A nonionic epoxy resin modified waterborne polyurethane sizing agent for carbon fibers and a preparation method thereof

Abstract

The application provides a non-ionic epoxy resin modified water-based polyurethane sizing agent for carbon fibers and a preparation method thereof, and belongs to the technical field of carbon fiber surface treatment and sizing agents. The sizing agent comprises 10-15 parts of epoxy resin modified polyurethane and 85-90 parts of deionized water by weight; the epoxy resin modified polyurethane is prepared by reacting hydrophilic soft segment polyol, diisocyanate, chain extender and epoxy resin, and the structural formula is shown as formula 1. The application also provides a preparation method of the non-ionic epoxy resin modified water-based polyurethane sizing agent for carbon fibers. The method does not use catalyst and neutralizing agent throughout the whole process, and the obtained polyurethane can be directly self-emulsified to form a stable water-based sizing agent by means of the non-ionic hydrophilic chain segment introduced in the molecular chain. The prepared sizing agent has a particle size of 100-300 nm, can be stably stored for more than 6 months at room temperature, is suitable for sizing treatment of carbon fiber / PA6 composite materials, and can improve the interfacial bonding performance between the carbon fibers and the PA6 matrix.

Description

Technical Field

[0001] This invention belongs to the field of carbon fiber surface treatment and sizing agent technology, specifically relating to a nonionic epoxy resin modified waterborne polyurethane sizing agent for carbon fiber and its preparation method. Background Technology

[0002] Carbon fiber is a fibrous material with a carbon content of more than 90%. Due to its lightweight, high strength, high modulus and excellent heat resistance and fatigue resistance, it is widely used in aerospace, automobile manufacturing, national defense and military industry and high-end sports equipment. It is an important reinforcing material for advanced composite materials.

[0003] However, the smooth surface and chemical inertness of carbon fibers often lead to insufficient interfacial compatibility with thermoplastic resin matrices such as nylon 6, resulting in limited interfacial load transfer efficiency and hindering the full utilization of the reinforcing effect of carbon fibers. To improve the interfacial bonding between carbon fibers and the resin matrix, sizing is widely used in carbon fiber surface modification. A suitable sizing agent should not only form a uniform and stable coating layer on the carbon fiber surface but also possess good wettability, adhesion, and bundle-forming properties, thereby improving the protective effect of carbon fibers during processing and the interfacial bonding performance between them and the resin matrix.

[0004] Both epoxy and polyurethane sizing agents are currently used for carbon fiber surface treatment. Epoxy sizing agents typically exhibit good interfacial adhesion, but their system flexibility and processing adaptability are relatively limited. Polyurethane sizing agents offer better flexibility, film-forming properties, and fiber protection, but their interfacial reinforcement capabilities still have room for improvement. Furthermore, some existing epoxy-modified polyurethane systems or waterborne polyurethane systems still require catalysts or neutralizing agents during preparation, resulting in longer process flows, greater environmental impact, and potential residues that could affect interfacial properties.

[0005] Therefore, developing an epoxy resin-modified polyurethane sizing agent that does not rely on ionic neutralization emulsification routes and can form a stable aqueous dispersion system under conditions without catalysts, neutralizers, or added emulsifiers has significant application value. Summary of the Invention

[0006] The purpose of this invention is to provide a nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fibers and its preparation method, so as to solve the problems of complex preparation process, insufficient emulsion stability and limited reinforcement effect of carbon fiber / PA6 interface in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber, comprising, by weight, 10-15 parts epoxy resin modified polyurethane and 85-90 parts deionized water. The epoxy-modified polyurethane is prepared by reacting hydrophilic soft-segment polyol, diisocyanate, chain extender and epoxy resin, and its structural formula is shown in Formula 1: Formula 1 In Equation 1, R1 is

[0008] R2 is

[0009]

[0010] R3 is

[0011] Where m = 0.15~2.0.

[0012] Preferably, the epoxy resin modified polyurethane has the structural formula shown in Formulas 2-4: Formula 2 Formula 3 Formula 4.

[0013] This invention also provides a method for preparing a nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fibers, comprising the following steps: Step 1: Under nitrogen protection, stir and heat the polyol, diisocyanate and chain extender to 70 ℃-85 ℃ and react for 2-4 hours to obtain polyurethane prepolymer; Step 2: Add epoxy resin to the polyurethane prepolymer obtained in Step 1, and react under nitrogen protection at 70 ℃-85 ℃ for 2-3 hours to obtain epoxy resin modified polyurethane. Step 3: Add deionized water at a constant speed to the epoxy resin modified polyurethane transfer emulsifier obtained in Step 2 under high-speed stirring to directly self-emulsify and form an aqueous sizing agent, thus obtaining a non-ionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber.

[0014] This invention also provides a nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fibers, comprising, by weight, 10-15 parts epoxy resin modified polyurethane and 85-90 parts deionized water; the epoxy resin modified polyurethane is prepared by reacting hydrophilic soft segment polyol, diisocyanate, chain extender and epoxy resin, and has the structural formula shown in Formula 1: Formula 1, In Equation 1, R1 is ; R2 is ; ; R3 is ; Where m = 0.15~2.0, n = 0~20.

[0015] This invention also provides a method for preparing the above-mentioned nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fibers, comprising the following steps: Step 1: Stir the polyol, diisocyanate and chain extender under nitrogen protection and heat to 60 ℃-90 ℃, react for 2-5 hours to obtain polyurethane prepolymer; Step 2: Add epoxy resin to the polyurethane prepolymer obtained in Step 1, and react under nitrogen protection at 60 ℃-90 ℃ for 2-5 hours to obtain epoxy resin modified polyurethane. Step 3: Add deionized water at a constant speed to the epoxy resin modified polyurethane transfer emulsifier obtained in Step 2 under high-speed stirring to directly self-emulsify and form an aqueous sizing agent, thus obtaining a non-ionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber.

