EP0531039A1 - Öffnungsvorrichtung in Behälterendwand - Google Patents

Öffnungsvorrichtung in Behälterendwand Download PDF

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Publication number
EP0531039A1
EP0531039A1 EP92307759A EP92307759A EP0531039A1 EP 0531039 A1 EP0531039 A1 EP 0531039A1 EP 92307759 A EP92307759 A EP 92307759A EP 92307759 A EP92307759 A EP 92307759A EP 0531039 A1 EP0531039 A1 EP 0531039A1
Authority
EP
European Patent Office
Prior art keywords
plastisol
aperture
weakness
line
closure
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
EP92307759A
Other languages
English (en)
French (fr)
Inventor
John Sidney Hewitt
Arthur John Gunstead
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
WR Grace and Co Conn
WR Grace and Co
Original Assignee
WR Grace and Co Conn
WR Grace and Co
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 WR Grace and Co Conn, WR Grace and Co filed Critical WR Grace and Co Conn
Publication of EP0531039A1 publication Critical patent/EP0531039A1/de
Ceased legal-status Critical Current

Links

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
    • B65D17/00—Rigid or semi-rigid containers specially constructed to be opened by cutting or piercing, or by tearing of frangible members or portions
    • B65D17/28—Rigid 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
    • B65D17/401—Rigid 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 characterised by having the line of weakness provided in an end wall

