Water-based resin dispersion liquid of carbon material and carbon fiber prepreg

Abstract

The invention relates to the field of carbon fiber modification, in particular to a water-based resin dispersion liquid of a carbon material and a carbon fiber prepreg, which are prepared from the following materials: modified acrylate water-based emulsion, polymer resin powder, absolute ethyl alcohol and pure water, the modified acrylate water-based emulsion is obtained by carrying out emulsion polymerization on a monomer emulsion under the action of an initiator, wherein the monomer emulsion is obtained by emulsifying the following raw materials: an olefine acid long-chain alkyl ester monomer, an acrylic acid short-chain alkyl ester monomer, a perfluorinated non-polar emulsifier and pure water; the water-based resin dispersion liquid is formed by synthesizing the modified acrylate emulsion and the polymer resin powder, the problems that the polymer resin powder is poor in dispersion in water and prone to agglomeration and sedimentation can be effectively solved, meanwhile, the water-based resin dispersion liquid is used for modifying the surface of a carbon material, adhesion between fibers can be promoted, and the water-based resin dispersion liquid is formed. And the preimpregnation effect on carbon fibers, especially continuous long carbon fibers, is good, and the formed prepreg does not have obvious dry yarns.

Description

Technical Field

[0001] The present invention relates to the field of carbon fiber modification, and particularly to an aqueous resin dispersion of carbon materials and a carbon fiber prepreg. Background Art

[0002] A carbon fiber prepreg, also known as a carbon fiber prepreg cloth, is a carbon fiber composite material processed through processes such as film coating, hot pressing, cooling, film laminating, and winding after the carbon fiber is fully infiltrated with a resin matrix.

[0003] The production methods of carbon fiber prepregs mainly include the following main steps and process methods:

[0004] 1) Solution impregnation method: Dissolve the resin in a low-boiling solvent to form a solution with a specific concentration, then impregnate the fiber bundle or fabric with the resin solution at a specified speed, control the resin content with auxiliary tools, volatilize the low-boiling solvent by drying, and finally wind it up.

[0005] 2) Hot melt impregnation method: Heat the resin to a molten state, then pass the carbon fiber through the molten resin to fully infiltrate the carbon fiber with the resin, and finally cool the impregnated carbon fiber to obtain the prepreg. The hot melt impregnation system generally includes three parts: a screw extruder, an impregnation die, and an impregnation roller. The carbon fiber enters the yarn spreading device after being adjusted by the yarn frame, and the fiber after yarn spreading passes through the impregnation die at a constant traction speed, and is impregnated with the fiber by generating an impregnation pressure through contact with the roller in the die. After impregnation, the prepreg is obtained through the traction device and the winding device.

[0006] 3) Powder impregnation method: Disperse the resin powder in water or other solvents to form a dispersion of the resin powder, and pass the carbon fiber through the dispersion under the action of a traction roller to uniformly adsorb the resin powder on the carbon fiber monofilament. Ultrasonic vibration can be assisted in this process to ensure uniform powder distribution. The impregnated carbon fiber passes through a drying device to remove the excess dispersant, so that the resin powder firmly adheres to the surface of the carbon fiber. The dried carbon fiber passes through a heating device to melt the resin powder and infiltrate the carbon fiber to form a prepreg, and then is mixed with the carbon fiber. After that, the resin powder is melted by heating, pressurizing, etc. to infiltrate the carbon fiber to obtain the prepreg.

[0007] Patent No. CN 116855078 A discloses a slurry for carbon fiber prepreg, a preparation method thereof, and a preparation method of prepreg. It discloses a slurry for carbon fiber prepreg, a preparation method thereof, and a preparation method of prepreg. The slurry is prepared by adding thermoplastic resin powder, slurry dispersion medium, surfactant, defoaming agent, viscosity regulator, modification material, etc. This patent reduces the surface energy of the slurry dispersion medium (water) by adding a surfactant, but the dispersion stability of the resin powder in it is poor, the powder is prone to agglomeration, and continuous stirring is required to reduce the risk of sedimentation. Summary of the Invention

[0008] In order to solve the technical problem of poor dispersion of polymer resin powder in water, a water-based resin dispersion liquid for carbon materials and a carbon fiber prepreg are provided. In the present invention, a modified acrylate emulsion is synthesized to form a water-based resin dispersion liquid with polymer resin powder, which can effectively solve the problems of poor dispersion, easy agglomeration and sedimentation of polymer resin powder in water. At the same time, it is used for surface modification of carbon materials, can promote the adhesion between fibers, has a good impregnation effect on carbon fibers, especially continuous long carbon fibers, and the formed prepreg has no obvious dry yarn.

