A method of manufacturing and apparatus for manufacturing short cut carbon fibers

Abstract

The application provides a preparation method and manufacturing device of chopped carbon fibers, and belongs to the technical field of chopped carbon fiber manufacturing. The preparation method of the chopped carbon fibers comprises the following steps: providing a continuous finished carbon fiber bundle, the surface of the carbon fiber bundle being a thermosetting coating; sequentially performing twisting treatment, degumming treatment, sizing treatment, pre-drying treatment, slitting treatment and drying treatment on the carbon fiber bundle to obtain the chopped carbon fibers; and in the sizing treatment step, the sizing agent is a thermoplastic resin. The chopped carbon fibers prepared by the method can resist high temperature and can be firmly combined with a thermoplastic matrix material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of short carbon fiber manufacturing, in particular to a preparation method and manufacturing device of short carbon fiber. BACKGROUND

[0002] Carbon fiber reinforced thermoplastic composite (CFRTP) has the advantages of good toughness, fatigue resistance, high temperature resistance, short molding cycle and easy recycling and reuse, and is widely used in aerospace, military, automobile, sports products and other fields. From the reinforcement method, CFRTP is divided into long carbon fiber reinforced thermoplastic composite, short carbon fiber reinforced thermoplastic composite and continuous carbon fiber reinforced composite. Among them, the short carbon fiber is a carbon fiber filament bundle with high strength and high modulus, which is cut into a specified length after being bundled. Compared with carbon fiber filaments, short carbon fibers have the advantage of more uniform distribution in the matrix material. At the same time, short carbon fibers also have the advantages of high mechanical strength and small density. However, the short carbon fibers prepared by the existing preparation process have the problems of not being resistant to high temperature and being difficult to firmly combine with the thermoplastic matrix material, which affects the application and promotion of short carbon fibers. SUMMARY

[0003] The purpose of the present application is to provide a preparation method and manufacturing device of short carbon fiber, which can be resistant to high temperature and firmly combined with the thermoplastic matrix material.

[0004] The embodiments of the present application are implemented as follows:

[0005] In a first aspect, the embodiments of the present application provide a preparation method of short carbon fiber, comprising the following steps: providing a continuous finished carbon fiber bundle, the surface of the carbon fiber bundle being a thermosetting coating; sequentially performing twisting treatment, degumming treatment, sizing treatment, pre-drying treatment, slitting treatment and drying treatment on the carbon fiber bundle to obtain short carbon fiber; wherein in the sizing treatment step, the sizing agent is a thermoplastic resin.

[0006] At present, the surface of the commercially available carbon fiber bundle is generally a thermosetting coating (i.e. formed after the epoxy resin sizing agent is coated and cured), and the chopped carbon fiber is cut from the corresponding commercially available carbon fiber bundle. On the one hand, the coating formed by the epoxy resin sizing agent is not resistant to high temperature, which makes the corresponding chopped carbon fiber difficult to meet the high-temperature processing requirements; on the other hand, the coating formed by the epoxy resin sizing agent can be stably combined with the epoxy resin matrix, but it is difficult to be stably combined with the thermoplastic resin matrix. In the present application, the researchers first remove the epoxy resin thermosetting coating on the surface of the carbon fiber material after the twisting treatment, and then reapply a thermoplastic coating on the surface of the carbon fiber material through the sizing treatment. The chopped carbon fiber prepared by the preparation method can withstand high temperature and can be firmly combined with the thermoplastic matrix material.

[0007] In some optional embodiments, the step of removing the sizing agent includes: immersing the twisted carbon fiber bundle in a sizing remover, the sizing remover including acetone; or, subjecting the twisted carbon fiber bundle to heat treatment in a pyrolysis furnace, the temperature of the heat treatment being 250-450°C.

[0008] In the above technical solution, the epoxy resin thermosetting coating on the surface of the carbon fiber material can be effectively removed by immersing the carbon fiber bundle in a sizing remover or by heat treatment in a pyrolysis furnace. The composition of the sizing remover and the temperature of the heat treatment are limited, which helps to improve the sizing removal effect.

