US-20260126021-A1 - FILTER MEDIUM AND METHOD OF PRODUCTION THEREOF

Abstract

The present invention relates to a filter medium comprising an antimicrobial compound, a method for producing the filter medium, the filter element, a filter system as well as the use of the filter medium for the filtration of water in the combustion chamber of an internal combustion engine.

Inventors

• Peter Koppi
• Fabian NUTZ
• Wolfgang Zupanc
• Birgit Renz

Assignees

• NEENAH GESSNER GMBH

Dates

Publication Date

20260507

Application Date

20231005

Priority Date

20221006

Claims (20)

1. 1 . A filter medium comprising: i) a first meltblown layer, and ii) a second spunbond layer, wherein at least one of the first and second layers comprises at least an antimicrobial compound.
2. 2 . The filter medium according to claim 1 , wherein the at least one antimicrobial compound is selected from the group consisting of metals, metal salts of pyrithione, quaternary ammonium salts, polyelectrolytes, polymeric biguanide derivatives or mixture thereof.
3. 3 . The filter medium according to claim 1 , wherein only the meltblown layer comprises the at least one antimicrobial compound.
4. 4 . The filter medium according to claim 1 further comprising a third spunbond layer.
5. 5 . The filter medium according to claim 1 , wherein the meltblown layer comprises polybutylene terephthalate (PBT) fibers.
6. 6 . The filter medium according to claim 1 , wherein the at least one antimicrobial compound is selected from the group consisting of quaternary ammonium salts and polymeric biguanide derivatives.
7. 7 . The filter medium according to claim 1 , wherein the amount of the at least one antimicrobial compound is about 0.0001 to about 2.0 wt % based on the total weight of the filter medium.
8. 8 . The filter medium according to claim 1 , wherein the meltblown layer comprises fibers having an average fiber diameter of about 0.5 μm to about 5.0 μm.
9. 9 . The filter medium according to claim 1 , wherein the spunbond layer comprises polybutylene terephthalate (PBT) or polyethylene terephthalate (PET).
10. 10 . The filter medium according to claim 4 , wherein the meltblown layer includes a first side and a second side opposite the first side, wherein the second spunbond layer is adjacent the first side and the third spunbond layer is adjacent the second side.
11. 11 . The filter medium according to claim 3 , wherein the antimicrobial compound is coated onto a surface of the first meltblown layer.
12. 12 . A liquid filter comprising: a first endplate; a second endplate; and a filter medium disposed between the first and second endplates, the filter medium comprising an antimicrobial compound.
13. 13 . The filter of claim 12 , wherein the filter medium comprises a first meltblown layer and a second spunbond layer in contact with the first melblown layer.
14. 14 . The filter of claim 12 , further comprising an inflow opening and an outflow opening positioned such that a liquid flows radially through the filter medium.
15. 15 . The filter medium of claim 12 wherein the antimicrobial compound is selected from the group consisting of metals, metal salts of pyrithione, quaternary ammonium salts, polyelectrolytes, polymeric biguanide derivatives or mixture thereof.
16. 16 . The filter of claim 13 , wherein only the meltblown layer comprises the at least one antimicrobial compound.
17. 17 . The filter of claim 13 , wherein the meltblown layer comprises polybutylene terephthalate (PBT) fibers.
18. 18 . The filter of claim 12 , wherein the antimicrobial compound is selected from the group consisting of quaternary ammonium salts and polymeric biguanide derivatives.
19. 19 . The filter of claim 12 wherein the antimicrobial compound is present in the filter medium in an amount of about 0.0001 to about 2.0 wt % based on the total weight of the filter medium.
