EP3385429A1

EP3385429A1 - Nonwoven cellulose fiber fabric with fiber connected radiation diffusing particles

Info

Publication number: EP3385429A1
Application number: EP17164606.0A
Authority: EP
Inventors: Tom Carlyle; Mirko Einzmann; Gisela Goldhalm; Malcolm John Hayhurst; Katharina Mayer; Ibrahim Sagerer Foric
Original assignee: Lenzing AG; Chemiefaser Lenzing AG
Current assignee: Lenzing AG
Priority date: 2017-04-03
Filing date: 2017-04-03
Publication date: 2018-10-10
Also published as: TWI782966B; TW201903227A; WO2018184926A1

Abstract

A nonwoven cellulose fiber fabric (102), in particular, directly manufactured from lyocell spinning solution (104), wherein the fabric (102) comprises a network of substantially endless fibers (108) and at least 0.1 mass % electromagnetic radiation diffusing particles (220) connected to the fibers (108).

Description

Field of the invention

The invention relates to a nonwoven cellulose fiber fabric, a method of manufacturing a nonwoven cellulose fiber fabric, a device for manufacturing a nonwoven cellulose fiber fabric, a product or composite, and a method of use.

Background of the invention

Lyocell technology relates to the direct dissolution of cellulose wood pulp or other cellulose-based feedstock in a polar solvent (for example n-methyl morpholine n-oxide, which may also be denoted as "amine oxide" or "AO") to produce a viscous highly shear-thinning solution which can be transformed into a range of useful cellulose-based materials. Commercially, the technology is used to produce a family of cellulose staple fibers (commercially available from Lenzing AG, Lenzing, Austria under the trademark TENCEL®) which are widely used in the textile industry. Other cellulose products from lyocell technology have also been used.
Cellulose staple fibers have long been used as a component for conversion to nonwoven webs. However, adaption of lyocell technology to produce nonwoven webs directly would access properties and performance not possible for current cellulose web products. This could be considered as the cellulosic version of the meltblow and spunbond technologies widely used in the synthetic fiber industry, although it is not possible to directly adapt synthetic polymer technology to lyocell due to important technical differences.
Much research has been carried out to develop technology to directly form cellulose webs from lyocell solutions (inter alia, WO 98/26122 , WO 99/47733 , WO 98/07911 , US 6,197,230 , WO 99/64649 , WO 05/106085 , EP 1 358 369 , EP 2 013 390 ). Further art is disclosed in WO 07/124521 A1 and WO 07/124522 A1 .

Object and summary of the invention

It is an object of the invention to provide a cellulose-based fiber fabric having adjustable optical properties and being safe in use.
In order to achieve the object defined above, a nonwoven cellulose fiber fabric, a method of manufacturing a nonwoven cellulose fiber fabric, a device for manufacturing a nonwoven cellulose fiber fabric, a product or composite, and a method of use according to the independent claims are provided.
According to an exemplary embodiment of the invention, a (in particular solution-blown) nonwoven cellulose fiber fabric is provided (which is in particular directly (in particular in an in situ process or in a continuous process executable in a continuously operating production line) manufactured from lyocell spinning solution), wherein the fabric comprises a network of substantially endless fibers and at least 0.1 mass % (in particular at least 0.4 mass %) electromagnetic radiation diffusing particles connected to (in particular applied on an exterior fiber surface and/or embedded in an interior of) the fibers.
According to another exemplary embodiment, a method of manufacturing (in particular solution-blown) nonwoven cellulose fiber fabric directly from lyocell spinning solution is provided, wherein the method comprises extruding the lyocell spinning solution through a jet (for instance a spinneret) with orifices supported by a gas flow into a coagulation fluid atmosphere (in particular an atmosphere of dispersed coagulation fluid) to thereby form substantially endless fibers, collecting the fibers on a fiber support unit to thereby form the fabric, and adjusting process parameters so that the fabric comprises at least 0.1 mass % electromagnetic radiation diffusing particles connected to the fibers.
According to a further exemplary embodiment, a device for manufacturing (in particular solution-blown) nonwoven cellulose fiber fabric directly from lyocell spinning solution is provided, wherein the device comprises a jet with orifices configured for extruding the lyocell spinning solution supported by a gas flow, a coagulation unit configured for providing a coagulation fluid atmosphere for the extruded lyocell spinning solution to thereby form substantially endless fibers, a fiber support unit configured for collecting the fibers to thereby form the fabric, and a control unit (such as a processor configured for executing program code for manufacturing the nonwoven cellulose fiber fabric directly from the lyocell spinning solution) configured for adjusting process parameters so that the fabric comprises at least 0.1 mass % electromagnetic radiation diffusing particles connected to the fibers.
According to still another exemplary embodiment, a product or composite is provided which comprises a fabric having the above mentioned properties.
According to yet another embodiment, a nonwoven cellulose fiber fabric having the above-mentioned properties is used for at least one of the group consisting of a wipe, a filter, a hygiene product, a medical application product, a geotextile, agrotextile, clothing, a product for building technology, an automotive product, a furnishing, an industrial product, a product related to beauty, leisure, sports or travel, and a product related to school or office.
In the context of this application, the term "nonwoven cellulose fiber fabric" (which may also be denoted as nonwoven cellulose filament fabric) may particularly denote a fabric or web composed of a plurality of substantially endless fibers. The term "substantially endless fibers" has in particular the meaning of filament fibers having a significantly longer length than conventional staple fibers. In an alternative formulation, the term "substantially endless fibers" may in particular have the meaning of a web formed of filament fibers having a significantly smaller amount of fiber ends per volume than conventional staple fibers. In particular, endless fibers of a fabric according to an exemplary embodiment of the invention may have an amount of fiber ends per volume of less than 10,000 ends/cm³, in particular less than 5,000 ends/cm³. For instance, when staple fibers are used as a substitute for cotton, they may have a length of 38 mm (corresponding to a typical natural length of cotton fibers). In contrast to this, substantially endless fibers of the nonwoven cellulose fiber fabric may have a length of at least 200 mm, in particular at least 1000 mm. However, a person skilled in the art will be aware of the fact that even endless cellulose fibers may have interruptions, which may be formed by processes during and/or after fiber formation. As a consequence, a nonwoven cellulose fiber fabric made of substantially endless cellulose fibers has a significantly lower number of fibers per mass compared to nonwoven fabric made from staple fibers of the same denier. A nonwoven cellulose fiber fabric may be manufactured by spinning a plurality of fibers and by attenuating and stretching the latter towards a preferably moving fiber support unit. Thereby, a three-dimensional network or web of cellulose fibers is formed, constituting the nonwoven cellulose fiber fabric. The fabric may be made of cellulose as main or only constituent.
In the context of this application, the term "lyocell spinning solution" may particularly denote a solvent (for example a polar solution of a material such as N-methyl-morpholine, NMMO, "amine oxide" or "AO") in which cellulose (for instance wood pulp or other cellulose-based feedstock) is dissolved. The lyocell spinning solution is a solution rather than a melt. Cellulose filaments may be generated from the lyocell spinning solution by reducing the concentration of the solvent, for instance by contacting said filaments with water. The process of initial generation of cellulose fibers from a lyocell spinning solution can be described as coagulation.
In the context of this application, the term "gas flow" may particularly denote a flow of gas such as air substantially parallel to the moving direction of the cellulose fiber or its preform (i.e. lyocell spinning solution) while and/or after the lyocell spinning solution leaves or has left the spinneret.
In the context of this application, the term "coagulation fluid" may particularly denote a non-solvent fluid (i.e. a gas and/or a liquid, optionally including solid particles) which has the capability of diluting the lyocell spinning solution and exchanging with the solvent to such an extent that the cellulose fibers are formed from the lyocell filaments. For instance, such a coagulation fluid may be water mist.
In the context of this application, the term "process parameters" may particularly denote all physical parameters and/or chemical parameters and/or device parameters of substances and/or device components used for manufacturing nonwoven cellulose fiber fabric which may have an impact on the properties of the fibers and/or the fabric, in particular on fiber diameter and/or fiber diameter distribution. Such process parameters may be adjustable automatically by a control unit and/or manually by a user to thereby tune or adjust the properties of the fibers of the nonwoven cellulose fiber fabric. Physical parameters which may have an impact on the properties of the fibers (in particular on their diameter or diameter distribution) may be temperature, pressure and/or density of the various media involved in the process (such as the lyocell spinning solution, the coagulation fluid, the gas flow, etc.). Chemical parameters may be concentration, amount, pH value of involved media (such as the lyocell spinning solution, the coagulation fluid, etc.). Device parameters may be size of and/or distances between orifices, distance between orifices and fiber support unit, speed of transportation of fiber support unit, the provision of one or more optional in situ post processing units, the gas flow, etc.
The term "fibers" may particularly denote elongated pieces of a material comprising cellulose, for instance roughly round or non-regularly formed in cross-section, optionally twisted with other fibers. Fibers may have an aspect ratio which is larger than 10, particularly larger than 100, more particularly larger than 1000. The aspect ratio is the ratio between the length of the fiber and a diameter of the fiber. Fibers may form networks by being interconnected by merging (so that an integral multi-fiber structure is formed) or by friction (so that the fibers remain separate but are weakly mechanically coupled by a friction force exerted when mutually moving the fibers being in physical contact with one another). Fibers may have a substantially cylindrical form which may however be straight, bent, kinked, or curved. Fibers may consist of a single homogenous material (i.e. cellulose). However, the fibers may also comprise one or more additives. Liquid materials such as water or oil may be accumulated between the fibers.
In the context of this document, a "jet with orifices" (which may for instance be denoted as an "arrangement of orifices") may be any structure comprising an arrangement of orifices which are linearly arranged.
In the context of this application, the term "electromagnetic radiation diffusing particles" may particularly denote solid pigments configured for efficiently scattering electromagnetic radiation. In other words, electromagnetic radiation diffusing particles may diffusely reflect electromagnetic radiation as a result of a strong scattering or bending of electromagnetic radiation at the particles. In the presence of electromagnetic radiation diffusing particles of a sufficient amount or concentration, a large portion of electromagnetic radiation of a corresponding wavelength striking the electromagnetic radiation diffusing particles will be reflected. As a result, the fabric may appear for instance opaque. In particular electromagnetic radiation diffusing particles operating in the visible range from 400 nm to 800 nm may impart opacity when incorporated into a nonwoven cellulose fiber fabric (which may have optically transparent properties under certain conditions, in particular when being wet). It is also possible that electromagnetic radiation diffusing particles efficiently scattering optical light impart whiteness and/or brightness of a nonwoven cellulose fiber fabric. In certain embodiments, electromagnetic radiation diffusing particles may however also operate in a nonvisible wavelength range: For instance, the electromagnetic radiation diffusing particles may be capable of efficiently scattering electromagnetic radiation in the infrared range (in particular in a range of wavelengths between 800 nm and 1 mm) and/or in the ultraviolet range (in particular in a range of wavelengths between 100 nm and 400 nm) and/or in the X-ray range (in particular in a range of wavelengths between 1 pm and 250 pm).
According to an exemplary embodiment, a nonwoven cellulose fiber fabric is provided which comprises incorporated electromagnetic radiation diffusing particles capable of diffusing electromagnetic radiation. This makes it for instance possible to render the fabric opaque in a suitable wavelength range adjustable by selecting the specific properties of the electromagnetic radiation diffusing particles. What concerns the properties of cellulose based fabric of endless fibers in the visible range, enriching the fibers with visible light diffusing particles allows to render the fabric opaque when wet. An optically transparent wet fabric may be disturbing for certain applications such as clothing. What concerns the properties of the fabric in the ultraviolet range, opacity for UV radiation is advantageous for other applications, such as a sunlight protection of clothing. Even in the X-ray range or in the range of gamma radiation, the absorption of this radiation by the fabric may be advantageous to provide radiation protection, or detection, for instance in terms of medical applications.
Advantageously, it is possible to stably incorporate electromagnetic radiation diffusing particles in a nonwoven cellulose fiber fabric by dispersing electromagnetic radiation diffusing particles into an operating fluid used for manufacturing the fabric. Such an operating fluid may be a dope or lyocell spinning solution, a gas flow used for stretching lyocell spinning solution during fiber formation, a coagulation fluid promoting precipitation of the fiber, etc. Since particles may cause harm when being easily removed from the fabric (for instance in view of health issues with respirable dust), a strong bonding or even embedding of the particles on or in the fibers of the fabric is highly advantageous. By connecting, bonding or immobilizing at least part of the integrated particles to the fibers (in particular adhering the particles to an exterior surface of the fibers and/or embedding the particles fully within the fibers) rather than only accommodating the fibers unconnected in hollow spaces within the fabric, it can be ensured that the corresponding particles are efficiently prevented from being released from the fabric during use. This ensures safe operation of the fabric when used by a human user who is therefore protected from being exposed to released fine particles.

