Carbon fiber composite material and preparation method thereof

Abstract

The invention discloses a carbon fiber composite material and a preparation method thereof. The composite material comprises carbon fibers and an epoxy resin matrix, and the epoxy resin matrix comprises the following components in parts by weight: 90-110 parts of epoxy resin, 80-100 parts of a curing agent and 0.5-2 parts of an accelerant; wherein the curing agent is methyl tetrahydrophthalic anhydride or hydrogenated methyl tetrahydrophthalic anhydride. The tensile strength and the Weibull modulus of the composite material can be remarkably improved by controlling the number of the tows to be close to the critical value. Concrete technical standards and solutions which are directly used for guiding production are developed; the performance is remarkably improved, the stability is greatly improved, and a new important basis is provided for quality control and performance design of a high-end carbon fiber composite material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon fiber composite materials, in particular to a carbon fiber composite material and a preparation method thereof. BACKGROUND

[0002] The mechanical properties of carbon fiber reinforced composite materials are highly dependent on the characteristics of the reinforcing fibers, and fiber strength is a key factor determining the ultimate strength of the composite material. In the prior art, the performance optimization of carbon fiber bundle composite materials mainly focuses on fiber surface treatment, matrix material improvement, etc., and the systematic research and application of the number of tows as a key parameter are less, and there is a lack of specific tow number optimization scheme that can guide actual production in actual production, making it difficult to achieve precise control of the performance of the composite material. SUMMARY

[0003] The present application aims to provide a carbon fiber composite material and a preparation method thereof, which provides a new way for the performance optimization of carbon fiber composite materials. By accurately controlling the number of tows of the carbon fiber bundle, the present application can effectively control the tensile properties of the composite material, and by using the JER813 epoxy resin and YH306 anhydride curing agent system, the prepared carbon fiber composite material has very small performance dispersion and very high reliability, and has very significant quality improvement.

[0004] According to one aspect of the present application, a carbon fiber composite material is provided, comprising carbon fibers and an epoxy resin matrix, wherein the epoxy resin matrix comprises the following components by weight: 90-110 parts of epoxy resin, 80-100 parts of curing agent, and 0.5-2 parts of accelerator; wherein the curing agent is methyl tetrahydrophthalic anhydride (MeTHPA) or hydrogenated methyl tetrahydrophthalic anhydride (H2-MeTHPA).

[0005] Preferably, the epoxy resin is E-51 epoxy resin, and the accelerator is 2,4,6-tris(dimethylaminomethyl) phenol (DMP-30).

[0006] Preferably, the carbon fibers are T1100 or M40X; the number of fibers of the T1100 is 11000-12000, and the number of fibers of the M40X is 9000-10000.

[0007] Preferably, the number of fibers of the T1100 is 12000, and the number of fibers of the M40X is 9000.

[0008] According to a second aspect of the present application, a preparation method of the aforementioned carbon fiber composite material is provided, comprising the following steps: S1: tow selection and treatment: selecting a predetermined number of tows from a carbon fiber bundle and cutting them perpendicular to the fiber axis with scissors; S2: Epoxy resin preparation: add epoxy resin and curing agent into a container, then add accelerant and stir evenly to prepare an epoxy resin solution; S3: Impregnation and curing: impregnate the carbon fiber with the prepared epoxy resin solution system, and then perform stepwise curing to obtain the carbon fiber composite material.

[0009] Preferably, in step S1, the determination method of the predetermined number of tows is as follows: for a range of tow numbers, different numbers of tows are selected at different predetermined intervals, and subsequent processing and performance testing are performed. Specifically: The number of carbon fiber tows ranges from 0 to 1000, and tows are selected at an interval of 500; The number of carbon fiber tows ranges from 1000 to 9000, and tows are selected at an interval of 1000; The number of carbon fiber tows ranges from 9000 to 12000, and tows are selected at an interval of 3000; The number of carbon fiber tows is more than 12000, and tows are selected at an interval of 4000.

[0010] The above method of selecting the number of tows can conveniently and accurately determine the optimal number of tows.

[0011] Preferably, in step S3, the stepwise curing is as follows: pre-curing at 80-100℃ for 2-4 hours, and then post-curing at 120-150℃ for 4-8 hours. The first stage of curing allows the resin to be initially cross-linked, which is convenient for subsequent operation and molding; the second stage of curing can further improve the performance of the cured material, so that the resin is fully cured.

