DE102012006501A1 - Lignocellulosic dope, lignocellulosic regenerated fiber and process for their preparation - Google Patents

Abstract

The invention relates to a lignocellulose spinning solution, regenerated fibers of lignocellulose and a process for their preparation. By the method according to the invention lignocellulose can be processed for the first time without prior chemical separation process to separate the cellulose impurities such as lignin and hemicellulose or without thermomechanical pretreatment of the raw material to fibers. The present invention is the use of specially adapted ionic liquids of the imidazole type as a solvent for lignocellulose of various origins. From the almost homogeneous spinning solutions prepared therefrom, it is possible with commercial spinning apparatus to produce stable filaments with comparable mechanical parameters as obtainable in commercial cellulose spinning processes. Neither laborious cellulose extraction, nor thermal and / or chemical pretreatment of the wood raw material are required here.

Description

The invention relates to a lignocellulose spinning solution, regenerated fibers of lignocellulose and a process for their preparation. By the method according to the invention lignocellulose can be processed for the first time without prior chemical separation process to separate the cellulose impurities such as lignin and hemicellulose or without thermomechanical pretreatment of the raw material to fibers. The present invention is the use of specially adapted ionic liquids of the imidazole type as a solvent for lignocellulose of various origins. From the almost homogeneous spinning solutions prepared therefrom, it is possible with commercial spinning apparatus to produce stable filaments with comparable mechanical parameters as obtainable in commercial cellulose spinning processes. Neither laborious cellulose extraction, nor thermal and / or chemical pretreatment of the wood raw material are required here.

There is a growing global demand for products and materials that should be as easy and cost-effective to produce from renewable raw materials. In particular, wood is the focus here, as it is not only the most heavily used biological raw material in terms of volume, but also a very complex natural material with a wide range of applications.

The same but variable composition of the main ingredients cellulose, hemicellulose and lignin has led to various approaches to processing, the most important of which is still the cellulose separation ( Kraft Process, Sulfite Process, Kirk-Othmer, Encyclopaedia of Chemical Technology, 1996, 4th Ed., Vol. 20, pp. 493-546 ), the use as construction material and the mostly thermal utilization of the residues are.

In view of the scarcity of resources and the development of suitable separation processes, hemicelluloses and lignin are increasingly being used for recycling ( Braun et al. in Carbon 2005, 43, 385-394 ). Desirable goals, however, are the avoidance of energetic and materially complex separation processes and the direct refinement of solubilized wood raw materials.

Since the 90s of the 20th century, organic salts with melting points mostly below 100 ° C, so-called ionic liquids (IL), intensively studied as a solvent ( ME Zakrzewska et al. in Energy Fuels 2010, 24 pp. 737-745 ; P. Mäki-Arvela et al. in Industrial Crops and Products 2010, 32, pp. 175-201 ). While selected ILs can now dissolve up to 25% cellulose ( Zhu, et al. in Green Chem. 2006, 8, pp. 325-327 ) and a processing to, for example, filaments or tissue ( EP 1980653 A2 . US 2008/0241536 ; WO 2006/000197 A1 ), this is not yet possible for wood raw materials or only with decisive limitations.

Thus, the best results so far for such solutions are achieved almost exclusively with chloride-based IL such as 1-butyl-3-methylimidazolium chloride (BMIMCI) or 1-allyl-3-methylimidazolium chloride (AMIMCI) ( WO 2005/017001 A1 . US 2008/0188636 A1 ), which due to their corrosivity (HCl) increase the cost of corresponding large-scale facilities enormously.

Furthermore, good solutions either by elaborate pretreatments of the raw materials (microwave, ultrasound) ( N. Sun in Green Chem, 30 2009, 11, p. 646-655 ), which often lead to the depolymerization of the cellulose, by uneconomical dilution to a maximum of 8 wt .-% "wood" content ( WO 2005/017001 A1 . I. Kilpeläinen et al. in J. Agric. Food Chem. 2007, 55, p. 9142-9148 ), by solution times> 24 h ( WO 2008/043837 A1 ) or by additives such as PEG ( WO 2009/105236 A1 ), which in turn makes it much more difficult to recycle the ILs used.

