JP2012197087A - Plastic cap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastic cap with a tamper evident band in which a bridge break at capping can be prevented effectively, and a plug opening characteristic thereof is improved.SOLUTION: In the plastic cap which is provided with a TE band 7 connected to the lower end of a cap skirt 3 via a breakable bridge 5 and in which a plurality of flap pieces 11 directing inward and upward are arranged in the peripheral direction with a space on the inner surface of the TE band 7, a plurality of flap pieces 11 are distributed longitudinally from the root and flap pieces located at a side opposite to the longest long flap piece 11a are short flap pieces 11b, 11c shorter than the long flap piece.

Description

  The present invention relates to a plastic cap provided with a tamper evident band (TE band).

  In general, many plastic caps attached to containers containing beverages or the like are provided with a TE band to prevent mischief and to assure the quality of contents. The TE band is connected to the lower end of the cap skirt portion via a breakable bridge, and the inner surface of the skirt portion to which the TE band is connected is a male male container formed on the outer surface of the container mouth. A female thread of a cap that engages with the thread is formed (for example, see Patent Document 1).

  On the inner surface of the TE band as described above, a plurality of flap pieces that are directed inward and upward are arranged at intervals in the circumferential direction. TE property is exhibited by engaging with the jaw portion of the container formed on the outer surface of the container. That is, when the flap piece is engaged with the jaw portion of the container at the time of opening, the TE band is prevented from rising, and only the skirt portion above the TE band is raised. As a result, the bridge connecting the TE bands is broken, and the cap is opened with the TE bands disconnected. Therefore, a general consumer can recognize the fact that the cap has been opened due to the TE band being cut off.

Utility model registration No. 2526433

  However, in the plastic cap provided with the TE band as described above, since the bridge connecting the skirt portion and the TE band has to be broken at the time of opening, there is a disadvantage that the opening torque is large and the opening is difficult. . This disadvantage is a big problem especially for elderly people and children with weak grip.

  In order to improve the above drawbacks, for example, it is conceivable to reduce the strength of the bridge. However, weakening the strength of the bridge cannot be adopted because the bridge tends to break during capping after the container contents are filled in the container.

  Accordingly, it is an object of the present invention to effectively prevent the breakage of the bridge during capping and improve the opening of the plastic cap having a tamper evident band.

According to the present invention, the tamp includes a top plate portion, a skirt portion lowered from the periphery of the top plate portion, and a tamper evidence band connected to the lower end of the skirt portion via a plurality of breakable bridges. A plurality of flap pieces directed inward and upward are arranged at intervals in the circumferential direction on the inner surface of the evidence band, and the container is formed on the outer surface of the container mouth portion on the inner surface of the skirt portion In the plastic cap in which the female thread of the cap engaged with the male thread is formed,
The plurality of flap pieces have a distribution in length from the base thereof, and the flap piece located on the side facing the longest flap piece having the longest length is shorter than the long flap piece. A plastic cap is provided which is a short flap piece.

In the plastic cap of the present invention,
(1) The female thread of the cap is longer than one turn and extends so that the thread start point and the thread end point are not located on the same axis, and the skirt portion at a position including the long flap piece The positions of the long flap pieces and the short flap pieces so that the number of the female threads in the side cross section of the skirt portion is smaller than the number of the female threads in the side cross section of the skirt portion at the position including the short flap pieces. Is set,
Is preferred, and
(2) The bridge formed at the position corresponding to the portion where the long flap piece is formed is compared with the bridge formed at the position corresponding to the portion where the short flap piece is formed. Include high-strength bridges that are formed wide,
Or
(3) The bridge formed at the position corresponding to the portion where the long flap piece is formed is compared with the bridge formed at the position corresponding to the portion where the short flap piece is formed, Being formed with low strength,
(4) The short flap piece is positioned between the shortest flap piece located on the side facing the long flap piece, the long flap piece and the shortest flap piece, and has a good length. Consisting of long medium and short flap pieces,
It can take the form.

