Toughening wear-resistant sizing agent for high-brittleness carbon fibers and preparation method of toughening wear-resistant sizing agent

Abstract

The invention discloses a toughening wear-resistant sizing agent for high-brittleness carbon fibers and a preparation method of the toughening wear-resistant sizing agent, and belongs to the technical field of preparation of carbon fiber sizing agents. The preparation method comprises the following steps: mixing isocyanate, polyalcohol, glycidol and the like for reaction to prepare a toughened wear-resistant resin, uniformly stirring and mixing the resin and deionized water to form a water-based sizing agent emulsion, and finally coating the sizing agent on the surface of the carbon fiber through carbon fiber sizing equipment to prepare the carbon fiber sizing agent. The toughening wear-resistant sizing agent for the high-brittleness carbon fibers is prepared. The introduction of a carbamate functional group generated by the reaction of isocyanate and polyol enables the material to have excellent toughness and wear resistance, and the introduction of an epoxy functional group endows the sizing agent and an epoxy resin matrix with a good bonding interface, so that the toughening wear-resistant sizing agent for the high-brittleness carbon fiber is prepared. The problems that existing high-brittleness carbon fibers are large in broken filament amount, not good enough in abrasion resistance, prone to being broken and the like are solved.

Description

Technical Field

[0001] This invention belongs to the field of carbon fiber sizing agent preparation technology, specifically relating to a toughening and wear-resistant sizing agent for high-brittle carbon fibers and its preparation method. Background Technology

[0002] High-modulus carbon fiber specifically refers to carbon fiber varieties with an elastic modulus exceeding 350 GPa. Its outstanding stiffness makes it a core choice for achieving lightweight structures and high-precision load-bearing capacity, and it is a key material used in satellite main frames, spacecraft rocket bodies, and the fuselage and wing load-bearing structures of large passenger aircraft. Its preparation requires high-temperature carbonization (2000-3000℃) and graphitization treatment, during which carbon atoms form a highly ordered six-membered ring layered structure (graphite-like structure). Although this structure endows the material with extremely high elastic modulus, the interlayer bonding force relies solely on weak van der Waals forces, making the interlayers highly susceptible to peeling and fracture under lateral loads or shear forces, exhibiting typical brittle fracture characteristics. The weak interlayer bonding force also makes it easy for individual filaments to separate from the bundle under external forces such as friction and bending, forming fuzzy fibers. High-modulus carbon fibers have a smooth surface and low chemical reactivity. This smooth surface results in insufficient cohesion between the monofilaments within the fiber bundle. During processing such as carding, winding, and weaving, the monofilaments are easily detached due to mutual friction or external pulling, forming fuzz. Furthermore, the low surface reactivity leads to poor coating adhesion during subsequent surface treatments, and the monofilaments at the coating delamination points are also easily exposed and fuzzy. The inherent defects of high-modulus carbon fibers, namely their brittleness and fragility, and the resulting fuzzing problem, severely restrict the expansion of their application scenarios and their safety, becoming a technical bottleneck that the industry urgently needs to overcome. The presence of fuzz creates voids between the composite material layers, reducing structural density and affecting fatigue and corrosion resistance. Simultaneously, fuzz reduces the wetting effect between the carbon fiber and resin, leading to unstable mechanical properties of the composite material and shortening its service life.

[0003] With the increasing demand for materials with "high modulus, high toughness, and high reliability" across various fields, improving high-modulus carbon fibers to enhance their fracture toughness, impact resistance, and anti-fuzzing ability has become an inevitable trend in the industry. This invention develops a toughening and wear-resistant water-based sizing agent for carbon fiber sizing, reducing fuzzing and thus improving the wear resistance of high-modulus carbon fibers. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by proposing a toughening and wear-resistant sizing agent for highly brittle carbon fibers, which solves problems such as large fuzz content, insufficient wear resistance, and easy breakage of existing highly brittle carbon fibers.

[0005] This invention involves reacting isocyanate, polyol, and glycidol to prepare a toughened and wear-resistant resin. The resin is then mixed with deionized water to form an aqueous sizing agent emulsion. Finally, the sizing agent is coated onto the surface of carbon fibers using a carbon fiber sizing device, resulting in a toughened and wear-resistant sizing agent for high-brittle carbon fibers. The introduction of urethane functional groups generated from the reaction of isocyanate and polyol imparts excellent toughness and wear resistance to the material. The introduction of epoxy functional groups provides a good bonding interface between the sizing agent and the epoxy resin matrix, thus producing a toughened and wear-resistant sizing agent for high-brittle carbon fibers.