[0009] In some optional embodiments, the sizing remover includes acetone and dichloromethane.

[0010] Optionally, the volume ratio of acetone to dichloromethane is (2-4):1.

[0011] In the above technical solution, the mixture of acetone and dichloromethane as a sizing remover can achieve better sizing removal effect.

[0012] Further, the volume ratio of acetone to dichloromethane is limited in a specific range, which helps to improve the sizing removal effect of the sizing remover.

[0013] In some optional embodiments, the temperature of the heat treatment is 300-400°C.

[0014] In the above technical solution, the temperature of the heat treatment is further limited in a more excellent range, which can achieve better sizing removal effect in the process of pyrolysis sizing removal.

[0015] In some optional embodiments, the solid content of the sizing agent is 1-10%.

[0016] Optionally, the solid content of the sizing agent is 4-8%.

[0017] In the technical solution, the solid content of the sizing agent is limited in a specific range, so that a good bundling effect can be achieved, and a thermoplastic coating with appropriate thickness and good thickness uniformity can be obtained after curing.

[0018] In some optional embodiments, the twisting specification in the step of the twisting treatment is 10-50 / m.

[0019] Optionally, the twisting specification in the step of the twisting treatment is 20-40 / m.

[0020] In the technical solution, the twisting specification is gradually limited in a specific range, which helps the degreasing agent and the sizing agent to infiltrate the carbon fiber bundle, so that a good degreasing effect and a good sizing effect can be achieved, and a good bundling effect can also be achieved.

[0021] In some optional embodiments, the slitting mode in the step of the slitting treatment is gantry type or rotary type.

[0022] Optionally, the slitting mode is gantry type.

[0023] Optionally, the slitting speed is 0.1-2 m / min.

[0024] In the technical solution, the gantry type or the rotary type slitting mode can achieve a good slitting effect, and the gantry type slitting mode can achieve a better slitting effect than the rotary type slitting mode.

[0025] Further, the slitting speed is controlled in a specific range, so that the corresponding production line has an appropriate production rate, and each process has a relatively appropriate processing time, so that the short carbon fibers with better quality can be obtained.

[0026] In some optional embodiments, in the step of the pre-drying treatment, the pre-drying equipment is a steam heating type drying roller, and the treatment temperature is 100-250℃ and the treatment pressure is 0.3-0.6 MPa.

[0027] Optionally, the treatment temperature is 180-220℃ and the treatment pressure is 0.5-0.6 MPa.

[0028] In the technical solution, the treatment temperature and the treatment pressure in the pre-drying treatment are gradually limited in a specific range, so that the slurry on the surface of the carbon fiber bundle has an appropriate curing degree after pre-drying, which facilitates the subsequent slitting treatment and also enables the short carbon fibers with high quality to be obtained (a lower curing degree, the coating is easy to adhere to the slitting equipment during slitting, which affects the slitting efficiency and slitting effect; a higher curing degree, the coating is easy to break during slitting, which reduces the product yield).

[0029] In some optional embodiments, in the step of drying treatment, the drying equipment is a tunnel pyrolysis furnace, and the treatment temperature is 200-300°C, and the conveying speed is 0.1-5m / min.

[0030] Optionally, the treatment temperature is 250-300°C, and the conveying speed is 0.5-2m / min.

[0031] In the above technical solution, the treatment temperature and the conveying speed in the drying treatment are gradually limited in a specific range, so as to provide more suitable drying conditions, thereby achieving better drying effect.

[0032] In the second aspect, the embodiments of the present application provide a short carbon fiber manufacturing device, which is suitable for the preparation method provided in the first aspect, and includes, along the conveying direction of the carbon fiber bundle, a yarn withdrawing frame, a degumming groove or a pyrolysis furnace, a sizing groove, a drying roller, a slitting machine and a drying furnace arranged in sequence.

[0033] In the above technical solution, the short carbon fiber manufacturing device in a specific form can be combined with the preparation method provided in the first aspect to prepare the short carbon fiber which is resistant to high temperature and can be firmly combined with the thermoplastic matrix material. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0035] Figure 1 A process flow chart of a short carbon fiber preparation method provided in the embodiments of the present application;

[0036] Figure 2 A structure schematic diagram of a short carbon fiber manufacturing device provided in the embodiments of the present application.

