Method for making a cellulosic fiber or film

Abstract

According to an exemplary aspect of the invention, a method for producing cellulose fibers or membranes is provided, the method comprising the step of: dissolving pulp in a cationic 1,5,7-triazabicyclo[4.4.0]dec-5-enium [TBDH] selected from the group consisting of formulas a), b), and c). + In partial and anionic ionic liquids, to provide spinning solutions, wherein R, R 2 R 3 R 4 R 5 R 7 R 8 R 9 and R 10 Each is either H or an organic group, and X ‑ Selected from: halide ions, halide-like ions, carboxyl ions, alkyl sulfite ions, alkyl sulfate ions, dialkyl phosphite ions, dialkyl phosphate ions, dialkyl phosphonite ions, and dialkyl phosphonate ions; extruding the spinning solution through a spinneret to form one or more filaments; and selected from the steps of: spinning cellulose fibers from a solution and extruding cellulose membranes from a solution.

Description

[0001] field

[0002] This invention relates to methods for producing cellulose fibers or membranes. The invention also relates to the use of ionic liquids with enhanced hydrothermal stability for dissolving pulp, and to cellulose solutions in ionic liquids with enhanced hydrothermal stability suitable for spinning cellulose fibers.

[0003] background

[0004] The textile market includes conventional apparel textiles and the increasingly important technical textiles (TT), which are used primarily for their performance or functional characteristics rather than their aesthetic appeal, or for non-consumer (i.e., industrial) applications. The apparel textile market is primarily (80%) based on cotton or polyester, both of which have problematic environmental impacts. Cotton production requires significant amounts of water, artificial fertilizers, and pesticides. Despite the unsustainable nature of cotton cultivation, its properties are favored by consumers because of its pleasant feel ("skin-friendly") and its status as a natural fiber, making it biodegradable. In both value and volume, the consumption of technical textiles is growing four times faster than that of apparel. In 2011, the global market value of technical textiles reached €100 billion, with particularly rapid growth in Asia. Viscose or other lignocellulosic fibers account for only 6% of the overall fiber market. Global TT consumption grew by 41% between 1995 and 2005. Approximately one-quarter of the raw materials used in technical textiles are based on natural fibers (cotton, wood pulp), amounting to 3.8 million tons in 2005. The global nonwovens market comprised 7.05 million tons, with a corresponding market value of approximately €19.8 billion in 2010, and is projected to increase to 10 million tons by the end of 2016. The average growth rate (2010-2015) for all nonwovens and sustainable nonwovens was 8.5% and 12.7% respectively, but in some sectors, annual growth exceeded 25%. Growth is expected to accelerate further due to the enhanced nature of sustainable materials. In terms of volume, the main market segments for nonwovens are: hygiene (31.8%), construction (18.5%), wipes (15.4%), and filtration (4.0%). The global fiber market totaled 89.4 million tons in 2014 and is projected to grow by approximately 10% by 2020. The MMCF share of this global market was 6.7%, or 6 million tons, and is projected to grow by 6% by 2020. Current MMCF production capacity cannot meet future demand, and the cellulose shortage is expected to reach 10-20 million tons per year by 2030.

[0005] Currently, approximately three-quarters of the world's man-made cellulose fibers are produced using viscose methods. However, from an environmental perspective, whether viscose technology should be further promoted is questionable. The extensive use of CS2 and corrosive agents leads to harmful byproducts such as SO2. x And H2S gases, which can put serious stress on labor and the environment. Alternatively, the so-called Lyocell process can convert pulp into a value-added product by direct dissolution in NMMO monohydrate. The first patent for manufacturing Lyocell fibers was filed by American Enka / Akzona Inc. (US 4246221), and later by Courtauld and Lenzing AG (EP0490870). Wood pulp is dissolved in a hot solution of N-methylmorpholine N-oxide monohydrate, and unlike the viscose process, the spinning solution is not directly extruded into the coagulation medium (wet spinning), but rather through an air gap, where it holds the liquid filament for a short period. By drawing the fibers before and during the coagulation zone, the characteristic high tensile strength of Lyocell fibers is obtained, which, unlike viscose, remains at a high level even under wet conditions. However, the versatility of the Lyocell process is limited by some inherent properties of NMMO caused by its unique structure. The NO component hinders the action of redox activators, while the cyclic ether structure tends to undergo so-called thermal runaway reactions, requiring suitable stabilizers. Ionic liquids (ILs) offer the possibility of circumventing these problems. WO 03 / 029329A2 claims the possibility of dissolving and regenerating cellulose in a variety of ionic liquids. DE 102005017715 A1 and WO 2006 / 108861 A2 describe the dissolution of cellulose in various ionic liquids and in mixtures of ILs and amine bases, respectively. In WO2007 / 101812A1, the intentional uniform degradation of cellulose in ionic liquids is demonstrated. Details regarding fiber spinning from ionic liquid solutions can be found in DE102004031025B3, WO 2007 / 128268 A2, and WO 2009 / 118262 A1. The solvents described in these patents are primarily based on imidazolium halides and carboxylates. Halides are characterized by their significant corrosiveness to metalworking equipment and the requirement for high processing temperatures, which leads to significant degradation of cellulose. Carboxylates, particularly 1-ethyl-3-methylimidazolium acetate, exhibit poor viscoelastic properties for fiber spinning.

[0006] Previously, solvents based on 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) have been described as excellent solvents for cellulose processing (WO2014 / 162062A1). In particular, [DBNH]carboxylates can dissolve cellulose at moderate temperatures for short periods. This greatly helps maintain the integrity of cellulose and saves energy and costs. Furthermore, they exhibit excellent spinnability in dry-jet wet Lyocell-type spinning processes to produce fibers with excellent mechanical properties. The resulting fibers are similar to or slightly superior to Lyocell fibers. Notably, ILs are inherently safer than NMMOs, which are prone to spontaneous thermal runaway reactions. Stabilizers are required; however, stabilizers can only minimize the risk of accidents, not guarantee 100% safe operation. For future processes, a safe technological foundation is clearly a decisive asset, even a critical requirement.

