NZ209283A

NZ209283A - Closure with integral sealing fin

Info

Publication number: NZ209283A
Application number: NZ20928384A
Authority: NZ
Inventors: J F Herbert; J H Guest; P R Hainea
Original assignee: Metal Closures Ltd
Priority date: 1983-08-26
Filing date: 1984-08-20
Publication date: 1988-02-12
Also published as: PT79135A; ZA846487B; GB8323037D0; PT79135B; JPS6068256A

Description

209283 Priority D 3te(s): ...?&> Complete Specification Filed: Class: feCa*DOfr+-l /OU* Publication Dale: P.O. Journal, Mq: fo&5003!/ co.. 12 ft'6'tS88" ,'5P.S4r 20AU6i Patents Form No. 5 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION 'IMPROVEMENTS RELATING TO CONTAINER CLOSURES" ✓J", WE METAL CLOSURES LIMITED, a British Company, of Bromford Lane, West Midlands B70 7HY, England, hereby declare the invention, for which 5Ywe pray that patent may be granted to me/us, and the method by which it is to be performed, to be particularly described in and by the followina statement:- ,, „ (followed by page I A.) f? FBS/4928 209283 IMPROVEMENTS RELATING TO CONTAINER CLOSURES This invention relates to container closures- According to this invention there is provided a container closure moulded in one piece from a plastics material and comprising a top, a dependent skirt the radially inner surface of which is formed with a screw-thread, a surface which is flared in a direction away from the top being formed on the internal surface of the skirt where it joins the top, and an annular resiliently flexible fin extending from the underside of the top at a position spaced radially inwardly of said flared surface, said fin having a main body which has an increasing diameter in a direction away from the top and having a free end portion which is thicker than said main body, said fin having a length such as to permit, when the closure is securely engaged on a container, at least its portion adjoining its free end portion to lie against said flared surface when the fin is deformed outwardly by the top of the neck of the container to which the closure is applied and to permit its free end portion to extend round the outer portion of said neck.

The free end portion may be thus thickened by reason of the provision of a peripheral rib formed locally on either the radially inner surface or the radially outer surface of said free end portion. The thickening of the free end portion serves to reduce the tensile stress in the fin when the closure is applied and in consequence to reduce the degree of extension of the free end portion of the fin so that a greater part of the length of the fin tends to hug the outer corner portion of the neck more closely and thus improves the seal. Where for this purpose a peripheral rib is formed on the radially inner surface of the fin, the rib may itself form with the neck of the container an additional line seal about the neck. Similarly where the rib is on the radially outer surface of the fin, the rXoC\1%'i. flared surface may engage the rib and press the free end portion of the fin towards the neck of the container.

In preferred arrangements said flared surface is frusto-conical. The flared surface may for example be inclined at 30° to the central axis of the closure. The fin may conveniently also be frusto-conical and may extend parallel to said flared surface.

The radially inner surface of the fin may have a plurality of annular grooves formed therein, each pair of adjacent grooves defining between them an annular rib of triangular cross-section. The grooves may be triangular and of buttress section, and the buttress face of the groove may face towards or away from the top to form a rib or ribs suitable for use with containers for materials under vacuum or under pressure, or may be of other triangular shape such as isosceles or equilateral triangular shape to form a rib or ribs of other required cross-sectional shape.

Some embodiments of the invention will now be described in more detail with reference to the accompanying drawings in which: Figures 1 and 2 are fragmentary sectional elevations illustrating a form of closure according to the invention in place on a container, and Figures 3 and M are corresponding views of a second form of closure according to the invention.

Referring first to Figures 1 and 2, the closure is moulded in one piece from a resilient plastics material and has a top 11 and a dependent skirt 12 formed with an internal screw-thread 13 and external knurling. The corner region 15 at the upper end of the skirt is thickened and has a conically flared internal surface 16 extending at an angle of 30° to the central axis of the closure. Spaced radially inwardl.y__.pf_ the surface 16 is a flexible resilient annular fin 1J3 extending from the underside of the top and 209283 substantially parallel to the surface 16.

The fin 18 has a main body of uniform thickness but has its free end portion thickened by reason of the formation of a broad flat-topped rib 30 on the radially inner surface of the end portion.