Detailed description of embodiments of the invention

In the following, further exemplary embodiments of the nonwoven cellulose fiber fabric, the method of manufacturing a nonwoven cellulose fiber fabric, the device for manufacturing a nonwoven cellulose fiber fabric, the product or composite, and the method of use are described.
In an embodiment, the fabric comprises not more than 15 mass % electromagnetic radiation diffusing particles, in particular not more than 4 mass % electromagnetic radiation diffusing particles. When remaining in these ranges, the electromagnetic radiation diffusing particles can remain rigidly bonded to the fibers within the fabric without being separated therefrom.
In an embodiment, the electromagnetic radiation diffusing particles are configured for diffusing electromagnetic radiation from at least one wavelength range selected from a group consisting of visible light, infrared light, ultraviolet light, and X-ray light. It is also possible that the electromagnetic radiation diffusing particles have pronounced diffusing properties even in more than one of the mentioned ranges and/or in other wavelength ranges.
In an embodiment, the electromagnetic radiation diffusing particles comprises at least one of the group consisting of silicates, magnesium oxide, magnesium hydrosilicate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, titanium dioxide, barium sulfate, calcium carbonate, boron nitride, silicon dioxide, and zinc oxide. For instance, titanium dioxide is a powerful material for manufacturing electromagnetic radiation diffusing particles operating in the visible range. Barium sulfate is an example for a material of electromagnetic radiation diffusing particles being active in the X-ray range.
A preferred choice for the electromagnetic radiation diffusing particles is titanium dioxide. Titanium dioxide pigments are insoluble in coating vehicles in which they are dispersed. Accordingly, performance properties (such as chemical, photochemical and physical characteristics) are determined in particular by the particle size of the pigment and the chemical composition of its surface. This allows a particularly precise and reproducible adjustment of the optical properties of the fabric when using titanium oxide pigments as electromagnetic radiation diffusing particles.
In an embodiment, a number of at least 80% of the electromagnetic radiation diffusing particles have a diameter of at least 70 nm, in particular of at least 100 nm, more particularly in a range between 70 nm and 3000 nm, preferably in a range between 100 nm and 200 nm. The given percentage value is hence related to a number of particles. In particular, the particle size of the electromagnetic radiation diffusing particles may be in the submicron range. As can be taken from Figure 8, the functionality of electromagnetic radiation diffusing particles in terms of light scattering are particularly pronounced in the mentioned ranges. Furthermore, electromagnetic radiation diffusing particles of these dimensions have turned out to remain stably within a fabric without being easily separated therefrom (in particular without being easily washed off from the readily manufactured fabric). By the adjustment of the particle size, a frequency selection of strongly influenced electromagnetic radiation can be made.
In an embodiment, a number of at least 80% of the electromagnetic radiation diffusing particles (in particular of titanium dioxide type) are in rutile state (compare Figure 9) or anatase state (compare Figure 10). In certain embodiments, electromagnetic radiation diffusing particles in rutile state may be preferred, since they have a particularly pronounced efficiency of light scattering while being at the same time more stable and more durable than pigments in other crystal structures. However, for other applications also particles in the anatase state can be appropriately used. In particular, the pronounced photocatalytic activity of anatase type titanium dioxide may be advantageously used for providing the fabric with the property of decomposing harmful substances.
More generally, at least a part of the electromagnetic radiation diffusing particles may be functionalized, in particular may be rendered photocatalytically active. Advantageously, a photocatalytically active fabric may have a self-cleaning function. Other functionalizations of the fabric by using correspondingly functionalized (for instance intrinsically functionalized or functionalized by coating) electromagnetic radiation diffusing particles are wicking (in particular wicking speed), oil take up, water absorption, cleanability, roughness.
In an embodiment, at least part, in particular a number of at least 50%, more particularly a number of at least 90%, of the electromagnetic radiation diffusing particles are embedded in an interior of the fibers, i.e. may be fully circumferentially surrounded by fiber material. Arranging the particles embedded in an interior of the fibers may be obtained by adjusting the process parameters by adding the particles to lyocell spinning solution prior to or during coagulation of precipitation of fibers. Embedding the particles within the fibers is a particularly efficient measure for preventing separation of the particles from the fabric even under harsh conditions.
In an embodiment, at least part, in particular a number of at least 50%, more particularly a number of at least 90%, of the electromagnetic radiation diffusing particles are attached to a surface of the fibers, i.e. may have a partial surface area remaining exposed to an environment and being not covered by the fiber material. Arranging the particles attached to an exterior of the fibers may be obtained by adjusting the process parameters by adding the particles to lyocell spinning solution at the end of the coagulation or precipitation procedure of fibers, or even after completion of the coagulation or precipitation procedure. Attaching the particles to an exterior surface of the fibers promotes a strong interaction between the particles and an environment (for instance in terms of a photocatalytic activity).
In an embodiment, the electromagnetic radiation diffusing particles have a refraction index (for instance for visible light, more particularly red light) of more than 1.5. This allows to obtain a pronounced opacity even when the nonwoven cellulose fiber fabric is wet.
In an embodiment, the electromagnetic radiation diffusing particles are configured so that the fabric is opaque in a wet condition, in particular when soaked with water. With a corresponding selection of particle material and particle size as well as with a corresponding selection of particle content in the fabric, it can be ensured that the fabric is not optically transparent even when it is filled with water.
In an embodiment, at least part, in particular at least a number of 50%, more particularly at least a number of 90%, of the electromagnetic radiation diffusing particles have a spherical shape. When the electromagnetic radiation diffusing particles are provided with spherical shape, the described advantageous effects in terms of reinforcement of adhesion and embedding are particularly pronounced. Moreover, spherical particles show a particularly advantageous dispersion behavior in operating fluid for manufacturing nonwoven cellulose fiber fabric, such as lyocell spinning solution.
In an embodiment, at least part of the electromagnetic radiation diffusing particles is connected to the lyocell spinning solution prior to completing coagulation. This increases the adhesion forces between fibers and particles and suppresses undesired release of the particles from the fabric.
In an embodiment, the coagulation fluid is enriched with at least part of the electromagnetic radiation diffusing particles to thereby provide the fabric with the electromagnetic radiation diffusing particles. When particles are included in the coagulation fluid, for instance a water mist in which particles are dispersed, they may interact with the strands of lyocell spinning solution for precipitation of the fibers so that the fibers are integrally mixed with the electromagnetic radiation diffusing particles.
In an embodiment, the gas flow is enriched with at least part of the electromagnetic radiation diffusing particles to thereby provide the fabric with the electromagnetic radiation diffusing particles. The gas flow is used for stretching filaments of lyocell spinning solution prior to coagulation or precipitation. When this gas flow is enriched with electromagnetic radiation diffusing particles, the latter can be incorporated in the fabric in a simple way and without a separate manufacturing procedure.
In an embodiment, the lyocell spinning solution is enriched with at least part of the electromagnetic radiation diffusing particles upstream of the orifices to thereby provide the fabric with the electromagnetic radiation diffusing particles. When already the dope of lyocell spinning solution is provided with the electromagnetic radiation diffusing particles, it is possible that a sufficiently large amount of the particles is embedded in an interior of the fibers so that the particles can be efficiently protected against separation from the fabric.
In an embodiment, the collected fibers are made subject to a washing procedure washing out electromagnetic radiation diffusing particles from the fabric which are only weakly connected to the fibers. While being transported along the fiber support unit, the nonwoven cellulose fiber fabric can be washed by washing unit supplying wash liquor to remove not only residual solvent, but also those particles which have not been connected strong enough to the fibers during manufacture. This prevents undesired release of particles during use of the fabric.
In an embodiment, the fibers have (in particular the fiber fabric has) a copper content of less than 5 ppm (in particular 5 mass ppm, i.e. 5 mg/kg) and/or have a nickel content of less than 2 ppm (in particular 2 mass ppm, i.e. 2 mg/kg). Due to the use of a lyocell spinning solution as a basis for the formation of the endless fiber-based fabric (in particular when involving a solvent such as N-methyl-morpholine, NMMO), the contamination of the fabric with the mentioned particularly harmful heavy metals copper (which may be harmful to health for human beings, in particular for children, when exceeding a certain dose) and/or nickel (which may cause allergic reactions of a user) may be kept extremely small. In particular, the very small amount of copper contamination can be ensured by omitting a copper salt solution for preparing the spinning solution.
