JPH06219441A - Container - Google Patents

Abstract

PURPOSE:To provide a container with a high gas-barrier property and a good ability to keep the odor of the contents by not employing a copolymer of ethylene and vinylalcohol for both the barrier layer and the sealing layer to be formed. CONSTITUTION:A laminate including a layer of paper 12 is used as the material 11 for a container. A barrier layer 16 therein is formed of any from among a copolymer of ethylene and vinyl alcohol, a polyamide resin represented by the formula, and polyvinylidene chloride resin. In the formula referred to (n) represents an integer satisfying 10<=n<=10000. The sealing layer 18 is formed of either a copolymer of ethylene and vinylalcohol or a copolymerized polyester. However, it is not applicable to formation of the barrier layer 16 and the sealing layer 18 to employ a copolymer of ethylene and vinyl-alcohol for both of them. Therefore, it is effectively prevented for the gas-barrier property to retrograde through contact of ethylene-vinyl-alcohol copolymer in the barrier layer 16 with moisture.

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 address this, a container using a resin layer on the innermost surface of which a flavor component is less adsorbed, and a container on which a barrier layer is formed using a resin layer having 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 deteriorates when it comes into contact with moisture,
The former container has a problem that it cannot maintain a high gas barrier property for a long time, and the latter container has a problem of E
Although the reduction of the gas barrier property of the VOH layer is prevented, there is a problem in 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
EVO as a barrier layer due to moisture that has permeated the H layer
There is a problem that the gas barrier property of the H layer is gradually lowered. 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 comprises a paper layer, a polyolefin resin layer formed on the outside of the paper layer, and an inside of the paper layer. In a container in which a base material including a barrier layer and a seal layer formed inside the barrier layer is formed so that the polyolefin-based resin layer has an outer surface, the barrier layer is ethylene-vinyl alcohol A polymer, which is formed of any one of a polyamide resin and a polyvinylidene chloride resin represented by the following chemical formula,

[0009]

[Chemical 2] (However, n is an integer, 10 ≦ n ≦ 10,000) The seal layer is formed of either an ethylene-vinyl alcohol copolymer or a copolyester, and the barrier layer and the seal. The layer and the layer were configured so as not to be formed of an ethylene-vinyl alcohol copolymer.

[0010]

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 the barrier layer in the substrate is ethylene-vinyl alcohol copolymer, any of the polyamide resin and polyvinylidene chloride resin represented by the above chemical formula. Since it is formed, excellent gas barrier properties are obtained, and when the barrier layer is formed of an ethylene-vinyl alcohol copolymer, the sealing layer is formed of a copolymerized polyester, and thus the barrier layer is formed. It is possible to effectively prevent the ethylene-vinyl alcohol copolymer from contacting with water from lowering its gas barrier property. That.

[0011]

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, a substrate 11 is a paper layer 12, a polyethylene resin (PE) layer 13 formed on one surface of the paper layer 12, and a polyethylene resin (PE) layer formed on the other surface of the paper layer 12. 14, a barrier layer 16 laminated on the PE layer 14 via an adhesive polyolefin resin 15
And a seal layer 18 laminated on the barrier layer 16 with an adhesive polyolefin resin 17 interposed therebetween. The PE layer 13 constitutes the outer surface of the container 1, and the sealing layer 18 constitutes the inner surface of the container 1.

The barrier layer 16 is formed of any one of an ethylene-vinyl alcohol copolymer, a polyamide resin represented by the following chemical formula, and a polyvinylidene chloride resin.

[0014]

[Chemical 3] (However, n is an integer, 10 ≦ n ≦ 10,000) The barrier layer 16 made of the above resin has an oxygen permeability of 10 cc / m ² · day · 1 atm or less and has an excellent gas barrier. is doing.

The seal layer 18 is formed of either ethylene-vinyl alcohol copolymer or copolymer polyester. 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, a trivalent carboxylic acid such as trimellitic acid is used as part of the acid component, or 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. In the present invention, the following five combinations of the resin forming the barrier layer 16 and the resin forming the seal layer 18 are used.

