EP3704289B1 - Herstellung von kohlenstofffasern aus lignin / pva-precursor-fasern - Google Patents

Herstellung von kohlenstofffasern aus lignin / pva-precursor-fasern Download PDF

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EP3704289B1
EP3704289B1 EP18795551.3A EP18795551A EP3704289B1 EP 3704289 B1 EP3704289 B1 EP 3704289B1 EP 18795551 A EP18795551 A EP 18795551A EP 3704289 B1 EP3704289 B1 EP 3704289B1
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Prior art keywords
lignin
fibres
pva
fibers
precursor
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French (fr)
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EP3704289A2 (de
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Marie FÖLLMER
Celia Mercader
Wilfrid NERI
Simon JESTIN
Alain Derre
Philippe Poulin
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Centre National de la Recherche Scientifique CNRS
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Centre National de la Recherche Scientifique CNRS
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    • 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
    • D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
    • D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
    • D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
    • D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
    • D01F9/16—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from products of vegetable origin or derivatives thereof, e.g. from cellulose acetate
    • D01F9/17—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from products of vegetable origin or derivatives thereof, e.g. from cellulose acetate from lignin
    • 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
    • D01D5/06—Wet 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
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/44—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds
    • D01F6/50—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds of polyalcohols, polyacetals or polyketals

Definitions

  • the present invention relates to precursor fibers for carbon fibers, a method for manufacturing such precursor fibers and a method for manufacturing carbon fibers.
  • carbon fibers as reinforcements in composite materials is limited to high-performance applications in the aerospace, transportation and energy sectors. Commercial applications are still hampered by the high costs of fibrous raw materials and their processing. Additionally, current carbon fibers are generally made from materials derived from the petrochemical industry. Their treatment is therefore expensive and associated with the net generation of CO 2 .
  • Conventional carbon fibers are made from polyacrylonitrile (PAN) as the most commonly used precursor material, while high modulus carbon fibers are made from meso-phase pitch.
  • PAN polyacrylonitrile
  • the fibers are subjected to heat treatment under an inert atmosphere at a temperature of 1000-1500 °C. Subsequently, the fiber consists of at least 92% by weight of carbon.
  • the fiber is heated to more than 3000°C, a so-called graphitization stage, which makes it possible to improve the ordering of the carbon planes in the direction of the fiber.
  • High temperature infusibility is the most important requirement for a precursor material to be able to withstand the carbonization process.
  • the precursor fibers thus undergo a thermostabilization treatment at low heating speed in air up to 200-300°C to make them infusible.
  • Precursor materials represent attractive prospects for the carbon fiber.
  • Cellulose and lignin two very abundant biomaterials, have been the subject of in-depth studies for several years.
  • the present invention focuses on lignin as an alternative precursor material for carbon fibers.
  • Lignin is the most abundant aromatic bio-polymer on earth and is therefore a widely available and renewable material. More than 50 million tonnes of lignin are extracted each year, mainly as a by-product of biofuel and paper production. Large quantities of the resulting lignin are used as an internal energy source, but there is growing interest in using it for higher value applications.
  • Lignin is an amorphous polyol formed from branched units of methoxylated phenylpropane with a three-dimensional structure, the shape and constitution of which are determined depending on the type of plant from which this polymer comes and the extraction process used to separate the lignin from the cellulose. Consequently, depending on its origin, the molecular structure of lignin presents variations, which leads to the chemical and physical properties varying between the different grades of lignin.
  • lignin The main sources of lignin are found in the pulp and paper industry (e.g. kraft lignin, lignosulfonate and soda lignin) and in biorefineries (e.g. organosolv lignin).
  • the most frequently used extraction technique is the kraft pulping process or sulfate process, in which lignin is separated from cellulose by dissolving the wood in aqueous sodium hydroxide (NaOH) and sodium sulfide (Na 2 S) at high temperatures (“kraft lignin” or "alkaline lignin”).
  • lignin soda comes from the manufacturing process where the wood is cooked in an aqueous solution of sodium hydroxide (NaOH) that dissolves the lignin.
