WO1997007967A1

WO1997007967A1 - Food container lid and method of molding hot plate thereof

Info

Publication number: WO1997007967A1
Application number: PCT/JP1996/000211
Authority: WO
Inventors: Toshiaki Shimono
Original assignee: Athena Kogyo Co., Ltd.
Priority date: 1995-08-25
Filing date: 1996-02-02
Publication date: 1997-03-06

Abstract

The invention has its object to enable accurately mass producing a foam resin sheet for a lid (20) of a container for an instant food which requires hot water discharging after hot water pouring cooking. Also, the invention has its object to enhance a property of mounting the lid (20) to and dismounting the lid (20) from a container body (10) to readily mount the lid to the container body and readily dismount the lid from the container body. A foam resin layer (31) in the lid, which is a finished molded product, has a thickness (T) of 0.3 to 1.2 mm and an expansion ratio of 1.5 to 8. The foam resin sheet used for hot plate molding has a thickness of 0.3 to 0.95 mm and an expansion ratio of 1.5 to 8.

Description

Description Food container lid and hot plate forming method

The present invention provides a food container lid and a hot plate forming method thereof, and more particularly, a lid obtained by forming a laminated sheet obtained by laminating a foamed resin sheet and a synthetic resin film, The present invention relates to a hot plate forming method for the lid. Background art

An instant food container, such as instant food, which is cooked by pouring water, comprises a container body for storing the food and a lid that is fitted to the edge of the container body and closes the opening. When a foamed resin is used for such an instant food container, the heat insulation property from pouring to draining water is kept good due to the heat insulation characteristic of the foamed resin, so that an appropriate cooking temperature is easily maintained. In addition, there is an advantage that when the hot water is drained by holding the lid and the container body by hand, the hand does not become so hot that there is no danger of burns. For this reason, attempts have been made to make the lid body as well as the container body for the ready-to-eat food using foamed resin (Japanese Utility Model Laid-Open No. 63-182210).

Japanese Utility Model Application Laid-Open No. 63-182182 mentions a packaging sheet made of a laminated sheet made of a foamed resin sheet laminated with a synthetic resin film. Although there is a statement that a foamed resin sheet with a thickness of 1.0 to 2.0 mm is used when forming a heat insulating lid for a container, a description of how to form the above thermal insulation lid is given. There is no.

However, although there is no description of the molding method, when a thick foamed resin sheet having a thickness of 1.0 to 2.0 mm as described in the above-mentioned publication is used, in general, the vacuum pressure molding method is used. Becomes ο

On the other hand, some manufacturers of the above-mentioned lids do not have equipment for performing the vacuum and pressure forming method, but they do have equipment for performing the hot plate forming method, or use the hot plate forming method. O want to manufacture lids

However, when a hot plate molding method is performed using a foamed resin sheet as a material, the foamed resin sheet is generally sandwiched between a hot plate heated to a predetermined temperature and a molding die, and the foamed resin sheet is formed. After heating the resin sheet at the temperature of the hot plate to soften it, the softened foamed resin sheet is brought into close contact with the mold by air pressure. When such a hot plate forming method is used for forming a relatively thick foamed resin sheet having a thickness of 1.0 to 2.0 mm, it is possible to form details of a food container lid as a final formed product. However, it is difficult to form a hot plate with a high degree of precision that is as detailed and sharp as required, and it is difficult to mass-produce lids.

On the other hand, when it comes to the lid, which is a molded product, it has the property of ensuring that it can be securely and easily inserted into and removed from the container, namely The lid must have some elasticity to ensure its realism and ease of removal.

The present invention has been made in view of the above points. That is, the present invention provides a highly elastic food container lid which can be formed finely, sharply and with high precision even by hot plate molding of a foamed resin sheet, can be mass-produced, and can be easily fitted to and removed from the container body. It is for this purpose.

