EP1524202A1 - Warmgeformter Kunststoffbehälter und Verfahren zu dessen Herstellung - Google Patents

Warmgeformter Kunststoffbehälter und Verfahren zu dessen Herstellung Download PDF

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Publication number
EP1524202A1
EP1524202A1 EP03023337A EP03023337A EP1524202A1 EP 1524202 A1 EP1524202 A1 EP 1524202A1 EP 03023337 A EP03023337 A EP 03023337A EP 03023337 A EP03023337 A EP 03023337A EP 1524202 A1 EP1524202 A1 EP 1524202A1
Authority
EP
European Patent Office
Prior art keywords
container
base
raised features
mould
hollow raised
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.)
Withdrawn
Application number
EP03023337A
Other languages
English (en)
French (fr)
Inventor
Morris John Field
Steven Mark Long
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.)
Cryovac LLC
Original Assignee
Cryovac LLC
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 Cryovac LLC filed Critical Cryovac LLC
Priority to EP03023337A priority Critical patent/EP1524202A1/de
Priority to ES04022757T priority patent/ES2342598T3/es
Priority to EP20040022757 priority patent/EP1544129B1/de
Priority to AT04022757T priority patent/ATE466789T1/de
Priority to DE602004026987T priority patent/DE602004026987D1/de
Publication of EP1524202A1 publication Critical patent/EP1524202A1/de
Withdrawn legal-status Critical Current

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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
    • B65D81/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents
    • B65D81/02—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents specially adapted to protect contents from mechanical damage
    • 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
    • B65D85/00—Containers, packaging elements or packages, specially adapted for particular articles or materials
    • B65D85/30—Containers, packaging elements or packages, specially adapted for particular articles or materials for articles particularly sensitive to damage by shock or pressure
    • B65D85/34—Containers, packaging elements or packages, specially adapted for particular articles or materials for articles particularly sensitive to damage by shock or pressure for fruit, e.g. apples, oranges or tomatoes

