CN115044985A - Method for preparing fiber spinning solution by low-temperature dissolution - Google Patents
Method for preparing fiber spinning solution by low-temperature dissolution Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000009987 spinning Methods 0.000 title claims abstract description 28
- 238000004090 dissolution Methods 0.000 title claims abstract description 26
- 239000000835 fiber Substances 0.000 title claims abstract description 26
- 239000000243 solution Substances 0.000 claims abstract description 59
- LFTLOKWAGJYHHR-UHFFFAOYSA-N N-methylmorpholine N-oxide Chemical compound CN1(=O)CCOCC1 LFTLOKWAGJYHHR-UHFFFAOYSA-N 0.000 claims abstract description 50
- 230000008961 swelling Effects 0.000 claims abstract description 45
- 239000011259 mixed solution Substances 0.000 claims abstract description 26
- 229920000642 polymer Polymers 0.000 claims abstract description 21
- 238000010438 heat treatment Methods 0.000 claims abstract description 17
- 239000005456 alcohol based solvent Substances 0.000 claims abstract description 6
- 239000004210 ether based solvent Substances 0.000 claims abstract description 6
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 29
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 27
- 239000002904 solvent Substances 0.000 claims description 26
- 238000003756 stirring Methods 0.000 claims description 15
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 10
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 10
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 9
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 9
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 6
- 239000002202 Polyethylene glycol Substances 0.000 claims description 6
- 229920001223 polyethylene glycol Polymers 0.000 claims description 6
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 5
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 4
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 claims description 4
- LZDKZFUFMNSQCJ-UHFFFAOYSA-N 1,2-diethoxyethane Chemical compound CCOCCOCC LZDKZFUFMNSQCJ-UHFFFAOYSA-N 0.000 claims description 3
- DURPTKYDGMDSBL-UHFFFAOYSA-N 1-butoxybutane Chemical compound CCCCOCCCC DURPTKYDGMDSBL-UHFFFAOYSA-N 0.000 claims description 3
- 230000001476 alcoholic effect Effects 0.000 claims 1
- 229920002678 cellulose Polymers 0.000 abstract description 38
- 239000001913 cellulose Substances 0.000 abstract description 38
- 238000005265 energy consumption Methods 0.000 abstract description 9
- 230000009286 beneficial effect Effects 0.000 abstract description 5
- 230000015556 catabolic process Effects 0.000 abstract description 5
- 238000006731 degradation reaction Methods 0.000 abstract description 5
- 230000002522 swelling effect Effects 0.000 abstract description 5
- 230000035699 permeability Effects 0.000 abstract description 4
- 238000009792 diffusion process Methods 0.000 abstract description 3
- 239000005416 organic matter Substances 0.000 abstract description 3
- 239000000084 colloidal system Substances 0.000 description 28
- ZTHYODDOHIVTJV-UHFFFAOYSA-N Propyl gallate Chemical compound CCCOC(=O)C1=CC(O)=C(O)C(O)=C1 ZTHYODDOHIVTJV-UHFFFAOYSA-N 0.000 description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 238000011978 dissolution method Methods 0.000 description 8
- 239000002994 raw material Substances 0.000 description 8
- 239000002245 particle Substances 0.000 description 6
- 239000000473 propyl gallate Substances 0.000 description 6
- 229940075579 propyl gallate Drugs 0.000 description 6
- 235000010388 propyl gallate Nutrition 0.000 description 6
- 229920000433 Lyocell Polymers 0.000 description 5
- 238000009835 boiling Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000002360 preparation method Methods 0.000 description 5
- 229920000875 Dissolving pulp Polymers 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000003292 glue Substances 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 229920003043 Cellulose fiber Polymers 0.000 description 3
- 238000006116 polymerization reaction Methods 0.000 description 3
- 239000003381 stabilizer Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 238000004043 dyeing Methods 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 239000011121 hardwood Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011122 softwood Substances 0.000 description 2
- 239000013526 supercooled liquid Substances 0.000 description 2
- 210000002268 wool Anatomy 0.000 description 2
- 241000209128 Bambusa Species 0.000 description 1
