Composite container

Abstract

To provide a composite container that reduces the amount of resin used while offering excellent airtightness when the lid is closed. [Solution] A bottomed cylindrical composite container 1 made primarily of paper and having an opening 5 on its top surface, comprising: a resin frame 10 having an annular frame 20 forming the opening 5 and a side frame 30 connected to the annular frame 20; a paper side 60 joined to the annular frame 20 and the side frame 30; and a threaded portion 21 provided on the annular frame 20 having outwardly protruding threads 25, wherein when the thickness of the threads 25 in the lead direction is X and the thickness of the opening 5 is Y, the condition X ≤ Y ···(1) is satisfied, the threading start position S of the threads 25 is set a certain distance or more from the end of the opening 5, and the top surface side of the threads 25 is cut flat.

Description

Technical Field

[0001] The present invention relates to a bottomed cylindrical composite container mainly made of paper and having an opening on the top surface.

Background Art

[0002] In recent years, for the purpose of reducing the environmental load, reduction of the amount of resin used in containers has been demanded. As such a container, a composite container in which a part of the container is replaced with paper blanks (a laminate including a paper layer and a resin layer) has been proposed (for example, see Patent Document 1).

[0003] The composite container described in Patent Document 1 is configured by using a resin framework and a paper cylindrical body for the housing part, so that the amount of resin used can be reduced compared with the case where the entire housing part is made of resin.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the composite container of Patent Document 1, when the amount of resin used in the composite container is greatly reduced, when the paper cylindrical body is deformed, the resin framework follows the deformation, so that the opening of the container is distorted (for example, deformed into an elliptical shape), and the roundness (the difference between the maximum diameter and the minimum diameter) of the opening is reduced. When the opening of the container is distorted and the roundness is reduced, a gap occurs when the lid is closed, resulting in impaired airtightness and a risk of leakage of the contents from the container.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a composite container that is excellent in airtightness when the lid is closed while reducing the amount of resin used. [Means for solving the problem]

[0007] The characteristic configuration of the composite container according to the present invention, which solves the above problems, is A bottomed cylindrical composite container made primarily of paper, with an opening on the top surface, A resin frame having an annular frame portion that forms the opening, and a side frame portion connected to the annular frame portion, The annular skeletal portion and the side skeletal portion are joined to the paper side portion, A threaded portion provided on the annular skeletal part, having outwardly protruding threads, Equipped with, When the thickness of the screw thread in the lead direction is X and the thickness of the opening is Y, X ≤ Y ···(1) Satisfying the conditions, The starting position for threading the aforementioned screw thread is set at a certain distance or more from the end of the opening, The top surface of the screw thread is cut flat.

[0008] This composite container configuration includes a resin frame and paper side panels, thus reducing the amount of resin used compared to a container entirely made of resin. However, in a composite container, if the thickness Y of the opening is made thin to reduce the amount of resin used, sink marks will occur on the back side of the screw threads (inner surface of the opening). If these sink marks coincide with the contact point between the lid and the opening (sealing point), it will affect the airtightness when the lid is closed. With this composite container configuration, the relationship between the thickness X in the lead direction of the screw threads and the thickness Y of the opening satisfies equation (1) above, making it less likely for sink marks to occur on the back side of the screw threads. Furthermore, because the threading start position of the screw threads is set a certain distance from the end of the opening, even if sink marks occur on the back side of the screw threads, they will not coincide with the sealing point when the lid is closed. In addition, because the top surface of the screw threads is cut flat, a flat surface is formed on the screw threads while reducing the amount of resin used in the screw threads. This flat surface and the screw threads formed on the lid make at least line contact, enabling stable capping. Based on the above, when the lid is closed, no gap is created between the lid and the opening, making it possible to provide a composite container with excellent airtightness.

[0009] In the composite container according to the present invention, Let Z be the distance from the end of the opening to the threading start position. When the pitch of the screw thread is W, W ≤ Z ···(2) It is preferable that the following conditions be met.

[0010] With this composite container configuration, the relationship between the distance Z from the end of the opening to the threading start position and the thread pitch W satisfies equation (2) above, allowing a sealing point to be set between the end of the opening and the threading start position. As a result, even if sink marks occur on the back side of the threads, when the lid is closed, the sink marks do not overlap with the sealing point, thus providing a composite container with excellent airtightness when the lid is closed.

[0011] In the composite container according to the present invention, The threaded portion is preferably a multi-start thread.