In an embodiment, at least part of (in particular at least 10% of) the fibers are integrally merged at merging positions. In the context of this application, the term "merging" may particularly denote an integral interconnection of different fibers at the respective merging position which results in the formation of one integrally connected fiber structure composed of the previously separate fiber preforms. Merging may be denoted as a fiber-fiber connection being established during coagulation of one, some or all of the merged fibers. Interconnected fibers may strongly adhere to one another at a respective merging position without a different additional material (such as a separate adhesive) so as to form a common structure. Separation of merged fibers may require destruction of the fiber network or part thereof. According to the described embodiment, a nonwoven cellulose fiber fabric is provided in which some or all of the fibers are integrally connected to one another by merging. Merging may be triggered by a corresponding control of the process parameters of a method of manufacturing the nonwoven cellulose fiber fabric. In particular, coagulation of filaments of lyocell spinning solution may be triggered (or at least completed) after the first contact between these filaments being not yet in the precipitated solid fiber state. Thereby, interaction between these filaments while still being in the solution phase and then or thereafter converting them into the solid-state phase by coagulation allows to properly adjust the merging characteristics. A degree of merging is a powerful parameter which can be used for adjusting the properties of the manufactured fabric. In particular, mechanical stability of the network is the larger the higher the density of merging positions is. By an inhomogeneous distribution of merging positions over the volume of the fabric, it is also possible to adjust regions of high mechanical stability and other regions of low mechanical stability. For instance, separation of the fabric into separate parts can be precisely defined to happen locally at mechanical weak regions with a low number of merging positions. In a preferred embodiment, merging between fibers is triggered by bringing different fiber preforms in form of lyocell spinning solution in direct contact with one another prior to coagulation.
Due to the concept of direct merging of fibers under certain conditions adjustable by process control, no extra material (such as a binder or the like) needs to be introduced in the process for interconnecting the fibers. This keeps contaminations of the fabric very low. Thus, interconnecting fibers by merging rather than adhering them using a separate adhesive material additionally contributes to the high degree of purity of the manufactured fabric.
In an embodiment, the merging positions consist of the same material as the merged fibers. Thus, the merging positions may be formed by cellulose material resulting directly from the coagulation of lyocell spinning solution. This not only renders the separate provision of a fiber connection material (such as an adhesive or a binder) dispensable, but also keeps the fabric clean and made substantially of a single material.
Merging may have the additional advantageous effect that merged endless fibers additionally inhibit electromagnetic radiation diffusing particles from leaving the fabric, as the overall fiber surface in the fabric is reduced.
In an embodiment, different ones of the fibers are located at least partially in different distinguishable (i.e. showing a visible separation or interface region in between the layers) layers. More specifically, fibers of different layers are integrally merged at at least one merging position between the layers. Hence, different ones of the fibers being located at least partially in different distinguishable layers (which may be identical or which may differ concerning one or more parameters such as merging factor, average fiber diameter, etc.) may be integrally connected at at least one merging position. For instance, two (or more) different layers of a fabric may be formed by serially aligning two (or more) jets with orifices through which lyocell spinning solution is extruded for coagulation and fiber formation. When such an arrangement is combined with a moving fiber support unit (such as a conveyor belt with a fiber accommodation surface), a first layer of fibers is formed on the fiber support unit by the first jet, and the second jet forms a second layer of fibers on the first layer when the moving fiber support unit reaches the position of the second jet. The process parameters of this method may be adjusted so that merging points are formed between the first layer and the second layer. In particular, fibers of the second layer under formation being not yet fully cured or solidified by coagulation may for example still have exterior skin or surface regions which are still in the liquid lyocell solution phase and not yet in the fully cured solid state. When such pre-fiber structures come into contact with one another and fully cure into the solid fiber state thereafter, this may result in the formation of two merged fibers at an interface between different layers. The higher the number of merging positions, the higher is the stability of the interconnection between the layers of the fabric. Thus, controlling merging allows to control rigidity of the connection between the layers of the fabric. Merging can be controlled, for example, by adjusting the degree of curing or coagulation before pre-fiber structures of a respective layer reach the fiber support plate on an underlying layer of fibers or pre-fiber structures. By merging of fibers of different layers at an interface there between, undesired separation of the layers may be prevented. In the absence of merging points between the layers, peeling off one layer from the other layer of fibers may be made possible.
In an embodiment, the merging between the different layers is adjusted so that pulling on the layers in opposite directions results in a separation of the fabric at an interface between the different layers. This can be achieved when the merging is adjusted so that merging-based adhesion between the different layers is smaller than merging based adhesion within a respective one of the different layers. In particular, a number of merging points or merging positions per volume may be larger in an interior of a respective one of the connected layers than at in an interface region between the layers. This can be manufactured by controlling the relation between inter-layer coagulation and intra-layer coagulation.
In an embodiment, an average diameter of the fibers of one of the layers is different from an average diameter of the fibers of another one of the layers. For instance, a ratio between the average diameter of the fibers of the one layer and the average diameter of the fibers of the other layer may be at least 1.5, in particular may be at least 2.5, more particularly may be at least 4. Thus, a nonwoven cellulose fiber fabric may be provided which can be manufactured as a network of substantially endless cellulose fibers showing a pronounced inhomogeneity in terms of fiber diameter between different layers. It has turned out that the distribution of diameters of the fibers of the nonwoven cellulose fiber fabric is a powerful design parameter for adjusting the physical properties, in particular the mechanical properties, of the obtained fabric. Without wishing to be bound to a specific theory, it is presently believed that such an inhomogeneous distribution of fiber thicknesses results in a self-organization of the fiber network which inhibits mutual motion of the individual fibers relative to one another. In contrast to this, the fibers tend to clamp together, thereby obtaining a compound with a high rigidity. Descriptively speaking, introducing a certain inhomogeneity in the fiber manufacturing process may translate into an inhomogeneity of the thickness or diameter distribution of the fibers in the fabric as a whole. However, it should be mentioned that by varying fiber diameter as a design parameter for a fabric, fiber physics may be adjusted in a more general way allowing to vary physical properties of the fabric over a broad range (wherein reinforcing stiffness is only one option or example). For instance, fiber diameter variation can also be a powerful tool for tuning moisture management of the manufactured fabric. By applying electromagnetic radiation diffusing particles to the spinning solution the overall density of the spinning solution changes and thus also the behavior during the spinning process changes. This will also result in a change of fiber diameter distribution and merging behavior and thus further gives the possibility to adjust the properties of the so produced fabric.
Different layers may also be provided with different concentrations and/or types of electromagnetic radiation diffusing particles. This may allow to fine tune the optical properties of the multi-layer fabric.
In an embodiment, the method further comprises further processing the fibers and/or the fabric after collection on the fiber support unit but preferably still in situ with the formation of the nonwoven cellulose fiber fabric with endless fibers. Such in situ processes may be those processes being carried out before the manufactured (in particular substantially endless) fabric is stored (for instance wound by a winder) for shipping to a product manufacture destination. For instance, such a further processing or post processing may involve hydroentanglement. Hydroentanglement may be denoted as a bonding process for wet or dry fibrous webs, the resulting bonded fabric being a nonwoven. Hydroentanglement may use fine, high pressure jets of water which penetrate the web, hit a fiber support unit (in particular a conveyor belt) and bounce back causing the fibers to entangle. A corresponding compression of the fabric may render the fabric more compact and mechanically more stable. Additionally or alternatively to hydroentanglement, steam treatment of the fibers with a pressurized steam may be carried out. Additionally or alternatively, such a further processing or post processing may involve a needling treatment of the manufactured fabric. A needle punching system may be used to bond the fibers of the fabric or web. Needle punched fabrics may be produced when barbed needles are pushed through the fibrous web forcing some fibers through the web, where they remain when the needles are withdrawn. If sufficient fibers are suitably displaced the web may be converted into a fabric by the consolidating effect of these fibers plugs. Yet another further processing or post processing treatment of the web or fabric is an impregnating treatment. Impregnating the network of endless fibers may involve the application of one or more chemicals (such as a softener, a hydrophobic agent, an antistatic agent, etc.) on the fabric. Still another further processing treatment of the fabric is calendering. Calendering may be denoted as a finishing process for treating the fabric and may employ a calender to smooth, coat, and/or compress the fabric.
A nonwoven cellulose fiber fabric according to an exemplary embodiment of the invention may also be combined (for instance in situ or in a subsequent process) with one or more other materials, to thereby form a composite according to an exemplary embodiment of the invention. Exemplary materials, which can be combined with the fabric for forming such a composite may be selected from a group of materials comprising, but not being limited to, the following materials or combinations thereof: fluff pulp, a fiber suspension, a wetlaid nonwoven, an airlaid nonwoven, a spunbond web, a meltblown web, a carded spunlaced or needlepunched web or other sheet like structures made of various materials. In an embodiment, the connection between the different materials can be done by (but not limited to) one or a combination of the following processes: merging, hydroentanglement, needle punching, hydrogen bonding, thermobonding, gluing by a binder, laminating, and/or calendering.
In the following, exemplary advantageous products comprising, or uses of, a nonwoven cellulose fiber fabric according to exemplary embodiments of the invention are summarized:

