CH717692A1 - cationized filter. - Google Patents

Abstract

A filter for filtering particles with a negatively charged surface, in particular anionic particles with a polar, negatively charged surface, from a fluid, in particular viruses and/or bacteria from the air, comprises a carrier material, preferably a permeable porous carrier material, and a cationic active agent which is covalently bound to the carrier material. When covalently bound to the carrier material, the cationically acting agent has a molecular weight of less than 1000, in particular less than 200.

Description

technical field

The invention relates to a filter for filtering particles with a negatively charged surface, in particular anionic particles with a polar, negatively charged surface, from a fluid, in particular viruses from the air, comprising a porous carrier material and a cationic acting agent, which is covalently bound to the carrier material. The invention further relates to a method for producing such a filter and the use of the filter for filtering particles with a negatively charged surface from a fluid.

State of the art

Filter materials for filtering particles with a negatively charged surface, in particular anionic particles with a polar, negatively charged surface, from a fluid are known to those skilled in the art. Such filter materials include, for example, nonwovens and fabrics made from meltblown polypropylene, polyester, cellulose fibers, etc. The filter materials are used in respiratory protection masks, for example. The particles with a negatively charged surface, in particular the anionic particles, can be present, for example, as viruses or bacteria.

[0003] EP 3 061 864 A1 discloses a method for producing textile materials with antimicrobial agents which can be covalently bonded to the textile material. The antimicrobial agent can include quaternary ammonium organosiloxanes and silver cations. The textile material, in particular cotton, cotton with polyester or polyester, can be used for masks.

[0004] The known cationized filters have the disadvantage that the efficiency of the filter effect is not sufficient to retain anionic particles in particular sufficiently and at the same time to be able to ensure a sufficiently high level of permeability for a fluid.

[0005] SARS-CoV-2 viruses (pathogens of Covid-19) have a diameter of 60 to 140 nm.

[0006] Viruses are transported in aerosols or water droplets. Aerosols have a maximum diameter of 5,000 nm. Water droplets are significantly larger.

The air molecules (N2 and O2) have a diameter of only 0.3 to 0.4 nm.

One task of a protective mask is, for example, to hold back dangerous viruses as completely as possible and to let breathing air through: N95 masks filter more than 94% of particles with a diameter of up to 600 nm. FFP1 masks filter more than 80% of particles with a diameter of up to 600 nm. FFP2 masks filter more than 94% of particles with a diameter of up to 600 nm. FFP3 masks filter more than 99% of particles with a diameter of up to 600 nm. Surgical masks filter particles with a diameter of 2,000 to 10,000 nm.

The mechanism for restraining dangerous viruses in an efficient protective mask can consist in a 1st step in that the aerosol hydration envelope is torn from the virus. For this purpose, the filter material is preferably made hydrophilic. In a second step, the non-enveloped viruses can now be electrostatically bound to their anionic surface with a preferably strong, positive surface charge of the filter passages.

To protect the environment, it can be advantageous if the filter is also reusable (i.e. washable). It can also be advantageous if the filter consists of renewable raw materials and is biodegradable. However, it is clear to the person skilled in the art that these features may not all have to be fulfilled. In particular, the filter can also be designed to be particularly wash-resistant, for example at the expense of biodegradability.

Presentation of the invention

The object of the invention is to create a filter for filtering particles with a negatively charged surface from a fluid, which belongs to the technical field mentioned at the outset, which on the one hand can efficiently filter the particles out of the fluid and on the other hand has a relatively low flow resistance to the fluid offers.

The solution to the problem is defined by the features of claim 1. According to the invention, the cationically active agent has a molecular weight of less than 1000 when it is covalently bound to the carrier material. The molecular weight is preferably less than 200.

In a method of manufacturing a filter, a cationic agent is covalently bound to a permeable porous support material, the cationic agent having a molecular weight of less than 1000, preferably less than 200.

In a particularly preferred embodiment, the molecular weight of the cationic agent is less than 190, in particular less than 170.

When anionic particles are mentioned below, this is to be understood merely as an example of a particle with a negatively charged surface. It is clear to the person skilled in the art that not only anionic particles can be attracted by a positive charge.

The cationic agent used for cationization can have a greater molecular weight before the reaction with the carrier material than after the reaction with the carrier material, since, for example, a condensate can be split off during the reaction, a substituent can be replaced, etc.

The advantage of the covalent bond formed during the reaction is that the cationic agent enters into a particularly stable connection with the carrier material. The filter can thus be cleaned without the bond between the cationic agent and the carrier material being broken. In particular, a washable filter can thus be created which, even after several washing cycles, in particular also with several boiled washing cycles, at a temperature of 95° C., still has the complete or almost complete effect of the cationically acting agent. The covalent bond is preferably formed in such a way that the filter still has at least 65%, preferably at least 95%, of the effect of the cationically acting agent even after 10, preferably after 50, hot washes. In variants, the covalent bond can also be less stable, in particular if the filter is intended as a disposable item, for example.

