An aqueous resin dispersion of a carbon material, a carbon fiber prepreg

Abstract

The present application relates to the field of carbon fiber modification, and particularly relates to a water-based resin dispersion of carbon material, a carbon fiber prepreg, which comprises the following materials: modified acrylic ester water-based emulsion, polymer resin powder, anhydrous ethanol and pure water; the modified acrylic ester water-based emulsion is obtained by emulsion polymerization of monomer emulsion under the action of an initiator, the monomer emulsion is obtained by emulsifying the following raw materials: long-chain alkyl ester monomer of oleic acid, short-chain alkyl ester monomer of acrylic acid, perfluoro non-polar emulsifier and pure water; the present application forms a water-based resin dispersion by synthesizing the modified acrylic ester emulsion and the polymer resin powder, which can effectively solve the problems of poor dispersion, easy agglomeration and sedimentation of the polymer resin powder in water, and can be used for surface modification of carbon material, can promote the adhesion between fibers, has good prepreg effect on carbon fiber, especially continuous long carbon fiber, and the formed prepreg has no obvious dry yarn.

Description

Technical Field

[0001] This invention relates to the field of carbon fiber modification, specifically to an aqueous resin dispersion of carbon materials and a carbon fiber prepreg. Background Technology

[0002] Carbon fiber prepreg, also known as carbon fiber prepreg fabric, is a carbon fiber composite material made by fully impregnating carbon fibers with a resin matrix and then processing it through coating, hot pressing, cooling, lamination, and winding.

[0003] The production methods of carbon fiber prepreg mainly include the following key steps and processes:

[0004] 1) Solution impregnation method: The resin is dissolved in a low-boiling-point solvent to form a solution with a specific concentration. Then, the fiber bundle or fabric is impregnated with the resin solution at a specified speed. The resin content is controlled by auxiliary tools. The low-boiling-point solvent is evaporated by drying, and finally, the fabric is wound up.

[0005] 2) Hot-melt impregnation method: The resin is heated to a molten state, and then the carbon fibers are passed through the molten resin to fully impregnate them. Finally, the impregnated carbon fibers are cooled to obtain prepreg. A hot-melt impregnation system generally includes three parts: a screw extruder, an impregnation die, and impregnation rollers. After being adjusted by the yarn frame, the carbon fibers enter the spreading device. After spreading, the fibers pass through the impregnation die at a constant traction speed. The impregnation pressure is generated by contact with the rollers inside the die, and after impregnation, the fibers pass through a traction device and a winding device to obtain the prepreg.

[0006] 3) Powder Impregnation Method: Resin powder is dispersed in water or other solvents to form a resin powder dispersion. Carbon fibers are then passed through this dispersion under the action of traction rollers, allowing the resin powder to be uniformly adsorbed onto the carbon fiber monofilaments. Ultrasonic vibration can be used during this process to ensure uniform powder distribution. After impregnation, the carbon fibers are dried to remove excess dispersant, ensuring the resin powder adheres firmly to the carbon fiber surface. The dried carbon fibers are then passed through a heating device to melt the resin powder and impregnate the carbon fibers, forming a prepreg. This prepreg is then mixed with the carbon fibers, and subsequently, the resin powder is melted again through heating and pressurization to impregnate the carbon fibers, yielding the prepreg.

[0007] Patent No. CN 116855078 A discloses a slurry for carbon fiber prepreg, its preparation method, and a method for preparing the prepreg. The invention discloses a slurry for carbon fiber prepreg, its preparation method, and a method for preparing the prepreg, which involves adding thermoplastic resin powder, a slurry dispersion medium, a surfactant, an antifoaming agent, a viscosity modifier, and modifying materials to prepare the slurry. This patent reduces the surface energy of the slurry dispersion medium (water) by adding a surfactant. However, the resin powder has poor dispersion stability within this medium, making it prone to agglomeration, and requiring continuous stirring to reduce the risk of sedimentation. Summary of the Invention

[0008] To address the technical problem of poor dispersibility of polymer resin powder in water, this invention provides an aqueous resin dispersion for carbon materials and a carbon fiber prepreg. This invention synthesizes a modified acrylate emulsion, which forms an aqueous resin dispersion with polymer resin powder. This effectively solves the problems of poor dispersion, easy agglomeration, and sedimentation of polymer resin powder in water. Simultaneously, it is used for surface modification of carbon materials, promoting adhesion between fibers. It has a good prepreg effect on carbon fibers, especially continuous long carbon fibers, and the resulting prepreg has no obvious dry yarn.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0010] An aqueous resin dispersion of a carbon material comprises the following materials in 100% by weight percentage:

[0011] The composition consists of 2%-10% modified acrylate aqueous emulsion, 15%-30% polymer resin powder, 8%-20% anhydrous ethanol, and the balance being pure water.

[0012] The modified acrylate aqueous emulsion has a solid content in the range of 20wt%-40wt% and a pH of 7-8;

[0013] The modified acrylate aqueous emulsion is obtained by emulsion polymerization of monomer emulsion under the action of an initiator. The monomer emulsion consists of the following raw materials in 100% by weight percentage: 12%-25% long-chain alkyl acrylate monomers, 12%-25% short-chain alkyl acrylate monomers, 2.5%-3.5% perfluorinated nonpolar emulsifier, and the balance being pure water.

