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WO1996007593A1 - Easy-open containers - Google Patents

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Publication number
WO1996007593A1
WO1996007593A1 PCT/GB1995/002050 GB9502050W WO9607593A1 WO 1996007593 A1 WO1996007593 A1 WO 1996007593A1 GB 9502050 W GB9502050 W GB 9502050W WO 9607593 A1 WO9607593 A1 WO 9607593A1
Authority
WO
WIPO (PCT)
Prior art keywords
line
weakness
annular
annulus
panel
Prior art date
Application number
PCT/GB1995/002050
Other languages
French (fr)
Inventor
Martin Christopher Hawes
Original Assignee
Carnaudmetalbox Plc
Carnaudmetalbox S.A.
Carnaudmetalbox N.V.
Carnaudmetalbox (Holdings) Usa Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Carnaudmetalbox Plc, Carnaudmetalbox S.A., Carnaudmetalbox N.V., Carnaudmetalbox (Holdings) Usa Inc. filed Critical Carnaudmetalbox Plc
Priority to AU33922/95A priority Critical patent/AU3392295A/en
Publication of WO1996007593A1 publication Critical patent/WO1996007593A1/en

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21DWORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D51/00Making hollow objects
    • B21D51/16Making hollow objects characterised by the use of the objects
    • B21D51/38Making inlet or outlet arrangements of cans, tins, baths, bottles, or other vessels; Making can ends; Making closures
    • B21D51/383Making inlet or outlet arrangements of cans, tins, baths, bottles, or other vessels; Making can ends; Making closures scoring lines, tear strips or pulling tabs
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65DCONTAINERS 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
    • B65D17/00Rigid or semi-rigid containers specially constructed to be opened by cutting or piercing, or by tearing of frangible members or portions
    • B65D17/28Rigid or semi-rigid containers specially constructed to be opened by cutting or piercing, or by tearing of frangible members or portions at lines or points of weakness
    • B65D17/404Details of the lines of weakness