[0007] A key unit operation in the Lysell process is the recycling of the solvent from the spinning and washing baths. This involves removing the antisolvent, typically water, through various evaporation stages. This imposes thermal stress on the solvent-antisolvent mixture and can lead to degradation or other side reactions. This results in highly undesirable solvent loss and requires strategies to reverse the (degradation) reaction and restore the original solvent structure. Furthermore, solute (cellulose) degradation can occur during dissolution, filtration, degassing, and spinning operations, with the respective degradation products accumulating in the coagulation bath. NMMO is known to induce a variety of cellulose degradation reactions. Stabilizers can only prevent them to a limited extent. This reduces cost competitiveness through material loss and additional purification steps in solvent recovery. Additional solvent-derived degradation products can exacerbate the removal of carbohydrates from the recycled solvent. Invention Overview

[0009] The object of this invention is to overcome at least some of the aforementioned disadvantages and to provide a method for producing cellulose fibers or membranes, wherein pulp is dissolved in a TBD-based ionic liquid and spun into textile fibers in a dry-jet wet spinning process. The solvents are characterized by their ability to rapidly dissolve wood pulp and their enhanced hydrothermal stability, particularly during solvent recycling. The resulting solution is solid or exhibits high viscosity at low temperatures, but is a processable viscoelastic solution at moderately elevated temperatures (≤100°C).

[0010] This invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0011] According to a first aspect of the invention, a method for producing cellulose fibers or membranes is provided, comprising the step of dissolving pulp in a cationic 1,5,7-triazabicyclo[4.4.0]dec-5-enium [TBDH] selected from the group consisting of formulas a), b), and c). +In partially and anionic ionic liquids, to provide spinning solutions,

[0012]

[0013] Among them, R, R 2 R 3 R 4 R 5 R 7 R 8 R 9 and R 10 Each is either H or an organic group, and X - Selected from: halide ions, halide-like ions, carboxyl ions, alkyl sulfite ions, alkyl sulfate ions, dialkyl phosphite ions, dialkyl phosphate ions, dialkyl phosphonite ions, and dialkyl phosphonate ions; and extruded from the spinning solution through a spinneret to form one or more filaments.

[0014] According to a second aspect of the invention, a cationic 1,5,7-triazabicyclo[4.4.0]dec-5-enium [TBDH] is provided, selected from the group consisting of formulas a), b), and c). + Partially and anionic ionic liquids are used to dissolve pulp.

[0015]

[0016] Among them, R, R 2 R 3 R 4 R 5 R 7 R 8 R 9 and R 10 Each is either H or an organic group, and X - Selected from: halide ions, halide-like ions, carboxyl ions, alkyl sulfite ions, alkyl sulfate ions, dialkyl phosphite ions, dialkyl phosphate ions, dialkyl phosphonite ions, and dialkyl phosphonate ions.

[0017] According to a third aspect of the invention, a cellulose solution is provided comprising cellulose derived from pulp and an ionic liquid having enhanced hydrothermal stability, said ionic liquid comprising the cation 1,5,7-triazabicyclo[4.4.0]dec-5-enium [TBDH]. + Parts and anions, selected from the group according to formulas a), b), and c):

[0018]

[0019] Among them, R, R 2 R 3 R 4 R 5 R7 R 8 R 9 and R 10 Each is either H or an organic group, X - The solution is selected from: halide ions, halide-like ions, carboxyl ions, alkyl sulfite ions, alkyl sulfate ions, dialkyl phosphite ions, dialkyl phosphate ions, dialkyl phosphonite ions, and dialkyl phosphonate ions, and is suitable for spinning cellulose fibers.

[0020] According to a fourth aspect of the invention, a cationic 1,5,7-triazabicyclo[4.4.0]dec-5-enium [TBDH] is provided, selected from the group consisting of formulas a), b), and c). + The use of partially and anion-recycled ionic liquids in the preparation of cellulose fibers or membranes.

[0021]

[0022] Among them, R, R 2 R 3 R 4 R 5 R 7 R 8 R 9 and R 10 Each is either H or an organic group, X - Selected from halide ions, halide-like ions, carboxyl ions, alkyl sulfite ions, alkyl sulfate ions, dialkyl phosphite ions, dialkyl phosphate ions, dialkyl phosphonite ions, and dialkyl phosphonate ions.

[0023] This invention offers considerable advantages. Surprisingly, it has been discovered that cellulose solutions in TBD-based ionic liquids possess viscoelastic properties, which are excellent for dry-jet wet spinning in which the filaments must withstand high draw ratios. The excellent spinnability results in fibers with properties exceeding those of currently commercially available Lyocell fibers. This is quite different from ionic liquids based on other guanidine derivatives. Brief description of the attached diagram

[0025] The preferred embodiments will now be examined more closely with the aid of detailed description and reference to the accompanying drawings.

[0026] Figure 1 shows a comparison of the complex viscosity (left) and dynamic modulus (right) of NMMO-cellulose solution, [DBNH]OAc-cellulose solution, and [mTBDH]OAc-cellulose solution.

[0027] Figure 2 This shows the molar mass distribution of the original pre-hydrolyzed sulfate birch pulp and fibers spun from various solvents.

[0028] Figure 3Example structures of ionic liquids suitable for cellulose dissolution, fiber spinning, and with increased hydrolytic stability: R, R 5 and R 7 It is H or an organic group. Additionally, position R... 2 R 3 R 4 R 8 R 9 and R 10 It can be replaced by an organic group, or can simply be a hydrogen atom. The organic group is preferably an alkyl or polyether chain, but most preferably methyl. b) Carboxylate has proven to be the most advantageous. c) 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enonium acetate [mTBDH]OAc.