[0012] The present application determines the influence of the number of fibers on the Weibull modulus, providing a statistical basis for the strength prediction of carbon fiber composites. The Weibull modulus calculation formula is as follows:

[0013] Wherein: P F : cumulative failure probability P F = i / (n+1) Where i: the number of bundle composites that fail at or below the stress level n: total number of tests N: the number of fibers in the fiber bundle N0: reference fiber number (usually 1) σ bf : tensile strength of the fiber bundle σ b0 : Weibull scale parameter (characteristic stress) m: Weibull modulus (shape parameter, reflecting the dispersion of strength distribution) Horizontal axis: σ bf Vertical axis: ln{ln(1 / (1-P F )} The slope of the fitting line is the Weibull modulus m, and the intercept is used to calculate the scale parameter σ b0 .

[0014] The present application can effectively control the tensile properties of the composite material by precisely controlling the number of tows of the carbon fiber bundle. When the number of tows is below the critical value, the tensile strength and Weibull modulus of the composite material significantly increase with the increase of the number of tows, indicating that the synergistic effect between the fibers is enhanced and the influence of defects on the material properties is reduced. When the number of tows exceeds the critical value, although the tensile strength decreases, the Weibull modulus remains constant, indicating that the stability of the material properties is maintained. In addition, JER813 epoxy resin and YH306 anhydride curing agent system are used. Specifically, E-51 epoxy resin + MeTHPA curing agent + DMP-30 accelerator system is used. Experimental studies have shown that the interfacial compatibility and curing characteristics of the resin matrix system used will directly affect the final performance of the composite material. The present application uses a specific and optimized compound system, which has different wettability and interface phase with carbon fiber than the prior art, which is an important factor leading to the difference in performance optimization effect.

[0015] Compared with the prior art, the present application provides precise and optimized tow number process parameters for two important commercial carbon fibers (T1100, M40X) for the first time; develops a concrete technical standard and solution directly used for production guidance; realizes significant improvement of performance and great improvement of stability, and provides new important basis for quality control and performance design of high-end carbon fiber composites. DETAILED DESCRIPTION

[0016] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the present application will be described clearly and completely below in combination with specific embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other arbitrarily without conflict.

[0017] In some alternative embodiments, a carbon fiber composite material is provided, comprising carbon fibers and an epoxy resin matrix, wherein the epoxy resin matrix comprises, by weight parts, the following components: 90-110 parts of an epoxy resin, 80-100 parts of a curing agent, and 0.5-2 parts of an accelerator; wherein the curing agent is methyl tetrahydrophthalic anhydride (MeTHPA) or hydrogenated methyl tetrahydrophthalic anhydride (H2-MeTHPA), the epoxy resin is E-51 epoxy resin, and the accelerator is 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30).

[0018] In some alternative embodiments, a method for preparing the carbon fiber composite material comprises the following steps: S1: selecting and processing the tows: selecting a predetermined number of tows from a carbon fiber tow and cutting them perpendicular to the fiber axis with scissors; the selection is specifically as follows: The number of carbon fiber tows ranges from 0 to 1000, and the tows are selected at intervals of 500; The number of carbon fiber tows ranges from 1000 to 9000, and the tows are selected at intervals of 1000; The number of carbon fiber tows ranges from 9000 to 12000, and the tows are selected at intervals of 3000; The number of carbon fiber tows is more than 12000, and the tows are selected at intervals of 4000; S2: preparing the epoxy resin: adding the epoxy resin and the curing agent into a container, then adding the accelerator and stirring until uniform to obtain an epoxy resin solution; S3: impregnation and curing: after the carbon fibers are fully impregnated with the prepared epoxy resin solution system, stepwise curing is performed, specifically, pre-curing at 80-100°C for 2-4 hours, and then post-curing at 120-150°C for 4-8 hours, to obtain the carbon fiber composite material.

[0019] In order to more clearly explain the technical solutions of the present application, some specific embodiments of the carbon fiber composite material of the present application are listed below.

[0020] Example 1 T1100 carbon fiber epoxy impregnated tow composite material (N=12000) 1. Select 12000 fibers from a T1100 carbon fiber tow and cut them to the appropriate length.