  • NaOH sodium hydroxide
  • This type of lignin is free of sulfur and, unlike other grades of lignin, it is mainly obtained from non-woody plants.
  • Organosolv process organic solvents are used to solubilize lignin in wood.
  • Organic solvents are used to solubilize lignin in wood.
  • “Organosolv lignin” contains only very small amounts of inorganic compounds, making it a high purity lignin.
  • Lignin with a carbon content of 60-65%, generally represents a cheap and environmentally friendly carbon fiber precursor.
  • current processes have not yet successfully reached industrial markets due to various limitations summarized in the following paragraphs.
  • CN 104 947 244 And Mariko Ago et al. (Lignin-Based Electrospun Nanofibers Reinforced with Cellulose Nanocrystals; Biomacromolecules, 2012, 13 (3), pp 918-926; DOI: 10.1021/bm201828g ) relate to electrospinning methods.
  • CN 104 947 244 explicitly relates to a method for extracting and preparing composite nanofibers (abstract).
  • Mariko Ago et al. (2012) concerns nanofibers (figure 3).
  • These processes do not make it possible to directly obtain fibers of more than 1 micron in diameter. They necessarily lead to nanofibers.
  • the transposition of such processes according to the prior art on a large scale is always a technological problem. In particular, they do not allow the production of multifilament yarns, such as those used in traditional composite and textile technologies.
  • the present invention aims to solve the technical problem of providing a new carbon fiber precursor, and in particular a precursor having a high lignin content in the fibers.
  • the present invention also aims to solve the technical problem of providing a new process for preparing carbon fiber precursors.
  • the present invention also aims to solve the problem of providing a new process for manufacturing carbon fibers, and in particular with a high rate of carbonization yield.
  • the present invention also aims to solve the technical problem of providing a new process.
  • the process of the invention is a wet spinning process.
  • the fibers obtained have diameters which can vary from 1 to 1000 microns, and generally from 1 to 100 microns.
  • the process of the invention makes it possible to produce multifilaments and is particularly industrializable.
  • the present invention aims to provide such processes in a reliable and environmentally friendly manner.
  • the present invention aims to provide such methods inexpensively. Furthermore, the present invention aims to solve the technical problem of providing a new carbon fiber precursor that is environmentally friendly and has low production costs.
  • the invention relates in particular to the production of lignin-PVA fibers.
  • PVA makes it possible to obtain good mechanical properties of the precursor lignin fiber.
  • a very important factor is the yield obtained after carbonization.
  • Lignin-PVA fibers must therefore contain a lignin content greater than 50%.
  • the invention relates to a process for manufacturing carbon fiber precursor fibers comprising a lignin and a polyvinyl alcohol (PVA) and containing at least 60% by mass of lignin relative to the total lignin-PVA mass, said process comprising: producing a solution of lignin and PVA in a solvent, injecting the solution containing lignin and PVA into a coagulation bath to obtain one or more fibers, containing at least 60% by mass of lignin, coagulated by wet spinning.
  • PVA polyvinyl alcohol
  • the invention therefore relates to a process for continuous wet spinning of lignin-PVA fibers containing 60% and more lignin, using non-hazardous solvents and mild processing conditions.
  • the solvent of the lignin solution and the solvent of the PVA solution are an identical solvent.
  • the solvent of the lignin solution and/or the solvent of the PVA solution are chosen from water, an aqueous solution comprising one or more salts, an ionic liquid, an organic solvent (for example N ,N-dimethylformamide, N,N'-dimethylethyleneurea, ethylene glycol, dimethylsulfoxide or tetrahydrofuran), and any of their mixtures, and preferably comprise or consist of dimethylsulfoxide (DMSO.
  • DMSO dimethylsulfoxide
  • a precursor fiber spinning solution containing lignin and PVA in a given solvent is thus prepared.
  • the mixture is homogeneous.
  • the concentration of lignin in the organic solvent is between 10 and 50%, and for example between 20 and 40%, and again for example between 30 and 40%, by mass relative to the total mass of the solution with lignin.
