JP2008184219A - Plastic cap - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic cap showing a superior fastening characteristic when capping, a superior cap opening characteristic and a superior cap sealing characteristic. <P>SOLUTION: This plastic cap includes a top plate part and a skirt part, the skirt inner surface has a threaded portion and this plastic cap is applied to an opening of a container. The threaded portion is formed with segments having different thread widths. In the plastic cap, an upper inclination surface of the threaded portion engaged with the threaded portion of the opening part of the container when the cap is opened coincides along the inclination of the threaded portion. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plastic cap having a screw portion on the inner surface of a cap skirt portion, and more particularly to a plastic cap excellent in capping and opening properties for a container mouth portion.

In general, in a plastic cap applied to a pressure-resistant container used for contents having a self-generated pressure such as carbonated beverages, particularly in a one-piece type cap, the top plate of the cap becomes a dome due to internal pressure, and the sealing performance is reduced. In order to prevent it, it is formed of a material having high rigidity and the width of the screw is large (for example, Patent Document 1).
For this reason, since such a plastic cap has a large resistance when capping the container mouth portion after filling the contents, there is a risk of causing poor winding.

  In general, in plastic caps, a lubricant such as wax is blended in the resin constituting the cap in order to improve the cap opening performance, and the amount of lubricant is increased in order to facilitate tightening during capping. However, if an excessive amount of lubricant is added, a large amount of lubricant bleeds out, making it difficult to control the tightening. As a result, excessive tightening may occur, and when excessive tightening occurs, the fitting allowance between the cap and the screw portion of the container is reduced. There is a possibility that the cap may be blown at the time of plugging, so that satisfactory openability cannot be obtained.

  In order to reduce the resistance at the time of winding, it has also been proposed to improve the shape of the flap pieces of the screw portion and the tamper evidence band (for example, Patent Document 2 and Patent Document 3).

JP 2004-352260 A Japanese Patent Laid-Open No. 11-180457 Japanese Utility Model Publication No. 4-71649

However, in caps used for contents having a self-generated pressure such as carbonated drinks, it is necessary to sufficiently satisfy both the tightening ability and the opening ability at the time of capping. Can not provide.
Accordingly, an object of the present invention is to provide a plastic cap that is excellent in winding property, capping property and sealing property at the time of capping.
Another object of the present invention is that when applied to a pressure-resistant container, the internal pressure is quickly released at the time of opening, the cap is prevented from jumping, and the tightness at the time of capping is improved. It is to provide a plastic cap.

  According to the present invention, in the plastic cap applied to the container mouth portion, which includes a top plate portion and a skirt portion, and has a screw portion on the inner surface of the skirt portion, the screw portion is formed with portions having different screw widths, A plastic cap is provided in which an upper inclined surface of a screw portion that engages with a screw of a container mouth portion when opening is aligned with the inclination of the screw portion.

In the plastic cap of the present invention,
1. The screw width of the screw part is formed so that thick parts and thin parts are alternately formed,
2. A notch is formed between a portion where the screw width of the screw portion is thick and a thin portion;
3. The parts having different screw widths of the screw parts are evenly arranged over the whole screw parts,
4). A tamper evidence band (hereinafter referred to as “TE band”) having a plurality of flap pieces extending upward and inward on the inner surface is formed at the lower end of the skirt portion through at least a plurality of breakable bridging portions. And a plurality of grooves are formed on the inner peripheral surface of the flap piece,
5. A plurality of notches are formed between the flap pieces, and the notches are formed at asymmetric positions with respect to the radial center of the cap.
Is preferred.

In the plastic cap of the present invention, the frictional resistance at the time of capping can be reduced by forming portions having different screw widths on the screw portion, and the winding property at the time of capping can be improved.
Moreover, since the upper inclined surface of the screw portion is aligned along the inclination of the screw portion regardless of the screw width, the screw engagement between the cap and the container is surely and firmly performed in the closed state. Even when used for contents having a self-generated pressure such as beverages, excellent sealing performance can be exhibited and opening can be performed smoothly.
Further, by providing a notch between adjacent screws with different screw widths, it is possible to reduce the number of places that come into contact with each other during capping, and to further improve the tightening property.
Further, by forming such a notch and an axial groove along the notch, it becomes possible to quickly release the internal pressure when opening the plug, and effectively prevent the cap from jumping at the time of opening. it can.

Furthermore, by forming a plurality of grooves on the surface of the flap piece formed on the inner surface of the TE band that comes into contact with the container mouth portion, it is possible to reduce the frictional resistance due to the TE band at the time of capping. Combined with the improvement of the tightening property due to the width, the tightening property can be further improved.
Also, notches are formed between adjacent flap pieces, and the positions of the notches are asymmetrical with respect to the center in the radial direction, so that deformation of the TE band can be prevented and capping properties can be prevented. In addition, the tamper evidence by the TE band is ensured.

