Carbon fiber sizing agent for vinyl resin and preparation process of carbon fiber sizing agent

Abstract

The invention belongs to the technical field of carbon fiber sizing agents, and particularly discloses a carbon fiber sizing agent for vinyl resin and a preparation process thereof, the sizing agent comprises the following raw materials by mass: 15-30 parts of epoxy vinyl resin / or phenolic vinyl resin, 12-20 parts of an emulsifier and a cosurfactant, and 50-70 parts of deionized water. The monodisperse sizing agent emulsion with the median particle size smaller than 200nm is directly prepared by selecting and matching the multi-layer emulsifier and the cosurfactant and combining fine regulation and control of an emulsification process, and the emulsion has excellent stability and has an excellent sizing effect on 48K large-tow carbon fibers.

Description

Technical Field

[0001] The present invention relates to the field of carbon fiber sizing agents, and more particularly to a carbon fiber sizing agent for vinyl resin and its preparation process. Background Art

[0002] Carbon fiber is a high-performance fiber material prepared from polyacrylonitrile, viscose or pitch-based fibers as precursors through processes such as pre-oxidation and carbonization. Its interior is mainly composed of large-sized graphite-like lamellar structures stacked along the fiber axis, with a carbon element content higher than 98%. This physical and chemical structure endows it with excellent specific strength, specific modulus, chemical resistance, low linear thermal expansion coefficient, etc., and is widely used in fields such as aerospace and high-end equipment manufacturing. Compared with traditional structural materials, carbon fiber composites have significant advantages such as thermal stability, chemical corrosion resistance, and lightweight. However, there are still several technical challenges in the practical application of carbon fiber materials. First, carbon fiber exhibits greater brittleness and is prone to problems such as hairiness and single-filament breakage during processing. Second, the graphite structure of carbon fiber is perfect, with fewer non-carbon elements and active functional groups, and strong chemical inertness, resulting in poor interfacial compatibility between it and the resin matrix, which directly affects the overall performance of the composite material. In this context, the application of sizing agents is particularly important. On the one hand, the sizing agent can form an organic polymer layer on the surface of carbon fiber, optimize the wear resistance, bundling, and spreading properties of carbon fiber, and adjust the dryness and elasticity of the fiber. This surface modification can effectively inhibit the generation of hairiness during the post-processing and use of carbon fiber, making it better adapt to the requirements of processes such as weaving, laying, and winding during the molding of composite materials. On the other hand, the functional organic polymer layer formed by the sizing agent on the inert carbon fiber surface can also significantly improve the wettability and bonding ability between the fiber and the matrix. During the molding process of the composite material, this modification helps to form a good fiber-matrix interface, thereby improving the interfacial bonding strength and the interfacial shear strength of the composite material.

[0003] Currently, patents on sizing agents for carbon fibers used in vinyl resins mainly involve the formulation design of emulsifiers, such as adjusting the types and contents of matrix resins and emulsifiers (CN 119083181 A, CN 118792885 A, CN 119061695 A, CN117385641A, CN 117702487 A, CN 118273124 A, etc.), to obtain sizing agents with different functions or types, such as heat-resistant sizing agents, bio-based sizing agents, wear-resistant sizing agents, etc. However, the preparation process of the sizing agent has not been studied or disclosed in depth and systematically, and at the same time, the control of the emulsion particle size in the sizing agent has been ignored. In fact, the size of the emulsion particles in the sizing agent directly affects its application effect. Generally, the smaller the emulsion particle size, the better the stability and permeability of the emulsion, which is more suitable for large tow carbon fibers and is also conducive to forming a uniform and dense coating layer to enhance interfacial chemical bonding. At present, the preparation of sizing agents with small emulsion particle sizes (less than 200 nm) mainly relies on post-treatment technologies and cannot be directly prepared. For example, Chinese patent CN116837632B uses ultrasonic dispersion to post-treat the sizing agent to obtain an emulsion with a smaller particle size and good stability, and Chinese patent CN118792885A uses an auxiliary solvent evaporation method to prepare a sizing agent emulsion with a small particle size.

[0004] Through the selection and matching of multi-level emulsifiers and co-surfactants, combined with the fine control of the emulsification process, the present invention directly prepares a monodisperse sizing agent emulsion with a median particle size of less than 200 nm. The emulsion has excellent stability and excellent sizing effect on 48K large tow carbon fibers. Summary of the Invention

[0005] The purpose of the present invention is to provide a sizing agent for carbon fibers used in vinyl resins. Providing its preparation method is the second invention purpose of the present invention. The sizing agent prepared by the present invention has a smaller emulsion particle size and good stability, and can achieve excellent sizing effect on 48K large tow carbon fibers.

