Plastic screw cap that is easy to clean

Abstract

To provide a plastic screw cap comprising a tamper-evident band enhanced in the drain ability of cleaning water.SOLUTION: A plastic screw cap 1 comprises a top plate 3, a skirt wall 5, and a TE band (tamper-evident band) coupled to a lower end of the skirt wall 5 by a breakable bridge and having, on an inner surface, an engagement projection 19 capable of being engaged with a lower side of a container jaw 53. On the inner surface of the TE band 7, a flow-passage-forming projection 30 is provided in a position upper than the engagement projection 19 so that it contacts an outer face of the container jaw 53 and assures a space X serving as a flow-passage of cleaning liquid between the container jaw 53 and an inner surface of the skirt wall 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to plastic screw caps, and more particularly to plastic screw caps with improved cleanability. [Background technology]

[0002] The plastic screw cap has a top plate and a skirt wall that descends from the periphery of the top plate. The outer surface of the skirt wall has threads (female threads) that engage with threads (male threads) on the outer surface of the container mouth. A tamper-evident band (TE band) is attached to the lower end of the skirt wall via a breakable bridge. The inner surface of the TE band has a locking protrusion that can engage with the underside of the container jaw. When the cap is turned in the opening direction, the skirt wall of the cap rises along the outer surface of the container mouth, but the TE band's rise is limited because the locking protrusion engages with the underside of the container jaw. As a result, when the cap is turned in the opening direction, the bridge connecting the skirt wall of the cap and the TE band breaks, and the TE band is separated from the cap when it is removed from the container mouth. In other words, the fact that the TE band is separated from the cap proves that the cap has been removed from the mouth of the container, thereby preventing tampering and guaranteeing the quality of the container contents.

[0003] However, the screw caps equipped with the above-mentioned TE bands have problems with cleaning, and improvements in this area are being sought. That is, screw caps are washed with water or the like, and the cleaning water inside the cap is removed by air blowing before being attached to a container. However, there is a problem in that the cleaning water remaining inside the cap accumulates on the upper part of the container's jaw. The cleaning water that accumulates on the upper part of the container's jaw gradually flows out onto the outer surface of the TE band, resulting in the inconvenience of bleeding the printing on the outer surface of the TE band. This problem of draining the cleaning water tends to be more pronounced when the contents are filled into containers and capped on a high-speed line. This is probably because the caps are often attached to containers without being sufficiently dried after washing.

[0004] Typically, water that accumulates on the jaw of a capped container is removed by blowing air through the tiny gap between the skirt wall of the cap attached to the container and the TE band. However, because the TE band has an engaging protrusion below it that engages with the underside of the container jaw, cleaning water that accumulates above the container jaw is difficult to drain, making removal by air blowing difficult. In particular, Patent Document 1 recently proposed a screw cap in which an annular inclined surface in the shape of an inverted truncated cone is formed above the engaging protrusion on the inner surface of the TE band to prevent the TE band from slipping off when the cap is opened and removed from the container mouth. This cap is designed so that the annular outer surface adheres closely to the outer peripheral surface of the container jaw when the cap is opened, preventing the TE band from slipping off. This makes it even more difficult to drain cleaning water that accumulates above the container jaw.

[0005] On the other hand, Patent Document 2 proposes forming multiple axially extending grooves on the inner surface of the TE band above the locking protrusion that engages with the underside of the container jaw to facilitate the flow of cleaning water accumulated on the upper side of the container jaw. However, because such grooves are formed on the inner surface of the TE band, their depth is limited. As a result, the drainage of cleaning water is not sufficient, and cleaning water still sometimes smears on the printed characters, for example, during high-speed filling. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6393497 [Patent Document 2] Patent No. 6373099 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, an object of the present invention is to improve the cleanability of a plastic screw cap equipped with a tamper-evident band and effectively prevent cleaning water from remaining. [Means for solving the problem]

