Claims
- 1. A closure and container combination, comprising:
- a container having an open end, said end having a top surface and an inner surface; and,
- a closure, adapted to be applied to said open end of said container, having a skirt, and a top coupled to said skirt, said top including:
- a sealing member adapted to engage said top surface of said end of said container with application of said closure to said end;
- an inner sealing region having an outwardly facing sealing surface adapted to be situated contiguous with said inner surface of said end of said container with application of said closure to said end;
- a central region coupled to said inner sealing region; and, means, coupled to said skirt, for enhancing engagement of said sealing member with said top surface of said end of said container in response to lifting of said inner sealing region relative to said skirt.
- 2. A closure and container combination, comprising:
- a container having an opening therein, and exterior and inner surfaces adjacent said opening; and,
- a closure, adapted to be applied to said opening of said container, having a skirt, and a top coupled to said skirt, said top including:
- a sealing member adapted to engage said exterior surface of said container with application of said closure to said opening;
- an inner sealing region having an outwardly facing sealing surface adapted to be situated contiguous with said inner surface of said container with application of said closure to said opening;
- a central region coupled to said inner sealing region; and,
- means, coupled to said skirt, for enhancing engagement of said sealing member with said exterior surface of said container in response to lifting of said inner sealing region relative to said skirt.
- 3. The closure and container combination according to claims 1 or 2, wherein said central region is non-planar and is displaceable in response to pressure differences between the interior of said container and the exterior of said container, whereby displacement of said central region generates a force that urges said inner sealing region tighter against said inner surface and said means coupled to said sealing member and said inner sealing region further impart said force to said displaceable sealing member.
- 4. The closure and container combination according to claim 3, wherein said central region is concave and said container holds contents stored under a positive pressure.
- 5. The closure and container combination according to claim 4, wherein said central region is convex and said container holds contents stored under a negative pressure.
BACKGROUND OF THE INVENTION
This application is a continuation of application Ser. No. 675,603 filed 11/28/84, now U.S. Pat. No. 4,574,966, which is a continuation-in-part of application Ser. No. 549,477 filed Nov. 7, 1983, now U.S. Pat. No. 4,550,841 which is a continuation-in-part of application Ser. No. 441,546 filed Nov. 15, 1982, now U.S. Pat. No. 4,479,585, which is a continuation-in-part of application Ser. No. 399,237 filed July 19, 1982, now U.S. Pat. No. 4,442,945, which is a continuation-in-part of application Ser. No. 335,216 filed Dec. 28, 1981, now U.S. Pat. No. 4,413,742.
This invention relates generally to closures and, more particularly, to plastic linerless closures.
A great deal of effort has been directed to the design and development of a multi-application plastic linerless closure to replace conventional metal closures. Plastic linerless closures find use in such general areas as hermetic and vacuum applications in the food industry and in carbonated beverage applicatins. Other markets include pharmaceutical, cosmetics and dairy.
An important application of plastic linerless closures is the carbonated beverage industry. Attempts have been made to replace metal closures which are conventional in the carbonated beverage industry with a plastic linerless closure. In particular, the conventional aluminum roll-on carbonated beverge closures, such as disclosed in U.S. Pat. No. 3,601,273 to Kutcher, require expensive equipment to roll the aluminum shell onto the container threads and have become increasingly expensive due to the high cost of aluminum. Plastic closures are generally preferred over aluminum closures for other reasons. For example, plastic closures are considered safer than aluminum closures in that the possibility of the user being cut during handling the closure is eliminated. Plastic closures may be less likely to blow off from a carbonated beverage container and are able to withstand consumer mishandling to a much greater extent than are aluminum closures. Plastic closures are perceived by consumers as being cleaner than aluminum roll-on containers and on-torquing and off-torquing forces are less than the smaller diameter aluminum roll on closures. Indeed, surveys have indicated that consumers believe that beverages from a container sealed with a plastic closure taste better than in the case where the container is sealed by an aluminum closure. Significant savings can also be achieved utilizing plastic closures in that, for example, the thick glass and plastic neck finishes necessary for aluminum closures to withstand the high pressure during formation of the closure are not required for plastic closures. Container weight and container manufacturing cycle time can be reduced if these high pressures are not required.
Early plastic closures designed to replace conventional metal sealing closures usually incorporated a liner to compensate for the unevenness and ragged edges on the top lip or land of glass and plastic bottles. The pressure of application torque compresses the liner and its surface conforms to the contour of the top of the bottle to provide the seal. However, the development of plastic materials, such as polyethylene and polypropylene, has enabled linerless closures to be developed with integral sealing features which are often more effective than in the case of lined closures. Moreover, linerless closures are generally preferred in that they are more economical in manufacture.
Prior attempts to provide a suitable plastic linerless carbonated beverage closure have not been entirely successful. A plastic linerless closure must satisfy at least two criteria, namely low cost and good performance. The plastic closure must be cost competitive with the aluminum roll on closure. With respect to performance, the seal attained by the aluminum roll on closure is generally considered to be effective over an indefinite shelf life period if it has been properly applied. Removal torques are relatively constant over the full use temperature range. Aluminum is not affected by factors such as stress cracking from which previously suggested plastic linerless closures suffer. Plastic closures should be capable of being applied on a wide variety of capping lines and be designed to incorporate relatively simple yet effective tamper evident indicators.