20. 20 . The filter of claim 13 , wherein the meltblown layer comprises fibers having an average fiber diameter of about 0.5 μm to about 5.0 μm.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a national stage application, filed under 35 U.S.C. § 371, of International Patent Application No. PCT/EP2023/077648 filed on Oct. 5, 2023, which claims priority to German Patent Application No. 202022105638.2, filed Oct. 6, 2022, the entire disclosure of which are incorporated herein by reference for all purposes. TECHNICAL FIELD OF THE INVENTION The present invention relates to a filter medium comprising an antimicrobial compound, a method for producing the filter medium, the filter element, a filter system as well as the use of the filter medium for the filtration of water in the combustion chamber of an internal combustion engine. PRIOR ART In the development of new engine generations, an increasing focus is currently being placed on the reduction of the emission of polluting exhaust gases such as nitrogen oxides (NOx). One possible technical solution for reducing NOx in the exhaust gas is the injection of water into the gas/air mixture in the combustion chamber of the engine. The injection of water into the combustion chamber leads indeed to a reduction of the exhaust gas temperatures as well as to a reduction of premature ignition. However, the use of water also shows some problems related to the presence of impurities in water. Said impurities can cause damages to the components located in the cylinder and, in addition, can favour the growth of microbial species such as bacteria, algae, fungi or other microorganisms. In patent application DE 10 2017 006 462 A1 (DE '462 in the following) it has been proposed a filter medium comprising a grid as a supporting layer and a meltblown layer as a filtration layer, wherein both the grid and the meltblown layers are impregnated or coated with an antibacterial material. However, this medium shows some disadvantages. First, the presence of the grid leads to increased costs of the medium. Further, the meltblown layer is required to have a high weight and thickness and this not only results in higher costs but also in a reduced number of pleats in the filter. As it is known, the number of pleats have an effect on the filtration surface, which in turn influences the service life, the dust holding capacity and the differential pressure. Accordingly, there remains a need for a filter medium showing excellent performance in terms of efficiency, dust holding capacity, strength, service life and antimicrobial activity that can be used for the filtration of the water to be injected in the combustion chamber. Further, there remains a need for a filter medium for the filtration of water in the combustion chamber of an internal combustion engine which is cheaper than the filter medium available to date. DESCRIPTION OF THE INVENTION It is an object of the present invention to provide a filter medium showing excellent performances in terms of efficiency, dust holding capacity, strength, differential pressure and service life as well as antimicrobial activity. It is a further object of the present invention to provide a filter medium for the filtration of water in the combustion chamber of an internal combustion engine, which is cheaper than the filter medium available to date. The filter medium of the present invention is particularly suitable for the filtration of water in the combustion chamber of an internal combustion engine. The filter medium according to the present invention comprises: i) a first meltblown layer, andii) a second spunbond layer, wherein at least one of the first and second layers comprises at least an antimicrobial compound. The first meltblown layer can be produced according to known manufacturing methods. Suitable polymers to be used for the first meltblown layer are for example polyolefin (such as polypropylene), polyester (such as polyethylene terephthalate and polybutylene terephthalate) and polyamide. Preferably, the meltblown layer comprises polybutylene terephthalate (PBT). Additives such as crystallization promoters and dyes can also be mixed into the polymers. The average fiber diameter of the first meltblown layer is 0.5-10 μm, preferably 0.5-5 μm and even more preferably 0.5-2 μm. Particularly preferable are fibers having an average fiber diameter of 0.8-1.4 μm. The first meltblown layer has a basis weight of 30-95 g/m2, preferably 40-90 g/m2 and even more preferably 45-80 g/m2. The thickness of the first meltblown layer is 0.05-0.80 mm, preferably 0.1-0.6 mm and even more preferably 0.2-0.5 mm (acc. to DIN EN ISO534:2012; 0.1 bar pressure). Additional meltbown layers can also be present in the filter medium. These may be the same as the first meltblown layer or may have different features in terms of polymer composition, thickness, fiber diameter and basis weight. The second spunbond layer can be produced according to known manufacturing methods. Suitable polymers are, for example, polyolefin (such as polypropylene), polyester (such as polyethylene terephthalate and polybutylene t