GB2429971A

GB2429971A - Closure with projection having an angled sealing surface

Info

Publication number: GB2429971A
Application number: GB0518593A
Authority: GB
Inventors: Keith Douglas
Original assignee: Ecocap Ltd
Current assignee: Ecocap Ltd
Priority date: 2005-09-12
Filing date: 2005-09-12
Publication date: 2007-03-14
Also published as: DK1931573T3; GB0518593D0; ES2403830T3; CN101370714B; US20100065569A1; GB2430930A; GB0616902D0; CN101370714A

Abstract

A closure 2 for closing an opening of a container 22, the closure comprising attachment means for attaching, in use, the closure to the container. A sealing surface 12 is inclined to a plane perpendicular to a central axis of the closure, and located such that when the closure is attached to the container by the attachment means the sealing surface is engageable with the container. The angled sealing surface 12 may be provided on a projection 10 which extends from a top 4 of the closure 2. The angled surface 12 may also have an arcuate profile. In another embodiment a closure is formed from a thermoplastic polymeric material comprising polylactic acid or a derivative thereof, and wherein the thermoplastic polymeric material is amorphous or at least partially amorphous.

Description

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CLOSURE

The present invention relates to a closure for closing an opening of a container. In particular, it relates to a closure device which is screwed onto a drinks container.

It is known to package potable fluids such as water in a container having a detachable closure to seal the container. The container and closure are typically moulded.

A thread or groove is formed on the bottle, around the opening, and a complimentary thread or groove is formed on the inside of the closure. If there are any inaccuracies in the moulding of the thread and groove, then the cap may not form a fluid tight seal over the opening. This may result in a leakage of fluid from the container.

The present invention provides, in a first aspect, a closure for closing an opening of a container, the closure comprising: attachment means for attaching, in use, the closure to the container; a sealing surface inclined to a plane perpendicular to a central axis of the closure, and located such that when the closure is attached to the container by the attachment means the sealing surface is engageable with the container.

The present invention provides, in a second aspect, a closure in combination with a container; the combination comprising: an attachment means for removeably attaching the closure to the container; the container comprising a neck defining an opening; the closure for closing the opening and comprising a sealing surface; the sealing surface inclined to a plane perpendicular to a central axis of the closure; the sealing surface located such that when the closure is attached to the container by the attachment means, the neck engages the sealing surface.

This has the advantage that a fluid tight seal is formed between the closure and the container, even if there are inaccuracies in the moulding of the closure or container.

Preferably, the neck of the container comprises a radiussed surface, the radiussed surface engageable with the sealing surface of the closure. Thus, a good seal is provided between the closure and the container.

Preferably, the sealing surface faces radially outwardly from the central axis of the closure. Thus, a good seal is provided between the closure and the container.

Preferably, the closure further comprises a second sealing surface inclined to the central axis of the closure.

Thus, the second sealing surface improves the seal between the closure and the container.

Preferably, the second sealing surface faces radially inwardly towards the central axis of the closure. Thus, the sealing surfaces face in opposite directions to provide a good seal.

Preferably, the neck comprises a radiussed surface for engagement with the second sealing surface. Thus, the surface area of the neck in contact with the sealing surface is increased.

Preferably, the or each sealing surface is annular.

Thus, a uniform sealing surface is provided which can be readily engaged with the container.

Preferably, the attachment means comprises one or more helical threads and grooves. Thus, a secure and releasable engagement means is provided.

Preferably, the or each projection comprises a cavity.

Thus, the projection is readily deformable when urged against the neck of the container, to ensure that a good seal is formed even if there are inaccuracies in the moulding.

Preferably, the neck comprises one or more cavity or cavities. Thus, the neck is readily deformable when urged against the sealing surface of the closure, to ensure that a good seal is formed even if there are inaccuracies in the moulding.

Preferably, the closure comprises a stop to limit movement of the neck relative to the closure. Thus, the projection or neck is not deformed so much that plastic deformation or breakage occurs.

Preferably, the closure is integrally moulded. Thus, the closure can be cheaply manufactured.

The following discussion is relevant to both the first and second aspects.

The closure or at least part of the closure will typically be formed from a polymeric material such as a thermoplastic or thermosetting material. A thermoplastic material is, however, preferred. Advantageously, the thermoplastic polymeric material comprises polylactic acid (PLA) (also known as poly(lactide)) or a derivative thereof.

This material has suitable mechanical, chemical and barrier properties and, furthermore, is an environmentally friendly material.

