Sizing agent for carbon fibers, sizing method for carbon fibers, carbon fibers, and thermoplastic resin carbon fiber composite material

Abstract

The invention provides a sizing agent for carbon fibers, a sizing method of the carbon fibers, the carbon fibers and a thermoplastic resin carbon fiber composite material. The sizing agent for the carbon fibers comprises polysilazane and a diluent, wherein the content of the polysilazane is 0.01 to 5 weight percent. The sizing agent for the carbon fiber contains the polychlorosilane, so that the sizing agent not only can uniformly cover the surface of the fiber and prevent the fiber from being broken, but also has excellent heat resistance, the degradation temperature exceeds 800 DEG C, and the processing temperature requirement of a high-performance thermoplastic resin-based carbon fiber reinforced composite material is far met; the problem that an existing common sizing agent cannot be used for a high-temperature-resistant thermoplastic resin-based composite material is effectively solved, and the situation that the interfacial strength of resin and carbon fibers is greatly reduced due to the fact that defects are increased due to decomposition of the sizing agent in the processing process of high-performance thermoplastic resin can be avoided.

Description

Technical Field

[0001] The invention relates to the technical field of carbon fiber preparation, and in particular to a sizing agent for carbon fiber, a carbon fiber sizing method, carbon fiber and a thermoplastic resin carbon fiber composite material. Background Art

[0002] High-performance thermoplastic resin-based carbon fiber composites have been widely used in aviation, aerospace, transportation, new energy and other fields due to their high specific strength, corrosion resistance, high chemical stability, strong designability, short molding cycle and ability to be recycled and reused. They are also key strategic materials for the future development of my country's high-end manufacturing industry. However, due to the highly graphitized structure of carbon fiber itself, the surface is smooth and chemically inert, while the molecular chain of high-performance thermoplastic resin is long and chemically stable, resulting in poor adhesion between carbon fiber and thermoplastic resin matrix, affecting the mechanical properties of thermoplastic resin-based carbon fiber composites.

[0003] The carbon fiber sizing agent can act as a bridge, connecting the carbon fiber and the high-performance thermoplastic resin, effectively transferring the load, thereby enhancing the interfacial bonding between the two, maximizing the excellent performance of the carbon fiber and the high-performance thermoplastic resin, and obtaining a high-performance thermoplastic resin-based carbon fiber composite material with high mechanical strength. In addition, due to its own brittleness during the production, spinning and transportation of carbon fiber, single filament breakage and hairiness are prone to occur. Therefore, in actual production, the fiber is usually sizing to suppress these defects.

[0004] At present, most carbon fiber products use thermosetting sizing agents. When used, thermosetting sizing agents will degrade when the temperature exceeds 250°C. However, the processing temperature of high-performance thermoplastic resins is generally 280-420°C, so thermosetting sizing agents will form defects in the molding of high-performance thermoplastic resin-based carbon fiber composites, seriously affecting the interface bonding between carbon fiber and thermoplastic resin, and greatly reducing the mechanical properties of the composite material. In addition, there is also an incompatibility problem between thermosetting sizing agents and high-performance thermoplastic resins. The degradation temperature of common thermoplastic sizing agents (180-250°C) is much lower than the processing temperature of high-performance thermoplastic resins (280-420°C). However, there are few reports on the research of high-temperature resistant carbon fiber sizing agents for high-performance thermoplastic resins.

[0005] Based on the above situation, in order to meet the higher processing temperature of thermoplastic resin-based fiber composites, it is necessary to develop a high-temperature resistant carbon fiber sizing agent suitable for high-performance thermoplastic resins. Summary of the invention

[0006] The main purpose of the present invention is to provide a sizing agent for carbon fiber, a sizing method for carbon fiber, and a carbon fiber and thermoplastic resin carbon fiber composite material to solve the problem that the heat resistance of the carbon fiber sizing agent in the prior art is difficult to meet the requirements of high-performance thermoplastic resin-based carbon fiber composite molding processing.

[0007] In order to achieve the above object, according to one aspect of the present invention, a sizing agent for carbon fiber is provided, which comprises: polysilazane and a diluent; wherein the content of polysilazane is 0.01-5wt%.

[0008] Further, the sizing agent also includes 0-0.5wt% of a silane coupling agent;

[0009] Preferably, the silane coupling agent is any one or more of KH550, KH560, KH570 and KH792;

[0010] Preferably, the content of polysilazane in the sizing agent is 0.1 wt% to 2 wt%, and the content of silane coupling agent is 0.005 wt% to 0.5 wt%.

