Patent Application
20240417888
The invention relates to a fiber material having an antimicrobial effect and comprising fibers of regenerated cellulose and/or regenerated cellulose derivatives and at least one antimicrobial agent component. The invention further relates to a method for producing a fiber material having an antimicrobial effect, to a fiber material produced according to this method and to the use of the fiber material.
Antimicrobial fibers, fiber composites, yarns and textile fabrics are well known. For example, numerous publications such as DE 10 2006 056977 B3, DE 10 2007 019 768 A1 and DE 10 2008 045 290 A1 describe additives consisting of antimicrobial, particulate, liquid or meltable or vaporizable active substances or active substance compounds consisting of metallic nano- or microphases, salts, glasses or modified aluminosilicates or organic biocidal active substances for wet, dry-wet or dry-spun fibers. These additives are added before or during the shaping process or for finishing fibers, yarns or textiles (e.g. EP 0 677 989 B1). A disadvantageous common feature of such functionalized fibers, fiber composites, yarns and fabrics is the insufficient resistance and the resulting deterioration or even lack of effect, which is difficult for the user to control, e.g. due to washing out of the active substances that are decisive for the function.
In addition to the textile, paper and building materials industries, cellulose is also used in the medical sector. The widespread use of cellulose materials, especially for medical applications, has led to the development of antimicrobial cellulose fibers. Most of the work on the production of antimicrobial cellulose to date has dealt with the introduction of biocidal nano-silver particles onto or into the cellulose fibers using various deposition processes (e.g. U.S. Pat. No. 8,367,089 B2 and DE 603 05 172 T2).
Antimicrobial fibers or textiles that contain coatings or active ingredients or agent compounds, such as combinations of silver, copper or zinc ions, which are fixed in or on the fiber matrix, e.g. on ion exchange resins, in glasses or modified aluminosilicates, show better resistance to washing out, but the effectiveness also deteriorates after 10-20 washing cycles, as these technologies are uniformly based on the release of the respective active ingredient (depot effect). Due to this depot effect, higher active ingredient concentrations of significantly more than 1% by weight would be necessary for a longer lasting effect. This is countered by the fact that the above-mentioned antimicrobial active ingredients such as silver, copper, zinc, etc. cannot, or only in very small quantities (<<1%), be introduced into the fiber matrix during the shaping step (solution production and fiber spinning) because of the associated risk of hindering cellulose modification (viscose or carbamate process) or the spontaneous, autocatalytic decomposition of the solvent used (lyocell process), which is reflected in an exothermic DSC curve by a significant reduction in the temperature for the start of decomposition of the preferred N-methylmorpholine-N-oxide (NMMO) (“on-set temperature”) from approx. 160° C. to below 130° C. in some cases. Another disadvantage, particularly in the case of active ingredient concentrations of several percent by weight, as would be required for the consistent effectiveness of conventional active ingredients, is the impairment of fiber properties such as mechanical stability, long service life, dyeability, water absorption/absorbency and processability.
In summary, to date there are no fibers, fiber composites, yarns and textile fabrics that can be produced using standard processes and equipment, that have fiber properties comparable to those of untreated fibers and that have a lasting antimicrobial effect over the entire textile life cycle.
It is the task of the present invention to provide a fiber material having an antimicrobial effect that lasts over the entire life cycle, which can be produced using standard processes and equipment and has properties that are comparable to those of untreated fiber materials.
According to the invention, the problem is solved by a fiber material of the type initially mentioned, wherein the agent component comprises silver (Ag) and ruthenium (Ru), silver and ruthenium being in electrical contact with one another and being embedded in and/or at least partially surrounded by the cellulose and/or cellulose-derivative fibers. The fiber material according to the invention comprises regenerated fibers which not only have antimicrobial properties, but surprisingly also deodorizing and/or odor-neutralizing properties. These properties of the fiber material according to the invention (hereinafter also referred to as “hygiene fibers”) are not based on the release of heavy metal ions or organic biocidal active substances, but surprisingly nevertheless exhibit an antimicrobial effectiveness which clearly exceeds the values required by the relevant standards. In addition, the fiber materials according to the invention also have a deodorizing and/or odor-neutralizing effect, which is not solely attributable to an inhibition or killing of microorganisms, but is also advantageously based on a neutralization (e.g. by degradation or conversion) of organic substances (odorous substances or molecules). The durability of the effectiveness of the hygiene fibers according to the invention is particularly surprising. Both after 50 washes and after 100 washes, no significant deterioration in the effectiveness or reduction in the antimicrobial, deodorizing and/or odor-neutralizing properties can be observed. It is also surprising for the skilled person that the antimicrobial, deodorizing and/or odor-neutralizing properties of the fiber material according to the invention do not depend on the presence or accessibility of the agent component on the surface of the hygiene fibers, but are fully pronounced despite the agent component being introduced into the fiber cross-section of the cellulose and/or cellulose-derivative fibers with complete and wash-resistant inclusion in the fiber matrix. Another particular advantage of the fiber material according to the invention is that it has properties which are comparable to those of untreated fiber materials, e.g. with regard to mechanical stability, durability, dyeability, water absorption/absorbability and processability.
