Patent Application
20060163192
1. Field of the Invention
This invention relates generally to closures and, more particularly, to plastic linerless closures.
2. Description of the Related Technology
Over the past few decades, the packaging industry has embraced plastic linerless closures to replace conventional metal closures for such applications as hermetic and vacuum applications in the food industry and for use in packaging carbonated beverages.
An important application of plastic linerless closures is the beverage industry, such as for packaging pressurized water. Attempts have been made to replace metal closures which are conventional in the beverage industry with a plastic linerless closure. Plastic closures are generally preferred over metal closures for a number of reasons. For example, plastic closures are considered safer than metal 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 pressurized beverage container and are able to withstand consumer mishandling to a much greater extent than are metal closures. Plastic closures may be molded, making it easy to integrate features such as ventilation and areas that are designed to frictionally engage the threading of the container finish in order to brake the closure as it is being removed from the container.
The first generation of plastic closures typically utilized a compressible liner in order to compensate for possible roughness or unevenness on the top rim of the container finish. The pressure created by the torque of application would compress the liner until its surface would conform to the contour of the bottle rim to provide the desired seal. More recently, however, second-generation linerless closures have been developed featuring integral sealing gaskets that are compressed on the closure is secured to a container. These integral gaskets or sealing members are often more effective than the compressible sealing liners that were used in lined closures. Moreover, linerless closures are generally preferred in that they are more economical in manufacture. They are also preferable to lined closures in the context of recycling.
An example of a linerless closure 10 is depicted in
Unfortunately, closures such as that described with reference to
A need clearly existed for an improved linerless closure that would provide the substantial benefits of a linerless closure but that is less likely to suffer from stress-related cracking and related degradation than was existing conventional linerless closures.
Accordingly, it is an object of the invention to provide an improved linerless closure that delivers the substantial benefits of a linerless closure but that is less likely to suffer from stress-related cracking and related degradation than was existing conventional linerless closures.
In order to achieve the above and other objects of the invention, a linerless closure that is constructed according to a first aspect of the invention includes a top panel having external and internal surfaces; a generally cylindrical sidewall that is unitary with the top panel and has a threaded internal surface; a shoulder portion defined between the internal surface of the top panel and the internal surface of the sidewall; a linerless sealing member extending radially inwardly from the shoulder portion; a first radius defined in the shoulder portion between the linerless sealing member and the internal surface of the top panel; and a second radius defined in the shoulder portion between the linerless sealing member and the internal surface of the sidewall, and wherein both the first radius and the second radius are at least 0.020 inches.
An improved linerless plastic closure according to a second aspect of the invention includes a top panel having external and internal surfaces; a generally cylindrical sidewall, the sidewall being unitary with the top panel and having a threaded internal surface; a shoulder portion defined between the internal surface of the top panel and the internal surface of the sidewall; a linerless sealing member extending radially inwardly from the shoulder portion; a first radius defined in the shoulder portion between the linerless sealing member and the internal surface of the top panel; and a second radius defined in the shoulder portion between the linerless sealing member and the internal surface of the sidewall, and wherein the first radius is at least 0.020 inches.
An improved linerless plastic closure according to a third aspect of the invention includes a top panel having external and internal surfaces; a generally cylindrical sidewall, the sidewall being unitary with the top panel and having a threaded internal surface; a shoulder portion defined between the internal surface of the top panel and the internal surface of the sidewall; a linerless sealing member extending radially inwardly from the shoulder portion; a first radius defined in the shoulder portion between the linerless sealing member and the internal surface of the top panel; and a second radius defined in the shoulder portion between the linerless sealing member and the internal surface of the sidewall, and wherein the second radius is at least 0.020 inches.
An improved linerless plastic closure according to a fourth aspect of the invention preferably includes a top panel having external and internal surfaces; a generally cylindrical sidewall that is unitary with the top panel and has a threaded internal surface; a linerless sealing member extending radially inwardly from an area that is adjacent to an area of connection between the sidewall and the top panel; a first radius defined between the linerless sealing member and the internal surface of the top panel; and a second radius defined between the linerless sealing member and the internal surface of said sidewall, and wherein the first radius is at least 0.020 inches.
An improved linerless plastic closure according to a fifth aspect of the invention preferably includes a top panel having external and internal surfaces; a generally cylindrical sidewall that is unitary with the top panel and has a threaded internal surface; a linerless sealing member extending radially inwardly from an area that is adjacent to an area of connection between the sidewall and the top panel; a first radius defined between the linerless sealing member and the internal surface of the top panel; and a second radius defined between the linerless sealing member and the internal surface of said sidewall, and wherein the second radius is at least 0.020 inches.
These and various other advantages and features of novelty that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.
Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and referring in particular to
Closure 30 is preferably fabricated from high-density polyethylene, which provides taste advantages and advantages in sealing properties with respect to alternative materials such as polypropylene.
A thickened shoulder region 46 is defined proximate the area where sidewall 38 joins top panel 32. Shoulder region 46 is preferably thicker in a radial direction than an average thickness of sidewall 38, and is also preferably thicker in a longitudinal, axial direction than an average thickness of top panel 32. Extending radially inwardly and slightly downwardly from shoulder portion 46 is a flexible linerless sealing member 48. The interior surface of shoulder portion 46 and flexible linerless sealing member 48 are preferably constructed so that they extend in annular fashion so as to have a regular cross-section throughout the entire axis of rotation of the closure 30.
An annular pressure rim 50 is preferably defined on the internal surface 36 of the top panel 32 to aid in sealing when the closure 30 is securely mounted upon a container.
According to one advantageous aspect of the invention, a first radius R1 is defined in an internal surface of the shoulder region 46 between the linerless sealing member 48 and the internal surface 36 of top panel 32. First radius R1 intersects the internal surface 36 of the top panel 32, as is shown in
A second radius R2 is also advantageously defined in the internal surface of the shoulder region 46 between the linerless sealing member 48 and the internal surface 42 of the sidewall 38. Second radius R2 intersects the internal surface 42 of the sidewall 38, as is shown in
The first and second radii R1, R2 may be although not necessarily are substantially the same dimension.
Closure 30 has been found to exhibit significantly improved resistance to stress-related cracking with respect to the conventional closure structure that is discussed above with reference to
It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