[0029] Figure 4 This demonstrates a possible reaction mechanism for the hydrolysis of [DBNH][OAc] to [APPH][OAc].

[0030] Figure 5 This demonstrates the possible reaction mechanisms by which [mTBDH][OAc] hydrolyzes to [APmTH][OAc] and [mAPTH][OAc].

[0031] Figure 6 This is a graph (adjusted) showing the mechanical properties of [mTBDH]OAc spun fibers as a function of draft. Fibers spun from a 13 wt% solution were measured at Aalto University; fibers spun from a 14 wt% solution were measured by an external, accredited institution.

[0032] Figure 7 Displaying [mTBDH][OAc] (top) and after heating (bottom) 1 H-NMR spectrum.

[0033] Figure 8 provides 8 images ( Figures 8A-8H The graph shows the relative concentration (in mol%) of ionic liquids and their hydrolysis products relative to time (in days).

[0034] Implementation Plan

[0035] As described above, through the implementation of the scheme, it was surprisingly found that, unlike other guanidine derivatives, cellulose solutions in TBD-based ionic liquids exhibit surprisingly viscoelastic properties, which are excellent for dry-jet wet spinning in which the filaments must withstand high draw ratios. The excellent spinnability results in fibers with properties exceeding those of currently commercially available Lyocell fibers. The particularly favorable viscoelastic properties encountered by the TBD-based IL-cellulose solution allow for mild processing conditions during the unit operations of dissolution, filtration, degassing, and spinning. This low thermal stress is reflected in the almost complete preservation of the molar mass distribution of cellulose.

[0036] Compared to [DBNH][OAc] (WO2014 / 162062A1) in our previous invention on the IONCELL-F method, [mTBDH][OAc] exhibits significantly increased hydrolytic stability (Table 1). [DBNH][OAc] has been shown to be unstable under recycling conditions. When solutions of [DBNH][OAc]:H2O (1:1 mol eq) and [mTBDH][OAc]:H2O (1:1 mol eq) were heated, we found that approximately 5 mol% of [DBNH][OAc] hydrolyzed within 15 minutes at 90 °C, while [mTBDH][OAc] hydrolyzed only <0.3% under the same conditions. 90 °C is roughly the condition required for recycling ionic liquids (water evaporation), and a 1:1 molar composition of ionic liquid and water is the condition where hydrolysis is problematic. Even at 130 °C, [mTBDH][OAc] hydrolyzed only ~3% within 15 minutes, thus its hydrolytic stability is greatly increased.

[0037]

[0038] Table 1. Results of preliminary hydrolysis kinetics study.

[0039] Figure 1 shows the complex viscosities of NMMO, [DBNH]OAc, and [mTBDH]OAc-cellulose solutions. Figure 1A ) and dynamic modulus (storage modulus and loss modulus) Figure 1B The comparison, wherein according to at least some embodiments of the invention, is performed by plotting each complex viscosity and dynamic modulus relative to an angular frequency. Figure 1B In the figure, solid symbols represent storage modulus, and open symbols represent loss modulus. As can be seen from the figure, cellulose solutions in (TBD)-ILs, particularly in 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate, exhibit viscoelastic properties similar to their respective solutions in NMMO monohydrate and [DBNH]OAc (see also Table 3). This allows for efficient spinning of the respective solutions in a dry-jet wet spinning process. The required spinning temperature is slightly higher than that required for the [DBNH]OAc solution, but lower than that required for the NMMO-based Lyocell process. This appears to be a characteristic of DBN-based and TBD-based ionic compounds. ILs derived from structurally similar 1,1,3,3-tetramethylguanidine (TMG), such as [TMGH]OAc, cannot be used as spinning solvents. The respective cellulose solutions exhibit strong gel characteristics, which hinder filament extrusion and their drafting in air gaps.

[0040] Figure 2This is a graph showing the differential mass fraction plotted relative to the logarithmic molar mass, where the molar mass distribution is the original pre-hydrolyzed sulfate birch pulp and the fibers spun from various solvents. Comparing the undissolved PHK birch pulp with fibers spun from NMMO, [DBNH]OAc, and [mTDBH]OAc, the graph shows no statistically significant degradation. In other words, the particularly favorable viscoelastic properties encountered by the TBD-based IL-cellulose solution allow for mild processing conditions during the unit operations of dissolution, filtration, degassing, and spinning. This low thermal stress is reflected in the almost complete preservation of the cellulose molar mass distribution.

[0041] Figure 3 This describes example structures of ionic liquids suitable for cellulose dissolution, fiber spinning, and exhibiting increased hydrolytic stability. The ionic liquids typically contain (preferably alkylated) a cationic 1,5,7-triazabicyclo[4.4.0]dec-5-enium [TBDH]. + Partially and anions, wherein the anions have high basicity, based on proton affinity or Kamlet-Taft parameters. R, R 5 and R 7 It is H or an organic group. Additionally, position R... 2 R 3 R 4 R 8 R 9 and R 10 It can be replaced by an organic group or can simply be a hydrogen atom. The organic group is preferably an alkyl or polyether chain, but most preferably methyl. Preferred anions for ionic liquids are halide ions (fluoride, chloride, bromide, and iodide ions), halide-like ions (cyanide, thiocyanate, cyanate), carboxylates (formate, acetate, propionate, butyrate), alkyl sulfites, alkyl sulfates, dialkyl phosphites, dialkyl phosphates, dialkyl phosphonites, and dialkyl phosphonates. Carboxylates have been shown to be the most beneficial. Figure 3 (b) The optimal range of ionic liquid structures based on core TBD is as follows: Figure 3 As shown in c.

[0042] Figure 4 This demonstrates a possible reaction mechanism for the hydrolysis of [DBNH][OAc] to [APPH][OAc]. For a 1:1 molar ratio ionic liquid-water mixture via... 1 The hydrolysis kinetics of [DBNH][OAc] were accurately determined by ¹H-NMR. 5% of [DBNH][OAc] was found to hydrolyze to [APPH][OAc] within 15 minutes at 90 °C.

