Method for preparing alkaline cellulose concentrate

Abstract

A method of preparing an alkaline cellulose concentrate is disclosed. The method may include providing a cellulosic material and a cold alkaline solution, and dispersing and dissolving the cellulosic material in the cold alkaline solution to obtain an alkaline cellulose concentrate. Providing the cold alkaline solution may include generating an alkaline solution by electrodialysis, thereby reducing or preventing absorption and / or dissolution of CO2 in the cold alkaline solution, and / or reducing the concentration of carbonate ions in the cold alkaline solution.

Description

Technical Field

[0001] The present disclosure relates to a method for preparing an alkaline cellulose dope, an alkali cellulose dope, and products obtainable from the alkali cellulose dope. Background Art

[0002] Dissolution of cellulose is a challenging process; cellulose is a very stable molecule with low reactivity due to its molecular structure with multiple intermolecular and intramolecular hydrogen bonds.

[0003] Methods of dissolving cellulose in an aqueous solvent system are available. For example, cellulose can be dissolved in a cold alkaline solution, such as a 7-10 wt% NaOH solution at a temperature of -5 to 1°C. Such cellulose solutions can be used for spinning and coagulation, such as cellulose fibers.

[0004] However, alkaline cellulose dopes, especially those with relatively high cellulose concentrations, may not be stable for long periods of time.

[0005] In addition, obtaining an alkali cellulose dope with a higher cellulose concentration may be challenging. The viscosity of the alkali cellulose dope is preferably such that it can be formed into various shapes, such as spinning or extruding fibers, from the solution. However, if the concentration of cellulose is increased to increase the viscosity, the alkali cellulose dope is more likely to form a gel-like structure. Such gel-like structures may not have sufficient fluidity for spinning or extrusion. They may also make filtering the alkali cellulose dope and / or transferring it forward in the process more challenging. Summary of the invention

[0006] A method for preparing an alkaline cellulose concentrate is disclosed. The method may include providing a cellulose material and a cold alkaline solution, and dispersing and dissolving the cellulose material in the cold alkaline solution to obtain an alkaline cellulose concentrate. Providing the cold alkaline solution may include generating the alkaline solution by electrodialysis, thereby reducing or preventing CO in the cold alkaline solution. 2 absorption and / or dissolution of, and / or reduction of the concentration of carbonate ions in the cold alkaline solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The accompanying drawings are included to provide a further understanding of the embodiments and constitute a part of this specification, and illustrate various embodiments. In the drawings:

[0008] Figure 1 An embodiment of a method for preparing an alkaline cellulose dope is shown;

[0009] Figure 2Embodiments of a method for preparing an alkaline cellulose dope and a system for operating the method are described;

[0010] Figure 3 An embodiment of a method for preparing an alkaline cellulose dope is shown;

[0011] Figure 4 Another embodiment of an electrodialysis apparatus is shown;

[0012] Figure 5 Another embodiment of an electrodialysis apparatus is shown;

[0013] Figure 6 The Brookfield viscosities of alkaline cellulose dope samples with different carbonate ion concentrations are shown;

[0014] Figure 7 The tenacity of the staple fibers is shown as a function of the stretch between the first godet and the second godet;

[0015] Figure 8 Show the tenacity of the staple fibers as a function of elongation at break; and

[0016] Fig. 9 Shown are the Brookfield viscosities of alkali cellulose dope samples stored in contact with air for 0, 1 and 5 days. DETAILED DESCRIPTION

[0017] In a first aspect, a method for preparing an alkaline cellulose concentrate is disclosed. The method may include:

[0018] providing a cellulosic material and a cold alkaline solution, and

[0019] The cellulose material is dispersed and dissolved in a cold alkaline solution to obtain an alkaline cellulose concentrate,

[0020] Wherein, providing the cold alkaline solution includes generating the alkaline solution by electrodialysis. The generation of the alkaline solution can reduce or prevent the CO 2 absorption and / or dissolution of, and / or reduction of the concentration of carbonate ions in the cold alkaline solution and / or the alkaline cellulose concentrate.

[0021] By electrodialysis, a cold alkaline solution can be produced in a substantially carbonate-free manner. Additionally or alternatively, CO 2 Absorption and / or dissolution in a cold alkaline solution and subsequent absorption and / or dissolution in an alkaline cellulose dope.

[0022] In addition, electrodialysis technology can also recover the sodium sulfate salt formed during the coagulation process. 2 SO 4Salt can be divided into sulfuric acid and pure sodium hydroxide, both of which are the main spinning chemicals.

[0023] CO dissolved in water 2 Carbonic acid is mainly formed. The carbonic acid can further react with alkaline agents present in the cold alkaline solution and / or the alkaline cellulose concentrate.

[0024] Without being bound by theory, the CO absorbed and dissolved in the alkaline cellulose concentrate 2 Carbonates can be formed in alkaline cellulose concentrate. Dissolved CO 2 The carbonic acid and carbonate may have an effect on the pH of the alkali cellulose dope and may thereby produce local points where gelation occurs. Such gel points may reduce the stability of the alkali cellulose dope. The CO absorbed and dissolved in the alkali cellulose dope 2 It may also reduce the solubility of cellulose.

[0025] The carbonates thus formed, or otherwise contained in the alkali cellulose dope, may also end up in the product obtained from the alkali cellulose dope. Under acidic conditions, carbonates may cause CO 2 The formation of CO and then when the product is condensed from the alkaline cellulose concentrate 2 May increase the porosity of the product. Increased porosity may reduce the strength of the product, such as the strength of short fibers.

[0026] Therefore, if the alkaline cellulose concentrate contains CO 2 absorption and / or dissolution reduction of CO2 and / or CO2 dissolved in the cellulosic material and the cold alkaline solution and / or in the alkaline cellulose concentrate 2 By at least partially removing or reducing the amount of carbonate in the cold alkali solution and / or alkali cellulose concentrate, the amount of carbonate in the cold alkali solution and / or alkali cellulose concentrate can be reduced.

[0027] In the context of this specification, the term "carbonate" may refer to carbonates such as Na 2 CO 3 , and / or bicarbonates such as NaHCO 3 , and / or refers to carbonate and / or bicarbonate ions. Carbonate can further form bicarbonate, so that carbonate and bicarbonate ions are in equilibrium, and the molar ratio of carbonate to bicarbonate depends on, for example, the pH value. For example, in alkaline cellulose concentrates, the pH value is often high, so that carbonate is mainly present as carbonate ions (CO 3 2-) in the form of. In other solutions, such as in water, there may be a large amount of bicarbonate. The method for determining the amount or concentration of carbonate can determine both carbonate and bicarbonate simultaneously, so that any reference to the amount of carbonate, carbonate content and / or concentration of carbonate ions can refer to the amount of carbonate and bicarbonate and / or the concentration of carbonate and / or bicarbonate ions.

[0028] If compared to a comparable process, such as a process that does not include one or more of the methods described in this specification to reduce CO in the cold alkaline concentrate, 2 Compared with comparable processes using absorption and / or dissolution measures (e.g., electrodialysis to generate an alkaline concentrate), CO in cold alkaline solutions 2 If the absorption and / or dissolution is reduced by at least 10%, or at least 20%, or at least 50%, then the CO in the cold alkaline solution may be considered to be 2 The absorption and / or dissolution is reduced.

[0029] If compared to comparable processes, e.g., processes that do not include one or more of the processes described in this specification that reduce CO in the (cold) alkaline solution and / or alkaline cellulose concentrate, 2 If the concentration of carbonate ions in the (cold) alkaline solution and / or alkaline cellulose concentrate is reduced, for example, by at least 10%, or at least 20%, or at least 50%, compared to a comparable process in which measures are taken to absorb and / or dissolve or reduce the concentration of carbonate ions, then the concentration of carbonate ions in the (cold) alkaline solution and / or alkaline cellulose concentrate is considered to be reduced.

[0030] In some embodiments, if the concentration of carbonate ions in the cold alkaline solution is 1.5% (w / w) or less, or 1.2% (w / w) or less, or 1.0% (w / w) or less, or 0.2% (w / w) or less, or 0.1% (w / w) or less, then it can be considered that the cold alkaline solution has a CO concentration of 1.5%. 2 The absorption and / or dissolution is reduced. The concentration is understood to be the concentration based on the total weight of the (cold) alkaline solution.

[0031] The concentration of carbonate ions can be measured using the standard SCAN-N 32:98. This standard is suitable for white, green and black liquors as well as burnt lime sludge, but can also be used for other samples. The accuracy and detection limit of the method can be improved by increasing the weight of the sample or reducing the volume of the absorption cell solution. If the amount of alkaline solution is increased, the volume of the reaction solution (HCl) may also be increased. It may be necessary to take care that the pH of the reaction solution is always below 2 and that the measurement time is long enough to collect all the CO generated by the carbonates. 2 .