[0008] According to the present invention, there is provided a plastic screw cap having a top plate, a skirt wall descending from the periphery of the top plate and having threads on its inner surface that threadably engage with the outer surface of the mouth of a container, and a tamper-evident band connected to the lower end of the skirt wall by a breakable bridge and having a locking projection on its inner surface that can engage with the underside of the jaw of the container, A flow path forming protrusion is provided on the inner surface of the tamper-evident band at a position above the locking protrusion, the protrusion abutting against the outer surface of the container jaw portion and ensuring a space serving as a flow path for cleaning liquid between the container jaw portion and the inner surface of the skirt wall. And, the flow path forming projection and the locking projection are spaced apart in the vertical direction, When the container is attached to the mouth of the container, a gap is formed between the upper surface of the locking projection and the lower surface of the container jaw. A plastic screw cap is provided, characterized in that

[0009] In the plastic screw cap of the present invention, (1) A portion of the upper surface of the locking projection is formed with an annular inclined surface or a circumferentially discontinuous arc-shaped inclined surface that gradually becomes thicker from above toward the base of the upper end of the locking projection, and the flow path forming projection is disposed above the annular inclined surface or the arc-shaped inclined surface. (2) The locking projections are formed in plurality at regular intervals in the circumferential direction, and the flow path forming projections are disposed above and between adjacent locking projections; (3) The flow path forming projection has a rib shape extending in the axial direction or a block shape; is preferred. [Effects of the Invention]

[0010] The cap of the present invention has a novel feature in that a flow path-forming protrusion is provided on the inner surface of the TE band at a position above the locking protrusion that engages with the container jaw. That is, when the cap is attached to the container mouth, the flow path-forming protrusion abuts against the outer surface of the container jaw, thereby forming a space around the flow path-forming protrusion between the cap and the container jaw. Furthermore, the locking protrusion, which engages with the underside of the container jaw to limit the lift of the cap when opening the cap, is maintained away from the underside of the container jaw in this state. That is, the space formed between the flow path-forming protrusion and the container jaw is not blocked by the locking protrusion but is connected to the external space along the underside of the container jaw. As a result, the space formed around the flow path-forming protrusion functions as a flow path for discharging cleaning liquid. For example, cleaning liquid accumulated on the upper side of the container jaw can be discharged to the outside from the space formed between the flow path-forming protrusion and the container jaw by blowing air through the gap formed between the TE band and the skirt wall. As described above, the cap of the present invention has excellent washability (water drainability), and effectively prevents bleeding of the printing on the outer surface of the TE band due to cleaning fluid remaining inside the cap.

[0011] Furthermore, as in Patent Document 2, if an axially extending groove is formed in a TE band and this groove is intended to function as a flow path, the groove width must be increased and the groove must be made deep. However, this significantly reduces the strength of the TE band, making it more susceptible to deformation and causing the TE band to climb over the chin of the container when opening the cap. In other words, the width and depth of the groove are significantly limited, and it does not function adequately as a drainage flow path for the cleaning liquid. However, in the present invention, the flow path is formed by a protrusion rather than a groove, so this inconvenience does not occur and the present invention can be fully applied to capping in high-speed filling machines, for example, to ensure water drainage. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a partial cross-sectional side view showing the plastic cap of the present invention together with the container opening. [Figure 2] FIG. 2 is a cross-sectional view of FIG. 1 taken along line AA. [Figure 3] 5A to 5C are diagrams for explaining the function of the flow path forming protrusions in the present invention. [Figure 4] FIG. 2 is a partial development view of the TE band of the plastic cap of the present invention. [Figure 5] 10A to 10C are diagrams showing examples of other forms of flow path forming projections in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Referring to Figure 1, the plastic screw cap (hereinafter sometimes simply referred to as the cap) of the present invention is generally designated by 1. This cap 1 is attached to a container opening 50 by screwing. A thread (male thread) 51 is formed on the outer surface of this container opening 50, and below the thread 51 is formed a jaw (bead) 53 with a larger diameter than the thread 51, and below the jaw 53 is formed a support ring 55 with an even larger diameter for ease of transportation, positioning, etc.

[0014] In the present invention, the cap 1 has a top plate 3 and a skirt wall 5 descending from the periphery of the top plate 3, and a TE band (tamper-evident band) 7 is connected to the lower end of the skirt wall 5 by a plurality of breakable bridges (not shown in the figure), and a slit 9, which is a tiny gap, is formed between the lower end of the skirt wall 5 and the upper end of the TE band 7.

