Preparation method of carbon fiber suitable for prepreg production

Abstract

The invention discloses a preparation method of carbon fiber suitable for prepreg production, and the preparation method comprises the following steps: preorder step: preparing filaments by using a spinning solution, and obtaining a finished product precursor through a plurality of preparation steps, according to the step of pre-oxidation, finished product protofilaments are subjected to oxidation treatment in the environment at the temperature of 200-300 DEG C, filament bundle monofilaments are opened through air pressure of 0.05-0.30 MPa before the finished product protofilaments enter the pre-oxidation procedure, then the opened finished product protofilaments are evenly arranged on rollers, finished product protofilaments with the uniform filament width are formed after arrangement of two or more sets of rollers, and the finished product protofilaments with the uniform filament width are obtained. And the low-temperature carbonization is to carry out low-temperature carbonization treatment on the finished product protofilament with uniform filament width in an environment of 300-800 DEG C. Compared with the prior art, the preparation method of the carbon fiber suitable for prepreg production has the advantages that the carbon fiber production process is controlled, so that the carbon fiber which is good in spreadability and suitable for prepreg is formed, and the production of the prepreg is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of organic polymer materials, and in particular relates to a method for preparing carbon fibers suitable for prepreg production. Background Art

[0002] Carbon fiber prepreg is a composite material, which is made of carbon fiber yarn, epoxy resin, release paper and other materials through coating, hot pressing, cooling, laminating, winding and other processes. This material forms a high-performance composite material by compounding epoxy resin on carbon fiber under high pressure and high temperature technology. The main characteristics of carbon fiber prepreg are high strength and low density, light weight, high strength, high stiffness, high temperature resistance, corrosion resistance and other characteristics. It is widely used in aerospace, automobile, sports equipment, construction and other fields, and is an important industrial material. As the raw material of carbon fiber prepreg, the carbon fiber tow is not only required to be flat, twist-free, uniform in wire width, but also has good bonding ability with resin. Therefore, it is necessary to study the controllability of carbon fiber according to demand.

[0003] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing carbon fiber suitable for prepreg production, which can solve the technical problems raised in the above background technology.

[0005] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0006] 1. A method for preparing carbon fiber suitable for prepreg production, comprising the following steps:

[0007] S1. Preliminary steps:

[0008] The spinning solution is used to prepare the filaments, and the filaments are prepared through multiple preparation steps to obtain the finished raw filaments;

[0009] S2, pre-oxidation:

[0010] The finished raw silk is oxidized in an environment of 200-300°C. Before the finished raw silk enters the pre-oxidation process, the single filaments of the tow are opened with an air pressure of 0.05-0.30MPa. After that, the opened finished raw silk is evenly arranged on the roller. After being arranged by more than two groups of rollers, the finished raw silk with uniform wire width is formed.

[0011] S3, low temperature carbonization:

[0012] The finished raw silk with uniform wire width is subjected to low-temperature carbonization treatment in an environment of 300 to 800° C. to obtain a first carbonized raw silk;

[0013] S4, high temperature carbonization:

[0014] Placing the first carbonized precursor in an environment of 1000-1600° C. for high-temperature carbonization treatment to obtain a second carbonized precursor;

[0015] S5. Surface treatment:

[0016] Applying a constant current to the second carbonized precursor in an electrolytic solution for surface treatment, and then washing the second carbonized precursor with water to obtain a washed carbonized precursor;

[0017] S6. Sizing:

[0018] Before sizing, the washed carbonized raw silk is first arranged to form a bundle of uniform wire width, and then immersed in a sizing tank for sizing;

[0019] After sizing, the washed carbonized raw silk is dried, and the washed carbonized raw silk after drying is subjected to a second finishing. After finishing by more than two groups of rollers, the wire width is controlled according to actual requirements to form a fiber bundle with uniform wire width;

[0020] S7, Carbon fiber winding:

[0021] The fiber bundles are collected by a winder to obtain finished carbon fibers.

