CN113862811A

CN113862811A - Acrylic fiber and preparation method thereof, and preparation method of carbon fiber

Info

Publication number: CN113862811A
Application number: CN202111350066.XA
Authority: CN
Inventors: 吴瀚森; 孙建旭; 马豪; 张向阳; 梁嫄
Original assignee: Envision Energy Co Ltd
Current assignee: Envision Energy Co Ltd
Priority date: 2021-11-15
Filing date: 2021-11-15
Publication date: 2021-12-31
Anticipated expiration: 2041-11-15
Also published as: CN113862811B

Abstract

The invention relates to acrylic fibers, a preparation method thereof and a preparation method of carbon fibers, wherein the acrylic fibers are copolymerized with a second monomer and/or a third monomer and have the following structural formula:

wherein X and Y are compounds containing one group of carboxyl, amido, amino, hydroxyl, sulfonic acid group, ester group or halogen and corresponding salts thereofX and Y are the same or different, and the mole percentage of m is 85-99.5%; the mol percentage of n is 0.5 to 15 percent; the mol percentage of p is 0-14.5%. The preparation of the acrylic fiber comprises the following steps: and (3) performing solidification molding, water washing, oiling, drying and post-drawing treatment on the stock solution to obtain the acrylic fibers. When the carbon fiber is prepared, the acrylic fiber is subjected to roller feeding, pre-oxidation treatment and carbonization treatment to obtain the carbon fiber. Compared with polyacrylonitrile protofilament, the invention has lower cost and higher cost performance; compared with commercial acrylic fiber, the cost for producing the carbon fiber is equivalent, but the manufacturability is stronger, and the mechanical property performance is better, so the application field is wider, and the competitiveness is promoted.

Description

Acrylic fiber and preparation method thereof, and preparation method of carbon fiber

Technical Field

The invention relates to the technical field of carbon fibers, and particularly relates to acrylic fibers and a preparation method thereof, and a preparation method of carbon fibers.

Background

The carbon fiber is a microcrystalline graphite material fiber with carbon content of more than 90 percent obtained by pre-oxidizing and carbonizing organic fiber, has the advantages of high strength, high specific modulus, small density, chemical corrosion resistance, fatigue resistance, high and low temperature resistance and the like, and is an important basic material for military and civil use. The raw material source can be divided into three types of carbon fiber: PAN-based, asphalt-based, and viscose-based. The PAN-based carbon fiber not only has excellent mechanical property, but also has a mature preparation process, so that the PAN-based carbon fiber is most widely applied and accounts for more than 90% of carbon fiber materials.

However, the PAN-based carbon fiber has high price all the time due to large early investment, high technical barrier and small yield, so that the application of the PAN-based carbon fiber in the civil field is limited. With the advent of carbon neutralization and the wind-powered equivalent times, the demand for carbon fibers in the field of wind-powered blades is increasing day by day, and therefore low-cost carbon fibers become a hot spot of current research. According to research, the cost of the PAN-based carbon fiber is 51% of the raw fiber, 23% of the preoxidation process and 15% of the carbonization process. Therefore, developing a carbon fiber precursor at low cost and improving production efficiency are effective ways to reduce the cost of carbon fibers. We find that the main components of acrylic fibers (also called artificial wool) and PAN precursor are the same, the acrylic fibers are acrylonitrile, the production technical principle and the process route are basically consistent, but the cost of the acrylic fibers is only 50-75% of the cost of the PAN precursor required for preparing carbon fibers, so that the production cost of the carbon fibers prepared by the acrylic fibers can be reduced by 20-50% on the premise of equivalent or slight loss of mechanical properties.

However, the comonomers used in commercial acrylic fibers are mostly monomers lacking in thermal stability promoting units, such as vinyl acetate or methyl acrylate, and the problems of high pre-oxidation initial reaction temperature, concentrated reaction heat release, poor process stability and the like are generally caused. In the past, people modify acrylic fibers in different physical/chemical modes, such as soaking with chemical reagents, ultraviolet light or electron beam irradiation, but the pretreatment process is complex, the investment is large, the effect is poor, and the method cannot be applied to the large-scale production of actual carbon fibers.

Therefore, a carbon fiber product with low production cost, strong manufacturability and up-to-standard performance is urgently needed in the field.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide acrylic fiber and a preparation method thereof.

The application also aims to provide a method for preparing carbon fibers by using the acrylic fibers.