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

[0010] A water-based resin dispersion liquid for carbon materials, comprising the following materials in 100% by weight percentage:

[0011] 2%-10% of modified acrylate water-based emulsion, 15%-30% of polymer resin powder, 8%-20% of absolute ethanol, and the balance is pure water;

[0012] Wherein the solid content of the modified acrylate water-based emulsion is in the range of 20wt%-40wt% and pH = 7-8;

[0013] The modified acrylate water-based 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% of long-chain alkyl acrylate monomers, 12%-25% of short-chain alkyl acrylate monomers, 2.5%-3.5% of perfluorinated non-polar emulsifier, and the balance is pure water;

[0014] The alkyl carbon chain of the long-chain alkyl acrylate monomer has at least 12 carbon atoms, and the alkyl carbon chain of the short-chain alkyl acrylate monomer has less than 10 carbon atoms and greater than or equal to 4 carbon atoms.

[0015] Further, the long-chain alkyl acrylate monomer is selected from one or more of 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 monomer is selected from one or more of 2-phenethyl acrylate, 2-phenethyl methacrylate, isoamyl acrylate, pentyl methacrylate, isobutyl methacrylate, and phenyl acrylate.

[0017] Still further, the monomer emulsion consists of the following raw materials in 100% by weight: 0%-15% of octadecyl (meth)acrylate monomer, 5%-15% of dodecyl (meth)acrylate monomer, 8%-18% of 2-phenethyl (meth)acrylate monomer, 0%-10% of isoamyl acrylate monomer, 2.5%-3.5% of perfluorinated non-polar emulsifier, and the balance being pure water.

[0018] Further, the initiator is selected from water-soluble persulfates such as potassium persulfate and ammonium persulfate, and the dosage 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, baking soda needs to be added, and the dosage of the 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 water. In the emulsion polymerization reaction, the addition of persulfate will reduce the pH value of the system, resulting in a slowdown in the reaction rate, coarser emulsion particles, and even phenomena such as gel breaking and demulsification. The addition of baking soda can neutralize the acidic substances generated by the persulfate initiator, thereby adjusting and controlling the pH value of the polymerization system and ensuring the smooth progress of the reaction.

[0020] Still further, the method for obtaining the modified acrylate aqueous emulsion is as follows: First, the long-chain alkyl acrylate monomer, short-chain alkyl acrylate monomer, perfluorinated non-polar emulsifier, and pure water are pre-emulsified at room temperature for at least 10 min to form a monomer emulsion;

[0021] Part of the monomer emulsion is added to the aqueous baking soda solution, preheated to 60-80 °C, and part of the initiator aqueous solution is added for reaction for 5-15 min. Then, the remaining part of the monomer emulsion and part of the initiator aqueous solution are simultaneously added dropwise within 2 hours. Finally, the remaining part of the initiator aqueous solution is added dropwise within 1 hour and the reaction continues for 15-45 min. Then, the temperature is raised to 80-90 °C for curing for 50 min-1.5 h to complete the emulsion polymerization. After cooling, the pH value is adjusted to 7-8 with ammonia water.

[0022] Furthermore, the perfluorinated non-polar emulsifier is selected from ammonium perfluorononanoate and sodium perfluorodecyloxybenzenesulfonate, and the mass ratio of ammonium perfluorononanoate to sodium perfluorodecyloxybenzenesulfonate is 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 for synthesizing the modified acrylate aqueous emulsion are non-polar monomers, which can promote the dispersion of the non-polar polymer material in the emulsion.

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

[0025] On the other hand, the present invention provides a carbon fiber prepreg. The carbon fiber is impregnated and sized with the aqueous resin dispersion of the above carbon material, and the impregnation time is at least 1 second. The sizing amount of the cured aqueous resin dispersion in the carbon fiber prepreg accounts for more than 25 wt%; preferably, the sizing amount of the cured aqueous resin dispersion in the carbon fiber prepreg accounts for 30 wt%-40 wt%.

[0026] Furthermore, the carbon fiber is selected from short carbon fibers or continuous long carbon fibers; 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; 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 the carbon fiber prepreg.

[0027] Still further, the carbon fiber prepreg is a continuous long carbon fiber prepreg, and the obtaining method is: arranging one or dozens of continuous long carbon fibers neatly on a heating roller, forming heat treatment on the carbon fiber by heating the heating roller to remove the original epoxy sizing agent on the surface, then immersing the continuous long carbon fibers into the aqueous resin dispersion of the above carbon material by means of traction, drying through a drying tunnel after impregnation to remove the solvent, obtaining a fully sized continuous long carbon fiber polymer resin mixture, and then roll-pressing or laminating to obtain the continuous long carbon fiber prepreg.

