Plastic screw cap with good washability

Abstract

Provided is a plastic threaded cap having a tamper-evident band that ensures improved removal of cleaning water. A plastic threaded cap (1) includes a top panel (3), a skirt wall (5), and a tamper-evident band (TE band) connected to a lower end of the skirt wall (5) via a breakable bridge and including an engagement protrusion (19) on an inner surface thereof that is engageable to a lower surface of a container claw portion (53). The TE band (7) further includes a flow path forming protrusion (30) on the inner surface thereof, which is positioned above the engagement protrusion (19) and abuts an outer surface of the container claw portion (53) to form a flow path between the container claw portion (53) and an inner surface of the skirt wall (5).

Description

Technical Field

[0001] This invention relates to plastic threaded caps. More specifically, this invention relates to plastic threaded caps with good washability. Background Technology

[0002] The plastic threaded cap has a top plate and a skirt extending downward from the periphery of the top plate. The skirt's inner surface includes threads (internal threads) that engage with threads (external threads) on the outer surface of the container opening. A tamper-evident tape (TE tape) is provided at the lower end of the skirt via a breakable bridging member. The TE tape includes engaging protrusions on its inner surface that engage with the lower surface of the container's claws. When the cap is rotated in the opening direction, the skirt of the cap is allowed to rise along the outer surface of the container opening, while the upward movement of the TE tape is restricted by the engaging protrusions engaging with the lower surface of the container's claws. Next, as the cap continues to rotate in the opening direction, the bridging member connecting the skirt of the cap and the TE tape disengages. Therefore, the TE tape separates from the cap as it is removed from the container opening. In other words, if the TE tape separates from the cap, it indicates that the cap has been opened and removed from the container opening. Therefore, the TE tape serves as an anti-tamper function and ensures the quality of the container contents.

[0003] At the same time, threaded caps with the aforementioned TE tape have issues with their washability, which needs to be improved.

[0004] More specifically, before the threaded cap is installed onto the container, it is cleaned with water and then dried by blowing air to remove the cleaning water inside the cap. The problem is that residual cleaning water accumulates on the upper surface of the container's gripper. This accumulated cleaning water slowly seeps out through the tiny gaps between the cap's skirt and the TE tape to the outer surface of the TE tape. As a result, marks and other imperfections on the outer surface of the TE tape become blurred. This problem of cleaning water removal is particularly pronounced when containers are filled and capped on high-speed production lines. This is likely because the caps are often not completely dry after cleaning before being installed onto the container.

[0005] Typically, water accumulated on the upper surface of the claws of a container sealed with a lid is removed by blowing air through a tiny gap between the skirt of the lid and the TE strip. However, the engagement protrusions formed on the lower surface of the TE strip, which is to engage with the container claws, impede the flow of cleaning water accumulated on the upper surface of the container claws, making it difficult to remove water by blowing air. In particular, water removal becomes more difficult with recently proposed lids that take measures to prevent the TE strip from slipping when opened and removed from the container opening. For example, Patent Document 1 proposes a threaded lid including an annular inclined surface with an inverted frustum shape, formed on the upper side of the engagement protrusions on the inner surface of the TE strip. When the lid is opened, the annular inclined surface comes into close contact with the outer peripheral surface of the container claws, thereby preventing the TE strip from slipping. Using this structure, cleaning water accumulated on the upper surface of the container claws becomes even more difficult to drain.

[0006] To allow rinsing water accumulating on the upper surface of the container claws to flow easily downwards, Patent Document 2 proposes a cap in which the TE tape has multiple axially extending grooves on its inner surface, located above engagement protrusions that engage with the lower surface of the container claws. However, because these grooves are formed on the inner surface of the TE tape, their depth is limited, resulting in insufficient removal of rinsing water. Consequently, in cases such as high-speed filling, the imprint may sometimes become blurred by the rinsing water.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: JP-B2-6393497

[0010] Patent Document 2: JP-B2-6373099 Summary of the Invention

[0011] The problem the invention aims to solve

[0012] Therefore, the object of the present invention is to provide a plastic threaded cap with a tamper-evident strip that has improved washability, thereby leaving less cleaning water residue.