[0012] According to the composite container of this configuration, since the threaded portion is a multi-start thread, even if the lid is closed with a small number of rotations, a composite container with excellent airtightness can be provided.

[0013] In the composite container according to the present invention, It is preferable that the paper conversion rate is 50% or more.

[0014] According to the composite container of this configuration, since the paper conversion rate is 50% or more, the amount of resin used can be reduced to less than half of that of conventional containers.

Brief Description of the Drawings

[0015] [Figure 1] FIG. 1 shows a perspective view of a composite container according to an embodiment of the present invention, (a) is a state where a lid is attached to the composite container, and (b) is a state where the lid is removed from the composite container. [Figure 2] FIG. 2 is a plan view and a side view of the composite container. [Figure 3] FIG. 3 is a cross-sectional end view at the A-A position of the composite container in FIG. 1(a). [Figure 4] FIG. 4 is a cross-sectional end view at the B-B position of the composite container in FIG. 1(b). [Figure 5] FIG. 5 is a plan view of the side surface portion and the bottom surface portion in the unfolded state before assembling the composite container.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, the present invention will be described with reference to the drawings. However, the present invention is not intended to be limited to the configurations described in the embodiments and drawings below. Regarding the sizes and thicknesses of each part shown in the drawings, they are enlarged as appropriate for ease of explanation and do not strictly reflect the actual size relationships (scale). In the following description, unless otherwise specified, the side where the opening 5 of the composite container 1 is arranged is referred to as the "top surface", and the side where the bottom surface portion 60 is arranged is referred to as the "bottom surface".

[0017] <Overall Structure> FIG. 1 shows a perspective view of a composite container 1 according to an embodiment of the present invention. (a) shows a state in which a lid C is attached to the composite container 1, and (b) shows a state in which the lid C is removed from the composite container 1. The composite container 1 is a bottomed cylindrical container mainly made of paper and having an opening 5 on the top surface, and the contents are put into the composite container 1 through the opening 5. Here, the main material refers to a material whose proportion in the total materials used for the composite container 1 is 50% or more, preferably 70% or more, more preferably 90% or more based on weight. In the composite container 1 of the present embodiment, it is preferable that the weight ratio of the paper used for the composite container 1 (hereinafter referred to as "paperization rate") is 50% or more with respect to the total weight of the composite container 1. By having a paperization rate of 50% or more, the amount of resin used can be reduced to less than half of that of a conventional container.

[0018] As shown in FIG. 1(b), the composite container 1 includes a resinous skeleton part 10, and a paper-made side part 50 and bottom part 60. By being configured in this way, the amount of resin used can be reduced as compared with the case where the entire container is made of resin. The composite container 1 is formed by insert molding the side part 50 and the bottom part 60 into the skeleton part 10. For example, it can be molded by injection molding the skeleton part 10 in a state where the die-cut side part 50 and bottom part 60 are accommodated in a molding die. Hereinafter, each component included in the composite container 1 will be described in detail.

[0019] <Skeleton Part> As shown in FIG. 1(b), the skeleton part 10 has an annular skeleton part 20, a side skeleton part 30, and a bottom skeleton part 40. The side skeleton part 30 is connected to the annular skeleton part 20 and the bottom skeleton part 40, and the annular skeleton part 20, the side skeleton part 30, and the bottom skeleton part 40 are integrally molded by injection molding. As the material for forming the skeleton part 10, thermoplastic resins such as polyethylene, polypropylene, polyester, and polyamide are preferable.

[0020] 〔Annular Skeleton Part〕 The annular frame portion 20 is annular and forms the opening 5. The annular frame portion 20 is cylindrical and is configured to cover the top end face of the side portion 50. In this embodiment, the threaded portion 21, lip 22, and reinforcing rib 23 constituting the annular frame portion 20 are arranged in this order from the top side to the bottom side. The annular frame portion 20 is also provided with a protrusion 24 (see Figure 4) that can make line contact with the lid C when the lid C is closed. In this embodiment, the lid C is attached to the annular frame portion 20 by screw engagement between the threads 25 of the threaded portion 21 and the threads of the lid C (not shown). However, in the annular frame portion 20, a convex or concave engaging portion may be provided instead of the threaded portion 21, and the lid C may be attached by the engagement of the concave or convex engaging portion provided on the lid C with the engaging portion.