[0028] Beneficial technical effects:

[0029] The aqueous resin dispersion of the present invention can enable good compatibility between the carbon fiber and the non-polar resin powder, enhance the interfacial properties between 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 be fully and evenly adsorbed with carbon fiber; the modified acrylate aqueous emulsion among them has better fluidity compared with other resin powders, correspondingly improves and enhances the wettability between the non-polar resin powder and the carbon fiber, and is used to adjust the viscosity and adhesion of the composite material system;

[0031] Adding absolute ethanol to the aqueous resin dispersion of the present invention can promote the dispersion of non-polar resin in the aqueous phase, enable the preparation of a higher-concentration dispersion for sizing carbon fiber, and at the same time avoid the agglomeration of resin powder. Brief Description of the Drawings

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

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

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments and drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The description of at least one exemplary embodiment below is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to 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 present invention. Technologies and methods known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies and methods should be regarded as part of the specification. In all examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0036] In the following embodiments, the experimental methods without specific conditions are generally determined according to national standards; if there is no corresponding national standard, they are carried out according to general standard requirements or general methods.

[0037] It should be noted that the writing of (meth)acrylic acid means that methyl is optional, that is, it represents acrylic acid or methacrylic acid, and so on.

[0038] Example 1

[0039] An aqueous resin dispersion of carbon materials, comprising the following materials in 100% by weight: 5% of a modified acrylate aqueous emulsion, 28% of PPS powder with a particle size of 30 μm, 10% of absolute ethanol, and 57% of pure water.

[0040] According to the above ratio, under continuous stirring, absolute ethanol and PPS powder are added to the modified acrylate aqueous emulsion and stirred for 15 min, and then pure water is added and stirred for 15 min to obtain the aqueous resin dispersion of carbon materials.

[0041] The above-mentioned modified acrylate aqueous emulsion is obtained by the following method:

[0042] (1) Monomer emulsion

[0043] In a 500 mL round-bottom flask, 90 mL of ultrapure water, 2.5 g of ammonium perfluorononanoate, and 2.5 g of perfluorodecyloxybenzenesulfonate are added. After stirring and dissolving, 13 g of octadecyl acrylate, 15 g of dodecyl acrylate, 15 g of phenethyl acrylate, and 10 g of isoamyl acrylate are added in sequence. Stir at 250 r / min at room temperature for 30 min to obtain a monomer emulsion.

[0044] (2) Emulsion polymerization

[0045] Weigh 0.8 g of potassium persulfate into a conical flask, dissolve it with 30 mL of ultrapure water to prepare an initiator aqueous solution, and place it in the refrigerator for later use;

[0046] In a 500 mL round-bottom flask, add 0.5 g of sodium bicarbonate and 15 mL of ultrapure water and stir to dissolve. Measure 20 mL of the monomer emulsion obtained in the previous step and add it to the reaction flask. Heat up to 80 °C at a stirring rate of 300 r / min, add 6 mL of the initiator aqueous solution and react until the system turns blue, and then continue to react for 10 min. First, add the remaining monomer emulsion dropwise and then add 21 mL of the initiator solution dropwise, and finish dropping in about 2 h; then add the remaining 3 mL of the initiator aqueous solution dropwise within 30 min, continue to react for 30 min, then heat up to 85 °C and cure for 1 h. After the emulsion polymerization is completed, cool to 60 °C, adjust the pH value to 7 - 8 with ammonia water, and discharge to obtain the modified acrylate aqueous emulsion, and the solid content of the emulsion is about 27 wt%.

[0047] The dispersion photograph of this case is as Figure 1 shown. It can be seen that the polymer PPS powder has a good dispersion effect in the dispersion liquid, and there is no sedimentation phenomenon after 30 min.

[0048] Preparation method of continuous long carbon fiber prepreg: Arrange 25 strands of continuous long carbon fibers neatly on a heating roller, and heat-treat the fibers through a 360 °C heating roller to remove the original epoxy sizing agent on the surface. Then, use a traction method to immerse the continuous long carbon fibers into the obtained aqueous resin dispersion (the impregnation time is about 3 s). Then, pass through a 130 °C drying tunnel to remove anhydrous ethanol and ultrapure water in the dispersion, and obtain a continuously long carbon fiber polymer resin PPS mixture fully sized (the sizing amount after curing of the aqueous resin dispersion in the prepreg accounts for 34 wt%).

[0049] Roll and press the continuous long carbon fiber polymer resin PPS mixture through a 320 °C vertical double-roll machine to obtain a continuous long carbon fiber prepreg.

[0050] The SEM diagram of the continuous long carbon fiber prepreg prepared in this case is as Figure 2 shown. It can be seen that the modified acrylic resin and PPS resin after curing of the aqueous resin dispersion have a good impregnation effect on the fibers, and there is no obvious dry yarn of carbon fibers.

[0051] Example 2

[0052] An aqueous resin dispersion of a carbon material, including the following materials in 100% weight percentage: 5% modified acrylate aqueous emulsion, 30% PPS powder with a particle size of 30 μm, 10% anhydrous ethanol, and 55% pure water.

[0053] According to the above ratio, under continuous stirring, add anhydrous ethanol and PPS powder to the modified acrylate aqueous emulsion and stir for 15 min, then add pure water and stir for 15 min to obtain the aqueous resin dispersion of the carbon material.