Further, the present invention is based on the fact that a food container lid is thermoformed using a foamed resin sheet, and in that case, the foamed resin sheet is formed into a fine, sharp, highly accurate food. It is an object of the present invention to provide a hot plate forming method capable of mass-producing container lids by thermoforming and obtaining a lid that can be fitted and detached from the container body. Disclosure of the invention

As the food container lid and the method of molding the same according to the present invention, if the following requirements are satisfied, it is a matter of course that vacuum pressure molding can be performed, but hot plate molding can also be adopted, and a foamed resin layer is formed. The thickness of the foamed resin sheet before molding is 0.3 to 0.95 mm, the expansion ratio is 1.5 to 8 times, and the food container lid as the final molded product It is necessary to make the thickness of the foamed resin layer 0.3 to 1.2 mm. The thickness of the foamed resin layer of the lid of the final molded product is preferably from 0.3 to 1.0 mm, more preferably from 0.3 to 1.0 mm. It is 3 to 0.9 mm, more preferably 0.5 to 0.9 mm, most preferably 0.65 to 0.9 mm. If the thickness of the foamed resin layer of the lid of the final molded product is more than 1.2 mm, heat transfer is poor during hot plate molding, and it is not possible to mold the foamed resin sheet with high accuracy, and moreover, the molding speed Cannot be accelerated to the level of mass production (hot plate forming time: about 10 seconds per piece), and the rigidity is too large to maintain the required elasticity of the lid, making it impossible. . If the thickness is less than 0.3 mm, satisfactory heat insulation cannot be obtained for the lid, which is the final molded product, and the lid is too soft to be securely fitted.

The foaming ratio of the foamed resin sheet before forming the hot plate for forming the foamed resin layer is 1.5 to 8 times, preferably 1.5 to 6 times. If the expansion ratio of the foamed resin sheet is larger than 8 times, the details will not be formed sharply and finely. This tendency is particularly noticeable when the molding speed is increased to the level of mass production. In addition, the rigidity is too high to maintain the required elasticity of the lid in order to secure the fitting property to the container body, and it is impossible. If the foaming ratio of the foamed resin sheet is less than 1.5 times, satisfactory thermal insulation cannot be obtained, and the cost of material for forming a lid of the same thickness is high, resulting in a product. Costs soar. Therefore, it is necessary to set the expansion ratio of the foamed resin sheet to 1.5 to 8 times, and the best is about 5 times.

A synthetic resin film is laminated on the above foamed resin sheet. In the case where a lid is obtained by hot-plate forming the laminated sheet thus formed, it is necessary to use a synthetic resin film having a thickness of 15 to 80 m. The preferred thickness of the synthetic resin film is 30 to 70 Ltm. The synthetic resin film is useful not only for printing on the lid, which is the final molded product, but also for suppressing the cracks by supplementing the strength of the foamed resin sheet that forms the lid. Also useful. If the thickness of the synthetic resin film is more than 80 m, the cost will be high at the mass production level. If the thickness is less than 15 m, the strength required for the synthetic resin film is insufficient, and the heat of molding the hot plate may damage the synthetic resin film itself. Therefore, the thickness of the synthetic resin film must be 15 to 80 m.

In this hot plate forming, a laminated sheet provided with the synthetic resin film on the hot plate side or the forming die side is sandwiched between the hot plate and the forming die, The laminated sheet is brought into close contact with the hot plate and heated by being heated to soften it.Then, the laminated sheet softened by the air blown out from the hot plate side is brought into close contact with the mold, and the laminated sheet is closed. O Brief description of drawings

FIG. 1 is a schematic perspective view showing a container body and a lid as containers. Figure 2 is an enlarged cross-sectional view of a part of the container.

FIG. 3 is an enlarged cross-sectional view of a part of a lid according to a modification. FIG. 4 is an enlarged sectional view of a part of the lid.

FIG. 5 is an enlarged view of a portion V in FIG.

Fig. 6A is an explanatory view of a state in which the laminated sheet is disposed between the hot plate and the mold, Fig. 6B is an explanatory view of a step of softening the laminated sheet, and Fig. 6C is a step of forming the lid. FIG. 6D is an explanatory view of the molded product released from the mold. BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 shows a food container A, specifically, a container body 10 and a lid 20 used for “instant fried noodles” and “instant 麵”. The container body 10 is made of foamed polystyrene resin or foamed polypropylene resin having a high expansion ratio (about 10 times), and is not printed on the surface.