- 235000017166 Bambusa arundinacea Nutrition 0.000 description 1
- 235000017491 Bambusa tulda Nutrition 0.000 description 1
- 229920000742 Cotton Polymers 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 235000015334 Phyllostachys viridis Nutrition 0.000 description 1
- 229920000297 Rayon Polymers 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- 238000002835 absorbance Methods 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000003729 cation exchange resin Substances 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000001112 coagulating effect Effects 0.000 description 1
- 239000000539 dimer Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000007730 finishing process Methods 0.000 description 1
- 244000144992 flock Species 0.000 description 1
- 239000002655 kraft paper Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 235000021395 porridge Nutrition 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000004781 supercooling Methods 0.000 description 1
- 229920002994 synthetic fiber Polymers 0.000 description 1
- 239000012209 synthetic fiber Substances 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
- 238000002166 wet spinning Methods 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D1/00—Treatment of filament-forming or like material
- D01D1/02—Preparation of spinning solutions
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
- Y02P70/62—Manufacturing or production processes characterised by the final manufactured product related technologies for production or treatment of textile or flexible materials or products thereof, including footwear
Landscapes
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Artificial Filaments (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
Abstract
The invention provides a method for preparing fiber spinning solution by low-temperature dissolution, which comprises the following steps: s1) mixing one or more of low molecular weight alcohol solvents, low molecular weight ether solvents and polymers with the high-concentration NMMO solution to obtain a mixed solution; s2) mixing the mixed solution with crushed pulp for swelling, then vacuumizing and heating to 75 ℃ or above for dissolving to obtain fiber spinning solution; the temperature of the swelling is less than or equal to 55 ℃. Compared with the prior art, the invention is swelled at low temperature, is not easy to form initial dissolution, is beneficial to full permeation and diffusion of NMMO solution, is more complete in swelling, and can increase the permeability of the solution to cellulose by the added organic matter, thereby further increasing the swelling effect; in addition, the added organic matters can be removed by heating, and reach a dissolving area in a short time, so that the thermal degradation of the cellulose is greatly reduced while the energy consumption and the cost are saved, and the mechanical property strength of the cellulose is improved.
Description
Technical Field
The invention belongs to the technical field of fiber preparation, and particularly relates to a method for preparing a fiber spinning solution by low-temperature dissolution.
Background
Cellulose is a natural high polymer with the largest reserve and the widest distribution on the earth, and is an inexhaustible renewable resource in the nature. Since cellulose fibers have advantages such as high strength, good dyeability, good spinning performance, and wide industrial applications, the market demand for cellulose fibers has been increasing worldwide in recent years.
The Lyocell fiber is prepared by using renewable resources such as cotton linters, trees, bamboos and the like as raw materials and NMMO as a solvent through dry-jet wet spinning, has a plurality of excellent performances of natural fiber and synthetic fiber, and is a green and environment-friendly cellulose fiber in the production process.
The Lyocell fiber has the advantages of high strength, good dyeing property, good spinning performance, wide industrial application and the like, and compared with viscose fiber, the Lyocell fiber has more outstanding performance, short process flow and green and pollution-free production process. Therefore, the worldwide market demand for Lyocell fibers has continued to increase in recent years.
At present, the preparation method of the Lyocell fiber spinning solution mainly comprises an indirect dissolution method (a wet method and a dry method) and a direct dissolution method.