[0054] Among them, the above-mentioned modified acrylate aqueous emulsion is obtained by the following method:

[0055] (1) Monomer emulsion

[0056] In a 500 mL round-bottom flask, add 90 mL of ultrapure water, 2.2 g of ammonium perfluorononanoate, and 2.0 g of perfluorodecyloxybenzenesulfonate. After stirring and dissolving, add 18 g of octadecyl acrylate, 20 g of dodecyl acrylate, and 20 g of phenethyl acrylate in sequence, and stir at 250 r / min at room temperature for 30 min to obtain a monomer emulsion.

[0057] (2) Emulsion polymerization

[0058] Weigh 1.0 g of potassium persulfate in a conical flask, dissolve it with 30 mL of ultrapure water to prepare an initiator aqueous solution, and place it in the refrigerator for later use;

[0059] Add 0.8 g of sodium bicarbonate and 15 mL of ultrapure water to a 500 mL round-bottom flask, stir to dissolve. Measure 20 mL of the monomer emulsion obtained in the previous step and add it to the reaction flask. Heat to 80 °C at a stirring rate of 300 r / min, add 6 mL of the initiator aqueous solution and react until the system turns blue, then continue to react for 10 min. First, add the remaining monomer emulsion dropwise, and then add 21 mL of the initiator solution dropwise, and finish dropping within about 2 h; then add the remaining 3 mL of the initiator aqueous solution dropwise within 30 min, continue to react for 30 min, then heat to 85 °C and cure for 1 h. After the emulsion polymerization is completed, cool to 60 °C, adjust the pH value to 7 - 8 with ammonia water, discharge, and obtain the modified acrylate aqueous emulsion with a solid content of about 29 wt%.

[0060] The photo of the dispersion in this case is as Figure 1 shown. It can be seen that the polymer PPS powder has a good dispersion effect in the dispersion, and there is no sedimentation phenomenon after 30 min.

[0061] Preparation method of continuous long carbon fiber prepreg: Arrange 25 strands of continuous long carbon fibers neatly on a heating roller, heat-treat the fibers through a heating roller at 360 °C to remove the original epoxy sizing agent on the surface, and then immerse the continuous long carbon fibers into the aqueous resin dispersion obtained above by means of traction (impregnation time 3 s), and then pass through a drying channel at 130 °C to remove anhydrous ethanol and ultrapure water in the dispersion, and obtain a fully sized continuous long carbon fiber polymer resin PPS mixture (the sizing amount after curing of the aqueous resin dispersion in the prepreg accounts for 35 wt%);

[0062] Roll and press the continuous long carbon fiber polymer resin PPS mixture through a vertical double-roll machine at 320 °C to obtain a continuous long carbon fiber prepreg.

[0063] Example 3

[0064] An aqueous resin dispersion of a carbon material, comprising the following materials in 100% by weight: 3% of modified acrylate aqueous emulsion, 15% of PPS powder with a particle size of 30 μm, 8% of anhydrous ethanol, and 74% of pure water.

[0065] According to the above ratio, under continuous stirring, add anhydrous ethanol and PPS powder to the modified acrylate aqueous emulsion and stir for 15 min, and then add pure water and stir for 15 min to obtain the aqueous resin dispersion of the carbon material.

[0066] Among them, the above-mentioned modified acrylate aqueous emulsion is obtained by the following method:

[0067] (1) Monomer emulsion

[0068] In a 500 mL round-bottom flask, add 90 mL of ultrapure water, 2.0 g of ammonium perfluorononanoate, and 3.0 g of perfluorodecyloxybenzenesulfonate. After stirring and dissolving, add 15 g of octadecyl acrylate, 10 g of dodecyl acrylate, 12 g of phenethyl acrylate, and 13 g of isoamyl acrylate in sequence. Stir at 250 r / min for 30 min at room temperature to obtain a monomer emulsion.

[0069] (2) Emulsion polymerization

[0070] Weigh 0.6 g of potassium persulfate into a conical flask, dissolve it with 30 mL of ultrapure water to prepare an initiator aqueous solution, and place it in the refrigerator for later use.

[0071] Add 0.5 g of sodium bicarbonate and 15 mL of ultrapure water to a 500 mL round-bottom flask, stir and dissolve. Measure 20 mL of the monomer emulsion obtained in the previous step and add it to the reaction flask. Heat to 80 °C at a stirring rate of 300 r / min, add 6 mL of the initiator aqueous solution and react until the system turns blue, then continue to react for 10 min. First, add the remaining monomer emulsion dropwise, and then add 21 mL of the initiator solution dropwise, and finish dropping in about 2 h. Then, add the remaining 3 mL of the initiator aqueous solution dropwise within 30 min, continue to react for 30 min, then heat to 85 °C and cure for 1 h. After the emulsion polymerization is completed, cool to 60 °C, adjust the pH value to 7 - 8 with ammonia water, and discharge to obtain a modified acrylate aqueous emulsion with a solid content of about 27 wt%.