[0013] Problem-solving methods

[0014] This invention provides a plastic threaded cap, comprising: a top plate; a skirt extending downward from the periphery of the top plate and having threads on its inner surface for threaded connection to an outer surface of a container opening; and a tamper-evident strip connected to a lower end of the skirt via a breakable bridging member, and having engaging protrusions on its inner surface capable of engaging with a lower surface of a container claw. The tamper-evident strip further includes flow-path forming protrusions on its inner surface, the flow-path forming protrusions being located above the engaging protrusions and abutting against the outer surface of the container claw to form a flow path between the container claw and the inner surface of the skirt.

[0015] The plastic threaded cap of this invention is applicable to:

[0016] (1) An annular inclined surface or a circumferentially discontinuous arc-shaped inclined surface is formed in a region continuous with the upper surface of the engaging protrusion, such that the inclined surface gradually thickens from the top toward the upper end contact of the engaging protrusion, and the flow path forming protrusion is disposed above the annular inclined surface or the arc-shaped inclined surface.

[0017] (2) A plurality of said engaging protrusions are formed at uniform intervals along the circumference, and between a pair of adjacent engaging protrusions, the flow path forming protrusion is positioned above the engaging protrusions.

[0018] (3) The flow path forming protrusion is axially extended rib or block shape.

[0019] Technical effects of the present invention

[0020] The novel feature of the cap of the present invention is that the TE band has a flow path forming protrusion on its inner surface, which is located above the engagement protrusion on the lower surface of the container claw. When the cap is installed at the container opening, the flow path forming protrusion abuts against the outer surface of the container claw, thereby allowing a space to be formed around the flow path forming protrusion between the TE band and the container claw. Furthermore, in this state, the engagement protrusion remains away from the lower surface of the container claw; however, when the cap is opened, the engagement protrusion restricts the upward movement of the cap by engaging with the lower surface of the container claw. In other words, the space formed by the flow path forming protrusion between the TE band and the container claw is not closed by the engagement protrusion but communicates with the external space. This allows the space formed around the flow path forming protrusion to be used as a flow path for discharging cleaning fluid. Therefore, cleaning fluid accumulated on the upper surface of the container claw can be discharged to the outside through the space between the flow path forming protrusion and the container claw by air blown through the gap formed between the TE band and the skirt.

[0021] In this way, the cap of the present invention exhibits excellent washability (except water), thereby effectively preventing the imprints on the outer surface of the TE tape from becoming blurred by, for example, the cleaning fluid accumulated in the cap.

[0022] As in Patent Document 2, if the TE tape has axially extending grooves intended to serve as flow paths, such grooves need to be wide and deep, which significantly reduces the strength of the TE tape. Consequently, the TE tape becomes easily deformable, making it difficult for the engaging protrusions to pass over the container claws when the cap is opened. To avoid this, the width and depth of the grooves are thus limited, preventing them from being fully utilized as flow paths for draining the cleaning fluid. However, the cap of the present invention uses protrusions instead of grooves to form flow paths, thereby ensuring water removal without causing the aforementioned inconveniences, even when processed by a high-speed filling and capping machine. Attached Figure Description

[0023] Figure 1 This is a partial vertical sectional view showing the plastic cap and container opening of the present invention;

[0024] Figure 2 It shows Figure 1 A view of section AA in the image;

[0025] Figure 3 This is a view used to illustrate the function of the protrusion for forming the flow path in this invention;

[0026] Figure 4 This is a partial exploded view of the TE strip in the plastic cap of the present invention;

[0027] Figure 5 This is a view illustrating an example of another embodiment of the protrusion for flow path formation in this invention.

[0028] Figure label:

[0029] 1: Cover; 3: Top plate; 5: Skirt; 7: TE strip; 9: Slit; 13: Inner ring; 19: Engaging protrusion; 30: Flow path forming protrusion; 50: Container opening; 53: Claw; X: Space; Y: Cleaning water droplets Detailed Implementation

[0030] refer to Figure 1 The plastic threaded cap (hereinafter simply referred to as the cap) of the present invention is generally indicated by reference numeral 1 in the accompanying drawings. The cap 1 is threadedly connected to and attached to the container opening 50. A thread (external thread) 51 is formed on the outer surface of the container opening 50. A claw (rib) 53 with a diameter larger than the thread 51 is formed below the thread 51. For purposes such as portability and positioning, a support ring 55 with a larger diameter is formed on the underside of the claw 53.

