Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D51/00—Making hollow objects
  • B21D51/16—Making hollow objects characterised by the use of the objects
  • B21D51/38—Making inlet or outlet arrangements of cans, tins, baths, bottles, or other vessels; Making can ends; Making closures
  • B21D51/44—Making closures, e.g. caps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D51/00—Making hollow objects
  • B21D51/16—Making hollow objects characterised by the use of the objects
  • B21D51/38—Making inlet or outlet arrangements of cans, tins, baths, bottles, or other vessels; Making can ends; Making closures
  • B21D51/383—Making inlet or outlet arrangements of cans, tins, baths, bottles, or other vessels; Making can ends; Making closures scoring lines, tear strips or pulling tabs
• • 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
  • B65D17/4011—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 for opening completely by means of a tearing tab

Definitions

• the present invention relates to a method for producing tear-open lids from a metal sheet with a surface protection layer applied on one or both sides and a handle bottle, embossing lines for a plurality of lids being produced first on a sheet metal sheet or on a sheet metal strip, and then on the pre-embossed sheet metal sheet or a surface protective layer is applied to the pre-embossed sheet metal strip and then the tear-open covers are punched out.
• the invention further relates to the tear-open covers produced by this method.
• Tear-off lids made of a metal sheet are used for easy opening of packaging, such as cans or beverage cans.
• embossing lines are incised into the metal sheet used to produce the tear-open covers.
• the tear-open lids have a handle bottle, with the help of which the sheet is torn open along the embossing lines.
• embossing or scoring process leads to damage to the surface protective layer, which can consist of tinning or a lacquer layer. This damage leads to undesirable signs of corrosion. As a result, it is necessary to repaint the damaged areas, which is associated with a considerable additional outlay.
• DE-AS 20 10 631 discloses a method for producing tear-open lids from sheet metal, in which the lids are punched out from a blank provided with a protective layer and provided with embossing lines and a handle bottle.
• the embossing lines for a large number of lids are first embossed on a common sheet metal strip or on a common sheet metal sheet, then a surface protective layer is applied on one or both sides, preferably by roller coating, only after that punching out the covers.
• the known method has the advantage that the surface protective layer applied for better corrosion protection cannot be applied separately for each individual lid, but together for a large number of tear-open lids, by coating the entire metal sheet or the entire metal sheet, preferably roller painting , is subjected. It is particularly advantageous that the tear-open covers punched out of the metal strips or metal sheets no longer require any further treatment. Only relatively weak presses are required for punching out the tear-open lids from the previously coated metal strips or metal sheets, while the strong presses required for producing the embossing lines are used centrally, where their use is worthwhile because of the larger numbers of pieces that are produced .
• the disadvantages of the process known from DE-AS 20 10 631 are that the lacquers used to produce the surface protection layer have a high proportion of organic solvents. For environmental protection reasons, this is to be regarded as a serious disadvantage.
• the applied lacquers require complex drying processes, since the lacquers are cured and the solvents contained therein have to be evaporated.
• the object on which the present invention is based was to provide an efficient and environmentally friendly method for producing tear-open lids which contain a grip bottle. This should be a largely solvent-free manufacturing process, ie the generation of a lacquer layer on the metal sheet should be solvent-free. In addition, the complex drying times associated with solvent-based paints should fall, be avoided. The production of the embossed lines should take place for a large number of tear-open covers on a common sheet metal strip or on a common sheet metal sheet.
• the object on which the present invention is based is surprisingly achieved by a method for producing tear-open lids from a metal sheet with a surface protection layer applied on one or both sides and a handle bottle, initially with embossing lines for a large number on a sheet metal sheet or on a sheet metal strip are produced by lids on a common metal sheet, after which a surface protective layer is applied to the pre-embossed metal sheet or to the pre-embossed metal sheet strip, and the tear-open lids are then punched out.
• the process according to the invention is characterized in that a thermoplastic film is laminated as a surface protective layer on the metal sheet or on the sheet metal strip.
• the metal sheets used have a thickness of 0.04 to 1 mm, and they consist of black sheet, tinplate, aluminum and various iron alloys, which are optionally provided with a passivation layer based on nickel, chromium and zinc compounds.
• the thickness of the metal sheets is preferably in the range from 0.20 to 0.50 mm.
• stamping lines for a large number of lids are first produced on these metal sheets by scoring.