In the present invention, the plurality of flap pieces provided on the inner surface of the tamper evidence band (TE band) have a distribution in the length from the root, and the longest flap piece and the long flap piece having the longest length. Shorter flap pieces having a shorter length are formed.
That is, in such a TE band, the length of the flap piece is different between the long flap piece side and the short flap piece side. Therefore, when the cap attached to the container mouth is opened, the long flap piece first comes into contact with the lower side of the container jaw and the rise at this portion is restricted, and then the short flap following the long flap piece. The piece comes into contact with the container jaw. Since the plug is opened in this way, the bridge located on the axis of the portion where the long flap piece is located is broken, and the bridges on both sides of the bridge are broken starting from this bridge.
As understood from this, in the cap of the present invention, at the time of opening, a large number of bridges connecting the TE bands are not broken at once, but are located on the axis of the portion where the long flap piece is located. It is broken from the bridge one after another.
Therefore, the cap of the present invention can be opened with a small force as compared with the conventional cap in which a large number of bridges are broken at once and the cap is opened, and has an excellent openability.

  Further, in the present invention, in order to make the maximum use of the length distribution of the flap piece as described above and to remarkably improve the cap opening performance, the cap female thread is longer than one turn and the thread start. The point and the thread end point extend so as not to be located on the same axis, and the number of the female threads in the side cross section of the skirt portion at the position including the long flap piece is a position including the short flap piece. It is optimal that the positions of the long flap piece and the short flap piece are set so as to be smaller than the number of female threads in the side cross section of the skirt portion.

More specifically, the female thread of the cap is formed longer than one turn in order to firmly engage with the male thread of the container mouth (that is, one or more rounds on the inner surface of the cap skirt). If the setting is made so that the thread start point and thread end point of the female thread do not lie on the same axis, the cross section of the skirt is observed on the side section. The number of female threads of the cap to be used is different. For example, when the circumferential length of the female thread is less than two, a side cross section in which only one female thread exists and a side cross section in which two female threads exist can be formed.
In the present invention, the structure is such that the side cross-section can be formed with different numbers of female threads in the side cross-section of the skirt portion, and the cross-section of the skirt portion including the long flap piece is formed. The positions of the long flap pieces and the short flap pieces are set so that the number of the female threads is smaller than the number of the female threads in the side cross section of the skirt portion at the position including the short flap pieces. It is.
That is, the position of the side cross section where the number of female threads of the cap is small is the position where the female thread and the male thread of the container mouth part are less than the other parts. The part where the skirt part is most likely to move upward when turning and opening in the direction, and the part where the number of female threads on the cap is large on the side section is the part where the skirt part is most difficult to move upward It is. As understood from this, in the above aspect, when the cap is opened, the long flap piece is located in the portion where the skirt portion is most easily movable upward, and the skirt portion is most likely to rise. First of all, the rise of the TE band upon opening is limited. Therefore, when the cap is opened, the breakage of the bridge proceeds promptly starting from the portion where the long flap piece is formed, and excellent openability can be ensured.

  Since the cap of the present invention has excellent openability, there is an advantage that the degree of freedom regarding the bridge strength is high and various settings can be made for the bridge strength. That is, since the opening of the bridge can be easily performed even when the strength of the bridge is increased, various characteristics such as effectively preventing breakage of the bridge at the time of capping are achieved by utilizing this characteristic. be able to.

  For example, with respect to the bridge corresponding to the above-mentioned long flap piece (that is, the bridge that breaks first when opened), the bridge width is increased to increase the bridge strength, thereby opening the cap to general consumers. A feeling of opening can be given. This is because the elongation of the bridge is small, and when the cap is opened, the bridge is broken at a stroke, so that a general consumer can reliably recognize a change in tactile sensation before and after the breaking. Further, in some cases, when this wide bridge breaks, a “click” sound may be generated.