According to the invention, the agent component comprises silver (Ag) and ruthenium (Ru), wherein silver and ruthenium are in electrical contact with each other. Silver and ruthenium may be present at least partially in metallic form, at least partially in the form of their salts and/or at least partially in the form of a metal compound. Silver and ruthenium have different electrochemical potentials and thus form a galvanic cell (i.e., a “microgalvanic element”). If this cell is short-circuited via an aqueous phase, a high electric field strength is created due to the small distance (nm or μm range) between the two contacting metals. This contributes significantly to the killing of germs. Redox reactions take place at both electrodes of the microgalvanic element, each of which leads to the destruction of microorganisms. At the first half-element (cathode), molecular oxygen is reduced to oxygen radicals, which then have a toxic effect on the microorganisms. At the second half-element (anode), electrons are transferred from the microorganisms to the silver semiconductor, thereby destroying them by oxidation. The agent component of silver and ruthenium according to the invention, whose antimicrobial effectiveness is not based on the release of biocides or metal ions but on the catalytically assisted generation of oxygen radicals, does not change its composition even with long-term use and, unlike biocides or oligodynamic metals, does not require a depot or devices that regulate the release of biocides or metal ions. In contrast to biocides and oligodynamic metals, which must release toxic substances into the environment in order to be effective, only water is finally produced from the oxygen radicals formed when the agent component according to the invention is used. Since the metal combination Ag/Ru is a catalytically supported system, its antimicrobial effect is advantageously dependent exclusively on the active surface and not, as in the case of biocides or oligodynamic systems (silver, copper and zinc or their salts or compounds), on their quantity and wash out rate.
The two metals (silver and ruthenium) can, for example, be applied as a layer system on the surface of a particulate carrier (carrier material), whereby the layer of one metal lies at least partially above that of the other metal. The respective upper layer can be porous (in particular nanoporous) or microcracked, in particular cluster-shaped, applied to or deposited on the other metal, so that the aqueous solution or moisture has access to both half-elements and the microgalvanic element is short-circuited. Alternatively or additionally, the two metals (half elements) can, for example, also be applied to the surface of a particulate carrier (carrier material) in the form of individual particles. In principle, these can be, for example, bimetallic particles comprising both metals and/or metal particles comprising only one of the two metals. The latter can be applied sequentially, i.e. first particles of the first metal and then particles of the second metal (or vice versa), or simultaneously as a mixture of particles of both metals on a carrier material in such a way that they are in electrically conductive contact. The particles can be applied to the carrier material in a single layer (lying next to each other) and/or at least partially in multiple layers (lying on top of each other).
In an advantageous embodiment of the invention, it is provided that silver and ruthenium are at least partially embedded in and/or at least partially surrounded by the cellulose and/or cellulose derivative fibers in a homogeneously distributed particulate form. The homogeneous distribution of individual particles within the fibers or in the fiber cross-section ensures a uniform antimicrobial, deodorizing and/or odor-neutralizing effect of the agent component within and on the entire surface of the fibers.
In a further advantageous embodiment of the invention, it is provided that silver and ruthenium are at least partly present in the form of silver/ruthenium bimetallic particles. For example, the silver/ruthenium bimetallic particles may comprise silver particles partially coated with ruthenium. Additionally or alternatively, the silver/ruthenium bimetallic particles may comprise particles made of cellulose and/or cellulose derivatives coated with silver and ruthenium.