Definitions

  • This invention relates to an end wall of a can from which a portion may be torn apart to provide an aperture and more particularly but not exclusively to can ends having a large aperture of area little less than the area of the can end. Such can ends are often called “full aperture” can ends.
  • Containers are known in which a tubular side wall is closed at each end by an end wall and the side wall has an openable portion defined by a pair of score lines extending around the side wall. These cans are opened by means of a key which winds away the openable portion from the body. Such cans are used for corned beef but require the expense of key and some difficulty in opening US 3397810 describes a side seamed cylindrical can comprising a side wall closed at both ends by a can end. Near the upper end of the side wall a slit line extends around the side wall to terminate a short distance from either side of the side seam. A band or tape comprising two layers is applied to span the slit line and create an hermetic seal. The container is opened by removing the band or tape.
  • a pull tab is staked to an integral rivet raised from the metal of the centre panel.
  • the pull tab is raised to break the score line and then pulled to progressively remove the removable panel by tearing the rest of the score line.
  • US Patent 2017460 (Hothersall) describes a can end comprising a central panel, a first annulus of outwardly convex cross-section depending from the periphery of the centre panel, a second annulus of outwardly concave cross-section extending from the first annulus to an outwardly extending annular ledge, a chuck wall upstanding from the periphery of the ledge, and a peripheral flange.
  • This can end has a score line extending along the junction of the second annulus and the ledge to define the removable portion.
  • GB-A-1590580 Metal Box
  • One objective of this invention is to use the strength of a scored full aperture can end or body during packing and thermal processing and then break the score line to rely on an annulus of polymeric or other material bonded to both sides of the score line to maintain an hermetic seal until a consumer tears the polymeric or other material to remove the removable portion of the can end.
  • Another objective is to provide an openable portion of a wall of a can which is easy to open because the score line is covered by an annulus of frangible material which may permit use of simplified pull tabs or other gripping means.
  • this invention provides a method closing a can body, said method comprising the step of,
  • step (b) filling and closing the can body with the can end, characterised in that, in step (a) the band or annular portion of impervious material is bonded to the material to both sides of the line of weakness and at least part of said band is supported so that after step (b) the line of weakness is broken without disruption of the band or annular portion of impervious material to retain an hermetic seal.
  • the impervious material of the annular portion may be in the form of a metal foil, a barrier polymer film or an annulus of plastics material cast in-situ to span the line of weakness. Plastisols, powders or molten polymer may be used to make the annular portion of impervious material.
  • the closed can and contents may be subjected to thermal treatment in which case the line of weakness is preferably broken after thermal treatment.
  • the line of weakness may be broken in one of several ways such as application of pressure to the centre panel by a punch, but in a preferred method a probe vibrating at ultra-sonic frequency is applied to the centre panel.
  • the breaking force may be supported by folded metal of the can end.
  • the side wall of the can body has an inwardly directed bead which supports the periphery of the can end while pressure is applied to centre panel to break the line of weakness in the can end or side wall.
  • this invention provides an openable portion of a wall of a can, said openable portion being defined by a line of weakness spanned by an impervious material characterised in that, the impervious matrerial is supported by a portion of can material to permit fracture of the line of weakness without loss of an hermetic seal between the impervious material and wall material spanning the line of weakness.
  • a can end has an annular portion of impervious material is bonded to the centre panel on both sides of the line of weakness, and is made of a material which permits the line of weakness in the metal to be broken while still maintaining an hermetic seal between the removable panel and the rest of the can end.
  • the can end has a centre panel comprising an annular ledge extending inwards from the chuck wall, a first annular fold of outwardly concave cross-section turning back towards the chuck wall, a second annular fold of outwardly convex cross-section extending from the first annulus to the removable panel portion to which it is joined by a line of weakness located over the first annular fold, characterised in that, the annular portion of impervious material is bonded to both the interior surface of the second annular fold and the removable panel portion to fill the space between the line of weakness and the top of the first annular fold.
  • the can end has a peripheral flange, a chuck wall dependent from the interior of the flange, and a centre panel comprising an annular ledge extending inwards from the chuck wall, a panel wall rising from the ledge, and a centre panel portion supported by the panel wall, characterised in that, the ledge has an arcuate cross-section with a score line on the convex side of the ledge and an annular portion of impervious material bonded to the concave underside of the ledge ( Figure 7).
  • the centre panel comprises an annular ledge extending inwards from the chuck wall, a first annular fold of outwardly concave cross-section turning back towards the chuck wall, a second annular fold of outwardly convex cross section extending from the first fold to a central panel portion characterised in that the ledge has a raised annular portion at its inner periphery and a line of weakness located on the raised annular portion, said annular portion of impervious material being bonded to either the underside or topside of the ledge.
  • a polymeric annulus may be bonded to both sides of the ledge or the scored surface only.
  • the centre panel comprises an annular ledge extending inwards from the chuck wall; a panel wall rising upwardly and outwardly from the inner periphery of the ledge; and a central panel portion spanning the panel wall; a line of weakness in the ledge defining the removable portion being covered by an annulus of polymeric material bonded to the ledge.
  • This invention permits manufacture of can ends with small apertures for fruit juice or soup, as well as full aperture can ends for solid foods.
  • the can ends are made of common metals, such as tinplate or aluminium alloy, coated with lacquer such as epoxy phenolic lacquer, epoxy polyester lacquer, polyester phenolic lacquer, or alternatively laminates of polypropylene or polyamide or polyester and the metal. These coatings are chosen to achieve firm bonding to the polymeric annulus.
  • the annulus of polymeric material may be chosen from polyvinyl chloride or copolyesters of polyvinyl chloride plastisols or organosols chosen to give a closed cell or puff structure.
  • the polymer film of metal polymer laminates may serve to provide the annular portion of impervious material.
  • the annulus may be in the form of an injection moulded ring.
  • Figure 1 is a perspective sketch of a prior art can fitted with a full aperture tear-open can end;
  • Figure 2 is a side view of the can end of Figure 1 sectioned on a diameter modified according to the invention
  • Figure 3 is a perspective view of a second embodiment of a can end according to the invention.
  • Figure 4 is a side view of the can end shown in Figure 3 sectioned on a diameter
  • Figure 5 is a side view of a can end of Figure 4, when fitted on a thermally treated filled can, after breaking of the line of weakness;
  • Figure 6 is a sectioned perspective view of a can end as shown in Figure 3, fitted with a pull tab fixed by bonding to the can end;
  • Figure 7 is a sectioned view of a third embodiment of the can end, when fixed to a can body;
  • Figure 8 is a sectioned side view of a fourth embodiment of the can end;
  • Figure 9 is a like view of the can end and a can body after fracture of the line of weakness;
  • Figure 10 is a fragmentary sectioned side view showing the can end of Figure 8 as a reclosure
