JPH09104068A - Mouth part curling method of synthetic resin container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method locally heating a region to be curled and subsequently downwardly or inwardly bending and curling the mouth flange part of a container and a method for culring the outpart of the safe synthetic resin container not injuring a lip by the mouth part and ensuring the max printing area on the side surface thereof. SOLUTION: In a synthetic resin container consisting of a container main body 11 and the opening flange 14 extending from the outer periphery of the opening part 12 of the container main body and having a mouth part formed by the curl processing of the opening flange, the opening flange is locally heated (hot air heater 17) to be subjected to curl processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for curling the mouth of a synthetic resin container that can be used as tableware for food packaging or when eating contents, and more particularly, it is projected on the outer periphery of the opening of the container body. The present invention relates to a curling method for curling an opening collar to form a safe mouth portion having a good mouth feel.

[0002]

2. Description of the Related Art A sheet-shaped raw material such as a non-foamed resin container (hereinafter referred to as "solid container") or a foamed resin sheet container is heated and then sandwiched by male and female molds to open the container body. A synthetic resin container adopts a molding process in which the opening flange is integrally projected on the outer periphery of the part, and then the molded product is cut off from the sheet with a punching blade. And sharp edges are created.
This sharp edge has a high risk of injury, especially in a food container or the like that is brought into contact with soft skin or lips and used for eating, and is regarded as dangerous in the market. Further, industrially, when a shrink film or the like is used for the exterior, there is a problem that the shrink film is broken due to a sharp edge.

Further, it is said that it is preferable in view of the container design that the size of this flange portion is as small as possible.
In addition, the mouthfeel is improved. However, the mouth collar has a deep relationship with the compressive strength in the direction of squeezing the container, such as the force when applying the shrink film, and in reality it is desirable to make it as large as possible in terms of strength. I can't.

In order to solve this problem, a so-called curl treatment has been proposed in which an opening flange formed in advance on the outer periphery of the opening of the container body with a margin for curling is folded downward. For this curl treatment, a curl device manufactured by Brown Co. of the United States of America is proposed and manufactured.

An outline of the curling device will be described by taking the device of Brown Co. as an example. As shown in FIGS. 3 to 6, the curling device 20 is composed of a screw portion 20A and a heating portion 20B, and the screw portion 20A is 1 The opening screw 14 of the container (intermediate molded product 10A) is held by the grooved heating screw 21 of the shaft and the seven drive rolls 22, ..., And the screw molding groove 23 is fed as the container is fed by the screw rotation.
Thus, the opening flange 14 can be folded and continuously curled. That is, screw 2
Formed at 1 is a molding groove 23 whose cross-sectional shape continuously changes so that the curl can be finished into a predetermined shape as the process progresses. A heating unit 20B as shown in FIG. 5 is arranged in the front stage of the screw unit 20A, and the heating unit 20B is composed of a heating furnace 24. The container is uniformly heated and softened to achieve curling by the screw unit 20A in the rear stage. It has a structure that allows it. Here, in the heating furnace 24, a heater 25 is arranged around the passage of the container row, and a guide rod 26 for guiding the container row forward without contacting the heater 25 is arranged. .

By carrying out the curl treatment, the cut surface of the sharp mouth collar portion is hard to come into contact with the skin or the shrink film, and the effective width as the mouth portion can be secured, so that the strength is also maintained. On the other hand, the resin has the characteristic that the shape cannot be changed unless it is heated above a predetermined temperature, for example, above the softening temperature. The same applies to the case of performing the curl processing in the curl device 20 described above, and the heating furnace 24 is trying to achieve this. However, the above-mentioned curling device is generally industrially adapted to continuously process the containers, and in this case, the containers are stacked (hereinafter referred to as “stacked state”) in the heating section 20B and the screw section 20A. Be transported to. Therefore, the heating is uniformly applied to the portion other than the portion to be curled.