[0043] Figure 5This demonstrates a possible reaction mechanism for the hydrolysis of [mTBDH][OAc] to [APmTH][OAc] and [mAPTH][OAc]. For a 1:1 molar ratio ionic liquid-water mixture via... 1 H-NMR accurately determined the hydrolysis kinetics of [mTBDH][OAc]. <0.3% of [mTBDH][OAc] was found to hydrolyze to [APmTH][OAc] and [mAPTH][OAc] within 15 minutes at 90 °C.

[0044] Figure 6 This is a graph (adjusted) showing the mechanical properties of [mTBDH]OAc spun fibers as a function of draft. The mechanical properties measured are fineness (dtex) and toughness (cN / tex). Fibers spun from a 13 wt% solution were measured at Aalto University; fibers spun from a 14 wt% solution were measured by an external, accredited institution.

[0045] Figure 7 Displaying [mTBDH][OAc] (top) and after heating (bottom) 1 H-NMR spectrum, that is, using 1 The degree of hydrolysis of [mTBDH][OAc] was measured by ¹H NMR. The ionic liquid-water mixture (1:1 molar ratio) was heated at 90 °C and separately at 130 °C. The integral of [mTBDH][OAc] relative to the two hydrolysis products [APmTH][OAc] and [mAPTH][OAc] was calculated. 1 ¹H NMR analysis showed a degradation of <0.3% within 15 minutes at 90 °C. At a significantly higher temperature of 130 °C, 11.4% hydrolysis was observed within 60 minutes. (APmT: 1-(3-ammonium-propyl)tetrahydro-3-methyl-2(1H)-pyrimidinone; mAPT: 1-[3-(methylammonium-propyl)tetrahydro-2(1H)-pyrimidinone acetate).

[0046] Figure 8 provides 8 images, ( Figures 8A-8H The results show the hydrolysis kinetics of [mTBDH][OAc](A,C,E,G) compared to [DBNH][OAc](B,D,F,H) at 80℃ (AD) and room temperature (EH), with and without 5% water (AB,EF) and without water (CD,GH).

[0047] The embodiments described herein relate to a method for producing cellulose fibers or membranes, the method comprising the step of: dissolving pulp in a cationic 1,5,7-triazabicyclo[4.4.0]dec-5-enium [TBDH] selected from the group consisting of formulas a), b), and c). + In partially and anionic ionic liquids, to provide spinning solutions,

[0048]

[0049] Among them, R, R 2 R 3 R 4 R 5 R 7 R 8 R 9 and R 10 Each is either H or an organic group, and X - Selected from: halide ions, halide-like ions, carboxyl ions, alkyl sulfite ions, alkyl sulfate ions, dialkyl phosphite ions, dialkyl phosphate ions, dialkyl phosphonite ions, and dialkyl phosphonate ions; extruding the spinning solution through a spinneret to form one or more filaments; and selected from the steps of: spinning cellulose fibers from a solution and extruding cellulose membranes from a solution.

[0050] As described above, the ionic liquid used in this embodiment exhibits excellent hydrolytic stability compared to other ionic liquids, such as [DBNH][OAc].

[0051] In one embodiment, the organic group of the cationic moiety is an alkyl group. In another embodiment, the organic group is a polyether chain. In one embodiment, the organic group is a straight-chain or branched alkyl group (typically C1-C6), an alkoxy or alkoxyalkyl group, or a residue containing an aryl moiety. In a preferred embodiment, the organic group is methyl.

[0052] Other embodiments describe the anions of the ionic liquid. In one embodiment, the anion is a halide ion, preferably selected from the following halide ions: fluoride ions, chloride ions, bromide ions, and iodide ions. In suitable embodiments, the anion is a carboxylate ion, preferably selected from the following carboxylate ions: formate ions, acetate ions, propionate ions, and butyrate ions. Carboxylate ions have proven to be the most advantageous anion in the embodiments of the present invention. Carboxylate ions, and especially acetate ions, offer the best trade-off in terms of viscosity, solubility according to the Kamlet-Taft value, and non-corrosiveness. However, other anions are very useful in other embodiments. In one embodiment, the anion is a halide-like ion, preferably selected from the following halide-like ions: cyanide ions, thiocyanate ions, and cyanate ions.

[0053] Various types of pulp can be dissolved in the dissolving step. In one embodiment, the pulp used for dissolving is chemical pulp, such as paper pulp and dissolving pulp, preferably unbleached chemical pulp, suitably bleached chemical pulp, and most preferably bleached dissolving pulp.

[0054] Dissolving pulp can be carried out in a variety of ways. In one embodiment, the dissolving step includes the following steps: contacting 5-20% by weight of the pulp with an ionic liquid to provide a suspension and mixing the suspension in a mixer to dissolve the pulp. Any mixer suitable for mixing ionic liquids and pulp can be used. In one embodiment, mixing is carried out using a vertical kneader system. In one embodiment, mixing is carried out using a filmtruder. In another embodiment, mixing is carried out using an extruder.

[0055] In an embodiment where a mixture of ionic liquid and antisolvent is used for the pre-homogenization and suspension of the solute, the antisolvent is partially removed under reduced pressure during dissolution. In another embodiment, all the antisolvent is removed under reduced pressure during dissolution.

[0056] To promote the dissolution of the pulp, the ionic liquid can be heated. In one embodiment, the ionic liquid is heated to a temperature ranging from 30°C to 150°C, preferably from 50°C to 130°C, and suitably from 80°C, 90°C, 100°C, 110°C or 120°C.

