Active element, method for manufacturing the same and container with active element

Abstract

An active element for trapping and/or releasing a gaseous or liquid substance is provided including a solid body, which is enveloped by an outer boundary surface (S), and contains an active material adapted to trap and/or release a gaseous or liquid substance, wherein the outer boundary surface S has an overall roundish, preferably round shape. The active element is manufactured by injection moulding and can be utilized within a container.

Claims

1. An active element comprising a solid body which is enveloped by an outer boundary surface (S), wherein the solid body comprises an active material adapted to trap and/or release a gaseous or liquid substance; characterized in that, the outer boundary surface (S) has an overall roundish shape; and the active material comprises a polymer blend with at least one active agent that is adapted to trap and/or release a gaseous or liquid substance, and wherein the solid body further comprises a plurality of intersecting walls, wherein the walls are planar or curved, wherein the thickness of any of the walls comprising radial walls is at most 4 mm, and wherein at least two recesses extend from the outer boundary surface towards the solid body; wherein the at least two recesses do not form a part of the solid body; and wherein neighboring recesses are separated by walls.

2. The active element according to claim 1, wherein the active material comprises 5 to 80% by weight of the at least one active agent.

3. The active element according to claim 1, wherein the active agent is selected from the group consisting of a desiccating agent, an oxygen scavenger and a mixture thereof.

4. The active element according to claim 1, wherein a total exchange surface of the active element with a surrounding atmosphere is greater than the outer boundary surface(s).

5. The active element according to claim 1, wherein the walls are integrally formed.

6. The active element according to claim 1, wherein the outer boundary surface (S) has at least one axis of rotational symmetry (R), wherein the shape of which is selected from the group consisting of essentially spherical, ellipsoidal, ovoidal shape and a cylindrical shape with beveled or rounded edges.

7. The active element according to claim 1, wherein the walls are substantially planar radial walls, which extend radially from one of the at least one axis of rotational symmetry (R) towards the outer boundary surface(s) of the active element.

8. The active element according to claim 7, wherein the solid body of the active element further comprises at least one additional wall that is perpendicular to the radial walls.

9. The active element according to claim 1, wherein the peripheral wall that extends from the outer boundary surface (S) of the active element towards the solid body.

10. The active element according to claim 9, wherein the active element on any of the walls, comprising radial walls, additional walls, and peripheral wall, further comprises ribs.

11. The active element of claim 1, wherein the gaseous or liquid substance trapped and/or released is water vapor and/or oxygen.

12. The active element according to claim 1, wherein its outer boundary surface (S) has an overall round shape.

13. The active element according to claim 3, wherein the desiccating agent is selected from the group consisting of a silica gel, a molecular sieve, clay, zeolites and a mixture thereof.

14. The active element according to claim 3, wherein the oxygen scavenger is selected from the group consisting of an iron-based oxygen scavenger, an organic oxygen scavenger, an enzymatic scavenger, an unsaturated polymer, and a mixture thereof.

15. The active element according to claim 4, wherein the total exchange surface of the active element with the surrounding atmosphere is at least 1.5 times greater than the outer boundary surface.

16. The active element of claim 1, wherein the thickness of the walls is from 0.5 mm to 3 mm.

17. The active element of claim 1, wherein the thickness of the walls is from 0.7 mm to 2 mm.

18. A container for stored products comprising a container body having an interior space; a cap adapted to seal the interior space of the container body substantially airtight, wherein the container further comprises: the active element according to claim 1 being contained within the interior space therein.

19. A method of manufacturing the active element according to claim 1 comprising injection molding the solid body of the active element in one piece.

Description

SHORT DESCRIPTION OF THE DRAWINGS

(1) In the following several embodiments of the invention will be described in more detail with reference to the drawings. In the drawings:

(2) FIGS. 1a and 1b are three dimensional views of a preferred embodiment according to the present invention showing a spherical active element;

(3) FIG. 2 is schematic representation of the silhouette of the active element according to the preferred embodiment;

(4) FIG. 3 is a cross-section view of the active element according to the preferred embodiment taken along the axis of rotational symmetry;

(5) FIG. 4 is a top view of the active element according to the preferred embodiment;

(6) FIGS. 5a and 5b are three dimensional view of a second preferred embodiment of the present invention showing an ellipsoidal active element; and

(7) FIGS. 6a and 6b are three dimensional view of a third preferred embodiment of the present invention showing a cylindrical active element.

(8) FIG. 7 is a container enclosing the active element of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) In the following, preferred embodiments of the invention are shown with respect to the figures.