The lid 20 is made of a synthetic resin film (described later), which is printed on the surface of a foamed resin layer made of foamed polystyrene resin or foamed polypropylene resin, with the printed surface inside. Lamination by heat fusion-The laminate structure is integrated. Of course, this lid 20 may be a lid made of only a foamed resin sheet without laminating and integrating the synthetic resin film, but in the best mode, the synthetic resin film is laminated and integrated. This will be described hereinafter.

As can be seen in FIG. 2, the lid 20 is integrally formed on the periphery thereof. The fitted projection 21 is fitted to the lid receiving portion 11 formed integrally with the upper opening edge of the container main body 10 to be mounted on the container main body 10. Then, in order to ensure the mounting state, an engaging ridge 22 is formed inward on the fitting projection 21, and the engaging ridge 22 is attached to the lid receiving portion 11. It is designed to engage with. The lid body 20 has a hollow frame portion 23 for accommodating the lid receiving portion 11 in a fitting shape in an outer peripheral portion thereof, and the hollow frame portion 23 has a hollow shape. At the two diagonal corners, a small opening 24 used for pouring and draining water and a cut-up piece 25 for closing it are provided, and the product name etc. of the contents are added. In addition, a bulging portion 26 for displaying it three-dimensionally and a small protrusion 27 at a predetermined position on an inner side portion of the hollow frame portion 23 are provided. In addition, the entire surface of the lid 20 is printed and displayed with the above-mentioned synthetic resin film (display of necessary information on contents and cooking method, etc.). In 26, the printed display of the product name of the contents is largely exaggerated.

As shown in FIG. 4, the lid 20 is provided with a synthetic resin film 41 having a printing surface 42 on one side and a printing surface 42 on the inside, on the surface of the foamed resin layer 31. Thus, they are laminated by heat fusion and integrated with the foamed resin layer 31. The synthetic resin film 41 of the lid 20 in the example is heat-sealed to a high-material-density skin layer (not shown) formed on the surface of the foamed resin layer 31. As shown in FIG. 5, the lid 20 has a total thickness T of 0.3 to 1.2 mm. This finished thickness T is preferably between 0.3 and 0.8 mm. If the cover 20 is finished to a thickness of 0.3 to 1.2 mm, the appropriate elastic force required for fitting and unsealing with respect to the container body 10 is ensured. The rigidity required of the lid of the ready-to-eat food container that is cooked and drained after cooking is secured, and it is molded from non-foamed resin that has been used as the lid of the ready-to-eat food container. It has the same strength as the lid.

The expansion ratio of the foamed resin sheet before thermal forming for forming the foamed resin layer 31 of the lid 20 is 1.5 to 8 times, preferably 1.5 to 6 times. Keep it. If the foaming ratio of the foamed resin sheet 3 is greater than 8, the details in the molding process, such as the fitting projection 21, the engaging ridge 22, and the small projection 27 described in FIG. This tends to make it difficult to perform fine and sharp molding of fine details, and the molding speed cannot be increased to the level of mass production. Also, it is impossible to maintain the required elasticity of the lid. If the thickness is less than 0.3 mm, the lid, which is the final molded product, does not have sufficient heat insulation.

In the foamed resin layer 31, the plastic deformation of the material is completely performed at the time of forming the hot plate, and the foamed resin layer 31 is finished with high accuracy. Therefore, there is no residual stress in the lid 20 that may be greatly deformed by the temperature of the hot water, and the lid 20 is fitted to the container body 10 in a fitted state. When pouring cooking or draining hot water after cooking, the lid 20 is not deformed and displaced or detached from the container body 19.

In FIG. 3, a part of the hollow frame 23 is bulged outward at the side of the lid 20, and a gap 29 is formed at the bulged portion, which can be used for pouring and discharging hot water and ventilation. This is shown.

