MULTILAYER FILTER

Abstract

A multilayer filter of a sterilization container or a sterile packaging includes a core layer made of an aramid fabric, which is covered by or is fully enclosed by at least one outer layer made of at least one other material, preferably PTFE.

Claims

1. A multilayer material for a medical sterilization container or for sterile packaging, the multilayer material comprising a core layer made of an aramid fabric as puncture protection, which is fully enclosed by at least one first outer layer made of filter material on one side thereof and by at least one second outer layer made of filter material on another side thereof.

2. The multilayer material according to claim 1, wherein the core layer, the at least one first outer layer and the at least one second outer layer have fluid exchange openings or pores which allow an exchange of fluids between an exterior and an interior of the medical sterilization container or sterile packaging.

3. The multilayer material according to claim 2, wherein the at least one first outer layer and/or the at least one second outer layer comprises cellulose or plastic.

4. The multilayer material according to claim 3, wherein the at least one first outer layer and the at least one second outer layer either: have a larger surface diameter than the core layer and are bonded together at their outer edge surrounding the core layer; are directly bonded to the core layer.

5. The multilayer material according to claim 4, wherein the aramid fabric comprises fibers each having a diameter, and the fluid exchange openings or pores of the at least one first outer layer and/or the at least one second outer layer are smaller than the diameter of fibers of the aramid fabric.

6. The multilayer material according to claim 3, wherein the core layer is coated with a coating material that comprises cellulose, polymer, polypropylene and/or PTFE.

7. The multilayer material according to claim 3, wherein the fluid exchange openings or pores of the core layer have larger diameters than the fluid exchange openings or pores of the at least one first outer layer and of the at least one second outer layer.

8. A method for producing a multilayer filter of a medical sterilization container or for producing a medical sterile packaging, comprising the following method steps: providing a core layer made of aramid fabric as puncture protection, the core layer comprising an inner side and an outer side, covering the core layer on the inner side with at least one first outer layer made of filter material, and covering the core layer on the outer side with at least one second outer layer made of filter material, so that the core layer is fully enclosed.

9. The method according to claim 8, wherein, the at least one first outer layer and the at least one second outer layer are formed from two separate filter discs or membranes, which are directly bonded together at their respective outer edge so as to enclose the core layer.

10. The method according to claim 8, wherein the core layer is coated with the at least one first outer layer and the at least one second outer layer.

11. A medical sterilization container comprising a multilayer material according to claim 1.

12. A medical sterile packaging comprising a multilayer material according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0028] The present invention will be explained in more detail below on the basis of preferred embodiments with reference to the accompanying Figures.

[0029] FIG. 1 shows a medical sterilization container.

[0030] FIG. 2 shows a filter holding device for a medical sterilization container.

[0031] FIG. 3 shows the process of manufacturing a first embodiment of a multilayer filter.

[0032] FIG. 4 shows the structure of the first embodiment of a multilayer filter in a cross-sectional view.

[0033] FIG. 5 shows the structure of a second embodiment of a multilayer filter in a cross-sectional view.

[0034] FIG. 6 shows the process of manufacturing a third embodiment of a multilayer filter.

[0035] FIG. 7 shows the structure of a third embodiment of a multilayer filter in a cross-sectional view.

DETAILED DESCRIPTION

[0036] FIG. 1 illustrates a multilayer filter 1 in a holding device 2 of a medical sterilization container 3. The filter 1 is designed as an approximately circular disc and is enclosed in the frame-like holding device 2, preferably clamped therein, which in turn is attached to the medical sterilization container 3.

[0037] FIG. 2 illustrates the structure of the filter holding device 2 for the multilayer filter 1 in a medical sterilization container 3. The filter holding device 3 consists of a truss-shaped holding ring 4 and a holding plate 5 in the manner of a grating or perforated plate, which hold/clamp the multilayer filter 1 between them. As a result, openings have been created in the filter holding device 3, both in the holding ring 4 and in the holding plate 5, which allow a fluid exchange between the interior of the sterilization container 3 and its surroundings and simultaneously protect the multilayer filter 1 from intense/large-area force influences.

[0038] FIG. 3 shows the manufacturing process and the constructional assembly of the multilayer filter 1 according to a first embodiment of the present invention. Accordingly, all elements of the multilayer filter 1 (composite material/composite membrane) are stacked one on top of the other, so that they are all arranged centrally along an imaginary axis (in the membrane thickness direction). The term elements are to be understood as the individual layers or filter discs of the multilayer filter 1.