Particular uses of the webs, either 100% cellulose fiber webs, or for example webs comprising or consisting of two or more fibers, or chemically modified fibers or fibers with incorporated materials such as anti-bacterial materials, ion exchange materials, active carbon, nano particles, lotions, medical agents or fire retardants, or bicomponent fibers may be as follows:
- The nonwoven cellulose fiber fabric according to exemplary embodiments of the invention may be used for manufacturing wipes such as baby, kitchen, wet wipes, cosmetic, hygiene, medical, cleaning, polishing (car, furniture), dust, industrial, duster and mops wipes.

It is also possible that the nonwoven cellulose fiber fabric according to exemplary embodiments of the invention is used for manufacturing a filter. For instance, such a filter may be an air filter, a HVAC, air condition filter, flue gas filter, liquid filters, coffee filters, tea bags, coffee bags, food filters, water purification filter, blood filter, cigarette filter; cabin filters, oil filters, cartridge filter, vacuum filter, vacuum cleaner bag, dust filter, hydraulic filter, kitchen filter, fan filter, moisture exchange filters, pollen filter, HEVAC/HEPA/ULPA filters, beer filter, milk filter, liquid coolant filter and fruit juices filters.
In yet another embodiment, the nonwoven cellulose fiber fabric may be used for manufacturing absorbent hygiene products. Examples thereof are an acquisition layer, a coverstock, a distribution layer, an absorbent cover, sanitary pads, topsheets, backsheets, leg cuffs, flushable products, pads, nursing pads, disposal underwear, training pants, face masks, beauty facial masks, cosmetic removal pads, washcloths, diapers, and sheets for a laundry dryer releasing an active component (such as a textile softener).
In still another embodiment, the nonwoven cellulose fiber fabric may be used for manufacturing a medical application product. For instance, such medical application products may be disposable caps, gowns, masks and shoe cover, wound care products, sterile packaging products, coverstock products, dressing materials, one way clothing, dialyses products, nasal strips, adhesives for dental plates, disposal underwear, drapes, wraps and packs, sponges, dressings and wipes, bed linen, transdermal drug delivery, shrouds, underpads, procedure packs, heat packs, ostomy bag liners, fixation tapes and incubator mattresses.
In yet another embodiment, the nonwoven cellulose fiber fabric may be used for manufacturing geotextiles. This may involve the production of crop protection covers, capillary matting, water purification, irrigation control, asphalt overlay, soil stabilisation, drainage, sedimentation and erosion control, pond liners, impregnation based, drainage channel liners, ground stabilisation, pit linings, seed blankets, weed control fabrics, greenhouse shading, root bags and biodegradable plant pots. It is also possible to use the nonwoven cellulose fiber fabric for a plant foil (for instance providing a light protection and/or a mechanical protection for a plant, and/or providing the plant or soil with dung or seed).
In another embodiment, the nonwoven cellulose fiber fabric may be used for manufacturing clothing. For example, interlinings, clothing insulation and protection, handbag components, shoe components, belt liners, industrial headwear/foodwear, disposable workwear, clothing and shoe bags and thermal insulation may be manufactured on the basis of such fabric.
In still another embodiment, the nonwoven cellulose fiber fabric may be used for manufacturing products used for building technology. For instance, roofing and tile underlay, underslating, thermal and noise insulation, house wrap, facings for plaster board, pipe wrap, concrete moulding layers, foundations and ground stabilisation, vertical drainages, shingles, roofing felts, noise abatement, reinforcement, sealing material, and damping material (mechanical) may be manufactured using such fabric.
In still another embodiment, the nonwoven cellulose fiber fabric may be used for manufacturing an automotive product. Examples are a cabin filter, boot liners, parcel shelves, heat shields, shelf trim, moulded bonnet liners, boot floor covering, oil filter, headliners, rear parcel shelves, decorative fabrics, airbags, silencer pads, insulation materials, car covers, underpadding, car mats, tapes, backing and tufted carpets, seat covers, door trim, needled carpet, and auto carpet backing.
Still another field of application of fabric manufactured according to exemplary embodiments of the invention are furnishings, such as furniture, construction, insulator to arms and backs, cushion thicking, dust covers, linings, stitch reinforcements, edge trim materials, bedding constructions, quilt backing, spring wrap, mattress pad components, mattress covers, window curtains, wall coverings, carpet backings, lampshades, mattress components, spring insulators, sealings, pillow ticking, and mattress ticking.
In yet another embodiment, the nonwoven cellulose fiber fabric may be used for manufacturing industrial products. This may involve electronics, floppy disc liners, cable insulation, abrasives, insulation tapes, conveyor belts, noise absorbent layers, air conditioning, battery separators, acid systems, anti-slip matting stain removers, food wraps, adhesive tape, sausage casing, cheese casing, artificial leather, oil recovery booms and socks, and papermaking felts.
Nonwoven cellulose fiber fabric according to exemplary embodiments of the invention is also appropriate for manufacturing products related to leisure and travel. Examples for such an application are sleeping bags, tents, luggage, handbags, shopping bags, airline headrests, CD-protection, pillowcases, and sandwich packaging.
Still another field of application of exemplary embodiment of the invention relates to school and office products. As examples, book covers, mailing envelopes, maps, signs and pennants, towels, and flags shall be mentioned.

Brief description of the drawings

The invention will be described in more detail hereinafter with reference to examples of embodiment but to which the invention is not limited:

Figure 1 illustrates a device for manufacturing nonwoven cellulose fiber fabric which is directly formed from lyocell spinning solution being coagulated by a coagulation fluid according to an exemplary embodiment of the invention.
Figure 2 to Figure 4 show experimentally captured images of nonwoven cellulose fiber fabric according to an exemplary embodiment of the invention in which merging of individual fibers has been accomplished by a specific process control.
Figure 5 and Figure 6 show experimentally captured images of nonwoven cellulose fiber fabric according to an exemplary embodiment of the invention in which swelling of fibers has been accomplished, wherein Figure 5 shows the fiber fabric in a dry non-swollen state and Figure 6 shows the fiber fabric in a humid swollen state.
Figure 7 shows an experimentally captured image of nonwoven cellulose fiber fabric according to an exemplary embodiment of the invention in which formation of two superposed layers of fibers has been accomplished by a specific process implementing two serial bars of nozzles.
Figure 8 shows a diagram illustrating a relation between a particle dimension, plotted along an abscissa, and a relative light scattering capability, plotted along an ordinate, of rutile-type titanium oxide as electromagnetic radiation diffusing particles of nonwoven cellulose fiber fabric according to an exemplary embodiment of the invention.
Figure 9 illustrates an elementary cell of rutile-type titanium oxide used as electromagnetic radiation diffusing particles of nonwoven cellulose fiber fabric according to an exemplary embodiment of the invention.
Figure 10 illustrates an elementary cell of anatase-type titanium oxide used as electromagnetic radiation diffusing particles of nonwoven cellulose fiber fabric according to another exemplary embodiment of the invention.
Figure 11 illustrates procedures carried out during executing a method of manufacturing nonwoven cellulose fiber fabric with implemented electromagnetic radiation diffusing particles according to exemplary embodiments of the invention.
Figure 12 illustrates a device for manufacturing nonwoven cellulose fiber fabric according to an exemplary embodiment of the invention which is specifically adapted for integrating electromagnetic radiation diffusing particles in the nonwoven cellulose fiber fabric.