[0037] Figure legend: 10-short carbon fiber manufacturing device; 100-yarn withdrawing frame; 200-pyrolysis furnace; 300-sizing groove; 400-drying roller; 500-slitting machine; 600-drying furnace; 700-vibrating screen. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are adopted. If the manufacturers of the reagents or instruments are not specified, the conventional products that can be purchased in the market are adopted.

[0039] It should be noted that "and / or" in the present application, such as "feature 1 and / or feature 2", means "feature 1" alone, "feature 2" alone, or "feature 1" plus "feature 2".

[0040] In addition, in the description of the present application, unless otherwise specified, the meaning of "multiple" in "one or more" is two or more; the range of "value a ~ value b" includes both end values "a" and "b", and "unit of measurement" in "value a ~ value b + unit of measurement" represents the "unit of measurement" of both "value a" and "value b".

[0041] The preparation method and manufacturing device of the short carbon fiber in the embodiments of the present application will be described in detail below.

[0042] In a first aspect, the embodiments of the present application provide a preparation method of a short carbon fiber, comprising the following steps: providing a continuous finished carbon fiber bundle, the surface of the carbon fiber bundle being a thermosetting coating; sequentially performing twisting treatment, degumming treatment, sizing treatment, pre-drying treatment, slitting treatment and drying treatment on the carbon fiber bundle to obtain a short carbon fiber; wherein in the sizing treatment step, the sizing agent is a thermoplastic resin.

[0043] At present, the surface of the commercially available carbon fiber bundle is usually a thermosetting coating (i.e. formed after the epoxy resin sizing agent is coated and cured), and the short carbon fiber is obtained by slitting the corresponding commercially available carbon fiber bundle. On the one hand, the coating formed by the epoxy resin sizing agent is not resistant to high temperature, which makes it difficult for the corresponding short carbon fiber to meet the high temperature processing requirements; on the other hand, although the coating formed by the epoxy resin sizing agent can be stably combined with the epoxy resin matrix, it is difficult to be stably combined with the thermoplastic resin matrix. In the present application, the researchers first perform degumming treatment on the carbon fiber bundle after the twisting treatment to remove the epoxy resin thermosetting coating on the surface of the carbon fiber material, and then reapply a thermoplastic coating on the surface of the carbon fiber material through sizing treatment. The short carbon fiber prepared by the preparation method can withstand high temperature and can be firmly combined with the thermoplastic matrix material.

[0044] It should be noted that the type of finished carbon fiber bundle is not limited, and the mainstream commercially available type of carbon fiber bundle can be selected, as long as the coating on the surface thereof is a thermosetting coating, such as T700-12K.

[0045] It should be noted that the current preparation process of the short carbon fiber usually also uses waste silk or tail yarn as the raw material, and the short carbon fiber prepared by the embodiment of the present application also has the properties of continuous defect-free and more excellent mechanical properties.

[0046] It should be noted that the specific type of thermoplastic resin is not limited, and can be set according to conventional selection in the art, for example, polyimide or polyaryletherketone.

[0047] As an example, the step of degumming treatment includes: placing the twisted carbon fiber bundle after the twisting treatment in a degumming agent for soaking, the degumming agent including acetone; or placing the twisted carbon fiber bundle after the twisting treatment in a pyrolysis furnace for heat treatment, the temperature of the heat treatment being 250-450℃, for example, but not limited to, any one point value or a range value between any two of 250℃, 300℃, 350℃, 400℃ and 450℃.

[0048] In this embodiment, both soaking the carbon fiber bundle in a degumming agent or heat treatment in a pyrolysis furnace can effectively remove the epoxy resin-based thermosetting coating on the surface of the carbon fiber material, wherein limiting the composition of the degumming agent and limiting the temperature of the heat treatment both help to improve the degumming effect.

[0049] As an example, the degumming agent includes acetone and dichloromethane.

