Carbon fiber tow, preparation method thereof and carbon fiber prepreg

Abstract

The invention discloses a carbon fiber tow, a preparation method thereof and a carbon fiber prepreg, and relates to the technical field of carbon fiber manufacturing. The carbon fiber tow is a carbon fiber tow of a first preset specification, the tensile strength of the carbon fiber tow of the first preset specification ranges from 4500 MPa to 5500 MPa, the tensile modulus ranges from 240 GPa to 265 GPa, the volume density ranges from 1.78 g / cm < 3 > to 1.82 g / cm < 3 >, and the first preset specification ranges from 24 k to 80 k. The carbon fiber tow has excellent mechanical properties as a large-size carbon fiber tow, and is not easy to generate filament retreating and branching in the process of preparing the prepreg, so that the problem of flash seams between the tows and in the tows on the cloth surface of the prepreg is solved, and the performance requirements of the low-gram-weight prepreg can be met.

Description

Technical Field

[0001] The present application relates to the technical field of carbon fiber manufacturing, and in particular to a fiber bundle and a preparation method thereof and a carbon fiber prepreg. Background Art

[0002] Carbon fiber can be divided into small-tow carbon fiber and large-tow carbon fiber according to the tow K number. There are obvious differences in the production processes of the two carbon fiber. Relatively speaking, the production process of small-tow carbon fiber is more mature, while the production process of large-tow carbon fiber is bulky.

[0003] Faced with the increasingly severe market environment, entering the prepreg market has become the first choice for domestic carbon fiber manufacturers. However, in the process of preparing prepreg, large-tow carbon fiber has problems such as back-stretching and gaps between prepreg fabric tows, which makes the currently prepared large-tow carbon fiber unable to meet the performance requirements of low-weight prepreg. Therefore, it is particularly important to develop a large-tow carbon fiber suitable for low-weight prepreg. Summary of the invention

[0004] In order to solve the above technical problems, the present application aims to provide a carbon fiber tow, a preparation method thereof and a carbon fiber prepreg. As a large-size carbon fiber tow, the carbon fiber tow has excellent mechanical properties. In the process of preparing the prepreg, the carbon fiber tow is not prone to back-drawing and bifurcation, which solves the problem of flash seams between the tows on the prepreg cloth surface and within the tows, and can meet the performance requirements of low-weight prepregs.

[0005] According to the first aspect of the present application, a carbon fiber tow is provided, wherein the carbon fiber tow is a carbon fiber tow of a first preset specification, and the carbon fiber tow of the first preset specification has a tensile strength of 4500-5500 MPa, a tensile modulus of 240-265 GPa, and a bulk density of 1.78-1.82 g / cm 3 , wherein the first preset specification is 24k-80k.

[0006] In some embodiments of the present application, when the carbon fiber tow of the first preset specification is 24k carbon fiber, the linear density of the carbon fiber is 1570-1630 g / km;

[0007] When the carbon fiber tow of the first preset specification is 36k carbon fiber, the linear density of the carbon fiber is 1770-1830 g / km;

[0008] When the carbon fiber tow of the first preset specification is 48k carbon fiber, the linear density of the carbon fiber is 3150-3250g / km.

[0009] According to a second aspect of the present application, a method for preparing a carbon fiber tow is provided, wherein the method for preparing a carbon fiber tow is used to prepare the carbon fiber tow as described above, and the method comprises:

[0010] Combining a preset number of carbon fiber tow precursors of a second preset specification for the first time under a first preset condition to form a pretreated carbon fiber tow;

[0011] The pretreated carbon fiber tow is combined for a second time under a second preset condition to form a carbon fiber tow precursor with a first preset specification;

[0012] The carbon fiber tow precursor of the first preset specification is carbonized under a third preset condition to obtain the carbon fiber tow of the first preset specification, wherein the k number of the first preset specification is greater than the k number of the second preset specification.

[0013] In some embodiments of the present application, the first spun yarn of a preset number of carbon fiber tow precursors of a second preset specification is synthesized under a first preset condition to form a pretreated carbon fiber tow, including:

[0014] The preset number of carbon fiber tow precursors of the second preset specification are stacked and combined to form a carbon fiber tow intermediate; the carbon fiber tow intermediate is sequentially subjected to a preset number of washing, drawing, oiling and drying to form the pretreated carbon fiber tow.

