WO2020103424A1 - 纤维素纤维的纺丝方法 - Google Patents

纤维素纤维的纺丝方法

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Publication number
WO2020103424A1
WO2020103424A1 PCT/CN2019/090123 CN2019090123W WO2020103424A1 WO 2020103424 A1 WO2020103424 A1 WO 2020103424A1 CN 2019090123 W CN2019090123 W CN 2019090123W WO 2020103424 A1 WO2020103424 A1 WO 2020103424A1
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Prior art keywords
cellulose
spinning
ionic liquid
tow
slime
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PCT/CN2019/090123
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English (en)
French (fr)
Inventor
赵张刚
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绍兴美标纺织品检验有限公司
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Application filed by 绍兴美标纺织品检验有限公司 filed Critical 绍兴美标纺织品检验有限公司
Publication of WO2020103424A1 publication Critical patent/WO2020103424A1/zh

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    • 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
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/06—Wet spinning methods
    • 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
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/04—Dry spinning methods
    • 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

Definitions

  • the invention relates to a method for spinning cellulose fibers, in particular to an industrialized method for spinning cellulose fibers using ionic liquid as a solvent.
  • Polypropylene (PP), polyester (PET), polyethylene (PE), nylon (Nylon) and other synthetic fibers derived from petrochemical resources have excellent properties and are still the most important fiber varieties.
  • PP polypropylene
  • PET polyester
  • PE polyethylene
  • nylon nylon
  • other synthetic fibers derived from petrochemical resources have excellent properties and are still the most important fiber varieties.
  • Cellulose has good biocompatibility and degradability, and has a wide range of sources, but its popularity is still not as good as the above-mentioned synthetic fibers.
  • the development and utilization of cellulose has gradually received people's attention.
  • Cellulose has high crystallinity, and there are a large number of hydrogen bonds between molecules and within molecules, making cellulose difficult to melt-spinning, and most solvents are also insoluble. This leads to limited processing and utilization of cellulose. Therefore, the development of environmentally friendly cellulose efficient solvents is very important for the widespread application of cellulose fibers.
  • Ionic liquids are not easily volatile under low vapor pressure, which solves the problem of environmental pollution caused by the easy evaporation of organic substances. Ionic liquids have the characteristics of low melting point and high polarity, and can dissolve many organic and inorganic substances. In addition, ionic liquids have the characteristics of non-flammability, resistance to strong acids, high thermal stability, high conductivity, and high electrochemical stability. In addition, ionic liquids can be designed according to different needs, giving them unique properties. The use of ionic liquids under normal pressure can not only reduce the cost, but also reduce the environmental pollution and harm to human beings caused by organic solvents. In summary, ionic liquids are called a kind of environmentally friendly solvents.
  • Cellulose-dissolving ionic liquids can be obtained by cations such as imidazoles and pyridines and anions such as amide, hexafluorophosphoric acid, tetrafluoroborate, acetate and halide.
  • anions such as amide, hexafluorophosphoric acid, tetrafluoroborate, acetate and halide.
  • CN101402658A discloses a method for catalyzing thermal degradation of cellulose by ionic liquid solvent, using alkyl imidazole chloride salt ionic liquid as solvent, and using solid acid less than 1% of total weight of raw material as catalyst in ionic liquid solution of cellulose Using ionic liquid as co-catalyst, homogenous catalytic thermal degradation of cellulose was carried out at 0.01 ⁇ 4.00MPa and 100 ⁇ 300 °C. This shows that ionic liquids also easily cause cellulose degradation. The degraded cellulose has a low degree of polymerization and cannot meet the requirements of high-speed spinning, which makes industrialization difficult.
  • CN102619026A discloses a method for preparing nano-microcellulosic fiber non-woven fabrics.
  • Cellulose powder and ionic liquid are made into a uniform mixture.
  • the mixture is fed into a twin-screw extruder to prepare a spinning solution. It is fed to the spinning die and extruded from the spinneret of the die to form a fine stream of spinning solution; high-pressure hot air is blown through the slit of the air cavity of the spinning die to form a high-speed air flow to the fine stream of spinning solution.
  • the nano-microcellulose fiber non-woven fabric is obtained.
  • the spinning speed of the above spinning process is slow, and only a non-woven fabric can be obtained, and high-strength cellulose fibers cannot be obtained.
  • CN103352266A discloses a method for preparing cellulose-thermoplastic polymer sheath-core composite fibers.
  • Cellulose and thermoplastic polymer are vacuum dried; the vacuum-dried cellulose and ionic liquid are added to a high-speed mixer according to the proportion to mix evenly; Add the mixture of cellulose and ionic liquid to one feeding port of the co-rotating twin screw extruder, add the thermoplastic polymer after vacuum drying to the other feeding port, and extrude both through the co-rotating twin screw extruder ,
  • the spinning module spinning through the spinneret, washing the obtained composite fiber through the water tank to remove the ionic liquid in the skin layer, and then drawing and winding through the spinning module to obtain cellulose and thermoplastic polymer skin Core composite fiber.
  • the fiber winding speed in the above method can reach 500-1500 m / min, but fiber-forming polymers such as polyester must be used as the core layer.
  • fiber-forming polymers such as polyester, not cellulose.
  • an object of the present invention is to provide a spinning method of cellulose fibers, which has a relatively high winding speed.
  • a further object of the invention is to provide a method for spinning cellulose fibers, the properties of the resulting cellulose being at least comparable to those of the NMMO method.
  • the invention provides a spinning method of cellulose fiber, which is made into cellulose fiber by dry-spray wet spinning method; wherein, the cellulose mucus is an ionic liquid solution of cellulose, and the cellulose Neither the slime nor the cellulose fiber contains other fiber-forming polymers, and the winding speed of the dry spray wet spinning method is 400 to 1500 m / min.
  • the method further comprises the steps of: heating the mixture of cellulose and ionic liquid at 50-100 ° C. for 3-10 minutes to obtain the cellulose mucus; wherein, the cellulose mucus
  • the viscosity is 1000 to 20000 poise
  • the cellulose content is 5 to 15 wt%
  • the light transmission index is 1.470 to 1.550
  • the rate of deterioration of the degree of polymerization of the cellulose in the cellulose slime is less than 15%.
  • the spinning method according to the present invention preferably includes the following steps:
  • the cellulose tow is introduced into a coagulation bath for coagulation, and the coagulated cellulose tow is washed, dried and wound to make cellulose fibers; wherein, the temperature of the coagulation bath is 5 to 45 ° C,
  • the coagulation bath is an ionic liquid aqueous solution with an ionic liquid concentration of less than 30% by weight; the winding speed is 400-1500 m / min.
  • the cellulose slime does not contain other fiber-forming polymers, and the rate of deterioration of the degree of polymerization of cellulose in the cellulose slime is less than 15%.
  • the viscosity of the cellulose slime is 1,000 to 20,000 poises
  • the cellulose content is 5 to 15 wt%
  • the light transmission index is 1.470 to 1.550.
  • the ⁇ -cellulose content of the cellulose is 65% or more; and the water content of the cellulose slime is 5-15 wt%.
  • the ionic liquid is composed of a cation and an anion
  • the cation is selected from imidazolyl or pyridyl
  • the anion is selected from chloride, bromide, At least one of iodide ion, hexafluorophosphate ion, nitrate ion, acetate ion, and aluminate ion.
  • the spinning temperature is 60 to 100 ° C.
  • the cellulose tow is first passed through a slit formed by a pair of regeneration slots; wherein, one of the regeneration slots
  • the side has a circular arc edge, the circular arc edge is oppositely formed to form the slit, and a water supplement device is provided on the regeneration tank.
  • the solidified cellulose tow is passed through two water washing wheels composed of rollers with a hollow grid, and the water washing liquid is The center of the roller is sprayed outward to the cellulose tow.
  • cellulose mucilage is spun into cellulose fibers by dry spray wet spinning.
  • the present invention can still obtain a very high winding speed, thereby making it possible to industrially spin cellulose using ionic liquids.