[0014] The long-chain alkyl ester monomers of acrylic acid have at least 12 carbon atoms in their alkyl carbon chains, while the short-chain alkyl ester monomers of acrylic acid have less than 10 carbon atoms in their alkyl carbon chains and more than or equal to 4 carbon atoms.

[0015] Furthermore, the long-chain alkyl acrylate monomers are selected from one or more of the following: docosyl acrylate, docosyl methacrylate, octadecyl acrylate, octadecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, tetradecyl acrylate, tridecyl methacrylate, dodecyl acrylate, and dodecyl methacrylate.

[0016] The short-chain alkyl acrylate monomers are selected from one or more of 2-phenylethyl acrylate, 2-phenylethyl methacrylate, isoamyl acrylate, amyl methacrylate, isobutyl methacrylate, and phenyl acrylate.

[0017] Furthermore, the monomer emulsion is composed of the following raw materials in 100% by weight percentage: 0%-15% octadecyl methacrylate monomer, 5%-15% dodecyl methacrylate monomer, 8%-18% 2-phenylethyl methacrylate monomer, 0%-10% isoamyl acrylate monomer, 2.5%-3.5% perfluorinated nonpolar emulsifier, and the balance being pure water.

[0018] Furthermore, the initiator is selected from water-soluble persulfates such as potassium persulfate and ammonium persulfate, and the amount of the initiator is 1.2%-1.8% of the total weight of the monomers in the monomer emulsion;

[0019] Before the emulsion polymerization reaction occurs, baking soda needs to be added, with the amount of baking soda ranging from 60-90% of the initiator weight. After the emulsion polymerization reaction is completed, the pH value is adjusted to 7-8 with ammonia. In the emulsion polymerization reaction, the addition of persulfate will lower the pH value of the system, leading to a slower reaction rate, coarser emulsion particles, and even gelation and demulsification. The addition of baking soda can neutralize the acidic substances produced by the persulfate initiator, thereby adjusting and controlling the pH value of the polymerization system and ensuring the smooth progress of the reaction.

[0020] Furthermore, the modified acrylate aqueous emulsion is obtained as follows: long-chain alkyl ester monomers of acrylate, short-chain alkyl ester monomers of acrylate, perfluorinated nonpolar emulsifier and pure water are pre-emulsified at room temperature for at least 10 minutes to form a monomer emulsion.

[0021] Add a portion of the monomer emulsion to a baking soda solution, preheat to 60-80℃, add a portion of the initiator solution and react for 5-15 minutes. Then, add the remaining portion of the monomer emulsion and a portion of the initiator solution dropwise over 2 hours. Finally, add the remaining portion of the initiator solution dropwise over 1 hour and continue the reaction for 15-45 minutes. Then, raise the temperature to 80-90℃ and mature for 50 minutes to 1.5 hours to complete the emulsion polymerization. After cooling, adjust the pH value to 7-8 with ammonia.

[0022] Furthermore, the perfluorononpolar emulsifier is selected from ammonium perfluorononanoate and sodium perfluorodecyloxybenzenesulfonate, with a mass ratio of ammonium perfluorononanoate to sodium perfluorodecyloxybenzenesulfonate of 0.1-1.2:1.

[0023] Furthermore, the polymer resin powder is a non-polar thermoplastic polymer material, and the particle size of the polymer resin powder is less than 50 μm. The monomers used to synthesize the modified acrylate aqueous emulsion are non-polar monomers, which can promote the dispersibility of the non-polar polymer material in the emulsion.

[0024] Preferably, the polymer resin powder is selected from one or more of polyethylene, polypropylene, fusible polytetrafluoroethylene, polyphenylene sulfide, and polystyrene.

[0025] In another aspect, the present invention provides a carbon fiber prepreg, wherein the carbon fiber is impregnated and sized using an aqueous resin dispersion of the aforementioned carbon material for at least 1 second, and the sizing amount of the aqueous resin dispersion after curing in the carbon fiber prepreg exceeds 25 wt%; preferably, the sizing amount of the aqueous resin dispersion after curing in the carbon fiber prepreg is 30 wt%-40 wt%.

[0026] Furthermore, the carbon fiber is selected from short carbon fiber or continuous long carbon fiber; the carbon fiber needs to be heat-treated at at least 300°C before impregnation to remove the original epoxy sizing agent on the surface; the carbon fiber is dried in the range of 100-180°C after impregnation, and then pressed in the melting temperature range of polymer resin powder to obtain carbon fiber prepreg.

[0027] Furthermore, the carbon fiber prepreg is a continuous long carbon fiber prepreg, which is obtained by: arranging one or dozens of continuous long carbon fibers neatly on a heating roller, heating the heating roller to heat the carbon fibers to remove the original epoxy sizing agent on the surface, then immersing the continuous long carbon fibers in the aqueous resin dispersion of the carbon material by traction, and drying them in a drying tunnel after immersion to remove the solvent, thereby obtaining a fully sizing continuous long carbon fiber polymer resin mixture, which is then rolled or laminated to obtain the continuous long carbon fiber prepreg.

