Preparation method of carbon fiber product and carbon fiber product

Abstract

The invention provides a preparation method of a carbon fiber product and the carbon fiber product. The preparation method of the carbon fiber product comprises the steps that a mold is pretreated, a highlight mold is obtained, and the surface roughness of the highlight mold is smaller than or equal to 0.05 m; a prepreg containing carbon fibers and the highlight mold are placed in a dust-free room, and the highlight mold is coated with the prepreg containing the carbon fibers; the highlight mold coated with the carbon fiber prepreg is placed in hot pressing equipment to be subjected to segmented hot pressing forming, and a carbon fiber prefabricated product is obtained; and performing size processing on the carbon fiber prefabricated product to obtain the carbon fiber product. When the preparation method disclosed by the embodiment of the invention is used for preparing the carbon fiber product, the carbon fiber product with high hardness and high glossiness can be obtained without secondary processing such as subsequent soil filling, grinding and coating.

Description

Technical Field

[0001] This disclosure relates to the field of carbon fiber product molding technology, specifically to a method for preparing carbon fiber products and carbon fiber products. Background Technology

[0002] Carbon fiber composites, due to their superior properties such as high specific strength, high specific modulus, and strong designability, have been widely used in aerospace, high-end automobiles, sporting goods, and consumer electronics. In these fields with stringent requirements for product appearance, the products not only need to possess excellent mechanical properties but also must have a high-quality surface finish, such as high gloss and no defects.

[0003] The typical process route for existing carbon fiber products is as follows: 1. Raw material preparation: Select carbon fiber tows and resin systems of specific specifications; 2. Prepreg manufacturing: For example, impregnate carbon fiber fabrics or unidirectional tapes with resin to produce prepregs with a certain viscosity and resin content; 3. Molding and curing: Lay the prepregs in a mold according to the design and cure them to obtain the basic preform of the composite material; 4. Post-processing and appearance repair: After the product is demolded, it needs to be post-processed, and multiple appearance repair processes such as puttying, grinding and coating are carried out to make the surface of the product achieve a high-gloss effect.

[0004] However, repeated repair, polishing and spraying operations rely heavily on the experience and operation of skilled workers, resulting in low production efficiency, a significant increase in labor and material costs, and the manual repair process makes it difficult to ensure consistent product appearance quality between different batches, or even within the same batch, leading to large fluctuations in product qualification rate. Summary of the Invention

[0005] In view of the above-mentioned problems in the prior art, the embodiments of this disclosure provide at least one method for preparing carbon fiber products, so as to obtain carbon fiber products that meet the requirements of high gloss surface effect after molding and curing, without subsequent coating process.

[0006] A first aspect of the embodiments of this disclosure provides a method for preparing a carbon fiber article, comprising:

[0007] The mold is pre-treated to obtain a high-gloss mold, wherein the surface roughness of the high-gloss mold is less than or equal to 0.05µm;

[0008] The carbon fiber-containing prepreg and the high-gloss mold are placed in a clean room, and the carbon fiber-containing prepreg is coated on the high-gloss mold.

[0009] A high-gloss mold coated with carbon fiber prepreg is placed in a hot press and hot-pressed in sections to obtain carbon fiber preforms; and

[0010] The carbon fiber preform is dimensionally processed to obtain the carbon fiber product.

[0011] According to an embodiment of this disclosure, the mold is an alloy steel mold, and the pretreatment of the mold to obtain a high-gloss mold includes: heat treatment of the polished mold; multi-stage polishing of the cavity surface of the heat-treated mold, wherein the last stage of polishing is performed using an abrasive material with a particle size greater than or equal to 2000 mesh; and surface treatment of the heat-treated mold to improve its wear resistance, thereby obtaining the high-gloss mold.

[0012] According to an embodiment of this disclosure, the hardness of the mold is greater than or equal to HRC37.

[0013] According to an embodiment of this disclosure, the mold is made of low-carbon alloy steel.

[0014] According to embodiments of this disclosure, the low-carbon alloy steel contains at least the following elements and amounts: 0.1% to 0.2% carbon, 3.0% to 3.4% nickel, 1.6% to 2.0% manganese, and 0.8% to 1.2% copper.

[0015] According to an embodiment of this disclosure, the cleanroom is a Class 100,000 cleanroom, and the method further includes: controlling the temperature of the cleanroom to 20°C to 28°C and the humidity to RH 45% to 65%.