[0021] 2. Select 100 parts of E-51 epoxy resin and 100 parts of methyl tetrahydrophthalic anhydride (MeTHPA) curing agent, add 1 part of 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30) as an accelerator and stir until uniform to obtain an epoxy resin solution.

[0022] 3. After the carbon fibers are fully impregnated with the prepared resin system, pre-cure at 90°C for 2 hours to make the resin preliminary crosslinking, which is convenient for subsequent operation and molding. The product after pre-curing is post-cured at 135°C for 6 hours to further improve the performance of the cured product, so that the resin is fully cured.

[0023] 4. The tensile test shows that the average tensile strength is 7.194 GPa and the Weibull modulus is 14.00.

[0024] Example 2 T1100 carbon fiber epoxy impregnated bundle composite (N = 12000) 1. 12000 T1100 carbon fiber tows are selected, and the above steps are performed for treatment and impregnation and curing.

[0025] 2. 90 parts of E-51 epoxy resin and 80 parts of methyl tetrahydrophthalic anhydride (MeTHPA) curing agent are selected, 0.8 parts of 2,4,6-tris (dimethylaminomethyl) phenol (DMP-30) is added as an accelerator and stirred uniformly to prepare an epoxy resin solution.

[0026] 3. After the carbon fibers are fully impregnated with the prepared resin system, pre-cure at 90°C for 3 hours to make the resin preliminary crosslinking, which is convenient for subsequent operation and molding. The product after pre-curing is post-cured at 135°C for 6 hours to further improve the performance of the cured product, so that the resin is fully cured.

[0027] 4. The tensile test results show that the average tensile strength is 7.012 GPa and the Weibull modulus is 13.78.

[0028] Example 3 T1100 carbon fiber epoxy impregnated bundle composite (N = 12000) 1. 12000 T1100 carbon fiber tows are selected, and the above steps are performed for treatment and impregnation and curing.

[0029] 2. 110 parts of E-51 epoxy resin and 100 parts of hydrogenated methyl tetrahydrophthalic anhydride (H2-MeTHPA) curing agent are selected, 2 parts of 2,4,6-tris (dimethylaminomethyl) phenol (DMP-30) is added as an accelerator and stirred uniformly to prepare an epoxy resin solution.

[0030] 3. After the carbon fibers are fully impregnated with the prepared resin system, pre-cure at 90°C for 3 hours to make the resin preliminary crosslinking, which is convenient for subsequent operation and molding. The product after pre-curing is post-cured at 135°C for 6 hours to further improve the performance of the cured product, so that the resin is fully cured.

[0031] 4. The tensile test results show that the average tensile strength is 7.05 GPa and the Weibull modulus is 13.85.

[0032] Example 4 T1100 carbon fiber epoxy impregnated bundle composite (N = 12000) 1. 12000 fibers were selected from T1100 carbon fiber bundle and cut into appropriate length.

[0033] 2. 100 parts of E-51 epoxy resin and 100 parts of methyl tetrahydrophthalic anhydride (MeTHPA) curing agent were selected, 1 part of 2,4,6-tris(dimethylaminomethyl) phenol (DMP-30) was added as an accelerator and stirred uniformly to prepare an epoxy resin solution.

[0034] 3. After the carbon fiber was fully impregnated with the prepared resin system, it was pre-cured at 80°C for 2 hours to preliminarily crosslink the resin, facilitate subsequent operation and molding. The pre-cured product was then post-cured at 120°C for 6 hours to further improve the performance of the cured product and completely cure the resin.

[0035] 4. The tensile test results show that the average tensile strength is 7.05 GPa and the Weibull modulus is 13.85.

[0036] Example 5 T1100 carbon fiber epoxy impregnated bundle composite (N = 12000) 1. 12000 fibers were selected from T1100 carbon fiber bundle and cut into appropriate length.

[0037] 2. 100 parts of E-51 epoxy resin and 100 parts of methyl tetrahydrophthalic anhydride (MeTHPA) curing agent were selected, 1 part of 2,4,6-tris(dimethylaminomethyl) phenol (DMP-30) was added as an accelerator and stirred uniformly to prepare an epoxy resin solution.