[0011] Further, the diluent includes any one or more of acetone, acetate, tetrahydrofuran, xylene, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide;

[0012] The polysilazane contains Si-H bonds. Preferably, the polysilazane includes any one or more of KB-8801 resin and KB-8802 resin;

[0013] Preferably, the degradation temperature of the carbon fiber sizing agent is greater than or equal to 800°C.

[0014] In order to achieve the above object, according to one aspect of the present invention, a method for sizing carbon fiber is provided, the sizing method comprising: treating the carbon fiber with any one of the above-mentioned sizing agents for carbon fiber.

[0015] Furthermore, the sizing method comprises: desizing the carbon fiber, immersing the desizing carbon fiber in a sizing agent, and obtaining sized carbon fiber through drying and heat treatment.

[0016] Further, desizing includes: desizing the carbon fibers by treating them with an organic solvent or at a high temperature;

[0017] The impregnation includes: impregnating the desized carbon fiber in a sizing agent for 5 minutes to 5 hours;

[0018] Drying includes: treating the impregnated carbon fiber at a temperature of 150-250° C. for 0.5-5 hours;

[0019] The heat treatment includes: treating the dried carbon fiber at a temperature of 280-350° C. for 0.5-5 hours.

[0020] Furthermore, the desized carbon fiber is subjected to surface modification, wherein the surface modification includes introducing any one or more of hydroxyl groups, carboxyl groups, sulfonic acid groups, nitro groups and amino groups into the surface of the carbon fiber.

[0021] According to another aspect of the present invention, there is provided a carbon fiber, which is a carbon fiber treated by any one of the above-mentioned sizing methods.

[0022] According to another aspect of the present application, a thermoplastic resin carbon fiber composite material is provided. The thermoplastic resin carbon fiber composite material is made from the above-mentioned carbon fiber raw material.

[0023] Further, the raw material includes a thermoplastic resin, and the thermoplastic resin includes any one or more of polyetherketoneketone, polyetheretherketone, polyphenylene sulfide, polyimide, polyetherimide, polysulfone, polyarylate and nylon.

[0024] By applying the technical solution of the present invention, the sizing agent for carbon fiber contains polysilicon chloride, so that the sizing agent can not only evenly cover the surface of the fiber to prevent it from breaking, but also has excellent heat resistance, and the degradation temperature exceeds 800°C, which far meets the processing temperature requirements of high-performance thermoplastic resin-based carbon fiber reinforced composite materials, and effectively solves the problem that the currently commonly used sizing agents cannot be used for high-temperature resistant thermoplastic resin-based composite materials, and can avoid the situation in which the interface strength between the resin and the carbon fiber is greatly reduced due to the increase of defects caused by the decomposition of the sizing agent during the processing of the high-performance thermoplastic resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0026] Figure 1 Thermogravimetric curves of sized carbon fibers and unsized carbon fibers according to Example 1 of the present invention are shown;

[0027] Figure 2 The microscopic morphology of the carbon fiber after desizing according to Example 1 of the present invention is shown.

[0028] Figure 3 The microscopic morphology of carbon fibers after sizing with the sizing agent according to Example 1 of the present invention is shown. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0030] As analyzed in the background technology of this application, the high-performance thermoplastic resin-based carbon fiber composite materials in the prior art require higher processing temperatures, but the existing carbon fiber sizing agents will degrade at higher temperatures, resulting in defects in the thermoplastic resin-based carbon fiber composite materials and significantly reducing their mechanical properties. In order to solve this technical problem, this application provides a sizing agent for carbon fiber, a carbon fiber sizing method, carbon fiber, and a thermoplastic resin carbon fiber composite material.

[0031] According to a typical embodiment of the present application, a sizing agent for carbon fiber is provided, and the sizing agent for carbon fiber includes: polysilazane and a diluent; wherein the content of polysilazane is 0.01-5wt%.

[0032] The carbon fiber sizing agent of the present application contains polysiloxane, so that the sizing agent can not only evenly cover the surface of the fiber to prevent it from breaking, but also has excellent heat resistance, and the degradation temperature exceeds 800°C, which far meets the processing temperature requirements of high-performance thermoplastic resin-based carbon fiber reinforced composite materials, and effectively solves the problem that the currently commonly used sizing agents cannot be used for high-temperature resistant thermoplastic resin-based composite materials, and can avoid the situation in which the interface strength between the resin and the carbon fiber is greatly reduced due to the increase in defects caused by the decomposition of the sizing agent during the processing of the high-performance thermoplastic resin.

