JPH10297673A - Easy separation composite container - Google Patents

Abstract

(57) Abstract: In a composite container in which a plastic inner container 10 is covered with an outer container 20 mainly made of paper, the outer container 20 and the inner container 10 are firmly joined to each other, and after use of the container. An object of the present invention is to provide a recycle type composite container which can be easily separated and separated at the time of disposal. An inner container resin layer (2) laminated on an inner surface of an outer container (20) is formed of a laminate of at least two layers, and has a strength (A) for breaking a paper layer (20a) constituting the outer container (20) and an inner container (10). A tensile strength B of the innermost resin layer 2a of the laminated body which is in contact with the laminated body is a readily separable composite container having a relation of B <A, and the innermost resin layer 2a of the laminated body has adhesiveness. This is an easily separable composite container made of resin and formed by locally joining the outer container 20 and the inner container 10 at the shoulder and the bottom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite container of a combination of paper and plastic for storing liquid contents, powder contents, viscous contents, and the like. The present invention relates to the provision of an environmentally conscious composite container in which separation between an outer container made of plastic and an inner container made of plastic is remarkably facilitated and recyclability is improved.

[0002]

2. Description of the Related Art Conventionally, as containers for storing various beverages, seasonings, liquid detergents and the like, polypropylene resin (P) has been used.
Plastic containers such as P), polyethylene terephthalate resin (PET), and polyvinyl chloride resin (PVC) are widely used.

[0003] However, in recent years, the increase in waste has become a major social problem, and in addition to the problem of resource conservation and energy and resource conservation, it has become a global environmental problem. I have. As a countermeasure, a composite container (back-in-box) in which a plastic bag with a spout is housed inside a paper outer container is widely used. This container is lightweight and can be transported easily because it can be folded small when no contents are stored.In addition, the container can be reduced in volume at the time of disposal, and paper and plastic can be easily separated. This is an environmentally friendly (ecological) composite container that can be recycled individually.

However, in the case of the above-mentioned composite container (back-in-box), for example, in the production of a bag-like container with a spout, the edge portion of a single-layer or multilayer film is bonded by heat sealing or the like, and then injection-molded thereto. However, there is a disadvantage that the number of manufacturing steps is large, for example, the spout formed by the above method must be joined by means such as fusion. In addition, in terms of performance, the heat-sealed part of the film end face and the fusion part of the spout are inferior in impact resistance compared to the part outside the fusion part, and there is also a problem that the bag may break due to a drop impact. is there.

Therefore, various methods have been proposed for solving the problems of the drop impact strength and the number of manufacturing steps by forming the inner container by blow molding (Japanese Patent Application No. 6-212538). In this method, an outer container (carton) mainly composed of paper coated with an adhesive or the like on its inner surface is placed in a blow mold, and a preform heated at a molding temperature is inserted into the blow mold. A composite container is formed by combining an outer container mainly made of paper by molding and an inner container made of plastic, which is integrally formed by blow molding in a seamless manner.

As shown in FIG. 1, this composite container saves petroleum resources by making the plastic inner container (10) ultra-thin, and is easily crushed at the time of disposal (reduction of waste volume). ) And facilitates the separation and separation of the paper constituting the outer container (20) and the plastic constituting the inner container (10), so that each can be recycled. Logical) composite container.

[0007] The composite container is used after the outer container (2).
0) and the inner container (10), and more preferably to measure the recycling of plastics. Therefore, when the consumer actually separates and discards the composite container after use, the outer container (20) and the inner container (10) are separated. It is required that the container (10) can be easily separated and separated. In particular, when separating and sorting
A state in which the outer container (20) is damaged and the damaged part is joined to the inner container (10), so as to avoid a so-called paper peeling phenomenon,
It is also necessary to make consumers aware of separation and disposal.

In a conventional composite container, base paper in which a polyolefin resin such as a polyethylene resin is laminated on at least the inner surface of an outer container (20) mainly composed of paper is used, and EVA or the like is formed on the polyolefin resin. Solvent dilution type hot lacquer is applied. When the inner container (10) is formed by stretch blow molding, the outer container (20) and the inner container (10) are joined and integrated by utilizing the heat.

