PRODUCTION OF REGENERATED POLYSACCHARIDS

Description

[0001] The invention relates to a method for producing a regenerated polysaccharide, a regenerated polysaccharide produced by the method and provided as a film, and a product made from the regenerated polysaccharide.

[0002] Polysaccharides are carbohydrate polymers composed of at least eleven monosaccharides linked by a glycosidic bond. The most abundant polysaccharide in nature is cellulose. Cellulose is used as a raw material in the paper industry, as well as in the construction, textile, and chemical industries. Furthermore, cellulose and its derivatives have been used for decades in numerous fields such as environmental technology, filtration, and medical applications.

[0003] Cellulose is a biopolymer synthesized by plants. Natural, crystalline cellulose is frequently converted into artificial, regenerated cellulose for processing and manufacturing products. Regenerated cellulose, in this context, refers to cellulose that has been dissolved and then reprecipitated. During this process, swelling and dissolution alter the crystal lattice of the natural cellulose, while the molecular structure of the cellulose remains unchanged. This conversion is irreversible, as regenerated cellulose is the thermodynamically most stable form of cellulose. Cellulose can also be chemically synthesized.

[0004] The processing of cellulose to produce regenerated cellulose fibers and films has been dominated for over a century by the viscose pathway (cellophane-cellulose) and the cuprammonium pathway (cuprophan-cellulose). However, these processes are associated with significant environmental pollution, which in turn leads to a number of economic problems. Therefore, there is a desire for more environmentally friendly, simpler, and energy-efficient methods.

[0005] In recent years, various industrial and non-industrial processes for the production of regenerated cellulose have been developed. Solvents used include non-derivatizing solvents such as lithium chloride / dimethylacetamide (DMAc), N-methylmorpholine N-oxide (NMMO, Lyocell process), alkali / urea, and thiourea. Besides ionic liquids, which are intolerant of water, aqueous solvent mixtures are also used, for example, sodium hydroxide (NaOH) together with highly toxic carbon disulfide (CS₂). However, most of these solvents exhibit disadvantageous properties such as high toxicity or high volatility and / or are expensive. Electrolyte solutions, such as those containing quaternary onium hydroxides like tetrabutylammonium hydroxide (TBAH) or tetrabutylphosphonium hydroxide (TBPH), are more advantageous, as they exhibit low toxicity and thus better environmental friendliness, and allow for easy handling.

[0006] Membranes are typically produced by immersing cellulose films in an antisolvent or by evaporating the solvent. With ammonium-based electrolytes such as TBAH, cellulose films can be preserved on a PTFE surface through "aging" (over a specific, extended period). These films cannot be removed from other surfaces (e.g., glass).

[0007] A process for producing regenerated cellulose using phosphonium-based electrolytes such as TBPH is disclosed in US 2014 / 0212670 A1. In this process, cellulose in the form of flakes or fiber, film, granules, or particles is precipitated using solvents that are more volatile than the solvent used for dissolution. This process displaces water and TBPH. However, according to the applicants' investigations, only fine powders of regenerated cellulose are obtained in practice. The objective is to develop a reliable process for providing regenerated polysaccharides in various forms and products.

[0008] This problem is solved by a method with the features according to claim 1. Further advantageous embodiments and configurations of the invention are described in the dependent and sub-claims, the figures, and the exemplary embodiments. The embodiments of the invention can be advantageously combined with one another.

[0009] A first aspect of the invention relates to a process for producing a solid regenerated polysaccharide, comprising the steps of: S1) Providing a polysaccharide, S2) Dissolving the polysaccharide in at least one electrolytic solvent, wherein the electrolytic solvent is a quaternary onium hydroxide in a concentration of about 40-80 wt% in water, S3) Precipitating the polysaccharide in gelled form by contacting the polysaccharide solution with an electrophilic reagent, wherein the electrophilic reagent is at least one cyclic organic carbonate or at least one polymer of a cyclic organic carbonate, S4) Washing the regenerated polysaccharide.