[0032] In the context of this specification, the term "alkali cellulose dope" can be understood as a solution comprising cellulose dissolved in an alkaline solution. For example, the alkali cellulose dope can be a cellulose spinning solution (i.e., an alkali cellulose spinning solution) or a cellulose solution (i.e., an alkali cellulose solution) for extrusion, spinning, electrostatic spinning, molding, casting, film forming, film extrusion, cellulose bead production, coating, spraying and / or 3D printing. In other words, it can refer to a cellulose material in an alkaline solution suitable for, for example, spinning filaments, staple fibers, film manufacturing, cellulose bead production and various other uses. The alkali cellulose dope can be condensed into solid cellulose under suitable conditions, for example, condensed into type II cellulose.

[0033] In the second aspect or one embodiment of the first aspect, a method for preparing an alkaline cellulose concentrate is disclosed. The method may include:

[0034] Providing a cellulosic material and a cold alkaline solution,

[0035] The cellulose material is dispersed and dissolved in a cold alkaline solution to obtain an alkaline cellulose concentrate,

[0036] placing the alkaline cellulose concentrate in a storage tank, and

[0037] The alkali cellulose concentrate placed in the storage tank is processed into the desired shape, thereby completing the daily output of the alkali cellulose solution in one day.

[0038] The capacity of the storage tank is sufficient to accommodate a volume of alkali cellulose concentrate equivalent to or less than the daily output.

[0039] When relatively smaller storage tanks are used, the stability of the alkali cellulose concentrate as well as the stability of the process are improved.

[0040] With such a tank, the air space within the tank, i.e., the space within the tank not filled with the alkali cellulose concentrate, can be minimized. Therefore, it is easier to reduce or minimize the CO in the air space. 2 The amount of CO that may be dissolved in the alkali cellulose concentrate can be reduced or minimized. 2 For example, it may be necessary to use a smaller volume of shielding gas in the air space. It may be easier to maintain the required temperature in the tank. If the stability of the alkali cellulose dope in the tank is affected, less alkali cellulose dope is lost and waste disposal is easier. The risk of water condensation on the surface of the alkali cellulose dope is also reduced or minimized.

[0041] Additionally, cleaning of the alkali cellulose dope storage tank can be challenging because the remaining alkali cellulose dope can create a sticky residue that is difficult to remove when cleaned with water. Therefore, it may be beneficial to utilize two storage tanks, one of which can be used to store alkali cellulose dope while the other is being cleaned or otherwise maintained.

[0042] The method can be operated in a system including a first storage tank and a second storage tank, wherein the alkali cellulose dope is placed in the first storage tank while the second storage tank is under maintenance. The volumes of the first and second storage tanks are sufficient to accommodate a volume of alkali cellulose dope equivalent to or less than the daily production. In this process, the alkali cellulose dope can then be placed in the second storage tank while the first storage tank is under maintenance.

[0043] The volume of the storage tank and / or the first and second storage tanks may correspond, for example, to a production volume of 2 to 24 hours (a production volume of 24 hours being a daily production volume).

[0044] The capacity of the storage tank and / or the first and second storage tanks may be sufficient to store a volume of the alkali cellulose concentrate equivalent to 1 / 12 to 1x (ie, 1 / 12 to 1 times) the daily production volume.

[0045] The daily output is understood to be the volume of the alkali cellulose concentrate which is processed, for example by forming it into the desired shape, during a production process of one day (i.e. 24 hours). The daily output naturally depends on the production process. For example, the daily output can be about 140 m 3 In this process, the volume of the storage tank and / or the first and second storage tanks may be, for example, about 11.7 to 140 m 3 within the range of about 11.7 to 70m 3 within the range.

[0046] The process may be a continuous process.Instead of storage, the alkali cellulose dope may be supplied directly to production, such as to an extrusion or printing device or other device suitable for forming the alkali cellulose dope into a desired shape.

[0047] Processing the alkali cellulose concentrate placed in the storage tank into a desired shape may include or include, for example, extrusion, spinning, film making, film extrusion, coating, casting, cellulose bead production, spraying, electrospinning or printing, and coagulating the alkali cellulose concentrate into the desired shape.

[0048] The cold alkaline solution may contain a zinc compound, such as ZnO, for example to stabilize the alkaline cellulose concentrate. 2 and / or carbonates may form insoluble ZnCO 3 Therefore, the CO absorbed and dissolved in the alkaline cellulose concentrate 2Carbonates in the alkali cellulose dope can effectively reduce the amount of zinc ions in solution originating from ZnO. For environmental reasons, it may not be desirable to simply compensate for this by adding more zinc compounds. 2 It may also form Na 2 CO 3 , which is not an ideal salt in the system either.

[0049] Zinc carbonate crystals may form in products condensed from alkali cellulose dope. Such crystals may be loosened from the surface of the product and eventually enter the regeneration bath or washing bath. This may create holes on the surface of the product. In addition, large zinc carbonate crystals may clog the holes of, for example, a spinneret used to spin the alkali cellulose dope. Such holes may typically have a diameter of, for example, about 40-100 μm.

[0050] By this method, the stability of the alkali cellulose dope can be improved. In particular, the stability can be improved, for example, so that the viscosity of the alkali cellulose dope does not increase within a given time, at least not to a significant extent. The time period can be, for example, at least 4 hours, or at least 12 hours, or at least 24 hours.

[0051] Additionally or alternatively, the concentration of cellulose dissolved in the alkaline cellulose dope may be increased.The consumption of zinc compounds (eg ZnO) in the cold alkaline solution comprising the zinc compound may also be reduced, making the process more cost-effective and environmentally friendly.

[0052] There are a number of possibilities for at least partially reducing or removing dissolved CO. 2 and / or the concentration of carbonate ions in the cellulosic material and the cold alkaline solution and / or in the alkaline cellulose concentrate, and / or dispersing and dissolving the cellulosic material in the cold alkaline solution, provided that in the alkaline cellulose concentrate CO 2 For example, any of the following process steps may be applied alone or in combination with one or more of the following other process steps to at least partially reduce or remove dissolved CO in the cellulosic material and the cold alkaline solution and / or the alkaline cellulose concentrate. 2 and / or carbonate ion concentration.

[0053] In addition, it can also reduce or prevent the O dissolved in the alkaline cellulose concentrate. 2 Absorption and content. 2 The presence of may lead to undesirable degradation of cellulose and / or hemicellulose and the production of monosaccharides and other degradation products.

[0054] Providing a cold alkaline solution may typically comprise mixing and / or dissolving an alkaline agent such as NaOH and an optional solubilizing agent or stabilizing agent such as a zinc compound (e.g. ZnO) with water. They may be mixed under conditions suitable for dissolving the components in water, e.g. at an elevated temperature, such that an alkaline agent such as NaOH is added at a concentration of at least 40% (w / w). The elevated temperature may be, for example, a temperature of at least 60° C. The resulting alkaline solution may then be diluted. However, as described in the present disclosure, the (cold) alkaline solution may be produced by electrodialysis.

[0055] In the context of this specification, the term "(cold) alkaline solution" is understood to mean an alkaline solution and / or a cold alkaline solution. The alkaline solution can be cooled to a desired temperature to obtain a cold alkaline solution, or the alkaline solution can be generated at a temperature at which the alkaline solution generated can be considered to be a cold alkaline solution.

[0056] The alkaline agent in the (cold) alkaline solution may include or be, for example, NaOH, LiOH, KOH and / or any mixture or combination thereof. The alkaline agent may include or be, for example, NaOH, LiOH and / or any mixture or combination thereof. The (cold) alkaline solution may also include additional organic hydroxides, for example, tetrabutylammonium hydroxide etc. The (cold) alkaline solution may be an alkaline aqueous solution.

[0057] As will be appreciated by those skilled in the art, zinc compounds such as ZnO may be present in the (cold) alkaline solution and the alkaline cellulose dope, for example in the form of zincates. Solid zinc oxide may be dissolved in the alkaline solution to give soluble zincates, as shown in the following exemplary equation:

[0058] ZnO+2NaOH+H 2 O→Na 2 [Zn(OH) 4 ]

[0059] The (cold) alkaline solution may comprise an alkaline agent, such as NaOH, in a concentration in the range of about 5-9% (w / w) or about 6.5-8% (w / w).

[0060] The (cold) alkaline solution may further comprise about 0-3% (w / w), or 0.1-2.5% (w / w), or 0.5-1.3% (w / w) of a zinc compound, such as ZnO.

[0061] The (cold) alkaline solution may comprise ZnO and NaOH, for example in a mass ratio in the range of 0.025-0.3.

[0062] Cellulosic material can comprise cellulose and optional hemicellulose.Many cellulose sources may also contain a certain amount of hemicellulose.For example, paper pulp can comprise a mixture of cellulose and hemicellulose.Based on the total dry weight of cellulose and hemicellulose, the mixture can comprise, for example, at least 9 wt %, or at least 13 wt %, or at least 15 wt %, or 10-23 wt %, or 13-18 wt % hemicellulose.Hemicellulose also can be dissolved in alkaline cellulose concentrated solution.