  • Figure 11 is a sectioned side view of a fifth embodiment of the can end when fixed to a beaded body
  • Figure 12 is a like view to Figure 9 after the line of weakness of the can end has been broken;
  • Figure 13 is a sectioned side view of a sixth embodiment of the can end.
  • Figure 14 shows a can end modified to permit gripping of the removable panel
  • Figure 15 is a perspective sketch of a can end with a small removable portion
  • Figure 16 is a fragmentary section of the openable panel shown in Figure 15 but modified to rely on metal/polymer laminates;
  • Figure 17 shows diagramatically an injection moulded annulus.
  • Figure 18 is a fragmentary side view of a can body embodying the invention.
  • Figure 19 is a fragmentary side view of a modified form of the body shown in Figure 18.
  • Figure 1 shows a prior art can body 1 comprising a cylindrical side wall 2 with a bottom wall 3 attached to the side wall by a double seam 4.
  • the can body has been filled with a product 5 leaving a headspace 6 and the can body has been closed by a top can end 7 fixed to the side wall by a double seam 8.
  • FIG 2 shows the can end 7 of Figure 1 before double seaming to the can body.
  • the can end 7 comprises a centre panel 10 a chuck wall 11 upstanding from the periphery of the centre panel, and a flange or cover hook 12 extending laterally from the top of the chuck wall.
  • a line of weakness 13 extends around the centre panel, near the chuck wall 11, to define the removable panel portion 9 which gives substantially a "full aperture” when opened.
  • the line of weakness 13 is spanned by an annulus 14 of polymeric material which according to prior practice is bonded to the removable panel portion 9 or the remaining ring of chuck wall to make one of the torn edges safe.
  • the removable panel portion 9 has an integral rivet 15 which retains a pull ring 16 which is lifted so the nose of the tab breaks the score line 13 before pulling to tear open the rest of the line of weakness, usually a score line of reduced metal thickness.
  • annulus of polymeric material and an appropriately placed annulus of release agent has been provided for the purposes of making only one of the torn edges of the removable panel or chuck wall ring safe by masking the torn metal.
  • a secondary benefit arising is that the annulus of polymeric material may cover any lacquer damage arising during forging of a line of weakness or score.
  • the user is faced with the problem of tearing scored metal apart to open the can. This problem is greater when the can ends are made from ferrous metals, such as tinplate or electrochrome coated steels (TFS), than with aluminium alloys which are relatively easier to tear.
  • ferrous metals such as tinplate or electrochrome coated steels (TFS)
  • the can end of Figure 2 may be modified by provision of an annulus of polymeric material which is bonded to both the removable panel and the surrounding remainder of the centre panel.
  • the polymeric material and bond are chosen to survive fracture of the line of weakness and provide an hermetic seal so that a consumer only has to tear or peel the polymeric or other material apart to open the removable panel.
  • Figure 3 shows a can body 17 having a side wall 18 joined by a double seam 19 according to the invention.
  • the can end 20 comprises a peripheral flange 21, a chuck wall 22 dependent from the interior of the flange, an annular ledge 23 extending inwards from the chuck wall, a first annular fold 24 of outwardly concave cross-section turning upwardly and outwardly towards the chuck wall, a second annular fold 25 of outwardly convex cross-section extending from the first annulus to a removable panel portion 26 to which it is joined by a line of weakness 27 located over the first annular fold 24 .
  • An annulus 28 of polymeric material is bonded to both the interior surface of the second annular fold 25 and the removable panel portion 26 so that the space between the line of weakness 27 and top of the first annular fold 24 is filled with polymeric material.
  • Figure 5 shows a filled and closed can body after the line of weakness 27 has been broken by application of a probe 29 vibrating at ultrasonic frequency to the removable panel portion.
  • Alternative methods of breaking the score line include vibration of the punch at subsonic frequency or use of simple punch pressure in a direction perpendicular to the score.
  • the annulus of polymeric material 28 not only joins the removable panel portion 26 to the remainder of the can end but also maintains an hermetic seal for the can. On removal, the removable portion may be used as a reclosure.
  • the can end of Figures 3 and 4 may be provided with a coated metal or plastics pull ring 30 which is fused or adhered to a coated removable panel portion as shown in Figure 6.
  • the force required to break the annulus of polymeric material, to achieve opening, is less than the force required to break a score in sheet metal.
  • Such a pull tab could equally be used in the can end of Figure 1 when modified by provision of an annulus of polymeric material permitting score fracture and giving an hermetic seal.
  • Figure 7 shows a third embodiment of the can end 31 when resting on a beaded can body 32 in readiness for joining by a double seam.
  • the can end 31 comprises a peripheral flange 33, a chuck wall 34 dependent from the interior of the flange, an annular ledge 35 extending inwardly from the chuck wall, a first annulus 36 of concave cross-section turning back on itself towards the chuck wall, a second annulus 37 of outwardly convex cross-section turning inwards to join a centre panel portion 38 this centre panel may include expansion panels as shown in Figure 3 if desired.
  • the annular ledge 35 is bowed upwards and has a circular line of weakness 39 at the highest part of the ledge.
  • the concave underside of the ledge 35 is filled with an annulus 40 of polymeric material bonded to both sides of the line of weakness 39.
  • the can end 31 is joined to the can body 32 by a double seam, the annulus 40 of polymeric material is in contact with an inwardly directed bead 41 of the side wall of the can body so that the annulus of polymeric material is supported against pressure used to break the line of weakness 39.
  • the can end of Figure 7 may be opened by inserting a lever into the first concave annulus and use of the double seam as a fulcrum. The removed centre panel and annulii can be used as a reclosure.
  • Figure 8 shows a preferred or fourth embodiment of the can end 41 in which the peripheral flange 33 and chuck wall 34 are as shown in Figure 7 but the ledge 35 extends inwardly from the chuck wall to a raised annular portion 35a in which the score line 37a is located, and the second convex annulus 45 projects outwardly over the score line.
  • An annulus 42 of polymeric material is bonded to the underside of the raised annular portion 35a to span the score line.
  • the concave annulus 36, and centre panel portion 38 are already as described with or without expansion beads in the centre panel.
  • Figure 9 shows the can end 41 of Figure 8 when attached by a double seam 46 to a seam wall 43 of a can body filled with product 44.
  • Figure 10 shows can of Figure 9 after a consumer has removed the removable portion, used some of the product, and reapplied the removable portion as a reclosure by placing the annulus 36 in the aperture with the second annulus 45 preventing the centre panel portion from falling through the aperture.
  • Figure 11 shows a can end similar to the can end of Figure 8 but provided with a second annulus 50 of polymeric material located in a channel 51 defined by the chuck wall 34, the stepped ledge 35 and the first outwardly concave annulus 36.
  • This can end may opened by a spoon or other form of lever inserted in the channel.
  • the can end is attached to the side wall of a can body by a double seam 46.
  • the can body has an inwardly directed bead 52 having a flat top surface 53 which extends into the can to support the first annulus of polymeric material under the line of weakness shown as a score 54.
  • the second annulus 50 of polymeric material covers the ledge 35 including the raised annular portion 35a and score line 54 which in this example is formed into the top or external surface of the raised annular portion 35a of the can end. This second annulus not only serves to provide an hermetic seal but also protects the score from corrosive environments.
  • Figure 12 shows the can end during fracture of the score line 54 by a force F which may be imposed by a punch or a probe (not shown) preferably vibrating at ultrasonic frequency applied to the removable panel portion.
