EP2616580A1 - Highly functional spunbonded fabric made from particle-containing fibres and method for producing same - Google Patents

Abstract

The invention relates to a highly functional spunbonded fabric made from fibres based on non-fusible polymers, which contain one or more functional additives. The fibres are interwoven and interlocked, are of different lengths having aspect ratios above 1.000 and form a firm fleece composite. Said fibres have a mean diameter of 0.1 to 500 micrometres and diameter variations within a fibre and/or among each other of at least 30%. In addition to the non-fusible polymers, the fibres contain, based on the total weight thereof, more than 40 wt % of functional additives in solid and/or liquid form, wherein the functional additives are finely distributed in the fibres. The spunbonded fabric is produced from a spinning solution that contains the non-fusible polymer dissolved in a direct solvent, and at least one functional additive. The spinning solution is pressed out of a spinneret, and the resulting polymer strands are drawn in the longitudinal direction to form filaments or fibres, stabilised and laid down to form a fleece fabric. The spunbonded fabrics can be used, for example, to produce clothing, technical textiles or as filters.

Description

 Highly functional spunbonded nonwoven made of particle-containing fibers and process for the production

The invention relates to highly functional spunbonded nonwovens as textile fabrics which can be produced directly from dissolved polymers by means of known spunbonding processes and which are constructed from fibers filled with liquid and / or solid functional additives. The fibers consist of more than 40 wt.%, Based on the total weight of the fibers, from functional additive, their average fiber diameter is 0.1 to 500 microns and the diameter variations within a fiber or each other is at least 30%. The spunbonded fabric is characterized by high functionality ■ due to very high concentrations of functional additives and can be used in a variety of ways, for example as interlining material, for hygiene applications, for wound dressings, as support materials, as construction and transport material, as cosmetic material or as filter.

Filled textile fabrics, e.g. those with thermo-regulating, antimicrobial or absorbing properties are already known.

As far as textile surfaces have been described, the materials hitherto used in the prior art are structures which have been processed into a textile surface after the production of functional fibers by at least one additional process step and / or contain only small amounts of functional particles. For example, DE 10 2008 045290 A1 discloses fibers from which textiles, wound dressings, filters, etc. are then produced. The additive components are limited exclusively to zinc white (ZnO and ZnS), wherein their proportion is limited to a maximum of 30% and particle sizes are smaller than 15 μπι. It is mentioned that for

CONFIRMATION COPY Fleece applications, the particle content may also be higher, but there is no teaching taught how such nonwovens are produced. The aim was not a functional nonwoven with high particle content, but washable and dyeable bactericidal bodies / fibers with controlled release of the active ingredients with prescribed washing permanence.

Often, thermoplastically processable polymers are used as carrier material whose melts can be processed einemμ a spunbonded, for example, in EP 1 199 393 A2. This is a spunbond made of thermoplastic polymers with hydrophobic additives. The aim is an enrichment of the hydrophobic additives on the fiber surface. This is achieved by the fact that the fiber is warped by the air flow so far that the mean fiber diameter is equal to the particle diameter or is reduced to at most half of the particle diameter. The proportion of asterbatches with the additives is between 10 and 20 wt .-% and may not be higher, so as not to affect the further processing to roof sheeting or use in sanitary napkins.

Particle-containing filaments or fibers can not be stably spun in a very high proportion of functional particles from 40% in normal filament or fiber spinning processes, since frequent breaks would result.

In various areas of the textile industry, there is a high demand for fiber materials with functional added value for the end user, which should also be inexpensive to produce and easy to process. Areas of application of such fiber materials are, for example, in the clothing industry as an insert material, in technical textiles, for example hygiene applications, for wound dressings, as support materials, as construction and transport material, as cosmetic material. al, or as a filter, for example for the filtration of Abwas ^¬ water or air and retention of air and water ingredients.