  • the concentration of lignin in solution must be increased up to its solubility threshold, generally between 20 and 40% by mass of the total mass of the solution.
  • solubility threshold generally between 20 and 40% by mass of the total mass of the solution.
  • a PVA solution is prepared by dispersing a PVA powder in the same solvent or in another solvent.
  • the molar mass of PVA is in the range of 10,000 to 500,000 g/mol, for example to serve as a reinforcing element having a high mixing affinity with lignin.
  • the concentration of PVA in the organic solvent is between 1 and 30%, and for example between 5 and 20%, and again for example between 5 and 15%, by mass relative to the mass of the solution.
  • PVA solution prepared by dissolving at concentrations of 1 to 30 wt% can be mixed with lignin solution in any possible ratio.
  • the masses of lignin and PVA solutions are mixed in equal or substantially equal proportions.
  • the lignin can be dissolved directly in the PVA solution previously made.
  • PVA can be dissolved directly in a lignin solution.
  • the concentration of lignin in the lignin-PVA solution includes a higher mass of lignin than PVA.
  • the mass of lignin and the mass of PVA are determined according to the desired ratio in the final precursor fibers.
  • the relative lignin/PVA ratio is controlled.
  • the lignin/PVA solution may also contain fillers such as graphene, graphene oxide, carbon nanotubes, cellulose whiskers or microfibrillated cellulose.
  • the solution can be prepared in two steps, by preparing a lignin solution and a PVA solution separately and then mixing them.
  • melt spinning is the most studied technique for the production of lignin-based precursor fibers. Regarding the final application of melt-spun lignin carbon fibers, however, no significant progress could be made so far. Since the late 1980s, the lignin spinning process has been the subject of extensive study. Despite these developments, the use of melt spinning remains tricky because the fibers obtained by melt spinning are fragile unless a large amount of plasticizer is introduced. Using large quantities of expensive plasticizers, however, makes the carbonization step more difficult and less efficient. Furthermore, the main limitation of melt spinning is the use of meltable lignin grades, which by definition implies the need for a long, difficult and expensive stabilization step before carbonization.
  • the solution proposed by the present invention is particularly awaited by the industry to provide carbon fiber precursors at low cost, and on the other hand more respectful of the environment, in particular through their manufacturing process.
  • the lignin is a kraft lignin, a soda lignin, an organosolv lignin, or a lignosulfonate.
  • the present invention comprises the use of unmodified Kraft softwood lignin.
  • lignin can thus be combined with polyvinyl alcohol (PVA), for example as a reinforcing polymer to facilitate the spinning process.
  • PVA polyvinyl alcohol
  • the lignin solution comprises a dispersion of charges, and for example, comprises nanoparticles such as for example graphene, graphene oxide (GO), carbon nanotubes (CNT), cellulose fibers (“cellulosic whiskers”), cellulose micro-fibrils, and any of their mixtures can be added to lignin to obtain the precursor fibers of the invention.
  • nanoparticles can typically be added to the lignin solution to obtain better structuring of the fibers.
  • the concentration of these fillers in the precursor fiber is for example between 0.05% and 10% relative to the mass of the fiber and advantageously between 0.05% and 1%.
  • the described fibers are suitable as a precursor for subsequent carbonization into carbon fibers (without stabilization treatment necessary). These fillers can induce an orientation in the direction of the fibers and therefore increase the structure and crystallinity of the composite fibers. Additionally, these fillers can also increase fiber carbonization yields.
  • the present invention relates in particular to a process for wet spinning lignin.
  • lignin can be wet spun into fibers in combination with small amounts of PVA as a low cost plasticizing polymer. Wet spinning is carried out according to conditions known to those skilled in the art.
  • the lignin fibers are formed by wet spinning or dry jet spinning.
  • the solution containing lignin, PVA and optional additives is for example injected through a die into a counter-solvent in which the solid materials coagulate to form a fiber in the gel state.
  • the solution is injected into an air gap of several millimeters to several centimeters before being immersed in the countersolvent.