[0028] Beneficial technical effects:

[0029] The aqueous resin dispersion of the present invention enables the carbon fiber and the non-polar resin powder to have good compatibility, which can enhance the interfacial properties of the carbon fiber and the non-polar resin powder and improve the mechanical properties of the prepreg composite material.

[0030] The aqueous resin dispersion of the present invention can greatly improve the dispersion uniformity of non-polar resin powder, has strong anti-settling ability, and can fully and uniformly adsorb with carbon fibers; the modified acrylate aqueous emulsion therein has better fluidity than other resin powders, which correspondingly improves and enhances the wettability between non-polar resin powder and carbon fibers, and is used to adjust the viscosity and adhesion of the composite material system.

[0031] The present invention adds anhydrous ethanol to the aqueous resin dispersion to promote the dispersion of non-polar resin in the aqueous phase, which enables the preparation of a higher concentration dispersion for sizing carbon fibers, while avoiding the agglomeration of resin powder. Attached Figure Description

[0032] Figure 1 Photographs of the aqueous resin dispersions prepared in Examples 1, 2, and Comparative Examples 1-4;

[0033] Figure 2 The images show SEM images of the continuous long carbon fiber prepregs prepared in Example 1 and Comparative Example 2. The scale bar in the SEM image of Example 1 is 20 μm, and the scale bar in the SEM image of Comparative Example 2 is 40 μm. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] Unless otherwise specifically stated, the numerical values ​​set forth in these embodiments do not limit the scope of the invention. Techniques and methods known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques and methods should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0036] Experimental methods not specified in the following examples are generally performed according to national standards; if there is no corresponding national standard, they are performed according to general standard requirements or general methods.

[0037] It should be noted that the notation (meth)acrylic acid indicates that the methyl group is optional, meaning it can mean either acrylic acid or methacrylic acid, and so on. Example 1

[0038] An aqueous resin dispersion of a carbon material comprises the following materials in 100% by weight percentage: 5% modified acrylate aqueous emulsion, 28% PPS powder with a particle size of 30 μm, 10% anhydrous ethanol, and 57% pure water.

[0039] Under continuous stirring, anhydrous ethanol and PPS powder were added to the modified acrylate aqueous emulsion according to the above ratio and stirred for 15 minutes. Then, pure water was added and stirred for 15 minutes to obtain the aqueous resin dispersion of carbon material.

[0040] The modified acrylate aqueous emulsion mentioned above was obtained by the following method:

[0041] (1) Monomer emulsion

[0042] In a 500mL round-bottom flask, add 90mL of ultrapure water, 2.5g of ammonium perfluorononanoate, and 2.5g of sodium perfluorodecyloxybenzenesulfonate. After stirring to dissolve, add 13g of octadecyl acrylate, 15g of dodecyl acrylate, 15g of ethyl acrylate, and 10g of isoamyl acrylate in sequence. Emulsify at 250r / min for 30min at room temperature to obtain a monomer emulsion.

[0043] (2) Emulsion polymerization

[0044] Weigh 0.8 g of potassium persulfate into an Erlenmeyer flask, dissolve it in 30 mL of ultrapure water to prepare an initiator aqueous solution, and store it in a refrigerator for later use;

[0045] Add 0.5g sodium bicarbonate and 15mL ultrapure water to a 500mL round-bottom flask and stir to dissolve. Measure 20mL of the monomer emulsion obtained in the previous step and add it to the reaction flask. Heat to 80℃ with a stirring rate of 300r / min. Add 6mL of initiator aqueous solution and react until the system turns blue. Continue to react for 10min. First, add the remaining monomer emulsion, then add 21mL of initiator solution dropwise, completing the addition in about 2 hours. Then, add the remaining 3mL of initiator aqueous solution dropwise in 30 minutes. Continue to react for 30 minutes, then heat to 85℃ and mature for 1 hour. After the emulsion polymerization is completed, cool to 60℃, add ammonia to adjust the pH to 7-8, and discharge to obtain a modified acrylate aqueous emulsion with a solid content of about 27wt%.

[0046] The dispersion photograph in this case is as follows: Figure 1 As shown, the polymer PPS powder has a good dispersion effect in the dispersion liquid, and there is no sedimentation phenomenon after 30 minutes.

[0047] Preparation method of continuous long carbon fiber prepreg: 25 strands of continuous long carbon fiber are arranged neatly on a heated roller. The fiber is heat-treated by the heated roller at 360°C to remove the original epoxy sizing agent on the surface. Then, the continuous long carbon fiber is immersed in the aqueous resin dispersion obtained above by traction (immersion time is about 3 seconds). Then, it is dried in a 130°C oven to remove anhydrous ethanol and ultrapure water from the dispersion, so as to obtain a fully sized continuous long carbon fiber polymer resin PPS mixture (the sizing amount of the aqueous resin dispersion after curing in the prepreg is 34 wt%).

