Carbon fiber reinforced 3D printing wire rod and preparation method thereof

Abstract

According to the carbon fiber reinforced 3D printing wire rod and the preparation method thereof, the mechanical property of continuous carbon fibers and a resin matrix can be effectively improved, full transmission of loads in a composite material can be effectively guaranteed, and improvement of the overall performance of the composite material is guaranteed; meanwhile, the short carbon fibers are doped into the carbon fiber reinforced 3D printing wire rod, so that the fluidity of the short carbon fibers in a molten matrix can be effectively improved, and the mechanical property of the carbon fiber reinforced 3D printing wire rod can be effectively ensured; the composite treatment agent can effectively enhance the surface modification treatment effect on the short carbon fibers and the continuous carbon fibers, so that the combination effect of the short carbon fibers and the continuous carbon fibers with the thermoplastic resin is better; nickel hydroxide and polydopamine modification can fill the defects of the short carbon fibers, the interface bonding state of the short carbon fibers and the thermoplastic resin is improved, correspondingly, the deformation resistance is higher during external force loading, and the interlaminar shear strength can be improved to different degrees.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing wires, and more specifically, to a carbon fiber reinforced 3D printing wire and a preparation method thereof. Background Art

[0002] 3D printing filaments refer to the filaments used in 3D printing technology, which mainly provide raw materials for 3D printing work; applying carbon fiber reinforced thermoplastic composite filaments to 3D printing technology is one of the effective ways to achieve the integrated manufacturing of complex structural parts of advanced composite materials.

[0003] The patent (CN113150329B) discloses a continuous carbon fiber reinforced polyetheretherketone 3D printing wire and its preparation method. The preparation method is: after the continuous carbon fiber is subjected to desizing treatment, sizing treatment and synchronous impregnation in-situ composite treatment in sequence, it is composited with molten extruded polyetheretherketone and then cooled and rolled to obtain a continuous carbon fiber reinforced polyetheretherketone 3D printing wire; the sizing treatment is a process in which the continuous carbon fiber passes through a polyamic acid solution and a layer of polyamic acid is uniformly coated on the surface of the continuous carbon fiber; the synchronous impregnation in-situ composite treatment is a process in which the continuous carbon fiber and the polyetheretherketone undergo physical entanglement and chemical interaction to form a strong interface bond; the final wire obtained includes continuous carbon fiber, polyetheretherketone matrix and the interface layer between the two. The method of the present invention improves the wettability and interface strength of the fiber and the resin, and the obtained wire can meet the FDM process, and the tensile strength and shear strength are respectively increased by 32% and 44% over the existing process.

[0004] The above-mentioned patents mainly use continuous carbon fibers for reinforcement, but the mechanical properties of the resin matrix between continuous fibers are poor, making it difficult to ensure sufficient transfer of the internal load of the composite material, affecting the improvement of the overall performance of the composite material. The discontinuity of short fibers and the addition of short fibers lead to a significant decrease in the fluidity of the molten matrix, resulting in a large number of voids in the samples printed by the in-situ impregnation process due to insufficient impregnation of the matrix with fibers, limiting the improvement of the mechanical properties of the samples. Summary of the invention

[0005] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a carbon fiber reinforced 3D printing wire and a preparation method thereof.

[0006] A carbon fiber reinforced 3D printing wire comprises, by weight percentage, 14.4-15.4% of short carbon fibers, 19.6-20.6% of continuous carbon fibers, 1.8-2.2% of a composite treatment agent, and the remainder being a thermoplastic resin.

[0007] Furthermore, the raw materials of the composite treatment agent are calculated by weight percentage as follows: 8.4-9.4% urea, 5.0-5.8% dopamine hydrochloride, 35.0-37.0% carbon nanotubes, and the rest nickel hydroxide.

