WO2001087725A1

WO2001087725A1 - Synthetic resin cap, and method and device for manufacturing the synthetic resin cap

Info

Publication number: WO2001087725A1
Application number: PCT/JP2001/004008
Authority: WO
Inventors: Kazuyuki Yamada
Original assignee: Alcoa Closure Systems Japan, Limited
Priority date: 2000-05-18
Filing date: 2001-05-15
Publication date: 2001-11-22
Also published as: JP2001328653A; KR20030015244A; CN1429168A; AU2001256730A1; TWI250122B

Abstract

A synthetic resin cap, comprising a top plate part and a tube part suspended from the peripheral edge of the top plate part, wherein an annular inside seal part is formed projectedly on the inside top surface of the top plate part, and a thin-walled part thinned more than the other portions is formed near the base end part of the inside seal part.

Description

Description Synthetic resin cap, method and apparatus for manufacturing the cap

The present invention relates to a synthetic resin cap for closing a container mouth, and a method and an apparatus for manufacturing a synthetic resin cap.

This application is based on a patent application to Japan (Japanese Patent Application No. 2000-141), and the contents of the Japanese application are incorporated as a part of this specification. O:

Fig. 12 shows an example of a conventional synthetic resin cap. The synthetic resin cap 51 of the closing device exemplified here is composed of a top plate part 32 and a cylindrical part 33 hanging down from the periphery thereof. The tubular portion 33 has a horizontal score 36, an upper main portion 38, and a TE ring portion 39 connected to a lower end of the main portion 38 by a number of narrow bridges 37. Is divided into

On the inner wall surface of the main part 38, a screw part 40 to be screwed with the male screw of the container mouth is formed. On the inner wall surface of the TE ring portion 39, there are provided a plurality of thin tabs 41 which are locked to the container when the cap 51 is opened to prevent the movement of the TE ring portion 39.o

On the inner top surface of the top plate portion 32, an annular inner seal portion 54 that is fitted into the container mouth when the cap 51 is attached to the container mouth is formed so as to protrude.

The inner seal portion 54 is formed such that when fitted into the container mouth, the outer periphery thereof abuts on the inner wall surface of the container mouth without any gap.

It is difficult to keep the thickness and shape of the mouth constant for containers equipped with the above synthetic resin caps, especially containers made of synthetic resin such as polyethylene terephthalate, and the dimensions may vary from container to container. .

In such a case, the pressing force of the inner seal portion against the inner surface of the container mouth is locally In some cases, the opening torque became too high, and a gap was easily formed between the inner seal portion and the container mouth, resulting in a decrease in sealing performance. Disclosure of the invention

The present invention has been made in view of the above circumstances, and the objects thereof are as follows.

(1) To provide a cap made of a synthetic resin capable of setting the opening torque to a desired value even when the dimensions of the container vary, and a method and an apparatus for manufacturing the cap.

(2) To provide a synthetic resin cap having excellent sealing performance, and a method and an apparatus for manufacturing the cap.

The synthetic resin cap of the present invention includes a top plate portion and a tubular portion hanging down from a peripheral edge thereof, and an annular inner seal portion to be fitted into the container opening is formed on the inner top surface of the top plate portion to protrude. A thin portion, which is thinner than other portions, is formed near the base end of the inner seal portion.

In this synthetic resin cap, the bending stiffness of the inner seal portion of the thin portion can be set low, and the inner seal portion can have sufficient flexibility.

For this reason, when the cap is attached to the container mouth, the inner seal portion is bent and deformed to have a shape corresponding to the inner surface shape of the container mouth, and abuts the inner surface of the container mouth with a constant pressing force in the circumferential direction. Become like

Therefore, even when the dimensions such as the inner diameter of the container mouth portion vary, the opening torque can be set to a desired value and the sealing performance can be improved.

The thin portion can be formed by a weakened recess formed on the outer periphery of the inner seal portion.