In addition, the bridge strength of the bridge corresponding to the long flap piece (the bridge that breaks first when opened) is set to be weak, and the bridge strength of other bridges is set to be high so that it is excellent. The TE property can be improved without impairing the opening property, and at the same time, the bridge break during capping can be effectively prevented. That is, since the bridge strength of the bridge that breaks first at the time of opening is set to be weak, when the cap is opened, the first bridge is surely broken before the seal break. improves. In addition, since the bridge strength of the other bridges is set high, bridge breakage during capping is effectively prevented.
In order to prevent bridge breakage at the time of capping, if the means for increasing the bridge strength is adopted, the openability is naturally reduced, but in the present invention, the long flap piece abuts the container jaw. In this case, since the corresponding bridge is easily broken, a means for increasing the bridge strength can be employed.

The figure which shows the side surface of the plastic cap of this invention with a container opening part. The figure which shows the side cross section of the cap of FIG. 1 with a container mouth part. The bottom view of the cap of FIG. The figure which shows the upper end surface of TE band of the cap of FIG. The perspective view of the cap of FIG. It is a figure which expands and shows the principal part of FIG. 2, (a) expands and shows the side cross section of a long flap piece, (b) is the figure which expands and shows the side cross section of a short flap piece. FIG. 7 is a development view of the TE band of the cap of FIG. The side view for demonstrating the form of TE band in the middle of opening of a cap. FIG. 9 is a side sectional view of FIG. 8. The expanded view of the other TE band used for the plastic cap of this invention. The expanded view of other TE band used for the plastic cap of this invention. The figure which shows the upper end surface of the TE band joined by the bridge | bridging of a form different from FIG. The figure which shows the upper end surface of TE band joined by the bridge | bridging of a form different from FIG.

1 to 5, the plastic cap of the present invention is formed by integral molding of polyolefin such as polypropylene and polyethylene, and includes a top plate portion 1 and a skirt portion 3 that descends from the periphery of the top plate portion 1. A tamper evidence band (TE band) 7 is provided at the lower end of the skirt portion 3 via a plurality of breakable bridges 5.
Further, as shown in FIG. 1 and FIG. 2, a male thread 53 for screw engagement with a cap, a jaw portion 55 for engagement with a TE band, and a container are easily provided on the outer surface of the container mouth portion 51. A support ring 57 is formed in order from above.

In the cap, a female thread 9 is formed on the inner surface of the skirt 3 so as to be engaged with the male thread 53 of the container mouth 51. The inner surface of the TE band 7 is inward and upward. A plurality of the flap pieces 11 that are oriented are formed at appropriate intervals. The flap piece 11 is engaged with the jaw 55 formed on the outer surface of the container mouth portion 51 and below the container screw 53 when the cap is opened. The upward movement is restricted, the bridge 5 is broken, the TE band 7 is cut off from the skirt portion 3, and the cap is opened.
The flap piece 11 is not formed as one annular piece, but is formed as a plurality of pieces (in this example, four flap pieces 11 are formed as shown in FIG. 3). This is because the engagement with the container jaw 55 is taken into consideration. That is, such a flap piece 11 is formed in a state of being directed downward, and is formed by being inverted upward using a predetermined jig after forming. In such a flap piece 11, when it has an annular shape, when it is inverted upward, it becomes almost upright, and therefore when the flap piece 11 is engaged with the container jaw 55, A slight deformation or the like tends to cause inconvenience such as the TE band 7 being completely removed. However, the flap pieces 11 are not formed in an annular shape, but are divided into a plurality of pieces, so that when the flap pieces 11 are inverted upward, each flap piece 11 is not in an upright state but in an obliquely inclined state. This is because it is possible to increase the engagement force with the container jaw 55 and to reliably prevent inconvenience such as the slipping of the TE band 7.

In addition, as can be understood from FIG. 3, each flap piece 11 has a notch 13 formed in the center portion. When this cap 13 is attached to the container mouth 51, The flap piece 11 is provided in order to ease resistance when the container male thread 53 and the jaw portion 55 are overcome, and to improve the plug-closing property. Further, instead of such a notch 13, the flap piece 11 can overcome the male thread 53 and the jaw 55 of the container by forming an appropriate groove on the inner surface of the flap piece 11 (the surface on the cap center side). When the resistance can be relaxed.
Note that the notch 13 of the TE band 7 is omitted in the perspective view of FIG.