[0033] The content of polysilazane in the above-mentioned carbon fiber sizing agent can be any value in the range of 0.01-5wt%, such as 0.01wt%, 0.1wt%, 0.5wt%, 0.8wt%, 1wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2wt%, 2.3wt%, 2.5wt%, 2.7wt%, 3wt%, 3.2wt%, 3.5wt%, 3.8wt%, 4wt%, 4.2wt%, 4.5wt% or 5wt%, but is not limited thereto. Preferably, the content of polysilazane in the carbon fiber sizing agent is 0.1wt% to 2wt%.

[0034] In some embodiments of the present application, the above-mentioned polysilazane contains Si-H bonds and has good high temperature resistance. Moreover, the Si-H bonds can form hydrogen bonds with high-performance thermoplastic resins, thereby improving the wettability of carbon fibers and high-performance thermoplastic resins and improving the interface properties between the two, thereby improving the mechanical properties of high-performance thermoplastic resin-based carbon fiber composites.

[0035] In some embodiments of the present application, the polysilazane includes any one or more of KB-8801 resin and KB-8802 resin, wherein the chemical structural formulas of KB-8801 resin and KB-8802 resin are as follows:

[0036]

[0037] The above-mentioned commercialized polysilazane contains Si-H bonds, which can form hydrogen bonds with high-performance thermoplastic resins, improve the wettability of carbon fibers and high-performance thermoplastic resins, improve the interface properties between the two, and thus improve the mechanical properties of high-performance thermoplastic resin-based carbon fiber composites, and have good high temperature resistance.

[0038] The diluent in the carbon fiber sizing agent of the present application can be selected from the prior art, and the present application has no special requirements. For example, the diluent includes but is not limited to any one or more of acetone, acetate, tetrahydrofuran, xylene, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

[0039] In some typical embodiments of the present application, the above-mentioned carbon fiber sizing agent also includes 0-0.5wt% of a silane coupling agent, which can further improve the bonding ability between the sizing agent and the carbon fiber, thereby improving the mechanical properties of the material. Preferably, the silane coupling agent is any one or more of KH550, KH560, KH570 and KH792, which can increase the active groups on the surface of the carbon fiber and improve the bonding ability between the carbon fiber and the resin. Preferably, the content of the silane coupling agent in the sizing agent is 0.005wt% to 0.5wt%. For example, the content of the silane coupling agent in the sizing agent is 0.01wt%, 0.015wt%, 0.02wt%, 0.03wt%, 0.04wt%, 0.05wt%, 0.06wt%, 0.07wt%, 0.08wt%, 0.09wt%, 0.1wt%, 0.12wt%, 0.15wt%, 0.18wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt% and the like, but is not limited thereto.

[0040] In some preferred embodiments of the present application, the content of polysilazane in the sizing agent is 0.1 wt% to 2 wt%, and the content of silane coupling agent is 0.005 wt% to 0.5 wt%.

[0041] In some embodiments of the present application, in addition to the above-mentioned polysilazane and silane coupling agent, the balance of the sizing agent is a diluent.

[0042] In some embodiments of the present application, the degradation temperature of the carbon fiber sizing agent is greater than or equal to 800°C, which can meet the processing temperature requirements of various high-performance thermoplastic resin-based carbon fiber reinforced composite materials and prevent the increase of defects caused by the decomposition of the sizing agent, resulting in a significant decrease in the interface strength between the resin and the carbon fiber.

[0043] According to another typical embodiment of the present application, a carbon fiber sizing method is provided, the sizing method comprising: treating the carbon fiber with any one of the above-mentioned carbon fiber sizing agents.

[0044] The carbon fiber sizing method of the present application adopts the above-mentioned carbon fiber sizing agent to treat and size the carbon fiber. Since the carbon fiber sizing agent contains polysiloxane, the sizing agent can not only evenly cover the surface of the fiber to prevent it from breaking, but also has excellent heat resistance, and the degradation temperature exceeds 800°C, which far meets the processing temperature requirements of high-performance thermoplastic resin-based carbon fiber reinforced composite materials, and effectively solves the problem that the currently commonly used sizing agents cannot be used for high-temperature resistant thermoplastic resin-based composite materials, and can avoid the situation in which the interface strength between the resin and the carbon fiber is greatly reduced due to the increase of defects caused by the decomposition of the sizing agent during the processing of the high-performance thermoplastic resin.