(Barrier Layer) (Sealing Layer) Ethylene-Vinyl Alcohol Copolymer ... Copolymer Polyester Polyamide Resin ... Ethylene-Vinyl Alcohol Copolymer Polyamide Resin ... Copolymer Polyester Polyvinylidene Chloride Resin ... Ethylene-Vinyl Alcohol Copolymer Combined Polyvinylidene chloride resin ... Copolyester In the above combination of the constituent resins of the barrier layer 16 and the seal layer 18, both the barrier layer 16 and the seal layer 18 are not formed of the ethylene-vinyl alcohol copolymer. Therefore, it is effectively prevented that the ethylene-vinyl alcohol copolymer of the barrier layer comes into contact with water and its gas barrier property is lowered. That is, the ethylene-vinyl alcohol copolymer has a property that the gas barrier property is deteriorated when it comes into contact with water, but when the barrier layer 16 is formed of the ethylene-vinyl alcohol copolymer, the sealing layer 18 is Since it is formed of the copolyester, moisture from the contents is less likely to permeate through the seal layer 18 and does not reach the barrier layer 16. On the other hand, in another resin that can form the barrier layer 16, that is, a polyamide resin or a polyvinylidene chloride resin, the seal layer 18 is formed of an ethylene-vinyl alcohol copolymer.
The barrier property does not deteriorate even if it contacts the moisture from the contents that have gradually permeated through. Therefore, due to the combination of the constituent resins of the barrier layer 16 and the seal layer 18, the gas barrier property of the base material 11 is high for a long period of time without providing a moisture-proof layer between the seal layer 18 and the barrier layer 16. Maintained at. Therefore, in the substrate used in the present invention, as described above, the barrier layer 16 and the seal layer 1
8 can be laminated by a single-layer adhesive polyolefin resin layer 17. The adhesive polyolefin-based resin layer 17 is replaced by the adhesive polyolefin-based resin layer / PE layer /
Needless to say, a three-layer structure including an adhesive polyolefin resin layer may be used.

Here, the adhesive polyolefin resin 15 for adhering the PE layer 14 and the barrier layer 16 and the adhesive polyolefin resin 17 for adhering the barrier layer 16 and the seal layer 18 are polyethylene and ethylene-α-olefin. Polymers, polyα-olefins such as polypropylene, polybutene and polyisobutylene, polydiolefins such as polybutadiene and polyisoprene, and copolymers thereof 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. Ethylenic unsaturated esters: 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, vinylmethylketone and vinylbutylketone are used, preferably ethylenically unsaturated carboxylic acid or ethylenically unsaturated anhydrous carboxylic acid. Acid is used.

The basis weight of the paper layer constituting the substrate 11 as described above is about 100 to 500 g / m ² , the PE layer 13 is about 10 to 50 μm thick, and the PE layer 14 is about 10 to 40 μm thick.
m, the thickness of the barrier layer 16 is preferably about 5 to 30 μm, the thickness of the seal layer 18 is preferably about 5 to 70 μm, and the total thickness of the substrate 11 is preferably about 140 to 700 μm. The container 1 using such a base material 11 can be formed using 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 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) to form a three-layered sheet. Created.

Next, the following two layers were laminated on one polyethylene resin layer of the above-mentioned three-layered sheet by coextrusion. Adhesive polyolefin-based resin layer (Mitsui Petrochemical Co., Ltd. Admer SE800) 7.5 μm Ethylene-vinyl alcohol copolymer layer (Kuraray Co., Ltd., Eval F) 7.5 μm Further, the above ethylene-vinyl alcohol copolymer The following two layers were laminated on the layers by coextrusion to obtain a substrate.

Adhesive polyolefin-based resin layer (Mitsui Petrochemical Industrial Co., Ltd. Admer SE800) 7.5 μm Copolyester layer (Mitsui DuPont Polychemical Co., Ltd. Miller PTX150) 12.5 μm Using this substrate, 1000 cc A carton type container (Sample 1) filled with orange juice was prepared. -Preparation of Sample 2 A container was used in the same manner as in Sample 1 except that a polyamide resin (nylon MXD6 manufactured by Mitsubishi Gas Chemical Co., Inc.) was used as the barrier layer forming resin instead of the ethylene-vinyl alcohol copolymer. (Sample 2) was prepared. -Preparation of Sample 3 The same procedure as in Sample 1 above except that a polyvinylidene chloride resin (Saran manufactured by Dow Chemical Co., Ltd.) was used as the barrier layer forming resin instead of the ethylene-vinyl alcohol copolymer. A container (Sample 3) was created. -Preparation of sample 4 First, low density polyethylene 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 [mu] m) to form a three-layered sheet.