[0006] The preparation method of toughening and wear-resistant sizing agent for high brittle carbon fiber is as follows:

[0007] (1) Place the polyol in a three-necked flask, evacuate, heat and stir to remove water, and then cool for later use; after the isocyanate is added to the catalyst and mixed evenly, it is slowly added dropwise to the polyol through a constant pressure funnel. After the addition is complete, heat the mixture and keep it warm to obtain a transparent viscous solution 1.

[0008] (2) Dissolve dimethylolbutyric acid in acetone, sonicate to dissolve it completely, add dimethylolbutyric acid solution dropwise to the product solution prepared in step (1), stir evenly and heat to obtain transparent viscous liquid 2.

[0009] (3) After cooling the transparent viscous liquid 2 obtained in step (2), add glycidol, add an appropriate amount of acetone to adjust its viscosity, stir thoroughly and then heat up to react, and obtain toughened and wear-resistant resin.

[0010] (4) Add dimethylethanolamine and acetone to the resin, stir thoroughly and cool to room temperature, gradually add deionized water and stir thoroughly to obtain a milky white water-based sizing agent.

[0011] The specific preparation steps are as follows:

[0012] (1) Place the polyol in a three-necked flask, evacuate, heat to 110°C, heat and stir for 2 hours to remove water, and then cool to 60°C for later use; after the isocyanate is added to the catalyst and mixed evenly, it is slowly dripped into the polyol through a constant pressure funnel for 40 minutes. After the dripping is completed, heat to 75°C, stir at 300 rpm, and keep the reaction at this temperature for 2 hours to obtain a transparent viscous solution 1, and then cool to 50°C.

[0013] The diisocyanate is isoflurone diisocyanate with a purity of 99%; the polyols include polyether polyols and polyester polyols, wherein the polyether polyol is polypropylene glycol with a preferred molecular weight of 400; and the polyester polyol is poly(1,4-butylene adipate) with a preferred molecular weight of 1000.

[0014] (2) Dissolve dimethylolbutyric acid in acetone and sonicate it until it is fully dissolved. Add dimethylolbutyric acid solution dropwise to the product solution prepared in step (1) for 30 minutes. After stirring evenly, heat to 75°C and stir at 350 rpm for 2 hours. Add acetone according to the viscosity to obtain transparent viscous liquid 2.

[0015] The dimethylolbutyric acid has a molecular weight of 148.16 g / mol and a purity of 99%. It is vacuum dried at 50°C for 2 hours before use, and the acetone is dehydrated by molecular sieve for 24 hours before use.

[0016] (3) Cool down to 45°C, add glycidol, stir, react at 75°C for 2 hours to obtain toughened and wear-resistant resin;

[0017] The glycidol has a molecular weight of 74.08 and a purity of 97%. The stirring speed is 300 r / min.

[0018] (4) Cool the toughened and wear-resistant resin to 45°C, add dimethylethanolamine and a small amount of acetone and stir thoroughly (e.g., at a speed of 300 r / min). After stirring for 30 min, cool to room temperature, add deionized water, stir, and finally obtain a milky white water-based sizing agent.

[0019] The relationship between the dosages of diisocyanate, polyol, dimethylolbutyric acid, glycidol, dimethylethanolamine, and acetone is as follows:

[0020] The preferred molar ratio of diisocyanate to polyol is 2.

[0021] The molar ratio of polyether polyol to polyester polyol in polyols is (10-0.2):1, for example, 5:1, 2:1, 0.5:1, etc.

[0022] Dimethylolbutyric acid accounts for 4-6% of the mass of the transparent viscous solution system 1;

[0023] The mass percentage of glycidol in pure viscous liquid 2 is 14wt%-5wt%. Pure viscous liquid 2 is a transparent viscous liquid and does not include acetone. Preferably, the total number of moles of dimethylolbutyric acid multiplied by 2 + glycidol is equal to the number of moles of diisocyanate. The actual amount of glycidol added is 1.2 times the theoretical value.

[0024] The preferred molar ratio of dimethylethanolamine to dimethylolbutyric acid is 1:1.

[0025] This invention is used for sizing high-modulus carbon fibers, such as sizing BHM3 high-modulus carbon fibers (3K).