When a synthetic resin container has been deformed by heating in the past (in this case, molding by the above-mentioned male and female dies corresponds to this), residual stress is released and deformed when heated again. Cause Furthermore, when the temperature rises, the apparent elastic modulus decreases, so that the elastic member is deformed by its own weight. Styrene-based resin foam sheet container (hereinafter referred to as "PSP
The term `` container '') is more problematic and has the characteristic that it foams and deforms when heated in a heating furnace, and its thermal conductivity is extremely low compared to non-foamed synthetic resins. When the core part in the thickness direction is heated to a temperature suitable for curling deformation, the surface layer part is heated more than necessary, causing additional foaming and deformation, as well as foam cells rupturing and causing problems in appearance or strength. Will occur. Further, when heated over a wide area, only the relevant portion seems to swell, so that a remarkable deformation occurs in the appearance design.

Although there is such a problem in heating a synthetic resin container, particularly in a stacked state, a portion hidden by a container to be processed next is not heated, and a portion to be curled and a The section between the container to be processed is heated. Therefore, the side surface is deformed only in this heated portion. In particular, in the case of a foamed resin container, the side surface part of the container exposed on the surface side is additionally foamed and deformed, and if this deformation occurs, not only the finished appearance is bad, but also a step between the part that is not deformed and As a result, it becomes difficult to print on this portion, which causes a problem that the printing area on the side surface is reduced.

In particular, in the case of a PSP container, the tendency is remarkable as compared with a non-foamed container, and there is a problem that the cell itself does not swell or break, and further, a foamed sheet laminated by laminating a non-foamed resin on the surface. In the body, when the softening point of the non-foamed resin is high and the resin is inside the curl of the portion to be curled, heating from the outer surface does not provide sufficient heating, and the curl does not occur. In addition to the problem that it does not exist, it has been a factor to date that virtually no curling-treated foamed sheet container, particularly a high foaming ratio container having a high expansion ratio and a high heat insulating property is provided.

[0010]

As a result of extensive studies on a method for improving such a drawback, in a curling method of heating the entire container from the outer peripheral side prior to curling, a heat insulating material is arranged at a portion other than the mouth portion of the container, Curling workability is remarkably improved by preventing heating of parts other than the mouth to reduce thermal deformation, etc., and sufficient heating can be achieved for parts not provided with a heat insulating material. The inventors have found that a printing area can be secured and have reached the present invention.

That is, in view of the above-mentioned situation, the present invention is to solve the problem by heating the entire container in a state where heat is cut off from the part other than the part to be curled, and then the mouth rim of the container. It is a processing method of curling the part downward or inward, and it is a safe synthetic resin container that does not damage the lips at the mouth and a synthetic resin container that secures the maximum printing area on the side surface. The point is to provide a method for curling the mouth.

[0012]

In order to solve the above-mentioned problems, the present invention has a container main body and an opening flange projecting to the outer periphery of the opening of the container main body, and the opening flange is curled. A synthetic resin container formed by forming a mouth part, which is covered with a heat insulating material other than the part of the opening flange to be curled, after heating the entire container including the opening flange from the outer peripheral side,
A method for curling the mouth of a synthetic resin container obtained by curling the opening flange.

Here, in a curling method for curling the opening flanges of a plurality of container bodies in a stacked state, a portion covered with a heat insulating material is at least an outer surface of the container body which is not thermally shielded by another container body. More preferably. Further, when the synthetic resin container is a foamed resin container, the effects of the present invention are maximized. Further, the present invention is also suitable when the drawing ratio represented by the container height / opening diameter is 0.8 or more.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the synthetic resin used as the material of the container broadly refers to the resin produced industrially, but in this embodiment, the processing of the mouth collar part is more preferable in the synthetic resin. Description will be made by taking a difficult foam resin container as an example. Here, a sheet-shaped resin is used as the foamed resin, and a styrene-based resin foamed sheet is typical in a shallow container for food packaging such as instant noodles.