[0045] In some typical embodiments of the present application, the sizing method includes: after desizing the carbon fiber, the desizing carbon fiber is immersed in a sizing agent, and the sizing carbon fiber is obtained by drying and heat treatment. The desizing treatment of the carbon fiber can remove the original sizing agent on the carbon fiber. Since the conventional sizing agent is composed of epoxy resin, rubber and other substances, it cannot withstand the high temperature of thermoplastic composite molding. Its presence will decompose and cause insufficient interface bonding, reducing the mechanical properties of the material; the desizing carbon fiber is immersed, dried and heat treated, the polysilazane resin is cured and a hydrophilic surface is formed on the surface of the polysilazane sizing agent, and the obtained carbon fiber has better interface bonding and high temperature resistance.

[0046] The method for desizing the carbon fiber can be selected from the prior art, and the present application has no limitation thereto. For example, the carbon fiber can be desizing by using an organic solvent treatment or a high temperature treatment, but is not limited to these methods.

[0047] In some embodiments of the present application, the impregnation includes: impregnating the desized carbon fiber in a sizing agent for 5 min-5 h, so that the sizing agent fully wets the fiber surface to form a uniform coating. Preferably, the carbon fiber is completely immersed in the sizing agent during the impregnation, and the impregnation is performed in a sealed environment to maintain the solution concentration of the sizing agent unchanged. Preferably, the impregnation time is 1 h-2 h.

[0048] In some embodiments of the present application, the drying comprises: treating the impregnated carbon fiber at a temperature of 150-250° C. for 0.5-5 h to remove the diluent in the sizing agent.

[0049] In some embodiments of the present application, the heat treatment comprises: treating the dried carbon fiber at 280-350°C for 0.5-5h. The heat treatment cures the polysilazane resin and forms a hydrophilic surface on the surface of the polysilazane sizing agent. Under such conditions, the curing effect is better, and the formed hydrophilic surface is more active, further improving the bonding force between the treated fiber and the thermoplastic resin.

[0050] The above sizing method is applicable to various types of carbon fiber materials, and the present application has no limitation thereto. For example, the carbon fiber can be PAN-based carbon fiber, which is particularly applicable to high temperature resistant carbon fiber materials.

[0051] In some embodiments of the present application, the desized carbon fiber is surface-modified, and the surface modification includes introducing any one or more of hydroxyl groups, carboxyl groups, sulfonic acid groups, nitro groups and amino groups onto the surface of the carbon fiber, which can further increase the hydrophilicity of the carbon fiber and improve the bonding strength between the carbon fiber and the sizing agent and the thermoplastic resin.

[0052] According to another typical embodiment of the present application, a carbon fiber is provided, which is a carbon fiber treated by any of the above-mentioned sizing methods.

[0053] The carbon fiber of the present application is treated and sized by the above-mentioned sizing method using the carbon fiber sizing agent of the present application. Since the carbon fiber sizing agent contains polysilicone, it can effectively improve the interface bonding strength between the carbon fiber and the high-performance thermoplastic resin matrix, and the sizing agent is stable under high-temperature processing conditions and does not degrade.

[0054] In some embodiments of the present application, the content of the solid component formed by the sizing agent for the above-mentioned carbon fiber in the above-mentioned carbon fiber accounts for 0.3wt% to 5wt% of the carbon fiber, preferably 1wt% to 2wt%, wherein the solid component formed by the sizing agent is the solid component formed on the surface of the carbon fiber after the carbon fiber is treated with the sizing agent and solidified.

[0055] According to another typical embodiment of the present application, a thermoplastic resin carbon fiber composite material is provided. The thermoplastic resin carbon fiber composite material is made of a raw material containing the above-mentioned carbon fiber.

[0056] The carbon fiber of the present application is not only not easy to break because it is evenly covered with the above-mentioned sizing agent containing polysilazane, but the sizing agent also has excellent heat resistance, and the degradation temperature exceeds 800°C, which far meets the processing temperature requirements of high-performance thermoplastic resin-based carbon fiber reinforced composite materials. The application of the carbon fiber in the preparation of thermoplastic resin carbon fiber composite materials effectively solves the problem that the commonly used sizing agents cannot be used for high-temperature resistant thermoplastic resin-based composite materials, and can avoid the situation in which the interface strength between the resin and the carbon fiber is greatly reduced due to the increase of defects caused by the decomposition of the sizing agent during the processing of high-performance thermoplastic resins.