[0026] Beneficial effects:

[0027] This invention involves reacting isocyanate, polyol, and glycidol to prepare a toughened and wear-resistant epoxy resin. The epoxy resin is then mixed with deionized water to form an aqueous sizing agent emulsion. Finally, the sizing agent is coated onto the surface of carbon fibers using a carbon fiber sizing device, resulting in a toughened and wear-resistant sizing agent for high-brittle carbon fibers. The urethane and polyol in the resin introduce abundant hydrogen bonds, giving the material excellent bundle properties, toughness, and wear resistance. The introduction of epoxy functional groups provides the sizing agent with good reaction sites with the epoxy resin matrix, thus preparing a toughened and wear-resistant sizing agent for high-brittle carbon fibers. Attached Figure Description

[0028] Figure 1 The Fourier transform infrared spectra of the samples obtained in Examples 1-3 are shown.

[0029] Figure 2 This is a schematic diagram of the carbon fiber abrasion resistance test.

[0030] Figure 3 The particle size distribution of the sizing agent emulsion prepared from the samples obtained in Examples 1-3 was determined.

[0031] Figure 4 The images show the frictional fracture morphology of the fibers in the samples obtained in Examples 1-3 after sizing, compared to the fibers in the control example. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] The performance test parameters for the following examples are shown in the table below:

[0034] Example 1

[0035] Take 4g of polypropylene glycol 400 (0.01 mol) and 0g of poly(1,4-butylene adipate) 1000 in a three-necked flask, evacuate and heat to 110℃, stir at 150rpm for 2h to dehydrate, then purge with nitrogen and cool to 60℃ for later use. Mix 4.45g of isoflurane diisocyanate (0.02 mol) with 0.0004g of dibutyltin dilaurate (0.5‰ mass fraction), and slowly add polypropylene glycol 400 dropwise through a constant pressure funnel over 40min, controlling the temperature below 65℃. After the addition is complete, heat to 75℃, stir at 300rpm, and maintain the reaction temperature for 2h. Cool to 50℃ to obtain a colorless and transparent solution. Dissolve 0.42g of dimethylolbutyric acid (0.0028 mol) in 2ml of acetone, and sonicate until completely dissolved to form a clear and transparent solution. A solution of dimethylolbutyric acid in acetone was slowly added dropwise at a stirring speed of 350 rpm over 30 minutes. After the addition was complete, the temperature was raised to 75°C and reacted for 2 hours. The temperature was then lowered to 45°C, and 1.27 g of glycidol (0.017 mol) was added. The mixture was stirred at 300 rpm and reacted at 75°C for 2 hours to obtain a transparent, viscous liquid. The temperature was then lowered to 45°C, and 0.26 g of dimethylethanolamine (0.0028 mol) and 3 ml of acetone were added and stirred thoroughly at 300 rpm for 30 minutes. After cooling to room temperature, 100 ml of deionized water was slowly added dropwise while stirring thoroughly at 1000 rpm for 1 hour. After the addition was complete, the mixture was stirred at 700 rpm for 30 minutes to obtain a milky white aqueous sizing agent.

[0036] The emulsion particle size was tested and found to be 0.149 μm. The slurry was diluted to a concentration of 1 wt% and used to sizing high-modulus carbon fibers. During sizing, BHM3 high-modulus carbon fibers (3K) passed through the slurry at a speed of 15 cm / min, and then dried at a temperature of 110℃. The resulting fibers were then placed on an abrasion resistance testing device for abrasion resistance testing.

[0037] A 200g weight was tied to one end of the fiber and the fiber was passed over a chrome-plated iron rod with a surface roughness of Ra=5μm. The chrome-plated iron rod was rotated at a speed of 30m / min to rub the fiber back and forth. The fiber broke after 245 rubs.