[0010] The term "regenerated polysaccharide" refers to a polysaccharide that has been dissolved and then precipitated again. During this process, swelling and dissolution alter the crystal lattice of the natural polysaccharide, while the molecular structure of the polysaccharide remains unchanged.

[0011] In the context of this invention, the term "gelled form" refers to a solidified form, also known as a hardened form. In the process according to the invention, the solid is formed in step S3.

[0012] In the process according to the invention, an electrophilic reagent is advantageously used for precipitation. However, the solvent is not replaced (as is standard practice in industrial processes or as described in US 2014 / 212 670 A1), but rather the polysaccharide is precipitated directly by a reaction of the electrophilic reagent with the hydroxide ions of the solvent. When the polysaccharide dissolves, hydrogen bonds are formed between the polysaccharide and, in the case of using TBPH as the solvent, the [TBP]< and [OH]< ions. These bonds are broken upon contact with the electrophilic reagent by reaction with the hydroxide groups. No reaction of the reagent with the polysaccharide occurs. The process advantageously enables the simple and rapid production of powders and films without the use of toxic chemicals. This makes the process economical in terms of time and materials, and also environmentally friendly.The regenerated polysaccharides produced by this process are of high purity. This provides a simple and rapid method that uses non-toxic, recyclable, and water-tolerant chemicals to produce regenerated polysaccharides.

[0013] The polysaccharides to be regenerated can be provided in microcrystalline form, but also in any other form, e.g. artificially, amorphously or produced from biomass.

[0014] The polysaccharide can be, for example, cellulose, starch, chitin, chitosan or glycogen.

[0015] Cellulose is particularly favored as the polysaccharide used in this process. Cellulose and its derivatives have a wide range of applications. The process advantageously enables the production of high-quality regenerated cellulose. Films produced using this method exhibit extremely high homogeneity both within the film and on the surface, which is very smooth. Both of these characteristics indicate a uniform and rapid penetration of the dissolved cellulose by the organic carbonate.

[0016] The cellulose to be regenerated can be provided in microcrystalline form, but also in any other form of cellulose, e.g. artificial, amorphous or produced from biomass.

[0017] In this process, a quaternary onium hydroxide in a concentration of approximately 40–80 wt% in water is used as the electrolytic solvent. Preferably, at least one phosphonium-containing and / or one ammonium-containing onium hydroxide is used. TBPH is particularly preferred. TBAH can also be used, although the amount of dissolved polysaccharide is lower and the dissolution process takes longer than with TBPH.

[0018] The quaternary onium hydroxide may, for example, be a quaternary onium hydroxide as described in US 2014 / 212 670 A1.

[0019] The quaternary onium hydroxide can be, for example, a tetraalkylphosphonium hydroxide whose alkyl groups have 2 to 8 carbon atoms, such as tetraethylphosphonium hydroxide, tetrapropylphosphonium hydroxide, tetrabutylphosphonium hydroxide, tetrapentylphosphonium hydroxide, or tetrahexylphosphonium hydroxide. The quaternary onium hydroxide can also be, for example, tetraphenylphosphonium hydroxide. The quaternary onium hydroxide can also be, for example, a substituted or unsubstituted alkyltriphenylphosphonium hydroxide, such as ethyltriphenylphosphonium hydroxide, butyltriphenylphosphonium hydroxide, pentyltriphenylphosphonium hydroxide, 2-dimethylaminoethyltriphenylphosphonium hydroxide, or methoxymethyltriphenylphosphonium hydroxide.

[0020] The quaternary onium hydroxide can, for example, be a tetraalkylammonium hydroxide whose alkyl groups have 2 to 6 carbon atoms, such as tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide or tetrapentylammonium hydroxide.

[0021] For example, quaternary onium hydroxide is used in a concentration of 50 wt.% in water.