[0038] 3. After the carbon fiber was fully impregnated with the prepared resin system, it was pre-cured at 100°C for 2 hours to preliminarily crosslink the resin, facilitate subsequent operation and molding. The pre-cured product was then post-cured at 150°C for 6 hours to further improve the performance of the cured product and completely cure the resin.

[0039] 4. The tensile test results show that the average tensile strength is 7.05 GPa and the Weibull modulus is 13.85.

[0040] Example 6 T1100 carbon fiber epoxy impregnated bundle composite (N = 12000) The difference from Example 1 is that hydrogenated methyltetrahydrophthalic anhydride (H2-MeTHPA) is used, and the average tensile strength is finally measured to be 7.155 GPa, and the Weibull modulus is 13.98.

[0041] Example 7 M40X carbon fiber epoxy impregnated bundle composite (N = 9000) 1. 6000 M40X carbon fiber tows are selected for subsequent processing. The preparation method is the same as that of Example 2.

[0042] 2. After curing, the average tensile strength is 5.629 GPa, and the Weibull modulus is 10.95.

[0043] Example 8 M40X carbon fiber epoxy impregnated bundle composite (N = 9000) 1. 6000 M40X carbon fiber tows are selected for subsequent processing. The preparation method is the same as that of Example 1.

[0044] 2. After curing, the average tensile strength is 5.871 GPa, and the Weibull modulus is 11.36.

[0045] In order to further illustrate the beneficial effects of the present application, different resin matrices and different tow quantities of composite materials are selected as comparative examples (Comparative Examples 1-3) for performance comparison test.

[0046] Comparative Example 1 M40X carbon fiber epoxy impregnated bundle composite (N = 12000) 1. 12000 fibers are selected from T1100 carbon fiber tows and cut to appropriate length.

[0047] 2. 100 parts of 5028 epoxy resin and 90 parts of 4,4'-diamino diphenyl sulfone (DDS) curing agent are selected, 1 part of 2,4,6-tris (dimethylaminomethyl) phenol (DMP-30) is added as an accelerator, and the mixture is stirred uniformly to prepare an epoxy resin solution.

[0048] 3. After the carbon fibers are fully impregnated with the prepared resin system, the product is pre-cured at 80°C for 2 hours to preliminarily crosslink the resin, facilitating subsequent operation and molding. The pre-cured product is then post-cured at 150°C for 6 hours to further improve the performance of the cured product, so that the resin is fully cured.

[0049] 4. Tensile test is performed, and the average tensile strength is measured to be 5.635 GPa, and the Weibull modulus is 9.78.

[0050] Comparative Example 2 T1100 carbon fiber epoxy impregnated bundle composite (N=12000) 1. Select 12000 fibers from T1100 carbon fiber bundle, cut into appropriate length.

[0051] 2. Select 100 parts of 5028 epoxy resin and 90 parts of 4,4'-diaminodiphenyl sulfone (DDS) curing agent, add 1 part of 2,4,6-tris(dimethylaminomethyl) phenol (DMP-30) as accelerator, stir uniformly to prepare epoxy resin solution.

[0052] 3. After the carbon fiber is fully impregnated with the prepared resin system, pre-cure at 80°C for 2 hours to make the resin preliminary crosslinking, which is convenient for subsequent operation and molding. The product after pre-curing is post-cured at 150°C for 6 hours to further improve the performance of the cured product, so that the resin is fully cured.

[0053] 4. Tensile test is performed, and the average tensile strength is 7.032 GPa, and the Weibull modulus is 12.24.

[0054] Comparative Example 3 T1100 carbon fiber epoxy impregnated bundle composite (N=500) 1. Select 500 fibers from T1100 carbon fiber bundle, cut into appropriate length. Process and impregnate and cure according to the steps of Example 1.

[0055] 2. Tensile test is performed, and the average tensile strength is 5.82 GPa, and the Weibull modulus is 2.28.

[0056] Through the comparison of the test data of the above examples and comparative examples, it can be found that the average tensile strength and Weibull modulus of the specific embodiments of the present application are significantly higher than those of the comparative examples. It shows that controlling the number of tows at the optimal critical value, combined with a specific resin system and curing process can significantly improve the performance of the composite material.

