Coagulable polymer solution containing aromatic high-performance polymers dissolved therein, a process for obtaining the same and their use

Description

[0001] The invention relates to a wet and dry-wet coagulable, in particular wet and dry-wet spinnable polymer solution based on ionic liquids and containing aromatic high-performance polymers dissolved therein in the form of m-aramids, aromatic polyamideimides, aromatic polyimides as poly(4,4-diphenylmethane-co-toluylenebenzophenonetetracarboxylimide) and / or polybenzimidazole, which were dissolved out with the ionic liquid from pollutant-containing textile fiber materials, in particular from textile fiber waste, a process for producing this polymer solution by processing textile fiber materials containing aromatic high-performance polymers, in particular for obtaining the designated coagulable polymer solution, and the use thereof for producing fibers by wet or dry-wet spinning as well as films, membranes and coatings.

[0002] These polymers are considered high-performance polymers. As fibers, they have gained great importance in the textile industry in areas where high demands are placed on the flame resistance of a textile, as they are considered inherently flame-retardant. This characteristic is generally characterized by the so-called Limiting Oxygen Index (LOI). This is at least 28 for inherently flame-retardant fibers.

[0003] Aromatic polyamides, also known as aramids for short, can generally be divided into meta-aramids and para-aramids. The term m-aramid indicates that the linkage within a chain between the individual aromatic rings is in the meta position, unlike p-aramid, which is in the para position. Meta-aramids include, in particular, poly(m-phenylene isophthalamide), and para-aramids include, in particular, poly(p-phenylene terephthalamide). Particularly well-known are the fibers marketed by DuPont under the NOMEX® brand: These are heat- and flame-resistant fibers used in protective clothing materials, protective clothing, electrical insulation paper, and other high-performance applications to protect people and the processes they perform.NOMEX ®< is an inherently flame-resistant fiber that has high temperature resistance and does not melt, does not drip, and supports combustion in air. It is available as paper, felt, fabric and fiber. The well-known NOMEX ®< fibers are essentially based on meta-aramid, while DuPont also markets para-aramids under the brand name KEVLAR ®<. Available on the market, for example, NOMEX T-450 ®< is a staple fiber made of 100% meta-aramid, NOMEX T-455 ®< , consisting of a staple fiber blend of 95% NOMEX ®< and 5% KEVLAR ®< , and NOMEX T-462 ®< , containing a fiber blend of 93% NOMEX ®< , 5% KEVLAR ®< and 2% polyamide-coated carbon fiber. Furthermore, fibers made of meta- and para-aramid are produced in large quantities in Asia.

[0004] Polyamideimides are generally obtained by reacting phthalic or trimellitic anhydride with aromatic diisocyanates, such as toluene diisocyanate or p,p'-dichlorodiphenyl ethers. According to the Official Journal of the European Union of October 28, 2011, some polyamideimide fibers, such as Kermel® fiber, are also classified as aramids.

[0005] A polyimide fiber developed by Lenzing AG and currently marketed by Evonik GmbH under the brand name P 84 ® (consisting of poly(4,4'-diphenylmethane-co-toluenebenzophenonetetracarboxyimide)). Polybenzimidazole (PBI) is obtained by the condensation of diphenyl isophthalate and tetraaminobiphenyl.

[0006] The above-mentioned high-performance polymers or fiber polymers made of aramid, polyimide, and polybenzimidazole are always spun from solution. With the exception of para-aramid, which is spun from concentrated sulfuric acid, dimethylformamide (DMF) or dimethylacetamide (DMA) are usually used as solvents. With the exception of PBI, which is spun into fibers using a dry spinning process, spinning of these polymer solutions is usually carried out in a wet spinning process using suitable spinnerets immersed in a coagulating bath, during which the fiber polymer coagulates. Drawing and drying result in consolidation into a fiber with suitable mechanical properties. For the state of the art regarding synthesis, solution preparation, and spinning, see, for example, HF Mark, NM Bikales, C. Ovrberger, G. Menges, JI Kroschwitz (eds): Encyclopedia of Polymer Science and Engineering, Vol. 11, John Wiley & Sons, Inc., 1988.

[0007] The spinning solvents mentioned above, dimethylformamide and dimethylacetamide, are highly questionable from a toxicological perspective: DMF is now listed as a CMR substance (carcinogenic, mutagenic, toxic to reproduction). The handling of DMF on an industrial scale is therefore highly problematic. Even substances containing more than 1% DMF fall into the CMR labeling category. DMA is subject to REACh labeling requirements and poses serious concerns regarding its toxicity.

[0008] Furthermore, dimethylimidazolidinone, DMI for short or dimethylethyleneurea as a synonym, is sometimes used in the production of high-performance fibers, which has at least as critical a potential for organisms as DMF or DMA.

[0009] It is known that fibers derived from aromatic high-performance polymers and spun from DMF, DMA, or DMI still contain harmful residual amounts of the spinning solvent. These remaining toxic pollutants force manufacturers to undergo intensive and expensive post-treatment of the fibers to reduce the residual content to a tolerable level. The necessary investments in complex exhaust air and wastewater treatment measures during production make the respective fiber polymers less competitive compared to other high-performance fibers, which are obtainable, for example, through thermoplastic production.