[0008] Furthermore, a carbon fiber reinforced 3D printing wire is calculated by weight percentage as follows: 14.7-15.1% of short carbon fibers, 19.9-20.3% of continuous carbon fibers, 1.9-2.1% of a composite treatment agent, and the rest is a thermoplastic resin; the raw materials of the composite treatment agent are calculated by weight percentage as follows: 8.7-9.1% of urea, 5.3-5.5% of dopamine hydrochloride, 35.5-36.5% of carbon nanotubes, and the rest is nickel hydroxide.

[0009] Furthermore, a carbon fiber reinforced 3D printing wire is calculated by weight percentage as follows: 14.9-15.4% of short carbon fibers, 20.1-20.6% of continuous carbon fibers, 2.0-2.2% of a composite treatment agent, and the rest is a thermoplastic resin; the raw materials of the composite treatment agent are calculated by weight percentage as follows: 8.9-9.4% of urea, 5.4-5.8% of dopamine hydrochloride, 36.0-37.0% of carbon nanotubes, and the rest is nickel hydroxide.

[0010] Furthermore, a carbon fiber reinforced 3D printing wire is calculated by weight percentage as follows: 14.9% short carbon fiber, 20.1% continuous carbon fiber, 2.0% composite treatment agent, and the rest is thermoplastic resin; the raw materials of the composite treatment agent are calculated by weight percentage as follows: 8.9% urea, 5.4% dopamine hydrochloride, 36.0% carbon nanotubes, and the rest is nickel hydroxide.

[0011] Furthermore, the thermoplastic resin is one or a combination of polyamide, polyetheretherketone, polyphenylene sulfide, polyimide, and polyetherimide.

[0012] A method for preparing a carbon fiber reinforced 3D printing wire, the specific preparation steps are as follows:

[0013] Step 1: weigh short carbon fibers, continuous carbon fibers, thermoplastic resins in the raw materials, and urea, dopamine hydrochloride, carbon nanotubes, and nickel hydroxide in the composite treatment agent raw materials;

[0014] Step 2: adding carbon nanotubes to a strong acid, subjecting them to water bath ultrasonic treatment for 7 to 8 hours, centrifugation filtering, washing to neutrality, and drying to obtain modified carbon nanotubes;

[0015] Step 3: Add nickel hydroxide to deionized water, perform ultrasonic treatment for 10 to 20 minutes, add short carbon fiber, perform ultrasonic treatment for another 10 to 20 minutes, then add urea, perform water bath ultrasonic treatment for 3 to 5 hours, wash and dry to obtain a mixture A;

[0016] Step 4: adding the modified carbon nanotubes and dopamine hydrochloride to deionized water, ultrasonically treating for 10 to 20 minutes, adding mixed material A, adjusting the pH to 7.2 to 7.8, ultrasonically treating for 1 to 2 hours, washing and drying to obtain mixed material B;

[0017] Step 5: Adding mixed material B to the thermoplastic resin, heating and melting it, and then stirring it for 1 to 2 hours to obtain modified material C;

[0018] Step six: The modified material C is used as the matrix and the continuous carbon fiber is used as the fiber. The modified material C is fed into the fiber-matrix mixing module for mixing and is fully mixed under the action of the heating block to form a synchronously reinforced composite filament. The synchronously reinforced composite filament is then extruded by the rollers in the roller impregnation module and enters the wire shaping module to form a carbon fiber reinforced 3D printing wire under the shaping action of the wire shaping module. Finally, the carbon fiber reinforced 3D printing wire is uniformly collected on the wire winding drum through the dragging action of the winding module.

[0019] Furthermore, in step one, the short carbon fibers and the continuous carbon fibers are put into deionized water and subjected to water bath ultrasonic cleaning for 20 to 40 minutes, the water bath temperature is 50 to 60° C., the ultrasonic frequency is 1.5 to 1.7 MHz, and the ultrasonic power is 400 to 600 W; in step two, the strong acid is one or a combination of nitric acid and concentrated sulfuric acid, the weight ratio of the carbon nanotubes to the strong acid is 1:40 to 60, the water bath temperature is 70 to 80° C., the ultrasonic frequency is 60 to 80 KHz, and the ultrasonic power is 400 to 600 W; the deionized water is used for repeated washing until the washing liquid is neutral, and then the carbon fibers are dried at 70 to 80° C.