6A to 6D illustrate the thermoforming method. In this hot plate molding, the synthetic resin film 41 is laminated on a foamed resin sheet 3 having a thickness of 0.3 to 0.95 mm and an expansion ratio of 1.5 to 8 times. G 30 is used. That is, in this thermoforming, as shown in FIG. 6A, the synthetic resin film 41 (see FIG. 5) is placed at an appropriate position between the hot plate 91 and the molding die 92 on the hot plate 91 side. After laminating the laminated sheet 30 toward the mold, the laminated sheet 30 is sandwiched between the hot plate 91 and the mold 92 as shown in FIG. the blown were laminated sheet 3 0 in air to soften Ri by the and this heating at 1 0 0 ~ 1 4 0 ^e C approximately of the hot plate 9 1 in close contact to the hot plate 9 1, then Fig. 6 C The laminated sheet 30 softened by the air (at an air pressure of 3 to 5 kg / cm ² ) blown out from the hot plate 91 side as described above is brought into close contact with the mold 92 to laminate a plurality of lids 20 Simultaneous molding at multiple locations on sheet 30. Then, after releasing the mold as shown in FIG. 6D, it is divided into individual lids 20. When forming a hot plate, make sure that the After placing the laminated sheet 30 with the synthetic resin film 41 facing the mold 92 at the position, the laminated sheet 30 is sandwiched between the hot plate 91 and the mold 92. The laminated sheet 30 is softened by being closely contacted with the hot plate 91 and heated by air blown from the molding die 92 side as indicated by an arrow, and then with the air blown from the hot plate 91 side. It is also possible to adopt a method in which the soft laminated sheet 30 is brought into close contact with the molding die 92 and a plurality of lids 20 are simultaneously molded at a plurality of locations of the laminated sheet 30.

In the laminated sheet 30 provided for hot plate molding, the thickness of the foamed resin sheet 3 is suitably from 0.3 to 0.95 mm, preferably from 0.3 to 0.9 mm. If the thickness is more than 0.95 mm, the heat transfer in the softening process shown in Fig. 6B is poor, and molding cannot be performed with high accuracy.Moreover, the molding speed cannot be increased to respond to mass production. No. Furthermore, if the time for forming the hot plate is increased to transfer heat to the entire foamed resin sheet, the synthetic resin film may be overheated and damaged. In addition, the elasticity of the lid, which is the final molded product, becomes poor, and it is not possible to sufficiently secure the required removability of the lid from the container body. If the thickness is less than 0.3 mm, satisfactory heat insulating properties of the final molded product lid 20 will not be obtained, and heat retention during pouring cooking. Serious burns can cause burns. When the thickness is 0.3 to 0.95 mm, the molding speed can be increased to such an extent that mass production is possible without increasing the temperature of the hot plate 91 so much. In addition, the heat insulation of the lid 20 as the final molded product was satisfactory, the heat retention during the pouring was kept good, and the lid 20 was gripped when the hot water was drained. The situation in which the hands become hot can no longer occur, and the ease of fitting into and removing from the container body is improved. The most preferable thickness of the foamed resin sheet 3 is 0.65 to 0.9 mm, and when the thickness is in this range, the above-mentioned action is remarkably exhibited.

It is desirable that the expansion ratio of the foamed resin sheet 3 be 1.5 to 8 times, preferably 1.5 to 6 times. If the expansion ratio of the foamed resin sheet 3 is larger than 6 times, especially larger than 8 times, details in the molding process shown in FIG. 6C, for example, the fitting projection 21 and the engaging ridge 22 described in FIG. However, it tends to be difficult to form details such as small projections 27 in a sharp manner, and the elasticity required for the lid, which is the final molded product, is not satisfied. Conversely, if the foaming ratio of the foamed resin sheet 3 is smaller than 1.5 times, satisfactory heat insulating properties cannot be obtained, and when the lid 20 having the same thickness is formed. Material costs are high and product costs are rising. The foaming ratio of the foamed resin sheet 3 should be 1 in order to have good heat insulation, to be able to mass-produce sharply and precisely the details, and to have sufficient elasticity to ensure the fitting and detachment to the container body. It is preferable to keep it 5 to 6 times, and about 5 times is best.

An appropriate thickness of the synthetic resin film 41 in the laminated sheet 30 is 15 to 80 μm. Synthetic resin film 4 1 is 8 0 Thicker than m increases cost. If the resin film 4 is thinner than 15 m, the strength required for the synthetic resin film 41 will be insufficient, and the heat generated during the softening process will cause the resin film 4 to lose its strength. 1 Risk of damage. If the thickness of the synthetic resin film 41 is 15 to 80 m, it is possible to respond to mass production by increasing the molding speed without increasing the temperature of the hot plate 91 so much. In particular, when the distance is 30 to 70 m, the above-mentioned action is remarkably exhibited.

