JP3352775B2 - Hinged plastic container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a container in which a main body composed of a main body of a container and an outer peripheral edge of the container and a lid formed of a lid and an outer peripheral edge of the lid are integrally formed. related to container being integrally molded by a hinge, more particularly, when opening the lid of the plastic container is able to maintain an open state and, when closed,
About Help La <br/> stick container having a structure capable of maintaining the closed by the weight of the lid.

[0002]

2. Description of the Related Art Plastic containers include a container without a lid, a container having a main body and a lid separated from each other, and a plastic container in which a main body and a lid are combined and integrated as a whole. These containers are used for various purposes by appropriately selecting the material, size and the like. Among them, the container in which the main body and the lid are integrally formed via a hinge includes an egg case using polyvinyl chloride, a container made of a foam sheet for packing natto and hamburger, and the like. These are generally used for the purpose of temporarily storing contents.

[0003] A container in which a main body and a lid are integrally formed via a hinge is molded with the lid open, so that the molded container generally tends to keep the lid open. In order to open and close the lid of the container via the hinge, it is possible to make the hinge bend easily by making the hinge portion thinner than other portions.
Japanese Patent Publication No. 624 and Japanese Patent Publication No. 3-60657 disclose a method of improving the flexibility of a hinge portion by forming a plurality of hinges by pressing. Japanese Patent Application Laid-Open No. 61-199942 discloses a method in which a plastic sheet is subjected to crease processing using a heated press die to impart flexibility.

[0004]

However, if the hinge portion, which integrally forms the outer peripheral edge of the main body of the container and the outer peripheral edge of the lid, is simply provided with a groove so as to impart flexibility, the lid portion is made elastic by the hinge. Cannot contact the main body by its own weight alone. Therefore, in order to close the container after filling the contents with the container, it is necessary to fix the container with an adhesive tape, heat sealing, or the like, or to provide a mechanism for a stopper between the main body and the lid. Especially for plastic containers,
The following characteristics are required at each time when the contents are filled in the container and when the contents are stored. First, when producing a container, it is important to obtain a product at a high yield from a plastic sheet from the viewpoint of product cost. Therefore, it is required that the hinge has a minimum form. Also, when filling the container with the contents, the lid can be maintained in a state of being opened substantially horizontally with respect to the main body by its own weight, and when the lid is further closed, the main body and the lid are closed by the own weight of the lid. Is required to maintain a substantially sealed state. A container having such characteristics has a good lid tightness when filling the contents with an automatic filling machine, and is excellent in applicability to the filling machine. Further, a consumer may purchase a product filled in such a container, use a part of the content filled in the container, and store the remaining content in a refrigerator. In such a case, the hinge of the container must have good flexibility, the lid closes well even when repeatedly opened and closed at a low temperature, and have good sealing properties with the container body. However, hinges having various properties required for these plastic containers cannot be formed by the disclosed method.

[0005] In addition, the following problems can be cited as problems with the hinge forming method. Simply applying pressure to the position of the hinge of the plastic sheet with a pressing die does not form the hinge having the function of the hinge described above. When the thickness of the hinge is large, its rigidity also increases, and the flexibility of the hinge deteriorates. Further, when the sheet is pinched by a sharp pressing die, the sheet is easily sheared at the time of forming the hinge, or a hinge having an uneven thickness is formed. Further, in a case where a plurality of containers are formed from one sheet in one process, that is, in a case where so-called multi-cavity is performed, a uniform hinge is not easily formed in each container. Further, in the case of vacuum pressure forming, it is customary to set the temperature of the mold lower than the preheating temperature of the sheet, and to cool the sheet quickly after the sheet is formed. For this reason, the seat at the hinge installation position is also cooled, and satisfactory hinge formation is not performed. If the preheating temperature of the sheet is increased for the purpose of forming a thin hinge, the molded product may be wrinkled due to the sagging of the sheet. Therefore, there is a strong demand for the development of a container having the above-described characteristics and the development of a method and a hinge forming device for forming a uniform hinge portion together with the molding of a plastic container when forming a hinge.

[0006]

The present inventors have SUMMARY OF THE INVENTION may, was intense research in view of these circumstances, there have particular storage operability hinge described above arrangement, that superior hinge formation is performed The present invention has been completed.