Definitions

  • the present invention relates to a thermoformed plastic container, useful for the packaging of soft products that might be easily bruised, and to the process for the manufacture thereof.
  • thermoformed plastic container for soft food and non food products, which container comprises a base portion and sidewalls extending upwardly from the periphery of the base portion, and is characterised in that said base portion is thermoformed in such a way that an array of hollow raised features with a flexible upper portion (also called here “soft caps”), project upwardly therefrom.
  • the container of the present invention will thus be characterised by a base or a part of it that is softened by the presence of these soft caps projecting towards the inner cavity of the container, and will therefore be particularly useful for the packaging of easily bruised products.
  • a protective pad of e.g. non woven material or air cushioning material such as Bubble-Wrap® , glued to the base portion which is used to prevent the damage to the products by the rigid base of the container.
  • a separate protective pad presents however several drawbacks. It is in fact necessary to provide for an additional, separate and dedicated step, in the product packaging process or in the process for the manufacture of the container, to position the separate pad into the container. This will bring about an increase in the overall cost of the process that will add up to the increase due to the cost of the separate pad and of the glue used to keep the separate pad in place. Finally, the use of a separate protective pad might give problems of recycling in case the protective pad cannot be recycled together with the container or if the glue employed for binding the pad to the container cannot be recycled.
  • a first object of the present invention is therefore a one-piece thermoformed plastic container with a base portion and sidewalls extending upwardly from the periphery of said base portion said container being characterised in that the base comprises an array of hollow raised features having an upper flexible portion projected upwardly from said base.
  • a second object of the present invention is the thermoforming process that is designed for the manufacture of the one-piece plastic container of the first object.
  • a third object of the present invention is a package of a soft product wherein the soft product is loaded into a container according to the first object of the present invention and the package is closed by lidding or wrapping the filled container.
  • the base (10) of the container (1) of the present invention comprises an array of hollow raised features (11) that are obtained in the thermoforming step.
  • each hollow raised feature is characterised by a flexible upper portion which is obtained by the thinning of the plastic web, with respect to the plastic web of the base portion, due to the thermoforming stretching.
  • the thermoforming process in fact those parts that have been stretched the least are the thickest while those that have been stretched the most are the thinnest.
  • the upper portion of the raised features will have to be less than 100 ⁇ m, preferably less than 90 ⁇ m and more preferably less than 80 ⁇ m thick, such as 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70 or 75 ⁇ m thick.
  • the width of the raised features expressed as the diameter of the hemisphere or cylinder to which each of the hollow raised feature (11) can be approximated, and indicated in Figure 2 as "a" would be typically less than 20 mm, preferably less than 18 mm and more preferably less than 15 mm.
  • soft caps larger than 20 mm might compromise the stability of the container, depending on the composition of the web and mainly on the number and distribution of the soft caps on the base portion.
  • a suitable width for the hollow raised features (11) would therefore be about 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 mm, with the central range, i.e. 7, 8, 9, 10, 11, 12, being preferred.
  • the height of the hollow raised features (the distance of the top of the hollow raised feature from the plane of the base, indicated in Figure 2 as "b") would typically be from one fifth of their width to a value about equal to their width. Preferably their height would be at least one fourth of their width and even more preferably at least one third up to a value that is slightly less than their width. Thus, for soft caps with e.g. a width of about 10 mm, a preferred height would be from about 3 to about 9 mm.
  • the raised hollow features (11) are preferably in evenly spaced relation.
  • the distance between two adjacent features would be small enough to maintain the desired rigidity to the base and the container but not too large to disrupt the softening effect.
  • the distance between two adjacent raised features (indicated in Figure 2 as "c") would be from at least about 1 mm to about 10 mm, preferably from about 1 mm to about 8 mm, more preferably from about 2 mm to about 6 mm.
  • the hollow raised features (11) While not necessarily disposed in a symmetrical fashion, preferably the hollow raised features (11) will be distributed in parallel rows, as illustrated in Figure 3, or in offset rows (not shown) or in concentric rings (also not shown) or in spiral form (also not shown) or in any other substantially regular pattern. Not necessarily however they need to cover the whole surface of the base portion. Typically the array of hollow raised features (11) will be positioned in the central portion of the base as illustrated for instance in Figure 3 and will cover at least 50 %, preferably at least 60 %, more preferably at least 70 %, and even more preferably at least 80 % of the surface of the base portion.