[0048] The continuous long carbon fiber polymer resin PPS mixture is pressed into continuous long carbon fiber prepreg through a vertical two-roll mill at 320°C.

[0049] The SEM image of the continuous long carbon fiber prepreg prepared in this case is shown below. Figure 2 As shown, the modified acrylic resin and PPS resin after curing of the water-based resin dispersion have a good pre-impregnation effect on the fibers, and the carbon fibers have no obvious dry yarn. Example 2

[0050] An aqueous resin dispersion of a carbon material comprises the following materials in 100% by weight percentage: 5% modified acrylate aqueous emulsion, 30% PPS powder with a particle size of 30 μm, 10% anhydrous ethanol, and 55% pure water.

[0051] Under continuous stirring, anhydrous ethanol and PPS powder were added to the modified acrylate aqueous emulsion according to the above ratio and stirred for 15 minutes. Then, pure water was added and stirred for 15 minutes to obtain the aqueous resin dispersion of carbon material.

[0052] The modified acrylate aqueous emulsion mentioned above was obtained by the following method:

[0053] (1) Monomer emulsion

[0054] In a 500mL round-bottom flask, add 90mL of ultrapure water, 2.2g of ammonium perfluorononanoate, and 2.0g of sodium perfluorodecyloxybenzenesulfonate. After stirring to dissolve, add 18g of octadecyl acrylate, 20g of dodecyl acrylate, and 20g of ethyl acrylate in sequence. Emulsify by stirring at 250r / min for 30min at room temperature to obtain a monomer emulsion.

[0055] (2) Emulsion polymerization

[0056] Weigh 1.0 g of potassium persulfate into an Erlenmeyer flask, dissolve it in 30 mL of ultrapure water to prepare an initiator aqueous solution, and store it in a refrigerator for later use;

[0057] 0.8 g of sodium bicarbonate and 15 mL of ultrapure water were added to a 500 mL round-bottom flask and stirred to dissolve. 20 mL of the monomer emulsion obtained in the previous step was added to the reaction flask. The mixture was heated to 80 °C with a stirring rate of 300 r / min. 6 mL of initiator aqueous solution was added and the reaction was continued until the system turned blue. The reaction was continued for 10 min. The remaining monomer emulsion was added dropwise first, followed by 21 mL of initiator solution, which was added dropwise over about 2 h. The remaining 3 mL of initiator aqueous solution was added dropwise over 30 min. The reaction was continued for 30 min, and then the temperature was raised to 85 °C for 1 h to complete the emulsion polymerization. The mixture was then cooled to 60 °C, and the pH was adjusted to 7-8 with ammonia. The product was discharged to obtain a modified acrylate aqueous emulsion with a solid content of about 29 wt%.

[0058] The dispersion photograph in this case is as follows: Figure 1 As shown, the polymer PPS powder has a good dispersion effect in the dispersion liquid, and there is no sedimentation phenomenon after 30 min.

[0059] Preparation method of continuous long carbon fiber prepreg: 25 strands of continuous long carbon fiber are arranged neatly on a heated roller. The fiber is heat-treated by the heated roller at 360°C to remove the original epoxy sizing agent on the surface. Then, the continuous long carbon fiber is immersed in the aqueous resin dispersion obtained above by traction (immersion time 3s). Then, it is dried in a 130°C oven to remove anhydrous ethanol and ultrapure water from the dispersion, and a fully sized continuous long carbon fiber polymer resin PPS mixture is obtained (the sizing amount of the aqueous resin dispersion after curing in the prepreg is 35wt%).

[0060] The continuous long carbon fiber polymer resin PPS mixture is pressed into continuous long carbon fiber prepreg through a vertical two-roll mill at 320°C. Example 3

[0061] An aqueous resin dispersion of a carbon material comprises the following materials in 100% by weight: 3% modified acrylate aqueous emulsion, 15% PPS powder with a particle size of 30 μm, 8% anhydrous ethanol, and 74% pure water.

[0062] Under continuous stirring, anhydrous ethanol and PPS powder were added to the modified acrylate aqueous emulsion according to the above ratio and stirred for 15 minutes. Then, pure water was added and stirred for 15 minutes to obtain the aqueous resin dispersion of carbon material.

[0063] The modified acrylate aqueous emulsion mentioned above was obtained by the following method:

[0064] (1) Monomer emulsion

[0065] In a 500mL round-bottom flask, add 90mL of ultrapure water, 2.0g of ammonium perfluorononanoate, and 3.0g of sodium perfluorodecyloxybenzenesulfonate. After stirring to dissolve, add 15g of octadecyl acrylate, 10g of dodecyl acrylate, 12g of ethyl acrylate, and 13g of isoamyl acrylate in sequence. Emulsify at 250r / min for 30min at room temperature to obtain a monomer emulsion.