[0015] The skirt wall 5 has an inner surface formed with a thread (female thread) 11 that is threadably mated with a thread 51 provided on the container opening 50 . On the other hand, an inner ring 13 is provided on the inner surface of the top plate 3, extending downward at a distance from the skirt wall 5, and on the outside of the inner ring 13, short auxiliary protrusions 15 inclined outward are formed circumferentially, and further, small, flat protrusions 17 are formed circumferentially between the inner ring 13 and the auxiliary protrusions 15. Furthermore, a hook-shaped locking projection 19 is formed on the inner surface of the TE band 7.

[0016] That is, when the cap 1 is placed over the container mouth 50 and turned in the closing direction, the threads 11 of the cap 1 and the threads 51 of the container mouth 50 thread together and the cap 1 descends. As a result, the upper end of the container mouth 50 enters the space between the inner ring 13 formed on the inner surface of the top plate 3 and the auxiliary protrusion 15, and the upper end surface of the container mouth 50 abuts against the flat surface of the small flat protrusion 17, thereby ensuring a tight seal of the container mouth 50. At this time, the locking protrusion 19 of the TE band 7 climbs over the jaw 53 and is positioned below this jaw 53.

[0017] An inclined surface 21 is formed on the upper side of the locking projection 19 provided on the inner surface of the TE band 7, the thickness of which gradually increases from the top toward the base of the upper end of the locking projection 19. This inclined surface 21 is described in detail in, for example, Patent Document 1 mentioned above.

[0018] That is, when the cap 1 in the closed state is turned in the opening direction, the threads 11 and 51 are disengaged and the skirt wall 5 rises, but the locking projection 19 of the TE band 7 rises and engages with the underside of the jaw 53. This limits the rise of the TE band 7, and as a result, stress is concentrated on a breakable bridge (not shown in the figure) connecting the skirt wall 5 and the TE band 7, causing the bridge to break and the TE band 7 to be separated from the skirt wall 5. If the TE band 7 were to rise all at once due to the rotation in the turning direction at this time, the locking projection 19 would climb over the jaw 23, and the TE band 7 would slip off the container opening 50 while still connected to the skirt wall 5. However, by forming the inclined surface 21 as described above, the TE band 7 gradually rises and the locking projection 19 engages with the jaw 53, effectively eliminating the problem of the TE band 7 slipping off. In this way, the TE band 7 is cut off from the cap 1 that has been removed from the container opening 50, thereby clearly indicating the history of opening.

[0019] In the cap 1 equipped with the above-described TE band 7, in the present invention, as shown in Fig. 1, a flow path forming projection 30 is provided on the inner surface of the TE band 7 above the locking projection 19. Such a flow path forming projection 30 is positioned opposite the jaw portion 53 and is provided so as to abut against the jaw portion 53. That is, as shown in Figure 2 (a cross-sectional view taken along line AA in Figure 1), a gap X is formed around this flow path forming protrusion 30 between the inner surface of the TE band 7 and the outer surface of the jaw portion 53.

[0020] Please refer to FIG. 3 for an explanation of the function of the flow path-forming protrusions 30. In a conventional cap that does not have these flow path-forming protrusions 30, the inner surface of the TE band 7 and the outer surface of the jaw 53 are in contact with each other, as shown in FIG. 3(a). Therefore, if droplets Y of cleaning water accumulate above the jaw 53, even if air is blown onto the droplets Y through the slit 9, no flow path for the droplets Y is formed below the jaw 53, and the droplets escape from the slit 9 and adhere to the outer surface of the TE band 7. This results in the inconvenience of bleeding of the printed characters or the like applied to the outer surface of the TE band 7 by inkjet printing or the like.

[0021] On the other hand, when the flow path forming projections 30 are provided on the inner surface of the TE band 7 according to the present invention, a gap X is formed around the flow path forming projections 30 between the inner surface of the TE band 7 and the outer surface of the jaw 53, and a gap is also formed between the locking projections 19 and the underside of the jaw 53. Therefore, as shown in Figure 3(b), if droplets Y of cleaning water accumulate on the upper side of the jaw 53, by blowing air onto the droplets Y through the slits 9, a flow path is formed that leads to the lower side of the jaw 53, and the droplets Y flow down below the jaw 53 and are discharged without adhering to the outer surface of the TE band 7.