Next, the following two layers were laminated on one polyethylene resin layer of the above-mentioned three-layered sheet by coextrusion. Adhesive polyolefin-based resin layer (Mitsui Petrochemical Co., Ltd. Admer SE800) 7.5 μm Polyamide resin layer (Mitsubishi Gas Chemical Co., Ltd. Nylon MXD6) 7.5 μm Further, the following two layers are provided on the polyamide resin layer. It laminated by co-extrusion and it was set as the base material.

Adhesive polyolefin resin layer (Mitsui Petrochemical Co., Ltd. Admer SE800) 7.5 μm Ethylene-vinyl alcohol copolymer layer (Kuraray Co., Ltd., Eval E) 12.5 μm ・ Preparation of sample 5 Barrier layer As a sample, a container (Sample 5) was prepared in the same manner as in Sample 4 except that a 7.5 μm-thick polyvinylidene chloride resin film (Saran made by Dow Chemical Co., Ltd.) was used instead of the polyamide resin film. did. -Preparation of Comparative Sample First, a sheet having a three-layer structure in which a polyethylene resin layer was laminated on both sides of the paper layer was prepared in the same manner as in Sample 1.

Next, the following two layers were laminated on one polyethylene resin layer of the above-mentioned three-layered sheet by coextrusion. Adhesive polyolefin-based resin layer (Mitsui Petrochemical Co., Ltd. Admer SE800) 7.5 μm Ethylene-vinyl alcohol copolymer layer (Kuraray Co., Ltd., Eval F) 7.5 μm Further, the above-mentioned ethylene-vinyl alcohol copolymer weight The following two layers were laminated on the united layer by coextrusion to form a base material.

Adhesive polyolefin resin layer (Mitsui Petrochemical Co., Ltd. Admer SE800) 7.5 μm Ethylene-vinyl alcohol copolymer layer (Kuraray Co., Ltd. Eval F) 12.5 μm 1000 cc using this substrate A carton type container (comparative sample) filled with the orange juice was prepared.

Each container prepared as described above (Sample 1)
.About.5 and comparative samples), the gas barrier properties and the aroma of the orange juice as the content were evaluated as follows. The results are shown in Table 1. (Gas barrier property) Using Oxytran manufactured by Modern Control Co., the oxygen permeability per container was measured at room temperature and normal pressure. (Aromaticity of contents) After being stored in an atmosphere of 7 to 8 ° C for 5 days, it was opened and evaluated by a sensory test.

[0029]

[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.

[0030]

As described above in detail, according to the present invention, the container has a high aroma-storing property of the contents due to the seal layer which is the innermost layer (inner surface of the container) of the base material constituting the container. The barrier layer in the base material imparts a superior gas barrier property to the container, and further, the combination of the resin forming the barrier layer and the resin forming the seal layer is set to a predetermined value, whereby the barrier layer and the seal layer are formed. Even if the and are laminated via a single adhesive layer, the deterioration of the gas barrier property of the barrier layer due to moisture from the contents is effectively prevented, and the container has 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 ... Base material 12 ... Paper layer 13 ... Polyethylene resin layer 14 ... Polyethylene resin layer 15 ... Adhesive polyolefin resin layer 16 ... Barrier layer 17 ... Adhesive polyolefin resin layer 18 ... Sealing layer

Claims (1)

[Claims] 1. A paper layer, a polyolefin resin layer formed outside the paper layer, a barrier layer formed inside the paper layer, and a seal layer formed inside the barrier layer. In a container in which a base material provided is box-formed so that the polyolefin-based resin layer serves as an outer surface, the barrier layer includes an ethylene-vinyl alcohol copolymer, a polyamide resin represented by the following chemical formula, and a polyvinylidene chloride resin. Formed by either of the following: (However, n is an integer, 10 ≦ n ≦ 10,000) The seal layer is formed of either an ethylene-vinyl alcohol copolymer or a copolyester, and the barrier layer and the seal. A container, wherein the layer and the layer are not formed of an ethylene-vinyl alcohol copolymer.