[0015] In some embodiments of the present application, the water washing temperature is 40-60°C;

[0016] The drawing temperature is 50-75°C;

[0017] The oiling temperature is 20-30°C;

[0018] The drying temperature is 150-210° C. and the pressure is 0.5-1.4 MPa.

[0019] In some embodiments of the present application, the second synthesis of the pretreated carbon fiber tow under a second preset condition to form a carbon fiber tow precursor of a first preset specification includes:

[0020] The pretreated carbon fiber tow is sequentially passed through the first-stage limiting groove, the second-stage limiting groove, and the third-stage limiting groove of the combiner, and then sequentially subjected to steam drawing, yarn spreading, and winding to form the first preset specification carbon fiber tow precursor;

[0021] The inner diameters of the first-stage limiting groove, the second-stage limiting groove, and the third-stage limiting groove decrease step by step;

[0022] The inner diameter of the third-stage limiting groove matches the hole size of the steam drawing.

[0023] In some embodiments of the present application, the steam pressure of the steam drawing is 0.3-0.6MPa;

[0024] The pretreated carbon fiber tow is stretched by 0.8-1.3 times after passing through the combiner;

[0025] The drafting multiple of the pretreated carbon fiber tow during fiber spreading is 0.8-1.3 times.

[0026] In some embodiments of the present application, the carbonizing of the carbon fiber tow precursor of the first preset specification under a third preset condition to obtain the carbon fiber tow of the first preset specification includes:

[0027] The carbon fiber tow precursor of the first preset specification is subjected to a pre-oxidation treatment, a low-temperature carbonization treatment, and a high-temperature carbonization treatment in sequence to obtain the carbon fiber tow of the first preset specification;

[0028] The pre-oxidation treatment temperature is 230-280°C, and the drafting ratio is 0.8-1.2 times;

[0029] The temperature of the low-temperature carbonization treatment is 400-850°C, and the draft ratio is 0.9-1.3 times;

[0030] The temperature of the high temperature carbonization treatment is 900-1600° C., and the drafting ratio is 0.8-1.1 times.

[0031] According to a third aspect of the present application, a carbon fiber prepreg is provided, the carbon fiber prepreg comprising a resin matrix and the carbon fiber tow as described above or a carbon fiber tow prepared by the method for preparing the carbon fiber tow as described above;

[0032] The carbon fiber prepreg has a gram weight of 50-100 g / m 2 .

[0033] In some embodiments of the present application, the number of inter-tow flash seams of the carbon fiber prepreg is 0-5, and the number of intra-tow flash seams is 0-5.

[0034] The technical solution provided by this application may have the following beneficial effects:

[0035] The carbon fiber tow of the present application has excellent mechanical properties as a large-size carbon fiber tow. In the process of preparing prepreg, the carbon fiber tow is not prone to back-drawing and bifurcation, which solves the problem of flash seams between tows and within tows on the prepreg cloth surface, and can meet the performance requirements of low-weight prepreg.

[0036] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0038] Figure 1 The present invention is a flow chart of a method for preparing a carbon fiber tow according to an exemplary embodiment.

[0039] Figure 2 is a schematic structural diagram of a limiter according to an exemplary embodiment.

[0040] Figure 3 It is a schematic structural diagram of a wire combiner according to an exemplary embodiment.

[0041] Figure 4 It is a schematic structural diagram of a yarn unroller according to an exemplary embodiment.

[0042] Reference numerals:

[0043] 1. Raw silk; 2. Limiter; 21. Silk path; 3. Wire combiner; 31. First-level limit groove; 32. Second-level limit groove; 33. Third-level limit groove; 4. Wire spreader; 41. Wire spreader roller. DETAILED DESCRIPTION

[0044] In order 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 clearly and completely described below in combination with the embodiments of the present application and the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be arbitrarily combined with each other.

[0045] The present application provides a carbon fiber tow, which is a carbon fiber tow of a first preset specification, and the carbon fiber tow of the first preset specification has a tensile strength of 4500-5500 MPa, a tensile modulus of 240-265 GPa, and a bulk density of 1.78-1.82 g / cm 3 , wherein the first preset specification is 24k-80k. The carbon fiber tow of the present application has excellent mechanical properties as a large-size carbon fiber tow. In the process of preparing prepreg, the carbon fiber tow is not easy to produce back-stretching and bifurcation, which solves the problem of flash seams between tows and within tows on the prepreg cloth surface, and can meet the performance requirements of low-weight prepreg.