In order to achieve the best possible efficiency of the filter, maximum cationization of the carrier material must be ensured with the highest possible fluid permeability. This is achieved by the cationically acting agent having a minimum diameter, which is achieved with a molecular weight of less than 1000, in particular less than 200. A particularly small cationic agent is therefore preferably used, which can penetrate even the smallest cavities and pores of the permeable, porous carrier material and can be fixed there to the carrier material via a covalent bond. A particularly large active surface of the filter passages can thus be achieved, which is covered with the cationically acting agent. This in turn has the effect that a particularly high charge density per unit volume is achieved, with the result that anionic particles can be adsorbed from a fluid and electrostatically fixed particularly efficiently. Even in the event of contact with the filter, contamination with the anionic particles can be largely prevented. The filter is therefore particularly suitable for filtering anionic particles, which can pose a risk to the environment and/or people even at low concentrations, in particular for viruses, preferably for Sars-CoV-2 viruses, or bacteria.

The filter preferably comprises more than 100 million molecules of the cationic agent per cubic centimeter of filter material. In variants, the filter can also have fewer molecules of the cationically acting agent per cubic centimeter of filter material. The filter preferably has more than 50 million molecules of the cationic agent per square centimeter of filter surface perpendicular to a flow direction. In variants, the number of molecules of the cationic agent per square centimeter of filter area can also be less than 50 million.

Preferably, a charge density based on the number of molecules of the cationic agent per volume or per unit area flown through and based on the charge of the cationic agent itself is set such that the viruses and/or bacteria are attracted to such an extent that they are eliminated . In the present case, elimination is understood to mean that the viruses and/or bacteria lose their pathological effect. This is of great advantage, as it can significantly minimize the risk of infection.

The advantage of the filter is particularly evident in the case of anionic particles which are relatively small, in particular in the range of 1000 nm (nanometers) or below. Such particles can be efficiently trapped and fixed in the narrow cavities and pores by the cationic agent. Viruses and/or bacteria are a typical class of anionic particles that can be trapped by the filter. Viruses typically have a diameter in the range of 1000 nm or less, Sars-CoV-2 viruses in particular around 60 to 140 nm. For such small anionic particles, it is particularly advantageous if the pores and channels in the carrier material have a small diameter, so that the probability of the viruses getting past the cationically acting agent is as low as possible.

[0022] Bacteria also typically have a length of a few 1000 nm and a diameter of less than 1000 nm. Bacteria are also typically anionic particles and are hydrophilic, so that the present filter can be used for bacteria as well.

In addition to the low molecular weight, a small diameter of the cationic agent is also important, so that it can be positioned within the pores and channels on the carrier material and reacted there. A cationically acting agent preferably has a maximum diameter of less than 30 nm, particularly preferably less than 3 nm. A particularly high surface occupancy can thus be achieved, with which a particularly high density of cations can be achieved. This in turn increases the absorption capacity of the filter, which means that it can have a greater absorption capacity for anionic particles per volume. In an application as a virus filter, this means that the filter does not have to be cleaned or replaced as often.

The person skilled in the art is aware that a cationic agent does not necessarily have a cationic effect in every environment. In the preferred embodiment, the agent with a cationic effect is a substance which has a cationic effect in particular in a pH-neutral environment. In variants, the cationically acting agent can also be designed in such a way that it acts cationically in an acidic or basic pH environment.

In the present case, the term agent is understood to mean a chemical group which is covalently bonded to the carrier material. However, it is clear that several different cationically acting agents can also be covalently bonded to the carrier material. In particular, several of the chemical groups mentioned below can be used together as cationic agents (see below).

The filter preferably comprises a permeable porous carrier material or a carrier material with cavities. The pores or cavities are designed in such a way that a fluid can flow through the filter at least in one direction. The pores or cavities are particularly preferably designed in such a way that the fluid cannot flow through the filter in a straight line, but is deflected in a number of ways. The pores or cavities in the carrier material are particularly preferably formed in the manner of a labyrinth. So the paths for the fluid are twisted and often diverted. If anionic particles such as viruses are now forced through the labyrinth course, they are thrown against the labyrinth walls like in a cyclone separator, whereby an intensive contact between the viruses and the labyrinth walls is achieved. In the case of a hydrophilic carrier material, a hydration shell of the virus is thus efficiently removed through contact with the labyrinth walls, as a result of which the now shellless viruses can be efficiently stopped and fixed by the cationically acting agent. Furthermore, a contact surface between the filter and the fluid, in particular between the anionic particles in the fluid and the cationically acting agent on the carrier material, is thus increased, which in turn can increase a filter effect. In use, however, the filter can still be used as a cross-flow filter, with one side of the filter possibly being able to be fluid-tight. In variants, the pores or cavities can also run in a straight line through the carrier material or run only minor deflections for a fluid flowing through.