[0063] The cellulosic material may include or be, for example, pulp. The pulp may be a hydrolyzed pulp. The pulp may be an alkali soluble pulp.

[0064] The pulp may include or be, for example, wood pulp (such as hardwood and / or softwood pulp), non-wood pulp and / or agricultural pulp. The pulp may be a chemical pulp, such as kraft pulp. Additionally or alternatively, the pulp may be an undried pulp, such as undried kraft pulp. The cellulosic material or slurry may include or be recycled fiber.

[0065] The pulp may be pretreated, for example by mechanical pretreatment (up to 5 hours) followed by enzymatic hydrolysis using cellulolytic enzymes for 2-3 hours.

[0066] Cellulosic materials such as pulps may have a CED viscosity in the range of 100-300 ml / g, or in the range of 140-200 ml / g, or in the range of 150-180 ml / g. The term "CED viscosity" may be understood to refer to the viscosity value in a copper ethylenediamine (CED) solution. Cellulosic materials with relatively low CED viscosities may have better solubility, and therefore may allow obtaining an alkali cellulose dope with a higher concentration of dissolved cellulose in the alkali cellulose dope and / or a more stable alkali cellulose dope. The CED viscosity may be measured, for example, according to the ISO 5351:2010 standard.

[0067] The cellulosic material may be in solid form, for example as a dry pulp. Alternatively, it may be in the form of, for example, a slurry.

[0068] Providing the cold alkaline solution may comprise generating the alkaline solution by electrodialysis and cooling the alkaline solution to obtain the cold alkaline solution.Any other components of the cold alkaline solution, such as a solubilizing agent or a stabilizing agent, such as a zinc compound, may be added to the alkaline solution, for example, after the electrodialysis.

[0069] Additionally or alternatively, electrodialysis may also be referred to as electrolysis. Although electrodialysis may be understood as a form of electrolysis, these terms are sometimes used interchangeably. Electrodialysis may be understood as a process of separating ionic species from aqueous solutions using a membrane (e.g., a semipermeable membrane and / or a charged membrane) and a potential difference. By electrodialysis, a saline solution may be electrochemically separated into at least two solutions of different composition.

[0070] A saline solution, such as one containing cations (such as Na + , K + or Li + Electrodialysis of a salt solution containing a cationic hydroxide may generate a solution containing a cationic hydroxide.

[0071] The saline solution may be a saline solution.

[0072] Electrodialysis can be performed using an apparatus comprising an anode, a cathode and a semipermeable membrane. The anode and cathode can be placed on opposite sides of the semipermeable membrane. Ions are transported through the semipermeable membrane under the influence of the electric potential generated by the anode and cathode.

[0073] The semi-permeable membrane may be a cation exchange membrane, etc. However, in certain embodiments, for example, electrodialysis may be performed using an apparatus including two semi-permeable membranes, such as a cation exchange membrane and an anion exchange membrane.

[0074] At the anode, the following reactions may occur:

[0075] H 2 O→2H + +1 / 2O 2 +2e -

[0076] At the cathode, the following reactions may occur:

[0077] 2H 2 O+2e - →2OH - +H 2

[0078] For example, when a saline solution contains Na 2 SO 4 The following reactions may occur at the anode:

[0079] H 2 O→2H + +1 / 2O 2 +2e -

[0080] 2H + +SO 4 2- →H 2 SO 4

[0081] At the cathode, the following reactions may occur:

[0082] 2H 2 O+2e - →2OH - +H 2

[0083] 2Na + +2OH - →2NaOH

[0084] The skilled person will appreciate that in the above equation, Na + The ion can be replaced by other suitable cations (such as K + or Li + ions) instead of SO 4 2- The ions may be replaced by other suitable anions contained in the saline solution (e.g., Cl - ions). The nature of the cations and anions depends on the salt contained in the saline solution.

[0085] Examples of suitable devices may include a generation chamber for generating an alkaline solution and a reservoir for storing a saline solution. The generation chamber may include a cathode, such as a perforated platinum (Pt) cathode, where hydroxide ions are formed. The electrolyte reservoir may include an anode (such as a Pt anode) and an electrolyte containing cations (such as K + 、Na + and / or Li + ) of a saline solution. The generation chamber can be connected to the reservoir via a cation exchange connector, which allows ions to enter the generation chamber from the reservoir while preventing anions from entering the generation chamber from the reservoir. The cation exchange connector can also serve as a physical barrier between the reservoir and the generation chamber. For example, the reservoir can be a low-pressure reservoir, and the generation chamber is a high-pressure generation chamber. In this embodiment, the cation exchange connector can serve as a pressure barrier between the low-pressure reservoir and the generation chamber. The cation exchange connector may include or be a membrane. The membrane may be, for example, a semi-permeable membrane, such as a cation selective membrane. An example of a cation selective membrane may be, for example, a negatively charged polyelectrolyte, which repels negatively charged ions and allows positively charged ions to flow through.

[0086] To generate an alkaline solution including KOH, NaOH and / or LiOH, water (e.g., deionized water) may be pumped through the generation chamber. A direct current may be applied between the anode and cathode. Under the action of the applied electric field, water is electrolyzed at the anode and cathode of the device. As shown in the figure below, water is oxidized at the anode of the reservoir to form H + ions and oxygen.

[0087] H 2 O+2e- →2H + +1 / 2O 2 ↑(at anode)

[0088] Water may be reduced to OH at the cathode of the generation chamber. - ions and hydrogen.

[0089] 2H 2 O+2e - →2OH - +H 2 ↑(at cathode)

[0090] When H is generated at the anode + Ions replace cations in reservoirs, such as K + 、Na + and / or Li + ions, the replaced ions can migrate through the cation exchange connector into the generation chamber.

[0091] These ions can react with OH generated at the cathode - The ions combine to form a KOH, NaOH and / or LiOH solution, which is then used as a cold alkaline solution to disperse and dissolve the cellulosic material. The concentration of the generated KOH, NaOH and / or LiOH can be determined by the current applied to the device and the water flow through the generation chamber.

[0092] Similar electrodialysis systems can be used, for example, in chromatography systems to generate the eluent on-line.

[0093] Other exemplary embodiments of suitable electrodialysis systems and apparatus are also described in the Examples.

[0094] The electrodialysis may be membrane electrodialysis.

[0095] The alkaline solution can be generated online.

[0096] The alkaline solution may be produced by an online electrodialysis system or an online membrane electrodialysis system. In other words, the electrodialysis system for electrodialysis may include or be an online electrodialysis system or an online membrane electrodialysis system.

[0097] In an online electrodialysis system, the alkaline solution generated can be used directly in the subsequent process steps, e.g. without the need for storage prior to the subsequent process steps. This can reduce the CO 2 absorption.

[0098] The alkaline solution may be generated in a closed environment, such as a closed container, for mixing the cellulose into the alkaline solution. The environment and / or container may be closed, i.e., the alkaline solution is not in contact with the atmosphere or air or other CO surrounding the closed environment and / or container. 2Therefore, the closed environment can reduce the contact between the alkaline solution and / or alkaline cellulose concentrate and CO 2 The environment and / or container in which cellulose is mixed into the alkaline solution may further include a protective gas. The protective gas may reduce the absorption of CO by the alkaline solution and / or the alkaline cellulose concentrate. 2 The protective gas may refer to CO 2 Reduced atmosphere, e.g. without CO 2 atmosphere or CO 2 Atmosphere with a content of 100 ppm or less; CO 2 An atmosphere in which the proportion of the alkali cellulose dope is reduced compared to the proportion of other gases contained in the atmosphere; and / or an inert gas. Since the alkali cellulose dope may have a low temperature, moisture may condense or even freeze on the surface of the alkali cellulose dope. This may have an adverse effect on the alkali cellulose dope. When a protective gas is used, the humidity of the atmosphere in contact with the alkali cellulose dope may also be reduced.

[0099] The (cold) alkaline solution may contain 0.5 g / kg or less, or 0.25 g / kg or less, or 0.05 g / kg or less of CO dissolved therein, based on the total weight of the (cold) alkaline solution. 2 .

[0100] The (cold) alkaline solution may comprise, for example, NaOH, LiOH, KOH and / or any mixture or combination thereof.

[0101] The (cold) alkaline solution may be a solution comprising NaOH, LiOH, KOH and / or any mixture or combination thereof.

[0102] The (cold) alkaline solution may be a NaOH solution.

[0103] The (cold) alkaline solution may be a NaOH solution produced by electrodialysis of a saline solution.

[0104] The saline solution can be considered as the electrolyte solution in electrodialysis. Therefore, the content of the alkaline solution will depend on the content of the saline solution.