[0016] According to embodiments of this disclosure, the step of placing a high-gloss mold coated with carbon fiber prepreg in a hot press and hot-pressing it in sections to obtain carbon fiber preforms includes: heating the high-gloss mold coated with carbon fiber prepreg to a first temperature, applying a first pressure for hot pressing, wherein the first temperature is 45℃~65℃, the first pressure is 10T~30T, and the holding time is 5-8min; raising the temperature to a second temperature, increasing the pressure from the first pressure to the second pressure and holding the pressure, wherein the second temperature is 65℃~100℃, the second pressure is 40T~80T, and the holding time is 8-10min; and continuing to raise the temperature to a third temperature, increasing the pressure from the second pressure to the third pressure and holding the pressure, wherein the third temperature is 120℃~180℃, the third pressure is 120T~150T, and the holding time is 12-20min.

[0017] According to embodiments of this disclosure, the prepreg containing carbon fibers comprises at least: carbon fibers and a resin composition, the resin composition comprising a mixture of epoxy resin, phenolic resin and polytetrafluoroethylene resin, the glass transition temperature of the resin composition being above 140°C, and the viscosity of the resin composition being 11000–16000 mPa·s.

[0018] According to an embodiment of this disclosure, the method further includes: after obtaining the high-gloss mold, applying a release agent to the cavity of the high-gloss mold, wherein the coating thickness of the release agent is less than or equal to 50 nm.

[0019] According to embodiments of this disclosure, the carbon fiber preform has a hardness greater than or equal to 6H and a gloss level greater than or equal to 92 GU.

[0020] A second aspect of the embodiments of this disclosure provides a carbon fiber article prepared using the method of the first aspect of the embodiments of this disclosure. Attached Figure Description

[0021] The above and other objects, features, and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings. Obviously, the drawings described below are some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any creative effort. In the drawings:

[0022] Figure 1 A flowchart illustrating a method for preparing a carbon fiber article according to an embodiment of the present disclosure is shown.

[0023] Figure 2 The flowchart illustrates a method for pre-treating an alloy steel mold to obtain a high-gloss mold according to an embodiment of the present disclosure.

[0024] Figure 3 A flowchart illustrating a segmented hot pressing process according to an embodiment of the present disclosure is shown.

[0025] Figure 4 A flowchart illustrating a method for preparing a carbon fiber article according to another embodiment of the present disclosure is shown.

[0026] Figure 5 A schematic diagram illustrating the appearance of a carbon fiber article according to an embodiment of the present disclosure is shown. Detailed Implementation

[0027] To make the above-disclosed objects, features, and advantages more apparent and understandable, specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, numerous specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0028] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0029] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0030] When using expressions such as "at least one of A, B, and C," it should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (e.g., "having at least one of A, B, and C" should include, but is not limited to, having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, features defined with "first" or "second" may explicitly or implicitly include one or more of the stated features.

[0031] In one exemplary embodiment of this disclosure, a method for preparing a carbon fiber article is provided. For example... Figure 1 As shown, the method includes steps S1 to S4:

[0032] Step S1: Pre-process the mold to obtain a high-gloss mold.

[0033] In embodiments of this disclosure, a specular mold refers to a mold with a mirror-like specular effect. This specular mold can clearly reflect the outline of an object, similar to a mirror reflection. Its surface roughness is less than or equal to 0.05µm. Under standard light source conditions, when measuring the object surface at an incident angle of 60°, the ratio of the specular reflected luminous flux to the luminous flux reflected by an ideal reference standard plate is greater than or equal to 120 GU.

[0034] In the embodiments of this disclosure, molds made of materials with extremely high purity, excellent homogeneity, and suitable hardness can be screened first. Then, a precise surface finishing process is used to improve the surface gloss of the original mold. Preferably, a precision polishing process can be used to obtain a high-gloss mold that meets the requirements of the embodiments of this disclosure. Optionally, after obtaining the original mold, heat treatment technology can be used to further process the mold to improve its toughness and strength.

[0035] Step S2: Place the prepreg containing carbon fibers and the high-gloss mold in a cleanroom, and coat the high-gloss mold with the prepreg containing carbon fibers. By coating the prepreg with carbon fibers in a cleanroom, it is possible to effectively prevent environmental suspended particulate matter from being encapsulated by the resin and cured inside the prepreg, thereby avoiding the adverse effects of impurities on the coating process and facilitating the acquisition of high-quality preformed structures.

