JP2000335550A - Paper container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper container capable of retort-sterilization with the suitability for a microwave oven by covering an exposed paper end face of an outer surface is exposed by an insert injection molding method to inject a thermoplastic resin in a flanged paper tray in which a cardboard on which thermoplastic sheet are laminated are drawn. SOLUTION: A blank is drawn in a tray shape to form a paper tray. An end face of a flange with an exposed end face on an outer surface of the paper tray is covered by an insert injection molding method of a thermoplastic resin to eliminate the exposure of the end face. In implementing this insert injection molding method, the paper tray is inserted in a core die 61 from an opening part side, and a cavity die 62 is mounted on an upper part of the paper tray. The heat-molten thermoplastic resin is injected as a covering member 40 from an open gate injection port 68 through a sprue 66 and a liner 67 to cover an exposed part in the end face of the paper tray. The paper capable of the retort sterilization with the suitability of the microwave oven is obtained thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper container which can be subjected to retort sterilization, and more particularly to a tray-shaped paper container which can be reheated by a microwave oven.

[0002]

2. Description of the Related Art Paper containers which can be subjected to a retort sterilization treatment are disclosed, for example, in JP-A-57-46734 and JP-A-5-46734.
Many inventions and ideas have been disclosed, including the inventions disclosed in JP-A-8-52033 and JP-A-58-20638.

[0003] The invention disclosed in Japanese Patent Application Laid-Open No. 57-46734 discloses a synthetic resin or paper mainly composed of a thermoplastic resin excluding a high-density polyethylene resin and having a melting point of 115 ° C or higher as both outer layers. The both ends of the laminated sheet made of aluminum foil are rolled and subjected to waterproofing and welded to form a cylindrical body, and the upper and lower openings of the obtained cylindrical body are formed with the synthetic resin in the laminated sheet. A container closed with a lid made of aluminum foil whose inner surface is coated with the same kind of synthetic resin, wherein the laminated sheet is a packaging container having a laminated structure in which aluminum foil is disposed on both sides of paper. Things.

Further, the invention disclosed in Japanese Patent Application Laid-Open No. 58-52033 discloses a method in which both ends corresponding to a body seal portion of a fan-shaped or square blank sheet made of a paper material subjected to a water-resistant treatment on both sides are opposite to each other over a certain width. The upper and lower parts of the body cylinder formed by folding both sides of the blank sheet so as to form a cylinder and bonding both ends at the surface having the pair of folded pieces obtained above, This is a completely water-resistant paper container sealed with a lid and a bottom plate so that the paper end surface is not exposed.

Further, in the invention disclosed in Japanese Patent Application Laid-Open No. 58-20638, the resin layer forming the inner layer and the intermediate layer made of paperboard and the like are integrally bonded, and the resin layer forming the outer layer and the intermediate layer are integrally bonded. Alternatively, the resin is bonded to each other at the upper edge of the container, the layers are degassed, and a multilayer container is formed in which an intermediate layer is sandwiched between resin layers on both sides.

However, all of these inventions have problems that they are not suitable for a microwave oven due to the heavy use of aluminum foil, and that there are still problems in the disposability due to the heavy use of synthetic resins.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems relating to a paper container capable of performing a retort sterilization treatment, and provides a paper container capable of performing a retort sterilization suitable for a microwave oven. The purpose is to.

[0008]

Means for Solving the Problems A first invention of the present invention is:
An insert for injecting thermoplastic resin that has been melted into a mold in which the paper end surface of the outer surface of a flanged paper tray formed by drawing and forming a paperboard laminated with thermoplastic sheets is inserted into a paper tray body in advance. A paper container coated by an injection molding method.

A second invention of the present invention is the paper container according to the first invention, wherein the thermoplastic sheet has a barrier layer.

[0010] A third invention of the present invention is characterized in that a portion of the outer surface of the paper tray with a flange, which is formed by drawing and forming a paperboard on which a thermoplastic plastic sheet is laminated, is covered with a thermoplastic plastic sheet. Paper container.

As described above, according to the present invention, since the end face of the paper of the paper container is covered with a thermoplastic resin sheet or a synthetic resin such as a thermoplastic resin, retort sterilization can be performed.

