NZ213702A - A composite metal-plastics closure: plastics portion bonded to metal portion by lacquer - Google Patents

Description

213702 , , >.i.Ch8£ 66300.3.102/, &£SDO£>/02 .f>.630UA|i >8 JAN 1988 F . I- .

P . \.V.

MEW ZEALAND PATENTS ACT. 195 J X/We. ACI AUSTRALIA LIMITED, a company incorporated in the State of Victoria, Australia, of Level 32, 200 Queen Street, Melbourne, Victoria 3000, Australia, hereby declare the invention for which X / we pray that a patent may be granted to jtxk/us, and the method by which it is to be performed, to be particularly described in and by the following statement:- 213702 This invention relates to improved method of forming composite metal/plastics closures, and includes closures formed by such methods.

Traditionally, closures for containers have generally been formed of metal or plastics, but in some cases metal and plastics components have been joined together after manufacture to form composite closures. With the growing need for more sophisticated closures, there has been a tendency to go over to composite metal/plastics closures which combine the 10 good points of both metal and plastics, to produce a superior product.

One of the disadvantages of composite metal/plastics closures is that the components have traditionally been manufactured separately and then joined in a subsequent joining operation. The procedure increases the overall cost of the closure because of the extra handling involved.

It is an object of the invention to provide a composite metal/plastics closure which does not require the manufacture of separate components which must be subsequently 20 assembled to form the complete closure.

The invention provides a closure comprising composite metal and plastics portions, wherein the metal portion is preformed and comprises a cup-shaped element which includes means to facilitate attachment thereto of the plastics portion, the facilitating means comprising a lacquer applied to sheet metal from which said metal portion is preformed, and wherein the plastics portion is directly moulded against a surface of the metal portion covered by the lacquer, said lacquer being one which is compatible with "'O plastics material from which said plastics portion is moulded and providing a direct bond with both the metal portion and the plastics portion.

The invention also provides a method of forming a closure, wherein a metal portion comprising a cup-shaped element is preformed from sheet material having a lacquer applied over at least one surface thereof, and a plastics portion is moulded against a surface of the metal portion covered by the lacquer, the lacquer being one compatible^ plastics material from which the plastics portion is moi FY -2- 313702 to provide means to facilitate attachment to the plastics portion to the metal portion by a direct bond between those portions.

The facilitating means may additionally consist of a mechanical key formed in the metal portion of the closure, which holds the plastics portion of the closure thereto when moulding has been completed. Examples of a suitable type of key may comprise knurling in the metal portion or roughened, undercut, recessed or slit portions in the metal 213702 portion, which facilitate mechanical attachment of the plastics material portion. portion has a top panel and a circumferential skirt depending from that panel; with the plastics portion of the closure comprising a tamper evident band which has been directly moulded onto the skirt of the cup shaped metal portion. In that aspect, a separate sealing ring preferably is separately or co-jointly moulded around the inner surface of the metal portion at the join between the skirt and the top panel portion of the cup shaped metal portion. plastics fin may be moulded on the underside of the top panel of the metal portion. Such sealing ring preferably has an abutment to limit movement of the fin when the cap is pressed down to seal against the rim of a container ; The abutment most preferably beina ioined to the fin by a web. In such a case both the sealing fin and the abutment have an annular configuration, the abutment being of wider diameter than the fin which is concentric therewith. applied to, and/or a mechanical key formed in, the metal portion facilitates attachment of the plastics portion to the metal portion. A lacquer preferably is used even when a mechanical key is provided, as this enables a more mechanically simple form of key to be used. The lacquer is required to be compatible with the plastics material to provide the plastics portion. Most preferably, the lacquer is one which chemically interacts with that material, such as by forming cross-links with the plastics material. Depending on the plastics material, suitable lacquers include PVC lacquers such as T-6985 available from Taubmans Pty. Ltd., and ethylene lacquers such as clear ethylene 8/9422/007 available from Mobil Oil Aust. Pty. Ltd. Most preferably a PVC lacquer is used where the plastics material to provide the plastics portion of the closure is PVC or a PVC blend; while an ethylene lacquer most preferably is~~trsed„where the plastics material is a polyolefin, such as polye ' In a preferred aspect of the invention, the metal Alternatively, a sealing ring comprising a resilient As indicated, facilitating means comprising a lacquer materials. polypropylene, or a polyolefin blend. However, othe can be used for compatibility with these and other p » • 213703 Preferred aspects of the invention will now be described with reference to the accompanying drawings, wherein Fig. 1 illustrates a fragmentary profile view of a section of a closure constructed in accordance with the invention; and Fig. 2 illustrates a fragmentary profile view of an alternative form of closure constructed in accordance with the invention.

Referring to Fig. 1 of the drawings, the closure generally designated 11 comprises a metal component 12 having a top panel 13 and a depending circumferential skirt 14.

