FR2518961A1 - MOLD COVER FOR HERMETICALLY CLOSING A CONTAINER - Google Patents

Abstract

THE INVENTION RELATES TO A LID INTENDED TO TIGHTLY CLOSE A CONTAINER. THIS COVER INCLUDES A TOP 2 FROM WHICH PROJECTS DOWN THE RIBS OR ARETES 7 ON WHICH A COATING 9 IS APPLIED IN RELATIVELY SOFT MATERIAL. THIS COATING IS INTENDED TO ESTABLISH AND MAINTAIN VACUUM-TIGHT CONTACT WITH THE TOP EDGE OF A CONTAINER. FIELD OF APPLICATION: HERMETIC CLOSURE OF CONTAINERS.

Description

The invention relates to closing lids

  to hermetically seal glass or plastic containers or other

  subjects, and it relates more particularly to a

  molded closure ring made of plastic, the sealing device of which includes ribs or ridges

  Sealing seal molded with the lid.

  Plastic covers with ribs or sealing edges are currently used to seal containers in various packaging applications. A closure of this type is placed on the threaded neck of the container and

  makes a hermetic seal when its ribs or ridges.

  carry firmly against the end of the container Such closures are commonly referred to as closures

without trim.

  Some packaging requires a seal that will

  holds a vacuum inside the closed container to preserve the packaged product Although the general type of plastic closure described above maintains a certain percentage of vacuum in closed packages, the percentage of packages in which the seal 'fails to maintain the vacuum is, in many

  case, too high to be acceptable.

  Plastic lids having ribs or sealing edges are usually integrally molded of polyolefin materials, often a polypropylene type polyolefin.

  are relatively rigid compared to -

  other materials such as plastisol gaskets normally used to seal

  containers Polyolefin sealing edges

  therefore, flexibility to establish contact

  intimate with the end of the container, as this is neces-

  to maintain a vacuum, especially during the -

  handling of packaging Although containers are

  manufactured within specified tolerances, they do not

  not always perfect ends as a result of

  problems specific to their manufacturing process.

  Another problem with the materials used for the production of plastic closures without

  is that the adhesion of other materials to

  polyolefin faces is very difficult.

  The method of the invention for improving the possibilities of sealing is to place a softer sealing material, for example a wax, a hot melt material, an epoxy resin, a plastisol or a softer or softer plastic material. the

  ribs or sealing edges of the closure lid.

  For example, a paraffin wax and a plastisol have been tried and have both improved the ability of the closure to maintain the vacuum. When a plastisol is used, it is applied in liquid form to the sealing edges, then is heated to solid state by melting or gelling The liquid plastisol can be applied to the edges by means of a fixed nozzle, while the lid is rotated A plastisol thickness of 0.025 to 0.5 mm, applied on the ribs

  or fins, has been found useful, as described below.

  The object of the invention is to improve the ability to seal or seal hermetically sealed

  plastic closure without lining, in particular

  to maintain a vacuum inside hermetic packaging, and is therefore intended to provide a

  molded plastic closure cover, allows

  to obtain an acceptable percentage of packaging

  venably closed under vacuum, the shutter can be performed on an automatic shutter machine, to

  extremely high work rates.

  Another object of the invention is an improved sealless closure made of a plastics material, and more particularly a non-lined, molded plastic closure having a relatively thin coating of sealing material on the sealing elements of the lid. closure may include a relatively thin, melted or gelled sealant coating applied to the obturation edges or

  other sealed sealing elements.

  The invention will be described in more detail with reference to the accompanying drawing as non-limiting examples and in which:

  FIG. 1 is an elevation with a sectional cut

  a preferred embodiment of the closure cap according to the invention; Figures 2 and 3 are partial and detailed longitudinal sections, on an enlarged scale, of different embodiments of the closure cover according to the invention, hermetically closing a container; Figure 4 is a partial longitudinal sectional view

  and detailed, on an enlarged scale, another form of

  use of the closure cap according to the invention; FIG. 5 is a partial and detailed longitudinal section, on an enlarged scale, of another embodiment of the closure cover according to the invention; and

  FIG. 6 is an elevation with sectional cutaway

  showing a preferred method of applying the coating

  a soft seal on the shut-off elements

  tion of the closure according to the invention -

  The lid 1 of closure according to the invention comprises a top 2 and a skirt 3 which extends down from above and which comprises threads 4 intended to engage with a container. The outer surface of the skirt 3 may have a knurling or other means 5 for setting the closure lid 1 on a container 6 and its removal from the container above 2,

  the skirt 3 and the threads 4, as well as a closure device

  hermetic container, constitute a lid

  closure molded from a single block or one piece, -

  realized by means of a conventional machine for molding lids.

