Screw-type sealing caps

Jdy 28, 1964

3,142,402

J. J. FOX

SCREW-TYPE SEALING CAPS

Filed Feb. 7, 1962

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United States Patent Office

3,142,402

Patented July 28, 1964

3,142,402

SCREW-TYPE SEALING CAPS

John J. Fox, Vancouver, British Columbia, Canada, assignor to The Tosca Seal Control Co. Ltd., Vancouver, British Columbia, Canada, a corporation of British Columbia

Filed Feb. 7,1962, Ser. No. 171,606

Claims. (Cl. 215—41)

This invention relates to screw-type sealing caps for bottles such as those containing liquid, such as bleach, that is liable to generate pressure as a result of heat and agitation, those that have screw caps in order that the caps may be replaced after the seal has been broken, and those requiring sealing as a protection against loss or for sanitary purposes.

The main purpose of the present invention is the provision of a cap formed of a suitable resilient material, such as polyethylene, polypropylene, or other plastic material, of such design that it may be rapidly molded and a minimum of material used, making it economically and practically competitive with any seal cap on the market, and which includes any or all of the following features:

(a) Provides an extremely good seal for bottles for pressurized or unpressurized fluids and yet may by quickly and easily removed when desired without any opening tool, (b) May be applied to any standard screw-neck bottle without alteration thereof, (c) May be applied to bottles by standard capping procedures and automatic cappers, (d) Includes a safety pressure release when used on bottles for liquids in which pressure is liable to build up during shipment and storage, and/or (e) Allows for manufacturing variations or tolerance in the dimensions of the type of bottle for which it is designed while retaining its sealing characteristics.

As is well know, much effort has been expended in the past to produce a satisfactory sealing cap. Most of the caps in use are made of metal despite their obvious drawbacks, although some not very successful efforts have been made in recent years to produce plastic caps. As far as the applicant is aware, no satisfactory plastic caps are in use for containing pressure liquids or liquids subjected to pressure.

Sealing cap according to the present invention over a number of disadvantages in known types of plastic caps as follows:

(1) This screw cap is formed with a skirt extension which includes a tear strip with a gripping tab projecting therefrom so that when the tear strip is removed, the screw cap may be easily removed and replaced on the bottle.

(2) This cap has a skirt and an extension which are designed to fit the standard screw neck of a bottle, making it unnecessary to redesign the bottle.

(3) The tear strip of this cap forming part of the skirt extension is not subjected directly to the effect of the bottle pressure against the cap, and the cap itself with its skirt extension provides a very firm grip on the bottle.

(4) The screw cap is left intact when the tear strip is removed so that the cap may still be used to seal the bottle during normal usage.

The present cap is pressed on to the bottle over the neck threads thereof, and the sealing portion of the cap includes projecting means for co-operating with the neck threads so that after the tear strip has been removed, the cap may be screwed on to and off the bottle neck in the same manner as ordinary screw caps.

Examples of the present cap are illustrated in the accompanying drawings, in which:

FIGURE 1 is an elevation, partly in section, of a bottle having a screw-threaded neck,

FIGURE 2 is a side elevation of a screw-type sealing cap particularly for this type of bottle,

FIGURE 3 is a plan view, partly in section, of the cap,

FIGURE 4 is a vertical section taken on the line 4—4 of FIGURE 3,

FIGURE 5 is a vertical section through the cap on the bottle of FIGURE 1 after the tear strip has been removed.

FIGURE 6 is an elevation of an alternative form of sealing cap,

FIGURE 7 is an enlarged fragmentary section taken on the line 7—7 of FIGURE 6, and

FIGURE 8 is a fragmentary vertical section taken on the line 8—8 of FIGURE 7.

FIGURES 2 to 5 of the drawings illustrate a sealing cap particularly for bottles requiring screw-type caps. FIGURE 1 illustrates a bottle 10 of the type having a threaded neck for receiving a cap which may be screwed on and off the bottle. The illustrated bottle is formed with a neck 11 having a screw thread 12 on its outer surface and an annular shoulder 13 projecting from said surface beneath the thread. When a standard threaded cap is placed on this bottle, it is screwed down very tightly in an effort to hold liquid in the bottle during shipment and handling up to the time it is desired to remove the contents therefrom. Neck 11 has the usual passage 14 therethrough which may or may not be downwardly flared.

