TWI643988B - Method for converting raw material composite carbon fiber by using raw material - Google Patents

Abstract

The invention relates to a method for producing low-cost raw carbon composite carbon fiber by using raw material, and provides a method for converting raw fiber-forming raw carbon fiber to raw fiber raw material, and improving lignin-based carbon fiber easy degradation and The phenomenon of uneven surface and the non-recyclable nature of the process solvent can effectively reduce the operating cost of the carbon fiber process. The invention is characterized in that the lignin raw material is uniformly dissolved by using a special ionic liquid and the lignin/standard cellulose raw composite fiber is prepared by the wet spinning equipment, and the ionic liquid solvent can be recycled and reused, and the raw material is mixed. It can improve the structural defects and broken filaments of lignin-based carbon fibers, and the pre-soaking of phenolic resin in the stabilization stage of lignin fiber can greatly reduce the phenomenon of brittle fracture caused by shrinkage during lignin fiber carbonization, and enhance the glass transfer through two-stage heating. The temperature maintains the surface integrity of the lignin fiber and retains the fiber form. The surface of the obtained lignin/standard cellulose raw composite carbon fiber is uniform and complete without voids, thereby creating a continuous and stable low-cost biomass composite carbon fiber production system.

Description

Method for converting raw material composite carbon fiber by using raw material

The invention relates to a method for converting raw carbon composite carbon fiber by using raw material, in particular to provide a composite carbon fiber suitable for conversion of raw biomass to raw fiber raw materials, in particular to improve the degradation of lignin-based carbon fiber. The phenomenon of uneven surface and the non-recyclable nature of the process solvent can effectively reduce the operating cost of the carbon fiber process.

Carbon fiber has a carbon content of more than 90%, a chemical structure similar to graphite, and has excellent tensile strength, high modulus of elasticity, high electrical conductivity and high thermal conductivity. The weight of the steel is three cents under the same volume. One of them, the strength is up to four times higher, and is widely used in the research and development of materials such as aerospace, military, energy and sports. The current preparation of carbon fiber precursor materials are mainly Rayon, Polyacrylonitrile (PAN) and Pitch. Among them, 缧萦 was the first material to be prepared as high-strength carbon fiber, but it was limited by the low yield and the rise of polyacrylonitrile material, which quickly replaced and became the main process of the carbon fiber industry. After that, although the asphalt raw material has the advantage of cost, And the performance and yield of carbon fiber is still less than that of polyacrylonitrile. At present, polyacrylonitrile has been widely used in commercial development. 80% of the commercial carbon fiber on the market is made of polyacrylonitrile. The carbon fiber manufacturing process is generally pre-oxidized and low-temperature carbonized. Heat treatment and pyrolysis procedures such as high temperature carbonization (graphitization), but the process of exothermic process and high temperature condensation of oxidized fibers is prone to heterogeneous fracture phenomena such as low physical density and structural defects, and the above are all petrochemical raw materials, which are petroleum. The non-renewable resources such as base or coal are predecessor materials, and the slow carbonization of polyacrylonitrile carbon fiber, the high price and the uneven distribution of asphalt carbon fiber quality are limited by the gradual shortage of material resources and the increase of carbon fiber demand. Reducing the cost of carbon fiber, so it can regenerate non-petroleum-based low-cost carbon fiber Develop research priorities for today. The fiber raw material structure is composed of cellulose, hemicellulose and lignin. The lignin is an amorphous polymer compound, which is mainly composed of aromatic polymerization. Its basic structure is phenylpropane (C6-C8) type structure. Herbs account for about 15-20%, woody plants can reach 30%, and lignin composition is rich in more than 60% of carbon components can be used as a carbon replacement material, plus lignin belongs to renewable resources and polypropylene. Compared with nitrile and asphalt, the expected cost is relatively low, highlighting the high potential application value of lignin. At present, lignin-based carbon fiber is a breakthrough in the development of bio-based carbon fiber technology. For example, the free hydroxyl group of lignin or lignin derivative can be derivatized by monovalent and bivalent free radicals to make it spinnable. The fibers are carbonized and then carbonized into carbon fibers by forming a non-thermoplastic stabilizer fiber through a general stabilization process. Lignin is not a good fiber-forming material in the unmodified case. Most of the literature adds additional additives to promote derivatization and melt-spinning to form long fibers. However, the additive is suitable for spinning fiber based on lignin raw materials. And subsequent carbonization processes are prone to adverse effects, such as JF Kadla, S Kubo, RA Venditti, RD Gilbert, AL Compere, W Griffith. Lignin-based carbon fibers for composite fiber applications Carbon, 2002, Vol .40 (15), pp.2913-2920) melt-spinning with sulphated lignin added with 5% ratio of polyethylene oxide (PEO). The long fibers in the curing process are highly viscous and carbonized carbon fibers only With 0.4Gpa tensile strength, the elastic modulus is in the range of 40-50 GPa, far lower than the commercial carbon fiber value or even lower than the fiberglass property, and PEO is a synthetic polymer with flammable, carcinogenic and irritating properties at room temperature. There are still safety concerns for the room temperature spinning process; in addition, Inventia Company proposed a loan in the Republic of China patent case TW201335452 Heat treatment in the absence of an oxidizing agent, a method for producing a stable lignin fiber from softwood alkaline lignin, which is subjected to a stable heat treatment in the absence of an oxidizing agent through a different heating rate change, and is obtained by extracting black liquor obtained from a general alkaline solution. Quality, while helping to maintain surface integrity, requires a large amount of alkaline solvent and is not recyclable. In addition, Stora Enso also proposed the Republic of China patent case TW201715106, which added some salts in the precipitation bath to minimize the loss of lignin, but its lignin has poor stability in the preparation of carbon fiber. At present, most of the patents focus on the development of renewable materials, lignin-based carbon fiber thermoplastic process improvement, the need to add derivatives for thermoplastic purposes, such as WO2012156441A1 using N-methylmorpholine-N-oxide (NMMO) The solvent dissolves the lignin fiber, but this method easily causes degradation of the lignin fiber in the forming tank and is not recyclable. Therefore, it is easy for the acne-like user to cause lignin degradation during the melt spinning process, which cannot meet the needs of the user in actual use.

