Linerless plastic closure

Abstract

An improved linerless plastic closure includes a top panel that has external and internal surfaces and a generally cylindrical sidewall that is unitary with the top panel and has an internally threaded surface that is adapted to engage with a threaded finish portion of a container. A shoulder portion is defined between the internal surface of the top panel and the internal surface of the sidewall. A linerless sealing member extends radially inwardly from the shoulder portion. A first radius is defined in the shoulder portion between the linerless sealing member and the internal surface of the top panel. A second radius is defined in the shoulder portion between the linerless sealing member and the internal surface of the sidewall. But the first and second radii are preferably configured to be at least 0.020 inches, which has been found to reduce the potential for stress-related cracking.

Description

BACKGROUND OF THE INVENTION

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 FIG. 1. Closure 10 included a top panel 12 having an exterior upper surface and an interior lower surface, and a generally cylindrical sidewall 14 having an external surface and internal surface upon which at least one interior threaded 16 is defined. A thickened shoulder portion 18 is defined where the top panel 12 joins the sidewall 14, and a linerless sealing member 20 extends radially inwardly and downwardly from the shoulder portion 18. A first radius R1_P is defined in the shoulder portion 18 between the linerless sealing member 20 and the interior surface of the top panel 12. A second radius R2_P is defined in the shoulder portion 18 between the linerless sealing member 20 and the interior surface of sidewall 14. In this particular closure, both the first and second radii were constructed to be about 0.10 inches.

Unfortunately, closures such as that described with reference to FIG. 1 were found in practice to be more susceptible to stress-related damage than was desirable, which often led to small cracks developing within the closure. Closures fabricated from high-density polyethylene were especially susceptible to such failure, which was disappointing considering this material has substantial advantages over alternative material such as polypropylene. These advantages include better taste characteristics and superior sealing properties.

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.

SUMMARY OF THE INVENTION

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.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatical cross-sectional view of a conventional linerless plastic closure; and

FIG. 2 is a diagrammatical cross-sectional view of a linerless plastic closure that is constructed according to a preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and referring in particular to FIG. 2, an improved linerless plastic closure 30 that is constructed according to a preferred embodiment of the invention includes a top panel 32 having an upper external surface 34 and a lower, internal surface 36. Top panel 32 is unitary with a downwardly depending generally cylindrical sidewall 38 that has an exterior surface 40 and internal surface 42 that has at least one thread 44 defined thereon for engaging with an external threaded surface of the finish portion of a container.

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 FIG. 2. First radius R1 is preferably at least 0.020 inches, and is preferably within a range of about 0.020 inches to about 0.036 inches. More preferably, first radius R1 is within a range of about 0.023 inches to about 0.030 inches.

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 FIG. 2. Second radius R2 is preferably at least 0.020 inches, and is preferably within a range of about 0.020 inches to about 0.036 inches. More preferably, second radius R2 is within a range of about 0.023 inches to about 0.030 inches.

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 FIG. 1.

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.

Claims

1. An improved linerless plastic closure, comprising:

a top panel having external and internal surfaces;

a generally cylindrical sidewall, said sidewall being unitary with said top panel and having a threaded internal surface;

a shoulder portion defined between said internal surface of said top panel and said internal surface of said sidewall;

a linerless sealing member extending radially inwardly from said shoulder portion;

a first radius defined in said shoulder portion between said linerless sealing member and said internal surface of said top panel; and

a second radius defined in said shoulder portion between said linerless sealing member and said internal surface of said sidewall, and wherein both said first radius and said second radius are at least 0.020 inches.

2. An improved linerless plastic closure according to claim 1, wherein both said first radius and said second radius are within a range of about 0.020 inches to about 0.036 inches.

3. An improved linerless plastic closure according to claim 2, wherein both said first radius and said second radius are within a range of about 0.023 inches to about 0.030 inches.

4. An improved linerless plastic closure according to claim 2, wherein said first radius is within a range of about 0.023 inches to about 0.030 inches.

5. An improved linerless plastic closure according to claim 2, wherein said second radius is within a range of about 0.023 inches to about 0.030 inches.

6. An improved linerless plastic closure according to claim 1, wherein said closure is fabricated from high-density polyethylene.

7. An improved linerless plastic closure according to claim 1, wherein said shoulder portion is thicker in a radial direction than an average radial thickness of said sidewall.

8. An improved linerless plastic closure according to claim 1, wherein said shoulder portion is thicker in a longitudinal direction than an average longitudinal thickness of said top panel.

9. An improved linerless plastic closure according to claim 1, wherein said first radius is substantially equal to said second radius.

10. An improved linerless plastic closure according to claim 1, wherein said first radius intersects said internal surface of said top panel

11. An improved linerless plastic closure according to claim 1, wherein said second radius intersects said internal surface of said sidewall.