[0022] The polysaccharide can, for example, make up a proportion of 20 wt.% in the solution.

[0023] To dissolve the polysaccharide, the polysaccharide solution can be stirred for about 30 minutes at room temperature (23°C).

[0024] Preferably, an additional solvent is used in step S2. This solvent can be used in addition to the at least one electrolytic solvent. The additional solvent can be added before dissolving the polysaccharide, simultaneously with the electrolytic solvent, or after dissolving the polysaccharide. The ratio of the additional solvent to the electrolytic solvent can be, for example, 1:1. Dimethyl sulfoxide (DMSO) is particularly preferred as the additional solvent. The addition of DMSO reduces the viscosity of the regenerated polysaccharide solution and improves its spreadability when producing films. It also accelerates coagulation. Films produced using DMSO are more flexible than those produced without DMSO and are also transparent.

[0025] In the process, the electrophilic reagent used is (i) at least one organic carbonate, or (ii) a mixture of different organic carbonates, or (iii) at least one polymer of an organic carbonate, or (iv) a mixture of different polymers of organic carbonates, or (v) a mixture of at least one organic carbonate and at least one polymer of an organic carbonate. Organic carbonates are particularly effective in the context of the invention. Organic carbonates cause the polysaccharide solution to solidify immediately without disrupting its overall structure. When the polysaccharide solution comes into contact with the organic carbonate, a chemical reaction occurs between the hydroxide anion of the solvent and the organic carbonate, releasing a diol and carbon dioxide, some of which is dissolved in carbonate.The solvent and the diol can theoretically be recycled and reused in subsequent steps. No reaction occurs with the polysaccharide. A regenerated polysaccharide is formed.

[0026] The organic carbonate can be, for example, propylene carbonate, vinylethylene carbonate, butyl carbonate or ethylene carbonate.

[0027] The organic carbonate can be either cyclic or non-cyclic. Examples of cyclic organic carbonates include propylene carbonate, vinylethylene carbonate, butyl carbonate, ethylene carbonate, or vinyl carbonate. Examples of non-cyclic organic carbonates include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, dibenzyl carbonate, diphenyl carbonate, or tert-butylphenyl carbonate.

[0028] Preferably, propylene carbonate is used as the organic carbonate in the process. Propylene carbonate is particularly advantageous because it is a liquid carbonate at room temperature, sustainably produced from biomass, and therefore easy to use. Propylene carbonate is also inexpensive.

[0029] The polymer of an organic carbonate can, for example, contain 2-1,000,000 monomers.

[0030] The polymer of an organic carbonate can be, for example, polypropylene carbonate.

[0031] The mixture of at least one organic carbonate and at least one polymer of an organic carbonate can, for example, be a mixture of propylene carbonate and polypropylene carbonate.

[0032] Solid organic carbonates are preferably dissolved in the process before use, for example in DMSO. DMSO is particularly suitable for this purpose. This also applies to polymers of organic carbonates. The polymers are solid at room temperature.

[0033] Preferably, at least one organic carbonate or a mixture of different organic carbonates is used in the process.

[0034] The electrophilic reagent is used in step S3 at a concentration of 10–100%, particularly at a concentration of 80–100%. Step S3 is preferably carried out at a temperature in the range of 0–100°C for 0.01–100 hours, particularly preferably at 23°C for 0.01–10 minutes, and more preferably at 23°C for 0.01–6 minutes. This allows the process to be advantageously carried out at room temperature. The process is also very fast.

[0035] The purification of the regenerated polysaccharide in step S4, preferably carried out with water, enables the effective removal of impurities, especially water-soluble impurities, as well as formed organic compounds (propylene glycol) and solvents. This advantageously results in a particularly high purity and a very uniform, homogeneous structure of the regenerated polysaccharide.