Such references have only one focus on the solubilization of wood with the aim of demonstrating alternative processes for separating the lignocellulosic components (ie, essentially cellulose, hemicellulose and lignin). Others aim to depolymerize the components of lignocellulose to obtain monomeric compounds ( WO 2007 / 112090A2 ).

A material development to gerakelten films is in US 2008/0188636 A demonstrated. The processing of low concentrations (<5 wt .-%) of lignocellulose from a solution to a monofilament by Sun et al. (in Green Chem., 2011, 13, pp. 1158-1161) first described. In this case, 1-ethyl-3-methyl-imidazolium acetate (EMIMAc) is used as the solvent. Furthermore, an alkaline pretreatment of the lignocellulose can not be dispensed with in order to obtain suitable solution qualities for spinning.

The alkaline extraction leads to a partial separation of the lignocellulose components. In the Sun et al. Solution conditions (solution of the lignocellulose at a temperature of 175 ° C.) furthermore lead to a strong depolymerization of hemicellulose, lignin and of cellulose, which is reflected in the achieved mechanical properties of the monofilament (maximum tear strength of 17 cN / tex). Further, in Sun et al. used equipment (syringe) not comparable with a spin system on a technical scale, which works on the principle of air gap spinning. The skilled person is aware of the major deficiencies and therefore the results obtained are not representative.

In summary, no ionic liquids are disclosed in the prior art which enable the solution of lignocellulose in high concentration and at low temperature and low dissolution time. Due to the relatively high temperatures and dissolution times resulting from the IL used in the prior art, the lignocellulose begins to chemically change during solution (eg, depolymerization of the polymeric constituents). This has a negative effect on the properties of the products of the spinning solution (eg tensile strength of fibers). Furthermore, long dissolution times and low levels of lignocellulose in the dope solution are not economical.

The problems of the prior art are solved by the lignocellulosic spinning solution according to claim 1, the regenerated fiber according to claim 23 and the use of the regenerated fiber according to claim 26.

According to the invention, a lignocellulosic spinning solution is provided which contains a solution of lignocellulose in at least one ionic liquid, wherein the at least one ionic liquid consists of a 1-alkyl-3-methylimidazolium cation and a substantially hydrophobic carboxylate anion and the Dyestuff solution characterized in that lignocellulose is present in a concentration of at least 10 wt .-% and the spinning solution has a zero shear viscosity, measured at 80 ° C, of ≤ 30000 Pas.

• – Die Spinnlösung enthält Lignocellulose in einer Konzentration von mindestens 10 Gew.-% in gelöster Form;
• – Die Spinnlösung enthält Lignocellulose mit einem geringen Grad an depolymerisierten polymeren Bestandteilen und weist folglich ausgezeichnete Spinneigenschaften auf;
• – Die Spinnlösung kann zu Filamenten mit hohem Anteil an Lignin (5 bis 30 Gew.-%) sowie Hemicellulosen (5 bis 30 Gew.-%) verformt werden;
• – Es liegen keine korrosiven (z. B. Cl^–-haltigen) IL in der Spinnlösung vor;
• – Die Spinnlösung ist ohne Einschränkung im technischen Maßstab herstellbar.

The spinning solution according to the invention is advantageous over the prior art in the following points:

• - The spinning solution contains lignocellulose in a concentration of at least 10 wt .-% in dissolved form;
• The spinning solution contains lignocellulose with a low level of depolymerized polymeric constituents and thus has excellent spinning properties;
• - The spinning solution can be formed into filaments with a high content of lignin (5 to 30 wt .-%) and hemicelluloses (5 to 30 wt .-%);
• - There are no corrosive (eg Cl ^- -containing) ILs in the spinning solution;
• - The spinning solution can be produced without restriction on an industrial scale.