In a further advantageous embodiment of the invention, it is provided that the silver and/or the ruthenium is/are at least partially present in the form of a metal compound, wherein the metal compound comprises at least one metal oxide, metal oxyhydrate, metal hydroxide, metal oxyhydroxide, metal halide and/or at least one metal sulfide. The present invention thus advantageously also comprises, for example, an agent component comprising a semiconducting, catalytically active ruthenium compound (half-element I of a galvanic element) and a semiconducting, sparingly soluble silver compound (e.g. silver oxide, silver hydroxide, silver sulfide, silver-halogen compounds or combinations thereof; half-element II of the galvanic element). Ruthenium is a noble metal that has several oxidation states and is, for example, capable of forming different ruthenium oxides due to its different valences. Surface redox transitions such as Ru(VIII)/Ru(VI), Ru(VI)/Ru(IV), Ru(IV)/Ru(III) and possibly Ru(III)/Ru(II) are the reason for the high catalytic activity of the ruthenium mixed compounds and their good electrical conductivities. The unusually pronounced catalytic and electrocatalytic properties of the ruthenium compounds depend on the variation of the oxidation states. For example, the antimicrobial effect is particularly high for agent components according to the invention which comprise ruthenium (VI) oxide in the first half-element. The high catalytic activity of such half-elements for oxygen reduction is due to the easy change of oxidation states and the easy exchange of oxygen, which preferably takes place at the active centers of the semiconductor surface. The ruthenium is only changed in its valence, which results in the actual redox reaction. Therefore, no ruthenium compound is consumed or formed, only the oxidation states are changed. The ruthenium compound binds the molecular oxygen, allowing it to be catalytically reduced. Therefore, the presence of several valences is a prerequisite for the catalytic effect and the redox reaction. This means that no ruthenium compound needs to be formed. Poorly soluble silver compounds have catalytic properties, electrical conductivity and high stability in water. In addition to metallic ruthenium and metallic silver, the agent component can therefore also comprise a semiconducting, catalytically active ruthenium oxide or ruthenium sulfide (half element I of the galvanic element) and a semiconducting, sparingly soluble silver compound (silver oxide, silver hydroxide, silver sulfide, silver-halogen compounds or combinations thereof; half element II of the galvanic element).
The fiber material according to the invention can be used, for example, in the form of antimicrobial fibers as a component of fiber composites, yarns and/or textile fabrics (hygiene fiber composites, hygiene yarns or textile hygiene fabrics), so that these have lasting antimicrobial, deodorizing and odor-neutralizing properties over their entire textile life cycle. The fiber material according to the invention can also be used, for example, to produce absorbent fabrics, which in turn can be used as wound dressings, wound bandages and/or plaster materials, and/or can be integrated therein.
According to the invention, the problem is solved by a method for producing a fiber material having antimicrobial effect, in particular the fiber material described above, which comprises the following steps:
According to the invention, the antimicrobial agent component is thus added during fiber production, e.g. in the lyocell, viscose or carbamate process. This has the effect that the agent component as well as silver and ruthenium can be completely embedded in the fibers and/or are at least partially surrounded or entangled by them. It was found, unexpectedly even for the skilled person, that the addition of the silver-ruthenium agent component did not result in a reduction of the on-set temperature or other adverse effects of the manufacturing process. Thus, fiber production could be carried out on the standard systems and with the standard processes without any loss of quality, even with the addition of this agent component. It is also surprising for the skilled person that the antimicrobial, deodorizing and/or odor-neutralizing effect of the fiber material produced according to the invention, which is manufactured, for example, using the dry-wet spinning process and is already provided with particulate, liquid or meltable or vaporizable agent components during the shaping process, is not based on the release of heavy metal ions or organic biocidal agents and yet shows an antimicrobial effectiveness which clearly exceeds the values required in the relevant standards. Furthermore, the specialist is surprised by the durability of the effectiveness of the fiber material produced according to the invention. Neither after 50 washes nor after 100 washes is any significant deterioration in effectiveness observed. For example, even after 100 washing cycles in accordance with the test standard DIN EN ISO 6330 “Textiles-Non-commercial washing and drying methods for testing textiles”, fiber materials according to the invention still show strong efficacy in the antibacterial test in accordance with DIN EN ISO 20743:2013 (absorption method) against both the gram-positive test germ Staphylococcus aureus and the gram-negative test germ Klebsiella pneunomiae, and still show complete antiviral efficacy within 2 hours in the antiviral test based on ISO 18184 (test virus: phi 6 DSM 21518, host bacterium: Pseudomonas sp. DSM 21482).