Sheets with functional additives can in principle either by the area of formation along a textile value chain or web formation each consist provided with functional additives, fibers that produce coating flat textile structures with the additive dispersions or the incorporation of solid or liquid functional additives in already he ^¬ witnessed nonwoven structures.

Fibers with a content of functional additives of more than 40% by weight can not be stably spun in normal fiber spinning processes, since frequent fiber breaks are the result. Although this disadvantage can be partially compensated by the use of functional fibers which are produced by solution spinning processes, the downstream textile surface forming processes also require at least one additional processing step in each case.

So far as the functional textile surfaces have been described, the materials hitherto produced in the prior art are structures that have been processed into a textile surface after a separate production of functional fibers by at least one additional process step and / or only small amounts Functional particles include. Due to the separate nonwoven production process, the highly filled fibers are additionally stressed and thereby damaged and only meet lower quality requirements in terms of functionality or mechanical resistance.

Aim of the present invention is a versatile sheet of particulate filaments and fibers having high functional utility for various applications. depending on the nature of the functional particles to provide, wherein the particulate filaments or fibers consist of more than 40 wt .-% of functional additives and have an average diameter of 0.1 to 500 microns. The fabrics are said to have already reached such a level of stability immediately after being deposited that they are suitable for further processing or for direct use. Due to the high content of functional additives, these fabrics should have such functional properties as are otherwise achieved only by additional process steps such as coating or surface finishing.

These objects are achieved according to the invention in that directly in the spinning process a highly functional textile fabric is continuously produced from a solution of non-meltable polymers doped with one or more functional additives in direct solvent with the aid of a spunbonding process. Surprisingly, textile fabrics with more than 40% by weight of additive content can be produced safely and reproducibly without additional process steps which have permanent functionality over the entire life cycle of the textile fabric. It has likewise been found that the nonwoven fibers according to the invention have diameter fluctuations within a fiber or of at least 30% with respect to one another and thus surprisingly have a high self-binding capacity due to entanglements and entanglements.

The present invention accordingly provides a highly functional spunbonded web of non-meltable polymer-based fibers containing one or more functional additives characterized in that the fibers are intertwined and entangled, have a different length with aspect ratios greater than 1,000 and form a strong nonwoven composite, wherein the fibers form a middle 0.1 to 500 microns diameter diameter and within a fiber and / or with each other of at least 30% and the fibers in addition to the non-meltable polymer more than 40 wt .-%, based on the total weight of the fibers, of functional additives in solid and / or liquid form, which are finely dispersed in the fibers

The textile fabrics which can be used for various fields of application, depending on the type of functional additives, are composed of additives containing more than 40% by weight and up to 96% by weight, optionally even more, in each case based on the total weight of the fibers, of functional additive contained and have a mean diameter 0.1 to 500 microns. Preferably, the proportion of functional additives is more than 40 wt .-% up to 90 wt .-%, based on the total weight of the fibers.

The incorporated and permanent functions of the additives range from, for example, electrically conductive, absorbing, ion-exchanging, antibacterial, temperature-regulating to flame-retardant, abrasive or caring or combinations thereof.

The functional additives are, in particular, activated carbon, superabsorbents, ion exchange resins, PCM, metal oxides, flame retardants, abrasives, zeolites, sheet silicates, such as bentonites, or modified sheet silicates, cosmetics or mixtures thereof. Also liquid lipophilic substances, such as paraffins, waxes or oils, can be introduced as a functional additive. In addition, one or more component (s) can be introduced in lower concentrations, for example nanosilver or dyes or even active substances, for example pharmaceutical substances or insecticides. The volume fraction of the functional additives (in the context of the present invention also referred to as functional particles or functional materials) in the spinning mixture is preferably chosen such that it makes up the main volume component in the non-woven air-moist filaments or fibers with more than 50%. In a particular embodiment, in which the diameter of the Funkt onspartikel is about 1/4 of the average filament or fiber diameter of the air-damp spunbonded fabric, it is achieved that the individual particles in the filaments or fibers have points of contact and so the functional properties can train in an advantageous manner.