[0066] (2) Emulsion polymerization

[0067] Weigh 0.6 g of potassium persulfate into an Erlenmeyer flask, dissolve it in 30 mL of ultrapure water to prepare an initiator aqueous solution, and store it in a refrigerator for later use;

[0068] Add 0.5g sodium bicarbonate and 15mL ultrapure water to a 500mL round-bottom flask and stir to dissolve. Measure 20mL of the monomer emulsion obtained in the previous step and add it to the reaction flask. Heat to 80℃ with a stirring rate of 300r / min. Add 6mL of initiator aqueous solution and react until the system turns blue. Continue to react for 10min. First, add the remaining monomer emulsion, then add 21mL of initiator solution dropwise, completing the addition in about 2 hours. Then, add the remaining 3mL of initiator aqueous solution dropwise in 30 minutes. Continue to react for 30 minutes, then heat to 85℃ and mature for 1 hour. After the emulsion polymerization is completed, cool to 60℃, add ammonia to adjust the pH to 7-8, and discharge to obtain a modified acrylate aqueous emulsion with a solid content of about 27wt%.

[0069] Preparation method of continuous long carbon fiber prepreg: 25 strands of continuous long carbon fiber are arranged neatly on a heated roller. The fiber is heat-treated by the heated roller at 380°C to remove the original epoxy sizing agent on the surface. Then, the continuous long carbon fiber is immersed in the aqueous resin dispersion obtained above by traction (immersion time 5s). Then, it is dried in a 120°C oven to remove anhydrous ethanol and ultrapure water from the dispersion, and a fully sized continuous long carbon fiber polymer resin PPS mixture is obtained (the sizing amount of the aqueous resin dispersion after curing in the prepreg is 31wt%).

[0070] The continuous long carbon fiber polymer resin PPS mixture is pressed into continuous long carbon fiber prepreg through a vertical two-roll mill at 260°C. Example 4

[0071] An aqueous resin dispersion of a carbon material comprises the following materials in 100% by weight: 10% modified acrylate aqueous emulsion, 18% PPS powder with a particle size of 30 μm, 15% anhydrous ethanol, and 57% pure water.

[0072] Under continuous stirring, anhydrous ethanol and PPS powder were added to the modified acrylate aqueous emulsion according to the above ratio and stirred for 15 minutes. Then, pure water was added and stirred for 15 minutes to obtain the aqueous resin dispersion of carbon material.

[0073] The modified acrylate aqueous emulsion mentioned above was obtained by the following method:

[0074] (1) Monomer emulsion

[0075] In a 500mL round-bottom flask, add 90mL of ultrapure water, 1.5g of ammonium perfluorononanoate, and 3.5g of sodium perfluorodecyloxybenzenesulfonate. After stirring to dissolve, add 20g of dodecyl acrylate, 25g of ethyl acrylate, and 10g of isoamyl acrylate in sequence. Emulsify at 250r / min for 30min at room temperature to obtain a monomer emulsion.

[0076] (2) Emulsion polymerization

[0077] Weigh 0.8 g of potassium persulfate into an Erlenmeyer flask, dissolve it in 30 mL of ultrapure water to prepare an initiator aqueous solution, and store it in a refrigerator for later use;

[0078] Add 0.5g sodium bicarbonate and 15mL ultrapure water to a 500mL round-bottom flask and stir to dissolve. Measure 20mL of the monomer emulsion obtained in the previous step and add it to the reaction flask. Heat to 80℃ with a stirring rate of 300r / min. Add 6mL of initiator aqueous solution and react until the system turns blue. Continue to react for 10min. First, add the remaining monomer emulsion, then add 21mL of initiator solution dropwise, completing the addition in about 2 hours. Then, add the remaining 3mL of initiator aqueous solution dropwise in 30 minutes. Continue to react for 30 minutes, then heat to 85℃ and mature for 1 hour. After the emulsion polymerization is completed, cool to 60℃, add ammonia to adjust the pH to 7-8, and discharge to obtain a modified acrylate aqueous emulsion with a solid content of about 28wt%.

[0079] Preparation method of continuous long carbon fiber prepreg: 25 strands of continuous long carbon fiber are arranged neatly on a heated roller. The fiber is heat-treated by the heated roller at 380°C to remove the original epoxy sizing agent on the surface. Then, the continuous long carbon fiber is immersed in the aqueous resin dispersion obtained above by traction (immersion time 4s). Then, it is dried in a 130°C oven to remove anhydrous ethanol and ultrapure water from the dispersion, and a fully sized continuous long carbon fiber polymer resin PPS mixture is obtained (the sizing amount of the aqueous resin dispersion after curing in the prepreg is 36wt%).

[0080] The continuous long carbon fiber polymer resin (PPS) mixture is pressed into a continuous long carbon fiber prepreg by a vertical two-roll mill at 300°C. Example 5

[0081] An aqueous resin dispersion of a carbon material comprises the following materials in 100% by weight: 3% modified acrylate aqueous emulsion, 25% PPS powder with a particle size of 45 μm, 12% anhydrous ethanol, and 60% pure water.

[0082] Under continuous stirring, anhydrous ethanol and PPS powder were added to the modified acrylate aqueous emulsion according to the above ratio and stirred for 15 minutes. Then, pure water was added and stirred for 15 minutes to obtain the aqueous resin dispersion of carbon material.