In order to achieve the object of the present invention, the present application provides the following technical solutions.

In a first aspect, the present application provides a method for preparing a customized acrylon, wherein the chemical structural composition of the polymer is represented by formula (I):

wherein m is 85 to 99.5 percent of molar ratio, n is 0.5 to 15 percent of molar ratio, and p is 0 to 14.5 percent of molar ratio.

Wherein, X and Y are compounds containing one group of carboxyl, amido, amino, hydroxyl, sulfonic acid group, ester group or halogen and corresponding salts thereof, and X and Y are the same or different;

R1/R2 comprise one of hydrogen atom, methyl, halogen or carboxymethyl, and R1 and R2 can be the same or different.

When X/Y is substituted carboxyl, substituted amido, substituted amino, substituted hydroxyl or substituted sulfonic group, the preoxidation process can generate a cyclization reaction of nucleophilic attack, the reaction starting temperature is reduced, and the reaction heat release is more smooth. The carboxyl group is taken as an example and is shown as follows:

in the past, due to the lack of similar functional groups in acrylon, the preoxidation process was only capable of radical attack cyclization as follows:

the chemical bond breaking generates free radicals, and a high reaction temperature is needed, so that the whole process has intense and concentrated heat release, and the acrylic fiber is easy to blow in the oxidation cyclization process, so that the commercial acrylic fiber can be used for producing carbon fibers, but the problems need to be solved. Therefore, the invention provides the following preferred formula acrylon:

preferably, when said-X is substituted-COOH, -R₁substituted-CH₂COOH, -Y is substituted-COOCH 3, -R₂Substituted H is of formula (II):

more preferably, x is 95 to 99 mol%, y is 1 to 3 mol%, and z is 0 to 4 mol%.

More preferably, x is 97% mole, y is 1% mole and z is 2% mole.

Preferably, the average weight average molecular weight Mw of the custom acrylic polymer is more than or equal to 30,000, and the molecular weight distribution Mw/Mn is more than or equal to 3. More preferably, the average weight average molecular weight Mw is 30,000-100,000, and the molecular weight distribution Mw/Mn is 3-6.

The invention also provides a one-step method or two-step method for preparing the acrylic continuous fiber, which comprises the following steps:

the acrylic fiber polymer stock solution is prepared by carrying out aqueous phase suspension polymerization, demonomerization, defoaming, filtering, granulation and dissolution on monomers in an organic or inorganic solvent, wherein the solvent can be a solution of dimethylacetamide, dimethylformamide, dimethyl sulfoxide, ethylene carbonate, nitric acid, zinc dichloride or sodium thiocyanate.

Preferably, no flatting agent (titanium dioxide) is added into the acrylic fiber polymer stock solution, and all the obtained acrylic fibers are glossy fibers. As is known, commercial acrylic fibers are matted or semi-matted fibers and therefore contain a certain amount of titanium dioxide. Titanium dioxide has a melting point of 1840 ℃ and is hardly soluble in organic solvents or water, so that if commercial acrylic fibers are directly preoxidized or carbonized, titanium dioxide still maintains the original structure, and titanium dioxide particles attached to the surface of the fibers or entering the interior of the fibers hinder the permeation of oxygen, inhibit the heat transfer efficiency, are not favorable for the production process, and also reduce the mechanical properties of carbon fibers as impurities in the fibers. In addition, the presence of titanium dioxide increases the burden on the equipment and the production cost. Therefore, the delustering agent is eliminated, the performance of the carbon fiber can be improved, and the production cost of the acrylic fiber can be reduced.

The acrylic fiber is prepared from a polymer stock solution through wet spinning, dry spinning or dry and wet spinning, and comprises the working procedures of coagulating bath spinning forming, washing, oiling, drying and post-steam drafting. Wherein, the post steam drafting process can be finished on line or off line.

Preferably, the invention is prepared by adopting a two-step method and a wet process.

Preferably, the polymer dissolution solvent of the present invention is dimethylacetamide.

Preferably, the polymer stock solution passes through 1 coagulation bath under the condition of a dimethyl sulfoxide-water system, and the concentration of the dimethyl sulfoxide is 50-85%.

Preferably, the nascent fiber is subjected to a water washing process under the condition of deionized water at the temperature of 80-100 ℃. The solvent content in the fiber after water washing is not more than 1.5 w%.

Preferably, the washed fiber is subjected to an oiling process, so that the washed fiber is soaked in the oil agent mixed solution to complete the oiling process. Preferably, a silicon-based oil agent is used in the present invention.