[0020] Furthermore, in step three, the weight ratio of nickel hydroxide to deionized water is 1:90-110, the ultrasonic frequency is 1.5-1.7 MHz, the ultrasonic power is 400-600 W, the water bath temperature is 50-60° C., and the cleaning treatment is performed with deionized water; in step four, the weight ratio of the total weight of the modified carbon nanotubes and dopamine hydrochloride to deionized water is 1:90-100, the ultrasonic frequency is 1.5-1.7 MHz, and the ultrasonic power is 400-600 W; and dilute hydrochloric acid is used to adjust the pH value.

[0021] Furthermore, in step five, the mixing speed is 300-600 r / min; in step six, the wire making speed is 110-130 cm / min, and the diameter of the shaping die in the wire shaping module is selected to be 0.7-0.9 mm.

[0022] Technical effects and advantages of the present invention:

[0023] 1. The carbon fiber reinforced 3D printing wire prepared by the raw material formula of the present invention can effectively improve the mechanical properties of the continuous carbon fiber and the resin matrix, can effectively ensure the full transfer of the internal load of the composite material, and ensure the improvement of the overall performance of the composite material. At the same time, short carbon fibers are added to the carbon fiber reinforced 3D printing wire, which can effectively ensure the improvement of the fluidity of the short carbon fibers in the molten matrix, reduce the voids in the matrix, and effectively ensure the mechanical properties of the carbon fiber reinforced 3D printing wire; the composite treatment agent can effectively perform a blending modification treatment on the short carbon fibers and the continuous carbon fibers, and can effectively enhance the surface modification treatment effect of the short carbon fibers and the continuous carbon fibers, so that the combination effect of the short carbon fibers and the continuous carbon fibers with the thermoplastic resin is better; the composite treatment The carbon nanotubes in the agent are surface-modified under the action of strong acid to obtain carboxyl-modified carbon nanotubes, and the modified carbon nanotubes are grafted on the surface of carbon fibers to obtain carbon nanotube-carbon fiber multi-scale reinforcements, which can effectively improve the bonding effect between short carbon fibers and thermoplastic resin matrix; after being modified with nickel hydroxide, the surface grooves of the short carbon fibers basically disappear and are covered with white mesh substances; the modified carbon nanotubes and dopamine hydrochloride are used together to modify the surface of the short carbon fibers after the surface modification with nickel hydroxide again, and both nickel hydroxide and further polydopamine modification will fill the defects of the short carbon fibers and improve the interface bonding state between the short carbon fibers and the thermoplastic resin, and accordingly, the ability to resist deformation when external force is loaded is stronger, and the interlaminar shear strength will be improved to varying degrees;

[0024] 2. The present invention adds carbon nanotubes to a strong acid and performs ultrasonic treatment in a water bath, which can effectively perform surface modification treatment on the carbon nanotubes to obtain carboxyl-modified carbon nanotubes, which can effectively improve the subsequent grafting treatment of the carbon nanotubes with the surfaces of short carbon fibers and continuous carbon fibers, and can further strengthen the subsequent bonding effect of short carbon fibers and continuous carbon fibers with thermoplastic resins, thereby improving the mechanical properties of carbon fiber-reinforced 3D printing wires; after adding nickel hydroxide to deionized water, adding short carbon fibers for ultrasonic treatment, and adding urea for ultrasonic treatment, the short carbon fibers can be effectively modified. The surface is modified with nickel hydroxide; the modified carbon nanotubes and dopamine hydrochloride are added to deionized water for ultrasonic treatment, and then the pH value is adjusted after adding the mixture A. Ultrasonic treatment can effectively deposit polydopamine on the surface of the nickel hydroxide modified short carbon fiber; the thermoplastic resin and the mixture B are heated, melted and stirred to make a modified material C; the synchronously reinforced prepreg wire prepared by the "mixing-impregnation-shaping" process route (successively passing through the fiber-matrix mixing module, the roller impregnation module and the wire shaping module) has almost no fiber pullout at the break and has the highest tensile strength. DETAILED DESCRIPTION