An indirect dissolution method: mixing the aqueous solution of the NMMO with medium and low concentration with cellulose pulp, fully swelling, and then distilling under reduced pressure to remove excessive water to reach a dissolution interval to complete dissolution, wherein the NMMO solution with medium and low concentration can not dissolve cellulose, and the excessive water is beneficial to fully swelling cellulose molecules in a solvent to easily form uniform pulp. The indirect dissolution method can be divided into a wet method and a dry method. The wet process includes mixing pulp with water, crushing, squeezing pulp solution to eliminate water, crushing, mixing with NMMO, and swelling in a storage tank to combine NMMO and cellulose fully to form cellulose pulp gruel. When wet pulp and NMMO solution are mixed in the wet process, the concentration of NMMO is about 80-84%, after swelling is completed, the pulp porridge is conveyed to a reaction kettle (such as a film evaporator) to be dissolved to form spinning solution, and the spinning solution is conveyed to a spinning machine to complete spinning. The pulp in the dry method does not need to be mixed with water, crushed and the like, and is directly mixed with the NMMO solution in a pulp board form, and compared with the wet method, the process of hydraulic pulp crushing and squeezing is omitted. The concentration of NMMO solution required by mixing dry pulp is between 75% and 80%. After swelling, conveying the slurry to a reaction kettle (such as a film evaporator) for dissolving to form a spinning solution, and conveying the spinning solution to a spinning machine to finish spinning. The existing dry method mainly adopts medium-high concentration NMMO (75-80%) to stir and swell at 80-85 ℃ and completely swell, and then the NMMO is added into a vacuum stirring reaction kettle and stirred at about 95-105 ℃ to evaporate water in vacuum for 2-3 hours until a dissolving interval is reached to prepare transparent and uniform colloid. However, this method has the following disadvantages: the swelling temperature is high, and the energy consumption is high. Secondly, the swelling temperature is high, the initial dissolution is easy to occur, a gel layer is formed on the surface of the cellulose to prevent the solvent from continuously permeating and diffusing into the cellulose, and the prepared glue solution may contain a part of undissolved white cores. The vacuum evaporation temperature is higher, the energy consumption is high, cellulose, PG, NMMO and the like are easy to be thermally degraded, the reaction time is longer, the quality performance and quality of subsequent glue solution and finished silk are reduced, and the burden of anion and cation resin for subsequent solvent recovery is increased along with the deepening of the color of the glue solution. And fourthly, the swelling temperature is simply and directly reduced, the NMMO solution is easy to crystallize and solidify, the permeation swelling speed is reduced, and the swelling effect is poor.
Still others have prepared colloids with 1-3% cellulose content by directly adding NMMO solids to ethanol solutions in laboratories, and have the following disadvantages: firstly, the preparation cost of the NMMO solid is too high; secondly, the NMMO solid is darker in color, so that the quality of subsequent finished silk products is adversely affected, and the burden of anion-cation exchange resin in a solvent recovery workshop is increased; the added ethanol content is too much, the cost is increased, and potential safety hazards exist in the actual production when the ethanol content is too high: fourthly, the content of the prepared colloidal cellulose is 1 to 3 percent, and the content is too low to be applied to actual production.
