A high-temperature-resistant thermoplastic carbon fiber water-based composite sizing agent and preparation method thereof

Abstract

The present invention relates to a high-temperature-resistant thermoplastic water-based composite sizing agent for carbon fibers and its preparation method. The sizing agent comprises amino-polyetherketoneketone, carboxylated carbon nanotubes, and deionized water. Compared with the prior art, the sizing agent of the present invention is a composite water-based sizing agent that does not contain any other additives and is environmentally friendly. Furthermore, this sizing agent addresses the issues of existing sizing agents being heat-resistant and unsuitable for carbon fiber-reinforced high-performance thermoplastic composites, significantly improving the interfacial bonding strength of carbon fiber-reinforced high-performance thermoplastic resin-based composites.

Description

Technical Field

[0001] The invention belongs to the field of functional materials, and in particular relates to a high-temperature resistant thermoplastic carbon fiber water-based composite sizing agent and a preparation method thereof. Background Art

[0002] Carbon fiber reinforced resin-based composites (CFRP) have been widely used in aerospace, automotive lightweighting, and military fields due to their lightweight, excellent mechanical properties, corrosion resistance, strong chemical stability, and strong designability. CFRP is divided into carbon fiber reinforced thermosetting resin-based composites and carbon fiber reinforced thermoplastic resin-based composites (CFRTP) based on the resin matrix. Due to the advantages of CFRTP such as short molding cycle, high toughness, and recyclability, it has been widely used in aviation, aerospace, transportation, new energy and other fields. It is also a key strategic material for the future development of my country's high-end manufacturing industry. Among thermoplastic resins, high-performance thermoplastic resins such as polyaryletherketone ketone resins have excellent high temperature resistance and mechanical properties due to the alternating arrangement of ketone and ether groups in their molecular backbone. They also have good hydrolysis resistance, UV resistance, corrosion resistance, easy melt processability, and recyclability. They are currently the resins with the highest heat resistance and the best overall performance among special engineering plastics. Because high-performance thermoplastic resins have long molecular chains and stable chemical properties, and the carbon fiber itself has a highly graphitized structure, a smooth surface and is chemically inert, the bonding between the carbon fiber and the thermoplastic resin matrix is relatively poor, significantly affecting the mechanical properties of CFRTP. To solve this problem, carbon fiber sizing agents are usually used to improve the bonding between the carbon fiber and the resin, thereby improving the mechanical properties of CFRTP. Currently, most commercial carbon fiber products use thermosetting sizing agents, which have low heat resistance, generally below 250°C, while the processing temperature of high-performance polyaryletherketone resins is generally 320-420°C, and there is an incompatibility problem between the two.

[0003] For sizing agents suitable for carbon fiber reinforced polyaryletherketone composites, current research mainly focuses on dissolving high-performance thermoplastic resin oligomers or modified high-performance thermoplastic resins in organic solvents.

[0004] Patent CN111423694A discloses a dichloromethane organic solvent sizing agent for polyetherketone ketone copolymers, which is used to prepare carbon fiber reinforced polyetheretherketone (CF / PEEK) composite materials with high interlayer shear strength; Patent CN111410758B discloses an N,N-dimethylacetamide organic solvent sizing agent for polyarylsulfone, which is used to prepare CF / PEEK composite materials with high impact resistance; Patent CN111440342A discloses a dimethylformamide organic solvent sizing agent for aminated polyetheretherketone & carbon nanotubes, which is used to prepare CF / PEEK composite materials; Patent CN111423695B discloses a dimethyl sulfoxide organic solvent sizing agent for sulfonated polyetheretherketone & carbon nanotubes, which is used to prepare CF / PEEK composite materials with high interlayer shear strength and flexural strength; Patent CN111410759B discloses an N-methyl-2-pyrrolidone organic solvent sizing agent for polyamic acid & carbon nanotubes, which is used to prepare CF / PEEK composite materials with high fatigue strength. The advantage of these patents is that they use high-performance thermoplastic resins as sizing agents to improve the adhesion between the carbon fiber and polyaryletherketone resin interface. The disadvantage is that the sizing agents are all organic solvent-based sizing agents, which are toxic to a certain extent and unfriendly to operators. They must be removed by heating later, which will cause environmental pollution and equipment damage. There are also problems such as the difficulty in completely removing organic solvents.

