JPH06219442A - Container - Google Patents

Abstract

PURPOSE:To employ a material in which there is virtually no difference in stiffness between the component on the inner side of a layer of paper and the component on the outer side of it and obtain in the material a high gas barrier property and a good ability to keep the odor of the contents by providing in the material a layer of polyolefin resin and a barrier layer on the outer side of a layer of paper and a layer of polyolefin resin and a sealing layer on the inner side of the layer of paper. CONSTITUTION:A material 11 has a layer of paper 12, a barrier layer 15 on the outer side of the layer of paper 12 with a layer of polyolefin resin 14 therebetween, and a sealing layer 18 on the inner side of the layer of paper 12 with a layer of polyolefin resin 17. This material is used to make a container with the sealing layer 18 forming the innermost surface. As a result, the material 11 has virtually the same stiffness between the inner part and outer part with the layer of paper 12 therebetween. Therefore, when the material 11 is bent in the forming process of a container, the bending is effected with the layer of paper 12 as the center and breaking of the layer of paper 12 through tension is prevented. In order to improve the processability in the forming process of a container it is possible to form a layer of polyolefin resin over the barrier layer 15 with an additional layer of adhesive polyolefin resin therebetween.

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 excellent gas barrier properties and aroma retaining property of contents and having high durability.

[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, since the base material used in the conventional container having a barrier property has a larger amount of resin located inside the paper layer than the amount of resin located outside the paper layer. The difference in rigidity between the front and back of the paper layer in the material is large.
Therefore, when the base material is bent in the container forming process, it is bent around the back side of the paper layer having high rigidity, and the stretching force acts on the paper layer located outside, causing the paper layer to rupture and the container strength. There was a problem that it decreased.

The present invention has been made in view of the above circumstances, and uses a base material having almost no difference in rigidity between the inside and outside of the paper layer, has a high gas barrier property, and has an aroma retaining property of the contents. It is intended to provide an excellent container.

[0007]

In order to achieve such an object, the present invention provides a paper layer, a barrier layer formed outside the paper layer via a polyolefin resin layer, and the paper layer. This is a configuration in which a base material provided with a seal layer formed on the inside with a polyolefin-based resin layer interposed therebetween is box-formed so that the seal layer serves as the inner surface.

[0008]

The base material forming the container has a laminated structure including a paper layer, the polyolefin resin layer and the barrier layer are located outside the paper layer of the base material, and the polyolefin is located inside the paper layer. The system resin layer and the seal layer are located, and the rigidity inside and outside the base material through the paper layer is substantially equal. Therefore, when the base material is bent in the container forming process, the paper layer is bent to be the center of the paper layer. Is prevented from being pulled and breaking.

[0009]

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 base material 11 is laminated with a paper layer 12, a polyethylene resin (PE) layer 13 formed on one surface of the paper layer 12, and an adhesive polyolefin resin 14 on the PE layer 13. The barrier layer 15, the polyethylene resin (PE) layer 16 formed on the other surface of the paper layer 12, and the adhesive polyolefin resin 1 on the PE layer 16
7 has a laminated structure composed of a seal layer 18 laminated via 7. The barrier layer 15 constitutes the outer surface of the container 1, and the seal layer 18 constitutes the inner surface of the container 1.

The barrier layer 15 is formed of any of an ethylene-vinyl alcohol copolymer, a polyamide resin represented by the following chemical formula, and a polyvinylidene chloride resin.