  There are a number of devices that

  suitable for hermetically sealing containers, made

  in one piece with the lid and having usual-

  In the form of ridges, ribs, or rings which project downward from the underside of the closure lid, a hermetic sealing device of this general type is described in prior patents such as the US Pat. United States Patent No. 3,815,771. This patent and other issued patents disclose protruding ribs or ridges molded with the closure cap and arranged to bear against the rim of the container.

  contact with the edge of the container and ensure the closure

  hermetic formulation for the contents of the closed container.

  As shown, the obturation edges 7

  are inclined at the same time with respect to the top 2 of the neck.

  closing circle and at the edge 8 of the container so

  to flex and adapt by itself against the adjoining edge

  cent 8 of the container while sealing.

  The improvement of the invention comprises the application of a thin layer 9 of softer or softer sealing material on the edges. Suitable sealing layers 9 comprise layers of material which can be easily applied, for example waxes, hot melt materials, epoxy resins,

  plastisols or other soft plastics

  7. Layers of these materials have been tested and have shown that they significantly increase the possibilities of airtight sealing of molded closures, and that

  in particular increased the ability of hand closures

  keep a vacuum inside closed hermetically sealed

  cally. When a plastisol is used, it is applied by spraying or otherwise on the sealing edges 7, and it is then heated and melted or

  gelled to form a continuous elastic layer of

  edge thickness Plastisol layers having a thickness of 0.025 to 0.5 mm were tested and

  proved to be effective in ensuring the

liorée.

  Plastisol melted or gelled is a sensitive

  the shape of plastic sealing edges

  and it is retained in the closure, not only because of

  its own adhesion qualities, but also because of the physical interlocking which occurs between the layer 9 and the sealing edges 7 Even in the case of hermetically sealed packages using the edges coated with the described above are subject to

  high temperatures such as those resulting from the use of

  water vaporization by the watertight sealing apparatus and vacuum production, no noticeable loss

  the improved sealing action of the layers did not appear.

  The preferred plastisols consist of a suitably dispersed mixture of ingredients such as dispersion resins, blending resins, plasticizers, stabilizers, lubricants,

251896 '1 -

  wetting agents, viscosity-lowering agents, pigments, fillers, etc. The resin may be a polyvinyl chloride homopolymer or copolymers of vinyl chloride such as a vinyl acetate copolymer and vinyl chloride copolymer. When a molded polyolefin closure is subjected to sufficient heat, it can shrink or melt to avoid these effects, the heat used

  to bring liquid plastisol, by fusion or gelation

  to a solid form should be relatively moderate.

  Tests have shown that certain copolymer dispersion resins, designed to melt at relatively low temperatures, are particularly suitable for this application. Temperatures of 150.degree.-165.degree.

  durations of 3 to 4 minutes have been used successfully.

  Butyl benzyl phthalate (PBB)

  read as plasticizer appeared to lower significantly

the heating cycle requested.

  A preferred composition of pastisol comprising

  copolymers of vinyl chloride and other

  plastisol dies, which melts or gels at low temperatures, is as follows: Formulation (PCR) 1 2 3 Resin 100 100 100 Plasticizer (P D O or

P.B B) 60 100 100

Stabilizing agent (Ferro

(707 X)) 2 1 2

  Pigment (Horsehead A-410) 2 2 Lubricant (Crodamide OR) 5 5 5 Lubricant (Crodamide ER) 7 P.D O = Dioctyl phthalate

  Description of the Supplier Description

  Hooker FPC-605 vinyl chloride homopolymer resin Tenneco 1759 Hooker FPC-6338 vinyl chloride copolymer and Stauffer Acetate SCC-40 Vinyl Stauffer Scc-52 Shamrock Diamond PVC-7401 Tenneco 0565 Copolymer Vinyl Chloride The six copolymer resins listed above have been found to be generally superior to homopolymer resins because they require less heat for

  In particular, the copolymer resins

  SCC-40, PVC-7401, Geon 138 and FPC 6338 have physical properties requiring less heat than that required by FPC-605 or Tenneco 1759 homopolymer resins. In addition, the copolymer resins achieve a maximum tensile load greater than that of the homopolymer resin, as shown below: Resin Breakdown Voltage (k Pa)

PVC-7401 7245

Geon 138 6965

FPC-6338 6790

SCC-40 6720

SCC-52 6580

0565 5950

1759 5495

FPC-605 5285

  These data show that not only

  Copolymers such as SCC-40, Geon 138, PVC-7401 and FPC-6338 exhibit physical properties under more moderate heating conditions than those used for polymeric resins, but are by their very nature.

  more resistant than similar homopolymer resins

FPC-605 and Tenneco 1759.