[0005] At present, some water-based sizing agents have been developed. For example, the articles [Surfaces and Interfaces, 2023, 37: 102652] and [Progress in Organic Coatings, 2021, 154: 106193] studied sulfonated polyetheretherketone sizing agents. Although the thermal decomposition temperature of sulfonated polyetheretherketone is about 320°C, the processing temperature of carbon fiber reinforced polyaryletherketone resin-based composite materials is generally higher than 320°C. The sizing agent has problems such as more thermal decomposition during use and reduced interfacial adhesion of the composite material. Patent CN 113718528 A discloses a sulfonated polyaryletherketone water-based sizing agent and its preparation method and application. The patent does not involve a preparation method of sulfonated polyaryletherketone, and the sulfonated polyaryletherketone sizing agent has problems such as a high emulsifier content and difficulty in complete removal.

[0006] Therefore, it is of great significance to develop an environmentally friendly, high-temperature-resistant thermoplastic carbon fiber water-based composite sizing agent. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a high-temperature resistant thermoplastic carbon fiber water-based composite sizing agent and a preparation method thereof, so as to overcome the problems of the carbon fiber sizing agent in the prior art, such as insufficient temperature resistance, environmentally unfriendly organic solvents, and a large number of additives that are difficult to remove.

[0008] The invention discloses an aqueous composite sizing agent, wherein the sizing agent components comprise, by mass percentage, 0.1-2.0 wt% of amino polyetherketoneketone, 0.1-0.5 wt% of carboxylated carbon nanotubes, and 97.5-99.8 wt% of water.

[0009] The water-based composite sizing agent is beneficial to improving the high temperature resistance of the carbon fiber sizing agent and strengthening the interface bonding between the carbon fiber and the high-performance thermoplastic resin.

[0010] Preferably, the sizing agent components include, by mass percentage, 0.2-1.0 wt% of amino-polyetherketoneketone, 0.2-0.5 wt% of carboxylated carbon nanotubes, and 98.5-99.6 wt% of water.

[0011] The water is deionized water.

[0012] Preferably, the amino polyetherketoneketone has the structural formula:

[0013] wherein n is an integer greater than 1.

[0014] The preparation method of the amino polyetherketoneketone comprises:

[0015] (1) Dissolve polyetherketoneketone in concentrated sulfuric acid, then add concentrated nitric acid and mix. Under nitrogen protection, heat to 80-120°C and react for 10-40 hours.

[0016] (2) pouring the reaction solution in step (1) into water at -20 to 10° C. to obtain a mixture of nitrated polyetherketoneketone, sulfuric acid, nitric acid and water;

[0017] (3) centrifuging or filtering the mixture in step (2) to obtain a precipitate, then washing the precipitate and vacuum drying to obtain nitrated polyetherketoneketone;

[0018] (4) dissolving the nitroated polyetherketoneketone in step (3) in dimethylacetamide, then adding formamidinesulfinic acid, heating to 60-100° C. under the protection of nitrogen, reacting for 5-15 hours, purifying, and drying to obtain the aminoated polyetherketoneketone.

[0019] Preferably, the average molecular weight of the polyetherketoneketone in step (1) is 1w~6w; in step (1), the polyetherketoneketone is first dissolved in concentrated sulfuric acid, and then concentrated nitric acid is added for mixing, wherein the concentration of the polyetherketoneketone after mixing is 5~20wt%; the volume ratio of the concentrated sulfuric acid to the concentrated nitric acid is 1 / 4-1 / 6.