[0016] Preferably, the polyol mentioned in step one is selected from one or more of polyethylene glycol (PEG), polytetrahydrofuran (PTMG), polyethylene glycol monomethyl ether diol (N120), polyether diol (N210), polycaprolactone polyol, polycarbonate diol, polyester polyol, soybean oil-derived polyol, Span 80 silicone-modified polyol, Span 80, and castor oil, with a number average molecular weight of 1000-3000.

[0017] Preferably, the diisocyanate in step one is selected from at least one of isoflurane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, toluene diisocyanate, hexamethylene diisocyanate biuret, 4,4'-methylene bis(phenyl isocyanate), and L-lysine diisocyanate.

[0018] Preferably, the chain extender mentioned in step one is selected from 1,4-butanediol, bisphenol A polyoxyethylene ether, bisphenol fluorene, hydroquinone dihydroxyethyl ether, 2,2-dimethylolpropionic acid, 1,6-hexanediol, neopentyl glycol, diethanolamine, 9,9-bis(3,5-dimethyl-4-hydroxyphenyl)fluorene, phenol red, phenolphthalein, 2,2'-bis[4-(4-aminophenoxyphenyl)]propane, 2,2'-diallyl bisphenol A, magnolol, or dehydrobiseugenol.

[0019] Preferably, the weight ratio of polyol, diisocyanate and chain extender in step one is (240-900):(460-1800):(30-240), and the weight ratio of polyol and epoxy resin is (240-900):(710-2860).

[0020] Preferably, the epoxy resin in step two is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and phenolic epoxy resin; wherein, the bisphenol A type epoxy resin is selected from one or more of E51, E44, E42, E35, E31, E20, E14, E12, E06, and E03; the bisphenol F type epoxy resin can be selected from one or more of bisphenol F diglycidyl ether, liquid bisphenol F type epoxy resin, and low viscosity bisphenol F type epoxy resin; the phenolic epoxy resin can be selected from one or more of phenolic epoxy resin, o-cresol phenolic epoxy resin, bisphenol A phenolic epoxy resin, bisphenol F phenolic epoxy resin, and dicyclopentadiene phenolic epoxy resin.

[0021] Preferably, a solvent is also added in step one, wherein the solvent is selected from one or more of acetone, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, butanone and N-methylpyrrolidone; In step three, one or more of the following can be added: leveling agent, wetting agent, defoamer, lubricant, and film-forming aid.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects: This invention provides a nonionic self-emulsifying epoxy resin-modified waterborne polyurethane sizing agent for carbon fibers and its preparation method. This system introduces hydrophilic soft-segment polyols into the polyurethane backbone to form nonionic hydrophilic segments. The resulting polyurethane, after subsequent modification with commercial epoxy resin, can achieve stable emulsification and form a waterborne sizing agent suitable for carbon fiber surface treatment without relying on ionic hydrophilic groups such as carboxyl or sulfonic acid groups, and without the need for neutralizing agents. Compared to existing self-emulsifying polyurethane epoxy sizing agent technologies that rely on catalysts and neutralizing agents, and anionic waterborne epoxy sizing agent technologies that rely on ionic small-molecule modifiers, this invention has fundamental differences in emulsification mechanism, film-forming substrate, and process route. It can simultaneously achieve better dispersion stability and carbon fiber / PA6 interface reinforcement effects while simplifying the process and reducing auxiliary chemicals. Experimental results show that the sizing agent prepared in this invention can form an aqueous emulsion with small particle size and stable dispersion, which is beneficial to forming a more uniform sizing layer on the carbon fiber surface. In addition, the sizing agent prepared in this invention is suitable for carbon fiber / nylon 6 composite material system, which can improve the interfacial bonding performance between carbon fiber and nylon 6 matrix, and improve the interlaminar shear strength and flexural strength of composite material. Attached Figure Description

[0023] Figure 1 Photographs of the sizing agents prepared in Comparative Examples 1-3 and Examples 1-3; Figure 2 The infrared spectra of the epoxy resin modified polyurethanes obtained in Examples 1-3 are shown below. Figure 3 The particle size distribution diagrams are for the epoxy resin modified polyurethane sizing agents obtained in Examples 1-3.

[0024] Figure 4 This is a schematic diagram of the reaction process for preparing the resin in Example 1; Figure 5 This is a schematic diagram of the reaction process for preparing the resin in Example 2; Figure 6 This is a schematic diagram of the reaction process for preparing the resin in Example 3. Detailed Implementation

[0025] A nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber, comprising, by weight, 10-15 parts epoxy resin modified polyurethane and 85-90 parts deionized water. The epoxy-modified polyurethane is prepared by reacting a hydrophilic soft-segment polyol, diisocyanate, chain extender, and epoxy resin. The hydrophilic soft-segment polyol introduces nonionic hydrophilic segments into the polyurethane molecular chain to impart self-emulsifying ability to the system. The structural formula is shown in Formula 1. Formula 1 In Equation 1, R1 is

[0026] R2 is

[0027]

[0028] R3 is

[0029] Where m = 0.15~2.0.