(10) FIGS. 1a and 1b show an active element 20 according to a first preferred embodiment. The active element 20 consists of a solid body 1 that is enveloped by an outer boundary surface S. The silhouette of this outer boundary surface S is shown in FIG. 2. As can be inferred from FIG. 2, the term outer boundary surface relates to a contour which envelopes the active element 20 irrespective of recesses 3 or the arrangement of walls 4, 5, 6, 9 that serve to increase the active surface of the active element 20.

(11) In the case of the active element 20 according to the first embodiment, the solid body 1 has a plurality of walls 4, 5, 6, 9 that separate neighbouring recesses 3. The recesses 3 do not form part of the solid body 1.

(12) In the first embodiment, the outer boundary surface S is substantially spherical. It envelopes eight radial walls 4 that are planar and extend radially from one axis of rotational symmetry R towards the outer boundary surface of the active element. The radial walls 4 are spaced in regular angular intervals along the axis of rotational symmetry R, from which the radial walls 4 extend. Further, the active element comprises an additional wall 5 that is perpendicular to the radial walls 4 (FIG. 3).

(13) To further increase the stiffness and the active surface of the active element 20, the solid body 1 of the active element 20 further has a peripheral wall 6 that extends from the outer boundary surface S of the active element 20 towards the solid body 1. More specifically, the peripheral wall 6 uniformly extends along the circumferential direction with respect to the axis of rotational symmetry R. Hence, the peripheral wall is essentially curved. The lateral extension of the peripheral wall 6 with respect to the axis of rotational symmetry R can vary. In the present preferred embodiment the extension of the peripheral wall 6 amounts to 33% of the length of the axis of rotational symmetry. Further, the additional wall that was defined to be perpendicular to the radial walls 4 is concentric with the centre of mass of the peripheral wall 6. In other words, the additional wall lies in the plane of symmetry of the peripheral wall 6 and is perpendicular to the axis of rotary symmetry.

(14) In this embodiment, the active element further comprises a concentric wall 9. As can be seen from FIG. 3, the axis of rotational symmetry of the concentric wall 9 is concentric with the axis of symmetry R of the active element 20 and with the axis of rotational symmetry of the peripheral wall 6. When viewed from the direction of the axis of symmetry R, the concentric wall 9 has an overall smaller diameter than the peripheral wall 6. In the present embodiment the concentric wall extends from one side of the additional wall 5. However, the concentric wall can also extend from both sides of the additional wall.

(15) Altogether the walls 4, 5, 6, 9 of the solid body 1 of the active element 20 according to the first preferred embodiment are made up of the radial walls 4, the additional walls 5, the peripheral wall 6, and the concentric wall 9.

(16) The thickness of the walls 4, 5, 6, 9 preferably is at most 4 mm and more preferably 0.5 mm to 3 mm and most preferably 0.7 mm to 2 mm.

(17) In a more particular example, the wall thickness of the active element is as follows: the thickness of radial walls 4 varies from 2.3 mm at parting line to 1.7 mm at the edge (draft angle included); the thickness of peripheral wall 6 varies between 2.1 mm at the intersection with wall 5 and 0.8 mm at upper and lower edges; and the thickness of additional wall 5 is 1.6 mm.

(18) As shown in FIG. 4, the peripheral wall 6 further has ribs 7 that are elongated and have a maximal length that corresponds to the lateral extension of the peripheral wall. The cross-sectional surface of these ribs 7 in this first embodiment is a half circle.

(19) All these structural features, the radial walls 4, the additional wall 5, the peripheral wall 6, the concentric wall 9, and the ribs 7 serve to increase the active surface of the active element 20 without increasing its bulk. Thereby, the active surface is defined as the entirety of exchange surfaces at which the active material is exposed to the surrounding atmosphere. Due to the existence of multiple walls 4, 5, 6, 9 and ribs 7 the effective active surface is significantly larger than the outer boundary surface S. In the case of the spherical active element shown in FIG. 1, the active surface amounts to approximately 3200 mm.sup.2 (with ribs), whereas the outer boundary surface S is approximately 1500 mm.sup.2 (for a sphere with a diameter of approximately 22 mm).

(20) The geometry of the active element 20 and specifically the arrangement of the walls 4, 5, 6, 9 enables that the active element is formed in one piece.

