JPH0550563A - Paper composite container with barrier property - Google Patents

Abstract

PURPOSE:To provide a barrier paper composite container having both of good barrier properties and sufficient strength and inexpensively producted without bringing about the complicatedness of a process. CONSTITUTION:A barrier paper composite container is formed from a packing material 1 based on an inner surface layer 2 composed of a carboxyl group- containing polyethylene resin, the barrier layer 3 positioned outside the inner surface layer 2 and containing a semi-aromatic polyamide resin being a copolymer of an aromatic polyamide forming component consisting of aliphatic diamine and isophthalic acid and/or terephthalic acid and lactam or an aliphatic polyamide forming component consisting of aliphatic diamine and aliphatic dicarboxylic acid or nylon MXD 6 and the paper provided to the outside of the barrier layer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a barrier paper composite container, which has particularly good barrier properties and sufficient strength and can be manufactured at low cost without complicating the manufacturing process. Regarding a composite container.

[0002]

2. Description of the Related Art Conventionally, in a paper composite container which is required to have a gas barrier property, a packaging material forming the container has a laminated structure, and an aluminum foil layer is further interposed in the laminated structure. It was generally done. And such a container was usually a single-use disposable container.

However, due to the recent demand for resource reuse,
There is a demand for a container that can be recovered after use and separated for each material for reuse. However, in a container formed of packaging material using aluminum foil as described above, a container formed of packaging material using aluminum foil laminated between resin and paper is laminated between resin and paper. There is a problem that the formed aluminum foil cannot be easily separated and collected.

Therefore, various containers having a good barrier property have been developed without using a metal thin film such as an aluminum foil. For example, from inside the container polyethylene (PE) resin layer / paper layer / PE resin layer / nylon 6 layer / P
A container formed of a packaging material having a five-layer structure of an E resin layer (see JP-A-63-22624), and from the inside of the container, a PE resin layer / paper layer / PE resin layer / ethylene-vinyl alcohol copolymer A container formed of a packaging material having a five-layer structure of a united (EVOH) layer / PE resin layer (see Japanese Patent Laid-Open No. 63-321143), or a PE resin layer / paper layer / PE resin layer / A container formed of a packaging material having a six-layer structure of EVOH layer / nylon 6 layer / PE resin layer (see Japanese Patent Laid-Open No. 160551/1990).
Etc. have been developed.

[0005]

However, of the above-mentioned containers, the first container has a problem that the gas barrier property of the nylon 6 layer is insufficient. In addition, in the second container, the barrier property due to the EVOH layer is good, but the strength is weak, and when it is used as a soft drink container, the EVOH layer cannot contact the contents, so it is located inside the container. There is a problem that the EVOH layer needs to be covered with skiving or the like on the end surface of the packaging material to complicate the manufacturing process. Furthermore, the third container is
Since the base material layer is provided on the outside of the EVOH layer and the nylon 6 layer, the container has both the EVOH layer and the nylon 6 layer although it is possible to have both excellent barrier properties and sufficient strength. Therefore, there is a problem that the manufacturing cost becomes high.

The present invention has been made in view of the above circumstances, and an object of the present invention is to have both good barrier properties and sufficient strength, and at a low cost without complicating the manufacturing process. It is intended to provide a barrier paper composite container manufactured.

[0007]

Means for Solving the Problems The constitution of the present invention for achieving the above object is to provide an inner surface layer containing a carboxyl group-containing polyethylene resin, and an aliphatic diamine and isophthalic acid located outside the inner surface layer. A semi-aromatic polyamide resin or nylon MXD6, which is a copolymer of an aromatic polyamide forming component consisting of and / or terephthalic acid and an lactam or an aliphatic diamine forming component consisting of an aliphatic diamine and an aliphatic dicarboxylic acid. A barrier paper composite container, characterized in that it is formed of a packaging material having a barrier layer and a base material layer which is located outside the barrier layer and has paper as a main component.