[0010] Another problem arises in the recycling of fiber waste derived from the aforementioned high-performance polymers and their associated pollutants. Recycling through purely mechanical processing of the fiber waste, for example, to produce fiber flakes or reusable nonwoven products, is not possible because the resulting products would then also be contaminated with residual solvents. At the same time, mechanical processing of fiber blends containing high-strength fibers, such as para-aramid, is often difficult and costly. The resulting fiber waste cannot be incinerated in a waste incineration plant because it is inherently flame-resistant or non-combustible, and also has a high temperature resistance. Instead, it must be permanently disposed of at great expense, which poses major economic problems for the processors of these fibers.

[0011] The invention therefore sets itself the task of providing technical proposals for converting textile fiber materials or waste based on the specified high-performance polymers and containing toxic pollutants in the form of residual spinning solvents or subject to CMR classification into an advantageous, coagulable, particularly spinnable, polymer solution. This should enable the original fiber materials or waste loaded with pollutants to be usefully recycled, for example, for the production of fibers, films, membranes, and coatings, particularly through wet or dry-wet coagulation or spinning. The products manufactured by this subsequent process should therefore contain no toxic pollutants at all or, at most, a negligible amount of them.

[0012] This object is achieved by a wet- and dry-wet-coagulable, in particular wet- and dry-wet-spinnable, polymer solution based on ionic liquids and containing dissolved aromatic high-performance polymers in the form of m-aramids, aromatic polyamideimides, aromatic polyimides as poly(4,4-diphenylmethane-co-toluylenebenzophenonetetracarboxylimide) and / or polybenzimidazole, which were dissolved with the ionic liquid from pollutant-containing textile fiber materials, in particular textile fiber waste, wherein the polymer solution contains 70 to 95 wt.% ionic liquid, 3 to 15 wt.% of the high-performance polymers and more than 0.01 wt.% and less than 7 wt.%, in particular 0.01 to 3 wt.% toxic pollutants. The toxic pollutants have a toxicity of 0.500 mg / kg to 15.000 mg / kg, measured according to the oral LD ​​50 value (rat), and are present in the form of residual spinning solvents resulting from the production of textile fiber materials. The polymer solution has a zero viscosity of 1.5 to 30,000 Pa.s.

[0013] In the case of pseudoplastic liquids, as in the present case, such as melts and concentrated solutions of linear, unbranched polymers, the viscosity converges towards a constant value, the so-called zero viscosity, at a small velocity gradient. The zero viscosity can be determined using a standard rheometer, for example, with a plate-on-plate arrangement. An oscillation measurement with a geometric arrangement of the test specimens suitable for polymer solutions is preferred. In this regard, reference is made to Pahl M., Gleißle W., Laun H.-M.: "Practical Rheology of Plastics and Elastomers," VDI Society for Plastics Technology, 1995, pp. 137-144. The zero viscosity (measured here at 70°C) is important for the present invention. However, even without its specification, the skilled person is given sufficient instructions to successfully implement the invention, which will also be evident from the following considerations.

[0014] Accordingly, it was surprisingly found that the stated object is achieved in a particularly advantageous manner by preparing the solution of the said high-performance polymers with the aid of suitable ionic liquids, wherein the polymer solution can be further processed in a particularly advantageous manner by wet and dry-wet coagulation or by wet and dry-wet spinning.

[0015] When carrying out the invention, there is no relevant restriction on the type of ionic liquid. It is preferred to use ionic liquids according to the general formula [Q+] n [Z] n-<, where the cation [Q+] n is a quaternized ammonium [R1R2R3R4N+], phosphonium [R1R2R3R4P+] or sulfonium [R1R2R3S+] cation or an analogous quaternized nitrogen, phosphorus or sulfur heteroaromatic of the following formulas (I), (II), (III), (IV), (V) and (VI) where the radicals R1, R2, R3, R4 or the radicals R1 to R8 in the formulas (I) to (VI) are independently of one another linear, cyclic, branched, saturated or unsaturated alkyl radicals, mono- or polycyclic, aromatic or heteroaromatic radicals or derivatives of these radicals substituted by further functional groups, where R1, R2, R3 and R4 can be bonded to one another, where the anion [Z] n-< is present in the form of a halide, pseudohalide, amide, in the form of phosphorus compounds or nitro compounds.

