EP0242419A1 - Fermeture en matière plastique pour le vide sans couche intermédiaire - Google Patents

Fermeture en matière plastique pour le vide sans couche intermédiaire Download PDF

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Publication number
EP0242419A1
EP0242419A1 EP86105621A EP86105621A EP0242419A1 EP 0242419 A1 EP0242419 A1 EP 0242419A1 EP 86105621 A EP86105621 A EP 86105621A EP 86105621 A EP86105621 A EP 86105621A EP 0242419 A1 EP0242419 A1 EP 0242419A1
Authority
EP
European Patent Office
Prior art keywords
closure cap
sealing
closure
fins
container
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Withdrawn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
EP86105621A
Other languages
German (de)
English (en)
Inventor
Charles S. Ochs
Larry A. Hottle
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.)
Anchor Hocking LLC
Original Assignee
Anchor Hocking 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 Anchor Hocking LLC filed Critical Anchor Hocking LLC
Priority to EP86105621A priority Critical patent/EP0242419A1/fr
Publication of EP0242419A1 publication Critical patent/EP0242419A1/fr
Withdrawn legal-status Critical Current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
    • B65D41/00—Caps, e.g. crown caps or crown seals, i.e. members having parts arranged for engagement with the external periphery of a neck or wall defining a pouring opening or discharge aperture; Protective cap-like covers for closure members, e.g. decorative covers of metal foil or paper
    • B65D41/02—Caps or cap-like covers without lines of weakness, tearing strips, tags, or like opening or removal devices
    • B65D41/04—Threaded or like caps or cap-like covers secured by rotation
    • B65D41/0435—Threaded or like caps or cap-like covers secured by rotation with separate sealing elements
    • B65D41/0442—Collars or rings