Sealing cap 18 of FIGURES 2 to 5 includes a cap section 22 consisting of a cover 23 and a skirt 24 depending therefrom. If desired, a resilient or compressible plug or sleeve 27 is secured to and hangs down from cover 23, and is concentric with and spaced from skirt 24 to form an annular pocket 28 therebetween. Sleeve 27 preferably flares outwardly and downwardly from an upper end 32 to a lower end 33. A bevel 34 is formed in the outer surface of this sleeve at the lower end thereof to provide a tip 35 at the lower end of the sleeve which is of smaller diameter than the outer diameter of the sleeve at its top 32, as indicated at 36. The sleeve bevel 34 creates a funnel-like annular entrance 38 for pocket 28. The inner surface 40 of skirt 24 is shaped to fit against the outer surface of bottle neck 11, and one or more projections or protuberances 42 are formed on inner surface 40 and projects into pocket 28. If desired, a plurality of vertical ribs 45 may be formed on the outer surface of skirt 24 to act as gripping means when it is desired to rotate cap scetion 22 on the bottle neck.

A skirt extension 50 is secured to and depends from cap skirt 24. This extension is shaped to fit shoulder 13 of the bottle illustrated in FIGURE 1. Extension 50 includes a tear strip 53 which is preferably curved outwardly in cross section, as clearly shown in FIGURE 4, said strip extending almost completely around the skirt extension and having separated ends 54 and 55, to one of which a grip tab 56 is connected, this being end 55, in the illustrated cap. A thin film of material 58 forms the part of the skirt extension extending between strip end 54 and tab 55. An outwardly-flaring gripping ring 60 is secured to and projects downwardly from strip 53. The upper edge of this tear strip is defined by a weakening line 62, while the lower edge thereof is defined by another weakening line 63.

When sealing cap 18 is placed on the upper end of bottle neck 11, the flared ring 60 acts as a lead-in for said end. When downward pressure is exerted against the top of the cap, the bottle neck in effect travels upwardly through entrance 38 and into annular pocket 28. The material from which this cap is made is of such resiliency that the upper edge or inward projection of ring 60 springs over neck threads 12 and shoulder 13. Pro3,142,402

Ci tuberances 42 also spring over the neck threads. With this arrangement, the cap may be applied to a bottle by a standard capping machine. As soon as ring 60 passes shoulder 13, it contacts to grip the bottle neck beneath said shoulder. This action draws tear strip 53 around said shoulder, and this pulls cover 23 of the cap down tightly against the upper end of the bottle neck. In other words, ring 60 exerts a camming action on bottle shoulder 13 to draw cover 23 against the top of the bottle neck, and said ring acts as a locking projection firmly to retain the cap on the bottle. As the cap is applied, sleeve 27 enters the passage 14 of the bottle neck, bevel 34 ensuring this action. The sleeve is compressed a little in the neck passage so that it fits snugly against the surface thereof. The downwardly flared sleeve allows for manufacturing tolerances in the interior diameters of the bottle necks, and it fits any downward flare in the inner surface of the neck passage. The sleeve effectively seals liquid in the bottle, and it also holds in any pressure that may exist or be developed in the bottle.

When it is desired to unseal the bottle, tab 56 is gripped and pulled outwardly around cap 18. This tears strip 53 away from the edge of skirt 24 and from ring 60. This leaves the ring on the bottle neck, unless said ring has been provided with a downwardly inclined weakening line 65 through ring 60 from weakening line 13 of the lower edge of the tear strip and spaced away from ends 54 and 55 of said strip. Weakening line 65 may be omitted if it is not necessary to remove ring 60 from the bottle neck.

Cap section 22 may now be removed by turning it in the same way as you would an ordinary screw cap. During this turning action, one or more of the protuberances 42 fit into the space between the convolutions of neck thread 12 so that it rides up said thread to lift the cap section in the same direction. When it is desired to reclose the bottle, section 22 is placed on the neck thereof and rotated in the same manner as a screw cap, at which time one or more of the protuberances 42 ride down the undersurface of thread 12.