[0006] To achieve the above invention purposes, the present invention adopts the following technical solutions:

[0007] A sizing agent for carbon fibers used in vinyl resins, in parts by mass, its raw material composition is: 15 - 30 parts of epoxy vinyl resin and / or phenolic vinyl resin, 12 - 20 parts of emulsifier and co-surfactant, and 50 - 70 parts of deionized water.

[0008] Preferably, the emulsifier is one or a mixture of two or more of polyoxyethylene cetyl ether, sodium decyl sulfate, sodium dodecyl sulfonate, sodium oleate, potassium oleate, and the Tween series.

[0009] Preferably, the co-surfactant is one of n-butanol, n-pentanol, and n-hexanol.

[0010] Preferably, the emulsifier is a mixture of polyoxyethylene cetyl ether and sodium decyl sulfate, and the co-surfactant is n-hexanol. By mass, the weight composition of the emulsifier and the co-surfactant is 80-90 parts of polyoxyethylene cetyl ether, 5-10 parts of sodium decyl sulfate, and 5-10 parts of n-hexanol.

[0011] As the second inventive aspect of the present invention, the present invention provides a method for preparing the sizing agent for carbon fiber for the above vinyl resin, comprising the following steps:

[0012] 1) Mix epoxy vinyl resin and / or phenolic vinyl resin, emulsifier and co-surfactant to obtain a vinyl resin mixture;

[0013] 2) Under the condition of constant temperature heating, dropwise add deionized water to the vinyl resin mixture obtained in step 1) and stir and mix until the addition of deionized water is completed, and then cool to room temperature to obtain the sizing agent.

[0014] Preferably, in step 2), the heating temperature is 60-80 °C, the dropping rate of deionized water is 0.5-1 mL / min, and the stirring speed is 16000-20000 rpm.

[0015] Compared with the prior art, the beneficial features of the present invention are as follows:

[0016] The present invention prepares a sizing agent emulsion with smaller particle size and good stability by selecting and matching multi-level emulsifiers and co-surfactants and combining the fine regulation of the emulsification process (high-speed shearing and dropping speed). The schematic structural diagram is as Figure 2 shown, and it has excellent sizing effect on 48K large tow carbon fiber, which provides a key basis for the optimization of the sizing process and effect of large tow carbon fiber. Description of the Drawings

[0017] Figure 1 is the SEM diagram of the sizing effect of the original carbon fiber and the carbon fiber sizing agent in Examples 1-2;

[0018] Figure 2 is the schematic diagram of the emulsion droplets of the multi-level structure of the present invention. Detailed Embodiments

[0019] The present invention will be further described in detail below by combining examples. The following examples are only descriptive and not restrictive, and the protection scope of the present invention cannot be limited thereby.

[0020] Unless otherwise specified, the raw materials in the examples of this application are all purchased through commercial channels. It should be noted that the room temperature mentioned in the present invention refers to 20-30 °C, and the effects of the present invention can be achieved.

[0021] Example 1

[0022] A sizing agent for carbon fiber used in vinyl resin, calculated by mass fraction, its raw material composition includes: 15 parts of epoxy vinyl resin, 15 parts of emulsifier and co-surfactant (compounded by polyoxyethylene cetyl ether, sodium dodecyl sulfate and n-hexanol according to the mass ratio of 80:10:10), and 70 parts of deionized water.

[0023] The preparation process of the above sizing agent for carbon fiber used in vinyl resin includes the following steps:

[0024] 1) Weigh the epoxy vinyl resin, emulsifier and co-surfactant according to the formula, stir evenly and set aside;

[0025] 2) Weigh the deionized water according to the formula. Under the heating condition of 60 °C, add the deionized water to the vinyl resin mixture obtained in step 1 at a speed of 0.5 mL / min, and mix it with an emulsifier at a rotation speed of 20000 rpm. After adding all the deionized water, cool it to room temperature to obtain the sizing agent.

[0026] Example 2

[0027] A sizing agent for carbon fiber used in vinyl resin, calculated by mass fraction, its raw material composition includes: 15 parts of epoxy vinyl resin, 15 parts of emulsifier and co-surfactant (compounded by polyoxyethylene cetyl ether, sodium dodecyl sulfate and n-hexanol according to the mass ratio of 80:10:10), and 70 parts of deionized water.