Definitions

  • the present invention relates to improved closure caps for sealing containers formed of glass or plastic or other materials and more particularly to a molded plastic closure cap where the sealing means includes integral sealing ribs or fins molded as an integral portion of the closure cap and covered with a softer sealing material.
  • Plastic closures with sealing ribs or fins are presently used to seal containers in various packaging applications.
  • a closure of this type is applied to the container's threaded neck and creates a seal when its ribs or fins press against the container finish.
  • Such closures are commonly called linerless closures.
  • Certain packages require a seal which retains an extremely airtight seal or a vacuum within the sealed container for preserving the packaged product.
  • a seal which retains an extremely airtight seal or a vacuum within the sealed container for preserving the packaged product.
  • the general type of plastic closure presently used may maintain vacuum in a certain percentage of sealed packages, the percentage of packages in which the seal fails to maintain vacuum is un­acceptably high in many cases.
  • Plastic caps with sealing ribs or fins are usually molded in one piece from polyolefin materials, often a polypropylene type.
  • the sealing fins are relatively rigid in comparison to other materials such as plastisol gaskets normally used to seal containers.
  • the polyolefin sealing fins thus lack the softness to attain intimate contact with container finishes such as is necessary to maintain a vacuum especially during the handling of the packages.
  • containers are manufactured to specified tolerances, they do not always have perfect finishes due to problems inherent in their manufacturing process.
  • the method of this invention to achieve the improved sealing capability is to place a softer sealing material such as a wax, hot melt, epoxy, or a softer plastic preferably a heat cured plastisol over the sealing ribs or fins of the closure cap.
  • a softer sealing material such as a wax, hot melt, epoxy, or a softer plastic preferably a heat cured plastisol
  • paraffin wax and plastisol have been tested and both have improved the ability of the closure to hold vacuum.
  • plastisol When plastisol is used, it is applied as a liquid over the sealing fins and then heated to cause the liquid plastisol to fuse or gel into a solid.
  • the liquid plastisol may be applied to the fins by a stationary nozzle or spray gun while the closure is rotated.
  • a thickness of the plastisol of 0.001" to 0.020" over the ribs or fins has proven useful as described below or thicker plastisol coatings anchored by the fins may be used.
  • the invention includes preferred plastisol formulations for use with molded closures such as those molded from polyolefin including polypropylene.
  • the preferred plastisols have uncharacteristically low fusing temperatures thereby eliminating heat damage to the closures such as the shrinking experienced with the prior plastisols requiring relatively high fusing temperatures.
  • the object of this invention is to improve the sealing ability of linerless plastic closure caps particularly for the retention of a vacuum within sealed packages and thus to provide a molded plastic closure cap suitable for achieving an acceptable percentage of properly sealed vacuum packages where the sealing may be done on automatic sealing machinery at extremely high sealing rates.
  • Another object of the invention is to provide an improved plastic linerless closure.
  • Another object of the present invention is to provide a molded linerless plastic closure incorporating a relatively thin coating of sealing material on the cap sealing members.
  • Another object of the present invention is to provide a molded linerless plastic closure having a fused or gelled and relatively thin sealing coating provided on the sealing fins or other sealing members.
  • Another object is to provide plastisol formulations having uncharacteristically low fusing temperatures to eliminate heat damage to the molded closures.
  • the closure cap 1 in accordance with the present invention, has a cover 2 and a depending skirt 3 including container engaging threads 4.
  • the outer surface of the skirt 3 may include knurls or other gripping means 5 for applying and removing the closure cap 1 from the container 6.
  • the cover 2, skirt 3 and threads 4, together with a container sealing means comprise a unitary or one-piece molded closure cap formed on conventional cap molding machinery.
  • the sealing fins 7 have an angular alignment with both the closure cap cover 2 and the container rim 8 so that they yield and accommodate themselves against the adjacent container rim 8 in a sealing relationship.
  • the improvement of this invention comprises the application of a coating of softer sealing material over the fins 7.
  • Suitable sealing films 9 include easily applied films such as waxes, hot melts, epoxies, or other soft plastic materials and preferably plastisols applied over the fins 7.
  • Coatings of these materials have been tested and have been proven to significantly increase the sealing capabilities of molded closures and in particular have increased the ability of the closures to hold a vacuum within the sealed containers.
  • a plastisol When a plastisol is employed, it may be sprayed or otherwise distributed over the sealing fins 7 and heated and fused or gelled into a continuous resilient sealing film over the fins.
