US3664536A

US3664536A - Screw type closure cap

Info

Publication number: US3664536A
Application number: US39611A
Authority: US
Inventors: Byron E Emery
Original assignee: Cutter Laboratories Inc
Current assignee: Bayer Corp
Priority date: 1970-05-22
Filing date: 1970-05-22
Publication date: 1972-05-23
Anticipated expiration: 1989-05-23

Abstract

THE SCREW TYPE CLOSURE CAP INCLUDES A FIRST CAP FOR DIRECTLY SEALING A CONTAINER OPENING HAVING INTERNAL ENGAGEMENT MEANS FOR ENGAGING CLOSURE RETAINING MEANS ON THE CONTAINER. THE INTERNAL ENGAGEMENT MEANS IS FORMED TO PERMIT LIMITED LONGITUDINAL MOVEMENT OF THE FIRST CAP RELATIVE TO THE CLOSURE RETAINING MEANS AFTER ENGAGEMENT THEREWITH. AN OVERCAP IS FORMED TO OVERLIE SAID FIRST CAP AND APPLY PRESSURE THERETO TO MOVE SAID FIRST CAP LONGITUDINALLY AND INCREASE THE SEALING PRESSURE THEREOF AGAINST THE OPEN END OF THE CONTAINER.

Description

May 23, 1972 B. E. EMERY 3,664,536

SCREW TYPE CLOSURE CAP Filed May 22, 1970 2 Sheets-Sheet l :iii jjjij 24 ll 26 "-i" INVENTOR. BYRO/V E. EMERY BY QM (My ATTORNEYS May 23,1972 B. E. EMERY SCREW TYPE CLOSURE CAP 2 Sheets-Sheet 2 Filed May 22, 1970 INVENTOR. BymnEE/nery BY 19 U) United States Patent O 3,664,536 SCREW TYPE CLOSURE CAP Byron E. Emery, El Cerrito, Calif., assignor to Cutter Laboratories, Inc., Berkeley, Calif. Filed May 22, 1970, Ser. No. 39,611 Int. Cl. B65d 23/00, 53/00 U.S. Cl. 21540 11 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The present invention relates to an improved screw type closure cap adapted to provide an effective sealing closure for the open end of a bottle or container and which may be easily removed therefrom.

For many applications, it is imperative that a bottle or other container be completely sealed to preclude any leakage of the contents. Such a seal is particularly essential when the contents of the container constitute a gas or a liquid containing gas. Likewise, a good seal is essential when the inward or outward pressure on the con tainer might vary significantly, such as would occur if it is necessary to heat sterilize the container and contents. A conventional method for sealing such containers is to employ a screw cap for the container which creates a seal by compressing resilient rubber or similar elastomeric material against the end of the container. The sealing pressure pre-set upon the screw cap is maintained by the holding force of the screw cap on the threads of the container. The problem presented by a screw cap of this type is that a balance must be established between the downward pressure or force required for an effective seal and the torque required to unscrew the cap from the container. In many cases, to facilitate removal of the cap, pressure required for an effective seal is sacrificed.

Also, if the container constitutes a glass bottle, a specialized machine must be employed to obtain a smooth top surface on the bottle neck for sealing purposes. Regular blowing machines used in the production of bottles adapted to receive a plug stopper do not produce a top sealing surface of sufficient smoothness to provide a good seal with conventional screw caps at pressures which permit manual removal of the cap.

In an attempt to provide an effective sealing cap while facilitating cap removal from a sealed container, tamperproof caps have been developed which include a screw cap having an integral sealing skirt formed by a tear strip which is operable to break the seal of the container. Once the tear strip is removed, air is permitted to freely enter the container under the screw cap to remove frictional forces which counteract cap removal.

Such sealing caps require the provision of auxiliary gaskets on the tear strip to produce a seal against the side of the container. Not only are effective side seals difficult to achieve due to the necessity for providing high sealing forces against the side of a container with a thin tear strip, but also rupture of the tear strip completely destroys the sealing capability of the cap.

It is a primary object of the present invention to provide 3,664,536 Patented May 23, 1972 a novel and improved screw type closure cap which is adapted to provide a high sealing pressure against a supporting container but which may be easily removed from the container by the manual application of a low removal torque.

Another object of the present invention is to provide a novel and improved screw type closure cap which will provide an effective seal for glass bottles formed by conventional blowing machines which may include slight irregularities in the cap engaging surfaces.

A further object of the present invention is to provide a novel and improved screw type closure cap which is rendered tamper proof by an overcap applied to a screw threaded sealing cap; such overcap attributing a high sealing pressure to the sealing cap.