[0046] Some specific implementation modes described below are intended to facilitate those skilled in the art to understand the present embodiment, and the present embodiment is not limited to some specific implementation modes described below.

[0047] In an exemplary embodiment, the present application provides a carbon fiber tow, the carbon fiber tow is a carbon fiber tow of a first preset specification, the carbon fiber tow of the first preset specification has a tensile strength of 4500-5500 MPa, a tensile modulus of 240-265 GPa, and a bulk density of 1.78-1.82 g / cm 3 , where the first preset specification is 24k-80k.

[0048] The carbon fiber tow of the present application is 24k-80k carbon fiber, which is a large-size tow with a tensile strength of 4500-5500MPa and a tensile modulus of 240-265GPa. It has excellent mechanical properties. In the process of preparing prepregs, the carbon fiber tow is not prone to back-drawing and bifurcation, which solves the problem of flash seams between the tows on the prepreg cloth and within the tows, and can meet the performance requirements of low-weight prepregs.

[0049] For example, the first preset specification can be 24k, 36k, 48k, 60k, 80k; the tensile strength of the carbon fiber tow can be 4500MPa, 5000MPa, 5500MPa; the tensile modulus can be 240GPa, 250GPa, 265GPa; the bulk density can be 1.78g / cm 3 , 1.80g / cm 3 , 1.82g / cm 3 .

[0050] In an exemplary embodiment, when the carbon fiber tow of the first preset specification is 24k carbon fiber, the linear density of the carbon fiber is 1570-1630 g / km;

[0051] When the carbon fiber tow of the first preset specification is 36k carbon fiber, the linear density of the carbon fiber is 1770-1830 g / km;

[0052] When the carbon fiber tow of the first preset specification is 48k carbon fiber, the linear density of the carbon fiber is 3150-3250g / km.

[0053] For example, when the carbon fiber tow of the first preset specification is 24k carbon fiber, the linear density of the carbon fiber can be 1570g / km, 1600g / km, 1630g / km. When the carbon fiber tow of the first preset specification is 36k carbon fiber, the linear density of the carbon fiber is 1770g / km, 1800g / km, 1830g / km. When the carbon fiber tow of the first preset specification is 48k carbon fiber, the linear density of the carbon fiber is 3150g / km, 3200g / km, 3250g / km.

[0054] like Figure 1 As shown, an exemplary embodiment of the present application provides a method for preparing a carbon fiber tow, the method for preparing a carbon fiber tow is used to prepare the above carbon fiber tow, and the preparation method includes:

[0055] S100, a preset number of carbon fiber tow precursors of a second preset specification are first combined under a first preset condition to form a pretreated carbon fiber tow.

[0056] In step S100, the second preset specification is 1k-12k, and the carbon fiber precursor under this specification is a small-sized carbon fiber. The small-sized carbon fiber precursor is easier to control the quality during the production process, and its product has good uniformity, consistency and reliability. A preset number of small-sized carbon fiber tow precursors are combined to form a large-sized pretreated carbon fiber tow.

[0057] The preset number can be determined according to the k number of the first preset specification and the second preset specification. For example, in order to prepare 24k carbon fiber, 2 bundles of 12k carbon fiber precursors can be used for merging, or 4 bundles of 6k carbon fiber precursors can be used for merging; in order to prepare 48k carbon fiber, 4 bundles of 12k carbon fiber precursors can be used for merging, or 2 bundles of 12k carbon fiber precursors and 4 bundles of 6k carbon fiber precursors can be used for merging.

[0058] S200, combining the pretreated carbon fiber tow for a second time under a second preset condition to form a carbon fiber tow precursor of a first preset specification.

[0059] In step S200, the pretreated carbon fiber tow is combined for the second time under the second preset condition, which can improve the bundling of the carbon fiber tow and solve the problem of fiber withdrawal and bifurcation when preparing the prepreg.