The production of additive-containing fabrics from particle-containing filaments or fibers takes place by a spunbonding process. A doped polymer-containing spinning solution is used in the fiber-forming process, wherein the direct solvent is preferably an aprotic solvent. Particularly suitable as direct solvents, especially for cellulose, are N-methylmorpholine N-oxide or N-ethyl-morpholine N-oxide monohydrate, ionic liquids, such as 1-ethyl-3-methylimidazolium acetate, Ethyl-l-methylimidazolium chloride or 3-butyl-l-methylimidazolium chloride, dimethylformamide, dimethylacetamide or dimethyl sulfoxide mixed with lithium chloride or NaOH-thiourea water or, if appropriate, also mixtures thereof. The spinning solution with the functional particles and the dissolved polymer is extruded, wherein the nozzle bores have a diameter of 0.1 to 1.1 mm, preferably of 0.3 to 0.7 mm.

The strands thus generated are immediately after leaving the nozzles by its own weight and / or an obliquely acting from behind airflow whose intensity is adapted to the reduced by the functional particles thread drawability of the spinning mixture, within a short distance in longitudinal direction tion to filaments and fibers with aspect ratios greater than 1,000, preferably greater than 5,000 and more preferably greater than 40,000, tapers. The resulting fiber cracks do not lead to a termination of the process and do not adversely affect the process of web formation. They lead to fibers of different lengths and varying diameters being present in a nonwoven. The fibers are subsequently stabilized in their shape (during the transition into the stress-free space) before the onset of longitudinal relaxation. This occurs by transferring the solution state of the polymer into an at least partially undissolved state, either by evaporation of the solvent in the tempered air stream or by means of a stream of fine droplets, in particular of water or an aprotic liquid, by gelling and possibly possible replacement of the solvent. After reaching a bonding-free state, the fibers or filaments are deposited on a wire belt or a screen drum to form a nonwoven, which may also be layered, and compressed by suction. The solvent-enriched excess water is separated off, the remaining solvent rinsed by washing several times and then optionally the resulting nonwoven can be dried, wherein the functional particles in the nonwoven filaments and / or fibers by the taking place swelling of the polymer property determining mutually reinforced touch and connect.

The directly dissolved and the particle-binding polymer is a non-melting polymer, ie a polymer in which the softening point is above the decomposition point. It is preferably a member of the group of natural polymers, for example the polysaccharides, particularly preferably cellulose, the polysaccharide derivatives or the proteins or protein derivatives and / or from the group of solution-formable synthetic polymers, for example polyacrylonitrile, polyvinyl alcohol. hol, polyethylene oxide, polysulfone, meta-aramid or their copolymers.

The wet spunbonded fabric obtained in this way can be consolidated, finished and shaped by textile processes (needle punching, hydroentanglement, chemical bonding), the solidification and refinement of the nonwoven fabric being able to take place before or after drying. Aftertreatment by, for example, aviva- gens, impregnations or with ionic active substances may follow.

A spunbond web is understood to mean a web of fibers and continuous fibers laid down directly in random orientation after the extrusion, in which case it is also possible to lay several layers one above the other. The mixture of fibers and continuous fibers is caused by fiber breaks after the nozzle, resulting from the high particle content, but do not lead to an interruption of the process. In addition, according to the method of the invention, the spunbonded nonwoven not only consists of fibers of different lengths, but the fibers themselves have different fiber thicknesses over their length or with each other. The fiber thickness is determined by various factors, such as the concentration of the solution, the rate of blowing, the type of polymer, the particle size, as well as interaction of the additives to other components of the solution and content of additives. When filing entangled and entangled fibers and filaments form, which form a solid nonwoven composite. Characteristic features are the irregularities in the mean diameter of the fibers due to the high particle content, the size of the particles and the fiber breaks, which are visually very easily discernible under a microscope.