A method of manufacturing a synthetic resin cap according to the present invention includes a top plate portion and a tubular portion hanging down from a periphery of the top plate portion, an annular inner seal portion protruding from an inner top surface of the top plate portion, and a base of the inner seal portion. In the vicinity of the end, a synthetic resin cap having a thinner portion formed to be thinner than other portions is formed by using an inner mold having an inner surface shape corresponding to the inner surface shape of the cap and an outer surface shape of the cap. A method of manufacturing using an outer-side mold having a shape, wherein the inner-side mold includes an inner-side mold body having a shape conforming to the inner surface shape of the inner seal portion; An outer cylinder member having a shape conforming to the outer shape of the seal portion, wherein the outer cylinder member and the inner mold body are relatively movable along the projecting direction of the inner seal portion, After filling the gap between the inner mold and the outer mold with a synthetic resin material, molding, and then pulling out the inner mold from the molded cap, the outer cylinder member and the inner mold body are moved inside the mold. After the projecting end of the seal portion is arranged at a position where it can be moved inward, the inner mold is pulled out.

In the drawing process, the vicinity of the tip of the inner seal portion moves inward, and the outer diameter of the inner seal portion becomes smaller, so that the inner surface mold can be smoothly placed without applying excessive force to the inner seal portion. Withdrawal can be performed.

Therefore, it prevents the formation of abnormal projections such as burrs in the inner seal part, damage such as cracks, elongation deformation, breakage, etc., and deformation and breakage of the inner seal part causes the inner seal part It is possible to prevent the pressing force from being locally excessive and to prevent a gap from being formed between the inner seal portion and the inner surface of the container opening, to set the opening torque to a desired value, and to improve the sealing performance.

The synthetic resin cap device of the present invention includes a top plate portion and a cylindrical portion hanging down from a periphery of the top plate portion. An annular inner seal portion is formed to project from an inner top surface of the top plate portion, and a base of the inner seal portion is provided. A synthetic resin cap manufacturing device for manufacturing a synthetic resin cap having a thinner portion formed thinner than other portions in the vicinity of an end portion, the inner surface having a shape conforming to the inner shape of the cap. A mold, and an outer mold having a shape conforming to the outer shape of the cap, wherein the inner mold has an inner mold body having a shape conforming to the inner shape of the inner seal portion; An outer cylinder member having a shape conforming to the outer surface shape is provided, and the outer cylinder member and the inner surface mold body are relatively movable along a projecting direction of the inner seal portion. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view showing an embodiment of the synthetic resin cap of the present invention. FIG. 2 is an enlarged view of a main part of the synthetic resin cap shown in FIG.

FIG. 3 is a sectional view showing an embodiment of the apparatus for manufacturing a synthetic resin cap of the present invention. FIG. 4 is an explanatory diagram showing the operation of the manufacturing apparatus shown in FIG.

FIG. 5 is an explanatory diagram showing the operation of the manufacturing apparatus shown in FIG.

FIG. 6 is an explanatory diagram showing the operation of the manufacturing apparatus shown in FIG.

FIG. 7 is an explanatory diagram showing the operation of the manufacturing apparatus shown in FIG.

FIG. 8 is an explanatory diagram showing the operation of the manufacturing apparatus shown in FIG.

FIG. 9 is an enlarged view of a main part showing another example of the synthetic resin cap of the present invention. FIG. 10 is an enlarged view of a main part showing another example of the synthetic resin cap of the present invention. FIG. 11 is an enlarged view of a main part showing another example of the synthetic resin cap of the present invention. FIG. 12 is a sectional view showing an example of a conventional synthetic resin cap. BEST MODE FOR CARRYING OUT THE INVENTION

FIGS. 1 and 2 show an example of the synthetic resin cap of the present invention. The cap 31 shown here is of a type called a one-piece cap, and has a disk-shaped top plate portion 32 and a peripheral portion thereof. And a cylindrical portion 33 suspended from the cylinder.

The cylindrical portion 33 has a horizontal score 36, an upper main portion 38, and a tamper evidence ring portion (TE ring portion) 3 connected to the lower end of the main portion 38 by a number of thin bridges 37. It is divided into nine.

A screw portion 40 is formed on the inner peripheral wall surface of the main portion 38. On the inner wall surface of the TE ring portion 39, a large number of tabs 41 projecting inward and protruding and undulating are provided along the circumferential direction.

On the inner top surface of the top plate portion 32, an annular inner seal portion 34 fitted into the container mouth when the cap 31 is attached to the container mouth is formed so as to protrude substantially vertically downward. I have.