Direct dissolution method: directly mixing the high-concentration NMMO solution with dissolving capacity with the crushed cellulose pulp under a proper condition, and directly completing the dissolution without swelling. The method does not need to remove water in the dissolving process, simplifies the process, but because the cellulose is dissolved when being contacted with a high-concentration NMMO solution, solvent molecules may not permeate into the cellulose, the surface is already initially dissolved, a 'gel cluster' is easily formed, the solvent is prevented from continuously permeating and diffusing into the cellulose, and the prepared glue solution may contain a part of insoluble white cores. In order to overcome the disadvantages of the direct dissolution method, the following solutions are mainly available: firstly, crushing a cellulose raw material into particle wool with extremely small particle size; secondly, supercooling liquid of NMMO/hydrosolvent is used, the dissolving capacity of the solvent is reduced or lost at low temperature, and the cellulose is fully swelled and then dissolved at elevated temperature. However, the raw materials are crushed into flocks, so that the cost is high, potential safety hazards are easily caused when flocked cellulose is used as the raw materials in a workshop, and if large particles are used as the raw materials and complete dissolution is ensured, the flocked cellulose needs to be destroyed by a large rotating speed or strong mechanical force, so that the physicochemical properties of the cellulose can be influenced; physically preparing the supercooled liquid of the high-concentration NMMO/hydrosolvent can be realized only by sudden temperature drop in a short time, and has high technical requirement, higher cost and unsuitable workshop production; the chemical method for preparing the supercooled liquid of the high-concentration NMMO/hydrosolvent needs to add polyvinyl alcohol, the alcohol has higher molecular weight, is white solid, needs to be heated and stirred for dissolution, has higher viscosity, can reduce the permeation of NMMO during pulp premixing to a certain degree, reduces the solubility of cellulose in the NMMO solution, has more molecular chains after the polyvinyl alcohol is added, is easy to generate intermolecular entanglement due to higher viscosity and more molecular chains, is not easy to be washed away in the spinning process, can cause the increase of the hygroscopicity of the fiber, improves the moisture absorption and expansion ratio of the fiber, causes scratches in the fabric dyeing and finishing process, influences the dimensional stability of the fabric, has higher boiling point of the polyvinyl alcohol (PVC), is not beneficial to seven-effect evaporation and recovery after the polyvinyl alcohol (PVC) is added, is subjected to swelling and dissolution by a double-screw extruder to prepare colloid, and the single double-screw extruder has smaller capacity and can be limited, a plurality of twin-screw extruders are required, and the equipment cost is high.
Disclosure of Invention
In view of the above, the technical problem to be solved by the present invention is to provide a method for preparing a fiber spinning dope by low temperature dissolution.
The invention provides a method for preparing fiber spinning solution by low-temperature dissolution, which comprises the following steps:
s1) mixing one or more of low molecular weight alcohol solvents, low molecular weight ether solvents and polymers with the high-concentration NMMO solution to obtain a mixed solution; the polymer comprises one or more of hydroxyl, carboxyl and amino;
s2) mixing the mixed solution with crushed pulp for swelling, and then heating to 75 ℃ or above for dissolving to obtain fiber spinning solution; the temperature of the swelling is less than or equal to 55 ℃.
Preferably, the mass of one or more of the low molecular weight alcohol solvent, the low molecular weight ether solvent and the polymer is 0.1-18% of the mass of the mixed solution.
Preferably, the mass concentration of the high-concentration NMMO solution is 82% -87%; the mass concentration of NMMO in the mixed solution is greater than or equal to 72%.
Preferably, the low molecular weight alcohol solvent is selected from one or more of ethanol, ethylene glycol, glycerol and isopropanol; the low molecular weight ether solvent is selected from one or more of diethyl ether, butyl ether and ethylene glycol diethyl ether; the polymer is selected from one or more of polyvinyl alcohol, polyethylene glycol and dihydric alcohol.
Preferably, the comminuted pulp is a granular pulp and/or a hand-torn bulk pulp.
Preferably, the mass of the crushed pulp is 9 to 19 percent of the total mass of the crushed pulp and the mixed solution.
Preferably, the swelling temperature is 50-55 ℃; the swelling time is 15-60 min.
Preferably, the dissolving temperature is 75-98 ℃; the dissolving time is 1-1.5 h.
Preferably, the swelling and dissolving are carried out under stirring conditions; the rotating speed of the stirring is 60-300 rpm.
Preferably, the dissolution is carried out under vacuum conditions; the vacuum degree under the vacuum condition is-0.098 MPa.