It is also surprising for the skilled person that no coating of the surface of the cellulose and/or cellulose derivative fibers is required in order to achieve the antimicrobial, deodorizing and/or odor-neutralizing effect of the fiber material according to the invention. Rather, in contrast to the prior art, the agent component introduced into the fiber cross-section of the fibers is also effective without restriction in the case of complete, homogeneous and washout-resistant inclusion in the fiber matrix, even on the fiber surface. Furthermore, a particular advantage of the fiber material produced according to the method of the invention is that it has properties which are comparable to those of untreated fiber materials, e.g. with regard to mechanical stability, durability, dyeability, water absorption/absorbability, and processability.
In an advantageous embodiment of the method according to the invention, it is provided that the antimicrobial agent component is added in solid form, in particular as a powder, and dispersed in the pulp and/or the spinning solution and/or optionally the solvent system.
In an advantageous embodiment of the method according to the invention, it is further provided that the antimicrobial agent component in solid form, in particular as a powder, is first dispersed in the solvent system and the resulting dispersion is then added to the pulp.
In a further advantageous embodiment of the method according to the invention, it is provided that the pulp is homogenized after addition of the antimicrobial agent component.
In a further advantageous embodiment of the method according to the invention, it is provided that silver and ruthenium are added at least partially in the form of silver metal particles which are partially coated with metallic ruthenium.
In a further advantageous embodiment of the method according to the invention, it is provided that silver and ruthenium are added at least partially in the form of particles comprising a carrier material to which silver and ruthenium are applied. The carrier material is preferably selected in such a way that it also dissolves or at least separates from the silver and ruthenium under the conditions required in step d) for dissolving the cellulose and/or cellulose derivatives. In particular, the carrier material may comprise cellulose and/or at least one cellulose derivative. For example, an antimicrobial fiber material can be advantageously produced with such a cellulose-silver-ruthenium particle variant of the agent component using the lyocell technology by means of the method according to the invention, since the cellulose-silver-ruthenium particles, despite their catalytic activity, have no negative influence on the decomposition temperature (on-set temperature) of the solvent N-methylmorpholine-N-oxide (NMMO) used in the lyocell process and can thus be processed in the lyocell process. In the Lyocell process, the cellulose carrier material dissolves in the NMMO and releases the silver-ruthenium particles deposited on the carrier material in the cellulose-containing solvent in a uniformly distributed manner, so that antimicrobial regenerated Lyocell fibers for the textile industry, but also for nonwovens and other technical applications such as films, e.g. for packaging, can be produced therefrom.
These particles are not nanoparticles, but rather particles that have a length, diameter and/or circumference greater than 100 nanometers (nm).
The carrier material can, for example, comprise at least one material selected from the group consisting of cellulose, glass, zeolite, silicate, metal or a metal alloy, metal oxide (e.g. TiO2), ceramic, graphite, and a polymer. The agent component can thus be specifically adjusted by the choice of carrier material with regard to the integration requirements in the cellulose and/or cellulose derivative fibers of the specific applications. For example, with regard to water absorption/suction capacity (e.g. cellulose as carrier material), for production applications in apparatus' from which particle removal is only possible from the outside using a magnet (magnetic particles such as iron particles as carrier material), for the production of a product with a high degree of water absorption/suction capacity (e.g. cellulose as carrier material), cellulose integration in the production of regenerated fibers, wherein the cellulose doped with the agent component according to the invention dissolves in the organic cellulose solution and finely distributes the agent component in the pulp, from which cellulose threads can then be spun, or color design (e.g. white color: cellulose as carrier material).
Surprisingly, the selection of cellulose as a carrier material for silver and ruthenium has thus opened up a new production possibility for antimicrobial regenerated fibers with regard to the method of the invention. For example, cellulose (C) or its derivatives as microcrystalline (MCC) or nanocrystalline cellulose powder (NCC) can be used as the carrier material, which have a number of inherent properties that support the antimicrobial, deodorizing and/or odor-neutralizing effect of the fiber material according to the invention, such as their hydrophilicity and a high water-binding capacity, which is still about 5-8% in the dry state. The regenerated fibers produced according to the invention can be varied not only in fiber length, but also in fiber cross-section, whereby the fiber surface can be considerably increased. Thus, in addition to the “standard cellulose” with a cloud-shaped cross-section, fibers with star-shaped (Trilobal) or letter-shaped (Umberto) cross-sections are also available. The cellulose carrier surface can also be significantly increased by so-called bacterial cellulose (BC) due to its tissue-like, fine network structure. BC also has an increased water absorption capacity and is therefore often used in medical applications.
