schematic cross-sectional view of a base material that constitutes the container of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Container 2 ... Body part 3 ... Top part 11 ... Substrate 12 ... Paper layer 13 ... Polyolefin resin layer 14 ... Polysand layer 15 ... Barrier layer 15A ... Adhesive polyolefin resin layer 15B ... Resin film layer 15C ... Inorganic oxide thin film 16 ... Adhesive layer 17 ... Seal layer

Claims (1)

[Claims] 1. A paper layer, a polyolefin-based resin layer formed on the outside of the paper layer, a barrier layer having an inorganic oxide thin film formed on the inside of the paper layer, and ethylene on the inside of the barrier layer. A container comprising a base material having a seal layer formed of either a vinyl alcohol copolymer or a copolyester, and the polyolefin resin layer serving as an outer surface of the base material.