The present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a view showing a side view and a side sectional view of an example of the plastic cap of the present invention, FIG. 2 is a view showing a bottom view of the plastic cap shown in FIG. 1, and FIG. FIG. 4 is a development view of the screw portion of the plastic cap shown, and FIG. 4 is a state in which the plastic cap shown in FIG. 1 is capped at the container mouth (A), and is sealed and fixed at the container mouth ( B) It is a figure explaining the state (C) opened.
The plastic cap of the present invention shown in FIG. 1 to FIG. 4 is, roughly speaking, integrated with the top plate portion 1 and the skirt portion 2 depending from the periphery of the top plate portion, and the lower end of the skirt portion 2 via the bridging portion 3. It consists of a TE band 4 molded into

On the inner surface of the top plate portion 1, an inner ring 5a, an annular protrusion 5b, and an outer ring 5c are formed as a seal portion with a container mouth portion (not shown).
Furthermore, a deformation prevention rib 11 is provided on the inner surface of the top plate portion 1 on the inner side in the radial direction of the inner ring 5a. The deformation prevention rib 11 is formed to prevent deformation of the cap top plate portion 1 due to an increase in internal pressure when used in carbonated beverages or the like.
Further, on the inner surface of the skirt portion 2, there are formed screw portions 6 in which thick screw portions 61 and narrow screw portions 62 are alternately arranged, and adjacent thick screw strips 61 and narrow widths. A groove 7 extending in the axial direction is formed between the screw strips 62.

As described above, in the present invention, the screw portion 6 is formed with portions having different screw widths, and in the specific example shown in the figure, the thick screw portion 61 and the narrow screw portion 62 are alternately arranged. Screw parts 6 are formed by being arranged at intervals.
At this time, as clearly shown in FIG. 3, the wide screw portion 61 and the narrow screw portion 62 coincide with the entire inclined surface of the screw portion 6 at the upper inclined surfaces 61a and 62a. On the other hand, the lower inclined surface 62b of the narrow screw portion is positioned above the lower inclined surface 62a of the thick screw portion, and the lower inclined surface does not form a straight line in the entire screw portion.

As described above, the upper inclined surfaces 61a and 62a of the screw portion 6 are portions that engage with the lower inclined surface 21b of the screw portion 21 of the container mouth portion 20 at the time of opening, and in the present invention, the wide width Since the upper inclined surfaces 61a and 62a of both the screw portion 61 and the narrow screw portion 62 come into contact with the screw portion of the container mouth portion, the cap can be smoothly turned, so that the cap opening property is excellent. (FIG. 4C).
On the other hand, the lower inclined surfaces 61b and 62b of the screw portion 6 are portions that engage with the upper inclined surface 21a of the screw portion 21 of the container mouth portion 20 when the plastic cap is capped. Since only the lower inclined surface 61b of the screw portion 61 is in contact with the upper inclined surface 21a of the screw portion 21 of the container mouth portion 20, the frictional resistance during capping is reduced (FIG. 4A).

In the specific example shown in the figure, a groove 7 extending in the axial direction is formed between the adjacent thick screw portion 61 and narrow screw portion 62.
Thereby, when filling the contents having a self-generated pressure such as carbonated drink, as is clear from FIG. 4 (C), when opening the cap, the screwing of the cap and the container mouth is not released, When the cap seal portion 5 is separated from the container mouth end, the internal pressure can be quickly released from below the cap via the groove 7, and it is possible to effectively prevent the cap from jumping when the cap is opened.

Further, nine flap pieces 8, 8 extending upward and inward from the inner surface lower portion of the TE band 4 are formed at equal intervals on the inner surface of the TE band 4, and the tips 8a of the flap pieces 8, 8 are in the container mouth portion in a sealed state. It is located on the lower surface of the 20 beads 22 (FIG. 4 (B)), and the tamper evidence is expressed by breaking the breakable bridging portion when opening (FIG. 4 (C)).
4A, in the plastic cap in which the TE band 4 is formed at the lower end of the skirt portion 2, the inner peripheral surface 8b with the flap piece 8 formed on the inner surface of the TE band 4 at the time of capping. However, in the present invention, the thickness of the flap pieces 8 and 8 is increased on the inner peripheral surface 8b of each flap piece 8 and 8 formed in the TE band 4 in the present invention. A plurality of grooves 9 to be reduced are provided. This makes it possible to reduce the frictional resistance by reducing the contact area of the flap piece with the container mouth portion at the time of capping, and the winding performance is improved in combination with the configuration of the screw portion described above.

  Further, as is apparent from FIG. 2, notches 10 are formed between the flap pieces 8, 8, and the positions of the notches 10, 10 are asymmetric with respect to the radial center O. Has been. That is, if the positions of the notches 10 and 10 are symmetrical with respect to the center O, the TE band may be deformed during supply before capping and capping failure may occur, but each notch 10 and 10 By being asymmetric with respect to the center O, such deformation of the TE band can be effectively prevented.