  • the hollow raised features (11) are represented as cylinders or hemispheres ("bubbles"). However they may also have a different shape. For instance they may be V-shaped or rod-shaped caps arranged alternatively in several rows such that caps in adjacent rows oppose each other.
  • the above description concerning size and distribution of soft caps having a cylinder or hemisphere shape can be applied analogously also to soft caps of a different shape.
  • hollow raised features (11) of essentially the same size are preferred, particularly because this will simplify the manufacturing process, this however is not a strict requirement to get the desired softening effect as for instance alternating smaller and larger soft caps, or alternating soft caps of different shape, may further improve the protecting effect.
  • a top flange (13) that is the upper periphery of the container and extends around its open top in a continuous unbroken manner.
  • Said flange is typically planar and parallel to the plane of the base. Its width is not critical. If the container has to be closed by heat-sealing a lidding film or sheet onto the flange, then the flange should be at least 3-4 mm wide. Otherwise, if the container has to be closed by wrapping up, or by snapping on a mating rigid lid or cover as known in the art, the flange may be smaller than that or even a mere bead. As illustrated in Figure 1, the flange may have a skirt (14).
  • the sidewalls (12) are substantially upright as in Figure 1, to give the container the shape of a punnet, but alternatively they may also project outwardly to give the container the shape of a conventional tray.
  • a plurality of ribs (15) is generally present in the sidewalls (12) to provide for the desired vertical stiffness.
  • Corrugations lines that may be parallel flutes, furrows, ridges, crests or grooves (16) may be formed also in the base portion, in the part thereof that does not comprise the raised features (11).
  • the container is also provided with a downwardly projecting element (17), that may be in the form of a continuous annular element extending over the whole perimetric portion of the base (10), at a slightly retracted position relative to the edge where the base (10) connects with the sidewalls (12), or it may be in the form of discrete projecting elements typically at the comers of the base (10), with a flat bottom external surface to serve as support for the container.
  • a downwardly projecting element (17) may be in the form of a continuous annular element extending over the whole perimetric portion of the base (10), at a slightly retracted position relative to the edge where the base (10) connects with the sidewalls (12), or it may be in the form of discrete projecting elements typically at the comers of the base (10), with a flat bottom external surface to serve as support for the container.
  • a rigid covering lid may be included and unitarily formed with the container.
  • the lid and the container are a single continuous piece of material formed simultaneously with a hinge, formed integrally therewith, which on deformation allows the covering lid to swing backwards and forwards on opening and closing the receptacle.
  • the polymeric materials that can be used in the manufacture of the container of the present invention can include any polymers that fulfill the purposes of the invention or which, with the addition of additives can be modified to fulfill the purposes of the invention.
  • Polymers suitable include polyolefins, such as polypropylenes and polyethylenes, polyvinyl chloride, polyesters, co-polyesters, polyamides, co-polyamides, polystyrene, polystyrene copolymers, and the like polymers. It is also possible to use blends of suitable polymers, particularly when one of the components of the blend is used in a minor amount as an impact modifier to increase flexural modulus and crack resistance.
  • the container is typically highly permeable and often it is also perforated to allow the exchange of gases with the environment.
  • the presence of discrete projecting elements (17) will be particularly preferred because by suitably selecting a gas permeable material for the container and/or suitably creating small perforations therein, the exchange of gases with the environment will be possible also for the items packaged in contact with the bottom of the container.
  • gas-barrier properties may be required e.g. to maintain a suitably modified or controlled atmosphere within the package that would prolong the shelf life of the packaged food product.
  • the material used for the container will comprise a gas-barrier layer, typically comprising ethylenevinyl alcohol copolymers, nylons, or blends thereof, set in order to provide the materials with an Oxygen Transmission Rate (OTR) (evaluated by following the method described in ASTM D-3985 and using an OX-TRAN instrument by Mocon) lower than 250, preferably lower than 125 cm 3 /m 2 .d.atm, when measured at 23 °C and 0 % of relative humidity.
  • OTR Oxygen Transmission Rate
  • the multi-layer structure will also comprise a heat-sealable resin such as a polyethylene resin, as the innermost layer (i.e. the skin or external layer of the container which is closer to the food product), to improve the sealability properties of the container, and a bulk layer of a polymer or polymer blend such as those indicated above.
  • a heat-sealable resin such as a polyethylene resin
  • the innermost layer i.e. the skin or external layer of the container which is closer to the food product
  • a bulk layer of a polymer or polymer blend such as those indicated above.