More preferably, the epoxy modified polydimethylsiloxane oil is used in the invention, and the content of the oil in the fiber is between 0.25 w% and 0.85 w%. In the past, the acrylic fiber spinning oil mostly selects organic acid fatty alcohol or polyol ester as a main component to play a role in lubrication and friction prevention, but the temperature resistance is poor. Through experiments, the acrylic fiber oiling agent can be used for carbon fiber production, but in the pre-oxidation process, the acrylic fiber oiling agent attached to the surface of the fiber can cause the adhesion of tows, so that the subsequent production is not facilitated.

Therefore, in the present invention, a silicon-based oil agent having higher heat resistance can be preferably used to avoid the above problem.

Preferably, the method comprises at least one drying process, and preferably, the temperature is 100-200 ℃; more preferably, the temperature is 140-180 ℃, and the water content of the dried fiber is not more than 3 w%.

Preferably, the total draft ratio in the drawing operation included in the total molding step of the present invention is 100% to 1000%.

Preferably, the acrylic fiber forming step does not include a curling step, and the obtained acrylic fiber does not have a curled shape. In the past, in order to improve spinning performance of acrylic fibers and to increase the feel and appearance of yarns and products, good and stable crimp has been required. However, through research, the curling position of the acrylic fiber is found to be the weak point of the mechanical property, which causes the yarn breakage in the production process of the carbon fiber, so the curling process is eliminated in the production process of the acrylic fiber.

Preferably, the drying and shaping process of the invention must be carried out by a drafting process, and the drafting multiple is 10-500%. More preferably, the drafting is steam drafting, and the drafting multiple is 100-350%. The fineness of the obtained acrylic fiber is 0.8 to 2 deniers, and more preferably, the fineness of the obtained acrylic fiber is 1 to 1.5 deniers. In the past, the mechanical property requirement of acrylic fiber is not high, so only hot water drafting process is needed, but experiments show that the mechanical property of carbon fiber prepared by commercial acrylic fiber is low, and the tensile modulus of the carbon fiber is not more than 180 GPa. Therefore, at least one steam draft is added in the production process of the invention, namely, the heating and plasticizing action of steam is utilized, when the temperature of the fiber is higher than the glass transition temperature of the fiber, the activity of the internal macromolecular chain segment is increased, and a certain tensile stress is applied, so that the axial aggregation and rearrangement of the structural units can be improved, the orientation of the molecular chains is facilitated, the optimal stress state of the molecular chains is facilitated to be optimized, the diameter and fineness of the fiber are reduced, and the performance of the final carbon fiber is improved.

In addition, the invention also provides a method for preparing carbon fiber by applying acrylic fiber, and the carbon fiber is obtained by carrying out roller rolling, yarn spreading or pre-drafting, pre-oxidation, low-temperature carbonization treatment and high-temperature carbonization treatment on the acrylic fiber. As known by people, the k number of acrylic fibers is large and is more than 100k, the fiber bundle is thick, heat transfer and oxygen permeation are not facilitated, the skin-core structure of the fibers in the oxidation process is obvious, the performance of the final carbon fibers is reduced, and meanwhile, the fibers are easy to break due to heat accumulation in the production process. Therefore, when the carbon fiber is prepared, a yarn spreading procedure is required to be added for increasing the width of the fiber bundle and reducing the thickness of the fiber, so that the manufacturability of the carbon fiber can be improved, and the subsequent forming process of the carbon fiber composite material is facilitated.

Preferably, the yarn spreading method is mechanical yarn spreading, and the spreading multiple is 200-500%.

Preferably, steam drawing is performed before pre-oxidation, and the multiple is 100-350%.

Preferably, the pre-oxidation temperature profile is 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃ and 275 ℃.

Preferably, the low-temperature carbonization temperature is 500-800 ℃, and the high-temperature carbonization temperature is 1500-2000 ℃.

Compared with the prior art, the invention has the beneficial effects that:

compared with the preparation of carbon fiber by polyacrylonitrile precursor, the preparation of carbon fiber by acrylic fiber of the application has lower cost and higher cost performance; compared with commercial acrylic fibers, the carbon fiber has the advantages that the cost for producing the carbon fiber is equivalent, the centralized heat release risk is smaller, and the mechanical property of the carbon fiber is better, so that the carbon fiber can be more widely applied to the fields of light weight of automobiles, sports materials, wind power generation blades and the like, and the competitiveness of the carbon fiber is promoted.