Although not shown by the imprinting numbers, as shown in FIG. 1, a knurling for preventing slipping is formed on the outer surface of the skirt portion 3. It can be easily rotated in the closing direction.
Further, a plurality of cleaning slits 14 are formed on the outer surface of the skirt portion 3 at appropriate intervals above the skirt portion 3. That is, after the cap is mounted on the container mouth portion 51, washing water is introduced into the inner surface of the cap from the slit 14 by a shower or the like, so that the liquid spilled between the cap and the container mouth portion 51 can be removed. It can be removed by washing. Note that forming a plurality of flap pieces 11 instead of annularly has an advantage that the washing water can be easily removed when washing is performed in this manner.

  On the other hand, an inner ring 15 is formed on the inner surface of the top plate portion 1 so as to extend downward with a gap from the skirt portion 3. As shown in FIG. 2, the inner ring 15 has a shape in which an outer surface (a surface on the skirt portion 3 side) swells outward. That is, when the cap is attached to the container mouth 51 using the screw engagement between the cap female thread 9 and the male male thread 53 (ie, closing), as shown in FIG. The upper part of the container mouth part 51 enters between the skirt part 3 and the inner ring 15, and the outer surface of the inner ring 15 is in close contact with the inner face of the container mouth part 51, thereby ensuring the sealing performance. is there.

  An outer ring 17 is formed on the inner surface of the top plate portion 1 at a portion between the inner ring 15 and the skirt portion 3. The outer ring 17 is for guiding the container mouth 51 into the cap so that the upper end of the container mouth 51 is in close contact with the outer surface of the inner ring 15 when the cap is closed.

  An annular small protrusion 19 is formed in the vicinity of the base portion of the outer ring 17. The annular small protrusion 19 is formed so as to be in close contact with the upper corner portion of the container mouth portion 51 in a state where the cap is closed, and the container mouth portion 51 is formed in an annular shape with the outer surface of the inner ring 15. It is firmly held between the small protrusions 19, and the sealing performance is reinforced by the annular small protrusions 19.

  Further, as shown in FIG. 3, a rib 21 is formed in the central portion of the inner surface of the top plate portion 1. The rib 21 extends radially from the cap center O and has a shape in which the tip ends are annularly connected. . The rib 21 is provided, for example, for height adjustment during printing. For example, when the cap is held on a predetermined mandrel or the like, the outer surface of the top plate portion 1 is held flat, and printing is performed. The work can be performed smoothly.

In the present invention, it is an important feature that the length distribution is formed on the plurality of flap pieces 11 formed on the inner surface of the TE band 7.
That is, referring to FIG. 1 to FIG. 5 together with the enlarged view of the main part of FIG. 6 and the developed view of the TE band 7 of FIG. 7, the plurality of flap pieces 11 have a long length L from the base. It consists of a long flap piece 11a and a short flap piece having a shorter length than the long flap piece 11a, and the short flap piece is a length between the shortest flap piece 11b having the shortest length L and both the flap pieces 11a, 11b. It consists of the medium-short flap piece 11c which has. Further, as apparent from FIGS. 6 and 7, the long flap piece 11a and the shortest flap piece 11b are opposed to each other in the radial direction, and the medium and short flap piece 11c is the long flap piece 11a and the shortest flap piece 11b. Is located between. For example, as shown in FIG. 6A, the tip of the long flap piece 11a is located in the vicinity of the container jaw 55, but the shortest flap piece 11b facing the long flap piece 11a. The tip is located slightly away from the container jaw 55 as shown in FIG. 6 (b). Therefore, although not shown in the figure about the medium-short flap piece 11c, the front-end | tip is separated from the container jaw part 55 in the intermediate position of Fig.6 (a) and FIG.6 (b).
Each of the long flap piece 11a, the shortest flap piece 11b, and the medium and short flap piece 11c is formed with the aforementioned notch 13 at the center portion in the circumferential direction (see FIG. 7). The resistance at the time of mounting on the bag is eased, and the capping property is improved.