[0016] A development of these ionic liquids which is particularly advantageous within the scope of the invention can be seen in the fact that the halides or pseudohalides have the formula F -< , Cl -< , Br -< , I -< , BF 4 -< , PF 6 -< , AlCl 4 -< , Al 2 Cl 7 -< , Al 3 Cl 10 -< , AlBr 4 , FeCl 4 -< , BCl 4 -< , SbF 6 -< , AsF 6 -< , ZnCl 3 -< , SnCl 3 -< , CuCl 2 -< , CF 3 SO 3 -< , (CN) 2 N -< , (CF 3 SO 3 ) 2 N -< , CF 3 CO 2 -< , CCl 3 CO 2 7< , CN -< , SCN -< , OCN -< , the Phosphorus compounds phosphates of the formula PO 4 3-<, HPO 4 2-<, H 2 PO 4 -<, R 1< PO 4 2-<, HR 1< PO 4 -<, R 1< R 2< PO 4 -<; Phosphonates and phosphinates of the formula: R 1< HPO 3 -<, R 1< R 2< PO 2 -<, R 1< R 2< PO 3 -<; Phosphites of the formula: PO 3 3-<, HPO 3 2-<, H 2 PO 3 -<, R 1< PO 3 2-<, R 1< HPO 3 -<, R 1< R 2< PO 3 -<; as well as phosphonites and phosphinites of the formula: R 1< R 2< PO 2 -< , R 1< HPO 2 -< , R 1< R 2< PO -< , R 1< HPO -<.

[0017] It is further advantageous if the alkyl radical is in the form of a C 1 -C 18 alkyl radical, in particular an alkyl radical having 1 to 4 carbon atoms, preferably a methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, or 2-butyl radical, the cyclic alkyl radical is in the form of a C 3-10 cycloalkyl radical, in particular in the form of a cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl radical, the unsaturated alkyl radical is in the form of a vinyl, 2-propenyl, 3-butenyl, cis-2-butenyl, trans-2-butenyl radical, the aromatic radical is in the form of a phenyl or naphthyl radical which is substituted with 1 to 3 halogen atoms, alkyl radicals having 1 to 4 carbon atoms or phenyl radicals may be substituted, and the heteroaromatic radical is in the form of an O-, S- or N-containing heterocyclic radical having 2 to 5 carbon atoms.It has proven particularly advantageous to use [EMIM] [DCA], [EMIM] [Cl], [EMIM] [SCN], [EMIM] [acetate], [EMIM] [DEP] and / or [MMIM] [DMP] as ionic liquids. The abbreviations have the following meanings: EMIM = ethylmethylimidazolium; [MMIM] = dimethylimidazolium; [DCA] = dicyanamide; [DMP] = dimethyl phosphate; [DEP] = diethyl phosphate; BMIM = 1-butyl-3-methylimidazolium; OMIM = 1-octyl-3-methylimidazolium. The following ionic liquids have proven particularly advantageous in the practice of the invention: the 1,3-dimethylimidazolium, 1,2,3-trimethylimidazolium, 1-butyl-3-methylimidazolium, 1-butyl-2,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium and / or 1-octyl-3-methylimidazolium salt.

[0018] In general, it can be stated that it is preferred if the ionic liquid is an imidazolium, pyridinium, pyrazolium, pyrimidinium, pyrazinium and / or pyridazinium salt.

[0019] According to the invention, the polymer solution contains 95 to 70 wt. %, in particular 95 to 85 wt. %, of ionic liquid, very particularly preferably 93 to 88 wt. Other compounds may be present dissolved in the polymer solution. These may be, for example, cellulose, for example in the form of cotton, or regenerated cellulose fibers, such as viscose, modal, or lyocell fibers. The regenerated cellulose fibers may optionally contain further additives, in particular flame retardant additives. The use of wool is also not excluded. Mixed moldings or polymer blends in the form of fibers, films, membranes, or coatings can be produced from corresponding mixed fiber waste, which contains the fibers named here in addition to m-aramids. Further details are disclosed in Example 4 below. Furthermore, the inclusion of cellulose derivatives, in particular cellulose acetate, propionate, butyrate, and / or carbamate, is advantageously possible here.

[0020] More about ionic liquids: Ionic liquids preferably have a high stability and particularly preferably have a decomposition temperature above 400°C; this applies, for example, in particular to dialkylamidazolium and alkylpyrridinium salts, in particular to the 1-alkyl-3-methyldimethazolium salt.

[0021] The temperature resistance of the ionic liquid is selected within the scope of the invention depending on the flow behavior of the polymer solution in the ionic liquid. The temperature resistance of the ionic liquid is preferably approximately 70°C or 150°C. The ionic liquids ethylmethylimidazolium diethyl phosphate (EMIM-DEP) and ethylmethylimidazolium chloride (EMIM-Cl) are particularly preferred. It has been shown that m-aramid, polyamideimide, polyimide, and polybenzimidazole dissolve particularly well in EMIM-DEP.

[0022] In principle, the concentration of the high-performance polymer in ionic liquids can be adjusted within a wide range. According to the invention, the coagulable or spinnable polymer solution contains 3 to 15 wt. %, in particular 3 to 12 wt. %, of high-performance polymers.

