JP5554604B2 - Integrated plastic cap - Google Patents

Description

  The present invention relates to an improvement of an integrally molded plastic cap that is attached to a mouth of a container such as a PET bottle for sealing.

  Conventionally, as this type of cap, as in Patent Documents 1 and 2 below, an inner annular seal piece that seals the container mouth from the inside and an outer annular seal that seals the container mouth from the outside on the inner surface of the top wall An integrally molded plastic cap having a piece projecting downward is known. The present applicant has also proposed an integrally molded plastic cap provided with an inner annular seal piece and an outer annular seal piece as in Patent Document 3 below.

  This type of cap, also called a one-piece cap, differs from the two-piece type in which the packing for sealing the container mouth is a separate component, and the container mouth is a seal piece protruding from the inner surface of the top wall. These parts are sealed together with the top wall at the time of molding.

  However, depending on molding conditions and the like, molding failure may occur in the inner annular seal piece and the outer annular seal piece. In other words, when the resin flows in the mold at the time of molding and solidifies before the resins are completely bonded, vertical streaks such as cracks remain at the location. If this phenomenon, also referred to as a weld phenomenon or a weld line, occurs in the outer annular seal piece, the degree of close contact with the outside of the container mouth deteriorates at the location where the phenomenon occurs, causing a seal failure. The outer annular seal piece has a shorter protruding length than the inner annular seal piece, and the degree of close contact with the container mouth tends to be weak. Therefore, when a weld phenomenon occurs in the outer annular seal piece, a seal failure is likely to occur in the state of being attached to the container mouth.

Japanese Patent Laid-Open No. 10-35699 JP 2002-173157 A JP 2009-29498 A

  Therefore, the present invention has been made in view of the above-mentioned conventional problems, and in an integrally molded plastic cap in which an outer annular seal piece that seals the container mouth portion from the outside protrudes from the inner surface of the top wall, the seal failure in the outer annular seal piece It is an object to prevent the occurrence of the above.

The present invention has been made to solve the above problems, and an integrally molded plastic cap according to the present invention includes a top wall and a cylindrical peripheral wall depending from a peripheral portion of the top wall, In the integrally molded plastic cap in which an outer annular seal piece that seals the container mouth portion from the outside protrudes on the inner surface , the inner circumferential surface of the outer annular seal piece has an upper main region and a trough extending in the circumferential direction. is constituted by Jo demarcation line from said main area and compartmentalized lower subregion, as in the sub-region with an outer annular seal piece into close contact with the container opening in the main region separated from the container mouth part The main region is composed of an upper end portion, an intermediate portion, and a lower end portion, and the intermediate portion is a sealing surface for sealing the container mouth and occupies most of the main region, and the intermediate portion Is radially outward toward the bottom Or an inclined shape, or, characterized in that it is a shape extending substantially vertically downwardly.

  Here, “partitioned by valley-shaped lane markings” means that the boundary between the main region and the sub-region is not a top but a valley, This means that the sub-regions are not smoothly continuous up and down, but the two regions are divided up and down by a circumferential partition line. In addition, “sealing the container mouth from the outside” means that the container mouth portion is sealed in close contact with the outer peripheral surface of the container mouth portion and the boundary curved surface between the outer peripheral surface and the upper end surface of the container mouth portion. In addition to the case, the case where both the outer peripheral surface of the container mouth portion and the boundary curved surface are in close contact and sealed is also included.

  In the integrally molded plastic cap having the above structure, a sub-region is formed on the inner peripheral surface of the outer annular seal piece, and the main region is in close contact with the container mouth portion when mounted on the container mouth portion. The sub-region located on the lower side is separated from the container mouth without being in close contact. The weld phenomenon is likely to occur at the tip, but the sub region is partitioned from the main region above it by a valley-shaped partition line, so that the weld phenomenon occurs in the sub region of the outer annular seal piece. However, the weld phenomenon is surely blocked by the valley-shaped dividing line, and does not reach the upper main region.