[0036] In a preferred embodiment of the process, the regenerated polysaccharide is produced as a film (also referred to as a foil) by spreading the polysaccharide solution after step S2 onto a surface with a spreading tool of defined height, e.g., a doctor blade, in an additional step S2a. This yields a polysaccharide-solvent layer with a defined and uniform thickness. After contact with the organic carbonate, such as propylene carbonate, in step S3, e.g., by immersion in a propylene carbonate bath, the layer is transformed into a film. This results in non-transparent, whitish films. As described above, transparent films can be produced by adding DMSO.

[0037] It was shown that the films produced using the method have a surface potential (zeta potential) in a range of pH 5.0 - 9.0 of an average of -20 mV.

[0038] By introducing the electrophilic reagent and dissolving the solvent from the polysaccharide solution, a permeable (porous), microfibrillated structure forms in films of regenerated polysaccharide produced using this method. It has been shown that the properties of these films are comparable to those of conventionally produced membranes.

[0039] The films can be stored in neutral, slightly alkaline, or slightly acidic media. It has been shown that the pressure stability of the films is maintained under such storage conditions. For this purpose, the pressure stability of the films between 1 and 3 bar was tested in a flow reactor.

[0040] The films can be stored in water, ethanol, or acetone, for example. Preferably, the films are stored in water.

[0041] In a further preferred embodiment of the process, the regenerated polysaccharide is produced in granular form by mechanically comminuting it in an additional step S4a after step S4. By comminuting the solid of regenerated polysaccharide that forms after contact of the polysaccharide solution with the organic carbonate, such as propylene carbonate, followed by washing, highly pure polysaccharide material can be obtained as granules, e.g., in powder form.

[0042] A second aspect of the invention relates to a regenerated polysaccharide produced by the inventive process according to the embodiments described above and provided as a film. The regenerated polysaccharide is preferably regenerated cellulose.

[0043] The regenerated polysaccharide is provided as a film. Preferably, a film made of regenerated cellulose is provided. The films exhibit high homogeneity both within the film and at the surface. The surface is very smooth. The distances (pores) between the fibrils (fibers) are very small, preferably 10–100 nm, and correspondingly selective for specific particle sizes. The films according to the invention can be used, for example, as films or membranes for the selective purification of drinking water. In addition, negatively charged ions can be selectively separated from positively charged ions. Furthermore, the films can be used to produce layers and nanotubes.

[0044] The regenerated polysaccharide is also preferably supplied in granular form. Granules, e.g., in powder form, can be used, for example, as an additive in nutritional or medicinal preparations, in the construction chemicals industry, or in ceramic applications.

[0045] The films and granules produced according to the invention from regenerated cellulose were characterized by methods such as Fourier transform infrared spectrometry, nuclear magnetic resonance spectroscopy, X-ray diffraction, thermal analysis, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, UV / VIS spectroscopy and size exclusion chromatography.

[0046] A third aspect of the invention relates to a product made from a polysaccharide regenerated according to the invention. Such products include, for example, membranes, films, layers, or nanotubes, or compounds with other materials.

[0047] The advantages of the regenerated polysaccharide produced by the process and of the product made from the regenerated polysaccharide correspond to the advantages of the process, insofar as they are not limited to purely process-related aspects.

[0048] Furthermore, a method for producing a solid regenerated polysaccharide is disclosed, comprising the steps: S1) Providing a polysaccharide, S2) Dissolving the polysaccharide in at least one electrolytic solvent, S3) Precipitating the polysaccharide in gelled form by contacting the polysaccharide solution with an electrophilic reagent with the formula or the formula or with a mixture of electrophilic reagents having formulas I and / or II, wherein X is a C=O, C=S, C=NR functionality and Y and Z are the same or different and are independently selected and consist of O, NH, NR, S, CR groups, wherein R is hydrogen and / or a substituted or unsubstituted hydrocarbon residue, and M is a bridge consisting of 0-20 carbon atoms and linear or branched, substituted or unsubstituted hydrocarbon residues, S4) Washing of the regenerated polysaccharide.