As described above, in this composite container, the amount of resin used as the inner container is reduced as much as possible.
Supplemented by. Therefore, the bonding strength when the outer container (20) and the inner container (10) are joined greatly affects the strength physical properties of the composite container. For example, when the bonding strength is low, it is easily affected by stress such as buckling. The outer container (20) and the inner container (10) are separated, and the strength properties of the inner container (10) cannot be compensated. In this sense, it can be said that the stronger the bonding strength between the outer container (20) and the inner container (10), the better.

For example, the strength at which the outer container (20) and the inner container (10) are not separated when a stress such as buckling is applied must be at least 6 kgf or more, preferably 10 kgf or more under a 4 mm deformation load.

On the other hand, since the composite container is a container for recycling plastic and paper or reducing the volume of waste, a consumer or the like separates the outer container (20) and the inner container (10) after using the container. Must be able to be discarded separately. However, if the bonding strength between the outer container (20) and the inner container (10) is increased due to the relationship between the strength and physical properties of the container, the outer container (20) may be separated when the outer container (20) and the inner container (10) are separated. It breaks and the damaged portion is joined to the inner container (10), which causes a phenomenon called paper peeling, which is not a preferable phenomenon for recycling plastic.

For example, the strength A that causes paper peeling, that is, the strength at which the outer container (20) is broken, is determined by the cohesive failure strength of the mainly used paper layer (20a) and the paper layer (20a) shown in FIG.
It can be considered as the total of the tensile breaking strength of the inner laminate resin layer (2) applied to the inner surface of the above. The strength A is determined by the type of the paper layer (20a) used, the type of the inner laminate resin layer (2), and the thickness thereof. More specifically, an adhesive is placed on an outer container (20) in which a low-density polyethylene resin is laminated on the inner surface of a coated ball having a basis weight of 310 g / m ² as an inner surface laminated resin layer (2) to a thickness of 25 μm. The T-peel strength of the outer container (20) coated with 1.0 g / m ² of the EVA adhesive as the layer (3) and the inner container (10) using polypropylene was measured to be about 600 gf / 15 mm. Paper peeling phenomenon occurs.

As described above, the function required for the composite container is to make it possible to easily separate and separate the outer container (20) and the inner container (10) while maintaining the strength properties of the container. For this conflicting purpose,
It is necessary to control the adhesive strength between the outer container (20) and the inner container, the type of adhesive, the type of material to be bonded, the amount of adhesive applied, the state and area of the coated surface, the bonding temperature, the pressure,
Many factors such as time need to be managed. In view of such a state, the management items are reduced as much as possible, and the outer container (20) and the inner container (10) are firmly joined,
A composite container which is easy to separate and separate at the time of disposal is desired.

[0014]

SUMMARY OF THE INVENTION The present invention satisfies the problems or needs of the prior art described above, and the object of the present invention is to provide a plastic inner container (1).
In the composite container in which the outer container (20) is covered with a paper-based outer container (20), the outer container (20) and the inner container (10) are firmly joined, and separated at the time of disposal after use of the container.
An object of the present invention is to provide a recyclable composite container that can be easily separated.

[0015]

In order to achieve the above-mentioned object, according to the present invention, a plastic inner container (10) is provided inside a paper-based outer container (20). ), The inner laminated resin layer (2) laminated on the inner surface of the outer container (20) comprises at least two or more laminates,
The relation of B <A is defined as the strength A that triggers the destruction of the paper layer constituting the outer container (20) and the tensile strength B of the innermost resin layer (2a) of the laminate in contact with the inner container (10). The composite container is characterized in that the composite container is easily separable.

According to the second aspect of the present invention, an adhesive layer (3) is attached to a joint between the inner laminated resin layer (2) laminated on the inner surface of the outer container (20) and the inner container (10).
The composite container according to claim 1 provided with:

In the invention according to claim 3, the innermost resin layer (3) of the laminate constituting the inner surface laminated resin layer (2) is provided.
0) is an easily separable composite container according to claim 1, wherein the composite container is made of an adhesive resin.