[0012]

[Chemical 2] (However, n is an integer, 10 ≦ n ≦ 10,000) The barrier layer 15 made of the resin as described above has an oxygen permeability of 100 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 is deteriorated when the aliphatic dicarboxylic acid component in the acid component is 10% by weight or more. Where PE
The adhesive polyolefin resin 14 for bonding the layer 13 and the barrier layer 15 and the adhesive polyolefin resin 17 for bonding the PE layer 16 and the seal layer 18 are polyethylene, ethylene-α-olefin copolymer, polypropylene, polybutene, It is possible to use poly α-olefins such as polyisobutylene, polydiolefins such as polybutadiene and polyisoprene, or copolymers thereof. Further, ethylene and a carbonyl group based on carboxylic acid, carboxylic acid salt, carboxylic acid anhydride, carboxylic acid ester, carboxylic acid amide or carboxylic acid imide, aldehyde, ketone or the like, or a cyano group,
A copolymer with one or more ethylenically unsaturated monomers having a combination with a hydroxy group, an ether group, an oxirane ring and 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 60 to 500 g / m ² , and the thickness of the PE layer 13 is 1
0 to 30 μm, the thickness of the barrier layer 15 is 5 to 20 μm
m, the thickness of the PE layer 16 is preferably about 15 to 50 μm, and the thickness of the seal layer 18 is preferably about 5 to 50 μm.
It is preferable that the total thickness of layers outside the paper layer 12 is about 20 to 70 μm, the total thickness of layers inside the paper layer 12 is about 25 to 120 μm, and the total thickness of the substrate 11 is about 100 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.

In the present invention, as described above, the polyolefin resin layer 13 and the barrier layer 15 are present outside the paper layer 12, and the polyolefin resin layer 16 and the seal layer 18 are present inside the paper layer 12. Therefore, the rigidity of the layers outside the paper layer 12 and the rigidity of the inside layers do not differ significantly. Therefore, the bending of the base material 11 in the container forming step is performed around the paper layer 12, and the paper layer 12 is prevented from being pulled and broken.

In the present invention, a polyolefin resin layer may be further formed on the barrier layer 15 via an adhesive polyolefin resin layer in order to improve workability in the container forming step. In this case, the thickness of the polyolefin resin layer is preferably about 10 to 30 μm.

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, on one polyethylene resin layer of this sheet, an adhesive polyolefin resin (Admer SE810 manufactured by Mitsui Petrochemical Industry Co., Ltd.) and an ethylene-vinyl alcohol copolymer (Eval E manufactured by Kuraray Co., Ltd.) were used. 6. Laminated by coextrusion to produce an adhesive layer (5 μm) and an ethylene-vinyl alcohol copolymer layer (barrier layer, 7.
5 μm) was formed. Furthermore, on the other polyethylene resin layer of the above sheet, an adhesive polyolefin resin (Admer SE-810 manufactured by Mitsui Petrochemical Industry Co., Ltd.) and a copolyester (PET-G676 manufactured by Eastman Kodak Co., Ltd.) were used.
3) was laminated by coextrusion to form an adhesive layer (7.5 μm) and a copolyester layer (seal layer, 12.5 μm) to obtain a base material.