[0025] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Embodiment 1:

[0027] The present invention provides a carbon fiber reinforced 3D printing wire, which comprises 144 g of short carbon fiber, 196 g of continuous carbon fiber, 18 g of a composite treatment agent, and 642 g of nylon 6; the raw materials of the composite treatment agent are: 1.512 g of urea, 0.9 g of dopamine hydrochloride, 6.3 g of carbon nanotubes, and 9.288 g of nickel hydroxide;

[0028] Short carbon fiber was purchased from Zibo Kunmaoda New Materials Co., Ltd., item number: CF300S; continuous carbon fiber was T300-1000 continuous carbon fiber tow (Toray, Japan); nylon 6 was purchased from Baiyi New Materials Technology (Dongguan) Co., Ltd., model: TP-4208; urea was purchased from Shanghai Yuanye Biotechnology Co., Ltd., item number: S30375; dopamine hydrochloride was purchased from Sinopharm Chemical Reagent Co., Ltd., national medicine code: XW00623172; carbon nanotubes were purchased from Sinopharm Chemical Reagent Co., Ltd., national medicine code: XW3080685669; nickel hydroxide was purchased from Sinopharm Chemical Reagent Co., Ltd., national medicine code: TN1202500G;

[0029] The preparation method of carbon fiber reinforced 3D printing wire, the specific preparation steps are as follows:

[0030] Step 1: weigh short carbon fibers, continuous carbon fibers, nylon 6 in the raw materials, and urea, dopamine hydrochloride, carbon nanotubes, and nickel hydroxide in the composite treatment agent raw materials;

[0031] Step 2: adding carbon nanotubes to a nitric acid solution, subjecting the carbon nanotubes to water bath ultrasonic treatment for 7.5 hours, centrifugally filtering, washing to neutrality, and drying to obtain modified carbon nanotubes;

[0032] Step 3: Add nickel hydroxide to deionized water, perform ultrasonic treatment for 15 minutes, add short carbon fiber, perform ultrasonic treatment for another 15 minutes, then add urea, perform water bath ultrasonic treatment for 4 hours, wash and dry to obtain a mixture A;

[0033] Step 4: adding the modified carbon nanotubes and dopamine hydrochloride to deionized water, ultrasonically treating for 15 minutes, adding mixed material A, adjusting the pH to 7.5, ultrasonically treating for 1.5 hours, washing and drying, and obtaining mixed material B;

[0034] Step 5: Add nylon 6 to mixed material B, heat and melt it, and stir it for 1.5 hours to obtain modified material C;

[0035] Step six: The modified material C is used as the matrix and the continuous carbon fiber is used as the fiber. The modified material C is fed into the fiber-matrix mixing module for mixing and is fully mixed under the action of the heating block to form a synchronously reinforced composite filament. The synchronously reinforced composite filament is then extruded by the rollers in the roller impregnation module and enters the wire shaping module to form a carbon fiber reinforced 3D printing wire under the shaping action of the wire shaping module. Finally, the carbon fiber reinforced 3D printing wire is uniformly collected on the wire winding drum through the dragging action of the winding module.

[0036] In step one, short carbon fibers and continuous carbon fibers are put into deionized water for water bath ultrasonic cleaning for 20 minutes, the water bath temperature is 50°C, the ultrasonic frequency is 1.5MHz, and the ultrasonic power is 400W; in step two, the concentration of nitric acid solution is 70%, the weight ratio of carbon nanotubes to nitric acid solution is 1:40, the water bath temperature is 70°C, the ultrasonic frequency is 60KHz, and the ultrasonic power is 400W; deionized water is used for repeated washing until the washing solution is neutral, and drying is performed at 70°C; in step three, the weight ratio of nickel hydroxide to deionized water is 1:90, the ultrasonic frequency is 1.5MHz, the ultrasonic power is 400W, and the water bath is 50°C. The temperature is 50°C and the cleaning is carried out with deionized water; in step 4, the weight ratio of the total weight of the modified carbon nanotubes and dopamine hydrochloride to the deionized water is 1:90, the ultrasonic frequency is 1.5MHz, and the ultrasonic power is 400W; dilute hydrochloric acid is used to adjust the pH value; in step 5, the mixing speed is 300r / min; in step 6, the silk making speed is 110cm / min, and the diameter of the forming mold in the wire shaping module is selected to be 0.7mm; nylon 6 is selected as the thermoplastic resin, and the melting temperature in step 5 is 300°C; in step 6, the temperature of the fiber-matrix mixing module, the roller impregnation module and the wire shaping module are all selected to be 270°C.