Further, in the invention according to claim 4, the outer container (20) and the inner container (10) are locally formed on the shoulder and the bottom, that is, the shoulder flap (40) and the bottom flap (30) of the outer container (20). An easily separable composite container according to any one of claims 1 to 3, wherein the composite container is joined in a simple manner.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the composite container of the present invention is a composite container (1) comprising an outer container (20) mainly composed of paper and an inner container (10) made of plastic, as shown in FIG. An inner laminate resin layer (2) laminated on the inner surface of the container (20) is composed of a laminate of at least two or more layers, and has a strength A that triggers the destruction of a paper layer constituting the outer container (20); An easily separable composite container characterized in that the tensile strength B of the innermost resin layer (2a) of the laminate in contact with the container (10) has a relationship of B <A.

Here, the paper layer (20a) can be specifically selected from a group of papers such as a wrapping paper, a magazine type, and a paperboard for a paper container. As the wrapping paper, unbleached wrapping paper and bleached wrapping paper can be used. It is possible. Further, as the paper container paperboard, it is possible to use base paper containing waste paper such as manila ball, white ball yellowboard, chipball, colored paperboard,
Base paper of 00% virgin pulp can also be used.

As the outer laminate resin layer (20b) of the outer container (20), a polyolefin resin such as a polyethylene resin or a polypropylene resin can be used. As shown in FIG. 3, the resin layer (2) in contact with the paper layer (20a) in the inner surface laminated resin layer (2) is used.
As b), besides polyolefin resins such as polyethylene resin and polypropylene resin, polyethylene terephthalate resin, polyamide resin and a barrier resin such as ethylene-vinyl alcohol copolymer alone can be selected, and It is also possible to form a multilayer structure using a composite film combining these resins. As the innermost resin layer (2a), a paper layer (20
It is possible to mix an additive, blend a resin of another component, or select a flexible resin or the like with a resin whose component is close to the resin layer (2b) in contact with a).

Here, as shown in FIG. 7, the layer structure of the conventional composite container is such that the outer container (20) and the inner container (10) are joined by an adhesive layer (3) and the outer container (20).
Is an inner laminated resin layer (2) on the inner surface of the paper layer (20a) and an outer laminated resin layer (20b) on the outer surface.
It is composed of This outer laminate resin layer (20
b) may not be provided depending on the use of the composite container.

The adhesive strength between the outer container (20) and the inner container (10) in this composite container is approximately 600 as described above.
If the gf / 15 mm is exceeded, the adhesive strength will be reduced to the outer container (20).
8, the paper layer (20a) of the outer container (20) is broken and a so-called paper peeling phenomenon occurs, as shown in FIG. It is not good separation and it is not good for recycling.

On the other hand, in the structure of the composite container of the present invention, as shown in FIG. 3, the inner laminated resin layer (2) of the outer container (20) is composed of the innermost resin layer (2a) and the paper layer (2).
0a) and the resin layer (2b) in contact with the paper layer (20a).
Between the tensile strength at break B of the innermost resin layer (2a) and B
By having the relationship of <A, as shown in FIG. 4, the innermost resin layer (2) is formed before the outer container (20) causes the paper peeling phenomenon.
a) is broken, and the outer container (20) and the inner container (10) are separated well, so that a composite container suitable for recycling can be obtained.

According to the second aspect of the present invention, as shown in FIG. 3, the second container laminated on the inner surface of the outer container (20).
This is an easy-separable composite container in which an adhesive layer (3) is provided at the joint between the inner laminate resin layer (2) composed of at least two layers and the inner container (10).

As the adhesive layer (3), a solvent-dilutable EVA-based, polyolefin-based, polyester-based hot lacquer, emulsion-based adhesive, heat-sensitive adhesive, pressure-sensitive adhesive, reactive adhesive, or the like is used. The coating method can be selected according to the type of the adhesive to be used, such as a gravure coat, a roll coat, and a reverse coat. The coated part of this adhesive layer (3) is shown in FIG.
By bonding to only the bottom flap (30) and the shoulder flap (40) shown in FIG. 1, or by controlling the bonding area by forming the coating pattern into a dot shape or a stripe shape, the separability is improved. .