[0105] If the salt solution is NaCl solution, then the alkaline solution will be NaOH solution; in addition, HCl solution will be produced. 2 SO 4 solution (e.g., salt from a regeneration bath), the product will be a NaOH solution; additionally, a solution containing NaHSO 4 and optionally H 2 SO 4 of solution.

[0106] The salt in the saline solution may be any suitable salt, including sodium, potassium, lithium, sulfur, chloride and / or phosphorus.

[0107] Electrodialysis can produce H 2 Gas. H can be collected 2 Gas. H 2 The gas can be used for other purposes, such as with the CO formed in the lime kiln of a pulp mill. 2 in combination; in a reduction process, such as a catalytic reduction process for producing biofuels; and / or as a fuel.

[0108] Electrodialysis can produce O 2 (Oxygen) gas. The generated oxygen can be used, for example, in the fiber line of a pulping process, for example in the oxygen delignification stage.

[0109] The saline solution may be obtained from various sources in various ways. Therefore, the composition of the saline solution may vary. The saline solution may contain one or more salts, and optionally one or more other ingredients.

[0110] In addition to salts (i.e., one or more salts) (such as Na 2 SO 4 ), the saline solution may also contain, for example, NaOH or other alkaline agents.

[0111] The alkaline solution may be a NaOH solution produced by electrodialysis of a saline solution. The saline solution may contain NaCl, NaHSO 4 and / or Na 2 SO 4 . 2 SO 4 (and / or NaHSO 4 ) can be obtained from the recovery process of a pulp mill. For example, it can be obtained from fly ash from a pulp mill recovery boiler. The saline solution can be obtained from recovery boiler ash obtained by electrostatic precipitation. This solution can contain Na 2 SO 4 And / or NaCl. This solution may further contain other salts, such as potassium salt (K + ) and chloride salts (Cl - ) and carbonate ions. If necessary, these other salts can be removed, for example, by precipitation and / or acidification, or ash leaching processes (for example, for NaCl). Therefore, a side stream of the pulp mill can be used to provide a cold alkaline solution. NaCl, i.e. a saline solution containing NaCl, can be obtained, for example, by reverse osmosis of seawater. Reverse osmosis can be used to produce pure water (drinking water) from seawater. In addition to pure water (drinking water), reverse osmosis can also produce a saline solution containing NaCl, wherein the concentration of NaCl is higher than the concentration in the seawater from which it is produced. Na 2 SO 4 or NaCl, i.e. containing Na 2 SO4 Salt solutions containing NaCl or NaCl can also be obtained as by-products from, for example, chlorine dioxide production. There are many different processes for producing chlorine dioxide, and the by-products may depend on the specific process. For example, a chlorine dioxine production process that includes a double decomposition unit can produce a solution containing NaCl. 2 SO 4 of solution.

[0112] Electrodialysis can be carried out by Na 2 SO 4 Solution (i.e. containing Na 2 SO 4 Electrodialysis can also generate NaHSO 4 and / or H 2 SO 4 The method may further include processing the alkaline cellulose concentrate into a desired shape, and the processing may include heating the concentrate in a solution containing NaHSO 4 and / or H 2 SO 4 Cellulose is coagulated from an alkaline cellulose concentrate in a regeneration bath of Na 2 SO 4 The solution (which can therefore be used as saline solution in electrodialysis) can be obtained, or at least partially obtained, from the regeneration bath.

[0113] Electrodialysis can be carried out by Na 2 SO 4 Solution generates NaHSO 4 and / or H 2 SO 4 Solution, NaHSO 4 and / or H 2 SO 4 The solution can be used in a regeneration bath.

[0114] In this way, the solution from the regeneration bath can be recycled for electrodialysis. The resulting (cold) alkaline solution can also be of high quality and can contain low concentrations of carbonate ions. Since the alkaline solution can be generated on site, it can be protected from CO in the air. 2 The carbonate ion concentration of the alkaline solution obtained, stored, and transported from commercial sources (e.g., NaOH solution) may be lower than that of the alkaline solution obtained from commercial sources. It may be difficult to avoid the alkaline solution from contacting CO 2 contact, nor can it be guaranteed to contain a large amount of dissolved CO 2 and / or carbonate ions.

[0115] Before electrodialysis, the electrolyte containing sulfate (such as NaHSO 4 and / or Na2 SO 4 ). This can be done, for example, by precipitation and subsequent filtration.

[0116] For example, Na can be obtained from the regeneration bath 2 SO 4 The solution may contain organic matter, such as carbohydrates, which can be removed by filtration, etc.

[0117] The concentration of carbonate ions in the (cold) alkaline solution may be 1.5% (w / w) or less, or 1.2% (w / w) or less, or 1.0% (w / w) or less, or 0.2% (w / w) or less, or 0.1% (w / w) or less. The concentration may be understood as the concentration based on the total weight of the (cold) alkaline solution.

[0118] Electrodialysis can also be used to at least partially remove components of the saline solution, thereby producing an alkaline solution more suitable for cellulose dissolution.

[0119] The saline solution may contain carbonates such as Na 2 CO 3 and / or NaHCO 3 .

[0120] Contains carbonates (such as Na 2 CO 3 and / or NaHCO 3 ) may not be so suitable for electrodialysis. Carbonates, as poorly soluble salts, may also be detrimental to obtaining an alkaline cellulose concentrate from a cold alkaline process (i.e., a process according to one or more embodiments described herein). Carbonates can be removed by acidification of the saline solution. However, in some embodiments, carbonate ions can also be at least partially removed by electrodialysis.

[0121] In one embodiment, the alkaline solution is prepared by electrodialysis of a carbonate (e.g., Na 2 CO 3 ) to generate a saline solution, thereby generating an alkaline solution and a solution containing H 2 CO 3 and removing at least part of the H 2 CO 3 The generated CO 2 .

[0122] In other words, the saline solution contains at least carbonates, but optionally also contains one or more other salts dissolved therein, such as sulfates (e.g., Na 2 SO 4). When the saline solution is subjected to electrodialysis, the saline solution can be used as an electrolyte solution. Electrodialysis of the saline solution can produce H 2 CO 3 The solution of H 2 CO 3 Can form CO in solution 2 , and the resulting CO 2 At the same time, electrodialysis produces an alkaline solution. In this way, a saline solution containing carbonates can be treated by electrodialysis to make it more suitable for use as an alkaline solution for preparing an alkaline cellulose concentrate.

[0123] In at least some embodiments, prior to electrodialysis, the saline solution may include an alkaline agent, such as NaOH. For example, the saline solution may be a weakly alkaline saline solution containing carbonates. The saline solution may be a solution containing NaOH or NaOH, LiOH, KOH and / or any mixture or combination thereof and carbonates (Na 2 CO 3 and / or NaHCO 3 ) solution. Electrodialysis of this saline solution can at least partially remove carbonates (carbonate ions) to obtain an alkaline solution.

[0124] For example, when a saline solution contains Na 2 CO 3 The following reactions can occur at the anode:

[0125] H 2 O→2H + +1 / 2O 2 +2e -

[0126] 2H + +CO 3 2- →H 2 CO 3

[0127] Then, H 2 CO 3 Can form gaseous CO 2 , which can be at least partially removed:

[0128] H 2 CO 3 →H 2 O+CO 2 ↑

[0129] In embodiments where the water is fed to electrodialysis, the water may be purified and / or degassed prior to feeding the water to electrodialysis in order to at least partially remove dissolved CO2 The water may be degassed and / or purified, for example by boiling, heating, ion exchange, reverse osmosis, nanofiltration, precipitation, ion exclusion chromatography, acidification and / or any combination thereof, to at least partially remove carbonate ions and optionally other ions.

[0130] Suitable ion exchange resins can be used to at least partially remove carbonate ions and optionally other ions. Such ion exchange resins and methods of using them are known. Ion exchange can be carried out, for example, by replacing Ca(OH) 2 or CaO is added to water to convert carbonate ions into CaCO 3 Precipitation and subsequent at least partial removal of the remaining Ca by ion exchange 2+ ions to carry out.

[0131] Additionally or alternatively, the water may be purified by acidification to remove carbonate ions and subsequently by anion exchange to remove anions originating from the acid added in the acidification. - ) and / or sulfate ions (SO 4 2- ) can be exchanged for hydroxyl ions (OH - ).

[0132] Additionally or alternatively, the water may be purified by boiling or heating. Boiling or heating may remove air (including O 2 and CO 2 ). The boiling or heating may be carried out under reduced pressure (e.g., under a partial vacuum). The boiled or heated water may then be stored in a CO 2 In an atmosphere with a low content of inert gas, such as helium (He) or nitrogen (N 2 )gas.