• – Die Spinnlösung kann durch direktes Lösen von Holzrohstoff ohne vorgeschaltetes Aufschlussverfahren hergestellt werden. Dadurch wird die Herstellung der Spinnlösung sehr ökonomisch, da Zeit und Kosten bei der Herstellung der Spinnlösung reduziert werden;
• – Es können Holzrohstoffe basierend auf allen Pflanzen, bevorzugt Einjahrespflanzen und/oder Bäume, ohne weitere Vorbehandlung wie TMP, Bestrahlung, Einwirkung von Säuren oder Laugen weitestgehend homogen in Lösung gebracht werden. Durch Wegfall der chemischen Vorbehandlung liegen Lignin und Hemicellulosen in der Spinnlösung ohne chemischen Modifikationen vor, wie sie durch klassische Aufschlussverfahren für Holzrohstoffe hervorgerufen werden. Hieraus ergeben sich Vorteile in Bezug auf die der Produkte der Spinnlösung (z. B. höhere Werte für Festigkeit und E-Modul für Regeneratfasern);
• – Durch Verzicht auf Vorbehandlung der Holzrohstoffe, Zusatz von Additiven (wie z. B. DMSO, PEG) und moderate Temperaturen werden gut recyclingfähige Fällbäder nach dem Spinnprozess erhalten. Die Umweltbelastung wird dadurch erheblich reduziert.

In a preferred embodiment of the invention, the lignocellulose is wood raw material, ie, for the extraction of lignocellulose from plants, no (chemical) digestion process is required prior to dissolution in the ionic liquid. The use of untreated wood raw material as lignocellulosic source has decisive advantages:

• - The spinning solution can be prepared by directly dissolving wood raw material without upstream digestion process. This makes the production of the spinning solution very economical, since time and costs are reduced in the production of the spinning solution;
• - Wood raw materials based on all plants, preferably annual plants and / or trees, can be brought as far as possible homogeneously in solution without further pretreatment such as TMP, irradiation, exposure to acids or alkalis. By eliminating the chemical pretreatment lignin and hemicelluloses are present in the dope without chemical modifications, as they are caused by classical pulping process for wood raw materials. This results in advantages with respect to the products of the spinning solution (eg higher values for strength and modulus of elasticity for regenerated fibers);
• By dispensing with pretreatment of the wood raw materials, addition of additives (such as DMSO, PEG) and moderate temperatures, well-recyclable precipitation baths are obtained after the spinning process. The environmental impact is thereby significantly reduced.

The spinning solution can have a zero shear viscosity, measured at 80 ° C., of 500 Pas to 3000 Pas, preferably a zero shear viscosity of 1000 Pas to 2500 Pas. A zero shear viscosity in this range has been found to be particularly advantageous for the production of regenerated fibers.

Preferably, the carboxylate anion has more carbon atoms than atoms of group 15, 16 and / or 17 of the periodic table (examples of group 15: N and P; examples of group 16: O and S. Examples of group 17: F, Cl, Br and I) or consists thereof.

With particular preference the carboxylate anion contains no further hydrophilic group apart from at least one carboxyl group (eg only one carboxyl group).

In a particularly preferred embodiment, the carboxylate anion contains at least 3 C atoms, preferably at least 4 C atoms.

• a) mindestens eine Doppelbindung aufweist, insbesondere im Fall eines C3, C4 und/oder C5-Carboxylat-Anions;
• b) zumindest bereichsweise verzweigt ist, insbesondere im Fall eines C4-, C5- und/oder C6-Carboxylat-Anions; und/oder
• c) zumindest bereichsweise zyklisiert ist, insbesondere im Fall eines C6- oder C7-Carboxylat-Anions.

The carboxylate anion may be further characterized by being

• a) has at least one double bond, in particular in the case of a C3, C4 and / or C5 carboxylate anion;
• b) is at least partially branched, in particular in the case of a C4, C5 and / or C6 carboxylate anion; and or
• c) is at least partially cyclized, especially in the case of a C6 or C7 carboxylate anion.

According to the invention, the carboxylate anion may have or consist of 3 to 18, preferably 3 to 12, particularly preferably 4 to 7, carbon atoms.

The carboxylate anion is particularly preferably selected from the group consisting of 2,2-dimethylpropanate anion, 2-butenate anion and cyclohexylcarboxylate anion.

It has surprisingly been found that an ionic liquid (IL) consisting of a 1-alkyl-3-methylimidazolium cation and a substantially hydrophobic carboxylate anion, especially an anion of the abovementioned preferred embodiments, lignocellulose or even wood pulp in over the prior art higher concentration and at a given temperature in less time can solve. It has furthermore been found that, in the case of C3-C7 carboxylate anions, branching, cyclization and / or the presence of a double bond is advantageous for the solution of lignocellulose (for example in the form of wood raw material) (low solution temperature and solution time) ,

The spinning solution according to the invention is preferably prepared by mixing the lignocellulose with water and / or an aliphatic alcohol and dissolving it in the ionic liquid at a temperature ≦ 150 ° C., preferably ≦ 140 ° C., particularly preferably ≦ 130 ° C. It is further preferred that the spinning solution is prepared by dissolving the lignocellulose within a time of ≦ 10 h, preferably ≦ 7 h, particularly preferably ≦ 5 h, with at least partial removal of the water and / or aliphatic alcohol.