Another object of the present invention is to provide a novel and improved screw type closure cap which includes an overcap applied to a screw threaded sealing cap to increase the sealing pressure of the sealing cap; the normal sealing capabilities of the sealing cap being retained upon destruction of the overcap.

A still further object of the present invention is to provide a novel method for forming a screw type sealing cap by applying a first cap to a container at a first pressure and subsequently forming threads therein to engage the container and then applying a second cap to the first cap at a second higher pressure and subsequently engaging the second cap to the container.

These and other objects of the present invention will become readily apparent upon consideration of the following specification and claims taken in conjunction with the accompanying drawing in which:

FIG. 1 is an exploded sectional view of the screw type closure cap;

FIG. 2 is a sectional view illustrating the sealing cap portion of the screw type closure cap in place on a container;

FIG. 3 is a sectional view illustrating the screw type closure cap in place on a container; and

FIG. 4 is a sectional view of an embodiment of the overcap for the screw type closure cap.

Referring to the drawing, the screw type closure cap of the present invention indicated generally at 10 includes a sealing cap 12 adapted to close the open end of a container 14. For purposes of description, the container 14 is illustrated as a glass bottle of conventional construction having a neck 16 provided with external screw threads 18 which extend from a point adjacent the bottle opening to an enlarged sealing ring 20. It is apparent that other containers having cap engaging means equivalent to the external screw threads and sealing ring may be employed with the screw type closure cap 10.

The sealing cap 12 includes a top closure wall 22 with a cylindrical skirt 24 depending therefrom. The skirt 24 is formed with internal screw threads 26 which are adapted to engage the external threads 18 on the bottle 14. Thus the sealing cap is operable in the same manner as conventional screw type bottle caps, and upon rotation of the sealing cap, the threads 26 may be engaged with the threads 18 to draw the sealing cap down over the open end of the bottle until the lower portion of the skirt 24 contacts the sealing ring 20.

A sealing disc 28 of rubber, plastic, or similar material may be adapted to fit within the sealing cap to form a seal between the sealing cap and the top edge of the bottle neck 14. Also, a metallic disc 30 of aluminum or similar metal may be provided to separate the sealing disc from the top closure wall 22 of the sealing cap. Both the sealing disc and metallic disc are formed to a diameter which is greater than the diameter of the bottle neck so that these discs extend laterally beyond the confines of the bottle neck when the sealing cap is engaged therewith. In

many containers, such as drink and food containers, the separate sealing and

metallic discs

28 and 30 may be omitted and replaced by a layer of elastomeric material bonded to the top closure wall 22 of the sealing cap.

As illustrated in FIG. 2, the sealing cap may be threaded onto the neck of the bottle 14 unil the top closure wall 22 thereof compresses the sealing disc 28 to provide a sealing closure for the open end of the bottle. In this manner, the sealing cap operates as a conventional bottle cap. However, it will be noted in FIG. 2 that the internal threads 26 of the sealing cap do not fill the spaces between the external bottle threads 18. Instead, the internal threads 26 contact only the underside of the external threads 18, and the bottom of each internal thread is spaced above the top of the next suceeding external thread.

The sealing cap 12 is removably secured to the bottle 14 so as to exert sealing pressure downwardly against the sealing disc 28. This sealing pressure is limited to a value which will permit easy manual removal of the sealing cap from the bottle.

To increase the effective sealing pressure of the sealing cap 12, an overcap 32 is provided. This overcap includes a top wall 34 adapted to engage the top wall 22 of the sealing cap and a depending skirt portion 36. The lower periphery of the skirt portion 36 is provided with an indented rim 38 which extends under the sealing ring to lock the overcap onto the bottle 14.

This indented rim portion may be part of a tear away section or the rim portion might be of rolled metal similar to that used in bottle caps where an opener is employed to snap the rim over the sealing ring to remove the cap. Also, the overcap may incorporate design features which make the use of screw threads feasible to retain the overcap on the container neck as will subsequently be described in connection with FIG. 4.

The overcap 32 may be constructed to provide a tamper proof protective cap for the sealing cap 12, and in this form, the overcap constitutes a tear away cap which must be torn from the bottle before the sealing cap can be removed. The overcap may be formed of metal foil material which is adapted to be torn or of stronger metal, plastic or similar material having a weakened rupture line or tear strip. For example, the juncture 39 between the indented rim 38 and the skirt portion 36 may be weakened so that the indented rim may be severed from the skirt portion to permit removal of the overcap.

