JP3666217B2 - Waterproof composite paper container - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a composite container for liquid using a composite material mainly composed of paper, and more particularly to a molding technique for a composite paper container having complete waterproofness.
[0002]
[Prior art]
In recent years, a composite container made mainly of paper has been demanded as an ecology container instead of a plastic container or a metal container due to a problem of resources or an increase in waste. As a response to this demand, conventionally, a composite paper container made of a sheet-like material mainly made of paper is known. As shown in FIG. 7, a general paper (100) for the composite paper container is generally used. The configuration is such that the outermost thermoplastic resin layer (50) is applied to the outer surface of the paperboard layer (30) and the innermost thermoplastic resin layer (10) is applied to the inner surface, which requires long-term storage of the contents. In this case, it is common to provide a barrier layer (20) that blocks oxygen, water vapor and the like between the paperboard layer (30) and the innermost thermoplastic resin layer (10).
[0003]
First, as shown in FIG. 6 (a), the composite paper container is molded by using a side plate (2) blank (in this case, a cup-shaped container) using the composite paper container base paper (100). The outermost thermoplastic resin layer as shown in FIG. 7, which is a resin film of the seal portion (60), in which one or both of the seal portions (60) at both ends (2b) of FIG. (50) and the innermost thermoplastic resin layer (10) are melted. Subsequently, the side plate (2) blank is immediately wound around a mandrel (die), and the seal portion (60) is press-fused.
[0004]
Next, as shown in FIG. 6 (b), the bottom plate (3) is attached to the side plate (2) press-fused as described above, and the bent peripheral end (3a) of the bottom plate (3) is connected with hot air. 6), immediately squeeze and squeeze the lower end (2a) of the side plate (2) as shown in FIG. 6 (c), and fuse and integrate with the peripheral end (3a) of the bottom plate (3). The upper end portion (2c) of the face plate (2) is subjected to top curl (flange) by embossing to form a composite paper container (1).
[0005]
[Problems to be solved by the invention]
However, in the above prior art, the cardboard layer (30) is exposed on the end faces (2e, 2g, 3e) of the side plate (2) and the bottom plate (3) using the composite paper container base paper (100). Therefore, there has been a problem that the liquid which is the content permeates from the cardboard layer (30) or hot water by retorting penetrates and the composite paper container is broken. Further, depending on the type (melting point, etc.) of the outermost thermoplastic resin layer (50) and the innermost thermoplastic resin layer (10) forming the base paper (100) for the composite paper container, the side plate (2) is sealed. In addition, when winding the side plate (2) and the bottom plate (3) together, pinholes are generated in the outermost thermoplastic resin layer (50) in the vicinity of the winding portion in combination with the heat of hot air and press stress. Since the paper surface of the cardboard layer (30) is exposed, there is a problem that a problem (water or the like permeates from the pinhole) occurs in the retort processing.
[0006]
The present invention solves the problems of the prior art, and the problem is that the end faces of the side plate (2) and the bottom plate (3) constituting the waterproof composite paper container mainly made of paper. Or providing a waterproof composite paper container that does not penetrate water or the like from a pinhole generated in the outermost thermoplastic resin layer (50) in the vicinity of winding.
[0007]
[Means for Solving the Problems]
In order to achieve the above object in the present invention, first, in the invention of claim 1, at least the outermost thermoplastic resin layer (50) on the outer surface of the cardboard layer (30) and the innermost thermoplastic resin layer ( 10) is used as the side plate (2) and the bottom plate (3) using the composite paper container base paper (100), and the side plate (2) whose both ends (2b) are sealed by the seal portion (60) And the bottom plate (3), a composite paper container formed by integrating the lower end (2a) of the side plate (2) and the peripheral end (3a) of the bottom plate (3),
The edge faces of both side edges of the side plate are edge protected,
Furthermore, the end surface (2g) of the upper end part of the side plate (2) is covered with an injection resin layer,
And the lower end part and its end surface (2e) which are bent inside the side plate (2) and folded back, and the peripheral end part and its end surface (3e) which are folded and bent outside the bottom plate (3). An injection resin layer is formed by insert injection molding so as to cover and integrated at the bottom, and the end surface (2e) of the lower end of the side plate and the end surface (2g) of the bottom plate are covered with the injection resin layer. This is a waterproof composite paper container.
[0008]
According to a second aspect of the invention, the waterproof composite paper container according to the first aspect of the invention is characterized in that the end faces of both side ends (2b) of the side plate (2) are covered with a protective tape to be edge protected. It is what.
