Preparation method of colored carbon fiber

Abstract

The present invention provides a method for preparing colored carbon fibers. The method comprises adding a cleaned carbon fiber substrate to a carbohydrate carbon source solution, and forming a carbon microsphere layer on the surface of the carbon fibers after a high-temperature carbonization reaction. The colored carbon fibers are then rinsed to obtain the colored carbon fibers. The method forms a carbon microsphere layer directly on the surface of the carbon fibers through the high-temperature carbonization principle, thereby obtaining structurally colored carbon fibers. The carbon microspheres have a strong binding force with the carbon fiber surface, and the resulting carbon fibers have a long-lasting color. The carbon source used is a widely available biomass carbohydrate, which is simple, easy to obtain, pollution-free, and has a low preparation cost. The carbon fiber color can be regulated by controlling the particle size and number of the carbon microspheres on the surface of the carbon fibers through the carbon source concentration, carbon source filling degree, reaction temperature, and reaction time. The obtained carbon fibers have rich colors, a simple process flow, low requirements on reaction equipment during the preparation process, mild reaction conditions, a short production cycle, and low production costs, making the fibers suitable for industrialized production.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon fiber coloring, and in particular to a method for preparing colored carbon fiber. Background Art

[0002] With the continuous development of science and technology and the improvement of people's living standards, fibers are widely processed and utilized, and textile materials are becoming increasingly colorful. As a new type of fiber, carbon fiber is mainly composed of carbon elements, and its carbon content is generally above 90%. Carbon fiber has excellent properties such as high specific strength, high specific modulus, corrosion resistance, high temperature resistance, high fatigue strength, electrical conductivity and thermal conductivity, and electromagnetic wave shielding, and is widely used in national defense and military industry, aerospace, transportation, civil engineering, conductor composite core, sports equipment and high-tech industries. At the same time, carbon fiber also has the softness and processability of textile fibers. Therefore, carbon fiber can be widely used in textile clothing and membrane materials.

[0003] Because carbon fiber is primarily composed of carbon, the resulting products are typically black, which can easily cause visual fatigue and fail to meet the needs of daily life and production. Consequently, the production of colored carbon fiber has attracted increasing attention. However, the limited number and variety of functional groups on the surface of carbon fiber makes it chemically inert, making dyeing of this low-reactivity carbon fiber difficult.

[0004] The traditional dye coloring method is to manually adhere pigments and coatings to the surface of carbon fiber for coloring. The preparation of dyes in this process is generally synthesized by chemical methods. When coloring carbon fiber, a large amount of toxic chemical dyes and a large amount of water are often used, causing environmental pollution and wasting water resources. In addition, it is very difficult to artificially color carbon fiber.

[0005] Currently, the most widely used method is structural coloring, which mainly deposits oxides on the surface of carbon fibers or forms a thin film on the surface of carbon fibers using an in-situ polymerization grafting method. It does not require chemical dye coloring. Through the structural characteristics of the object itself, white light undergoes physical processes such as interference, diffraction, and scattering, thereby causing light of a certain color to be reflected back more strongly, producing color. Invention patent application number CN201510127348.1 discloses a method for preparing colored carbon fibers based on a ring-based polyphosphazene film. The method activates the carbon fiber surface and uses an in-situ polymerization grafting method to introduce a ring-clustered polyphosphazene film on the carbon fiber surface to prepare blue carbon fibers. However, the colored carbon fibers obtained by this method have uneven surface film thickness, resulting in uneven color and relatively weak color brightness. The invention patent with application number CN201810557206.2 discloses a colored carbon fiber material based on one-dimensional photonic crystals and its preparation method. Atomic layer deposition is used to alternately deposit thin films with high and low refractive indices on the surface of the carbon fiber material to construct a one-dimensional photonic crystal, so that the surface of the carbon fiber material presents a bright structural color. However, this method has a long cycle and needs to be carried out in an inert gas and atomic layer deposition equipment. The reaction conditions are high and it cannot be used for large-scale production.

[0006] Currently, few methods have been reported for forming structural colors on carbon fiber surfaces using simple equipment and mild reaction conditions. Due to the chemical inertness of the carbon fiber surface, activation treatment is required to deposit inorganic substances on the carbon fiber surface through a mild reaction. This increases preparation costs and limits the choice of inorganic raw materials.