[0083] The modified acrylate aqueous emulsion mentioned above was obtained by the following method:

[0084] (1) Monomer emulsion

[0085] In a 500mL round-bottom flask, add 90mL of ultrapure water, 0.5g of ammonium perfluorononanoate, and 3.5g of sodium perfluorodecyloxybenzenesulfonate. After stirring to dissolve, add 13g of octadecyl acrylate, 15g of dodecyl acrylate, 15g of ethyl acrylate, and 10g of isoamyl acrylate in sequence. Emulsify at 250r / min for 30min at room temperature to obtain a monomer emulsion.

[0086] (2) Emulsion polymerization

[0087] Weigh 0.3 g potassium persulfate and 0.5 g ammonium persulfate into an Erlenmeyer flask, dissolve them in 30 mL of ultrapure water to prepare an initiator aqueous solution, and store it in a refrigerator for later use;

[0088] Add 0.5g sodium bicarbonate and 15mL ultrapure water to a 500mL round-bottom flask and stir to dissolve. Measure 20mL of the monomer emulsion obtained in the previous step and add it to the reaction flask. Heat to 80℃ with a stirring rate of 300r / min. Add 6mL of initiator aqueous solution and react until the system turns blue. Continue to react for 10min. First, add the remaining monomer emulsion, then add 21mL of initiator solution dropwise, completing the addition in about 2 hours. Then, add the remaining 3mL of initiator aqueous solution dropwise in 30 minutes. Continue to react for 30 minutes, then heat to 85℃ and mature for 1 hour. After the emulsion polymerization is completed, cool to 60℃, add ammonia to adjust the pH to 7-8, and discharge to obtain a modified acrylate aqueous emulsion with a solid content of about 27wt%.

[0089] Preparation method of continuous long carbon fiber prepreg: 25 strands of continuous long carbon fiber are arranged neatly on a heated roller. The fiber is heat-treated by the heated roller at 400℃ to remove the original epoxy sizing agent on the surface. Then, the continuous long carbon fiber is immersed in the aqueous resin dispersion obtained above by traction (immersion time 3s). Then, it is dried in a 150℃ oven to remove anhydrous ethanol and ultrapure water from the dispersion, and a fully sized continuous long carbon fiber polymer resin PPS mixture is obtained (the sizing amount of the aqueous resin dispersion after curing in the prepreg is 32wt%).

[0090] The continuous long carbon fiber polymer resin PPS mixture is pressed into continuous long carbon fiber prepreg through a vertical twin-roll mill at 340°C.

[0091] Comparative Example 1

[0092] The aqueous resin dispersion in this case comprises the following materials in 100% by weight percentage: 5% modified acrylate aqueous emulsion, 28% PPS powder with a particle size of 30μm, and 67% pure water. Following the above proportions, PPS powder is added to the modified acrylate aqueous emulsion and stirred for 15 minutes under continuous stirring, followed by the addition of pure water and stirring for another 15 minutes to obtain the desired product.

[0093] The dispersion photograph in this case is as follows: Figure 1 As shown, the PPS polymer powder immediately floats to the surface of the liquid after stirring and dispersion, and the particles are distinct. Compared with Example 1, the dispersion does not contain ethanol, and the polymer cannot be effectively dispersed in the dispersion. Therefore, no prepreg will be prepared for this case.

[0094] Comparative Example 2

[0095] The aqueous resin dispersion in this case comprises the following materials in 100% by weight percentage: 28% PPS powder with a particle size of 30μm, 10% anhydrous ethanol, and 62% pure water. Following the above proportions, PPS powder is added to anhydrous ethanol and stirred for 15 minutes, followed by the addition of pure water and stirring for another 15 minutes to obtain the desired solution.

[0096] The dispersion photograph in this case is as follows: Figure 1 As shown, compared with Example 1, the dispersion without the participation of modified acrylate aqueous emulsion has already undergone significant sedimentation after 1 minute, and the polymer cannot be effectively dispersed in the aqueous dispersion.

[0097] The above-mentioned aqueous resin dispersion was used to prepare continuous long carbon fiber prepreg, and the process was the same as in Example 1.

[0098] The SEM image of the continuous long carbon fiber prepreg prepared in this case is shown below. Figure 2 As shown, after the water-based resin dispersion is cured, only PPS resin has a poor pre-impregnation effect on carbon fibers, and there are many obvious dry fibers on the carbon fibers.

[0099] Comparative Example 3

[0100] The aqueous resin dispersion in this case comprises the following materials in 100% by weight: 5% modified acrylate aqueous emulsion, 28% PPS powder with a particle size of 30 μm, 10% anhydrous ethanol, and 57% pure water. The dispersion preparation process is the same as in Example 1.

[0101] The synthesis of the modified acrylate aqueous emulsion is the same as in Example 1, except that the composition of the monomer emulsion in step (1) is different (i.e., there is no short-chain alkyl ester monomer of acrylate in this case): 90 mL of ultrapure water, 2.5 g of ammonium perfluorononanoate, and 2.5 g of sodium perfluorodecyloxybenzenesulfonate are added to a 500 mL round-bottom flask. After stirring and dissolving, 24.6 g of octadecyl acrylate and 28.4 g of dodecyl acrylate are added in sequence. The mixture is stirred and emulsified at room temperature for 30 min to obtain the monomer emulsion.