The overcap 32 is engaged with the bottle 14 in a manner which causes the overcap to exert a downward pressure on the sealing cap 12 which is greater than the pressure previously applied by the sealing cap to the sealing disc 28. Thus, with the overcap in place as illustrated in FIG. 3, the sealing cap is moved downwardly to increase the sealing pressure between the sealing disc and the upper edge of the bottle neck. The metallic disc 30 applies force across the top surface of the sealing disc, thereby causing the sealing disc to overhang the neck of the bottle 14 and to engage the sides thereof adjacent the bottle opening. This added side seal is effective when the edge of the bottle adjacent to the opening is irregular.

It will be noted that with the overcap in place, the internal threads 26 of the sealing cap are moved downwardly away from engagement with the underside of the external threads 18 on the bottle neck so that substantially all contact between the internal threads and the external threads is eliminated. The internal threads are formed so that when contact with the bottom of an external thread is broken, there is still space between the bottom of an internal thread and the next succeeding external thread. Thus with the overcap in place, the internal threads are somewhat free floating and substantially no pressure exists between these threads and the bottle neck 14. This provides limited compensation for internal pressure variations within the bottle.

If only the sealing cap 12 were to provide the increased sealing pressure added by the overcap 32, it would be difficult to manually remove the sealing cap from the bottle 14. However, when the overcap is removed, the sealing cap again returns to the position of light seal illustrated in FIG. 2, and may be easily removed manually. It is important to note that removal of the overcap does not destroy the seal provided by the sealing cap.

The increased pressure provided by the overcap 32 positively eliminates the incidence of container leakage occurring when the lower sealing pressure necessary for the manual removal of the conventional screw seal caps is employed. Additionally, use of the screw type closure cap 10 makes it unnecessary to employ special machinery to form the sealing surface at the top of a glass bottle neck, and regular blowing machines may be used.

In accordance with the method of the present invention, the screw type closure cap 10 is formed by placing a threadless cap blank for the sealing cap 12 with the sealing disc 28 and metal disc 30 in place, over the end of the bottle neck 16. A first downward force is then applied to the top closure wall 22 of the cap blank to compress the sealing disc, such first force being limited to a value which will facilitate subsequent manual removal of the finished sealing cap. For purposes of description, a force of 25 lbs. will be employed.

With a 25 lb. force on the sealing cap blank, the internal threads 26 are rolled into the sealing cap blank to mate with the external threads 18 on the bottle 14. To obtain the proper spacing of the internal threads between the external threads, the internal threads may be rolled to be smaller in radius than the clearance of the external threads on the bottle, or the relative pitch of the internal and external threads may be varied to provide the desired spacing. It will be noted in FIG. 2 that the internal threads 26 extend inwardly beyond the outer confines of the dealing disc 28 and metallic disc 30 so that these discs are retained within the sealing cap by the internal threads when the sealing cap is removed from the bottle. In some cases, it is desirable to form a seal retaining projection 26a during the formation of the internal threads to engage and positively retain the sealing disc.

After the sealing cap 12 is secured to the bottle 14, an overcap blank without the rim 38 is placed over the sealing cap and a second downward force of greater magnitude than the first force previously applied to the sealing cap blank is applied to the top wall 34 thereof. For descriptive purposes only, the second force will be denoted as lbs.

The second force further compresses the sealing disc 28 to provide a final seal, and once this seal is established, the rim 38 is rolled into the overcap blank to mate the overcap with the sealing ring 20.

Referring now to FIG. 4 an embodiment of the overcap 32 of FIGS. 13 is illustrated. This overcap, indicated at 40, is designed for use with containers having external threads 18 which extend down the container or bottle neck beyond the sealing ring 20 in FIGS. l-3. As the bottle neck tapers outwardly, the external threads in this area extend laterally beyond the external threads adjacent the bottle opening, and therefore these threads may receive the overcap 40 as the overcap is fit over the sealing cap 12.

The overcap 40 includes a top Wall 42 and a depending skirt portion 44. The lower section of this skirt portion is formed with internal screw threads 46 which are adapted to engage the external threads 18 on the bottle 14 below the lowermost extremity of the sealing cap when the sealing cap is in place on the bottle.

The top wall 42 of the overcap 40 is formed to minimize the frictional contact between the overcap and the sealing cap 12. Thus cap seats 48 are provided on the internal surface of the overcap top wall to engage the top wall 22 of the sealing cap. These cap seats may be formed by scoring, punching, or otherwise indenting the top wall 42 to provide projecting cap seats of minimal contact area. Thus, when the overcap 40 is threaded onto the externl threads 18 over the sealing cap 12 to exert an increased downward pressure on the sealing disc 28, only the cap seats 48 will contact the top Wall of the sealing cap. This minimal contact permits the overcap to be manually removed with ease, as frictional contact with the sealing cap has been minimized.