[0049] The substituted or unsubstituted hydrocarbon group subsumed under R is in particular an alkyl or aryl group, e.g. an alkyl group with 1 to 20 carbon atoms or with 1 to 8 carbon atoms. Preferably, R is a methyl, ethyl, or n-propyl group.

[0050] Compounds disclosed in US 2014 / 212670 A1 for the precipitation of regenerated cellulose are expressly excluded for use as electrophilic reagents. This applies particularly to alcohols with one to four carbon atoms, e.g., methanol, ethanol, and 2-propanol, as well as ketones such as acetone. In other words, the use of these compounds is excluded from the scope of disclosure in paragraph 1.

[0051] For the purposes of this disclosure, an "electrolytic solvent" is understood to be a dissolved solid consisting of ionic crystals composed of hydroxide ions as negatively charged anions and positively charged cations. Preferably, in the disclosed process, a quaternary onium hydroxide is used as the electrolytic solvent in a concentration of approximately 40–80 wt.% in water. Furthermore, it is also possible to tolerate other protic and aprotic solvents, which can lead to an improvement in flow properties and thus processability.

[0052] The invention is explained in more detail using the figures. They show Figure 1 is a flowchart of a general embodiment of the inventive process for producing regenerated cellulose. Figure 2 is a flowchart of a further embodiment of the inventive process for producing a film. Figure 3 is a flowchart of an embodiment of the inventive process for producing granules. Figure 4 is a diagram for analyzing the permeability of the material produced according to the inventive process. Fig. 2 Produced regenerated cellulose film. Figure 5 shows a diagram (¹³C nuclear magnetic resonance spectroscopy) for analyzing the quality and structure of the regenerated cellulose according to Fig. 2 manufactured film. K. m. Cell. - Commercial microcrystalline cellulose. Figure 6 Diagrams for analyzing the pore size of the film according to Fig. 2 Produced regenerated cellulose film. Figure 7: Diagrams for analyzing the structure of the regenerated cellulose of the film produced according to Fig. 3 granules produced by A) FT-IR spectroscopy, B) X-ray diffraction, and C) nuclear magnetic resonance spectroscopy. Figure 8: Diagrams for the comparative analysis of the structure of regenerated cellulose using four different organic carbonates according to Fig. 3 Granules produced by A) FT-IR and B) X-ray diffraction. Figure 9 shows a light micrograph of a cross-section of a granule produced according to A) FT-IR and B) X-ray diffraction. Fig. 2 Produced regenerated cellulose film. Figure 10: A transmission electron micrograph of a cross-section of a film produced according to Fig. 2 manufactured regenerated cellulose film.

[0053] In a general embodiment of the method according to Fig. 1 Regenerated cellulose is produced. In a first step (S1), natural cellulose in microcrystalline form is provided. Alternatively, the cellulose can also be provided in any other possible form, e.g., synthetic, amorphous, or biomass-derived. In a second step (S2), 20 wt% (200 mg) of the microcrystalline cellulose is dissolved in a 50% aqueous solution of TBPH (1 ml) in a suitable container. The resulting cellulose solution is stirred for approximately 30 minutes at room temperature (23°C). In a third step (S3), propylene carbonate is added to the liquid to initiate coagulation. This immediately converts the cellulose-solvent layer into regenerated cellulose. In a fourth step (S4), the regenerated cellulose is washed with water to remove solvent and any organic compounds that may have formed. Highly purified regenerated cellulose is obtained.

[0054] In one embodiment of the inventive method for producing regenerated cellulose films / sheets according to Fig. 2 The procedure will be analogous to Fig. 1 The process differs in that, in an additional step S2a, the clear solution is spread onto the glass plate, for example, using a doctor blade. This achieves a specific, pre-set thickness of the cellulose-solvent layer (e.g., 300 µm). In a third step S3, the poured liquid is immersed in a propylene carbonate bath for coagulation. This immediately transforms the cellulose-solvent layer into a film of regenerated cellulose. In a fourth step S4, the regenerated cellulose films are washed with water to remove solvents and any organic compounds that have formed, resulting in a highly purified cellulose film. The film is then immediately detached from the glass plate. The films are stored in water until needed.