[0050] In this embodiment, using a mixture of acetone and dichloromethane as a degumming agent can achieve better degumming effect.

[0051] As an example, the volume ratio of acetone and dichloromethane is (2-4):1, for example, but not limited to, any one point value or a range value between any two of 2:1, 2.5:1, 3:1, 3.5:1 and 4:1.

[0052] In this embodiment, the volume ratio of acetone and dichloromethane is further limited in a specific range, which is more helpful to improve the degumming effect of the degumming agent.

[0053] As an example, the temperature of the heat treatment is 300-400℃, for example, but not limited to, any one point value or a range value between any two of 300℃, 320℃, 340℃, 360℃, 380℃ and 400℃.

[0054] In this embodiment, the temperature of the heat treatment is further limited in a more excellent range, which can achieve better degumming effect in the process of pyrolysis degumming.

[0055] As an example, the sizing agent has a solid content of 1-10%, for example but not limited to any one of the point values of 1%, 2%, 4%, 6%, 8%, and 10% or a range value between any two of them.

[0056] As an example, the sizing agent has a solid content of 4-8%, for example but not limited to any one of the point values of 4%, 5%, 6%, 7%, and 8% or a range value between any two of them.

[0057] In this embodiment, the solid content of the sizing agent is limited to a specific range, which can achieve a better bundling effect, and at the same time, a thermoplastic coating with a suitable thickness and good thickness uniformity can be obtained after curing.

[0058] As an example, in the twisting step, the twisting specification is 10-50 / m, for example but not limited to any one of the point values of 10 / m, 20 / m, 30 / m, 40 / m, and 50 / m or a range value between any two of them.

[0059] As an example, in the twisting step, the twisting specification is 20-40 / m, for example but not limited to any one of the point values of 10 / m, 15 / m, 20 / m, 25 / m, 30 / m, 35 / m, and 40 / m or a range value between any two of them.

[0060] In this embodiment, the twisting specification is gradually limited to a specific range, which helps the degreasing agent and the sizing agent to infiltrate the carbon fiber bundle, thereby achieving a better degreasing effect and sizing effect, and at the same time, a better bundling effect can be achieved.

[0061] As an example, in the slitting step, the slitting method is gantry type or rotary type.

[0062] As an example, the slitting method is gantry type.

[0063] In this embodiment, both the gantry type and the rotary type slitting methods can achieve a better slitting effect, and the gantry type slitting method can achieve a better slitting effect than the rotary type slitting method.

[0064] As an example, the slitting speed is 0.1-2 m / min, for example but not limited to any one of the point values of 0.1 m / min, 0.5 m / min, 1 m / min, 1.5 m / min, and 2 m / min or a range value between any two of them.

[0065] It should be noted that, generally, the twisting treatment, the degumming treatment, the sizing treatment, the pre-drying treatment and the slitting treatment are in the same production line, so the slitting speed also determines the processing speed of the front-end process.

[0066] In this embodiment, further controlling the slitting speed in a specific range can enable the corresponding production line to have a suitable production rate, and thus each process section has a more suitable processing time, so as to obtain short carbon fibers with better quality.

[0067] As an example, in the pre-drying treatment step, the pre-drying equipment is a steam-heated drying roller, and the treatment temperature is 100-250°C, such as but not limited to any one of the point values of 100°C, 150°C, 200°C and 250°C or a range value between any two of them; the treatment pressure is 0.3-0.6 MPa, such as but not limited to any one of the point values of 0.3 MPa, 0.4 MPa, 0.5 MPa and 0.6 MPa or a range value between any two of them.

[0068] As an example, the treatment temperature is 180-220°C, such as but not limited to any one of the point values of 180°C, 190°C, 200°C, 210°C and 220°C or a range value between any two of them; the treatment pressure is 0.5-0.6 MPa, such as but not limited to any one of the point values of 0.52 MPa, 0.54 MPa, 0.56 MPa, 0.58 MPa and 0.6 MPa or a range value between any two of them.