Preferably the skirt is provided with a widened annular portion 15, joined to the bottom of the skirt by a shoulder 16 for purposes to become apparent.

The under surface of the metal portion 12 is coated with a lacquer which is compatible with a plastics material chosen to be moulded thereon in order to allow the lacquer and moulded plastics material to chemically interact to form a strong bond with the metal portion of the cap. Preferably the lacquer will have been applied to a flat sheet of metal which is ultimately pressed or stamped by conventional forming operations to produce the cup shaped configuration shown in Fig. 1.

Ideally, the stamping or pressing machinery for forming the cup shaped component 12 is arranged to feed successive metal components directly to a moulding machine, such as an injection moulding machine, in order to reduce handling. The moulding machine can then directly mould the plastics portion of the cap thereto.

In Fig. 1 the plastics portions comprise an annular sealing gasket 20, and a separate tamper evident band 21. Both plastic components may be moulding directly into the cap at the same time or separately, and depending upon the choice of a material used, the two plastics portions may be of the same or different material. Ideally a single material for the two plastics portions should be used, as this reduces the cCJmp^ic-ation of the manufacturing process. ~ As can be seen from the drawing, the sealing gas^^pOT^*^ is located at the region of joining between the circulatfAfcop FY - 5 - rJ 213702 panel 13 and the depending skirt 14 in order that a seal can be made with the top and/or side of the end finish of a container to which the closure will be applied.

The annular tamper evident band 21 comprises a joining portion 22 which is moulded in the recess formed by portion 15 of the metal cap, and is connected by an integral weakened portion 23 which may comprise a series of weak bridges annularly spaced around the bottom of the joining portion 22 to secure the break away section 24 of the tamper evident band thereto.

An annular barb 25, or other suitable means, is provided on section 24 to cause tearing or rupturing of section 24 from the cap portion as the latter is removed from a container on which closure 10 has been applied. In the illustrated embodiment, barb 25 may snap fit under an annular shoulder provided on the container to which the cap is applied in order to prevent removal of the breakaway section 24 from the container when the cap is removed from the container.

As will be appreciated, barb 25 is shown in its in use position to which it is moved in a secondary operation after manufacture of the closure. As formed, barb 25 projects axially away from component 12, beyond section 24, and is resiliently bent to its in use position by such operation, prior to application of the closure to the container.

An annular shoulder 26 may also be formed on the tear off closure in order to protect the fingers of a consumer from the raw metal edge provided by the bottom of the metal skirt portion.

Referring to Fig. 2, the fragmentary portion of the cap shown therein comprises a metal section 31 having a circular top panel 32 and a circumferentially depending skirt portion 33 all formed of metal. As in the case of the closure described in Fig. 1, the metal has had a compatible lacquer applied thereto in order to assist securement of moulded plastics portions thereto. In addition, mechanical keying means such as an annular raised portion 34 forming a recessed section in the underside of the top panel 31 may also be provided.*""^ A gasketting material may be applied directly to the lacquered underside of the metal top panel 32, preferabl recess similar to the annular recess defined by the rai£ted v." •I FY 6 213702 portion 34. The gasketting material may comprise a foamed injection moulded annular ring of material sitting in the recess, or alternatively a resilient plastics sealing member such as the sealing fin abutment combination 35 shown in Fig. 2.

The annular sealing fin 36 is concentric vfith an annular abutment 37, and is arranged in such a way that application of the closure 31 to a container forces the sealing fin onto the open ended rim of a container, thereby pushing the sealing fin up against the abutment 37 to form a seal both with the abutment and the container rim.

The closure of Fig. 2 is intended for roll-on secure-ment to a container, by skirt 33 being deformed by rollers after its application to a container, so as to threadedly engage with threads on the container neck. However, skirt 33 can be preformed so as to define threads, if required. In the closure of Figure 1, the portion of skirt 14 between gasket 20 and shoulder 16 can be preformed to define threads or thread portions for screw engagement of the closure onto a container neck. Alternatively, after application to the closure to a container, that portion of skirt 14 can be deformed so as to threadedly engage threads on the container neck.

It is to be appreciated that the invention is applicable to a wide variety of alternative forms of closures in addition to those illustrated. In one alternative form, the closure may have a metal component as in the closure of Figure 1, or of a simple cup-shaped form (i.e. as in Figure 1 but without widened portion 15). In that alternative the plastics component may comprise a plastics liner injected moulded against the inner surface of the skirt of the metal component and defining threads by which the closure can be applied to a container.