[0057] In addition, the performance test of the composite material with different tow numbers is listed as follows. Specifically, as shown in Table 1 and Table 2. Sample preparation and testing: trim the cured composite material sample (preparation method same as Example 1) to about 65mm long, and paste sandpaper labels on both ends of the sample. Use a universal testing machine (Table-Top Universal Testing Instruments EZ-LX) to perform tensile test, the loading speed is 0.5mm / min, the gauge length is 25mm, 20 samples are tested for each group, and the average tensile strength and Weibull modulus are calculated.

[0058] Table 1 T1100 carbon fiber different number of corresponding strength and Weibull modulus

[0059] Table 2 Strength and Weibull Modulus of M40X Carbon Fiber with Different Number of Roots

[0060] From the data in the table, the precise optimization critical value of the two industrialized carbon fibers can be seen: T1100: N=12000, M40X: N=9000. Under the clear optimal critical value, the strength of the T1100 beam composite material (7.194 GPa) is obtained, and excellent stability is found: the Weibull modulus as high as 15.14 is first realized on the M40X fiber, which indicates that the performance consistency is excellent.

[0061] In summary, for different, unexplored commercial fiber materials (T1100, M40X), through systematic experimental research, the unique performance optimization critical point is first discovered, and different composite material preparation processes are adopted, and finally the performance better than the prior art (higher strength, extremely high Weibull modulus) is obtained. Therefore, the present application has significant technical differences, and the specific critical value and technical scheme proposed by the present application have novelty and unique application value. Specific, quantitative process parameters are provided, which can be directly used to guide production practice. The prior art only discloses general rules, and the present application provides a customized solution for a specific commercial fiber model, and the technical teaching is clearer and more advanced.

[0062] The above examples are only used to illustrate the technical solutions of the present application, but not to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

[0063] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application, but not to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A carbon fiber composite material comprising carbon fibers and an epoxy resin matrix, characterized in that, The epoxy resin matrix comprises the following components by weight parts: epoxy resin 90~110 parts, curing agent 80~100 parts, accelerator 0.5~2 parts; wherein the curing agent is methyl tetrahydrophthalic anhydride or hydrogenated methyl tetrahydrophthalic anhydride.

2. The carbon fiber composite material according to claim 1, characterized by, The epoxy resin is E-51 epoxy resin, and the accelerator is 2,4,6-tris(dimethylaminomethyl) phenol.

3. The carbon fiber composite material according to claim 1, characterized by, The carbon fiber is T1100 or M40X; the fiber number of the T1100 is 11000~12000, and the fiber number of the M40X is 9000~10000.

4. The carbon fiber composite material according to claim 3, characterized by, The fiber number of the T1100 is 12000, and the fiber number of the M40X is 9000.

5. A method for producing a carbon fiber composite material as claimed in any one of claims 1 to 4, characterized by, The method comprises the following steps: S1: selecting and processing the filaments: selecting a predetermined number of filaments from a carbon fiber bundle and cutting them vertically to the fiber axis with scissors; S2: preparing the epoxy resin: adding epoxy resin and curing agent in a container, then adding the accelerator and stirring uniformly to prepare an epoxy resin solution; S3: impregnation and curing: after the carbon fiber is fully impregnated with the prepared epoxy resin solution system, step curing is carried out, and the carbon fiber composite material is obtained.

6. The method for producing a carbon fiber composite material according to claim 5, characterized by, In step S1, the determination method of the predetermined number of filaments is: for the filament number range, different numbers of filaments are selected at different predetermined intervals, and subsequent processing and performance testing are carried out.

7. The method for producing a carbon fiber composite material according to claim 6, characterized by, The selection of different numbers of filaments at different predetermined intervals for the filament number range is as follows: The carbon fiber filament number range is 0-1000, and the filaments are selected at a predetermined interval of 500; The carbon fiber filament number range is 1000-9000, and the filaments are selected at a predetermined interval of 1000; The carbon fiber filament number range is 9000-12000, and the filaments are selected at a predetermined interval of 3000; The carbon fiber filament number range is more than 12000, and the filaments are selected at a predetermined interval of 4000.

8. The method for producing a carbon fiber composite material according to claim 5, characterized by, In step S3, the step curing is specifically: pre-curing at 80~100℃ for 2~4 hours, and then post-curing at 120~150℃ for 4~8 hours.

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