JP5086148B2 - Plastic container lid - Google Patents

Description

  The present invention relates to a synthetic resin container lid having a circular top wall and a cylindrical skirt wall depending from the periphery of the top wall. More specifically, a female thread is formed on the inner peripheral surface of the skirt wall. The outer peripheral surface is divided into 2n regions, where n is a natural number of 2 or more, and the first region and the second region are alternately present, and the first region has an angular interval of α degrees. In addition, the present invention relates to a synthetic resin container lid in which a large number of protrusions extending in the axial direction are formed, and in the second region, a large number of protrusions extending in the axial direction are formed at an angle interval of 2α degrees.

  In Patent Document 1 below, as a container lid for a container having a male thread formed on the outer peripheral surface of a cylindrical mouth and neck, a circular top wall and a cylindrical skirt wall hanging from the periphery of the top wall A synthetic resin container lid is disclosed. On the inner peripheral surface of the skirt wall, a female thread that is screwed into a male thread formed on the mouth and neck of the container is formed. The outer peripheral surface of the skirt wall is divided into, for example, six regions extending over an angular range of 60 degrees, that is, three first regions and three second regions that are alternately present. Yes. For example, a number of protrusions extending in the axial direction at an angular interval of 3 degrees are formed in the first region, and a number of extending lines in the axial direction are formed in the second region at an angular interval of 2α degrees. The ridges are formed. These ridges are generally referred to as knurls, and are arranged to prevent slipping of fingers hung on the outer peripheral surface of the skirt wall.

When the container lid is mounted on the mouth / neck portion of the container, a container lid mounting apparatus including a chuck for holding the container lid is used. The container lid held by the check is fitted on the mouth and neck of the container, is rotated in the closing direction, that is, clockwise when viewed from above, and is formed on the inner peripheral surface of the skirt wall of the container lid. Is screwed into a male thread formed on the outer peripheral surface of the mouth and neck of the container. As a chuck for holding the container lid, a chuck disclosed in Patent Document 2 below is used. Such a chuck is composed of an annular member that defines a container lid housing space whose lower surface is open. The annular member has a frustoconical engagement inner peripheral surface whose radius gradually decreases upward, and a plurality of engagement protrusions extending in the axial direction at equal angular intervals are formed on the engagement inner peripheral surface. Is formed. A plurality of holes penetrating in the radial direction at equal intervals in the circumferential direction are formed in the lower part of the annular member, and a sphere is arranged in each of the holes so as to be movable in the radial direction. The directional inner end is defined by a circle having a diameter smaller than the diameter of the sphere, which limits the movement of the sphere radially inward. The center axis of each of the holes and the center axis of the circle defining the radially inner end are aligned with one circumferential center of the locking protrusion formed on the locking inner peripheral surface. The annular member is provided with elastic biasing means for elastically biasing the sphere radially inward. The container lid is accommodated in the container lid accommodating space, and a sphere that partially protrudes radially inward from the hole is elastically pressed to the lower part of the outer peripheral surface of the skirt wall of the container lid. A container lid is held. When the annular member constituting the chuck is rotated in the closing direction, the engagement protrusion of the annular member is engaged with the protrusion formed on the outer peripheral surface of the skirt wall of the container in the circumferential direction. Thus, the required rotational torque is transmitted to the container lid, and the female thread of the container lid is screwed to the male thread of the mouth and neck of the container with the required torque.
JP 2008-44629 A Japanese Utility Model Publication No. 7-31693