[0069] In this embodiment, the treatment temperature and the treatment pressure in the pre-drying treatment are gradually limited in a specific range, so that the sizing on the surface of the carbon fiber bundle has a suitable curing degree after pre-drying, thereby facilitating subsequent slitting treatment and obtaining short carbon fibers with higher quality (a lower curing degree, the coating is easy to adhere to the slitting equipment during slitting, affecting the slitting efficiency and slitting effect; a higher curing degree, the coating is easy to break during slitting, resulting in a lower product yield).

[0070] As an example, in the drying treatment step, the drying equipment is a tunnel-type pyrolysis furnace, and the treatment temperature is 200-300°C, such as but not limited to any one of the point values of 200°C, 220°C, 240°C, 260°C, 280°C and 300°C or a range value between any two of them; the conveying speed is 0.1-5 m / min, such as but not limited to any one of the point values of 0.1 m / min, 0.5 m / min, 1 m / min, 2 m / min, 3 m / min, 4 m / min and 5 m / min or a range value between any two of them.

[0071] As an example, the processing temperature is 250-300℃, for example but not limited to any one of the point values of 250℃, 260℃, 270℃, 280℃, 290℃ and 300℃ or a range value between any two of them; the conveying speed is 0.5-2 m / min, for example but not limited to any one of the point values of 0.5 m / min, 1 m / min, 1.5 m / min and 2 m / min or a range value between any two of them.

[0072] In this embodiment, the processing temperature and the conveying speed in the drying treatment are gradually limited in a specific range to provide more suitable drying conditions, thereby achieving a better drying effect.

[0073] It should be noted that the processes or steps not specially mentioned or limited in the preparation process of the chopped carbon fibers can be set according to the conventional selection in the art.

[0074] As an example, in the slitting process, the length of the chopped carbon fibers after slitting is 2-10 mm, the bulk density of the chopped carbon fibers is greater than 400 g / L, and the profile shape of the chopped carbon fibers is flat or columnar.

[0075] As an example, the process flow chart of the preparation method of the chopped carbon fibers is exemplarily shown in Figure 1 .

[0076] Referring to Figure 2 , in a second aspect, the present application provides a manufacturing device 10 of chopped carbon fibers, which is suitable for the preparation method provided in the first aspect, and includes, along the conveying direction of the carbon fiber bundle, a yarn withdrawing frame 100, a degumming groove or pyrolysis furnace 200, a sizing groove 300, a drying roller 400, a slitting machine 500 and a drying furnace 600 arranged in sequence.

[0077] In the present application, the manufacturing device 10 of the chopped carbon fibers in a specific form can be combined with the preparation method provided in the first aspect to prepare the chopped carbon fibers which are resistant to high temperature and can be firmly combined with the thermoplastic matrix material. Among them, the yarn withdrawing frame 100 is used for twisting treatment, the degumming groove or pyrolysis furnace 200 is used for degumming treatment, the sizing groove 300 is used for sizing treatment, the drying roller 400 is used for pre-drying treatment, the slitting machine 500 is used for slitting treatment, and the drying furnace 600 is used for drying treatment.

[0078] It should be noted that since each device in the manufacturing device of the chopped carbon fibers is a common device type in the art, the present application does not further introduce the device, which can be set according to the conventional form in the art.

[0079] As an example, downstream of the drying furnace along the conveying direction of the carbon fiber bundle further comprises a vibrating screen 700, the vibrating screen 700 is a linear vibrating screen with three outlets, and the length is 1.5-2 m.

[0080] In this embodiment, the vibrating screen 700 is provided to improve the specification consistency of the chopped carbon fiber.

[0081] As an example, the length of the sizing tank 300 is 0.8-1.2 m, and the conveying roller in the sizing tank has a groove for accommodating the carbon fiber bundle.

[0082] The features and performance of the present application are further described in detail below in conjunction with the embodiments.

[0083] Embodiment 1

[0084] The present application provides a preparation method of chopped carbon fiber, comprising the following steps:

[0085] A continuous finished carbon fiber bundle is provided, the surface of the carbon fiber bundle is a thermosetting coating, and the specific model of the finished carbon fiber bundle is T700-12K; the carbon fiber bundle is sequentially subjected to twisting treatment, degumming treatment, sizing treatment, pre-drying treatment, slitting treatment, drying treatment, and vibrating screen treatment to obtain chopped carbon fiber.