[0009]
According to a third aspect of the invention, the side plate (2) is folded inward and folded back to the upper end (2c) and its end surface (2g) or the side plate (2) horizontally and folded. The waterproof composite paper container is characterized in that an injection resin layer is formed by insert injection molding so as to cover the upper end (2c) and the end surface (2g) thereof, thereby forming a flange at the container mouth. is there.
[0010]
Furthermore, in the invention of claim 4, the injection resin layer is the same kind as the innermost thermoplastic resin layer (10) and the outermost thermoplastic resin layer (50) forming the base paper (100) for the composite paper container. It is a waterproof composite paper container characterized by comprising a resin.
[0011]
The above-mentioned insert injection molding means that an insert product is obtained by inserting paper, cardboard, plastic film, aluminum foil, or a bonded product of these into an injection mold in advance, clamping the mold, injecting molten injection resin, and cooling. The insert according to the present invention is a side plate and a bottom plate using a composite paper container base paper made of cardboard and a plastic film.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
First, as shown in FIG. 7, the waterproof composite paper container of the present invention has at least an outermost thermoplastic resin layer (50) on the outer surface of the cardboard layer (30) and an innermost thermoplastic resin layer (10) on the inner surface. As shown in FIG. 1, the composite paper container base paper (100) thus formed is used as a side plate (2) and a bottom plate (3), and both side ends (2b) are sealed by a seal portion (60). Combining a side plate (2) and the bottom plate (3), a composite paper container mainly composed of paper formed by integrating the lower end (2a) of the side plate and the peripheral end (3a) of the bottom plate, As shown in the enlarged view of the seal portion (60) in FIG. 2, the protective tape in which the both side ends (2b) and the end surfaces (2d) are provided with a transparent barrier layer between at least two thermoplastic resin films. (200) is a waterproof composite paper container (1).
[0013]
Further, as shown in FIG. 3, the protection tape (200) has a transparent barrier layer (20a) between at least two thermoplastic resin films (70). The plastic resin film (70) is made of the same kind of thermoplastic resin as the innermost thermoplastic resin layer (10) and the outermost thermoplastic resin layer (50) forming the composite paper container base paper (100). .
[0014]
The seal portion (60) of the side plate (2) having the above-described configuration is heat-pressed into a cylindrical shape so that the seal portion (60) is easily fixed and at least both side ends of the side plate (2). (2b) and its end face (2d) can completely prevent the penetration of contents and hot water for retort processing.
[0015]
Further, as shown in FIG. 4, the side plate (2) is folded inside and folded back to the lower end (2a) and its end surface (2e) and outside the bottom plate (3) and folded. A molten injection resin is injected by insert injection molding so as to cover the peripheral end (3a) and its end surface (3e), and an injection resin layer (80) is formed to integrate the side plate (2) and the bottom plate (3). Into the bottom (300).
[0016]
Furthermore, as shown in FIG. 5 (a) (inner flange type), the upper end portion (2c) and its end surface (2g) folded back and folded inside the side plate (2), or FIG. As shown in (b) (outside flange type), melted by insert injection molding so that the upper end (2c) and its end face (2g) are folded back horizontally on the side plate (2). The injection resin is injected to form the injection resin layer (80) to form the flange portion (400) at the container mouth.
[0017]
The injection resin layer (80) described above is made of the same type of resin as the innermost thermoplastic resin layer (10) and the outermost thermoplastic resin layer (50) forming the base paper (100) for the composite paper container. It is characterized by.
[0018]
By using the bottom portion (300) having the structure as shown in FIG. 4 above, the side plate (2) and the bottom plate (3) are completely fixed, and at least the lower end portion (2a) of the side plate (2) and its From the end surface (2e) and the peripheral end portion (3a) of the bottom plate (3) and its end surface (3e), penetration of water from outside such as hot water for retorting can be completely prevented.
[0019]
Further, as described above, by using the flange portion (400) at the container mouth having the structure as shown in FIGS. 5 (a) and 5 (b), at least the upper end portion (2c) of the side plate (2). It can completely prevent penetration of contents and hot water for retorting from the end face (2g), and a cover (not shown) such as a thin plastic film is provided on the flange (400) at the container mouth. It can be easily sealed.
[0020]
That is, as shown in FIG. 1, in the present invention, the above-described configuration and measures are taken for the seal portion (60) of the side plate (2), the bottom portion (300) of the container, and the flange portion (400) at the container mouth. This occurs from the end face of the side plate (2) and bottom plate (3) (the thick paper layer exposed on the bottom plate (3)) constituting the composite paper container mainly composed of paper or in the outermost thermoplastic resin layer near the winding It is possible to provide a waterproof composite paper container (1) that does not penetrate water or the like from the pinhole.