[0072] Preparation method of continuous long carbon fiber prepreg: Arrange 25 strands of continuous long carbon fibers neatly on a heating roller, heat-treat the fibers through a heating roller at 380 °C to remove the original epoxy sizing agent on the surface, and then immerse the continuous long carbon fibers into the aqueous resin dispersion obtained above by means of traction (immersion time 5 s). Then, pass through a drying tunnel at 120 °C to remove anhydrous ethanol and ultrapure water in the dispersion to obtain a well-sized continuous long carbon fiber polymer resin PPS mixture (the sizing amount after curing of the aqueous resin dispersion in the prepreg accounts for 31 wt%).

[0073] Roll the continuous long carbon fiber polymer resin PPS mixture through a vertical double-roll machine at 260 °C to obtain a continuous long carbon fiber prepreg.

[0074] Example 4

[0075] An aqueous resin dispersion of a carbon material, comprising the following materials in 100% weight percentage: 10% of modified acrylate aqueous emulsion, 18% of PPS powder with a particle size of 30 μm, 15% of anhydrous ethanol, and 57% of pure water.

[0076] Under continuous stirring, add absolute ethanol and PPS powder to the modified acrylate aqueous emulsion according to the above ratio and stir for 15 min, then add pure water and stir for 15 min to obtain the aqueous resin dispersion of the carbon material.

[0077] Among them, the above-mentioned modified acrylate aqueous emulsion is obtained by the following method:

[0078] (1) Monomer emulsion

[0079] In a 500 mL round-bottom flask, add 90 mL of ultrapure water, 1.5 g of ammonium perfluorononanoate, and 3.5 g of perfluorodecyloxybenzenesulfonate. After stirring and dissolving, add 20 g of dodecyl acrylate, 25 g of phenethyl acrylate, and 10 g of isoamyl acrylate in sequence. Stir at 250 r / min at room temperature for emulsification for 30 min to obtain the monomer emulsion.

[0080] (2) Emulsion polymerization

[0081] Weigh 0.8 g of potassium persulfate into a conical flask, dissolve it with 30 mL of ultrapure water to prepare an initiator aqueous solution, and place it in the refrigerator for later use;

[0082] Add 0.5 g of sodium bicarbonate and 15 mL of ultrapure water to a 500 mL round-bottom flask and stir to dissolve. Measure 20 mL of the monomer emulsion obtained in the previous step and add it to the reaction flask. Raise the temperature to 80 °C at a stirring rate of 300 r / min, add 6 mL of the initiator aqueous solution and react until the system turns blue, then continue to react for 10 min. First, add the remaining monomer emulsion dropwise and then add 21 mL of the initiator solution dropwise, and finish dropping in about 2 h; then add the remaining 3 mL of the initiator aqueous solution dropwise within 30 min, continue to react for 30 min, then raise the temperature to 85 °C and cure for 1 h. After the emulsion polymerization is completed, cool to 60 °C, adjust the pH value to 7 - 8 with ammonia water, and discharge to obtain the modified acrylate aqueous emulsion with a solid content of about 28 wt%.

[0083] Preparation method of continuous long carbon fiber prepreg: Arrange 25 continuous long carbon fibers neatly on the heating roller, heat-treat the fibers through a heating roller at 380 °C to remove the original epoxy sizing agent on the surface, then use the traction method to immerse the continuous long carbon fibers into the above-mentioned aqueous resin dispersion (impregnation time 4 s), and then pass through a drying channel at 130 °C to remove absolute ethanol and ultrapure water in the dispersion to obtain a fully sized continuous long carbon fiber polymer resin PPS mixture (the sizing amount after curing of the aqueous resin dispersion in the prepreg accounts for 36 wt%);

[0084] Roll the continuous long carbon fiber polymer resin PPS mixture through a vertical double-roll machine at 300 °C to obtain the continuous long carbon fiber prepreg.

[0085] Example 5

[0086] An aqueous resin dispersion of a carbon material, comprising the following materials in 100% by weight: 3% of a modified acrylate aqueous emulsion, 25% of PPS powder with a particle size of 45 μm, 12% of absolute ethanol, and 60% of pure water.

[0087] According to the above ratio, under continuous stirring, absolute ethanol and PPS powder are added to the modified acrylate aqueous emulsion and stirred for 15 min, and then pure water is added and stirred for 15 min to obtain the aqueous resin dispersion of the carbon material.

[0088] The above-mentioned modified acrylate aqueous emulsion is obtained by the following method:

[0089] (1) Monomer emulsion

[0090] In a 500 mL round-bottom flask, 90 mL of ultrapure water, 0.5 g of ammonium perfluorononanoate, and 3.5 g of sodium perfluorodecyloxybenzenesulfonate are added. After stirring and dissolving, 13 g of octadecyl acrylate, 15 g of dodecyl acrylate, 15 g of phenethyl acrylate, and 10 g of isoamyl acrylate are added in sequence. Stir at 250 r / min at room temperature for emulsification for 30 min to obtain the monomer emulsion.

