Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D41/00—Caps, e.g. crown caps or crown seals, i.e. members having parts arranged for engagement with the external periphery of a neck or wall defining a pouring opening or discharge aperture; Protective cap-like covers for closure members, e.g. decorative covers of metal foil or paper
  • B65D41/02—Caps or cap-like covers without lines of weakness, tearing strips, tags, or like opening or removal devices
  • B65D41/04—Threaded or like caps or cap-like covers secured by rotation
  • B65D41/0435—Threaded or like caps or cap-like covers secured by rotation with separate sealing elements
  • B65D41/0457—Threaded or like caps or cap-like covers secured by rotation with separate sealing elements the sealing element covering or co-operating with the screw-thread or the like of a container neck

Definitions

• This invention relates to closure caps, to closure/neck finish combinations, and to a method of manufacturing closure caps.
• the invention relates to PT (Press-On/Twist-off ) closures which are designed to be applied to a container by an axial movement and removed from the container by a rotary movement .
• a plastJsol compound is flowed into a cap to provide sealing and thread forming features.
• the compound is injected as a viscous fluid onto the inside of the wall portion of the metal cap, which is spun in order to distribute the compound evenly.
• the compound is then subjected to a moulding operation by means of a plug pressed into the closure to produce the desired distribution of compound.
• the cap is then passed through an oven, the heat from which causes the compound to expand and solidify.
• An example of this type of closure is described in US4562930.
• a closure cap of the press-on/twist-off type comprising a shell including a skirt and an end panel, a first sealing portion adapted to form a seal between the end panel and at least the end sealing surface of a container, and a second liner portion adapted to be located between the skirt and a thread finish provided on the container, the liner portion being such that the closure may be applied to a container by an axial movement and removed from the container by a rotary movement, characterised in that the first sealing portion and the second liner portion are both provided by means of a single pre-formed gasket which is firstly moulded and subsequently secured in position within the closure.
• the closure skirt conveniently includes an inwardly facing projection, and the pre-formed gasket is secured in position by means of this inwardly facing projection.
• the skirt includes an inwardly facing curl at the extremity thereof, and the pre-formed gasket is crimped in position by means of the curl. This avoids the need for any adhesives, or any heat treatment of the gasket as is required with flowed-in p] astisoJ compounds.
• the cap is provided with a tamper evident band
• the tamper evident band is also secured into position by means of the inwardl facing projection or curl.
• the pre-formed gasket is conveniently formed of a polymeric material having a flexural modulus of between 30 and 900 MPa, typically between 36 and 500, and ideally around 100.
• the pre-formed gasket is preferably formed of polypropylene, although alternative materials such as polypropylene/nylon blends or even thermoplastic elastomers (TPEs) such as Santoprenes may be appropriate.
• the pre-formed gasket is preferably such that the thread finish on the container forms complementary threads on the gasket when the closure is applied to the container.
• the pre-formed gasket provides both the sealing function between the end panel and the end sealing surface of a neck finish, and also the thread retention function which allows the PT cap to be twisted off and also reapplied to the neck finish by the user. Whereas pre-formed gaskets have been proposed for vacuum closures, this has typically only been to carry out the sealing function in closures other than PT closures.
• the pre-formed gasket is preferably provided with a plurality of projections adapted to be deformed by the thread finish on a container, so as to retain the impression of the complementary threads on the gasket.
• the projections are conceivably ribs running transverse to the thread finish on the conainer, although other projections, such as pimples etc., could be envisaged.
• the pre-formed gasket is provided with preformed thread formations, adapted to engage the thread finish on the container.
• the preformed gasket has or rec e ives thread formations, to allow the closure to be ramped-off by the user and reapplied with a twist-on action.
• a closure and neck finish combination wherein the neck finish has a rim and at least one helically extending thread, and the closure has a shell including a skirt and an end panel, a first sealing portion forming a seal between the end panel and at least the rim of the container, and a second liner portion located between the skirt and the at least one helically- extending thread, the liner portion being such that the closure may be applied to a container by an axial movement and removed from the container by a rotary movement, characterised in that the first sealing portion and the second liner port. ion are both provided by means of a single pre-formed gasket which is firstly moulded and subsequently secured in position within the closure.