[0028] The preparation process of the above sizing agent for carbon fiber used in vinyl resin includes the following steps:

[0029] 1) Weigh the epoxy vinyl resin, emulsifier and co-surfactant according to the formula, stir evenly and set aside;

[0030] 2) Weigh the deionized water according to the formula. Under the heating condition of 70 °C, add the deionized water to the vinyl resin mixture obtained in step 1 at a speed of 1 mL / min, mix it with an emulsifier at a rotation speed of 16000 rpm. After adding all the deionized water, cool it to room temperature to obtain the sizing agent.

[0031] Example 3

[0032] A sizing agent for carbon fiber used in vinyl resin, calculated by mass fraction, its raw material composition includes: 18 parts of epoxy vinyl resin, 12 parts of emulsifier (compounded by polyoxyethylene cetyl ether, sodium dodecyl sulfate and n-hexanol according to the mass ratio of 80:10:10), and 70 parts of deionized water.

[0033] The preparation process of the above sizing agent for carbon fiber used in vinyl resin includes the following steps:

[0034] 1) Weigh the epoxy vinyl resin, emulsifier and co-surfactant according to the formula, stir evenly and set aside.

[0035] 2) Weigh deionized water according to the formula. Under the heating condition of 60 °C, slowly add the deionized water to the vinyl resin mixture obtained in step 1) at a rate of 0.5 mL / min. Mix with an emulsifier at a rotation speed of 20000 rpm. After adding all the deionized water, cool to room temperature to obtain the sizing agent.

[0036] Example 4

[0037] A sizing agent for carbon fiber used in vinyl resin, calculated by mass, its raw material composition includes: 18 parts of epoxy vinyl resin, 12 parts of emulsifier and co-surfactant (compounded by polyoxyethylene cetyl ether, sodium dodecyl sulfate and n-hexanol according to the mass ratio of 90:5:5), and 70 parts of deionized water.

[0038] The preparation process of the above sizing agent for carbon fiber used in vinyl resin includes the following steps:

[0039] 1) Weigh the epoxy vinyl resin and emulsifier according to the formula, stir evenly and set aside.

[0040] 2) Weigh deionized water according to the formula. Under the heating condition of 80 °C, slowly add the deionized water to the vinyl resin mixture obtained in step (1) at a rate of 1 mL / min. Mix with an emulsifier at a rotation speed of 16000 rpm. After adding all the deionized water, cool to room temperature to obtain the sizing agent.

[0041] Example 5

[0042] A sizing agent for carbon fiber used in vinyl resin, calculated by mass, its raw material composition includes: 30 parts of epoxy vinyl resin, 20 parts of emulsifier and co-surfactant (compounded by polyoxyethylene cetyl ether, sodium dodecyl sulfate and n-hexanol according to the mass ratio of 90:5:5), and 50 parts of deionized water.

[0043] The preparation process of the above sizing agent for carbon fiber used in vinyl resin includes the following steps:

[0044] 1) Weigh the epoxy vinyl resin, emulsifier and co-surfactant according to the formula, stir evenly and set aside.

[0045] 2) Weigh deionized water according to the formula. Under the heating condition of 60 °C, slowly add the deionized water to the vinyl resin mixture obtained in step (1) at a rate of 0.5 mL / min. Mix with an emulsifier at a rotation speed of 16000 rpm. After adding all the deionized water, cool to room temperature to obtain the sizing agent.

[0046] Example 6

[0047] A sizing agent for carbon fiber used in vinyl resin, calculated by mass parts, its raw material composition includes: 30 parts of epoxy vinyl resin, 20 parts of emulsifier and co-surfactant (compounded by polyoxyethylene cetyl ether, sodium decyl sulfate and n-hexanol according to the mass ratio of 90:5:5), and 50 parts of deionized water.

[0048] The preparation process of the above sizing agent for carbon fiber used in vinyl resin includes the following steps:

[0049] 1) Weigh the epoxy vinyl resin, emulsifier and co-surfactant according to the formula, stir evenly, and set aside;

[0050] 2) Weigh the deionized water according to the formula. Under the heating condition of 80 °C, add the deionized water to the vinyl resin mixture obtained in step (1) at a speed of 1 mL / min, mix with an emulsifier at a rotation speed of 20000 rpm. After adding all the deionized water, cool to room temperature to obtain the sizing agent.

[0051] Comparative Example 1

[0052] A sizing agent for carbon fiber used in vinyl resin and its preparation method in this comparative example are the same as those in Example 1, the difference is that

[0053] In step 2), the dropping speed of the deionized water is 3 mL / min.