That is, according to the present invention, a main body composed of a main body and an outer peripheral edge of the main body, and a lid composed of a lid and a peripheral periphery of the lid are integrally formed by a hinge, and a plane formed by the outer peripheral edge of the main body and a lid outer part are formed. When the lid is opened so that the plane formed by the peripheral edge is the same horizontal plane and the inner surface thereof is directed upward, the hinge connecting the outer peripheral edge of the main body and the outer peripheral edge of the lid to form an integrally molded product is merely located at a position higher than the same horizontal plane. An object of the present invention is to provide a hinged plastic container formed as a single piece . Also, the thickness of the hinge is 0.03-0.2 m
m is provided. Said
In the invention, the material is polyethylene terephthalate
Provide plastic containers. Furthermore, form a hinge
The degree of crystallinity of polyethylene terephthalate is
Or 0.001 to 0.1 greater than the crystallinity of the outer edge of the lid
A plastic container according to the invention is provided.

Hereinafter, the present invention will be described in detail. As the plastic sheet in the present invention, a sheet of a thermoplastic resin such as polyethylene terephthalate, amorphous polyethylene terephthalate, polyethylene, polystyrene, or polypropylene can be used. Preferably, polyethylene terephthalate is used. In particular, when the container requires transparency, amorphous polyethylene terephthalate is preferable, and it may be appropriately selected according to the purpose of use of the container.

The plastic container of the present invention is, for example, shown in FIG.
(A), and as shown in the figure, a hinge for integrally forming a main body portion composed of the main body of the container and the outer peripheral edge of the container, and a lid portion composed of the lid and the outer peripheral edge of the lid is referred to as an outer peripheral edge of the main body. When the lid is opened so that the outer peripheral edge of the main body and the outer peripheral edge of the lid are substantially in the same horizontal plane by being provided between the outer peripheral edge of the lid and an integrally molded container, the container is opened such that its inner surface faces upward, as shown in FIG. As shown in (1), only one hinge (H) is formed at a position higher than the horizontal plane. The thickness of the hinge varies depending on the thickness of the plastic sheet to be used and the weight of the lid portion.
When a 0.4 mm sheet is used, the thickness of the hinge is 0.1 mm.
It is preferably from 0.3 to 0.2 mm, more preferably from 0.04 to 0.12 mm for a 0.3 mm sheet.
It is. When amorphous polyethylene terephthalate is used for the molding plastic sheet, the crystallinity of the hinge is 0.001 to 0 greater than the crystallinity of the outer periphery of the main body or the outer periphery of the lid. .1 (0.1 to 10% when crystallinity is expressed in%), preferably 0.0
02 to 0.08 (when crystallinity is expressed in%, 0.2 to 8
%), Particularly preferably 0.003 to 0.06 (0.3 to 6% in terms of% crystallinity).
The degree of crystallinity was determined by the following equation by measuring the density by a density gradient tube method. By the function of the hinge installed in this way, the plastic container of the present invention can maintain a state in which the main body and the lid are opened substantially horizontally by their own weight,
In addition, when the lid is closed, the state in which the main body and the lid are in contact with each other by its own weight can be maintained.

[0010]

(Equation 1)

[0011] The method of forming the hinge of the plastic container of the present invention
As a method, for example, there is a method in which at least one of a pressing die or a receiving die for forming a hinge is heated and a sheet is pressed by a pressing die having an elastic mechanism . By using the pressing die having such an elastic mechanism, the clamping pressure in the formation of the hinge can be adjusted, the melting of the plastic sheet is prevented, and even when a plurality of hinges are simultaneously formed by multi-cavity. A uniform hinge is formed. The temperature of the pressing die or the receiving die is 80 to 200 ° C., depending on the plastic sheet used and the pressing time.
And more preferably 120 to 160 ° C.

[0012] Further , an apparatus used for the hinge forming method is provided .
Examples include at least one of the push-type or receiving-type for hinge formation has a heating device, there is one provided with a temperature regulating mechanism. The heating device may be installed in either a pressing die or a receiving die, but is more preferably a device installed in a pressing die, and is appropriately selected in consideration of the method of forming the main body and the lid. Also, have use a push-type having a resilient mechanism as a push to type, for example, by a spring or pneumatic pressure may be added to the elastic function, it may be used an elastic material such as heat resistance elastomers. Also,
As the receiving mold for forming the hinge on the plastic sheet, a part of the mold of the container body that forms the outer periphery of the main body (a mold for forming the outer periphery of the body) and a part of the mold of the container lid that forms the outer periphery of the lid (Cover outer peripheral edge forming type) A cutting edge having a height of 0.1 to 1 mm and a width of 0.3 to 1 mm is used. The size of this receiving mold is based on the thickness of the plastic sheet to be used, and the lid is formed such that the plane formed by the outer peripheral edge of the main body of the plastic container in which the main body and the lid are integrally formed and the plane formed by the outer peripheral edge of the lid are horizontal. When the part is opened and its inner surface is turned upward, the hinge which connects the outer peripheral edges to form an integrally formed product as shown in FIG. 1 (B) has a height selected so as to be installed above the horizontal plane. Have.