[0102] The above-mentioned aqueous resin dispersion was used to prepare continuous long carbon fiber prepreg, and the process was the same as in Example 1.

[0103] The dispersion photograph in this case is as follows: Figure 1 As shown, compared with the dispersion in Example 1, although the polymer can be dispersed in the aqueous dispersion, it has already agglomerated and settled after 3 minutes, with obvious clear liquid in the upper layer and poor stability.

[0104] Comparative Example 4

[0105] The aqueous resin dispersion in this case comprises the following materials in 100% by weight: 2% modified acrylate aqueous emulsion, 28% PPS powder with a particle size of 30 μm, 10% anhydrous ethanol, and 60% pure water. The dispersion preparation process is the same as in Example 1.

[0106] The synthesis of the modified acrylate aqueous emulsion is the same as in Example 1, except that the composition of the monomer emulsion in step (1) is different (i.e., there is no long-chain alkyl ester monomer of acrylate in this case): 90 mL of ultrapure water, 2.5 g of ammonium perfluorononanoate, and 2.5 g of sodium perfluorodecoxybenzenesulfonate are added to a 500 mL round-bottom flask. After stirring and dissolving, 31.8 g of ethyl acrylate and 21.2 g of isoamyl acrylate are added in sequence. The mixture is stirred and emulsified at room temperature for 30 min to obtain the monomer emulsion.

[0107] The above-mentioned aqueous resin dispersion was used to prepare continuous long carbon fiber prepreg, and the process was the same as in Example 1.

[0108] The dispersion photograph in this case is as follows: Figure 1As shown, compared with the dispersion in Example 1, although the polymer can be dispersed in the aqueous dispersion, it has already agglomerated and settled after 3 minutes, with obvious clear liquid in the upper layer and poor stability.

[0109] Comparative Example 5

[0110] The aqueous resin dispersion in this case comprises the following materials in 100% by weight: 5% modified acrylate aqueous emulsion, 28% PPS powder with a particle size of 30 μm, 10% anhydrous ethanol, and 57% pure water. The dispersion preparation process is the same as in Example 1.

[0111] The synthesis of the modified acrylate aqueous emulsion is the same as in Example 1, except that the composition of the monomer emulsion in step (1) is different: 90 mL of ultrapure water and 5 g of ammonium perfluorononanoate are added to a 500 mL round-bottom flask, stirred and dissolved, and then 13 g of octadecyl acrylate, 15 g of dodecyl acrylate, 15 g of ethyl acrylate and 10 g of isoamyl acrylate are added in sequence. The mixture is stirred and emulsified at room temperature for 30 min to obtain the monomer emulsion.

[0112] The above-mentioned aqueous resin dispersion was used to prepare continuous long carbon fiber prepreg, and the process was the same as in Example 1.

[0113] Comparative Example 6

[0114] The aqueous resin dispersion in this case comprises the following materials in 100% by weight: 2% modified acrylate aqueous emulsion, 28% PPS powder with a particle size of 30 μm, 10% anhydrous ethanol, and 60% pure water. The dispersion preparation process is the same as in Example 1.

[0115] The synthesis of the modified acrylate aqueous emulsion is the same as in Example 1, except that the composition of the monomer emulsion in step (1) is different: 90 mL of ultrapure water and 5 g of sodium perfluorodecyloxybenzenesulfonate are added to a 500 mL round-bottom flask, stirred and dissolved, and then 13 g of octadecyl acrylate, 15 g of dodecyl acrylate, 15 g of phenylethyl acrylate and 10 g of isoamyl acrylate are added in sequence. The mixture is stirred and emulsified at room temperature for 30 min to obtain the monomer emulsion.

[0116] The above-mentioned aqueous resin dispersion was used to prepare continuous long carbon fiber prepreg, and the process was the same as in Example 1.

[0117] Test case

[0118] The performance of the prepregs in the above cases was tested, and the results are shown in Table 1.

[0119] Table 1 Prepreg Performance in Each Case

[0120]

[0121] As shown in Table 1, the present invention synthesizes modified acrylate emulsion, which can form an effective aqueous resin dispersion with polymer resin powder. This effectively solves the problems of poor dispersion, easy agglomeration and sedimentation of polymer resin powder in water. At the same time, it can be used for surface modification of carbon materials, which can promote the adhesion between fibers. It has a good prepreg effect on carbon fibers, especially continuous long carbon fibers. The resulting prepreg has no obvious dry yarn and has better mechanical properties.