In addition to silver and ruthenium, the agent component can also comprise other substances within the meaning of the invention which have surface-active effects (for example surfactants), lipophilic properties (for example oils or fats) and/or hydrophilic properties (for example silicate particles).
In a further advantageous embodiment of the method according to the invention, it is provided that the solvent is N-methylmorpholine-N-oxide (NMMO), which is frequently used in the production of regenerated fibers. Alternatively, however, other suitable solvents or solvent systems, such as N,N-dimethylbenzylamine N-oxide or sodium hydroxide/carbon disulfide (NaOH/CS2), or solvents from the group of ionic liquids, such as 3-butyl-1-methylimidazolium acetate ([BMIM]Ac), can be used as solvents for the cellulose or cellulose derivatives in the manufacturing process.
According to the invention, the problem is further solved by a fiber material produced by means of the method described above. This fiber material according to the invention is characterized by an antimicrobial, deodorizing and/or odor-neutralizing effect which lasts over its entire service life and has other properties which are comparable to those of untreated fiber materials, e.g. with regard to mechanical stability, service life, dyeability, water absorption/absorbency and processability.
According to the invention, the problem is furthermore solved by using the fiber material according to the invention for the production of wound dressings, wound bandages and/or plaster materials. Yarns, knitted fabrics, knotted fabrics and/or woven fabrics produced from the fiber material according to the invention can thus be used in an advantageous manner for the production of wound dressings, wound bandages and/or plaster material due to the properties mentioned. These yarns, knitted fabrics, knotted fabrics and/or woven fabrics can themselves be used as wound dressings, wound bandages and/or plaster material, and/or can be integrated into such dressing material in the form of at least one absorbent body, for example in close connection with a carrier material. The yarns, knitted fabrics, knotted fabrics and/or woven fabrics produced from the fiber material according to the invention form an absorbent material which absorbs the wound exudate, including the germs present in the wound. In this way, the spread of germs in the absorbent material taking up the exudate and a retransmission of the germs taken up with the exudate into the wound can be prevented. Since the absorbent material according to the invention absorbs, immobilizes and inactivates or kills the microorganisms or germs discharged from the wound with the wound exudate, a wound dressing material formed or equipped accordingly can exert a significant antimicrobial effect without the antimicrobial compounds/substances or mechanisms having to be present and/or acting on the surface of the covered wound. Thus, wound dressings, wound bandages and/or plaster materials provided with and/or consisting of the fiber material according to the invention can advantageously exert an effective antimicrobial effect even if the wound or wound surface does not come into contact with antimicrobially active substances or mechanisms. Therefore, the wound dressings, wound bandages and/or plaster materials comprising the fiber material according to the invention contribute in a particularly advantageous manner to the gentle and well-tolerated acceleration of wound healing due to their integrated antimicrobial effect and the avoidance of reinfection. An absorbent material comprising the fiber material according to the invention can, for example, also be a carrier of a substance and/or material which maintains a moist climate in/over the wound, e.g. a hydrogel.
The invention further comprises the use of an antimicrobial agent component comprising metallic silver (Ag) and metallic ruthenium (Ru) as an agent for reducing or preventing odors in textile fiber materials. Fibers doped with this antimicrobial agent component as well as fiber composites, yarns and textile fabrics produced therefrom not only exhibit an antimicrobial effect that lasts over the entire life cycle of the textile structures, but also have a surprising and advantageous deodorizing and/or odor-neutralizing effect. It has been found that this additional effect is not only due to the inhibition or killing of microorganisms, but is also based in particular on the neutralization (e.g. by degradation or conversion) of organic substances. In olfactometric studies on the decay behavior of odor contaminants (set-up: test on long-lasting effects of odors and fragrances), it was shown that typical organic compounds that cause bad or foul odors, such as iso-valeric acid (3-methylbutanoic acid) or 3-hydroxy-3-methylhexanoic acid, could no longer be detected on fiber materials doped with the antimicrobial agent component according to the invention after a uniform loading time of 180 minutes, even after 60 minutes. Other organic substances that can be responsible for bad odors of textile fiber materials are, for example, 3-methyl-2-hexenoic acid, thioalcohol, androstenone, butyric acid, n-valeric acid, n-hexanoic acid and n-octanoic acid. These and many other odorous substances can also be effectively neutralized over the entire textile life cycle by using the antimicrobial Ag/Ru agent component according to the invention.