  Thus, the outer surface of the skirt wall is formed with a plurality of ridges extending in the axial direction with an angular interval of α degrees and the first region extending in the axial direction with an angular interval of 2α degrees. A plurality of locking ridges extending in the axial direction at an angular interval of 2α degrees, for example, are formed on the container lid in the form in which the second regions where the ridges are formed are alternately present. It has been found that the following problems occur when the formed chuck is applied. That is, when the container lid is accommodated in the container lid accommodating space of the annular member constituting the chuck, one of the plurality of balls arranged on the annular member is the second region on the outer peripheral surface of the skirt wall of the container lid. One of the ridges formed in the first region of the skirt wall of the container lid is another one of the plurality of balls when positioned between two adjacent ridges formed on In the first region of the skirt wall, the locking ridge of the annular member is not between two adjacent ridges formed on the outer peripheral surface of the skirt wall. The ridge formed on the skirt wall is located opposite to one circumferential center of the skirt wall, and the ridge formed on the skirt wall is damaged in the first region of the skirt wall. In some cases, a container lid accommodated in the container lid accommodating space of the annular member Sometimes it becomes inclined to Jo member. Such a problem will be further described later with reference to the accompanying drawings.

  The present invention has been made in view of the above-mentioned facts, and the main technical problem thereof is that a plurality of protrusions extending in the axial direction are formed on the outer peripheral surface of the skirt wall at an angular interval of α degrees. A container lid in a form in which a plurality of protrusions extending in the axial direction with an angular interval of 2α degrees are formed alternately with one region, and the locking inner peripheral surface has, for example, 2α degrees Even when a chuck having a configuration in which a large number of locking protrusions extending in the axial direction are formed at an angular interval is applied, it is possible to reliably prevent the above-described problem from occurring.

  As a result of diligent research and experiments, the inventors of the present invention have found that the protrusions in the radial direction of the protrusions formed in the second region on the outer peripheral surface of the skirt wall of the container lid have the first protrusion amount in the radial direction. The above-mentioned main technique is achieved by adding a modification that the projections in the radial direction of the ridges formed in the area of the ridge are the same, but the projections in the radial direction of the remaining ridges are made somewhat smaller. We found that we can achieve the objective.

That is, according to the present invention, the synthetic resin container lid for solving the main technical problem has a circular top wall and a cylindrical skirt wall depending from the periphery of the top wall, and the inner periphery of the skirt wall. A female thread is formed on the surface, and the outer peripheral surface of the skirt wall is divided into regions of 2n in the circumferential direction and n is a natural number of 2 or more, and the first region and the second region are alternately arranged. A plurality of protrusions extending in the axial direction at an angular interval of α degrees are formed in the first region, and extending in the axial direction at an angular interval of 2α degrees in the second region. In a synthetic resin container lid in which a large number of protrusions are formed,
The protrusion formed in the first region has a radial protrusion amount x, the odd number of protrusions are formed in the second region, and the protrusion is formed in the second region. The projecting ridge includes normal projecting ridges and low projecting ridges alternately arranged, and the projecting ridges located on both sides in the circumferential direction are the low projecting ridges, and the projecting amount in the radial direction of the normal projecting ridge is x. However, there is provided a synthetic resin container lid characterized in that the protruding amount in the radial direction of the low protrusion is y smaller than x.

In good suitable embodiment, the n is 3, the outer peripheral surface of the skirt wall there are the three of the first region and three of the second region, said first region The extension angle of each of the second regions and the extension angle of each of the second regions are all 60 degrees. The α degree is 3 degrees, the x is 0.3 mm, and the y is 0.2 mm.

  According to the container lid of the present invention, in the second region on the outer peripheral surface of the skirt wall, there are a normal ridge having a radial protrusion amount x and a low ridge having a radial protrusion amount y smaller than x. Since they are alternately formed, when the container lid is accommodated in the container lid accommodating space of the annular member, one of the plurality of spheres arranged on the annular member is the first on the outer peripheral surface of the skirt wall of the container lid. Even if it is located in the middle of two adjacent ridges formed in the two regions, the container lid is surrounded by the annular member due to the difference in the radial protrusion amount of the two adjacent ridges. The other one of the plurality of spheres is located opposite one circumferential center of the ridge formed in the first region of the container lid skirt wall. Thus avoiding the locking ridges of the annular member in the first region of the skirt wall. It is avoided located opposite to one circumferential center of the protrusion formed on the outer circumferential surface of the cart walls, thus the occurrence of the problems can be reliably prevented.

