The present application relates to a face mask comprising a layer of microfiber material. The microfiber material maybe equipped with one or more antimicrobial agents that are adhered to the material in such a manner that they are substantially not released from the material even if the face mask is washed, so that the face mask can be re-used. Advantageously, the face mask does not comprise antimicrobial agents which impose undesired toxic effects on a user such as metal-based antimicrobial agents, in particular silver-based antimicrobial agents. In preferred embodiments, where one or more antimicrobial agents are adhered to the textile material, the face mask can be used to protect the wearer against airborne particulate and microbial pollution which comes in contact with the textile material. Specifically, the face mask efficiently deactivates human coronavirus 229E (ATCC VR-740) and/or SARS-C0V-2 and/or H1N1 influenza virus. Also, the face mask provides for a high filter efficiency and high breathability (i.e. low pressure drop) at the same time.

Background of the Invention

Particulate filtering face masks are used in various circumstances to protect against a variety of airborne particles and contaminations, such as microbes that are transferred via droplets, aerosols, fine particles and dust. Face masks are regularly used in hospitals and industry environments as well as in crowded places, such as trains. Here, the danger of infections and threats to the respiratory system are high due to microbial contamination. Workers in the health care system as well as treated patients are particularly exposed to infectious contaminations and therefore require high standards of disinfection routines to prevent the spread of pathogens within the health care system as well as population-wide crisis situations, such as the recent H1N1 and Covid- 19 pandemics.

COVID-19 is an infectious disease caused by the SARS-C0V-2 virus that has recently caused a global pandemic. SARS-C0V-2 mainly spreads via airborne droplet infection. COVID-19 has resulted in immense stress on global healthcare systems and produced a shortage of lifesaving medical devices and personal protective equipment used by medical professionals, including face masks. Most commonly used face masks comprise particulate filtering materials that trap particles, such as microorganisms, out of the breathing air. Respiratory face masks produced from particulate filtering materials reduce the risk of infections for the face mask’s wearer; however, they are typically disposable, i.e. non-washable and not reusable. Other face masks are washable and re-usable; however, they are not antimicrobial, i.e. they - at best - filter microbes from air passing through the mask, but they do not kill the filtered microbes. Therefore, such filtered microbes stay infectious within and on such known re-usable face masks.

Moreover, commonly used face masks do not provide for an acceptable comfort for the user, as the breathability of the material of the face masks is limited. Therefore, in particular during physical activity, such as while doing sports, users prefer not wearing face masks.

Therefore, there is an urgent need for face masks that are antimicrobial and provide for excellent breathability, while being wash-durable and, thus, environmentally friendly.

Summary of the Invention

It is an object of the present invention to provide a face mask that overcomes some or all of the above-mentioned problems. Some or all of these objects are solved by the subject matter of the independent claims. Preferred embodiments are subject of the dependent claims.

In the context of the present invention, the terms “textile” and “textile material” relate to a flexible material consisting of fibres, or a network of natural and/or artificial fibres, such as a yarn or a fabric. The material may be in its natural or processed or even finished form.

The term “antimicrobial” as used in the context of the present invention relates to the ability to kill at least some types of microorganisms, or to inhibit the growth or reproduction of at least some types of microorganisms. Said term relates to any compound, agent, product or process that is harmful to one or more “microorganism” as used in the context of the present invention. Preferably, the one or more “microorganisms” get killed by the “antimicrobial” product or process. By “antimicrobial agent” is meant any substance or combination of substances that kills, inactivates or prevents the growth of a microorganism. The terms “microorganism” and “microbe”, which are used interchangeably in the context of the present invention, are defined to comprise any organism too small to be seen by the unaided eye, such as, especially, single-celled organisms or viruses.

The present application relates to a face mask comprising a layer of microfiber material, in particular a fabric. The microfiber material comprises or preferably consist of fibers characterized by having a denier of at most 1.0 denier, more preferably characterized by a denier of at most 0.9 denier, even more preferably by a denier of at most 0.8 denier.

The inventors have found that a microfiber material provides for excellent breathability of the face mask, while the fine fibers of the material allow for an extraordinary high coverage with antimicrobial agents. Also, the microfiber material provides for a high filter efficiency, while the face mask also provides for excellent breathability. The breathability is about 5 times higher compared to face masks prepared from usual cotton fabric.

The microfiber material may comprise or consist of cellulose fiber material. Preferably, the microfiber is made of rayon or modal, preferably modal, wherein the modal is at least partially made from beech wood or bamboo. The modal is preferably from bamboo, more preferably wherein the modal is made entirely from bamboo. Thus, the material is a natural material and resource-saving.

The face mask may comprise one or more layers of microfiber material, preferably microfiber modal material.

