JP7093120B2 - Packaging container lid and its molding method - Google Patents

Description

The present invention relates to a lid of a molded container obtained by molding a synthetic resin sheet, and relates to a configuration capable of improving the visibility of the contents while maintaining the rigidity of the lid itself.

Sheet-molded food packaging containers, which are widely used in supermarkets and department stores, protect the foodstuffs stored in the containers and place importance on load resistance when stacking and displaying the containers. Rigidity is required not only for the container body but also for the lid. Generally, in order to improve the rigidity of the packaging lid, reinforcing ribs are often attached to the top surface and side walls of the lid. However, if ribs are attached to these portions, there is a problem that the visibility of the foodstuff in the container is lowered. Therefore, there is a need for a means for simultaneously solving the contradictory problems of improving the visibility of foodstuffs and at the same time ensuring the rigidity of the lid.

Japanese Unexamined Patent Publication No. 2012-30887 Japanese Unexamined Patent Publication No. 2014-141270

In the invention described in Patent Document 1, a plurality of vertical ribs are formed on the side wall portion as one means for maintaining the rigidity of the lid. However, there is a problem that the visibility from the side surface direction is inferior due to the provision of the rib. In the invention described in Patent Document 2, since the rib is similarly provided on the side wall portion of the lid, the visibility from the side surface direction is inferior. In addition, the container in which this type of lid is used has one aspect that it is important to visually appeal to the customer, such as sashimi and prepared foods, and to motivate the purchase. Visibility from the side, that is, the side wall, is important because it may be displayed.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a lid of a packaging container that maintains rigidity and improves visibility.

In order to achieve the above-mentioned object, in the present invention, in the lid of the packaging container formed by molding the sheet material made of thermoplastic resin, the top plate portion having a polygonal plan view and the periphery of the top plate portion. The top plate portion is composed of a flat surface, and the side wall portion is connected to the top plate portion and the adjacent side wall portion via a linear continuous portion. A means is used in which the dihedral angle θ formed by the top plate portion and the side wall portion is θ> 90 °, and the radius of curvature R on the surface side of the continuous portion is R ≦ 0.6 mm. board.

According to the above means, the top plate portion is composed of a flat surface, and the portion connected to the top plate portion of the side wall portion is composed of a flat surface portion, so that the visibility of the contents is extremely good as if it were covered with glass. Is. Moreover, since the side wall portion supports the top plate portion almost vertically and each continuous portion is formed by a curved surface having an extremely small radius of curvature, the continuous portion has a relatively gentle curve with a radius of curvature exceeding 0.6 mm. Compared with the case where it is formed in, the resistance to bending and twisting is increased, and the rigidity can be maintained without using ribs. In this respect, the numerical value of 0.6 mm allows some error as long as the action and effect of the present invention can be achieved. The top plate portion is typically a rectangle or a square in a plan view, but may be a polygon other than that. Further, the fact that the continuous portion is linear means that there is no deformed portion such as a rib in the continuous portion. Further, the surface side of the continuous portion means the outer surface side of the outside of the container. On the other hand, the back surface side of the continuous portion, that is, the inner surface side inside the container is naturally smaller than the radius of curvature on the front surface side, but the specific numerical values are the thickness of the sheet material used and the mold. Since it depends on the edge shape in contact with the continuous portion, it is not specified.

Further, in the above means, the dihedral angle θ formed by the top plate portion and the side wall portion is set to more than 90 °. Originally, 90 ° has the highest load capacity in the vertical direction and is mechanically preferable, but this makes it difficult to stack multiple molded lids, and it is difficult to separate the lids if they are forcibly stacked. be. However, if the dihedral angle θ is too large, when a plurality of packaging containers containing the contents are stacked, the side wall portion expands outward due to the weight of the upper stage, and the lid is squeezed. Since there is a risk, the maximum angle is 105 ° at most.

On the other hand, as the sheet material for molding the lid, a thermoplastic polyester resin is suitable. As the thermoplastic polyester resin, PBT resin (polybutylene terephthalate resin), PEN resin (polyethylene naphthalate resin), PET resin (polyethylene terephthalate resin), PETG resin (a part of ethylene glycol in polyester is replaced with cyclohexanedimethanol). Modified polyester resin), SPG resin (modified polyestes resin in which a part of ethylene glycol is replaced with spiroglycol in polyester) and the like can be mentioned. Among them, it is preferable to select a PET resin having excellent workability, moldability, and cost.

When the sheet material is a PET resin, the IV value of the PET resin (based on JIS K7367-1) is 0.70 to 0.85 in order to more reliably achieve the above-mentioned means. It is more preferable that the moisture content of the sheet material (curl Fisher coulometric titration method based on JIS K0113) is less than 1500 PPM and the thickness of the sheet material is 0.10 to 0.80 mm.