[0122] Compared with Comparative Examples 1 and 2, Example 1 is derived from... Figure 1 As shown in Table 1, the addition of anhydrous ethanol does not easily cause foaming in the emulsion system. The aqueous dispersion formed by the modified acrylate aqueous emulsion in the presence of anhydrous ethanol effectively promotes the uniform dispersion of polymer powder, resulting in prepreg with better mechanical properties. Compared with Examples 1, 3, and 4, the aqueous resin dispersions formed by emulsions synthesized using only long-chain alkyl ester monomers or short-chain alkyl ester monomers of acrylic acid showed poor polymer dispersibility and all exhibited significant sedimentation within 3 minutes. Figure 1 In Comparative Examples 3 and 4, distinctly stratified aqueous phases were formed. The prepregs prepared in Comparative Examples 3 and 4 showed slightly worse tensile mechanical properties compared to the prepreg in Example 1, but significantly lower flexural and compressive mechanical properties. In Comparative Examples 5 and 6, only one perfluorinated nonpolar emulsifier was added during emulsion synthesis. The resulting aqueous resin dispersions exhibited poorer dispersion stability of the polymer powder compared to Example 1, but the absence of one of the perfluorinated nonpolar emulsifiers had a relatively small impact on mechanical properties.

[0123] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An aqueous resin dispersion of a carbon material, characterized in that, Includes the following materials at 100% by weight: The composition consists of 2%-10% modified acrylate aqueous emulsion, 15%-30% polymer resin powder, 8%-20% anhydrous ethanol, and the balance being pure water. The modified acrylate aqueous emulsion has a solid content in the range of 20wt%-40wt% and a pH of 7-8; The modified acrylate aqueous emulsion is obtained by emulsion polymerization of monomer emulsion under the action of an initiator. The monomer emulsion consists of the following raw materials in 100% by weight percentage: 12%-25% long-chain alkyl acrylate monomers, 12%-25% short-chain alkyl acrylate monomers, 2.5%-3.5% perfluorinated nonpolar emulsifier, and the balance being pure water. The long-chain alkyl acrylate monomers are selected from one or more of the following: docosyl acrylate, docosyl methacrylate, octadecyl acrylate, octadecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, tetradecyl acrylate, tridecyl methacrylate, dodecyl acrylate, and dodecyl methacrylate. The short-chain alkyl acrylate monomers are selected from one or more of 2-phenylethyl acrylate, 2-phenylethyl methacrylate, isoamyl acrylate, amyl methacrylate, isobutyl methacrylate, and phenyl acrylate. The perfluorononpolar emulsifier is selected from ammonium perfluorononanoate and sodium perfluorodecoxybenzenesulfonate, with a mass ratio of ammonium perfluorononanoate to sodium perfluorodecoxybenzenesulfonate of 0.1-1.2:1; The polymer resin powder is a non-polar thermoplastic polymer material, and the particle size of the polymer resin powder is less than 50 μm.

2. The aqueous resin dispersion of a carbon material according to claim 1, characterized in that, The monomer emulsion is composed of the following raw materials in 100% by weight percentage: 0%-15% octadecyl methacrylate monomer, 5%-15% dodecyl methacrylate monomer, 8%-18% 2-phenylethyl methacrylate monomer, 0%-10% isoamyl acrylate monomer, 2.5%-3.5% perfluorinated nonpolar emulsifier, and the balance being pure water.

3. The aqueous resin dispersion of a carbon material according to claim 2, characterized in that, The initiator is selected from potassium persulfate and / or ammonium persulfate, and the amount of the initiator is 1.2%-1.8% of the total weight of the monomers in the monomer emulsion; Before the emulsion polymerization reaction occurs, baking soda needs to be added, and the amount of baking soda is in the range of 60-90% of the weight of the initiator; after the emulsion polymerization reaction is completed, the pH value is adjusted to 7-8 with ammonia.

4. The aqueous resin dispersion of a carbon material according to claim 3, characterized in that, The modified acrylate aqueous emulsion is obtained as follows: long-chain alkyl ester monomers of acrylate, short-chain alkyl ester monomers of acrylate, perfluorinated nonpolar emulsifier and pure water are pre-emulsified at room temperature for at least 10 minutes to form a monomer emulsion. Add a portion of the monomer emulsion to a baking soda solution, preheat to 60-80℃, add a portion of the initiator solution and react for 5-15 minutes. Then, add the remaining portion of the monomer emulsion and a portion of the initiator solution dropwise over 2 hours. Finally, add the remaining portion of the initiator solution dropwise over 1 hour and continue the reaction for 15-45 minutes. Then, raise the temperature to 80-90℃ and mature for 50 minutes to 1.5 hours to complete the emulsion polymerization. After cooling, adjust the pH value to 7-8 with ammonia.

5. A carbon fiber prepreg, characterized in that, The carbon fiber is impregnated and sized using an aqueous resin dispersion of the carbon material as described in any one of claims 1-4, with an impregnation time of at least 1 second, and the sizing amount of the aqueous resin dispersion after curing in the carbon fiber prepreg exceeds 25 wt%.

6. The carbon fiber prepreg according to claim 5, characterized in that, The carbon fiber is selected from short carbon fiber or continuous long carbon fiber; Before impregnation, the carbon fiber needs to be heat-treated at at least 300°C to remove the original epoxy sizing agent on the surface; after impregnation, the carbon fiber is dried in the range of 100-180°C, and then pressed in the melting temperature range of the polymer resin powder to obtain carbon fiber prepreg.

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