The preparation of the lignocellulose spinning solution can be carried out in a stirring unit or kneading unit.

• a) Lignin in einem Anteil von mindestens 5 Gew.-%, besonders bevorzugt 5 bis 35 Gew.-%;
• b) Hemicellulose in einem Anteil von mindestens 5 Gew.-%, besonders bevorzugt von 5 bis 35 Gew.-%; und/oder
• c) Cellulose in einem Anteil von mindestens 30 Gew.-%, bevorzugt 30 bis 70 Gew.-%;

in Bezug auf das Gesamtgewicht der Lignocellulose.The spinning solution according to the invention preferably contains

• a) lignin in a proportion of at least 5 wt .-%, particularly preferably 5 to 35 wt .-%;
• b) hemicellulose in an amount of at least 5% by weight, more preferably from 5 to 35% by weight; and or
• c) cellulose in a proportion of at least 30 wt .-%, preferably 30 to 70 wt .-%;

in relation to the total weight of lignocellulose.

Preferably, the spinning solution contains 10 to 35 wt .-%, preferably 10 to 30 wt .-%, lignocellulose.

With respect to the cation of the ionic liquid, the alkyl radical at position 1 in the 1-alkyl-3-alkylimidazolium cation may be a substituted or unsubstituted C ₁ -C ₆ alkyl radical or an aryl radical, preferably selected from the group consisting from methyl, ethyl, propyl, butyl, pentyl, hexyl, allyl, benzyl, imidazolyl, methoxymetyl, methoxyethyl and ethoxyethyl, particularly preferably ethyl and butyl.

The spinning solution may contain or consist of lignocellulose of at least one plant, preferably at least one annual or at least one tree, more preferably at least one plant selected from the group consisting of wheat, rye, maize, hemp, flax, poplar and / or beech.

The lignocellulose may be wood raw material d. H. In a preferred embodiment of the invention, native lignocellulose is dissolved in the spinning solution. In this case, the lignocellulose has not been chemically treated (eg, by the Kraft process or the sulfite process) prior to dissolution in the ionic liquid, and thus has not been chemically modified. It can be used, for example, lignocellulose, which consists of ground wheat straw.

The lignocellulose may be dried in a spin bath prior to solution as this further improves the solubility of the lignocellulose in the ionic liquid. The spinning solution may thus contain ≦ vol.%, Preferably ≦ 2 vol.%, Particularly preferably ≦ 1 vol.%, Of water.

The spinning solution is preferably a homogeneous particle-free spinning solution. This can be prepared, for example, by filtering the spinning solution through a filtration device. A homogeneous particle-free spinning solution has an advantageous effect on the properties of a regenerated fiber obtained from the spinning solution.

• a) Pressen einer Lignocellulose-Spinnlösung, welche mindestens 10 Gew.-% Lignocellulose in mindestens einer ionischen Flüssigkeit enthält und eine Nullscherviskosität, gemessen bei 80°C, von ≤ 30000 Pas aufweist, durch mindestens eine Öffnung mindestens einer Spinndüse, wobei mindestens ein Faden entsteht;
• b) Verstreckung des mindestens einen Fadens in mindestens einem Luftspalt; und
• c) Verfestigung des mindestens einen Fadens in mindestens einem Fällbad.

Furthermore, a method for producing a regenerated fiber according to the invention provided, the method comprising the following steps:

• a) pressing a lignocellulosic spinning solution containing at least 10 wt .-% lignocellulose in at least one ionic liquid and having a zero shear viscosity, measured at 80 ° C, of ≤ 30000 Pas, through at least one opening at least one spinneret, wherein at least one thread arises;
• b) stretching the at least one thread in at least one air gap; and
• c) solidification of the at least one thread in at least one precipitation bath.