Drawings

FIG. 1 is a schematic view of a process for producing acrylon;

FIG. 2 is a schematic view of a fiber oiling process;

FIG. 3 is a schematic view of the dried and shaped fiber undergoing a post-steam drafting process;

FIG. 4 is a schematic view of a production process of carbon fibers;

FIG. 5 is a schematic view of a mechanical spreading;

FIG. 6 is a heat release diagram and heat release enthalpy of conventional acrylon and the present invention;

FIG. 7 is a comparison of the cost of carbon fiber prepared from acrylic fibers of the present invention and polyacrylonitrile precursor.

Detailed Description

Unless otherwise indicated, implied from the context, or customary in the art, all parts and percentages herein are by weight and the testing and characterization methods used are synchronized with the filing date of the present application. Where applicable, the contents of any patent, patent application, or publication referred to in this application are incorporated herein by reference in their entirety and their equivalent family patents are also incorporated by reference, especially as they disclose definitions relating to synthetic techniques, products and process designs, polymers, comonomers, initiators or catalysts, and the like, in the art. To the extent that a definition of a particular term disclosed in the prior art is inconsistent with any definitions provided herein, the definition of the term provided herein controls.

The numerical ranges in this application are approximations, and thus may include values outside of the ranges unless otherwise specified. A numerical range includes all numbers from the lower value to the upper value, in increments of 1 unit, provided that there is a separation of at least 2 units between any lower value and any higher value. For example, if a component, physical or other property (e.g., molecular weight, etc.) is recited as 100 to 1000, it is intended that all individual values, e.g., 100, 101,102, etc., and all subranges, e.g., 100 to 166,155 to 170,198 to 200, etc., are explicitly recited. For ranges containing a numerical value less than 1 or containing a fraction greater than 1 (e.g., 1.1, 1.5, etc.), then 1 unit is considered appropriate to be 0.0001, 0.001, 0.01, or 0.1. For ranges containing single digit numbers less than 10 (e.g., 1 to 5), 1 unit is typically considered 0.1. These are merely specific examples of what is intended to be expressed and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application. It should also be noted that the terms "first," "second," and the like herein do not define a sequential order, but merely distinguish between different structures.

When used with respect to chemical compounds, the singular includes all isomeric forms and vice versa (e.g., "hexane" includes all isomers of hexane, individually or collectively) unless expressly specified otherwise. In addition, unless explicitly stated otherwise, the use of the terms "a", "an" or "the" are intended to include the plural forms thereof.

The terms "comprising," "including," "having," and derivatives thereof do not exclude the presence of any other component, step or procedure, and are not intended to exclude the presence of other elements, steps or procedures not expressly disclosed herein. To the extent that any doubt is eliminated, all compositions herein containing, including, or having the term "comprise" may contain any additional additive, adjuvant, or compound, unless expressly stated otherwise. Rather, the term "consisting essentially of … …" excludes any other components, steps or processes from the scope of any of the terms hereinafter recited, except those necessary for performance. The term "consisting of … …" does not include any components, steps or processes not specifically described or listed. Unless explicitly stated otherwise, the term "or" refers to the listed individual members or any combination thereof.

The invention provides a preparation method of customized acrylon, the chemical structure composition of the polymer is shown as the formula (I):

preferably, when said-X is substituted-COOH, -R1 substituted-CH 2COOH, -Y is substituted-COOCH 3, -R2 is substituted-H, preferably, m is 97% molar, n is 1% molar, and p is 2% molar, as in formula (III)

The present invention is not particularly limited in terms of the source of all raw materials, and any raw materials are commercially available, wherein the preferred polymer represented by the formula (III) is prepared by an aqueous polymerization method: as in procedure 10, the monomers acrylonitrile, itaconic acid and methyl acrylate are mixed in a molar equivalent of 100: 2: 4 adding the mixture into a reaction kettle, taking deionized water as a reaction medium, adding initiators of ammonium ferrous sulfate-potassium persulfate and sodium bisulfite, and carrying out free radical polymerization reaction, and obtaining a working procedure 11.

In addition, the invention also provides a process route of acrylon, which is specifically shown in figure 1:

and after the polymerization is finished, discharging the slurry from the top of the reaction kettle, introducing the slurry into a monomer removing tower for removing monomers and defoaming, filtering and separating polymer precipitate, and drying and granulating. Re-dissolving the pelletized polymer in a dimethylacetamide solvent to obtain 25-50% of a spinning solution, filtering and defoaming, feeding the spinning solution into a candle filter by a spinning metering pump, and feeding the spinning solution into a coagulating bath from a spinneret to form nascent fibers, in step 12.