Detailed description of the drawings

The illustrations in the drawings are schematic. In different drawings similar or identical elements are provided with the same reference labels.
Figure 1 illustrates a device 100 according to an exemplary embodiment of the invention for manufacturing nonwoven cellulose fiber fabric 102 which is directly formed from lyocell spinning solution 104. The latter is at least partly coagulated by a coagulation fluid 106 to be converted into partly-formed cellulose fibers 108. By the device 100, a lyocell solution blowing process according to an exemplary embodiment of the invention may be carried out. In the context of the present application, the term "lyocell solution-blowing process" may particularly encompass processes which can result in essentially endless filaments or fibers 108 of a discrete length or mixtures of endless filaments and fibers of discrete length being obtained. As further described below, nozzles each having an orifice 126 are provided through which cellulose solution or lyocell spinning solution 104 is ejected together with a gas stream or gas flow 146 for manufacturing the nonwoven cellulose fiber fabric 102 according to an exemplary embodiment of the invention.
As can be taken from Figure 1, wood pulp 110, other cellulose-based feedstock or the like may be supplied to a storage tank 114 via a metering unit 113. Water from a water container 112 is also supplied to the storage tank 114 via metering unit 113. Thus, the metering unit 113, under control of a control unit 140 described below in further detail, may define relative amounts of water and wood pulp 110 to be supplied to the storage tank 114. A solvent (such as N-methyl-morpholine, NMMO) accommodated in a solvent container 116 may be concentrated in a concentration unit 118 and may then be mixed with the mixture of water and wood pulp 110 or other cellulose-based feedstock with definable relative amounts in a mixing unit 119. Also the mixing unit 119 can be controlled by the control unit 140. Thereby, the water-wood pulp 110 medium is dissolved in the concentrated solvent in a dissolving unit 120 with adjustable relative amounts, thereby obtaining lyocell spinning solution 104. The aqueous lyocell spinning solution 104 can be a honey-viscous medium composed of (for instance 5 mass % to 15 mass %) cellulose comprising wood pulp 110 and (for instance 85 mass % to 95 mass %) solvent.
The lyocell spinning solution 104 is forwarded to a fiber formation unit 124 (which may be embodied as or which may comprise a number of spinning beams or jets 122). For instance, the number of orifices 126 of the jets 122 may be larger than 50, in particular larger than 100. In one embodiment, all orifices 126 of a fiber formation unit 124 (which may comprise a number of spinnerets or jets 122) of orifices 126 of the jets 122 may have the same size and/or shape. Alternatively, size and/or shape of different orifices 126 of one jet 122 and/or orifices 126 of different jets 122 (which may be arranged serially for forming a multilayer fabric) may be different.
When the lyocell spinning solution 104 passes through the orifices 126 of the jets 122, it is divided into a plurality of parallel strands of lyocell spinning solution 104. A vertically oriented gas flow, i.e. being oriented substantially parallel to spinning direction, forces the lyocell spinning solution 104 to transform into increasingly long and thin strands which can be adjusted by changing the process conditions under control of control unit 140. The gas flow may accelerate the lyocell spinning solution 104 along at least a part of its way from the orifices 126 to a fiber support unit 132.
While the lyocell spinning solution 104 moves through the jets 122 and further downward, the long and thin strands of the lyocell spinning solution 104 interact with non-solvent coagulation fluid 106. The coagulation fluid 106 is advantageously embodied as a vapor mist, for instance an aqueous mist. Process relevant properties of the coagulation fluid 106 are controlled by one or more coagulation units 128, providing the coagulation fluid 106 with adjustable properties. The coagulation units 128 are controlled, in turn, by control unit 140. Preferably, respective coagulation units 128 are provided between the individual nozzles or orifices 126 for individually adjusting properties of respective layers of fabric 102 being produced. Preferably, each jet 122 may have two assigned coagulation units 128, one from each side. The individual jets 122 can thus be provided with individual portions of lyocell spinning solution 104 which may also be adjusted to have different controllable properties of different layers of manufactured fabric 102.
When interacting with the coagulation fluid 106 (such as water), the solvent concentration of the lyocell spinning solution 104 is reduced, so that the cellulose of the former e.g. wood pulp 110 (or other feedstock) is at least partly coagulated as long and thin cellulose fibers 108 (which may still contain residual solvent and water).
During or after initial formation of the individual cellulose fibers 108 from the extruded lyocell spinning solution 104, the cellulose fibers 108 are deposited on fiber support unit 132, which is here embodied as a conveyor belt with a planar fiber accommodation surface. The cellulose fibers 108 form a nonwoven cellulose fiber fabric 102 (illustrated only schematically in Figure 1). The nonwoven cellulose fiber fabric 102 is composed of continuous and substantially endless filaments or fibers 108.
Although not shown in Figure 1, the solvent of the lyocell spinning solution 104 removed in coagulation by the coagulation unit 128 and in washing in a washing unit 180 can be at least partially recycled.
While being transported along the fiber support unit 132, the nonwoven cellulose fiber fabric 102 can be washed by washing unit 180 supplying wash liquor to remove residual solvent and may then be dried. It can be further processed by an optional but advantageous further processing unit 134. For instance, such a further processing may involve hydro-entanglement, needle punching, impregnation, steam treatment with a pressurized steam, calendering, etc.
The fiber support unit 132 may also transport the nonwoven cellulose fiber fabric 102 to a winder 136 on which the nonwoven cellulose fiber fabric 102 may be collected as a substantially endless sheet. The nonwoven cellulose fiber fabric 102 may then be shipped as roll-good to an entity manufacturing products such as wipes or textiles based on the nonwoven cellulose fiber fabric 102.
As indicated in Figure 1, the described process may be controlled by control unit 140 (such as a processor, part of a processor, or a plurality of processors). The control unit 140 is configured for controlling operation of the various units shown in Figure 1, in particular one or more of the metering unit 113, the mixing unit 119, the fiber formation unit 124, the coagulation unit(s) 128, the further processing unit 134, the dissolution unit 120, the washing unit 118, etc. Thus, the control unit 140 (for instance by executing computer executable program code, and/or by executing control commands defined by a user) may precisely and flexibly define the process parameters according to which the nonwoven cellulose fiber fabric 102 is manufactured. Design parameters in this context are air flow along the orifices 126, properties of the coagulation fluid 106, drive speed of the fiber support unit 132, composition, temperature and/or pressure of the lyocell spinning solution 104, etc. Additional design parameters which may be adjusted for adjusting the properties of the nonwoven cellulose fiber fabric 102 are number and/or mutual distance and/or geometric arrangement of the orifices 126, chemical composition and degree of concentration of the lyocell spinning solution 104, etc. Thereby, the properties of the nonwoven cellulose fiber fabric 102 may be properly adjusted, as described below. Such adjustable properties (see below detailed description) may involve one or more of the following properties: diameter and/or diameter distribution of the fibers 108, amount and/or regions of merging between fibers 108, a purity level of the fibers 108, properties of a multilayer fabric 102, optical properties of the fabric 102, fluid retention and/or fluid release properties of the fabric 102, mechanical stability of the fabric 102, smoothness of a surface of the fabric 102, cross-sectional shape of the fibers 108, etc.
Although not shown, each spinning jet 122 may comprise a polymer solution inlet via which the lyocell spinning solution 104 is supplied to the jet 122. Via an air inlet, a gas flow 146 can be applied to the lyocell spinning solution 104. Starting from an interaction chamber in an interior of the jet 122 and delimited by a jet casing, the lyocell spinning solution 104 moves or is accelerated (by the gas flow 146 pulling the lyocell spinning solution 104 downwardly) downwardly through a respective orifice 126 and is laterally narrowed under the influence of the gas flow 146 so that continuously tapering cellulose filaments or cellulose fibers 108 are formed when the lyocell spinning solution 104 moves downwardly together with the gas flow 146 in the environment of the coagulation fluid 106.
Thus, processes involved in the manufacturing method described by reference to Figure 1 may include that the lyocell spinning solution 104, which may also be denoted as cellulose solution is shaped to form liquid strands or latent filaments, which are drawn by the gas flow 146 and significantly decreased in diameter and increased in length. Partial coagulation of latent filaments or fibers 108 (or preforms thereof) by coagulation fluid 106 prior to or during web formation on the fiber support unit 132 may also be involved. The filaments or fibers 108 are formed into web like fabric 102, washed, dried and may be further processed (see further processing unit 134), as required. The filaments or fibers 108 may for instance be collected, for example on a rotating drum or belt, whereby a web is formed.
As a result of the described manufacturing process and in particular the choice of solvent used, the fibers 108 have a copper content of less than 5 ppm and have a nickel content of less than 2 ppm. This advantageously improves purity of the fabric 102.
The lyocell solution blown web (i.e. the nonwoven cellulose fiber fabric 102) according to exemplary embodiments of the invention preferably exhibits one or more of the following properties:

(i) The dry weight of the web is from 5 to 300 g/m², preferably 10-80 g/m²
(ii) The thickness of the web according to the standard WSP120.6 respectively DIN29073 (in particular in the latest version as in force at the priority date of the present patent application) is from 0.05 to 10.0 mm, preferably 0.1 to 2.5 mm
(iii) The specific tenacity of the web in MD according to EN29073-3, respectively ISO9073-3 (in particular in the latest version as in force at the priority date of the present patent application) ranges from 0.1 to 3.0 Nm²/g, preferably from 0.4 to 2.3 Nm²/g
(iv) The average elongation of the web according to EN29073-3, respectively ISO9073-3 (in particular in the latest version as in force at the priority date of the present patent application) ranges from 0.5 to 100%, preferably from 4 to 50%.
(v) The MD/CD tenacity ratio of the web is from 1 to 12
(vi) The water retention of the web according to DIN 53814 (in particular in the latest version as in force at the priority date of the present patent application) is from 1 to 250%, preferably 30 to 150%
(vii) The water holding capacity of the web according to DIN 53923 (in particular in the latest version as in force at the priority date of the present patent application) ranges from 90 to 2000%, preferably 400 to 1100%.
(viii) Metal residue levels of copper content of less than 5 ppm and nickel content of less than 2 ppm, according to the standards EN 15587-2 for the substrate decomposition and EN 17294-2 for the ICP-MS analysis (in particular in the latest version as in force at the priority date of the present patent application).