The inventor have found that it is advantageous if the polymeric material (e.g. PLA) is amorphous or at least partially amorphous. This has been found to result in improved mechanical properties. In particular, it has been found that a closure formed from a polymer having a high degree of crystallinity can be difficult to remove from the container, for example a plastic bottle with a screw thread attachment. Moreover, a highly crystalline polymer closure can fracture when it is attached to the container. A highly crystalline polymer may also result in the closure locking up or jamming on the bottle. Having identified this problem the inventor have found that improved mechanical properties can be achieved if the degree of crystallinity (volume) in the polymeric material is preferably less than 50 %, more preferably less than 30 %, still more preferably less than %.

The degree of crystallinity in the polymer material forming the closure may be reduced in a number of ways. For example, if the closure if formed by injection moulding or compression moulding, then desirable results can be achieved by ensuring that the mould cavity is filled relatively quickly, for example in = 1 second, preferably 0.5 seconds. Moreover, it is preferable that heat is removed from the closure, once moulded, as quickly as possible.

Heat can be conducted away from the moulded closure through the mould parts, for example the metal core and cavity.

Cooling means are preferably provided to cool the metal core and cavity. It is also preferable if the wall section of the moulded closure is = 2 mm, preferably = 1 mm.

The closure is preferably integrally formed from the polymeric material (e.g. PLA).

As to manufacture, the closure may, for example, be injection moulded or compression moulded.

In a further aspect, the present invention provides a closure for closing an opening of a container, wherein at least a part of the closure is formed from a thermoplastic polymeric material comprising polylactic acid (PLA) (also known as poly(lactide)) or a derivative thereof, and wherein the thermoplastic polymeric material is amorphous or at least partially amorphous.

The foregoing discussion in relation to the first and second aspects is also applicable to the further aspect of the present invention.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a cross-sectional view of a closure and container in accordance with the present invention; Figure 2 is a cross-sectional view of a second embodiment of the closure and container; Figure 3a is a cross sectional view of a third embodiment of the closure and container; Figure 3b is a cross sectional view of a fourth embodiment of the closure and container; Figure 4 is a cross sectional view of a fifth embodiment of the closure and container.

Figure 5 is a cross sectional view of a sixth embodiment of the closure and container.

Figure 6 is a cross sectional view of a seventh embodiment of the closure and container.

Referring to Figure 1 there is shown a container 22 having a neck 20. The remainder of the container 22 is not shown as its body shape may take any suitable form and may, for example, be of square, rectangular or circular cross- section, or another geometrical shape.

The neck 20 defines a circular opening 28 having a central axis and surrounded by a substantially smooth, cylindrical internal surface 30. An internal edge 24 is formed at an end of the internal surface 30 remote from the body of the container 22. An external surface 32 of the neck has an external edge 26 at an end remote from the body of the container 22, the external edge 26 being radially outside the internal edge 24.

The external surface 32 is provided with attachment means with which to engage complementary attachment means provided on a closure. The attachment means may take the form of a helical thread or groove 34. The thread or groove 34 may be a single thread or groove, or alternatively be in the form of a plurality of threads or grooves having different starting points.

The closure 2 is also shown in Figure 1. The closure 1 has a top 4 which is circular in plan view, and merges at a radially outer edge with a depending annular side wall 6.

The side wall 6 is provided, on its inner surface, with attachment means for releasable engagement with the complementary attachment means provided on the neck 20. The attachment means may take the form of one or more helical threads or grooves 8. The side wall 6 defines a central axis, extending longitudinally along an axis of symmetry of the closure. The central axis is marked as line A-A on Figure 1.

The closure 2 is provided with an annular projection 10 extending from the top 4, the projection 10 extending from the same side of the top 4 as the side wall 6. The projection 10 is provided with an angled, or sealing, surface 12, which faces radially outwardly and away from the top 4. The angled surface 12 is preferably angled at 45 degrees to the top 4, and may be angled between 10 and 80 degrees. The angled surface 12 can be considered to be inclined to a plane perpendicular to the central axis of the closure. The angled surface 12 could also be considered to be inclined to the longitudinal axis of the threads or grooves 8 of the closure.

The annular projection 10 is circumferentially spaced apart from the side walls 6. The angled surface 12 is located such that when the closure 2 is attached to the container 22 by the attachment means, the internal edge 24 of the neck 20 abuts against the angled surface 12 in order to close the opening 28.

The angled surface 12 is shown in profile to define a straight line. The angled surface may also have an arcuate profile. The effect of the angle is that the angled surface 12 and/or the neck 20 undergo a slight elastic deformation in a radial direction when urged together.

Figure 2 shows a second embodiment of the neck 20. The internal surface 30 has an internal radiussed surface 224 at an end remote from the body of the container 22. The closure 2 and the other features of the container 22 are as described in the first embodiment.