Subsequently, the nascent fiber is further subjected to water washing and stretching, the stretching multiple is 600 percent, the diameter of the nascent fiber is reduced, and the content of the solvent in the fiber is not more than 1.5w percent, in the working procedure 13.

Specifically, the fiber is subjected to a oiling process, as shown in fig. 2, an epoxy modified polydimethylsiloxane finish is used, and the finish content in the fiber is between 0.25 w% and 0.85 w%. In step 14 shown in FIG. 1, the fiber bundle 35 is passed through a finish bath 33 equipped with a silicone oil bath by a guide roll 36, and the finish impregnates the fibers and adheres to the fiber surfaces. In the oiling process, the concentration of the oil agent in the tank needs to be kept basically constant, so that the old oil agent solution needs to be continuously recycled, and fresh oil agent solvent such as 34 needs to be supplemented.

Subsequently, the fiber attached with the silicone oil is dried and simultaneously drafted by a certain amount with the multiple of 11 percent in a drying procedure 15 to obtain the shaped fiber, wherein the water content of the fiber is not more than 3w percent.

In particular, the process route of the present invention is free of crimping steps, and therefore, uncrimped fibers are obtained.

Specifically, the dried and set fiber is subjected to the post-steam drawing step 16, and as shown in fig. 3, the draw ratio is 150%. The fiber 31 is post-steam drawn to provide a fiber 32, the fiber 32 having a smaller diameter than the fiber 31.

And finally, the post-drawing process can be finished off line, namely the dried fiber is packaged, the fiber is transferred to another area, the roller 18 is rolled again, the post-steam drawing process 16 is carried out, and finally the fiber is packed again to obtain an acrylic fiber product 19.

Acrylic example A:

the chemical composition of the polymer is acrylonitrile: itaconic acid: 97% of methyl acrylate: 1%: 2% molar content, a fiber k number of 480k, and is formed by plying 8 strands of 60k single yarns. The diameter of the spinning orifice is 0.063mm, and the spinning speed is 5.73 m/min. The solvent is dimethyl sulfoxide, the wet drafting multiple is 600 percent, the dry drafting multiple is 113 percent, and the steam drafting multiple is 110 percent. The oil content was 0.62 w%, the fineness was 1.3 deniers, the cross-sectional shape was kidney-shaped, the tensile strength was 4.29cN/dtex, and the elongation at break was 13.45%. (test characterization is according to GBT 14335-

Acrylic example B:

the chemical composition of the polymer is acrylonitrile: itaconic acid: 99.5% of methyl acrylate: 0.5%: 0% molar content, a fiber k number of 480k, and is formed by plying 8 strands of 60k single yarns. The diameter of the spinning orifice is 0.063mm, and the spinning speed is 5.73 m/min. The solvent is dimethyl sulfoxide, the wet drafting multiple is 600 percent, the dry drafting multiple is 113 percent, and the steam drafting multiple is 110 percent. The oil content was 0.28 w%, the fineness was 1.3 denier, the tensile strength was 4.31cN/dtex, and the elongation at break was 13.36%.

Acrylic example C:

the chemical composition of the polymer is acrylonitrile: acrylic acid: 85% of methyl acrylate: 15%: 0% molar content, a fiber k number of 480k, and is formed by plying 8 strands of 60k single yarns. The diameter of the spinning orifice is 0.063mm, and the spinning speed is 5.73 m/min. The solvent is dimethyl sulfoxide, the wet drafting multiple is 600 percent, the dry drafting multiple is 113 percent, and the steam drafting multiple is 0 percent. The oil content was 0.45 w%, the fineness was 1.4 denier, the tensile strength was 4.14cN/dtex, and the elongation at break was 14.97%.

Acrylic example D:

the chemical composition of the polymer is acrylonitrile: acrylic acid: vinyl acetate 85%: 0.5%: 14.5% molar content, a fiber k number of 240k, and was plied from 4 plies of 60k single yarn. The diameter of the spinning orifice is 0.063mm, and the spinning speed is 5.73 m/min. The solvent is dimethyl sulfoxide, the wet drafting multiple is 600 percent, the dry drafting multiple is 113 percent, and the steam drafting multiple is 110 percent. The oil content was 0.32 w%, the fineness was 1.3 deniers, the tensile strength was 4.27cN/dtex, and the elongation at break was 13.61%.