  • the first annulus 55 of polymeric material is temporarily compressed against the top surface 53 of -the body bead 52, the load being passed through the inclined surface 56 of the bead to the rest of the side wall 57 of the can body which is supported on a firm surface.
  • Figure 13 shows another embodiment of the can end 60 which comprises a simplified channel portion 61 comprising the chuck wall 62, a flat ledge 63 extending inwardly from the chuck wall, an annular outwardly concave bead 64 rising from the inner periphery of the ledge, an annular outwardly convex bead 65 extending over a score line 66 in the ledge to turn inwards to join a central panel portion 67 provided with an expansion panel 68.
  • a force is applied to the central panel portion 67 to break the score the annulus 68 of polymeric material bonded in the channel over the score line, is put in compression so there is less risk of premature tearing of the polymeric material.
  • FIG 14 is a sketch showing that instead of the usual pull ring attached by bonding or an integral rivet to the removable portion, the removable portion 70 may be provided with sunken panels 71, 72 that permit finger grip for removal provided the annulus of polymeric material permits it.
  • Figure 15 shows another can end 80 connected to a fragment of a cylindical can body 81 by a double seam 82.
  • This can end comprises a peripheral seam portion 83, a chuck wall 84 dependent from the seam portion, a flat centre panel 85 provided with an openable portion 86 much smaller in area than the area of the panel.
  • the openable portion 86 is defined by an approximately triangular score line 87 surrounded by an outwardly convex annulus or fold 88 connecting with an outwardly concave annulus 89 which joins the upper, outwardly convex annulus to the centre panel 85.
  • the can end is made from a laminate of sheet metal and a polymeric film.
  • the laminate will be electrochrome coated steel covered by a layer of polypropylene or polyethylene terephthalate of thickness between 30um and lOOum.
  • the outwardly convex annulus 88 is filled with an annulus 90 of polymeric material such as a polyvinyl chloride to act as a sealant if the polymeric film is broken during fracture of the score line 87.
  • a pull tab 91 is bonded to the upper side of the openable portion 86.
  • Figure 16 shows a fragment of the can end shown in Figure 15 in which the convex 98 and concave 99 annulii have been crushed so that the folded layers of polymer film in the concave annulus touch under the score lines so making it possible to fracture the metal M without fracturing the polymer coated P.
  • a preferred thickness of polymer film is between 50um and lOOum to act not only as a protective coating but also as the impermeable annular portion.
  • Figure 17 shows a fragment of a can end 100 comprising a peripheral flange 101, a chuck wall 102 dependent from the interior of the flange, and an annular bead 103 extending inwards from the chuck wall to support a flat centre panel 104.
  • a removable panel portion 105 is defined in the centre panel by a circular score line 106.
  • the can end has a lacquer coating 107.
  • a lining compound comprising a peripheral flange 101, a chuck wall 102 dependent from the interior of the flange, and an annular bead 103 extending inwards from the chuck wall to support a flat centre panel 104.
  • a removable panel portion 105 is defined in the centre panel by a circular score line 106.
  • the can end has a lacquer coating 107.
  • 108 is located in the peripheral flange to serve as a sealing gasket when the can end is fixed to a can body by a double seam.
  • annulus As shown in Figure 17, an injection moulded annulus
  • Figure 18 shows a can body 110 comprising a cylindrical side wall 111 closed at one end by a bottom wall 112 attached to the side wall by means of a double seam 113.
  • a line of weakness 114 extends around the side wall to define an openable portion.
  • the line of weakness is spanned on the interior surface of the side wall by a band 115 of impervious material which is bonded on both sides of the line of weakness to the side wall material.
  • a top can end 116 comprising a centre panel 117 surrounded by an upstanding chuck wall 118, is attached to the side wall by a double seam 119.
  • the band 115 of impervious material extends between the side wall metal above the line of weakness 114 and the chuck wall 118 of the can end 116 so that line the line of weakness 114 may be broken, after closing and thermal processing of the can and content P without breaking hermetic seal provided by the band 115 across the line of weakness. After breaking of the line of weakness 114 the band 115 is relied on to provide an hermetic seal which is only broken when the product is to be consumed.
  • Figure 19 shows a closed can similar to that shown in Figure 18 but modified to support the band of impervious material at both sides of the line of weakness so reducing reliance on adhesion.
  • a can body 120 comprises a cylindrical side wall 121 closed at one end by a bottom wall 122 attached to the side wall by means of a double seam 123.
  • a circumferential bead 124 extends radially inwards and upwards before returning on itself to define a channel 125 portion supporting the upper, terminal, margin of the side wal metal.
  • This side wall margin includes a line of weakness 126 and material for inclusion as body hook 127 in the double seam 128 which joins a top can end 129 to the side wall 121.
  • the line of weakness 126 is spanned by a band 130 impervious material bonded to the side wall material at both sides of the line of weakness 126.
  • the upper can end 129 comprises an annular seam portion a chuck wall 132 dependent from the seam portion, a plug portion 133 dependent from the chuck wall and a centre panel 134 spanning the plug portion.
  • the chuck wall 132 serves to support the band 130 of impervious material on the terminal margin of the side wall whilst bead channel 125 supports the other side of the band during fracture of the line of weakness.
  • the bead 124 acts to mask the fractured line of weakness 126 after opening.
  • the plug portion 133 of the can end 129 fits in the circumferential bead 124 to permit reclosure of the body if only part of the product P is used immediately after opening of the impervious band.
  • the side walls 111, 121 of Figures 18 and 19 may conveniently be made by cutting a rectangular blank from a sheet metal, which may or may not be coated; scoring a line of weakness along the blank; applying the tape of polymeric material to can edge margin of the blank; forming a cylinder from the taped blank; and lap welding the adjacent edges. It will be appreciated that the lap weld edges may be kept uncovered if the tape is a little shorter than the blank. If desired, the line of weakness may start and finish a short from the lap weld so that a "hinge" portion of sidewall is retained.
  • the peel strength of the bond permits the removed panel to peel easily away from the moulded annulus while the annulus remains firmly bonded to the fixed inner wall of the bead and other side of the score.
  • Typical metal/polymer laminates suitable for use in the embodiment shown in Figure 16 include: a) electrochro e coated steel/maleic anhydride modified polyprop lene/polyamide; b) electrochrome coated steel/maleic anhydride modified polyprop lene/polyamide eg nylon 6; c) electrochrome coated steel/copolyester of ethylene terephthate and ethylene isophthalate (80:20)/polyethylene terephthalate; or d) tinplate/linear low density polyethylene;
  • electrochrome coated steel/copolyester of ethylene terephthate and ethylene isophthalate (80:20)/polyethylene terephthalate; or d) tinplate/linear low density polyethylene However it will be understood that many alternative laminates may be used.
  • the can ends are made from sheet metal such as electrochrome coated steel, tinplate or aluminium or aluminium alloy.
  • the sheet metal is coated with a coating material to which the annular portion of impervious material will adhere firmly e.g. epoxy phenolic coating or epoxy polyester coatings or laminate of the sheet metal and a polymeric film such as polypropylene or polyamide such as nylon 6.
  • the annular portion of impervious material may be a polyurethane for external use on the can end or a PVC or rubber compound for internal use. Suitable PVC annulii include PVC copolymers and foamed closed cell PVC.
  • the hermetic seal provided may be a peelable seal. In alternative embodiments the impervious material may be ruptured to achieve final opening by the consumer.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Containers Opened By Tearing Frangible Portions (AREA)