The protruding length of the inner seal portion 34, that is, the protruding length A shown in FIG. 2, is 2.5 to 5.5 mm (preferably 3 to 5 mm, more preferably 3.5 to 4.5 mm). It is preferable to do so. If the protruding length A is less than the above range, the container is quickly unsealed when the cap is opened, and the tamper-evident property is reduced.

If the protruding length A exceeds the above range, it becomes difficult for the inner seal portion 34 to fit into the container mouth when the cap is attached. In the synthetic resin cap of the present embodiment, the weakened concave portion 34 a is formed on the entire outer periphery near the base end of the inner seal portion 34, and the weakened concave portion 34 a is formed by force. The inner seal portion 34 of the first portion is a thin portion 35 that is thinner than the other portions.

The weakened concave portion 34a is for forming a thin portion 35 that enhances the flexibility of the inner seal portion 3, and is formed along an upper edge portion 34d having an inwardly curved cross-sectional shape and along the vertical direction. It has a bottom portion 34e and a lower edge portion 34f having a cross-sectional shape protruding outward. The weakened concave portion 34a has a maximum inclination angle of the outer surface of the lower edge portion 34f with respect to the vertical direction, that is, a maximum inclination angle B shown in FIG. 2 of 9 Q degrees or less (preferably 60 degrees or less, more preferably Or less than 30 degrees).

If the maximum inclination angle B exceeds the above range, the lower edge portion 34f is easily locked to the cap forming die during cap molding, and the inner seal portion 3 is likely to be deformed or broken.

The depth of the weakened concave portion 34a, that is, the depth C shown in 园 2, is 0.1 to 2 mm (preferably 0.3 to 1.5 mm, more preferably 0.5 to L;). I prefer to do that.

If the depth C is less than the above range, the flexibility of the inner seal portion 34 in the thin portion 35 is reduced, and the opening torque of the cap 31 may be increased. In addition, the sealing performance of the cap 31 may be reduced.

If the depth C exceeds the above range, the strength of the inner seal portion 34 at the thin portion 35 becomes insufficient, and the inner seal portion 34 when the inner seal portion 34 is fitted into the container opening is formed. Deformation (buckling deformation, etc.) tends to cause a decrease in sealing performance. The thickness of the thin portion 35, that is, the thickness D shown in FIG. 2, should be 1 to 2.2 mm (preferably 1.2 to 2 mm, more preferably 1.4 to 1.8 mm). When the thickness D is less than the above range, the strength of the inner seal portion 34 in the thin portion 35 becomes insufficient, and the inner seal portion 34 when the inner seal portion 34 is fitted into the container mouth is provided. Deformation (buckling deformation, etc.) tends to cause a decrease in sealing performance. When the thickness D exceeds the above range, the inner seal portion 34 in the thin portion 35 can be used. The flexibility may be reduced, which may cause an increase in the opening torque of the cap 31. Also, the sealing performance of the cap 31 may be reduced.

The width of the weakened recess 34a, that is, the width E shown in FIG. 2, should be 0.5 to 2.5 mm (preferably 0.8 to 2 mm, more preferably 1 to 1.5 mm). If the width E is less than the above range, the flexibility of the inner seal portion 34 in the thin portion 35 is reduced, and the opening torque of the cap 31 is increased. In addition, the sealing property of the cap 31 may be reduced.

If the width E exceeds the above range, the strength of the inner seal portion 34 at the thin portion 35 becomes insufficient, and the inner seal portion 34 is deformed when the inner seal portion 34 is fitted into the container mouth. (Such as buckling deformation) is likely to cause a decrease in sealing performance. Due to the formation of the weakened concave portion 34a, the lower portion of the inner seal portion 34 protrudes outward from the vicinity of the base end portion, and becomes a contact convex portion 34b which comes into contact with the inner wall of the container opening when the cap is attached.

The inner seal portion 34 is preferably formed such that the contact convex portion 34b has a substantially arc-shaped cross-sectional shape from the viewpoint of sealing properties.

Further, it is preferable that the maximum outer diameter of the inner seal portion 34 be set to be substantially equal to or slightly larger than the inner diameter of the container mouth to which the cap 31 is to be mounted. A ring-shaped outer seal portion 42 protruding downward is formed on the top plate portion 32 slightly outside the inner seal portion 34. The outer seal portion 42 is formed so as to contact the outer peripheral surface of the container mouth when the cap is mounted.