The advantage of producing the sheet from solutions of polymers in comparison with the production from polymer melts is that the particle content is much higher can, since in addition to the polymer and additive, the solvent is present in the starting solution, which is then removed at a later date. It is exploited that the cohesive forces are so great that it rarely breaks down, but at the same time the network of the dissolved polymer retains its sliding action so that the particles can slide off each other during extrusion and drawing. In addition, various gel states of the fibers and filaments that result from the replacement of the solvent with water can be exploited for further processing.

The highly functional spunbonded nonwoven has a basis weight of 2 to 1000 g / m ² , preferably of 5 to 500 g / m ² and a thickness of 0.01 to 20 mm, preferably from 0.05 to 5 mm. It has incorporated and permanent additional functions, such as electrically conductive, absorbent, ion-exchanging, antibacterial, temperature-regulating, flame-retardant, abrasive, caring or combinations thereof.

In a particular embodiment, particulate pore formers, for example Glauber's salt, can be integrated into the polymer solution. In the produced spunbonded fabric, the pore formers then lead, during the washing process, to a spunbonded web of highly porous fibers and filaments, which have a much larger surface area in comparison with area-like sponges.

The use of a highly functional spunbond web of particulate filaments or fibers ranges from clothing materials, such as heat-trapping or drug release liners, to technical textiles having high functional utility for various applications - depending on the type of functional particles, for example for hygiene applications, as wound dressings, as support materials for active substances or as support materials in composites, as Construction and transport material, as a cosmetic material or as a filter, for example for the filtration and binding of air and water ingredients such as phosphates, nitrates and ammonium-nitrogen compounds. Due to the special characteristics of the functional properties, due to the high concentration of additives, these nonwovens are also suitable for layered composites with other fabrics. This can happen by producing the highly functional spunbonded fabric on another, already introduced fabric during spunbonding production.

The following examples serve to illustrate the invention. Percentages are to be understood as weight percentages unless otherwise stated or immediately apparent from the context.

(Comparative) Example 1:

In 1.5 kg of a 9% strength cellulose solution in N-methylmorpholine N-oxide monohydrate (NMMO monohydrate), 0.1 kg of a ground ion exchange resin (strongly basic anion exchanger) with a particle diameter of D ₉₉ = 14, Dispersed 8 ym and homogenized at 90 ° C for 30 minutes. The spinning solution was then fed by means of a gear spinning pump at 95 ° C a spinneret (1200 holes with a diameter of 0.3 mm) and spun. However, a secure deformation over an air gap (1 = 10 mm) was not possible, it came at the nozzle exit to bonding of the exiting solution jets. Some of the resulting fiber cable pieces were completely freed of solvent and cut, as far as possible, to a staple length of 40 mm, with the described bonds sorted out as far as possible. The fibers were treated with a 1% sodium chloride solution and dried at 55 ° C to constant weight. A secondary spinning to the yarn was not possible. Fleece formation was only conditionally possible. lent, whereby a large number of short fibers and extreme shortening of the fibers was observed. The irregular loose fleece sections could not be further processed or used. A consolidation by needling for Sta stabilization was not possible because the fleece was completely destroyed and fell apart.

Example 2:

A cellulose solution prepared according to Example 1 was solidified by means of an el-blown spinning process (solution blowing) at a solution temperature of 95 ° C, blowing with 80 ° C warm air and spraying with a water mist directly at the exit of the nozzle blowing unit and depositing on a Sieve belt deformed to a direct web. The deformation ^{^} process was stable and the nonwoven fabric was obtained after complete extraction of the solvent and drying at 60 ° C without any difficulty as the ion exchanger non-woven can be used. The functional fleece was mechanically stable enough to be cut to size and fed into the water treatment plant. An additionally performed moderate needling and thus further compaction was also possible without the fleece was destroyed.