[0030] Preferably, the epoxy resin modified polyurethane has the structural formula shown in Formulas 2-4: Formula 2 Formula 3 Formula 4 The present invention also provides a method for preparing the above-mentioned sizing agent, comprising the following steps: Step 1: The polyol, diisocyanate, and chain extender are stirred and heated to 70℃-85℃ under nitrogen protection for 2-4 hours to obtain a polyurethane prepolymer. The polyol is preferably selected from polyethylene glycol (PEG), polytetrahydrofuran (PTMG), polyethylene glycol monomethyl ether diol (N120), polyether diol (N210), polycaprolactone polyol, polycarbonate diol, polyester polyol, soybean oil-derived polyol, Span 80 silicone-modified polyol, Span 80, and one or more castor oils, with a preferred number-average molecular weight of 1000-3000. The diisocyanate is preferably selected from isoflurane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, toluene diisocyanate, hexamethylene diisocyanate biuret, and 4,4'-methylene diisocyanate. At least one of bis(phenyl isocyanate) and L-lysine diisocyanate; the chain extender is preferably one of 1,4-butanediol, bisphenol A polyoxyethylene ether, bisphenol fluorene, hydroquinone dihydroxyethyl ether, 2,2-dimethylolpropionic acid, 1,6-hexanediol, neopentyl glycol, diethanolamine, 9,9-bis(3,5-dimethyl-4-hydroxyphenyl)fluorene, phenol red, phenolphthalein, 2,2'-bis[4-(4-aminophenoxyphenyl)]propane, 2,2'-diallyl bisphenol A, magnolol, or dehydrobiseugenol; the weight ratio of the polyol, diisocyanate and chain extender is preferably (240-900):(460-1800):(30-240).

[0031] Step 2: Add epoxy resin to the polyurethane prepolymer obtained in Step 1, and react under nitrogen protection at 70 ℃-85 ℃ for 2-3 hours to obtain epoxy resin modified polyurethane; the epoxy resin is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and phenolic epoxy resin; wherein the bisphenol A type epoxy resin is selected from one or more of E51, E44, E42, E35, E31, E20, E14, E12, E06, and E03; the bisphenol F type epoxy resin can be selected from one or more of bisphenol F diglycidyl ether, liquid bisphenol F type epoxy resin, and low viscosity bisphenol F type epoxy resin, specifically YDF-170, YDF-175, NPEF-170, EPON 862, and EPICLON. One or more of 835; the phenolic epoxy resin may be selected from one or more of phenolic epoxy resin, o-cresol phenolic epoxy resin, bisphenol A phenolic epoxy resin, bisphenol F phenolic epoxy resin and dicyclopentadiene phenolic epoxy resin, specifically one or more of F51, F44, EOCN-1020, EOCN-1025 and ECN-1280, and the preferred weight ratio of the polyol to the epoxy resin is (240-900):(710-2860).

[0032] Step 3: Deionized water is added uniformly to the epoxy resin-modified polyurethane transfer emulsifier obtained in Step 2 under high-speed stirring, directly self-emulsifying to form an aqueous sizing agent, thus obtaining an epoxy resin-modified aqueous polyurethane sizing agent for carbon fiber. The preferred high-speed stirring speed is 1000-1100 r / min, and the preferred stirring time is 1 h.

[0033] According to the present invention, the sizing agent can be diluted to a solid content of 2.0%-5.0% before use, so as to adjust the viscosity and fluidity of the sizing solution, improve the uniformity of carbon fiber surface impregnation and the stability of the sizing process.

[0034] This invention also provides a nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fibers, comprising, by weight, 10-15 parts epoxy resin modified polyurethane and 85-90 parts deionized water; the epoxy resin modified polyurethane is prepared by reacting hydrophilic soft segment polyol, diisocyanate, chain extender and epoxy resin, and has the structural formula shown in Formula 1: Formula 1, In Equation 1, R1 is ; R2 is ; ; R3 is ; Where m = 0.15~2.0, n = 0~20.

[0035] The present invention also provides a method for preparing the above-mentioned nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fibers, comprising the following steps: Step 1: The polyol, diisocyanate, and chain extender are stirred and heated to 60℃-90℃ under nitrogen protection for 2-5 hours to obtain a polyurethane prepolymer. The polyol is preferably selected from polyethylene glycol (PEG), polytetrahydrofuran (PTMG), polyethylene glycol monomethyl ether diol (N120), polyether diol (N210), polycaprolactone polyol, polycarbonate diol, polyester polyol, soybean oil-derived polyol, Span 80 silicone-modified polyol, Span 80, and one or more castor oils, with a preferred number-average molecular weight of 1000-3000. The diisocyanate is preferably selected from isoflurane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, toluene diisocyanate, hexamethylene diisocyanate biuret, and 4,4'-methylene diisocyanate. At least one of bis(phenyl isocyanate) and L-lysine diisocyanate; the chain extender is preferably selected from 1,4-butanediol, bisphenol A polyoxyethylene ether, bisphenol fluorene, hydroquinone dihydroxyethyl ether, 2,2-dimethylolpropionic acid, 1,6-hexanediol, neopentyl glycol, diethanolamine, 9,9-di(3,5-dimethyl-4-hydroxyphenyl)fluorene, phenol red, phenolphthalein, 2,2'-bis[4-(4-aminophenoxyphenyl)]propane, 2,2'-diallyl bisphenol A, magnolol, or dehydrobiseugenol; the weight ratio of the polyol, diisocyanate and chain extender is preferably (240-900):(460-1800):(30-240); According to the present invention, a solvent may be added during the reaction process, preferably one or more of acetone, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, butanone, and N-methylpyrrolidone.

[0036] Step 2: Add epoxy resin to the polyurethane prepolymer obtained in Step 1, and react under nitrogen protection at 60 ℃-90 ℃ for 2-5 hours to obtain epoxy resin modified polyurethane; the epoxy resin is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and phenolic epoxy resin; wherein the bisphenol A type epoxy resin is selected from one or more of E51, E44, E42, E35, E31, E20, E14, E12, E06, and E03; the bisphenol F type epoxy resin can be selected from one or more of bisphenol F diglycidyl ether, liquid bisphenol F type epoxy resin, and low viscosity bisphenol F type epoxy resin, specifically YDF-170, YDF-175, NPEF-170, EPON 862, and EPICLON. One or more of 835; the phenolic epoxy resin may be selected from one or more of phenolic epoxy resin, o-cresol phenolic epoxy resin, bisphenol A phenolic epoxy resin, bisphenol F phenolic epoxy resin and dicyclopentadiene phenolic epoxy resin, specifically one or more of F51, F44, EOCN-1020, EOCN-1025 and ECN-1280, and the preferred weight ratio of the polyol to the epoxy resin is (240-900):(710-2860).