  In particular, it is preferable that the lower end portion of the main region is formed in a curved surface that is radially inwardly convex in a longitudinal sectional view so that a step is formed between the main region and the sub region. By forming a step between the sub-region and the sub-region, the weld phenomenon is more reliably blocked at the partition line and the progress to the main region is prevented.

  Furthermore, it is preferable that the upper portion of the sub region extends substantially vertically downward from the partition line, and the lower portion of the sub region is curved outward in the radial direction. The upper part of the sub-region may be inclined outward in the radial direction from the lane line downward, but if the upper part extends substantially vertically downward from the lane line, the upper part of the subregion is inclined radially outward. As a result, the effect of the step between the sub-region and the main region bordered by the partition line is further exerted to prevent the weld phenomenon from proceeding upward. In addition, while the upper portion of the sub-region extends substantially vertically downward, the lower portion of the sub-region is curved outward in the radial direction, so that the sub-region does not hinder attachment when attaching to the container mouth. Easy to install.

Furthermore, bending the outer annular seal piece radially outer lower end portion of the main region to the boundary curved surface in contact between the upper surface and the outer peripheral surface of the container mouth part when mounted on the container mouth, the container It is preferable that the middle part of the main region is in close contact with the boundary curved surface of the container mouth in the state of being attached to the mouth. Since the outer annular seal piece bends radially outward, the elastic restoring force can sufficiently secure the adhesion with the container mouth. In addition, since a step is formed between the lower end portion of the main region and the sub region, a large amount of deflection can be easily ensured. Further, since the lower end portion of the main region is a curved surface, the outer annular seal piece can be smoothly bent radially outward. And since the middle part of the main region is in close contact with the boundary curved surface of the container mouth part, it is more effective to use the deflection outward in the radial direction than when sealing the outer peripheral surface of the container mouth part. A more secure seal can be obtained.

Incidentally, the intermediate portion of the main area you are inclined radially outwardly toward the lower side, it is possible to and largely deformed smoothly outer annular seal piece radially outwardly during attachment to the container opening.

  Moreover, it is preferable that the thickness in the sub area | region of an outer annular seal piece is thinner than the thickness in the main area | region of an outer annular seal piece. By providing a difference between the thickness of the main region and the thickness of the sub region, the progress of the weld phenomenon to the main region can be more reliably blocked.

  Furthermore, it is preferable that the thickness of the outer annular seal piece changes suddenly with the dividing line as a boundary, and the progress of the weld phenomenon to the main region can be more reliably blocked by the sudden change in thickness.

  As described above, by providing the sub-region divided by the main region and the valley-shaped dividing line on the outer annular seal piece, even if a weld phenomenon occurs, it can be retained in the sub-region, Seal failure can be prevented.

Sectional drawing which shows the integrally molded plastic cap in one Embodiment of this invention. The principal part enlarged view of FIG. It is a principal part expanded sectional view which shows the use condition of the cap, (a) shows the state in the middle of mounting | wearing to a container mouth part, (b) shows a mounting state (mounting completion state). The principal part expanded sectional view which shows the integral molding type plastic cap in other embodiment of this invention. The principal part expanded sectional view which shows the integral molding type plastic cap in other embodiment of this invention.

  Hereinafter, an integrally molded plastic cap according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. The cap in this embodiment is screwed to the container mouth 50 (see FIG. 2) for sealing, and includes a top wall 1 and a cylindrical peripheral wall 2 depending from the peripheral edge of the top wall 1. It has. The cap is formed by injection molding or compression molding, and is made of a synthetic resin having excellent flexibility and low frictional resistance with the container, such as high density polyethylene (HDPE) or polypropylene (PP).