[0057] The carbon fiber of the present application can be applied to the preparation of various thermoplastic resin carbon fiber composite materials, that is, there is no restriction on the thermoplastic resin raw materials in the thermoplastic resin carbon fiber composite materials. Considering its excellent high temperature resistance, it is particularly suitable for application in thermoplastic resin carbon fiber composite materials that need to be processed or used at higher temperatures. In some embodiments of the present application, the thermoplastic resin includes any one or more of polyetherketoneketone, polyetheretherketone, polyphenylene sulfide, polyimide, polyetherimide, polysulfone, polyarylate and nylon, which can be well combined with the carbon fiber of the present application and have good mechanical properties.

[0058] The beneficial effects that can be achieved by the present application will be further illustrated below in combination with embodiments and comparative examples.

[0059] Example 1

[0060] A high temperature resistant carbon fiber sizing agent suitable for high performance thermoplastic resin, comprising: 1wt% polysilazane KB-8802 resin (provided by Kube Chemical Shanghai Co., Ltd.), 0.1wt% KH550, and the rest being diluent acetone.

[0061] The sizing process is as follows: immerse the carbon fiber (Toray T300) in acetone and reflux at 70°C for 10 hours to remove the surface sizing agent, take it out and rinse it with deionized water and dry it, immerse the dried carbon fiber in the above sizing agent, and seal it at room temperature to keep the concentration of the sizing agent unchanged. After immersion for 2 hours, take out the carbon fiber and dry it at 200°C for 1 hour to completely remove the acetone diluent, and then heat treat it at 300°C for 1 hour to completely cure the sizing agent and improve the hydrophilicity and surface energy of the sizing agent surface.

[0062] Thermogravimetric curves of carbon fiber before and after sizing are shown in the figure below. Figure 1 As shown in the figure, it can be seen that the heat resistance of the carbon fiber after sizing is significantly improved compared with the carbon fiber before treatment, that is, the unsizing carbon fiber. The solid component content of the sizing agent is about 3%, and it does not decompose above 800°C, indicating that the heat resistance of the sizing agent exceeds 800°C. The scanning electron microscope (SEM) image of the carbon fiber after acetone reflux desizing is shown in the figure. Figure 2As shown in the figure, the thermosetting sizing agent on the fiber surface is removed, revealing the uneven carbon fiber surface; the SEM image of the carbon fiber sizing agent after being sized with a high temperature resistant polysilazane is shown in the figure. Figure 3 As shown, it can be seen that the sizing agent evenly wraps the carbon fiber and combines well with the carbon fiber. In addition, since the carbon fiber sizing is relatively uniform, it can effectively prevent the carbon fiber from having "hair" problems during use.

[0063] The carbon fiber before and after sizing was tested for single-filament tensile strength, and at least 50 valid data were tested and the average value was calculated. Before sizing, the strength of the carbon fiber was 67cN / tex, and the tensile strength of the carbon fiber after sizing was 127cN / tex, indicating that the defects on the fiber surface were reduced and the sizing agent greatly increased the tensile strength of the carbon fiber. In addition, the sizing carbon fiber and polyetheretherketone resin (PEEK 550G) were subjected to a droplet embedding experiment to test the interfacial bonding strength (IFBS) of the two, and at least 25 valid data were tested and averaged. Before sizing, the average IFBS was 51MPa. After sizing, due to the hydrogen bond interaction between the sizing agent and polyetheretherketone, the IFBS increased to 81MPa, indicating that the sizing agent enhanced the interfacial bonding strength between the carbon fiber and polyetheretherketone. The above test results are summarized in Table 1.

[0064] Example 2

[0065] A high temperature resistant carbon fiber sizing agent suitable for high performance thermoplastic resin, comprising: 1wt% polysilazane KB-8802 resin (provided by Kube Chemical Shanghai Co., Ltd.), and the rest is diluent ethyl acetate.