  Hereinafter, a preferred embodiment of a synthetic resin container lid constructed according to the present invention will be described in detail with reference to the accompanying drawings.

  1 to 4 illustrate a preferred embodiment of a container lid constructed in accordance with the present invention. Referring mainly to FIG. 1 and FIG. 2, the container lid, generally indicated by the number 2, is composed of a container lid body 4 and a liner member 6.

  A container lid body 4 that can be compression-molded or injection-molded from an appropriate synthetic resin such as polypropylene or rigid polyethylene includes a circular top wall 8 and a substantially cylindrical skirt wall 10 that hangs down from the periphery of the top wall 8. doing. A circumferential break line 12 is formed in the skirt wall 10, and the skirt wall 10 has a main portion 14 above the circumferential break line 12 and a tamper evidence skirt 16 below the circumferential break line 12. It is partitioned. The circumferential break line 12 includes a plurality of bridging portions 18 arranged at intervals in the circumferential direction. In regions other than the plurality of bridging portions 18, the main portion 14 of the skirt wall 10 and the tamper evidence skirt portion 16 are separated from each other by cutting. In other words, the tamper evidence skirt 16 is connected to the main portion 14 of the skirt wall 10 via a plurality of bridging portions 18. More specifically, an annular shoulder surface 20 facing downward is formed on the inner peripheral surface of the skirt wall 10 and is located slightly above the circumferential break line 12. A plurality of ridges 22 extending downward from the annular shoulder surface 20 are formed at intervals in the circumferential direction. The circumferential rupture line 12 is formed by cutting the skirt wall 10 from the outer peripheral surface of the skirt wall 10 leaving only the whole or a part of the ridge 22. A female thread 24 is formed on the inner peripheral surface of the main portion 10. The female thread 24 is formed with a notch 26 extending in the axial direction at intervals in the circumferential direction. The notch 26 forms a so-called air passage when the mouth and neck of the container is opened. An annular ridge 28 is formed on the top wall 8 so as to hang from the peripheral edge of the inner surface. An annular shoulder surface 30 facing downward is formed at the upper part of the inner peripheral surface of the tamper evidence skirt 16 (slightly below the lower end of the protrusion 22). A plurality of flap pieces 32 are formed at equal intervals in the circumferential direction on the inner peripheral surface of the tamper evidence skirt 16 below the annular shoulder surface 30. Each of the flap pieces 32 has a closed rotation direction of the container lid 2 when the container lid 2 is attached to the mouth-neck portion of the container from the base edge 34 connected to the inner peripheral surface of the tamper evidence skirt 16, that is, FIG. In FIG. 1 and FIG. 2, it protrudes inward in the radial direction inclining toward the opposite direction to the clockwise direction when viewed from above. Each base edge 34 itself of the flap piece 32 also inclines in the direction opposite to the closing rotation direction of the container lid 2 and extends downward. A thin curl 36 is attached to the lower end of the tamper evidence skirt 16 and extends in an arc toward the inside in the radial direction.

  The liner member 6 is disposed in a space defined by the inner surface of the top surface wall 8 of the container lid main body 4 and the annular protrusion 28 that hangs down from the peripheral edge of the inner surface. Such a liner member 6 can be conveniently formed by supplying a soft and molten synthetic resin material to the inner surface of the top wall 8 and compressing the synthetic resin material with a pressing tool. The synthetic resin material for the liner member 6 is preferably a relatively soft synthetic resin such as soft polyethylene.