The main object of the present invention is to overcome the above problems encountered in the prior art and to provide a composite carbon fiber suitable for conversion of raw biomass to raw fiber raw materials for a wide range of fiber raw materials, and to select an appropriate and recyclable ionic solution for the process. The spinning solvent dissolves the lignin/standard cellulose mixture, and the lignin/standard cellulose raw composite fiber is prepared by continuous wet spinning equipment, and further carbonized into lignin/standard cellulose raw composite carbon fiber through heat treatment. The raw material mixing method greatly improves the phenomenon of easy degradation and surface unevenness of the original melt spinning process, and the non-recyclable nature of the process solvent, effectively reducing the operating cost of the carbon fiber process, and improving the lignin/standard cellulose biocomposite compound. The basic physical properties of carbon fiber, showing a significant difference in the method of converting raw biomass composite carbon fiber using raw materials. For the purpose of the above, the present invention is a method for converting a raw material composite carbon fiber by using a raw material, which comprises at least the following steps: a procedure for dissolving the raw material: separating the raw material into more than 90% of the solid lignin particles by using a solvent. Mixing the lignin particles with standard cellulose, adding special ionic liquid, mixing and stirring, dispersing and dissolving the lignin/standard cellulose mixture uniformly, preparing into a spinning solution of 1-15 wt%, and spinning with wet spinning equipment. Lignin/standard cellulose raw composite fiber, the ionic liquid removed in the process can be recycled and reused as a spinning solvent; Stabilization/preoxidation procedure: pre-soaking the lignin/standard cellulose raw material with phenolic resin The composite fiber is further stabilized and pre-oxidized in a high-pass oxygen environment to cause a condensation reaction of the structure, and the ring-shaped stable structure is maintained to maintain the surface integrity of the composite fiber, and the lignin/standard cellulose raw composite oxidized fiber is obtained; and carbonization is obtained. Procedure: The lignin/standard cellulose biocomposite oxidized fiber is placed in a high temperature environment of an inert atmosphere, and added in two stages. The carbonization is carried out by heat, and the impurities and impurities are removed by heat treatment to obtain lignin/standard cellulose raw composite carbon fiber. In the above embodiment of the present invention, the dissolved raw material raw material is prepared by mixing the lignin microparticles with the ionic liquid to prepare a 10-15 wt% solution, and heating at 65 to 95 ° C for 4 to 6 hours, and placing Forming in water for evaluation of dissolution characteristics. In the above embodiment of the present invention, the lignin microparticles in the dissolved raw material raw material program are blended with the standard cellulose system in a ratio of 5 to 10%. In the above embodiment of the present invention, the raw material is selected from the group consisting of rice straw, bagasse, Miscanthus, Pennisetum, switchgrass, corn stalk, wood and bamboo. In the above embodiment of the invention, the ionic liquid and the lignin microparticles have Hansen dissolution parameters indicative of their ability to interpenetrate with their lignin properties. In the above embodiment of the invention, the ionic liquid system is selected from the group consisting of 1-Butyl-3-Methylimidazolium Chloride (BMIM]Cl), 1-butyl-3-methyl 1-Butyl-3-Methylimidazolium Hexafluorophosphate, [BMIM]PF6, 1-Butyl-3-Methylimidazolium Tetrafluoroborate, [BMIM]BF4 Or other ionic liquids whose solubility parameters are similar to those of lignin. In the above embodiment of the present invention, the stabilization/preoxidation procedure is performed by immersing the lignin/standard cellulose raw composite fiber and the phenolic resin in a coagulation bath for 24 hours, and then placing it in an oxidation furnace at a pre-oxidation temperature of 150. Stabilization and pre-oxidation were carried out at -300 ° C, a heating rate of 0.5 to 3 ° C / min, and a holding time of 0 to 2 hours. In the above embodiment of the present invention, the carbonization process is to place the lignin/standard cellulose bio-composite oxidized fiber in a high-temperature furnace of a nitrogen atmosphere (>99.99%) at a heating rate of 170 to 200 ° C / h. It is heated to 800-900 ° C and the carbonization process is completed at a temperature of 1200-1400 ° C.