Acrylic example E:

the chemical composition of the polymer is acrylonitrile: itaconic acid: methyl acrylate 90%: 5%: 5% molar content, a fiber k number of 240k, and is formed by plying 4 strands of 60k single yarns. The diameter of the spinning orifice is 0.063mm, and the spinning speed is 5.73 m/min. The solvent is dimethyl sulfoxide, the wet drafting multiple is 600 percent, the dry drafting multiple is 113 percent, and the steam drafting multiple is 0 percent. The oil content was 0.52 w%, the fineness was 1.4 denier, the tensile strength was 4.04cN/dtex, and the elongation at break was 14.69%.

Acrylic example F:

the chemical composition of the polymer is acrylonitrile: itaconic acid: 95% of methyl acrylate: 3%: 2% molar content, a fiber k number of 60k, consisting of 1 ply of a 60k single yarn. The diameter of the spinning orifice is 0.063mm, and the spinning speed is 5.73 m/min. The solvent is dimethyl sulfoxide, the wet drafting multiple is 600 percent, the dry drafting multiple is 120 percent, and the steam drafting multiple is 110 percent. The oil content was 0.65 w%, the fineness was 1.2 denier, the tensile strength was 4.75cN/dtex, and the elongation at break was 9.29%.

The properties of the acrylic fibers prepared in examples A-F are shown in the following table:

as shown in FIG. 6, we collected several current acrylic products on the market, which are 1.2D and 1.5D in Korea, 3 grades in China, 1-1.5D, 2-1.5D and 3-1.5D. Experimental comparison shows that the reaction enthalpy of the acrylon (example A) is at least 30% higher than that of the ordinary acrylon, which indicates that under the same conditions, the preoxidation degree of the acrylon is higher, and the carbon fiber yield is improved. Meanwhile, the trade mark 3-1.5D is selected as a contrast, and the acrylic fiber has the advantages of lower reaction starting temperature and smoother exothermic peak, is favorable for reducing the concentrated heat release during the preparation of the carbon fiber and improves the manufacturability.

The invention also provides a method for preparing carbon fiber by applying the customized acrylic fiber, which comprises the preparation steps shown in figure 4, wherein the acrylic fiber 40 can be subjected to a yarn spreading process 42, or a pre-drafting process 43, a pre-oxidation treatment process 44, a low-temperature carbonization treatment process 45 and a high-temperature carbonization treatment process 46 through an upper roller process 41 to obtain the carbon fiber. The yarn spreading method is mechanical yarn spreading, as shown in figure 5, acrylic fibers 50 are spread by a multi-stage spreading roller 51, the spreading multiple is 10-500%, and the spread acrylic fibers can directly enter a pre-oxidation furnace 52 for oxidation cyclization reaction.

Carbon fiber example 1:

the k number of the fiber is 480k, the spreading multiple is 200%, the pre-oxidation temperatures are 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃ and 275 ℃ respectively, and the draft multiples in the pre-oxidation process are 85%, 60%, 35%, 10%, 5% and 2% respectively. The low-temperature carbonization temperature is 650 ℃, the high-temperature carbonization temperature is 1500 ℃, and the draft multiple is 5 percent and-3 percent. The carbon fiber had a diameter of 7.18 μm and a density of 1.771g/cm³The strength is 2550MPa, and the modulus is 224 GPa. (test characterization reference GBT 26752-;GBT 30019 and 2013; GBT 3362-

Carbon fiber example 2:

the number of the fibers k is 480k, the spreading multiple is 250%, the pre-oxidation temperatures are 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃ and 275 ℃ respectively, and the draft multiples in the pre-oxidation process are 75%, 38%, 23%, 13%, 4% and 3% respectively. The low-temperature carbonization temperature 675 ℃ and the high-temperature carbonization temperature 1650 ℃ and the drawing times are 3 percent and-5 percent. The carbon fiber has a diameter of 7.35 μm and a density of 1.732g/cm³The strength is 2230MPa and the modulus is 213 GPa.