  • the die can be made up of a single hole up to several thousand holes.
  • the diameters of the fibers obtained are between 1 and 1000 ⁇ m and preferably between 10 and 100 ⁇ m.
  • the diameters of the fibers are typically measured by optical and electronic microscopies, according to the knowledge of those skilled in the art. In general, reflection mode optical microscopy and scanning electron microscopy are used. It is preferred to use optical microscopy for fibers with a diameter greater than 1 micron and scanning electron microscopy for fibers less than 10 microns in size.
  • the coagulation bath comprises a counter-solvent for the coagulation of lignin, said counter-solvent being preferably chosen from water, an aqueous saline solution and organic solvents comprising one or more hydroxyl groups, polyols or ketones used alone or in mixtures.
  • the solvent and the counter-solvent must be miscible.
  • an alcohol is used as a counter-solvent for the coagulation bath.
  • isopropanol, ethanol or butanol or one of their mixtures is used as a counter-solvent as a coagulation bath.
  • suitable countersolvents leading to lignin coagulation include, but are not limited to: water, aqueous saline solutions and organic solvents characterized by one or more hydroxyl groups, the solvent and the countersolvent being advantageously miscible.
  • the process according to the present invention allows the use of non-toxic solvents and materials, making it possible to improve the ecological footprint of the process of the invention on the environment.
  • the fiber in the gel state can pass through one or more washing baths, possibly to remove residual solvent from the solution or salt residue.
  • Wash baths may contain water, alcohol, organic solvents or mixtures thereof.
  • the fibers can also be stretched during these operations.
  • the washing baths when the solvent is not completely eliminated in the coagulation bath, generally contain the same counter-solvent as that used for coagulation or another counter-solvent such as for example water, an aqueous saline solution, an organic solvent comprising one or more hydroxyl groups or a solvent identical to that of the spinning solution and any combination thereof.
  • the process includes drying the coagulated fibers, preferably after rinsing the coagulated fibers.
  • an alcohol is used as a solvent for rinsing the coagulated fiber.
  • isopropanol, ethanol, butanol or one of their mixtures is used as a rinsing solvent.
  • drying of the fibers should take place at temperatures ranging from room temperature up to 250°C before hot drawing and winding.
  • the coagulated fibers are kept under mechanical tension during drying.
  • the fiber is kept under tension in the spinning line. The applied tension and stretching process generally improve the structure and mechanical properties of lignin fibers.
  • the dried fibers are pre-impregnated by passing through a bath containing an impregnating agent, before carbonization.
  • This procedure consists, for example, of passing the precursor fiber through a bath containing, for example, urea, a polysiloxane solution, a silane solution or similar substances.
  • the final quantity of additives on the surface of the fibers generally varies from 0.1 to 10% by mass relative to the mass of the impregnated fiber. Indeed, to increase the carbonization yield and/or the mechanical properties of the carbon fiber, it is possible to pre-impregnate the precursor fiber before carbonization.
  • This procedure consists, for example, of passing the precursor fiber through a bath containing, for example, urea, a polysiloxane solution, a silane solution or similar substances.
  • the final quantity of additives on the surface of the fibers generally varies from 0.1 to 10% by mass relative to the mass of the impregnated fiber.
  • the present invention thus relates to a material comprising or consisting of one or more precursor fibers of carbon fibers, the precursor fiber(s) comprising a proportion of lignin greater than or equal to 60% by mass and a polyvinyl alcohol (PVA).
  • PVA polyvinyl alcohol
  • the present invention also relates to a material comprising or consisting of one or more precursor fibers of carbon fibers, the precursor fiber(s) comprising a proportion of lignin greater than or equal to 60% by mass and an alcohol polyvinyl (PVA) and capable of being obtained by a process as defined according to the present invention.
  • a material comprising or consisting of one or more precursor fibers of carbon fibers, the precursor fiber(s) comprising a proportion of lignin greater than or equal to 60% by mass and an alcohol polyvinyl (PVA) and capable of being obtained by a process as defined according to the present invention.