In the composite container of the present invention, the outer container (20)
When the inner container (10) is separated from the inner container (10), a damaged portion of the innermost resin layer (2a) remains in the inner container (10). However, this problem also involves selecting a resin having good compatibility with the resin used as the inner container (10). This makes it possible to recycle the resin used as the inner container (10). However, considering the recycling of plastic, it is preferable to use an adhesive resin rather than an adhesive as the adhesive layer (3).

According to the third aspect of the present invention, the innermost resin layer (30) of the laminate constituting the inner laminate resin layer (2) is made of an adhesive resin. This is an easily separable composite container.

This is, as shown in FIG.
In order to join the inner container (10) and the inner container (10), an adhesive resin is used as the innermost resin layer (2a) of the outer container (20). Adhesive-type adhesive resin obtained by adding a tackifier to low-density polyethylene, adhesive resin obtained by copolymerizing polyethylene with acrylic acid ester (or methacrylic acid ester) and maleic anhydride or ester component, or polyolefin resin An adhesive resin obtained by graft polymerization of maleic anhydride can be used, and a thermoplastic elastomer such as a low- or non-crystalline ethylene-α-olefin copolymer may be used depending on the type of the resin used for the inner container 2. It is possible.

In the structure of the composite container in this case, the outer container (20) and the inner container (10) are partially joined so that the outer container (20) and the inner container (10) can be easily separated and separated. It is preferable to use a silicone-based release agent, a varnish, or an ink (urethane-based) commonly used for printing so that the adhesive resin can exert its performance on the shoulder flap (40) and the bottom flap (30) of the composite container. , Nitrocellulose-based, polyamide-based, acrylic-based, etc.) as a release agent layer (50) on the part where the outer container (20) and the inner container (10) are not required to be adhered to each other. The container (10) is partially joined. By forming the bonding pattern at this time in a dot shape or a stripe shape, a composite container that can be more easily separated can be obtained.

The separated state of the composite container having the above structure is as follows.
As shown in FIG. 5, the innermost resin layer (2a) is broken before the outer container (20) causes a paper peeling phenomenon.
The inner container (10) and the inner container (10) provide good separation, so that a composite container suitable for recycling can be obtained.

On the other hand, the inner container (10) is made of a stretch-blown resin such as a polyethylene resin, a polypropylene resin, a cyclic polyolefin resin, a polymethylpentene resin, a polyethylene terephthalate resin, a polyethylene naphthalate resin, a mixture thereof, or a polyacrylonitrile resin. Any type of resin can be used as long as it can be molded. Further, the material of these composite containers may be a single layer or a multilayer structure.

[0033]

Next, the present invention will be described more specifically with reference to examples. <Example 1> A 100% virgin pulp base paper (basis weight 310 g / m ² ) was used as the paper layer (20a).
The resin layer (2b) in contact with a) and the outer laminate resin layer (20b) have a tensile breaking strength of 150 kg / c.
The low-density polyethylene resin of m ² was laminated. On the resin layer (2b), a resin layer having adhesiveness to the inner container (10) is used as an innermost resin layer (2a), and a low crystalline linear low density (density: 77 kg / cm ² ) is obtained. d = 0.87 / cm ³ ) 15 polyethylene resin
It was laminated with a thickness of μm. After that, the release agent layer (5
6) As shown in FIG. 6, a nitrocellulose-based gravure ink is gravure-printed as shown in FIG. 6, and the entire body (4), bottom flap (30) and shoulder flap (4) of the composite container are provided.
0) was applied so that the portion joined to the inner container (10) was in a dot shape. This base paper was cut into blanks, and then an outer container (20) was prepared by heat sealing. Thereafter, the outer container (20) is set in a mold of a biaxial stretch blow molding machine, and a preform obtained by injection molding using a polypropylene resin is heated and stretched by an infrared heater mounted on the biaxial stretch blow molding machine. A composite container was obtained by blow molding.