The pores or cavities preferably have small cross-sectional areas, so that the fluid can come into the greatest possible contact with the cationic agent, so that the negatively charged particles can be optimally filtered out of the fluid. The pores or cavities preferably have an average diameter in the range of a few micrometers. A mean diameter is preferably less than 50 microns, in particular less than 10 microns, preferably less than 5 microns. It is clear to the person skilled in the art that the average diameter of the pores or cavities can also be greater than 50 micrometers, in particular if, for example, a significant proportion, preferably more than 10%, in particular more than 25%, of the pores or cavities have an average diameter of less than 50 have microns. Finally, the average diameter of the pores or cavities can be greater than 50 micrometers without a significant portion of the pores or cavities having a diameter of less than 50 micrometers.

If the permeable pores or cavities of the carrier material have a particularly small diameter, this has the effect that, in addition to the optimal filtration of small anionic particles such as viruses, these areas cannot be overloaded by larger anionic particles and thus the cationic areas occupy. The filter thus remains active even if larger anionic particles are present in addition to the small anionic particles to be primarily filtered.

Preferably, the cationically acting agent is directly or indirectly connected to the carrier material via precisely one covalent bond. On the one hand, the cationically acting agent can thus be particularly compact, with which, in particular, a particularly high coverage of the inner surface with the cationically acting agent can also be achieved.

The cationically acting agent is preferably bound directly to the carrier material via a covalent bond. In variants, the carrier material can be treated beforehand in such a way that the cationically acting agent enters into a covalent bond indirectly with the carrier material. For this purpose, a surface of the carrier material can be modified, for example chemically or by a plasma, in such a way that the cationically acting agent can be connected to the carrier material in a particularly stable or particularly simple manner via a covalent bond. Depending on the choice of the carrier material and the choice of the cationic agent, a large number of possibilities are known to the person skilled in the art.

In variants, the cationically acting agent can also be connected to the carrier material via more than one covalent bond.

The cationic agent is preferably non-polymerizable. This prevents the small molecules of the cationically acting agent from penetrating into the innermost, narrow areas of the carrier material and being covalently bound to the carrier material there. In the case of cellulose fibers, the molecules of the cationic agent can penetrate into the amorphous areas, which means that the large number of molecules can result in a high charge density in the filter and thus a filter with a particularly high capacity for absorbing anionic particles, in particular viruses. This also ensures that the passages for the fluid, in particular the air passages in the case of a respirator, are not blocked by a polymer. This can reduce a pressure drop across the filter, which in turn makes breathing easier. This in turn leads to the wearing comfort being improved. In the context of a pandemic or epidemic, it is important that as many people as possible wear a respirator to protect each other. The wearing comfort of the respirator is an important criterion for whether a person wears the respirator and, if so, for how long. If it is more comfortable to wear, it can be assumed that a larger percentage of a group of people will wear the respirator mask, which means that a viral pandemic can be contained more efficiently.

Preferably, the carrier material comprises hydrophilic material. In particular, the carrier material can consist entirely of a hydrophilic material. Viruses, which are transmitted, for example, with the breathing air, are typically transmitted in aerosols or water droplets and in particular also include a shell made of water. The hydrophilic material now allows the water envelope around the virus to adsorb, exposing the virus. The virus, which carries a negative charge, can then be captured via the cationically acting agent and fixed to the cationically acting agent. This achieves a particularly efficient filtration of water-coated anionic particles, in particular of viruses in aerosols.

In variants, the hydrophilic material in the carrier material can also be dispensed with.

The carrier material preferably comprises a natural polymer, in particular a polysaccharide such as cotton and/or man-made or synthetic, degradable polymers such as viscose, modal, lyocell or polyvinyl alcohol. The carrier material thus preferably comprises a fibrous substance, in particular a woven fabric. By providing several fabric layers, labyrinth-like passages for the fluid, in particular air passages, can be created, whereby a fluid and in particular the anionic particles to be filtered contained therein come into the greatest possible contact with the cationically acting agent. However, it is clear to the person skilled in the art that fabrics with a lower level of order can also fulfill the same purpose, in particular nonwovens, for example.

The natural polymers, in particular the polysaccharides, which include cotton, have the advantage that they are readily available and inexpensive to produce. A large number of everyday objects such as clothes, covers for seating furniture, paper, filters for respiratory masks, etc. can also be made from cotton. Fabrics made of cotton can be produced in many different variants and for different requirements. Furthermore, man-made and synthetic polymers can also be provided. Biodegradable polymers are preferably used so that the highest possible ecological standard can be achieved. These include viscose, modal, lyocell and polyvinyl alcohol. This enumeration is not to be understood as exhaustive; the person skilled in the art is aware of other suitable polymers.