Abstract

The scored side wall of a can body (110) or a large aperture tear-open can end (20) has a removable portion (26) defined by a score line (27) which is covered by a band or annulus (28) of polymeric or other material bonded to the side wall or can end at both sides of the score line so that after seaming of the can end onto a can body (17) the score line may be broken without disruption of the hermetic seal provided by the polymeric annulus. The polymers chosen for the annulus are easier to tear than scored metal. The removable portion of the body or can end is opened either by fracture of the polymeric annulus or peeling of the removable portion away from the annulus.

Description

EASY-OPEN CONTAINER
This invention relates to an end wall of a can from which a portion may be torn apart to provide an aperture and more particularly but not exclusively to can ends having a large aperture of area little less than the area of the can end. Such can ends are often called "full aperture" can ends.
Containers are known in which a tubular side wall is closed at each end by an end wall and the side wall has an openable portion defined by a pair of score lines extending around the side wall. These cans are opened by means of a key which winds away the openable portion from the body. Such cans are used for corned beef but require the expense of key and some difficulty in opening US 3397810 describes a side seamed cylindrical can comprising a side wall closed at both ends by a can end. Near the upper end of the side wall a slit line extends around the side wall to terminate a short distance from either side of the side seam. A band or tape comprising two layers is applied to span the slit line and create an hermetic seal. The container is opened by removing the band or tape. A problem with this pre-slit is that pressures arising inside a container during thermal processing are resisted by only the tape strength. The benefit available from the strength of the side wall metal is lost at the slit line. Furthermore the tape is available to abuse during transit and vending. Full aperture can ends are described in British Patents 1530122 (MetalBox), and British Patents 1322140 and 1350674 (Continental Can). These patent specifications describe can ends stamped from sheet metal to comprise a centre panel, a chuck wall upstanding from the periphery of the centre panel, and a peripheral flange or "cover hook" extending laterally from the top of the chuck wall. A circular line of weakness, usually formed by scoring, extends around the centre panel near the chuck wall to define a removable panel. A pull tab is staked to an integral rivet raised from the metal of the centre panel. The pull tab is raised to break the score line and then pulled to progressively remove the removable panel by tearing the rest of the score line. These patent specifications describe various arrangements of annulii of polymeric material bonded to either the removable panel or the remainder of the can end in order to mask the torn edges of the removed panel or the remainder. GB-A-1530122 also describes use of an inwardly directed guard bead formed in the side wall of a can body which masks the torn edge of a remainder portion of a full aperture can end.
US Patent 2017460 (Hothersall) describes a can end comprising a central panel, a first annulus of outwardly convex cross-section depending from the periphery of the centre panel, a second annulus of outwardly concave cross-section extending from the first annulus to an outwardly extending annular ledge, a chuck wall upstanding from the periphery of the ledge, and a peripheral flange. This can end has a score line extending along the junction of the second annulus and the ledge to define the removable portion. A can, fitted with this can end by means of a double seam, is opened by inserting the tip of a lever into the second annulus and, using the double seam as a fulcrum, the removable portion is prised apart by breaking the score line. GB-A-1590580 (Metal Box) provides a modified form of lever-out full aperture can end in which the remainder portion is folded back on itself and the score is located on top of the fold so that the torn edge of the remainder portion is made safe by the fold.
All these prior art can ends require the user to tear open the thin metal of the can end so that inspite many years of diligent endeavour to make the score lines as thin as possible to reduce the force required during opening, the score line has had to remain strong enough to survive pressures arising due to expansion of product in the closed can during thermal processing, and accidental abuse in transit.
One objective of this invention is to use the strength of a scored full aperture can end or body during packing and thermal processing and then break the score line to rely on an annulus of polymeric or other material bonded to both sides of the score line to maintain an hermetic seal until a consumer tears the polymeric or other material to remove the removable portion of the can end.
Another objective is to provide an openable portion of a wall of a can which is easy to open because the score line is covered by an annulus of frangible material which may permit use of simplified pull tabs or other gripping means.
In a first aspect this invention provides a method closing a can body, said method comprising the step of,
(a) providing a can body and can end at least one of which has an openable portion defined by a line of weakness spanned by a band or annular portion of impervious material, and
(b) filling and closing the can body with the can end, characterised in that, in step (a) the band or annular portion of impervious material is bonded to the material to both sides of the line of weakness and at least part of said band is supported so that after step (b) the line of weakness is broken without disruption of the band or annular portion of impervious material to retain an hermetic seal.
The impervious material of the annular portion may be in the form of a metal foil, a barrier polymer film or an annulus of plastics material cast in-situ to span the line of weakness. Plastisols, powders or molten polymer may be used to make the annular portion of impervious material. After step (b) the closed can and contents may be subjected to thermal treatment in which case the line of weakness is preferably broken after thermal treatment.
The line of weakness may be broken in one of several ways such as application of pressure to the centre panel by a punch, but in a preferred method a probe vibrating at ultra-sonic frequency is applied to the centre panel.
During breaking of the line of weakness the breaking force may be supported by folded metal of the can end. In an alternative method the side wall of the can body has an inwardly directed bead which supports the periphery of the can end while pressure is applied to centre panel to break the line of weakness in the can end or side wall.
In a second aspect this invention provides an openable portion of a wall of a can, said openable portion being defined by a line of weakness spanned by an impervious material characterised in that, the impervious matrerial is supported by a portion of can material to permit fracture of the line of weakness without loss of an hermetic seal between the impervious material and wall material spanning the line of weakness.
In a first embodiment a can end has an annular portion of impervious material is bonded to the centre panel on both sides of the line of weakness, and is made of a material which permits the line of weakness in the metal to be broken while still maintaining an hermetic seal between the removable panel and the rest of the can end.
In a second embodiment the can end has a centre panel comprising an annular ledge extending inwards from the chuck wall, a first annular fold of outwardly concave cross-section turning back towards the chuck wall, a second annular fold of outwardly convex cross-section extending from the first annulus to the removable panel portion to which it is joined by a line of weakness located over the first annular fold, characterised in that, the annular portion of impervious material is bonded to both the interior surface of the second annular fold and the removable panel portion to fill the space between the line of weakness and the top of the first annular fold.
In a third embodiment the can end has a peripheral flange, a chuck wall dependent from the interior of the flange, and a centre panel comprising an annular ledge extending inwards from the chuck wall, a panel wall rising from the ledge, and a centre panel portion supported by the panel wall, characterised in that, the ledge has an arcuate cross-section with a score line on the convex side of the ledge and an annular portion of impervious material bonded to the concave underside of the ledge (Figure 7).
In a fourth embodiment the centre panel comprises an annular ledge extending inwards from the chuck wall, a first annular fold of outwardly concave cross-section turning back towards the chuck wall, a second annular fold of outwardly convex cross section extending from the first fold to a central panel portion characterised in that the ledge has a raised annular portion at its inner periphery and a line of weakness located on the raised annular portion, said annular portion of impervious material being bonded to either the underside or topside of the ledge. If desired a polymeric annulus may be bonded to both sides of the ledge or the scored surface only.
In another embodiment the centre panel comprises an annular ledge extending inwards from the chuck wall; a panel wall rising upwardly and outwardly from the inner periphery of the ledge; and a central panel portion spanning the panel wall; a line of weakness in the ledge defining the removable portion being covered by an annulus of polymeric material bonded to the ledge.
This invention permits manufacture of can ends with small apertures for fruit juice or soup, as well as full aperture can ends for solid foods.