  • cellulose degradation can be effectively avoided, thereby making cellulose fibers have good performance.
  • Figure 1 is a schematic diagram of the spinning process of cellulose slime.
  • Figure 2 is a schematic diagram of the cellulose fiber spinning process.
  • the cellulose fiber of the present invention is a regenerated fiber, which is usually obtained by using natural cellulose as a raw material through processes such as dissolution, spinning, and winding.
  • Ionic liquid can be used as a solvent for cellulose, but the dissolution temperature is higher and the dissolution time is longer, which leads to the degradation of cellulose and affects its spinnability. Therefore, in the process of forming cellulose spinning solution (also called cellulose slime), it is necessary to avoid the degradation of cellulose, which is also the basis for improving the spinning speed of cellulose fibers.
  • the spinning method of the present invention includes a dissolving step, a spinning step, and the like.
  • the present invention found that the use of a thin-film evaporator can rapidly dissolve cellulose in an ionic liquid to reduce the degradation of cellulose.
  • the viscosity of the formed cellulose mucus is low, and the degradation rate of the polymerization degree is low.
  • the liquid material flows in a film shape along the wall of the heating tube, thereby performing heat transfer and evaporation.
  • Thin-film evaporators are generally suitable for the evaporation of heat-sensitive substances, and there is no report on their use in ionic liquids to dissolve cellulose. In addition, there is no direct connection between liquid evaporation and material dissolution.
  • thin film evaporators can be divided into rising film evaporators, falling film evaporators, scraped film evaporators, preferably falling film evaporators.
  • the type of thin film evaporator of the present invention is not particularly limited.
  • Thin-film evaporator unit usually consists of evaporator, gas-liquid separator, preheater and separator.
  • cellulose and the ionic liquid with a polymerization degree of 400 to 5000 are mixed uniformly at 40 to 60 ° C, and then a film evaporator is used to heat at 50 to 100 ° C for 3 to 10 minutes to obtain a cellulose slime.
  • the mixing temperature may be 40 to 60 ° C, preferably 50 to 55 ° C.
  • the mixing time is not particularly limited, as long as the two are uniformly mixed.
  • the dissolution temperature may be 50 to 100 ° C, preferably 60 to 80 ° C, and more preferably 65 to 75 ° C.
  • the dissolution time is 3 to 10 minutes, preferably 5 to 8 minutes.
  • the cellulose is fully dispersed, which accelerates the dissolution rate of cellulose in the ionic liquid.
  • the degree of polymerization of cellulose can be determined by the viscosity method, as described in detail below.
  • the degree of polymerization of cellulose may be 400 to 5000, preferably 400 to 3500, and more preferably 500 to 2000. This is conducive to the rapid dissolution of cellulose and high-speed spinning.
  • the cellulose of the present invention may be long-fiber wood pulp, short-fiber wood pulp, cotton pulp, bamboo pulp, etc .; or a mixture of two or more of them in different ratios.
  • the cellulose of the present invention is short fiber wood pulp or bamboo pulp.
  • the content of ⁇ -cellulose in cellulose is 65% or more, preferably 70% or more. This will help to improve its fiber-forming properties.
  • the ionic liquid of the present invention may be selected from imidazole type ionic liquid or pyridine type ionic liquid.
  • the cation of the imidazole-type ionic liquid is a substituted or unsubstituted imidazole cation
  • the cation of the pyridine-type ionic liquid is a substituted or unsubstituted pyridine cation.
  • the anion in the imidazole-type ionic liquid or pyridine-type ionic liquid can be selected from chloride ion, bromide ion, iodide ion, hexafluorophosphate ion, nitrate ion, acetate ion, tetrafluoroborate ion, aluminate ion Or more; preferably acetate ion or tetrafluoroborate ion.
  • the imidazole-type ionic liquid may be an imidazolium salt containing two substituents, wherein at least one substituent is an alkyl group, such as a dialkyl-substituted imidazolium salt.
  • the substituent may contain 1 to 30 carbon atoms; the substituent may be at the 1-position and 3-position of the imidazolium structure.
  • one of the substituents is a C1-C6 alkyl group, preferably a C1-C4 alkyl group; the other substituent is a C1-C6 hydrocarbon group, preferably a C1-C4 hydrocarbon group.
  • C1-C4 alkyl groups are not limited to methyl, ethyl, propyl, isopropyl, butyl, isobutyl or tert-butyl.
  • C1-C4 hydrocarbon groups are not limited to allyl, methyl, ethyl, propyl, isopropyl, butyl, isobutyl or tert-butyl.
  • the pyridine-type ionic liquid of the present invention may be a pyridinium salt containing a substituent, and the substituent may be a C1-C6 alkyl group, preferably a C1-C4 alkyl group.
  • substituent may be a C1-C6 alkyl group, preferably a C1-C4 alkyl group.
  • Examples of C1-C4 alkyl groups are not limited to methyl, ethyl, propyl, isopropyl, butyl, isobutyl or tert-butyl.
  • ionic liquid of the present invention include, but are not limited to: 1-ethyl-3-methyl-imidazolium chloride (EMIC), 1-butyl-3-methyl-imidazolium chloride (EMIC) , 1-butylpyridinium chloride (BPC), 1-butylpyridine hexafluorophosphate, 1-butylpyridine tetrafluoroborate, 1-ethyl-3-methyl-imidazole acetate, 1-ethyl-3-methylimidazolium tetrachloroaluminate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-allyl-3-methyl-imidazolium chloride ( [AMIm] Cl), 1-allyl-3-methyl-imidazole acetate or 1-butyl-3-methylimidazole acetate.
  • EMIC 1-ethyl-3-methyl-imidazolium chloride
  • EMIC 1-butyl-3-methyl-imid
  • Ionic liquids can be synthesized by conventional methods in the art, and will not be repeated here.
  • the ionic liquid of the present invention is selected from 1-ethyl-3-methyl-imidazolium acetate, 1-ethyl-3-methylimidazolium tetrachloroaluminate, 1-ethyl-3-methyl One of the imidazole tetrafluoroborate. This can further improve cellulose dissolution efficiency.
  • the imidazole-type ionic liquid of the present invention has the structure represented by formula (I):
  • R1 and R2 are independently selected from C1-C6 alkyl, C1-C6 alkyl-containing nitrile, C1-C6 alkyl-containing ester, phenyl, vinyl, C1-C6 alkyl-containing a hydroxyl group, a carboxyl group containing a C1 ⁇ C6 alkyl group, an ether group-containing C1 ⁇ C6 alkyl group and a sulfonic acid group containing a C1 ⁇ C6 alkyl group;
  • B - is selected from chloride, bromide, iodide, hexafluorophosphate One of phosphate ion, nitrate ion, acetate ion and aluminate ion.
  • the imidazole-type ionic liquid has the structure represented by formula (II):
  • R is selected from C1 ⁇ C6 alkyl group, a nitrile group-containing C1 ⁇ C6 alkyl group, C1 ⁇ C6 alkyl group having an ester group, a phenyl group, a vinyl group, C1 ⁇ C6 alkyl group having a hydroxyl group, C1 ⁇ carboxy C6 alkyl group, an ether group-containing C1 ⁇ C6 alkyl group and a sulfonic acid group containing a C1 ⁇ C6 alkyl group;
  • B - is selected from chloride, bromide, iodide, hexafluorophosphate, nitrate Root ion, acetate ion, aluminate ion.
  • the viscosity of the cellulose slime of the present invention may be 1,000 to 20,000 poises, preferably 5,000 to 10,000 poises. The above viscosities are measured at room temperature.
  • the cellulose content may be 5 to 15% by weight, preferably 6 to 10% by weight.
  • the light transmission index may be 1.470 to 1.550, preferably 1.470 to 1.500.
  • the cellulose slime of the present invention does not contain other fiber-forming polymers, such as polypropylene, polyester, polyamide and the like.
  • the rate of degradation of the polymerization degree of cellulose is less than 15%.
  • the above method can reduce the degradation of cellulose.