[0022] In one or more embodiments of the present invention, the specific steps of step S1 are:

[0023] S1.1、Aggregation:

[0024] Acrylonitrile and comonomer are polymerized in a dimethyl sulfoxide solution to obtain a polymerization solution;

[0025] S1.2, single and bubble removal:

[0026] Under vacuum conditions, the residual acrylonitrile monomer in the polymerization solution is separated from the system to separate the monomer, and the mixed gas in the polymerization solution is removed to eliminate bubbles, thereby obtaining a spinning solution;

[0027] S1.3, solidification molding:

[0028] The spinning solution enters the coagulation liquid in the form of filaments and coagulates to obtain coagulated filaments;

[0029] S1.4, washing:

[0030] The coagulated filaments are washed by water using a flower roller beating method, the direction of the washing water flow is countercurrent, the water temperature of the washing water is controlled at 30-70° C., and the tension of the filament bundle during the washing process ranges from 1.0 to 3.5 cN / dtex, thereby obtaining the first filaments;

[0031] S1.5, hot water drawing:

[0032] The first filament is placed in hot water and stretched by 1.2 to 4 times to obtain a second filament;

[0033] S1.6, Oiling and drying densification:

[0034] The second wire strips are evenly arranged on the rollers, and the wire width is controlled according to actual requirements to obtain a third wire strip with even wire width;

[0035] The third wire is oiled with silicone oil, and the oiled third wire is dried and densified, and then the third wire is opened with compressed air to obtain a fourth wire;

[0036] S1.7, Steam drawing:

[0037] Using saturated steam to draw the fourth filament by 1.5 to 6 times to obtain a fifth filament;

[0038] S1.8, Heat setting:

[0039] heat setting the fifth filament using saturated steam;

[0040] S1.9, Raw silk collection:

[0041] The fifth silk strips that have undergone the heat setting step are collected to obtain finished raw silk.

[0042] In one or more embodiments of the present invention, the comonomer is one or more combinations of methyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, acrylamide, itaconic acid, ammonium itaconate, and isobutyl methacrylate.

[0043] In one or more embodiments of the present invention, the specific steps of step S1.3 are: the spinning solution is output through a spinning metering pump, flows through a buffer, enters a spinneret assembly and is ejected, adopts a wet or dry-wet spinning process, enters a coagulation liquid for coagulation and forming, and obtains coagulated filaments.

[0044] In one or more embodiments of the present invention, in step S1.6, the roller includes rollers, and the number of the roller rollers is not less than 3;

[0045] The first roller of each group of rollers is a flower roller, the distance between roller groups is not less than 0.5m, and the tension between rollers is maintained at less than 0.5cN / dtex.

[0046] In one or more embodiments of the present invention, the silicone oil is one of modified silicone oil or non-silicone oil;

[0047] The temperature of the drying and densification treatment is 100-190°C;

[0048] The air pressure used to open the third monofilament is 0.05 to 0.30 MPa.

[0049] In one or more embodiments of the present invention, in step S2, each group of rollers includes no less than 5 roller rollers, the distance between each group of rollers is no less than 0.5m, and the tension between the rollers is less than 0.5cN / dtex.

[0050] In one or more embodiments of the present invention, in step S6, during the first finishing, each group of rollers includes no less than 5 roller rollers, the distance between each group of rollers is not less than 0.5m, the tension between the rollers is less than 0.5cN / dtex, and the washed carbonized precursor is finished by at least 2 groups of rollers.

[0051] In one or more embodiments of the present invention, in step S6, during the second finishing, the dried washed carbonized raw silk is evenly arranged on the rollers, each group of rollers includes no less than 3 roller rollers, the first roller roller of each group of rollers is a flower roller, the distance between each group of rollers is no less than 1m, and the tension between the rollers is less than 0.5cN / dtex.

[0052] In one or more embodiments of the present invention, in step S7, a winder is used to collect the fiber bundle, and the effective width of the guide wheel of the winder is not less than 1 to 2 times the width of the fiber bundle.