In particular, the face mask may have only one layer, the layer being the layer of microfiber material.

The one or more layers are designed to cover the mouth and / or nose of the user when wearing the mask. I.e. while breathing and / speaking, air and/or aerosols pass through all of the one or more layers of the face mask.

The microfiber material may be woven, weft-knitted or warp-knitted fabric. Preferably the microfiber material is a woven fabric.

The microfiber material preferably has a weight of too to 200 gram/m ² , preferably about 145 to 165 g/ m ² .

The face mask may have a breath resistance of at most 30 Pa, preferably at most 20 Pa differential pressure when measured for an inhalation breath resistance at about 90 to 1001/min, preferably about 951/min pressurized air flow; and/or a breath resistance of at most 40 Pa, preferably at most 30 Pa differential pressure when measured for an exhalation breath resistance at about 155 to 1651/min, preferably about 1601/min pressurized air flow.

The microfiber material may be treated with an antimicrobial agent, preferably with two antimicrobial agents. A such, the microfiber material maybe antimicrobial.

In particular, the microfiber material can be treated with antimicrobial agents carrying positive charges, such as polyhexamethylene biguanide (PHMB), a quaternary ammonium organosilane compound, chitosan, or silver, preferably with two or more antimicrobial agents. The silver may be in particular in form of silver cations.

The microfiber material can thus carry more than too billion, such as more than 120 billion, or even up to about 150 billion positive charges per cm ² . By use of the microfiber material, the density of the antimicrobial agents and thus their positive charges can be higher compared to a usual fiber material.

The inventors have found that a microfiber material equipped with a combination of one or more of the above antimicrobial agents, i.e. polyhexamethylene biguanide (PHMB), a quaternary ammonium organosilane compound, chitosan, or silver cations, is highly efficient in deactivating viruses, in particular coronaviruses.

The antimicrobial agents may be bound to the microfiber material directly, or via cross linking. Direct binding is, however, preferred.

Suitable quaternary ammonium organosilane compounds have the formula wherein the radicals have, independently of each other, the following meanings: Ri, R2, and R3 are a Ci-Ci2-alkyl group, in particular a Ci-C6-alkyl group, preferably a methyl group; R4, and R5 are a Ci-Ci8-alkyl group, a Ci-Ci8-hydroxyalkyl group, a C3- C -cycloalkyl group, a phenyl group, or a C -Cio-aralkyl group, in particular a C1-C18- alkyl group, preferably a methyl group; R6 is a Ci-Ci8-alkyl group, in particular a C8- Ci8-alkyl group; X- is the counterion and an anion, for example, chloride, bromide, fluoride, iodide, acetate, or a sulfonate group, preferably X- is chloride or bromide; and n is an integer of 1 to 6, in particular an integer of 1 to 4, preferably 3. The term “alkyl group” as used herein means a branched or unbranched alkyl group.

Quaternary ammonium organosilane compounds are known in the art and commercially available. Such compounds possess specific functional groups which enable their bonding to functional groups of the textile material. Under the reaction conditions disclosed herein, the quaternary ammonium organosilane compounds are bonded to the textile material via a covalent bond between the organosilane moiety and functional groups of the textile. Furthermore, organosilane moieties polymerize with each other, resulting in -O-Si-O- bonds.

The quaternary ammonium organosilane compound can comprise dimethyloctadecyl[3-(trimethoxysilyl)propyl] ammonium chloride or dimethyltetradecyl[3-(trimethoxysilyl)propyl] ammonium chloride, most preferably dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride. Dimethyloctadecyl[3-(trimethoxysilyl)propyl] ammonium chloride is available on the market, e.g. in AEM 5772 (manufactured by Aegis, USA), sold as a 72% by weight solution. Dimethyltetradecyl[3-(trimethoxysilyl)propyl] ammonium chloride is available on the market, e.g. in Sanitized T 99-19 (manufactured by Sanitized AG, Switzerland); N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride is available from Gelest Inc.;Other suitable ammonium silane compounds are described, e.g., in patent applications US 2011/0271873 Al and US 2006/0193816 Al, and in US patent 8,906,115.

Polyhexamethylene biguanide (PHMB) has a structure as shown hereinafter, wherein n indicates the number of monomer units as known in the art.