12. An improved linerless plastic closure, comprising:

a top panel having external and internal surfaces;

a generally cylindrical sidewall, said sidewall being unitary with said top panel and having a threaded internal surface;

a shoulder portion defined between said internal surface of said top panel and said internal surface of said sidewall;

a linerless sealing member extending radially inwardly from said shoulder portion;

a first radius defined in said shoulder portion between said linerless sealing member and said internal surface of said top panel; and

a second radius defined in said shoulder portion between said linerless sealing member and said internal surface of said sidewall, and wherein said first radius is at least 0.020 inches.

13. An improved linerless plastic closure according to claim 12, wherein said first radius is within a range of about 0.020 inches to about 0.036 inches.

14. An improved linerless plastic closure according to claim 13, wherein said first radius is within a range of about 0.023 inches to about 0.030 inches.

15. An improved linerless plastic closure according to claim 12, wherein said closure is fabricated from high-density polyethylene.

16. An improved linerless plastic closure according to claim 12, wherein said shoulder portion is thicker in a radial direction than an average radial thickness of said sidewall.

17. An improved linerless plastic closure according to claim 12, wherein said shoulder portion is thicker in a longitudinal direction than an average longitudinal thickness of said top panel.

18. An improved linerless plastic closure according to claim 12, wherein said first radius intersects said internal surface of said top panel

19. An improved linerless plastic closure according to claim 12, wherein said second radius intersects said internal surface of said sidewall.

20. An improved linerless plastic closure, comprising:

a top panel having external and internal surfaces;

a generally cylindrical sidewall, said sidewall being unitary with said top panel and having a threaded internal surface;

a shoulder portion defined between said internal surface of said top panel and said internal surface of said sidewall;

a linerless sealing member extending radially inwardly from said shoulder portion;

a first radius defined in said shoulder portion between said linerless sealing member and said internal surface of said top panel; and

a second radius defined in said shoulder portion between said linerless sealing member and said internal surface of said sidewall, and wherein said second radius is at least 0.020 inches.

21. An improved linerless plastic closure according to claim 20, wherein said second radius is within a range of about 0.020 inches to about 0.036 inches.

22. An improved linerless plastic closure according to claim 21, wherein said second radius is within a range of about 0.023 inches to about 0.030 inches.

23. An improved linerless plastic closure according to claim 20, wherein said closure is fabricated from high-density polyethylene.

24. An improved linerless plastic closure according to claim 20, wherein said shoulder portion is thicker in a radial direction than an average radial thickness of said sidewall.

25. An improved linerless plastic closure according to claim 20, wherein said shoulder portion is thicker in a longitudinal direction than an average longitudinal thickness of said top panel.

26. An improved linerless plastic closure according to claim 20, wherein said first radius intersects said internal surface of said top panel

27. An improved linerless plastic closure according to claim 20, wherein said second radius intersects said internal surface of said sidewall.

28. An improved linerless plastic closure, comprising:

a top panel having external and internal surfaces;

a generally cylindrical sidewall, said sidewall being unitary with said top panel and having a threaded internal surface;

a linerless sealing member extending radially inwardly from an area that is adjacent to an area of connection between said sidewall and said top panel;

a first radius defined between said linerless sealing member and said internal surface of said top panel; and

a second radius defined between said linerless sealing member and said internal surface of said sidewall, and

wherein said first radius is at least 0.020 inches.

29. An improved linerless plastic closure according to claim 28, wherein said first radius is within a range of about 0.020 inches to about 0.036 inches.

30. An improved linerless plastic closure according to claim 29, wherein said first radius is within a range of about 0.023 inches to about 0.030 inches.

31. An improved linerless plastic closure according to claim 28, wherein said closure is fabricated from high-density polyethylene.

32. An improved linerless plastic closure according to claim 28, wherein said second radius is also at least 0.020 inches.

33. An improved linerless plastic closure according to claim 32, wherein both said first and second radii are within a range of about 0.020 inches to about 0.036 inches.

34. An improved linerless plastic closure according to claim 33, wherein both said first and second radii are within a range of about 0.023 inches to about 0.030 inches

35. An improved linerless plastic closure, comprising:

a top panel having external and internal surfaces;

a generally cylindrical sidewall, said sidewall being unitary with said top panel and having a threaded internal surface;

a linerless sealing member extending radially inwardly from an area that is adjacent to an area of connection between said sidewall and said top panel;

a first radius defined between said linerless sealing member and said internal surface of said top panel; and

a second radius defined between said linerless sealing member and said internal surface of said sidewall, and wherein said second radius is at least 0.020 inches.

36. An improved linerless plastic closure according to claim 35, wherein said second radius is within a range of about 0.020 inches to about 0.036 inches.

37. An improved linerless plastic closure according to claim 36, wherein said second radius is within a range of about 0.023 inches to about 0.030 inches.

38. An improved linerless plastic closure according to claim 35, wherein said closure is fabricated from high-density polyethylene.