  3 and 4 together with FIG. 1, the outer peripheral surface of the main portion 14 of the skirt wall 10 of the container lid body 4 is 2n in the circumferential direction, where n is a natural number of 2 or more. It is important that the area is partitioned. In the illustrated embodiment, the outer peripheral surface of the main portion 14 of the skirt wall 10 is divided into six regions, that is, three first regions 38 and three second regions 40. The regions 38 and the second regions 40 are alternately arranged. The three first regions 38 and the three second regions 40 have the same circumferential extension angle, and each extends over an angle range of 60 degrees. Each of the first regions 38 is formed with a plurality of protrusions 42 extending in the axial direction at an angle of α degrees. Conveniently, the cross section of each of the ridges 42 is substantially semicircular. In the illustrated embodiment, the angle α is 3 degrees, and 21 protrusions 42 are formed in the first region 38. On the other hand, each of the second regions 40 is formed with a plurality of protrusions 44a and 44b extending in the axial direction with an angular interval of 2α degrees. In the illustrated embodiment, the angle 2α is 6 degrees, and four protrusions 44a and five protrusions 44b are formed.

The second protrusion 44a and 44b are formed in the region 40 of, it is important that and a normal projection 44a and the low ridges 44b which are arranged alternately. The number of protrusions formed in the second region 40 is an odd number, and the protrusions located on both sides in the circumferential direction, that is, the protrusions adjacent to the protrusions 42 formed in the first region 38 are low. It is important that the protrusion 44b. The protruding amount in the radial direction of the protrusion 42 formed in the first region 38 is x, and the protruding amount in the radial direction of the normal protrusion 44a formed in the second region 40 is also x. It is important that the protruding amount in the radial direction of the low protrusion 44b formed in the second region 40 is y smaller than x. It is preferable that x is about 0.3 mm and y is about 0.2 mm. On the other hand, it is preferable that the circumferential width w at the bases of the protrusions 42 and 44a and 44b on which the locking protrusions of the chuck described later are locked is substantially the same.

  The description will be continued with reference to FIG. 2. In FIG. 2, the mouth-neck portion of the container to which the container lid 2 is attached is also indicated by a two-dot chain line. The mouth / neck portion 46 of the container, which can be made of glass, synthetic resin, or metal, has a cylindrical shape as a whole, and has an external thread 48 and an annular locking jaw positioned below the external thread 48 on its outer peripheral surface. Part 50 is formed. After the container is filled with appropriate contents such as a soft drink, the container lid 2 is attached to the mouth-and-neck portion 46. At this time, the container lid 2 is fitted on the mouth-and-neck portion 46, and the container lid 2 is rotated in the closed rotation direction, that is, clockwise when viewed from above in FIG. 2, and thus the female thread 24 in the container lid body 4. Is screwed into the male thread 48 of the mouth-and-neck portion 46, and the container lid 2 is lowered in accordance with the rotation. The flap piece 32 formed on the tamper evidence skirt 16 of the container lid body 4 is elastically deformed and passes through the locking jaw portion 50 of the mouth-neck portion 46, and then is elastically restored. The locking jaw 50 is locked. When the container lid 2 is attached to the mouth / neck portion 46 as required, the peripheral edge of the liner member 6 is brought into close contact with the mouth / neck portion 46 of the container, thereby sealing the mouth / neck portion 46.

  When opening the mouth-neck portion 46 of the container, the container lid 2 is rotated in the opening rotation direction, that is, counterclockwise as viewed from above in FIG. Thus, the female thread 24 formed on the main portion 14 of the skirt wall 10 in the container lid body 4 is moved along the male thread 48 formed on the mouth / neck part 46 of the container. 2 is raised with rotation. However, since the flap piece 32 formed on the inner peripheral surface of the tamper evidence skirt portion 16 of the container lid body 4 is locked to the locking jaw portion 50 of the mouth-and-neck portion 46, Movement is prevented. Accordingly, a considerable stress is generated in the bridging portion 18 in the circumferential break line 12 disposed on the skirt wall 10, the bridging portion 18 is broken, and the tamper evidence skirt portion 16 is separated from the main portion 14. The Thereafter, the tamper evidence skirt portion 16 is left on the mouth and neck portion 46, and the other portion of the container lid 2 is lifted with rotation to be detached from the mouth and neck portion 46.