[0057] The embodiments provide spinning solutions for spinning cellulose filaments, fibers, and / or membranes. For the purposes of this invention, the spinning solution is a cellulose solution that, due to the specific viscoelastic properties of the cellulose solution, can be drawn into fibers, filaments, and / or membranes through a spinneret.

[0058] In one embodiment, the dissolving step provides a spinning solution with a zero shear viscosity in the range of 20,000 to 60,000 Pas. In another embodiment, the dissolving step provides a spinning solution with a viscosity in the range of 0.2-2 s. -1 The spinning solution has a dynamic modulus crossover point between 1500-7000 Pa (especially 2000-7000 Pa). Clearly, embodiments of this method provide solutions with viscoelastic properties, which are excellent for dry-jet wet spinning where the filaments must withstand high draw ratios. The viscoelastic properties enable a stable spinning process involving extrusion through a spinneret.

[0059] In another embodiment, the spinning solution is filtered using a pressure filtration device equipped with a metal fleece filter before being extruded through the spinneret. Filtering the spinning solution removes insoluble solid particles and gel particles. Removing such particles promotes spinning and ensures a long service life for the spinning equipment; for example, if insoluble particles are filtered out, the spinneret will not become clogged.

[0060] Similarly, degassing the spinning solution can promote spinning. In one embodiment, the spinning solution is degassed in a heated vacuum environment.

[0061] After dissolving the pulp, in one embodiment, the filtered and degassed spinning solution is transferred to the spinning unit. The spinning solution can be transferred in a thermoplastic state, for example at temperatures above room temperature, typically in the range of 30°C to 150°C, preferably 50°C to 130°C, suitably 80°C, 90°C, 100°C, 110°C or 120°C, and most preferably at temperatures equal to or close to the dissolving, filtering or spinning temperature.

[0062] Alternatively, the spinning solution can be stored and subsequently transferred as a solid. In one embodiment, the spinning solution is transferred in one or more solid blocks at a temperature below its crystallization point. For the purposes of the embodiments described herein, the storage temperature is meant to be in the range of 17°C to 50°C, particularly in the range of 20°C to 30°C, and suitable at 25°C. Solidification of the spinning solution at room temperature is a good indicator of suitable viscoelasticity, but not a prerequisite.

[0063] In another embodiment, the spinning solution is extruded into an air gap. In one embodiment, the filament provided by extrusion is stretched in the air gap. The stretching can include a draw ratio of 1 to 20, preferably 6 to 15. This makes it possible to shape the solution into a filament or film by stretching the filament or film to orient the molecules while it is still in solution.

[0064] Extrusion is carried out at elevated temperatures. In one embodiment, the spinning solution is extruded at a temperature in the range of 60°C to 100°C, preferably 75°C to 95°C, and suitably 80°C to 90°C.

[0065] Different spinnerets can be used in the implementation scheme. In one implementation scheme, the spinning solution is extruded through a multifilament spinneret.

[0066] In another embodiment, the filament is drawn through a spinning bath to regenerate cellulose, said spinning bath containing an antisolvent or a mixture of an antisolvent and an ionic liquid used as a spinning solvent. In one embodiment, the antisolvent is water.

[0067] Fibers spun from hydrothermally stable ionic liquids possess excellent properties. As can be seen from the table below, the properties of fibers spun from cellulose solutions in [mTBDH]OAc are extremely advantageously comparable to those of commercial textile fibers, viscose, modal, and lyocell, as well as fibers spun from NMMO and [DBNH]OAc.

[0068]

[0069] Therefore, the embodiments relate to the production of fibers and membranes. In one embodiment, the method produces cellulose fibers having a dry toughness >35 cN / tex and a wet-to-dry toughness ratio >0.70, preferably a dry toughness ≥40 cN / tex and a wet-to-dry toughness ratio ≥0.80. In another embodiment, the method produces textile fibers. In yet another embodiment, the method produces technical fibers. In one embodiment, the method produces membranes.

[0070] Other embodiments involve the treatment of the ionic liquid solvent. In one embodiment, the ionic liquid is recycled. In one embodiment, the recycling of the ionic liquid is facilitated by the enhanced hydrothermal stability of the TBD-derived ionic liquid. In another embodiment, the ionic liquid is purified by vacuum distillation. In one embodiment, the ionic liquid is purified before or after recycling in the embodiments used in this method. Typically, ionic liquids are recycled for use in embodiments of this method to dissolve pulp to produce cellulose fibers or membranes. Therefore, embodiments involve the use of recycled ionic liquids for the preparation of cellulose fibers or membranes. In one embodiment, the recycled ionic liquid is contacted with pulp to dissolve the pulp, providing a spinning solution, said recycled ionic liquid comprising the cationic 1,5,7-triazabicyclo[4.4.0]dec-5-enium [TBDH]. + Parts and anions, selected from the group according to formulas a), b), and c).

[0071]

[0072] Among them, R, R 2 R 3 R 4 R 5 R 7 R 8 R 9 and R 10 Each is either H or an organic group, and X - Selected from: halide ions, halide-like ions, carboxyl ions, alkyl sulfite ions, alkyl sulfate ions, dialkyl phosphite ions, dialkyl phosphate ions, dialkyl phosphonite ions, and dialkyl phosphonate ions; extruding the spinning solution through a spinneret to form one or more filaments; and selected from the following steps: spinning cellulose fibers from a solution and extruding cellulose membranes from a solution. Example

[0073] Example 1. Preparation of [mTBDH][OAc]

[0074] Over a period of 10 minutes, add 400g of pre-distilled MTBD to 157g of glacial acetic acid in an Erlenmeyer flask. Immerse the flask in an ice bath to prevent the temperature from rising above 80°C. After the addition, shake the mixture thoroughly to obtain 557g of [mTBDH][OAc].

[0075] Example 2. Hydrolysis kinetics of [DBNH][OAc]

[0076] For a 1:1 molar ratio ionic liquid-water mixture via 1 Accurate determination of the hydrolysis kinetics of [DBNH][OAc] by ¹H NMR revealed that 5% of [DBNH][OAc] hydrolyzes to [APPH][OAc] within 15 minutes at 90 °C.