The use of cellulose material or polyvinyl alcohol has the advantage that they can be wetted very easily with water. Viruses are anionic particles with a polar surface. With this, viruses tend to form a hydration envelope, particularly when they are airborne. A filter for filtering viruses, in particular for example a respirator, is therefore preferably hydrophilic so that the viruses can be attracted to the hydration envelopes.

Due to the good wettability, any hydration shells can now be removed from the anionic particles, in particular from viruses, for example Sars-CoV-2 viruses. This in turn allows a distance between the anionic particles and the cationic agent to be reduced, which ultimately leads to a firm bond between the cationic agent and the anionic particles. In particular when used as a virus filter, the hydration envelope can be removed from a virus and the virus can then be bound to the cationically acting agent under strong electrostatic forces. The person skilled in the art is also aware of other carrier materials which are hydrophilic and can be used in the present application.

The easy wettability of the cellulose material results from the large number of hydroxyl groups, which creates a large number of polar centers. This allows anionic particles, such as viruses, in particular Sars-CoV-2 viruses, to be fixed particularly efficiently by the cationic agent. The large number of hydroxy groups has the further advantage that a covalent bond to a cationically acting agent can be created in a simple manner, especially since the person skilled in the art is aware of many ways of attaching a molecule to an OH group via a functional group tie.

In variants, other support materials can also be used, rigid materials, for example silicates, sintered metals, ceramics, activated carbon, etc. Other suitable support materials are known to those skilled in the art.

The carrier material preferably comprises many OH groups, with the cationic agent forming a covalent bond with the carrier material via the OH groups, with the covalent bond being formed in particular via an oxygen atom of the OH group.

In particular, polysaccharides, for example cotton, contain a large number of OH groups, which means that the inner surface can be covered densely with the cationic agent.

In variants, the carrier material can also have other functional groups, with which a covalent bond can be entered into with the cationic agent, in particular a halide, for example a chloride or a bromide, an epoxide, an amine, a multiple bond, an acid , an ester, a ketone, an aldehyde, a nitrile, a sulfoxide, etc. Finally, the support material can also be provided with the functional group by a chemical reaction or by a plasma treatment.

The carrier material preferably consists of more than 90% by weight %, preferably entirely, from biodegradable and/or renewable raw materials. This means that the filter can be easily disposed of after use without unnecessarily polluting the environment. This can be achieved, for example, by using cotton as the carrier material. The person skilled in the art is also aware of other carrier materials which are renewable and biodegradable.

In variants, the carrier material can also be less than 90% by weight. % consist of biodegradable and renewable raw materials.

The carrier material preferably comprises a fleece or a reusable, in particular washable, fabric made up of yarns. In variants, carrier materials can also be provided which are not made of fibers or yarns, for example a sintered material or a foam. The fabric made up of yarns is preferably roughened, ground and/or fulled. This mechanical processing allows the inner surface of the carrier material to be enlarged, which in turn can improve the filter effect.

[0047] Depending on the fabric used, these treatments can also be dispensed with, in particular if, for example, a yarn spacing is already sufficiently small.

The cationic agent preferably comprises at least one quaternary ammonium group with the substituents R1, R2, R3 and R4, where R1 is in particular an alkyl radical having between 2 and 10 carbon atoms, preferably between 2 and 5 carbon atoms, particularly preferably exactly 3 carbon atoms. The molecular weight or the diameter of the substituent thus remains relatively small. With the quaternary ammonium compounds, a cationic agent is achieved, which is particularly inexpensive. In variants, other compounds known to the person skilled in the art can also be used as a cationically acting agent, for example metal ions, in particular silver ions, etc. Other cationically acting agents from organic chemistry, complex chemistry, etc. are also known to the person skilled in the art.

Preferably R1 is unbranched. In variants, R1 can also be branched.

Preferably, R 1 comprises a reactive group such as a hydroxyl group, a halogen atom, preferably a chlorine atom, or a terminal epoxide. The person skilled in the art is also aware of other reactive groups which can be comprised by R1, in particular an amine, a multiple bond, an acid, an ester, a ketone, an aldehyde, a nitrile, a sulfoxide, etc. The reactive group is preferably chosen such that that this can react with an OH group of the carrier material.

In variants, the OH group can also be on R1, while the reactive group is connected to the carrier material. The reactive group is particularly preferably bonded terminally to R1 covalently. This enables a sterically particularly simple and therefore efficient bond to the carrier material. In variants, the reactive group can also be attached to a secondary or tertiary carbon atom.

Preferably, R 2 , R 3 and R 4 each comprise an alkyl group having between 1 and 5, preferably between 1 and 3, more preferably exactly one carbon atom, i.e. a methyl group. This achieves a particularly strong cationic effect with a low molecular weight. In variants, R2, R3 and R4 can also include other substituents, in particular also alkyl groups with more than 5 carbon atoms.