[0091] (2) Emulsion polymerization

[0092] Weigh 0.3 g of potassium persulfate and 0.5 g of ammonium persulfate in a conical flask, dissolve them with 30 mL of ultrapure water to prepare an initiator aqueous solution, and place it in the refrigerator for standby;

[0093] In a 500 mL round-bottom flask, add 0.5 g of sodium bicarbonate and 15 mL of ultrapure water and stir to dissolve. Measure 20 mL of the monomer emulsion obtained in the previous step and add it to the reaction flask. Heat up to 80 °C at a stirring rate of 300 r / min, add 6 mL of the initiator aqueous solution and react until the system turns blue, and then continue to react for 10 min. First, add the remaining monomer emulsion dropwise and then add 21 mL of the initiator solution dropwise, and finish dropping within about 2 h; then add the remaining 3 mL of the initiator aqueous solution dropwise within 30 min, continue to react for 30 min, then heat up to 85 °C and cure for 1 h. After the emulsion polymerization is completed, cool to 60 °C, adjust the pH value to 7 - 8 with ammonia water, and discharge to obtain the modified acrylate aqueous emulsion, and the solid content of the emulsion is about 27 wt%.

[0094] Preparation method of continuous long carbon fiber prepreg: Arrange 25 continuous long carbon fibers neatly on a heating roller, heat-treat the fibers through a heating roller at 400 °C to remove the original epoxy sizing agent on the surface, and then use a traction method to immerse the continuous long carbon fibers in the above-mentioned obtained aqueous resin dispersion (impregnation time 3 s), and then pass through a drying tunnel at 150 °C to remove absolute ethanol and ultrapure water in the dispersion to obtain a fully sized continuous long carbon fiber polymer resin PPS mixture (the sizing amount after curing of the aqueous resin dispersion in the prepreg accounts for 32 wt%);

[0095] The continuous long carbon fiber polymer resin PPS mixture is roll-pressed by a vertical double-roll machine at 340 °C to obtain continuous long carbon fiber prepreg.

[0096] Comparative Example 1

[0097] The aqueous resin dispersion of this example includes the following materials in 100% by weight: 5% of modified acrylate aqueous emulsion, 28% of PPS powder with a particle size of 30 μm, and 67% of pure water. According to the above ratio, under continuous stirring, PPS powder is added to the modified acrylate aqueous emulsion and stirred for 15 min, and then pure water is added and stirred for 15 min to obtain it.

[0098] The dispersion photo of this example is as Figure 1 shown. It can be seen that the polymer PPS powder immediately floats to the liquid surface and the particles are distinct after being stirred and dispersed. Compared with Example 1, there is no ethanol in the dispersion, and the polymer cannot be effectively dispersed in the dispersion. No prepreg will be prepared from this example subsequently.

[0099] Comparative Example 2

[0100] The aqueous resin dispersion of this example includes the following materials in 100% by weight: 28% of PPS powder with a particle size of 30 μm, 10% of absolute ethanol, and 62% of pure water. According to the above ratio, under continuous stirring, PPS powder is added to absolute ethanol and stirred for 15 min, and then pure water is added and stirred for 15 min to obtain it.

[0101] The dispersion photo of this example is as Figure 1 shown. Compared with Example 1, there is no modified acrylate aqueous emulsion in the dispersion, and obvious sedimentation has occurred at 1 min, and the polymer cannot be effectively dispersed in the aqueous dispersion.

[0102] The continuous long carbon fiber prepreg is prepared using the above aqueous resin dispersion, and the process is the same as that of Example 1.

[0103] The SEM image of the continuous long carbon fiber prepreg prepared in this example is as Figure 2 shown. It can be seen that only the PPS resin has a poor impregnation effect on the carbon fiber after the aqueous resin dispersion is cured, and there are many obvious dry yarns on the carbon fiber.

[0104] Comparative Example 3

[0105] The aqueous resin dispersion of this example includes the following materials in 100% by weight: 5% of modified acrylate aqueous emulsion, 28% of PPS powder with a particle size of 30 μm, 10% of absolute ethanol, and 57% of pure water. The preparation process of the dispersion is the same as that of Example 1;

[0106] Among them, the synthesis of the modified acrylate aqueous emulsion is the same as that in Example 1, except that the composition of the monomer emulsion in step (1) is different (i.e., there is no short-chain alkyl acrylate monomer in this case): In a 500 mL round-bottom flask, add 90 mL of ultrapure water, 2.5 g of ammonium perfluorononanoate, and 2.5 g of perfluorodecyloxybenzenesulfonate. After stirring and dissolving, add 24.6 g of octadecyl acrylate and 28.4 g of dodecyl acrylate in sequence, and stir and emulsify at room temperature for 30 min to obtain a monomer emulsion.