When the cap of the present invention having the TE band 7 provided with the flap pieces 11a to c as described above is opened, the long flap piece 11a first comes into contact with the lower side of the container jaw 55 in the initial stage of opening. The rise in this part is restricted, and therefore the bridge 5 located on the axis of the part where the long flap piece 11a is located is first broken. In this state, the shortest flap piece 11b and the medium-short flap piece 11c are not in contact with the lower side of the container jaw 55, and the bridge 5 is located on the axis of the portion where the flap pieces 11b and 11c are located. Is not broken.
When the cap is further rotated from the initial stage of the opening, the opening is performed with reference to FIGS. 8 and 9 showing the form of the TE band 7 in the middle of the opening, adjacent to the long flap piece 11a. The medium / short flap piece 11c contacts the lower side of the container jaw 55 and the bridge 5 located above the medium / short flap piece 11c is broken. In this state, the tip of the shortest flap piece 11b is the container jaw 55. The bridge 5 located above the shortest flap piece 11b has not yet been broken. Therefore, as shown in FIGS. 8 and 9, the TE band 7 is in a state of being connected to the lower end of the skirt portion 3 in a so-called half-open state in the middle of opening.
When such opening is continued, finally, the shortest flap piece 11b comes into contact with the lower side of the container jaw 55, and the bridge 5 located above the shortest flap piece 11b is broken, thereby the TE band. 7 is completely separated from the skirt part 3, and the fact that the TE band 7 is separated (or that the bridge 5 is broken), the general consumer knows that the cap has been opened. It can be clearly recognized.

Thus, in the cap of the present invention in which the flap piece 11 has a length distribution, when the cap is opened, a large number of bridges 5 connecting the TE bands 7 are not broken at once, but are long. Since the bridge 5 located above the flap piece 11a starts as a starting point, the bridge 5 located above the medium-short flap piece 11c and the bridge 5 located above the shortest flap piece 11b are gradually broken. The force required to open the plug (opening torque) is low, and the plug is easily opened.
For example, a conventionally known plastic cap with a TE band does not have a length distribution formed on the plurality of flap pieces 11 and the lengths are uniform, so that the TE band 7 is connected when the cap is opened. The bridge 5 is broken at a stroke so that the TE band 7 is separated from the cap. For this reason, a large force is required to open the cap. However, in the present invention, the flap piece 11 has a length distribution so that the cap can be opened with a small force.

  In the above-described embodiment of the present invention, the circumferential width and number of the flap pieces 11a to 11c are positioned so that the long flap piece 11a and the shortest flap piece 11b face each other, and the long flap piece 11a As long as the middle and short flap pieces 11c are located between the shortest flap pieces 11b, there is no particular limitation, but generally, the circumferential widths of the flap pieces 11a to 11c are set to the same level, and the long flap pieces Between the pair of 11a and the shortest flap piece 11b, there are 1-2 medium and short flap pieces 11c, respectively, and a total of about 4 to 6 flap pieces 11 are formed. And the degree of engagement with the container jaw 55 is preferable. Incidentally, in the cap of the example described above, four flap pieces 11 are formed as shown in FIGS. 3 and 7.

  Moreover, although the positional relationship of each flap piece 11a-11c mentioned above is not restrict | limited in particular, when opening a cap in order to exhibit the improvement effect of the plug opening property by length distribution mentioned above to the maximum It is preferable to provide a structure in which the female thread 9 of the cap is provided so that the skirt portion 3 is formed with the most movable portion so that the long flap piece 11a is located in the movable portion. It is.

For example, the female thread 9 of the cap extends to the inner surface of the skirt portion 3 with a length of one or more rounds (one or more turns), and thus, firmly between the male thread 53 of the container mouth 51. Although the screw can be engaged, the length of the female thread 9 is set so that the end point is not positioned below the start point 9a (see FIG. 5) in the axial direction. When the length of the female thread 9 is set in this way, the size of the number of female threads 9 present in the side cross section varies depending on the position of the side section of the skirt portion 3. For example, if the length of the female thread 9 is not less than two but not less than two turns of the skirt part 3, the number of the female threads 9 is 1 or 2 depending on the position of the side cross section of the skirt part 3. Incidentally, in FIG. 2, one female thread 9 exists in the right side cross section of the skirt portion 3, and two female threads 9 exist in the left side cross section.
That is, when the female thread 9 extends with such a length that its start point and end point are located on the same axis, the number of female threads 9 varies depending on the position of the side cross section of the skirt portion 3. In any case, the number of the female threads 9 corresponds to the number of turns in the side cross section at any position.