The invention provides a method for preparing fiber spinning solution by low-temperature dissolution, which comprises the following steps: s1) mixing one or more of low molecular weight alcohol solvents, low molecular weight ether solvents and polymers with the high-concentration NMMO solution to obtain a mixed solution; the polymer comprises one or more of hydroxyl, carboxyl and amino; s2) mixing the mixed solution with crushed pulp for swelling, and then heating to 75 ℃ or above for dissolving to obtain fiber spinning solution; the temperature of the swelling is less than or equal to 55 ℃. Compared with the prior art, the invention is swelled at low temperature, is not easy to form initial dissolution, is beneficial to full permeation and diffusion of NMMO solution, is more complete in swelling, and can increase the permeability of the solution to cellulose by the added organic matter, thereby further increasing the swelling effect; in addition, the added organic matters can be removed by heating or vacuum heating, the organic matters reach a dissolving area in a short time, the vacuum heating also reduces the dissolving temperature, the thermal degradation of the cellulose is greatly reduced while the energy consumption and the cost are saved, and the mechanical property strength of the cellulose is further improved.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a method for preparing fiber spinning solution by low-temperature dissolution, which comprises the following steps: s1) mixing one or more of low molecular weight alcohol solvents, low molecular weight ether solvents and polymers with the high-concentration NMMO solution to obtain a mixed solution; the polymer comprises one or more of hydroxyl, carboxyl and amino; s2) mixing the mixed solution with crushed pulp for swelling, and then heating to 75 ℃ or above for dissolving to obtain fiber spinning solution; the temperature of the swelling is less than or equal to 55 ℃.
In the present invention, the sources of all raw materials are not particularly limited, and they may be commercially available.
Mixing one or more of low molecular weight alcohol solvent, low molecular weight ether solvent and polymer with high-concentration NMMO solution to obtain mixed solution; the low molecular weight alcohol solvent is not particularly limited as long as it is well known to those skilled in the art, and in the present invention, one or more of ethanol, ethylene glycol, glycerol and isopropanol are preferable; the low molecular weight ether solvent is not particularly limited, but is preferably one or more of diethyl ether, dibutyl ether and ethylene glycol diethyl ether; the polymer is not particularly limited as long as it is a hydroxyl group-containing polymer known to those skilled in the art, and in the present invention, one or more of polyvinyl alcohol, polyethylene glycol and dihydric alcohol is preferable; the molecular weight of the polyvinyl alcohol is preferably 2.5-3.5 ten thousand; the molecular weight of the polyethylene glycol is preferably 1000-5000, and the molecular weight of the dimer alcohol is preferably 537; the mass of one or more of the low molecular weight alcohol solvent, the low molecular weight ether solvent and the polymer is preferably 0.1 to 18% of the mass of the mixed solution, more preferably 0.1 to 15%, still more preferably 0.1 to 10%, still more preferably 0.1 to 5%, still more preferably 0.1 to 3%, and most preferably 0.1 to 2%; the mass concentration of the high-concentration NMMO solution is preferably 82% -87%, preferably 82.8% -85%, and more preferably 82.8% -84.5%; the mass concentration of NMMO in the mixed solution is preferably greater than or equal to 72%; when the boiling point of the low molecular weight alcohol solvent, the low molecular weight ether solvent and the polymer is higher than 110 ℃, the mass concentration of the NMMO in the mixed solution is preferably not less than 80%, more preferably not less than 83%.