[0038] Example 2

[0039] Take 3.33 g of 1,4-butylene adipate 1000 (0.0033) and 2.66 g of polypropylene glycol 400 (0.0067 mol) in a three-necked flask, evacuate and heat to 110 °C, stir at 150 rpm for 2 h to dehydrate, then purge with nitrogen and cool to 60 °C for later use. Mix 4.45 g of isoflurane diisocyanate (0.02 mol) with 0.0004 g of dibutyltin dilaurate (0.5‰ mass fraction), and slowly add polypropylene glycol 400 dropwise through a constant pressure funnel over 40 min, controlling the temperature below 65 °C. After the addition is complete, heat to 75 °C, stir at 300 rpm, and maintain the reaction temperature for 2 h. Cool to 50 °C to obtain a colorless and transparent solution. 0.52 g of dimethylolbutyric acid (0.0035 mol) was dissolved in 2 ml of acetone and sonicated until completely dissolved, forming a clear and transparent solution. The acetone solution of dimethylolbutyric acid was slowly added dropwise at 350 rpm for 30 min. After the addition was complete, the temperature was raised to 75°C and reacted for 2 h. The temperature was then lowered to 45°C, and 1.18 g of glycidol (0.016 mol) was added. The mixture was stirred at 300 rpm and reacted at 75°C for 2 h, yielding a clear, viscous liquid. The temperature was then lowered to 45°C, and 0.31 g of dimethylethanolamine (0.0035 mol) and 3 ml of acetone were added and stirred thoroughly at 300 rpm for 30 min. After cooling to room temperature, 100 ml of deionized water was slowly added dropwise while stirring thoroughly at 1000 rpm for 1 h. After the addition was complete, the mixture was stirred at 700 rpm for 30 min, finally yielding a milky white water-based sizing agent.

[0040] The emulsion particle size was tested and found to be 0.149 μm. The slurry was diluted to a concentration of 1 wt% and then used to sizing BHM3 high-modulus carbon fiber (3K). The fiber passage speed during sizing was 15 cm / min, and the drying temperature was 110℃. The resulting fibers were then placed on an abrasion resistance testing device for abrasion resistance testing.

[0041] A 200g weight was tied to one end of the fiber and the fiber was passed over a chrome-plated iron rod with a surface roughness of Ra=5μm. The fiber was rubbed back and forth at a speed of 30m / min for 358 cycles before breaking.

[0042] Example 3

[0043] Take 6.66 g of 1,4-butylene adipate 1000 (0.0066 mol) and 1.33 g of polypropylene glycol 400 (0.0033 mol) in a three-necked flask, evacuate and heat to 110 °C, stir at 150 rpm for 2 h to dehydrate, then purge with nitrogen and cool to 60 °C for later use. Mix 4.45 g of isoflurane diisocyanate (0.02 mol) with 0.0004 g of dibutyltin dilaurate (0.5‰ mass fraction), and slowly add polypropylene glycol 400 dropwise through a constant pressure funnel over 40 min, controlling the temperature below 65 °C. After the addition is complete, heat to 75 °C, stir at 300 rpm, and maintain the reaction temperature for 2 h. Cool to 50 °C to obtain a colorless and transparent solution. 0.62 g of dimethylolbutyric acid (0.0042 mol) was dissolved in 2 ml of acetone and sonicated until completely dissolved, forming a clear and transparent solution. The acetone solution of dimethylolbutyric acid was slowly added dropwise at 350 rpm for 30 min. After the addition was complete, the temperature was raised to 75°C and reacted for 2 h. The temperature was then lowered to 45°C, and 1.04 g of glycidol (0.14 mol) was added. The mixture was stirred at 300 rpm and reacted at 75°C for 2 h, yielding a clear, viscous liquid. The temperature was then lowered to 45°C, and 0.37 g of dimethylethanolamine (0.0042 mol) and 3 ml of acetone were added and stirred thoroughly at 300 rpm for 30 min. After cooling to room temperature, 100 ml of deionized water was slowly added dropwise while stirring thoroughly at 1000 rpm for 1 h. After the addition was complete, the mixture was stirred at 700 rpm for 30 min, finally yielding a milky white water-based sizing agent.

[0044] The emulsion particle size was tested and found to be 0.150 μm. The slurry was diluted to a concentration of 1 wt% and then applied to BHM3 high-modulus carbon fiber (3K) at a fiber speed of 15 cm / min and a drying temperature of 110℃. The resulting fibers were then placed on an abrasion resistance testing device for abrasion resistance testing.

[0045] A 200g weight was tied to one end of a fiber, which was then passed over a chrome-plated iron rod with a surface roughness of Ra=5μm. The fiber was rubbed back and forth at a speed of 30m / min for 740 cycles before breaking.

[0046] Compare with Example 1

[0047] BHM3 high modulus carbon fiber (3K) was immersed in acetone solution and subjected to Soxhlet extraction at 80°C for 2 hours to desizing. The resulting degummed carbon fiber was then placed on an abrasion resistance testing device for abrasion resistance testing.