Further, the thickness of the sheet material is preferably 0.20 to 0.50 mm, and if the sheet material has the thickness, it is possible to achieve both the maintenance of rigidity and the visibility at a higher level.

Further, the method for molding the lid of the present invention is preferably a vacuum forming method in which the sheet material is evacuated to the male mold side in order to carry out the above-mentioned means more satisfactorily. However, a pressure forming method in which the sheet material is brought into close contact with the mold by compressed air may be adopted, and it can also be used in combination with the vacuum forming method.

According to the present invention, although the top plate portion and the side wall portion have a planar structure, ribs are not formed in the portions that hinder the visibility of the contents while maintaining the rigidity. The visibility can be greatly improved.

Perspective view of a packaging container according to an embodiment of the present invention. Same as above, plan view of the lid Same, side view of the lid AA line end view in FIG. BB line end view in FIG. Process diagram showing the molding method of this invention

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of a packaging container according to an embodiment of the present invention, showing the lid 10 and the container body 20 separately. On the other hand, FIGS. 2 and 3 are a plan view and a side view showing only the lid 10. The lid 10 has a flange portion 11 to be attached to the opening edge of the container body 20 from the outside, and a concave lid fitting portion 12 to be fitted to the main body fitting portion 21 is further provided on the side surface of the flange portion 11. The portion that protects the contents housed in the container main body 20 is composed of a top plate portion 1 and a side wall portion 2 that is continuously provided around the top plate portion 1.

The top plate portion 1 is a rectangular shape in a plan view, which is entirely composed of a flat surface. A side wall portion 2 is continuously provided on each of the four sides of the top plate portion 1 via the continuous portion 3. Each of the continuous portions 3 is a straight line in the horizontal direction along the four sides of the top plate portion 1, but as a whole, it forms the same rectangular shape in a plan view as the top plate portion 1.

In the case of this embodiment, the side wall portion 2 has a two-stage configuration in which the upper flat surface portion 4 and the lower flat surface portion 5 are interposed via the boundary portion 6, as is often shown in FIG. Of these, the upper flat surface portion 4 is connected to the top plate portion 1 via the above-mentioned horizontal continuous connection portion 3, and the adjacent upper flat surface portions 4 are connected to each other in a vertical linear shape. It is installed continuously. On the other hand, the lower flat surface portion 5 is connected to the upper flat surface portion 4 via the boundary portion 6, and the adjacent lower flat surface portions 5 are connected to each other via the triangular chamfered portion 8. Here, since the upper flat surface portion 4 and the lower flat surface portion 5 have the same rising angle from the flange portion 11 side to the top plate portion 1 side and are so-called flush with each other, they are actually linear as shown in the drawing. Although the boundary portion 6 of the above does not exist, there is a difference in the continuous configuration of adjacent to each other, that is, the linear continuous portion 7 in the upper flat surface portion 4 and the triangular chamfered portion 8 in the lower flat surface portion 5. For convenience of explanation, the boundary portion 6 is used.

The side wall portion 2 is formed with a stacking protrusion 9 that bulges out of the container, straddling the lower flat surface portion 5 and the flange portion 11. This prevents the lids from completely fitting into each other when the lids 10 are overlapped with each other, and when the lid 10 is closed to the container body 20 containing the contents (foodstuffs, etc.). It is easy to take out one by one.

Explaining the characteristic configuration of the lid 10 according to FIGS. 4 and 5, first, the dihedral angle formed by the top plate 1 and the side wall 2 (upper plane portion 4) is the long side of the lid 10. Both the short side and the short side are set to more than 90 ° and 105 ° or less. Specifically, the dihedral angle θ1 on the long side is set to 97.0 ° as shown in FIG. 4, and the short side is not shown, but it is still over 90 ° and 105 °. It is set as follows. Further, the angle θ2 formed by the top plate portion 1 and the continuous portion 7 at the corner portion of the lid 10 is set to 100.0 ° as shown in FIG. The two sets of dihedral angles on the long side and the short side can be set to different angles within the above range. By making the angles different in this way, when the containers containing the contents are displayed, the appearance of the display can be changed as compared with the ones having the same angle, and the customer attraction can be enhanced.

Further, in the continuous portion 3 between the top plate portion 1 and the side wall portion 2 (upper flat surface portion 4) and the continuous portion 7 between the side wall portions 2 (upper flat surface portion 4), the radius of curvature R on the surface side thereof is all. It is set to 0.4 mm. This numerical value is also an example, and it is preferable to set it smaller, but if it is 0.6 mm or less, the object of the present invention can be achieved.