  FIG. 5 shows a chuck used in a container lid mounting device for mounting the container lid 2 on the mouth neck portion 46 of the container and sealing the mouth neck portion 46. The chuck generally indicated by numeral 52 includes an annular member 54. A through-opening 56 penetrating in the axial direction is formed at the center of the annular member 54, and the lower half of the through-opening 56 defines a container lid housing space 58 as will be clearly understood from the following description. . The through opening 56 has an introduction part 60, a center part 62, and an upper end part 64 located at the lowermost part thereof. The inner peripheral surface of the introduction portion 60 has a truncated cone shape whose radius gradually decreases upward, and the inclination angle θ1 is relatively large and about 45 degrees. The inner peripheral surface of the central portion 62 also has a truncated cone shape whose radius gradually decreases upward, and its inclination angle θ2 is relatively small and is about 3 to 5 degrees. The inner peripheral surface of the upper end portion 64 has a cylindrical shape. A substantially lower half portion of the inner peripheral surface of the central portion 62 forms a locking inner peripheral surface 66, and a number of locking protrusions 68 are formed on the locking inner peripheral surface 66 at equal angular intervals in the circumferential direction. Has been. The angle interval β between the adjacent locking protrusions 68 (FIGS. 9 and 10) is the protrusions 44a and 44b formed in the second region 40 in the main portion 14 of the skirt wall 10 of the container lid body 4. Is equal to or an integral multiple of 2α degrees. In the illustrated embodiment, β degrees is the same as 2α degrees and is 6 degrees. Conveniently, the cross-section of the locking protrusion 68 has a substantially arcuate shape on both sides in the circumferential direction and has a concave arc shape (see FIGS. 7 to 10).

  6 and FIG. 6, the annular groove 70 continuously extending in the circumferential direction is formed on the outer peripheral surface of the annular member 54 at a position corresponding to the lower end portion of the locking inner peripheral surface 66. Has been. And the hole 72 penetrated to radial direction from the bottom face (radial direction inner surface) of the annular groove 70 to the latching inner peripheral surface 66 is formed at equal intervals in the circumferential direction. In the illustrated embodiment, six holes 72 are formed at an angular interval of 60 degrees. The radially inner end of each of the holes 72 has a truncated cone shape in which the radius gradually decreases inward in the radial direction. A sphere 74 is accommodated in each of the holes 72. The diameter of the sphere 74 is substantially the same as the diameter of the main part of the hole 72 and is larger than the diameter of the frustoconical tip of the hole 72, so that the sphere 74 can move in the hole 72 in the radial direction. Movement inward in the radial direction is limited to a predetermined position. The central axis of the hole 72 is aligned with the circumferential center of the locking protrusion 68, and therefore the radially innermost point of the ball 74 is also aligned with the circumferential center of the locking protrusion 68. The chuck 52 is also provided with elastic biasing means 76 for elastically biasing the sphere 74 accommodated in the hole 72 radially inward. In the illustrated embodiment, the elastic biasing means 76 is composed of a synthetic rubber ring accommodated in the annular groove 70. The elastic biasing means 76 elastically biases the sphere 74 to an innermost position (a position indicated by a two-dot chain line in FIG. 5), a part of which protrudes into the container lid housing space 58.

