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
  • B65D77/00—Packages formed by enclosing articles or materials in preformed containers, e.g. boxes, cartons, sacks or bags
  • B65D77/10—Container closures formed after filling
  • B65D77/20—Container closures formed after filling by applying separate lids or covers, i.e. flexible membrane or foil-like covers
  • B65D77/2024—Container closures formed after filling by applying separate lids or covers, i.e. flexible membrane or foil-like covers the cover being welded or adhered to the container
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
  • B65B7/00—Closing containers or receptacles after filling
  • B65B7/16—Closing semi-rigid or rigid containers or receptacles not deformed by, or not taking-up shape of, contents, e.g. boxes or cartons
  • B65B7/162—Closing semi-rigid or rigid containers or receptacles not deformed by, or not taking-up shape of, contents, e.g. boxes or cartons by feeding web material to securing means
  • B65B7/164—Securing by heat-sealing
• • 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
  • B65D1/00—Rigid or semi-rigid containers having bodies formed in one piece, e.g. by casting metallic material, by moulding plastics, by blowing vitreous material, by throwing ceramic material, by moulding pulped fibrous material or by deep-drawing operations performed on sheet material
  • B65D1/34—Trays or like shallow containers

Definitions

• the present invention relates to a container suitable for packaging foods therein and a process for covering such container with a film so that the film conforms to the contour of food which is packaged in the container.
• CPET is often viewed as being suitable for the manufacture of "dual-ovenable" containers, viz, suitable for use in both conventional oven and microwave oven applications.
• Thermoformed lids tend to be expensive to manufacture, partly because of the thickness of sheet used to manufacture such lids and the quantity of waste formed in the thermoforming process.
• Lids are an important component in food packages for the prepackaged food market, and have several functions. Rigid lids are useful for enabling food trays to be stacked, whether in card boxes or not. If sealed to the tray, lids may be used for form, with the tray, a hermetically sealed package. With aluminium or nylon trays, it is often necessary to use thermoformed lids with a snap-fit or to use a foil lid crimped to the tray, because it is not easy to seal materials thereto. Another type of lid may have a vacuum-induced and thermally-set crimp as disclosed in European Patent Publication No. 0282277 to Du Pont Canada Inc., published 1988 September 14.
• lids It is particularly desirable for lids to conform to the contours of the food in the container in order to minimize the air space between the food and the lid. Such air spaces contribute to the phenomenon known as freezer burn, which occurs when frozen food is stored for a substantial period in a freezer.
• the present invention attempts to provide a solution to the problem of freezer burn.
• the present invention provides a container made of a substantially gas impermeable material, said container comprising a floor, a circumferential wall attached to said floor, and a rim distal to the floor, wherein at least the rim and the wall have a plurality of grooves therein which extend from the rim towards the floor on the inside of the container.
• the grooves at least at the rim and adjacent thereto, have a width of from 0.25 mm to about 1.5 mm and a depth of from about 0.25 mm.
• the depth of the grooves is from 0.3 mm to about 0.5 mm, especially from 0.35 mm to 0.4 mm.
• the width of the grooves is from about 0.7 mm to 1.0 mm.
• each groove is 30 mm or less apart from an adjacent groove, preferably 6 mm or less apart from an adjacent groove, and especially 3 mm apart or less.
• the rim is in the form of a lip, circumferentially attached to the wall and which extends outwardly from and parallel to the floor.
• grooves extend to the outside of the container, at least part-way down the outside of the wall.
• the grooves extend to the outside of the container, at least part-way down the outside of the wall and such exterior grooves are offset from the grooves on the inside of the container.
• grooves on the inside of the container are in the form of letters or other design elements.
• the lips of at least some of the grooves are raised above the surface of the surrounding container material.
• the container is injection moulded, preferably from Nylon or polypropylene.
• the container is made from a thermosetting resin.
• the present invention also provides a method for packaging food, comprising the steps of:
• the process is carried out using a conventional "skin packaging" machine.