[0023] Given that the polymer solution according to the invention is intended to be wet- or dry-wet-coagulated or spun, the zero viscosity is particularly important. Within the scope of the invention, it is particularly between 1.5 and 30,000 Pa.s. It is preferred that the polymer solution according to the invention has a zero viscosity of 10 to 2,000 Pa.s, in particular 200 to 2,000 Pa.s, for spinning purposes, and a zero viscosity of 1 to 100, in particular 2 to 50 Pa.s, for coagulation purposes to produce films, membranes, and coatings. The zero viscosity, determined with a rheometer, can be adjusted depending on the high-performance polymer via the concentration and temperature. This is a well-known measurement method derived from the specialist literature (see above). The zero viscosity can be determined as described above.It should also be noted that the polymer solution according to the invention shows rheologically shear-thinning behavior.

[0024] Within the scope of the invention, the aromatic high-performance polymers, particularly from textile materials containing pollutants, are extracted in the manner described below. The aromatic polyamides are present as meta-aramids, particularly as poly(m-phenylene isophthalamide), and the aromatic polyimides are present as poly(4,4'-diphenylmethane-co-toluylenebenzophenonetetracarboxylimide) or as polybenzimidazole.

[0025] The particular value of the invention lies in the fact that pollutants can be removed during the processing of pollutant-containing textile materials using the process according to the invention, as described in more detail below. It is important that the pollutant and the aromatic high-performance polymers are dissolved and are therefore present in the coagulable or spinnable polymer solution. According to the invention, the pollutant is present in the form of residual spinning solvent resulting from the production of the fibers from the textile fiber waste, in particular as dimethylformamide (DMF), dimethylacetamide (DMA), tetramethylurea (TMH), dimethyl sulfoxide (DMSO), dimethylimidazolidinone (DMI), and / or N-methylpyrrolidone (NMP).

[0026] The above-mentioned pollutants or toxic residual spinning solvents can be described with regard to their toxicity as follows: They exhibit a toxicity of 0.500 mg / kg to 15,000 mg / kg, particularly 0.900 mg / kg to 7,500 mg / kg (measured according to the oral LD ​​50 value (rat)). In this regard, reference is made to the "Merck Atlas for Toxicity" literature.

[0027] The coagulable and spinnable polymer solution according to the invention may also contain further additives, either dissolved, finely dispersed, or emulsified. Examples of suitable additives include flame retardants, color pigments, matting agents, antibacterial or antiviral additives, anti-vector additives, and electromagnetic radiation-absorbing or reflecting additives.

[0028] The invention also relates to a process for processing textile fiber waste which contains high-performance polymers in the form of m-aramids, aromatic polyamideimides, aromatic polyimides as poly(4,4-diphenylmethane-co-toluylenebenzophenonetetracarboxylimide) and / or polybenzimidazoles as well as toxic pollutants with a toxicity of 0.500 mg / kg to 15,000 mg / kg, measured according to the oral LD ​​50 value (rat), in order to obtain a coagulable or spinnable polymer solution, as described above, which is characterized in that the textile fiber materials or waste which contain residual spinning solvents as a pollutant, in particular as a toxic pollutant, are mixed with an ionic liquid at room temperature up to 170°C, in particular under the action of shear forces, the ratio of the amount of textile fiber waste to the amount of ionic liquid being selected such that in the coagulable orspinnable polymer solution contains 70 to 95 wt.%, preferably 85 to 95 wt.% and particularly preferably 88 to 93 wt.% ionic liquid, 3 to 15 wt.%, in particular 3 to 12 wt.% high-performance polymers and more than 0.01 wt.% and less than 7 wt.%, preferably 0.01 to 3 wt.% and in particular 0.01 to 0.5 wt.% toxic pollutants.

[0029] The type of toxic pollutants or toxic spinning solvents considered for removal according to the invention has already been discussed above. The polymers of the textile fiber waste therefore contain toxic pollutants in such an amount that they are present in the coagulable or spinnable polymer solution in an amount of more than 0.01 wt.% and / or less than 7 wt.%, in particular less than 5 wt.%, preferably up to 3 wt.%, in particular from 0.01 to 0.5 wt.%.

[0030] Within the scope of the invention, the starting material in the form of textile fiber waste deserves further consideration. It is preferred that the textile fiber materials, in particular fiber waste, originate from fiber spinning, yarn spinning, knitting, dyeing, and finishing, or represent clothing waste, in particular cutting waste.The following describes the typical material compositions of yarns containing meta-aramid (commercially available fiber composition) used in knitted and woven articles: For example: Nomex ®< Comfort (solution-dyed, with pigments), consisting of: 93% m-aramid (poly-metaphenylene isophthalamide), 5% p-aramid (poly-paraphenylene terephthalamide), 2% non-conductive antistatic bicomponent fiber, consisting of a carbon core and a covering of poly-hexamethylene adipamide; 95% m-aramid (poly-metaphenylene isophthalamide), 5% p-aramid (poly-paraphenylene terephthalamide); 67% m-aramid (poly-metaphenylene isophthalamide), 23% p-aramid (poly-paraphenylene terephthalamide); 100% m-aramid (poly-metaphenylene isophthalamide).