The internal radiussed surface 224 has a profile curved with a constant radius, or the surface 224 may take any arcuate form. The angled surface 12 may also have an arcuate profile, which may be complementary to radiussed surface 224. The radiussed surface 224 and angled surface 12 may abut each other to seal the opening 28. The internal surface 224 may alternatively be chamfered at an angle complimentary to the angle of the angled surface 12, as shown in Figure 2.

The radiussed surface 224 provides a greater surface area in contact with the angled surface 12 than provided by the edge 24.

Figure 3a shows a further embodiment of the closure 2.

The closure 2 is provided with a second projection 310. The second projection 310 is an annular projection extending from the top 4 in substantially the same direction as the annular projection 10 and side walls 6. The second projection 310 is located radially outwardly and spaced apart from the projection 10. The second projection 310 is provided with a second angled surface 312. The second angled surface 312 faces radially inwardly, and away from the top 4. The angled surface 312 is shown in profile to define a straight line. The angled surface 312 may also have an arcuate profile.

The second angled surface 312 is positioned to abut external edge 26 of the neck 20, in order to assist in the sealing of opening 28.

The second projection 310 may be the same size, or larger or smaller than the projection 10. The angled surface 312 may be orientated at the same angle from the top 4 as the projection 10, or alternatively, the second angled surface may be at a smaller or larger angle than the angled surface 12.

Figure 3a shows annular projection 10 in abutment with the internal radiussed surface 224 of the second embodiment.

Alternatively, the internal surface 30 may end at an internal edge, for example internal edge 24 as described in the first embodiment.

- L0 - Figure 3b indicates that external surface 32 of the neck 20 has an external radiussed surface 326 at an end remote from the body of the container 22. The external radiussed surface 326 may have a profile curved with a constant radius, or the surface 326 may have a profile of any arcuate form. The surface 326 may also have an arcuate profile, which may be complementary to radiussed surface 312. The radiussed surface 326 and angled surface 310 may abut each other to assist in sealing the opening 28.

The radiussed surface 326 may alternatively be chamfered at an angle complimentary to the angle of the angled surface 312, as shown in Figure 3b. The radiussed surface 326 provides a greater surface area in contact with the angled surface 310 than provided by the edge 26.

The abutment of the external radiussed surface 326 with the second angled surface 312 assists in sealing the opening 28.

Figure 4 shows an embodiment with differences from the second embodiment described above and shown in Figure 2. An annular projection 410 is provided on the top 4, the annular projection 410 having an angled surface 412 as a previously described. The annular projection 410 is not a solid projection, but comprises a cavity. The annular projection 410 is hollow and defines an annular groove 405 on the top 4. The annular projection 410 may alternatively comprise a cavity which does not have an opening. The hollow projection 410 results in the angled surface 412 being more easily elastically deformable than the angled surface 12 when urged by the neck 20.

- 11 - The angled surface 412 is shown in profile to define a straight line. The angled surface 412 may also have an arcuate profile, which may be convex or concave.

The internal surface 30 may have an internal radiussed surface 424 at an end remote from the body of the container 22. The closure 2 and the other features of the container 22 are as described in the first embodiment.

The internal radiussed surface 424 may have a profile curved with a constant radius, or the surface 424 may take any arcuate form. The internal radiussed surface 424 may take the form of a chamfer, having a profile of a straight line. The internal radiussed surface 424 may be an edge. The angled surface 412 may have an arcuate profile or straight- line profile complementary to radiussed surface 224.

The closure 2 may optionally be provided with a stop 407, the stop 407 being an annular projection on the top 4 and adjacent the side wall 6. The stop 407 is positioned to be engageable with the end of the neck 20 remote from the body of the container 22, when the closure 2 is attached to the neck 20. The stop 407 has a height chosen to allow some elastic deformation of the angled surface 412, but limits movement of the neck 20 to prevent excess deformation of the annular projection 410.

Figure 5 shows a further embodiment of the neck of the container. Neck 520 is provided with an annular cavity 505 extending around the neck. The cavity 505 opens onto the end of the neck 20 remote from the body of the container 22, but may alternatively open onto the internal surface 530 or - 12 - external surface of the neck. Internal edge 524 of the neck 520 is able to engage with angled surface 512 on the closure 2. When the internal edge 524 is urged onto the angled surface 512, the part of the neck supporting the internal edge 524 can elastically deform inwardly, into the cavity 505. This embodiment thus allows a relatively large elastic deformation of the neck in order to create a good seal for closing the opening.