Carbon fiber example 3:

the k number of the fiber is 480k, the spreading multiple is 300 percent, the pre-oxidation temperatures are 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃ and 275 ℃ respectively, and the draft multiples in the pre-oxidation process are 59 percent, 43 percent, 18 percent, 9 percent, 5 percent and 4 percent respectively. The low-temperature carbonization temperature is 705 ℃, the high-temperature carbonization temperature is 1800 ℃, and the draft multiple is 4 percent and-4 percent. The diameter of the carbon fiber is 6.95 microns, and the density is 1.754g/cm³The strength was 2120MPa and the modulus was 216 GPa.

Carbon fiber example 4:

the number of the fibers k is 240k, the spreading multiple is 200%, the pre-oxidation temperatures are 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃ and 275 ℃ respectively, and the draft multiples in the pre-oxidation process are 74%, 50%, 20%, 11%, 6% and 3% respectively. The low-temperature carbonization temperature is 700 ℃, the high-temperature carbonization temperature is 1850 ℃, and the drawing multiple is 6 percent and-3 percent. The carbon fiber has a diameter of 7.28 microns and a density of 1.728g/cm³The strength is 2430MPa and the modulus is 210 GPa.

Carbon fiber example 5:

the number of the fibers k is 240k, the spreading multiple is 250%, the pre-oxidation temperatures are 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃ and 275 ℃ respectively, and the draft multiples in the pre-oxidation process are 77%, 50%, 11%, 3%, 5% and 4% respectively. The low-temperature carbonization temperature is 680 ℃, the high-temperature carbonization temperature is 1750 ℃, and the draft multiple is 7 percent and-5 percent. The carbon fiber had a diameter of 7.50 μm and a density of 1.706g/cm³The strength was 2180MPa, and the modulus was 206 GPa.

Carbon fiber example 6:

the k number of the fiber is 60k, the spreading multiple is 200%, the pre-oxidation temperatures are 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃ and 275 ℃ respectively, and the draft multiples in the pre-oxidation process are 68%, 45%, 30%, 15%, 5% and 3% respectively. The low-temperature carbonization temperature is 650 ℃ and the high-temperature carbonization temperature is 1850 ℃, and the drawing multiple is 5 percent and-5 percent. The carbon fiber had a diameter of 7.05 μm and a density of 1.786g/cm³The strength is 2150MPa, and the modulus is 220 GPa.

Carbon fiber examples 1-6 are carbon fibers prepared using acrylic fiber examples a-F and the performance tests are as follows:

we can see from the above examples that the tensile modulus of the carbon fiber prepared by the present invention is not less than 180 GPa. According to literature research, the tensile modulus of the carbon fiber prepared by the common acrylic fiber is not more than 144GPa (e-Polymers 2014; 14(3): 217-224). Therefore, the invention greatly improves the mechanical property of the carbon fiber prepared by the acrylic fiber.

In addition, from the cost dimension analysis, the invention reduces the use of the flatting agent, cancels the curling process, and basically keeps the same production cost with the commercial acrylic fiber though additionally adding a small amount of functional monomers and a post steam drafting process, but the cost is reduced by nearly 30 percent compared with the polyacrylonitrile protofilament. A50K protofilament is used as a contrast, a single-production line is provided with 24 spinneret plates, stranding is not carried out, 24 channels are formed, single-channel filament bundles are 50K, the spinning running speed is 70m/min, and the annual capacity of single lines is 7000 tons. The single line of the acrylic fiber production line is provided with 40 spinneret plates, and can be plied to form 5 channels, the single-channel filament bundle is 480K, the running speed is 80m/min, the annual capacity of the single line is at least 10,000 tons, and the cost can be directly reduced by 30% from capacity analysis. As shown in the following table:

meanwhile, the carbon fiber is prepared by using the acrylic fiber, the unit output efficiency is higher, if the unit price of the carbon fiber is reduced by 28% under the condition of yarn spreading, the condition of yarn non-spreading is reduced by 23% compared with the condition of yarn spreading, as shown in figure 7. Compared with the preparation of carbon fiber by using polyacrylonitrile precursor, the preparation method has the advantages of lower cost and higher cost performance; compared with the common acrylic fiber, the carbon fiber has the advantages of equivalent production cost, stronger manufacturability and better mechanical property.

The embodiments described above are intended to facilitate the understanding and appreciation of the application by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present application is not limited to the embodiments herein, and those skilled in the art who have the benefit of this disclosure will appreciate that many modifications and variations are possible within the scope of the present application without departing from the scope and spirit of the present application.