[0077] Example 3. Hydrolysis kinetics experiment of [mTBDH][OAc]

[0078] use 1 The degree of hydrolysis of [mTBDH][OAc] was determined by ¹H NMR. The ionic liquid-water mixture (1:1 molar ratio) was heated at 90 °C and separately at 130 °C. The integral of [mTBDH][OAc] relative to the two hydrolysis products [APmTH][OAc] and [mAPTH][OAc] was calculated. 1 H NMR analysis ( Figure 5 and Figure 7 The study showed that <0.3% degradation occurred within 15 minutes at 90°C. At a significantly higher temperature of 130°C, 11.4% hydrolysis was observed within 60 minutes.

[0079] (APmT: 1-(3-ammonylpropyl)tetrahydro-3-methyl-2(1H)-pyrimidinone; mAPT: 1-[3-(methylammonyl)propyl]tetrahydro-2(1H)-pyrimidinone acetate).

[0080] Example 4. Preparation of spinning solution

[0081] 5-20% by weight of pulp (preferably 10-15% by weight) is mixed in a mixture of TBD-based ionic liquids. The suspension is transferred to a vertical kneader system (or a smaller-scale agitator). Dissolution proceeds rapidly (over a period of 0.5-3 hours) at low speeds (10 rpm) and moderate temperatures (60°C-100°C). The resulting solution is filtered by pressure filtration using a metal wool filter (5 μm absolute fineness) and degassed in a heated vacuum environment. The spinning solution is then transferred to the spinning unit in a hot plastic state or as a solid block at room temperature. Spinning conditions are summarized in Examples 5 and 6.

[0082] Example 5: Spinning of TBD-based dope

[0083] The spinning solution (13% by weight pre-hydrolyzed birch sulfate pulp in [mTBDH]OAc) prepared as described in Example 4 was spun at 84°C through a multifilament spinneret (36 orifices, 100 μm capillary diameter) at an extrusion rate of 1.6 ml / min. The winding speed was systematically varied to set different draw ratios. The properties of the resulting fibers are shown in Table 4 and... Figure 6 The results are presented in the paper. The filaments exhibit excellent spinning stability throughout the entire range studied.

[0084] Example 6: Spinning of TBD-based dope

[0085] The spinning solution prepared as described in Example 4 (14% by weight pre-hydrolyzed birch sulfate pulp in [mTBDH]OAc) was spun at 93°C through a multifilament spinneret (36 orifices, 100 μm capillary diameter) at an extrusion rate of 1.6 ml / min. The winding speed was systematically varied to set different draw ratios. Other parameters and the properties of the resulting fibers are shown in Table 5 and... Figure 6 The results are presented in the paper. The filaments exhibit excellent spinning stability throughout the entire range studied.

[0086]

[0087] Table 3. Key rheological properties of different spinning solutions at their respective spinning temperatures.

[0088]

[0089] Table 4. Mechanical properties of fibers from 13 wt% [mTBD] OAc solution (adjusted, with exceptions in the last row).

[0090]

[0091] Table 5. Mechanical properties of fibers from 14 wt% [mTBD] OAc solution (measured by an external, accredited body).

[0092] Example 7: Hydrolytic stability of [mTBDH][OAc] compared to [DBNH][OAc].

[0093] The hydrolysis kinetics of [mTBDH][OAc] and [DBNH][OAc] were determined using a moisture content ranging from 0 to 5% by weight (representing the relevant range for dissolution and spinning processes). Room temperature was relevant to the transport and long-term storage of the ionic liquids, while 80°C represented the operating temperature for dissolution and spinning processes. The concentrations of the ionic liquids and their hydrolysis products were determined by capillary electrophoresis (CE). The results are shown in Figure 8.

[0094] For pure [mTBDH][OAc], no hydrolysis was observed at room temperature during the 38-day period. The same was applied to pure [DBNH][OAc] for the same storage time; however, after 80 days, the formation of 5 mol% APPAc was observed.

[0095] At 80°C, the [mTBDH][OAc] sample without added moisture showed 6 mol% hydrolysis over 16 days and 20 mol% hydrolysis over 39 days. In the first 16 days, the hydrolysis was due to the formation of [H-mTBDH][OAc], while [A-mTBDH][OAc] was also observed after 39 days. For pure [DBNH][OAc], more than 20 mol% was converted to APPAc after 16 days, and approximately 80 mol% was converted after 39 days. After 80 days, only 8 mol% of the original [DBNH][OAc] remained in the sample, with the remainder hydrolyzed to APPAc.

[0096] During the 39-day study period, the [mTBDH][OAc] sample with 5% wt% added water was also completely stable to hydrolysis at room temperature. In contrast, 8 mol% of [DBNH][OAc] with 5% water hydrolyzed to [APPH][OAc] after 35 days and 10 mol% after 80 days.

[0097] At 80 °C, 38 mol% of [mTBDH][OAc] with 5 wt% added water hydrolyzed after 16 days, and 49 mol% after 39 days. At the end of the 39-day period, 22 mol% of [H-mTBDH][OAc] was observed, while the share of the acetylated form was 27 mol%. For comparison, over 90% of [DBNH][OAc] hydrolyzed within the same timeframe, completely converting to its amide form. After 80 days, only 5 mol% of the original [DBNH][OAc] remained.

[0098] Based on the following findings, [mTDBH][OAc] is superior to [DBNH][OAc]:

[0099] [mTBDH][OAc] exhibits complete hydrolytic stability at room temperature for up to 39 days, even in the presence of 5% by weight added water.

[0100] • It was found that pure [mTBDH][OAc] was 4 times more stable at 80°C than pure [DBNH][OAc] (20 mol% hydrolysis after 39 days compared to 80 mol%), and hydrolyzed 64% slower (20 mol% hydrolysis after 39 days compared to 14 days).

