JP3110081B2 - Container manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention mainly relates to side dishes, soups,
The present invention relates to a container used for heat sterilization of boil, retort, etc. of desserts or the like, or a container for foods to be used for heating and drinking by using an electronic synth or the like at the time of use.
The present invention relates to a method for easily and inexpensively manufacturing a heat-insulated container with legs that can withstand the above-mentioned heating and can be handled directly by hand when used.

[0002]

2. Description of the Related Art Conventionally, injection-molded containers are generally and widely used as legs-mounted containers for food packaging made of synthetic resin. However, these containers are made of a single synthetic resin because molding is performed by an injection molding method, and in order to obtain a high gas barrier property required as a food packaging container, the container must be made thick. In addition, even if the synthetic resin having good fluidity used for injection molding has a large thickness, the gas barrier property of the synthetic resin used has a large effect, and a container having a high gas barrier property has not been obtained. In addition, there is an inconvenience that the thickness of the container increases the cost of the container. Furthermore, in injection molding, a molding die is also expensive, which also causes an increase in cost.

[0003] Various attempts have been made in the past to produce these legged containers by a method other than injection molding, but a complete method of producing containers premised on heating has not yet been obtained. For example, Japanese Patent Publication No. 39-807 describes a method and an apparatus for manufacturing cups and similar containers made of thermoplastic materials.
As described in Japanese Patent Publication No. 8 (1994), this technique is a method of forming a cup-shaped product and an apparatus relating to the method. The structure of the part is to form simply folded legs with a shape that is widened in the outer diameter direction of the bottom part. In these legs, the insides of the legs are not welded to each other, and these containers In the case of heating, these folded portions are deformed or become groove-shaped at the time of heating, so that the content food enters the inside of these folded portions. Further, Japanese Utility Model Publication No. 45-27564 is disclosed as a container shape having a folded portion, but this relates to a double container,
The outer container is provided with a folded leg to improve the tackiness, and has a structure in which the storage container is completely covered with an inner container to completely prevent the contents flowing into the gap between the folded legs. .

Further, Japanese Utility Model Application Laid-Open No. 58-143308 discloses a technique of folding the bottom of a container made of a synthetic resin foam sheet to form a thread tail, but this technique involves providing a gap in the folded portion. This is based on a concept completely different from the object of the present invention.
Furthermore, the inventors of the present application proposed a container with legs and a method of manufacturing the container with legs disclosed in Japanese Patent Application Laid-Open No. 61-9304, but these containers physically wrap the upper edge of the folded inner peripheral plate in a liquid-tight manner. It was merely a matter of contact, and it was quite difficult to completely bond these inscribed parts. Further, it is found that leaving the hollow portion partially hollow without completely extruding the air in the folded portion may cause a deformation of the container when heating at the time of heating and sterilizing the food or drink as the contents, or the container may be deformed. The present invention has been accomplished through intensive studies to improve these disadvantages.

As described above, in the method of manufacturing a container with legs by injection molding, it is made of a single synthetic resin, and it is very difficult to provide characteristics suitable for each content. In particular, providing a gas barrier property is a problem from the viewpoint of the cost of the container, and in any case where a folded portion is provided by a method other than injection molding to form a leg, the peripheral edge of the upper end of the folded portion is completely welded. Therefore, when heated by a microwave oven or the like at the time of heat sterilization or eating and drinking, there is a disadvantage that these upper peripheral edges are deformed, the gap is widened, and the contents enter the gap.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a container with legs which can be easily and inexpensively molded in response to heat sterilization or heating by a microwave oven. .

[0007]

According to the present invention, an opening 1 is provided at the top.
To form a leg 8 formed by a folded portion over a part or the entire circumference of a bottom surface of a mold for vacuum, air pressure or vacuum / pressure air forming comprising a side wall portion 2 and a bottom surface portion. Using a mold having a bottom portion 3 capable of being pushed up, a single-layer or composite multilayer sheet that can withstand heating of 90 ° C. or more is used as an outer sheet, and a single-layer sheet or a composite multilayer sheet having a lower softening temperature than this outer sheet is used. Using the laminated sheet as the inner sheet, the forming temperature is equal to or higher than the temperature at which the inner sheet can be welded and the forming temperature of the outer sheet is within the temperature range that can be formed. By pushing up the bottom portion 3 which can be pushed up while the temperature is within the temperature range where welding is possible, the folded portion 8 which is welded to the bottom portion of the container over the entire circumference is formed. It is to provide a manufacturing method of.

Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 shows an example of a molding die used for molding according to the present invention. The molding die includes a side wall portion 2 and a bottom surface portion 3, and the bottom surface portion 2 has a driving source 4 such as an air cylinder.
And the mechanism is movable upward. Outside the contact portion between the sliding portion of the side wall portion 2 and the bottom portion 3, there is formed a minute concave portion 5 which serves as a kick for forming the laminated sheet and forming the folded portion 8 serving as a leg. I have. FIG. 2 is a cross-sectional view showing a state in which the bottom surface 3 is pushed up within a temperature range in which the inner sheet 7 immediately after being formed by the forming die of FIG. 1 can be welded. By pushing up the bottom portion 3, the folded portion 8 serving as a leg is easily formed with the concave portion 5 of the mold as a base point. In particular, in vacuum forming and vacuum pressure forming, it is desirable to provide a vacuum suction section (not shown) also in the concave portion 5. Also bottom 3
The movable range is naturally determined by the shape of the intended container.

FIG. 3 is an enlarged view of a portion where a folded portion 8 to be a leg is formed in a molding die used in the present invention. The width t of the portion for forming the folded portion 8 is determined depending on the shape of the intended container, and as an essential condition for this determination, the thickness of the laminated sheet stretched to form the bottom portion in FIG. It is necessary that the thickness is not more than twice, and not more than twice the thickness of the outer sheet that can withstand heating at 90 ° C. or more that constitutes the stretched laminated sheet. In order to satisfy these conditions, if the target container shape is determined, the stretching ratio is naturally calculated, and the gap t is determined. If the molding is performed using a mold having such a gap t, the folded portion 8 is completely welded and integrated as shown in FIGS. 4A and 4B because the inner sheet is in a welded state. Depending on the selection of the gap t, a phenomenon in which the resin layer of the inner sheet rises inside the container may be observed, but the rise of these resins gives a rib effect to the bottom surface of the container, and a reinforcing effect can be expected. .

FIGS. 5 (a), 5 (b) and 5 (c) show examples of a bottom view and a cross-sectional view of a container formed according to the present invention. They may be formed at positions (a) and (c) at the portions, or may be formed so as to extend along the side wall portions (b), and these folded legs 8 are formed on the entire bottom surface of the container. Further, the shape may be a circle, an ellipse, a square with a rounded corner, or the like, and can be arbitrarily determined according to the shape of the intended container.

The laminated sheet of the present invention comprises an outer sheet 6 having a thickness of 200 to 1800 .mu.m and having a softening temperature of 20 to 100 .mu.m which is resistant to heating at 90.degree. C. or more. Polycarbonate and polyester sheets and polypropylene /
A multilayer sheet such as a saponified ethylene copolymer / polypropylene is used, and a sheet such as polyethylene is used as the inner sheet 7. These sheets are formed by a known laminating method such as a dry laminating method, an extruding laminating method and a co-extruding multilayering method. To form a laminated sheet.

For example, the outer sheet 6 is made of polypropylene,
When the inner sheet 7 is a low-density polyethylene, the suitable molding temperature of polypropylene is 150 to 180 ° C., the welding temperature of the low-density polyethylene is about 130 ° C. When the polypropylene and the inner sheet 7 are low-density polyethylene, the appropriate molding temperature of the polypropylene is 150 to 180.
° C, and the welding temperature of the low density polyethylene is about 130 ° C.
The temperature is about 0 ° C., and a known vacuum forming method, pressure forming method or vacuum pressure forming method is used as the forming method.