[0007] In view of this, it is necessary to design an improved method for preparing colored carbon fiber to solve the above problems. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for preparing colored carbon fiber, so as to solve the problems that the existing preparation process of colored carbon fiber has high requirements on machinery and equipment, harsh experimental conditions, long production cycle, high production cost, insufficient color brightness of the obtained carbon fiber, and cannot be produced on a large scale.

[0009] To achieve the above-mentioned object of the invention, the present invention provides a method for preparing colored carbon fiber, comprising the following steps:

[0010] S1. Pretreatment of carbon fiber: cleaning the carbon fiber to remove surface impurities to obtain a clean surface of carbon fiber;

[0011] S2. Preparation of carbon source solution: dissolving the carbohydrate carbon source in a certain amount of deionized water to obtain a carbon source solution with a concentration of 10 to 400 g / L;

[0012] S3. Preparation of colored carbon fiber: The cleaned carbon fiber obtained in step S1 is placed in a closed reactor containing the carbon source solution in step S2, soaked for a preset time, and then carbonized at a temperature of 180-250°C for a preset time. After cooling naturally, the carbon fiber is taken out to obtain colored carbon fiber.

[0013] As a further improvement of the present invention, in step S2, the sugar is a monosaccharide, a disaccharide or a polysaccharide; the monosaccharide includes glucose, fructose, and xylose; the disaccharide includes sucrose and maltose; and the polysaccharide includes cyclodextrin and starch.

[0014] As a further improvement of the present invention, in step S2, the dissolution is to dissolve the sugar carbon source in deionized water or an organic solvent / deionized water system; the organic solvent is ethanol or isopropanol; the volume ratio of the organic solvent / deionized water is (0:100%) to (30%:70%).

[0015] As a further improvement of the present invention, in step S3, the preset time of the carbonization reaction is 1 to 12 hours, and the carbonization reaction is carried out by placing the closed reactor in a high-temperature environment.

[0016] As a further improvement of the present invention, in step S3, the volume of the carbon source solution is 10% to 70% of the volume of the closed reactor.

[0017] As a further improvement of the present invention, in step S3, the preset soaking time is 1 to 60 minutes and the temperature is 15 to 60°C.

[0018] As a further improvement of the present invention, in step S3, the carbonization reaction is carried out by placing the closed reactor in a high-temperature environment.

[0019] As a further improvement of the present invention, in step S1, the cleaning is carried out by soaking in a mixed solution of ethanol, acetone and deionized water in a volume ratio of 1:1:(0.5~8) for 6~48 hours; in step S2, the dissolution is carried out in a stirrer, and the stirrer speed is 50~850r / min.

[0020] As a further improvement of the present invention, a method for preparing colored carbon fiber further includes the following steps:

[0021] S4. Post-processing of colored carbon fibers: washing and drying the colored carbon fibers obtained in step S3 to obtain clean colored carbon fibers.

[0022] As a further improvement of the present invention, in step S4, the cleaning is first performed with deionized water, then rinsed in an alkaline solution, and finally washed with deionized water until the residual liquid is neutral.

[0023] As a further improvement of the present invention, in step S4, the alkaline solution is 10 wt% to 50 wt% ammonia water; the rinsing time is 5 to 240 minutes, and the rinsing temperature is 15 to 60°C.

[0024] The beneficial effects of the present invention are:

[0025] (1) The present invention provides a method for preparing colored carbon fibers, which uses sugars as a carbon source and directly grows a layer of carbon microspheres in situ on the surface of the carbon fibers through the principle of high-temperature carbonization reaction, thereby obtaining structurally colored colored carbon fibers. Due to the hydrophobic similarity between sugar molecules and carbon fibers, the carbon microspheres generated in this process can have a strong binding force with the surface of the carbon fibers without the need to activate the carbon fibers. The carbon microspheres are not easy to fall off, and the color of the generated carbon fibers is long-lasting. The research results of the present invention also show that the growth process of the carbon microspheres and the bonding strength between the carbon microspheres and the carbon fibers also have an important influence on the color development effect. In addition, the carbon source used is a widely available biomass sugar, which is simple and easy to obtain, pollution-free, and has a low preparation cost.

[0026] (2) The present invention provides a method for preparing colored carbon fibers. By adjusting the carbon source concentration, carbon source filling degree, reaction temperature and reaction time, the particle size and number of carbon microspheres generated on the carbon fiber surface are controlled, thereby controlling the macrostructure of the carbon microsphere layer on the carbon fiber surface, and further controlling the color rendering effect of the carbon fiber. The microscopic shape and molecular structure of the organic carbon microsphere layer give the carbon fibers richer colors, and the colors are easy to control.