The cationically acting agent is preferably silicon-free. The cationically acting agent is particularly preferably siloxane-free. More preferably, the filter is silicon-free, in particular siloxane-free. In this way, particular consideration is given to possible problems in sewage treatment plants and landfills, since the combustion of compounds containing silicon can produce silicon dioxide, which can lead to wear and tear on moving parts of the plant. This means that there is no need for complex pre-treatment during disposal. In variants, the filter, in particular the cationically acting agent, can contain silicon.

The cationically acting agent is preferably free of heavy metals, in particular free of silver. The filter is preferably free of heavy metals, in particular free of silver. This creates a particularly environmentally friendly filter. Silver ions pose major problems, especially in wastewater treatment, since silver kills the microorganisms that are supposed to break down the pollution in the water. In variants, the filter may include silver.

The ammonium group preferably comprises a halide ion, in particular a chloride ion, as counterion. The chloride ion has the advantage of being inexpensive. Other counterions known to those skilled in the art can also be provided in variants.

Preferably, the cationic active agent comprises N-3-chloropropyl-dialkyl-polyamine ammonium salt, N-(3-chloro-2-hydroxypropyl)-trimethyl-ammonium salt, or N-2,3-epoxypropyl-trimethyl-ammonium salt. These examples have a low molecular weight with a particularly strong cationic effect. It has been shown that in particular a carrier material based on polysaccharides can be combined with a cationic agent in a particularly efficient but also particularly cost-effective manner. Tests have also shown that this creates a particularly efficient filter which, for example, can fix a virus particularly strongly via the tertiary ammonium compound. Because the molecules of the examples each have a particularly low molecular weight, they can be covalently bonded to the carrier material in a particularly high concentration, in particular via the OH groups of a polysaccharide.

However, it is clear from the above description that other cationically acting agents can also be used. The above examples can also be modified, e.g. via the alkyl length or via the reactive group etc.

As already mentioned, the filter is preferably used in a respirator mask. In such a respirator, the filter is preferably arranged between a hydrophilic or hydrophobic first layer and a hydrophobic second layer such that when the respirator is on, a hydrophilic or hydrophobic inner, first layer on one facing the wearer's face and a hydrophobic outer, second layer positioned on a side remote from the wearer's face. The advantage of the second hydrophobic outer layer, which faces away from the face, is that viruses with their hydration shells do not accumulate on the surface, but either roll off or penetrate the filter. Due to the hydrophilic carrier material of the filter, the hydration envelope is withdrawn from the virus, whereupon the anionic virus is electrostatically attracted to the cationic agent and fixed.

In variants, the outer, second layer can also be hydrophilic.

Preferably the inner first layer is hydrophobic. With the hydrophobic inner, first layer facing the face, improved wearing comfort is achieved, since the hydrophobic coating means that the surface of the respirator mask that is in contact with the face does not become wet, which in turn can prevent skin irritation.

In variants, the inner, first layer can also be hydrophilic.

In further variants, the inner and/or outer layer can be dispensed with.

Preferably, the hydrophobic outer layer and/or hydrophobic inner layer comprises a backing material. In variants, the layer carrier material of the first inner and the second outer layer can also be dispensed with. In this case, the carrier material of the filter can be made hydrophobic directly.

Preferably, the carrier material of the filter, and optionally the inner and / or the outer layer of the respiratory mask comprises a natural polymer, in particular a polysaccharide such as cotton, and / or man-made or synthetic, degradable polymers such as viscose, modal, or lyocell polyvinyl alcohol. Other carrier materials can also be provided in variants (see above).

Preferably, this substrate comprises a hydrophobic overcoat. The hydrophobic overcoat can be applied directly to the substrate or as an additional layer of substrate to the substrate. The overcoat coating preferably comprises a long chain hydrocarbon derivative substance with at least one fatty alcohol derivative, at least one fatty amine derivative and at least one fatty acid derivative.

In variants, the hydrophobic shell coating can also be achieved by another chemical or physical modification, such as with a coating with a polymer. Such methods are known to those skilled in the art. Furthermore, hydrophobing can also be achieved by introducing hydrophobic substances during fiber production. Such methods are known, for example, from AT 512 143 A1 and AT 512 144 A1.

The hydrophobic coating is preferably achieved by a coating with a polymer, with which a hydrophobic outer coating can be achieved. In variants, the hydrophobic outer coating can also be achieved, for example, by acetylation.

In a particularly preferred variant, the hydrophobing is carried out according to European Patent EP 3 115 502 B1. For this purpose, the layer support material preferably comprises cellulose fibers. The overcoat coating preferably comprises a long chain hydrocarbon derivative substance with at least one fatty alcohol derivative, at least one fatty amine derivative and at least one fatty acid derivative.