[0021]
Here, as the outermost thermoplastic resin layer (50) and the innermost thermoplastic resin layer (10), in the case of a general liquid cup-shaped composite container, a low density polyethylene film (LDPE) having a thickness of 30 μm to 70 μm. In the case of a composite paper container for retort, an unstretched polypropylene (cast polypropylene) film (CPP) having a relatively high melting point and a thickness of 30 μm to 70 μm is used. Among them, in particular, a block copolymerized polypropylene cast film (B? CPP) or a random block copolymerized polypropylene cast film (R? CPP) is more preferably used as a high impact resistant film for high retort.
[0022]
For the resin film forming the outermost thermoplastic resin layer (50) and the innermost thermoplastic resin layer (10), the resin for forming the injection resin layer (80) of the present invention is generally used for liquids. For composite paper containers, outermost thermoplastic resin layer such as linear low density polyethylene resin (L? LDPE), low density polyethylene resin (LDPE), medium density polyethylene resin (MDPE), high density polyethylene resin (HDPE) (50) and the same type of resin as the resin film forming the innermost thermoplastic resin layer (10). In the case of a composite paper container for retort, block copolymer polypropylene resin (B? CPP), random block copolymer Outermost thermoplastic resin layer (50) and innermost thermoplastic resin layer (1) such as polymerized polypropylene resin (R? CPP), homopolypropylene resin (PP) ) Resin film of the same kind as the resin forming the preferably used. In this case, the outermost thermoplastic resin layer (50) or the innermost thermoplastic resin layer (10) and the injection resin layer (80) are easily fixed by thermocompression bonding.
[0023]
Further, as the thermoplastic resin film (70) for forming the protective tape (200) shown in FIG. 3, the above-mentioned injection resin layer (80) is used for both a general liquid composite paper container and a retort composite paper container. And a thermoplastic resin film (70) made of the same resin corresponding to each of the outermost thermoplastic resin layer (50) or the innermost thermoplastic resin layer (10) and this heat. The plastic resin film (70) is easily fixed by thermocompression bonding.
[0024]
Further, as the transparent barrier layer (20a) for forming the protective tape (200) shown in FIG. 3, silicon oxide or aluminum oxide is made of polyethylene terephthalate film (PET), nylon film (Ny), biaxially oriented polypropylene film (OPP). For example, an ethylene / vinyl alcohol copolymer may be used as the base film. Thus, by making it transparent, the discomfort of the protective tape (200) is eliminated on the surface of the waterproof composite paper container (1).
[0025]
Moreover, as a barrier layer (20) shown in FIG. 7, in addition to the same material structure as the transparent barrier layer (20a), there are eval, polyvinylidene chloride and the like, and aluminum foil may be used because transparency is not necessary. However, due to the recent waste problems, aluminum foil tends to be avoided in recent years because there is a problem that aluminum ingots damage the fire grate etc. in the furnace or make it move badly during waste incineration. Those obtained by vapor-depositing silicon oxide as described above are preferred.
[0026]
Further, as the paperboard layer (30) which is the main material of the base paper (100) for the composite paper container shown in FIG. 7, a cup base paper having a basis weight of 280 g / m 2 to 320 g / m 2 is preferably used particularly for foods, and 12 g A cup base paper having a diatomaceous earth coat layer of / m 2 to 18 g / m 2 is more preferable. In addition to foods such as for bath preparations, coat manila, coat ivory, and coat balls having a basis weight of about 210 g / m 2 to 320 g / m 2 can also be used in addition to the cup base paper.
[0027]
The shape of the waterproof composite paper container (1) of the present invention is not limited to the shape such as a cylindrical shape or a rectangular tube shape other than the cup shape as shown in FIG.
[0028]
【The invention's effect】
Since this invention is the above structure, there exist the following effects.
That is, at least the outermost thermoplastic resin layer on the outer surface of the cardboard layer and the base paper for the composite paper container formed with the innermost thermoplastic resin layer on the inner surface are used as the side plate and the bottom plate, and both side ends are sealed by the seal portions. A composite paper container mainly composed of paper in which a side plate and a bottom plate are combined and a lower end portion of the side plate and a peripheral end portion of the bottom plate are integrated, and the end surfaces of both side ends are edge protected. Therefore, the seal part of the side plate is heated and pressure-bonded into a cylindrical shape so that the seal part is easily fixed and at least completely penetrates the contents and hot water for retorting from both sides of the side plate. Can be prevented.