[0101] • In the presence of 5% by weight added water, [mTBDH][OAc] is 5 times more stable to hydrolysis than [DBNH][OAc] (retaining complete IL after 39 days, 51 mol% for [mTBDH][OAc] compared to 10 mol% for [DBNH][OAc]). Hydrolysis is 19 times slower (50 mol% hydrolysis for [mTBDH][OAc] after >39 days compared to <2 days for [DBNH][OAc]).

[0102] Example 8: Recyclability of [mTBDH][OAc]

[0103] The spinning solution prepared as described in Example 4 (13 wt% pre-hydrolyzed birch sulfate pulp in [mTBDH][OAc]) was spun at 85°C through a multifilament spinneret (200 orifices, 100 μm capillary diameter) at an extrusion rate of 5.5 ml / min. The [mTBDH][OAc] solvent was recovered from the condensation bath by using multi-step evaporation to remove water, achieving a residual water content of 2 to 3.5 wt%. The recovered solvent was determined based on capillary electrophoresis (CE), Karl-Fischer titration, and... 1 Characterized by H NMR, and used to prepare the spinning solution for the next cycle without further purification.

[0104] A total of five consecutive spinning cycles were run. No hydrolysis products were detected in the recovered solvent in any of the five runs. The spinnability of the dope prepared with the recovered solvent was comparable to that prepared using fresh solvent. The key rheological properties of the spinning dope are listed in Table 6.

[0105]

[0106] Table 6. Key rheological properties of spinning solutions prepared using recycled [mTBDH][OAc].

[0107] In contrast, when [DBNH][OAc] used for fiber spinning is recycled, the recycled solvent contains 10.3 to 11.9 mol% [APPH][OAc]. This recycled solvent (with a residual water content of 2.9 to 3.5 wt%) cannot dissolve cellulose to prepare spinning solutions and therefore cannot be recycled even once.

[0108] It should be understood that the embodiments of the present invention disclosed herein are not limited to the specific structures, processes, or materials disclosed herein, but extend to their equivalents, as will be recognized by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be restrictive.

[0109] Throughout this specification, any reference to an embodiment or embodiment means that the specific features, structures, or characteristics described in relation to that embodiment are included in at least one embodiment of the invention. Therefore, the phrases "in one embodiment" or "in an embodiment" appearing in various places throughout this specification do not necessarily refer to the same embodiment. Where numerical values ​​are mentioned using terms such as about or substantially, precise numerical values ​​are also disclosed.

[0110] As used herein, for convenience, multiple items, structural elements, constituent elements, and / or materials may be presented in a common list. However, these lists should be interpreted as if each member in the list were individually identified as a separate and distinct member. Therefore, without indication to the contrary, any individual member in such a list should not be construed as a de facto equivalent to any other member in the same list solely based on its presentation in the common group. Furthermore, various embodiments and examples of the invention may be mentioned herein along with alternatives to their various components. It should be understood that such embodiments, examples, and alternatives should not be construed as de facto equivalents to each other, but should be regarded as separate and autonomous expressions of the invention.

[0111] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Numerous specific details, such as examples of length, width, shape, etc., are provided in the following description to provide a full understanding of embodiments of the invention. However, those skilled in the art will recognize that the invention may be practiced without one or more specific details or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring aspects of the invention.

[0112] While the foregoing embodiments illustrate the principles of the invention in one or more specific applications, it will be apparent to those skilled in the art that many modifications in form, usage, and implementation details can be made without inventiveness and without departing from the principles and concepts of the invention. Therefore, the invention is not intended to be limited except for the claims set forth below.

[0113] The verbs “comprising” and “including” are used in this document as open-ended restrictions, neither excluding nor requiring the same presence of unlisted features. Unless otherwise expressly stated, the features listed in the dependent claims may be freely combined with each other. Furthermore, it should be understood that the use of “a” or “an,” i.e., the singular form, throughout this document does not exclude a plurality.

[0114] Industrial applicability

[0115] At least some embodiments of the present invention have been industrially applied in the preparation of shaped cellulose articles formed from cellulose membranes, fibers, and filaments. The articles may be woven or nonwoven, melt-formed, vacuum-formed, or molded in any other manner suitable for articles formed from spun cellulose.

[0116] Reference List

[0117] 1.CAC,CIRFS,Fibre Economic Bureau,National Statistics,The Fibre Year 2015

[0118] 2. Bywater, N. (2011) The global viscose fiber industry in the 21st century–the first 10 years. Lenzinger Ber. 89: 22-29.

[0119] 3. T.,Moosbauer,J.,Kliba,G.,Schlader,S., G., Sixta, H. (2009) Comparative cha-racterisation ofman-made regenerated cellulosefibres.Lenzinger Ber.87:98-105.

[0120] 4.a)Buijtenhuijs,FA,Abbas,M.,Witteveen,AJ(1986)The degradation and stabilization of cellulose dissolved in N-methylmorpholine N-oxide(NMMO).Papier(Darmstadt)40:615-619.b)Rosenau,Thom-as;Potthast,Antje;Sixta,Herbert;Kosma,Paul(2001)The chemistry of side reactions and byproduct formation in the system NMMO / cellulose(Lyocell process).Progressin Polymer Science 26(9):1763-1837.

[0121] 5.Swatloski,RP,Spear,SK,Holbrey,JD,Rogers,RD(2002)Dissolutionof Cellose withIonic Liquids.J.Am.Chem.Soc.124:4974-4975.

[0122] 6.Hummel,M.Michud,A.Tanttu,M.Asaadi,S.Ma,Y.Hauru,LJParviainen,A.King,AT. I.Sixta,H.,Ionic Liquids for theProduction of Man-MadeCellulosic Fibres:Opportunities andChallenges.Adv.Polym.Sci.2016,271,133-168.