[0133] In the context of this specification, the term "reduced pressure" may be understood to refer to a pressure below atmospheric pressure. The reduced pressure may be, for example, a partial vacuum. The reduced pressure used or required may depend, for example, on the temperature. For example, the reduced pressure may enable at least partial degassing, but without causing a large amount of water to evaporate. The reduced pressure may be, for example, a pressure range of 80-800 mbar, or 100-200 mbar. In the context of this specification, the term "partial vacuum" may refer to a pressure in the range of 80-800 mbar or in the range of 100-200 mbar. A person skilled in the art will understand that under reduced pressure, CO in the atmosphere is 2 The absolute concentration of CO may decrease, while 2 The concentration or ratio relative to other gases in the atmosphere can remain constant.

[0134] As the skilled person will appreciate, water is generally not pure water or contains only H2 O, but may contain certain amounts of other components, such as components dissolved therein, such as CO 2 and / or carbonate ions.

[0135] The water may contain 0.5 g / kg or less, or 0.25 g / kg or less, or 0.05 g / kg or less of CO dissolved therein, based on the total weight of the water. 2 .

[0136] The concentration of carbonate ions in water may be 1.5% (w / w) or less, or 1.2% (w / w) or less, or 1.0% (w / w) or less, or 0.2% (w / w) or less, or 0.1% (w / w) or less. The concentration may be understood as the concentration based on the total weight of water.

[0137] In the context of this specification, the term "having reduced CO 2 The term "atmosphere containing no CO 2 atmosphere or contains 100 ppm or less CO 2 atmosphere. With reduced CO 2 The atmosphere may contain 50000 ppm or less of O 2 . With reduced CO 2 The atmosphere with reduced CO content may be formed by an inert gas, such as helium, argon and / or nitrogen, or other suitable inert gases. In one embodiment, the term "having reduced CO 2 The term "gas atmosphere" may refer to a gas atmosphere in which CO is present in a proportion relative to other gases contained in the atmosphere. 2 For example, a reduced CO 2 The atmosphere can contain 1.5g / m 3 or less CO 2 .

[0138] The cellulosic material can be a slurry suspension prepared by mixing a slurry (e.g., hydrolysis slurry or other suitable slurry) with water. The water can be, for example, water purified according to one or more embodiments described in this specification. Mixing can be performed using a mixing device with sufficient mixing power to separate the fibers from each other and avoid fiber bundles in the alkaline cellulose concentrate. Mixing with such a mixing device can also help bring energy into the system under mixing so that the solid-gas interface in the system can be replaced by the solid-liquid interface.

[0139] The temperature of the slurry suspension may be adjusted to a desired temperature, for example, a temperature in the range of 0° C. to 5° C. Mixing may continue.

[0140] The cellulosic material may then be dispersed and dissolved in the cold alkaline solution.Before and / or during this step, the temperature of the cold alkaline solution and / or the cellulosic material may be adjusted to a temperature in the range of -5°C to 5°C.

[0141] The cellulosic material may be dispersed and dissolved in the cold alkaline solution, for example by feeding the cellulosic material and the cold alkaline solution into a continuous reactor or a high concentration dissolution unit, wherein partial or complete dissolution of the cellulose may be achieved.

[0142] Using one or more embodiments of the methods described herein, a higher concentration of dissolved cellulose in an alkaline cellulose dope can be obtained.

[0143] The concentration of dissolved cellulose in the alkaline cellulose dope may be at least 5% (w / w), or at least 7% (w / w), or at least 8% (w / w), or at least 9% (w / w), or at least 10% (w / w), or at least 11% (w / w), or at least 12% (w / w). The concentration of dissolved cellulose in the alkaline cellulose dope may be in the range of about 5-12% (w / w).

[0144] When dissolving the cellulosic material and / or the alkali cellulose dope, the temperature of the cold alkali solution may be in the range of -20°C to 5°C, or in the range of -4°C to 5°C.

[0145] The cold alkaline solution may contain 0.5 g / kg or less, or 0.25 g / kg or less, or 0.05 g / kg or less of CO dissolved therein, based on the total weight of the cold alkaline solution. 2 .

[0146] The concentration of carbonate ions in the cold alkaline solution can be 1.5% (w / w) or less, or 1.2% (w / w) or less, or 1.0% (w / w) or less, or 0.2% (w / w) or less, or 0.1% (w / w) or less (based on the total weight of the cold alkaline solution).

[0147] The method may further comprise forming the alkali cellulose dope into a desired shape. The alkali cellulose dope may be formed into a desired shape, for example, by extruding, spinning, film making, film extrusion, cellulose bead production, coating, casting, spraying, electrostatic spinning or printing and coagulating the alkali cellulose dope.

[0148] The alkali cellulose dope may be extruded, for example, through a die or a nozzle.

[0149] The viscosity of the alkali cellulose dope can be adjusted to a desired viscosity, such as for extrusion, film making, film casting, spinning and / or spraying. The consistency of the alkali cellulose dope can be in the range of, for example, 5-12 wt%.

[0150] The cellulose of the alkaline cellulose dope may be considered to be coagulated and / or regenerated when the desired shape is obtained therefrom. The cellulose is not necessarily actually regenerated cellulose, i.e. it has been subjected to a viscose process and subsequent regeneration. In this context, the terms "coagulated" and "regenerated" may refer to cellulose that has been precipitated and / or crystallized from a dissolved state. It may be at least partially crystallized into cellulose II; or partially crystallized into cellulose I and partially crystallized into cellulose II. Typically, the coagulated cellulose is in the form of cellulose II.

[0151] The shape can be, for example, a pellet, a powder, a film, a filament, a staple fiber, a bead, a melt, a 3D shape, a coating, a hot melt adhesive, a container, a housing, a packaging product, a film label, paper, a medical device, a plastic or composite profile, an abrasive particle, an abrasive film or paper, and / or a 3D printing filament. The shape is not particularly limited. Various shapes can be extruded, spun, formed into a film, cast, sprayed, printed, coated or molded from an alkaline cellulose concentrate.

[0152] The extruded shape, such as a filament or any other shape, can be coagulated and washed after extrusion. For example, the method may include immersing the extruded shape in a regeneration bath (or one or more regeneration baths). The regeneration bath may contain a regeneration solution, which may then help to coagulate the cellulose contained in the shape. The regeneration solution may be an acidic regeneration solution, such as a sulfuric acid solution. However, in some embodiments, the regeneration solution may be, for example, water or a weakly alkaline solution. The extruded and coagulated shape may be immersed in one or more washing baths. For example, after a washing bath containing an acidic washing solution, the extruded shape may be immersed in a second washing bath. The second washing bath may include, for example, water or other neutral solutions.

[0153] An alkaline cellulose concentrate is disclosed. The alkaline cellulose concentrate may contain 0.5 g / kg or less, or 0.25 g / kg or less, or 0.05 g / kg or less of CO dissolved therein. 2 .

[0154] The concentration of carbonate ions in the alkali cellulose dope may be 1.5% (w / w) or less, or 1.2% (w / w) or less, or 1.0% (w / w) or less, or 0.2% (w / w) or less, or 0.1% (w / w) or less. The concentration may be understood as the concentration based on the total weight of the alkali cellulose dope.

[0155] The alkaline cellulose dope may have a viscosity in the range of 2000-100000 mPas, or in the range of 2000-20000 mPas, or in the range of 2000-10000 mPas, or in the range of 3000-8000 mPas, or in the range of 4000-6000 mPas, or in the range of 3000-6000 mPas.

[0156] The alkali cellulose dope may have a viscosity of 10000 mPas or less during a period of at least 24 hours during which the cellulosic material is dissolved in the alkali cellulose dope. If the stability of the alkali cellulose dope decreases, the viscosity may increase, especially during storage.

[0157] In the time of at least 24 hours during which the cellulosic material is dissolved in the alkaline cellulose dope, the viscosity of the alkaline cellulose dope increases by no more than 50%, or no more than 20%, or no more than 10%. The time period can be, for example, at least 4 hours, or at least 12 hours, or at least 24 hours.

[0158] Also disclosed are products obtainable by coagulating an alkali cellulose dope from a cold alkali process.

[0159] The product may comprise 1.0% (w / w) or less carbonate ions. The product may comprise 0.2% (w / w) or less, or 0.1% (w / w) or less carbonate ions.

[0160] The product can be obtained by coagulating an alkali cellulose dope according to one or more embodiments described in this specification.

[0161] The product obtained by coagulating the alkali cellulose dope from the cold alkaline process may be such that it does not contain xanthate of cellulose and / or sulfur covalently bound to cellulose. The product obtained by coagulating the alkali cellulose dope from the cold alkaline process may be such that it does not contain residues of N-methylmorpholine 4-oxide (NMMO) and / or ionic liquids (ionic solvents). In other words, the product obtainable by coagulating the alkali cellulose dope from the cold alkaline process may not cover the residues that may be obtained by viscose, lyocell or Products obtained by process.

[0162] The product may have a CED viscosity in the range of 100-300 ml / g, or in the range of 140-200 ml / g, or in the range of 150-180 ml / g.