Definitions

  • This invention relates to container closures having a panel that includes an aperture that during use is maintained closed, but that can be opened to allow the removal of the contents of the container.
  • Containers such as cans and bottles are provided with a closure that often comprises a metal panel.
  • a closure that often comprises a metal panel.
  • substantially the entire closure should be removed in order to open the container, but in other instances it is intended that opening should be achieved by displacing part or all of the panel, the remainder of the closure being left on the container.
  • a line of weakness is provided in the panel around the edges of a desired aperture in the panel and this aperture is covered by a displaceable tab.
  • the tab is displaced, either by pulling or pushing, so as to open the aperture.
  • the displacement of the tab may involve total removal of the tab, or it may be displaced into an open hinged position.
  • the line of weakness is formed by scoring or stamping the metal or other panel and a ring pull or other holding means is provided for pulling the area defined by the line of weakness as a tab from the panel when it is desired to open the aperture.
  • the scoring, stamping or other operation that is used to form the line of weakness should not disrupt the continuity of the material of the closure, with the result that leakage of the contents of the container should be incapable of occurring through the line of weakness.
  • the stamping, scoring or other operation that is used to form the line of weakness is liable to disrupt the continuity of any lacquer, laminated polyester film or other protective coating on the inner face of the closure and this can lead to corrosion.
  • the line of weakness can potentially allow for leakage to occur from the container. This can be due to accidental disruption of the material of the panel, but in some instances it is deliberate.
  • the layer of polymeric material is a layer of gelled PVC plastisol that has been formed by applying a fluid PVC plastisol and then gelling it.
  • the layer may be in the form of a disc but often is in the form of a ring covering the line of weakness.
  • GB 2,197,634 describes a container closure in which the removable tab is hinged to the panel and the edges of the tab overlie and are separated from the edges of the aperture and defines the requirements of the PVC plastisol that should be used.
  • PVC plastisol that has a viscosity of 2,000 to 2,800 mPa.s at 40°C when measured at a shear of 441 seconds ⁇ 1.
  • Other necessary properties are also defined.
  • a container closure according to the invention comprises a closure panel, a line of weakness in the panel around the edges of an aperture in the panel that is covered by a displaceable tab, and a layer of gelled plastisol that covers the line of weakness and seals against corrosion and/or leakage through the line of weakness and which has been formed by applying on to the line of weakness a fluid plastisol of polymeric material and then gelling the plastisol.
  • the polymeric material of the plastisol is free of polyvinyl chloride and the fluid plastisol has a viscosity that is below 2,000 mPa measured at a shear of 441 seconds ⁇ 1 and 40°C and that is in the range 200 to 1,800 mPa at 100 seconds ⁇ 1 and 43°C.
  • the invention also includes containers fitted with the closure end and, in particular, sealed containers containing a beverage or foodstuff, methods in which the plastisol is lined on to the closure and then gelled, and plastisol for use in these methods.
  • the container can be a bottle, for instance of glass or organic polymeric material, in which event the closure can be a bottle cap. More usually, the container is a can, in which event the closure will be a can end.
  • the can and/or can end could be of polymeric material but generally both are of metal.
  • fillings can be stored within the container but preferably the filling is a foodstuff or beverage.
  • the filling is one that is packed under pressure and so the invention is of particular pressure when the filling is a carbonated beverage, especially beer.
  • the line of weakness may be a score line or press line that defines a tab provided with a ring pull or other means for removal or hinging, as described above.
  • the invention is then primarily of use for preventing corrosion of the inner face of the closure.
  • the displaceable tab is hinged to the panel, the edges of the tab overlie and are separated from the edges of the aperture, and the layer of gelled plastisol seals between the edges of the tab and the aperture.
  • the layer of gelled plastisol generally also extends over the edges of the tab and the parts of the panel that surround the edges of the tab. The plastisol will therefore prevent leakage between the tab edges and the aperture edges, and will also seal against corrosion initiating at the edges.
  • the tab is positioned on the inner face of the closure and the closure is intended for a pressurised container (such as beer) since the internal pressure then forces the tab against the panel.
  • a pressurised container such as beer
  • the aperture can be opened by pressing the tab inwardly.
  • the tensile strength and elongation values of the gelled plastisol should be selected having regard to the size of the aperture such that it is possible to open the aperture by the application of convenient finger or thumb pressure.
  • the aperture is often relatively small (typically in the range 5 to 20mm diameter) and suitable opening forces are typically in the range 10 to 60N. In order to obtain these values it is then convenient for the gelled plastisol to have a tensile strength of about 0.4 to 1N/mm2 and a maximum elongation of about 120 to 250%.
  • the gelled plastisol is preferably such that the opening force required for the pouring aperture is about 20 to 60N preferably 20 to 40N or 20 to 30N while the opening force for the venting aperture is about 10 to 40N preferably 15 to 25N.
  • the opening force is determined when there is no counter pressure.
  • the fluid plastisol should have a viscosity of below 1,500mPa at 100s ⁇ 1 and 43°C.
  • the viscosity under these conditions is at least 250mPa and preferably at least 400mPa.
  • the viscosity measured at 40°C and 441 sec ⁇ 1 typically is also below 1500mPa but above 200mPa.
  • Plastisols for use in the invention comprise a dispersion of thermoplastic polymeric particles in a liquid organic plasticiser into which the particles will dissolve on heating to form a gelled structure.
  • the polymeric component preferably comprises a homopolymer or copolymer of an acrylic ester or a copolymer of an olefin with maleic anhydride or blends of these or blends of either or both of these with other polymers that are free of polyvinyl chloride.
  • Suitable polymers are copolymers of styrene and/or alkyl styrene (e.g., ⁇ -methyl styrene) with unsaturated carboxylic acid such as methacrylic acid.
  • Suitable maleic anhydride copolymers are those disclosed in U.S. 4,020,966, comprising copolymers of normal ⁇ -olefin and maleic anhydride in a one to one molar ratio in suspension in a polyepoxide plasticiser, for example epoxidised soy bean oil.
  • Suitable acrylic ester copolymers include those described in U.S. 4,199,486 and comprise homo- or copolymers of methyl methacrylate as the resin, in suspension in organic plasticisers such as phthalate plasticiers, for example dioctylphthalate or dibutylphthalate.
  • Suitable acrylate polymers include homo- or copolymers of alkyl methacrylates and alkylacrylates with methacrylic acid esters with C2 to 10 aliphatic alcohol, acrylic acid esters with C1 to 10 aliphatic alcohol, styrene and/or a-methyl styrene.
  • Suitable alkyl acrylates or alkyl methacrylates include methyl methacrylate, tertiary butyl acrylate, ethyl methacrylate, N-propyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, s-butyl methacrylate, t-butyl methacrylate or cyclohexyl methacrylate.
  • plasticiser suitable for the particular polymer or polymer blend may be used, and it should be capable of solvating or dissolving the polymer or polymer blend when heated and of remaining essentially compatible on cooling.
  • suitable materials from which the plasticisers may be selected include, for example, dialkyl phthalates such as dibutyl, diisodecyl, dioctyl, diethylhexyl or octyldecyl phthalate; alkylphthalylalkyl glycolate, such as ethylphthalyl glycolate and butylphthalylbutyl glycolate; dialkyl esters of alkane dicarboxylic acids such as diisobutyladipate and dibutylsebacate, acetyltrialkyl citrates, such as acetyltributyl citrate; trialkyl and triaryl phosphates such as trioctyl phosphate and tricresyl phosphate; alkyl esters of
  • the amount of plasticiser used in the plastisol composition may for example be between 60 and 300 , preferably 80 to 200, phr (parts by weight per 100 parts by weight of the resin).
  • the non-PVC plastisols used in the invention may also comprise filler materials such as aluminium trihydrate, barytes, china clay, chalk, kaolin, mica flour, wood flour and diatomaceous earth.
  • filler materials such as aluminium trihydrate, barytes, china clay, chalk, kaolin, mica flour, wood flour and diatomaceous earth.
  • the amount typically is in the range 60 to 600, often 100 to 400, phr.
  • the plastisol may, if desired, comprise a finely divided suspension of particles comprising a core material which reacts well with the plasticiser to form a suitable seal after fluxing, and a shell material which is less readily able to react with the plasticiser and which prevents contact between the plasticiser and the core material until the plastisol is heated to flux it.
  • the plasticiser or plasticisers and any other components in the plastisol it is possible to formulate a plastisol that after gelling will give a gelled layer having elongation and tensile strength values that are suitable for the intended use of the composition.
  • Such fluid plastisols are liable to have too high a viscosity for use in the invention and so it is generally necessary to include a viscosity depressant.
  • This is normally selected from one or more volatile diluents, emulsifiers and protective colloids.
  • Suitable volatile diluents include low boiling olefinic hydrocarbons such as C10-C16 hydrocarbons.
  • Suitable emulsifiers include salts or esters of fatty acids, ethylene oxide condensates with alkyl phenyls and fatty alcohols, zinc resinate and zinc/magnesium octoate.
  • Suitable protective colloids include lecithin.
  • the amount will be selected according to the other components in the composition and the desired viscosity at the conditions of application, but is generally in the range 5 to 100, usually 10 to 50, phr.
  • compositions can contain other conventional additives, for instance pigments such as carbon black and titanium dioxide.
  • the formulation of the plastisol is preferably such that, having regard to the lacquer or other surface characteristics of the closure, the plastisol wets the surface adequately, for instance forming an edge angle of around 30 to 40°.
  • the plastisol can be applied through a ring nozzle as described in DE 2,421,315 or by other suitable lining apparatus to a thickness as described in GB 2,197,634.
  • the closure carrying it is then subjected to heating in order to cause gelling and fluxing of the plastisol.
  • This generally requires exposure to a temperature of 150 to 250°C for from 5 seconds to 10 minutes. Often the temperature is in the range 180 to 230°C and the time is often in the range 1 ⁇ 2 to 2 minutes.
  • a fluid plastisol is formulated from (in parts by weight) MMA/BMA carboxylated copolymer (Paste grade) 70 MMA/BMA copolymer (Filler grade) 30 Aluminium trihydrate 200 Barytes 60 Titanium dioxide 3 Diethyl hexyl phtalate 100 Volatile diluent (tetradecene) 28 Protective colloid (lecithin) 5 Emulsifiers (blend of Zn/Mg octoate and ethoylated nonyl phenol) 4.5 MMA/BMA stands for copolymer of methyl methacrylate and butyl methacrylate. This composition has a viscosity of 690mPa at 441 seconds ⁇ 1 and 40°C and 600mPa at 100 sec ⁇ 1 and 43°C.
  • a can end is provided with a pouring aperture about 16mm in diameter and a venting aperture about 8mm in diameter, and each aperture has a hinged tab covering it, of slightly larger diameter so that the edges of the tab overlie the edges of the associated aperture, with the tab on the side of the can end that has been coated with lacquer and that is intended to be inside the can.
  • the general arrangement is described in GB 2,197,634.
  • the plastisol is applied as a ring around each aperture, as described in GB 2,197,634 to give coatings having a thickness of 0.5mm at the pouring aperture and 0.4mm at the vent ring aperture and which extend between the adjacent edges of the associated apertures and tabs.
  • the lined can end is then heated to a temperature of 210°C for 1 minute in order to flux and gel the plastisol.
  • the force required to open the pouring and venting apertures is 30N and 17N respectively.
  • Two fluid plastisols are formulated from (parts by weight):-
  • compositions have the following viscosities (in mPa):- A B 441 sec ⁇ 1 at 40°C 909 325 100 sec ⁇ 1 at 43°C 1042 407
  • Viscosities in mPa