[0036] In the coating of the prepreg, an exemplary method can be adopted as follows: Before the coating process begins, the environmental control system is activated in a cleanroom with a preset cleanliness level, controlling the environmental parameters to suitable temperature and humidity. For example, the temperature can be 15℃~35℃, optionally 18℃~30℃, and further optionally 20℃~28℃; the humidity can be RH 38%~70%, optionally RH 40%~68%, and further optionally 45%~65%. The cleanliness and pressure difference of the cleanroom are checked to ensure they meet the requirements. Electrostatic dust removal is performed on the fiber substrate. In the cleanroom, the resin composition is quantitatively applied to the surface of the dust-removed fiber substrate at a predetermined unit area weight. The resin-coated fiber substrate is passed through a temperature-controlled pressure roller to impregnate the fibers with resin. The areal density of the resulting prepreg is monitored in real time, and the resin coating amount is adjusted according to the monitoring results until coating is complete.

[0037] Step S3: Place the high-gloss mold coated with carbon fiber prepreg into a hot press and hot press it in sections, then demold to obtain the carbon fiber preform.

[0038] In the embodiments of this disclosure, the carbon fiber prepreg is subjected to segmented hot pressing, allowing the resin sufficient time and fluidity to fully impregnate the fiber bundles and expel interlayer bubbles. When the resin reaches its optimal viscosity window, higher pressure is applied to further compact the layers and expel residual gas, thereby reducing internal defects such as porosity and dry spots. Optionally, the segmented hot pressing can be a two-stage or three-stage process. In a two-stage process, the first stage of hot pressing fully impregnates the carbon fibers, and the second stage of hot pressing cures the resin in the prepreg to form a carbon fiber-resin composite material product.

[0039] Preferably, a three-stage hot pressing process can be used. In the first stage, the resin fully flows and impregnates the carbon fibers, preheating the prepreg in the laminate. After reaching the second stage temperature, the pressing pressure is rapidly increased to compact and limit the flow, expelling excess resin and reducing porosity. The temperature is then raised to the third stage temperature to completely cure the resin network. This three-stage, precise control of the resin curing process improves the uniformity and surface gloss of the carbon fiber preform.

[0040] In the embodiments of this disclosure, the pressure, temperature, and time in segmented hot pressing can be adjusted based on the resin formulation. The inventors of this disclosure have discovered that by selecting a resin composition with an appropriate viscosity, for example, a resin composition between 11000 mPa·s and 17000 mPa·s, and setting the second-stage hot pressing temperature to be comparable to the lowest viscosity temperature of the resin composition (i.e., the temperature at which the fluidity of the resin composition increases with increasing temperature below this temperature and decreases rapidly above this temperature), and setting the third-stage hot pressing temperature slightly higher than the glass transition temperature of the resin composition, for example, 20°C to 30°C above the glass transition temperature of the resin composition, better molding results and high gloss of the carbon fiber preforms can be achieved.

[0041] Step S4: Perform dimensional processing on the carbon fiber preform to obtain the carbon fiber product.

[0042] In the embodiments of this disclosure, after steps S1 to S3, the obtained carbon fiber preform has a high-gloss mirror effect. In step S4, only the carbon fiber preform needs to be dimensionally processed, without the need for subsequent processes such as puttying, grinding, and coating, which can save a lot of labor time and avoid dust pollution to the environment and grinding consumption of water.

[0043] Optionally, the mold is an alloy steel mold.

[0044] Figure 2 The flowchart illustrates a method for pre-treating an alloy steel mold to obtain a high-gloss mold according to an embodiment of the present disclosure.

[0045] In this embodiment, pre-processing the alloy steel mold to obtain a high-gloss mold includes steps S11 to S13.

[0046] Specifically, in step S11, the polished mold undergoes heat treatment. Typical heat treatment processes include quenching and tempering. For example, the mold is heated to above the austenitizing temperature, held at that temperature, and then cooled. Alternatively, it is heated to above the critical point AC3 or ACM, held at an appropriate temperature for a certain time, and then cooled in a cooling medium such as air / water / oil to improve toughness and strength.

[0047] Furthermore, in step S12, the cavity surface of the heat-treated mold is polished in multiple stages.

[0048] In embodiments of this disclosure, the final polishing stage is performed using an abrasive material with a particle size greater than or equal to 2000 mesh, so as to obtain a mold with a high-gloss mirror finish after the final polishing stage.