The process of the invention for producing a regenerated fiber is an air-gap spinning process. In the air-gap spinning process, the viscous spinning solution is forced through the holes of a spinneret and drawn (extruded) fiber in the air gap.

The spinning solution can in this case be adjusted to a temperature of 60 to 150.degree. C., preferably 80 to 130.degree. C., particularly preferably 90 to 120.degree.

In the process, the spinning solution can be pressed through an opening of the at least one spinneret which has a diameter of more than 100 μm, preferably a diameter of 100 μm to 600 μm.

Furthermore, the at least one thread can be stretched in at least one air gap with a length of at least 20 mm, preferably with a length of 20 to 500 mm.

The at least one thread can according to the invention with a delay ratio of 2 to 10, preferably 3 to 9, particularly preferably 4 to 8, are stretched.

Further, the at least one (extruded) thread may be solidified in at least one coagulation bath containing or consisting of a liquid selected from the group consisting of water, polymer solvent, ionic liquid and aliphatic C ₁ -C ₈ alcohol. The precipitation bath preferably contains water or a mixture of a polymer solvent and water.

After solidification in at least one precipitation bath, the at least one thread can be dried in a further step, preferably at a temperature of at least 80 ° C., more preferably at a temperature of at least 100 ° C.

In a further preferred embodiment, the at least one thread is equipped with at least one spinning oil. This is preferably done after solidification of the at least one thread in at least one precipitation bath and / or after the drying of the at least one thread. By equipping the at least one thread with the spinning oil, it is to be understood that spinning oil is applied at least in regions to the surface of the at least one thread. As a result, static charges and "sticking together" of the threads can be reduced, which has a particularly advantageous effect on downstream processes for textile production.

The threads or fibers can be washed, finished, dried and then wound up as filament. Optionally, multiple filaments or fibers can be formed into filaments and / or wound up.

The spinning solution used in the process may have a zero shear viscosity, measured at 80 ° C, of 500 Pas to 3000 Pas, preferably 1000 Pas to 2500 Pas.

Preferably, in the process according to the invention before step a), homogenization of the spinning solution and liberation of the spinning solution from particles are carried out. This can be z. B. by filtration of the spinning solution.

In a further preferred embodiment of the process according to the invention, the lignocellulose spinning solution according to the invention is used as lignocellulose spinning solution in the process.

There is further provided a regenerated fiber of lignocellulose, which can be prepared by the process according to the invention. The regenerated fiber according to the invention can be produced inexpensively, since in the lignocellulose spinning solution as lignocellulose native wood raw material can be dissolved d. H. Cost-intensive pretreatment of lignocellulose (eg by chemical processes) is not required.

The regenerated fiber according to the invention preferably has one according to DIN 53834 measured strength of at least 20 cN / tex, preferably a strength of 20 cN / tex to 50 cN / tex, on. Furthermore, the regenerated fiber according to the invention can be distinguished by an E-modulus of at least 1000 cN / tex, preferably an E-modulus of 1000 cN / tex to 2500 cN / tex.

• a) Lignin von mindestens 5 Gew.-%, bevorzugt von 5 bis 35 Gew.-%
• b) Hemicellulose von mindestens 5 Gew.-%, bevorzugt von 5 bis 35 Gew.-%; und/oder
• c) Cellulose von mindestens 30 Gew.-%, bevorzugt 30–70 Gew.-%, aufweisen.

The regenerated fiber may contain a content

• a) Lignin of at least 5% by weight, preferably from 5 to 35% by weight
• b) hemicellulose of at least 5% by weight, preferably from 5 to 35% by weight; and or
• c) cellulose of at least 30 wt .-%, preferably 30-70 wt .-%, have.

The regenerated fiber according to the invention can be used for example as a textile fiber and / or as a reinforcing fiber for composites with thermoplastic materials.

The subject according to the invention is intended to be explained in more detail with reference to the following examples, without wishing to restrict it to the specific embodiments presented here.