[0053] Compared with the prior art, the method for preparing carbon fiber suitable for prepreg production of the present invention controls the carbon fiber production process to form carbon fiber with good spreadability and suitable for prepreg, which is beneficial to the production of prepreg. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0055] Figure 1 The relationship between the carbon fiber and the prepreg application process of multiple embodiments of a method for preparing carbon fiber suitable for prepreg production in one embodiment of the present invention Figure 1;

[0056] Figure 2 The relationship between the carbon fiber and the prepreg application process of multiple embodiments of a method for preparing carbon fiber suitable for prepreg production in one embodiment of the present invention Figure 2 ;

[0057] Figure 3 The relationship between the carbon fiber and the prepreg application process of multiple embodiments of a method for preparing carbon fiber suitable for prepreg production in one embodiment of the present invention Figure 3 . DETAILED DESCRIPTION

[0058] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0059] In one embodiment of the present invention, a method for preparing carbon fiber suitable for prepreg production includes polymerization, coagulation molding, water washing, hot water drawing, oiling and drying densification, steam drawing, heat setting, and raw silk collection to obtain finished raw silk, which is then subjected to pre-oxidation, low-temperature carbonization, high-temperature carbonization, surface treatment, sizing, and carbon fiber winding to obtain finished carbon fiber.

[0060] Specifically, the polymerization is carried out by polymerizing acrylonitrile and a comonomer in a dimethyl sulfoxide solution to obtain a polymer solution, wherein the comonomer can be one or more combinations of methyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, acrylamide, itaconic acid, ammonium itaconate, and isobutyl methacrylate.

[0061] Before polymerization and coagulation, it is necessary to separate the residual acrylonitrile monomer in the polymerization solution from the system under vacuum conditions to separate the monomers and remove the mixed gas in the polymerization solution to eliminate bubbles and obtain a spinning solution. The spinning solution is then output through a spinning metering pump, flows through a buffer, enters a spinneret assembly, and then is ejected. A wet or dry-wet spinning process is used to enter the coagulation solution to coagulate into coagulated filaments.

[0062] The water washing uses a flower roller to beat the coagulated filaments. The water flow direction of the washing is countercurrent. The water temperature of the washing is controlled at 30-70°C. The tension range of the filament bundle during the washing process is 1.0-3.5 cN / dtex. After the washing is completed, the first filament is obtained.

[0063] Hot water traction: Place the first wire in hot water for 1.2 to 4 times drafting to obtain the second wire. Then, the second wire is evenly arranged on the roller, and the wire width is controlled according to actual requirements to obtain a third wire with uniform wire width. Silicone oil is used to oil the third wire, and the oiled third wire is dried and densified, and compressed air is used to open the single filaments of the third wire to obtain the fourth wire.

[0064] Specifically, the fibers are evenly arranged on the rollers before oiling, each group of rollers includes ≥3 rollers, the first roller of each group of rollers is a flower roller, the distance between roller groups is ≥0.5m, the tension between rollers is maintained at <0.5cN / dtex, and after being arranged by more than 2 groups of rollers, the wire width is controlled according to actual requirements, and the third wire strip has uniform wire width. Use modified silicone oil or non-silicone oil agent to oil the coagulated wire strip after water washing and traction, and use hot rollers for drying and densification, the drying and densification temperature is 100-190°C, and use compressed air to open the single filaments of the wire bundle after drying and densification, the air pressure used is 0.05-0.30MPa, and the fourth wire strip is obtained after drying and densification.

[0065] Steam drawing is to use saturated water vapor to draw the fourth filament 1.5 to 6 times to obtain the fifth filament. And use saturated water vapor to heat-set the fifth filament. The fifth filament that has undergone the heat-setting step is collected by a winding machine to obtain the finished raw silk. During the operation of the filament bundle, the effective width of all guide wheels is ≥ 1.5 times the wire width.

[0066] Pre-oxidation is to oxidize the raw silk in an environment of 200-300°C. Before the tow enters the pre-oxidation process, compressed air is used to open the single filaments of the tow. The air pressure used is 0.05-0.30MPa. Then the fibers are evenly arranged on the rollers. Each group of rollers includes ≥5 rollers, and the distance between the roller groups is ≥0.5m. The tension between the rollers is maintained at <0.5cN / dtex. After being arranged by more than 2 groups of rollers, a fiber bundle with uniform wire width is formed.

[0067] Low temperature carbonization is to perform low temperature carbonization treatment on the finished raw silk with uniform wire width in an environment of 300-800°C to obtain the first carbonized raw silk, and high temperature carbonization is to place the first carbonized raw silk in an environment of 1000-1600°C for high temperature carbonization treatment to obtain the second carbonized raw silk.