[0027] (3) The present invention provides a method for preparing colored carbon fiber, which has a simple process flow, the reaction is carried out in an aqueous solution, and there is no need for preliminary drying of the raw materials. The preparation process has low requirements for reaction equipment and the reaction conditions are mild.

[0028] (4) The method for preparing colored carbon fiber provided by the present invention has a fast reaction speed, a short production cycle, simple reaction raw materials, and a low production cost, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Scanning electron microscope images of carbon fibers after treatment with three different concentrations of carbon sources.

[0030] Figure 2 This is the infrared spectrum of carbon microspheres generated by high-temperature reaction of glucose and glucose solution.

[0031] Figure 3 This is a picture of the colored carbon fiber prepared in Example 3. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] It should also be noted here that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0034] In addition, it should be noted that 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 includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0035] The present invention provides a method for preparing colored carbon fiber, comprising the following steps:

[0036] S1. Pretreatment of carbon fiber:

[0037] Ethanol, acetone and deionized water are placed in an ultrasonic treatment at a volume ratio of 1.0:1.0:(0.5~8.0) to obtain a uniform mixed solution. The mixed solution is prepared by mixing organic solvents and inorganic solvents. The proportion of each substance in the mixed solution is adjusted according to the different types of impurities on the surface of the carbon fiber. The solubility of impurities on the surface of the carbon fiber in the mixed solution can be increased, which is beneficial to the cleaning of the carbon fiber and facilitates the bonding of carbon microspheres to the surface of the carbon fiber. The carbon fiber substrate (such as carbon fiber or carbon fiber fabric) is placed in the obtained mixed solution and soaked for 6~48h to remove impurities such as the glue layer and its attachments on the surface of the carbon fiber to obtain a carbon fiber with a clean surface. The soaking temperature is controlled at 15~60℃, preferably at 25~45℃, because when the soaking temperature is low, the impurities on the surface of the carbon fiber dissolve slowly, the cleaning speed is slow, and it takes a long time; high temperature can accelerate the dissolution of impurities and thus increase the cleaning speed, but too high a temperature will cause the evaporation of the organic solvent and deteriorate the working environment.

[0038] S2. Preparation of carbon source solution:

[0039] The carbohydrate carbon source is added to a certain amount of solvent system and placed in a stirrer for 10 to 50 minutes. The solvent system is deionized water or an organic solvent / deionized water system, wherein the organic solvent is ethanol or isopropanol, and the volume ratio of the organic solvent / deionized water is (0:100%) to (30%:70%). The stirrer speed is controlled at 50 to 850 r / min to obtain a carbon source solution with a concentration of 10 to 400 g / L. By adjusting the concentration of the carbon source solution, the particle size and number of the carbon microspheres generated by high-temperature carbonization are controlled, and ultimately the particle size and number of the carbon microspheres bound to the carbon fiber surface are different, and carbon fibers of different colors are prepared. As the carbon source concentration increases, the particle size of the carbon microspheres generated by high-temperature carbonization is larger and the number increases, and the color of the obtained colored carbon fibers is more vivid.

[0040] With the increase of carbon source concentration, the carbon microspheres generated by high-temperature carbonization have larger particle sizes and more in number, and the color of the obtained colored carbon fibers is brighter.

[0041] The sugars used can be monosaccharides, disaccharides or polysaccharides; monosaccharides include glucose, fructose, and xylose; disaccharides include sucrose and maltose; and polysaccharides include cyclodextrin and starch. Selecting sugars with a wide range of sources as carbon sources can reduce production costs.

[0042] S3. Preparation of colored carbon fibers:

[0043] The surface-cleaned carbon fiber obtained in step S1 is placed in a closed reactor containing the carbon source solution of step S2, ensuring that the volume of the carbon source solution is 10% to 70% of the closed reactor volume (i.e., the filling degree of the carbon source solution is 10% to 70%, filling degree = carbon source solution volume / reactor total volume × 100%. The filling degree can be used to control the pressure of the reaction process to a certain extent, thereby affecting the carbonization reaction product and ultimately affecting the color of the colored carbon fiber). The carbon fiber is first soaked in a closed reactor for 1 to 60 minutes, and the soaking temperature is controlled at 15 to 60°C to fully contact the carbon source solution with the carbon fiber, so that the generated carbon microspheres are evenly distributed on the surface of the carbon fiber. After soaking, the closed reactor containing the carbon fiber and the carbon source solution is moved into a high temperature environment and the temperature is controlled to react at 180 to 250°C for 1 to 12 hours. The high temperature accelerates the reaction speed, and the obtained colored carbon fiber has different colors. The carbon source undergoes intermolecular condensation polymerization in the solution to form carbon microspheres with a certain microstructure on the surface of the carbon fiber. These carbon microspheres are tightly attached to the surface of the carbon fiber and will not fall off easily. They are taken out after natural cooling. Colored carbon fibers of different colors are obtained according to the effect of carbon microspheres of different particle sizes and quantities on light.

[0044] S4. Post-processing of colored carbon fiber:

[0045] The colored carbon fiber obtained in step S3 is first washed with deionized water to preliminarily wash away the unreacted carbon source solution on the surface of the carbon fiber and the carbon microspheres that are not adhered to the surface of the carbon fiber; then placed in 10wt% to 50wt% ammonia water and rinsed for 5 to 240 minutes at a rinsing temperature of 15 to 60°C to further wash away the carbon microspheres that are not completely adhered to the surface of the carbon fiber. Preferably, 15wt% to 30wt% ammonia water is used. Ammonia water with an appropriate mass concentration can quickly wash away the carbon microspheres that are not completely adhered to the surface of the carbon fiber. During use, ammonia volatilizes less, the operating environment is better, and the subsequent water washing operation is simpler; finally, deionized water is used to wash away the ammonia remaining on the surface of the carbon fiber until the residual liquid is neutral, and the colored carbon fiber is obtained after drying at 30 to 80°C.

[0046] In some embodiments, the carbon fiber fabric is processed to obtain a colored carbon fiber fabric.

[0047] The present invention is described in detail below through a number of embodiments:

[0048] Example 1

[0049] S1. Pretreatment of carbon fiber:

[0050] Ethanol, acetone, and deionized water are mixed in an ultrasonic bath at a volume ratio of 1:1:3 to obtain a uniform mixed solution. The carbon fibers are then immersed in the resulting mixed solution for 28 hours at a temperature of 28°C to remove impurities such as the adhesive layer and its attachments on the carbon fiber surface. The cleaned carbon fibers or carbon fiber fabrics are then dried to obtain carbon fibers with a clean surface.

[0051] S2. Preparation of carbon source solution:

[0052] Glucose was added to a certain amount of deionized water and placed in a stirrer and stirred for 30 minutes. The stirrer speed was controlled at 300 r / min to prepare a carbon source solution with a glucose concentration of 60 g / L.

[0053] S3. Preparation of colored carbon fibers:

[0054] The cleaned carbon fibers obtained in step S1 and the glucose solution obtained in step S2 were placed in a reactor with a glucose solution filling degree of 50%. The carbon fibers were first soaked in the reactor for 30 minutes at a temperature of 28°C to allow the carbon fibers and the glucose solution to be thoroughly mixed. The reactor was then placed in a high-temperature oven at 195°C for 1.5 hours, and then removed from the oven after natural cooling to obtain the product.

[0055] like Figure 2 The infrared spectrum of the carbon microspheres (scraped from the colored carbon fibers prepared in Example 1) generated by the high-temperature reaction of glucose and glucose solution shown in FIG: Before the reaction, the solution was mainly composed of glucose, and the infrared spectrum was Figure 2 Curve a, 3300cm from a -1 The broad and strong peaks show the characteristic peaks of hydroxyl groups in glucose. Due to the influence of multiple hydroxyl groups in its own structure, the absorption peak of carbonyl group is weak. The infrared spectrum of the product after high temperature reaction of glucose is as follows: Figure 2 In the middle b curve, the characteristic peaks of functional groups such as hydroxyl groups disappear, and the glucose solution undergoes polymerization reaction at high temperature to form aromatic compounds and oligosaccharides. Subsequently, oligosaccharides or macromolecules undergo intermolecular dehydration to induce cross-linking reactions. When the carbonization process reaches the critical saturation value, explosive nucleation occurs in the system, and the formed carbon nuclei grow isotropically through diffusion to finally obtain a uniform carbon microsphere structure.

[0056] S4. Post-processing of colored carbon fiber:

[0057] The colored carbon fiber obtained in step S3 is first washed with deionized water, then rinsed in 25wt% ammonia water for 120 min at a temperature of 28°C, and finally washed with deionized water until the residual liquid is neutral, and dried at 60°C to obtain the colored carbon fiber.