Further, the paper container of the present invention is made of a thermoplastic plastic sheet, paper or the like, and therefore has a microwave oven suitability.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments. FIG. 1 is an explanatory view showing a longitudinal section showing an embodiment of a paper container 100 of the present invention, FIG. 2 shows an example of a blank 10 used in the present invention, and FIG. FIG. 4 is an explanatory view showing a state in which a molding process is performed, and FIG. 4 is an explanatory view showing an example of an apparatus for injecting a thermoplastic resin by an insert injection molding method to cover a portion where an outer end face of a paper container is exposed.

The blank 10 comprises a bottom surface 11, a side surface 12, a corner 13 connected between adjacent side surfaces 12, and a flange 14 connected to the side surface 12 and the upper edge of the corner 13.
Each part is formed by punching out a paperboard, which is drawn and formed into a paper tray 10a. The corner portion 13 is provided with a pressing rule n whose interval becomes wider outward.
By providing the pressing rule n, it is possible to exactly form a corner when drawing and forming. As the paperboard, a coated ball, virgin paper or the like, or a laminated paper obtained by laminating a thermoplastic plastic sheet such as polyethylene or polypropylene on these paperboards can be preferably used.

Thermoplastic sheet 5 to be the outer surface
For 0, a film made of polyethylene, polystyrene, polyester, polypropylene, ethylene-vinyl alcohol copolymer resin, nylon or the like having a thickness of about 15 to 200 μm can be suitably used. On the other hand, the inner surface of the thermoplastic sheet 20 has a thickness of 30 to 400 μm.
m, polyethylene, polystyrene, polyester, polypropylene, ethylene vinyl alcohol copolymer resin, nylon or other plastic film,
In order to have gas barrier properties, polyester film,
A vapor-deposited film obtained by vapor-depositing a thin film of silicon oxide, aluminum oxide, or the like on a polypropylene film or a nylon film at a thickness of about 400 ° by a vacuum vapor deposition method or the like can be preferably used.

The blank 10 is drawn into a tray using a drawing die (not shown) to form a paper tray 10a as shown in FIG.

Next, the end surface of the flange 14 whose end surface is exposed on the outer surface of the paper tray 10a is covered with a thermoplastic resin by an insert injection molding method so that the end surface is not exposed.

The procedure of the insert injection molding method is as follows, for example.
As shown in FIG. 4, first, the paper tray is inserted into the core mold 61 from the opening side, and the cavity mold 62 is mounted on the paper tray. Next, the hot-melt thermoplastic resin passes through the sprue 66 and the liner 67 and is coated as the coating member 40 from the open gate injection port 68 so that the end surface of the portion where the end surface of the paper tray is exposed is not exposed. . Thus, the paper container 100 is manufactured.

The thermoplastic resin used for the covering member 40 is a block type polypropylene resin having excellent impact resistance and a small amount of eluted low molecular weight components.
Those having an FR of 8 to 30 g / min can be preferably used.

The paper container 100 (paper 1) prepared as described above
0; Laminated paper, coated member 50; block, laminated with a three-layer film consisting of 20 μm of polypropylene on the outer surface of coated ball 210 g / m ² and 50 μm of undrawn propylene / 20 μm ethylene vinyl alcohol copolymer resin / 30 μm of undrawn propylene on the inner surface Type polypropylene, MFR = 14 g / min), filled with water, [outside of container] PET film (12 μm thickness), silicon oxide evaporated thin film (400 °) / ONy film (14 μm thickness) / C
After heat-sealing a lid member made of a PP film (70 μm thick) [inside of the container], an apparatus manufactured by Hisaka Manufacturing Co., Ltd. was used, and the initial temperature was 80 ° C., and the temperature was raised to 120 ° C. for 15 minutes. When the pneumatic retort sterilization treatment was performed under the conditions of holding conditions: 30 minutes, cooling time: 30 minutes, the container had no deformation such as the shape and the retort sterilization was appropriate.

Then, after the retort sterilization treatment, heating was performed using a microwave oven having a rated voltage of 100 V and a rated frequency of 60 Hz. As a result, reheating by the microwave oven was successfully performed.