• the film is made from a polymer selected from amorphous polyester, partially crystalline polyester and mixtures thereof; amorphous polyester, partially crystalline polyester and mixtures thereof admixed with at least one compatibilized poly­olefin; and amorphous nylon and mixtures thereof with at least one compatibilized polyolefin, and is heated to a temperature of from 65 to 95°C in step c).
• the grooves at least at the rim and adjacent thereto, have a width of from 0.25 mm to about 1.5 mm and a depth of from about 0.25 mm.
• the depth of the grooves is from 0.3 mm to about 0.5 mm, especially from 0.35 mm to 0.4 mm.
• the width of the grooves is from about 0.7 mm to 1.0 mm.
• each groove is 30 mm or less apart from an adjacent groove, preferably 6 mm apart or less, and especially 3 mm apart or less.
• the rim is in the form of a lip, circumferentially attached to the wall and which extends outwards, parallel to the floor.
• grooves extend to the outside of the container, at least part-way down the outside of the wall.
• the grooves extend to the outside of the container, at least part-way down the outside of the wall and such exterior grooves are offset from the grooves on the inside of the container.
• grooves on the inside of the container are in the form of letters or other design elements.
• the lips of at least some of the grooves are raised above the surface of the surrounding container material.
• the container is injection moulded, preferably from nylon or polypropylene.
• the container is made from a thermosetting resin.
• Another aspect of the invention provides a food package comprising food contained in the aforementioned container, said container and food being covered with a lid comprising a film which substantially conforms to the exposed food and interior of the food-containing container.
• the container may be made from any suitable materia.
• the container may be made of aluminium, CPET or nylon, amongst other materials.
• CPET CPET
• ABS CPET
• nylon CPET
• Particularly suitable materials are disclosed in European Patent Application 0 231 663 published 1987 August 12, to D.H. Dawes and E.L. Fletcher.
• the lid may be made from films such as polyethylene, ionomer, amorphous polyethylene terephthalate, case, i.e. substantially unoriented, nylon, films.
• the film may also be in the form of a laminate or coextrusion.
• the film is preferably from 25 to 250 ⁇ m in thickness and, more preferably, from 50 to 105 ⁇ m.
• compatibilized polyolefin refers to olefin-based polymers having polar groups attached thereto which allow the olefin-based polymer and the nylon or polyester to be blended without phase separation.
• Such compatibilized olefin-based polymers may be in the form of so-called graft copolymers.
• the compatibilized olefin-based polymers may also be mixtures of compatibilized olefin-based polymers and olefin-based polymers which are incompatible with the nylon or polyester.
• incompatible polymers examples include homopolymers of ethylene or propylene, copolymers of ethylene and C4 to C10 alpha-olefins, polyisobutylene and poly(4-methylpentene-1).
• compatibilized olefin-based polymers include copolymers of ethylene and an unsaturated carboxylic acid or copolymers of ethylene and an unsaturated carboxylic acid ester monomer, e.g.
• ethylene/vinyl acetate copolymers ethylene/methylacrylate copolymers, ethylene/ethyl­acrylate copolymers, ethylene/n-butylacrylate copolymers, ethylene/methacrylate copolymers, ethylene/methacrylic acid copolymer and partially neutralized ethylene/methacrylic acid copolymers (ionomers); hydrocarbon alpha-olefins grafted with an unsaturated carboxylic acids or hydrocarbon alpha-olefins grafted with an unsaturated anhydride, e.g.
• ethylene/acrylate ester copolymer grafted with an unsaturated carboxylic acid or unsaturated anhydride ethylene/C4 to C10 alpha-olefin copolymers grafted with unsaturated carboxylic acids or ethylene/C4 to C10 alpha-olefin copolymers grafted with an unsaturated anhydride, ethylene homopolymers grafted with an unsaturated carboxylic acid and ethylene homopolymers grafted with an unsaturated anhydride.
• the preferred unsaturated carboxylic acid and unsaturated anhydride are maleic acid and maleic anhydride.
• Such compatibilized polyolefin materials must, of course, be compatible with the polyesters, e.g. polyethylene terephthalates, or nylons useful in this invention.
• Suitable apparatus for carrying out the process of the present invention is available from a number of commercial suppliers.
• One such apparatus is manufactured by Allied Automation Inc. of Texas, U.S.A.
• the film which is to be used for the lid, is pulled from a roll and held in a frame.
• the frame is larger than the plan-form of the container which is to be lidded.