[0060] S300, carbonizing the carbon fiber tow precursor of the first preset specification under the third preset condition to obtain the carbon fiber tow of the first preset specification, wherein the k number of the first preset specification is greater than the k number of the second preset specification.

[0061] In step S300, the carbon fiber tow precursor 1 of the first preset specification is carbonized under the third preset conditions, which can increase the tensile strength and modulus of the fiber and improve the thermal properties and dimensional stability of the fiber.

[0062] In an exemplary embodiment, this embodiment is a further description of step S100 in the above embodiment, and a preset number of carbon fiber tow precursors of a second preset specification are first combined under a first preset condition to form a pretreated carbon fiber tow, including:

[0063] A preset number of carbon fiber tow raw yarns of a second preset specification are superimposed and combined to form a carbon fiber tow intermediate; the carbon fiber tow intermediate is sequentially subjected to a preset number of times of washing, drawing, oiling and drying to form a pretreated carbon fiber tow.

[0064] In this embodiment, the following can be used Figure 2 The stopper 2 shown in the figure performs the first silk combining, and the stopper 2 has a silk path 21, and the width of the silk path 21 = the width of the carbon fiber tow precursor 1 of the second preset specification × the number of bundles of the carbon fiber tow precursor 1 of the second preset specification. Fixing multiple bundles of carbon fiber tow precursor 1 of the second preset specification on a silk path 21 can make them combine into a bundle of carbon fiber tow precursor 1 of the first specification. Then, after the carbon fiber tow intermediate is washed, drawn, oiled, and dried for a preset number of times in sequence, the bundling property of the carbon fiber tow intermediate after the silk combining can be improved to form a pre-treated carbon fiber tow.

[0065] During the water washing process, the preset number of times can be one, two, five, ten, etc., and the number of water washings can be determined based on whether the residual amount of solvent in the solution after water washing meets the requirements in the process. After water washing, the residual solvent or impurities on the carbon fiber tow intermediate can be washed away. The water washing temperature is 40-60°C. Exemplarily, the water washing temperature can be 40°C, 50°C, or 60°C.

[0066] During the drawing process, the precursor 1 is stretched, which helps the polymer molecular chain to be oriented along the axial direction of the fiber, thereby improving the strength and modulus of the carbon fiber. The drawing can be done by hot water drawing, and the drawing temperature is 50-75° C. For example, the drawing temperature is 50° C., 60° C., and 75° C.

[0067] During the oiling process, a layer of oil is applied to the surface of the original silk 1, which can protect the original silk 1 and reduce its friction and wear during subsequent processing. The oiling temperature is 20-30°C. For example, the oiling temperature can be 20°C, 25°C, or 30°C.

[0068] During the drying process, on the one hand, the moisture in the precursor 1 can be removed to avoid structural defects in the fiber caused by the presence of moisture. On the other hand, a certain pressure can be applied during the drying process to densify the precursor 1, which can reduce the porosity of the precursor 1 and improve the microstructure inside the precursor 1 to enhance the mechanical strength and modulus of the carbon fiber. The drying temperature is 150-210°C and the pressure is 0.5-1.4MPa. For example, the drying temperature can be 150°C, 180°C, 210°C; the pressure can be 0.5MPa, 0.8MPa, 1.0MPa, 1.2MPa.

[0069] In an exemplary embodiment, this embodiment is a further description of step S200 in the above embodiment, and the pretreated carbon fiber tow is subjected to a second yarn combination under a second preset condition to form a carbon fiber tow precursor of a first preset specification, including:

[0070] The pretreated carbon fiber tow is passed through the first-stage limiting groove 31, the second-stage limiting groove 32, and the third-stage limiting groove 33 of the combiner 3 in sequence, and then is successively subjected to steam drawing, yarn spreading, and winding to form a carbon fiber tow precursor 1 of a first preset specification; wherein the inner diameters of the first-stage limiting groove 31, the second-stage limiting groove 32, and the third-stage limiting groove 33 are gradually reduced; and the inner diameter size of the third-stage limiting groove 33 matches the hole size of the steam drawing.