  • Relatively thin plastisol films having a thickness of as little as 0.001 to 0.020 inches have been tested and found to be effective in providing the improved sealing action.
  • Such a thin or film-like coating is illustrated in FIG. 3.
  • a heavier coating is illustrated in FIG. 2.
  • the fused or gelled plastisol conforms generally to the shape of the plastic sealing fins with the thin coating illustrated in FIG. 3 and is held in the closure by its own adhesive qualities but also by the physical interlock resulting between the film 10 and the sealing fins 7.
  • the thicker coating 9 in FIG. 2 provides the sealing improvements while using more of the sealing material. Even though packages sealed with fins coated in the manner illustrated in FIGS. 2 and 3 were subjected to elevated temperatures, such as those resulting from the use of steam by the vacuum forming sealing apparatus, no significant loss of the improved sealing action of the films has been found to result.
  • Preferred low-temperature fusion plastisol formulations for the sealants in linerless plastic closures as described are of the following general type:
  • Vinyl dispersion resins include both polyvinyl chloride homopolymer and polyvinyl chloride copolymer resins.
  • Examples of commercially available homopolymer resins include FPC-605 (Occidental Chemical Corp.) and Geon 125 (B.F. Goodrich, Chemical Division).
  • Examples of commercially available copolymer resins containing vinyl actate comonomer include FPC-6338, 4.2% vinyl acetate, (Occidental Chemical Corp.) and Formolon 40, 4.6% vinyl acetate, (Formosa Plastics Corp.).
  • Another copolymer resin is Geon 138, 4% vinyl ester (B.F. Goodrich, Chemical Division) which contains a proprietary vinyl ester comonomer instead of vinyl acetate comonomer.
  • the vinyl copolymer dispersion resins are preferred over the homopolymer resins for this type of formulation because plastisols containing copolymer resin fuse at a lower temperature than do those made with homopolymer resins.
  • fast-fusing plasticizers examples include: butyl benzyl phthalate, di-butyl phthalate, and butyl octyl phthalate.
  • Butyl benzyl phthalate is commercially available as Santicizer 160 from Monsanto Industrial Chemicals Co.
  • Butyl octyl phthalate is commercially available as PX-914 from U.S.S. Chemicals.
  • Di-butyl phthalate is commercially available as Palatinol DBP (Badische Corp.), Nuoplaz DBP (Tenneco Chemicals, Inc.), and PX-104 (U.S.S. Chemicals).
  • Examples of general purpose plasticizers include di-2-ethyl hexyl phthalate (DOP), and di-isodecyl phthalate (DIDP). These plasticizers are both commercially available from a number of companies.
  • DOP is available as Nuoplaz DOP (Tenneco Chemicals, Inc.), PX-138 (U.S.S. Chemicals, Inc.), and Palatinol DOP (Badische Corp.).
  • DIDP is available as Nuoplaz DIDP (Tenneco Chemicals, Inc.) PX-120 (U.S.S. Chemicals), and Palatinol DIDP (Badische Corp.).
  • the general purpose plasticizer functions to stabilize the viscosity of the unfused (liquid) plastisol.
  • Stabilizers retard the heat degradation of the vinyl resin.
  • stabilizers available as powders, liquids, or pastes. Examples of commercially available stabilizers include Ferro 707X, Zinc, Epoxy, Organic inhibitor paste type, (Ferro Corporation) and Interstab CZL 731, Calcium, Zinc Liquid type, (Interstab Chemicals, Inc.).
  • a filler is an inert, powdered material which can be properly dispersed in plastisol, is usually inexpensive, and is included in the formulation to lower the plastisol cost. Often fillers also function synergistically with other ingredients such as lubricants. Examples of commercially available fillers include No. 1 Barytes, barium sulphate, (Pfizer, Inc.) and Mica #279 (Whittaker, Clark, and Daniels).
  • a pigment provides color to the fused plastisol.
  • examples of commercially available pigments include TI-Pure R-101, titanium dioxide, (E.I. du Pont deNemours & Co.) and BK-5099 Pure Black Iron Oxide (Pfizer, Inc.).
  • Lubricants cause the fused plastisol to have a slippery surface, reducing friction between the closure's plastisol sealing surface and the container's sealing surface. A slippery plastisol is necessary to lower the torque required to remove the closure.
  • examples of commercially available lubricants are oleamide, erucamide, and silicone fluid. Oleamide is commercially available as Kemamide U and erucamide as Kemamide E (both from Witco Chemical Corp., Humko Division). Silicone fuid is available as SF-18 (General Electric).
  • Blowing agents decompose during plastisol fusion causing the fused plastisol to have a cellular or foamed structure.
  • Commercially available blowing agents include Celogen OT and Celogen TSH,p,p1 - oxybis (benzene sulfonyl hydrazide), (both from Uniroyal Chemical Co.) and Nitropore OBSH,p,p1 - oxybis (benzene sulfonyl hydrazide), (Olin Corp.).
  • the ingredients are combined as described below to form a liquid plastisol.
  • the liquid plastisol is deposited into a plastic linerless closure to form a sealing surface for a vacuum package consisting of the closure and container onto which the closure is applied.
  • the container can be made of materials such plastic, glass, or metal.
  • Plastisol formulations as disclosed above have the required low-temperature fusion properties by virtue of their containing a combination of (1) vinyl copolymer dispersion resins and (2) fast fusing plasticizers.
  • the general purpose plasticizer functions to stabilize the viscosity of the liquid plasticizer, increasing its shelf life.
  • the remaining ingredients are not critical to the low temperature fusion properties of the plastisol.