The filter is preferably used for filtering anionic particles from a fluid, particularly in a pH neutral environment. The filter is preferably used to filter anionic particles, such as viruses, from air or from water. The virus type is irrelevant, the filter can be used for all virus types. In a preferred embodiment, however, the filter is used to intercept Sars and CoV-2 viruses.

In a preferred embodiment, the filter is used as a depth filter, with the anionic particles, in particular the viruses, being fixed within the carrier material of the filter by the cationic agent. For this purpose, the filter is preferably flowed through with the fluid during use.

In variants, however, the filter can also be used as a surface filter. The cationically acting agent does not necessarily have to be covalently bonded to the carrier material exclusively in pores of the carrier material. Alternatively or additionally, this can also be covalently bonded to the carrier material on the surface of the carrier material. Thus, the filter itself or in an application can be designed, for example, in such a way that the fluid flows past the filter only tangentially. Such an application can be desired, for example, in protective clothing that is deliberately not fluid-permeable. An outer shell of the protective clothing can be designed as a carrier material to which a cationic agent is covalently bound. This has the advantage that, for example, viruses that come into contact with the protective clothing are fixed by the cationic agent. This can prevent further contamination by the viruses. The protective clothing can be washed after use to render the virus harmless and remove it. The protective clothing can then be used again.

According to the same principle, for example, seat covers for vehicles, in particular for vehicles for passenger transport, such as buses, trains, airplanes, ships, etc., can also be equipped with the filter material. This can be an advantage, particularly in the area of passenger transport, since the cover does not have to be disinfected immediately after it has been used by one person, since the viruses and/or bacteria are effectively fixed in the filter by the cationically acting agent and thus a following person hardly or cannot be infected by the fixed viruses and/or bacteria. The seat covers can be washed and reused at regular intervals.

In a further variant, the filter can also be used for bed linen, bath towels, washcloths, cleaning cloths, household paper, seat furniture covers for the living area, etc., covers, etc. The filter can also be used to equip handles etc. Other possible uses of the filter are known to those skilled in the art.

In a preferred embodiment, as mentioned above, the filter is used in a breathing air filter, in particular in a breathing mask. The respirator is preferably designed as a mouth-nose respirator, but can also cover more than mouth and nose. The respirator filter can be designed according to the European standard EN 149 as an FFP1 respirator mask up to an FFP3 respirator mask, as an N95 mask, etc. The filter can also be used in a full face mask. Other types of respirator masks are known to those skilled in the art, which can also be equipped with the filter.

[0075] The respirator mask can optionally have an outlet valve for the breathing air. In the preferred embodiment, in which the respirator is used to trap viruses and/or bacteria from the air, it may be undesirable for breathing air to flow to the outside unfiltered, since there is a risk that an already infected person wearing the respirator carries, releases viruses and/or bacteria into the environment. However, if the focus is on self-protection (e.g. in a laboratory or other applications) or if greater physical effort is required of the respirator wearer, an outlet valve can be provided to make breathing easier.

The filter can also be used in other installations for filtering breathing air, for example in a ventilation system of a preferably closed room. The room can, for example, be a building, in particular a residential building, a company or business building, a restaurant, a hotel, an event hall (cinema, indoor swimming pool, gymnasium, club, disco, etc.), a waiting room, an industrial building, etc. The filter can also be designed to filter breathing air in a vehicle, in particular in a motor vehicle such as a car, truck, train, ship (passenger transport, ferry, cruise ship, cargo ship, sailing ship, etc.), airplane, etc.

In a further preferred application, the filter is used in drinking water treatment or in a sewage treatment plant, particularly preferably in a final stage of a sewage treatment plant.

The filter can be used in municipal or private drinking water treatment. For example, the drinking water can be freed from anionic particles, such as viruses and/or bacteria, with the filter. The filter can be used in an existing filter system for drinking water treatment. The filter can also be used in the private sector, for example in connection with a decalcification system, which means that installation work and maintenance work can be reduced. The filter can also be used in water bubblers or similar. Water systems with cooling, carbonators or the like can also be equipped with such a filter. Other possible uses are known to those skilled in the art.

However, the filter can also be used in industry, for example in the food industry, for filtering fluids. This can be used, for example, to free liquid foods from viruses and bacteria.

Embodiments of the present invention are kitchen or baking textiles, particularly a towel, apron or oven mitt, medical garment, particularly scrubs or medical masks, military clothing, airline staff clothing, children's clothing, school uniform, upholstery, tabletop, automotive interiors Architectural material, in particular a tent or an awning, fitness equipment, in particular a fitness mat or boxing gloves, a dog bed or, in general, an animal toy or animal accessories, bandages, diapers.

In general, the filter can be equipped with a pre-filter for filtering particles, with which the filter cannot clog up too quickly. For example, the pre-filter can be replaced regularly. The service life of the filter can thus be increased significantly.