[0068] The surface treatment is to apply a constant current to the second carbonized precursor in an electrolytic solution for surface treatment, and then wash it with water to obtain the washed carbonized precursor. Before sizing, the washed carbonized precursor is first trimmed to form a bundle of uniform width, and then immersed in a sizing tank for sizing. After sizing, the washed carbonized precursor is dried, and the washed carbonized precursor is trimmed for the second time. After being trimmed by more than two groups of rollers, the wire width is controlled according to actual requirements to form a fiber bundle with uniform wire width.

[0069] Specifically, the fibers are evenly arranged on the rollers, each group of rollers includes ≥5 rollers, the distance between roller groups is ≥0.5m, and the tension between rollers is maintained at <0.5cN / dtex. After being sorted by more than two groups of rollers, a bundle of fibers with uniform width is formed, and then immersed in a sizing tank for sizing. After sizing, the silk strips are dried, and the dried fibers are sorted for the second time.

[0070] The second finishing is to arrange the washed carbonized raw silk evenly on the rollers after drying. Each group of rollers includes ≥3 rollers. The first roller of each group of rollers is a flower roller. The distance between roller groups is ≥1m. The tension between rollers is maintained at <0.5cN / dtex. After finishing with more than 2 groups of rollers, the wire width is controlled according to actual requirements to form a fiber bundle with uniform wire width.

[0071] Finally, the winder is used to collect the carbon fiber to obtain the finished carbon fiber. During the operation, the effective width of all guide wheels is ≥ 1.5 times the wire width.

[0072] Embodiment 1:

[0073] Before oiling, the second silk strip is evenly arranged on two groups of rollers. Each group of rollers includes 5 roller rollers. The first roller roller of each group of rollers is a flower roller. The distance between the roller groups is 0.5m. The tension between the rollers is maintained at 0.4cN / dtex. After being arranged by more than two groups of roller rollers, the fourth silk strip is obtained.

[0074] The fourth filaments were dried and densified, and then compressed air was used to open the filament bundles. The air pressure used was 0.10 MPa.

[0075] The effective width of the guide wheel during the fiber bundle collection process is 1.5 times the fiber width.

[0076] Before the finished raw silk enters the pre-oxidation process, compressed air is used to open the filament bundle. The air pressure used is 0.10MPa. Then the fibers are evenly arranged on the rollers. Each group of rollers includes 5 rollers. The distance between the roller groups is 0.5m. The tension between the rollers is maintained at 0.4cN / dtex. After being arranged by two groups of rollers, the finished raw silk with uniform wire width is formed.

[0077] Before sizing, the washed carbonized raw silk is evenly arranged on the rollers. Each group of rollers includes 5 rollers. The distance between the roller groups is 0.5m. The tension between the rollers is maintained at 0.4cN / dtex. After being arranged by two groups of rollers, a fiber bundle with uniform wire width is formed.

[0078] After sizing and drying, the washed carbonized raw silk is evenly arranged on the rollers. Each group of rollers includes 3 rollers. The first roller of each group of rollers is a flower roller. The distance between the roller groups is 1m. The tension between the rollers is maintained at 0.4cN / dtex. After being arranged by two groups of rollers, a fiber bundle with uniform wire width is formed. The effective width of all guide wheels during the carbon fiber winding process is 1.5 times the wire width.

[0079] Embodiment 2:

[0080] Before oiling, the second silk strip is evenly arranged on two groups of rollers. Each group of rollers includes 5 roller rollers. The first roller roller of each group of rollers is a flower roller. The distance between the roller groups is 0.5m. The tension between the rollers is maintained at 0.4cN / dtex. After being arranged by more than two groups of roller rollers, the fourth silk strip is obtained.

[0081] The fourth filaments were dried and densified, and compressed air was used to open the filaments of the filament bundle. The air pressure used was 0.20 MPa.

[0082] During the fiber bundle collection process, the effective width of the guide wheel is twice the wire width.

[0083] Before the finished raw silk enters the pre-oxidation process, compressed air is used to open the filament bundle. The air pressure used is 0.20MPa. Then the fibers are evenly arranged on the rollers. Each group of rollers includes 5 rollers. The distance between the roller groups is 0.5m. The tension between the rollers is maintained at 0.4cN / dtex. After being arranged by two groups of rollers, the finished raw silk with uniform wire width is formed.