[0013] body and lid of the plastic container of the present invention having a hinge is formed by vacuum pressure forming, or matched forming method.

[0014]

EXAMPLES The present invention will be described in detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Embodiment FIG. 1A is a perspective view showing an example of a plastic container molded according to the present invention, and FIG. 1B is a sectional view thereof. Hereinafter, an example in which a container is formed by a vacuum pressure forming method using a sheet of amorphous polyethylene terephthalate having a thickness of 0.3 mm will be described with reference to FIGS.

(Apparatus) A plastic molding apparatus equipped with a hinge forming apparatus shown in FIG. 2 was used. This plastic molding device is an upper frame 2
Has a hinge forming die 8. An upper frame base 5 is installed inside the upper frame 2 via an upper frame stay 4, and a plug 6 for molding the container body is fixed to the upper frame base 5. The hinge forming die 8 is attached to the hinge forming press mounting plate 7 via a hinge forming press guide 10 and a compression spring 11. A piston rod 12 of an air cylinder 14 is screwed into the press mounting plate 7 and is fixed by a nut 13. Further, a guide rod is provided to prevent the press mounting plate 7 from rotating about the piston rod 12. 9 is fixedly provided on the upper frame base 5. Note that the hinge forming receiving die 37 is installed so as to protrude 0.8 mm above the outer peripheral edge forming die 41 and the lid outer peripheral forming die 42, and has a width of 0.5 mm and a length of 96 mm. The hinge forming die 8 is opposed to the hinge forming receiving die 37 and moves in the direction of the hinge forming receiving die 37. However, the hinge forming pressing die 8 includes a compression spring 11 for elastically pressing the sheet. Numeral 8 is supported by four compression springs 11 and constitutes an elastic pressing mechanism. A heater 16 is installed in the hinge forming die 8 to heat the hinge forming die 8. The heating temperature is detected by a thermocouple 19, and a signal thereof is sent to a control device (not shown) via a compensating lead 20 to control the temperature of the hinge forming die 8. The air cylinder 14 attached to the upper frame base 5 operates by receiving compressed air from an electromagnetic valve 15 through an air pipe. Lower frame 3
A vacuum suction connection port 32 is provided at a lower portion of the unit 1 and is connected to a vacuum suction device (not shown) by a connection hose. The container body part mold 35 and the hinge forming receiving mold 37 are respectively directly on the lower frame base 33, and the container lid mold 36 is the lid mold base 3.
9 and is attached to the lower frame 33 through the lower frame base 3.
3 is attached to the lower frame 31 via the lower frame stay 34. In addition, the main body mold 35 and the lid mold 36 include:
Numerous vacuum holes 38 for vacuum suction are formed, all of which communicate with the vacuum suction port 32. A vacuum hole 38 is also provided around the hinge forming receiving die 37 so that vacuum suction can be performed. Lowering of these upper frames 2, lower frame 31
The timing of operations such as the rise of the mold, the lowering of the hinge forming die 8, and the vacuum suction are separately determined so that a predetermined operation is performed by a molding control device (not shown).