Claims

1. The acrylic fiber is characterized by being copolymerized by an acrylonitrile monomer, a second monomer and a third monomer, and has the following structural formula:

R₁/R₂including one of hydrogen atom, methyl, halogen or carboxymethyl, R₁And R₂The same or different;

the mol percentage of m is 85 to 99.5 percent; the mol percentage of n is 0.5 to 15 percent; the mol percentage of p is 0-14.5%.

2. The acrylic fiber of claim 1 wherein the second and third monomers comprise methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, dimethyl itaconate, dibutyl itaconate, vinyl acetate, sodium methallyl sulfonate, n-hexyl methacrylate, vinyl chloride, vinyl bromide, 1, 1-dichloroethylene, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, 2-acrylamide-2-methylpropanesulfonic acid, N-methacrylamide, N-methylolacrylamide, methacrylamide, N-methylmethacrylamide, N-dimethylacrylamide, N-methylolacrylamide, acrylamide or homologues thereof, or any combination thereof.

3. The acrylic fiber according to claim 1, wherein the acrylic fiber has a single filament fineness of 0.8 to 3.5 denier and a breaking strength of not less than 2 cN/dtex; the number of filaments in the single strand bundle is 60k or more.

4. A method for preparing acrylic fibers as claimed in any one of claims 1 to 3, characterized in that the method comprises the following steps:

(1) copolymerizing an acrylonitrile monomer, a second monomer and a third monomer to obtain an acrylic polymer;

(2) carrying out monomer removal, defoaming, filtering or granulation on an acrylic fiber polymer, and re-dissolving to obtain a polymer stock solution, and then preparing acrylic fibers by a dry spinning method, a wet spinning method or a dry and wet spinning method;

wherein the second monomer and the third monomer can be methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, dimethyl itaconate, dibutyl itaconate, vinyl acetate, sodium methallyl sulfonate, n-hexyl methacrylate, vinyl chloride, vinyl bromide, 1, 1-dichloroethylene, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, 2-acrylamide-2-methylpropanesulfonic acid, N-methacrylamide, N-methylolacrylamide, methacrylamide, N-methylmethacrylamide, N-dimethylacrylamide, N-methylolacrylamide, acrylamide or homologues thereof, or any combination thereof.

The acrylonitrile monomer, the second monomer and the third monomer are in a molar ratio of (85-99.5): (0.5-15): (0 to 14.5).

5. The method for preparing acrylic fiber as claimed in claim 4, wherein the solvent used for dissolving the acrylic fiber polymer comprises one or any combination of dimethylacetamide, dimethylformamide, dimethyl sulfoxide, ethylene carbonate, nitric acid, zinc dichloride or sodium thiocyanate.

6. The method for producing acrylon according to claim 4, characterized in that the method for producing acrylon further comprises the following steps: the polymer stock solution is processed by the working procedures of coagulating bath spinning forming, water washing, oiling, drying and post-drawing.

7. The process for producing acrylic fibers as claimed in claim 6, wherein the coagulation bath used in the coagulation bath spinning step is a mixture of a polymer dope solvent and water;

soaking the nascent fiber in a washing tank to finish a washing process at 60-100 ℃ through at least one washing process, wherein the solvent content in the fiber after washing is not more than 1.5 w%;

at least one oiling process is carried out, so that the fiber after washing is soaked in the oiling agent mixed solution to complete the oiling process, and the oiling agent content in the fiber is 0.2 w-1.5 w%;

at least one drying procedure is carried out, the drying temperature is not lower than 100 ℃, and the water content in the final fiber is not more than 3 w%;

at least one post-drawing process is carried out, the drawing temperature is 90-250 ℃, and the drawing multiple is 10-500%.

8. A method for producing carbon fiber using the acrylic fiber according to any one of claims 1 to 3, characterized by comprising the steps of:

and (3) carrying out roller feeding, pre-oxidation treatment and carbonization treatment on the acrylon to obtain the carbon fiber.

9. The method for producing a carbon fiber according to claim 8, wherein the method for producing a carbon fiber comprises a spreading or pre-drawing process, in which,

the spreading multiple of the yarn spreading process is 10-1000%;

the multiple of the pre-drafting process is 10-500%.

10. The method for producing carbon fiber according to claim 8, wherein the pre-oxidation treatment comprises at least 4 temperature zones, the temperature range being 200 to 300 ℃;

the carbonization treatment comprises low-temperature carbonization and high-temperature carbonization, wherein the temperature of the low-temperature carbonization is 500-1000 ℃, and the temperature of the high-temperature carbonization is 1000-2000 ℃.