[0082] Further advantageous embodiments and combinations of features of the invention result from the following detailed description and the entirety of the patent claims.

Brief description of the drawings

The drawings used to explain the exemplary embodiment show: FIG. 1a a schematic representation of an oblique view of a breathing mask; FIG. 1b shows a schematic sectional illustration through a protective mask according to FIG. 1a; FIG. 2 shows a schematic representation of an oblique view of a chair combination of an aircraft, equipped with the filter; FIG. Fig. 3 is a schematic representation of a T-shirt fitted with the filter; and FIG. 4 is a schematic sectional view of a water filter equipped with the filter.

In principle, the same parts are provided with the same reference symbols in the figures.

Ways to carry out the invention

FIG. 1a shows a schematic representation of an oblique view of a protective mask 1. From the outside, the protective mask does not differ from conventional protective masks. The respirator mask 1 includes a mask body 1.1 and carrying strap 1.2. In use, the mask body 1.1 is guided over the mouth and nose and fastened behind the ears with the carrying straps 1.2.

1b shows a schematic sectional view through a mask body 1.1 of the breathing mask 1 according to FIG. 1a. Three layers 1.3, 1.4 and 1.5 can be seen here, all of which are made of cotton in the present case. The middle layer forms the actual filter layer 1.4, with which viruses and bacteria can be filtered. The carrier material of the filter layer 1.4 is a fabric made up of yarns that is roughened. In a first embodiment, N-3-chloropropyl-dialkyl-polyamine-ammonium salt is covalently bonded via the OH groups of the cotton by means of a reaction which is sufficiently well-known to those skilled in the art, with elimination of HCl. In a second embodiment, N-(3-chloro-2-hydroxypropyl)-trimethylammonium salt is used. In both cases, the quaternary ammonium compound forms the cationic agent. Since both molecules have a molecular weight of less than 170 when reactively bound to the cotton, the molecules are very small, which means that many of these molecules penetrate into the innermost, particularly amorphous, areas of the cotton and are covalently bound to the cotton there can become. This achieves a particularly efficient respirator, especially for filtering viruses and bacteria.

The introduction of the cationic active agent into the cotton can be accomplished by techniques well known to those skilled in the art. For example, a packing system, an exhaust process, a pad-cold dwell process (KKV process), a pad-dry-cure process (PDC process) can be provided for this purpose. For this purpose, the cotton is treated with the cationic agent in an aqueous, basic solution.

In further variants, the respirator mask can also be equipped with a valve or designed as a full mask, etc. The person skilled in the art is aware of a large number of areas of application for the filter in the field of filtration of breathing air. In particular, the filter can also be used in ventilation systems of rooms or means of transport such as airplanes, vehicles, trains or ships.

FIG. 2 shows a schematic representation of an oblique view of a chair combination 2 of an aircraft, equipped with the filter. The filter is incorporated in the backrest and headrest 2.1, on the seat cushion 2.2 and on the armrests 2.3. This prevents viruses and bacteria from being spread by passengers who use the same chair one after the other. It is clear to the person skilled in the art that similarly seats and armchairs from other means of transport such as buses, trains, ships etc., but also in the area of restaurants, cinemas, concert halls, waiting rooms, offices etc. can be equipped with the filter.

FIG. 3 shows a schematic representation of a T-shirt 3 equipped with the filter. In particular, the T-shirt itself can consist of the carrier material, in particular, for example, cotton, to which the cationic agent has been added. Other items of clothing can also be equipped with the filter or essentially consist of the filter material, in particular underwear etc.

Here, too, it is clear to the person skilled in the art that the filter can be used not only for clothing but also for related objects. For example, a bandage may be equipped with the filter. Furthermore, bath towels, cleaning towels, facial tissues, etc. can be equipped with them or consist of them. The filter can also be incorporated into textiles which comprise different materials.

FIG. 4 shows a schematic sectional view of a water filter 4 equipped with the filter. The water filter 4 comprises a feed line 4.1, a filter 4.2 and a discharge line 4.3, the filter 4.2 being arranged between the feed line 4.1 and the discharge line 4.3. The carrier material of the filter 4.2 can in turn be based on cellulose, but can also include another material, such as a sintered material or the like. The water filter can be intended for municipal water distribution systems. Further, the water filter can be for home use. Finally, the water filter can also be provided for sewage treatment plants.

It is clear to the person skilled in the art that, instead of water, air or other fluids can also be freed from viruses and/or bacteria using the filter.

In summary, it can be stated that, according to the invention, a filter for filtering viruses and/or bacteria from a fluid is created which is particularly efficient.