The center portion of the shoulder flap (40) of this composite container was sampled in a lengthwise direction with a width of 15 mm, and was subjected to JIS-K-
As a result of performing a T-type peeling test according to 6854 “Testing method of peeling adhesive strength of adhesive”, no paper peeling phenomenon occurred, and the innermost resin layer (dots) joined to the inner container (10) in a dot shape When 2a) was broken, separation occurred, and the peel strength was 500 kgf / 15 mm. The buckling strength was 11 kgf under a 4 mm deformation load, and the strength properties of the container were maintained.

<Example 2> The basis weight of the paper layer (20a) was 3
Using a coated ball base paper of 10 g / m ² , a composite container was prepared in the same manner as in Example 1.

The coated ball base paper is inferior to the 100% virgin pulp base paper in the strength of the paper. However, as a result of performing a T-peel test on the composite container having this configuration in the same manner as in Example 1, cohesive failure of the paper layer (20a) of the coated ball base paper occurred, but the paper peeling phenomenon did not occur. The peel strength at this time was the same as in Example 1 and the innermost resin layer (2
When a) is broken, 500 g
f / 15 mm. Further, the buckling strength was such that the strength of the paper itself was reduced, and the 4 mm deformation load was 9 kgf, but the strength physical properties of the container were maintained.

<Embodiment 3> As the paper layer (20a), 10
Using a 0% virgin pulp base paper (basis weight 310 g / m ² ), low-density polyethylene is applied to the innermost resin layer (2a).
As a resin layer (2b) in contact with the inner container (10), a linear low-density polyethylene resin having a tensile breaking strength of 200 kg / cm ² was laminated to a thickness of 15 μm. On the resin layer (2b), a linear linear low-density polyethylene resin having a tensile rupture strength of 120 kg / cm ² was further laminated as an innermost resin layer (2a) to a thickness of 15 μm. Further, on this innermost resin layer (2a), as shown in FIG.
1. A hot color of A system is applied to the shoulder flap (40) and the bottom flap (30) in dot form by gravure printing.
Coating of 0 g / m ² was performed, and an outer container (20) was produced by heat sealing. The outer container (20) is set in a mold of a biaxial stretch blow molding machine, and a preform obtained by injection molding using a polyethylene terephthalate resin is heated and stretched by an infrared heater mounted on the biaxial stretch blow molding machine. A composite container was obtained by blow molding.

The composite container of this configuration also has a T
As a result of the mold release test, no paper peeling phenomenon was observed. The peel strength at this time was 600 gf / 15 mm. The buckling strength was 16 kgf under a 4 mm deformation load, and the strength physical properties of the container were maintained.

<Comparative Example 1> As the paper layer (20a), 10
Using a 0% virgin pulp base paper (basis weight 310 g / m ² ), a polyethylene resin was laminated as the outer laminate resin layer (20a) and the inner laminate resin layer (2) shown in FIG. Then the inner surface laminated resin layer (2)
EVA hot color is coated on the shoulder flap (40) and the bottom flap (30) in dot form by gravure printing at a coating amount of 2.0 g / m ² , and the outer container ( 20) was produced. The outer container (20) is set in a mold of a biaxial stretch blow molding machine, and a preform obtained by injection molding using a polyethylene terephthalate resin is heated and stretched by an infrared heater mounted on the biaxial stretch blow molding machine. A composite container was obtained by blow molding.

In the composite container having this structure, since the adhesive strength between the inner laminated resin layer (2) and the inner container (10) was strong, a peeling phenomenon occurred as a result of a T-type peel test. The peeling strength at this time was 800 gf / 15 mm.