Mixing the mixed solution with crushed pulp for swelling; the pulp is preferably hardwood dissolving pulp and/or softwood dissolving pulp (but not limited to), more preferably kraft hardwood dissolving pulp and/or softwood sulfite dissolving pulp; the content of α -cellulose in the pulp is preferably 90% or more, more preferably 95% or more; the intrinsic viscosity of the pulp is preferably 400-480 ml/g, more preferably 420-460 ml/g, and still more preferably 440 ml/g; the content of Fe in the pulp is preferably less than 5 ppm; the water content of the pulp is preferably 5-10%, more preferably 6-8%, and still more preferably 7%; in the invention, pulp does not need to be beaten into wool or superfine particles, larger particles or large pulp plates are added to fully permeate and swell, and transparent and uniform colloid is obtained by heating and dissolving, so that the crushed pulp is preferably granular pulp and/or hand-torn large pulp; the mass of the crushed pulp is preferably 9-19%, more preferably 10-15%, and even more preferably 12-14% of the total mass of the pulp and the mixed solution; in the present invention, it is preferable to further add a stabilizer; the kind of the stabilizer is not particularly limited as long as it is known to those skilled in the art, but Propyl Gallate (PG) is preferable in the present invention; the mass of the stabilizer is preferably 0.5 to 10 percent of the mass of the crushed pulp, more preferably 2 to 8 percent, even more preferably 4 to 6 percent, and most preferably 4.6 percent; the swelling temperature is less than or equal to 55 ℃, and is preferably 25-55 ℃; in consideration of the speed and effect of swelling, in the present invention, the temperature of swelling is more preferably 50 to 55 ℃; the lower temperature leads the medium and high concentration NMMO solution to lose the dissolving capacity to the cellulose or the dissolving capacity is greatly weakened, thus leading the cellulose particles to only swell in the high concentration NMMO solution at the low temperature or hardly dissolve in a short time, and completely preventing the surface of the cellulose from forming a gel layer to prevent the further permeation of the NMMO; the lower the swelling temperature is, the better the swelling temperature is, the lower the temperature is, although the energy requirement is low, the temperature is too low, the swelling permeation speed is too low, the verified temperature can be selected to ensure both energy consumption and the swelling speed, and the temperature is reduced, although the swelling speed is reduced, the addition of one or more of a low molecular weight alcohol solvent, a low molecular weight ether solvent and a polymer can increase the permeability of the solution to cellulose and increase the swelling effect; the swelling is preferably carried out under stirring; the stirring is preferably low-speed stirring; the rotating speed of the stirring is preferably 60-300 rpm; the swelling time is preferably 15-60 min, more preferably 20-50 min, and still more preferably 30-40 min.
After swelling fully, heating to 75 ℃ or above for dissolving to obtain fiber spinning solution; the new process of adding the low-boiling point additive changes the evaporated water into the evaporated low-boiling point organic solvent, and the transparent colloid with good uniform state can be prepared without vacuumizing, thereby greatly saving energy consumption; the solution can be heated and dissolved under the vacuum condition, and low molecular weight organic matters can be quickly evaporated and defoamed at the same time, so that transparent and uniform colloid can be obtained in a short time; the vacuum degree of the vacuum condition is preferably-0.098 MPa; adding high boiling point additive, swelling, heating to 75 deg.C or above for dissolving, and directly obtaining transparent and uniform fiber spinning solution without evaporating water; the dissolving temperature is preferably 75-98 ℃, more preferably 85-98 ℃, and further preferably 90-95 ℃; the dissolving time is preferably 1-1.5 h; the dissolution is preferably carried out under stirring; the stirring is preferably low-speed stirring; the rotating speed of the stirring is preferably 60-300 rpm. The swelling and dissolving temperature is lower, the energy consumption cost can be greatly saved, the thermal degradation of the cellulose is greatly reduced, the mechanical property strength of the cellulose is obviously improved, the color of the colloidal solvent is obviously lightened, and the burden of the anion-cation resin for subsequent solvent recovery is greatly reduced.
The invention is swelled at low temperature, is not easy to form initial dissolution, is beneficial to full permeation and diffusion of NMMO solution, is more complete in swelling, and can increase the permeability of the solution to cellulose by the added organic matter, thereby further increasing the swelling effect; in addition, the added organic matters can be removed by heating or vacuum heating, the organic matters reach a dissolving area in a short time, the vacuum heating also reduces the dissolving temperature, the thermal degradation of the cellulose is greatly reduced while the energy consumption and the cost are saved, and the mechanical property strength of the cellulose is further improved.
To further illustrate the present invention, the following examples are provided to describe the method of preparing a fiber dope by low temperature dissolution.