• the framed film is heated from about with, for example, hot wire heating elements or infra-red lamps.
• the film tends to soften and sag slightly when the film is hot enough for the next step int he process.
• the frame, with film is caused to descend onto a container which is filled with food and which is positioned on a platen having holes therein. The heating is then stopped and vacuum is applied from beneath the platen. The heat-softened film is pulled downwards, around the lip of the container.
• the vacuum is such that, because of the presence of the grooves in the container, it is able to suck air from below the film in the container thereby pulling the film into conformity with the food within the container and into conformity with the walls and rim of the container.
• the container is sealed by the film then conforming to a smooth surface of the container and/or conforming to and blocking the grooves.
• the film is sucked closely into contact with the upper and lower surface of the lip.
• the vacuum is then released, the frame is permitted to release the film and the thus-lidded container is transported away from the platen. Any excess film may then be trimmed, and the frame grasps more film so that the next cycle of the process may take place. Some of the excess film may be left in place, to act as a pull-tab for removal of the lid.
• the grooves are not too shallow in relation to the width of the grooves; other­wise the firm is likely to block the groove when it is first drawn into conformity with the container. Such blockage is likely to prevent the film from conforming with the food.
• the grooves should not have a depth of more than about half of the wall thickness. For example, for nylon containers having a wall thickness of about 0.76 mm, the grooves in the containers should be less than about 0.40 mm. In any event, in terms of operational efficiency, there is less and less benefit to having deeper grooves.
• the grooves should not be wider than about 1.5 mm and preferably be between about 0.5 and 0.75 mm in width. It is preferable, also, that the grooves extend from the inside of the container to the outside, e.g. down the outside walls of the container, as the process causes film to be drawn over the outside of the container walls. Although not necessary, it is preferable for the grooves to extend to the centre of the floor of the container. This permits faster evacuation of the air fromthe container.
• the grooves extend radially across the floor of the container and up the walls, in straight lines, it is not necessary that they do so.
• the grooves may form a pattern e.g. arcuate, sinusoidal, provided that there is a route along which air may travel from the container during the lidding process.
• the pattern may be regular, as for example in a star burst pattern, or may be irregular, as for example in letters or cursive writing.
• the cross-sectional shape of the grooves is unimportant and may be, for example U-shaped or V-shaped.
• it is not necessary that the cross-sectional area of the groove remain the same along the length of the groove, e.g. it may taper.
• the shape of the container may vary considerably, although it will normally be of such a shape as can be used for serving food. It is normal to have the container in a tray shape. In plan-form it may be circular, oval, rectangular or kidney-shaped.
• the container may also be compartmentalized so that different types of food, e.g. meat, potatoes, vegetables, may be kept separated.
• the lips of the grooves may be raised above the surface of the surrounding material of the container. This may be accomplished by having raised areas on the container surface, e.g. raised strips, which have the grooves formed or cut therein. It is preferable that the raised strips join smoothly with the surrounding material. Raised strips with grooves therein are particularly useful when the container thickness would not, by itself, permit use of sufficiently deep grooves for the lidding process to occur quickly and efficiently, without compromising the structural integrity of the container.
• the raised portions would provide the extra thickness to strengthen the container at the grooved portion and thus provide such structural integrity.
• the raised areas would normally be no more than about 1 mm above the surrounding container material.

Landscapes

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

Applications Claiming Priority (2)

Publications (1)

Family

ID=10634059

Family Applications (1)

Country Status (2)

Cited By (2)

• 1988
  • 1988-03-24 GB GB888807060A patent/GB8807060D0/en active Pending
• 1989
  • 1989-03-23 EP EP19890302955 patent/EP0334670A2/de not_active Withdrawn

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