[0084] Before sizing, the washed carbonized raw silk is evenly arranged on the rollers. Each group of rollers includes 5 rollers. The distance between the roller groups is 0.5m. The tension between the rollers is maintained at 0.4cN / dtex. After being arranged by two groups of rollers, a fiber bundle with uniform wire width is formed.

[0085] After sizing and drying, the washed carbonized raw silk is evenly arranged on the rollers. Each group of rollers includes 3 rollers. The first roller of each group of rollers is a flower roller. The distance between the roller groups is 1m. The tension between the rollers is maintained at 0.4cN / dtex. After being arranged by two groups of rollers, a fiber bundle with uniform wire width is formed. The effective width of all guide wheels during the carbon fiber winding process is twice the wire width.

[0086] Embodiment three:

[0087] Before oiling, the second silk strip is evenly arranged on two groups of rollers. Each group of rollers includes 5 roller rollers. The first roller roller of each group of rollers is a flower roller. The distance between the roller groups is 0.5m. The tension between the rollers is maintained at 0.3cN / dtex. After being arranged by more than two groups of roller rollers, the fourth silk strip is obtained.

[0088] The fourth filaments were dried and densified, and then compressed air was used to open the filament bundles. The air pressure used was 0.10 MPa.

[0089] The effective width of the guide wheel during the fiber bundle collection process is 1.5 times the fiber width.

[0090] Before the finished raw silk enters the pre-oxidation process, compressed air is used to open the filament bundle. The air pressure used is 0.10MPa. Then the fibers are evenly arranged on the rollers. Each group of rollers includes 5 rollers. The distance between the roller groups is 0.5m. The tension between the rollers is maintained at 0.3cN / dtex. After being arranged by two groups of rollers, the finished raw silk with uniform wire width is formed.

[0091] Before sizing, the washed carbonized raw silk is evenly arranged on the rollers. Each group of rollers includes 5 rollers. The distance between the roller groups is 0.5m. The tension between the rollers is maintained at 0.3cN / dtex. After being arranged by two groups of rollers, a fiber bundle with uniform wire width is formed.

[0092] After sizing and drying, the washed carbonized raw silk is evenly arranged on the rollers. Each group of rollers includes 5 roller rollers. The first roller roller of each group of rollers is a flower roller. The distance between the roller groups is 1m. The tension between the rollers is maintained at 0.3cN / dtex. After being arranged by two groups of roller rollers, a fiber bundle with uniform wire width is formed. The effective width of all guide wheels during the carbon fiber winding process is 1.5 times the wire width.

[0093] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0094] The present invention controls the carbon fiber production process to form carbon fiber with good spreadability and suitable for prepreg, which is beneficial to the production of prepreg.

[0095] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing carbon fiber suitable for prepreg production, characterized in that: The following steps are involved: S1. Preliminary steps: The spinning solution is used to prepare the filaments, and the filaments are prepared through multiple preparation steps to obtain the finished raw filaments; S2, pre-oxidation: The finished raw silk is oxidized in an environment of 200-300°C. Before the finished raw silk enters the pre-oxidation process, the single filaments of the tow are opened with an air pressure of 0.05-0.30MPa. After that, the opened finished raw silk is evenly arranged on the roller. After being arranged by more than two groups of rollers, the finished raw silk with uniform wire width is formed. S3, low temperature carbonization: The finished raw silk with uniform wire width is subjected to low-temperature carbonization treatment in an environment of 300 to 800° C. to obtain a first carbonized raw silk; S4, high temperature carbonization: Placing the first carbonized precursor in an environment of 1000-1600° C. for high-temperature carbonization treatment to obtain a second carbonized precursor; S5. Surface treatment: Applying a constant current to the second carbonized precursor in an electrolytic solution for surface treatment, and then washing the second carbonized precursor with water to obtain a washed carbonized precursor; S6. Sizing: Before sizing, the washed carbonized raw silk is first arranged to form a bundle of uniform wire width, and then immersed in a sizing tank for sizing; After sizing, the washed carbonized raw silk is dried, and the washed carbonized raw silk after drying is subjected to a second finishing. After finishing by more than two groups of rollers, the wire width is controlled according to actual requirements to form a fiber bundle with uniform wire width; S7, Carbon fiber winding: The fiber bundles are collected by a winder to obtain finished carbon fibers.