Due to the properties mentioned, yarns, knitted fabrics, knotted fabrics or woven fabrics produced from the fiber material according to the invention are ideally suited as sports, leisure or outdoor textiles, as home textiles, and as medical textiles for wound care or healing. Woven or nonwoven fabrics made from the fiber material according to the invention can also be used, for example, as permanently antimicrobial cleaning cloths (e.g. in the kitchen), plastic-coated nonwoven pieces in dishwashers or to support the washing effect in the washing machine. The invention also relates to hygiene fiber composites, hygiene yarns and textile hygiene fabrics made therefrom, as well as textiles made therefrom.
Hygienic yarns can be formed as part of the secondary spinning process in a mixture of 1 to 99% of the fiber material according to the invention with many mixed fibers used in textiles (natural and man-made fibers such as cotton, linen, hemp, wool, viscose, modal, lyocell, polyester, polyacrylonitrile, polyamide, polypropylene). Hygienic fibers and/or hygienic yarns made therefrom can also be processed into fabrics with 0.05 to 90% agent content using standard textile fabric forming processes (including nonwoven fabric production). In a special embodiment, yarns, fabrics or textiles can also be subsequently coated with the antimicrobial agent component in one of the aforementioned processing steps or special finishing steps. In addition to a simple coating using agent dispersions and subsequent agent fixation by drying, for example, a coating using special techniques such as ultrasonic impregnation or the like is also possible.
“Regenerated fibers” within the meaning of the invention refers to man-made fibers made from regenerated cellulose and/or cellulose derivatives, which are produced by means of a chemical process from cellulose (cellulose is a fibrous mass resulting from the chemical pulping of plant fibers, which consists predominantly of cellulose or cellulose derivatives (wood)). Regenerated fibers include viscose, modal, lyocell and cupro.
“Antimicrobial effect” in the sense of the invention refers to the property of a substance, a combination of substances, a material, a material composite and/or a surface thereof to kill microorganisms, to inhibit their growth and/or to prevent or impede microbial colonization or adhesion.
“Microorganisms” within the meaning of the invention refers to single-cell or multicellular, microscopically small organisms or particles selected from the group consisting of bacteria, fungi, algae, protozoa, and viruses.
“Pulp” in the sense of the invention refers to a cellulose dispersion dissolved down to the individual fiber in an aqueous solution.
“Particle” or “particulate” within the meaning of the invention refers to individual particulate bodies which are delimited as a whole from other particles and their environment. All possible particle shapes and sizes are included within the scope of the invention, irrespective of geometry and mass.
“Half element” within the meaning of the invention refers to a part of a galvanic element which forms this in conjunction with at least one other half element. A half-element comprises a metal electrode which is at least partially located in an electrolyte.
“Galvanic cell”, “galvanic element” or “microgalvanic element” within the meaning of the invention refers to the combination of two different metals, each of which forming an electrode (anode or cathode) in a common electrolyte. If the two metal electrodes are in direct contact with each other or are electrically conductively connected to each other via an electron conductor, the less noble metal with the lower redox potential (electron donor, anode) releases electrons to the more noble metal with the higher redox potential (electron acceptor, cathode) and consequently sets the redox processes at the electrodes in motion.
“Electrolyte” in the sense of the invention refers to a substance (e.g. ions in aqueous solution) which conducts electric current under the influence of an electric field through the directed movement of ions.
“Metal” within the meaning of the invention refers to atoms of a chemical element of the periodic table of elements (all elements which are not non-metals) which form a metal lattice by means of metallic bonds and thereby a macroscopically homogeneous material which is characterized, inter alia, by a high electrical conductivity and a high thermal conductivity. The term “metal” within the meaning of the invention also includes alloys comprising at least two different metals, metals which are at least partially present in the form of their respective salts, and metal compounds such as metal oxides, metal oxyhydrates, metal hydroxides, metal oxyhydroxides, metal halides and metal sulfides, as well as combinations of metals and corresponding metal compounds.
The invention is exemplarily explained in more detail in the following figures and examples.
After 0, 50 and 100 washes, the wet-laid nonwovens produced with an Ag/Ru functional fiber content of 30% received the following rating for the test germs tested:
Testing in accordance with ISO 18184 showed complete antiviral efficacy after 2 hours.