  • PVA alcohol polyvinyl
  • a precursor fiber comprises a proportion of lignin greater than or equal to 65%, preferably greater than or equal to 70%, and even more preferably greater than or equal to 75%, by mass relative to the mass of the fiber.
  • the precursor fibers according to the present mention comprise a high lignin content.
  • the quantity of lignin can be detected by thermogravimetric analysis.
  • the precursor fiber comprises a proportion of lignin less than or equal to 90%, and for example less than or equal to 85%, by mass relative to the mass of the fiber.
  • the precursor fibers according to the present invention have a high rate of carbonization.
  • the carbonization rate is greater than 30%.
  • lignin fibers do not contain PAN.
  • the precursor fiber comprises a proportion of PVA less than or equal to 40%, preferably less than or equal to 35%, and even more preferably less than or equal to 30%, by mass relative to the mass of the fiber.
  • the precursor fiber comprises a proportion of PVA less than or equal to 25% by mass relative to the mass of the fiber.
  • the precursor fibers consist of lignin, PVA and optionally carbon precursor fillers by carbonization.
  • a precursor fiber also comprises carbon fillers.
  • the carbon fillers are chosen from graphene, graphene oxide, carbon nanotubes, cellulose whiskers or microfibrillated cellulose. These fillers can induce an orientation in the direction of the fibers and therefore improve the structure and crystallinity of the composite fibers.
  • the lignin fiber Before carbonization, the lignin fiber may undergo a stabilization or oxidation treatment, whereby it is heated from 20 to 200 °C under an oxidizing atmosphere (air) at low heating rates.
  • the process usually causes the lignin to cross-link to make it infusible.
  • the treatment can last from 1 minute to 24 hours.
  • fibers can also be treated with physical oxidation methods such as: plasma treatment, microwave treatment, gamma or beta rays, electron beam treatment or ozone.
  • the process of the invention does not include any stabilization or oxidation treatment, in particular before carbonization.
  • the precursor fibers according to the present invention do not liquefy at high temperatures, and in particular at the carbonization temperature.
  • the precursor fibers according to the present invention are therefore infusible.
  • the invention also relates to a process for manufacturing carbon fibers, said process comprising the manufacture of precursor fibers according to a process as defined in the invention, the drying if necessary of the coagulated fibers, preferably after rinsing the coagulated fibers, and the carbonization of dried fibers to obtain a carbon fiber.
  • Carbon fiber can be obtained by carbonization with or without prior thermostabilization.
  • lignin-based precursor fibers obtained by wet spinning can be carbonized in a static or continuous carbonization furnace at temperatures between 800 and 2000 °C under an inert atmosphere (e.g. nitrogen, argon). It is recommended to heat the fibers under tension to avoid strong shrinkage in length.
  • inert atmosphere e.g. nitrogen, argon
  • fiber diameters are generally reduced to 1-70 ⁇ m.
  • the structure and therefore mechanical properties of the resulting carbon fiber can be significantly improved.
  • the fibers are kept under mechanical tension during carbonization.
  • the invention also relates to a material, comprising or consisting of one or more precursor fibers of carbon fibers, in which the precursor fiber(s) comprise a proportion of lignin greater than or equal to 60% by mass and a polyvinyl alcohol (PVA).
  • PVA polyvinyl alcohol
  • the invention also relates to a material, comprising or consisting of one or more precursor fibers of carbon fibers, in which the precursor fiber(s) comprise a proportion of lignin greater than or equal to 60% by mass and an alcohol polyvinyl (PVA) and capable of being obtained by a process as defined according to the invention.
  • precursor fiber(s) comprise a proportion of lignin greater than or equal to 60% by mass and an alcohol polyvinyl (PVA) and capable of being obtained by a process as defined according to the invention.
  • PVA alcohol polyvinyl
  • the precursor fiber(s) further comprise carbonaceous fillers.
  • the carbon fillers are chosen from graphene, graphene oxide, carbon nanotubes, cellulose whiskers or microfibrillated cellulose. These fillers can induce an orientation in the direction of the fibers and therefore improve the structure and crystallinity of the composite fibers.