[0020] Further preferably, the concentration of polyetherketoneketone in step (1) is 10 wt%.

[0021] Preferably, the reaction in step (1) is continued at 100° C. for 15 hours.

[0022] Preferably, in step (3), the precipitate is washed 5 to 10 times with deionized water to remove residual sulfuric acid and nitric acid.

[0023] Preferably, in the step (4), the nitroated polyetherketoneketone is dissolved in dimethylacetamide, wherein the concentration of the nitroated polyetherketoneketone is 5 to 15 wt %; the mass ratio of the nitroated polyetherketoneketone to formamidinesulfinic acid is 1:8 to 10, and further preferably, the mass ratio of the nitroated polyetherketoneketone to formamidinesulfinic acid is 1:10.

[0024] More preferably, the concentration of the nitrated polyetherketoneketone is 10 wt %.

[0025] Preferably, in step (4), the temperature is raised to 80° C. and the reaction is carried out for 8 to 10 hours.

[0026] Preferably, the purification in step (4) is specifically as follows: the reaction solution is poured into ethanol, the amino polyether ketone ketone will precipitate and precipitate in the ethanol, and then the precipitate is washed 5 to 10 times with deionized water, and finally the precipitate is vacuum-dried to obtain the amino polyether ketone ketone.

[0027] The preparation method of a water-based composite sizing agent of the present invention comprises the following steps: mixing amino polyetherketoneketone, carboxylated carbon nanotubes and water according to a proportion, stirring and ultrasonically dispersing the mixture.

[0028] Preferably, the stirring is carried out at 60-90° C. for 0.5-3 h; and the ultrasonic dispersion time is 30-120 min.

[0029] More preferably, the stirring time at 90° C. is 2 h, and the ultrasonic dispersion time is 1 h.

[0030] The present invention provides a carbon fiber composite material, wherein the composite material is obtained by treating carbon fibers with the aqueous composite sizing agent.

[0031] The method for preparing a carbon fiber composite material of the present invention comprises: impregnating the carbon fiber material with the aqueous composite sizing agent, taking the carbon fiber material out and drying the impregnated carbon fiber material.

[0032] The present invention provides an application of the carbon fiber composite material in aerospace.

[0033] Beneficial effects

[0034] (1) The sizing agent provided by the present invention is not an organic solvent sizing agent, but a water-based sizing agent, which is environmentally friendly and has good application prospects;

[0035] (2) The water-based composite sizing agent provided by the present invention has simple ingredients, does not involve other additives, and the solvent is water, which is easy to remove, and the sizing agent has high stability;

[0036] (3) The thermoplastic water-based composite sizing agent provided by the present invention has high temperature resistance, a decomposition temperature greater than 390°C, and is suitable for carbon fiber reinforced high-performance thermoplastic composite materials;

[0037] (4) The present invention provides a thermoplastic water-based composite sizing agent, which can form an effective interface bond with carbon fibers through peptide bond bonding, π-π interaction, mechanical interlocking, van der Waals force, and other methods. At the same time, it can also undergo melt entanglement, mechanical interlocking, hydrogen bond interaction, etc. with the thermoplastic resin matrix, thereby effectively improving the interface bonding ability between the carbon fibers and the high-performance thermoplastic resin matrix. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the H NMR spectrum of amino-polyetherketoneketone.

[0039] Figure 2 This is the thermogravimetric spectrum of the composite sizing agent under nitrogen conditions. DETAILED DESCRIPTION

[0040] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0041] Source of raw materials:

[0042] Polyetherketoneketone resin powder: Shandong Kaisheng New Materials Technology Co., Ltd., model 5601, average molecular weight is about 2w, carboxylated carbon nanotubes: Zhongke Nano, model TNMC8.