The use of a synthetic resin film 41 having a thickness of 15 to 80 m has the following advantages. That is, before the lid 20 is formed on a hot plate, a synthetic resin film, which is printed on the surface of a foamed resin layer made of foamed polystyrene resin or foamed polypropylene resin, is printed on the printing surface. It is necessary to make a sheet material for forming the lid 20 by laminating by heat fusion and laminating the laminated body with the inside facing, but in the laminating process, a synthetic resin film is used. If the thickness of 41 is greater than 80 am, it is too thick to make the heat transfer worse, making it difficult to increase the laminating speed. If the height is increased, the printing surface 42 of the synthetic resin film 41 may be damaged. If the thickness of the synthetic resin film 41 is less than 15 m, the strength required for the synthetic resin film 41 will be insufficient, and the laminated sheet 30 will also have satisfactory strength. Absent. If the thickness of the synthetic resin film 41 is 15 to 80 m, the temperature of the heating roll should not be so high. In this case, the laminating speed can be forcibly increased, and the above effect is remarkably exhibited particularly when the laminating speed is 30 to 70 m.

The softening process of FIG. 6 B, the hot plate 9 1 1 the temperature of 0 0~ 1 4 0 ^e C, the outlet and pressure of the air blown out from the mold 9 2 side as indicated by an arrow 0. 5~ lkg Z cm ^If the processing time is set to ² and the processing time is set to about 6 seconds, the softening of the laminated sheet 30 proceeds rapidly. If the temperature of the hot plate at this time is too high, the air blowing pressure is too high, or the processing time is too long, the back surface of the foamed resin sheet 3 in the laminated sheet 30 or the synthetic resin The surface of the film 41 becomes more likely to be roughened or damaged, and conversely, the temperature of the hot plate is too low, the air blowing pressure is too low, or the processing time is too short. Then, the laminated sheet 30 is not softened to an extent necessary for the subsequent molding or takes too much time. In the softening process of FIG. 6B, the temperature of the hot plate 91 is increased by the synthetic resin film. Transmit from the front side of 4 1 to the printing surface 4 2. Therefore, the printing surface 42 of the synthetic resin film 41 is hard to be damaged due to roughening. In the molding process of FIG. 6C, the pressure of the air blown from the hot plate 91 side as shown by an arrow is 3 to If the thickness is set to 5 kgZcm ² , the laminated sheet 30 will surely adhere to the mold 92, and the lid 20 will be molded quickly and accurately. If the air blowing pressure at this time is too high, the air bubbles in foamed resin sheet 3 will be crushed and the insulation If the blowing pressure is too low, reliable molding, especially the molding of the details, may not be performed in a finely divided shape. Also, in this molding process, the temperature of the hot plate 91 is transmitted from the front side of the synthetic resin film 41 to the printing surface 42, so that the printing surface 42 of the synthetic resin film 41 is formed. Will not be damaged by damage.

As described above, the lid 20 as a final product obtained by hot-plate forming the laminated sheet 30 has a total thickness T of 0.3 to 1.2 mm, preferably 0.3 to 1.2 mm. Finished to 0.8 mm. Since the laminated sheet 30 may be somewhat compressed by undergoing the thermoforming process, it can be finished in this thickness range. If the lid 20 is finished to a total thickness of 0.3 to 1.2 mm, the rigidity required for the lid of the container body of the ready-to-eat food that is poured and poured after cooking, and the lid When fitting / removing the body to / from the container, appropriate elasticity is ensured for secure fitting and easy removal.