[0058] Examples 2-3

[0059] A method for preparing colored carbon fiber, compared with Example 1, is different in that, in step S2, the concentrations of the glucose solution are different, namely 150 g / L and 250 g / L, respectively. The rest are substantially the same as Example 1 and will not be repeated here.

[0060] Figure 1 Figures a, b, and c are scanning electron micrographs of the carbon fiber surface after treatment with 60 g / L, 130 g / L, and 220 g / L glucose solutions, respectively (scales for a1, b1, and c1 are 5 μm, and scales for a2, b2, and c2 are 1 μm). As can be seen from the figure, as the concentration of the glucose solution increases, the number of carbon microspheres attached to the carbon fiber surface increases, and the particle size also increases.

[0061] Figure 3 The color carbon fiber image prepared in Example 3 of the present invention is Figure 3 It can be seen from the figure that the colored carbon fiber has uniform color and obvious color rendering effect.

[0062] In summary, the present invention provides a method for preparing colored carbon fiber, which directly forms a layer of carbon microspheres on the surface of the carbon fiber through the principle of high-temperature carbonization reaction, thereby obtaining structurally colored colored carbon fiber. This process does not require activation of the carbon fiber, and the generated carbon microspheres have strong bonding force with the carbon fiber surface, are not easy to fall off, and the generated carbon fiber has a long-lasting color; the carbon source used is a biomass sugar with a wide source, which is simple and easy to obtain, pollution-free, and has a low preparation cost; by adjusting the carbon source concentration, carbon source filling degree, reaction temperature and reaction time, the particle size and number of carbon microspheres generated on the carbon fiber surface are controlled, thereby controlling the macrostructure of the carbon microsphere layer on the carbon fiber surface, and then controlling the color development effect of the carbon fiber, and the obtained carbon fiber has rich color varieties and is easy to control; the reaction is carried out in an aqueous solution, and there is no need for preliminary drying of the raw materials. The process flow is simple, the preparation process has low requirements for reaction equipment, the reaction conditions are mild, the production cycle is short, the production cost is low, and it is suitable for large-scale industrial production.

[0063] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing colored carbon fiber, characterized in that: The following steps are involved: S1. Pretreatment of carbon fiber: cleaning the carbon fiber substrate to remove surface impurities to obtain a clean surface of carbon fiber; The cleaning step is to soak the sample in a mixed solution of ethanol, acetone and deionized water in a volume ratio of 1:1:(0.5-8) for 6-48 hours; S2. Preparation of a carbon source solution: dissolving a carbohydrate carbon source to obtain a carbon source solution having a concentration of 60 to 250 g / L; the carbohydrate carbon source is glucose; the dissolution is performed by dissolving the carbohydrate carbon source in deionized water or an organic solvent / deionized water system; the organic solvent is ethanol or isopropanol; and the volume ratio of the organic solvent / deionized water is (0:100%) to (30%:70%). S3. Preparation of colored carbon fiber: The cleaned carbon fiber obtained in step S1 is placed in a closed reactor containing the carbon source solution in step S2, soaked for a preset time, and then carbonized at a temperature of 180 to 250°C for a preset time. After natural cooling, the carbon fiber is taken out to obtain colored carbon fiber; the volume of the carbon source solution is 50% of the volume of the closed reactor; the preset soaking time is 30 minutes, and the temperature is 15 to 60°C; the preset carbonization reaction time is 1 to 12 hours, and the carbonization reaction is carried out in a high-temperature environment in the closed reactor; S4. Post-processing of colored carbon fibers: washing and drying the colored carbon fibers obtained in step S3 to obtain clean colored carbon fibers.

2. The method for preparing colored carbon fiber according to claim 1, wherein: In step S2, the dissolution is carried out in a stirrer, and the rotation speed of the stirrer is 50 to 850 r / min.

3. The method for preparing colored carbon fiber according to claim 1, wherein: In step S4, the cleaning is first performed with deionized water, then rinsed in an alkaline solution, and finally washed with deionized water until the residual liquid is neutral.

4. The method for preparing colored carbon fiber according to claim 3, characterized in that: In step S4, the alkaline solution is 10 wt% to 50 wt% ammonia water; the rinsing time is 5 to 240 minutes, and the rinsing temperature is 15 to 60°C.

Images