[0066] The sizing process is as follows: immerse the carbon fiber (Toray T300) in acetone at 70°C for 10 hours to remove the surface sizing agent, take it out, rinse it with deionized water and dry it, immerse the dried carbon fiber in the above sizing agent, seal it at room temperature to keep the concentration of the sizing agent unchanged, and after immersion for 3 hours, take out the carbon fiber and dry it at 220°C for 2 hours to completely remove the ethyl acetate diluent, and then heat treat it at 310°C for 1 hour to completely cure the sizing agent and improve the hydrophilicity of the sizing agent surface. Among them, the content of the solid component of the sizing agent is 2.5wt%.

[0067] The carbon fiber before and after sizing was tested for single-filament tensile strength, and at least 50 valid data were tested and averaged. Before sizing, the strength of the carbon fiber was 67cN / tex, and after sizing, the tensile strength of the carbon fiber was 101cN / tex, indicating that the defects on the fiber surface were reduced and the sizing agent greatly increased the tensile strength of the carbon fiber. The sizing carbon fiber was subjected to a droplet embedding experiment with polyetheretherketone resin (PEEK 550G) to test the interfacial bonding strength (IFBS) of the two. The average was calculated after at least 15 tests. Before sizing, the average IFBS was 51MPa. After sizing, due to the hydrogen bond interaction between the sizing agent and polyetheretherketone, the IFBS increased to 76MPa, indicating that the sizing agent enhanced the interfacial bonding strength of the carbon fiber and polyetheretherketone. The test results are summarized in Table 1.

[0068] Example 3

[0069] The difference from Example 1 is that the sizing agent is composed of: 5 wt % polysilazane KB-8802 resin (provided by KubeChem Shanghai Co., Ltd.), 0.5 wt % KH550, and the rest is diluent acetone.

[0070] The sizing process, the single filament tensile strength and the interface bonding strength test process of the carbon fiber are the same as those of Example 1, wherein the content of the solid component of the sizing agent in the fiber after sizing is 4.1wt%. The single filament tensile strength of the sizing carbon fiber is 98cN / tex, and the IFBS of the sizing carbon fiber and the high-performance thermoplastic polyetheretherketone resin is 71MPa.

[0071] Example 4

[0072] The difference from Example 1 is that the composition of the sizing agent is: 0.01 wt % polysilazane KB-8802 resin (provided by KubeChem Shanghai Co., Ltd.) and the rest is diluent acetone.

[0073] The sizing process, the single filament tensile strength and the interface bonding strength test process of the carbon fiber are the same as those of Example 1, wherein the content of the solid component of the sizing agent in the fiber after sizing is 0.3wt%. The single filament tensile strength of the sizing carbon fiber is 89cN / tex, and the interface bonding strength IFBS between the sizing carbon fiber and the high-performance thermoplastic polyetheretherketone resin is 73MPa.

[0074] Example 5

[0075] The difference from Example 1 is that the composition of the sizing agent is: 0.01 wt % of polysilazane KB-8802 resin (provided by KubeChem Shanghai Co., Ltd.), 0.005 wt % of KH550, and the rest is diluent acetone.

[0076] The sizing process, the single filament tensile strength and the interface bonding strength test process of the carbon fiber are the same as those of Example 1, wherein the content of the solid component of the sizing agent in the fiber after sizing is 0.36wt%. The single filament tensile strength of the sizing carbon fiber is 75cN / tex, and the interface bonding strength IFBS between the sizing carbon fiber and the high-performance thermoplastic polyetheretherketone resin is 95MPa.

[0077] Example 6

[0078] The only difference from Example 1 is that the composition of the sizing agent is: 5wt% polysilazane KB-8802 resin (provided by KubeChem Shanghai Co., Ltd.), 0.1wt% KH550, and the rest is diluent acetone.

[0079] The sizing process, the single filament tensile strength and the interface bonding strength test process of the carbon fiber are the same as those of Example 1, wherein the content of the solid component of the sizing agent in the fiber after sizing is 4.8wt%. The single filament tensile strength of the sizing carbon fiber is 91cN / tex, and the interface bonding strength IFBS between the sizing carbon fiber and the high-performance thermoplastic polyetheretherketone resin is 74MPa.

[0080] Example 7

[0081] The difference from Example 1 is that the same amount of KH792 is used to replace KH550 in the sizing agent.

[0082] The sizing process, single filament tensile strength and interface bonding strength test process of the carbon fiber are the same as those of Example 1. The single filament tensile strength of the sizing carbon fiber is 80 cN / tex, and the interface bonding strength IFBS between the sizing carbon fiber and the high-performance thermoplastic polyetheretherketone resin is 119 MPa.