[0086] Specifically, in the step of twisting treatment, the twisting specification is 25 / m; in the step of degumming treatment, the degumming agent is soaked in the degumming tank, the degumming agent is a mixed system of acetone and dichloromethane, and the volume ratio of the two is 3:1; in the step of sizing treatment, the sizing agent is a polyimide thermoplastic resin, and the solid content of the sizing agent is 6%; in the step of pre-drying treatment, the pre-drying equipment is a steam heating type drying roller, the treatment temperature is 200°C, and the treatment pressure is 0.5 MPa; in the step of drying treatment, the drying equipment is a tunnel type pyrolysis furnace, the treatment temperature is 250°C, and the conveying speed is 2.5 m / min; in the step of slitting treatment, the slitting method is a gantry type, and the slitting speed is 0.1-2 m / min.

[0087] Embodiment 2

[0088] The present application provides a preparation method of chopped carbon fiber, which is only different from embodiment 1 in that in the step of degumming treatment, heat treatment is performed in a pyrolysis furnace, and the temperature of the heat treatment is 350°C.

[0089] Embodiment 3

[0090] The present application provides a preparation method of chopped carbon fiber, which is only different from embodiment 1 in that the degumming agent is only acetone.

[0091] Embodiment 4

[0092] The embodiment of the present application provides a preparation method of short carbon fibers, which is only different from the embodiment 1 that the degreasing agent is only dichloromethane.

[0093] Embodiment 5

[0094] The embodiment of the present application provides a preparation method of short carbon fibers, which is only different from the embodiment 1 that the degreasing agent is a mixed system of acetone and dichloromethane, and the volume ratio of the two is 2:1.

[0095] Embodiment 6

[0096] The embodiment of the present application provides a preparation method of short carbon fibers, which is only different from the embodiment 1 that the degreasing agent is a mixed system of acetone and dichloromethane, and the volume ratio of the two is 4:1.

[0097] Embodiment 7

[0098] The embodiment of the present application provides a preparation method of short carbon fibers, which is only different from the embodiment 1 that the degreasing agent is a mixed system of acetone and dichloromethane, and the volume ratio of the two is 1:1.

[0099] Embodiment 8

[0100] The embodiment of the present application provides a preparation method of short carbon fibers, which is only different from the embodiment 1 that the degreasing agent is a mixed system of acetone and dichloromethane, and the volume ratio of the two is 5:1.

[0101] Embodiment 9

[0102] The embodiment of the present application provides a preparation method of short carbon fibers, which is only different from the embodiment 2 that in the step of degreasing treatment, heat treatment is performed in a pyrolysis furnace, and the temperature of the heat treatment is 300 DEG C.

[0103] Embodiment 10

[0104] The embodiment of the present application provides a preparation method of short carbon fibers, which is only different from the embodiment 2 that in the step of degreasing treatment, heat treatment is performed in a pyrolysis furnace, and the temperature of the heat treatment is 400 DEG C.

[0105] Embodiment 11

[0106] The embodiment of the present application provides a preparation method of short carbon fibers, which is only different from the embodiment 2 that in the step of degreasing treatment, heat treatment is performed in a pyrolysis furnace, and the temperature of the heat treatment is 250 DEG C.

[0107] Embodiment 12

[0108] The embodiment of the present application provides a preparation method of short carbon fibers, which is only different from the embodiment 2 in that the heat treatment is performed in a pyrolysis furnace in the step of glue removal treatment, and the temperature of the heat treatment is 450 DEG C.

[0109] Comparative example 1

[0110] The comparative example of the present application provides a preparation method of short carbon fibers, which is only different from the embodiment 1 in that the glue removal treatment is not performed.