Neither parallel-washed, unmodified cellulose fibers, a PET control nor an organic cotton that was also washed in parallel showed an antibacterial or antiviral effect. This shows that the antimicrobial effect of the tested cellulose Ag/Ru fabrics is based on the incorporation of silver (Ag) and ruthenium (Ru) into the modified fibers. The numerical changes in the absolute values can be regarded as lying within the fluctuation range of the test method used.
In a stainless steel stirred tank, 399 g of pulp (type MODO, DP: 590, solids content: 95.5%) is mixed with 3,486 g of 80% aqueous NMMO solution. Add 2.4 g gallic acid propyl ester (0.63% based on the pulp dry weight) to the mixture and mix everything thoroughly for 15 minutes using an Ultra-Turrax at 10,000 min−1. The mixture is then transferred to a double-walled stirred vessel and the excess water is distilled off while stirring at 95° C. and a vacuum of 20 mbar. The resulting cellulose solution, whose onset temperature (temperature of the start of decomposition of the solvent NMMO), which was determined as a time-dependent pressure change (dp/dT)max to 153° C. according to [Knorr 2006] using a miniautoclave, for example, is transferred manually to a storage vessel and degassed at 80° C.
Under low N2 pressure, the spinning solution prepared in this way is extruded through nozzle holes with a diameter of 90 μm using a gear spinning pump and the resulting spinning capillaries are drawn in the air gap, regenerated as they pass the spinning bath surface and exhaustively freed from the NMMO with the countercurrent spinning bath.
After drying at 60° C., the fibers cut into staple fibers with a staple length of 38 mm have a final fineness (according to DIN EN ISO 1973 1995-12) of 1.62 dtex. Their fineness-related strength (according to DIN EN ISO 5079 1996-2) is 43.60 cN/tex, their elongation (also determined according to DIN EN ISO 5079:1996-2) is 12.8% and the fineness-related loop tensile strength (according to DIN 53843-2:1988-03) was determined to be 15.10 cN/tex.
The antibacterial effect (based on DIN EN ISO 20743:2013 absorption method, see examples 4-6) against both gram-positive (Staphylococcus aureus) and gram-negative (Klebsiella pneumoniae) test strains was determined to be ineffective in each case. The determination of antiviral efficacy (based on ISO 18184, test virus: phi6) also showed no reduction in viral load over a 2-hour determination period.
(A. Knorr: “Anwendung der TRAS 410 auf die sicherheitstechnische Beurteilung einer Perestersynthese”, Dissertation TU Berlin, 2006, p. 34 ff)
In a stainless steel container, 36 g of a finely ground ion exchange resin (weakly cross-linked cation exchanger based on a cross-linked copolymer of acrylic acid and sodium acrylate with a particle size D90≤8 μm) is homogeneously distributed in 1 l of aqueous NMMO (60%, w/w) using an Ultra-Turrax high-performance disperser and, after a standing time of 30 minutes, a pulp of 377 g pulp (MoDo, DP: 590, solids content: 95.5%) and 3.372 g NMMO is added. The modified pulp is homogenized again for 15 minutes at 10,000 min−1. In addition, 2.4 g gallic acid was added to the pulp as a stabilizer and the mixture was transferred to a double-walled stirred container. Its onset temperature was 145° C. The excess water is removed while stirring at 100° C. and a vacuum of 25 mbar until the cellulose is homogeneously dissolved. After transferring the spinning solution prepared in this way, staple fibers with a length of 60 mm, a titer of 6.7 dtex, a fineness-related tensile strength of 25.7 cN/tex, a maximum elongation of 14.8% and a fineness-related loop tensile strength of 8.2 cN/tex are formed at a spinning temperature of 90° C. and a spinning speed of 30 m/min. The staple fibers, completely free of solvent but still initially moist, are loaded with a 0.1 molar silver nitrate solution per kilogram of staple fiber material, pressed and then washed once with sodium chloride solution.
The loaded staple fibers are then dried at 80° C. to equilibrium moisture content. The silver content of the fibers produced in this way is approx. 6 percent.
A homogeneous mixture of 36 g of a ZnO/ZnS mixture (1:2, w/w, in each case D99≤2 μm) and 0.5 l of 60% NMMO (w/w) and 0.63% (based on the amount of cellulose used) of gallic acid propyl ester is added to a pulp produced analogously to Example 1. The mixture is homogenized at 10,000 min.−1 for 15 minutes and then formed into staple fibers with a length of 40 mm, a fineness of 1.5 dtex, a fineness-related tensile strength of 35.4 cN/tex, an elongation at break of 14.2% and a fineness-related loop tensile strength of 9.8 cN/tex, analogous to previous examples 1 or 2. The zinc content is 9%.
