A nonionic epoxy resin modified waterborne polyurethane sizing agent for carbon fiber and its preparation method.
By introducing nonionic self-emulsifying epoxy resin to modify waterborne polyurethane in carbon fiber surface treatment agents, the problems of complex processes and high environmental burden in existing technologies have been solved, the interfacial bonding performance between carbon fiber and nylon 6 matrix has been improved, and the mechanical properties of composite materials have been enhanced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHANGCHUN UNIV OF TECH
- Filing Date
- 2026-04-10
- Publication Date
- 2026-06-30
AI Technical Summary
Existing carbon fiber surface treatment agents suffer from complex processes, heavy environmental impact, and limited interfacial reinforcement effects, especially when combined with nylon 6 matrix, where interfacial compatibility is insufficient.
A waterborne polyurethane sizing agent modified with nonionic self-emulsifying epoxy resin is used. By introducing hydrophilic soft segment polyols into the polyurethane main chain, nonionic hydrophilic segments are formed. These segments are directly mixed with deionized water to form a stable emulsion. The preparation process does not rely on organic solvents, catalysts, or neutralizing agents, and a uniform sizing layer is formed directly on the carbon fiber surface.
The preparation process was simplified, the use of chemicals was reduced, the interfacial bonding performance between carbon fiber and nylon 6 matrix was improved, and the interlaminar shear strength and flexural strength of the composite material were enhanced.
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Figure CN122304194A_ABST
Abstract
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 the use of organic solvents, 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 organic solvents, 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 insufficient green preparation, complex process 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] Preferably, the polyol mentioned in step one is selected from one or two of polyethylene glycol (PEG), polytetrahydrofuran (PTMG), polyethylene glycol monomethyl ether diol (N120), and polyether diol (N210), with a number average molecular weight of 1000-3000.
[0015] Preferably, the diisocyanate in step one is selected from at least one of isoflurane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate and toluene diisocyanate.
[0016] Preferably, the chain extender mentioned in step one is selected from 1,4-butanediol, bisphenol A polyoxyethylene ether, or bisphenol fluorene.
[0017] Preferably, the weight ratio of the polyol, diisocyanate and chain extender in step one is (240-900):(460-1800):(30-240).
[0018] Preferably, the epoxy resin mentioned in step two is selected from one or two of E51, E44, E20 and E12.
[0019] Preferably, the weight ratio of the polyol to the epoxy resin is (240-900):(710-2860).
[0020] Preferably, the high-speed stirring speed in step three is 1000-1100 r / min, and the stirring time is 1 h.
[0021] 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, achieves stable emulsification and forms a waterborne sizing agent suitable for carbon fiber surface treatment without relying on ionic hydrophilic groups such as carboxyl or sulfonic acid groups, neutralizing agents, external emulsifiers, catalysts, or organic solvents. Compared to existing self-emulsifying polyurethane epoxy sizing agent technologies that rely on solvents, 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 entity, and process route. It can simultaneously achieve better dispersion stability and carbon fiber / PA6 interface reinforcement effect 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
[0022] 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.
[0023] 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
[0024] 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
[0025] R2 is
[0026]
[0027] R3 is
[0028] Where m = 0.15~2.0.
[0029] 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: Under nitrogen protection, stir and heat the polyol, diisocyanate, and chain extender to 70 ℃-85 ℃ and react for 2-4 hours to obtain a polyurethane prepolymer. The polyol is preferably one or two of polyethylene glycol (PEG), polytetrahydrofuran (PTMG), polyethylene glycol monomethyl ether diol (N120), and polyether diol (N210), with a number average molecular weight preferably of 1000-3000. The diisocyanate is preferably at least one of isoflurane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and toluene diisocyanate. The chain extender is preferably one of 1,4-butanediol, bisphenol A polyoxyethylene ether, and bisphenol fluorene. The weight ratio of the polyol, diisocyanate, and chain extender is preferably (240-900):(460-1800):(30-240).
[0030] 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 preferably one or two of E51, E44, E20 and E12, and the weight ratio of the polyol to the epoxy resin is preferably (240-900):(710-2860).
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] Comparative Example 2 Comparative Example 2 provides a method for preparing a nonionic waterborne polyurethane sizing agent, comprising the following steps: (1) Mix 900 parts of N120, 240 parts of 1,4-butanediol and 1800 parts of toluene diisocyanate evenly under nitrogen protection, and heat to 70 °C for 2 hours to obtain polyurethane.
[0036] (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.
[0037] 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.
[0038] 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.
[0039] (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.
[0040] 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.