[0049] Optionally, a three-stage polishing method—rough polishing, fine polishing, and mirror polishing—can be used to polish the cavity surface of the mold. Further, a four-stage polishing method—rough polishing, medium-fine polishing, fine polishing, and mirror polishing—can be used to polish the cavity surface of the mold.

[0050] In one example, to achieve a high-gloss mirror finish, the polishing of the mold cavity employs a multi-stage progressive process, including but not limited to the following sequence: rough polishing with 300-grit sandpaper to remove machining marks; followed by medium-fine polishing with 800-grit sandpaper and 1500-grit diamond paste; and finally, fine polishing with 2000-grit diamond paste. Each step must be performed only after all scratches from the previous step have been completely removed, and the polishing direction should intersect with the texture direction of the previous step.

[0051] In step S13, the heat-treated mold undergoes surface treatment to improve its wear resistance, resulting in the high-gloss mold. Typical surface treatment processes may include coating the mold cavity with a wear-resistant layer, depositing a hard film, or performing surface diffusion modification. In one example, surface plating with hard metals such as chromium or titanium may be used. In another example, electroplating / coating with 2μm~5μm of chromium can improve the wear resistance of the mold surface.

[0052] After the above steps S11 to S13, a high-gloss mold with the required strength, gloss, and wear resistance can be obtained.

[0053] Preferably, the mold has a hardness greater than or equal to HRC37. In one embodiment of this disclosure, the mold is made of steel with a hardness greater than or equal to HRC37 to facilitate obtaining the high-gloss mold during pretreatment. More preferably, the mold is a low-carbon alloy steel mold containing uniformly hardened martensite, which can achieve a high-gloss mirror effect after multi-stage polishing.

[0054] In one example, low-carbon alloy steel contains the following components: 0.1% to 0.2% carbon, 3.0% to 3.4% nickel, 1.6% to 2.0% manganese, and 0.8% to 1.2% copper.

[0055] In an optional embodiment, the cleanroom is a Class 100,000 cleanroom, which meets ISO 8 cleanliness standards. During the coating process of the prepreg containing carbon fibers, the temperature of the cleanroom is controlled at 20°C to 28°C and the humidity at RH 45% to 65% to regulate the coating uniformity, wetting rate, and impregnation content on the fibers, which helps to improve the uniformity and stability of the prepreg quality.

[0056] Figure 3 A flowchart illustrating a segmented hot pressing process according to an embodiment of the present disclosure is shown.

[0057] According to embodiments of this disclosure, a high-gloss mold coated with carbon fiber prepreg is placed in a hot press and hot-pressed in sections to obtain carbon fiber preforms, including steps S31 to S33.

[0058] In step S31, the high-gloss mold coated with carbon fiber prepreg is heated to a first temperature and hot-pressed under a first pressure. The first temperature is 45℃~65℃, the first pressure is 10T~30T, and the holding time is 5-8min.

[0059] In step S32, the temperature is raised to a second temperature, the pressure is increased from the first pressure to the second pressure and held, the second temperature is 65℃~100℃, the second pressure is 40T~80T, and the holding time is 8-10min.

[0060] In step S33, the temperature is increased to a third temperature, the pressure is increased from the second pressure to the third pressure and held. The third temperature is 120℃~180℃, the third pressure is 120T~150T, and the holding time is 12-20min.

[0061] In the above embodiments, the carbon fiber prepreg comprises at least: carbon fiber and a resin composition. The resin composition is a mixture of epoxy resin, phenolic resin, and polytetrafluoroethylene resin, and the glass transition temperature of the resin composition is above 140°C, preferably above 150°C. The viscosity of the resin composition is 11000–16000 mPa·s.

[0062] The inventors of this disclosure have discovered that, in one embodiment, a prepreg prepared by combining a resin composition with the above parameters with carbon fiber can be obtained after segmented hot pressing, resulting in a carbon fiber preform with a hardness greater than or equal to 6H and a gloss level greater than or equal to 92GU.

[0063] In another embodiment, such as Figure 4 As shown, after step S3, step S5 is also included.

[0064] In step S5, after obtaining the high-gloss mold, a release agent is applied to the cavity of the high-gloss mold, and the thickness of the release agent coating is less than or equal to 50 nm. In this embodiment, applying a release agent to the cavity of the high-gloss mold prevents the cured carbon fiber preform from sticking to the mold. By applying a release agent with a thickness of less than or equal to 50 nm, the surface gloss of the preform can be avoided without affecting the dimensional accuracy of the carbon fiber preform.