[0054] Comparative Example 2

[0055] A sizing agent for carbon fiber used in vinyl resin and its preparation process in this comparative example are the same as those in Example 1, the difference is that

[0056] In step 2), the rotation speed of the emulsifier is 8000 rpm.

[0057] Comparative Example 3

[0058] A sizing agent for carbon fiber used in vinyl resin and its preparation process in this comparative example are the same as those in Example 1, the difference is that the emulsifier is only polyoxyethylene cetyl ether.

[0059] Comparative Example 4

[0060] A sizing agent for carbon fiber used in vinyl resin and its preparation process in this comparative example are the same as those in Example 1, the difference is that the emulsifier is only sodium decyl sulfate.

[0061] Comparative Example 5

[0062] A sizing agent for carbon fiber used in vinyl resin and its preparation process in this comparative example are the same as those in Example 1, the difference is that the co-surfactant is n-butanol.

[0063] Comparative Example 6

[0064] A sizing agent for carbon fiber for vinyl resin and its preparation process in this comparative example are the same as those in Example 1, except that the co-surfactant is n-pentanol.

[0065] In order to verify the effects of the sizing agents for carbon fiber obtained in Examples 1-6 and Comparative Examples 1-6, the present invention conducts the following tests on them:

[0066] (1) Sizing agent storage stability test: Store the prepared sizing agent for carbon fiber for vinyl resin for 30 days, and observe whether demulsification and precipitation occur.

[0067] (2) Sizing agent particle size test: Measure the particle size of the sizing agent using a laser particle size analyzer.

[0068] The test results are shown in Table 1:

[0069] Table 1 Particle size and stability of sizing agents for carbon fiber in Examples 1-6 and Comparative Examples 1-6

[0070]

[0071]

[0072] (3) Sizing effect test of carbon fiber: Size the 48K carbon fiber bundle with the sizing agents prepared in Example 1 and Example 2 respectively, and use a field emission scanning electron microscope to test the sizing effect of the sizing agent for carbon fiber. The results are as Figure 1 shown.

[0073] Figure 1 in, Figure 1 (a) is the surface SEM image of the carbon fiber without sizing treatment, Figure 1 (b) is the surface SEM image of the carbon fiber sized with the sizing agent in Example 1, Figure 1 (c) is the surface SEM image of the carbon fiber sized with the sizing agent in Example 2.

[0074] It can be Figure 1 seen that there are many surface grooves on the carbon fiber before sizing. After sizing with the sizing agents in Example 1 and Example 2, the surface grooves of the carbon fiber are significantly reduced, and a complete and uniform sizing agent coating layer is formed.

Claims

1. A sizing agent for carbon fiber used in vinyl resin, characterized in that, In parts by mass, its raw material composition is: 15 - 30 parts of epoxy vinyl resin and / or phenolic vinyl resin, 12 - 20 parts of emulsifier and co-surfactant, and 50 - 70 parts of deionized water.

2. The sizing agent for carbon fiber for vinyl resin according to claim 1, wherein The emulsifier is one or a mixture of two or more of polyoxyethylene cetyl ether, sodium decyl sulfate, sodium dodecyl sulfonate, sodium oleate, potassium oleate, and the Tween series.

3. The sizing agent for carbon fiber used in vinyl resin according to claim 1, characterized in that, The co-surfactant is one of n-butanol, n-pentanol, and n-hexanol.

4. The sizing agent for carbon fiber used in vinyl resin according to claim 1, characterized in that, The emulsifier is a mixture of polyoxyethylene cetyl ether and sodium decyl sulfate, and the co-surfactant is n-hexanol. In terms of mass fraction, the composition of the emulsifier and the co-surfactant is: 80 - 90 parts of polyoxyethylene cetyl ether, 5 - 10 parts of sodium decyl sulfate, and 5 - 10 parts of n-hexanol.

5. The preparation method of the sizing agent for carbon fiber used in vinyl resin according to any one of claims 1-4, characterized in that, It includes the following steps: 1) Mix epoxy vinyl resin and / or phenolic vinyl resin, emulsifier, and co-surfactant to obtain a vinyl resin mixture; 2) Under the condition of constant-temperature heating, add deionized water dropwise to the vinyl resin mixture obtained in step 1) and stir and mix until the addition of deionized water is completed, and then cool to room temperature to obtain a sizing agent.

6. The preparation method of the sizing agent for carbon fiber for vinyl resin according to claim 5, characterized in that, In step 2), the heating temperature is 60 - 80 °C, the dropping rate of deionized water is 0.5 - 1 mL / min, and the stirring speed is 16000 - 20000 rpm.

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