[0107] The continuous long carbon fiber prepreg was prepared using the above aqueous resin dispersion, and the process was the same as that in Example 1.

[0108] The dispersion photo of this case is as Figure 1 shown. Compared with the dispersion in Example 1, although the polymer can be dispersed in the aqueous dispersion, agglomeration and sedimentation have occurred at 3 min, the supernatant is obvious, and the stability is poor.

[0109] Comparative Example 4

[0110] The aqueous resin dispersion of this case includes the following materials in 100% by weight: 2% of modified acrylate aqueous emulsion, 28% of PPS powder with a particle size of 30 μm, 10% of absolute ethanol, and 60% of pure water. The preparation process of the dispersion is the same as that in Example 1;

[0111] Among them, the synthesis of the modified acrylate aqueous emulsion is the same as that in Example 1, except that the composition of the monomer emulsion in step (1) is different (i.e., there is no long-chain alkyl acrylate monomer in this case): In a 500 mL round-bottom flask, add 90 mL of ultrapure water, 2.5 g of ammonium perfluorononanoate, and 2.5 g of perfluorodecyloxybenzenesulfonate. After stirring and dissolving, add 31.8 g of phenethyl acrylate and 21.2 g of isoamyl acrylate in sequence, and stir and emulsify at room temperature for 30 min to obtain a monomer emulsion.

[0112] The continuous long carbon fiber prepreg was prepared using the above aqueous resin dispersion, and the process was the same as that in Example 1.

[0113] The dispersion photo of this case is as Figure 1 shown. Compared with the dispersion in Example 1, although the polymer can be dispersed in the aqueous dispersion, agglomeration and sedimentation have occurred at 3 min, the supernatant is obvious, and the stability is poor.

[0114] Comparative Example 5

[0115] The aqueous resin dispersion of this case includes the following materials in 100% by weight: 5% of modified acrylate aqueous emulsion, 28% of PPS powder with a particle size of 30 μm, 10% of absolute ethanol, and 57% of pure water. The preparation process of the dispersion is the same as that in Example 1;

[0116] Among them, the synthesis of the modified acrylate aqueous emulsion is the same as that in Example 1, except that the composition of the monomer emulsion in step (1) is different: In a 500 mL round-bottom flask, add 90 mL of ultrapure water and 5 g of ammonium perfluorononanoate. After stirring and dissolving, add 13 g of octadecyl acrylate, 15 g of dodecyl acrylate, 15 g of phenethyl acrylate, and 10 g of isoamyl acrylate in sequence. Stir and emulsify at room temperature for 30 min to obtain the monomer emulsion.

[0117] The continuous long carbon fiber prepreg is prepared using the above aqueous resin dispersion, and the process is the same as that in Example 1.

[0118] Comparative Example 6

[0119] The aqueous resin dispersion of this case includes the following materials in 100% weight percentage: 2% of modified acrylate aqueous emulsion, 28% of PPS powder with a particle size of 30 μm, 10% of absolute ethanol, and 60% of pure water. The preparation process of the dispersion is the same as that in Example 1;

[0120] Among them, the synthesis of the modified acrylate aqueous emulsion is the same as that in Example 1, except that the composition of the monomer emulsion in step (1) is different: In a 500 mL round-bottom flask, add 90 mL of ultrapure water and 5 g of sodium perfluorodecyloxybenzenesulfonate. After stirring and dissolving, add 13 g of octadecyl acrylate, 15 g of dodecyl acrylate, 15 g of phenethyl acrylate, and 10 g of isoamyl acrylate in sequence. Stir and emulsify at room temperature for 30 min to obtain the monomer emulsion.

[0121] The continuous long carbon fiber prepreg is prepared using the above aqueous resin dispersion, and the process is the same as that in Example 1.

[0122] Test Example

[0123] The prepregs of the above cases were subjected to performance tests, and the results are shown in Table 1.

[0124] Table 1 Performance of Prepregs of Each Case

[0125]

[0126] As can be seen from Table 1, by synthesizing the modified acrylate emulsion, the present invention can form an effective aqueous resin dispersion with the polymer resin powder, which can effectively solve the problems of poor dispersion, easy agglomeration and sedimentation of the polymer resin powder in water. At the same time, it is used for surface modification of carbon materials, which can promote the adhesion between fibers, has a good impregnation effect on carbon fibers, especially continuous long carbon fibers, and the formed prepreg has no obvious dry yarn and better mechanical properties.