[0031] The starting materials according to the invention are also derived, in particular, from waste generated during the production process. During fiber production and fiber spinning, for example, significant amounts of waste arise due to the transmission of different batches, dyes, etc. Production-related waste arises during yarn and staple fiber production, as well as in yarn spinning. In knitting, unprocessable waste arises due to varying yarn lengths on the spools and remnants on the spools. Dyeing and finishing also generate waste caused by edge trimming. This waste is collected for recycling.

[0032] Clothing waste is particularly important for the implementation of the invention: The largest quantities of cutting waste arise during the clothing process. The fabrics (e.g., woven or knitted fabrics) are laid out on cutting tables, and the templates for the garment pieces are placed on the fabric. Using the templates, the pieces are cut out and then joined (sewn). Despite minimizing gaps, large quantities of cutting waste are generated during cutting. This waste has been collected for years, so that quantities in the ton range exist.

[0033] The process according to the invention is particularly advantageous when shear forces are applied during the described process of dissolving the high-performance polymers, including the discussed pollutants. This is achieved, for example, by using a suitable stirrer or kneader. Shear forces in the range of 1 to 50,000 Pa.s, in particular 10 to 30,000 Pa.s, are preferably considered.

[0034] The temperature during the implementation of the process according to the invention, ie the mixing of the specified starting materials, is from room temperature up to 170°C. A temperature of 85 to 130°C, in particular 100 to 115°C, is preferred.

[0035] In individual cases, the polymer solution obtained according to the invention may contain insoluble components, which is also the rule. In order to advantageously further process the polymer solution according to the invention, in particular to coagulate or spin it using wet or dry-wet processes, it is expedient to separate the insoluble components by suitable means. This can be done, for example, by conventional filtration. The insoluble components can be, in particular, polypropylene, polyethylene terephthalate, polytetrafluoroethylene, p-aramid, and carbon fibers.

[0036] As already mentioned above, the polymer solutions according to the invention have the advantage that they can be used with great benefit for the production of fibers by wet or dry-wet spinning. Also important is the use of the polymer solution according to the invention for the production of films, membranes, and coatings, using conventional coagulation processes, in particular by wet or dry-wet coagulation.

[0037] The invention relates not only to the coagulable or spinnable polymer solution described in detail above and a process for its production, but also to its specific use. This can involve the production of fibers by wet or dry-wet spinning, but also the production of films, membranes, and coatings by conventional coagulation processes, in particular by wet or dry-wet coagulation. Subsequently, process products are obtained which contain virtually no toxic pollutants or at most in negligible quantities, preferably in an amount of less than 20 ppm, in particular less than 5 ppm. The particular advantage of the invention lies in the fact that the value below 3 ppm and in particular 1 ppm can easily be undercut.

[0038] The fibers, films, membranes, or coatings produced by the process according to the invention have levels of toxic pollutants, particularly DMF or DMA, of even less than 1 ppm. The residual amounts of ionic liquid in the consolidated and post-washed and optionally stretched products are negligible. The ionic liquid present in the coagulation baths can be enriched, distilled, and reused to dissolve the described high-performance polymers using known methods.

[0039] Accordingly, it is advantageous according to the invention that, based on the polymer solution that can be coagulated or spun wet-on-wet and dry-on-wet, fibers can be produced in which the proportion of the designated pollutants is reduced to a minimum, practically 0, or negligibly small. For the purpose of fiber production, it is advantageous to spin the polymer solutions into fibers in an aqueous coagulation bath, either wet-on-wet or dry-on-wet via an air gap. Wet-on-wet means that the spinneret is immersed in the aqueous coagulation bath. When spinning via an air gap, the polymer solution first passes through an air gap as it emerges from the nozzle, which air gap generally has a height of 1 to 20 mm, preferably 5 to 11 mm. Both process principles are sufficiently known to the person skilled in the art.

[0040] To produce film membranes or coatings from the specified high-performance polymers, the polymer solutions are coated onto a suitable carrier material, and the film membrane or coating is subsequently formed by coagulation in an aqueous precipitation bath. Various substrates can be considered as carrier materials for coatings. The textiles are preferably in the form of woven fabrics, knitwear, or nonwovens. The polymer solution can be applied to the base substrate using conventional technical methods, such as a doctor blade or roller. The films can also be produced using a casting process.

[0041] Advantageously, the structural and mechanical properties of the formed fibers, membranes, and coatings can be directly influenced by altering the coagulation medium. For example, the mechanical and elastic properties of formed fibers are sometimes significantly improved by additives that delay coagulation and structure formation, such as, in particular, glycerol, ethylene glycol, 1,2-propanediol, polyethylene glycols, polypropylene glycols, or other suitable polyhydric alcohols or carbohydrates known to those skilled in the art. The pore structures of formed membranes or coatings made of the aforementioned high-performance polymers are also sometimes positively influenced, resulting in increased breathability.