[0037] Step 3: In the epoxy resin modified polyurethane transfer emulsifier obtained in Step 2, deionized water is added at a constant speed under high-speed stirring to directly self-emulsify and form an aqueous sizing agent. The preferred speed of the high-speed stirring is 1000-1100 r / min, and the preferred stirring time is 0.5-1.5 h. Then, one or more of the following are preferred: leveling agent, wetting agent, defoamer, lubricant, and film-forming aid, to obtain a nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber.

[0038] The leveling agent is preferably selected from one or more of polyacrylate leveling agents, modified polyacrylate leveling agents, acrylate copolymer leveling agents, fluorinated acrylate leveling agents, and polyester modified acrylate leveling agents. The amount of leveling agent added is preferably 0.01–2.0 parts by weight, based on 100 parts by weight of epoxy resin modified polyurethane.

[0039] The wetting agent is preferably selected from one or more of phenethylphenol polyoxyethylene ether polyoxypropylene ether, phenethylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, isotridecyl alcohol polyoxyethylene ether, acetylacetonate diol polyoxyethylene ether, alkyl glycoside, and sorbitan fatty acid ester polyoxyethylene ether. The amount of the wetting agent added is preferably 0.05–1.5 parts by weight per 100 parts by weight of epoxy resin modified polyurethane.

[0040] The defoamer is preferably selected from one or more of the following: polydimethylsiloxane defoamer, methyl silicone oil emulsion defoamer, organosilicon emulsion defoamer, polyether-modified polysiloxane defoamer, mineral oil-hydrophobic silica compound defoamer, higher alcohol defoamer, and fatty acid ester defoamer. The amount of defoamer added is preferably 0.01–0.8 parts by weight, based on 100 parts by weight of epoxy resin-modified polyurethane.

[0041] The lubricant is preferably selected from one or more of polyethylene wax emulsion, oxidized polyethylene wax emulsion, polypropylene wax emulsion, paraffin wax emulsion, microcrystalline wax emulsion, lignite wax emulsion, oleamide, erucamide, stearamide, and ethylene bis-stearamide; the amount of lubricant added is preferably 0.1–3.0 parts by weight based on 100 parts by weight of epoxy resin modified polyurethane.

[0042] The film-forming aid is preferably selected from one or more of dodecyl alcohol ester, diethylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol butyl ether, propylene glycol phenyl ether, benzyl alcohol, ethylene glycol butyl ether, and environmentally friendly ester film-forming aids. The amount of the film-forming aid added is preferably 0.1–3.0 parts by weight, based on 100 parts by weight of epoxy resin modified polyurethane.

[0043] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described below with reference to embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Experimental conditions not specifically described can be those conventional in the art, and the raw materials and equipment used, unless otherwise specified, can be obtained through conventional commercial channels.

[0044] Comparative Example 1 Unsized carbon fiber and nylon 6 (PA6) composites were prepared using a hot-pressing process. Specifically, eight layers of PA6 film (120 mm × 100 mm × 0.3 mm) and seven layers of carbon fiber fabric (120 mm × 100 mm) were alternately stacked and hot-pressed at 250 °C and 5 MPa for 30 minutes to obtain the CF / PA6 composite. The resulting composite was cut into test strips, and its interlaminar shear strength and flexural strength were tested. The results are shown in Table 1. Photos of the actual product are shown below. Figure 1 As shown.

[0045] Comparative Example 2 Comparative Example 2 provides a method for preparing a nonionic waterborne polyurethane sizing agent, comprising the following steps: (1) 900 parts of polyethylene glycol monomethyl ether type diol (N120), 240 parts of 1,4-butanediol and 1800 parts of toluene diisocyanate were mixed evenly under nitrogen protection and heated to 70 °C for 2 hours to obtain polyurethane.

[0046] (2) Take 10 parts of the polyurethane obtained in step (1) and place them in an emulsifier. Add 90 parts of deionized water at a constant speed under high-speed stirring at 1000 rpm / min. After mixing evenly, stir for 1 h to obtain a non-ionic waterborne polyurethane sizing agent for carbon fibers. See the actual product photo below. Figure 1 As shown.

[0047] Carbon fiber fabric was impregnated with the sizing agent prepared in Comparative Example 2 for sizing treatment. After sizing, it was combined with PA6 using hot pressing technology to prepare composite materials, and test strips for interlaminar shear strength and flexural strength were cut to obtain the test results. The test results are shown in Table 1.

[0048] Comparative Example 3 (1) Heat 80 parts of epoxy resin E51 and 20 parts of epoxy resin E20 to 50-60 ℃ to reduce viscosity, and slowly add deionized water under high-speed shearing to make a white or milky white epoxy emulsion.

[0049] (2) The epoxy resin emulsion was slowly added dropwise to the WPU emulsion prepared in Comparative Example 2 under high-speed shear conditions, and stirred for 30 min to obtain a uniformly mixed epoxy / PU physical blend sizing agent. Actual product photos are shown below. Figure 1 As shown.

[0050] Carbon fiber fabric was impregnated with the sizing agent prepared in Comparative Example 3 for sizing treatment. After sizing, it was combined with PA6 using hot pressing technology to prepare composite materials, and test strips for interlaminar shear strength and flexural strength were cut to obtain the test results. The test results are shown in Table 2.