[0021] The lip 22 is annular and protrudes outward. As shown in Figure 1(a), the top surface of the lip 22 abuts against the lower end of the lid C when the lid C is attached to the annular frame 20. Because the lip 22 is annular and protrudes outward, the section modulus can be increased over the entire circumference of the annular frame 20, which contributes to maintaining the roundness of the opening 5. However, if the thickness (axial width) of the lip 22 increases, the amount of resin used increases, and the paper-based ratio of the composite container 1 becomes less than 50%. Therefore, it is preferable that the thickness of the lip 22 be set to 0.5 mm to 2 mm. By setting the thickness of the lip 22 to 0.5 mm to 2 mm, it is possible to provide a composite container 1 with a paper-based ratio of 50% or more while maintaining the roundness of the opening 5.

[0022] In the composite container 1, reducing the amount of resin used in the annular skeletal portion 20 that forms the opening 5 makes it easier for the annular skeletal portion 20 to follow the deformation of the paper side portion 50 (from a curved shape when viewed from above to a straight shape), and the opening 5 becomes an elliptical shape with the straight line connecting the connection point between the annular skeletal portion 20 and the side skeletal portion 30 as its major axis, which may reduce its roundness. Also, in the composite container 1, if the thickness of the opening 5 is set to be thin in order to reduce the amount of resin used, sink marks will occur on the back side of the screw threads 25 (the inner surface of the opening 5), and if these sink marks overlap with the part where the lid C and the opening 5 come into contact (sealing point), it will affect the airtightness when the lid C is closed. Therefore, in the present invention, the problem of reduced airtightness due to the reduction in the amount of resin used is solved by providing reinforcing ribs 23 or protrusions 24 in the composite container 1, or by devising the configuration of the screw portion 21. The configurations of the reinforcing ribs 23, protrusions 24, and screw portion 21, which are characteristic of the present invention, will be described in detail below.

[0023] [Reinforcement ribs] The reinforcing ribs 23 reinforce the annular skeletal portion 20 that forms the opening 5. Because the composite container 1 is equipped with the reinforcing ribs 23, even if the paper side portion 50 attempts to deform from a curved shape to a straight shape due to elastic restoring force when viewed from above, the shape of the annular skeletal portion 20 is maintained against that elastic restoring force, and deformation of the opening 5 can be suppressed. Therefore, by maintaining the roundness of the opening 5, no gap is created between the lid C and the opening 5 when the lid C is closed, and a composite container 1 with excellent airtightness can be provided.

[0024] Preferably, the reinforcing rib 23 is provided integrally with the lip 22 on the bottom side (lower side) of the lip 22, along the direction in which the lip 22 extends, as shown in Figure 1. By providing the reinforcing rib 23 on the lip 22, deformation of the annular lip 22 can be suppressed. As a result, the roundness of the opening 5 is maintained, and a composite container 1 with excellent airtightness when the lid C is closed can be provided.

[0025] The reinforcing ribs 23 are preferably provided near the connection point between the annular frame portion 20 and the side frame portion 30, as shown in Figure 1. The reinforcing ribs 23 are provided near the connection point between the annular frame portion 20 and the side frame portion 30, which are particularly prone to deformation, because the elastic restoring force of the side portion 50 is strongest thereon. This ensures that the roundness of the opening 5 is maintained while reducing the amount of resin used, and a composite container 1 with excellent airtightness when the lid C is closed can be provided.

[0026] Figure 2 shows a plan view and a side view of the composite container 1. In the plan view of Figure 2, the screw threads 25 and the bottom frame portion 40 are omitted, and the overlapping portion of the lip 22 and the reinforcing rib 23 is shown in black. As shown in the plan view of Figure 2, when viewed from above, it is preferable that the reinforcing rib 23 is provided in an angular region R of ±1 to 5° from the center O of the annular frame portion 20, with reference to the straight line connecting the center O of the annular frame portion 20 and the connection point P between the annular frame portion 20 and the side frame portion 30. By providing the reinforcing rib 23 in an angular region R of ±1 to 5°, it is possible to effectively reinforce the area near the connection point between the annular frame portion 20 and the side frame portion 30, which is particularly prone to deformation, while suppressing the increase in the amount of resin due to the provision of the reinforcing rib 23. If the angular region R in which the reinforcing rib 23 is provided is greater than ±5°, the amount of resin used will increase, and the paper content of the composite container 1 will fall below 50%. Furthermore, if the angular region R in which the reinforcing ribs 23 are provided becomes smaller than ±1°, the effect of reinforcing the annular frame portion 20 is not sufficiently obtained, and the roundness of the opening 5 decreases.