3.6 g silver/ruthenium powder is finely dispersed in 0.5 l aqueous NMMO (60%, w/w) using a Turrax high-performance disperser. The dispersion is then added to a pulp of 377 g cellulose (analogous to example 2) and 3,872 g NMMO and everything is homogenized again at 10,000 min−1 for 15 minutes. Gallic acid propyl ester in a concentration of 0.63% (based on the cellulose used) was used as a stabilizer. The thermal stability of the spinning solution produced in the same way as in Example 1 was determined by means of onset temperature measurement and was found to be 150° C., which is a safe value. The fibers spun and post-treated as in Example 1 have a final fineness of 1.76 dtex, a fineness-related tensile strength of 42 cN/tex, an elongation at break of 13.6% and a fineness-related loop strength of 14.4 cN/tex and are therefore completely equivalent to the fibers from Example 1.
The antibacterial efficacy (based on DIN EN ISO 20743:2013 absorption method) was determined against both gram-positive (Staphylococcus aureus) and gram-negative (Klebsiella pneumoniae) test strains. It was calculated as the difference between the Ig reduction of a control tested in parallel (Tula cotton) and the Ig reduction of a short fiber fleece sample over 24 hours in each case. Values above 3 are considered to have a strong antibacterial effect.
To determine the antiviral efficacy (based on ISO 18184, test virus: phi6), the reduction in the viral load of a reference tested in parallel (usually PET) and a sample over 2 hours was recorded. It is calculated from the difference between the decadic logarithms of the mean phage titers of the reference and the sample after 2 hours of contact.
A fiber sample prepared according to example 1 proved to have no antibacterial effect against either gram-positive or gram-negative test germs. The test also showed no reduction in the viral load over a 2-hour determination time. Even after 50 or 100 wash cycles, these samples showed no or only very low, non-specific antibacterial and no antiviral efficacy, which may result from the very smooth fiber morphology (see Table 1).
The lyocell fibers, which were spun in the same way as in Example 2 or Example 3, were processed into staple fiber yarns and subsequently into blended fabrics with a total functional fiber content of approx. 30%. Representative pieces of fabric were subjected to the antibacterial and antiviral tests mentioned in Example 6. Unwashed mixed fabrics showed an Ig reduction Δ log of 4.0 (example 2) and 3.4 (example 3) against Staphylococcus aureus and 3.8 (example 2) and 3.1 (example 3) against Klebsiella pneumoniae. The reduction in viral load after 2 hours was 3.1 (example 2) and 3.0 (example 3). After 30 washes in accordance with DIN EN ISO 6330, the antibacterial Ig reduction Δ log against Staphylococcus aureus had fallen to 2.9 (example 2) and 2.0 (example 3) and against Klebsiella pneumoniae to 2.4 (example 2) and 1.8 (example 3). The reduction of the viral load after 2 hours decreased to the low antiviral efficacy for both samples and amounted to 2.4 (example 2) and 2.1 (example 3). Based on the values obtained, a larger number of wash cycles was not examined.
Fibers produced in the same way as Example 1 and Example 4 were cut into short staple fibers with staple lengths≤5 mm before drying. The staple fibers dried to equilibrium moisture content were processed using a Rapid-Köthen sheet former to form circular wet laid nonwoven pieces with a dry weight of approx. 150 g/m2. To determine their antimicrobial effect, short fiber nonwovens made of 70% pure Lyocell fiber (manufactured according to example 1) and 30% fibers with 1% silver/ruthenium additive (manufactured according to example 4) were used in addition to completely unmodified ones. Analogous to example 4, these were also tested against the test germs mentioned there. Unmodified fibers were tested as a reference after 0 and 100 washes and 70/30 short fiber nonwovens were tested as a sample after 0, 50 and 100 washes. The washing tests of all wet-laid nonwovens were carried out in accordance with DIN EN ISO 6330. At the end of the washing tests, the washed nonwovens were opened separately, redispersed in deionized water and placed back on the short-fiber nonwoven using Rapid Köthen sheet former.
Table 1 shows the results of the independently performed antimicrobial tests.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21210621.5 | Nov 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/083266 | 11/25/2022 | WO |