  Therefore, copolymer resins such

  that SCC-40, Geon 138 and PVC-7401 appeared to be particularly

  well suited to this application. The ability of this formulation to melt to

  relatively low temperatures protects the hull of the neck.

  molded plastic vane from deterioration during the application of a coating,

melting or gelation.

  Figure 2 shows a coating according to

  the invention, of medium thickness, the material-9 of the coating

  filling the space between the two sealing edges 7 In this case, it appears that the coating

  makes the tight contact between the closure 2 and the recess

please 6.

  FIG. 3 represents a similar closure,

  but applied to a container 6 and using a coating

  1 of smaller thickness that appears as a wedding

  more closely the shape of the sealing edges 7

  least, such coatings, the thickness of which is close to the lower limit of the thickness range, ensures

  better ability to seal vacuum.

  Figure 4 illustrates the use of a coating

  of the type described above on a cover 11 of

  The coating comprises a different sealing device which comprises three sealing edges 12 having different lengths and forming a larger angle with the top 13 of the cover 11. This coating functions in a manner similar to that previously described to improve

the sealing ability.

  Figure 5 represents another form of reali-

  in which the closure 14 is in sealing contact

  with a container 19 and in which also a coating

  16 forms a seal between the inclined ridges 15 and the

251896 I

  edges 18 of the end of the container.

  Figure 6 illustrates a preferred method for

  the application of these coatings to specific thicknesses

  The lids are arranged in tower

  of a typical filling machine.

  A spraying nozzle, arranged to direct a spray of coating material onto the sealing elements, operates for a time sufficient to apply the desired coating thickness. After the application of the coating, in the case where a plastisol or another material requiring maturation has been used, the lid is transferred to a suitable device

  heating for the ripening or gelling stage.

  It thus appears that an improved, linerless closure lid is obtained by the addition of a favorable soft coating providing the vacuum sealability. The lids are manufactured in the same manner as the lids currently known, with ,

  in addition, the coating application steps.

  It goes without saying that many modifications can be made to the closure lid described

  and shown without departing from the scope of the invention.

Claims (8)

  1 molded closure lid, comprising a sealing device integrally molded, for sealing a container (6), characterized in that it comprises a coating (9 or 10) relatively thin softer material than the material of the molded lid, this   covering the surfaces of the water the sheerness of the closure.   Lid according to claim 1, characterized   characterized by one or more elements (7   or 12) sealing, similar to edges, cons-   the sealing device intended to be applied against the container, the coating being applied to the surfaces of these elements.   Lid according to claim 2, characterized   characterized in that the coating has a thickness from about 0.025 to 0.5 mm.   Lid according to claim 3, characterized   characterized in that the coating is selected from the group consisting of waxes, hot melt materials, epoxy resins or plastisols.   Lid according to claim 4, characterized   in that the plastisol resin is a homopolymer   mother or a copolymer of vinyl chloride.   Lid according to claim 5, characterized   characterized in that the resin is a copolymer of vinyl acetate and vinyl chloride   Lid according to claim 6, characterized   in that the copolymer resin is selected from   the group consisting of SCC-40, Geon 138, PVC-7401 or FPC- 6338.   Lid according to claim 6, characterized   wherein the composition of the coating is selected from a group consisting of the following ingredients, in the indicated proportions: 251896 'Formulation (PCR) 1 2 3 Resin (vinyl chloride copolymer) 100 100 100 parts parts Plasticizer (PDO) or P.B B) 60 100 100   Stabilizing agent (Ferro (707 X)) 2 1 2 Pigment (Horsehead A-410) 2 2 Lubricant (Crodamide OR) 5 5 5 Lubricant (Crodamide ER) 7   Lid according to claim 5, characterized   characterized in that the plasticizer is butyl phthalate and benzyl and the resin is a chloride copolymer of vinyl.