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Containers Opened By Tearing Frangible Portions (AREA)
  • Closures For Containers (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
EP92307759A 1991-09-04 1992-08-26 Öffnungsvorrichtung in Behälterendwand Ceased EP0531039A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB919118890A GB9118890D0 (en) 1991-09-04 1991-09-04 Container closure
GB9118890 1991-09-04

Publications (1)

Publication Number Publication Date
EP0531039A1 true EP0531039A1 (de) 1993-03-10

Family

ID=10700874

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92307759A Ceased EP0531039A1 (de) 1991-09-04 1992-08-26 Öffnungsvorrichtung in Behälterendwand

Country Status (6)

Country Link
EP (1) EP0531039A1 (de)
JP (1) JPH05213350A (de)
AU (1) AU646970B2 (de)
CA (1) CA2076460A1 (de)
GB (1) GB9118890D0 (de)
ZA (1) ZA926287B (de)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4199486A (en) * 1977-05-20 1980-04-22 Rohm Gmbh Plastisols comprising copolymers of methyl methacrylate
GB2197634A (en) * 1986-11-18 1988-05-25 Rasselstein Ag Ends for pressurized cans

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4020966A (en) * 1975-03-28 1977-05-03 W. R. Grace & Co. Plastisol composition and container closure gasket made therefrom

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4199486A (en) * 1977-05-20 1980-04-22 Rohm Gmbh Plastisols comprising copolymers of methyl methacrylate
GB2197634A (en) * 1986-11-18 1988-05-25 Rasselstein Ag Ends for pressurized cans

Also Published As

Publication number Publication date
CA2076460A1 (en) 1993-03-05
AU646970B2 (en) 1994-03-10
ZA926287B (en) 1993-03-03
AU2207392A (en) 1993-03-11
GB9118890D0 (en) 1991-10-23
JPH05213350A (ja) 1993-08-24

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