[0027] [Convex part] Figure 3 is a cross-sectional view of the composite container 1 at position AA in Figure 1(a). The protrusion 24 is provided on the annular frame 20 so that it can make line contact with the lid C when the lid C of the composite container 1 is closed. By providing the protrusion 24, when the lid C is closed, the protrusion 24 and the side surface of the lid C compete with each other, improving the airtightness between the annular frame 20 and the lid C. Therefore, when the lid C is closed, no gap is created between the lid C and the opening 5, and a composite container 1 with excellent airtightness can be provided. The protrusion L of the protrusion 24 (amount of protrusion from the inner circumferential surface of the annular frame 20) is preferably 0.01 mm to 0.5 mm, and more preferably 0.05 mm to 0.1 mm. If the protrusion L of the protrusion 24 is greater than 0.5 mm, molding defects will occur during insert molding. Furthermore, if the protrusion L of the protrusion 24 becomes smaller than 0.01 mm, the protrusion 24 and the side surface of the lid C will not come into contact, which may impair airtightness.

[0028] It is preferable that the protrusions 24 are formed to extend in the circumferential direction of the annular skeleton portion 20. By forming the protrusions 24 to extend in the circumferential direction of the annular skeleton portion 20, the protrusions 24 contribute to improving the roundness of the opening 5. Furthermore, when the lid C is closed, the protrusions 24 and the side surface of the lid C compete with each other around the entire circumference of the opening 5, so that the amount of resin used can be reduced while maintaining the roundness of the opening 5. As a result, a composite container 1 with excellent airtightness when the lid C is closed can be provided.

[0029] The protrusion 24 is preferably formed to protrude inward from the annular skeletal portion 20, as shown in Figure 3. By forming the protrusion 24 to protrude inward from the annular skeletal portion 20, the outer surface of the inner ring I provided on the lid C comes into contact with the protrusion 24. Therefore, no gap is created when the lid C is closed, and a composite container 1 with excellent airtightness can be provided.

[0030] [Screw part] Figure 4 is a cross-sectional view of the composite container 1 at position BB in Figure 1(b). The threaded portion 21 has outwardly projecting threads 25 formed at a predetermined pitch W. As shown in Figure 4, the relationship between the thickness X of the threads 25 in the lead direction and the thickness Y of the opening 5 is given by the following equation (1): X ≤ Y ···(1) If the conditions are met, sink marks are less likely to occur on the back side of the screw threads 25. Also, as shown in Figure 1(b), since the threading start position S of the screw threads 25 is set a certain distance away from the end of the opening 5, even if sink marks occur on the back side of the screw threads 25, when the lid C is closed, the sink marks will not overlap with the sealing point. Furthermore, as shown in Figure 4, since the top side of the screw threads 25 is cut flat, the amount of resin in the screw threads 25 is reduced, a flat portion 25a is formed on the screw threads 25, and the flat portion 25a and the screw threads 25 formed on the lid C make at least line contact, enabling stable capping. As a result, when the lid C is closed, no gap is created between the lid C and the opening 5, and a composite container 1 with excellent airtightness can be provided. Note that "thickness of the opening 5" is, in other words, the radial thickness of the screw portion 21 in the part where the protrusion 24 and screw threads 25 are not provided.

[0031] In this embodiment, in addition to satisfying the relationship of equation (1) above, as shown in Figure 4, the relationship between the distance Z from the end of the opening 5 (upper end of the threaded portion 21) to the threading start position S and the pitch W of the thread 25 (distance between adjacent threads 25 in Figure 4) is given by the following equation (2): W ≤ Z ···(2) It is preferable that the following conditions are met. The relationship between the distance Z from the end of the opening 5 to the threading start position S and the pitch W of the thread 25 satisfies the above equation (2), so that a sealing point can be set between the end of the opening 5 and the threading start position S. As a result, even if sink marks occur on the back side of the thread 25, when the lid C is closed, the sink marks do not overlap with the sealing point, so a composite container 1 with excellent airtightness when the lid C is closed can be provided.

[0032] The threaded portion 21 is preferably a multi-start thread. Having a multi-start thread in the threaded portion 21 allows the lid C to be closed with fewer rotations, and even when the lid C is closed with fewer rotations, a composite container 1 with excellent airtightness can be provided. Furthermore, in this embodiment, since the threads 25 are intermittent threads (skipping threads) provided intermittently in the circumferential direction, resin is not required in the intermittent portions, thus reducing the amount of resin in the threads 25.