  When the container lid 2 is attached to the mouth-and-neck portion 46 (FIG. 2) of the container, for example, the chuck 52 is lowered with respect to the container lid 2 disposed at a predetermined position, as clearly shown in FIG. A substantial portion of the container lid 2, that is, a portion slightly above the portion above the circumferential break line 12 (FIGS. 1 and 2) is accommodated in the container lid accommodating space 58 of the chuck 52. At this time, the container lid 2 is positioned concentrically with respect to the chuck 52 by the guiding action of the introduction portion 60 having a frustoconical inner peripheral surface. When the container lid 2 is gradually advanced into the container lid housing space 58 in accordance with the lowering of the chuck 52, the plurality of balls 74 disposed at the lower end portion of the locking inner peripheral surface 66 are formed on the elastic biasing means 76. It is displaced radially outward against the biasing action. The container lid 2 is caused to enter the container lid housing space 58 up to the housing position indicated by a two-dot chain line in FIG. 5, and a plurality of balls 74 are elastically applied to the outer peripheral surface of the main portion 14 of the skirt wall 10 of the container lid body 4. Is elastically held in the accommodation position shown in FIG. The container lid 2 held by the chuck 52 is moved together with the chuck 52 so as to be fitted on the mouth neck portion 46 (FIG. 2) of the container, and is rotated together with the chuck 52 to be attached to the mouth neck portion 46.

  When the container lid 2 is caused to enter the container lid housing space 58 of the chuck 52, it is formed in the second region 40 in the main portion 14 of the skirt wall 10 of the container lid body 4 as shown in FIG. The container lid 2 is slightly centered about the central axis relative to the annular member 54 due to the mutual interference between the radial tips of the protruding ridges 44a and 44b and the protruding surface of the sphere 74 disposed on the chuck 52. Rotated, some of the spheres 74 are located between adjacent ridges 44a and 44b. However, in the container lid 2 configured according to the present invention, one of the two adjacent ridges 44a and 44b is a normal ridge 44a having a radial protrusion amount x, and the other is a radial protrusion. Since the amount of the low protrusion 44b is y which is smaller than x, the ball 74 is not positioned between the normal protrusion 44a and the low protrusion 44b, but is displaced slightly toward the low protrusion 44b. Each of the locking ridges 68 formed on the locking inner peripheral surface 66 is not a center in the circumferential direction between the normal ridge 44a and the low ridge 44b, as shown in FIG. It is positioned at a position slightly displaced from the center of the direction. On the other hand, with respect to the first region 38 in the main portion 14 of the skirt wall 10 of the container lid main body 4, as shown in FIG. 8, the sphere 74 has a protrusion whose innermost point is formed in the first region 38. Each of the locking ridges 68 is positioned so as not to face the circumferential center of the ridge 42 as shown in FIG. It is positioned at a position slightly displaced in the circumferential direction from the center in the circumferential direction. Therefore, it is avoided as much as possible that the locking protrusion 68 interferes excessively with the protrusion 42 and damages the protrusion 42. When the chuck 52 is rotated in the closing direction in order to rotate the container lid 2 fitted to the mouth / neck portion 46 of the container in the closing direction, the chuck 52 is slightly rotated with respect to the container lid 2, and the engagement of the chuck 52. The stop protrusion 68 engages with the protrusion 42 of the container lid 2 and the one side edge of the base of the protrusions 44a and 44b, and thereafter, the protrusion 42 of the container lid 2 and the protrusion 42 from the locking protrusion 68 of the chuck 52. Rotational torque is transmitted to 44a and 44b, and the container lid 2 is rotated together with the chuck 52.

However, in the container lid disclosed in Patent Document 1, all the protrusions formed in the second region of the main part of the skirt wall of the container lid body have the same cross-sectional shape and the same radial direction. It has a protruding amount x. Therefore, as shown in FIG. 11, when the container lid is advanced into the container lid receiving space of the chuck, some of the chuck balls are formed in the second region in the main part of the skirt wall. Each of the locking ridges 168 positioned on the circumferential center of the adjacent two protruding ridges 144 and formed on the locking inner peripheral surface 166 is also the circumferential direction of the two adjacent protruding ridges 144. Located in the center. On the other hand, with respect to the first region in the main part of the skirt wall of the container lid main body, as shown in FIG. 12, the sphere is centered in the circumferential direction of the protrusion 142 whose innermost point is formed in the first region. It is allowed positioned pairs countercurrent, and each of the locking projections 168 are brought located opposite the circumferential center of the ridge 142. Therefore, the locking protrusion 168 excessively interferes with the protrusion 142 and damages the protrusion 142, and in some cases, the container lid may be inclined with respect to the chuck.