  • Lignin-based precursor fibers can be carbonized into individual fibers or multifilaments, or woven into fabrics which are then carbonized. Graphitization of carbon fibers obtained at temperatures above 2000 °C is also possible.
  • the present invention relates to multifilament yarns.
  • the process of the invention makes it possible to produce multifilaments and is particularly industrializable.
  • the method of the invention for spinning yarns uses a multi-hole injection head to obtain multifilament yarns.
  • the fibers obtained can be carbonized directly at temperatures between 800 and 2000 °C under an inert atmosphere, without any oxidative stabilization step necessary (when using infusible Kraft lignin), but with high carbon yields.
  • Carbonization can for example be carried out in a static oven with a suitable tension system or in one or more continuously powered ovens.
  • Graphitization up to 3000°C can be carried out in the same way to improve the structure of the carbon fiber.
  • This invention relates to a process for obtaining carbon fibers or activated carbon fibers from a precursor fiber based on lignin and polyvinyl alcohol (PVA).
  • the precursor fiber includes a high lignin content and is obtained by wet spinning.
  • the invention therefore represents an economical process based on a renewable raw material for the preparation of carbon fibers.
  • the carbon fibers obtained from spun molten lignin still do not have the mechanical and/or electrical and/or thermal properties required for their implementation in larger-scale industrial applications.
  • the present invention also relates to carbon fibers capable of being obtained by a manufacturing process according to the present invention.
  • the present invention also relates to a composite material comprising carbon fibers capable of being obtained by a manufacturing process according to the present invention.
  • the applications targeted for carbon fibers from lignin according to the invention are multiple.
  • the fibers can be used as is or transformed into fabrics, in combination with other fibers.
  • the fibers are suitable for example for the preparation of laminates, for infusion or other techniques used for the manufacture of composite materials.
  • the fibers can be combined with thermoplastic or thermosetting resins or elastomers.
  • the following industrial fields could constitute markets for these composite materials: construction and infrastructure, industrial equipment, transport (vehicles, railways, boats, etc.), electricity and electronics, sports and leisure as well as renewable energies (for example wind turbines).
  • the carbon fibers according to the invention are particularly suitable for mass applications, such as in the transport, sports and leisure and wind power industries for example.
  • the terms “the fiber” or “the fibers” are used indiscriminately regardless of the embodiment, the variant, or the advantageous or preferred characteristic. Thus, all the embodiments, or advantageous or preferred characteristics concern one or more fibers.
  • a solution of kraft lignin in 35 mass % dimethyl sulfoxide (DMSO) is mixed with an equal part solution of polyvinyl alcohol (PVA) in 10 mass % DMSO.
  • PVA polyvinyl alcohol
  • a homogeneous mixture solution containing 17.5% by mass of Kraft lignin and 5% by mass of PVA is obtained by mixing for at least 30 minutes at room temperature.
  • the solution is then injected into a coagulation bath containing isopropanol.
  • a coagulated monofilament fiber is passed through a wash bath containing ethanol to remove DMSO residue and facilitate the drying process.
  • the fiber is then dried in an infrared oven at 80-90°C and then wound. After removal of DMSO, the dried fiber contains 78% Kraft lignin and 22% PVA.
  • the continuously spun lignin and PVA fiber is then transformed into carbon fiber by heating it up to 1200°C under nitrogen in a static oven.
  • the heating power used varies from 5 to 8°C/min.
  • the fiber is kept under constant tension.
  • the resulting carbonized lignin-PVA fiber is electrically conductive (1.9 ⁇ 10 3 S/m). This confirms the production of a carbon fiber containing a more or less graphitized material.
  • a Kraft lignin solution (at 35% by mass in DMSO) is mixed with 60 g of a PVA solution (at 10% by mass in DMSO). The mixture is stirred for 15 minutes at room temperature.
  • the lignin-PVA solution is injected into a coagulation bath containing isopropanol through a multifilament spinneret (diameter 90 ⁇ m).