[0041] Example 1 (1) Mix 900 parts of N120, 240 parts of 1,4-butanediol and 1800 parts of toluene diisocyanate evenly under nitrogen protection, and heat to 70 °C for 2 hours to obtain polyurethane prepolymer.
[0042] (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.
[0043] (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.
[0044] 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.
[0045] Example 2 (1) Mix 450 parts of 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.
[0046] (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.
[0047] (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.
[0048] 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.
[0049] (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.
[0050] (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.
[0051] Table 1 Mechanical properties of the composite materials obtained in Comparative Examples 1-3 and Examples 1-3
[0052] 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.
[0053] The chemical structures of the samples obtained in Examples 1-3 were analyzed using Fourier transform infrared spectroscopy (FT-IR). Figure 2 As 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. -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.
[0054] 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.
[0055] Table 2 Thermal stability of epoxy-modified polyurethane resins in Examples 1-3 of the present invention
[0056] 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.
[0057] 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.
[0058] In summary, the sizing agent prepared by this invention has good dispersion stability, sizing applicability and interface enhancement effect, and its preparation process does not rely on organic solvents, catalysts and neutralizing agents, thus showing good application prospects.
[0059] 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 fibers, characterized by, By weight parts, including epoxy resin modified polyurethane 10-15 parts and deionized water 85-90 parts; the epoxy resin modified polyurethane is prepared by hydrophilic soft segment polyol, diisocyanate, chain extender and epoxy resin, the structural formula is shown as formula 1: Formula 1, In Formula 1, R1is ; R2 is ； ； R3 is ; Wherein, m = 0.15-2.
0.
2. The nonionic self-emulsifying epoxy resin modified waterborne polyurethane sizing agent for carbon fibers according to claim 1, characterized by, The structural formula of the epoxy resin modified polyurethane is shown as formula 2-4: Formula 2 Formula 3 Formula 4.
3. The method for preparing the nonionic self-emulsifying epoxy resin-modified waterborne polyurethane sizing agent for carbon fiber according to claim 1, characterized in that, Including the following steps: Step one: polyol, diisocyanate and chain extender are stirred under nitrogen protection, and the temperature is raised to 70-85 ℃, and the reaction is carried out for 2-4 hours to obtain polyurethane prepolymer; Step two: epoxy resin is added to the polyurethane prepolymer obtained in step one, and the reaction is carried out at 70-85 ℃ under nitrogen protection for 2-3 hours to obtain epoxy resin modified polyurethane; Step three: the epoxy resin modified polyurethane obtained in step two is transferred to the emulsifier, and deionized water is added at a uniform speed under high speed stirring to form a water-based sizing agent by direct self-emulsification, and a non-ionic self-emulsifying epoxy resin modified water-based polyurethane sizing agent for carbon fiber is prepared.
4. The method for preparing the nonionic self-emulsifying epoxy resin-modified waterborne polyurethane sizing agent for carbon fiber according to claim 3, characterized in that, The polyol in step one is selected from one or two of polyethylene glycol, polytetrahydrofuran, polyethylene glycol monomethyl ether type diol and polyether diol, and the number average molecular weight is 1000-3000.
5. The method for preparing the nonionic self-emulsifying epoxy resin-modified waterborne polyurethane sizing agent for carbon fiber according to claim 3, characterized in that, The diisocyanate in step one is selected from at least one of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexyl methane-4,4'-diisocyanate and toluene diisocyanate.
6. The method for preparing the nonionic self-emulsifying epoxy resin-modified waterborne polyurethane sizing agent for carbon fiber according to claim 3, characterized in that, The chain extender in step one is selected from one of 1,4-butanediol, bisphenol A polyoxyethylene ether or bisphenol fluorene.
7. The method for preparing the nonionic self-emulsifying epoxy resin-modified waterborne polyurethane sizing agent for carbon fiber according to claim 3, characterized in that, The weight ratio of polyol, diisocyanate and chain extender in step one is (240-900):(460-1800):(30-240).
8. The method for preparing the nonionic self-emulsifying epoxy resin-modified waterborne polyurethane sizing agent for carbon fiber according to claim 3, characterized in that, The epoxy resin in step two is selected from one or two of E51, E44, E20 and E12.
9. The method for preparing the nonionic self-emulsifying epoxy resin-modified waterborne polyurethane sizing agent for carbon fiber according to claim 3, characterized in that, The weight ratio of polyol and epoxy resin is (240-900):(710-2860).
10. The method for preparing the nonionic self-emulsifying epoxy resin-modified waterborne polyurethane sizing agent for carbon fiber according to claim 3, characterized in that, The speed of high speed stirring in step three is 1000-1100 r / min, and the stirring time is 1 h.