[0031] The cover 1 has a top plate 3 and a skirt 5 extending downward from the periphery of the top plate 3. The lower end of the skirt 5 is connected to a TE strip (tamper-evident strip) 7 via a plurality of breakable bridging elements (not shown). A slit 9 with a small gap is formed between the lower end of the skirt 5 and the upper end of the TE strip 7.

[0032] The skirt 5 includes a thread (internal thread) 11 on its inner surface, which will be threadedly connected to the thread 51 provided at the container opening 50.

[0033] An inner ring 13 extending downward away from the skirt wall 5 is provided on the inner surface of the top plate 3. Short, outwardly inclined auxiliary protrusions 15 are formed circumferentially on the outer side of the inner ring 13. Small, flat protrusions 17 are formed circumferentially between the inner ring 13 and the auxiliary protrusions 15.

[0034] Hook-shaped engaging protrusions 19 are formed on the inner surface of the TE band 7.

[0035] With this structure, when the cap 1, placed on the container opening 50, rotates in the closing direction, the cap is allowed to descend as the threads 11 of the cap 1 are threaded together with the threads 51 of the container opening 50. Therefore, the upper end of the container opening 50 is inserted into the space between the inner ring 13 and the auxiliary protrusion 15 formed on the inner surface of the top plate 3, until the upper end face of the container opening 50 abuts against the flat surface of the small flat protrusion 17, thereby sealing the container opening 50. At this time, the engaging protrusion 19 of the TE band 7 passes over the claw portion 53 and is located below the claw portion 53.

[0036] An inclined surface 21 is formed on the upper side of the engaging protrusion 19 on the inner surface of the TE belt 7, such that the inclined surface 21 gradually thickens from top to bottom toward the upper end contact of the engaging protrusion 19. The inclined surface 21 is described in detail, for example, in Patent Document 1.

[0037] When the cover 1, in the closed state, rotates in the opening direction, the skirt 5 is allowed to rise as the threads 11 and 51 disengage. However, the upward movement of the TE band 7 is restricted by the rising engaging protrusion 19 engaging with the lower surface of the claw 53. As a result, stress concentrates on the breakable bridging element (not shown) connecting the skirt 5 and the TE band 7, allowing the bridging element to break. Therefore, the TE band 7 separates from the skirt 5. At this point, if the TE band 7 rises rapidly in response to rotation in the opening direction, the engaging protrusion 19 may pass over the claw 53, causing the TE band 7, still connected to the skirt 5, to slip off the container opening 50. To avoid this, an inclined surface 21 is formed to allow the TE band 7 to rise gradually until the engaging protrusion 19 engages with the claw 53. Therefore, slippage of the TE band 7 is effectively prevented.

[0038] Therefore, if the TE band 7 separates from the cap 1 removed from the container opening 50, it clearly indicates that the cap has been opened.

[0039] like Figure 1 As shown, according to the cover 1 having the TE tape 7 of the present invention, the TE tape 7 has a flow path forming protrusion 30 on its inner surface, located above the engaging protrusion 19. The flow path forming protrusion 30 is configured such that it is positioned to face and abut against the claw portion 53.

[0040] like Figure 2 As shown (shown) Figure 1 (AA section in the middle), a space X is formed by protrusion 30 around the flow path between the inner surface of TE band 7 and the outer surface of claw 53.

[0041] refer to Figure 3 This will explain the function of the protrusion 30 in forming the flow path. In, for example... Figure 3 In the conventional cap shown in (a) without the flow path forming protrusion 30, the inner surface of the TE strip 7 is in contact with the outer surface of the claw portion 53. Using this structure, even if air is blown through the slit 9 to a droplet Y of cleaning water that may accumulate on the upper surface of the claw portion 53, the droplet Y will flow out through the slit 9 because there is no flow path for the droplet Y below the claw portion 53. As a result, the droplet Y flows through the slit 9, adheres to the outer surface of the TE strip 7, and causes the inkjet prints or the like to become blurred on the outer surface of the TE strip 7.