  • the degree of deterioration of the degree of polymerization of the resulting cellulose is less than 15%, preferably less than 12%, and more preferably less than 10%.
  • the specific formula is as follows:
  • Decay rate of polymerization degree (degree of polymerization of cellulose before dissolution-degree of polymerization of cellulose after dissolution) / degree of polymerization of cellulose before dissolution ⁇ 100%.
  • the cellulose mucilage is spun into cellulose fibers by dry-jet wet spinning.
  • the cellulose slime is an ionic liquid solution of cellulose, and neither the cellulose slime nor the cellulose fibers contain other fiber-forming polymers.
  • Fiber-forming polymer is a synthetic polymer that can be made into fibers. It has the ability to form fibers. It can be completely dissolved in a suitable solvent to form a thick concentrated solution for solution spinning, or it can be melted and converted into viscous Flow state without decomposition for melt spinning. Examples of other fiber-forming polymers include, but are not limited to, polypropylene, polyester, polyamide, and the like.
  • the cellulose fiber of the present invention can be used for spinning, weaving, etc., and is not a non-woven fabric or a fiber having a sheath-core structure.
  • the winding speed of the dry-jet wet spinning method of the present invention can reach 400-1500 m / min, preferably 600-150 m / min, more preferably 800-1500 m / min, for example 1000-1500 m / min. This is much higher than the normal NMMO spinning speed (for example, 200 m / min).
  • the cellulose slime is extruded from the spinneret hole, passes through an air interval of 0.5-30 cm, and is stretched in the presence of cooling air to form a cellulose tow.
  • the cellulose slime from the thin film evaporator enters the spinneret through a metering pump and other equipment, and is extruded from the spinneret's spinneret hole.
  • the spinning temperature is 60 to 100 ° C, preferably 70 to 85 ° C.
  • the ratio L / D of the length of the spinneret hole to the caliber is 3 to 15; preferably 5 to 13, more preferably 8 to 12. This is conducive to improving the orientation of cellulose molecules and creating conditions for high-speed spinning.
  • the temperature of the cooling air is 5 to 45 ° C, preferably 15 to 30 ° C; It is 60 to 99%, preferably 70 to 95%. This is conducive to improving the tensile properties of cellulose tow and avoiding breakage during solidification, thus creating conditions for high-speed spinning.
  • the cellulose tow Before introducing the cellulose tow into the coagulation bath, the cellulose tow is passed through a slit formed by a pair of regeneration tanks. In the coagulation bath, turbulence caused by high-speed stretching of the tow should be avoided. When the cellulose tow enters the coagulation bath, turbulent flow is caused by the high-speed stretching of the tow and the resistance of the liquid in the coagulation bath, which easily causes the cellulose tow to tangle and break. As shown in FIG. 1, one side of the first regeneration tank 4 a and the second regeneration tank 4 b each have an arc side, and the two arc sides are oppositely arranged to form a slit.
  • the cellulose tow 2 is extruded from the spinneret 1, and then passes through the slit. Such a design can guide the water flow and increase the bunching of the tow, thereby avoiding turbulent flow.
  • a water replenishment device 3 is provided on both regeneration tanks. When the cellulose tow 2 enters the coagulation bath, the cellulose tow 2 stretches the water flow at a high speed. At this time, the water supplement device 3 quickly replenishes water to avoid water shortage in the coagulation bath.
  • the cellulose tow is introduced into a coagulation bath for coagulation, and the coagulated cellulose tow is washed with water, dried and wound to make cellulose fibers.
  • the cellulose tow coagulated by the coagulation bath 22 passes through the water washing device 23, and then passes through the dryer 24, the oiler 25, and the winding device 26, thereby obtaining cellulose fibers.
  • the water washing device 23 includes a first water washing wheel 13a and a second water washing wheel 13b, each of which is composed of a roller having a hollow grille.
  • the washing liquid in the washing process will cause a large amount of water mist to splash due to the high-speed operation of the washing wheel, thereby reducing the washing efficiency and spinning stability.
  • the present invention passes the solidified cellulose tow through two water washing wheels composed of rollers with a hollow grille, and sprays the washing liquid from the center of the roller to the cellulose tow. In this way, the friction of the tow on the surface of the washing wheel can be reduced, and the water spray can be prevented from splashing due to the high-speed operation of the washing wheel, thereby greatly improving the washing efficiency and spinning stability.
  • the use of the above-mentioned water washing wheel can ensure that the tow is continuously threaded during high-speed operation, and is beneficial to greatly reduce the residual of ionic liquid in the cellulose fiber and improve the recovery rate of the ionic liquid.
  • the water washing liquid formed by water washing and the coagulation bath after coagulation treatment contain a part of the ionic liquid, and these liquids are filtered and concentrated to obtain an ionic liquid solvent, which is further used to dissolve cellulose for recycling purposes.
  • Filtration can use two-stage filtration. The first stage coarse filtration uses a general cartridge filter; the second stage fine filtration uses a precision filter (UF). The purity of the filtrate after fine filtration is the same as that of fresh solvent. Concentration can concentrate the recovered solvent concentration from 3.5 to 8.0 wt% to 85 to 95 wt%.
  • the three-effect concentration method is adopted, and the steam consumption is about 0.5 tons per ton of water removal; when the fiber output is large, the MVR concentration method is used, and the water removal is about 0.003 to 0.03 tons of steam per ton.
  • the resulting concentrate and condensate can all be recovered.
  • the concentrated liquid is used in the process of dissolving cellulose, and the process of condensate water supply and washing.
  • the temperature of the coagulation bath is 5 to 45 ° C; preferably 15 to 30 ° C.
  • the coagulation bath is an ionic liquid aqueous solution with an ionic liquid concentration of less than 30% by weight; preferably an ionic liquid aqueous solution with an ionic liquid concentration of less than 8% by weight.
  • the ionic liquid here is the same as the ionic liquid in the above dissolution step, and will not be repeated here.
  • the winding speed of the dry-jet wet spinning method of the present invention can reach 400-1500 m / min, preferably 600-150 m / min, more preferably 800-1500 m / min, for example 1000-1500 m / min.
  • the cellulose fiber obtained by the above method has a tensile strength (dry strength) of 3.0 to 6.0 g / d and an elongation at break of 5.0 to 12.0%, which is equivalent to the cellulose fiber obtained by the NMMO method, and can meet the requirements for cellulose Fiber requirements.
  • Determination of fiber mechanical properties According to the method of ASTM D2256, the mechanical properties of the fiber such as breaking strength and elongation at break are tested using the British Instron 4685 type tensile tester. The clamping distance is 20 mm, the drawing speed is 20 cm / min, the environmental conditions for fiber pre-conditioning are 20 ⁇ 3 ° C, and the relative humidity is 65% ⁇ 5%. Each sample is tested 10 times, and the results are averaged.
  • Determination of shrinkage of hot water in fiber Refer to GB / T6506-2001 to carry out the experiment of shrinkage of hot water.
  • the hot water treatment time is 30min
  • the temperature is 50 ⁇ 130 °C
  • a test point is set every 10 °C
  • each test point is tested 9 times.
  • the formula for hot water shrinkage S is as follows:
  • Lo is the length of the sample before hot water treatment
  • Ls is the length of the sample after hot water treatment.
  • Viscosity measurement of cellulose mucilage Refer to the textile industry standard of the People's Republic of China: Determination of viscosity of pulp for viscose fiber "Intrinsic Viscosity Measurement-Copper Ethylenediamine Solution Method (Method A)" in FZ / T50010.3-1998 To determine the relative viscosity ( ⁇ relative ) of cellulose mucus.
  • h is the constant of the measuring viscometer measured during calibration, the unit is second -1 ;
  • t 1 is the time when the sample solution flows through the measuring viscometer, the unit is second.
  • Capillary viscometer for calibration (0.57 ⁇ 0.02) mm; capillary viscometer for measurement: (0.80 ⁇ 0.05) mm; constant temperature water bath: control temperature at (25 ⁇ 1) ° C, with external circulation pump; Sample dissolution bottle: a polyethylene plastic bottle with a screw cap and a volume of 52mL.