[0048] A 200g weight was tied to one end of the fiber and the fiber was passed over a chrome-plated iron rod with a surface roughness of Ra=5μm. The fiber was rubbed back and forth at a speed of 30m / min. After 193 rubs, the fiber showed obvious pull-out and breakage and could not be used.

Claims

1. A method for preparing a toughening and wear-resistant sizing agent for highly brittle carbon fibers, characterized in that, Includes the following steps: (1) Place the polyol in a three-necked flask, evacuate, heat and stir to remove water, and then cool for later use; after the isocyanate is added to the catalyst and mixed evenly, it is slowly added dropwise to the polyol through a constant pressure funnel. After the addition is complete, heat the mixture and keep it warm to obtain a transparent viscous solution 1. (2) Dissolve dimethylolbutyric acid in acetone, sonicate to dissolve it completely, add dimethylolbutyric acid solution dropwise to the product solution prepared in step (1), stir evenly and heat to obtain transparent viscous liquid 2. (3) After cooling the transparent viscous liquid 2 obtained in step (2), add glycidol, add an appropriate amount of acetone to adjust its viscosity, stir thoroughly and then heat up to react, and obtain toughened and wear-resistant resin. (4) Add dimethylethanolamine and acetone to the resin, stir thoroughly and cool to room temperature, gradually add deionized water and stir thoroughly to obtain a milky white water-based sizing agent.

2. The method according to claim 1, characterized in that, Specifically, the following steps are included: (1) Place the polyol in a three-necked flask, evacuate, heat to 110°C, heat and stir for 2 hours to remove water, and then cool to 60°C for later use; after the isocyanate is added to the catalyst and mixed evenly, it is slowly dripped into the polyol through a constant pressure funnel for 40 minutes. After the dripping is completed, heat to 75°C, stir at 300 rpm, and keep the reaction at this temperature for 2 hours to obtain a transparent viscous solution 1, and then cool to 50°C. The diisocyanate is isoflurone diisocyanate with a purity of 99%; the polyols include polyether polyols and polyester polyols, wherein the polyether polyol is polypropylene glycol with a preferred molecular weight of 400; and the polyester polyol is poly(1,4-butylene adipate) with a preferred molecular weight of 1000. (2) Dissolve dimethylolbutyric acid in acetone and sonicate it until it is fully dissolved. Add dimethylolbutyric acid solution dropwise to the product solution prepared in step (1) for 30 minutes. After stirring evenly, heat to 75°C and stir at 350 rpm for 2 hours. Add acetone according to the viscosity to obtain transparent viscous liquid 2. The dimethylolbutyric acid has a molecular weight of 148.16 g / mol and a purity of 99%. It is vacuum dried at 50°C for 2 hours before use, and the acetone is dehydrated by molecular sieve for 24 hours before use. (3) Cool down to 45°C, add glycidol, stir, react at 75°C for 2 hours to obtain toughened and wear-resistant resin; Among them, glycidol has a molecular weight of 74.08 and a purity of 97%; (4) Cool the toughened and wear-resistant resin to 45°C, add dimethylethanolamine and a small amount of acetone to it and stir thoroughly. After stirring for 30 minutes, cool to room temperature, add deionized water and stir to finally obtain a milky white water-based sizing agent.

3. The method according to claim 1 or 2, characterized in that, The dosage relationships of diisocyanate, polyol, dimethylolbutyric acid, glycidol, dimethylethanolamine, and acetone are as follows: The molar ratio of diisocyanate to polyol is 2; The molar ratio of polyether polyol to polyester polyol in the polyol is (10-0.2):1; Dimethylolbutyric acid accounts for 4-6% of the mass of the transparent viscous solution system 1; The mass percentage of glycidol in pure viscous liquid 2 is 14wt%-5wt%, and pure viscous liquid 2 is a transparent viscous liquid 2 excluding acetone; preferably, the molar ratio of dimethylethanolamine to dimethylolbutyric acid is 1:

1.

4. The method according to claim 3, characterized in that, The total number of moles of dimethylolbutyric acid multiplied by 2 plus the total number of moles of glycidol equals the number of moles of diisocyanate. The actual amount of glycidol added is 1.2 times the theoretical value.

5. The sizing agent prepared according to any one of claims 1-4.

6. The application of the sizing agent prepared according to any one of claims 1-4 for sizing high modulus carbon fibers.

7. The application according to claim 6, wherein BHM3 high modulus carbon fiber is sized after dilution.

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