By forming the top plate portion 1 and the side wall portion 2 as described above, the lid 10 has good visibility while maintaining rigidity. That is, with regard to rigidity, since the top plate portion 1 is supported substantially vertically by the side wall portion 2, the load bearing capacity is increased, and the continuous portions 3.7 are formed into a curved surface having an extremely small radius of curvature, whereby bending and twisting are performed. Increases resistance to.

Regarding visibility, the top plate portion 1 is entirely flat, the side wall portion 2 is also entirely flat in the upper flat portion 4, and the lower flat portion 5 is composed of flat surfaces except for the stacking protrusion 9. Therefore, the contents can be clearly seen without distortion not only from directly above or diagonally above, but also from the side.

It should be noted that the colorless and transparent lid 10 can maximize visibility, but is not limited in terms of color and transparency. Further, the molding material, that is, the sheet material can be selected from conventionally known thermoplastic resins, but thermoplastic polyester resins such as PBT resin, PEN resin, PET resin, PETG resin, and SPG resin are preferable. .. In particular, it is preferable to select a PET resin having excellent workability, moldability, and cost.

Further, when the lid 10 is molded from a PET resin sheet material, a PET resin having an IV value (based on JIS K7367-1) of 0.70 to 0.85 is used to obtain a moisture content (based on JIS K0113). It is preferable to use a sheet material having a curl Fisher coulometric titration method) of less than 1500 PPM and a thickness of 0.10 to 0.80 mm. If the sheet thickness is in the range of 0.20 to 0.50 mm, the above-mentioned rigidity and visibility can be achieved at a higher level.

Next, the molding method of the lid 10 will be described with reference to FIG. (A) to (e) of the figure are conceptual diagrams showing the molding process of the lid body 10. First, the above-mentioned thermoplastic resin sheet material 30 is heated by a double-sided heater 31 to be softened (FIG. 6). (A)). Then, the softened sheet material 30 is conveyed between the mold (male mold) 32 and the plug 33 (FIG. 6 (b)), the mold 32 is raised, and the molded surface thereof is pushed against the sheet material 30. Hit (Fig. 6 (c)). In this state, the plug 33 is operated so as to seal the sheet material 30 with the mold 32, and evacuation is performed through a large number of suction holes 32a provided through the mold 32 (FIG. 6 (d)). ). Then, the mold 32 and the plug 33 are returned to their original positions and released from the mold (FIG. 6 (e)), and then the excess portion is cut and trimmed to obtain the lid 10.

Here, the vacuum forming method has been described as the molding method of the lid 10, but a pressure forming method in which the softened sheet material is brought into close contact with the mold by compressed air may be adopted, and these vacuum forming methods and the pressure forming methods may be used. It is also possible to adopt at the same time.

1 Top plate part 2 Side wall part 3.7 Continuous part 4 Upper flat part 5 Lower flat part 6 Boundary part 8 Chamfering part 9 Stacking protrusion 10 Lid 20 Container body 30 Sheet material 31 Heater 32 Mold (male type)
32a Suction hole 33 plug

Claims (4)

In the lid of a packaging container made by molding a sheet material made of thermoplastic resin,
The top plate, which has a polygonal view in plan view,
A side wall portion continuously provided around the top plate portion and a side wall portion
A flange portion formed around the side wall portion is provided .
The top plate portion is composed of a flat surface.
The side wall portion has a flat surface portion that is continuously connected to the top plate portion and the adjacent side wall portion via a linear continuous portion.
The flat surface portion has an upper flat surface portion in which adjacent plane portions are continuously connected via a linear continuous portion in the vertical direction, and the lower end and the apex of the continuous flat portion in which the adjacent flat surface portions are connected to each other in the vertical direction. It has a lower flat surface portion that is continuously connected via a triangular chamfered portion.
The upper flat surface portion and the lower flat surface portion form a flush plane with the same rising angle from the flange portion side toward the top plate portion.
The dihedral angle θ formed by the top plate portion and the side wall portion is 90 ° <θ≤105 °.
A lid of a packaging container characterized in that the radius of curvature R on the surface side of the continuous portion is R ≦ 0.6 mm. The sheet material is made of PET resin and is made of PET resin.
The IV value of the PET resin (based on JIS K7367-1) is 0.70 to 0.85.
The moisture content of the sheet material (Karl Fischer potentiometric titration method based on JIS K0113) is less than 1500 PPM.
The lid of the packaging container according to claim 1 , wherein the thickness of the sheet material is 0.10 to 0.80 mm. The lid of the packaging container according to claim 2 , wherein the thickness of the sheet material is 0.20 to 0.50 mm. The method for molding a lid of a packaging container according to any one of claims 1 to 3 .
A method for molding the lid of a packaging container, which is characterized by a vacuum forming method in which the sheet material is evacuated to the male mold side.

Images