[0028]
Furthermore, the end surface of the upper end of the side plate is covered with an injection resin layer, bent to the inside of the side plate, folded to the lower end portion and its end surface and the outer side of the bottom plate, and folded back. Injecting molten injection resin by insert injection molding so as to cover the end and its end surface, forming the injection resin layer and integrating the side plate and the bottom plate to form the bottom, the side plate and the bottom plate are completely fixed Further, it is possible to completely prevent permeation of contents and hot water for retorting from the lower end portion and its end surface of the side plate, the peripheral end portion and its end surface of the bottom plate, and the end surface of the upper end portion of the side plate.
[0030]
And, since the penetration of the contents and hot water for retort processing etc. was completely prevented from both side ends and upper and lower ends of the side plate and the peripheral end portion end surface of the bottom plate in this way, as a container for containing these retort foods, etc. Is optimal.
[0031]
As an incidental effect, a lid material such as a thin plastic film can be easily sealed on the flange portion at the container mouth.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a part of a waterproof composite paper container showing an embodiment of the present invention in a side cross section and a part in front.
FIG. 2 is an explanatory view showing a seal part of a waterproof composite paper container showing an embodiment of the present invention in a side section.
FIG. 3 is a side sectional view showing a protective tape applied to a waterproof composite paper container showing an embodiment of the present invention.
FIG. 4 is an explanatory view showing a bottom part of a waterproof composite paper container showing one embodiment of the present invention in a side section.
FIG. 5 is an explanatory view showing a flange portion at a container mouth of a waterproof composite paper container showing an embodiment of the present invention in a side cross section, and (a) is an explanatory view of an inner flange type.
(B) is explanatory drawing of an outer flange type.
FIG. 6 is a diagram for explaining a molding procedure of a composite paper container according to the present invention, and (a) is an explanatory diagram showing a blank of a side plate.
(B) is explanatory drawing of the procedure which attaches a baseplate to a side plate.
(C) is a figure explaining the procedure which winds and squeezes a side plate and a bottom plate and press-bonds.
FIG. 7 is an explanatory view showing a base paper of a composite paper container according to the present invention in a side cross section.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Waterproof composite paper container 2 ... Side plate 2a ... Lower end part of side plate 2b ... Both side ends of side plate 2c ... Upper end part of side plate 2d ... End face of both side ends of side plate 2e ... End face of the lower end of the side plate 2g ... End face of the upper end of the side plate 3 ... Bottom plate 3a ... Peripheral end of the bottom plate 3e ... End face of the peripheral end of the bottom plate 10 ... Innermost thermoplastic resin layer 20 ... ...... Barrier layer 20a ... Transparent barrier layer 30 ... Cardboard layer 50 ... Outermost thermoplastic resin layer 60 ... Sealing part 70 ... Thermoplastic resin film 80 ... Injection resin layer 100 ... Base paper 200 for composite paper containers ...... Protective tape 300 ... Bottom of container 400 ... Flange of container mouth

Claims (4)

The base paper for composite paper container is formed by using at least the outermost thermoplastic resin layer on the outer surface of the cardboard layer and the innermost thermoplastic resin layer on the inner surface, and the side plate and the bottom plate are used. A composite paper container in which a side plate and the bottom plate are combined, and a lower end portion of the side plate and a peripheral end portion of the bottom plate are integrated,
The edge faces of both side edges of the side plate are edge protected,
Furthermore, the end surface of the upper end portion of the side plate is covered with an injection resin layer,
In addition, the injection resin layer is formed by insert injection molding so as to cover the folded lower end and the end face thereof and the outer end of the bottom plate and the folded peripheral end and the end face thereof. A waterproof composite paper container formed and integrated at the bottom, wherein an end surface of a lower end portion of the side plate and an end surface of the bottom plate are covered with the injection resin layer .   2. The waterproof composite paper container according to claim 1, wherein end faces of both side ends of the side plate are covered with a protection tape to be edge protected.   The injection resin layer is formed by insert injection molding so as to cover the upper end portion and its end surface folded and folded inside the side plate, or the upper end portion and its end surface folded horizontally outside the side plate. The waterproof composite paper container according to claim 1 or 2, wherein the waterproof composite paper container is formed into a flange portion at a container mouth.   The said injection resin layer consists of resin of the same kind as the innermost thermoplastic resin layer and outermost thermoplastic resin layer which form the said base paper for composite paper containers, The any one of Claims 1-3 characterized by the above-mentioned. Waterproof composite paper container.

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