[0055] The optical properties do not change during this conversion; the cellulose films are whitish and opaque, so the conversion of the cellulose-solvent layer into a cellulose film cannot be visually detected. In a further embodiment of the process according to the invention, DMSO (preferred solvent : DMSO ratio 1 : 1) is added as an additional solvent to the dissolved cellulose in step S2. This results in the production of a transparent cellulose film in step S3. The conversion is also not visually detectable. The use of DMSO also affects the permeability of the films, as demonstrated by a water flow test in films used as membranes according to [reference to relevant document]. Fig. 4 This can be demonstrated. The water flow rate depends primarily on the size and distribution of pores in the membrane. A first membrane without DMSO (RC1) and a second membrane with DMSO (RC2) were produced. In the first film, RC1, the water permeability increased pressure-dependently from 1.6 to 5.4 L*m⁻²*h⁻¹ within a pressure range of 0.5 to 2.1 bar (square data markers). In the second film, RC2, the water permeability increased pressure-dependently from 3.7 to 7.8 L*m⁻²*h⁻¹ within a pressure range of 0.5 to 1.1 bar (round data markers). The evidently higher permeability indicates a clear diluting effect of DMSO on the regenerated cellulose.

[0056] In Fig. 5 The purification effect of the new process and the improved quality of the produced films are demonstrated. The abbreviation "au" stands for arbitrary units. The impurities (sharp signals) are not present in the films. Furthermore, the chemical structure of the membranes RC2 (film 2, top graph) and RC1 (film 1, second graph from the top) corresponds to that of commercial microcrystalline cellulose (abbreviated as K. m. Cell., second graph from the bottom). The bottom graph refers to the solvent (TBPH, 50%).

[0057] In Fig. 6 The pore distribution of both films is shown. The pores have a size of 10-70 nm and are therefore significantly smaller than those of commercially available regenerated cellulose membranes (200-500 nm).

[0058] In a further embodiment of the method according to Fig. 3 A granulate made from regenerated cellulose is produced. Steps S1 and S2 are carried out as described in the [document / section / etc.]. Fig. 1 The described procedure is carried out. In step S3, propylene carbonate (preferably a 10:1 excess of propylene carbonate) is added directly to the cellulose solution. The regenerated cellulose gels or solidifies immediately. In step S4, the solidified regenerated cellulose can be washed with water, e.g., by repeatedly decanting the supernatant or centrifuging, after the cellulose has settled at the bottom of the vessel containing the cellulose and solvent. The regenerated cellulose is preferably dried at 30–100°C and stored as granules until further use. Optionally, the granules can be mechanically crushed in step S4a, e.g., using a pestle or mortar. The size of the granules in the Abb. 3 The granular particles produced by the described process can be varied to produce either a powder or a coarser granulate. The size of the granulate can be adjusted by using appropriate grinding equipment and by varying the intensity of the grinding process (applied force, duration of exposure).

[0059] The produced granules were structurally examined. It was shown that the regenerated cellulose was not chemically modified by the propylene carbonate; that is, no chemical reaction between the cellulose and the propylene carbonate actually takes place. Analysis by Fourier transform infrared spectrometry (FT-IR) shows that no propylene carbonate was incorporated into the cellulose structure. Fig. 7A The upper line indicates propylene carbonate, the middle line regenerated cellulose, and the lower line natural microcrystalline cellulose. The dissolved cellulose is thus regenerated without changes in its chemical structure. Analysis of the granules by X-ray diffraction ( X-Ray diffraction, XRD) shows that a transformation of the macroscopic structure has occurred. Newly appearing reflections at 12.1° and 20.6° in the upper graph (regenerated cellulose) compared to the lower graph (natural cellulose, crystalline cellulose) indicate the formation of the cellulose II structure (regenerated cellulose) ( Fig. 7B ). Analysis by nuclear magnetic resonance ( nuclear magnetic resonance, NMR) showed no changes in chemical structure, as can be seen from the similar shape of the upper graph (regenerated cellulose) compared to the lower graph (natural cellulose) ( Fig. 7C The abbreviation au stands for arbitrary units.