Suitable materials for the cap 31 are polypropylene and high-density polyethylene.

Next, a method and an apparatus for manufacturing the cap 31 will be described.

FIG. 3 is a cross-sectional view showing an embodiment of the synthetic resin cap manufacturing apparatus according to the present invention. The manufacturing apparatus 1 shown here has an annular inner seal portion 34 on an inner top surface of a top plate 32. This is a manufacturing device configured to manufacture a cap 31 having a protruding portion, and an inner mold 2 forming the inner surface of the cap 31 and an outer surface of the cap 31 are formed. The outer mold 3 to be formed and the end mold 4 forming the end of the cap 3 1 It has.

The outer mold side is formed in a bottomed cylindrical shape having an inner surface shape corresponding to the outer shape of the cap 31.

The inner mold 2 includes an inner mold body 5 and an outer cylinder member 6 provided on the outer periphery of the body 5.

The inner surface mold body 5 includes a shaft 8 and a cylindrical head portion 9 provided at a tip of the shaft 8 (a lower end in FIG. 3).

The head portion 9 is formed so as to have an outer diameter larger than that of the shaft 8, and has an outer shape conforming to the shape of the inner surface of the inner seal portion 34 of the cap 31.

The outer cylinder member 6 is formed in a cylindrical shape having an outer surface shape corresponding to the inner surface shape of the outer portion of the inner seal portion 34 of the top plate portion 32 and the cylindrical portion 33. A shaft passage portion 10 through which the air flows and a head portion housing portion 11 in which the head portion 9 is housed are formed.

The head housing 11 is formed such that its axial (vertical) length is longer than the axial length of the head 9, and the inner surface near the lower end thereof has An inner seal portion forming notch 12 having an inner surface shape conforming to the outer surface shape of the inner seal portion 34 is formed over the entire circumference.

On the lower inner wall of the inner seal portion forming notch 12, a weakened concave portion forming convex portion 12 a having a shape along the weakened concave portion 34 a is formed so as to protrude. Therefore, the weakened concave portion forming convex portion 12 a has an inner diameter smaller than the maximum outer diameter of the inner seal portion 34.

In the present embodiment, the outer cylinder member 6 and the inner mold body 5 are relatively movable in the axial direction (vertical direction in FIG. 3).

In the present embodiment, the outer cylinder member 6 can be moved vertically with respect to the inner mold body 5. In the present invention, the inner mold body 5 may be vertically movable with respect to the outer cylinder member 6.

Hereinafter, as shown by a solid line in FIG. 3, the outer cylinder member 6 is retracted (moved upward) with respect to the main body 5, the main body 5 is positioned relatively below, and the inner mold 2 and the outer mold are disposed. The position of the inner mold body 5 when the gap with the mold 3 conforms to the shape of the cap 31 is referred to as a “down position”. As shown by the two-dot chain line, the position of the inner mold body 5 when the outer cylinder member 6 is advanced (moved downward) with respect to the main body 5 is referred to as a “elevated position”.

When the inner mold body 5 is in the raised position, the outer periphery of the lower end of the head portion 9 is located near the tip of the inner seal portion 34, and when a radially inward force is applied to the inner seal portion 34. The inner seal portion 34 is designed so that the protruding end 34 c of the inner seal portion 34 can be moved inward by elastic deformation of the inner seal portion 34.

The end-side mold 4 is formed in a cylindrical shape, and the inside thereof is an outer cylinder member passage portion 13 through which the outer cylinder member 6 passes. The lower end of the end side mold 4 is shaped along the end of the TE ring portion 39 (the upper end in FIG. 3) and the tab 41.

The end mold 4 is movable in the axial direction (up and down direction) with respect to the inner mold 2.

The gap formed by the inner mold 2 (the inner mold body 5 is in the lower position), the outer mold 3 and the end mold 4 is formed by a cap 3 1 It is formed so as to form a molding space 14 conforming to the shape of.

Next, an embodiment of a method for manufacturing a synthetic resin cap of the present invention will be described with reference to FIGS. 3 to 8 as an example of a case where the cap 31 is manufactured using the manufacturing apparatus 1. FIG.