It will be apparent that the present invention provides a novel tamper-proof screw type cap which is adapted for use on a wide variety of containers. This cap greatly enhances the normal sealing ability of a threaded sealing cap while maintaining the sealing capability of such sealing cap when the overcap is removed.

I claim:

1. A sealing closure for the open end of the neck portion of a container, said neck portion being provided with external closure retaining means, comprising:

a first cap (12) for closing the container opening, said first cap having a first top wall portion (22) adjacent the extremity of said container open end, and a first cylindrical skirt portion (24) arranged concentrically about said container open end;

a layer of resilient sealing material (28) arranged Within said first cap adjacent said top closure wall portion for engaging and sealing the open end of said container;

internal engagement means (26) carried by the lower end of the skirt portion of said first cap for engaging said container external closure retainer means to progressively compress said layer of resilient sealing material to a desired first degree of compression, said internal engagement means being formed to permit limited longitudinal movement of said first cap relative to said external closure retaining means after engagement therewith;

overcap means (32) adapted to overlie said first cap, said overcap means including a second top wall portion (34) arranged above and parallel with said first top wall portion, and a second cylindrical skirt portion (36) arranged concentrically about said first skirt portion; and

connecting means (38, 46) for connecting said overcap means with said container to apply pressure upon said first cap to further compress said layer of resilient sealing material to a desired second degree of compression.

2. A sealing closure as defined in claim 1, wherein said connecting means for connecting said overcap means with said container comprises radially inwardly directed tear-away rim means (38) carried by the lower extremity of said second skirt portion for engagement with a corresponding external annular shoulder on said container.

3. A sealing closure for the open end of a container having external closure retaining means, comprising:

a first cap adapted for mounting across the container opening;

a layer of resilient sealing material provided within said first cap for engaging and sealing the open end of said container;

a separation disc positioned between said layer of resilient sealing material and said first cap;

internal engagement means carried by said first cap for engaging said external closure retaining means to compress said resilient sealing material to provide a light seal against the open end of said container, said internal engagement means being formed to permit limited longitudinal movement of said first cap relative to said closure retaining means after engagement therewith; and

overcap means adapted to overlie said first cap and to engage said closure retaining means to apply external pressure to said first cap in a direction to further compress said layer of resilient sealing material and thereby provide increased sealing pressure against the open end of said container.

4. The sealing closure of claim 3 wherein said separator disc and resilient layer constitute independent elements separate from said first cap and unattached thereto.

5. A sealing closure for the open end of a container having external screw-thread closure retaining means formed thereon, comprising:

a first cap adapted for mounting across the container opening, said first cap including internal screwthread engagement means for engaging said external closure retaining means, the teeth of said external closure retaining means being spaced to permit said internal threads to move longitudinally therebetween, thereby affording limited longitudinal movement of said first cap relative to said external closure retaining means after engagement therewith; and

overcap means adapted to overlie said first cap and to engage said closure retaining means, said overcap means operating when engaged with said closure retaining means to apply external pressure to displace said first cap longitudinally against the open end of said container to increase the sealing pressure thereof.

6. The sealing closure of claim 5 wherein said external closure retaining means includes a projecting bead formed below said external threads, said overcap having a depending fiange adapted to engage said projecting bead to hold said overcap against said first cap.

7. The sealing closure of claim 6 wherein a layer of resilient sealing material is provided within said first cap for engaging and sealing the open end of said container, a metallic separator disc is positioned between said layer of resilient sealing material and said first cap, and said overcap means is formed by a tearaway cap.

8. The sealing closure of claim 4 wherein said separator disc and resilient layer are formed to extend laterally beyond the confines of the open end of said container when said first cap engages said closure retaining means.

9. The sealing closure of claim 7 wherein said first cap includes an inwardly projecting retaining bead formed internally thereof and spaced from said internal threads to engage and retain said resilient sealing material.

10. The sealing closure of claim 1 wherein said overcap means includes inwardly projecting contact surface means for engaging said first cap when said overcap means is engaged with said closure retaining means, said contact surface means being formed to reduce the contact area between said overcap means and first cap.

11. The sealing closure of claim 5 wherein said overcap means includes internal thread means for engaging said external threads on said container below the lower extremity of said first cap when said first cap is in place on said container, said overcap means including inwardly projecting contact surface means for engaging said first cap, said contact surface means being formed to reduce the contact area between said overcap means and first cap.

References Cited UNITED STATES PATENTS 3,158,282 11/1964 Housz 22029 X 3,303,955 2/1967 Osborne et al 215-42 X GEORGE T. HALL, Primary Examiner U.S. Cl. X.R.