[0039] The multilayer filter 1 has a lowermost/outermost first layer/sheet 6 made of a filter material preferably from the group consisting of cellulose or plastic, preferably made of polypropylene (e.g. polypropylene sold by Kimberly-Clark under the trademark KIMGUARD), polyethylene (e.g. polyethylene sold by DuPont under the registered trademark TYVEC) or PTFE (e.g. PTFE sold by DuPont under the registered trademark TEFLON). The at least one middle, second layer/sheet, namely the core layer 7, consists of an aramid fabric. The uppermost/outermost third layer 8 is again made of a material from the group including cellulose or plastic, preferably of polypropylene (e.g. polypropylene sold by Kimberly-Clark under the trademark KIMGUARD), polyethylene (e.g. polyethylene sold by DuPont under the registered trademark TYVEC) or PTFE (e.g. PTFE sold by DuPont under the registered trademark TEFLON). This preferred sandwich-like structure is exemplary and may also have several other layers/sheets of aramid as well as several layers/sheets of the above-mentioned filter materials or materials with similar (filter) properties. All layers/sheets have fluid exchange openings (pores) 9, with the first and third layer/sheet 6, 8 having fluid exchange opening diameters (pore size) which are smaller than the fiber diameter of the aramid fabric of the second layer 7.

[0040] In the manufacturing process for the first embodiment of the multilayer filter 1, the individual layers/sheets are bonded by means of an adhesive or by ultrasonic welding near the outer circumference of the two outer layers/sheets 6, 8 and thus (loosely) enclose the second layer 7, namely the aramid fabric between them.

[0041] The two outer layers/sheets made of a suitable filter material thus form the actual filter membrane with corresponding filter properties, whereas the middle layer/sheet made of the aramid fabric (exclusively) represents a puncture protection. If the filter 1 is damaged on one flat side by the action of a mechanical force and thus the filter property of the one outer layer/sheet is destroyed/impaired, the intermediate layer of aramid fabric leaves the other outer layer/sheet undamaged and thus its filter effect intact.

[0042] FIG. 4 shows the cross-section of the first embodiment of the multilayer filter 1 according to the first embodiment. In this embodiment, all fluid exchange openings or pores 9 of the layers have the same fluid exchange opening diameter/pore diameter. The intermediate layer of aramid fabric, i.e. the second layer 7, is embedded between the two other, outer layers/sheets 6 and 8 and fully enclosed. The peripheral edge-side contact/connection areas 10 of the two outer layers/sheets are bonded together, but can also be braided, caulked, riveted or similar due to production. In this embodiment, only the two outer layers/sheets are firmly connected to each other and the middle layer/sheet is loosely inserted between them. The two outer layers/sheets may also be firmly bonded (glued) to the central filter. Other exemplary embodiments of bonding are also obvious, which include a complete enclosure of the core layer, e.g. welding (preferably ultrasonic welding) or pressing.

[0043] FIG. 5 shows a second embodiment of the multilayer filter 1 in which the two outer layers/sheets have a fluid exchange opening diameter or pore diameter which is smaller than the fluid exchange opening diameter of the core layer 7. The method for its manufacture corresponds to the first preferred exemplary embodiment.

[0044] FIG. 6 shows the process of manufacturing a third embodiment of the multilayer filter 1. Here, the aramid core, i.e. the middle layer, is coated with a coating material 11 from the group consisting of cellulose or plastic, preferably of a polymer, especially polypropylene (e.g. polypropylene sold by Kimberly-Clark under the trademark KIMGUARD), polyethylene (e.g. polyethylene sold by DuPont under the registered trademark TYVEC) or PTFE (e.g. PTFE sold by DuPont under the registered trademark TEFLON). This can be done by plastic and powder coating, wet painting, a spray-sintering method, electrothermal processes and evaporation.

[0045] FIG. 7 shows the cross-section of a third embodiment of the multilayer filter 1 as a whole and in detail. In this embodiment, all outer sides (top and bottom) of the aramid fabric 7 and also all fluid exchange openings/pores 9 (inside the pores) formed by the aramid fabric 7 are coated with a (filter) material 11 of the already known group. The coating not only reaches the layer surfaces or disc surfaces of the aramid fabric 7 but also the inner surfaces of the fluid exchange openings/pores 9. The multilayer filter 1 according to the third preferred exemplary embodiment of the present invention is not formed from three separate layers in this embodiment but from a middle layer 7, namely the aramid fabric, and a coating 11 which fully envelops the aramid fabric and penetrates its pores.

[0046] In summary, the invention relates to a multilayer filter of a (medical) sterile container or a (medical) sterile packaging each consisting of a core layer of an aramid fabric, which is covered or fully enclosed by at least one outer layer of at least one other material, preferably PTFE and most preferably PTFE sold by DuPont under the registered trademark TEFLON, a method for producing the multilayer (medical) filter of a sterile container or for producing the (medical) sterile packaging, and the use of a composite membrane as a multilayer filter of a (medical) sterile container or as a (medical) sterile packaging, the composite membrane consisting of a core layer made of an aramid fabric, which is covered or fully enclosed by at least one outer layer made of at least one other material, preferably PTFE and most preferably PTFE sold by DuPont under the registered trademark TEFLON.