  On the outer peripheral surface of the peripheral wall 2, a vertical knurl 3 is formed over the entire periphery, and on the inner peripheral surface of the peripheral wall 2, a female screw portion 4 is formed which is screwed with the male screw portion 51 of the outer peripheral surface of the container mouth portion 50. Has been. An annular band 6 (tamper evidence band) is connected to the lower end of the peripheral wall 2 via a plurality of bridges 5, and the cap is configured as a pilfer proof cap. The bridges 5 are formed at regular intervals in the circumferential direction. For example, the bridges 5 are formed as follows. That is, a plurality of connecting piece portions 7 are formed at regular intervals in the circumferential direction from the inner peripheral surface of the peripheral wall 2 to the inner peripheral surface of the band 6, and the connecting piece portions 7 are formed on the outer peripheral surface of the portion corresponding to the connecting piece portion 7. A slit 8 is formed by a cutter or the like so as to leave a part of the connection piece 7, and a part of the remaining connecting piece 7 is configured as a bridge 5.

  A flap 9 is formed on the inner peripheral surface of the band 6 so as to be engaged with a bulging portion (not shown) of the container mouth portion 50 so that the band 6 remains in the container mouth portion 50 when the cap is opened. The flap 9 is folded inward from the lower part of the band 6 and extends obliquely upward. The flap 9 may be annular, but in the present embodiment, a plurality of pieces are formed at predetermined intervals in the circumferential direction. The flap 9 can be elastically deformed so as to rotate radially outward (that is, in a direction approaching the inner peripheral surface of the band 6) with the base end portion (lower end portion) as a fulcrum by its retained elasticity. Therefore, the flap 9 is elastically deformed radially outward when the cap is attached to the container mouth portion 50, gets over the bulging portion (bead portion) of the container mouth portion 50, and passes through the bulging portion downward. It automatically rotates inward in the radial direction by its own elastic restoring force and is located below the bulging portion.

  On the other hand, on the inner surface of the top wall 1, as shown in FIG. 2, an inner annular seal piece 11, an annular projection 12, and an outer annular seal piece 13 are formed integrally with the top wall 1 by molding in order from the radially inner side. ing. The inner annular seal piece 11 is fitted inside the container mouth part 50 and tightly seals with the inner peripheral surface 52 of the container mouth part 50. In FIG. 2, the container mouth portion 50 is indicated by a two-dot chain line, and the inner annular seal piece 11 and the like show a state before being attached to the container mouth portion 50. The inner annular seal piece 11 has a shape that expands outward in the radial direction toward the lower side as a whole. Therefore, in a state where the inner annular seal piece 11 is fitted into the container mouth portion 50, the inner annular seal piece 11 bends inward in the radial direction. The container mouth part 50 is in close contact with the inner peripheral surface 52. The annular protrusion 12 is located between the outer annular seal piece 13 and the inner annular seal piece 11, and is in close contact with the upper end surface 53 of the container mouth portion 50 to seal. The annular protrusion 12 has a small protrusion amount, and is, for example, a semicircular shape in a longitudinal sectional view.

  The outer annular seal piece 13 seals the container opening 50 from the outside, and is formed to have a protruding length of about 1/3 to 1/2 of the inner annular seal piece 11. Specifically, the inner peripheral surface of the outer annular seal piece 13 is composed of an upper main region 20 and a lower subregion 30, and both regions 20, 30 are formed over the entire circumference in the circumferential direction. It is divided up and down by a valley-like division line 15. The main region 20 as a whole has a shape that is radially outward toward the lower side, and is composed of an upper end portion 21 located at the proximal end, an intermediate portion 22 located in the middle, and a lower end portion 23 located at the distal end. Yes. The upper end portion 21 of the main region 20 is a curved surface (concave curved surface) that is radially outwardly convex in a longitudinal sectional view, and smoothly connects the inner surface of the top wall 1 and the intermediate portion 22. The intermediate portion 22 of the main region 20 is a portion where a seal point for sealing the container mouth portion 50 is formed, that is, a seal surface, and occupies most of the main region 20. The intermediate portion 22 of the main region 20 is gradually inclined radially outward toward the lower side. The lower end portion 23 of the main region 20 is formed in a radially inwardly convex curved surface (convex curved surface) in a longitudinal sectional view so that a step is formed between the main region 20 and the sub region 30. That is, the lower end portion 23 of the main region 20 is curved outward in the radial direction from the intermediate portion 22 to the partition line 15. The inner circumferential surface of the outer annular seal piece 13 is bent at the dividing line 15, and a lower sub-region 30 is extended downward from the dividing line 15. The sub-region 30 extends substantially vertically downward from the partition line 15 at the upper portion 31 and is curved outward in the radial direction at the lower portion 32. As shown in FIG. 3A, the inner diameter of the sub-region 30 is substantially equal to or slightly larger than the outer diameter of the outer peripheral surface 54 of the container mouth portion 50.