The plastic cap of the present invention is not limited to the specific examples shown in FIGS. 1 to 4 described above, and various modifications can be made.
That is, in the specific example shown in the figure, the screw portion 6 is formed with a gap (notch) between adjacent screw portions, and the thick screw portion 61 and the narrow screw portion 62 that are independent from each other are equal. Alternatingly arranged at intervals, the wide and narrow portions are evenly arranged over the whole to form a single thread, which is particularly excellent in terms of openability and resealability. The length or width of each of the wide-width screw portion and the narrow-width screw portion, or the arrangement thereof is not particularly limited, and the hardness of the cap material, the diameter of the cap, and the type of contents (applies to the cap) The pressure can be determined appropriately from the viewpoints of both the plug-opening property and the tightening property.
For example, in a cap with a diameter of 28 mm made of high-density polyethylene, which is applied to a general pressure-resistant polyethylene terephthalate bottle (500 ml), the width of the thick screw portion is in the range of 1.5 to 2.2 mm, The width of the wide screw portion is preferably in the range of 50 to 80% of the width of the thick screw portion. Further, it is preferable that 20 to 50% of the entire length of the screw portion (the length from the start end to the end end) is a narrow screw portion.

  Incidentally, in the point that the screw part is formed with different screw widths and the upper inclined surface is aligned along the inclination of the screw part, unevenness is formed on the lower inclined part of the continuous single thread. A screw portion with an adjusted screw width may be used. Further, the thread portion may be a double thread other than the single thread, and each thread may form a thick thread section and a narrow thread section as in the case of the single thread. .

In addition, the width of the notch (interval) between adjacent screw portions is preferably in the range of 1.0 to 3.0 mm from the viewpoint of plug opening and resealability.
Further, the axial grooves for releasing the internal pressure formed in the notches are not limited in number, width, etc. as long as they are formed at equal intervals, and the cross-sectional shape of the grooves in the transverse direction is also semicircular and triangular. For example, various shapes can be adopted.
The length of the groove is such that the upper end is located above the uppermost end of the screw portion and the lower end is located below the lowermost end of the screw portion, so that the vent function is effectively expressed. Preferred above.

In the specific example shown in the figure, nine flap pieces are formed at equal intervals in the TE band. The number of flap pieces is not limited to this, but in order to make the position of the notch formed between adjacent flap pieces asymmetric with respect to the center O, the number of flap pieces is an odd number. Preferably, it is generally 7 to 11 numbers.
Further, five grooves are formed on the surface of each flap piece that comes into contact with the container mouth, but the number of grooves is not limited, and preferably the surface that comes into contact with the container mouth of the flap piece. It is preferable to form a groove to such an extent that the area is reduced by 10 to 70%. Also, the cross-sectional shape of the groove can be various shapes such as a semicircular shape and a triangular shape.

The plastic cap of the present invention can be integrally molded by injection molding or the like using a resin conventionally used for plastic caps such as polyethylene and polypropylene.
The plastic cap of the present invention can be molded as a one-piece type cap that also integrally molds the seal portion, but of course, it can also be suitably molded into a two-piece type cap in which the seal portion is separately formed in the cap shell.

It is the partial side view and partial side sectional view of an example of the plastic cap of this invention. It is a bottom view of the plastic cap shown in FIG. It is an expanded view of the screw part of the plastic cap shown in FIG. It is a figure for demonstrating the capping process (A) of a plastic cap shown in FIG. 1, a sealing state (B), and a plug opening process (C).

Explanation of symbols

1 top plate, 2 skirt, 3 breakable bridge, 4 TE band, 5 seal,
6 screw part, 6a thick screw part, 6b narrow screw part, 7 groove, 8 flap piece, 9 groove, 10 notch, 20 container mouth part.

Claims (6)

In the plastic cap applied to the container mouth portion, which consists of a top plate portion and a skirt portion, and has a screw portion on the inner surface of the skirt portion,
The screw portion is formed with portions having different screw widths, and the upper inclined surface of the screw portion that engages with the screw of the container mouth portion when opening is aligned with the inclination of the screw portion. And plastic cap.   The plastic cap according to claim 1, wherein the screw width of the screw portion is formed so that thick portions and thin portions are alternately formed.   The plastic cap according to claim 2, wherein a notch is formed between a portion where the screw width of the screw portion is thick and a portion where the screw width is thin.   The plastic cap according to any one of claims 1 to 3, wherein portions of the screw portion having different screw widths are arranged uniformly over the entire screw portion.   A tamper evidence band having a plurality of flap pieces extending upward and inward is formed on the inner surface through at least a plurality of breakable bridging portions at the lower end of the skirt portion. The plastic cap according to any one of claims 1 to 4, wherein a plurality of grooves are formed on the inner peripheral surface.   The plastic cap according to claim 5, wherein a plurality of notches are formed between the flap pieces, and the notches are formed at positions asymmetric with respect to the radial center of the cap.

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