[0071] In this embodiment, the pretreated carbon fiber tow is subjected to Figure 2 The wire combiner 3 shown in the figure passes through the first-level limiting groove 31, the second-level limiting groove 32, and the third-level limiting groove 33 of the wire combiner 3 in sequence. Since the inner diameters of the first-level limiting groove 31, the second-level limiting groove 32, and the third-level limiting groove 33 are gradually reduced, and the inner diameter size of the third-level limiting groove 33 is matched with the hole size of the steam drawing in the next process, the width of the pretreated carbon fiber tow can be adjusted to match the hole size of the steam drawing, so as to avoid damage to the surface of the tow due to excessive tow width when passing through the steam drawing hole, and the bundling of the pretreated carbon fiber tow can be further improved, so as to avoid the problem of back-drawing and bifurcation when preparing prepreg, which helps to reduce the flash seams between tows and flash seams within tows of the prepreg, and solves the problem of poor prepreg cloth effect caused by uneven carbon fiber performance and carbon fiber width. Among them, the pretreated carbon fiber is "S"-shaped and passes through the first-level limiting groove 31, the second-level limiting groove 32, and the third-level limiting groove 33 in sequence.

[0072] The pretreated carbon fiber tow is steam drawn and then Figure 3The yarn spreader 4 shown includes a three-stage spreader roller 41. Since the width of the pretreated carbon fiber tow after steam drawing is insufficient, the tow is fully spread under the action of the three-stage spreader roller 41, and its uniformity is improved, so that the uniformity of the width of the prepared carbon fiber is better, and further in the prepreg application process, it shows a better yarn spreading effect. Among them, the pretreated carbon fiber tow passes through the three-stage spreader roller 41 of the yarn spreader 4 in an "S" shape.

[0073] In an exemplary embodiment, the steam pressure of the steam drawing is 0.3-0.6 MPa. Exemplarily, the steam pressure of the steam drawing can be 0.3 MPa, 0.45 MPa, or 0.6 MPa.

[0074] In an exemplary embodiment, the drafting ratio of the pre-treated carbon fiber tow passing through the combiner 3 is 0.8-1.3 times.

[0075] In this embodiment, the pretreated carbon fiber tow is stretched when passing through each level of the limit groove of the combiner 3, and the stretching force at each level is consistent. Exemplarily, the stretching multiples of the pretreated carbon fiber tow passing through the combiner 3 can be 0.8 times, 0.9 times, 1.1 times, and 1.3 times.

[0076] In an exemplary embodiment, the drafting ratio of the pretreated carbon fiber tow during the stretching is 0.8-1.3 times. Exemplarily, the drafting ratio of the pretreated carbon fiber tow during the stretching can be 0.8 times, 0.9 times, 1.1 times, or 1.3 times.

[0077] In an exemplary embodiment, this embodiment is a further description of step S300 in the above embodiment, wherein a carbon fiber tow precursor of a first preset specification is carbonized under a third preset condition to obtain a carbon fiber tow of a first preset specification, including:

[0078] The carbon fiber tow precursor 1 of the first preset specification is subjected to pre-oxidation treatment, low-temperature carbonization treatment and high-temperature carbonization treatment in sequence to obtain a carbon fiber tow of the first preset specification; wherein the temperature of the pre-oxidation treatment is 230-280°C, and the drafting ratio is 0.8-1.2 times; the temperature of the low-temperature carbonization treatment is 400-850°C, and the drafting ratio is 0.9-1.3 times; the temperature of the high-temperature carbonization treatment is 900-1600°C, and the drafting ratio is 0.8-1.1 times.

[0079] In this embodiment, by adjusting the temperature and the draft ratio during the pre-oxidation treatment, the low-temperature carbonization treatment and the high-temperature carbonization treatment, it helps to improve the mechanical properties of the carbon fiber, such as the tensile strength and tensile modulus.

[0080] Exemplarily, in one embodiment, the temperature of the pre-oxidation treatment is 230°C, and the stretching ratio is 0.8 times; the temperature of the low-temperature carbonization treatment is 400°C, and the stretching ratio is 0.9 times; the temperature of the high-temperature carbonization treatment is 900°C, and the stretching ratio is 0.8 times.

[0081] In another embodiment, the temperature of the pre-oxidation treatment is 250°C, and the stretching ratio is 0.9 times; the temperature of the low-temperature carbonization treatment is 450°C, and the stretching ratio is 1.0 times; the temperature of the high-temperature carbonization treatment is 1200°C, and the stretching ratio is 0.96 times.