[0022] As described above, according to the present invention, the cleaning water is drained well, and bleeding of the print caused by the cleaning water remaining in the cap 1 can be effectively prevented.

[0023] In the present invention, to maximize the drainage effect of the flow path-forming projections 30 described above, it is preferable to form a plurality of locking projections 19 at intervals in the circumferential direction, as shown in the partial development view of the TE band 7 in FIG. 4, and to form a locking projection 19 above each of the adjacent locking projections 19. For example, depending on the size of the cap 1, in the case of a cap with a nominal diameter of 28 mm, it is preferable to form approximately 3 to 9 locking projections 19, and the total spacing between the locking projections 19 is approximately 1 to 50% of the circumferential length of the TE band 7. This allows for sufficient voids X to be formed around the flow path-forming projections 30, allowing for effective drainage of cleaning water by air blowing. As shown in FIG. 5, the flow path-forming projections 30 may overlap both circumferential ends of the locking projections 19 in the axial direction, as long as they are above the locking projections 19.

[0024] In the example of FIG. 4, the flow path-forming protrusions 30 have a rib shape extending in the axial direction, but as shown in FIG. 5, they can also be block-shaped. In any case, the shape and height of the flow path-forming protrusions 30, as well as their positional relationship with the locking protrusions 19, can be set to maximize drainage performance, taking into account ease of removal from the mold when molding the cap. For example, the height of the flow path-forming protrusions 30 is preferably approximately 0.05 to 0.30 mm. In the example of FIG. 4, one flow path-forming protrusion 30 is provided per section between adjacent locking protrusions 19, but multiple flow path-forming protrusions may be provided.

[0025] As shown in Patent Document 1, a small rib may be formed on the inclined surface 21 formed above the locking projection 19 on the inner surface of the TE band 7. This rib is provided so that when the TE band 7 is separated from the cap 1, the separated TE band 7 falls quickly without coming to rest on the outer surface of the jaw portion 53. In other words, since such a rib is not provided for the purpose of forming a flow path for draining cleaning water, its height is extremely low and it is formed at a position lower than the flow path forming projection 30 in the present invention, and it has almost no drainage function.

[0026] The above-described cap 1 of the present invention can be easily manufactured by injection molding or embossing using a thermoplastic resin, for example, an olefin resin such as polypropylene or polyethylene. [Explanation of symbols]

[0027] 1: Cap 3: Top plate 5: Skirt wall 7:TE band 9:Slit 13: Inner ring 19: Locking protrusion 30: Protrusion for forming flow path 50: Container mouth 53: Jaw X: void Y: Droplets of cleaning water

Claims

1. A plastic screw cap having a top plate, a skirt wall descending from the periphery of the top plate and having threads on its inner surface for threaded engagement with the outer surface of a container mouth, and a tamper-evident band connected to the lower end of the skirt wall by a breakable bridge and having a locking projection on its inner surface for engagement with the underside of the container jaw, a flow path forming protrusion is provided on the inner surface of the tamper-evident band at a position above the locking protrusion, the flow path forming protrusion abutting against the outer surface of the container jaw portion and ensuring a space serving as a flow path for cleaning liquid between the container jaw portion and the inner surface of the skirt wall; the flow path forming projection and the locking projection are spaced apart in the vertical direction, A plastic screw cap, characterized in that, when attached to the container mouth, a gap is formed between the upper surface of the locking projection and the lower surface of the container jaw.

2. A plastic screw cap as described in claim 1, wherein the portion continuing from the upper surface of the locking projection has an annular inclined surface or a circumferentially discontinuous arc-shaped inclined surface that gradually becomes thicker from the top toward the base of the upper end of the locking projection, and the flow path forming projection is arranged above the annular inclined surface or the arc-shaped inclined surface.

3. 3. The plastic screw cap according to claim 1, wherein the locking projections are formed at regular intervals in the circumferential direction, and the flow path forming projections are disposed above and between adjacent locking projections.

4. 4. The plastic screw cap according to claim 1, wherein the flow path forming projection has a rib shape extending in the axial direction or a block shape.

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