[0060] As an alternative to the propylene carbonate used, other organic carbonates can also be used to obtain regenerated cellulose ( Fig. 8 Using FT-IR ( Fig. 8A ) and X-ray diffraction ( Fig. 8B It was shown that regenerated cellulose with vinylethylene carbonate (top graph), butyl carbonate (second graph from the top), and ethylene carbonate (second graph from the bottom) yields the same structure as cellulose regenerated with propylene carbonate (bottom graph). The abbreviation au stands for arbitrary units.

[0061] In Fig. 9 is a light microscopic image of a cross-section of a according to Fig. 2 The image shows a film produced from regenerated cellulose. The image shows a film (foil) produced without DMSO as an additional solvent (RC1). The film is 200 µm thick. The image demonstrates the excellent homogeneity within the film. It also shows that the film is free of air bubbles.

[0062] In Fig. 10 is a high-resolution transmission electron micrograph (TEM image) of a cross-section of a according to Fig. 2 The image shows a film produced from regenerated cellulose. The image shows a film (foil) produced without DMSO as an additional solvent (RC1). The microfibrillar structure was visualized using uranyl acetate and lead citrate.

[0063] Materials produced from regenerated cellulose can find applications in filter technology. For example, the resulting films can be used as membranes for the selective purification of drinking water.

Claims

1. A process for producing a solid regenerated polysaccharide, comprising the steps of: - S1) providing a polysaccharide, - S2) dissolving the polysaccharide in at least one electrolytic solvent, wherein a quaternary onium hydroxide with a content of about 40-80% by weight in water is used as the electrolytic solvent, - S3) precipitating the polysaccharide in gelated form by contacting the polysaccharide solution with an electrophilic reagent, wherein at least one cyclic organic carbonate, or at least one polymer of a cyclic organic carbonate are used as the electrophilic reagent, - S4) washing the regenerated polysaccharide.

2. The process of claim 1, wherein cellulose is used as polysaccharide.

3. The process of claim 1 or 2, wherein at least one phosphonium-containing and / or at least one ammonium-containing onium hydroxide is used.

4. The process of claim 3, wherein tetrabutylphosphonium hydroxide is used.

5. The process of claim 3, wherein tetrabutylammonium hydroxide is used.

6. The process according to any one of the preceding claims, wherein an additional solvent is used in step S2.

7. The process of claim 6, wherein dimethyl sulfoxide is used as additional solvent.

8. The process according to any one of the preceding claims, wherein the electrophilic reagent is used at a concentration of 80 - 100%.

9. The process of claim 1, wherein propylene carbonate, vinyl ethylene carbonate, butyl carbonate, ethylene carbonate, and / or vinyl carbonate is used as cyclic organic carbonate.

10. The process according to any one of the preceding claims, wherein the regenerated polysaccharide is produced as a film by coating the polysaccharide solution after step S2 on a surface in an additional step S2a.

11. The process according to any one of claims 1 - 10, wherein the regenerated polysaccharide is produced in powder or pelletized form by mechanically comminuting it after step S4 in an additional step S4a.

12. A regenerated polysaccharide produced by a process according to any one of claims 1 - 11, wherein the regenerated polysaccharide is provided as a film, and the distances between the fibres range from 10-100 nm.

13. A product made from a regenerated polysaccharide according to claim 12.