[0008]

The barrier paper composite container of the present invention is provided with an inner surface layer containing a carboxyl group-containing polyethylene resin,
A barrier layer containing a semi-aromatic polyamide resin having a good barrier property or nylon MXD6, which is a crystalline thermoplastic polymer, is provided on the outside of the inner surface layer, and a group having excellent strength is provided on the outside of the barrier layer. A material layer is provided. Therefore, the barrier paper composite container of the present invention has both good barrier properties and sufficient strength.
Further, by forming the inner surface layer forming the innermost surface of the container from a carboxyl group-containing polyethylene resin, a barrier layer is formed directly outside the inner surface layer without an adhesive layer, so that the layer structure is simplified. The barrier paper composite container is provided at low cost by a simplified manufacturing process.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of a packaging material forming the barrier paper composite container of the present invention. In FIG. 1, a packaging material 1 includes an inner surface layer 2 which is an innermost surface of a container, a barrier layer 3 directly formed on the outer surface of the inner surface layer 2, and an outer surface of the barrier layer 3 via an adhesive layer 8. And a substrate layer 4 formed on the substrate.

The inner surface layer 2 contains a carboxyl group-containing polyethylene resin and is a layer for heat-sealing the inner surface layers 2 to each other or to the inner surface layer 2 and the outermost layer of the base material layer 4 described later when forming a container. .. The carboxyl group-containing polyethylene resin contained in the inner surface layer 2 has adhesiveness with the semi-aromatic polyamide resin contained in the barrier layer 3 or nylon MXD6, and thus the inner surface layer 2 and the barrier layer 3 are Are laminated directly without interposing an adhesive layer.

Specific examples of the carboxyl group-containing polyethylene resin include, for example, ethylene-methacrylic acid copolymer resin (EMAA), ethylene-acrylic acid copolymer resin (EAA), ionomer resin, ethylene-
Examples thereof include maleic anhydride copolymer resin and ethylene-ethyl acrylate-maleic anhydride copolymer resin. The thickness of the inner surface layer 2 containing such a carboxyl group-containing polyethylene resin is preferably about 5 to 100 μm.

The barrier layer 3 is a semi-aromatic compound composed of an aliphatic polyamide-forming component composed of an aliphatic diamine and isophthalic acid and / or terephthalic acid, and an lactam or an aliphatic polyamide-forming component composed of an aliphatic diamine and an aliphatic dicarboxylic acid. Polyamide Resin or Nylon M
Contains XD6.

More specifically, the semi-aromatic polyamide resin is usually a polyamide-forming component 1 comprising an aliphatic diamine and isophthalic acid and / or terephthalic acid.
It is a copolymer composed of 0 to 60% by weight and 0 to 40% by weight of an aliphatic polyamide forming component composed of a lactam or an aliphatic diamine and an aliphatic dicarboxylic acid. This semi-aromatic polyamide resin has a lower degree of crystallinity than ordinary aliphatic polyamide resins and exhibits characteristics as an amorphous resin. Also, unlike EVOH, this semi-aromatic polyamide resin may come into direct contact with liquid contents such as soft drinks, so that it is not necessary to treat the end surface of the packaging material with skive or the like, and the process can be simplified. Becomes Further, since the semi-aromatic polyamide resin has the same strength as that of nylon 6, it is not necessary to provide a reinforcing layer, and the manufacturing cost can be reduced.

The nylon MXD6 is a crystalline thermoplastic polymer obtained by a polycondensation reaction of metaxylenediamine (MXDA) and adipic acid, and is a polyamide resin represented by the following chemical formula.

[0015]

[Chemical 1] This nylon MXD6 has a good barrier property due to the aromatic ring in the main chain. FIG. 2 is a diagram showing oxygen permeability coefficients of nylon MXD6 and other resins. As is apparent from FIG. 2, nylon MXD6 has an oxygen permeability coefficient at 100% relative humidity, which is a problem in a container filled with a liquid content such as a soft drink, but not only conventional nylon 6 but also ethylene-vinyl alcohol copolymer ( It has a better barrier property than EVOH). Also, nylon MD
Since X6 may come into direct contact with liquid contents such as soft drinks as in the case of the above semi-aromatic polyamide resin, it is not necessary to perform treatment such as skiving on the end surface of the packaging material when EVOH is used. It is possible to simplify the process.
Furthermore, since nylon MXD6 has the same strength as conventional nylon, it is not necessary to provide a reinforcing layer, and the manufacturing cost can be reduced.

The semi-aromatic polyamide resin or nylon MXD6 is preferably contained in the barrier layer 3 in a proportion of about 20 to 100% by weight. The content of semi-aromatic polyamide resin or nylon MXD6 is 20
If it is less than wt%, sufficient barrier properties may not be obtained.

The thickness of the barrier layer 3 is preferably about 5 to 60 μm. If the thickness of the barrier layer 3 is less than 5 μm, the barrier properties may not be sufficiently exhibited. On the other hand, if the thickness exceeds 60 μm, it is not preferable because not only the strain becomes hard and difficult to mold when molding into a container but also the cost becomes expensive.