[0082] In another embodiment, the temperature of the pre-oxidation treatment is 260°C, and the stretching ratio is 1.1 times; the temperature of the low-temperature carbonization treatment is 650°C, and the stretching ratio is 1.2 times; the temperature of the high-temperature carbonization treatment is 1400°C, and the stretching ratio is 1.0 times.

[0083] In another embodiment, the temperature of the pre-oxidation treatment is 280°C, and the stretching ratio is 1.2 times; the temperature of the low-temperature carbonization treatment is 850°C, and the stretching ratio is 1.3 times; the temperature of the high-temperature carbonization treatment is 1600°C, and the stretching ratio is 1.1 times.

[0084] An exemplary embodiment of the present application provides a carbon fiber prepreg, the carbon fiber prepreg comprising a resin matrix and a carbon fiber tow as in the above embodiment or a carbon fiber tow prepared by the method for preparing a carbon fiber tow as in the above embodiment; the gram weight of the carbon fiber prepreg is 50-100 g / m 2 .

[0085] In this embodiment, the carbon fiber tow has good bundling properties and is not easy to bifurcate. The weight of the prepreg prepared from the carbon fiber can be 50-100 g / m 2 , meeting the requirements of low-weight prepreg. For example, the weight of the carbon fiber prepreg is 50g / m 2 , 75g / m 2 , 100g / m 2 .

[0086] In an exemplary embodiment, the number of flash joints between tows of the carbon fiber prepreg is 0-5, and the number of flash joints within the tows is 0-5.

[0087] In this embodiment, when the carbon fiber of the present application is used to prepare prepreg, the problem of fiber withdrawal and bifurcation is significantly improved. The number of flash seams between filament bundles and the number of flash seams within filament bundles of the prepreg thus prepared are both between 0 and 5, and the product grade meets the A+ grade requirement.

[0088] In order to more clearly explain the technical solution of the present application, the present application lists specific embodiments of the preparation method of carbon fiber tow and prepreg, and the beneficial effects of selecting the above-mentioned ranges of each process parameter will be explained by giving specific experimental data through specific embodiments.

[0089] Example

[0090] For ease of explanation, in the following embodiments, two bundles of 12k small-tow carbon fiber precursors are combined to form a 24k large-tow carbon fiber precursor; the carbon fiber tow of the first preset specification is 24k carbon fiber, and the carbon fiber tow precursor of the second preset specification is 12k carbon fiber precursor.

[0091] Embodiment 1: A method for preparing a carbon fiber tow, comprising the following steps:

[0092] (1) Two bundles of 12k carbon fiber tows are superimposed and combined through the wire path of the limiter to form a bundle of 24k carbon fiber intermediates; the carbon fiber intermediates are sequentially washed, hot water drawn, oiled, and dried ten times to form a pretreated carbon fiber tow. The washing temperature is 50°C; the oiling temperature is 20°C; the drying temperature is 150°C, and the pressure is 0.5MPa.

[0093] (2) The pretreated carbon fiber tow is sequentially passed through the first-stage limiting groove, the second-stage limiting groove, and the third-stage limiting groove of the combiner, and then sequentially subjected to steam drawing, yarn spreading, and winding to form a 24k carbon fiber tow precursor. The drawing multiple of the pretreated carbon fiber tow after the combiner is 0.8 times; the steam pressure of the steam drawing is 0.3 MPa; and the drawing multiple of the pretreated carbon fiber tow during yarn spreading is 0.8 times.

[0094] (3) The 24k carbon fiber tow precursor is subjected to pretreatment, low-temperature carbonization, and high-temperature carbonization in sequence to obtain a 24k carbon fiber tow. The temperature of the pre-oxidation treatment is 230°C, and the draft ratio is 0.8 times; both the low-temperature carbonization treatment and the high-temperature carbonization treatment adopt six temperature zones with step-by-step heating, the temperature of the highest temperature zone of the low-temperature carbonization treatment is 740°C, and the draft ratio is 0.9 times; the temperature of the highest temperature zone of the high-temperature carbonization treatment is 1350°C, and the draft ratio is 0.8 times.

[0095] In order to more clearly explain the technical solution of the present application, the present application also lists Examples 2-8 of carbon fiber tows, wherein the process parameters of Examples 2-8 are shown in Table 1.