PHMB is known in the art and commercially available, e.g. in Texguard 20 of Swissol Specialties Pvt. Ltd, India, or Vantocil TM IB of Lonza. Vantocil TM IB has a concentration of 20% PHMB in solution. Furthermore, PHMB is a polymer, typically with 10-40 repeating units and a molecular weight in excess of 700 g/mol. Therefore, it is expected to be non-volatile and has a reported vapour pressure of 4.nxio-7Pa at 25 °C and not able to vaporize for inhalation at any appreciable amounts (see CLH Monograph on PHMB). Because the active agent on the treated textiles is permanently applied, persisting over several washes, and non-volatile, they are not available to be inhaled and interact with respiratory tissues. The non-volatile nature of PHMB and its persistence on the textile provide for biocompatibility required for face masks regulated by, for example, according to US Code of Regulation 21CFR878.4040.

The antimicrobial agent may be or comprise silver cations. In particular embodiments, the silver cations are trapped in an inorganic or organic matrix. Preferably, the inorganic matrix is an aluminosilicate. Preferably, the organic matrix is a polymeric matrix. Such silver-containing microbial agents are known in the art and available on the market.

A silver cation in form of its acrylate salt is shown hereinafter.

Silver acrylate salt

In an exemplary embodiment of the invention, the aluminosilicate is a sodium- poly(sialate-disiloxo) compound.

In an exemplary embodiment of the invention, the polymeric matrix into which silver cations are trapped is an acrylic polymer. Such silver-containing agents are known in the art and available on the market, e.g. SilvaDur AQ Antimicrobial (manufactured by Rohm and Haas) which contains acrylic polymer(s), silver nitrate, nitric acid and water. In another exemplary embodiment of the invention, the silver cations are trapped in a polymeric matrix. Such silver-containing agents are known in the art and available on the market, e.g. SILVADUR™ 930 Antimicrobial (of Dow Chemical Company) which contains polymer(s), silver cations, ammonia, ethanol and water. In another embodiment of the invention, the antimicrobial agent is or may comprise polyglucosamine (chitosan). Chitosan has a structure as shown hereinafter, wherein n indicates the number of monomer units as known in the art:

Chitosan is known in the art and commercially available.

The face mask preferably provides for deactivation of viruses, preferably corona viruses, for example selected from human coronavirus 229E (ATCC VR-740) and/or SARS-C0V-2 (ATCC VR-1986HK) and / or H1N1 Influenza.

Preferably, the antimicrobial microfiber material exhibits a reduction value of human coronavirus 229E (ATCC VR-740) and/or SARS-C0V-2 (ATCC VR-1986HK) and/or H1N1 Influenza of at least 95%, preferably at least 98%, more preferably at least 99%, even more preferably 99.5% most preferably of at least 99.9%, within 240 minutes, preferably within 120 minutes, more preferably within 60 minutes, even more preferably within 30 minutes, most preferably within 10 minutes, when measured according to ISO 18184 at one contact time.

Preferably, the reduction values are obtained after at least 30, preferably at least 50, more preferably at least 70, even further preferably at least 100, most preferably at least 150 laundry washes.

The face mask may have the shape of a pad, with dimensions of 5 to 15 cm (width) and 10 to 25 cm (length). At least two expansion pleats may be integrated in order to balloon over nose and face and to grant both wearing comfort and protection against breathing unfiltered air. A nose clip may be further integrated to better fit the face mask to the nose thus reducing the amount of inhaled or exhaled unfiltered air by-passing the face mask.

Fixing means to attach the face mask to the wearer’s head may be provided by ear loops or straps to be fixated around the head and/ or neck. Those fixing means may be adhered at each edge of the face mask. The face mask may further comprise one or more, preferably two valves. The valves may be plastic one-way valves. Such valves further improve the breathability of the face mask in that they close while breathing in, and open while breathing out.

The face mask can be in particular used as sports face mask, in particular for cardio or strength training. In this case, the fixing means are preferably provided by straps to be fixated around the head. This way, the face mask does not move inadvertently during use, but is fixated around the head.

In a further aspect, the present application relates to the use of the face mask as described above as mouth/nose protector for protecting the user and/or third parties from infection by droplet transmission, wherein the user is preferably doing practicing sports while wearing the face mask, in particular cardio or strength training.

The invention is exemplified in the accompanied figures.

Fig. 1 shows a face mask consisting of one layer of antimicrobial fiber material, to which straps to be fixated around the head are attached. Further, a nose clip is integrated into the seam.

Fig. 2 shows a face mask consisting of one layer of antimicrobial fiber material, to which straps to be fixated around the head are attached. Further, a nose clip is integrated into the seam. In this embodiment, the face mask is furthermore equipped with two valves that provide for a further improved breathability.

Worked example: Breath resistance / Valve test

A face mask consisting of one layer of microfiber material (ioo% bamboo modal) was tested with respect to breath resistance on a PMFT 1000 machine according to test norm EN 149:2009.08.

Aerosol: pressurized air

The results are as follows:

The results indicate that the breathability is about 5 times higher compared to face masks prepared from usual cotton fabric.