[0083] Example 8

[0084] The only difference from Example 1 is that in the interface bonding strength IFBS test, a high-performance thermoplastic polyphenylene sulfide resin (Durafide 0220A9) is used to replace the high-performance thermoplastic polyetheretherketone resin. Before sizing, the interface bonding strength IFBS between the carbon fiber and the polyphenylene sulfide resin is 47 MPa, and after sizing, the IFBS between the carbon fiber and the polyphenylene sulfide resin is 75 MPa.

[0085] Example 9

[0086] The difference from Example 1 is that the same amount of polysilazane KB-8801 resin (provided by Kube Chemical Shanghai Co., Ltd.) is used in the sizing agent instead of polysilazane KB-8802 resin. The single-filament tensile strength of the sizing carbon fiber is 116 cN / tex, and the IFBS of the sizing carbon fiber and the high-performance thermoplastic polyetheretherketone resin is 79 MPa.

[0087] The results of IFBS and single-filament tensile strength in the above examples are shown in Table 1 below.

[0088] Table 1

[0089]

[0090]

[0091] From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects: the sizing agent for carbon fiber of the present application contains polysiloxane, so that the sizing agent can not only evenly cover the surface of the fiber to prevent it from breaking, but also has excellent heat resistance, and the degradation temperature exceeds 800°C, which far meets the processing temperature requirements of high-performance thermoplastic resin-based carbon fiber reinforced composite materials, and effectively solves the problem that the commonly used sizing agents cannot be used for high-temperature resistant thermoplastic resin-based composite materials, and can avoid the situation in which the interface strength between the resin and the carbon fiber is greatly reduced due to the increase in defects caused by the decomposition of the sizing agent during the processing of high-performance thermoplastic resins.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A sizing agent for carbon fiber, characterized in that: include: Polysilazane and diluent; Wherein, the content of polysilazane is 0.01-5wt%.

2. The sizing agent for carbon fiber according to claim 1, characterized in that The sizing agent also includes 0-0.5wt% of a silane coupling agent; Preferably, the silane coupling agent is any one or more of KH550, KH560, KH570 and KH792; Preferably, the content of polysilazane in the sizing agent is 0.1 wt% to 2 wt%, and the content of silane coupling agent is 0.005 wt% to 0.5 wt%.

3. The sizing agent for carbon fiber according to claim 1, characterized in that The diluent includes any one or more of acetone, acetate, tetrahydrofuran, xylene, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide; The polysilazane contains Si-H bonds. Preferably, the polysilazane includes any one or more of KB-8801 resin and KB-8802 resin; Preferably, the degradation temperature of the carbon fiber sizing agent is greater than or equal to 800°C.

4. A method for sizing carbon fiber, characterized in that: include: The carbon fiber is treated with the sizing agent for carbon fiber according to any one of claims 1 to 3.

5. The sizing method according to claim 4, characterized in that: include: After the carbon fiber is desized, the desized carbon fiber is immersed in the sizing agent, and the sized carbon fiber is obtained through drying and heat treatment.

6. The sizing method according to claim 5, characterized in that: The desizing comprises: desizing the carbon fiber by treating it with an organic solvent or at a high temperature; The impregnation comprises: impregnating the desized carbon fiber in the sizing agent for 5 minutes to 5 hours; The drying comprises: treating the impregnated carbon fiber at a temperature of 150-250° C. for 0.5-5 hours; The heat treatment comprises: treating the dried carbon fiber at a temperature of 280-350° C. for 0.5-5 hours.

7. The sizing method according to claim 5 or 6, characterized in that: The desized carbon fibers are subjected to surface modification, wherein the surface modification comprises introducing any one or more of hydroxyl groups, carboxyl groups, sulfonic acid groups, nitro groups and amino groups onto the surface of the carbon fibers.

8. A carbon fiber, characterized in that: The carbon fiber is a carbon fiber treated by the sizing method according to any one of claims 4 to 7.

9. A thermoplastic resin carbon fiber composite material, characterized in that: The thermoplastic resin carbon fiber composite material is made of a raw material containing the carbon fiber according to claim 8.

10. The thermoplastic resin carbon fiber composite material according to claim 9, wherein the raw material comprises a thermoplastic resin, and the thermoplastic resin comprises any one or more of polyetherketoneketone, polyetheretherketone, polyphenylene sulfide, polyimide, polyetherimide, polysulfone, polyarylate and nylon.

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