Example 1: Preparation of the ionic liquids

• – 1-Butyl-methylimidazoliumpivalat;
• – 1-Butyl-3-methylimidazoliumcyclohexylcarboxylat;
• – 1-Ethyl-3-methylimidazoliumcrotonat;
• – 1-Ethyl-3-methylimidazoliumcyclohexylcarboxylat; und
• – 1-Ethyl-3-methylimidazoliumacetat (als Vergleichssubstanz)

As ionic liquids were used:

• - 1-butyl-methylimidazolium pivalate;
• 1-butyl-3-methylimidazolium cyclohexylcarboxylate;
• 1-ethyl-3-methylimidazolium crotonate;
• 1-ethyl-3-methylimidazolium cyclohexylcarboxylate; and
• 1-ethyl-3-methylimidazolium acetate (as reference substance)

These were determined according to standard methods known from the literature ( WO 2009/040242 A1 ) produced.

For example, 7706 g of 27.8% methanolic solution of 1-butyl-3-methylimidazoliummethylcarbonate (10 mol) with 1282 g of cyclohexanecarboxylic acid (10 mol) are heated to 50 ° C. with stirring for 2 h. Subsequently, the methanol is removed on a rotary evaporator. After further drying at 400 ° C in vacuo over P ₂ O ₅ about 2700 g of 1-butyl-3-methylimidazolium cyclohexylcarboxylate are obtained. The IL has a melting point of about 35 ° C at a water content <0.5% (Karl Fischer titration), and a methanol content of about 1% ⁽¹ H NMR).

Example 2: Wheat lignocellulose dissolved in 1-butyl-3-methylimidazoliumccylohexylcarboxylate

To 280 g of air-dry wheat lignocellulose 2300 g of 1-butyl-3-methylimidazoliumcyclohexylcarboxy-lat are mixed and dissolved in a horizontal kneader at a temperature of 130 ° C within 5 h. The resulting black, viscous solution is virtually free of fiber residues and has a zero shear viscosity, measured at 80 ° C, of 1200 Pas. To increase the quality of the spinning solution, it was filtered. The solution was then forced through a 40-hole spinneret with the aid of an extruder (hole diameter 200 μm) and stretched in the air gap at a draft ratio of 4. The filaments were dropped in the aqueous coagulation bath. The washing of the filaments was carried out with distilled water, the drying was carried out at 105 ° C by means of heated rollers.

The filaments had a strength of 27 cN / tex, an elongation of 2.9%, and an E modulus of 1800 cN / tex.

Example 3: Hemp straw lignocellulose dissolved in 1-butyl-3-methylimidazolium cccylohexylcarboxylate

To 280 g of air-dry hemp straw 2300 g of 1-butyl-3-methylimidazoliumcyclohexylcarboxylat be mixed and dissolved in a horizontal kneader at a temperature of 130 ° C within 3 h. The resulting black suspension is almost free of fiber residues and has a zero shear viscosity, measured at 80 ° C, of 1500 Pas. The solution was extruded through an extruder through a 40-hole spinneret (hole diameter 200 μm) and stretched in the air gap at a draft ratio of 6. The filaments were precipitated in an aqueous coagulation bath. The washing of the filaments was carried out with distilled water, the drying was carried out at 105 ° C by means of heated rollers.

The filaments had a tenacity of 22 cN / tex, an elongation of 4.3%, and an modulus of elasticity of 1351 cN / tex.

Example 4: Wheat lignocellulose dissolved in 1-butyl-3-methylimidazolium cyclohexylcarboxylate

To 325 g of air-dry wheat lignocellulose 2300 g of 1-butyl-3-methylimidazoliumcyclohexyl-carboxylate are mixed and dissolved in a horizontal kneader at a temperature of 130 ° C within 4 h. The resulting black, highly viscous solution is virtually free of fiber residues and has a zero shear viscosity, measured at 80 ° C, of 2300 Pas. The solution was extruded through an 80-hole spinneret with the aid of an extruder (hole diameter 100 μm) and stretched in the air gap at a draft ratio of 8. The filaments were dropped in the aqueous coagulation bath. The washing of the filaments was carried out with distilled water, the drying was carried out at 105 ° C by means of heated rollers.

The filaments had a tenacity of 36 cN / tex, 2100 cN / tex.