  • the [ ⁇ ] ⁇ C value is found from the correspondence relationship between the relative ( ⁇ / ⁇ 0 ) value and the [ ⁇ ] ⁇ C value of different relative viscosities, and then the [ ⁇ ] value is obtained.
  • [ ⁇ ] is the intrinsic viscosity, mL / g
  • C is the concentration of cellulose mucus, g / mL.
  • the degree of polymerization of cellulose is calculated by measuring the viscosity of the copper ethylenediamine solution of cellulose. Dissolving cellulose in a copper ethylenediamine solution at a predetermined concentration, was measured at (25 ⁇ 1) at °C cellulose mucus and water through the outflow time of a capillary viscometer, to calculate the relative viscosity of a cellulose mucus ([eta] relative ) the relative viscosity ([eta] relative) and the [ ⁇ ] ⁇ C value correspondence table isolated [ ⁇ ] ⁇ C values, and the intrinsic viscosity is determined according to a known concentration of the solution to be measured [[eta]] value, and then according to the fiber
  • Ionic liquid (1-ethyl-3-methylimidazole acetate, the concentration of the aqueous solution is 90wt%) and wood pulp cellulose (degree of polymerization is 600) are mixed uniformly at 50 °C, using a thin film evaporator at 65 °C It was heated for 8 minutes to obtain cellulose mucus (see Table 1), and the rate of degradation of the polymerization degree was less than 10%.
  • the dry-spray wet spinning method is used for spinning.
  • the cellulose slime was extruded from the spinneret hole, passed through an air gap of 10 cm, and stretched in the presence of cooling air to form a cellulose tow.
  • the ratio of the length of the spinneret hole to the diameter (L / D) is 10 to improve the orientation of the cellulose molecules.
  • the temperature of the cooling air is 25 ° C and the relative humidity is 80%.
  • the cellulose tow solidifies in the coagulation bath.
  • the temperature of the coagulation bath is 25 ° C.
  • the coagulation bath is an aqueous solution of ionic liquid, and the concentration of the ionic liquid is less than 8.0 wt%.
  • the coagulated cellulose tow is washed, dried and wound to make cellulose fibers.
  • the winding speed is 1000m / min.
  • the water washing liquid and coagulation liquid with too high concentration of ionic liquid formed in the water washing process are filtered and concentrated, and then recycled. See Table 2 for properties of cellulose fibers.
  • the ionic liquid (1-ethyl-3-methylimidazole acetate, the concentration of the aqueous solution is 90wt%) and the wood pulp cellulose (degree of polymerization 1050) are mixed uniformly at 50 ° C, using a thin film evaporator at 75 ° C It was heated for 5 minutes to obtain a cellulose slime (see Table 3), and the rate of degradation of the polymerization degree was less than 9%.
  • the dry-spray wet spinning method is used for spinning.
  • the cellulose slime was extruded from the spinneret hole, passed through an air gap of 10 cm, and stretched in the presence of cooling air to form a cellulose tow.
  • the ratio of the length of the spinneret hole to the diameter (L / D) is 10 to improve the orientation of the cellulose molecules.
  • the temperature of the cooling air is 25 ° C and the relative humidity is 80%.
  • the cellulose tow after cooling and drawing enters the coagulation bath and solidifies.
  • the temperature of the coagulation bath is 25 ° C.
  • the coagulation bath is an aqueous solution of ionic liquid, and the concentration of the ionic liquid is less than 10% by weight.
  • the coagulated cellulose tow is washed, dried and wound to make cellulose fibers.
  • the winding speed is 1400m / min.
  • the water washing liquid and coagulation liquid with too high concentration of ionic liquid formed in the water washing process are filtered and concentrated, and then recycled. See Table 4 for properties of cellulose fibers.
  • the oxidized methyl morpholine and wood pulp cellulose (degree of polymerization 600) were mixed uniformly and heated at 90 ° C for 8 hours to obtain a cellulose slime.
  • the dry-spray wet spinning method is used for spinning.
  • the cellulose slime was extruded from the spinneret hole, passed through an air gap of 10 cm, and stretched in the presence of cooling air to form a cellulose tow.
  • the ratio of the length of the spinneret hole to the diameter (L / D) is 10 to improve the orientation of the cellulose molecules.
  • the temperature of the cooling air is 25 ° C and the relative humidity is 80%.
  • the cellulose tow solidifies in the coagulation bath.
  • the temperature of the coagulation bath is 25 ° C, and the coagulation bath is an aqueous solution with an NMMO concentration of less than 8.0 wt%.
  • the coagulated cellulose tow is washed, dried and wound to make cellulose fibers.
  • the winding speed is 300m / min.
  • Oxidized methyl morpholine and wood pulp cellulose (degree of polymerization 1050) were mixed uniformly and heated at 90 ° C for 8 hours to obtain a cellulose slime.
  • the dry-spray wet spinning method is used for spinning.
  • the cellulose slime was extruded from the spinneret hole, passed through an air gap of 10 cm, and stretched in the presence of cooling air to form a cellulose tow.
  • the ratio of the length of the spinneret hole to the diameter (L / D) is 10 to improve the orientation of the cellulose molecules.
  • the temperature of the cooling air is 25 ° C and the relative humidity is 80%.
  • the cellulose tow solidifies in the coagulation bath.
  • the temperature of the coagulation bath is 25 ° C, and the coagulation bath is an aqueous solution with an NMMO concentration of less than 10 wt%.
  • the coagulated cellulose tow is washed, dried and wound to make cellulose fibers.
  • the winding speed is 350m / min.