[0111] Test example

[0112] Performance test of short carbon fibers

[0113] Test method:

[0114] The short carbon fibers prepared in the embodiment 1 to 12 and the comparative example 1 are numbered respectively, then each sample is compounded with a bismaleimide thermoplastic resin matrix, and then the interlaminar interface bonding strength of the composite at room temperature and the interface bonding strength after high-temperature treatment (treatment at 180 DEG C for 48h) are tested, specifically, the interlaminar shear strength is determined according to JC / T 773-2010 and GB / T 30969.

[0115] Table 1 is a performance statistical table of each sample

[0116]

[0117] Referring to Table 1, the test results of the embodiment 1 to 12 and the comparative example 1 show that, after the twisting treatment, the carbon fiber bundle is first subjected to the glue removal treatment to remove the epoxy resin type thermosetting coating on the surface of the carbon fiber material, and then the thermoplastic coating is re-applied on the surface of the carbon fiber material through the glue application treatment, compared with the glue application treatment directly after the twisting treatment, the short carbon fiber reinforced thermoplastic composite corresponding to the former has more excellent interlaminar interface bonding strength at room temperature and after high-temperature treatment, that is, has more excellent high-temperature resistance.

[0118] The test results of the embodiment 1 and the embodiment 3 to 8 show that, compared with using a single glue removal agent or not limiting the volume ratio of the two within a specific range, the short carbon fiber reinforced thermoplastic composite corresponding to the former has more excellent interlaminar interface bonding strength at room temperature and after high-temperature treatment, that is, has more excellent high-temperature resistance.

[0119] From the test results of Example 2 and Examples 9-12, it can be seen that, in the step of removing the adhesive by using a pyrolysis furnace, limiting the temperature of the heat treatment in a specific range, compared with not limiting the treatment temperature in a specific range, the short-cut carbon fiber reinforced thermoplastic composite material corresponding to the former has more excellent interlaminar interface bonding strength at room temperature and after high temperature treatment, that is, has more excellent high temperature resistance.

[0120] The above-described examples are part of the examples of the present application, rather than all the examples. The detailed description of the examples of the present application is not intended to limit the scope of the claimed application, but only represents selected examples of the present application. Based on the examples in the present application, all other examples obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application.

Claims

1. A method for preparing short-cut carbon fibers, characterized in that, Includes the following steps: A continuous finished carbon fiber bundle is provided, the surface of which is a thermosetting coating; The carbon fiber bundle is subjected to twisting, degumming, sizing, pre-drying, slitting and drying processes in sequence to obtain short-cut carbon fibers; wherein, in the sizing process, the sizing agent is a thermoplastic resin. The degumming process includes: immersing the twisted carbon fiber bundle in a degumming agent, the degumming agent comprising acetone and dichloromethane; the volume ratio of acetone to dichloromethane is (2~4):

1.

2. The preparation method according to claim 1, characterized in that, The solid content of the sizing agent is 1-10%.

3. The preparation method according to claim 2, characterized in that, The solid content of the sizing agent is 4-8%.

4. The preparation method according to any one of claims 1 to 3, characterized in that, In the twisting process, the twisting specification is 10~50 strands / m.

5. The preparation method according to claim 4, characterized in that, In the twisting process, the twisting specification is 20~40 strands / m.

6. The preparation method according to any one of claims 1 to 3, characterized in that, In the slitting process, the slitting method is either gantry-type or rotary-type.

7. The preparation method according to claim 6, characterized in that, The cutting method is gantry type.

8. The preparation method according to claim 6, characterized in that, The slitting speed is 0.1~2 m / min.

9. The preparation method according to any one of claims 1 to 3, characterized in that, In the pre-drying process, the pre-drying equipment is a steam-heated drying roller, and the processing temperature is 100~250℃, and the processing pressure is 0.3~0.6 MPa.

10. The preparation method according to claim 9, characterized in that, The processing temperature is 180~220℃, and the processing pressure is 0.5~0.6 MPa.

11. The preparation method according to any one of claims 1 to 3, characterized in that, In the drying process, the drying equipment is a tunnel pyrolysis furnace, the processing temperature is 200~300℃, and the conveying speed is 0.1~5 m / min.

12. The preparation method according to claim 11, characterized in that, The processing temperature is 250~300℃, and the conveying speed is 0.5~2 m / min.

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