(Molding Method) As shown in FIG. 2, a sheet 1 of amorphous polyethylene terephthalate having a thickness of 0.3 mm is heated in a preheating zone (not shown), and then the upper frame 2 and the lower frame of a container forming apparatus. It is installed between 31. The amorphous polyethylene terephthalate sheet 1 has a temperature of 100 to 12 suitable for the vacuum pressure forming method.
Preheated to 0 ° C. Next, as shown in FIG. 3, the upper frame 2 and the lower frame 31 are respectively moved so as to sandwich the sheet from above and below.
Push down in the direction of 5. At this time, the air in the lower frame is sucked from the vacuum suction port 32, and the air in the sheet 1, the main body mold 35 and the lid mold 36 is evacuated from the vacuum hole 38 to remove the sheet 1 from the cavity of the mold. Adhere to the surface. The compressed air is supplied to the compressed air inlet 3 of the upper frame 2 slightly behind the vacuum suction operation.
Then, the sheet 1 is fed into the upper frame, and the sheet 1 is pressed against the cavity surface of the main body mold 35 together with the vacuum suction operation to deform the sheet along the cavity. At this time, the hinge remains unformed. Next, after a few seconds from the start of the vacuum suction operation, the hinge forming press die 8 descends toward the hinge forming receiving die 37 as shown in FIG. 4, and squeezes the hinge forming portion of the sheet 1 while heating. ,
The hinge H shown in FIG. 5 is formed. In this case, the hinge forming die 8 is heated and adjusted to 140 ° C. The operation of the hinge forming apparatus before and after hinge formation is shown in FIGS. As shown in FIG. 5, the container provided with the hinge is released from the container forming apparatus by raising the upper frame and lowering the lower frame. The release sheet 1B is then trimmed to obtain the container shown in FIG.

(Measurement of Crystallinity) The densities of the outer peripheral edge of the lid and the hinge of the obtained container were measured by a density gradient tube method, and the crystallinity was determined by the above-described equation (1). The results are shown in Table 1.

[0019]

[Table 1]

[0020]

Plastic containers obtained by connecting the main body and the lid together by hinges container of the present invention according to the present invention comprises a plane main body outer peripheral edge make, as a plane lid outer periphery make is horizontal When the lid is opened, the lid can be kept open by its own weight, and when the lid is closed, it has the property of keeping the lid closed by contacting the main body by the weight of the lid. I have. Therefore, when filling the container with the contents,
The lid does not become an obstacle, and when using the container, the lid can be kept closed by its own weight, so it can be reused without using special fasteners, etc. When used, drying and moisture absorption can be prevented in refrigerated storage of the remaining contents.

[Brief description of the drawings]

1] Fig. 1 (A): 1 of the onset Ming plastic container
The perspective view which shows an example. FIG. 1B: a cross-sectional view thereof.

[2] In the plastic molding apparatus having a hinge forming apparatus according to the present onset Ming plastic containers, apparatus and cross-sectional view of a sheet of plastic sheet sandwiched pre-.

FIG. 3 is a cross-sectional view of the container body and the lid during vacuum pressure forming.

FIG. 4 is a cross-sectional view during hinge formation.

FIG. 5 is a cross-sectional view after completion of container molding.

FIG. 6 is an enlarged view of the hinge forming device in FIG. 3;

FIG. 7 is an enlarged view of the hinge forming device in FIG. 4;

[Explanation of symbols]

 Reference Signs List 1, 1B amorphous polyethylene terephthalate sheet 2 Upper frame 3 Compressed air inlet 6 Plug 8 Hinge forming die 16 Heater 31 Lower frame 32 Vacuum suction connection port 35 Container main body mold 36 Container lid mold 37 Hinge forming die 38 Vacuum hole 41 Main body outer peripheral edge forming type 42 Lid outer peripheral forming type H Hinge

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-16027 (JP, A) JP-A-61-199942 (JP, A) JP-A-58-194104 (JP, U) JP-A-59-194104 716 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B65D 1/34-1/36 B65D 43/14-43/16

Claims (4)

(57) [Claims] 1. A body composed of a main body and an outer peripheral edge of the main body, and a lid formed of a lid and an outer peripheral edge of the lid are integrally formed with a hinge, and a plane formed by the outer peripheral edge of the main body and an outer peripheral edge of the lid are formed. When the lid is opened so that the plane is the same horizontal plane and the inner surface is facing upward, only one hinge is formed at a position higher than the same horizontal plane by connecting the outer peripheral edge of the main body and the outer peripheral edge of the lid and forming an integrally molded product. A hinged plastic container characterized by being made. 2. The plastic container according to claim 1, wherein the hinge has a thickness of 0.03 to 0.2 mm. 3. The plastic container according to claim 1, wherein the material is polyethylene terephthalate. 4. The plastic container according to claim 3, wherein the degree of crystallinity of the polyethylene terephthalate forming the hinge is 0.001 to 0.1 greater than the degree of crystallinity of the outer peripheral edge of the main body or the outer peripheral edge of the lid.