Such liner may be secured to the metal component of the closure solely by means of a lacquer applied over that surface of a metal blank to provide the inner surface of the metal component. Additionally, or alternatively, the liner may be mechanically keyed to the metal component, such as by axial ribs or corrugations formed in the skirt which also may provide knurled external surface for the closure. The liner maj^extend Q across the junction of the skirt and top panel of the metal FY _ 7 - vejo* 213702 component so that its portion thereat provides a sealing gasket similar to gasket 10 of Figure 1. Also, the liner may have formed therewith a tamper evident band, similar to band 21 of Figure 1, which is connected to the liner within the skirt by an integral weakened portion.

Finally, it is to be understood that various alterations, modifications and/or additions may be introduced into the construction and arrangements of parts previously ■s described without departing from the spirit or ambit of the invention.

Claims (20)

^WHAT*/WE CLAIM IS; 213702 HlB^»flffS=gBWWHWaWS^VLUllUll ARC AO P»LLOWO:

1. A closure comprising composite metal and plastics portions, wherein the metal portion is preformed and comprises a cup-shaped element which includes means to facilitate attachment thereto of the plastics portion, the facilitating means comprising a lacquer applied to sheet metal from which said metal portion is preformed, and wherein the plastics portion is directly moulded against a surface of the metal portion covered by the lacquer, said lacquer being one which is compatible with plastics material from which said plastics portion is moulded and providing a direct bond with both the metal portion and the plastics portion.

2. A closure according to claim 1, wherein said lacquer is one which chemically interacts with said plastics material, such as by cross-linking therewith.

3. A closure according to claim 1 or claim 2, wherein said lacquer is a PVC or a polyethylene lacquer. --

4. A closure according to claim 3, wherein said lacquer is a PVC lacquer and said plastics portion is moulded from a plastics material comprising PVC or a PVC blend.

5. A closure according to claim 3, wherein said lacquer is a polyethylene lacquer and said plastics portion is moulded from a plastics material comprising a polyolefin or a polyolefin blend.

6. A closure according to any one of claims 1 to 5, wherein said facilitating means further includes a mechanical key formed in the metal portion of the closure, which key holds the plastics portion in relation to the metal portion.

7. A closure according Lo any one of claims 1 to 6, wherein said metal portion defines a top panel and circumferential skirt depending from that panel, with the plastics portion comprising or including a tamper evident band which has been directly moulded onto the skirt.

8. A closure according to claim 7, wherein said band comprises a joining section moulded onto the skirt, such as in a recess defined by the skirt, and a break away section to which the joining section is connected by an integral weakened, section, the weakened section for example comprising a V ^ 1 of weak bridging elements spaced circumferentially around the -9- -^\ 213702 joining section.

9. A closure according to claim 8, wherein said break away section has formed thereon means, such as an annular barb, adapted to engage a shoulder of a container to which the closure is applied and to cause tearing or rupturing of the weakened section on removal of the closure from the container.

10. A closure according to any one of claims 7 to 9, wherein said plastics portion further includes a sealing ring moulded around the junction of the top panel and skirt.

11. A closure according to any one of claims 1 to 6, wherein said metal portion defines a top panel and circumferential skirt depending from that panel, with the plastics portion comprising or including a sealing ring moulded around and adjacent the junction of the top panel and skirt.

12. A closure according to claim 10 or claim 11, wherein said sealing ring is moulded on the underside of the top panel and comprises a resilient sealing fin for sealing against the rim of a container to which the closure is applied.

13. A closure according to claim 12, wherein the sealing ring defines an abutment located radially outwardly of the sealing fin and adapted to limit movement of the fin when the closure is applied to a container.

14. A closure according to claim 13, wherein said abutment and the sealing fin are joined by a web section of the sealing ring with said web section being mechanically keyed in an annular raised section of said top panel.

15. A closure according to any one of claims 7 to 14, wherein said plastics portion defines a thread defining section moulded around the inner surface of said skirt.

16. A closure according to claim 1, substantially as herein described with reference to Figure 1 to Figure 2 of the accompanying drawings.

17. A method of forming a closure, wherein a metal portion comprising a cup-shaped element is preformed from sheet material having a lacquer applied over at,_least one surface thereof, and a plastics portion is moulded against a surface of the metal portion covered by the lacquer being one compatible with plastics material (xjcom which ^ -10- _ o: \-9N0Vl9S7i ,/ 213702 the plastics portion is moulded to provide means to facilitate attachment to the plastics portion to the metal portion by a direct bond between those portions.

18. A method according to claim 17, wherein said plastics portion is injection moulded.

19. A method according to claim 17 or claim 18, wherein metal portion is formed to provide facilitating means which includes or comprises a mechanical key formed in the metal portion of the closure and which key holds the plastics portion in relation to the metal portion.

20. A method according to any one of claims 17 to 19, wherein said closure is a closure according to any one of claims 1 to 16. iAHo THl DAY Of A. J. PARK & SON PfR AGBNTS FOR THE APPLICANTS'