Abstract

一种纤维素纤维的纺丝方法，将纤维素粘液采用干喷湿式纺丝法纺制成纤维素纤维；所述纤维素粘液为纤维素的离子液体溶液，所述纤维素粘液和所述纤维素纤维均不含其他成纤高分子，所述干喷湿式纺丝法的卷绕速度为400～1500m/min。该方法可以将纤维素的离子液体溶液高速纺制成纤维。

Description

纤维素纤维的纺丝方法 技术领域
本发明涉及一种纤维素纤维的纺丝方法，尤其是一种采用离子液体为溶剂纺制纤维素纤维的工业化方法。
背景技术
聚丙烯(PP)、聚酯(PET)、聚乙烯(PE)、尼龙(Nylon)等来源于石化资源的合成纤维具有优良的性能，依然是最主要的纤维品种。然而，石化资源的产量日益减少，且面临耗竭。纤维素具有良好的生物兼容性及可降解性，并且来源广泛，但是其普及程度仍然不及上述合成纤维。目前，纤维素的开发利用逐渐收到人们的重视。
纤维素具有较高的结晶度、分子间及分子内存在着大量氢键，使得纤维素难以熔融纺丝，并且大部分溶剂也无法溶解。这导致纤维素的加工利用受到限制。因此，开发环境友好的纤维素高效溶剂对于纤维素纤维的普及应用是非常重要的。
传统的纤维素纤维的纺丝过程十分繁杂，纺丝速度甚慢，耗时甚久，且排放物质极易造成环境污染。近年来，开发出以氧化甲基吗啉(N-methylmorpholine N-oxide，简称NMMO)为代表的溶剂法纤维素纤维(Lyocell)纺丝工艺。NMMO溶解纤维素的温度高、时间长，容易导致纤维素粘液变深，聚合度降低。因此，离子液体作为新型溶剂，开始受到重视。离子液体为在室温或室温附近温度下呈液态且由离子构成的物质，通常是一种由体积较大的不对称有机阳离子和体积较小的无机/有机阴离子组成的、在室温下呈熔融态的盐。与传统溶剂相比，离子液体具有诸多优异特性。离子液体在低蒸汽压下不易挥发，解决了有机物质容易挥发导致的环境污染问题。离子液体具有低熔点、高极性的特性，可溶解许多有机物及无机物。另外，离子液体具有不可 燃性、耐强酸、高热稳定性、高导电度、电化学稳定性高等特点。此外，离子液体可根据不同需求进行设计，使其具有独特性质。离子液体在常压下使用，不但可以降低成本，也可以减少有机溶剂对环境的污染及人类的伤害。综上，离子液体被称为一种绿色环保溶剂。
通过咪唑类、吡啶类等阳离子与酰胺、六氟磷酸、四氟硼酸盐、乙酸酯及卤化物等阴离子可以得到溶解纤维素的离子液体。关于离子液体法纺制纤维素纤维的相关文献较多，但关于其真正产业化的报道却很少。CN101402658A公开了一种离子液体溶剂催化热降解纤维素的方法，采用烷基咪唑氯盐离子液体为溶剂，在纤维素的离子液体溶液中，用小于原料总重量1％的固体酸为催化剂，附以离子液体为共催化剂，在0.01～4.00MPa和100～300℃下进行均相催化热降解纤维素。由此可见，离子液体也容易导致纤维素降解。降解后的纤维素聚合度较小，无法满足高速纺丝的要求，导致产业化困难。
CN102619026A公开一种纳微纤维素纤维非织造布的制备方法，将纤维素粉末与离子液体制成均匀的混合物，将混合物喂入双螺杆挤出机，制备纺丝溶液，再经过计量泵后被送入到纺丝模头，从模头的喷丝孔中挤出，形成纺丝溶液细流；将高压热风经由纺丝模头的气腔狭缝形成高速气流吹向纺丝溶液细流，实现对溶液的拉伸细化；再经非织造布的成形与后处理后得到纳微纤维素纤维非织造布。上述纺丝工艺的纺丝速度慢，仅能获得无纺布，无法获得高强度纤维素纤维。
CN103352266A公开了一种纤维素与热塑性高聚物皮芯型复合纤维的制备方法，将纤维素和热塑性高聚物真空干燥；将真空干燥后的纤维素和离子液体按配比加入高速搅拌机混合均匀；将纤维素和离子液体的混合物加入同向双螺杆挤出机的一个投料口，将真空干燥后的热塑性高聚物加入到另一个投料口，通过同向双螺杆挤出机将两者挤出，进入纺丝组件中通过喷丝板进行纺丝，将所得的复合纤维经过水 槽洗去皮层中的离子液体，然后通过纺丝组件进行拉伸、卷绕，得到纤维素与热塑性高聚物皮芯型复合纤维。上述方法中的纤维卷绕速度可以达到500～1500m/min，但必须采用聚酯等成纤高分子作为芯层。实际上，可以高速纺丝的贡献主要来自聚酯等成纤高分子，而不是纤维素。
因此，目前仍然需要开发纤维素纤维的高速纺丝方法。
发明内容
有鉴于此，本发明的一个目的在于提供一种纤维素纤维的纺丝方法，其具有较高的卷绕速度。本发明进一步的目的在于提供一种纤维素纤维的纺丝方法，所得纤维素的性能至少与NMMO法的纤维素性能相当。
本发明提供一种纤维素纤维的纺丝方法，将纤维素粘液采用干喷湿式纺丝法纺制成纤维素纤维；其中，所述纤维素粘液为纤维素的离子液体溶液，所述纤维素粘液和所述纤维素纤维均不含其他成纤高分子，所述干喷湿式纺丝法的卷绕速度为400～1500m/min。
根据本发明的纺丝方法，优选地，还包括如下步骤：将纤维素与离子液体的混合物在50～100℃下加热3～10分钟，获得所述纤维素粘液；其中，所述纤维素粘液的粘度为1000～20000泊，纤维素含量为5～15wt％，透光指数为1.470～1.550，且所述纤维素粘液中的纤维素的聚合度衰退率小于15％。
根据本发明的纺丝方法，优选地，包括如下步骤：
(1)将聚合度为400～5000的纤维素与离子液体在40～60℃下混合均匀，然后采用薄膜蒸发器在50～100℃下加热3～10分钟，得到纤维素粘液；
(2)将所述纤维素粘液从喷丝孔挤出，经过0.5～30cm的空气间隔，在冷却风的存在下进行拉伸，形成纤维素丝束；其中，所述喷丝 孔的长度与口径之比L/D为3～15；冷却风的温度为5～45℃，相对湿度为60～99％；
(3)将所述纤维素丝束引入凝固浴中凝固，将凝固后的纤维素丝束经水洗、干燥和卷绕，制成纤维素纤维；其中，凝固浴的温度为5～45℃，凝固浴为离子液体的浓度低于30wt％的离子液体水溶液；卷绕速度为400～1500m/min。
根据本发明的纺丝方法，优选地，步骤(1)中，所述纤维素粘液不含其他成纤高分子，且所述纤维素粘液中的纤维素的聚合度衰退率小于15％。
根据本发明的纺丝方法，优选地，步骤(1)中，所述纤维素粘液的粘度为1000～20000泊，纤维素含量为5～15wt％，且透光指数为1.470～1.550。
根据本发明的纺丝方法，优选地，步骤(1)中，所述纤维素的α-纤维素含量为65％以上；且所述纤维素粘液的含水量为5～15wt％。
根据本发明的纺丝方法，优选地，步骤(1)中，所述的离子液体由阳离子和阴离子组成，所述阳离子选自咪唑基或吡啶基，所述阴离子选自氯离子、溴离子、碘离子、六氟磷酸根离子、硝酸根离子、醋酸根离子、铝酸根离子的至少一种。
根据本发明的纺丝方法，优选地，步骤(2)中，纺丝温度为60～100℃。
根据本发明的纺丝方法，优选地，在将所述纤维素丝束引入凝固浴之前，将所述纤维素丝束先通过一对再生槽形成的狭缝；其中，所述再生槽的一侧具有圆弧边，所述圆弧边相对设置形成所述狭缝，所述再生槽上设置有补水装置。
根据本发明的纺丝方法，优选地，在步骤(3)的水洗过程中，将凝固后的纤维素丝束通过两个由具有中空格栅的罗拉组成的水洗 轮，将水洗液由所述罗拉的中心向外喷洗至纤维素丝束。
本发明将纤维素粘液采用干喷湿式纺丝法纺制成纤维素纤维。在纤维素粘液和纤维素纤维均不含其他成纤高分子的情况下，本发明依然可以获得很高的卷绕速度，从而使得采用离子液体对纤维素进行工业化纺丝成为可能。根据本发明优选的技术方案，通过纤维素的快速溶解，可以有效避免纤维素降解，从而使得纤维素纤维具有良好性能。