The adhesive layer 8 interposed between the barrier layer 3 and the base material layer 4 is formed of, for example, an adhesive polyolefin resin or an isocyanate adhesive. Examples of the adhesive polyolefin-based resin include polyethylene, ethylene-α-olefin copolymers, α-polyolefins such as polypropylene, polybutene and polyisobutylene, and polydiolefins such as polybutadiene and polyisoprene, and carboxylic acids and carboxylates. Ethylenic unsaturation having carbonyl group based on carboxylic acid anhydride, carboxylic acid ester, carboxylic acid amide or imide, aldehyde, ketone, etc. alone or in combination with cyano group, hydroxy group, ether group, oxirane ring, etc. A copolymer with one or more monomers may be used. Further, the adhesive layer 8 containing such an adhesive polyolefin resin may contain a polyolefin resin, particularly polyethylene. In this case, the content of the adhesive polyolefin resin in the adhesive layer 8 is preferably 40% by weight or more. When the content of the adhesive polyolefin-based resin is less than 40% by weight, the adhesiveness to the barrier layer 3 is lowered, which is not preferable. Further, as the above-mentioned isocyanate-based adhesive, use a two-component curing type adhesive or the like in which a polyester polyurethane-based resin, a polyether polyurethane-based resin as a main component and a curing agent such as tolylene diisocyanate or xylene diisocyanate is used for curing. You can

The thickness of the adhesive layer 8 is 3 to 30 μm.
About m is preferable. The surface of the base material layer 4 in contact with the adhesive layer 8 (polyolefin resin layer 6) is preferably subjected to corona discharge treatment. Thereby, the base material layer 4
The adhesive strength between the adhesive layer 8 and the adhesive layer 8 is further improved.

The base material layer 4 is a three-layer laminate in which olefin resin layers 6 and 7 are provided on both sides of a support 5. Support 5
As the material, paper, biaxially oriented polyester film, biaxially oriented polypropylene film or the like can be used. The thickness of the support 5 is preferably about 100 to 600 μm. The polyolefin resin layers 6 and 7 provided on both sides of the support 5 are particularly preferably polyethylene resin layers. The thickness of the resin layers 6 and 7 is 10 to 10 respectively.
It is about 60 μm. The base material layer 4 may have a two-layer structure having a polyolefin resin layer on one surface of the support 5.

A packaging material 1 in which the above layers are laminated.
Is usually subjected to corona discharge treatment on the surface of the base material layer 4 to be in contact with the adhesive layer 8 (polyolefin resin layer 6), and then an adhesive is applied to this treated surface to form an adhesive, and thereafter, It is produced by laminating the above-mentioned semi-aromatic polyamide resin or nylon MXD6 and carboxyl group-containing polyethylene on the above adhesive layer by coextrusion laminating.

The barrier paper composite container of the present invention is formed by using the above-mentioned packaging material 1 by, for example, punching the packaging material 1 into a predetermined shape and then heat-sealing it by hot air heating, flame heating or the like. Done.

Next, the present invention will be described in more detail with reference to experimental examples. Experimental Example First, an acid-resistant paper having a basis weight of 400 g / m ² was used as a support, and low-density polyethylene resin as a polyolefin-based resin layer [manufactured by Mitsui Petrochemical Industry Co., Ltd., “Mirason 16sp ]] Was extruded and laminated to form a resin layer having a thickness of 20 μm to form a base material layer of a three-layer laminate. (Sample-1) A corona discharge treatment was applied to one surface of the base material layer, and an isocyanate adhesive [Takelac A310] and "Ketanate A-3" manufactured by Takeda Yakuhin Kogyo Co., Ltd. was applied on the treated surface. It was applied to form an adhesive layer. Then, a barrier layer (thickness: 10 μm) made of a semi-aromatic polyamide resin [“Novamid X21” manufactured by Mitsubishi Kasei Co., Ltd.] and a carboxyl group-containing polyethylene resin [Mitsui DuPont Polychemical ( Co., Ltd.
"Neucrele 0908C"] inner layer (thickness 30
μm) and were co-extruded and laminated so as to be laminated in this order to prepare a packaging material (Sample-1). (Sample-2) Acid-resistant paper having a basis weight of 400 g / m ² was used as a support, and a low-density polyethylene resin was used as a polyolefin resin layer on one surface of the acid-resistant paper [Mitsui Petrochemical Industry Co., Ltd.].
"Mirason 16sp"] was extruded and laminated to form a resin layer having a thickness of 20 μm to form a base material layer of a two-layer laminate.