As shown in Fig. 3, the molding space 14 formed by the inner mold 2, outer mold 3, and end mold 4 is filled with a synthetic resin material (polypropylene, high-density polyethylene, etc.) and molded. I do. At this time, the relative position between the outer cylinder member 6 and the inner mold body 5 is determined so that the inner mold body 5 is located at a lower position.

The synthetic resin material filled in the gap between the inner seal portion forming notch 12 on the inner surface of the outer cylinder member 6 and the head portion 9 becomes the inner seal portion 34.

As a method for forming the cap 31, it is preferable to use compression molding.

Hereinafter, a process of removing the cap 31 from the inner mold 2 and the outer mold 3 will be described in detail.

First, as shown in FIGS. 4 and 5, the cap 31 is removed from the outer mold 3 and the outer cylinder member 6 of the inner mold 2 is sealed inside the inner mold body 5 with respect to the inner mold body 5. 3 Move the inner mold body 5 in the downward direction, which is the direction along the Place it in the raised position.

In this raised position, the outer periphery of the lower end of the head portion 9 is located near the upper end of the inner seal portion 34, and the protruding end 3c of the inner seal portion 34 can move radially inward. Becomes

In addition, the end side mold 4 is raised with respect to the inner side mold 2, and is separated from the TE ring portion 39 and the tab 41.

Next, as shown in FIG. 6, the entire inner mold 2 (the inner mold body 5 and the outer cylinder member 6) is moved upward with respect to the cap 31.

On the inner periphery of the inner seal portion forming notch 12, a weakened concave portion forming convex portion 12 a having an inner diameter smaller than the maximum outer diameter of the inner seal portion 34 is formed, so that the main body 5 and the outer cylinder are formed. When the member 6 is moved upward, an upward force is applied to the inner seal portion 34 (the lower edge 34 f of the weakened concave portion 34 a) by the weakened concave portion forming convex portion 12 a.

As shown in FIG. 7, at this time, due to the elastic deformation of the inner seal portion 34, the vicinity of the tip of the inner seal portion 34 moves inward, and the outer diameter of the inner seal portion 34 becomes smaller. It becomes smaller. Therefore, the weakened concave portion forming convex portion 12 a smoothly passes through the contact convex portion 34 b of the inner seal portion 34.

Therefore, the inner surface side mold 2 is pulled out without applying an excessive force to the inner seal portion 34 by the weakened concave portion forming convex portion 12a.

In this process, an upward force is applied to the tab 41 by the outer cylinder member 6. Since the end side mold 4 is separated from the TE ring part 39 and the tab 41, the tab 41 Are elastically deformed upward and folded. For this reason, the inner mold 2 is pulled out without applying an excessive force to the tab 41 by the outer cylinder member 6.

Through the above-described drawing process, the inner mold 2 is removed from the cap 31 as shown in FIG. 8 to obtain a completed cap 31.

The cap 31 is attached to the container mouth by covering the container mouth, turning in the closing direction, and screwing the screw portion 40 into a male screw of the container mouth. .

At this time, the inner seal portion 34 fits into the inside of the container mouth, the contact convex portion 34b abuts on the inner wall of the container mouth without any gap, and the container mouth is sealed. When opening the cap, turning the cap 31 in the opening direction prevents the TE ring section 39 from rising, while raising the main section 38 and moving the TE ring section 39 away from the main section 38. Cut the bridge 37 and pull out the inner seal 34 from the container opening to release the seal.

The cap 31 of the present embodiment includes a top plate portion 32 and a cylindrical portion 33 hanging down from the periphery thereof, and an annular inner seal portion 34 protrudes from the inner top surface of the top plate portion 32. Since the thin portion 35 is formed near the base end of the inner seal portion 34 and is thinner than the other portions, the bending rigidity of the inner seal portion 34 in this portion is set to be low. This allows the inner seal portion 34 to have sufficient flexibility.

For this reason, when the cap 31 is attached to the container mouth, the inner seal portion 34 is bent and deformed at the thin portion 35 so as to have a shape corresponding to the inner surface shape of the container mouth, and is substantially constant in the circumferential direction. The pressing force comes in contact with the inner surface of the container opening.

For example, when the container mouth is formed to be thinner in one part in the circumferential direction than in the other part, due to the bending deformation in the thin part 35, the vicinity of the tip of the inner seal part 34 becomes the thin part of the container mouth. Displace toward.