Example 5: Wheat lignocellulose dissolved in 1-ethyl-methylimidazolium acetate (comparative example)

To 320 g of wheat lignocellulose 2700 g of 1-ethyl-3-methylimidazoliumacetat are mixed and dissolved in a horizontal kneader at a temperature of 130 ° C within 6 h. The resulting black solution is virtually free of fiber residues and has a zero shear viscosity, measured at 80 ° C, of 200 Pas. The solution was extruded through an 40-hole spinneret with the aid of an extruder, but threading was not possible because of the appearance of discontinuities directly at the die.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1980653 A2 [0005]
• US 2008/0241536 [0005]
• WO 2006/000197 A1 [0005]
• WO 2005/017001 A1 [0006, 0007]
• US 2008/0188636 A1 [0006]
• WO 2008/043837 A1 [0007]
• WO 2009/105236 A1 [0007]
• WO 2007/112090 A2 [0008]
• US 2008/0188636 A [0009]
• WO 2009/040242 A1 [0052]

Cited non-patent literature

• Kraft Process, Sulfite Process, Kirk-Othmer, Encyclopedia of Chemical Technology, 1996, 4th Ed., Vol. 20, pp. 493-546 [0003]
• Braun et al. in Carbon 2005, 43, 385-394 [0004]
• ME Zakrzewska et al. in Energy Fuels 2010, 24 pp. 737-745 [0005]
• P. Mäki-Arvela et al. in Industrial Crops and Products 2010, 32, pp. 175-201 [0005]
• Zhu, et al. in Green Chem. 2006, 8, pp. 325-327 [0005]
• N. Sun in Green Chem, 30 2009, 11, p. 646-655 [0007]
• I. Kilpeläinen et al. in J. Agric. Food Chem. 2007, 55, p. 9142-9148 [0007]
• Sun et al. (in Green Chem., 2011, 13, pp. 1158-1161) [0009]
• Sun et al. [0010]
• DIN 53834 [0047]

Claims (29)