附图说明
图1为纤维素粘液喷丝过程示意图。
图2为纤维素纤维纺丝过程示意图。
附图标记说明如下：
1-喷丝头，2-纤维素丝束，3-补水装置，4a-第一再生槽，4b-第二再生槽；22-凝固浴，23-水洗装置，24-干燥机，25-上油器，26-卷取装置，13a-第一水洗轮，13b-第二水洗轮。
具体实施方式
下面结合具体实施例对本发明作进一步的说明，但本发明的保护范围并不限于此。
本发明的纤维素纤维属于再生纤维，通常采用天然纤维素为原料，经过溶解、纺丝、卷绕等工序获得。离子液体可以作为纤维素的溶剂，但是溶解温度较高、溶解时间较长，从而导致纤维素降解，影响其可纺性。因此，在纤维素纺丝液(也称之为纤维素粘液)形成过程中，如何避免纤维素降解是非常必要的，这也是提高纤维素纤维纺丝速度的基础。本发明的纺丝方法包括溶解步骤和纺丝步骤等。
<溶解步骤>
本发明发现，采用薄膜蒸发器可以使得纤维素在离子液体中快速溶解减少纤维素的降解，所形成的纤维素粘液的粘度较低、聚合度衰 退率较低。在薄膜蒸发器中，液体物料沿加热管壁呈膜状流动，从而进行传热和蒸发。薄膜蒸发器通常适合于热敏性物质的蒸发，尚没有将其用于离子液体溶解纤维素的报道。此外，液体蒸发与物料溶解之间并无直接联系。按照成膜原因及流动方向不同，薄膜蒸发器可分为升膜蒸发器、降膜蒸发器、刮膜蒸发器，优选为降膜蒸发器。本发明的薄膜蒸发器的类型并没有特别限制。薄膜蒸发器机组通常由蒸发器、气液分离器、预热器和分离器组成。
本发明将聚合度为400～5000的纤维素与离子液体在40～60℃下混合均匀，然后采用薄膜蒸发器在50～100℃下加热3～10分钟，得到纤维素粘液。混合温度可以为40～60℃，优选为50～55℃。混合时间并没有特别限制，只要将二者混合均匀即可。将混合均匀得到的浆液置于薄膜蒸发器中进行溶解。溶解温度可以为50～100℃，优选为60～80℃，更优选为65～75℃。溶解时间为3～10分钟，优选为5～8分钟。在薄膜蒸发器中，纤维素充分分散，加快了纤维素在离子液体中的溶解速度。
纤维素的聚合度可以通过粘度法测定，详见下文。纤维素的聚合度可以为400～5000，优选为400～3500，更优选为500～2000。这样有利于纤维素的快速溶解和高速纺丝。
本发明的纤维素可以为长纤维木浆、短纤维木浆、棉浆或竹浆等；或者由它们的两者或两者以上按不同比例形成的混合物。优选地，本发明的纤维素为短纤维木浆或竹浆。纤维素中的α-纤维素含量为65％以上，优选为70％以上。这样有利于改善其成纤性。
本发明的离子液体可以选自咪唑型离子液体或吡啶型离子液体。咪唑型离子液体的阳离子为取代或未取代的咪唑阳离子，吡啶型离子液体的阳离子为取代或未取代的吡啶阳离子。咪唑型离子液体或吡啶型离子液体中的阴离子可以选自氯离子、溴离子、碘离子、六氟磷酸 根离子、硝酸根离子、醋酸根离子、四氟硼酸根离子、铝酸根离子的一种或多种；优选为醋酸根离子或四氟硼酸根离子。
在本发明中，咪唑型离子液体可以为含有两个取代基的咪唑鎓盐，其中至少一个取代基为烷基，例如二烷基取代的咪唑鎓盐。取代基可以含有1～30个碳原子；取代基可以在咪唑鎓结构的1-位和3-位。根据本发明的一个实施方式，其中一个取代基为C1-C6烷基、优选为C1-C4烷基；另一个取代基为C1-C6烃基，优选为C1-C4烃基。C1-C4烷基的实例但不限于甲基、乙基、丙基、异丙基、丁基、异丁基或叔丁基。C1-C4烃基的实例但不限于烯丙基、甲基、乙基、丙基、异丙基、丁基、异丁基或叔丁基。
本发明的吡啶型离子液体可以为含有一个取代基的吡啶鎓盐，该取代基可以为C1-C6烷基、优选为C1-C4烷基。C1-C4烷基的实例但不限于甲基、乙基、丙基、异丙基、丁基、异丁基或叔丁基。
本发明的离子液体的具体实例包括但不限于：1-乙基-3-甲基-氯化咪唑鎓盐(EMIC)、1-丁基-3-甲基-氯化咪唑鎓盐(EMIC)、1-丁基氯化吡啶鎓盐(BPC)、1-丁基吡啶六氟磷酸盐、1-丁基吡啶四氟硼酸盐、1-乙基-3-甲基-咪唑醋酸盐、1-乙基-3-甲基咪唑鎓四氯铝酸盐、1-乙基-3-甲基咪唑四氟硼酸盐、1-烯丙基-3-甲基-氯化咪唑鎓盐([AMIm]Cl)、1-烯丙基-3-甲基-咪唑醋酸盐或1-丁基-3-甲基咪唑醋酸盐。离子液体可以采用本领域常规的方法合成，这里不再赘述。优选地，本发明的离子液体选自1-乙基-3-甲基-咪唑醋酸盐、1-乙基-3-甲基咪唑鎓四氯铝酸盐、1-乙基-3-甲基咪唑四氟硼酸盐中的一种。这样可以进一步改善纤维素溶解效率。
在某些实施方案中，本发明的咪唑型离子液体具有式(I)所示的结构：
Figure PCTCN2019090123-appb-000001
式中，R1和R2分别独立地选自C1～C6烷基、含C1～C6烷基的腈基、含C1～C6烷基的酯基、苯基、乙烯基、含C1～C6烷基的 羟基、含C1～C6烷基的 羧基、含C1～C6烷基的 醚基和含C1～C6烷基的磺酸基的一种；B —选自氯离子、溴离子、碘离子、六氟磷酸根离子、硝酸根离子、醋酸根离子、铝酸根离子的一种。
在某些实施方案中，咪唑型离子液体具有式(II)所示的结构：
Figure PCTCN2019090123-appb-000002
式中，R选自C1～C6烷基、含C1～C6烷基的腈基、含C1～C6烷基的酯基、苯基、乙烯基、含C1～C6烷基的 羟基、含C1～C6烷基的 羧基、含C1～C6烷基的 醚基和含C1～C6烷基的磺酸基的一种；B —选自氯离子、溴离子、碘离子、六氟磷酸根离子、硝酸根离子、醋酸根离子、铝酸根离子的一种。
本发明的纤维素粘液的粘度可以为1000～20000泊，优选为5000～10000泊。上述粘度均在室温下测定。纤维素含量可以为5～15wt％，优选为6～10wt％。透光指数可以为1.470～1.550，优选为1.470～1.500。通过选择这些参数，可以使得纤维素粘液的可纺性非常好，更加有利于高速纺丝。由于离子液体中含有一定量的水，因此，本发明的纤维素粘液中也还有一定量的水。为了改善可纺性和高速纺丝特性，需要控制纤维素粘液的含水量。含水量可以为5～15wt％，优选为6～9wt％。这样可以改善纤维素粘液的可纺性，从而确保高速 纺丝的稳定性。
本发明的纤维素粘液不含其他成纤高分子，例如聚丙烯、聚酯、聚酰胺等。在溶解过程中，纤维素的聚合度衰退率小于15％。不受现有理论限制，采用上述方法可以减少纤维素的降解。所得纤维素的聚合度衰退率少于15％，优选小于12％，更优选小于10％。具体公式如下：
聚合度衰退率＝(溶解前纤维素聚合度-溶解后纤维素聚合度)/溶解前纤维素聚合度×100％。
<纺丝步骤>
在本发明的纺丝方法，将纤维素粘液采用干喷湿式纺丝法纺制成纤维素纤维。所述纤维素粘液为纤维素的离子液体溶液，所述纤维素粘液和所述纤维素纤维均不含其他成纤高分子。成纤高分子是能制成纤维的合成高分子，其具有形成纤维的能力，可以在合适的溶剂中完全溶解形成粘稠的浓溶液以便进行溶液纺丝，或者可以在升温下熔融转化为粘流态而不发生分解以便进行熔体纺丝。其他成纤高分子的实例包括但不限于聚丙烯、聚酯、聚酰胺等。本发明的纤维素纤维可以用于纺纱、织造等，并不是无纺布或具有皮芯结构的纤维。本发明的干喷湿式纺丝法的卷绕速度可以达到400～1500m/min，优选为600～150m/min，更优选为800～1500m/min，例如1000～1500m/min。这远大于通常的NMMO法的纺丝速度(例如，200m/min)。