Most preferably, the lyocell solution-blown web exhibits all of said properties (i) to (viii) mentioned above.
As described, the process to produce the nonwoven cellulose fiber fabric 102 preferably comprises:

(a) Extruding a solution comprising cellulose dissolved in NMMO (see reference numeral 104) through the orifices 126 of at least one jet 122, thereby forming filaments of lyocell spinning solution 104
(b) Stretching said filaments of lyocell spinning solution 104 by a gaseous stream (see reference numeral 146)
(c) Contacting said filaments with a vapor mist (see reference numeral 106), preferably containing water, thereby at least partly precipitating said fibers 108. Consequently, the filaments or fibers 108 are at least partly precipitated before forming web or nonwoven cellulose fiber fabric 102.
(d) Collecting and precipitating said filaments or fibers 108 in order to form a web or nonwoven cellulose fiber fabric 102
(e) Removing solvent in wash line (see washing unit 180)
(f) Optionally bonding via hydro-entanglement, needle punching, etc. (see further processing unit 134)
(g) Drying and roll collection

Constituents of the nonwoven cellulose fiber fabric 102 may be bonded by merging, intermingling, hydrogen bonding, physical bonding such as hydroentanglement or needle punching, and/or chemical bonding.
In order to be further processed, the nonwoven cellulose fiber fabric 102 may be combined with one or more layers of the same and/or other materials, such as (not shown) layers of synthetic polymers, cellulosic fluff pulp, nonwoven webs of cellulose or synthetic polymer fibers, bicomponent fibers, webs of cellulose pulp, such as airlaid or wetlaid pulp, webs or fabrics of high tenacity fibers, hydrophobic materials, high performance fibers (such as temperature resistant materials or flame retardant materials), layers imparting changed mechanical properties to the final products (such as Polypropylene or Polyester layers), biodegradable materials (e.g. films, fibers or webs from Polylactic acid), and/or high bulk materials.
It is also possible to combine several distinguishable layers of nonwoven cellulose fiber fabric 102, see for instance Figure 7.
The nonwoven cellulose fiber fabric 102 may essentially consist of cellulose alone. Alternatively, the nonwoven cellulose fiber fabric 102 may comprise a mixture of cellulose and one or more other fiber materials. The nonwoven cellulose fiber fabric 102, furthermore, may comprise a bicomponent fiber material. The fiber material in the nonwoven cellulose fiber fabric 102 may at least partly comprise a modifying substance. The modifying substance may be selected from, for example, the group consisting of a polymeric resin, an inorganic resin, inorganic pigments, antibacterial products, nanoparticles, lotions, fire-retardant products, absorbency-improving additives, such as superabsorbent resins, ion-exchange resins, carbon compounds such as active carbon, graphite, carbon for electrical conductivity, X-ray contrast substances, luminescent pigments, and dye stuffs.
Concluding, the cellulose nonwoven web or nonwoven cellulose fiber fabric 102 manufactured directly from the lyocell spinning solution 104 allows access to value added web performance which is not possible via staple fiber route. This includes the possibility to form uniform lightweight webs, to manufacture microfiber products, and to manufacture continuous filaments or fibers 108 forming a web. Moreover, compared to webs from staple fibers, several manufacturing procedures are no longer required. Moreover, nonwoven cellulose fiber fabric 102 according to exemplary embodiments of the invention is biodegradable and manufactured from sustainably sourced raw material (i.e. wood pulp 110 or the like). Furthermore, it has advantages in terms of purity and absorbency. Beyond this, it has an adjustable mechanical strength, stiffness and softness. Furthermore, nonwoven cellulose fiber fabric 102 according to exemplary embodiments of the invention may be manufactured with low weight per area (for instance 10 to 30 g/m²). Very fine filaments down to a diameter of not more than 5 µm, in particular not more than 3 µm, can be manufactured with this technology. Furthermore, nonwoven cellulose fiber fabric 102 according to an exemplary embodiment of the invention may be formed with a wide range of web aesthetics, for instance in a flat crispy film-like way, in a paper-like way, or in a soft flexible textile-like way. By adapting the process parameters of the described process, it is furthermore possible to precisely adjust stiffness and mechanical rigidity or flexibility and softness of the nonwoven cellulose fiber fabric 102. This can be adjusted for instance by adjusting a number of merging positions, the number of layers, or by after-treatment (such as needle punch, hydro-entanglement and/or calendering). It is in particular possible to manufacture the nonwoven cellulose fiber fabric 102 with a relatively low basis weight of down to 10 g/m² or lower, to obtain filaments or fibers 108 with a very small diameter (for instance of down to 3 to 5 µm, or less), etc.
Figure 2, Figure 3 and Figure 4 show experimentally captured images of nonwoven cellulose fiber fabric 102 according to an exemplary embodiment of the invention in which merging of individual fibers 108 has been accomplished by a corresponding process control. The oval markers in Figure 2 to Figure 4 show such merging regions where multiple fibers 108 are integrally connected to one another. At such merging points, two or more fibers 108 may be interconnected to form an integral structure.
Figure 5 and Figure 6 show experimentally captured images of nonwoven cellulose fiber fabric 102 according to an exemplary embodiment of the invention in which swelling of fibers 108 has been accomplished, wherein Figure 5 shows the fiber fabric 102 in a dry non-swollen state and Figure 6 shows the fiber fabric 102 in a humid swollen state. The pore diameters can be measured in both states of Figure 5 and Figure 6 and can be compared to one another. When calculating an average value of 30 measurements, a decrease of the pore size by swelling of the fibers 108 in an aqueous medium up to 47% of their initial diameter could be determined.
Figure 7 shows an experimentally captured image of nonwoven cellulose fiber fabric 102 according to an exemplary embodiment of the invention in which formation of two superposed layers 200, 202 of fibers 108 has been accomplished by a corresponding process design, i.e. a serial arrangement of multiple spinnerets. The two separate, but connected layers 200, 202 are indicated by a horizontal line in Figure 7. For instance, an n-layer fabric 102 (n≥2) can be manufactured by serially arranging n spinnerets or jets 122 along the machine direction.
Specific exemplary embodiments of the invention will be described in the following in more detail:

Nonwoven cellulose fiber fabric 102 according to an exemplary embodiment of the invention, for instance manufactured on the basis of the procedure described referring to Figure 1, may be provided with electromagnetic radiation diffusing particles 220 in a range between 0.1 mass % and 15 mass %, in particular in a range between 0.4 mass % and 5 mass %. Advantageously, the electromagnetic radiation diffusing particles 220 may be adhered or connected to the fibers 108. For example, the electromagnetic radiation diffusing particles 220 may be configured for diffusing electromagnetic radiation in the wavelength regime of visible light, i.e. having a wavelength in a range between 400 nm and 800 nm. The electromagnetic radiation diffusing particles 220 may substantially consist of titanium dioxide with diameters in a range between 70 nm and 3000 nm. The large majority of the electromagnetic radiation diffusing particles 220 may be in rutile state (compare Figure 9) for obtaining high stability and/or anatase state (compare Figure 10) for obtaining strong photocatalytic activity. Depending on the adjustment of the process parameters of the manufacturing method, it can be ensured that the electromagnetic radiation diffusing particles 220 are predominantly embedded within an interior of the fibers 108 and/or are attached to an exterior surface of the fibers 108. The electromagnetic radiation diffusing particles 220 may be provided with a refraction index of more than 1.5 at 600 nm. As a result of their electromagnetic radiation interaction properties the electromagnetic radiation diffusing particles 220 are configured so that the fabric 102 is opaque in a wet condition. In this context, it should be mentioned that nonwoven cellulose fiber fabric without electromagnetic radiation diffusing particles 220 may be optically transparent in a wet state which can be undesired for certain applications, for instance clothing. For instance, the electromagnetic radiation diffusing particles 220 have a substantially spherical shape which eases manufacturability and promotes an intimate connection between particles 220 and fibers 108.