For this reason, the pressing force on the inner surface of the inner seal portion 34 in the thin portion becomes a sufficient value, and the pressing force on the portion other than the thin portion is kept low. The pressing force comes into contact with the inner surface of the container mouth.

Therefore, even if the dimensions such as the inner diameter of the container opening vary, the opening torque due to excessive pressing force of the inner seal portion 34 against the inner surface of the container opening is prevented from rising, and the opening torque is set to a desired value. Can be set to

In addition, it is possible to prevent the pressing force of the inner seal portion 34 against the inner surface of the container opening from becoming insufficient, improve the sealing performance of the inner seal portion 34 against the container opening, and improve the sealing performance of the cap 31. it can.

Further, since the thin portion 35 is formed by the weakened concave portion 34 a formed on the outer periphery of the inner seal portion 34, the lower portion (near the distal end portion) of the inner seal portion 34 is closer than the vicinity of the base end portion. The contact protrusion 34 b protruding outward can be used.

For this reason, when attaching the cap, the lower part of the inner seal part 34 (near the tip) The container opening can be sealed, delaying the release of the container when the cap is opened, and improving tamper evidence.

In the manufacturing method of the above embodiment, when the inner mold 2 is pulled out from the formed cap 31, the outer cylindrical member 6 and the inner mold body 5 are connected to the protruding end 3 4 c of the inner seal portion 34. After arranging it at a position where it can be moved inward, the inner mold 2 is removed with a cap 31.

In this drawing process, an upward force is applied to the inner seal portion 34 by the weakened concave portion forming convex portion 12 a formed in the notch 12. And the outer diameter of the inner seal portion 34 becomes smaller. For this reason, although the outer cylindrical member 6 is formed with the weakened concave portion forming convex portion 12 a having an inner diameter smaller than the maximum outer diameter of the inner seal portion 34, the inner seal portion 34 is excessively large. The inner mold 2 can be pulled out smoothly without applying excessive force.

Accordingly, it is possible to prevent the formation of abnormal projections such as burrs in the inner seal portion 34, breakage such as cracks, elongation deformation, breakage, and the like.

Therefore, it is possible to prevent the pressing force on the inner surface of the container opening of the inner seal portion 34 from being locally excessive due to the deformation of the inner seal portion 34 (for example, the formation of an abnormally protruding portion), and to reduce the opening torque. It can be set to a desired value.

Also, the dimensional accuracy of the inner seal part 34 is improved to prevent a gap between the inner seal part 34 and the inner surface of the container opening due to deformation or breakage (for example, crack) of the inner seal part 34. A cap 31 with excellent sealing performance can be obtained.

In the manufacturing apparatus 1 of the above embodiment, the inner mold 2 includes an inner mold body 5 having a head portion 9 having a shape corresponding to the inner shape of the inner seal portion 34, and an inner seal portion 34. An outer cylinder member 6 having an inner surface shape conforming to the outer surface shape of the outer cylinder member, and the outer cylinder member 6 and the inner surface side mold body 5 are arranged in a vertical direction which is a direction along a projection direction of the inner seal portion 34. Since the inner mold 2 is pulled out from the molded cap 3 1, the outer cylindrical member 6 and the inner mold body 5 are pulled out of the inner seal portion 3 4. The inner mold 2 can be pulled out from the cap 31 after the 4 · c is arranged at a position where it can be moved inward. As a result, the inner mold 2 can be smoothly pulled out without applying excessive force to the inner seal portion 34, and abnormal protrusions such as burrs in the inner seal portion 34, cracks, etc. Breakage, elongation deformation, breakage, etc. can be prevented. Therefore, due to the deformation or breakage of the inner seal portion 34, the pressing force of the inner seal portion 34 against the inner surface of the container opening becomes locally excessive, or the pressing force between the inner seal portion 34 and the inner surface of the container opening is changed. It is possible to prevent the formation of a gap in the opening, set the opening torque to a desired value, and enhance the sealing performance.

In the present invention, the weakened recess formed in the inner seal portion is not limited to the example, and for example, as shown by reference numeral 44a in FIG. 9, the inclination angle at the lower edge portion 44f is constant. It can be formed as follows.