(21) The active material, the walls 4, 5, 6, 9 of the active element 20 consist of, comprises a polymer blend with at least one active agent that is adapted to trap and/or release a gaseous or liquid substances, especially water vapour or oxygen. Thereby the active material preferably comprises 5 to 80% by weight of active agent, more preferably 20 to 75%, and most preferably 50 to 70% by weight of active agent. Concerning the polymer blend that forms the basis of the active material, one can in principle choose from a wide variety of polymers. Examples are polyolefin based polymers, in particular polyethylene, polypropylene, or polystyrene or a biodegradable polymer, in particular a cellulose-based polymer or a polylactic acid or an elastomer in particular thermoplastic elastomers. Similarly, the active agent can be any of: a desiccant agent, an oxygen scavenger, active carbon, sent releasing agent or mixtures thereof. As regards the desiccant agent, silica gels or molecular sieve, clay, zeolites or a mixture thereof have proven effective. The oxygen scavenger can be an iron based oxygen scavenger an organic oxygen scavenger, an enzymatic scavenger, an unsaturated polymer, or a mixture thereof.

(22) Of course, the active element 20 described in the first embodiment is not limited to a spherical outer boundary surface S. As shown in FIGS. 5a and 5b according to another preferred embodiment, the active element 20 can also be of ellipsoidal shape. In this preferred embodiment, the solid body 1 of the active element 20 also comprises multiple walls that can be further subdivided into eight radial walls 4, one additional wall 5, perpendicular to the radial walls, and one peripheral wall 6 extending along the circumferential direction around the axis of rotational symmetry R. Although the ribs 7 have been omitted in this embodiment, they may as well be included on any of the walls.

(23) Even without the ribs, however, the ellipsoidal active element 20 according to the second preferred embodiment has an active surface of about 4300 mm.sup.2 at an outer boundary surface S of about 1800 mm.sup.2. The short axis of the ellipsoid is approximately 36 millimetres long and the long axis is approximately 66 millimetres long. The thickness of the wall again is approximately one millimetre.

(24) In yet a third preferred embodiment, the active element can also have an overall cylindrical shape into which the walls 4, 5, 6, 9 are inscribed. Again, the solid body 1 of the active element 20 altogether has eight radial walls 4 that extend from the axis of rotational symmetry R towards the outer boundary surface. It further has a perpendicular wall 5 and a peripheral wall 6. Together the radial walls 4, the additional wall 5 and the peripheral wall 6 constitute the walls of the solid body 1 of the active element 20. To facilitate an easier insertion of the active element into a container, the edges of the radial walls 4 are rounded edges 8. The cylindrical active element shown in FIGS. 6a and 6b has an active surface of approximately 5800 mm.sup.2 with an outer boundary surface of about 2400 mm.sup.2 (the diameter of the cylinder is 23 mm; the axis length is 28 mm).

(25) Apart from the shape of the outer boundary surface S and the ribs 7 that have been omitted in the second and third preferred embodiment, the active elements 20 shown in the second and third preferred embodiment correspond to the active element 20 of the first preferred embodiment. In particular, they also consist of an active material which may have a composition as described above.

(26) Further, all active elements 20 described so far have in common that they are ideally suited to be manufactured in one piece. Specifically, they are optimally adapted to be injection moulded, in particular by using an Injection Moulding Compounder (IMC). For example, the ribs 7 provide additional contact points when the injection moulded active element 20 is to be released from a mould. Further, the axis of rotational symmetry R can be used as injection channel for the manufacture of the active element. Accordingly, a preferred way of manufacturing the active elements 20 according to the present invention is an injection moulding technique where the active material is injected into a mould to form the active element. Furthermore, the internal side of the peripheral wall 6 is preferably parallel to the axis of rotational symmetry R or slightly inclined so as to facilitate the de-moulding of this active element 20

(27) (even in a roundish shape). The same preferably applies for the internal and external sides of the concentric wall 9 (as shown in FIG. 3) and for the external side of the core constituted by the intersections of the radial walls 4.

(28) In general, the blending of the active agents into a polymer to form the active material can be operated with the moulding of the active element by using a single equipment. Hence, the active element is obtained from a single process step.

(29) Accordingly, the active elements 20 of the present invention can readily be formed by an injection moulding technique that enables a simple and cheap manufacturing. At the same time, since the active elements 20 are formed in one piece, the risk of undesired opening and leakage of the active agent is prevented.

(30) Another advantage of the active element is that for an equivalent weight of active agent, the active element shows a smaller bulk than usual canisters that contain a certain headspace within.

(31) A further advantage of the active element is that the weight of active agent it contains is more reproducible than the weight of active agent inserted in usual canisters as differences can be observed a canister to another, for example due to losses or defaults during filling.

(32) Following the above, a container 40 for stored products comprises a container body 10 having an interior space 12 and a cap 11 that is adapted to seal the interior space 12 of the container body 10 in an airtight way. The active elements 20 according to the present invention can now be provided in either the cap 11 or the interior space of the container body 10. See FIG. 7.