[0163] The product can be obtained from the alkali cellulose dope by extrusion, spinning, electrospinning, molding, casting, film forming, film extrusion, cellulose bead production, coating, spraying and / or printing, and coagulation of the alkali cellulose dope.

[0164] According to one or more embodiments described in this specification, the product can be obtained from the alkali cellulose dope by extruding, spinning, molding, film-forming, casting, spraying, electrospinning, coating and / or printing, and coagulating the alkali cellulose dope.

[0165] The product can be, for example, a pellet, a powder, a film, a filament, a staple fiber, a bead, a melt, a 3D shape, a coating, a hot melt adhesive, a container, a housing, a packaging article, a film label, paper, a medical device, a plastic or composite profile, an abrasive particle, an abrasive film or paper, and / or a 3D printing filament.

[0166] For example, the product may be a sausage casing obtainable by extruding and coagulating an alkali cellulose dope, or a sausage casing obtainable by coating and / or impregnating a fiber reinforcement with an alkali cellulose dope.The outer side or the outer side and the inner side of the fiber reinforcement may be coated.

[0167] The product may be a paper or paperboard obtainable by coating the paper or paperboard with an alkaline cellulose dope.

[0168] The product may be filaments and / or staple fibers. Such a product may have a tenacity of 15 cN / tex or more.

[0169] Example

[0170] Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings.

[0171] The following description discloses some embodiments in detail so that those skilled in the art can utilize these embodiments based on the present disclosure. Not all steps or features of the embodiments are discussed in detail because many steps or features are obvious to those skilled in the art based on the present description.

[0172] Figure 1 An embodiment of a method for preparing an alkaline cellulose dope is depicted, in particular providing a cold alkaline solution comprises generating the alkaline solution by electrodialysis. The alkaline solution is generated in an electrodialysis device 1 .

[0173] An example of a suitable device 1 may include a cartridge. However, the device 1 is not necessarily in the form of a cartridge. The device may include a generation chamber 2 for generating an alkaline solution and a reservoir 3 for storing a saline solution, i.e., an electrolyte reservoir. The generation chamber 2 may include a cathode 4, such as a perforated platinum (Pt) cathode, where hydroxide ions are formed. The reservoir 3 may include an anode 5 (such as a Pt anode) and a saline solution 6 containing cations. The cations are represented as Na in this exemplary embodiment. +Ions. The generation chamber 2 can be connected to the reservoir 3 through a cation exchange connector 7, which allows ions to enter the generation chamber 2 from the reservoir 3 while preventing anions from entering the generation chamber 2 from the reservoir 3. The cation exchange connector 7 can also serve as a physical barrier between the reservoir and the generation chamber. For example, the reservoir 3 can be a low-pressure reservoir, and the generation chamber 2 is a high-pressure generation chamber. In this embodiment, the cation exchange connector 7 can serve as a pressure barrier between the low-pressure reservoir and the generation chamber. The cation exchange connector may include or be a membrane. The membrane may be, for example, a semi-permeable membrane, such as a cation selective membrane.

[0174] In order to generate an alkaline solution containing KOH, NaOH and / or LiOH, water (e.g., deionized water) can be pumped through the generation chamber 2 by a pump 8. The alkaline solution is represented as NaOH in this schematic diagram. A direct current can be applied between the anode 5 and the cathode 4. Under the action of the external electric field, water is electrolyzed at the anode 5 and the cathode 4 of the device 1. As shown in the figure below, water is oxidized at the anode 5 of the reservoir 3 to form H + ions and oxygen.

[0175] H 2 O+2e - →2H + +1 / 2O 2 ↑(at anode)

[0176] In order to remove the O generated at the anode 5 in the storage 3 2 , the storage can be equipped with a vent 9.

[0177] Water can be reduced to OH at the cathode 4 of the generation chamber 2. - ions and hydrogen.

[0178] 2H 2 O+2e - →2OH - +H 2 ↑(at cathode)

[0179] The H generated at the cathode 4 2 It can be removed and collected at, for example, the degassing module 10 .

[0180] When the H generated at the anode 5 + Ions replace cations in reservoirs, such as K + 、Na + and / or Li + ions, the replaced ions can migrate through the cation exchange connector 7 to the generation chamber 2. These ions can react with the OH generated at the cathode 4. -The ions combine to form an alkaline concentrate which can then be used as a cold alkaline solution for dispersing and dissolving the cellulosic material. The concentration of the generated KOH, NaOH and / or LiOH can be determined by the current applied to the device and the water flow through the generating chamber 2.

[0181] Figure 2 Embodiments of methods of preparing an alkaline cellulose dope and systems for operating the methods are described.

[0182] The alkaline concentrate is provided by generating an alkaline solution in an electrodialysis device 1, for example Figure 1 , Figure 4 or Figure 5 The electrodialysis device 1 is depicted in FIG. However, as will be appreciated by the skilled person, the alkaline solution may also be produced by conventional methods (eg, dissolving NaOH or other suitable alkaline agent in water under suitable conditions).

[0183] The alkaline solution may be generated online by electrodialysis at 1. The alkaline solution may be generated in a closed environment, such as a closed container 11, for mixing the cellulosic material 12 into the alkaline solution. The environment and / or container may be closed, i.e., the alkaline solution is not exposed to the atmosphere or other CO after being generated and introduced into the container 11. 2 Therefore, the closed environment can reduce the contact between the alkaline solution and / or alkaline cellulose concentrate and CO 2 The environment and / or container in which cellulose is mixed into the alkaline solution may further include a protective gas. The protective gas may reduce the absorption of CO by the alkaline solution and / or the alkaline cellulose concentrate. 2 absorption.

[0184] A cellulosic material 12, such as a pulp, is provided. The cellulosic material 12 may be, for example, a cellulosic material according to one or more embodiments described herein.

[0185] Additives 13 such as dissolving agents or stabilizing agents, for example zinc compounds such as ZnO, may be added to the container 11 .

[0186] Then the cellulose material 12 can be dispersed and dissolved in the alkaline solution in the container 11 to obtain an alkaline cellulose dope. Prior to this, the alkaline solution can be cooled to form a cold alkaline solution.

[0187] The alkali cellulose concentrate can be temporarily stored in the storage tank 14 before being sent to the production system 15. The volume of the storage tank 14 is sufficient to accommodate a volume of alkali cellulose concentrate equivalent to or less than the daily production. The daily production can be understood as the volume of alkali cellulose concentrate processed in the production system 15 during a day (i.e., 24 hours). Therefore, the method can be a continuous or semi-continuous method.

[0188] In some embodiments, Figure 2 The system depicted in the figure may include a first storage tank 14 and a second storage tank 14', the operation of the two storage tanks is to place the alkali cellulose concentrate in the first storage tank 14 while maintaining the second storage tank 14'; wherein the volume of the first storage tank 14 and the second storage tank 14' are both sufficient to accommodate a volume of alkali cellulose concentrate equivalent to or less than the daily production. However, it is understood that in some embodiments, the system may include only one storage tank 14.

[0189] The alkali cellulose dope can be fed from the storage tanks 14 and 14' or from a previous process stage to the production system 15, which can be, for example, an extrusion or printing device. In this exemplary embodiment, the system 15 includes an extrusion device capable of extruding and coagulating the alkali cellulose dope into a certain shape (such as a filament or a film). However, other types of equipment can be envisioned. In the production system 15, the alkali cellulose dope is driven through a die 18 by a screw 16 driven by a motor 17. At the die 18, the alkali cellulose dope is extruded into a shape 19, such as a filament; however, the alkali cellulose dope can alternatively be extruded into various other shapes or contours, such as extrusion into a film. The wet filaments 19 can then be immersed in a regeneration bath 20, which contains, for example, sulfuric acid (H 2 SO 4 ) solution. In the regeneration bath 10, the dissolved cellulose (and hemicellulose, if present) from the cellulosic material is coagulated. The coagulated filaments or other shapes can then be further processed.

[0190] As schematically shown by the arrow at 21, electrodialysis at 1 can be used to convert Na 2 SO 4 The solution generates H 2 SO 4 Solution, H 2 SO 4 The solution may be introduced into a regeneration bath 20 and used therein.

[0191] Alternatively or additionally, electrodialysis at 1 may be performed from Na 2 SO 4 The solution generates NaOH solution. 2 SO 4 The solution can be obtained from 2 SO 4 The solution is obtained or at least partially obtained from the regeneration bath 20 of the solution. In such an embodiment, the device 22 for removing zinc compounds from the regeneration bath can be used to remove Na 2 SO 4 For example, in the device 22, the regeneration bath and subsequent Na 2 SO 4The device 22 may include, for example, a filter for removing precipitated zinc, for example in the form of precipitated zinc carbonate. After removing the precipitated zinc, the electrodialysis may be performed at 1 by acidifying the Na 2 SO 4 Solution, from Na 2 SO 4 Alternatively, ZnSO 4 Than Na 2 SO 4 are more soluble in water, for example at 20°C. These differences in solubility allow at least partial removal of ZnSO 4 .