The angled surface 512 and projection 510 may be any of the surfaces or projections described in any of the embodiments. The internal edge 524 may be a radiussed edge, or chamfered or arcuate, as described in any of the embodiments.

The closure 2 for use with neck 520 may be provided with a stop as described in the embodiment of Figure 4, in order to limit the deformation of the neck 520.

The neck may optionally be provided with a second cavity (not shown) adjacent an external edge of the neck.

The second cavity may allow greater elastic deformation of the neck with a second angled surface in the embodiment of Figures 3a or 3b. Third and/or further cavities may be provided for the same purpose.

Figure 6 shows a further embodiment of the closure 2.

Neck 620 is the same as that described in Figure 5, having a cavity 605. Edges 611 are formed at the end of the annular cavity 605 remote from the container.

- 13 - Closure 2 is provided with a projection 610, having two angled sealing surfaces 612. One angled surface 612 faces radially outwardly, and one angled surface 612 faces radially inwardly. Each angled surface is inclined at an angle of approximately 10 to 80 degrees to the central axis of the closure.

The projection 612 may be hollow, comprising a cavity to allow it to readily elastically deform. Alternatively, the projection 612 may be solid.

The angled surfaces 612 are located to each engage with an edge 611 of the neck 620. The apex of the projection 610 thus extends into the cavity 605. As the edges 611 are urged against the angled surfaces 612, the edges 611 may be urged radially apart and/or the sealing surfaces 612 may be urged radially together.

The edges 611 may be radiussed, or may have an arcuate profile or be chamfered. The angled surfaces 612 may have a straight-line profile, or have a convex or concave arcuate profile.

Closure 2 may comprise more than one projection 610, each projection comprising two sealing surfaces 612. The neck 620 may comprises a corresponding number of cavities 605 having edges for sealing against surfaces 612. For example, the neck 630 may comprise three cavities 605, extending parallel to each other and circumferentially spaced. The three cavities 605 will form a total of six edges 611. The closure 2 would comprise three projections 610, having a total of six sealing surfaces 612. All the - 14 - sealing surfaces 612 would simultaneously engage against the edges 611 to seal the opening of the container. Furthermore, the or each projection 610 may have one, two or more sealing surfaces 612.

The closure 2 may be integrally formed as a single piece, for example by moulding. Alternatively, the closure 2 may be formed in two or more pieces, for example with the angled surface formed on an insert which is secured to the inside of the top 4.

In use, the closure 2 is screwed onto the neck 20 of the container 22. The closure 2 is attached to the neck 20 be means of threads and grooves 8, 34. One or more edge(s) or radiussed surface(s) of the neck engages against one or more angled surface(s) provided in the inside of the closure. The end of the neck does not directly engage against the top 4 of the closure. The closure then seals the opening 28. If a second angled surface is provided on the top 4, then the second angled surface simultaneously engages with a second edge or chamfered surface of the neck 20. The angled surface 12, 412 and/or neck 520 may be elastically deformable to improve the seal around the opening 28.

Although the closure has been described in one embodiment as having a single angled surface facing in part radially outwardly, the closure may alternatively have a single angled surface of any one of the embodiments facing radially inwardly. A radiussed surface may be provided in place of edge 26, in combination with an edge 24. Thus, any combination of one or two angled surfaces, of which one or - 15 - both may be hollow, and edges or radiussed surfaces of the neck, may form part of the present invention. Any combination of convex or concave arcuate angled surfaces, or a straight-line profiled angled surfaces, with any radiussed or chamfered surface or edge of the neck may also form part of the present invention. In particular, a closure with an angled surface having a straight-line profile may be used in combination with a neck with a radiussed edge.

Although the closure is described as provided with an annular angled surface, the angled surface may be any shape to f it the neck of the container, for example substantially square, oval or rectangular.

The attachment means may be a hinge pivotally connecting the closure and container, i.e. a flip-top. The attachment means may also comprise a projection extending radially inwardly from the side wall of the closure engageable with a projection extending outwardly from the neck of the container, i.e. a snap-cap.

Claims

- 16 - CLJIMS: 1. A closure for closing an opening of a container, the

closure comprising: attachment means for attaching, in use, the closure to the container; a sealing surface inclined to a plane perpendicular to a central axis of the closure, and located such that when the closure is attached to the container by the attachment means the sealing surface is engageable with the container.
2. A closure in accordance with claim 1 wherein the sealing surface is provided on a projection extending from the closure.
3. A closure in accordance with claim 1 or claim 2 wherein the sealing surface faces radially outwardly from the central axis of the closure.
4. A closure in accordance with any one of the preceding claims further comprising a second sealing surface, inclined to the central axis of the closure.
5. A closure in accordance with claim 4 wherein the second sealing surface faces radially inwardly towards the central axis of the closure.
6. A closure in accordance with any one of the preceding claims wherein the or each sealing surface is annular.