• the sheet metal strips or the sheet metal plates are then coated with a thermoplastic plastic film.
• a thermoplastic plastic film can also be a composite plastic film that is obtained by extruding different plastics together.
• the thermoplastic plastic films are produced from granules of the plastics by known processes (blowing process, chill-roll process, etc.). Foil coating of metal sheets is a generally known method, it is described, for example, in DE-A-31 28 641.
• a metal sheet and a thermoplastic film are usually made using an adhesion promoter or an adhesive using pressure and Temperature pressed, whereby the metal-plastic film composite is produced.
• a solvent-containing or aqueous adhesive is usually used, or an adhesion-promoting plastic (adhesion promoter) is coextruded together with the plastic that is to be used for the plastic film .
• an adhesion-promoting plastic adheresion promoter
• the gluing of a plastic film onto a metal sheet by means of an adhesive is known for example from EP-A-199 228.
• Composites of metal foils with A large number of thermoplastic foils, an adhesion promoter layer being arranged for adhesion between the metal foil and the plastic foil are known. Acid-modified polypropylenes, for example, are used as adhesion promoters. Such composites are described, for example, in EP-A-101 250 and EP-A-312 306.
• the following plastics can advantageously be used to produce the thermoplastic plastic film: polyolefins, polyesters, polyamides and polyurethanes. Films and films made from these plastics are known and are available in a large number on the market. Polyethylene low density (PE-LD), medium density (PE-MD), high density (PE-HD), linear low and linear very low density polyethylene (PE-LLD, PE-VLD) are suitable for the production of the plastic films.
• PE-LD Polyethylene low density
• PE-MD medium density
• PE-HD high density
• PE-LLD linear low and linear very low density polyethylene
• PE-LLD linear very low density polyethylene
• Polypropylenes their copoly ere with ethylene and other monomers as well as the copolymers of ethylene and propylene with one or more comonomers from the group of vinyl esters, vinyl alkyl ethers, unsaturated mono- and dicarboxylic acids, their salts, anhydrides and esters.
• These polyolefins are commercially available, for example, under the following brand names: Escorene, Lupolen, Lotader, Laqtene, Orevac, Dowlex, Primacor, Surlyn, Admer, Sclair, Stamylan.
• polyamide plastics examples include polyamide 6 (polyamide made from C-aminocaproic acid), polyamide 6.6 (polyamide made from hexamethylene diamine and sebacic acid), polyamide 66.6 (mixed polyamide made from polyamide 6 and polyamide 6.6 consists), polyamide 11 (polyamide, made from U-aminodecanoic acid) and polyamide 12 (polyamide, made from-aminolaurine) acid or from lauryl lactam).
• suitable commercial products are Grilon, Snia id and Ultramid.
• polyester plastics are polyethylene terephthalate and polybutylene terephthalate as well as other polyesters based on terephthalic acid, isophthalic acid and phthalic acid and various polyols, such as e.g. Polyethylene glycol and polytetramethylene glycols have different degrees of polymerization.
• suitable commercial products are Hostaphan®, Melinex *, Hostadui® and Ultradur®.
• thermoplastic film is particularly preferably laminated onto the metal sheet or sheet metal strip at elevated temperatures by means of a coextruded adhesion promoter.
• a coextruded adhesion promoter is particularly preferred, since in this case no organic solvents are used.
• thermoplastic plastic film made from propylene homopolymer and / or propylene copolymer is particularly preferably used to produce the surface protective layer, an acid-modified polypropylene preferably being used as the adhesion promoter.
• the polypropylene for the production of the plastic film are commercially available propylene homopolymers, propylene random copolymers and propylene block copolymers which are commercially available, for example, under the name Novole ⁇ ö '(BASF AG). Such polypropylenes are described, for example, in DE-A-37 30 022.
• the as an adhesion promoter or adhesives for manufacturing can be both copolymers, terpolymers, graft copolymers and ionomers with the proviso that they have carboxyl or anhydride groups or groups which can be hydrolyzed to carboxyl groups.
• Suitable copolymers or terpolymers can be prepared by copolymerization, for example of ethylene or propylene with ⁇ , ⁇ -ethylenically unsaturated carboxylic acids, such as, for example, acrylic acid, methacrylic acid, itaconic acid, Lacic acid, isocrotonic acid, maleic acid and fumaric acid, the corresponding anhydrides or the corresponding esters or half-esters with 1 to 8 carbon atoms in the alcohol radical.
• the corresponding salts of the carboxylic acids listed can also be used.
• the carboxylic acids or their anhydrides are particularly preferably used.
• the amounts of the monomers used are chosen so that the resulting polymer has a carboxyl group content of 0.1 to 30% by weight.
• Polymers suitable for producing the adhesion promoter layer or the adhesive layer are furthermore graft copolymers which can be produced by grafting at least one polymer from the group of the polyolefins with up to 10% by weight, based on the total weight of the monomers, of at least one monomer from the group of ⁇ , ⁇ -ethylenically unsaturated
• Carboxylic acids their anhydrides, their esters or salts in the presence or absence of peroxides.