[0096] Table 1 shows a specific embodiment of the carbon fiber tow in the present application. It should be noted that, except for the parameters listed in Table 1, other parameters of Examples 2-8 are substantially the same as those of Example 1.

[0097] Table 1 Process parameters of carbon fiber tow in Example

[0098]

[0099] Comparative Example

[0100] Comparative Example 1: The main difference between this comparative example and Example 1 is that the pretreated carbon fiber tow is not subjected to the second wire combining treatment of the wire combiner, as follows:

[0101] (1) Two bundles of 12k carbon fiber tows are superimposed and combined through the wire path of the limiter to form a bundle of 24k carbon fiber intermediates; the carbon fiber intermediates are sequentially washed, hot water drawn, oiled, and dried ten times to form a pretreated carbon fiber tow. The washing temperature is 50°C; the oiling temperature is 20°C; the drying temperature is 150°C, and the pressure is 0.5MPa.

[0102] (2) The pretreated carbon fiber tow is subjected to steam drawing, yarn spreading, and winding in sequence to form a 24k carbon fiber tow precursor, wherein the steam pressure of the steam drawing is 0.3 MPa; and the drawing multiple of the pretreated carbon fiber tow during yarn spreading is 0.8 times.

[0103] (3) The 24k carbon fiber tow precursor is subjected to pretreatment, low-temperature carbonization, and high-temperature carbonization in sequence to obtain a 24k carbon fiber tow. The temperature of the pre-oxidation treatment is 230°C, and the draft ratio is 0.8 times; both the low-temperature carbonization treatment and the high-temperature carbonization treatment adopt six temperature zones with step-by-step heating, the temperature of the highest temperature zone of the low-temperature carbonization treatment is 740°C, and the draft ratio is 0.9 times; the temperature of the highest temperature zone of the high-temperature carbonization treatment is 1350°C, and the draft ratio is 0.8 times.

[0104] Performance Testing

[0105] Large tow (24k) carbon fiber tows were prepared according to the methods of the embodiment and the comparative example, and the tensile strength and tensile modulus of large tow carbon fiber were tested according to GB / T 3362-2017 "Test method for tensile properties of carbon fiber multifilaments"; low gram weight (75g / m 2 ) prepreg, and the performance of the prepreg was tested, and the test results are shown in Table 2. Wherein, when preparing the prepreg, the twisting of the carbon fiber tow is 0.

[0106] Table 2 Performance test table of carbon fiber tow and prepreg of embodiment and comparative example

[0107]

[0108] Combining the data in Table 1 and Table 2, and combining Example 1 and Comparative Example 1, it can be seen that the carbon fiber tow prepared by Example 1 of the present application has higher mechanical properties. When the low-weight prepreg is prepared from the carbon fiber tow, no obvious flash seams between tows are observed, a small amount of flash seams within tows exist, and the withdrawal state is normal. It can be rated as grade A+, and the prepreg meets 75g / m 2 The mechanical properties of the carbon fiber tow prepared in Comparative Example 1 are relatively poor, and when the carbon fiber tow is used to prepare low-weight prepreg, the problem of fiber withdrawal and bifurcation is more obvious, and the prepreg cannot meet the requirements of 75g / m 2 Low weight.

[0109] It can be seen from Examples 1-8 that when preparing carbon fiber tows, changes in the process parameters of each step will have a certain impact on the mechanical properties of the carbon fiber tows and the flash seams between and within the prepreg tows. Among them, the carbon fiber tows of Examples 4-6 have better mechanical properties, and the problem of wire withdrawal and bifurcation is significantly improved when preparing low-weight prepregs.

[0110] In summary, the carbon fiber tow prepared by the method of the present application can be used for the preparation of low-weight prepregs, which effectively solves the problems of fiber withdrawal and bifurcation and flash seams between prepreg fabric tows, and meets the performance requirements of low-weight prepregs.

[0111] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0112] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application is described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features can be replaced by equivalents; 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 tow, characterized in that: The carbon fiber tow is a carbon fiber tow of a first preset specification, and the carbon fiber tow of the first preset specification has a tensile strength of 4500-5500 MPa, a tensile modulus of 240-265 GPa, and a bulk density of 1.78-1.82 g / cm 3 , wherein the first preset specification is 24k-80k.