[0065] Embodiments of this disclosure also provide a carbon fiber article. This carbon fiber article is prepared using the carbon fiber article preparation method of embodiments of this disclosure.

[0066] Figure 5 A schematic diagram illustrating the appearance of a carbon fiber article according to an embodiment of the present disclosure is shown. Figure 5 As shown, the carbon fiber product of this disclosure has a high-gloss mirror appearance. Testing shows that its hardness exceeds 6H and its gloss (60°) exceeds 92 GU. It can be seen that when preparing carbon fiber products using the preparation method of the embodiments of this disclosure, high-hardness, high-gloss carbon fiber products can be obtained without subsequent secondary processing such as puttying, grinding, or coating.

[0067] Unless otherwise specified, the numerical parameters in this specification and the appended claims are approximate values ​​and can be changed according to the desired characteristics obtained from the content of this disclosure. Specifically, all figures used in the specification and claims to indicate the content of composition, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. Generally, this means that there may be a variation of ±10% in some embodiments, ±5% in some embodiments, ±1% in some embodiments, and ±0.5% in some embodiments.

[0068] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

[0069] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A method for preparing carbon fiber products, characterized in that, include: The mold is pre-treated to obtain a high-gloss mold, wherein the surface roughness of the high-gloss mold is less than or equal to 0.05µm; The carbon fiber-containing prepreg and the high-gloss mold are placed in a clean room, and the carbon fiber-containing prepreg is coated on the high-gloss mold. A high-gloss mold coated with carbon fiber prepreg is placed in a hot press and hot-pressed in sections, then demolded to obtain carbon fiber preforms. as well as The carbon fiber preform is dimensionally processed to obtain the carbon fiber product.

2. The preparation method according to claim 1, characterized in that, The mold is an alloy steel mold, and the pretreatment of the mold to obtain a high-gloss mold includes: The polished mold is then subjected to heat treatment; The cavity surface of the heat-treated mold is polished in multiple stages, with the final stage polishing using abrasive material with a particle size of 2000 mesh or greater. The heat-treated mold is then subjected to surface treatment to improve its wear resistance, thereby obtaining the high-gloss mold.

3. The preparation method according to claim 2, characterized in that, The hardness of the mold is greater than or equal to HRC37.

4. The preparation method according to claim 2, characterized in that, The mold is made of low-carbon alloy steel.

5. The preparation method according to claim 4, characterized in that, The low-carbon alloy steel contains at least the following elements and amounts: 0.1% to 0.2% carbon, 3.0% to 3.4% nickel, 1.6% to 2.0% manganese, and 0.8% to 1.2% copper.

6. The preparation method according to claim 1, characterized in that, The cleanroom is a Class 100,000 cleanroom, and the method further includes: The temperature of the cleanroom is controlled at 20℃~28℃, and the humidity is controlled at RH 45%~65%.

7. The preparation method according to claim 1, characterized in that, The step of placing a high-gloss mold coated with carbon fiber prepreg in a hot press and hot-pressing it in sections to obtain carbon fiber preforms includes: The high-gloss mold coated with carbon fiber prepreg is heated to a first temperature and hot-pressed under a first pressure. The first temperature is 45℃~65℃, the first pressure is 10T~30T, and the holding time is 5-8min. The temperature is raised to a second temperature, and the pressure is increased from the first pressure to the second pressure and held. The second temperature is 65℃~100℃, the second pressure is 40T~80T, and the holding time is 8-10 minutes. Continue heating to the third temperature, increase the pressure from the second pressure to the third pressure and hold the pressure. The third temperature is 120℃~180℃, the third pressure is 120T~150T, and the holding time is 12-20min.

8. The preparation method according to claim 1, characterized in that, The prepreg containing carbon fibers comprises at least: carbon fibers and a resin composition, wherein the resin composition comprises a mixture of epoxy resin, phenolic resin and polytetrafluoroethylene resin, wherein the glass transition temperature of the resin composition is above 140°C, and the viscosity of the resin composition is 11000–16000 mPa·s.

9. The preparation method according to claim 1, characterized in that, The method further includes: After obtaining the high-gloss mold, a release agent is applied to the cavity of the high-gloss mold, and the coating thickness of the release agent is less than or equal to 50 nm.

10. The preparation method according to claim 1, characterized in that, The carbon fiber preform has a hardness greater than or equal to 6H and a gloss level greater than or equal to 92 GU.

11. A carbon fiber product, characterized in that, The carbon fiber product is prepared using the method described in any one of claims 1 to 10.

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