The front view which shows suitable embodiment of the container lid comprised according to this invention. The front view which shows the container lid shown in FIG. The top view of the container lid shown in FIG. The fragmentary sectional view which shows the cross-sectional shape of protrusion in the container lid shown in FIG. Sectional drawing which shows the chuck | zipper used for the container lid mounting apparatus for mounting | wearing the container neck shown in FIG. 1 with the mouth neck part of a container. Sectional drawing which shows the chuck | zipper shown in FIG. 5 and the container lid shown in FIG. 1 accommodated in the container lid accommodation space. The partial expanded sectional view which shows the relationship between the 2nd area | region in the main part of the skirt wall of a container lid main body, and the ball | bowl of a chuck | zipper. The partial expanded sectional view which shows the relationship between the 1st area | region in the main part of the skirt wall of a container lid main body, and the ball | bowl of a chuck | zipper. The partial expanded sectional view which shows the relationship between the 2nd area | region in the main part of the skirt wall of a container lid main body, and the latching protrusion of a chuck | zipper. The partial expanded sectional view which shows the relationship between the 1st area | region in the main part of the skirt wall of a container lid main body, and the latching protrusion of a chuck | zipper. The partial expanded sectional view which shows the relationship between the 2nd area | region in the main part of the skirt wall of a container lid main body, and the latching protrusion of a chuck | zipper in the case of the conventional container lid. The partial expanded sectional view which shows the relationship between the 1st area | region in the main part of the skirt wall of a container lid main body, and the latching protrusion of a chuck | zipper in the case of the conventional container lid.

Explanation of symbols

2: Container lid 4: Container lid body 6: Liner member 8: Top wall 10: Skirt wall 12: Circumferential break line 14: Main part of skirt wall 16: Tamper-proof hem 24: Female thread 38: First Region 40: Second region 42: Projection strip 44a: Normal projection 44b: Low projection 46: Container neck and neck 48: Male thread 52: Chuck 54: Ring member 58: Container lid housing space 66: Locking Inner peripheral surface 68: Locking protrusion 74: Ball 76: Elastic biasing means

Claims (3)

A circular top wall and a cylindrical skirt wall depending from the peripheral edge of the top wall, and female threads are formed on the inner peripheral surface of the skirt wall, and the outer peripheral surface of the skirt wall is 2n in the circumferential direction, n is divided into regions of natural numbers of 2 or more, and the first region and the second region are alternately present, and the first region extends in the axial direction with an angular interval of α degrees. In the synthetic resin container lid in which a number of ridges are formed, and in the second region, a number of ridges are formed extending in the axial direction with an angular interval of 2α degrees.
The protrusion formed in the first region has a radial protrusion amount x, the odd number of protrusions are formed in the second region, and the protrusion is formed in the second region. The projecting ridge includes normal projecting ridges and low projecting ridges alternately arranged, and the projecting ridges located on both sides in the circumferential direction are the low projecting ridges, and the projecting amount in the radial direction of the normal projecting ridge is x. A synthetic resin container lid, wherein the protruding amount in the radial direction of the low protrusion is y smaller than x. The n is 3, and there are three first regions and three second regions on the outer peripheral surface of the skirt wall, and the extension angle of each of the first regions and each of the extending angle of said second region are all 60 degrees, according to claim 1 Symbol placement plastic container closure of. The synthetic resin container lid according to claim 1 or 2 , wherein the α degree is 3 degrees, the x is 0.3 mm, and the y is 0.2 mm.