Plastic linerless closures have been designed with a so-called land seal formed across the top of the neck finish or with a so-called valve seal formed on the inside or outside of the neck finish. Indeed, closures utilizing the combination of both types of seals have been suggested. A closure available from Sun Coast Plastic Closures, Inc. of Sarasota, Fla. includes two flexible wide angle sealing flanges which edge seal, independently of each other, with the inside and outside edges of the container neck. However, this closure has not been proven entirely satisfactory in that when applied to carbonated beverage containers, the pressure of the container contents tends to reduce the sealing force of the inner flange on the inside edge of the container neck. If this inner seal developes a leak, the container pressure will act on the outer flange and also thereby affect the overall reliability of the closure sealing. This closure is also subject to cracking due to stresses created in the region of the closure top between the inner and outer sealing flanges by vacuum, pressure or just the container to closure interface.
Other plastic linerless closures have been suggested. All of these prior closures utilize one or a combination of top or land and side or valve sealing flanges which act independently of each other. The seals provided by virtually all of such closures are the result of local deformations in the sealing flanges which occur when they are forced against the container neck. The reliability of these seals is adversely affected by the container pressure which acts in a manner which tends to reduce the sealing effectiveness, especially over extended periods of time due to cold flow or creep of the plastic. All plastics when loaded not only deform but continue to yield because of their viscoelastic nature. The sealing flanges utilized in conventional plastic linerless closures apply to carbonated beverage containers are continuously subjected to forces which tend to reduce their sealing effectiveness and over extended periods of time their sealing reliability is permanently reduced due to the cold flow or creep of the plastic material.
Accordingly, it is an object of the present invention to provide a new and improved plastic linerless closure for use in hermetic, vacuum and carbonated beverage applications.
Another object of the present invention is to provide a new and improved plastic linerless closure for carbonated beverage applications which is cost competitive with conventional aluminum roll on closures.
Still another object of the present invention is to provide a new and improved plastic linerless carbonated beverage closure which forms a seal which is competitive with the seal provided by conventional aluminum roll-on closures and which is significantly more reliable than seals provided by currently available plastic linerless closures.
A further object of the present invention is to provide a new and improved plastic linerless carbonated beverage closure which forms a seal with the container which is not adversely affected but, rather, is enhanced under the force of container pressure.
A still further object of the present invention is to provide a new and improved plastic linerless carbonated beverage closure which is not subject to stress cracking, which is capable of being applied on a wide variety of capping lines and is capable of incorporating relatively simple yet effective tamper evident indicators.
Briefly, in accordance with the present invention these and other objects are attained by providing a plastic linerless closure having an integrated sealing mechanism including a primary top or land sealing region, a secondary inner sealing region and a central region which are formed such that sealing and central regions act in concert with each other in the form of a mechanical linkage during and after torquing of the closure onto the container to effect top and inner seals with the container neck. The flexural deformation of the primary top seal during engagement with the neck top is transmitted to the inner seal region in a manner to cause the inner seal to expand outwardly into tight sealing engagement with the inner surface of the container neck to thereby effect mutual primary top and inner seals.
The central region of the closure top forms a part of the integrated mechanical linkage along with the primary and inner sealing regions. The upward force exerted on the central region of the closure top by the contained pressure of carbonation is transmitted through a part of the secondary sealing region and a part of the primary sealing region in a manner which tends to rotationally flex the primary seal to enhance its sealing engagement with the neck top. The central region of the closure top preferably has a non-planar configuration such that the internal pressure (or vacuum) acting on it tends to flex or deform the top in a manner so as to expand the inner seal to enhance its sealing engagement with the inner surface of the neck. Moreover, the tendency of the central region of the closure and top to flex under the pressure (or vacuum) of the container contents to expand the inner seal is transmitted to the primary sealing region to further enhance its sealing engagement with the neck top.
A mechanism is thereby provided by which the inner sealing region is expanded radially outwardly during and after the application of the closure to the container to urge the inner sealing region tightly into sealing engagement with the inner surface of the container neck to provide a reliable seal. The mechanism is constituted by the primary sealing region which is situated between the closure skirt and the inner sealing region. The configuration of the primary sealing region is such that when the container neck acts upon it during application of the closure to the container, its flexural deformation (which effects the primary top seal) is transmitted to the inner sealing region to expand the latter tightly into engagement with the inner neck surface to effect the inner seal.
US Referenced Citations (5)
Foreign Referenced Citations (4)
| Number |
Date |
Country |
| 1117478 |
Feb 1982 |
CAX |
| 119788 |
Sep 1984 |
EPX |
| 2641543 |
Mar 1977 |
DEX |
| 607702 |
Oct 1978 |
CHX |
Continuations (1)
|
Number |
Date |
Country |
| Parent |
675603 |
Nov 1984 |
|
Continuation in Parts (4)
|
Number |
Date |
Country |
| Parent |
549477 |
Nov 1983 |
|
| Parent |
441546 |
Nov 1982 |
|
| Parent |
399237 |
Jul 1982 |
|
| Parent |
335216 |
Dec 1981 |
|
Patent Grant
4714167