- 17 -
7. A closure in accordance with any one of the preceding claims wherein the attachment means comprises one or more helical threads or grooves.
8. A closure in accordance with any one of the preceding claims wherein the or each projection comprises a cavity.
9. A closure in accordance with claim 8 wherein the closure comprises a stop, such that in use the stop limits movement of the neck relative to the closure.
10. A closure in accordance with any one of the preceding claims wherein the closure is integrally moulded.
11. A closure in combination with a container; the combination comprising: an attachment means for removeably attaching the closure to the container; the container comprising a neck defining an opening; the closure for closing the opening and comprising a sealing surface; the sealing surface inclined to a plane perpendicular to a central axis of the closure; the sealing surface located such that when the closure is attached to the container by the attachment means, the neck engages the sealing surface.
12. A closure and container in accordance with claim 11 wherein the neck of the container comprises a radiussed surface, the radiussed surface engageable with the sealing surface of the closure.

- 18 -
13. A closure and container in accordance with claim 11 or claim 12, wherein the sealing surface faces radially outwardly from the central axis of the closure.
14. A closure and container in accordance with any one of the preceding claims further comprising a second sealing surface inclined to the central axis of the closure.
15. A closure and container in accordance with claim 14 wherein the second sealing surface faces radially inwardly towards the central axis of the closure.
16. A closure and container in accordance with claims 14 or wherein the neck comprises a radiussed surface for engagement with the second sealing surface.
17. A closure and container in accordance with any one of claims 11 to 16 wherein the or each sealing surface is annular.
18. A closure and container in accordance with any one of claims 11 to 17 wherein the attachment means comprises one or more helical threads and grooves.
19. A closure and container in accordance with any one of claims 11 to 18 wherein the or each projection comprises a cavity.
20. A closure and container in accordance with any one of claims 11 to 19 wherein the neck comprises one or more cavity or cavities.

- 19 -
21. A closure and container in accordance with claim 20, wherein the closure comprises a projection having at least one sealing surface; the or each sealing surface engageable with an edge of a cavity in the neck.
22. A closure and container in accordance with claim 21 wherein the closure comprises a projection having two sealing surfaces.
23. A closure and container in accordance with claim 19 to claim 22 wherein the closure comprises a stop to limit movement of the neck relative to the closure.
24. A closure and container in accordance with any one of claims 11 to 23 wherein the closure is integrally moulded.
25. A closure substantially as herein described with reference to the accompanying drawings.
26. A container in combination with a closure, the combination being substantially as herein described with reference to the accompanying drawings.
27. A closure as claimed in any one of claims 1 to 10, wherein at least a part of the closure is formed from a polymeric material.
28. A closure as claimed in claim 27, wherein the polymeric material is a thermoplastic.

- 20 -
29. A closure as claimed in claim 27 or claim 28, wherein the polymeric material comprises polylactic acid (PL) or a derivative thereof.
30. A closure as claimed in any one of claims 27 to 29, wherein the polymeric material is amorphous or at least partially amorphous.
31. A closure as claimed in claim 30, wherein the degree of crystallinity (volume) in the polymeric material is less than 50 %.
32. A closure as claimed in claim 31, wherein the degree of crystallinity is less than 30 %.
33. A closure as claimed in claim 32, wherein the degree of crystallinity is less than 20 %.
34. A closure as claimed in any one of claims 27 to 33, wherein the closure is integrally formed from the polymeric material.
35. A closure as claimed as claimed in any one of claims 27 to 34, wherein the closure is injection moulded or compression moulded.
36. A closure for closing an opening of a container, wherein at least a part of the closure is formed from a thermoplastic polymeric material comprising polylactic acid (PLA) or a derivative thereof, and wherein the thermoplastic polymeric material is amorphous or at least partially amorphous.

- 21 -
37. A closure as claimed in claim 36, wherein the degree of crystallinity (volume) in the thermoplastic polymeric material is less than 50 %.
38. A closure as claimed in claim 37, wherein the degree of crystallinity is less than 30 %.
39. A closure as claimed in claim 38, wherein the degree of crystallinity is less than 20 %.
40. A closure as claimed in any one of claims 36 to 39, wherein the closure is integrally formed from the thermoplastic polymeric material.
41. A closure as claimed as claimed in any one of claims 36 to 40, wherein the closure is injection moulded or compression moulded.