  • the multifilament fiber is washed in isopropanol and dried at 90 °C in an infrared oven before 'to be rolled up.
  • the final fiber contains 70% Kraft lignin and 30% PVA.
  • the carbonization of the multifilament fiber can be carried out as described in Example 1.
  • a homogeneous dispersion of cellulose nanocrystals is prepared in DMSO by sonication.
  • Kraft lignin powder is added to the dispersion and the mixture is prepared by stirring until the lignin dissolves.
  • the final concentrations in the dispersion are 2 wt% NCC and 26.6 wt% lignin.
  • a solution of PVA in DMSO at 11.4% by mass is prepared.
  • the NCC-lignin dispersion and the PVA solution are mixed in equal parts.
  • the spinning solution containing 13.3 wt% lignin, 5.7 wt% PVA and 1 wt% NCC is injected into a coagulation bath containing isopropanol.
  • the fiber is washed in isopropanol, stretched and dried at 90°C in an infrared oven before being wound.
  • the final fiber contains 66.5% Kraft lignin, 28.5% PVA and 5% NCC.
  • the carbonization of the fiber can be carried out as described in Example 1.
  • a dispersion of graphene oxide (GO) at 2% by mass in DMSO is mixed with a solution of Kraft lignin (at 35% by mass in DMSO) and a solution of PVA (at 10% by mass in DMSO).
  • the mixing solution is injected into a coagulation bath containing ethanol through a syringe with a diameter of 50 ⁇ m.
  • the fibers obtained are stretched by a factor of 2 then dried at room temperature.
  • the resulting fibers, containing 70% Kraft lignin, 25% PVA and 5% GO, can be carbonized as described in Example 1.
  • Example 2 80 g of DMSO is heated to 90 °C and 6 g of PVA is added, thus a PVA solution is prepared. Then, 14 g of Kraft lignin are added and the mixture is kept stirring for at least 6 hours hot. The spinning solution is coagulated into fibers as described in Example 2. The 70% Kraft lignin and 30% PVA precursor fibers can be carbonized as described in Example 1.
  • This comparative example shows the importance of a lignin level in accordance with the invention.
  • Two lignin-PVA precursor fibers were spun according to the process of the invention under similar conditions, that is to say by solubilization in DMSO then coagulation in isopropanol.
  • the fibers thus manufactured differ only in their lignin/PVA mass ratio.
  • One fiber has a 70/30 ratio and another 50/50.

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  • Engineering & Computer Science (AREA)
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  • Mechanical Engineering (AREA)
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  • Artificial Filaments (AREA)

Claims (13)

  1. Verfahren zur Herstellung von Kohlenstofffaser-Vorläuferfasern, die ein Lignin und einen Polyvinylalkohol (PVA) umfassen und mindestens 60 Massen-% Lignin, bezogen auf die gesamte Lignin-PVA-Masse, enthalten, wobei das Verfahren das Herstellen einer Lösung von Lignin und PVA in einem Lösungsmittel und das Einspritzen der das Lignin und das PVA enthaltenden Lösung in ein Koagulationsbad umfasst, um eine oder mehrere Fasern zu erhalten, die mindestens 60 Massen-% Lignin enthalten und durch Nassspinnen koaguliert werden, wobei der Durchmesser der erhaltenen Vorläuferfasern zwischen 1 und 1000 µm und vorzugsweise zwischen 10 und 100 µm beträgt.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass das Lösungsmittel der Ligninlösung und das Lösungsmittel der PVA-Lösung ein identisches Lösungsmittel ist.
  3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass das Lösungsmittel der Ligninlösung und/oder das Lösungsmittel der PVA-Lösung aus Wasser, einer wässrigen Lösung, die ein oder mehrere Salze umfasst, einer ionischen Flüssigkeit, einem organischen Lösungsmittel (z. B. N,N-Dimethylformamid, N,N'-Dimethylethylenharnstoff, Ethylenglykol, Dimethylsulfoxid oder Tetrahydrofuran) und einer beliebigen Mischung davon ausgewählt wird und vorzugsweise Dimethylsulfoxid (DMSO) umfasst oder daraus besteht.