  On the other hand, the outer peripheral surface of the outer annular seal piece 13 is composed of an upper end portion 41 (base end portion), an intermediate portion 42, and a lower end portion 43 (tip end portion), and the upper end portion 41 protrudes radially inward in a longitudinal sectional view. The inner surface of the top wall 1 and the intermediate portion 42 are smoothly connected. The intermediate portion 42 of the outer peripheral surface of the outer annular seal piece 13 is a portion that occupies most of the outer peripheral surface, and is gradually inclined radially inward toward the lower side. It is formed to a position facing or a position close to it. The lower end 43 of the outer peripheral surface of the outer annular seal piece 13 extends substantially vertically downward.

  By forming the inner peripheral surface and the outer peripheral surface of the outer annular seal piece 13 in this way, the outer annular seal piece 13 has a thickness in the subregion 30 of the inner peripheral surface that is greater than the thickness in the main region 20 of the inner peripheral surface. The thickness is abruptly changed up and down with the dividing line 15 as a boundary. In particular, since a step is formed on the upper side of the lane marking 15, the thickness rapidly increases at that portion as compared to the lower side of the lane marking 15. Moreover, the intermediate portion 22 of the main region 20 on the inner peripheral surface of the outer annular seal piece 13 is inclined radially outward toward the lower side, and the intermediate portion 22 of the outer peripheral surface is radially inward toward the lower side. Since it is inclined, the thickness gradually decreases toward the dividing line 15 toward the lower side. Note that the thickness in the sub-region 30 below the dividing line 15 is about half as thin as the thickness in the main region 20 above the dividing line 15 and is easily elastically deformed. Since the outer annular seal piece 13 is annular, it expands and contracts in the radial direction. Therefore, the portion below the partition line 15 constitutes an easily deformable annular projecting piece 16 that is easier to expand and contract than the upper portion. doing.

  The cap configured as described above is attached by being wound around the container mouth portion 50 with a predetermined torque. In the mounting process to the container mouth portion 50, first, the inner annular seal piece 11 is fitted into the container mouth portion 50 while being bent radially inward, and then the outer annular seal piece 13 comes into contact with the container mouth portion 50. As shown in FIG. 3, an arcuate boundary curved surface 55 is formed in the container mouth portion 50 between a substantially horizontal and substantially flat upper end surface 53 and a substantially vertical outer peripheral surface 54. The lower end portions 23 of the 13 main regions 20 abut on the boundary curved surface 55 of the container mouth portion 50. At this time, the inner diameter of the outer annular seal piece 13 in the sub-region 30 is substantially equal to or slightly larger than the outer diameter of the outer peripheral surface 54 of the container mouth portion 50, so that the container mouth portion 50 is shown in FIG. In the middle of mounting, the sub-region 30 of the outer annular seal piece 13 does not contact or slightly contacts the container mouth 50. Further, coupled with the fact that the lower portion 32 of the sub-region 30 of the outer annular seal piece 13 is curved outward in the radial direction, the outer annular seal piece 13 is mounted on the container mouth 50 after the inner annular seal piece 11. The wearing resistance does not become too large when going and can be smoothly attached to the container.