[0042] The invention, as described above, achieves the stated objective to a surprisingly favorable extent. The fibers, films, membranes, and other molded bodies produced according to the invention all exhibit very good flame-resistant properties, expressed by the LOI value. The LOI value is a measure of the quality of the flame-retardant finish (according to ASTM D2863-77). It represents the limiting value of the volume fraction of oxygen in an oxygen / nitrogen gas mixture at which a textile fabric just burns from top to bottom. The higher the LOI value, the better the flame-retardant effect. An LOI of 24 or higher is considered flame-retardant, and values ​​of 27 and higher are considered self-extinguishing. The fibers made of aramid, polyimide, and polybenzimidazole produced according to the invention have an LOI of > 29. Film membranes produced by the process also exhibit LOI values ​​greater than 28.

[0043] The present invention offers a wide range of advantages, as outlined above. In particular, the toxic pollutants are elegantly removed from the described fiber waste. The polymer solution according to the invention can advantageously be coagulated or spun, whereby the pollutants originally contained in the fiber waste are completely or largely removed. Fiber waste can be used that contains the specified high-performance polymers in quantities of up to 100% or 100%, as well as waste that only contains a portion of these polymers, and also other components that are insoluble in the ionic liquid but are easily separated. These insoluble components can be, for example, those based on polypropylene, polyethylene terephthalate, polytetrafluoroethylene, p-aramid, or carbon fibers.If such fiber components are present in mixtures with one or more of the high-performance polymers soluble in the ionic liquid, they can be easily separated, allowing advantageous further processing into fibers, films, or other products (see above) with the polymer solution after separation. Consequently, textile materials containing pollutants can be further processed that contain the high-performance polymers mentioned, but also mixed fibers that are insoluble in the mixture, i.e., "Foreign fibers", which, after separation, can in individual cases be made available for advantageous further use.

[0044] The invention will be explained in more detail below using examples: Example 1 (fibers)

[0045] In a 10-liter kneader, 5 liters of ethylmethylimidazolium diethyl phosphate (EMIM-DEP) are placed, and 733 g of a shredded fiber blend consisting of 93% m-aramid, 5% p-aramid, and 2% graphite-coated synthetic fiber from clothing waste are added at room temperature. The dimethylacetamide (DMA) content of the fiber blend was determined to be 0.44 wt.%. The mixture is heated to 90°C, and the kneading process is maintained for 3 hours. A paste is obtained containing the carbon and p-aramid fibers insoluble in EMIM-DEP. If the fibers or textile were dyed, the paste may optionally contain dyes or color pigments.

[0046] The undissolved fiber particles were filtered using a vacuum filtration device. To keep viscosity as low as possible, filtration was performed while hot. Narrower mesh sizes were successively used: 1. Sieve: Metal mesh, mesh size approx. 1 mm 2. Wire mesh GKD Gebr. Kufferath (Düren), mesh size: 0.1 mm 3. Triple combination filter, mesh size of the smallest filter: 10 µm

[0047] After filtration, a homogeneous, possibly colored solution of the m-aramid in EMIM-DEP was obtained. The fiber components of the mixture used that are insoluble in EMIM-DEP, i.e., the p-aramid and the carbon fibers, remain as filter residue. The solution of the m-aramid in EMIM-DEP at a concentration of 8.6 wt.% had a zero viscosity of 260 Pa.s (measured as described above) and exhibited pseudoplastic behavior.

[0048] The solution was processed on a spinning system using the air-gap spinning process. This consisted of a heatable storage vessel, a filter device, and a 48-hole spinneret with individual hole diameters of 60 µm. The air gap was 10 mm long. The spinning solution temperature was 70°C. The coagulation bath contained a mixture of 95% water and 5 wt.% EMIM-DEP. The spun filaments were post-drawn and dried over two heatable godets.

[0049] Blue-black dyed filaments with a fineness of 2.2 dtex were obtained, with a maximum tensile strength (measured according to DIN EN ISO 2062) of 30.4 cN / tex (measured according to EN ISO 2062) and a maximum tensile elongation (measured according to DIN EN ISO 2062) of 35%. The dimethylacetamide content of the spun fibers is < 1 ppm. Example 2 (membranes)

[0050] 240 g of ethylmethylimidazolium diethyl phosphate (EMIM-DEP) are placed in a three-necked round-bottom flask equipped with a propeller stirrer. 20 g of a fiber mixture consisting of 93% m-aramid, 5% p-aramid, and 2% graphite-coated synthetic fiber from clothing waste are added while stirring slowly. The temperature of the EMIM-DEP was set to 110°C. Over the course of 10 hours, a filterable solution forms, with the undissolved components being filtered off using the procedure described in Example 1. This results in a 5.1 wt. % pseudoplastic solution of the m-aramid with a zero viscosity of 17 Pa.s.