In the case of using a laminated sheet in which a printed synthetic resin film is integrated with a foamed resin sheet, it is preferable to use the above-described hot plate molding method. This is because, in the vacuum pressure forming method, there is a softening zone for heating the laminated sheet to a temperature at which it can be molded before entering the forming zone, and the laminated sheet softened in the softening zone has its own weight. May hang or bend. And the laminated sheet softened in that way Is fed into the molding zone at a constant feed rate. Therefore, the laminated sheet may bend before entering the molding zone, and the laminated sheet may not be sent to a predetermined position of the molding zone. In other words, when the plastic sheet of the laminated sheet is printed, the center of the printed sign may not be sent to the center of the mold in the molding zone. If the laminated sheet is molded into the lid of a food container while the situation is occurring, the printed portion of the final molded product, such as its contents and cooking method, will be displaced from the proper position. It is. Therefore, it is better to use a hot plate forming method that does not cause such displacement. Industrial applicability

The lid of the food container according to the present invention, in particular, the thickness of the foamed resin layer of the lid is 0.3 to 1.2 mm, and the foamed resin sheet before forming a hot plate for forming the foamed resin layer With a thickness of 0.3 to 0.95 mm and an expansion ratio of 1.5 to 8 times, it has an appropriate degree of elasticity, so that it can be securely attached to and detached from the container body. Also, there is no danger of the lid being detached from the container body during hot water pouring and draining during hot water spillage. In addition, the rigidity required for the lid, which is the final molded product, is sufficiently secured. The hot plate forming method of the food container lid of the invention according to the present invention, in particular, foaming with a thickness of 0.3 to 0.95 mm and an expansion ratio of 1.5 to 8 times According to the method of forming a laminated sheet obtained by laminating the above synthetic resin film on a resin sheet into a lid having a foamed resin layer thickness of 0.3 to 1.2 mm, a container body is formed. It will be possible to manufacture the lid as the final molded product at a high molding speed that has the resilience that can be easily fitted to and removed from the product, and that can respond to mass production o

Claims

The scope of the claims

(1) The lid of the food container as the final molded article, the thickness of the foamed resin layer of the lid of the final molded article is 0.3 to 1.2 mm, and the foamed resin layer is formed. A food container lid characterized in that the foamed resin sheet before molding has a thickness of 0.3 to 0.95 mm and an expansion ratio of 1.5 to 8 times.

(2) The food according to claim 1, wherein a synthetic resin film is laminated and integrated on the foamed resin layer, and the synthetic resin film has a thickness of 15 to 80 m. Container lid.

(3) A hot plate molding method for a food container lid using a foamed resin sheet, wherein the foaming ratio is 1.5 to 0.95 mm and the thickness is 0.3 to 0.95 mm.

It is characterized in that the thickness of the foamed resin layer of the food container lid as the final molded product is 0.3 to 1.2 mm by hot plate forming an 8 times foamed resin sheet on the lid. Hot plate molding method for a food container lid.

(4) The hot plate molding method for a food container lid according to claim 3, wherein a synthetic resin film having a thickness of 15 to 80 czm is laminated and integrated on the foamed resin sheet. .

(5) A hot plate forming method for a food container lid using a foamed resin sheet, which covers a foamed resin sheet having a thickness of 0.3 to 0.9 mm and an expansion ratio of 1.5 to 8 times. Hot plate molding of a food container lid characterized in that the thickness of the foamed resin layer of the food container lid as a final molded product after being formed into a hot plate is 0.3 to 1.0 mm. Method.

(6) A synthetic tree with a thickness of 15 to 8 otm on the foamed resin sheet 6. The hot plate molding method for a food container lid according to claim 5, wherein the fat film is laminated and integrated.

(7) Between the hot plate and the mold, the laminated sheet with the synthetic resin film on the hot side is sandwiched between the hot plate and the mold, and the laminated sheet is placed on the hot plate. The laminated sheet softened by being closely contacted and heated by heating, and then the laminated sheet softened by the air blown out from the hot plate side is brought into close contact with a mold, and the laminated sheet is formed into a hot plate by a hot plate. Item 5. The hot plate molding method for a food container lid according to Item 4.

(8) Between the hot plate and the mold, the laminated sheet with the synthetic resin film on the hot side is sandwiched between the hot plate and the mold, and the laminated sheet is placed on the hot plate. The laminated sheet softened by being closely contacted and heated by heating, and then the laminated sheet softened by the air blown out from the hot plate side is brought into close contact with a mold, and the laminated sheet is formed into a hot plate by a hot plate. 7. The hot plate molding method for a food container lid according to item 6.