[0043] Example 1

[0044] The preparation process of amino polyetherketoneketone is as follows:

[0045] Step 1: Dissolve 15g of polyetherketoneketone powder in concentrated sulfuric acid, then add concentrated nitric acid and mix. The volume of concentrated sulfuric acid is 62.5mL and the volume of concentrated nitric acid is 187.5mL. Under nitrogen protection, heat to 100℃ and react for 10h.

[0046] Step 2: Pour the reaction solution of step 1 into deionized water at 0°C to obtain a mixture of nitrated polyetherketoneketone, sulfuric acid, nitric acid and water;

[0047] Step 3: The mixture in step 2 is centrifuged or filtered to obtain a milky white precipitate, and then the precipitate is washed 10 times with deionized water to remove residual sulfuric acid and nitric acid. Finally, the precipitate is dried to obtain nitroated polyetherketoneketone.

[0048] Step 4: Dissolve 2 g of the nitroated polyetherketoneketone obtained in step 3 in 200 mL of dimethylacetamide, then add 20 g of formamidinesulfinic acid, and under the protection of nitrogen, raise the temperature to 80°C and react for 8 to 10 hours;

[0049] Step 5: Pour the reaction solution in step 4 into ethanol, and the amino polyether ketone ketone is precipitated and precipitated in the ethanol. Then, the precipitate is washed 5 times with deionized water. Finally, the precipitate is vacuum-dried to obtain the amino polyether ketone ketone.

[0050] The structural formula of amino polyetherketoneketone is:

[0051] Where n = (20-140)

[0052] After testing, the nuclear magnetic hydrogen spectrum of amino polyetherketoneketone is as follows Figure 1 shown.

[0053] Example 2

[0054] A high-temperature-resistant thermoplastic carbon fiber water-based composite sizing agent and a preparation method thereof, wherein the preparation process is as follows:

[0055] (1) Preparation of aqueous composite sizing agent: 0.1 wt% of amino-polyetherketoneketone (Example 1), 0.5 wt% of carboxylated carbon nanotubes and deionized water were stirred at 80°C for 2 h to form an amino-polyetherketoneketone aqueous suspension sizing agent.

[0056] (2) Desizing and sizing the carbon fiber surface:

[0057] Desizing: reflux the CF fabric in acetone solvent at 70°C for 10 h, rinse with deionized water, and dry;

[0058] Sizing: Place the desized CF fabric into the above-mentioned aqueous composite sizing agent, soak it at room temperature for 1 hour, then take it out and dry it to obtain the sized CF fabric.

[0059] According to the test, the interfacial bonding strength (IFBS) between the carbon fiber and polyether ketone ketone after composite sizing is 89 MPa, and the interlaminar shear strength of the prepared carbon fiber / polyether ether ketone composite material is 82 MPa.

[0060] Example 3

[0061] A high-temperature-resistant thermoplastic carbon fiber aqueous composite sizing agent and a preparation method thereof are basically the same as those in Example 2, except that: in step (1), the concentration of amino-polyetherketoneketone is 2 wt%, the concentration of carboxylated carbon nanotubes is 0.1 wt%, and the other preparation processes are the same as those in Example 1.

[0062] After testing, such as Figure 2 As shown in the figure, when the weight loss of the composite sizing agent is 5%, the temperature is 463 degrees, indicating that the composite sizing agent has good thermal stability; the interfacial bonding strength (IFBS) between the carbon fiber and polyetheretherketone after amino polyetherketoneketone sizing is 93MPa, and the interlaminar shear strength of the prepared carbon fiber / polyetheretherketone composite material is 85MPa.

[0063] Example 4

[0064] A high-temperature-resistant thermoplastic carbon fiber aqueous composite sizing agent and a preparation method thereof are basically the same as those in Example 2, except that: in step (1), the concentration of amino-polyetherketoneketone is 0.5wt%, the concentration of carboxylated carbon nanotubes is 0.25wt%, and the other preparation processes are the same as those in Example 1.