In preferred embodiments the can ends are made of common metals, such as tinplate or aluminium alloy, coated with lacquer such as epoxy phenolic lacquer, epoxy polyester lacquer, polyester phenolic lacquer, or alternatively laminates of polypropylene or polyamide or polyester and the metal. These coatings are chosen to achieve firm bonding to the polymeric annulus.
The annulus of polymeric material may be chosen from polyvinyl chloride or copolyesters of polyvinyl chloride plastisols or organosols chosen to give a closed cell or puff structure. Alternatively the polymer film of metal polymer laminates may serve to provide the annular portion of impervious material. To facilitate mechanical handling the annulus may be in the form of an injection moulded ring.
Various embodiments will now be described by way of example and with reference to the accompanying drawings in which:
Figure 1 is a perspective sketch of a prior art can fitted with a full aperture tear-open can end;
Figure 2 is a side view of the can end of Figure 1 sectioned on a diameter modified according to the invention;
Figure 3 is a perspective view of a second embodiment of a can end according to the invention;
Figure 4 is a side view of the can end shown in Figure 3 sectioned on a diameter;
Figure 5 is a side view of a can end of Figure 4, when fitted on a thermally treated filled can, after breaking of the line of weakness;
Figure 6 is a sectioned perspective view of a can end as shown in Figure 3, fitted with a pull tab fixed by bonding to the can end;
Figure 7 is a sectioned view of a third embodiment of the can end, when fixed to a can body;
Figure 8 is a sectioned side view of a fourth embodiment of the can end; Figure 9 is a like view of the can end and a can body after fracture of the line of weakness;
Figure 10 is a fragmentary sectioned side view showing the can end of Figure 8 as a reclosure;
Figure 11 is a sectioned side view of a fifth embodiment of the can end when fixed to a beaded body;
Figure 12 is a like view to Figure 9 after the line of weakness of the can end has been broken;
Figure 13 is a sectioned side view of a sixth embodiment of the can end; and
Figure 14 shows a can end modified to permit gripping of the removable panel;
Figure 15 is a perspective sketch of a can end with a small removable portion;
Figure 16 is a fragmentary section of the openable panel shown in Figure 15 but modified to rely on metal/polymer laminates;
Figure 17 shows diagramatically an injection moulded annulus.
Figure 18 is a fragmentary side view of a can body embodying the invention; and
Figure 19 is a fragmentary side view of a modified form of the body shown in Figure 18.
Figure 1 shows a prior art can body 1 comprising a cylindrical side wall 2 with a bottom wall 3 attached to the side wall by a double seam 4. The can body has been filled with a product 5 leaving a headspace 6 and the can body has been closed by a top can end 7 fixed to the side wall by a double seam 8.
Figure 2 shows the can end 7 of Figure 1 before double seaming to the can body. The can end 7 comprises a centre panel 10 a chuck wall 11 upstanding from the periphery of the centre panel, and a flange or cover hook 12 extending laterally from the top of the chuck wall. A line of weakness 13 extends around the centre panel, near the chuck wall 11, to define the removable panel portion 9 which gives substantially a "full aperture" when opened. The line of weakness 13 is spanned by an annulus 14 of polymeric material which according to prior practice is bonded to the removable panel portion 9 or the remaining ring of chuck wall to make one of the torn edges safe. The removable panel portion 9 has an integral rivet 15 which retains a pull ring 16 which is lifted so the nose of the tab breaks the score line 13 before pulling to tear open the rest of the line of weakness, usually a score line of reduced metal thickness.
Hitherto the annulus of polymeric material and an appropriately placed annulus of release agent has been provided for the purposes of making only one of the torn edges of the removable panel or chuck wall ring safe by masking the torn metal. A secondary benefit arising is that the annulus of polymeric material may cover any lacquer damage arising during forging of a line of weakness or score. However, the user is faced with the problem of tearing scored metal apart to open the can. This problem is greater when the can ends are made from ferrous metals, such as tinplate or electrochrome coated steels (TFS), than with aluminium alloys which are relatively easier to tear.
According to this invention the can end of Figure 2 may be modified by provision of an annulus of polymeric material which is bonded to both the removable panel and the surrounding remainder of the centre panel. The polymeric material and bond are chosen to survive fracture of the line of weakness and provide an hermetic seal so that a consumer only has to tear or peel the polymeric or other material apart to open the removable panel.
Figure 3 shows a can body 17 having a side wall 18 joined by a double seam 19 according to the invention. In Figures 3 and 4 the can end 20 comprises a peripheral flange 21, a chuck wall 22 dependent from the interior of the flange, an annular ledge 23 extending inwards from the chuck wall, a first annular fold 24 of outwardly concave cross-section turning upwardly and outwardly towards the chuck wall, a second annular fold 25 of outwardly convex cross-section extending from the first annulus to a removable panel portion 26 to which it is joined by a line of weakness 27 located over the first annular fold 24 . An annulus 28 of polymeric material is bonded to both the interior surface of the second annular fold 25 and the removable panel portion 26 so that the space between the line of weakness 27 and top of the first annular fold 24 is filled with polymeric material.
Figure 5 shows a filled and closed can body after the line of weakness 27 has been broken by application of a probe 29 vibrating at ultrasonic frequency to the removable panel portion. Alternative methods of breaking the score line include vibration of the punch at subsonic frequency or use of simple punch pressure in a direction perpendicular to the score. When the line of weakness in the metal is broken the annulus of polymeric material 28 not only joins the removable panel portion 26 to the remainder of the can end but also maintains an hermetic seal for the can. On removal, the removable portion may be used as a reclosure.
The can end of Figures 3 and 4 may be provided with a coated metal or plastics pull ring 30 which is fused or adhered to a coated removable panel portion as shown in Figure 6. The force required to break the annulus of polymeric material, to achieve opening, is less than the force required to break a score in sheet metal. Such a pull tab could equally be used in the can end of Figure 1 when modified by provision of an annulus of polymeric material permitting score fracture and giving an hermetic seal.
Figure 7 shows a third embodiment of the can end 31 when resting on a beaded can body 32 in readiness for joining by a double seam. The can end 31 comprises a peripheral flange 33, a chuck wall 34 dependent from the interior of the flange, an annular ledge 35 extending inwardly from the chuck wall, a first annulus 36 of concave cross-section turning back on itself towards the chuck wall, a second annulus 37 of outwardly convex cross-section turning inwards to join a centre panel portion 38 this centre panel may include expansion panels as shown in Figure 3 if desired. In Figure 7 it will be seen that the annular ledge 35 is bowed upwards and has a circular line of weakness 39 at the highest part of the ledge. The concave underside of the ledge 35 is filled with an annulus 40 of polymeric material bonded to both sides of the line of weakness 39. When after filling with a product, the can end 31 is joined to the can body 32 by a double seam, the annulus 40 of polymeric material is in contact with an inwardly directed bead 41 of the side wall of the can body so that the annulus of polymeric material is supported against pressure used to break the line of weakness 39. The can end of Figure 7 may be opened by inserting a lever into the first concave annulus and use of the double seam as a fulcrum. The removed centre panel and annulii can be used as a reclosure.
A problem arises with the can end 31 of Figure 7 because a score located midway across the ledge 35 gives an aperture through which the removed panel portion may fall when used as a reclosure. Also there is little support for the annulus 40 of polymeric material during fracture of the score line 39 unless the can body is provided with an inwardly directed ledge.
Figure 8 shows a preferred or fourth embodiment of the can end 41 in which the peripheral flange 33 and chuck wall 34 are as shown in Figure 7 but the ledge 35 extends inwardly from the chuck wall to a raised annular portion 35a in which the score line 37a is located, and the second convex annulus 45 projects outwardly over the score line. An annulus 42 of polymeric material is bonded to the underside of the raised annular portion 35a to span the score line. The concave annulus 36, and centre panel portion 38 are already as described with or without expansion beads in the centre panel.
Figure 9 shows the can end 41 of Figure 8 when attached by a double seam 46 to a seam wall 43 of a can body filled with product 44.
Application of force to the centre panel portion by tool 47 has broken the score 37a displacing the removable panel a distance (exaggerated in Figure 9) into the opening created in the rest of the can end. However, abuttment of the second, convex annulus 45 with the remainder of the can end limits displacement so that the annulus 42 of polymeric material is not broken when the scored metal is broken.
Figure 10 shows can of Figure 9 after a consumer has removed the removable portion, used some of the product, and reapplied the removable portion as a reclosure by placing the annulus 36 in the aperture with the second annulus 45 preventing the centre panel portion from falling through the aperture.
Figure 11 shows a can end similar to the can end of Figure 8 but provided with a second annulus 50 of polymeric material located in a channel 51 defined by the chuck wall 34, the stepped ledge 35 and the first outwardly concave annulus 36. This can end may opened by a spoon or other form of lever inserted in the channel.