[0037] Embodiment 2:

[0038] Different from Example 1, the carbon fiber reinforced 3D printing wire weighs 154g of short carbon fiber, 206g of continuous carbon fiber, 22g of composite treatment agent, and 618g of nylon 6; the raw materials of the composite treatment agent are: 2.068g of urea, 1.276g of dopamine hydrochloride, 8.14g of carbon nanotubes, and 10.516g of nickel hydroxide.

[0039] Embodiment 3:

[0040] Different from Examples 1-2, the carbon fiber reinforced 3D printing wire weighs 149g of short carbon fiber, 201g of continuous carbon fiber, 20g of composite treatment agent, and 630g of nylon 6; the raw materials of the composite treatment agent are: 1.78g of urea, 1.08g of dopamine hydrochloride, 7.20g of carbon nanotubes, and 9.94g of nickel hydroxide.

[0041] Embodiment 4:

[0042] The difference from Example 3 is that in step 1, the short carbon fiber and the continuous carbon fiber are put into deionized water and subjected to water bath ultrasonic cleaning for 30 minutes, the water bath temperature is 55°C, the ultrasonic frequency is 1.6MHz, and the ultrasonic power is 500W; in step 2, the concentration of the nitric acid solution is 70%, the weight ratio of the carbon nanotubes to the nitric acid solution is 1:50, the water bath temperature is 75°C, the ultrasonic frequency is 70KHz, and the ultrasonic power is 500W; the deionized water is used for repeated washing until the washing solution is neutral, and the washing solution is dried at 75°C; in step 3, the hydroxyl radical is used for the washing solution. The weight ratio of nickel chloride to deionized water is 1:100, the ultrasonic frequency is 1.6 MHz, the ultrasonic power is 500 W, the water bath temperature is 55°C, and the cleaning treatment is carried out with deionized water; in step 4, the weight ratio of the total weight of the modified carbon nanotubes and dopamine hydrochloride to deionized water is 1:95, the ultrasonic frequency is 1.6 MHz, and the ultrasonic power is 500 W; dilute hydrochloric acid is used to adjust the pH value; in step 5, the mixing speed is 450 r / min; in step 6, the silk making speed is 120 cm / min, and the diameter of the shaping mold in the wire shaping module is 0.8 mm.

[0043] Comparative Example 1:

[0044] The difference from Example 4 is that: the carbon fiber reinforced 3D printing wire weighs 149g of short carbon fiber, 201g of continuous carbon fiber, and 630g of nylon 6;

[0045] The preparation method of carbon fiber reinforced 3D printing wire, the specific preparation steps are as follows:

[0046] Step 1: Weigh the short carbon fiber, continuous carbon fiber and nylon 6 in the raw materials;

[0047] Step 2: Blending nylon 6 and short carbon fibers, heating and melting them, and stirring them for 4 hours to obtain modified material C;

[0048] Step 3: The modified material C is used as a matrix and the continuous carbon fiber is used as a fiber. The modified material C is fed into the fiber-matrix mixing module for mixing and fully mixed under the action of the heating block to form a synchronously reinforced composite filament; then, the synchronously reinforced composite filament is extruded by the roller in the roller impregnation module and enters the wire shaping module, and under the shaping action of the wire shaping module, a carbon fiber reinforced 3D printing wire is formed; finally, the carbon fiber reinforced 3D printing wire is uniformly collected on the wire winding drum through the dragging action of the winding module;

[0049] In step 2, the mixing speed is 300 r / min; in step 3, the silk making speed is 110 cm / min, and the diameter of the forming mold in the wire shaping module is 0.7 mm; nylon 6 is selected as the thermoplastic resin, and the melting temperature in step 2 is 300°C; in step 3, the temperature of the fiber-matrix mixing module, the roller impregnation module and the wire shaping module are all selected to be 270°C.