  • the ingredients comprising a plastisol formulation are weighed in the proportions described in Part I. Then the weighed ingredients are combined and thoroughly mixed to form a homogeneous dispersion. This liquid dispersion is called a plastisol. Plastisol mixing and handling are well described in trade literature.
  • Mixing is usually done by automatic equipment. Many laboratory and production mixers of various designs are suitable for mixing plastisols and are commercially available. An example is the Double Planetary Mixer manufactured by Charles Ross and Son Co.
  • minor liquid and paste ingredients in the formulation are preblended to form slurries.
  • the slurries are inroduced into the mixer, followed by the remaining powders and resins in the formulation.
  • the general purpose plasticizer can be added. At this point, some of the fast-fusing plasticizer can be added, but it is usually withheld.
  • the purpose of withholding part of the plasticizer is to create a condition of high shear during the initial phase of mixing.
  • the mixer is operated under high shear conditions until all the lumps of dry powder have been broken and dispersed.
  • the remainder of the plasticizer is added, and mixing is continued until a homogeneous dispersion is obtained. Often, mixing is done in a partial vacuum (25-30 inches Hg) to remove air bubbles from the plastisol.
  • Plastisol can be mixed in advance of use and stored until needed. Some plastisols, especially the low-temperature fusion type described in Part I, become more viscous during storage due to plasticizer absorption by the vinyl resin. Storage life can be lengthened by maintaining the storage temperature at 40-50°F and particularly by avoiding temperatures of 80°F or greater.
  • Plastisol is placed into a pressurized tank which is connected to a dispensing nozzle. This nozzle is positioned over a rotating closure into which the plastisol is injected when the nozzle opens. The liquid plastisol is thereby flowed onto the closure's fins in a precisely metered amount. Next, the closure and plastisol are heated to a temperature of less than 330°F for a period of time necessary to sufficiently fuse or flux the plastisol in the closure.
  • FIG. 2 as indicated illustrates a coating in accordance with the invention with a middle range of thickness and where the coating material 9 fills the space between the two sealing fins 7.
  • the coating provides the sealing contact between the closure 2 and the container 6.
  • FIG. 3 illustrates a similar closure where a coating 10 is of lesser thickness is used and where the coating is seen to conform more closely to the shape of the sealing fins 7. Nevertheless, such coatings with a thickness near the lower side of the thickness range provide significantly improved sealing capability.
  • FIG. 4 illustrates the use of a coating of the type described above on a closure cap 11 having a differing sealing means comprising three sealing fins 12 having differing lengths and having a lesser angle with the cover 13 of the closure 11.
  • This fin and coating combination functions in a similar manner to provide the improved sealing capability.
  • FIG. 5 illustrates another embodiment where the closure 14 is in sealing engagement with a container 19 and where a relatively thin coating 16 forms a seal between the slanted fins 15 and the container finish edges 18.
  • FIG. 6 shows a preferred method of applying these coatings in controlled thicknesses.
  • the caps are mounted in rotating nests of a typical gasket applying machine.
  • a spray nozzle positioned to direct a coating spray onto the sealing members operates for a sufficient period to apply the desired coating thickness.
  • the cap is transferred to a suitable heating means for the curing or gelling step.
  • FIG. 7 illustrates another embodiment of the invention as a closure 20.
  • the closure 20 has a molded closure cap shell with a cover 21 and a depending skirt 22 including closure threads 23 for engaging cooperating threads 24 on a container 25.
  • the sealing means for the closure cap 20 comprises a pair of sealing fins 26 having a generally triangular cross-section and depending from the underside 31 of the closure cap cover 21. The fins 26 are inclined at about a 30° angle from the vertical and their angularly aligned sides enclose an angle of about 20°.
  • a plastisol is sprayed or flowed around the two sealing fins 26 to form a sealant 28 of generally rectangular cross-section which is confined in a channel 27 comprising the underside 31 of the cap cover 21, the inner and upper wall 29 of the closure skirt 22 and a downwardly extending and generally vertically oriented bead 30. If there is no bead corresponding to the bead 30, the inner edge of the sealant tapers inwardly and upwardly to the cover underside 31.
  • the two fins 26 and the sealant 28 combine to provide an efficient seal useful for vacuum seals as well as air tight seals of extremely high efficiency.
  • the two fins 26 also cooperate to anchor the sealant 28 in the closure cap shell in combination with the channel firming walls.
  • the sealant is preferably a low temperature fusing plastisol as described herein.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Closures For Containers (AREA)
EP86105621A 1986-04-23 1986-04-23 Fermeture en matière plastique pour le vide sans couche intermédiaire Withdrawn EP0242419A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP86105621A EP0242419A1 (fr) 1986-04-23 1986-04-23 Fermeture en matière plastique pour le vide sans couche intermédiaire