Cap 18 effectively seals the bottle upon which it is placed, and protects the neck from dirt and contamination. It also protects the contents of the bottle against tampering since you cannot get at such contents without destroying at least part of the sealing cap, Although this cap is a screw-type, it does not need to be screwed on to the bottle neck when the bottle is being sealed. It may be placed on the neck by downward hand pressure or by a capping machine. Although providing a strong and effective seal, this cap may be quickly and easily opened merely by removing tear strip 53. The remaining cap section may then be screwed off and on to the bottle neck in the usual manner.

FIGURES 6 to 8 illustrate a variation of sealing cap 18. Some liquids, such as bleach, build up pressure in the bottles due to heat and/or agitation. In some cases, it is desirable to relieve this pressure when it builds up to a predetermined point. Cap 18α includes very simple but effective means for relieving pressure under these circumstances.

Film 58α is formed with a small hole 70 therethrough which is just below the upper edge of tear strip 53α. This hole communicates with a space 72 within the tear strip and above bottle shoulder 13, see FIGURE 7. Very shallow passage means is provided in pocket 28α extending from space 72 to the interior of bottle neck 11. For this purpose, one or more pairs of spaced ribs 75 and 76 are formed on the surfaces of skirt 24α, cover 23α, and sleeve 27α defining annular pocket 28α. These ribs are extremely shallow, and each pair forms a passage 78 therebetween. Ribs 75 and 76 extend up the outer surface of sleeve 27α, radially along the inner surface of cover 23α, and down the inner surface of skirt 24α. Thus, each passage 78 extends from substantially the lower end of the sleeve, across the cover, and down the inner surface of skirt 24α to space 72 within tear strip 53α.

Ribs 75-76 are so shallow that when sealing cap 18α is applied to a bottle neck, the material of the cap is drawn against the bottle neck to provide an effective liquid-tight seal. However, when the pressure in the bottle builds up to a predetermined level, it forces the material of the cap outwardly adjacent said ribs so that the gas travels along passage 78 to space 72 and out through hole 70. As soon as the pressure is released, the material of the cap springs back to its normal position against the bottle neck surface. With this arrangement, the pressure cannot build up sufficiently to damage the bottle or the sealing cap, or to the point where gas suddenly emerges from the bottle when the seal is broken and the cap removed.

If desired, sleeve 27 or 27α may be omitted. The camming effect of ring 60 provides a good seal by drawing the cap cover tightly against the bottle neck, but if gases are involved, or if the bottle is liable to be subjected to rough handling, it is better to have the sleeve.

The curved cross sectional shape of the tear strip, and the gripping ring of each of these caps provides a secondary seal for the bottle on which the cap is positioned. The first seal is provided by the sleeve and by the fact that the cover of the cap section is drawn tightly against the upper end of the bottle neck by the action of the gripping ring drawing the tear strip around the bottle neck shoulder. The cap is freed from the secondary seal when the tear strip is removed. However, the cap section itself still provides a very good seal for the bottle because of the downwardly-flared sleeve of said section. The present sealing cap does not require any specially constructed bottle, in fact, it utilizes features of standard bottle constructions to help provide an effective seal. The action of the gripping ring in pulling the tear strip around and against the bottle neck shoulder illustrates this point. Each of these sealing caps may be applied to bottles by standard capping procedures and automatic cappers. The flare of the sealing ring guides the neck of the bottle properly into the cap. In addition, the cap may be placed lightly on the bottle neck with the upper end of the latter just fitting into the gripping ring. Then pressure is applied either manually or by a capping machine. The upper end of the bottle neck ends in the annular pocket of the cap, and the flared entrance is provided for this pocket so that there is no danger of the thin sleeve being displaced as the cap is pressed down on to the bottle. The embodiment of FIGURES 6 to 8 includes a safety pressure release for bottles which contain liquids that are liable to generate pressure from the time they are filled with the liquids until they reach the ultimate consumer. The flared sleeve of each cap allows for variatons or tolerances in the dimensions of the type of bottle for which it is designed without affecting the sealing characteristics of the cap.