When the closure is applied to the neck 20 of a container the top 21 of the neck of the container deforms the fin 18 upward and the fin lies across and against at least the radially outer portions of the top 21 of the container neck and has a sufficient length in contact with the surface 16 to be pressed thereby against the outer corner portion 22 of the neck to form a top and corner seal . The axial length of the surface 15 and the length of the fin are also such that this sealing engagement takes place when the diameter of the container neck is on the upper limit of its tolerance as shown in Figure 2 or on the lower limit of its tolerance as shown in Figure 1.Figure 2 also shows the sealing fin in its unstressed condition extending parallel to the flared surface 16. The rib 30 serves to strengthen the free end portion of the fin so that the diametral strain in that portion, due to the outward flexing of the fin by the top and outer corner parts of the neck, is less than if the rib were absent, and in consequence the end portion of the fin tends to lie closer to the neck even when, as in Figure 1, it is not constrained by the surface 16 to do so.

The construction shown in Figures 3 and 4 is similar to that in Figures 1 and 2, but in Figures 3 and 4 the thickening of the free end portion of the fin is achieved by forming a rib 31 having a curved profile on the radially outer surface of the fin 18. Figures 3 and 4 show the closure applied to container necks on the lower and higher limits respectively of the diametral tolerance. As in the construction of Figures 1 and 2 tfie thickening of the free end portion of the fin 209283 strengthens it locally and causes it to be stretched to a lesser extent, but the surface 16 engages the rib 31 and presses the free end portion of the fin radially inward so as further to improve the seal.

The fin may have a thickness of the order of 0 .63mm (.025").

The closures shown in Figures 1 to 4 may additionally have grooves on the radially inner faces of the main bodies of the fins, the ribs formed between said grooves improving the sealing engagement between the fin and the container. The grooves may be triangular and of buttress section or of any other suitable section.

The closures may thus be designed for use with ^ either glass or plastic containers which are intended to contain still or carbonated liquids or materials under partial vacuum.

" 'V o\ " 1 0 NOV 1987 «|T // 209283

Claims

CLAIMS 10 15 20 WU<=a VsJe. Clai »^y-> Is *

1. A container closure moulded in one piece from a plastics material and comprising a top, a dependent skirt the radially inner surface of which is formed 5 with a screw-thread, a surface which is flared in a direction away from the top being formed on the internal surface of the skirt where it joins the top, and an annular resiliently flexible fin extending from the underside of the top at a position spaced radially inwardly of said flared surface, said fin having a main body which has an increasing diameter in a direction away from the top and having a free end portion which is thicker than said main body, said fin having a length such as to permit, when the closure is securely engaged on a container, at least its portion adjoining its free end portion to lie against said flared surface when the fin is deformed outwardly by the top of the neck of the container to which the closure is applied and to permit its free end portion to extend round the outer corner portion of said neck.

2. A closure as claimed in claim 1, wherein the free end portion is thickened by reason of the provision of a peripheral rib formed locally on the radially outer surface of said free end portion.

3. A closure as claimed in claim 1, or claim 2 wherein said flared surface is frusto-conical.

4. A closure as claimed in claim 3, wherein said flared surface extends at an angle of 30° to the central axis of the closure.

5. A closure as claimed in any one of claims 1 to 4, wherein the fin is of frusto-conical form.

6. A closure as claimed in claim 5 in conjunction with claim 3 or claim 4, wherein the fin extends parallel to the flared surface. 35 E _ ' o\ I, 1 0 NOV 1987£; V V' 25 30 V - 6 - 209283

7. A closure as claimed in any one of the preceding claims, wherein the main body of the fin is of substantially uniform thickness.

8. A closure as claimed in any one of claims 1 to 6 wherein the radially inner surface of the main body of the fin has a plurality of annular grooves therein, each pair of adjacent grooves defining between them an annular rib of triangular cross-section.

9. A container closure substantially as hereinbefore described with reference to the accompanying drawings. METAL CLOSURES LIMITED 15 By theiay^Attorneys^ ALDMX^g-QN & CAREY 20 25 30 35 E 'V f/f x %' . I 7 0NOV/9S7.; vtsy