  Thus, after the lower end portion 23 of the main region 20 of the outer annular seal piece 13 abuts on the boundary curved surface 55 of the container mouth portion 50, the outer annular seal piece 13 gradually moves in the radial direction by relative movement to the lower side of the cap. Bends outward. That is, the outer annular seal piece 13 gradually expands radially outward. At this time, since the lower end portion 23 of the main region 20 is a curved surface, the outer annular seal piece 13 is smoothly bent radially outward as the cap moves relative to the lower side. Further, since the lower end portion 23 of the main region 20 contacts the boundary curved surface 55 of the container mouth portion 50, the outer annular seal piece 13 is greatly bent outward as compared with the case where the intermediate portion 22 of the main region 20 contacts. Can do. And since the level | step difference is formed between the subregion 30 by the lower end part 23 of the main area | region 20, the big deflection amount can be ensured easily. When the container mouth portion 50 is completely attached as shown in FIG. 3B, the intermediate portion 22 of the main region 20 of the outer annular seal piece 13 is brought into close contact with the boundary curved surface 55 so that the container mouth portion 50 is moved from the outside. Seal. Since the outer annular seal piece 13 is bent outward in the radial direction, its elastic restoring force ensures sufficient adhesion with the container mouth portion 50. In addition, the outer annular seal piece 13 is bent and inclined outward in the radial direction. However, since the outer annular seal piece 13 is in close contact with the boundary curved surface 55 instead of the outer peripheral surface 54 of the container mouth portion 50, elastic recovery is achieved by bending outward in the radial direction. The force acts on the container opening 50 efficiently, and a more reliable seal is obtained. In FIG. 3B, the point S is the main seal point. Actually, however, the portion of the outer annular seal piece 13 positioned below the point S is also about to reduce its diameter due to its elastic restoring force. The intermediate portion 22 below the point S may be slightly reduced in diameter radially inward from the position indicated by the solid line in FIG. 3B and may contact the outer peripheral surface 54 of the container mouth portion 50. Further, since the easily deformable annular projecting piece 16 at the lower end (tip) of the outer annular seal piece 13 is thin, it is relatively larger than the upper portion in the radial direction as shown by a two-dot chain line in FIG. Restore to. Due to the diameter-reducing action of the easily deformable annular projecting piece 16 toward the inside in the radial direction, the upper part thereof is affected and attempts to reduce the diameter toward the inside in the radial direction. Therefore, the sealing force to the container mouth 50 is also enhanced by the diameter reducing action of the easily deformable annular projecting piece 16. Further, since the easily deformable annular projecting piece 16 can be reduced in diameter relatively large, a sufficient sealing force can be ensured without making the entire outer annular seal piece 13 thick, and it is easily deformed at the time of attachment, and therefore, it can be attached to the container. Sometimes it can be securely tightened to a predetermined position.

  As described above, the cap 50 is attached to the container mouth portion 50. In the cap of the present embodiment, the inner peripheral surface of the outer annular seal piece 13 is partitioned from the main region 20 by the valley-shaped partition line 15. Since the subregion 30 is provided, even if a weld phenomenon occurs in the outer annular seal piece 13 during molding, it can be retained in the subregion 30. That is, the weld phenomenon is surely blocked by the valley-shaped dividing line 15 and does not proceed to the upper main region 20. Since the sub-region 30 is a portion that is separated from the container mouth portion 50 without being in close contact with the container mouth portion 50, the sealing performance is not affected, and a sealing failure in the main region 20 can be prevented.

  In particular, since the lower end portion 23 of the main region 20 is formed in a curved surface that is radially inwardly convex in a longitudinal sectional view and a step is formed between the lower region 23 and the sub-region 30, the progress of the weld phenomenon on the partition line 15 is ensured Can be blocked. Further, since the upper portion 31 of the sub-region 30 extends substantially vertically downward from the lane marking 15, the effect of the step between the sub-region 30 and the main region 20 with the lane marking 15 as a boundary is further exhibited. In addition, the thickness of the outer annular seal piece 13 in the sub-region 30 is thinner than that in the main region 20, and in particular, since it changes suddenly at the dividing line 15, the progress of the weld phenomenon to the main region 20 is further increased. It can be blocked more reliably. At the same time, the tip portion is used as the easily deformable annular projecting piece 16 to improve the sealing performance, and it can be securely wound to a predetermined position when mounted on the container.