[0051] Example 1 (1) 900 parts of polyethylene glycol monomethyl ether type diol (N120), 240 parts of 1,4-butanediol and 1800 parts of toluene diisocyanate were mixed evenly under nitrogen protection and heated to 70 °C for 2 hours to obtain polyurethane prepolymer.

[0052] (2) Add 2400 parts of epoxy resin E51 and 460 parts of epoxy resin E20 to the prepolymer obtained in step (1), and react at 70°C for 2 hours under nitrogen protection to obtain epoxy resin modified polyurethane. A schematic diagram of the reaction process is shown below. Figure 4 As shown.

[0053] (3) Take 10 parts of the epoxy resin modified polyurethane obtained in step (2) and place them in an emulsifier. Under high-speed stirring at 1000 rpm / min, add 90 parts of deionized water at a uniform rate. After mixing evenly, stir for 1 hour to allow it to self-emulsify directly, thus obtaining the epoxy resin modified waterborne polyurethane sizing agent. Actual product photos are shown below. Figure 1 As shown.

[0054] Carbon fiber fabric was impregnated with the sizing agent prepared in Example 1 for sizing treatment. After sizing, it was combined with PA6 using hot pressing technology to prepare composite materials, and test strips for interlaminar shear strength and flexural strength were cut. The test results are shown in Table 2.

[0055] Example 2 (1) Mix 450 parts of polyether diol (N210), 120 parts of bisphenol A polyoxyethylene ether and 900 parts of isoflurane diisocyanate under nitrogen protection, and heat to 70 °C for 2 h to obtain polyurethane prepolymer.

[0056] (2) Add 1200 parts of epoxy resin E51 and 230 parts of epoxy resin E20 to the prepolymer obtained in step (1), and react at 70°C for 2 hours under nitrogen protection to generate epoxy resin modified polyurethane. A schematic diagram of the reaction process is shown below. Figure 5 As shown.

[0057] (3) Transfer 15 parts of epoxy resin-modified polyurethane obtained in step (2) to an emulsifier, and uniformly add 85 parts of deionized water under high-speed stirring at 1000 rpm / min. Mix evenly and stir for 1 hour to allow direct self-emulsification, thus obtaining epoxy resin-modified waterborne polyurethane sizing agent. Actual product photos are shown below. Figure 1 As shown. Subsequently, the sizing and composite material preparation were completed in the same manner as in Example 1.

[0058] Example 3 (1) Mix 240 parts of N120, 30 parts of 1,4-butanediol and 460 parts of isoflurane diisocyanate under nitrogen protection, and heat to 70 °C for 2 h to obtain polyurethane prepolymer.

[0059] (2) Add 600 parts of epoxy resin E51 and 110 parts of epoxy resin E20 to the prepolymer from step (1), and react at 70°C for 2 hours under nitrogen protection to obtain epoxy resin modified polyurethane. A schematic diagram of the reaction process is shown below. Figure 6 As shown.

[0060] (3) Place 15 parts of the epoxy resin-modified polyurethane obtained in step (2) into an emulsifier, and add 85 parts of deionized water at a high speed of 1000 rpm / min. After mixing evenly, stir for 1 hour to allow it to self-emulsify directly, thus obtaining an epoxy resin-modified waterborne polyurethane sizing agent. Actual product photos are shown below. Figure 1 As shown. Subsequently, the sizing and composite material preparation were completed in the same manner as in Example 1.

[0061] Example 4 (1) 240 parts of polytetrahydrofuran, 30 parts of 2,2-dimethylolpropionic acid, 460 parts of hexamethylene diisocyanate biuret and 1000 parts of acetone were mixed evenly under nitrogen protection and heated to 60 °C for 2 h to obtain polyurethane prepolymer.

[0062] (2) Add 500 parts of bisphenol F diglycidyl ether YDF-170 and 210 parts of epoxy resin E44 to the prepolymer of step (1), heat to 60 °C and react for 2 h under nitrogen protection, and obtain epoxy resin modified polyurethane after removing acetone.

[0063] (3) Place 20 parts of the epoxy resin modified polyurethane obtained in step (2) in an emulsifier, add 80 parts of deionized water at a high speed of 1100 rpm / min, mix evenly and stir for 1 h to allow it to self-emulsify directly. Add 0.30 parts of phenylethylphenol polyoxyethylene ether and 0.30 parts of dodecyl alcohol ester to 100 parts by weight of epoxy resin modified polyurethane, mix evenly to obtain epoxy resin modified waterborne polyurethane sizing agent; then complete the sizing and composite material preparation in the same manner as in Example 1.

[0064] Example 5 (1) 280 parts of soybean oil-derived polyol, 30 parts of 9,9-bis(3,5-dimethyl-4-hydroxyphenyl)fluorene, 460 parts of toluene diisocyanate and 800 parts of N,N-dimethylformamide were mixed evenly under nitrogen protection and heated to 80 °C for 4 h to obtain polyurethane prepolymer.

[0065] (2) Add 460 parts of phenolic epoxy resin F51 and 250 parts of epoxy resin E12 to the prepolymer of step (1), and heat to 60 °C for 2 h under nitrogen protection to remove N,N dimethylformamide and obtain epoxy resin modified polyurethane.

[0066] (3) Place 20 parts of the epoxy resin modified polyurethane obtained in step (2) in an emulsifier, and add 80 parts of deionized water at a high speed of 1100 rpm / min. After mixing evenly, stir for 1.5 h to allow it to self-emulsify directly. Based on 100 parts by weight of epoxy resin modified polyurethane, add 0.3 parts of polyacrylate leveling agent, 0.7 parts of isomeric tridecyl alcohol polyoxyethylene ether, and 0.3 parts of methyl silicone oil emulsion defoamer to obtain epoxy resin modified waterborne polyurethane sizing agent. Then, complete the sizing and composite material preparation in the same manner as in Example 1.