[0123] 7.Buijtenhuijs,FA;Abbas,M.andWitteveen,AJ,The degradation andstabilization ofcellulose dissolved in N-methylmorpholine N-oxide(NMMO).Paper 1986,40,615-19.

[0124] 8. Rosenau, T. and Potthast, A. Sixta, H. and Kosma, P., The chemistry of side reactions and by-product formation in the system NMMO / cellulose (Lyocell process).Prog.Polym.Sci.2001,26(9),1763-1837.

Claims

1. A method for producing cellulose fibers or membranes, comprising the steps of: • Dissolve the pulp in a solution containing the cationic 1,5,7-triazabicyclo[4.4.0]dec-5-enium [TBDH] according to formula b). + In partially and anionic ionic liquids, to provide spinning solutions, wherein R, R 2 , R 3 , R 4 , R 5 , R 7 , R 8 , R 9 and R 10 are each H or an organic group, wherein the organic group is an alkyl group; • The spinning solution is extruded through a spinneret to form one or more filaments; and • Select from the following steps: Spinning cellulose fibers from solution, and A cellulose membrane is extruded from the solution.

2. The method according to claim 1, wherein the organic group is methyl.

3. The method according to claim 1, wherein the anion is selected from the following carboxylate groups: formate, acetate, propionate and butyrate.

4. The method according to claim 1, wherein the ionic liquid is an ionic liquid according to formula c): 。 5. The method according to any one of claims 1-4, wherein the pulp used for dissolution is chemical pulp.

6. The method according to claim 5, wherein the chemical pulp is paper pulp or dissolving pulp.

7. The method according to claim 5, wherein the chemical pulp is an unbleached chemical pulp.

8. The method according to claim 5, wherein the chemical pulp is a bleached chemical pulp.

9. The method according to claim 5, wherein the chemical pulp is a bleached dissolving pulp.

10. The method according to any one of claims 1-4 and 6-9, wherein the ionic liquid is heated to a temperature in the range of 30°C to 150°C.

11. The method of claim 10, wherein the ionic liquid is heated to a temperature in the range of 50°C to 130°C.

12. The method of claim 10, wherein the ionic liquid is heated to a temperature of 80°C, 90°C, 100°C, 110°C or 120°C.

13. The method according to any one of claims 1-4, 6-9 and 11-12, wherein the dissolution step provides a spinning solution having a zero shear viscosity in the range of 20,000 to 60,000 Pas.

14. The method according to any one of claims 1-4, 6-9 and 11-12, wherein the dissolving step provides a spin dope having a cross-over point of dynamic modulus between 0.2-2 s -1 and 1500-7000 Pa.

15. The method according to claim 14, wherein the dissolving step provides a spin dope having a cross-over point of dynamic modulus between 0.2-2 s -1 and 2000-7000 Pa.

16. The method according to any one of claims 1-4, 6-9, 11-12 and 15, wherein the spinning solution is filtered using a pressure filtration device equipped with a metal wool filter.

17. The method according to any one of claims 1-4, 6-9, 11-12 and 15, wherein the spinning solution is degassed in a heated vacuum environment.

18. The method according to any one of claims 1-4, 6-9, 11-12 and 15, wherein the spinning solution is transferred to the cylinder of the piston spinning unit.

19. The method according to any one of claims 1-4, 6-9, 11-12 and 15, wherein the spinning solution is transferred in a thermoplastic state at a temperature equal to or close to the dissolving, filtering or spinning temperature.

20. The method according to any one of claims 1-4, 6-9, 11-12 and 15, wherein the spinning solution is transferred in one or more solid blocks at a storage temperature or a temperature below the solidification temperature of the spinning solution.

21. The method according to any one of claims 1-4, 6-9, 11-12 and 15, wherein the spinning solution is extruded into the air gap.

22. The method according to any one of claims 1-4, 6-9, 11-12 and 15, wherein the spinning solution is extruded at a temperature in the range of 70°C to 100°C.

23. The method of claim 22, wherein the spinning solution is extruded at a temperature in the range of 80°C to 95°C.

24. The method of claim 22, wherein the spinning solution is extruded at a temperature in the range of 85°C to 90°C.

25. The method according to any one of claims 1-4, 6-9, 11-12, 15 and 23-24, wherein the spinning solution is extruded through a multifilament spinneret.

26. The method according to any one of claims 1-4, 6-9, 11-12, 15 and 23-24, wherein the filament is drawn through a spinning bath to regenerate cellulose, said spinning bath comprising an antisolvent or a mixture of an antisolvent and an ionic liquid used as a spinning solvent.

27. The method of claim 26, wherein the antisolvent is water.

28. The method according to any one of claims 1-4, 6-9, 11-12, 15, 23-24 and 27, for producing cellulose fibers having: dry toughness > 35 cN / tex and wet-to-dry toughness ratio > 0.

70.

29. The method of claim 28, for producing cellulose fibers, said cellulose fibers having: dry toughness ≥ 40 cN / tex and wet-to-dry toughness ratio ≥ 0.

80.

30. The method according to any one of claims 1-4, 6-9, 11-12, 15, 23-24, 27 and 29, wherein the method is used to produce textile fibers.

31. The method according to any one of claims 1-4, 6-9, 11-12, 15, 23-24, 27 and 29, wherein the method is used to produce technical fibers.

32. The method according to any one of claims 1-4, 6-9, 11-12, 15, 23-24, 27 and 29, wherein the method is used to produce a membrane.

33. The method according to any one of claims 1-4, 6-9, 11-12, 15, 23-24, 27 and 29, wherein the method comprises recycling the ionic liquid.

34. The method according to any one of claims 1-4, 6-9, 11-12, 15, 23-24, 27 and 29, wherein the method comprises purifying the ionic liquid by vacuum distillation.

35. Use of recycled ionic liquids in the method according to any one of claims 1-34.

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