  In the present embodiment, in the outer annular seal piece 13, the lower end portion 23 of the main region 20 is formed in a curved surface that is radially inwardly convex in a longitudinal sectional view so as to form a step between the subregion 30. However, for example, the lower end portion 23 of the main region 20 may be an inclined surface, and in that case, an inclined surface continuously integrated with the intermediate portion 22 as shown in FIG.

  Further, as shown in FIG. 5, the intermediate portion 22 of the main region 20 may be formed to extend substantially vertically downward without being inclined. In this case, the outer annular seal piece 13 does not bend greatly in the radial direction even when it comes into contact with the container mouth portion 50, or does not substantially bend, and is in close contact with only the outer peripheral surface 54 of the container mouth portion 50. It is good. Thus, various design changes are possible for the shape of the inner peripheral surface of the outer annular seal piece 13.

  Also, various changes can be made to the outer peripheral surface of the outer annular seal piece 13. For example, as shown in FIG. 5, the intermediate portion 42 and the lower end portion 43 may be integrated into a shape extending substantially vertically downward.

DESCRIPTION OF SYMBOLS 1 Top wall 2 Perimeter wall 3 Knurl 4 Female thread part 5 Bridge 6 Band 7 Connection piece part 8 Slit 9 Flap 11 Inner annular seal piece 12 Annular protrusion 13 Outer annular seal piece 15 Dividing line 16 Easily deformable annular protrusion 20 Main area 21 Upper end part 22 Intermediate part 23 Lower end part 30 Subregion 31 Upper part 32 Lower part 41 Upper end part 42 Intermediate part 43 Lower end part 50 Container port part 51 Male thread part 52 Inner peripheral surface 53 Upper end surface 54 Outer peripheral surface 55 Boundary curved surface S Seal point

Claims (6)

An integrally molded plastic cap provided with a top wall and a cylindrical peripheral wall depending from the peripheral edge of the top wall, and an outer annular seal piece for sealing the container mouth from the outside projecting on the inner surface of the top wall In
The inner peripheral surface of the outer annular seal piece, an upper main region, the trough of the partition lines extending in the circumferential direction is composed of said main area and compartmentalized lower subregion, the outer annular seal piece main It is configured to be in close contact with the container mouth in the region and to be separated from the container mouth in the sub region ,
The main region is composed of an upper end portion, an intermediate portion, and a lower end portion, and the intermediate portion is a sealing surface for sealing the container mouth and occupies most of the main region, and the intermediate portion is An integrally molded plastic cap characterized by having a shape inclined radially outward toward the side or a shape extending substantially vertically downward .   2. The integrally molded plastic cap according to claim 1, wherein the lower end portion of the main region is formed in a curved surface that is radially inwardly convex in a longitudinal sectional view so that a step is formed between the subregion and the subregion. The integrally molded plastic cap according to claim 1 or 2, wherein an upper portion of the sub-region extends substantially vertically downward from the partition line, and a lower portion of the sub-region is curved radially outward. When the container mouth portion is mounted, the lower end portion of the main region comes into contact with the boundary curved surface between the upper end surface and the outer peripheral surface of the container mouth portion, and the outer annular seal piece bends radially outwardly. The integrally molded plastic cap according to any one of claims 1 to 3, wherein an intermediate portion of the main region is in close contact with a boundary curved surface of the container mouth portion in the mounted state. The integrally molded plastic cap according to any one of claims 1 to 4, wherein a thickness in the sub region of the outer annular seal piece is thinner than a thickness in a main region of the outer annular seal piece. 6. The integrally molded plastic cap according to claim 5 , wherein the thickness of the outer annular seal piece changes abruptly with the dividing line as a boundary.

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