  As described above, when the structure is such that the number of cap female threads 9 in the side cross section differs depending on the position of the side cross section of the skirt portion 3, the number of female threads 9 is small (for example, FIG. 2) is a position where the female thread 9 and the male thread 53 of the container are less engaged than the other parts, so that the cap is swung in the opening direction. When opening, the skirt portion 3 is the portion that is most easily movable upward, and a position where a large number of female threads on the cap is observed (for example, the portion corresponding to the left side cross section in FIG. 2) ) Is a portion in which the skirt portion 3 is most difficult to move upward.

  In the present invention, it is desirable to set the position of the long flap piece 11a described above to a portion where the skirt portion 3 is most easily movable when the cap is opened, whereby the skirt portion 3 is most likely to rise. Thus, the rise of the TE band 7 at the time of opening is restricted first, and a large stress acts on the bridge 5 at this portion. Therefore, when the cap is opened, the bridge 5 is rapidly broken starting from the bridge 5 located above the portion where the long flap piece 11c is formed, and excellent openability is ensured. It can be done.

Further, in the above-described example, as shown in FIG. 7, the length is gradually reduced from the long flap piece 11a to the medium / short flap piece 11c and the shortest flap piece 11b. It is also possible to set a length distribution that is tapered.
For example, as shown in the developed view of the TE band 7 in Fig. 10, the longest length L ₁ at the center portion of the long flap pieces 11a, at the center portion of the shortest flap piece 11b opposed thereto and shortest length L _2, from the center of the long flap piece 11a toward the center of the shortest flap piece 11b, the long flap piece 11a, the length in the short flap piece 11c and the shortest flap piece 11b is gradually reduced It is also possible to do so. In particular, the aspect in which the length distribution is set in a tapered shape as shown in FIG. 10 has an advantage that it is easy to make a mold.

Furthermore, in the present invention, the thickness distribution of the flap piece 11 is not particularly limited as long as the length of the flap piece 11 does not change drastically and does not cause backlash or molding failure. also varies depending typically, the length L of the long flap piece 11a (maximum length L ₁ in the example of FIG. _10), the maximum length L in the example of the length L (FIG. 10 of the shortest flap piece 11b ₂ ) is set to about 50 to 70%.

  Further, in the present invention, the thickness distribution of the flap piece 11 does not have three stages as described above, but, for example, as shown in the development view of the TE band 7 in FIG. It is also possible to have two stages of short flap pieces 11c. Even in this case, the effects of the present invention can be obtained.

  The cap of the present invention having the above-described structure has an excellent openability. Therefore, the strength of the bridge 5 connecting the skirt portion 3 and the TE band 7 can be variously changed. There are advantages. This is because, as described above, the plug can be easily opened even when the strength of the bridge 5 is increased.

  For example, a large number of bridges 5 that connect the skirt portion 3 and the TE band 5 need to be set to a low strength so that they can be easily broken when the cap is opened. Breaks the bridge 5 when getting over the container jaw 55. For this reason, normally, as shown in FIG. 4, the thick bridges 5a having a relatively large bridge width d and the thin bridges 5b having a small bridge width d are alternately positioned so as to be evenly distributed in the entire circumferential direction. Dispersion is made so that the bridge width d of the thick bridge 5a is also about 2.0 to 2.5 mm to ensure a balance between the unplugging property and the prevention of bridge breakage during capping.