A carton type container (Sample 1) filled with 1000 cc of orange juice was prepared using this substrate. -Preparation of Sample 2 The same procedure as in Sample 1 above except that a polyvinylidene chloride resin (Saran made by Dow Chemical Co., Ltd.) was used as the barrier layer forming resin instead of the ethylene-vinyl alcohol copolymer. A container (Sample 2) was prepared. -Preparation of sample 3 A container was prepared 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 3) was prepared. -Preparation of sample 4 As a resin for forming the seal layer, an ethylene-vinyl alcohol copolymer (Kuraray Co., Ltd.) was used instead of the copolymerized polyester.
A container (Sample 4) was prepared in the same manner as in Sample 1 except that Eval G) was used. -Preparation of sample 5 As a resin for forming the seal layer, an ethylene-vinyl alcohol copolymer (Kuraray Co., Ltd.) was used instead of the copolyester.
Manufactured by EVAL G) as a resin for forming a barrier layer,
A container (Sample 5) was prepared in the same manner as in Sample 1 except that a polyvinylidene chloride resin (Saran manufactured by Dow Chemical Co., Ltd.) was used instead of the ethylene-vinyl alcohol copolymer.
It was created. -Preparation of Sample 6 Instead of the copolyester as the resin for forming the seal layer, an ethylene-vinyl alcohol copolymer (Kuraray Co., Ltd.)
Manufactured by EVAL G) as a resin for forming a barrier layer,
A container (Sample 6) similar to Sample 1 above except that a polyamide resin (nylon MXD6 manufactured by Mitsubishi Gas Chemical Co., Inc.) was used instead of the ethylene-vinyl alcohol copolymer.
It was created. -Preparation of sample 7 A barrier layer (ethylene-
Adhesive polyolefin resin (Admer S manufactured by Mitsui Petrochemical Co., Ltd.) on the vinyl alcohol copolymer layer
E-810) and low-density polyethylene (Mirason 11P manufactured by Mitsui Petrochemical Industry Co., Ltd.) were laminated by coextrusion to form an adhesive layer (7.5 μm) and a polyethylene resin layer (12.5 μm). It was used as the base material. Then, in the same manner as the sample 1, a carton type container (sample 7) filled with 1000 cc of orange juice was prepared. ・ Preparation of comparative sample Adhesive polyolefin resin (Mitsui Petrochemical Industry Co., Ltd.)
(Admer SE-810 manufactured by K.K.) was used as an intermediate layer and three-layer coextrusion with an ethylene-vinyl alcohol copolymer (Eval E manufactured by Kuraray Co., Ltd.) was performed to obtain an ethylene-vinyl alcohol copolymer layer (barrier layer, 7.5 .mu.m). , Adhesive layer (7.5
μm) and an ethylene-vinyl alcohol copolymer layer (sealing layer, 12.5 μm). A barrier layer side of this laminated sheet and one polyethylene resin layer side of the same three-layer sheet used to prepare Sample 1 were dry laminated to obtain a substrate. Using this substrate, a carton type container (comparative sample) filled with 1000 cc of orange juice was prepared.

Each container prepared as described above (Sample 1
.About.7 and comparative samples), the presence or absence of breakage of the paper layer was observed at the bent portions at the bottom and the top.
Further, the container strength, the gas barrier property, and the aroma of the orange juice as the content were evaluated as follows. The results are shown in Table 1. (Container Strength) Drops were made twice from a height of 50 cm in the vertical direction, and leakage or liquid stain was visually inspected. n number = 50 (gas barrier property) Using Oxytran manufactured by Modern Control Co., Ltd., oxygen permeability per 1 m ² of paper 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.

[0022]

[Table 1] As shown in Table 1, the container of the present invention had high paper strength without breakage of the paper layer, and also had both excellent gas barrier property and aroma retention performance. However, the comparison sample is
The paper layer was broken and the container strength was poor.

[0023]

As described above in detail, according to the present invention, the rigidity of the polyolefin-based resin layer and the barrier layer positioned outside the paper layer of the substrate and the polyolefin-based resin layer positioned inside the paper layer and Since there is almost no difference from the rigidity of the seal layer, the paper layer is prevented from being pulled and ruptured when the base material is bent in the container forming process, and the container has high strength and excellent gas barrier property and aroma retention performance. Is possible.

[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 ... Adhesive polyolefin resin layer 15 ... Barrier layer 16 ... Polyethylene resin layer 17 ... Adhesive polyolefin resin layer 18 ... Sealing layer

Claims (3)

[Claims] 1. A paper layer, a barrier layer formed outside the paper layer via a polyolefin resin layer, and a seal layer formed inside the paper layer via a polyolefin resin layer. A container, characterized in that a base material is box-formed so that the sealing layer serves as an inner surface. 2. The barrier layer of the substrate is ethylene-
A vinyl alcohol copolymer, a polyamide resin represented by the following chemical formula, or a polyvinylidene chloride resin, wherein: (However, n is an integer, 10 ≦ n ≦ 10,000) The seal layer is formed of either an ethylene-vinyl alcohol copolymer or a copolyester. Container. 3. The container according to claim 1, wherein the base material further comprises a polyolefin resin layer formed outside the barrier layer via an adhesive layer.