Further, the weakened concave portion may be formed so as to have a substantially inwardly curved cross-sectional shape as shown by reference numeral 54a in FIG.

In the above embodiment, the weakened recess is formed only on the outer periphery of the inner seal portion. However, the present invention is not limited to this. In addition to the configuration of the cap 31, as shown in FIG. A weakened concave portion 64a may be formed on the inner periphery near the portion. In FIGS. 9 to 11, reference numerals 45, 55, and 65 indicate thin portions.

Further, in the present invention, the position where the weakened concave portion is formed may be only the inner periphery of the inner seal portion. Industrial applicability

The synthetic resin cap of the present invention includes a top plate portion and a tubular portion hanging down from a peripheral edge thereof, an annular inner seal portion protruding from an inner top surface of the top plate portion, and a base of the inner seal portion. A thin wall portion is formed near the end, which is thinner than the other portions, so that the bending rigidity of the inner seal portion of this portion can be set low, and sufficient for the inner seal portion It can have flexibility.

Therefore, even if the dimensions such as the inner diameter of the container mouth vary, the inner seal The pressing force against the inner surface of the container mouth can be prevented from being locally excessive, and the opening torque can be set to a desired value.

In addition, it is possible to prevent a gap from being formed between the inner seal portion and the inner surface of the container opening, and to enhance the sealing performance.

Further, in the method for manufacturing a synthetic resin cap of the present invention, in pulling out the inner mold from the molded cap, the outer cylindrical member and the inner mold body are oriented with the protruding end of the inner seal portion facing inward. Since the inner mold is pulled out of the cap after being placed at a position where it can be moved, the inner mold can be smoothly pulled out without applying excessive force to the inner seal portion.

Therefore, it is possible to prevent the formation of abnormal projections such as burrs in the inner seal portion, breakage such as cracks, elongation deformation, and breakage.

Therefore, due to the deformation or breakage of the inner seal, the pressing force of the inner seal against the inner surface of the container opening becomes locally excessive, or a gap is generated between the inner seal and the inner surface of the container opening. , The opening torque can be set to a desired value, and the sealing performance can be improved.

Claims

The scope of the claims

1. A top plate portion and a cylindrical portion hanging down from the periphery of the top plate portion. An annular inner seal portion to be fitted into the container mouth is formed on the inner top surface of the top plate portion so as to protrude therefrom. A synthetic resin cap, characterized in that a thin portion is formed in the vicinity, which is thinner than other portions.

2. The synthetic resin cap according to claim 1, wherein the thin portion is formed by a weakened recess formed on the outer periphery of the inner seal portion.

3. Includes a top plate and a tube hanging down from the periphery of the top plate. An annular inner seal protrudes from the inner top surface of the top plate, near the base end of the inner seal, and at other parts. A synthetic resin cap having a thinner portion is formed by using an inner mold having a shape conforming to the inner shape of the cap and an outer mold having a shape conforming to the outer shape of the cap. Manufacturing method,

The inner mold includes an inner mold body having a shape conforming to the inner shape of the inner seal portion, and an outer cylinder member having a shape conforming to the outer shape of the inner seal portion. The one that can be relatively moved with the side mold body along the projecting direction of the inner seal part,

After filling the gap between the inner mold and the outer mold with a synthetic resin material, molding, and then pulling out the inner mold from the molded cap, the outer cylinder member and the inner mold body are sealed with the inner seal. A method of manufacturing a cap made of synthetic resin, characterized in that, after arranging the protruding end of the portion at a position where it can move inward, the inner mold is pulled out.

4. Includes a top plate and a cylindrical portion that hangs down from the periphery of the top plate. An annular inner seal protrudes from the inner top surface of the top plate, near the base end of the inner seal, and at other parts. An apparatus for manufacturing a synthetic resin cap having a thinner portion formed therein, comprising: an inner mold having a shape conforming to the inner shape of the cap; and an outer surface having a shape conforming to the outer shape of the cap. With a side mold,

The inner mold includes an inner mold body having a shape conforming to the inner shape of the inner seal portion, and an outer cylinder member having a shape conforming to the outer shape of the inner seal portion. An apparatus for manufacturing a synthetic resin cap, wherein the outer cylinder member and the inner surface side mold body are relatively movable along a protruding direction of the inner seal portion.