As shown in Figures 11 and 12 the can end is attached to the side wall of a can body by a double seam 46. The can body has an inwardly directed bead 52 having a flat top surface 53 which extends into the can to support the first annulus of polymeric material under the line of weakness shown as a score 54. The second annulus 50 of polymeric material covers the ledge 35 including the raised annular portion 35a and score line 54 which in this example is formed into the top or external surface of the raised annular portion 35a of the can end. This second annulus not only serves to provide an hermetic seal but also protects the score from corrosive environments.
Figure 12 shows the can end during fracture of the score line 54 by a force F which may be imposed by a punch or a probe (not shown) preferably vibrating at ultrasonic frequency applied to the removable panel portion. The first annulus 55 of polymeric material is temporarily compressed against the top surface 53 of -the body bead 52, the load being passed through the inclined surface 56 of the bead to the rest of the side wall 57 of the can body which is supported on a firm surface.
After fracture of the score line 54, the polymeric annulii 50, 55 will elastically return to their original shape to act as an hermetic seal for the can.
Figure 13 shows another embodiment of the can end 60 which comprises a simplified channel portion 61 comprising the chuck wall 62, a flat ledge 63 extending inwardly from the chuck wall, an annular outwardly concave bead 64 rising from the inner periphery of the ledge, an annular outwardly convex bead 65 extending over a score line 66 in the ledge to turn inwards to join a central panel portion 67 provided with an expansion panel 68. When a force is applied to the central panel portion 67 to break the score the annulus 68 of polymeric material bonded in the channel over the score line, is put in compression so there is less risk of premature tearing of the polymeric material. A further advantage arises because the diameter of the outwardly convex bead 65 is too large to pass through the score diameter so that there is no need for an inwardly directed bead on the side wall of the can body to support this can end during fracture of the scored metal. When the consumer has opened this can end and removed a solid or semi solid product, the removed panel may be used as a reclosure for the can. Figure 14 is a sketch showing that instead of the usual pull ring attached by bonding or an integral rivet to the removable portion, the removable portion 70 may be provided with sunken panels 71, 72 that permit finger grip for removal provided the annulus of polymeric material permits it.
Figure 15 shows another can end 80 connected to a fragment of a cylindical can body 81 by a double seam 82. This can end comprises a peripheral seam portion 83, a chuck wall 84 dependent from the seam portion, a flat centre panel 85 provided with an openable portion 86 much smaller in area than the area of the panel. The openable portion 86 is defined by an approximately triangular score line 87 surrounded by an outwardly convex annulus or fold 88 connecting with an outwardly concave annulus 89 which joins the upper, outwardly convex annulus to the centre panel 85.
In Figure 15 it will be seen that the can end is made from a laminate of sheet metal and a polymeric film. Typically the laminate will be electrochrome coated steel covered by a layer of polypropylene or polyethylene terephthalate of thickness between 30um and lOOum.
As shown in Figure 15 the outwardly convex annulus 88 is filled with an annulus 90 of polymeric material such as a polyvinyl chloride to act as a sealant if the polymeric film is broken during fracture of the score line 87. A pull tab 91 is bonded to the upper side of the openable portion 86.
Figure 16 shows a fragment of the can end shown in Figure 15 in which the convex 98 and concave 99 annulii have been crushed so that the folded layers of polymer film in the concave annulus touch under the score lines so making it possible to fracture the metal M without fracturing the polymer coated P. In this embodiment a preferred thickness of polymer film is between 50um and lOOum to act not only as a protective coating but also as the impermeable annular portion.
Figure 17 shows a fragment of a can end 100 comprising a peripheral flange 101, a chuck wall 102 dependent from the interior of the flange, and an annular bead 103 extending inwards from the chuck wall to support a flat centre panel 104. A removable panel portion 105 is defined in the centre panel by a circular score line 106. The can end has a lacquer coating 107. A lining compound
108 is located in the peripheral flange to serve as a sealing gasket when the can end is fixed to a can body by a double seam.
As shown in Figure 17, an injection moulded annulus
109 of polymeric material is bonded to the lacquered surface of the can end in a position to span the score line 106.
Figure 18 shows a can body 110 comprising a cylindrical side wall 111 closed at one end by a bottom wall 112 attached to the side wall by means of a double seam 113.
Near the upper end of the side wall a line of weakness 114 extends around the side wall to define an openable portion. The line of weakness is spanned on the interior surface of the side wall by a band 115 of impervious material which is bonded on both sides of the line of weakness to the side wall material.
At the top of the side wall a top can end 116, comprising a centre panel 117 surrounded by an upstanding chuck wall 118, is attached to the side wall by a double seam 119.
As shown in Figure 18, the band 115 of impervious material extends between the side wall metal above the line of weakness 114 and the chuck wall 118 of the can end 116 so that line the line of weakness 114 may be broken, after closing and thermal processing of the can and content P without breaking hermetic seal provided by the band 115 across the line of weakness. After breaking of the line of weakness 114 the band 115 is relied on to provide an hermetic seal which is only broken when the product is to be consumed.
Figure 19 shows a closed can similar to that shown in Figure 18 but modified to support the band of impervious material at both sides of the line of weakness so reducing reliance on adhesion.
In Figure 19 a can body 120 comprises a cylindrical side wall 121 closed at one end by a bottom wall 122 attached to the side wall by means of a double seam 123.
Near the upper end of the side wall a circumferential bead 124 extends radially inwards and upwards before returning on itself to define a channel 125 portion supporting the upper, terminal, margin of the side wal metal. This side wall margin includes a line of weakness 126 and material for inclusion as body hook 127 in the double seam 128 which joins a top can end 129 to the side wall 121.
The line of weakness 126 is spanned by a band 130 impervious material bonded to the side wall material at both sides of the line of weakness 126.
The upper can end 129 comprises an annular seam portion a chuck wall 132 dependent from the seam portion, a plug portion 133 dependent from the chuck wall and a centre panel 134 spanning the plug portion.
The chuck wall 132 serves to support the band 130 of impervious material on the terminal margin of the side wall whilst bead channel 125 supports the other side of the band during fracture of the line of weakness. '
The bead 124 acts to mask the fractured line of weakness 126 after opening. The plug portion 133 of the can end 129 fits in the circumferential bead 124 to permit reclosure of the body if only part of the product P is used immediately after opening of the impervious band. The side walls 111, 121 of Figures 18 and 19 may conveniently be made by cutting a rectangular blank from a sheet metal, which may or may not be coated; scoring a line of weakness along the blank; applying the tape of polymeric material to can edge margin of the blank; forming a cylinder from the taped blank; and lap welding the adjacent edges. It will be appreciated that the lap weld edges may be kept uncovered if the tape is a little shorter than the blank. If desired, the line of weakness may start and finish a short from the lap weld so that a "hinge" portion of sidewall is retained.
As with all the embodiments described, two methods of opening the removable portion are available:-
(i) If the annulus or band is frangible part will remain adhered to the fixed part of the can body or end and part will adhere to the periphery of the removed portion so that both broken score edges will be made safe;
(ii) Alternatively, particularly as shown in Figure 17, the peel strength of the bond permits the removed panel to peel easily away from the moulded annulus while the annulus remains firmly bonded to the fixed inner wall of the bead and other side of the score.
Typical metal/polymer laminates suitable for use in the embodiment shown in Figure 16 include: a) electrochro e coated steel/maleic anhydride modified polyprop lene/polyamide; b) electrochrome coated steel/maleic anhydride modified polyprop lene/polyamide eg nylon 6; c) electrochrome coated steel/copolyester of ethylene terephthate and ethylene isophthalate (80:20)/polyethylene terephthalate; or d) tinplate/linear low density polyethylene; However it will be understood that many alternative laminates may be used.
The can ends are made from sheet metal such as electrochrome coated steel, tinplate or aluminium or aluminium alloy. The sheet metal is coated with a coating material to which the annular portion of impervious material will adhere firmly e.g. epoxy phenolic coating or epoxy polyester coatings or laminate of the sheet metal and a polymeric film such as polypropylene or polyamide such as nylon 6. The annular portion of impervious material may be a polyurethane for external use on the can end or a PVC or rubber compound for internal use. Suitable PVC annulii include PVC copolymers and foamed closed cell PVC. The hermetic seal provided may be a peelable seal. In alternative embodiments the impervious material may be ruptured to achieve final opening by the consumer.