The reagents used in the following examples are all commercially available; the pulp sheet used in the examples was of the type BSC 430-Brazilian pulp DP 430.
The tests obtained in the examples were carried out according to the following methods:
1. zero-shear viscosity of the colloid: detecting the zero-cut viscosity at 85 ℃ by using a Haake rheometer;
2. the polymerization degree of the colloid is that the colloid is washed and dried, then ground into powder, and the polymer of the fiber in the colloid is obtained by measuring with an Ubbelohde viscometer after the cuprammonia solution is dissolved;
3. color of the colloid: 10g of colloid is added into 500g of water, the mixture is completely soaked, and the ultraviolet selective absorbance is used for testing the chroma at 400 nm.
Example 1
Raw materials: BSC430 large-block hand-torn pulp board 7.471g, Propyl Gallate (PG)0.348g, 84.5% NMMO solution 49g + ether 1g mixed solution.
The novel process direct preparation method comprises the following steps: adding PG0.348g, hand-tearing large-block pulp 7.471g into 50g of mixed solution of NMMO and ether, stirring and premixing at 500rpm at 50 ℃ for about 30min, and then heating to 95 ℃ to react for 1.5h to prepare uniform and transparent colloid.
The traditional direct dissolution method comprises the following steps: adding PG0.348g and 7.471g of pulp board catkin crushed by a crusher into 50g of NMMO heated and melted 84.5% NMMO solution, then heating to 110 ℃, adjusting the rotating speed to about 500rpm, and reacting for 2.5h to prepare uniform and transparent colloid.
The physical and chemical properties of the colloid obtained in example 1 were measured, and the results are shown in table 1.
Table 1 example 1 colloidal property test data
| Conventional direct dissolution process | New process | |
| Temperature of dissolved colloid/. degree.C | 110 | 95 |
| Time to prepare colloid/h | 2 | 1 |
| Number of bright spots under microscope (undissolved fiber) | 1 | 1 |
| Content of cellulose% | 13.2 | 13.2 |
| Zero shear viscosity at 85 DEG C | 16000 | 22500 |
| Degree of polymerization of colloid | 378 | 410 |
| Color of the colloid | 725 | 250 |
Example 2
Raw materials: BSC430 bulk hand-tear pulp 7.471g, PG0.348g, mixed solution of 82.8% NMMO solution 49.95g +0.05g polyethylene glycol.
The new process direct dissolution preparation method comprises the following steps: PG and a hand-tearing large pulp board are added into a mixed solution of 50g of NMMO and polyethylene glycol, the mixture is stirred and premixed for about 30min at about 50 ℃ and 300rpm, and then the temperature is raised to 95 ℃ to react for 1.5h to prepare uniform and transparent colloid.
The traditional direct dissolution method comprises the following steps: PG0.348g and 7.471g of pulp board floc crushed by a crusher are added into 84.5 percent NMMO solution which is heated and melted by 50g of NMMO, then the temperature is raised to 110 ℃, the rotating speed is adjusted to be about 500rpm, and the uniform and transparent colloid is prepared after 2.5h of reaction.
The physical and chemical properties of the colloid obtained in example 2 were measured, and the results are shown in table 1.
Table 2 example 2 colloidal property test data
| Conventional direct dissolution process | New process | |
| Temperature of dissolved colloid/. degree.C | 110 | 95 |
| Time to prepare colloid/h | 2 | 1 |
| Number of bright spots under microscope (undissolved fiber) | 1 | 1 |
| Cellulose content% | 13.2 | 13.2 |
| Zero shear viscosity at 85 DEG C | 16000 | 22518 |
| Degree of polymerization of colloid | 378 | 411 |
| Color of the colloid | 725 | 252 |
Compared with the traditional method, the novel method for preparing the colloid by swelling at low temperature greatly reduces energy consumption, reduces fiber degradation, improves zero-cut viscosity and reduces chromaticity of the colloid and a coagulating bath.