<Comparative Example 2> Basis weight 3 as paper layer (20a)
A coated ball base paper of 10 g / m ^2, a polyethylene resin as an outer laminated resin layer (20b) on its surface, and a low-crystalline straight line having a tensile breaking strength of 77 kg / cm ² as an inner laminated resin layer (2) on its back surface. A linear low density (density d = 0.87 g / cm ³ ) polyethylene resin was laminated to a thickness of 15 m. Then release agent layer (50)
As shown in FIG. 6, a nitrocellulose-based gravure ink is gravure-printed, as shown in FIG. 6, the entire body (4), bottom flap (30) and shoulder flap (40) of the outer container (20).
Was applied to the portion excluding the dot pattern. Then 2
The composite container is set in a mold of an axial stretch blow molding machine, and subjected to heat stretch blow molding of a preform obtained by injection molding using a polypropylene resin with an infrared heater mounted on a biaxial stretch blow molding machine. I got

The composite container of this configuration also has a T
As a result of the mold release test, the inner laminate resin layer (2)
Although the inner container (10) and the inner container (10) are adhered to each other, the paper peeling phenomenon occurs because the breaking strength of the inner laminate resin layer (2) and the paper layer (20a) is low. Its strength is 500gf / 15
mm.

[0043]

As described above, the present invention has the following effects. That is, in a composite container in which a plastic inner container is joined to the inside of an outer container mainly composed of paper, a resin layer laminated on the inner surface of the outer container is formed of a laminate of at least two or more layers. And the tensile strength B of the innermost resin layer in contact with the inner container is B <A,
By interposing the innermost resin layer, which is easily broken, there is no need for careful management of the adhesive strength, and while maintaining sufficient adhesive strength, the paper peeling phenomenon occurs when the outer container and the inner container are separated and separated. It is possible to provide an environment-friendly and easily separable composite container which is free of paper and plastic and has high recyclability.

Further, an adhesive layer may be provided at a joint portion between the resin layer laminated on the inner surface of the outer container and the inner container, or the innermost resin layer may be made of a resin having an adhesive property. Locally joined at the shoulder and bottom, making it easier for consumers and others to separate, separate and dispose of the outer and inner containers after use of the container, making it the ultimate recyclable, easily separable composite Containers can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of the entire composite container according to the present invention in a side cross section.

FIG. 2 is a side sectional view of a composite container showing one embodiment of the present invention.

FIG. 3 is a side sectional view of another composite container showing an embodiment of the present invention.

FIG. 4 is an explanatory view showing a cross section of a sheet of a composite container according to an embodiment of the present invention.

FIG. 5 is an explanatory view showing a cross section of another composite container showing an embodiment of the present invention in a side cross section.

FIG. 6 is an explanatory view of a blank sheet of an outer container showing an adhesive portion of the composite container showing one embodiment of the present invention.

FIG. 7 is an explanatory view showing an example of a conventional composite container according to the present invention in a side cross section.

FIG. 8 is an explanatory view showing a cross section of a conventional composite container according to the present invention in the form of a paper strip.

[Explanation of symbols]

 1 composite container 2 inner laminated resin layer 2a innermost resin layer 2b resin layer in contact with paper layer 3 adhesive layer 4 body of composite container 10 inner container 20 Outer container 20a ‥‥ Paper layer 20b ‥‥ Outer surface laminated resin layer 30 ‥‥ Bottom flap 40 ‥‥ Shoulder flap 50 ‥‥ Release agent layer

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hiroshi Kawasaki 1-5-1, Taito, Taito-ku, Tokyo Letterpress Printing Co., Ltd.

Claims (4)

[Claims] 1. A composite container in which a plastic inner container is joined to an inner side of a paper-based outer container,
The resin layer laminated on the inner surface of the outer container is formed of a laminate of at least two or more layers, and the strength A serving as a trigger for breaking the paper layer constituting the outer container, and the innermost resin of the laminate in contact with the inner container An easily separable composite container, wherein the tensile strength B of the layers is in a relationship of B <A. 2. The easily separable composite container according to claim 1, wherein an adhesive layer is provided at a joint portion between the resin layer laminated on the inner surface of the outer container and the inner container. 3. The easily separable composite container according to claim 1, wherein the innermost resin layer of the laminate is made of an adhesive resin. 4. The easily separable composite container according to claim 1, wherein the outer container and the inner container are locally joined at a shoulder and a bottom.