[0051] To produce membranes, this solution was applied to a glass plate and spread using a doctor blade with a 250 µm gap. After a residence time of 10 minutes, the film was coagulated in hot distilled water. The membrane formed after coagulation was washed twice with water and then dried. The membrane has a layer thickness of approximately 140 µm with an asymmetric structure. The water vapor permeability, determined according to ASTM E96, is 2,970 g / m² per day. The flame resistance of the formed membrane, evaluated using the Limiting Oxygen Index according to ASTM 2863, is 43. The dimethylacetamide content of the spun fibers is < 1 ppm. Example 3 ( Coatings )

[0052] 240 g of ethylmethylimidazolium diethyl phosphate (EMIM-DEP) are placed in a three-necked round-bottom flask equipped with a propeller stirrer. 37 g of a fiber mixture consisting of 93% m-aramid, 5% p-aramid, and 2% graphite-coated synthetic fiber from clothing waste (see Example 1) are added while stirring slowly. The temperature of the EMIM-DEP was set to 110°C. Over the course of 24 hours, a filterable solution forms, with the undissolved components being filtered off using the same procedure as described in Example 1. The result is a 9.7 wt. % pseudoplastic solution of the m-aramid with a zero viscosity of 24 Pa.s.

[0053] The solution was spread onto a polyamide fabric (warp satin, basis weight 100 g / m²) using a doctor blade and coagulated in 60°C hot water. The composite was then dried in air. The aramid structure formed, tightly bonded to the textile substrate, featuring finger-shaped channels with a layer thickness of approximately 100 µm. The water vapor permeability, determined according to ASTM E96, was 3,320 g / m² per day. The dimethylacetamide content of the product was < 1 ppm. Example 4 ( Blend m-Aramid / Viscose FR)

[0054] In a 4-liter kneader, 2.5 liters of ethylmethylimidazolium diethyl phosphate (EMIM-DEP) are placed, and 305 g of a fiber blend consisting of 50% m-aramid and 50% viscose FR from clothing waste are added at room temperature. The mixture is heated to 90°C, and the kneading process is maintained for 3 hours. A homogeneous solution is obtained, which may also contain dyes or color pigments. The dimethylacetamide content of the fiber blend was determined to be 0.15 wt.%.

[0055] After filtration through a filter pack with 0.1 and 0.01 mm mesh sizes, a homogeneous solution consisting of m-aramid and viscose in EMIM-DEP was obtained. The concentration was 12.0 wt.%. The solution had a zero viscosity of 940 Pa.s and exhibited pseudoplastic behavior.

[0056] The solution was processed and post-treated analogously to Example 1 on a spinning system using the so-called air-gap spinning process.

[0057] Filaments with a fineness of 1.8 dtex were obtained, with a maximum tensile strength (measured according to DIN EN ISO 2062) of 21.0 cN / tex and a maximum tensile elongation (measured according to DIN EN ISO 2062) of 23%. The dimethylacetamide content of the spun fibers is < 1 ppm. Example 5

[0058] The filaments obtained from Example 1 were cut to approximately 50 mm fiber length using a cutting knife. The resulting staple fibers were parallelized on a carding machine and then needled into a nonwoven fabric. The basis weight of the nonwoven fabric was 84 g / m², the LOI value was 31.2, and dimethylacetamide was <1 ppm. Example 6

[0059] The filaments obtained from Example 4 were cut to approximately 50 mm fiber length using a cutting knife. After carding, the resulting staple fibers were processed into a ring yarn Nm 50 / 1 with a set twist of 110°. The yarn's maximum tensile strength was 18.2 cN / tex (measured above), and its maximum tensile elongation was 6% (measured above). The dimethylacetamide content was < 1 ppm.

[0060] A single jersey knit was produced from the yarn on a Lawson Hemphill circular knitting machine. Needle count: 624, eccentric pitch: 6.4 mm, and needle tension: 2 needles. The LOI of the jersey fabric was 23.2.

Claims

1. A wet and dry-wet coagulable, in particular wet and dry-wet spinnable polymer solution based on ionic liquids and having a content of aromatic high-performance polymers dissolved therein in the form of m-aramids, of aromatic polyamide-imides, of aromatic polyimides as poly(4,4-diphenylmethane-co-toluylene benzophenone tetracarboxylimide) and / or of polybenzimidazole, which have been dissolved out of textile fiber materials containing toxic pollutants by means of the ionic liquid, wherein the toxic pollutants have a toxicity of 0.500 mg / kg to 15,000 mg / kg, measured according to the oral LD50 value (rat), and are present in the form of residual spinning solvents resulting from the manufacture of textile fiber materials, and wherein the polymer solution contains 70 to 95% by weight of ionic liquid, 3 to 15% by weight of high-performance polymers, and more than 0.01 % by weight and less than 7 % by weight of toxic pollutants.

2. The coagulable polymer solution according to claim 1, characterized in that the textile fiber materials are textile fiber waste.

3. The coagulable polymer solution according to claim 1 or 2, characterized in that it contains 3 to 12% by weight of high-performance polymers.

4. The coagulable polymer solution according to any one of the claims 1 to 3, characterized in that the polymer solution contains 85 to 95% by weight, in particular 88 to 93% by weight, of an ionic liquid, more than 0.01% by weight and less than 5% by weight of toxic pollutants, preferably 0.01 to 3% by weight and in particular 0.01 to 0.5% by weight.