The styrene-based resin foamed sheet includes butane of polystyrene and copolymers of styrene and maleic anhydride, methacrylic acid, etc., and styrene-based resins such as mixed resins of these styrene-based resins and polyphenylene oxide. After kneading with a blowing agent such as chlorofluorocarbon and an extruder,
It is a foamed sheet extruded and foamed. Sheet thickness is 1
Generally, a sheet basis weight of 150 to 550 g / m ² is used, and a foaming ratio of 3 to 5 is preferable, but the range is not limited to this range. Further, a laminated styrene resin foam sheet obtained by laminating a non-foamed thermoplastic resin film on one side or both sides of the above styrene resin foam sheet and laminating them together can also be used.

As the non-foamed thermoplastic resin film laminated and laminated on the styrene resin foam sheet, polystyrene, styrene resin such as high impact polystyrene (HIPS), polyethylene, polypropylene (P
Olefin resin film such as P), polyvinylidene chloride, ethylene-vinyl alcohol copolymer resin,
Examples include individual and composite films of various gas barrier films such as polyester and polyamide. When the resin films are laminated on both sides, the same resin film may be used on both sides or separate resin films may be used.

As a method for laminating and compounding a thermoplastic resin film on a styrene resin foam sheet, a method of dropping a film resin on a styrene resin foam sheet and laminating it, a method of directly laminating a resin film by heat, and There is a method of laminating resin films via an adhesive. In the present embodiment, the styrene resin foam sheet and the laminated styrene resin foam sheet are both referred to as a styrene resin foam sheet when there is no particular need to distinguish between them.

A method of manufacturing the container 10 from the styrene resin foam sheet obtained by the above method will be described with reference to FIGS. First, as shown in FIG. 1, a styrene-based resin foam sheet 1 wound in a roll is heated through a heating furnace 2 to be secondarily foamed, and then a male and female mold 3 (in the figure, 3A is a female mold piece, 3B is The container body 11 is molded with a male mold piece, and the opening flange 14 having a horizontal portion 14A parallel to the bottom surface 13 is formed on the outer periphery of the opening 12 of the container body 11. The opening flange 14 is continuous with the surplus foam sheet 15 that does not participate in the molding of the container 10. Male and female molds 3 during this molding
The inside of the mold is decompressed by the vacuum evacuation means 4 to enhance the transferability of the mold shape. After molding the container body 11 and the opening flange 14,
The styrene-based resin foam sheet 1 is punched out with the automatic punching machine 5 equipped with a punching blade, a Thomson blade, or the like, leaving the opening flange 14 and an intermediate molded product 10A to be an individual container 10. The thickness of the obtained container is governed by the shape of the mold and the like and is not particularly limited, but is generally 1.5 to 2 mm.

Intermediate molded product 10A thus obtained
An example is shown in FIG. The illustrated intermediate molded product 10A
The horizontal portion 14 in which the inner peripheral side of the opening flange 14 is parallel to the bottom surface 13.
A, and the tip portion 14B is inclined toward the bottom surface 13 side. The tip of the tip portion 14B of the opening collar 14 has a cut surface 1 vertically punched by an automatic punching machine 5.
4C.

The opening flange 14 is a portion which becomes a mouth portion by curling as will be described later. In the one shown in FIG. 2, the width of the horizontal portion 14A is set to the required width of the sealing surface and the tip portion is formed. The width of 14B is set to a width sufficient for curling. However, the shape of the opening flange 14 is not particularly limited in the present invention. In addition, the opening 12
It is desirable that the curvature radius of the bent portion 16 where the container body 11 facing the side and the opening flange 14 intersect is made as small as possible in order to secure a sufficient sealing area on the upper surface of the mouth portion.