Please refer to FIG. 1 to FIG. 4 , which are schematic diagrams of the process architecture of the present invention, the surface morphology diagram of the lignin/standard cellulose raw composite fiber of the present invention, and the lignin/standard cellulose of the present invention. Photograph of the composite composite oxidized fiber, and the surface and cross-sectional pattern of the lignin/standard cellulose raw composite carbon fiber of the present invention. As shown in the figure: The present invention establishes a method for converting biomass composite carbon fiber by using raw material, and the main implementation structure is as shown in Fig. 1, which comprises at least the following steps: Dissolving raw material raw material program s11: selecting raw material 1 It can be any common biomass waste such as rice straw, bagasse, miscanthus, pennisetum, switchgrass, corn stalk, wood and bamboo. More than 90% of solid lignin particles 3 are separated by solvent 2. The lignin particles 3 and standard After the cellulose 4 is mixed, a special ionic liquid is added and mixed, and the lignin/standard cellulose mixture is uniformly dispersed and dissolved to prepare a spinning solution of 1 to 15 wt%, and the lignin/standard fiber is spun through the wet spinning device. The eucalyptus composite fiber 6, the ionic liquid 5 removed in the process can be reused as a spinning solvent via system recovery. Among them, the invention is characterized in that the ionic liquid system adopts the Hansen dissolution theory to design an ionic liquid having a similar molecular property to lignin, thereby improving the mutual solubility of the ionic liquid. The ionic liquid used may be 1-Butyl-3-Methylimidazolium Chloride ([BMIM]Cl), 1-butyl-3-methylimidazolium hexafluorophosphate (1) -Butyl-3-Methylimidazolium Hexafluorophosphate, [BMIM]PF6), 1-Butyl-3-Methylimidazolium Tetrafluoroborate, [BMIM]BF4, or other dissolution parameters and wood The ionic liquid with similar properties is prepared by mixing lignin microparticles with ionic liquid to prepare a 10-15 wt% solution, heating at 65-95 ° C for 4-6 hours, and forming in water to evaluate the solubility characteristics. In addition, the present invention uses a conventional wet spinning technique to prepare a lignin/standard cellulose raw composite fiber by operating the lignin/ionic liquid viscous solution into an injection pump and controlling the flow through the push. The velocity forms a linear solution, and helps the molecular solution to be aligned in the forward direction through the air gap. After entering the forming tank, the ionic liquid is replaced with a non-solvent of lignin, such as water, and the lignin fiber is shaped by a screw after being formed. The fiber tension is applied and the fiber fineness and elongation can be adjusted. Stabilization/preoxidation procedure s12: Before stabilizing, the lignin/standard cellulose bio-composite fiber 6 and the phenolic resin 7 are immersed in a coagulation bath for 24 hours, and then placed in a high-pass oxygen environment, lignin/standard cellulose raw Pre-oxidation temperature of the composite fiber (mainly based on DSC and TGA set temperature) 150 ~ 300 ° C, heating rate 0.5 ~ 3 ° C / min, and holding temperature for 0 ~ 2 hours for stabilization and pre-oxidation, the structure is produced The condensation reaction is converted into a cyclic stable structure to maintain the surface integrity of the composite fiber, and a lignin/standard cellulose bio-composite oxidized fiber 8 is obtained. Carbonization procedure s13: placing the lignin/standard cellulose raw composite oxidized fiber 8 in a high temperature environment of an inert atmosphere, carbonizing by two-stage heating, and heating to 800 by a heating rate of 170 to 200 ° C / h The carbonization process is completed at ~900 ° C and at a temperature of 1200 to 1400 ° C, and the impurities and impurities are removed by heat treatment to obtain lignin/standard