5. The coagulable polymer solution according to any one of the claims 1 to 3, characterized in that it has a zero shear viscosity of 10 to 2,000 Pa.s for the purpose of spinning, and a zero shear viscosity of 1 to 100 Pa.s for the purpose of coagulating for the production of films, membranes, and coatings, wherein the zero shear viscosity is measured at 70°C using a rheometer with a plate-plate arrangement.

6. The coagulable polymer solution according to at least any one of the preceding claims, characterized in that the ionic liquid is an imidazolium, pyridinium, pyrazolium, pyrimidinium, pyrazinium, and / or pyridazinium salt.

7. The coagulable polymer solution according to at least any one of the preceding claims, characterized in that the toxic pollutants are present in the form of residual spinning solvents resulting from the production of textile fiber materials, wherein the residual spinning solvents is present in particular in the form of dimethylformamide (DMF), dimethylacetamide (DMA), tetramethylurea (TMU), dimethylsulfoxide (DMSO), dimethylimidazolidinone (DMI), and / or N-methylpyrrolidone (NMP).

8. The coagulable polymer solution according to at least any one of the preceding claims, characterized in that the toxic pollutants or the residual spinning solvents have a toxicity of 0.900 mg / kg to 7,500 mg / kg.

9. A process for working up textile fiber materials or textile fiber waste containing high-performance polymers in the form of m-aramids, aromatic polyamide-imides, aromatic polyimides as poly(4,4-diphenylmethane-co- toluylene benzophenone tetracarboxylimide) and / or polybenzimidazoles as well as toxic pollutants with a toxicity of 0.500 mg / kg to 15,000 mg / kg, measured according to the oral LD50 value (rat), for obtaining a coagulable or spinnable polymer solution, characterized in that the textile fiber materials or textile fiber waste containing residual spinning solvents as toxic pollutants are mixed with an ionic liquid at room temperature up to 170°C, in particular at a temperature of 85 to 130°C, wherein the ratio of the amount of the textile fiber materials or textile fiber waste to the amount of the ionic liquid is selected, so that the coagulable or spinnable polymer solution obtained contains 70 to 95% by weight, preferably 85 to 95% by weight, and particularly preferably 88 to 93% by weight of ionic liquid, 3 to 15% by weight, in particular 3 to 12% by weight of high-performance polymers, and more than 0.01% by weight and less than 7% by weight, preferably 0.01 to 3% by weight, and in particular 0.01 to 0.5% by weight of toxic pollutants.

10. The process according to claim 9, characterized in that the textile fiber materials are mixed with the ionic liquid under the action of shearing forces.

11. The process according to at least any one of the claims 9 or 10, characterized in that textile fiber materials or waste are used which contain dimethylformamide (DMF), dimethylacetamide (DMA), tetramethylurea (TMH), dimethylsulfoxide (DMSO), dimethylimidazolidinone (DMI), and / or N-methylpyrrolidone (NMP) as toxic pollutant.

12. The process according to at least any one of the claims 9 and 11, characterized in that the high-performance polymers of the textile fiber materials or waste contain the toxic pollutants or the spinning solvents in such an amount that, after mixing with the ionic liquids and further reprocessing, they are present in the spinnable polymer solution in an amount of more than 0.01% by weight and less than 7% by weight, wherein the toxic pollutants are present in the spinnable polymer solution in particular in an amount of 0.01 to 5% by weight, preferably in an amount of 0.01 to 3% by weight, in particular in an amount of 0.01 to 0.05% by weight.

13. The process according to at least any one of the claims 9 to 12, characterized in that the textile fiber materials or wastes originate from fiber spinning, yarn spinning, knitting, dyeing, and / or finishing or are garment manufacturing waste, wherein the garment manufacturing waste is in particular cutting waste.

14. The process according to at least any one of the claims 9 to 13, characterized in that an imidazolium, pyridinium, pyrazolium, pyrimidinium, pyrazinium, and / or pyridazinium salt is used as the ionic liquid.

15. The process according to at least any one of the claims 9 to 14, characterized in that insoluble constituents present in the spinnable polymer solution are separated off before further processing thereof, wherein the insoluble constituents are in particular polypropylene, polyethylene terephthalate, polytetrafluoroethylene, p-aramid, and / or carbon fibers.

16. The process according to at least any one of the claims 9 to 15, characterized in that the coagulable or spinnable polymer solution contains additional polymeric materials and / or wool dissolved in order to obtain shaped bodies based on mixed polymers during further processing by coagulation or spinning, wherein the additional polymeric materials are present in particular in the form of cellulose, cellulose derivatives, cellulose acetate, cellulose propionate, cellulose butyrate, and / or cellulose carbamate.

17. A use of the spinnable polymer solution according to at least any one of the claims 1 to 8 for the production of fibers by wet or dry-wet spinning or use of the coagulable polymer solution according to at least one of the claims 1 to 8 for the production of films, membranes, and coatings by wet or dry-wet coagulation, wherein the fibers, films, membranes, and coatings obtained in particular have a content of toxic pollutants of less than 20 ppm.