While extruding a low-density polyethylene resin [Mirason 16sp, manufactured by Mitsui Petrochemical Industry Co., Ltd.] on one exposed surface of the paper of the base material layer, the following coextrusion film was heat-fused and laminated. Packaging material (sample-
2) was created. This laminating method is usually called polysand.

Composition of coextrusion film (thickness 35 μm) Low density polyethylene (thickness 10 μm) / adhesive polyethylene (thickness 5 μm) / nylon MXD6 (thickness 10 μm)
m) / carboxyl group-containing polyethylene (thickness 10μ
m) It should be noted that the low-density polyethylene is "Mirason 16sp" manufactured by Mitsui Petrochemical Industry Co., Ltd., and the adhesive polyethylene is "Admar AT49 manufactured by Mitsui Petrochemical Industry Co., Ltd."
9 ”, nylon MXD6 was“ MX Nylon 6007 ”manufactured by Mitsubishi Gas Chemical Industry Co., Ltd., and carboxyl group-containing polyethylene resin was“ Nucrel 0908C ”manufactured by Mitsui DuPont Polychemical Co., Ltd. (Comparative Sample-1) Polyamide resin (nylon 6) as a barrier layer [manufactured by Mitsubishi Kasei Co., Ltd., "Novamid 103"
0 "] was used to prepare a packaging material (Comparative Sample-1) in the same manner as in Sample-1 above. (Comparative Sample-2) Ethylene-vinyl alcohol copolymer as a barrier layer [Kuraray Co., Ltd., "Eval E"]
A packaging material (Comparative Sample-2) was prepared in the same manner as Sample-1 except that the above was used.

Next, each packaging material prepared as described above was punched into a predetermined size, and then a bottomed container sample was prepared by a predetermined box making process. Each bottomed container sample was measured for barrier properties and container strength under the following measurement conditions.

The measurement results are shown in Table 1. (Measurement conditions) ・ Barrier property The bottomed container has a size of 70 mm × 70 mm and a height of 180 mm and is usually called a Gobel-top type carton, and contains liquid food such as milk and orange juice.

As the barrier property, Oxytran manufactured by Modern Control Co. was used, and the oxygen permeability per container with a bottom was measured at room temperature and normal pressure.・ Container strength A bottomed container was dropped from a height of 30 cm with its lower surface facing down, and the liquid leakage was evaluated.

[0029]

[Table 1] Examination of Results As is apparent from Table 1, the containers prepared using Sample-1 and Sample-2 have both good barrier properties and high strength. However, the container prepared using the comparative sample-1 has sufficient strength but poor barrier property, while the comparative sample-2 has good barrier property but insufficient strength.

[0030]

As is apparent from the above detailed description, according to the present invention, a barrier layer containing a semi-aromatic polyamide resin or nylon MXD6 having a good barrier property has high strength, And the container is formed by the packaging material in which the inner surface layer containing the carboxyl group-containing polyethylene resin is directly inside the barrier layer without interposing the adhesive layer, and the base material layer is provided outside the barrier layer. Therefore, the container has both barrier properties and strength, does not require end surface treatment of the packaging material, does not need to provide a reinforcing layer, and provides a barrier paper composite container manufactured at a low cost in a simplified process. be able to.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an outline of a packaging material used for a barrier paper composite container of the present invention.

FIG. 2 is a diagram showing oxygen permeability coefficients of nylon MXD6 and other resins.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Packaging material 2 ... Inner surface layer 3 ... Barrier layer 4 ... Base material layer 5 ... Support body 6 ... Resin layer 7 ... Resin layer 8 ... Adhesive layer

Claims (1)

[Claims] 1. An inner surface layer containing a carboxyl group-containing polyethylene resin, an aromatic polyamide-forming component located outside the inner surface layer and comprising an aliphatic diamine and isophthalic acid and / or terephthalic acid, and a lactam or an aliphatic compound. A barrier layer containing a semi-aromatic polyamide resin or nylon MXD6 which is a copolymer with an aliphatic polyamide-forming component consisting of a diamine and an aliphatic dicarboxylic acid, and a paper mainly located outside the barrier layer A barrier paper composite container, which is formed of a packaging material having a base material layer.