Claims

1. A method closing a can body, said method comprising the steps of: a) providing a can body and can end at least one of which has an openable portion defined by a line of weakness spanned by a band or annular portion of impervious material, and b) filling and closing the can body with the can end, characterised in that, in step (a) the band or annular portion of impervious material is bonded to the material to both sides of the line weakness and at least part of said band is supported so that after step (b) the line of weakness is broken without disruption of the band or annular portion of impervious material to retain an hermetic seal.
2. A method according to claim 1 wherein the annular portion of impervious material is chosen from a metal foil, a film of polymer, or an annulus of polymeric material or an annulus of rubber.
3. A method according to claim 1 or claim 2 wherein the closed can and contents are thermally treated before the line of weakness is broken.
4. A method according any preceding wherein the score is broken by applying a probe, preferably vibrating at ultrasonic frequency, to the removable panel.
5. A method according to any preceding claim wherein the annular portion of impervious material is supported by folded metal of the can end while the line of weakness is broken.
6. A method according to any one of claims 1 to 3 wherein the annular portion of impervious material is supported by an inwardly directed bead formed in the side wall of the can body.
7. A method according to any preceding claim wherein a second annular portion of impervious material spanning the line of weakness is bonded to the opposite side of the can end from the first annular portion of impervious material also spanning the line of weakness.
8. An openable portion of a wall of a can, said openable portion being defined by a line of weakness spanned by an impervious material, characterised in that^ the impervious material is bonded to the wall material on both sides of the line weakness and the impervious material is supported by a portion of can material to permit fracture of the line of weakness without loss of an hermetic seal between the impervious material and wall material.
9. A metal can end having a centre panel, a chuck wall upstanding from the periphery of the centre panel, and a peripheral flange extending laterally from the top of the chuck wall, said centre panel including a line of weakness defining a removable panel portion, and an annular portion material spanning the line of weakness, characterised in that, an annular portion of impervious material is bonded to the centre panel on both sides of the line of weakness,and is made of material which permits the line of weakness in the metal to be broken while still maintaining an hermetic seal between the removable panel and the rest of the can end.
10. A can end according to claim 9 wherein the can end has a centre panel comprising an annular ledge extending inwards from the chuck wall, a first annular fold of outwardly concave cross-section turning back towards the chuck wall, a second annular fold of outwardly convex cross-section extending from the first annulus to the removable panel portion to which it is joined by a line of weakness located over the first annular fold, characterised in that, the annular portion of impervious material is bonded to both the interior surface of the second annular fold and the removable panel portion to fill the space between the line of weakness and the top of the first annular fold.
11. A can end according to claim 9 wherein the can end has a peripheral flange, a chuck wall dependent from the interior of the flange, and a centre panel comprising an annular ledge extending inwards from the chuck wall, a panel wall rising from the ledge, and a centre panel portion supported by the panel wall, characterised in that, the ledge has an arcuate cross-section with a score line on the convex side of the ledge and an annulus of impervious material bonded to the concave underside of the ledge.
12. A can end according to claim 9 wherein the centre panel comprises an annular ledge extending inwards from the chuck wall, a first annular fold of outwardly concave cross-section turing back towards the chuck wall, a second annular fold of outwardly convex cross-section extending from the first annular to a centre panel portion characterised in that the ledge has a raised annular portion at its inner periphery and a line of weakness located on the raised annulus portion said annulus of polymeric material being bonded to the underside of the raised annular portion.
13. A can end according to claim 12 wherein a further annulus of polymeric material is bonded to the upper side of the ledge to span the line of weakness.
14. A can end according to claim 9 wherein the centre panel comprises a ledge extending inwardly from the chuck wall, a panel wall rising upwardly and outwardly from the inner periphery of the ledge, and a centre panel portion spanning the panel wall, a line of weakness in the ledge, defining the removable portion covered by an annular portion of impervious material.
15. A can end according to any preceding claim wherein the metal surface to which the annular portion of impervious material is bonded is coated with a lacquer chosen from epoxy phenolic lacquer, epoxy polyester lacquer, a polyester phenolic lacquer, a polypropylene film or polyamidε film.
16. A can end according to any preceding claim wherein the material of the impervious annulus is chosen from polyvinyl chloride plastisols or organosols, polyvinyl chloride copolymer to give a closed cell structure, a film of polyamide, or film of polypropylene, a film of polyester or a metal foil.
17. A can end substantially as herein described and shown in Figures 2, Figures 3 to 6, Figure 7, Figures 8 to 10, Figures 11 and 12, Figure 13, Figure 14, Figure 15, Figure 16, Figure 17, Figure 18 or Figure 19 of the accompanying drawings.
PCT/GB1995/002050 1994-09-10 1995-08-31 Easy-open containers WO1996007593A1 (en)

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Applications Claiming Priority (2)

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GB9418290.4 1994-09-10
GB9418290A GB9418290D0 (en) 1994-09-10 1994-09-10 Containers

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EP1182140A1 (en) * 2000-03-06 2002-02-27 Crown Cork & Seal Technologies Corporation Food can end
EP1800770A1 (en) * 2005-12-23 2007-06-27 Crown Packaging Technology, Inc Can body with a sealing compound placed on a step or flange and method of forming such a can body
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US2601937A (en) * 1949-03-28 1952-07-01 Ottesen Andrew Receptacle cover
GB1512013A (en) * 1975-05-09 1978-05-24 Grise Frederick Gerard J Containers of the so-called easy-open type and closure members forming part of such containers
EP0268690A1 (en) * 1986-06-13 1988-06-01 Toyo Seikan Kaisha Limited Easy-to-open can lid able to protect cut edge of score and producing process thereof
EP0313149A1 (en) * 1987-10-19 1989-04-26 Michael John Mary Doyle End face with tear-away lip closure for pressurized container

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Publication number Priority date Publication date Assignee Title
WO1998003406A1 (en) * 1996-07-19 1998-01-29 Effem Gmbh Method of producing a filled container
US6325232B1 (en) 1996-07-19 2001-12-04 Effem Gmbh Process for producing a filled container and filled container
EP1182140A1 (en) * 2000-03-06 2002-02-27 Crown Cork & Seal Technologies Corporation Food can end
EP1800770A1 (en) * 2005-12-23 2007-06-27 Crown Packaging Technology, Inc Can body with a sealing compound placed on a step or flange and method of forming such a can body
WO2016142677A1 (en) * 2015-03-11 2016-09-15 Crown Packaging Technology, Inc. Ringless metal cans and method
EP3543157A1 (en) * 2015-03-11 2019-09-25 Crown Packaging Technology, Inc. Ringless metal cans
RU2713976C2 (en) * 2015-03-11 2020-02-11 Краун Пэкеджинг Текнолоджи, Инк. Can, suitable for use with detachable cover (embodiments), can body (embodiments) and method of processing can body
US11084632B2 (en) 2015-03-11 2021-08-10 Crown Packaging Technology, Inc. Ringless metal cans and method
JP2021181337A (en) * 2015-03-11 2021-11-25 クラウン・パッケージング・テクノロジー・インク Ringless metal can and method for producing the same
JP7098029B2 (en) 2015-03-11 2022-07-08 クラウン・パッケージング・テクノロジー・インク Ringless metal cans and their manufacturing methods

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Publication number Publication date
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GB9418290D0 (en) 1994-10-26
AU3392295A (en) 1996-03-27

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