[0067] Example 6 (1) 240 parts of Span 80 silicone-modified polyol, 30 parts of phenolphthalein and 460 parts of 4,4'-methylenebis(phenyl isocyanate) were mixed evenly under nitrogen protection and heated to 85 °C for 4.5 h to obtain polyurethane prepolymer.

[0068] (2) Add 300 parts of epoxy resin E51 and 500 parts of epoxy resin E12 to the prepolymer of step (1), and heat to 85 °C for 4 h under nitrogen protection to obtain epoxy resin modified polyurethane.

[0069] (3) Place 20 parts of the epoxy resin modified polyurethane obtained in step (2) into an emulsifier, and add 80 parts of deionized water at a high speed of 1100 rpm / min. After mixing evenly, stir for 1 h to allow it to self-emulsify directly, and obtain the epoxy resin modified waterborne polyurethane sizing agent. Then, complete the sizing and composite material preparation in the same manner as in Example 1.

[0070] Example 7 (1) 400 parts of polyethylene glycol, 60 parts of dehydrobiseugenol, 460 parts of L-lysine diisocyanate and N-methylpyrrolidone were mixed evenly under nitrogen protection and heated to 90 °C for 4.5 h to obtain polyurethane prepolymer.

[0071] (2) Add 1000 parts of epoxy resin E44 and 800 parts of phenolic epoxy resin F44 to the prepolymer of step (1), and heat to 90 °C for 4 h under nitrogen protection to obtain epoxy resin modified polyurethane.

[0072] (3) Place 15 parts of the epoxy resin modified polyurethane obtained in step (2) in an emulsifier, and add 85 parts of deionized water at a high speed of 1100 rpm / min. After mixing evenly, stir for 1 h to allow it to self-emulsify directly. Based on 100 parts by weight of epoxy resin modified polyurethane, add 0.80 parts of phenethylphenol polyoxyethylene ether, 0.20 parts of polyether modified polysiloxane defoamer, and 1.00 parts of polypropylene wax emulsion. After mixing evenly, obtain the epoxy resin modified waterborne polyurethane sizing agent. Then, complete the sizing and composite material preparation in the same manner as in Example 1.

[0073] Example 8 (1) Mix 240 parts of polyethylene glycol, 30 parts of honokiol and 460 parts of hexamethylene diisocyanate under nitrogen protection, and heat to 85 °C for 4.5 h to obtain polyurethane prepolymer.

[0074] (2) Add 500 parts of epoxy resin E44 and 400 parts of epoxy resin E12 to the prepolymer of step (1), and heat to 85 °C for 4 h under nitrogen protection to obtain epoxy resin modified polyurethane.

[0075] (3) Place 15 parts of the epoxy resin-modified polyurethane obtained in step (2) in an emulsifier, and add 85 parts of deionized water at a high speed of 1000 rpm / min. After mixing evenly, stir for 1 h to allow it to self-emulsify directly. Add 1.00 parts of oxidized polyethylene wax emulsion and 0.50 parts of dipropylene glycol butyl ether based on 100 parts by weight of epoxy resin-modified polyurethane to obtain epoxy resin-modified waterborne polyurethane sizing agent. Then, complete the sizing and composite material preparation in the same manner as in Example 1.

[0076] Example 9 (1) Mix 900 parts of polyethylene glycol, 240 parts of phenol red, 1800 parts of hexamethylene diisocyanate and methyl ethyl ketone under nitrogen protection, and heat to 80 °C for 2 hours to obtain polyurethane prepolymer.

[0077] (2) Add 2000 parts of liquid bisphenol F type epoxy resin NPEF-170 and 400 parts of o-cresol phenolic type epoxy resin EOCN-1020 to the prepolymer obtained in step (1), and heat to 80 °C for 2 hours under nitrogen protection to obtain epoxy resin modified polyurethane.

[0078] (3) Take 25 parts of the epoxy resin modified polyurethane obtained in step (2) and place them in an emulsifier. Add 75 parts of deionized water at a high speed of 1100 rpm / min. Mix evenly and stir for 1.5 h to allow it to self-emulsify directly. Add 0.50 parts of fluorinated modified acrylate leveling agent and 0.80 parts of acetylation diol polyoxyethylene ether based on 100 parts by weight of epoxy resin modified polyurethane to obtain epoxy resin modified waterborne polyurethane sizing agent.

[0079] The aramid fiber fabric was sized by immersing it in the sizing agent prepared in Example 9. After sizing, it was combined with PA6 using hot pressing technology to prepare a composite material, and test strips for interlaminar shear strength and flexural strength were cut. The test results are shown in Table 1.

[0080] Example 10 (1) Mix 800 parts of polytetrahydrofuran, 200 parts of 2,2-dimethylolpropionic acid, 1800 parts of toluene diisocyanate and N,N-dimethylacetamide evenly under nitrogen protection, and heat to 90 °C for 2 hours to obtain polyurethane prepolymer.

[0081] (2) Add 2000 parts of low viscosity bisphenol F type epoxy resin EPON 862 and 600 parts of epoxy resin E44 to the prepolymer obtained in step (1), and heat to 90 °C for 2 hours under nitrogen protection to obtain epoxy resin modified polyurethane.

[0082] (3) Take 25 parts of the epoxy resin modified polyurethane obtained in step (2) and place them in an emulsifier. Add 75 parts of deionized water at a high speed of 1100 rpm / min. After mixing evenly, stir for 1.5 h to allow it to self-emulsify directly and obtain epoxy resin modified waterborne polyurethane sizing agent.