将所述纤维素粘液从喷丝孔挤出，经过0.5～30cm的空气间隔，在冷却风的存在下进行拉伸，形成纤维素丝束。从薄膜蒸发器出来的纤维素粘液，经过计量泵等设备进入喷丝头，并从喷丝头的喷丝孔挤出成型。纺丝温度为60～100℃，优选为70～85℃。喷丝孔的长度与口径之比L/D为3～15；优选为5～13，更优选为8～12。这样有利于提高纤维素分子的取向性，为高速纺丝创造条件。在喷丝孔和凝固浴 之间具有一定的空气间隔，在挤出的细流经过空气间隔过程中，供给冷却风，冷却风的温度为5～45℃，优选为15～30℃；相对湿度为60～99％，优选为70～95％。这样有利于改善纤维素丝束的拉伸性能，避免凝固过程断裂，从而为高速纺丝创造条件。
在将所述纤维素丝束引入凝固浴中之前，将所述纤维素丝束先通过一对再生槽形成的狭缝。在凝固浴中应避免因丝束高速拉伸造成乱流。当纤维素丝束进入凝固浴时，由于丝束高速拉伸及凝固浴液体的阻力导致乱流，从而容易造成纤维素丝束纠结和断丝。如图1所示，第一再生槽4a和第二再生槽4b的一侧均具有圆弧边，两个圆弧边相对设置形成狭缝。纤维素丝束2从喷丝头1挤出，然后通过上述狭缝。这样的设计可以导引水流和增加丝束的集束性，从而避免乱流。此外，在两个再生槽上均设置有补水装置3。当纤维素丝束2进入凝固浴时，纤维素丝束2高速拉伸水流，此时由补水装置3快速补水，避免凝固浴缺水。
将所述纤维素丝束引入凝固浴中凝固，将凝固后的纤维素丝束经水洗、干燥和卷绕，制成纤维素纤维。如图2所示，经过凝固浴22凝固后的纤维素丝束经过水洗装置23，再经过干燥机24、上油器25和卷取装置26，从而得到纤维素纤维。水洗装置23包括第一水洗轮13a和第二水洗轮13b，它们均由具有中空格栅的罗拉组成。
在干喷湿式纺丝法高速纺丝过程中，水洗过程的水洗液将由于水洗轮高速运转而造成大量水雾飞溅，从而降低水洗效率与纺丝稳定性。为了克服上述问题，本发明将凝固后的纤维素丝束通过两个由具有中空格栅的罗拉组成的水洗轮，将水洗液由所述罗拉的中心向外喷洗至纤维素丝束。这样可以减少丝束在水洗轮表面的摩擦，并防止水洗液因水洗轮高速运转而造成水雾飞溅，从而大大提升水洗效率与纺丝稳定性。采用上述水洗轮，可以保证丝束在高速运转时不断丝，且 有利于大幅降低纤维素纤维中的离子液体的残留，提高离子液体的回收率。
在本发明中，水洗形成的水洗液以及凝固处理后的凝固浴中含有一部分离子液体，将这些液体经过过滤、浓缩得到离子液体溶剂，进而用于溶解纤维素，达到循环利用的目的。过滤可以采用二阶段过滤。第一阶段粗滤使用一般滤芯式过滤器；第二阶段精滤使用精密过滤器(UF)。精滤后的滤液清净度与新鲜溶剂相同。浓缩可以将回收的溶剂浓度由3.5～8.0wt％浓缩至85～95wt％。当纤维产量较少时，采用三效浓缩方式，其除水每吨约需蒸汽用量0.5吨；当纤维产量大时，则采用MVR浓缩方式，其除水每吨约需蒸汽0.003～0.03吨。产生的浓缩液和冷凝水都可全部回收。浓缩液供纤维素溶解过程使用，冷凝水供水洗过程使用。
在纺丝过程中，凝固浴的温度为5～45℃；优选为15～30℃。凝固浴为离子液体的浓度低于30wt％的离子液体水溶液；优选为离子液体的浓度低于8wt％的离子液体水溶液。这里的离子液体与上述溶解步骤的离子液体相同，这里不再赘述。本发明的干喷湿式纺丝法的卷绕速度可以达到400～1500m/min，优选为600～150m/min，更优选为800～1500m/min，例如1000～1500m/min。
采用上述方法获得的纤维素纤维的拉伸强度(干强度)为3.0～6.0g/d，断裂伸长率为5.0～12.0％，与NMMO法得到的纤维素纤维相当，可以满足服装用纤维素纤维的要求。
以下描述实施例和对比例中使用的测试方法：
纤维力学性能的测定：根据ASTM D2256的方法，采用英国Instron公司的4685型强伸仪测试纤维的断裂强度和断裂伸长率等力学性能。夹持距离为20mm，拉伸速度20为cm/min，纤维预调湿的环境条件为20±3℃，相对湿度为65％±5％，每个样品测试10次， 结果取平均值。
纤维热水收缩率的测定：参照GB/T6506-2001进行热水收缩率的实验。热水处理时间为30min，温度为50～130℃，每隔10℃设置一个测试点，每个测试点进行9次实验。热水收缩率S的公式如下：
S＝(Lo-Ls)/Lo×100％
式中:Lo为试样的热水处理前长度；Ls为试样的热水处理后长度。纤维素粘液的粘度测定：参照中华人民共和国纺织行业标准:粘胶纤维用浆粕粘度的测定FZ/T50010.3-1998中的《特性粘度测定——铜乙二胺溶液法(方法A)》来测定纤维素粘液的相对粘度(η 相对)。
η 相对＝η/η 0＝h·t 1
式中，h－校正时测定的测定用粘度计常数，单位为秒 -1；t 1－试样溶液流过测定粘度计的时间，单位为秒。
毛细管粘度计的校准：在(25±1)℃下，测定65％甘油水溶液、蒸馏水及稀释一倍的铜乙二胺溶液在校准用粘度计中的流出时间，然后再测定同一甘油水溶液在测定用粘度计中的流出时间，从而求出测定用粘度计常数h。本发明用的粘度计常数h＝0.863。
校准用毛细管粘度计：直径为(0.57±0.02)mm；测定用毛细管粘度计：直径为(0.80±0.05)mm；恒温水浴：控制温度在(25±1)℃，带有外引循环水泵；试样溶解瓶：容积为52mL带螺口盖的聚乙烯塑料瓶。
根据不同相对粘度η 相对(η/η 0)值与[η]·C值的对应关系表查出[η]·C值，进而求出[η]值。这里[η]为特性粘度，mL/g，C为纤维素粘液的浓度，g/mL。
纤维素聚合度的测定：通过测定纤维素的铜乙二胺溶液的粘度，进而计算出纤维素的聚合度。将纤维素溶解在铜乙二胺溶液中，在规定浓度下，于(25±1)℃下测定水和纤维素粘液通过毛细管粘度计的流出时间，计算出纤维素粘液的相对粘度(η 相对)，根据相对粘度(η 相对)与 [η]·C值的对应关系表查出[η]·C值，并根据待测溶液的已知浓度求出特性粘度[η]值，再根据纤维素聚合度与特性粘度的关系式(DP 0.905＝0.75[η])求得聚合度。
实施例1
将离子液体(1-乙基-3-甲基咪唑醋酸盐，水溶液的浓度为90wt％)与木浆纤维素(聚合度为600)在50℃下混合均匀，利用薄膜蒸发器在65℃下加热8分钟，得到纤维素粘液(参见表1)，聚合度衰退率小于10％。
表1、纤维素粘液
Figure PCTCN2019090123-appb-000003
采用干喷湿式纺丝法进行纺丝。该纤维素粘液从喷丝孔挤出，经过10cm的空气间隔，在冷却风的存在下进行拉伸，形成纤维素丝束。喷丝孔的长度与口径之比(L/D)为10，以提高纤维素分子的取向。冷却风的温度为25℃，相对湿度为80％。经过冷却拉伸的纤维素丝束进入凝固浴中凝固。凝固浴的温度为25℃，凝固浴为离子液体水溶液，离子液体的浓度低于8.0wt％。将凝固后的纤维素丝束经水洗、干燥及卷绕，制成纤维素纤维。卷绕速度为1000m/min。水洗过程中形成的水洗液和离子液体浓度过高的凝固液经过过滤、浓缩后循环使用。纤维素纤维的性能参见表2。