cellulose raw composite carbon fiber 9 . Wherein, the stabilizing stage of the lignin fiber of the invention is pre-soaked with phenolic resin, which can greatly reduce the phenomenon of shrinkage caused by shrinkage during lignin fiber carbonization, and enhance the glass transition temperature through two-stage heating to maintain the surface integrity of the lignin fiber. Retain fiber form. As such, a novel process for converting biomass composite carbon fibers using raw materials is constructed by the above disclosed process. The invention provides a composite fiber carbon fiber suitable for conversion of raw biomass waste into raw fiber raw materials, improves the degradation of lignin-based carbon fiber and surface non-uniformity, and the non-recyclable characteristics of the process solvent, thereby effectively reducing the operation of the carbon fiber process. cost. When used, the invention utilizes different solvents to reconcile, applies different reaction temperatures and reaction time, and dissolves 20-40% lignin in the raw material by one-phase two-phase separation, and concentrates and precipitates more than 90% high purity and low loss lignin under reduced pressure. . In a specific embodiment, the present invention screens wood chips of high lignocellulosic raw materials, and the composition of the wood chips is 44.60%, hemicellulose 18.74% and lignin 30.59%. The composition analysis of the above wood chips was carried out by high-performance liquid chromatography (HPLC) using a Coregel-87H ₃ column with 4 mM sulfuric acid (H ₂ SO ₄ ) at a flow rate of 1 mL min ^-1 . The sample was separated at 65 ° C, the compound signal was detected by a refractive index detector and the separation time of each compound was recorded. According to the mixed solvent, the wood chips are subjected to a phase separation reaction to dissolve the lignin, and the solid lignin particles having a purity greater than 90% in the liquid solution are concentrated and extracted as a reaction raw material, and the dissolution characteristics of the lignin particles and the ionic liquid are evaluated, indicating that the ionic liquid is not It affects the basic properties of lignin particles and can be used simply as a solvent. The degree of lignin polymerization before and after spinning is 11.2 DPv and the molecular weight is 1814. Subsequently, the solid lignin microparticles are mixed with standard cellulose in a ratio of 5-10%, and then added to the ionic liquid, and the mixture is uniformly dispersed and dissolved at 80 ° C to prepare a homogeneous spinning solution of 1 to 10 wt%, followed by spinning. The liquid is placed in a wet spinning apparatus, and the spinning parameter is set to a discharge amount of 2.5 g/min and a take-up speed of 10 m/min to obtain a lignin/standard cellulose raw composite fiber, as shown in Fig. 2. The ionic liquid can be used as a spinning solvent and can be recycled and reused after the preparation of the spun fiber, that is, the reactants such as lignin and standard cellulose are continuously dissolved in the solvent role. In the pre-oxidation stage, the lignin/standard cellulose raw fiber composite fiber is pre-soaked with the fireproof phenolic resin for 24 hours, and then placed in an oxidation furnace, and the temperature is raised to 250 ° C at 2 ° C / min and the temperature is maintained for 1 hour to increase the lignin. /Standard cellulosic biomass composite oxidized fiber uniformity reduces interfiber pore formation (fiber fineness 2.58±0.18, fiber elongation 5.15±0.84, thermal cracking temperature raw material 1 solvent 2 lignin particles 3 standard cellulose 4 ionic liquid 5 Lignin / Standard Cellulose Biomass Composite Fiber 6 Phenolic Resin 7 Lignin / Standard Cellulose Biocomposite Composite Oxidized Fiber 8 Lignin / Standard Cellulose Biomass Composite Carbon Fiber 9 Dissolved Biomass Raw Material Program s11 Stabilization / Preoxidation Procedure S12 carbonization program s13