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP86105621A EP0242419A1 (fr) 1986-04-23 1986-04-23 Fermeture en matière plastique pour le vide sans couche intermédiaire

Publications (1)

Publication Number Publication Date
EP0242419A1 true EP0242419A1 (fr) 1987-10-28

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EP86105621A Withdrawn EP0242419A1 (fr) 1986-04-23 1986-04-23 Fermeture en matière plastique pour le vide sans couche intermédiaire

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2161303A1 (fr) * 2008-09-08 2010-03-10 In. Cam. Fabbrica Barattoli S.p.a. Une composition de plastisol, et une méthode et une usine pour appliquer la composition aux capsules de fermeture de récipients pour créer un joint, et aux capsules construites utilisant la composition, la méthode et l'usine
WO2015001479A1 (fr) * 2013-07-02 2015-01-08 Silgan Holdings Inc. Récipient maniable à hauteur de col réduite destiné à être fermé au moyen d'un couvercle et procédé de fermeture

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3815771A (en) * 1972-06-07 1974-06-11 Anchor Cap & Closure Corp Linerless closure cap
GB2111965A (en) * 1981-12-24 1983-07-13 Anchor Hocking Corp Moulded closure caps
WO1984000346A1 (fr) * 1982-07-09 1984-02-02 Metal Closures Group Plc Ameliorations a des fermetures pour recipients filetes

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3815771A (en) * 1972-06-07 1974-06-11 Anchor Cap & Closure Corp Linerless closure cap
GB2111965A (en) * 1981-12-24 1983-07-13 Anchor Hocking Corp Moulded closure caps
WO1984000346A1 (fr) * 1982-07-09 1984-02-02 Metal Closures Group Plc Ameliorations a des fermetures pour recipients filetes

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2161303A1 (fr) * 2008-09-08 2010-03-10 In. Cam. Fabbrica Barattoli S.p.a. Une composition de plastisol, et une méthode et une usine pour appliquer la composition aux capsules de fermeture de récipients pour créer un joint, et aux capsules construites utilisant la composition, la méthode et l'usine
WO2015001479A1 (fr) * 2013-07-02 2015-01-08 Silgan Holdings Inc. Récipient maniable à hauteur de col réduite destiné à être fermé au moyen d'un couvercle et procédé de fermeture
RU2708757C2 (ru) * 2013-07-02 2019-12-11 Силган Холдингс Инк. Удобная для использования емкость с уменьшенной высотой горловины для укупорки укупорочной крышкой и способ укупорки
US10538363B2 (en) 2013-07-02 2020-01-21 Silgan Holdings Inc. Closure unit consisting of cover and vessel, closure cover and closing method
US10633149B2 (en) 2013-07-02 2020-04-28 Silgan Holdings, Inc. Manipulable container having reduced neck height for closure with a closure cap, and method of closure

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