[0065] According to the test, the interfacial bonding strength (IFBS) between carbon fiber and polyetheretherketone after amino-polyetherketone sizing is 112MPa, and the interlaminar shear strength of the prepared carbon fiber / polyetheretherketone composite material is 93MPa.

[0066] The statistics of interface bonding strength and interlaminar shear strength in Examples 2 to 4 are shown in Table 1

[0067] Table 1

[0068]

[0069] By comparing Example 2, Example 3 and Example 4, it can be seen that changes in the concentration of the amino-polyetherketoneketone and carboxylated carbon nanotube composite sizing agent will lead to changes in the interface strength and interlaminar shear strength of the carbon fiber composite material. At an appropriate composite sizing agent concentration, a carbon fiber reinforced polyaryletherketone composite material with high interface strength can be obtained.

Claims

1. A water-based composite sizing agent, characterized in that In terms of mass percentage, the sizing agent components include: 0.1-2.0 wt% of amino-polyetherketoneketone, 0.1-0.5 wt% of carboxylated carbon nanotubes, and 97.5-99.8 wt% of water.

2. The aqueous composite sizing agent according to claim 1, wherein In terms of mass percentage, the sizing agent components include: 0.2-1.0 wt% of amino-polyetherketoneketone, 0.2-0.5 wt% of carboxylated carbon nanotubes, and 98.5-99.6 wt% of water.

3. The aqueous composite sizing agent according to claim 1, wherein The structural formula of the amino polyetherketoneketone is: wherein n is an integer greater than 1.

4. The aqueous composite sizing agent according to claim 3, wherein The preparation method of the amino polyetherketoneketone comprises: (1) Dissolve polyetherketoneketone in concentrated sulfuric acid, then add concentrated nitric acid and mix. Under nitrogen protection, heat to 80-120°C and react for 10-40 hours. (2) pouring the reaction solution in step (1) into water at -20 to 10° C. to obtain a mixture of nitrated polyetherketoneketone, sulfuric acid, nitric acid and water; (3) centrifuging or filtering the mixture in step (2) to obtain a precipitate, then washing the precipitate and vacuum drying to obtain nitrated polyetherketoneketone; (4) dissolving the nitroated polyetherketoneketone in step (3) in dimethylacetamide, then adding formamidinesulfinic acid, heating to 60-100° C. under the protection of nitrogen, reacting for 5-15 hours, purifying, and drying to obtain the aminoated polyetherketoneketone.

5. The aqueous composite sizing agent according to claim 4, characterized in that The average molecular weight of the polyetherketoneketone in step (1) is 1w-6w; in step (1), the polyetherketoneketone is first dissolved in concentrated sulfuric acid, and then concentrated nitric acid is added for mixing, wherein the concentration of the polyetherketoneketone after mixing is 5-20wt%; the volume ratio of the concentrated sulfuric acid to the concentrated nitric acid is 1 / 4-1 / 6.

6. The aqueous composite sizing agent according to claim 4, characterized in that In the step (4), the nitroated polyetherketoneketone is dissolved in dimethylacetamide, wherein the concentration of the nitroated polyetherketoneketone is 5 to 15 wt %; and the mass ratio of the nitroated polyetherketoneketone to formamidinesulfinic acid is 1:8 to 10.

7. A method for preparing an aqueous composite sizing agent, comprising: The amino-polyetherketoneketone, carboxyl-carbon nanotubes and water are mixed according to the proportion, stirred and ultrasonically dispersed.

8. The preparation method according to claim 7, characterized in that: The stirring is carried out at 60-90° C. for 0.5-3 h; and the ultrasonic dispersion time is 30-120 min.

9. A carbon fiber composite material, characterized in that: The composite material is obtained by treating carbon fiber with the water-based composite sizing agent according to claim 1.

10. Use of the carbon fiber composite material according to claim 9 in aerospace.

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