  • thermoplastic material used for the container of the present invention may be transparent, either clear or colored, translucent, either clear or colored, or opaque.
  • the sheet used for the manufacture of the container of the invention may be obtained by extrusion and in case of a multilayer sheet by co-extrusion or by conventional lamination techniques.
  • the conversion of the sheet into the container according to the present invention is then carried out by a first step of negative thermoforming using a concave, female mould having an essentially flat base, where the heat-softened plastic is drawn down over the mould by drawing a vacuum through the mould, optionally with the assistance of a suitable plug, followed by a second step of inverted negative thermoforming, where the array of hollow raised features with a flexible upper portion is created into the base of the container by blowing air from the base of the concave mould against a suitably shaped positive plug mould that compresses the formed sheet against the base of the concave mould and/or by suitably applying a negative pressure through said shaped positive plug mould.
  • the base comer and top flange areas of the female mould are cooled during the entire process by chilled water circulating within the metal body of the mould.
  • the central base area of the mould however is never cooled during the entire thermoforming process.
  • This central portion of the female mould base may on the other hand also be heated, e.g. by electrical element heaters or circulating hot fluids (water, oil, etc.).
  • the central shaped portion of the plug assist is held inside the main body of the plug until the second, re-forming, step takes place.
  • Said central shaped portion is lowered towards the female mould in said second step of inverted negative thermoforming to allow the subsequent re-forming of the base area of the mould-shaped plastic to create the desired array of raised features therein.
  • Said separate shaped portion of the plug assist is cooled by circulating chilled water and once this second thermoforming step is completed, and the soft caps are blown and/or sucked against the surface of the shaped central portion of the plug assist, this allows a rapid temperature drop. With the reduced temperature the shaped plastic container becomes stable and can suitably be removed from the mould without being distorted.
  • (21) represents the heated and softened thermoformable sheet which is fed between the two halves of the tool, the upper one, pressure box (22), and the lower one, mould (23).
  • the two halves are separated.
  • the tool closes sealing sheet (21) against the top of the lower mould (23) and the open end of the pressure box (22).
  • Plug (25) then moves towards the cavity (24) of the mould (23) until it has completed its travel and is stopped by the plug stopping plate (29) and at the same time a positive pressure is applied to pressure box (22) through the plug pillars (28) and the plug "soft caps” mould plate (26) while a negative pressure (vacuum) is applied to cavity (24) via the cavity vented plate (27), pushing sheet (21) against said plate (27) ( Figure 4c).
  • the plug "soft caps” mould plate (26) has moved further down to face the formed sheet (21) in contact with the cavity vented plate (27).
  • the positive pressure that was applied through the plug "soft caps” mould (26) is switched to a negative pressure and the negative pressure applied through the cavity vented plate (27) is switched to a positive air pressure to create the array of hollow raised features (11) mating the shape of the plug "soft caps” mould plate (26).
  • the sidewalls, base comer and top flange areas of the mould (23), but not the central base portion are cooled by chilled circulating water. Also cooled by circulating cold water is the plug "soft caps" mould plate (26).
  • the containers are thermoformed from a webstock of material even if in line of principle separated cut sheets could also be employed.
  • cutting means separate the containers, one from the other, if prepared from a webstock, and trim out the excess plastic material.
  • the thickness of sheet (21), used as starting material in the above described thermoforming process would be generally within the range of from about 150 ⁇ m to about 1,000 ⁇ m, preferably from about 160 ⁇ m to about 900 ⁇ m, even more preferably from about 170 ⁇ m to about 800 ⁇ m, most preferably from about 180 ⁇ m to about 700 ⁇ m, mainly depending on the height desired for the tray and therefore on the depth of the first thermoforming step.
  • Thermoplastic materials suitable for the manufacture of the wrapping or lidding sheet or film include mono- and multi-layer films, oriented or non oriented, and, if oriented, heat-shrinkable or heat-set.
  • Monolayer structures will typically comprise polyolefins (such as propylene-based polymers or, preferably cross-linked, polyethylene-based polymers) or polyesters.
  • Multi-layer structures will comprise at least an outer sealing layer, generally an outer heat-sealing layer, and an outer abuse layer. These multi-layer structure may include additional inner layers, such as gas-barrier layers, if a gas-barrier package is desired, bulk layers, and tie layers, as known in the art.
  • Suitable rigid lids will generally be made by thermoforming, using the same plastic material of the container.
  • cardboard may also be employed.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
  • Containers Having Bodies Formed In One Piece (AREA)
  • Packages (AREA)
  • Packaging Frangible Articles (AREA)
EP03023337A 2003-10-15 2003-10-15 Warmgeformter Kunststoffbehälter und Verfahren zu dessen Herstellung Withdrawn EP1524202A1 (de)