However, in the present invention, as shown in FIG. 12, the bridge width d of the portion corresponding to the long flap piece 11a (the bridge 5 that breaks first at the time of opening) is extremely large. A high-strength bridge 5c can be provided. In other words, the bridge width d of the high-strength bridge 5c is set to be considerably thick, about 0.5 to 0.7 mm. By providing such a high-strength bridge 5c, a cap can be opened to general consumers. A feeling of opening can be given.
That is, when the bridge strength is set as shown in FIG. 4 and the like, since the elongation of the bridge 5 is large, the change in the tactile sensation when the bridge 5 is first broken is scarce, and a general consumer has a cap. I don't feel a sense of freedom. However, the high-strength bridge 5c having a remarkably large bridge width as described above has little elongation and breaks at a stretch, and is provided at a position where it is first broken when the cap is opened. Therefore, when a cap is opened, a general consumer can first and reliably recognize a change in tactile sensation before and after the break. Further, when the bridge 5c breaks at a stroke, a “click” sound may be generated. Therefore, by providing the high-strength bridge 5c as shown in FIG. 12, a feeling of opening when the cap is opened can be given.

  In the example of FIG. 12, the bridge interval L of the bridge 5 corresponding to the long flap piece 11a is set large, and at the same time, the bridges 5 other than the high-strength bridge 5c are the same as in the example of FIG. The thick bridges 5a and the bridge widths d may be arranged at equal intervals with a small width so that they are alternately positioned.

  Further, in the example of FIG. 13, the bridge 5 in the portion corresponding to the long flap piece 11 c is all set as a narrow narrow bridge 5 b, and the bridge strength in this portion is set to be weak overall, and the bridge 5 in the other portion. Is a thick bridge 5a having a relatively large bridge width d. In this embodiment, since the bridge strength of the bridge 5 (5b) that breaks first at the time of opening is set to be weak, when the cap is opened, the first break of the bridge 5 is surely performed prior to the seal break. Thereby, TE property improves. Moreover, since the bridge strength of the other bridges 5 (5a) is set high, bridge breakage during capping is effectively prevented.

  As described above, the plastic cap of the present invention has a very high degree of freedom in designing because it has excellent openability despite the provision of the TE band that is cut off at the time of opening. Various structures can be employed without impairing the properties.

1: Top plate part 3: Skirt part 5: Bridge 5a: Thick bridge 5b: Fine bridge 5c: High-strength bridge 7: Tamper evidence band (TE band)
9: female thread 11: flap piece 11a: long flap piece 11b: shortest flap piece 11c: medium and short flap piece 21: container mouth 23: male screw 25: container jaw

Claims (5)

A top plate portion, a skirt portion that descends from the periphery of the top plate portion, and a tamper evidence band that is connected to the lower end of the skirt portion through a plurality of breakable bridges. A plurality of flap pieces directed inward and upward are arranged at intervals in the circumferential direction, and a male thread and a screw of the container formed on the outer surface of the container mouth portion on the inner surface of the skirt portion In the plastic cap in which the female thread of the cap to be engaged is formed,
The plurality of flap pieces have a distribution in length from the base thereof, and the flap piece located on the side facing the longest flap piece having the longest length is shorter than the long flap piece. A plastic cap characterized by short flap pieces.   The female thread of the cap is longer than one turn and extends so that the thread start point and the thread end point are not located on the same axis, and the side cross section of the skirt portion at the position including the long flap piece The positions of the long flap pieces and the short flap pieces are set so that the number of the female threads in is smaller than the number of the female threads in the side cross section of the skirt portion at the position including the short flap pieces. The plastic cap according to claim 1.   The bridge formed at the position corresponding to the portion where the long flap piece is formed is wider than the bridge formed at the position corresponding to the portion where the short flap piece is formed. 3. A plastic cap according to claim 1 or 2, comprising a formed high strength bridge.   The bridge formed at the position corresponding to the portion where the long flap piece is formed is lower in strength than the bridge formed at the position corresponding to the portion where the short flap piece is formed. The plastic cap according to claim 1 or 2, wherein the plastic cap is formed.   The short flap piece is located between the shortest flap piece located on the side facing the long flap piece, the long flap piece, and the shortest flap piece, and has a longer and shorter length than the shortest flap piece. The plastic cap according to claim 1, comprising a flap piece.

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