[0192] Figure 3 An embodiment of a method for preparing an alkaline cellulose dope is shown. In this exemplary embodiment, the hydrolyzed pulp 2 obtained from a fiber line 23 of a pulping process is directly cold alkali dissolved at 24, ie the hydrolyzed pulp 2 is dissolved at 24 in a cold alkaline solution.

[0193] The cold alkaline solution is obtained from a sodium hydroxide solution 25 (i.e., alkaline solution) obtained by electrodialysis 1. An additive (e.g., ZnO) may be added to the sodium hydroxide solution at 26. The sodium hydroxide solution containing the additive may then be mixed with the hydrolyzed pulp at 24; water 27 is then added. The hydrolyzed pulp 2 is then dissolved in the cold sodium hydroxide solution at 24, thereby obtaining an alkaline cellulose concentrate.

[0194] The resulting alkali cellulose dope is then filtered and degassed at 28. The resulting alkali cellulose dope is used as a spinning solution and extruded through a spinneret at 29 into a regeneration bath 20 to obtain textile fibers, which are then washed at 30. However, as will be appreciated by those skilled in the art, the alkali cellulose dope may also be formed into various other shapes by various other processes.

[0195] The sodium sulfate solution 31 obtained from the regeneration bath 20 can then be further processed and recycled. Impurities, such as zinc compounds in the sodium sulfate solution, can be removed at 32, for example, by precipitation and filtration. Optionally, sulfuric acid is added to the filtered sodium sulfate solution at 33 to remove carbonates. The purified sodium sulfate solution can be input to the electrodialysis 1 as a saline (electrolyte) solution.

[0196] In addition to sodium hydroxide 25, electrodialysis 1 may produce other products that can be used for various purposes. Sulfuric acid 34 obtained from electrodialysis 1 may be reused, for example, for acidification of sodium sulfate solution at 33 to remove carbonate ions, and / or for use in regeneration bath 20. Another option for utilizing sulphuric acid 34 obtained from electrodialysis 1 may include, for example, using it in a pulp mill process for a fiber line at 23, or for obtaining a hydrolyzed pulp 2. Hydrogen 35 and oxygen 36 produced by electrodialysis 1 may be collected and optionally reused, for example, oxygen 36 may be used in a fiber line 23, hydrogen 35 may be used as a reducing agent, used in a catalytic process (such as biofuel production) and / or as a fuel for energy production.

[0197] Figure 4 Another electrodialysis device 1 is shown. The device comprises an anode, a cathode, a first compartment 37 and a second compartment 38, and a semi-permeable membrane 39 connecting the first compartment 37 and the second compartment 38. The semi-permeable membrane 39 can be, for example, a cation exchange membrane. The anode is in contact with the first compartment 37, and the cathode is in contact with the second compartment 38.

[0198] The device 1 can be operated as a flow-through device, i.e. the saline solution (in this case Na 2 SO 4 The solution) can flow through the first compartment 37, and water can flow through the second compartment 38. The electrochemical reactions occurring at the anode and cathode are shown in the figure. 2 SO 4 and Na 2 SO 4 A solution containing only H 2 SO 4 From the second compartment 38, an alkaline solution containing NaOH as an alkaline agent can be obtained.

[0199] Figure 5 Another electrodialysis device 1 is shown. Figure 4 The device shown is similar, except that instead of two compartments, there are three compartments. Device 1 also includes an anode and a cathode. The anode is in contact with the first compartment 37 and the cathode is in contact with the second compartment 38. The third compartment 40 is located between the first compartment 37 and the second compartment 38 and is separated by a first semi-permeable membrane 39 and a second semi-permeable membrane 39'. The first semi-permeable membrane 39 can be a cation exchange membrane and the second semi-permeable membrane 39' can be an anion exchange membrane.

[0200] The device 1 can also be operated as a flow-through device. 2 SO 4 A solution) can flow through the third compartment 40, and water or an alkaline solution (such as a NaOH solution) can flow through the second compartment 38. Water and an optional salt solution (in this example, Na2 SO 4 The solution) can flow through the first compartment 37. The electrochemical reaction occurring at the anode and cathode is shown in the figure. Sulfate ions can enter the first compartment 37 from the third compartment 40 through the anion exchange membrane 39', where they form H 2 SO 4 In this way, the first compartment 37 can be used to obtain the H 2 SO 4 Solution of Na + Ions can enter the second compartment 38 from the third compartment 40 through the cation exchange membrane 39, where they form NaOH with the hydroxide ions produced at the cathode. An alkaline solution containing NaOH as an alkaline agent can be obtained from the second compartment 38. The solution from the third compartment 40 can be subjected to purification treatment, for example.

[0201] Figure 4 and Figure 5 The electrodialysis apparatus 1 shown can produce a 10-15 wt % NaOH solution. Figure 5 The equipment shown is Figure 4 The apparatus shown differs at least in that the sulfuric acid solution produced may contain less Na 2 SO 4 . Figure 4 H of the device shown 2 SO 4 The conversion rate can be as high as 50-60%. Figure 5 The conversion rate of the device shown can reach nearly 100%. However, Figure 5 A three-compartment device is more complex and may cost more.

[0202] Example 1

[0203] Alkaline cellulose dope was prepared from pretreated kraft pulp with a CED viscosity of 170 ml / g for use in spinning trials. Figure 1 The electrodialysis apparatus shown in the figure prepares an alkaline solution containing 18 wt% NaOH by electrodialysis. ZnO is added to the alkaline solution to obtain an alkaline solution containing 3 wt% ZnO. The alkaline solution is produced in an inert N 2 atmosphere to prevent CO 2 absorbed into alkaline solution.

[0204] The dissolution of cellulose is carried out in an inert N 2 Under an atmosphere of inert N, water with very low carbon dioxide content and washed cellulose are mixed together and the temperature is lowered to nearly 1°C (without freezing water). When the temperature is reached, 2Add the alkaline solution at a temperature close to -15°C under an inert N atmosphere. Continue mixing for 30 minutes, and the temperature at the end of the dissolution step is 2°C. Slowly increase the temperature to 15°C while maintaining an inert N atmosphere. 2 atmosphere to obtain an alkaline cellulose concentrate.

[0205] Example 2

[0206] The effect of carbonate ion concentration on the stability of alkaline cellulose dope was studied by producing alkaline cellulose dope with low carbonate ion concentration. 2 Gas was introduced into the freshly prepared dope to produce dope samples containing different amounts of carbonate ions (ranging from 0.01% to 1.8% based on the total weight of the alkali cellulose dope in % (w / w).

[0207] The carbonate ion concentration of the concentrate samples was determined by standard SCAN-N 32:98.

[0208] The Brookfield viscosity of the alkaline cellulose dope samples was measured and plotted as a function of carbonate ion concentration, as Figure 6 As shown in Figure 2, when the carbonate ion concentration exceeds 1.2% (w / w), the viscosity increases, indicating that the stability is reduced. When the carbonate ion concentration exceeds 1.5% (w / w), the stability is significantly reduced.

[0209] Example 3

[0210] Pretreated kraft pulp with a CED viscosity of 170 ml / g was used in the spinning trials.

[0211] By heating RO water to 60°C and evaporating more than 5% of water and CO under reduced pressure 2 , can produce CO 2 The pressure is so low that the water boils. This extremely low CO 2 Water with a concentration of 100 g / g cellulose was used to wash the pulp (50 g water / g cellulose) and also to produce an alkaline solution containing 18 wt % NaOH and 3 wt % ZnO. Both chemicals were of analytical grade and the bottles were opened before use. The alkaline solution was prepared under inert N 2 Carried out in atmosphere.

[0212] By inert N 2 The atmosphere will be extremely low in CO 2 Mix the washed cellulose with water and lower the temperature to approximately 1°C (without freezing the water) to complete the dissolution of the cellulose. 2Add the alkaline solution at a temperature close to -15°C under an inert N atmosphere. Continue mixing for 30 minutes, and the temperature at the end of the dissolution step is 2°C. Slowly increase the temperature to 15°C while maintaining an inert N atmosphere. 2 atmosphere.

[0213] At this stage, the cellulose solution is divided into two parts, one of which is heated in an inert N 2 The spinning solution (i.e., alkaline cellulose concentrate) A) is treated under the atmosphere, while the other part (spinning solution B) absorbs CO 2 And was not blocked. The viscosity of the solution was 4560 mPas at this time. Both cellulose solutions were filtered using 3 filters (25 μm, 10 μm and 5 μm) and centrifuged (1000 g, gravity) and transferred to the spinning container. The two samples were always mixed very slowly to keep the carbonate ion concentration of the samples constant.