[0013]

EXAMPLE An 800 μ thick polypropylene / ethylene-vinyl acetate copolymer saponified sheet / polypropylene sheet was used as the outer sheet, and a 20 μ thick low density polyethylene laminated sheet was used as the inner sheet. At 70 ° C., a 70 cc circular container A was formed. The height of the folded legs was 3 mm, and the gap t for forming the folded legs was 1.5 mm. Similarly, a container B was obtained by molding under the above conditions using a multilayer sheet composed of polypropylene / ethylene-vinyl acetate copolymer saponified product / polypropylene having a thickness of 820 μm. The obtained containers A and B are filled with red-colored water, completely sealed with a cover film, and heated at 120 ° C.
Container A after retort sterilization under the conditions of 30 minutes
It was confirmed that red water had entered the container B where the folded leg was formed. Similarly, containers A and B were filled with curry roux and heated in a microwave oven (500 W) for 2 minutes. Container A remained in the same state, but container B was folded back to form curry curls. Roux penetrated, and the legs were deformed.

[0014]

The container obtained by the method of the present invention does not penetrate into the folded legs even when subjected to high-temperature sterilization such as boiling and retort sterilization, and also when heated by a microwave oven or the like during use, and can be deformed without any deformation. Without causing
Moreover, to eat and drink the heated contents,
This is a method in which a folded leg serves as a thread end of a bowl, has a heat insulating effect, and can provide a very easy-to-handle container at low cost. In addition, by providing the container with legs,
When heating is performed using a microwave oven, the efficiency can be increased, and a uniformly heated product without uneven heating can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing an outline of a molding die, and is a view showing a state before a folded leg portion is formed.

FIG. 2 is a view showing an outline in which a movable bottom portion 3 is pushed up in an upper surface direction to form a folded leg portion.

FIG. 3 is an enlarged conceptual diagram of a portion formed by a mold side wall portion 2 and a movable bottom portion 3;

4 (a) and 4 (b) are enlarged schematic views of a folded leg formed by the method of the present invention, and FIG. 4 (a) shows a case where a gap t of the folded portion exceeds twice the thickness of the outer sheet. FIG. 3 is a view showing a state of not more than twice the thickness of the laminated sheet,
FIG. 4 is a view showing a state in which the gap t is substantially twice the thickness of the outer sheet, and a view showing a state in which the inner sheet is welded.

FIG. 5 is a view showing various forms having a folded leg obtained by the present invention.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FIB29L 9:00 22:00 (56) References JP-A-57-178816 (JP, A) JP-A-1-208116 (JP, A) JP-A-1-214426 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 51/00-51/46

Claims (3)

(57) [Claims] 1. A molding die having an opening at an upper portion, comprising a side wall portion and a bottom portion, and capable of forming a folded portion over a part or the entire periphery of the bottom portion, using a push-up mold. A single-layer or composite multilayer sheet capable of withstanding heating of 90 ° C. or more is used as an outer sheet, and a single-layer sheet or a composite multilayer sheet having a lower softening temperature than the outer sheet is used as an inner sheet. In the temperature range in which the outer sheet can be molded, vacuum, air pressure molding or vacuum / air pressure molding method is used to form the bottom sheet that can be pushed up while the inner sheets are in the temperature range where welding is possible. By pushing up, a folded part is formed all around the bottom of the molded container, and the inner sheet is welded and integrated to form a container with legs. Construction method. 2. A mold having a gap t for forming a folded portion with a mold 2 forming a side wall and a bottom mold 3 forming a bottom surface and capable of being pushed up, wherein the gap t is laminated. The thickness of the outer sheet made of a single-layer or composite multilayer sheet, which is not more than twice the thickness when the sheet is stretched to form the bottom portion, and which can withstand heating of 90 ° C. or more, which constitutes the laminated sheet A method for producing a container using a mold that is twice or more. 3. A bottom surface portion is formed at a tip end of a gap t for forming a folded portion by a bottom surface forming mold 3 which forms a side wall and a bottom surface portion which is capable of being pushed up. A method of molding a container using a mold having a concave portion 5 of FIG.