• Both the adhesion promoter layer and the thermoplastic plastic layer can also contain conventional additives such as. B. contain internal and external lubricants, anti-blocking agents, stabilizers, antioxidants, pigments, crystallization aids and the like. These additives are used in the manufacturing, processing, packaging and application Amounts in the form of powder, powder, pearls or a concentrate incorporated directly into the corresponding polymer. More detailed information on the amounts conventionally used and examples of suitable additives can be found, for example, in Gumbleter-Müller, Kunststoffadditive, Carl-Hanser Verlag.
• the thermoplastic film can be applied to the pre-embossed metal strip or to the pre-embossed metal sheet on one or both sides.
• the layer thickness of the thermoplastic plastic film (without adhesive layer or adhesive layer) is advantageously 10 to 200 ⁇ m, particularly preferably 40 to 100 ⁇ m. Since the layer thickness of the film can be varied easily and without problems according to the present method, and thus higher layer thicknesses of the surface protective layer can also be achieved, an otherwise commonly used sealing compound can be saved in the tear-open covers if necessary.
• relatively thin sheet metal sheets or relatively thin sheet metal strips can be used to produce the tear-open covers if a correspondingly thicker plastic film is used to produce the surface protective layer.
• the tear-open covers are punched out of the pre-embossed sheets or sheets provided with the laminated plastic film.
• the handle bottle required for tearing is attached to the lid after punching, for example by spot welding or, if necessary, by soldering. Spot welding is carried out on the top or outside of the cover with a double electrode, as is used for spot welding coated surfaces.
• the thermoplastic plastic film is applied at least to the top of the lid facing the filling material.
• the method according to the invention for the production of tear-open lids with a grip bottle is a largely solvent-free and thus environmentally friendly production method.
• the tear-open lids can be produced economically, since the drying times that are otherwise common with paints are eliminated.
• thermoplastic plastic films By using the thermoplastic plastic films to produce the surface protective layer, it is possible to emboss the embossing lines more strongly, ie to produce deeper cracks, since the thermoplastic plastic films are generally more elastic than conventional lacquer systems.
• the more developed embossed lines result in better opening values of the tear-open covers.
• the tear-open lids for closing cans the otherwise customary use of sealing compounds on the inside of the lids can be dispensed with without loss of tightness occurring.
• the method according to the invention makes it possible to use pre-printed plastic films for the production of the tear-open covers, the printing of the films, which, for. B. can be done in the flexographic printing process, can already be carried out at the film manufacturer.
• printing on the lacquer surface can of course only take place after the tear-open cover has been produced in an additional separate method step.
• the method according to the invention is therefore particularly advantageous with regard to the production of printed tear-open lids for reasons of process economy.
• the present invention also relates to tear-open covers which are obtained by the production process described above.
• FIG. 1 schematically demonstrates the structure of a coated metal sheet for the production of tear-open covers according to the present invention.
• a thermoplastic coextrusion film is laminated on both sides of the pre-embossed metal sheet.
• the thermoplastic coextrusion film consists of an adhesion promoter layer made of polypropylene grafted with maleic anhydride and a layer made of polypropylene plastic (trade name Novolen® 3225 MCX from BASF AG).
• a coextruded plastic film is produced from the polypropylene Novoleri® 3225 MCX (BASF AG; layer thickness 30 ⁇ m) and polypropylene, which is grafted with maleic anhydride (adhesion promoter; layer thickness 10 ⁇ m).
• the coextruded plastic film is laminated on both sides to the pre-embossed aluminum sheet at a temperature of 190 ° C.
• the metal-plastic film composite is then cooled in a water bath (temperature 10 ° C.).
• the coated aluminum sheet is punched lid.
• the tear-open covers have very good corrosion protection properties.
• the lid is checked for its tear behavior. Very good properties can also be found here.

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

Applications Claiming Priority (3)

Publications (1)

Family

ID=6474104

Family Applications (1)

Country Status (8)

Families Citing this family (5)

• 1992
  • 1992-12-01 DE DE4240373A patent/DE4240373A1/de not_active Withdrawn
• 1993
  • 1993-11-20 EP EP94901826A patent/EP0673315A1/de not_active Ceased
  • 1993-11-20 CA CA002150009A patent/CA2150009A1/en not_active Abandoned
  • 1993-11-20 WO PCT/EP1993/003245 patent/WO1994012348A1/de not_active Application Discontinuation
  • 1993-11-20 BR BR9307562A patent/BR9307562A/pt not_active Application Discontinuation
  • 1993-11-26 YU YU73893A patent/YU73893A/sh unknown
  • 1993-11-30 CO CO93420615A patent/CO4180430A1/es unknown
• 1995
  • 1995-05-31 NO NO952157A patent/NO301266B1/no unknown

Non-Patent Citations (1)

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