Therefore, according to the present invention, before heating the intermediate molded product 10A by the above-mentioned heating section 20B, the outer surface of the container main body 11 excluding the portion of the opening flange 14 is substantially the same in shape as the heat insulating material 17.
To prevent unnecessary heating of uncurled parts. The shape and material of the heat insulating material 17 according to the present invention are not particularly limited as long as the heat insulating effect of heat to the container (intermediate molded product 10A) in the heating furnace 24 is sufficiently achieved in a portion which is not desired to be heated. However, considering that the container is continuously processed in a stacked state, it is preferable that the thickness is thin and excellent in heat resistance, and that the thermal conductivity is small, for example, polypropylene, a heat resistant resin such as polycarbonate, or paper. Etc. are suitable. The heat insulating material 17
Is arranged so as to cover the outer surface of the container body 11 other than the opening flange 14, in particular. It is preferable to dispose on the inner surface as well for heat insulation, but since the intermediate molded product 10A is conveyed in a superposed manner, most of the side surface is covered by the other container body itself to be processed in the next stage, Sufficient performance on the outer surface alone. If the container is in a stacked state, the heat insulating material 17 is applied to the opening flange 14 of the container body 11 in the next stage, that is, the intermediate molded product 10A in the next stage.
If the width is large enough to cover the section between the opening flange 14 of the above and the opening flange 14 of the intermediate molded product 10A to be processed now, the performance can be achieved.

As in the present invention, the heat insulating material 1 is provided on the portion where heating is unnecessary.
By disposing No. 7, it is possible to perform curl treatment with good workability without exerting a thermal influence on other portions.
To perform this curl process, for example, the curl device 20 manufactured by Brown Co. shown in FIGS. 3 to 6 is used.

That is, first, as shown in FIG. 5, after stacking a plurality of intermediate molded products 10A each having the heat insulating material 17 arranged thereon, they are conveyed to the heating section 20B of the curl device 20 and heated by the heating furnace 24. When the whole of the intermediate molded product 10A in the stacked state is uniformly heated from the outer peripheral side in the inside, only the opening flange 14 not covered with the heat insulating material 17 is heated to a predetermined temperature. At that time, the temperature of the heating furnace 24 is the same as that of the heat insulating material 1.
It may be selected so that the portion not covered with 7, that is, the portion to be curled (opening collar 14) is heated to the optimum temperature for curling. Depending on the length of the heating furnace 24 or the heating time, if the heating is about 5 seconds, the PSP
In the case of a container, an ambient temperature of about 350 ° C is suitable.

Then, the heated intermediate molded product 10A
Is conveyed to the screw unit 20A. In this screw portion 20A, as shown in FIG. 6, the open flange 14 is formed while the intermediate molded products 10A, ... In a stacked state are sequentially forwarded by the heating screw 21 and the driving rolls 22 ,.
Curl processing is performed by the molding groove 23 of the heating screw 21, and finally the container 10 having the curled mouth portion 19 is manufactured. The mouth portion 19 of the container 10 is illustrated in FIG. 7. In this case, the horizontal portion 14A of the opening collar 14
Is a flat seal surface 1 for attaching a seal lid (not shown)
9A, and the tip cut surface 14C approaches the side surface of the container body 11, so there is no possibility of contacting the cut surface 14C even when the lip or the like is applied to the mouth portion 19.

[0025]

[Example] A polystyrene foam sheet having a basis weight of 700 g / m ² before molding was used to give a molded product shape by meshing of the male and female dies 3, and punched from the surplus foam sheet 15 by an automatic punching machine 5 to obtain a mouth diameter. 97mm, bottom diameter 60mm, height 100mm, drawing ratio about 1, basic wall thickness 2m
m PSP container (intermediate molded product 10A shown in FIG. 2) was prepared, and the curl treatment was tried using the curl device manufactured by Brown Co., USA.

Here, the entire outer diameter of the opening flange 14 before curling is 98 mm, and the width of the horizontal portion 14A is about 2.
The width of the tip portion 14B is 2 m as a folding margin.
m. The angle of the folding margin (tip portion 14B) was set to 80 ° with respect to the horizontal plane. At this time, the horizontal portion 14
It was slightly compressed so that the thickness of A was about 1.2 mm.