[0083] The glass fiber fabric was impregnated with the sizing agent prepared in Example 10 for sizing treatment. After sizing, it was combined with PA6 using hot pressing technology to prepare a composite material, and test strips for interlaminar shear strength and flexural strength were cut to obtain the test results. The test results are shown in Table 1.

[0084] Example 11 (1) Mix 800 parts of polycaprolactone polyol, 200 parts of 1,6-hexanediol, 1800 parts of toluene diisocyanate and N,N-dimethylacetamide evenly under nitrogen protection, and heat to 80 °C for 2 hours to obtain polyurethane prepolymer.

[0085] (2) Add 2000 parts of epoxy resin E20 and 600 parts of phenolic epoxy resin F51 to the prepolymer obtained in step (1), and heat to 80 °C for 2 hours under nitrogen protection to obtain epoxy resin modified polyurethane.

[0086] (3) Take 25 parts of the epoxy resin modified polyurethane obtained in step (2) and place them in an emulsifier. Add 75 parts of deionized water at a high speed of 1100 rpm / min. After mixing evenly, stir for 1.5 h to allow it to self-emulsify directly and obtain epoxy resin modified waterborne polyurethane sizing agent.

[0087] The carbon fiber fabric was impregnated with the sizing agent prepared in Example 11 for sizing treatment. After sizing, it was combined with PA6 using hot pressing technology to prepare a composite material, and test strips for interlaminar shear strength and flexural strength were cut to obtain the test results. The test results are shown in Table 1.

[0088] Example 12 (1) 900 parts of polycarbonate diol, 240 parts of 2,2'-diallyl bisphenol A, 1800 parts of toluene diisocyanate and N,N-dimethylacetamide were mixed evenly under nitrogen protection and heated to 90 °C for 2 hours to obtain polyurethane prepolymer.

[0089] (2) Add 2000 parts of epoxy resin E12 and 600 parts of o-cresol phenolic epoxy resin ECN-1280 to the prepolymer obtained in step (1), and heat to 90 °C for 2 hours under nitrogen protection to obtain epoxy resin modified polyurethane.

[0090] (3) Take 30 parts of the epoxy resin modified polyurethane obtained in step (2) and place them in an emulsifier. Add 70 parts of deionized water at a high speed of 1100 rpm / min. Mix evenly and stir for 1.5 h to allow it to self-emulsify directly, thus obtaining epoxy resin modified waterborne polyurethane sizing agent.

[0091] The carbon fiber fabric was impregnated with the sizing agent prepared in Example 12 for sizing treatment. After sizing, it was combined with PA6 using hot pressing technology to prepare a composite material, and test strips for interlaminar shear strength and flexural strength were cut to obtain the test results. The test results are shown in Table 1.

[0092] Example 13 (1) 900 parts of polyester diol, 240 parts of bisphenol A polyoxyethylene ether, 1800 parts of toluene diisocyanate and N,N-dimethylformamide were mixed evenly under nitrogen protection and heated to 90 °C for 2 hours to obtain polyurethane prepolymer.

[0093] (2) Add 2000 parts of epoxy resin E12 and 600 parts of o-cresol phenolic epoxy resin EOCN-1025 to the prepolymer obtained in step (1), and heat to 90 °C for 2 hours under nitrogen protection to obtain epoxy resin modified polyurethane.

[0094] (3) Take 30 parts of the epoxy resin modified polyurethane obtained in step (2) and place them in an emulsifier. Add 70 parts of deionized water at a high speed of 1100 rpm / min. Mix evenly and stir for 1.5 h to allow it to self-emulsify directly, thus obtaining epoxy resin modified waterborne polyurethane sizing agent.

[0095] The carbon fiber fabric was impregnated with the sizing agent prepared in Example 13 for sizing treatment. After sizing, it was combined with PA6 using hot pressing technology to prepare a composite material, and test strips for interlaminar shear strength and flexural strength were cut to obtain the test results. The test results are shown in Table 1.

[0096] Table 1 Mechanical properties of the composite materials obtained in Comparative Examples 1-3 and Examples 1-13

[0097] As shown in Table 1, compared with Comparative Example 1 which was not sizing, the interlaminar shear strength and flexural strength of the carbon fiber / PA6 composite material treated with the sizing agent of the present invention are improved. This indicates that the epoxy resin modified waterborne polyurethane sizing agent provided by the present invention can improve the interfacial bonding performance between carbon fiber and PA6 matrix, thereby improving the mechanical properties of the composite material.

[0098] The chemical structures of the samples obtained in Examples 1-3 were analyzed using Fourier transform infrared spectroscopy (FT-IR). Figure 2As shown, the spectrum is plotted with the carbonyl group (C=O) at 1655 cm⁻¹. -1 Normalization was performed using the characteristic absorption peak at 3324 cm⁻¹ as a reference. The characteristic double peak of amino groups appears at 3324 cm⁻¹. -1 and 1531 cm -1 Location. At 2250-2300 cm. -1 No obvious isocyanate (-NCO) characteristic peaks were observed within the range, indicating that the reactive group was completely consumed during the process. Furthermore, at 1652 cm⁻¹... -1 Another prominent absorption peak can be attributed to the C=O stretching vibration in the urea structure, further demonstrating the reaction between the OH and -NCO groups.

[0099] Thermogravimetric analysis (TGA) was used to test the thermal stability of the resins obtained in Examples 1-3. The test conditions were: under a nitrogen atmosphere, the temperature was increased from room temperature to 600 °C at a rate of 10 °C / min, and the thermal decomposition temperature was characterized by the temperature corresponding to a 5% weight loss. The test results are shown in Table 2.

[0100] Table 2 Thermal stability of epoxy-modified polyurethane resins in Examples 1-3 of the present invention

[0101] The particle size distribution of the sizing agents obtained in Examples 1-3 was determined by a particle size analyzer as follows: Figure 3 As shown.