• a method of manufacturing a press-on/twist- off type closure comprising the steps of:- i) stamping a shell including a skirt and an end panel, ii) moulding a gasket of polymeric material, comprising a first sealing portion and a second liner portion, and iii) attaching the gasket to the shell such that the first sealing portion is adjacent the end panel to form a seal between the end panel and at least the end sealing surface of the container, and the second liner portion is adjacent the skirt such that it is adapted to be located between the skirt and the thread finish provided on the container, the liner portion being such that the closure may be applied to a container by an axial movement and removed from the container by a rotary movement.
• the invention further resides in a method of manufacturing a press-on/twi st-off type closure comprising the steps of :- i) stamping a shell including a skirt and an end panel, ii) moulding a gasket of polymeric material comprising a first sealing portion and a second liner portion, iii) presenting the gasket to the shell such that the first sealing portion is adjacent the end panel, and a second liner portion is adjacent the skirt, and iv) forming the edge of the shell into a curl such that the polymeric gasket is crimped in position such that the first sealing portion is adapted to form a seal between the end panel and at least the end sealing surface of a container, and the second liner portion is adapted to be located between the skirt and the thread finish provided on the container, t " liner portion being such that the closure may be applied t o the container by an axial movement and removed from the container by a rotary movement.
• Fig.l is a schematic cross sectional view of a vacuum closure in accordance with the present inventon
• Fig.2 is a schematic cross sectional vie'-/ of the vacuum closure of Fig.l shown applied to the neck finish of a container
• Fig.3 is a sectional- perspective view of an alternative embodiment of vacuum closure according to the present invention
• Fig.4 is a schematic sectional He of a further alternative embodiment of vacuum closure according to the present invention.
• Fig.5 is a schematic sectional ⁇ of an alternative embodiment of the vacuum closure of Fig.3 incorporating a tamper-evident band.
• the vacuum closure is shown generally at 1, and comprises a metal shell 2, including an end panel 3 and a downwardly dependant skirt 4.
• a polypropylene gasket 6 is received within the shell 2, and comprises a sealing portion 7, a thread retention portion 8, and a securing rim 9.
• the gasket is typically formed by injection moulding.
• the gasket 6 is applied to the shell 2, and the skirt 4 is curled over to form an inwardly facing curl 5.
• the curl 5 traps the rim 9 and secures the gasket 6 within the shell.
• Fig.2 shows the vacuum closure applied to the neck finish 10 of a container such as a glass jar.
• the neck finish includes thread formations 11 and an end sealing surface 12.
• the sealing portion 7 of the gasket 6 forms a hermetic seal between the end panel 3 and the end sealing surface 12 of the container at Area 'A'.
• a side seal is also formed between a portion of the gasket and the neck finish at Area '--.'.
• a lower portion of the gasket 6 cooperates with the sidewall of the neck finish at Area 'C, in order to provide a barrier to the ingress of foreign bodies such as dust, dirt and insects etc.
• the thread retention portion 8 of the gasket is deformed by the thread format ions 11 on the neck finish so that the vacuum closure 1 can be removed from the container by the user in a "twist-off" manner.
• the thread retaining portion 8 of the gasket 6 remains at least partially deformed by the thread formations 11, so that the closure can be reapplied to the glass jar by twisting it back on to the neck finish.
• Suitable materials for the gasket 6 are shown in Table 1.
• Fig.3 shows a variant to the vacuum closure of
• Figs. 1 and 2 in which the gasket 6 is provided with pre-formed longitudinally extending ribs 13.
• the ribs are typically 0.35 mm in radial depth as compared to an overall gasket radial thickness of 0.6 mm.
• the thread formations 11 make indentations in the ribs 13 which allow the closure to be easily reapplied to the container, whilst ensuring that the initial opening torque necessary to remove the closu-e from the container is not excessive and typically in the range 10 - 30 Kgf-cm.
• the ribs 13 also act as a cushion, so as to improve the abuse resistance of the closure.
• Other forms of projections, such as pimples etc. could also be employed to retain the impression of the thread formations 11 and so as to ensure that the closure 'ramps off when twisted.
• Fig. shows an alernative design of closure in which the gasket 6 has thread features 14 pre-formed therein, as opposed to relying on the impressions formed from the thread formation 11.
• Fig.5 shows an embodiment in which a tamper-evident plastics band 15 is crimped under the curl 5 together with the securing ring 9 of the gasket 6.
• the tamper- evident band 15 has weak sections (not- shown) which cause the band to break as the closure 1 is first removed from the container neck finish 10, as described in our European Patent No. 0450959B.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Closures For Containers (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

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Family Applications (1)

Country Status (4)

Families Citing this family (10)

Family Cites Families (4)

• 1997
  • 1997-05-23 GB GBGB9710538.1A patent/GB9710538D0/en not_active Ceased
• 1998
  • 1998-05-20 WO PCT/GB1998/001467 patent/WO1998052833A1/en not_active Application Discontinuation
  • 1998-05-20 EP EP98922929A patent/EP0983200A1/de not_active Withdrawn
  • 1998-05-20 AU AU75391/98A patent/AU7539198A/en not_active Abandoned

Non-Patent Citations (1)

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