Then, from immediately below the opening flange 14 to be curled, the intermediate molded product 10 in the next stage in the stacked state is formed.
A container in which a white copy sheet was wrapped as the heat insulating material 17 and a container in which the heat insulating material 17 was not provided were prepared on the outer side surface of A, and a comparison was made regarding curling.

The general settings of the curl device 20 are as follows.・ Heating furnace atmosphere temperature setting 350 ℃ ・ Screw temperature setting 90 ℃ ・ Heating time about 5 seconds

The results of curling under these conditions are shown in Table 1 below.

[0030]

[Table 1]

Here, when the heating furnace temperature is lowered and the processing is carried out, swelling of the side portion does not occur, but curling cannot be achieved because the temperature at the mouth is not sufficiently raised. On the other hand, if only the ambient temperature is simply raised to a temperature considered suitable for curling, curling can be performed,
The side surface of the section between the container of the next stage swells. In addition, since the strength of the portion was also reduced, the deformation caused by curling could not be supported and the bending phenomenon was observed not only on the mouth but also on the side surface. The printing area on the side surface is reduced accordingly.

On the other hand, when the heat insulating material 17 is arranged on the outer surface of the container body 11 of the intermediate molded product 10A, the outer surface of the container body 11 is insulated by the heat insulating material 17 even if the opening collar 14 is heated to the proper curling temperature. No swelling was observed as a result. Also, curling itself could be achieved.

[0033]

According to the method for curling the mouth of the synthetic resin container of the present invention as described above, the curl characteristic of the opening collar serving as the mouth is improved by utilizing the present invention based on the test results. The mouth part having a good appearance could be curled.

[Brief description of the drawings]

FIG. 1 is a simplified layout view showing a part of a container manufacturing apparatus according to the present invention.

FIG. 2 is a partial cross-sectional view showing a positional relationship between an intermediate molded product before curling and a heat insulating material.

FIG. 3 is an abbreviated perspective view showing a screw portion of a curl device.

FIG. 4 is also a partial side view of the heating screw.

FIG. 5 is a partial cross-sectional view showing the relationship between the heating unit of the curl device and the intermediate molded product in a stacked state.

FIG. 6 is a partial cross-sectional view showing a state where the opening flange of the intermediate molded product in the stacked state is curled by the screw portion to mold the mouth portion.

FIG. 7 is an enlarged cross-sectional view of a mouth portion curled according to the present invention.

[Explanation of symbols]

 1 Styrene Resin Foamed Sheet 2 Heating Furnace 3 Mold 3A Female Mold Piece 3B Male Mold Piece 4 Vacuum Evacuation Means 5 Automatic Punching Machine 10 Container 10A Intermediate Molded Product 11 Container Body 12 Opening 13 Bottom 14 Opening Collar 14A Horizontal Part 14B Tip Part 14C Cutting surface 15 Surplus foamed sheet 16 Bending part 17 Insulating material 19 Mouth part 19A Sealing surface 20 Curl device 20A Screw part 20B Heating part 21 Heating screw 22 Driving roll 23 Forming groove 24 Heating furnace 25 Heater 26 Guide rod

Claims (4)

[Claims] 1. A synthetic resin container comprising a container body and an opening flange projecting from the outer periphery of the opening of the container body, wherein the opening flange is curled to form a mouth portion. After covering the parts other than the part of the opening flange to be processed with a heat insulating material, and heating the entire container including the opening flange from the outer peripheral side,
A method for curling the mouth of a synthetic resin container, characterized in that the opening flange is curled. 2. A curling method for curling the opening flanges of a plurality of container bodies in a stacked state, wherein a portion covered with a heat insulating material is an outer surface of the container body which is not thermally shielded by at least another container body. The method for curling the mouth of a synthetic resin container according to claim 1. 3. The method for curling the mouth of a synthetic resin container according to claim 1, wherein the synthetic resin container is a foamed resin container. 4. The method for curling the mouth of a synthetic resin container according to claim 1, wherein the drawing ratio represented by the height of the container / diameter of the opening is 0.8 or more.