表2、纤维素纤维性能
Figure PCTCN2019090123-appb-000004
实施例2
将离子液体(1-乙基-3-甲基咪唑醋酸盐，水溶液的浓度为90wt％)与木浆纤维素(聚合度为1050)在50℃下混合均匀，利用薄膜蒸发器在75℃下加热5分钟，得到纤维素粘液(参见表3)，聚合度衰退率小于9％。
表3、纤维素粘液
Figure PCTCN2019090123-appb-000005
采用干喷湿式纺丝法进行纺丝。该纤维素粘液从喷丝孔挤出，经过10cm的空气间隔，在冷却风的存在下进行拉伸，形成纤维素丝束。喷丝孔的长度与口径之比(L/D)为10，以提纤维素分子的取向。冷却风的温度为25℃，相对湿度为80％。经过冷却拉伸的纤维素丝束进入 凝固浴中凝固。凝固浴的温度为25℃，凝固浴为离子液体水溶液，离子液体的浓度低于10wt％。将凝固后的纤维素丝束经水洗、干燥及卷绕，制成纤维素纤维。卷绕速度为1400m/min。水洗过程中形成的水洗液和离子液体浓度过高的凝固液经过过滤、浓缩后循环使用。纤维素纤维的性能参见表4。
表4、纤维素纤维性能
Figure PCTCN2019090123-appb-000006
对比例1
将氧化甲基吗啉与木浆纤维素(聚合度为600)混合均匀，在90℃下加热8小时，得到纤维素粘液。
采用干喷湿式纺丝法进行纺丝。该纤维素粘液从喷丝孔挤出，经过10cm的空气间隔，在冷却风的存在下进行拉伸，形成纤维素丝束。喷丝孔的长度与口径之比(L/D)为10，以提纤维素分子的取向。冷却风的温度为25℃，相对湿度为80％。经过冷却拉伸的纤维素丝束进入凝固浴中凝固。凝固浴的温度为25℃，凝固浴为NMMO浓度低于8.0wt％的水溶液。将凝固后的纤维素丝束经水洗、干燥及卷绕，制成纤维素纤维。卷绕速度为300m/min。
对比例2
将氧化甲基吗啉与木浆纤维素(聚合度为1050)混合均匀，在 90℃下加热8小时，得到纤维素粘液。
采用干喷湿式纺丝法进行纺丝。该纤维素粘液从喷丝孔挤出，经过10cm的空气间隔，在冷却风的存在下进行拉伸，形成纤维素丝束。喷丝孔的长度与口径之比(L/D)为10，以提纤维素分子的取向。冷却风的温度为25℃，相对湿度为80％。经过冷却拉伸的纤维素丝束进入凝固浴中凝固。凝固浴的温度为25℃，凝固浴为NMMO浓度低于10wt％的水溶液。将凝固后的纤维素丝束经水洗、干燥及卷绕，制成纤维素纤维。卷绕速度为350m/min。
表5、本发明方法与传统方法的比较
方法种类 本发明方法 传统方法
纤维素聚合度 400～1500 550～1200
溶剂 离子液体 氧化甲基吗啉
纤维纤度(Denier) 120 120
卷绕速度(m/min) 400～1500 200～350
干强度(g/d) 4.4～5.6 4.2～5.2
湿强度(g/d) 3.8～5.0 3.4～4.5
干伸率(％) 6％～12％ 5％～8％
湿伸率(％) 7％～15％ 6％～10％
热水收缩率(％) 2％ 2％
本发明方法与传统方法的比较参见表5。由表可知，本发明的卷绕速度显著提高，从而有利于工业化生产。本发明的方法所得纤维素纤维的性能与NMMO法所得纤维素纤维的性能相当。
实施例3
将1-乙基-3-甲基咪唑醋酸盐替换为1-乙基-3-甲基咪唑鎓四氯铝酸盐，其余条件与实施例1相同，得到纤维素纤维。
实施例4
将1-乙基-3-甲基咪唑醋酸盐替换为1-乙基-3-甲基咪唑鎓四氯铝酸盐，且水溶液浓度改变为85wt％，其余条件与实施例1相同，得到纤维素纤维。
实施例5
将1-乙基-3-甲基咪唑醋酸盐替换为1-乙基-3-甲基咪唑鎓四氯铝酸盐，其余条件与实施例2相同，得到纤维素纤维。
实施例6
将1-乙基-3-甲基咪唑醋酸盐替换为1-乙基-3-甲基咪唑鎓四氯铝酸盐，且水溶液浓度改变为85wt％，其余条件与实施例2相同，得到纤维素纤维。
本发明并不限于上述实施方式，在不背离本发明的实质内容的情况下，本领域技术人员可以想到的任何变形、改进、替换均落入本发明的范围。

Claims (10)

  1. 一种纤维素纤维的纺丝方法，其特征在于，将纤维素粘液采用干喷湿式纺丝法纺制成纤维素纤维；其中，所述纤维素粘液为纤维素的离子液体溶液，所述纤维素粘液和所述纤维素纤维均不含其他成纤高分子，所述干喷湿式纺丝法的卷绕速度为400～1500m/min。
  2. 根据权利要求1所述的纺丝方法，其特征在于，还包括如下步骤：将纤维素与离子液体的混合物在50～100℃下加热3～10分钟，获得所述纤维素粘液；其中，所述纤维素粘液的粘度为1000～20000泊，纤维素含量为5～15wt％，透光指数为1.470～1.550，且所述纤维素粘液中的纤维素的聚合度衰退率小于15％。
  3. 一种纤维素纤维的纺丝方法，其特征在于，包括如下步骤：
    (1)将聚合度为400～5000的纤维素与离子液体在40～60℃下混合均匀，然后采用薄膜蒸发器在50～100℃下加热3～10分钟，得到纤维素粘液；
    (2)将所述纤维素粘液从喷丝孔挤出，经过0.5～30cm的空气间隔，在冷却风的存在下进行拉伸，形成纤维素丝束；其中，所述喷丝孔的长度与口径之比L/D为3～15；冷却风的温度为5～45℃，相对湿度为60～99％；
    (3)将所述纤维素丝束引入凝固浴中凝固，将凝固后的纤维素丝束经水洗、干燥和卷绕，制成纤维素纤维；其中，凝固浴的温度为5～45℃，凝固浴为离子液体的浓度低于30wt％的离子液体水溶液；卷绕速度为400～1500m/min。
  4. 根据权利要求3所述的纺丝方法，其特征在于，步骤(1)中，所述纤维素粘液不含其他成纤高分子，且所述纤维素粘液中的纤维素的聚合度衰退率小于15％。
  5. 根据权利要求4所述的纺丝方法，其特征在于，步骤(1)中， 所述纤维素粘液的粘度为1000～20000泊，纤维素含量为5～15wt％，且透光指数为1.470～1.550。
  6. 根据权利要求5所述的纺丝方法，其特征在于，步骤(1)中，所述纤维素的α-纤维素含量为65％以上；且所述纤维素粘液的含水量为5～15wt％。
  7. 根据权利要求3所述的纺丝方法，其特征在于，步骤(1)中，所述的离子液体由阳离子和阴离子组成，所述阳离子选自咪唑基或吡啶基，所述阴离子选自氯离子、溴离子、碘离子、六氟磷酸根离子、硝酸根离子、醋酸根离子、铝酸根离子的至少一种。
  8. 根据权利要求7所述的纺丝方法，其特征在于，步骤(2)中，纺丝温度为60～100℃。
  9. 根据权利要求3所述的纺丝方法，其特征在于，在将所述纤维素丝束引入凝固浴之前，将所述纤维素丝束先通过一对再生槽形成的狭缝；其中，所述再生槽的一侧具有圆弧边，所述圆弧边相对设置形成所述狭缝，所述再生槽上设置有补水装置。
  10. 根据权利要求9所述的纺丝方法，其特征在于，在步骤(3)的水洗过程中，将凝固后的纤维素丝束通过两个由具有中空格栅的罗拉组成的水洗轮，将水洗液由所述罗拉的中心向外喷洗至纤维素丝束。
PCT/CN2019/090123 2018-11-22 2019-06-05 纤维素纤维的纺丝方法 WO2020103424A1 (zh)

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