1‧‧‧ Raw materials

2‧‧‧Solvent

3‧‧‧Lignin particles

4‧‧‧Standard cellulose

5‧‧‧Ionic liquid

6‧‧‧Lignin/Standard Cellulose Composite Fiber

7‧‧‧Phenolic resin

8‧‧‧Lignin/Standard Cellulose Biocomposite Oxidized Fiber

9‧‧‧Lignin/Standard Cellulose Composite Carbon Fiber

S11‧‧‧Solid raw material raw material program

S12‧‧‧Stabilization/Preoxidation Procedure

S13‧‧‧carbonization procedure

Figure 1 is a schematic diagram of the process architecture of the present invention. Fig. 2 is a surface pattern diagram of the lignin/standard cellulose raw composite fiber of the present invention. Figure 3 is a photograph of the lignin/standard cellulose biocomposite oxidized fiber of the present invention. Figure 4 is a diagram showing the surface and cross-sectional morphology of the lignin/standard cellulose biocomposite carbon fiber of the present invention.

Claims (8)

A method for converting a raw material composite carbon fiber by using a raw material, comprising at least the following steps: Dissolving the raw material raw material program: separating the raw material into more than 90% solid lignin particles by using a solvent, and the lignin particles and the standard cellulose After mixing, special ionic liquid is mixed and stirred to uniformly disperse and dissolve the lignin/standard cellulose mixture, and prepare a spinning solution of 1-15 wt%, and mix the lignin/standard cellulose raw material with the wet spinning equipment. Composite fiber, the ionic liquid removed during the process can be recycled and reused as a spinning solvent; Stabilization/preoxidation procedure: pre-soaking the lignin/standard cellulose raw composite fiber with phenolic resin and placing it in a high-pass oxygen environment Stabilization and pre-oxidation, the structure is subjected to a condensation reaction, and the ring-shaped stable structure is maintained to maintain the surface integrity of the composite fiber to obtain a lignin/standard cellulose raw composite oxidized fiber; and a carbonization procedure: the lignin/standard The cellulose raw composite oxidized fiber is placed in a high temperature environment of an inert atmosphere, and carbonized by two-stage heating, by heat Carbide eliminate impurities and impurities to prepare the lignin / cellulose biomass standard composite carbon fibers. The method for converting a raw material composite carbon fiber by using a raw material according to the first aspect of the patent application, wherein the raw material of the raw material is mixed with the ionic liquid to prepare a solution of 10 to 15 wt%. The mixture was heated at 65 to 95 ° C for 4 to 6 hours, and placed in water for evaluation of dissolution characteristics. The method for converting a raw material composite carbon fiber by using a raw material according to the first aspect of the invention, wherein the lignin fine particles in the dissolved raw material raw material are mixed with the standard cellulose system in a ratio of 5 to 10%. The method for converting a raw material composite carbon fiber by using a raw material according to the first aspect of the patent application, wherein the raw material is selected from the group consisting of rice straw, bagasse, miscanthus, pennisetum, switch grass, corn stalk, wood and bamboo. Biomass waste. A method for converting a biomass composite carbon fiber using a raw material according to the first aspect of the invention, wherein the ionic liquid and the lignin microparticle have a Hansen dissolution parameter indicating the interpenetrability of their molecules with lignin properties. The method for converting a raw material composite carbon fiber by using a raw material according to claim 1 or 5, wherein the ionic liquid system is selected from the group consisting of 1-butyl-3-methylimidazolium chloride (1-Butyl-3- Methylimidazolium Chloride, [BMIM]Cl), 1-Butyl-3-Methylimidazolium Hexafluorophosphate, [BMIM]PF6, 1-butyl-3-methylimidazole IV Fluorine (1-Butyl-3-Methylimidazolium Tetrafluoroborate, [BMIM] BF4), or other ionic liquids with similar solubility parameters to lignin. The method for converting a raw material composite carbon fiber by using a raw material according to the first aspect of the patent application, wherein the stabilizing/preoxidizing step is the lignin/standard cellulose raw composite fiber and the phenolic resin. After soaking for 24 hours in the coagulation bath, it is placed in an oxidizing furnace, and is stabilized and pre-oxidized at a pre-oxidation temperature of 150 to 300 ° C, a heating rate of 0.5 to 3 ° C/min, and a holding time of 0 to 2 hours. The method for converting a raw material composite carbon fiber by using a raw material according to the first aspect of the patent application, wherein the carbonization program places the lignin/standard cellulose raw composite oxidized fiber in a nitrogen atmosphere (>99.99%) In the high-temperature furnace, the temperature is raised at a heating rate of 170 to 200 ° C / h to 800 to 900 ° C, and the carbonization process is completed at a temperature of 1200 to 1400 ° C.