[0127] Comparing Example 1 with Comparative Example 1 and Comparative Example 2, from Figure 1As can be seen from the data in Table 1, the addition of absolute ethanol does not easily cause foaming in the emulsion system. The aqueous dispersion formed by the modified acrylate aqueous emulsion in the presence of absolute ethanol can effectively promote the uniform dispersion of polymer powders, resulting in prepregs with good mechanical properties. Compared with Example 1, Comparative Example 3, and Comparative Example 4, the aqueous resin dispersions formed by emulsions synthesized using only long-chain alkyl acrylate monomers or short-chain alkyl acrylate monomers have poor dispersibility for polymers, and obvious sedimentation occurs within 3 minutes. Figure 1 In Comparative Example 3 and Comparative Example 4, an obvious water phase separation occurred; the prepregs prepared in Comparative Example 3 and Comparative Example 4 had slightly worse tensile mechanical properties than the prepreg in Example 1, but the bending and compressive mechanical properties decreased more. In Comparative Example 5 and Comparative Example 6, only one perfluorinated non-polar emulsifier was added during the synthesis of the emulsion. The dispersion stability of the prepared aqueous resin dispersion for polymer powders was worse than that of Example 1, but the absence of one of the perfluorinated non-polar emulsifiers had little effect on the mechanical properties.

[0128] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. An aqueous resin dispersion of a carbon material, characterized in that: The following materials are included in 100% by weight: Modified acrylic acid ester aqueous emulsion 2%-10%, polymer resin powder 15%-30%, anhydrous ethanol 8%-20%, the balance is pure water; The modified acrylic ester aqueous emulsion has a solid content in the range of 20wt%-40wt% and a pH of 7-8; The modified acrylic ester aqueous emulsion is obtained by emulsion polymerization of a monomer emulsion under the action of an initiator, wherein the monomer emulsion is composed of the following raw materials in 100% by weight: 12%-25% of a long-chain alkyl acrylate monomer, 12%-25% of a short-chain alkyl acrylate monomer, 2.5%-3.5% of a perfluorinated non-polar emulsifier, and the remainder is pure water; The number of carbon atoms in the alkyl carbon chain of the long-chain alkyl acrylate monomer is at least 12, and the number of carbon atoms in the alkyl carbon chain of the short-chain alkyl acrylate monomer is less than 10 and greater than or equal to 4.

2. The aqueous resin dispersion of a carbon material according to claim 1, characterized in that: The long-chain alkyl acrylate monomer is selected from one or more of behenyl acrylate, behenyl methacrylate, octadecyl acrylate, octadecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, tetradecyl acrylate, tridecyl methacrylate, dodecyl acrylate, and dodecyl methacrylate; The short-chain alkyl acrylate monomer is selected from one or more of 2-phenylethyl acrylate, 2-phenylethyl methacrylate, isopentyl acrylate, amyl methacrylate, isobutyl methacrylate, and phenyl acrylate.

3. The aqueous resin dispersion of carbon material according to claim 2, characterized in that: The monomer emulsion is composed of the following raw materials in 100% by weight: 0%-15% of octadecyl (meth)acrylate monomer, 5%-15% of dodecyl (meth)acrylate monomer, 8%-18% of 2-phenylethyl (meth)acrylate monomer, 0%-10% of isopentyl acrylate monomer, 2.5%-3.5% of perfluoro non-polar emulsifier, and the balance is pure water.

4. The aqueous resin dispersion of carbon material according to claim 3, characterized in that: The initiator is selected from persulfates such as potassium persulfate, ammonium persulfate and other water-soluble persulfates, 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 the baking soda used 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 water.

5. The aqueous resin dispersion of carbon material according to claim 4, characterized in that: The modified acrylic acid ester aqueous emulsion is obtained by pre-emulsifying a long-chain alkyl acrylate monomer, a short-chain alkyl acrylate monomer, a perfluoro non-polar emulsifier and pure water at room temperature for at least 10 minutes to form a monomer emulsion; Add part of the monomer emulsion to the baking soda aqueous solution, preheat to 60-80°C, add part of the initiator aqueous solution to react for 5-15 minutes, then add the remaining part of the monomer emulsion and part of the initiator aqueous solution dropwise at the same time within 2 hours, finally add the remaining part of the initiator aqueous solution dropwise within 1 hour and continue to react for 15-45 minutes, then heat to 80-90°C for aging for 50 minutes to 1.5 hours to complete the emulsion polymerization, and adjust the pH value to 7-8 with ammonia water after cooling.

6. The aqueous resin dispersion of carbon material according to claim 3, characterized in that: The perfluoro non-polar emulsifier is selected from ammonium perfluorononanoate and sodium perfluorodecyloxybenzenesulfonate, and the mass ratio of ammonium perfluorononanoate to sodium perfluorodecyloxybenzenesulfonate is 0.1-1.2:

1.

7. The aqueous resin dispersion of carbon material according to claim 3, characterized in that: 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.

8. A carbon fiber prepreg, characterized in that: The carbon fiber is impregnated and sized using the aqueous resin dispersion of the carbon material according to any one of claims 1 to 7, the impregnation time is at least 1 second, and the sizing amount of the aqueous resin dispersion in the carbon fiber prepreg after curing accounts for more than 25wt%.

9. The carbon fiber prepreg according to claim 8, characterized in that: 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; 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 a carbon fiber prepreg.

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