By taking these measures, opacity of the fabric 102 may be ensured even when the fiber fabric 102 as such is optically transparent in a wet state of the fabric 102. However, presence of the electromagnetic radiation diffusing particles 220 such as titanium dioxide may ensure in particular visual opacity, whiteness and brightness of the fabric 102. More generally, by adjusting the properties of the electromagnetic radiation diffusing particles 220 (for instance in terms of material, size and/or concentration), the optical properties of the obtained fabric 102 may be fine-tuned.
Advantageously and as a consequence of the manufacturing procedure described herein, the fibers 108 may have an only very small content of certain heavy metals such as a copper content of less than 5 ppm and a nickel content of less than 2 ppm.
Figure 8 shows a diagram 250 illustrating a relation between a particle dimension D, plotted along an abscissa 252, and a relative light scattering capability S, plotted along an ordinate 254, of rutile-type titanium oxide electromagnetic radiation diffusing particles 220 of a nonwoven cellulose fiber fabric 102 according to an exemplary embodiment of the invention. Corresponding curves are plotted in Figure 8 for blue light (see reference numeral 256), for green light (see reference numeral 258), and for red light (see reference numeral 260). As can be taken from Figure 8, the scattering strength of the electromagnetic radiation diffusing particles 220 is particularly pronounced in a range between about 70 nm and about 3000 nm so that the implementation of particles 220 in a corresponding dimensional range is particularly efficient.
Figure 9 illustrates an elementary cell of rutile-type titanium oxide 222 used as electromagnetic radiation diffusing particles 220 of nonwoven cellulose fiber fabric 102 according to an exemplary embodiment of the invention. In Figure 9, oxygen is indicated with reference numeral 224, and titanium is indicated with reference numeral 226. Due to its pronounced scattering capability, stability and durability, rutile-type titanium oxide 222 is a particularly preferred material for the electromagnetic radiation diffusing particles 220.
Figure 10 illustrates an elementary cell of anatase-type titanium oxide 228 used as electromagnetic radiation diffusing particles 220 of nonwoven cellulose fiber fabric 102 according to another exemplary embodiment of the invention. Again, oxygen is indicated with reference numeral 224, and titanium is indicated with reference numeral 226. Anatase-type titanium oxide 228 is an appropriate alternative to the rutile-type titanium oxide 222, in particular when a pronounced photocatalytic activity of the fabric 102 is desired.
Figure 11 illustrates procedures carried out during executing a method of manufacturing nonwoven cellulose fiber fabric 102 with implemented electromagnetic radiation diffusing particles 220 according to exemplary embodiments of the invention. The upper illustration in Figure 11 (see A) shows a mixture of cellulose-based lyocell spinning solution 104 with electromagnetic radiation diffusing particles 220 immediately after extrusion and hence directly downstream of the nozzle or orifice 126. A further process flow indicated schematically with reference numeral 270 shows formation of fibers 108 by gas flow 146 (see Figure 1 and Figure 12) supported stretching only (see B).
Figure 12 illustrates a device 100 for manufacturing nonwoven cellulose fiber fabric 102 according to an exemplary embodiment of the invention which is specifically adapted for integrating electromagnetic radiation diffusing particles 220 in the nonwoven cellulose fiber fabric 102.
According to Figure 12, the device 100 is configured so that the gas flow 146 may be enriched with electromagnetic radiation diffusing particles 220 to thereby provide the fabric 102 with the electromagnetic radiation diffusing particles 220. For that purpose, a metering valve 234 is provided which connects a particle container 232 (containing electromagnetic radiation diffusing particles 220 such as titanium dioxide spheres) with a flow generation unit for generating the gas flow 146. The metering valve 234 is controlled by the control unit 140. Consequently, the gas flow 146 may be supplied with the added electromagnetic radiation diffusing particles 220 which come into interaction with strands of the lyocell spinning solution 104 extruded through the orifices 126. Thereby, the lyocell spinning solution 104 may be mixed in an adjustable way with the electromagnetic radiation diffusing particles 220, so that fibers 108 with attached and/or embedded particles 220 may be obtained.
According to Figure 12, the device 100 can be additionally or alternatively configured so that the lyocell spinning solution 104 itself is enriched with at least part of the electromagnetic radiation diffusing particles 220 prior to being supplied to the jets 122, i.e. upstream of the orifices 126. Thereby, it is also possible to provide the fabric 102 with the electromagnetic radiation diffusing particles 220 attached to and/or embedded in the fibers 108. This can be accomplished by providing a particle container 230 containing electromagnetic radiation diffusing particles 220 which can be mixed into the lyocell spinning solution 104 at the metering valve 119.
Beyond this, the coagulation fluid 106 may be enriched with electromagnetic radiation diffusing particles 220 stored in a further particle container 236 to thereby provide the fabric 102 with the electromagnetic radiation diffusing particles 220. The control unit 140 controls an amount of particles 220 added to the coagulation fluid 106 so as to connect particles 220 to the fibers 108 during coagulation.
More generally, an exemplary embodiment of the invention provides an embedding of electromagnetic radiation diffusing particles 220 in a nonwoven cellulose fiber fabric 102. Since a nonwoven cellulose fiber fabric 102 may be optically transparent when wet, the embedding of electromagnetic radiation diffusing particles 220 may provide a fabric 102 being opaque in all humidity states. What concerns conventional staple fibers, the high amount of free fiber ends may here function as scattering centers so that a corresponding fabric can be more opaque in all humidity states. However, with a fabric 102 according to an exemplary embodiment of the invention composed of substantially endless fibers 108 with extremely small amount of free fiber ends, the opacity in the wet state of the fabric 102 requires the added particles 220.
Electromagnetic radiation diffusing particles 220 having a high efficiency of scattering optical light have in many cases dimensions which are in the range of respirable particles (which may enter, as such, into the alveoles of the human body) and/or particles having a tendency to enter the blood circuit (i.e. entering the human organism). As a rule of thumb, particles smaller than 2.5 µm may have a strong tendency of entering the alveoles, and particles smaller than 100 nm may have the tendency of intruding into the organism. Thus, it is important to implement the particles 220 in the fabric 102 with a sufficiently low tendency of separating from the fibers 108 in order to obtain a fabric 102 which can be brought in contact with human beings. Referring to Figure 14, several examples for adjusting the process parameters of manufacturing the fabric 102 have been described by which it is possible to ensure such a strong adhesion of the particles 220 at and/or in the fibers 108. By taking this measure, even when fine dust powder particles 220 (for instance made of titanium dioxide) are integrated into the fabric 102, they can adhere sufficiently strong to the fibers 108 so that they do not have a pronounced tendency of being released from the fibers 108. In order to efficiently promote diffusing effects in the range of visible light, in particular particle dimensions in a range between 70 nm (or even 200 nm) and 3000 nm are particularly advantageous, since this results in pronounced diffraction of electromagnetic radiation as optical diffusion. In view of the foregoing, in particular a control of average particle diameter and/or control of a diameter distribution of a set of particles 220 is a powerful tool for precisely adjusting the optical properties of the fabric 102 according to an exemplary embodiment of the invention.
It has turned out that, when the dimensions of the electromagnetic radiation diffusing particles 220 are sufficiently small, they can be properly introduced in lyocell spinning solution 104 and can therefore be integrally embedded within the fibers 108 during the manufacturing process of the fabric 102 described above. At the same time, particles of such dimensions have strong diffusing properties in the optical regime (compare Figure 8). Too large particles 220 may also have the tendency of clogging the orifices 126 of the nozzles of device 100. Although additionally or alternatively, the particles 220 may also be added to the coagulation fluid 106 and may adhesively attach to the fibers 108, the percentage of the particles 220 being embedded in an interior of the fibers 108 (and being therefore less prone of being released from the fabric 102) is higher when the particles 220 are added to the lyocell spinning solution 104. In contrast to this, a relatively large percentage of the particles 220 adheres to an exterior surface of the fibers 108 when the particles 110 20 are added to the coagulation fluid 106 and/or to the gas flow 146. In view of these considerations, a dimensional range of the particles 220 between 70 nm and 3000 nm has turned out as preferred. It may be preferred that not more than 10% of the particles 220 has a diameter of smaller than 100 nm. It may also be advantageous that at least 90% of the particles 220 has a diameter of not more than 3000 nm, in particular not more than 1000 nm. The diameter or diameter distribution of the implemented electromagnetic radiation diffusing particles 220 may be controlled as a process parameter by control unit 140 for adjusting the optical properties of the manufactured fabric 102 and the adhesion force between particles 220 and fibers 108. However, it should be said that the addition of the particles 220 into one or both of the lyocell spinning solution 104 and the coagulation fluid 106 allows to obtain a fabric 102 with sufficiently strong adhesion of the particles 220 to the fibers 108 and with proper light diffusing properties.
In particular, it is possible to control, by the dimension of the particles 220, the frequency selection of the filtered (since reflected) electromagnetic radiation. For example, small particles 220 may allow to manufacture a nonwoven cellulose fiber fabric 102 being still optically transparent in a wet state while showing a proper filter effect and protection function with regard to ultraviolet radiation. On the other hand, it is also possible, with another configuration of the electromagnetic radiation diffusing particles 220 in fabric 102, to obtain an opacity over the entire visible range of light, which for instance may be advantageous for the example of wet T-shirts. In a nutshell, size and/or size distribution, material and concentration of the electromagnetic radiation diffusing particles 220 may be adjusted for adjusting the properties of the fabric 102 in terms of interaction with electromagnetic radiation.
On the other hand, certain electromagnetic radiation diffusing particles 220 (such as barium sulfate) have not only a light diffusing function, but additionally have an electromagnetic radiation absorbing function (in the given example in particular in the X-ray range).
More generally, an exemplary embodiment of the invention may implement electromagnetic radiation diffusing particles 220 in nonwoven cellulose fiber fabric 102 to thereby provide an electromagnetic radiation diffusing function in a first wavelength range and an electromagnetic radiation absorbing function in a second wavelength range, wherein the first wavelength range and the second wavelength range may be identical, may be completely different, or may overlap.
During the process of connecting the particles 222 to the fibers 108 of the fabric 102, the fiber formation process may not yet have already been completed. More specifically, this connection may be accomplished before completion coagulation and/or precipitation of the fibers 108 from the lyocell spinning solution 104. Advantageously, the adhesive strength between the particles 220 and the fibers 108 may be further reinforced during a shrinkage process and a drying process of the fibers 108 after coagulation or precipitation. As a result of a corresponding control of the process parameters of the manufacturing method, it is therefore possible to obtain an intimately connected particle-fiber fabric 102 in which the fiber 108 and the particles 220 do not tend to be separated from one another. Attaching and/or embedding the particles 222 on or in the fibers 108 during their formation allows a proper embedding and allows surrounding cellulose material to find a large number of adhesion points with regard to respective particles 220. By taking this measure, the amount of particles 220 to be added to the fabric 102 may be kept small, and at the same time an undesired release of the particles 220 from the fibers 108 may be efficiently prevented.
A further advantageous property of certain electromagnetic radiation diffusing particles 220 (such as titanium dioxide) is their photocatalytic activity. The latter can be further reinforced by the high surface/volume ratio of nanoparticles compared to microparticles. Thus, the particles 220 may be configured as nanoparticles. In this context, it has turned out that titanium dioxide may be more appropriate to be used for the electromagnetic radiation diffusing particles 221 in the anatase crystal state when strong photocatalytic properties are desired. In the presence of ultraviolet radiation, anatase type titanium dioxide can form radicals from water or air which are capable of (in particular oxidatively) decomposing (in particular organic) harmful substances. Such an additional functionalization of nonwoven cellulose fiber fabric 102 with electromagnetic radiation diffusing particles 220 having a photocatalytic activity (such as anatase type titanium dioxide) may be particularly advantageous according to an exemplary embodiment of the invention.
According to an exemplary embodiment of the invention, a washing procedure of washing the fiber fabric 102 with the attached and/or embedded electromagnetic radiation diffusing particles 220 in washing unit 180 may selectively remove weakly attached particles 220 from the fiber 108. By taking this measure, it can be ensured that the readily manufactured fabric 102 comprises only particles 220 being strongly bonded to the fibers 108. This prevents an undesired release of particles 220 from the fibers 108 during use of the fabric 102 by a user.
It is also possible to merge fibers 108 prior to and/or during coagulation to additionally promote particles 220 to remain within the fabric 102 by reducing the total fiber surface in the so produced fabric 102.
In yet another exemplary embodiments, the electromagnetic radiation diffusing particles 220 can be coated with an additional material, in order to provide a certain additional function. Such an additional function may be an improved dispersion property and/or an improvement of the photostability. Moreover, the particles 220 may be coated so that they are not chemically attacked by the dope or lyocell spinning solution 104.
In still other embodiments, large electromagnetic radiation diffusing particles 220 (such as titanium dioxide particles) may be embedded in the nonwoven cellulose fiber fabric 102. By taking this measure it can be ensured that sufficient particles 220 are also present at the surface of the fibers 108. As a result, the photocatalytic effect of titanium dioxide may be used particularly efficiently. For instance, this effect can be applied for antibacterial, taste neutralizing and/or cleaning functions. The respective effect can be reinforced or even optimized by correspondingly adjusting an amount of the particles 220, a dimension of the particles 220, a surface positioning of the particles 220, etc. Since the particles 220 are only active when they are present at the surface of the fibers 108, in particular for making use of the effects of such a functionalization, the addition of the particles 222 to the gas flow 146 and/or to the coagulation fluid 106 may be advantageous.
In yet another embodiment, the manufactured fabric 102 with the surface attached and/or embedded electromagnetic radiation diffusing particles 220 may be used for providing an ultraviolet protection for products such as medical bandage or surgical dressing, or for smoke masks. At the same time, an optical diffusing function may be realized (so that a wound covered by the fabric 102 does not become visible in the wet state).
In still another embodiment, the manufactured fabric 108 may be used for an X-ray protection product, for instance for medical clothing or cloths with X-ray protection function.
In still another embodiment, the manufactured fabric 108 may be used for surgical pads or cloths which can be detected easily by X-ray analysis.
Summarizing, in particular one or more of the following adjustments may be made according to exemplary embodiments of the invention:

a low homogeneous fiber diameter may allow to obtain a high smoothness of the fabric 102
multilayer fabric 102 with low average fiber diameters may allow to obtain a high fabric thickness at a low fabric density
equal absorption curves of the functionalized layers can allow to obtain a homogeneous humidity and fluid take up behavior, as well as a homogenous behavior in terms of fluid release
the described connection of layers 200, 202 of fabric 102 allows to design products with low linting upon layer separation
it is also possible to differently functionalize single layers 200, 202 so that products with anisotropic properties are obtained (for instance for wicking, oil accommodation, water accommodation, cleanability, roughness).

Finally, it should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be capable of designing many alternative embodiments without departing from the scope of the invention as defined by the appended claims. In the claims, any reference signs placed in parentheses shall not be construed as limiting the claims. The words "comprising" and "comprises", and the like, do not exclude the presence of elements or steps other than those listed in any claim or the specification as a whole. The singular reference of an element does not exclude the plural reference of such elements and vice-versa. In a device claim enumerating several means, several of these means may be embodied by one and the same item of software or hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

A nonwoven cellulose fiber fabric (102), in particular directly manufactured from lyocell spinning solution (104), wherein the fabric (102) comprises a network of substantially endless fibers (108) and at least 0.1 mass % electromagnetic radiation diffusing particles (220) connected to the fibers (108).
The fabric (102) according to claim 1, wherein the fabric (102) comprises not more than 15 mass % electromagnetic radiation diffusing particles (220), in particular not more than 4 mass % electromagnetic radiation diffusing particles (220).
The fabric (102) according to claim 1 or 2, comprising at least one of the following features:
wherein the electromagnetic radiation diffusing particles (220) are configured for diffusing electromagnetic radiation within at least one wavelength range selected from a group consisting of visible light, infrared light, ultraviolet light, and X-ray light;

wherein the electromagnetic radiation diffusing particles (220) comprises at least one of the group consisting of silicates, magnesium oxide, magnesium hydrosilicate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, titanium dioxide, barium sulfate, calcium carbonate, boron nitride, silicon dioxide, and zinc oxide.
The fabric (102) according to any of claims 1 to 3, wherein a number of at least 80% of the electromagnetic radiation diffusing particles (220) have a diameter of at least 70 nm, in particular of at least 100 nm, more particularly in a range between 70 nm and 3000 nm, preferably in a range between 100 nm and 2000 nm.
The fabric (102) according to any of claims 1 to 4, wherein the fibers (108) have a copper content of less than 5 ppm and/or have a nickel content of less than 2 ppm.
The fabric (102) according to any of claims 1 to 5, wherein a number of at least 80% of the electromagnetic radiation diffusing particles (220) are in rutile state and/or anatase state.
The fabric (102) according to any of claims 1 to 6, comprising at least one of the following features:
wherein at least part, in particular a number of at least 50%, more particularly a number of at least 90%, of the electromagnetic radiation diffusing particles (220) are embedded in an interior of the fibers (108);

wherein at least part, in particular a number of at least 50%, more particularly a number of at least 90%, of the electromagnetic radiation diffusing particles (220) are attached to a surface of the fibers (108);

wherein at least part, in particular a number of at least 50%, more particularly a number of at least 90% of the electromagnetic radiation diffusing particles (220) have a substantially spherical shape;

wherein the electromagnetic radiation diffusing particles (220) have a refraction index of more than 1.5.
The fabric (102) according to any of claims 1 to 7, wherein the electromagnetic radiation diffusing particles (220) are configured so that the fabric (102) is opaque in a wet condition of the fabric (102).
The fabric (102) according to any of claims 1 to 8, wherein at least a part of the electromagnetic radiation diffusing particles (220) is functionalized, in particular is photocatalytically active.
A method of manufacturing nonwoven cellulose fiber fabric (102) directly from lyocell spinning solution (104), wherein the method comprises
extruding the lyocell spinning solution (104) through at least one jet (122) with orifices (126) supported by a gas flow (146) into a coagulation fluid (106) atmosphere to thereby form substantially endless fibers (108);
collecting the fibers (108) on a fiber support unit (132) to thereby form the fabric (102);
adjusting process parameters so that the fabric (102) comprises at least 0.1 mass % electromagnetic radiation diffusing particles (220) connected to the fibers (108).
The method according to claim 10, comprising at least one of the following features:
wherein at least part of the electromagnetic radiation diffusing particles (220) operatively interacts with the lyocell spinning solution (104) prior to completing coagulation;

wherein the gas flow (146) is enriched with at least part of the electromagnetic radiation diffusing particles (220) to thereby provide the fabric (102) with the electromagnetic radiation diffusing particles (220);

wherein the coagulation fluid (106) is enriched with at least part of the electromagnetic radiation diffusing particles (220) to thereby provide the fabric (102) with the electromagnetic radiation diffusing particles (220);

wherein the lyocell spinning solution (104) is enriched with at least part of the electromagnetic radiation diffusing particles (220) upstream of the orifices (126) to thereby provide the fabric (102) with the electromagnetic radiation diffusing particles (220);

wherein the collected fibers (108) are made subject to a washing procedure washing out electromagnetic radiation diffusing particles (220) from the fabric (102) which are only weakly connected to the fibers (108).
The method according to claim 10 or 11, wherein the method further comprises further processing the fibers (108) and/or the fabric (102) in situ after collection on the fiber support unit (132), in particular by at least one of the group consisting of hydro-entanglement, needle punching, impregnation, steam treatment with a pressurized steam, and calendering.
A device (100) for manufacturing nonwoven cellulose fiber fabric (102) directly from lyocell spinning solution (104), wherein the device (100) comprises:
at least one jet (122) with orifices (126) configured for extruding the lyocell spinning solution (104) supported by a gas flow (146);

a coagulation unit (128) configured for providing a coagulation fluid (104) atmosphere for the extruded lyocell spinning solution (104) to thereby form substantially endless fibers (108);

a fiber support unit (132) configured for collecting the fibers (108) to thereby form the fabric (102);

a control unit (140) configured for adjusting process parameters so that the fabric (102) comprises at least 0.1 mass % electromagnetic radiation diffusing particles (220) connected to the fibers (108).
A method of using a nonwoven cellulose fiber fabric (102) according to any of claims 1 to 9 for at least one of the group consisting of a wipe, a dryer sheet, a filter, a hygiene product, a medical application product, a geotextile, agrotextile, clothing, a product for building technology, an automotive product, a furnishing, an industrial product, a product related to beauty, leisure, sports or travel, and a product related to school or office.
A product or composite, comprising a fabric (102) according to any of claims 1 to 9.