Lignocellulose spinning solution containing a solution of lignocellulose in at least one ionic liquid, said at least one ionic liquid consisting of a 1-alkyl-3-methylimidazolium cation and a substantially hydrophobic carboxylate anion, characterized in that the spinning solution Contains lignocellulose in a concentration of at least 10 wt .-% and a zero-shear viscosity, measured at 80 ° C, of ≤ 30000 Pas. Lignocellulose spinning solution, characterized in that the carboxylate anion contains or consists of more C atoms than atoms of group 15, 16 and / or 17 of the periodic table. Lignocellulose spinning solution according to claim 1, characterized in that the carboxylate anion contains no hydrophilic group except at least one carboxyl group. Lignocellulose spinning solution according to one of the preceding claims, characterized in that the carboxylate anion has 3 to 18, preferably 3 to 12, particularly preferably 4 to 7, carbon atoms or consists thereof. Lignocellulose spinning solution according to one of the preceding claims, characterized in that the carboxylate anion a) has at least one double bond, in particular in the case of a C3, C4 and / or C5 carboxylate anion; b) is at least partially branched, in particular in the case of a C4, C5 and / or C6 carboxylate anion; and or c) is at least partially cyclic, especially in the case of a C6 or C7 carboxylate anion. Spinning solution according to one of the preceding claims, characterized in that the carboxylate anion is selected from the group consisting of 2,2-dimethylpropanate anion, 2-butenate anion and cyclohexylcarboxylate anion. Spinning solution according to one of the preceding claims, characterized in that the spinning solution is prepared by the lignocellulose is mixed with water and / or an aliphatic alcohol and in the ionic liquid at a temperature ≤ 140 ° C, preferably ≤ 130 ° C, within a Time ≤ 5 h with at least partial separation of the water and / or aliphatic alcohol is dissolved, wherein the preparation is preferably carried out in a stirring unit or kneading unit. Spinning solution according to one of the preceding claims, characterized in that the spinning solution contains lignocellulose in a concentration of 10 to 35 wt .-%, preferably from 10 to 30 wt .-%. Dyestuff solution according to one of the preceding claims, characterized in that the alkyl radical at position 1 in the 1-alkyl-3-alkylimidazolium cation is a substituted or unsubstituted C ₁ -C ₆ alkyl radical or an aryl radical, preferably selected from Group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, allyl, benzyl, imidazolyl, methoxymetyl, methoxyethyl and ethoxyethyl, most preferably ethyl and butyl. Spinning solution according to one of the preceding claims, characterized in that the lignocellulose a) lignin in a proportion of at least 5 wt .-%, particularly preferably 5 to 35 wt .-%; b) hemicellulose in an amount of at least 5% by weight, more preferably from 5 to 35% by weight; and or c) cellulose in a proportion of at least 30 wt .-%, preferably 30 to 70 wt .-%; in relation to the total weight of lignocellulose. Spinning solution according to one of the preceding claims, characterized in that the lignocellulose wood raw material of at least one plant, preferably at least one year old plant or at least one tree, more preferably at least one plant selected from the group consisting of wheat, rye, corn, hemp, flax, poplar and / or beech, contains or consists of. Dyestuff solution according to one of the preceding claims, characterized in that the spinning solution is a homogeneous particle-free spinning solution, which was preferably prepared by filtering the spinning solution. Spinning solution according to one of the preceding claims, characterized in that the spinning solution has a zero shear viscosity, measured at 80 ° C, from 500 Pas to 3000 Pas, preferably 1000 Pas to 2500 Pas. Spinning solution according to one of the preceding claims, characterized in that the spinning solution contains ≤ 5 vol .-%, preferably ≤ 2 vol .-%, particularly preferably ≤ 1 vol .-%, water. An air-gap spinning process for producing a regenerated fiber of lignocellulose, the process comprising the steps of: a) pressing a lignocellulosic spinning solution containing at least 10% by weight of lignocellulose in at least one ionic liquid and a zero shear viscosity, measured at 80 ° C, of ≤ 30000 Pas, through at least one opening at least one spinneret, wherein at least one thread is formed; b) stretching the at least one thread in at least one air gap; and c) solidification of the at least one thread in at least one precipitation bath. A method according to claim 15, characterized in that the spinning solution is adjusted to a temperature of 60 to 150 ° C, preferably 80 to 130 ° C, particularly preferably 90 to 120 ° C. Method according to one of claims 15 to 16, characterized in that the spinning solution is pressed through an opening of the at least one spinneret, which has a diameter of more than 100 microns, preferably a diameter of 100 microns to 600 microns. Method according to one of claims 15 to 17, characterized in that the at least one thread in at least one air gap with a length of at least 20 mm, preferably with a length of 20 to 500 mm, is stretched. Method according to one of claims 15 to 18, characterized in that the at least one thread with a delay ratio of 2 to 10, preferably 3 to 9, particularly preferably 4 to 8, is stretched. Method according to one of claims 15 to 19, characterized in that the at least one thread is solidified in at least one precipitation bath, which contains a liquid selected from the group consisting of water, polymer solvent, ionic liquid and aliphatic C ₁ -C ₈ alcohol or thereof consists. Method according to one of claims 15 to 20, characterized in that the at least one thread after solidification in at least one precipitation bath is dried in a further step, preferably at a temperature of at least 80 ° C, more preferably at a temperature of at least 100 ° C. Method according to one of claims 15 to 21, characterized in that the at least one thread is equipped with at least one spinning oil, wherein the at least one thread preferably after the solidification of the at least one thread in a precipitation bath and / or after drying the at least one Thread is equipped with a minimum of spin oil. Method according to one of claims 15 to 22, characterized in that the spinning solution has a zero shear viscosity, measured at 80 ° C, from 500 Pas to 3000 Pas, preferably 1000 Pas to 2500 Pas. Method according to one of claims 15 to 23, characterized in that prior to step a), a homogenization of the spinning solution and liberation of the spinning solution of particles, preferably by filtration of the spinning solution is performed. Method according to one of claims 15 to 24, characterized in that a lignocellulosic spinning solution according to one of claims 1 to 14 is used. Regenerate fiber of lignocellulose, preparable by a process according to one of claims 15 to 25. Regenerate fiber according to claim 26, characterized in that it according to DIN 53834 a a) strength of at least 20 cN / tex, preferably 20 cN / tex to 50 cN / tex; and or b) an E modulus of at least 1000 cN / tex, preferably 1000 cN / tex to 2500 cN / tex; having. Regenerated fiber according to one of claims 26 or 27, characterized in that the fiber has a content a) Lignin of at least 5% by weight, preferably from 5 to 35% by weight b) hemicellulose of at least 5% by weight, preferably from 5 to 35% by weight; and or c) cellulose of at least 30% by weight, preferably 30-70% by weight, having. Use of the regenerated fiber according to any one of claims 26 to 28 as a textile fiber and / or as a reinforcing fiber for composites with thermoplastics.