2. The carbon fiber tow according to claim 1, characterized in that: When the carbon fiber tow of the first preset specification is 24k carbon fiber, the linear density of the carbon fiber is 1570-1630 g / km; When the carbon fiber tow of the first preset specification is 36k carbon fiber, the linear density of the carbon fiber is 1770-1830 g / km; When the carbon fiber tow of the first preset specification is 48k carbon fiber, the linear density of the carbon fiber is 3150-3250g / km.

3. A method for preparing a carbon fiber tow, characterized in that: The method for preparing the carbon fiber tow is used to prepare the carbon fiber tow according to any one of claims 1 to 2, and the method comprises: Combining a preset number of carbon fiber tow precursors of a second preset specification for the first time under a first preset condition to form a pretreated carbon fiber tow; The pretreated carbon fiber tow is combined for a second time under a second preset condition to form a carbon fiber tow precursor with a first preset specification; The carbon fiber tow precursor of the first preset specification is carbonized under a third preset condition to obtain the carbon fiber tow of the first preset specification, wherein the k number of the first preset specification is greater than the k number of the second preset specification.

4. The method for preparing carbon fiber tow according to claim 3, characterized in that: The method of combining a preset number of carbon fiber tow precursors of a second preset specification for the first time under a first preset condition to form a pretreated carbon fiber tow comprises: The preset number of carbon fiber tow precursors of the second preset specification are stacked and combined to form a carbon fiber tow intermediate; the carbon fiber tow intermediate is sequentially subjected to a preset number of washing, drawing, oiling and drying to form the pretreated carbon fiber tow.

5. The method for preparing a fiber tow according to claim 4, characterized in that: The water washing temperature is 40-60°C; The drawing temperature is 50-75°C; The oiling temperature is 20-30°C; The drying temperature is 150-210° C. and the pressure is 0.5-1.4 MPa.

6. The method for preparing carbon fiber tow according to claim 3, characterized in that: The second step of combining the pretreated carbon fiber tow under a second preset condition to form a carbon fiber tow precursor with a first preset specification comprises: The pretreated carbon fiber tow is sequentially passed through the first-stage limiting groove, the second-stage limiting groove, and the third-stage limiting groove of the combiner, and then sequentially subjected to steam drawing, yarn spreading, and winding to form the first preset specification carbon fiber tow precursor; The inner diameters of the first-stage limiting groove, the second-stage limiting groove, and the third-stage limiting groove decrease step by step; The inner diameter of the third-stage limiting groove matches the hole size of the steam drawing.

7. The method for preparing carbon fiber tow according to claim 6, characterized in that: The steam pressure of the steam drawing is 0.3-0.6MPa; The pretreated carbon fiber tow is stretched by 0.8-1.3 times after passing through the combiner; The drafting multiple of the pretreated carbon fiber tow during fiber spreading is 0.8-1.3 times.

8. The method for preparing carbon fiber tow according to claim 3, characterized in that: The step of carbonizing the carbon fiber tow precursor of the first preset specification under a third preset condition to obtain the carbon fiber tow of the first preset specification comprises: The carbon fiber tow precursor of the first preset specification is subjected to a pre-oxidation treatment, a low-temperature carbonization treatment, and a high-temperature carbonization treatment in sequence to obtain the carbon fiber tow of the first preset specification; The pre-oxidation treatment temperature is 230-280°C, and the drafting ratio is 0.8-1.2 times; The temperature of the low-temperature carbonization treatment is 400-850°C, and the draft ratio is 0.9-1.3 times; The temperature of the high temperature carbonization treatment is 900-1600° C., and the drafting ratio is 0.8-1.1 times.

9. A carbon fiber prepreg, characterized in that: The carbon fiber prepreg comprises a resin matrix and the carbon fiber tow according to any one of claims 1 to 2 or the carbon fiber tow prepared by the method for preparing a carbon fiber tow according to any one of claims 3 to 8; The carbon fiber prepreg has a gram weight of 50-100 g / m 2 .

10. The carbon fiber prepreg according to claim 9, characterized in that: The carbon fiber prepreg has a flash number of 0-5 between tows and a flash number of 0-5 within tows.

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