2. The method for preparing carbon fiber suitable for prepreg production according to claim 1, characterized in that: The specific steps of step S1 are: S1.1、Aggregation: Acrylonitrile and comonomer are polymerized in a dimethyl sulfoxide solution to obtain a polymerization solution; S1.2, single and bubble removal: Under vacuum conditions, the residual acrylonitrile monomer in the polymerization solution is separated from the system to separate the monomer, and the mixed gas in the polymerization solution is removed to eliminate bubbles, thereby obtaining a spinning solution; S1.3, solidification molding: The spinning solution enters the coagulation liquid in the form of filaments and coagulates to obtain coagulated filaments; S1.4, washing: The coagulated filaments are washed by water using a flower roller beating method, the direction of the washing water flow is countercurrent, the water temperature of the washing water is controlled at 30-70° C., and the tension of the filament bundle during the washing process ranges from 1.0 to 3.5 cN / dtex, thereby obtaining the first filaments; S1.5, hot water drawing: The first filament is placed in hot water and stretched by 1.2 to 4 times to obtain a second filament; S1.6, Oiling and drying densification: The second wire strips are evenly arranged on the rollers, and the wire width is controlled according to actual requirements to obtain a third wire strip with even wire width; The third wire is oiled with silicone oil, and the oiled third wire is dried and densified, and then the third wire is opened with compressed air to obtain a fourth wire; S1.7, Steam drawing: Using saturated steam to draw the fourth filament by 1.5 to 6 times to obtain a fifth filament; S1.8, Heat setting: heat setting the fifth filament using saturated steam; S1.9, Raw silk collection: The fifth silk strips that have undergone the heat setting step are collected to obtain finished raw silk.

3. The method for preparing carbon fiber suitable for prepreg production according to claim 2, characterized in that: The comonomer is one or more combinations of methyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, acrylamide, itaconic acid, ammonium itaconate, and isobutyl methacrylate.

4. The method for preparing carbon fiber suitable for prepreg production according to claim 2, characterized in that: The specific steps of step S1.3 are: the spinning solution is output through the spinning metering pump, flows through the buffer, enters the spinneret assembly and is ejected, adopts a wet spinning process or a dry-wet spinning process, enters the coagulation liquid for coagulation and forming, and obtains coagulated filaments.

5. The method for preparing carbon fiber suitable for prepreg production according to claim 2, characterized in that: In the step S1.6, the roller includes rollers, and the number of the rollers is not less than 3; The first roller of each group of rollers is a flower roller, the distance between roller groups is not less than 0.5m, and the tension between rollers is maintained at less than 0.5cN / dtex.

6. A method for preparing carbon fiber suitable for prepreg production according to claim 2 or 5, characterized in that: The silicone oil is one of modified silicone oil or non-silicone oil; The temperature of the drying and densification treatment is 100-190°C; The air pressure used to open the third monofilament is 0.05 to 0.30 MPa.

7. The method for preparing carbon fiber suitable for prepreg production according to claim 1, characterized in that: In step S2, each group of rollers includes no less than 5 roller rollers, the distance between the rollers in each group is no less than 0.5m, and the tension between the rollers is less than 0.5cN / dtex.

8. The method for preparing carbon fiber suitable for prepreg production according to claim 1, characterized in that: In step S6, during the first finishing, each group of rollers includes no less than 5 roller rollers, the distance between each group of rollers is not less than 0.5m, the tension between the rollers is less than 0.5cN / dtex, and the washed carbonized precursor is finished by at least 2 groups of rollers.

9. The method for preparing carbon fiber suitable for prepreg production according to claim 1, characterized in that: In the step S6, during the second finishing, the washed carbonized raw silk after drying is evenly arranged on the rollers, each group of rollers includes no less than 3 roller rollers, the first roller roller of each group of rollers is a flower roller, the distance between each group of rollers is no less than 1m, and the tension between the rollers is less than 0.5cN / dtex.

10. The method for preparing carbon fiber suitable for prepreg production according to claim 1, characterized in that: In the step S7, a winder is used to collect the fiber bundle, and the effective width of the guide wheel of the winder is not less than 1 to 2 times the width of the fiber bundle.

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