[0042] On the other hand, in this invention, the flow path forming protrusion 30 provided on the inner surface of the TE belt 7 allows a space X to be formed around the flow path forming protrusion 30 between the inner surface of the TE belt 7 and the outer surface of the claw portion 53. Furthermore, a gap is formed between the engaging protrusion 19 and the lower surface of the claw portion 53. Therefore, a flow path leading to the lower side of the claw portion 53 exists between the inner surface of the claw portion 53 and the skirt wall 5. With this structure, as... Figure 3 As shown in (b), when air is blown through the slit 9 to the droplets Y of cleaning water that may accumulate on the upper surface of the claw 53, the droplets Y flow through the flow path to the lower side of the claw 53 and are discharged without adhering to the outer surface of the TE belt 7.

[0043] As described above, the cover 1 of the present invention can effectively remove cleaning water, thereby effectively preventing the imprint from becoming blurred, for example, due to water remaining in the cover 1.

[0044] To maximize the water removal effect of the flow path forming protrusion 30 in this invention, it is preferable that a plurality of engaging protrusions 19 are formed circumferentially spaced according to the size of the cover 1, and that the flow path forming protrusion 30 is formed at a position higher than the engaging protrusions 19 between pairs of adjacent engaging protrusions 19, as shown in a partial exploded view of the TE band 7. Figure 4As shown. For example, with a lid having a nominal diameter of 28 mm, it is desirable to form approximately three to nine engaging protrusions 19 at a total interval of approximately 1% to 50% of the circumference of the TE band 7. This allows sufficient space X to be formed around the flow path forming protrusion 30, thereby effectively removing cleaning water by blowing air. As long as the flow path forming protrusion 30 is located above the engaging protrusion 19, the flow path forming protrusion 30 can axially overlap with the circumferential ends of the engaging protrusion 19, as shown. Figure 5 As shown.

[0045] Flow path formation using protrusion 30 Figure 4 The example shown is an axially extending rib, or alternatively it can be as follows: Figure 5 The shape shown is block-shaped. In any case, the shape and height of the flow path forming protrusion 30, the positional relationship between the flow path forming protrusion and the engaging protrusion 19, etc., can be set to maximize the water removal effect while taking into account the demolding properties during the molding process. For example, the height of the flow path forming protrusion 30 is suitably about 0.05 to 0.30 mm. Figure 4 In the example shown, between adjacent locking protrusions 19, there is only a single flow path forming protrusion 30 above the locking protrusion 19; however, multiple flow path forming protrusions 30 may also be provided.

[0046] As shown in Patent Document 1, tiny ribs are sometimes formed on the inclined surface above the engaging protrusion 19 on the inner surface of the TE band 7. These ribs are configured to allow the TE band 7, separated from the cover 1, to fall quickly without remaining on the outer surface of the claw portion 53. Since these ribs are not used to form a flow path for removing cleaning water, they are very low in height and formed at a position lower than the flow path forming protrusion 30 in this invention; therefore, they have almost no water removal function.

[0047] The cover 1 of the present invention can be easily made from a thermoplastic resin (such as an olefin-based resin (e.g., polypropylene, polyethylene, etc.)) by injection molding or compression molding.

Claims

1. A plastic threaded cap, comprising: roof; A skirt wall that extends downward from the periphery of the top plate and includes threads on its inner surface that will be threaded to the outer surface of the container opening; and A thief-tampering strip, which is connected to the lower end of the skirt wall via a breakable bridging member, and includes engaging protrusions on its inner surface capable of engaging with the lower surface of the container claw; wherein The thief-proof strip also includes a flow path forming protrusion on its inner surface, the flow path forming protrusion being located above the engaging protrusion and abutting against the outer surface of the container claw to form a flow path between the container claw and the inner surface of the skirt wall; The flow path forming protrusion and the engaging protrusion are separated from each other in the vertical direction, and when installed at the container opening, a gap is formed between the upper surface of the engaging protrusion and the lower surface of the container claw.

2. The plastic threaded cap according to claim 1, wherein an annular inclined surface or a circumferentially discontinuous arc-shaped inclined surface is formed in a region continuous with the upper surface of the engaging protrusion, such that the inclined surface gradually thickens from the top toward the upper end contact of the engaging protrusion, and The flow path forming protrusion is disposed above the annular inclined surface or the arc-shaped inclined surface.

3. The plastic threaded cap according to claim 1, wherein a plurality of said engaging protrusions are formed at uniform intervals along the circumferential direction, and Between two adjacent engaging protrusions, above the engaging protrusions, is the flow path forming protrusion.

4. The plastic threaded cap according to claim 1, wherein the flow path forming protrusion is axially extending rib or block shape.

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