Priority Applications (5)

Application Number Priority Date Filing Date Title
EP03023337A EP1524202A1 (de) 2003-10-15 2003-10-15 Warmgeformter Kunststoffbehälter und Verfahren zu dessen Herstellung
ES04022757T ES2342598T3 (es) 2003-10-15 2004-09-24 Recipiente de plastico termoconformado y metodo para su fabricacion.
EP20040022757 EP1544129B1 (de) 2003-10-15 2004-09-24 Warmgeformter Kunststoffbehälter und Verfahren zu dessen Herstellung
AT04022757T ATE466789T1 (de) 2003-10-15 2004-09-24 Warmgeformter kunststoffbehälter und verfahren zu dessen herstellung
DE602004026987T DE602004026987D1 (de) 2003-10-15 2004-09-24 Warmgeformter Kunststoffbehälter und Verfahren zu dessen Herstellung

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP03023337A EP1524202A1 (de) 2003-10-15 2003-10-15 Warmgeformter Kunststoffbehälter und Verfahren zu dessen Herstellung

Publications (1)

Publication Number Publication Date
EP1524202A1 true EP1524202A1 (de) 2005-04-20

Family

ID=34354459

Family Applications (1)

Application Number Title Priority Date Filing Date
EP03023337A Withdrawn EP1524202A1 (de) 2003-10-15 2003-10-15 Warmgeformter Kunststoffbehälter und Verfahren zu dessen Herstellung

Country Status (4)

Country Link
EP (1) EP1524202A1 (de)
AT (1) ATE466789T1 (de)
DE (1) DE602004026987D1 (de)
ES (1) ES2342598T3 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015000743A (ja) * 2013-06-17 2015-01-05 株式会社エフピコ 食品包装用容器の蓋及び食品包装用容器
US20180162595A1 (en) * 2015-07-09 2018-06-14 Toyo Seikan Group Holdings, Ltd. Container in which inner surface is formed from olefin resin layer
GB2580793A (en) * 2019-01-24 2020-07-29 Softform Ltd A method and tool for manufacturing a container from a thermoplastic material

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2715373A1 (fr) * 1994-01-24 1995-07-28 Bourjala Robert Cagette en matière plastique.
US5954203A (en) * 1997-12-24 1999-09-21 Allegiance Corporation Packaging container
FR2816923A1 (fr) * 2000-11-17 2002-05-24 Quatre C Sarl Emballage unitaire d'objet fragile ou non de differentes formes et dimensions entrant dans un cabarit admissible
US6443309B1 (en) * 2000-05-15 2002-09-03 Victory Packaging, Inc. Apparatus for packaging goods

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2715373A1 (fr) * 1994-01-24 1995-07-28 Bourjala Robert Cagette en matière plastique.
US5954203A (en) * 1997-12-24 1999-09-21 Allegiance Corporation Packaging container
US6443309B1 (en) * 2000-05-15 2002-09-03 Victory Packaging, Inc. Apparatus for packaging goods
FR2816923A1 (fr) * 2000-11-17 2002-05-24 Quatre C Sarl Emballage unitaire d'objet fragile ou non de differentes formes et dimensions entrant dans un cabarit admissible

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015000743A (ja) * 2013-06-17 2015-01-05 株式会社エフピコ 食品包装用容器の蓋及び食品包装用容器
US20180162595A1 (en) * 2015-07-09 2018-06-14 Toyo Seikan Group Holdings, Ltd. Container in which inner surface is formed from olefin resin layer
US11820553B2 (en) 2015-07-09 2023-11-21 Toyo Seikan Group Holdings, Ltd. Container in which inner surface is formed from olefin resin layer
GB2580793A (en) * 2019-01-24 2020-07-29 Softform Ltd A method and tool for manufacturing a container from a thermoplastic material

Also Published As

Publication number Publication date
ES2342598T3 (es) 2010-07-09
DE602004026987D1 (de) 2010-06-17
ATE466789T1 (de) 2010-05-15

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