Claims (10)
1. A method for preparing fiber spinning solution by low-temperature dissolution is characterized by comprising the following steps:
s1) mixing one or more of low molecular weight alcohol solvents, low molecular weight ether solvents and polymers with the high-concentration NMMO solution to obtain a mixed solution; the polymer comprises one or more of hydroxyl, carboxyl and amino;
s2) mixing the mixed solution with crushed pulp for swelling, and then heating to 75 ℃ or above for dissolving to obtain fiber spinning solution; the temperature of the swelling is less than or equal to 55 ℃.
2. The method according to claim 1, wherein the mass of one or more of the low molecular weight alcohol-based solvent, the low molecular weight ether-based solvent and the polymer is 0.1 to 18% of the mass of the mixed solution.
3. The method of claim 1, wherein the high concentration NMMO solution has a mass concentration of 82% to 87%; the mass concentration of NMMO in the mixed solution is greater than or equal to 72%.
4. The method of claim 1, wherein the low molecular weight alcoholic solvent is selected from one or more of ethanol, ethylene glycol, glycerol and isopropanol; the low molecular weight ether solvent is selected from one or more of diethyl ether, butyl ether and ethylene glycol diethyl ether; the polymer is selected from one or more of polyvinyl alcohol, polyethylene glycol and dihydric alcohol.
5. The method according to claim 1, characterized in that the comminuted pulp is a granular pulp and/or a hand-torn bulk pulp.
6. The method according to claim 1, characterized in that the mass of the comminuted pulp is 9% to 19% of the total mass of the comminuted pulp and the mixed solution.
7. The method of claim 1, wherein the swelling temperature is 50 ℃ to 55 ℃; the swelling time is 15-60 min.
8. The method of claim 1, wherein the temperature of dissolution is 75 ℃ to 98 ℃; the dissolving time is 1-1.5 h.
9. The method according to claim 1, wherein the swelling and dissolving are carried out under stirring conditions; the rotating speed of the stirring is 60-300 rpm.
10. The method according to claim 1, wherein the dissolving is performed under vacuum conditions; the vacuum degree under the vacuum condition is-0.098 MPa.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4290815A (en) * | 1980-01-28 | 1981-09-22 | Akzona Incorporated | Use of co-solvents in amine N-oxide solutions |
| JPS61275411A (en) * | 1985-05-27 | 1986-12-05 | Toyobo Co Ltd | Production of spinning stock solution |
| CN1612958A (en) * | 2003-06-30 | 2005-05-04 | 株式会社晓星 | A solution containing cellulose dissolved in N-methylmorpholine-N-oxide and high tenacity lyocell multifilament using the same |
| CN101240461A (en) * | 2007-02-08 | 2008-08-13 | 中国纺织科学研究院 | Method for preparing cellulose spinning fluid |
| CN114016141A (en) * | 2021-12-09 | 2022-02-08 | 赛得利(常州)纤维有限公司 | Method for preparing fiber spinning solution by direct dissolution method |
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- 2022-06-23 CN CN202210716699.6A patent/CN115044985A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4290815A (en) * | 1980-01-28 | 1981-09-22 | Akzona Incorporated | Use of co-solvents in amine N-oxide solutions |
| JPS61275411A (en) * | 1985-05-27 | 1986-12-05 | Toyobo Co Ltd | Production of spinning stock solution |
| CN1612958A (en) * | 2003-06-30 | 2005-05-04 | 株式会社晓星 | A solution containing cellulose dissolved in N-methylmorpholine-N-oxide and high tenacity lyocell multifilament using the same |
| CN101240461A (en) * | 2007-02-08 | 2008-08-13 | 中国纺织科学研究院 | Method for preparing cellulose spinning fluid |
| CN114016141A (en) * | 2021-12-09 | 2022-02-08 | 赛得利(常州)纤维有限公司 | Method for preparing fiber spinning solution by direct dissolution method |
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