FIG. 5 is an explanatory diagram showing another embodiment of the present invention. First, as in the previous embodiment, the blank 10
Is drawn using a drawing die (not shown), and the tip of the flange 14 is bent downward to produce a paper tray 10a having a curled portion 15. Then, flange 14
In order to cover the end surface of the paper container 100, a ring-shaped thermoplastic plastic sheet 45 is inserted from under the paper tray 10a and bonded by heat sealing so that the end surface of the curled portion 15 is not exposed, and the paper container 100 is manufactured.

The thermoplastic sheet 45 has a thickness of 15
A film made of polyethylene, polystyrene, polyester, polypropylene, ethylene vinyl alcohol copolymer resin, nylon, etc. having a thickness of about 200 μm, or a silicon film, an aluminum oxide film, a polyester film, a polypropylene film, or a nylon film to have a gas barrier property. A vapor-deposited film or the like obtained by vapor-depositing a thin film of about 400 ° by a method such as a vacuum vapor deposition method can be preferably used.

The paper container 100 (paper 1) prepared as described above
0: Polypropylene film 20 μm on outer surface of coated ball 210 g / m ² , unstretched propylene 50 μm on inner surface
Laminated paper, thermoplastic sheet 4 laminated with a three-layer film consisting of m / ethylene vinyl alcohol copolymer resin 20 μm / non-stretched propylene 30 μm
5; Non-stretched polypropylene film (30 μm) is filled with water, [outside of container] PET film (12 μm thick), silicon oxide vapor-deposited thin film (400 °) / ONy film (14 μm)
m thickness) / CPP film (70 μm thickness) [inside of container], after heat-sealing the lid member, using an apparatus manufactured by Hisaka Manufacturing Co., Ltd., initial temperature: 80 ° C., temperature rising condition: 120 °
C reached 15 minutes, holding condition: 30 minutes, cooling time: 30
When the retort sterilization treatment of the aeration method was performed under the conditions of minutes, the container had no deformation such as the shape, and had the retort sterilization suitability.

Then, after the retort sterilization treatment, heating was performed using a microwave oven having a rated voltage of 100 V and a rated frequency of 60 Hz. Reheating by the microwave oven was successfully performed.

[0026]

As described above, since the paper container of the present invention is a container mainly composed of paper, it has excellent display properties and printability, and does not require a secondary container such as a plastic container.
Generation of garbage can be suppressed. Because it is a paper container, it has excellent incineration. Further, since retort sterilization treatment is possible, it can be used as a water-resistant container as a container instead of a plastic bottle around water. Also, since no aluminum foil is used, heating by a microwave oven is possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a cross-sectional view showing one embodiment of a paper container of the present invention.

FIG. 2 is a plan view showing an example of a blank used in the present invention.

FIG. 3 is an explanatory diagram showing an example of an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an example of an insert injection molding method.

FIG. 5 is an explanatory view showing another embodiment of the present invention.

[Explanation of symbols]

 10 blank 10a paper tray 11 bottom 12 side 13 corner 14 flange 15 curl 20 thermoplastic sheet 40 covering member 45 thermoplastic sheet 50 ‥‥ Thermoplastic sheet 61 ‥‥ Core mold 62 ‥‥ Cavity mold 66 ‥‥ Sprue 67 ‥‥ Liner 68 ‥‥ Open gate injection port 100 ‥‥ Paper container m ‥‥ Bending line n ‥‥ Press crease

Claims (3)

[Claims] A thermoplastic resin obtained by hot-melting a portion of an outer surface of a paper tray with a flange formed by drawing and forming a paperboard laminated with a thermoplastic plastic sheet into a mold in which a paper tray body is inserted and arranged in advance. A paper container coated by an insert injection molding method for injecting a resin. 2. The paper container according to claim 1, wherein said thermoplastic sheet has a barrier layer. 3. A paper container characterized in that a portion of a paper tray provided with a flange formed by drawing and forming a paperboard on which a thermoplastic plastic sheet is laminated is exposed, and a portion of the outer surface where the paper end face is exposed is covered with the thermoplastic plastic sheet.