Claims (21)

1. Filter for filtering particles with a negatively charged surface, in particular anionic particles with a polar, negatively charged surface, from a fluid, in particular viruses and/or bacteria from the air, comprising a carrier material, preferably a permeable porous carrier material, and a cationically acting agent which is covalently bonded to the carrier material, characterized in that the cationically acting agent has a molecular weight which is less than 1000, in particular less than 200, when covalently bonded to the carrier material. 2. Filter according to claim 1, characterized in that the cationically acting agent is directly or indirectly connected to the carrier material via precisely one covalent bond. 3. Filter according to claim 1 or 2, characterized in that the carrier material comprises hydrophilic material. 4. Filter according to any one of claims 1 to 3, characterized in that the carrier material comprises a natural polymer, in particular a polysaccharide such as cotton and/or man-made or synthetic, degradable polymers such as viscose, modal, lyocell or polyvinyl alcohol. 5. Filter according to any one of claims 1 to 4, characterized in that the carrier material comprises one or more OH groups, wherein the cationic agent enters into the covalent bond via the OH group with the carrier material, the covalent bond in particular via a Oxygen atom of the OH group is formed. 6. Filter according to any one of claims 1 to 5, characterized in that the carrier material is more than 90 wt. %, preferably completely, consists of biodegradable and/or renewable raw materials. 7. The filter according to any one of claims 1 to 6, characterized in that the carrier material comprises a fleece or one or more reusable, in particular washable, fabrics made up of yarns, the fabrics in particular having no passages greater than 1000 nm, are preferably greater than 600 nm, which is achieved in particular by roughening, grinding or fulling. 8. Filter according to any one of claims 1 to 7, characterized in that the cationically acting agent comprises at least one quaternary ammonium group with the substituents R1, R2, R3 and R4, where R1 is in particular an alkyl radical with between 2 and 10 carbon atoms, preferably between 2 and 5 carbon atoms, particularly preferably exactly 3 carbon atoms, and where R1 is unbranched and where R1 comprises a reactive group such as a hydroxyl group and a halogen atom, preferably a chlorine atom, or a halogen atom, preferably a chlorine atom, or a terminal epoxide, where the reactive group can react with an OH group of the carrier material, which is preferably terminally covalently bonded to R1. 9. Filter according to claim 8, characterized in that R2, R3 and R4 each comprise an alkyl group with between 1 and 5, preferably between 1 and 3, particularly preferably exactly one carbon atom, i.e. a methyl group. 10. Filter according to any one of claims 1 to 9, characterized in that the cationic agent is silicon-free. 11. Filter according to any one of claims 1 to 10, characterized in that the filter is free of heavy metals, in particular free of silver. 12. Filter according to any one of claims 9 to 11, characterized in that the ammonium group comprises a halide ion, in particular a chloride ion, as counterion. 13. Filter according to claims 9 to 12, characterized in that the cationically acting agent is N-3-chloropropyl-dialkyl-polyamine-ammonium salt, N-(3-chloro-2-hydroxypropyl)-trimethyl-ammonium salt or N-2, 3-epoxypropyl-trimethylammonium salt. 14. A method for producing a filter according to any one of claims 1 to 13, wherein a cationic agent is covalently bound to a porous support material, characterized in that the cationic agent has a molecular weight of less than 1000, in particular less than 200 . 15. Respirator mask comprising a filter according to any one of claims 1 to 14. 16. Respiratory protection mask according to claim 15, characterized in that the filter is arranged between a hydrophilic or hydrophobic first layer and a hydrophobic second layer such that when the respirator is put on, a first hydrophilic or hydrophobic inner layer on one side facing the wearer's face and a second hydrophobic outer layer is disposed on a side remote from the wearer's face. 17. Respiratory protection mask according to claim 16, characterized in that the hydrophobic outer layer and/or hydrophilic or hydrophobic inner layer comprises a carrier material, the carrier material being a natural polymer, in particular a polysaccharide such as cotton, and/or man-made or synthetic, degradable Polymers such as viscose, modal, lyocell or polyvinyl alcohol and wherein the carrier material comprises a hydrophobic coat coating, the coat coating comprising a substance made from a long-chain hydrocarbon derivative with at least one fatty alcohol derivative, at least one fatty amine derivative and at least one fatty acid derivative, or the hydrophobic coat coating is achieved by a polymer will. 18. Respiratory protection mask according to one of claims 16 to 17, characterized in that it is mixed with a fragrance. 19. Use of a filter according to any one of claims 1 to 18, for filtering particles with a negatively charged surface, in particular anionic particles with a polar, negatively charged surface, from a fluid, in particular air or water in a pH-neutral environment. 20. Use of the filter according to claim 19 in an air circulation system, preferably in an air conditioning or air purification system or in a breathing air filter, in particular in a breathing mask. 21. Use of the filter according to claim 19 in drinking water treatment or in a sewage treatment plant, particularly preferably in a final stage of a sewage treatment plant.