  4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass das Koagulationsbad ein Gegenlösungsmittel für die Koagulation von Lignin umfasst, wobei das Gegenlösungsmittel vorzugsweise aus Wasser, einer wässrigen Salzlösung und organischen Lösungsmitteln, die ein/e oder mehrere Hydroxyl-, Polyole-oder Ketone-Gruppen umfassen, die allein oder in Mischungen verwendet werden, ausgewählt wird.
  5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass das Verfahren das Trocknen der koagulierten Fasern, vorzugsweise nach dem Spülen der koagulierten Fasern, umfasst.
  6. Verfahren nach Anspruch 5, dadurch gekennzeichnet, dass die koagulierten Fasern beim Trocknen unter mechanischer Spannung gehalten werden.
  7. Verfahren zur Herstellung von Kohlenstofffasern, wobei das Verfahren das Herstellen von Vorläuferfasern gemäß einem wie in einem der Ansprüche 1 bis 6 definierten Verfahren, gegebenenfalls das Trocknen der koagulierten Fasern, vorzugsweise nach dem Spülen der koagulierten Fasern, und das Karbonisieren der getrockneten Fasern zum Erhalten einer Kohlenstofffaser umfasst.
  8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, dass die Vorläuferfaser unschmelzbar ist und keine Oxidationsbehandlung oder Stabilisierung der Fasern vor dem Karbonisieren benötigt.
  9. Verfahren nach Anspruch 7 oder 8, dadurch gekennzeichnet, dass die Fasern während des Karbonisierens unter mechanischer Spannung gehalten werden.
  10. Material, umfassend oder bestehend aus einer oder mehreren Vorläuferfasern aus Kohlenstofffasern, dadurch gekennzeichnet, dass die Vorläuferfasern einen Anteil an Lignin größer oder gleich 60 Massen-% und einen Polyvinylalkohol (PVA) und einen Durchmesser zwischen 1 und 1000 µm und vorzugsweise zwischen 10 und 100 µm umfassen.
  11. Material, umfassend oder bestehend aus einer oder mehreren Vorläuferfasern aus Kohlenstofffasern, dadurch gekennzeichnet, dass die Vorläuferfasern einen Anteil an Lignin größer oder gleich 60 Massen-% und einen Polyvinylalkohol (PVA) umfassen und einen Durchmesser zwischen 1 und 1000 µm und vorzugsweise zwischen 10 und 100 µm aufweisen und durch ein wie in einem der Ansprüche 1 bis 6 definiertes Verfahren erhalten werden können.
  12. Material nach Anspruch 10 oder 11, dadurch gekennzeichnet, dass die eine oder mehrere Vorläuferfasern ferner kohlenstoffhaltige Füllstoffe umfassen.
  13. Material nach Anspruch 12, dadurch gekennzeichnet, dass die kohlenstoffhaltigen Füllstoffe aus Graphen, Graphenoxid, Kohlenstoffnanoröhren, Zellulose-Whiskern oder mikrofibrillierter Zellulose ausgewählt werden, wobei die Füllstoffe eine Ausrichtung in Faserrichtung induzieren und so die Struktur und die Kristallinität der Verbundfasern verbessern können.
EP18795551.3A 2017-10-30 2018-10-29 Herstellung von kohlenstofffasern aus lignin / pva-precursor-fasern Active EP3704289B1 (de)

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FR1760248A FR3072976B1 (fr) 2017-10-30 2017-10-30 Preparation de fibres de carbone a partir de fibres precurseurs lignine/pva
PCT/EP2018/079571 WO2019086377A2 (fr) 2017-10-30 2018-10-29 Préparation de fibres de carbone à partir de fibres précurseurs lignine/pva

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CN114752201B (zh) * 2022-04-15 2023-05-26 江南大学 一种分散相纳米复合材料、高强高耐内应力开裂共混物及制备方法和应用
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