Claims

Claims: 1. Highly functional spunbonded non-meltable polymer fiber-containing fibers containing one or more functional additives, characterized in that the fibers are intertwined and entangled, have a different length with aspect ratios greater than 1,000 and form a strong nonwoven composite, wherein the Fibers have a mean diameter of 0.1 to 500 micrometers and variations in diameter within a fiber and / or with each other of at least 30% and wherein the fibers in addition to the non-meltable polymer more than 40 wt .-%, based on the total weight of the fibers, of functional additives in solid and / or liquid form, which are finely dispersed in the fibers. 2. Spunbonded nonwoven according to claim 1, characterized in that the functional additives are solid or liquid, preferably lipophilic substances, particularly preferably activated carbon, superabsorbents, ion exchange resins, piezoelectric materials, phase change materials, especially paraffins, metal oxides, flame retardants, abrasives, Zeolites, phyllosilicates, modified phyllosilicates and / or cosmetics. 3. Spunbonded nonwoven according to claim 1 or 2, characterized in that the functional additives binding non-meltable polymer is a natural polymer, preferably a polysaccharide, more preferably cellulose, a polysaccharide derivative and / or a protein or protein derivative and / or that a solution-formable synthetic polymer, preferably polyacrylonitrile or a copolymer with acrylonitrile units, polyvinyl alcohol, polyethylene oxide, polysulfone and / or meta-aramid. 4. spunbonded nonwoven according to at least one of the preceding claims, characterized in that it comprises a layered structure of self-entangled mechanically connected filaments or fibers. 5. Spunbonded nonwoven according to at least one of the preceding claims, characterized in that it has a basis weight of 2 to 1000 g / m ² , preferably from 5 to 500 g / m ² . 6. spunbonded fabric according to any one of the preceding claims, characterized in that it has a thickness of 0.1 to 20 mm, preferably from 0.5 to 5 mm. 7. spunbonded nonwoven according to one or more of claims 1 to 6, characterized in that the de proportion of the functional additives is more than 40 wt .-% up to 96 wt .-%, optionally even more, based on the total weight of the fibers. Process for the preparation of a highly functional spun egg according to one or more of claims 1 to 7, characterized in that  - The spinning solution, consisting of one or more functional additives, solvent and in this dissolved polymer from the spinneret is pressed, wherein  the nozzle bores have a diameter of 0.1 to 1.5 mm, preferably 0.3 to 0.7 mm, - The polymer strands thus formed immediately after leaving the nozzles by own weight and / or an obliquely acting from above blowing, the intensity of which is adapted to the reduced by the functional additives Fadenziehvermögen the spinning mixture, are warped within a short distance in the longitudinal direction to filaments and / or fibers . - These below, when moving into the tension-free space, even before the onset of longitudinal relaxation, by means of a stream of tempered air and / or fine water droplets are stabilized by consolidation or gelation and partial replacement of the solvent by water in their form, the stabilization locally more or less offset from the nozzle exit can be done and so nonwovens are obtained with more or less bonded gel fibers can,  After reaching this stabilized state, these are laid down on a sieve belt or a sieve drum to form a nonwoven, the remaining solvent is rinsed out by repeated washing and the nonwoven can then optionally be dried. 9. The method according to claim 8, characterized in that the solvent comprises an aprotic solvent or consists thereof. 10. The method according to claim 8 or 9, characterized in that the highly functional spunbonded further consolidated by textile processes, finished and deformed and that the solidification and refinement of the web before or after drying is carried out. 11. The method according to one or more of claims 8 to 10, characterized in that the highly functional spunbonded stabilized by needling or hydroentanglement and / or additionally chemically crosslinked. 12. Use of a highly functional spunbonded nonwoven fabric comprising functional additive-containing filaments or fibers according to claims 1 to 7 for the production of clothing materials, in particular interlining materials, and of technical textiles, in particular for hygiene applications, for wound dressings, as carrier materials for active substances or carrier materials for composites, as Construction and transport material, as cosmetic beautiful material or as a filter, with high functional value for various applications - depending on the type of functional additives.