[0033] [Side frame section] The side frame portion 30 is formed in a columnar shape, with one end (upper end) connected to the annular frame portion 20 and the other end (lower end) connected to the bottom frame portion 40. In this embodiment, two side frame portions 30 are provided at opposing positions, joining the lateral end faces of the side portion 50.

[0034] The side frame portion 30 has a linear projection 30a formed to extend in the vertical direction and a plate portion 30b provided on the inner surface of the composite container 1. The linear projection 30a is arranged so that it can abut the circumferential ends of the side portion 50. In this embodiment, a reinforcing rib 23 is provided at the position where the linear projection 30a and the lip 22 intersect. In this way, the interaction of the lip 22, the reinforcing rib 23, and the linear projection 30a makes it possible to more reliably maintain the shape of the annular frame portion 20.

[0035] [Bottom frame] As shown in Figure 1(b), the bottom frame 40 has a hollow disc-shaped disc portion 41 and a bottom reinforcement portion 42. The bottom frame 40 is positioned to have the same central axis as the annular frame 20 and is connected to the side frame 30. The disc portion 41 joins the bottom-side end face of the side frame 50 to the end face of the outer periphery of the bottom frame 60. The bottom reinforcement portion 42 is provided to connect the vicinity of the connection point between the disc portion 41 and the side frame 30, passing through the center of the disc portion 41 to the vicinity of the connection point between the opposing disc portion 41 and the side frame 30.

[0036] <Side part / Bottom part> The side sections 50 and bottom section 60 are die-cut from paper blanks, which are laminates containing a paper layer and a resin layer. The paper blanks used for the side sections 50 and bottom section 60 consist of five layers, arranged in order from the outside of the composite container 1: an outer resin coating layer, a paper layer, an adhesive resin layer (adhesive layer), a gas barrier layer, and an inner resin coating layer. The paper blanks may also have other layers, such as a toughening layer and a printing ink layer.

[0037] Figure 5 is a plan view of the side portion 50 and bottom portion 60 of the composite container 1 in its unfolded state before assembly. The side portion 50 has a first side portion 51 and a second side portion 52 and is formed in a substantially rectangular shape. As shown in Figure 5, the first side portion 51 is connected to both ends of the substantially circular bottom portion 60 via valley fold lines 71, and the second side portion 52 is connected via valley fold lines 72. In addition, cutting lines 73 and 74 are formed at the boundaries between the bottom portion 60 and the first side portion 51 and the second side portion 52.

[0038] Although the composite container of the present invention has been described above based on embodiments, the present invention is not limited to the configuration described in the above embodiments, and its configuration can be modified as appropriate without departing from the spirit of the invention. [Industrial applicability]

[0039] Because the composite container of the present invention has excellent airtightness when the lid is closed, it can be used as a container for storing easily flowing contents such as powders, liquids, and semi-solids. [Explanation of Symbols]

[0040] 1. Composite container 5 Openings 10 Skeletal parts 20 Annular skeletal part 21 Threaded part 22 Lip 23 Reinforcement Ribs 24 Convex part 25 threads 30 Side frame section 40 Bottom frame 50 Side part O Center of the annular skeletal structure P is the connection point between the annular skeletal section and the lateral skeletal section. R angle area S Thread cutting start position

Claims

1. A bottomed cylindrical composite container made primarily of paper, with an opening on the top surface, A resin frame having an annular frame portion that forms the opening, and a side frame portion connected to the annular frame portion, The annular skeletal portion and the side skeletal portion are joined to the paper side portion, A threaded portion provided on the annular skeletal part, having outwardly protruding threads, Equipped with, When the thickness of the screw thread in the lead direction is X and the thickness of the opening is Y, X≦Y...(1) Satisfying the conditions, The starting position for threading the aforementioned screw thread is set at a certain distance or more from the end of the opening, The top surface of the aforementioned screw threads is cut flat in this composite container.

2. Let Z be the distance from the end of the opening to the threading start position. When the pitch of the screw thread is W, W≦Z...(2) A composite container according to claim 1 that satisfies the requirements.

3. The composite container according to claim 1, wherein the threaded portion is a multi-start thread.

4. A composite container according to any one of claims 1 to 3, wherein the paper conversion rate is 50% or more.

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