[0214] Spinning was carried out the next morning. The viscosity and carbonate ion concentration of the spinning solution were measured before spinning. The viscosity and carbonate ion concentration of spinning solutions A and B were 4320 mPas and 0.09% (w / w), and 12610 mPas and 1.05% (w / w), respectively. The temperature of the two spinning solutions was 21°C. The spinning of the two spinning solutions used a spinneret with 250 holes and used exactly the same spinning parameters (regeneration bath with 10% H 2 SO 4 and 15% Na 2 SO 4 The fiber was washed with RO water and dried using an air dryer (60°C).

[0215] Figure 7 The tenacity of the staple fibers is shown as a function of the stretch between the first godet and the second godet. Figure 8 The tenacity of the staple fibers is shown as a function of the elongation at break. Figure 7 It is shown that the staple fibers made from spinning solution A are much more stretchable than the staple fibers made from spinning solution B. It can be concluded that spinning solution A has significantly better stretchability and the regeneration is more uniform. The mechanical properties of the staple fibers made from spinning solution A are much better. For textile fibers, both tenacity and elongation at break are important properties. The tenacity of spinning solution A can be higher than 20 cN / tex, and the elongation at break is still close to 20%, while the staple fibers made from spinning solution B cannot reach the combination of tenacity 15 cN / tex and elongation at break of 15%.

[0216] The carbonate ion concentration of the dried staple fibers produced from spinning solution A was measured and found to be only 0.08% (w / w). The low carbonate ion concentration in the spinning solution enables the production of high tenacity fibers with low porosity and low carbonate content. Fibers with high porosity are more difficult to clean.

[0217] Example 4

[0218] The alkali cellulose dope sample containing 7.4% (w / w) cellulose was stored in a container at 4° C. for 5 days so as to be in contact with air in the container. The alkali cellulose dope samples were collected on days 0, 1, and 5, and the Brookfield viscosities of the samples were measured.

[0219] Fig. 9 The Brookfield viscosity of the samples is shown. The viscosity of the alkali cellulose dope was found to increase upon storage, indicating that its stability decreases more with longer storage time.

[0220] It is obvious to a person skilled in the art that, as technology develops, the basic idea can be implemented in various ways. Therefore, the implementations are not limited to the above-described embodiments; instead, they may vary within the scope of the claims.

[0221] The embodiments described above can be used in any combination with each other. Several embodiments can be combined to form further embodiments. The methods, products, or uses disclosed herein may include at least one embodiment described above. It is understood that the above benefits and advantages may relate to one embodiment, or may relate to several embodiments. The embodiments of the present invention are not limited to the embodiments that can solve any or all of the problems described, nor are they limited to the embodiments that have any or all of the benefits and advantages described. It should be further understood that the "one" item mentioned refers to one or more items therein. The term "comprising" used in this specification includes the features or behaviors thereafter, without excluding the presence of one or more other features or behaviors.

Claims

1. A method for preparing an alkaline cellulose concentrate, wherein: The method comprises: providing a cellulosic material and a cold alkaline solution, and The cellulose material is dispersed and dissolved in a cold alkaline solution to obtain an alkaline cellulose concentrate, Wherein, providing the cold alkaline solution includes generating an alkaline solution by electrodialysis, thereby reducing or preventing the absorption and / or dissolution of CO2 in the cold alkaline solution, and / or reducing the concentration of carbonate ions in the cold alkaline solution.

2. The method of claim 1, wherein: Electrodialysis is membrane electrodialysis.

3. The method according to claim 1 or 2, wherein: The alkaline solution is generated online, for example, by an online electrodialysis system or an online membrane electrodialysis system.

4. The method according to any one of claims 1 to 3, wherein: The alkaline solution contains 0.5 g / kg or less, or 0.25 g / kg or less, or 0.05 g / kg or less of CO2 dissolved therein, based on the total weight of the alkaline solution; and / or wherein the concentration of carbonate ions in the alkaline solution is 1.5% (w / w) or less, or 1.2% (w / w) or less, or 1.0% (w / w) or less, or 0.2% (w / w) or less, or 0.1% (w / w) or less.

5. The method according to any one of claims 1 to 4, wherein: The alkaline solution is a solution comprising NaOH, LiOH, KOH and / or any mixture or combination thereof.

6. The method according to any one of claims 1 to 5, wherein: Electrodialysis produces H2 gas, which is then collected.

7. The method according to any one of claims 1 to 6, wherein: The alkaline solution is a NaOH solution produced by electrodialysis of a saline solution, wherein the saline solution comprises NaCl, Na2SO4, NaHCO3 and / or Na2CO3 as salts; wherein NaCl, Na2SO4, NaHCO3 and / or Na2CO3 are optionally obtainable from a pulp mill recovery process or are obtained from a pulp mill recovery process.

8. The method according to any one of claims 1 to 7, wherein: Electrodialysis generates NaOH solution from Na2SO4 solution; wherein the method further comprises processing the alkaline cellulose concentrate into a desired shape, the processing comprising coagulating cellulose from the alkaline cellulose concentrate in a regeneration bath containing NaHSO4 and / or H2SO4; and the Na2SO4 solution can be obtained from the regeneration bath or at least partially obtained from the regeneration bath.

9. The method of claim 8, wherein: Electrodialysis generates NaHSO4 and / or H2SO4 solution from Na2SO4 solution, and NaHSO4 and / or H2SO4 solution is used in the regeneration bath.

10. The method according to any one of claims 1 to 9, wherein: The alkaline solution is generated by electrodialysis of a saline solution comprising carbonates such as NaHCO3 and / or Na2CO3, thereby generating an alkaline solution and a solution comprising NaHCO3 and / or H2CO3, and at least partially removing CO2 formed from H2CO3 from the solution.

11. The method according to any one of claims 1 to 10, wherein: The water fed to the electrodialysis is purified and / or degassed before being fed to the electrodialysis, thereby at least partially removing the CO2 dissolved therein.

12. The method according to any one of claims 1 to 11, wherein: The method further comprises: placing the alkaline cellulose concentrate in a storage tank, and The alkali cellulose concentrate placed in the storage tank is processed into a desired shape, thereby completing the daily output of the alkali cellulose concentrate in one day. The capacity of the storage tank is sufficient to accommodate a volume of alkali cellulose concentrate equivalent to or less than the daily output.

13. The method of claim 12, wherein: The method is operated in a system, which includes a first storage tank and a second storage tank. The operation mode of the two storage tanks is to place the alkaline cellulose concentrate in the first storage tank while maintaining the second storage tank; wherein the volume of the first storage tank and the second storage tank is sufficient to accommodate the volume of the alkaline cellulose concentrate equivalent to or less than the daily production.

14. The method according to claim 12 or 13, wherein: The capacity of the storage tank and / or the first and second storage tanks is sufficient to store a volume of the alkali cellulose concentrate corresponding to 1 / 12 to 1 times the daily production.

15. The method according to any one of claims 1 to 14, wherein: The process is a continuous process.

16. An alkaline cellulose concentrate, wherein: The alkali cellulose dope contains 0.5 g or less of CO2 / kg dissolved therein based on the total weight of the alkali cellulose dope; and / or wherein, The concentration of carbonate ions in the alkaline cellulose dope is 1.5% (w / w) or less.

17. The method according to any one of claims 1 to 15 or the alkaline cellulose dope according to claim 16, wherein The alkaline cellulose dope has a viscosity in the range of 2000-100000 mPas, or in the range of 2000-20000 mPas, or in the range of 2000-10000 mPas, or in the range of 3000-6000 mPas.

18. The method according to any one of claims 1 to 15 or 17 or the alkaline cellulose dope according to claim 16 or 17, wherein During a period of at least 24 hours during which the cellulosic material is dissolved in the alkali cellulose dope, the alkali cellulose dope has a viscosity of 10000 mPas or less.

19. A product obtainable by coagulation of an alkali cellulose dope from a cold alkaline process, wherein: The product contains 1.0% (w / w) or less carbonate ions.

20. The product of claim 19, wherein: The product can be obtained from the alkali cellulose dope according to any one of claims 16 to 18 by extrusion, spinning, electrospinning, molding, casting, film formation, coating, cellulose bead production, spraying or printing, and coagulation of the alkali cellulose dope.

21. The product of claim 19 or 20, wherein: The product is a pellet, powder, film, filament, staple fiber, bead, melt, 3D shape, coating, hot melt adhesive, container, shell, casing, packaging article, film label, paper, medical device, plastic or composite profile, abrasive grain, abrasive film or paper, and / or 3D printing filament.

22. The product of any one of claims 19 to 21, wherein The product has a CED viscosity in the range of 100-300 ml / g, or in the range of 140-200 ml / g, or in the range of 150-180 ml / g.

23. A product as claimed in any one of claims 19 to 22, wherein The products are filaments and / or staple fibers and have a tenacity of 15 cN / tex or more.

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