[0102] Particle size test results show that the average particle size of the sizing agents obtained in Examples 1-3 is in the range of 100-300 nm, and the samples can be stably stored at room temperature for more than 6 months, indicating that the sizing agent has good dispersion stability.

[0103] In summary, the epoxy resin-modified polyurethane obtained by this invention possesses nonionic self-emulsifying capabilities, enabling the formation of a stable water-based sizing agent without the need for neutralizers or added emulsifiers. This sizing agent exhibits stable dispersion and good film-forming properties, improving the interfacial bonding between carbon fiber and PA6 and enhancing the mechanical properties of the composite material.

[0104] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered within the scope of protection of the present invention.

Claims

1. A nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber, characterized in that, The product comprises, by weight, 10-15 parts epoxy resin modified polyurethane and 85-90 parts deionized water; the epoxy resin modified polyurethane is prepared by reacting hydrophilic soft segment polyol, diisocyanate, chain extender and epoxy resin, and has the structural formula shown in Formula 1: Formula 1, In Equation 1, R1 is ; R2 is ; ； R3 is ; Where m = 0.15~2.

0.

2. A nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber, characterized in that, The product comprises, by weight, 10-15 parts epoxy resin modified polyurethane and 85-90 parts deionized water; the epoxy resin modified polyurethane is prepared by reacting hydrophilic soft segment polyol, diisocyanate, chain extender and epoxy resin, and has the structural formula shown in Formula 1: Formula 1, In Equation 1, R1 is ； R2 is ； ； R3 is ; Where m = 0.15~2.0, n = 0~20.

3. The method for preparing a nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber according to claim 1, characterized in that, Includes the following steps: Step 1: Under nitrogen protection, stir and heat the polyol, diisocyanate and chain extender to 70 ℃-85 ℃ and react for 2-4 hours to obtain polyurethane prepolymer; Step 2: Add epoxy resin to the polyurethane prepolymer obtained in Step 1, and react under nitrogen protection at 70 ℃-85 ℃ for 2-3 hours to obtain epoxy resin modified polyurethane. Step 3: Add deionized water at a constant speed to the epoxy resin modified polyurethane transfer emulsifier obtained in Step 2 under high-speed stirring to directly self-emulsify and form an aqueous sizing agent, thus obtaining a non-ionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber.

4. The preparation method of a nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber according to claim 2, characterized in that, Includes the following steps: Step 1: Stir the polyol, diisocyanate and chain extender under nitrogen protection and heat to 60 ℃-90 ℃, react for 2-5 hours to obtain polyurethane prepolymer; Step 2: Add epoxy resin to the polyurethane prepolymer obtained in Step 1, and react under nitrogen protection at 60 ℃-90 ℃ for 2-5 hours to obtain epoxy resin modified polyurethane. Step 3: Add deionized water at a constant speed to the epoxy resin modified polyurethane transfer emulsifier obtained in Step 2 under high-speed stirring to directly self-emulsify and form an aqueous sizing agent, thus obtaining a non-ionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber.

5. A method for preparing a nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber according to claim 3 or 4, characterized in that, The polyol mentioned in step one is selected from one or more of polyethylene glycol, polytetrahydrofuran, polyethylene glycol monomethyl ether diol, polyether diol, polycaprolactone polyol, polycarbonate diol, polyester polyol, soybean oil-derived polyol, Span 80 silicon-modified polyol, Span 80 and castor oil, with a number average molecular weight of 1000-3000.

6. A method for preparing a nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber according to claim 3 or 4, characterized in that, The diisocyanate mentioned in step one is selected from at least one of isoflurane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, toluene diisocyanate, hexamethylene diisocyanate biuret, 4,4'-methylene bis(phenyl isocyanate), and L-lysine diisocyanate.

7. A method for preparing a nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber according to claim 3 or 4, characterized in that, The chain extender mentioned in step one is selected from 1,4-butanediol, bisphenol A polyoxyethylene ether, bisphenol fluorene, hydroquinone dihydroxyethyl ether, 2,2-dimethylolpropionic acid, 1,6-hexanediol, neopentyl glycol, diethanolamine, 9,9-bis(3,5-dimethyl-4-hydroxyphenyl)fluorene, phenol red, phenolphthalein, 2,2'-bis[4-(4-aminophenoxyphenyl)]propane, 2,2'-diallyl bisphenol A, magnolol, or dehydrobiseugenol.

8. A method for preparing a nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber according to claim 3 or 4, characterized in that, The weight ratio of the polyol, diisocyanate and chain extender mentioned in step one is (240-900):(460-1800):(30-240). The weight ratio of the polyol to the epoxy resin is (240-900):(710-2860).

9. A method for preparing a nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber according to claim 3 or 4, characterized in that, The epoxy resin mentioned in step two is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and phenolic epoxy resin; wherein, the bisphenol A type epoxy resin is selected from one or more of E51, E44, E42, E35, E31, E20, E14, E12, E06, and E03; the bisphenol F type epoxy resin is selected from one or more of bisphenol F diglycidyl ether type epoxy resin, liquid bisphenol F type epoxy resin, and low viscosity bisphenol F type epoxy resin; the phenolic epoxy resin is selected from one or more of phenolic epoxy resin, o-cresol phenolic epoxy resin, bisphenol A phenolic epoxy resin, bisphenol F phenolic epoxy resin, and dicyclopentadiene phenolic epoxy resin.

10. The method for preparing a nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fiber according to claim 4, characterized in that, In step one, a solvent is also added, which is selected from one or more of acetone, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, butanone and N-methylpyrrolidone; In step three, one or more of the following can be added: leveling agent, wetting agent, defoamer, lubricant, and film-forming aid.

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