[0050] Comparative Example 2:

[0051] The difference from Example 4 is that: the carbon fiber reinforced 3D printing wire weighs 149g of short carbon fiber, 201g of continuous carbon fiber, 12.8g of composite treatment agent, and 630g of nylon 6; the raw materials of the composite treatment agent are: 1.78g of urea, 1.08g of dopamine hydrochloride, and 9.94g of nickel hydroxide;

[0052] The preparation method of carbon fiber reinforced 3D printing wire, the specific preparation steps are as follows:

[0053] Step 1: Weigh short carbon fibers, continuous carbon fibers, nylon 6 in the raw materials, and urea, dopamine hydrochloride, and nickel hydroxide in the composite treatment agent raw materials;

[0054] Step 2: Add nickel hydroxide to deionized water, perform ultrasonic treatment for 15 minutes, add short carbon fiber, perform ultrasonic treatment for another 15 minutes, then add urea, perform water bath ultrasonic treatment for 4 hours, wash and dry to obtain a mixture A;

[0055] Step 3: Add dopamine hydrochloride to deionized water, perform ultrasonic treatment for 15 minutes, add mixed material A, adjust pH to 7.5, perform ultrasonic treatment for 1.5 hours, wash and dry, and obtain mixed material B;

[0056] Step 4: Add nylon 6 to mixed material B, heat and melt it, and stir it for 1.5 hours to obtain modified material C;

[0057] Step 5: The modified material C is used as a matrix and the continuous carbon fiber is used as a fiber. The modified material C is fed into the fiber-matrix mixing module for mixing and fully mixed under the action of the heating block to form a synchronously reinforced composite filament; then, the synchronously reinforced composite filament is extruded by the roller in the roller impregnation module and enters the wire shaping module, and under the shaping action of the wire shaping module, a carbon fiber reinforced 3D printing wire is formed; finally, the carbon fiber reinforced 3D printing wire is uniformly collected on the wire winding drum through the dragging action of the winding module;

[0058] In step 1, short carbon fiber and continuous carbon fiber are put into deionized water and subjected to water bath ultrasonic cleaning for 30 minutes, the water bath temperature is 55°C, the ultrasonic frequency is 1.6MHz, and the ultrasonic power is 500W; in step 2, the weight ratio of nickel hydroxide to deionized water is 1:100, the ultrasonic frequency is 1.6MHz, the ultrasonic power is 500W, the water bath temperature is 55°C, and the cleaning is carried out with deionized water; in step 3, the weight ratio of dopamine hydrochloride to deionized water is 1:95, The ultrasonic frequency is 1.6MHz, and the ultrasonic power is 500W; dilute hydrochloric acid is used to adjust the pH value; in step 4, the mixing speed is 450r / min; in step 5, the spinning speed is 120cm / min, and the diameter of the forming mold in the wire shaping module is selected to be 0.8mm; nylon 6 is selected as the thermoplastic resin, and the melting temperature in step 4 is 300℃; in step 5, the temperatures of the fiber-matrix mixing module, the roller impregnation module and the wire shaping module are all selected to be 270℃.

[0059] Comparative Example 3:

[0060] The difference from Example 4 is that:

[0061] Carbon fiber reinforced 3D printing wire, weigh 149g of short carbon fiber, 201g of continuous carbon fiber, 7.2g of composite treatment agent, 630g of nylon 6; the raw material of the composite treatment agent is: 7.20g of carbon nanotubes;

[0062] The preparation method of carbon fiber reinforced 3D printing wire, the specific preparation steps are as follows:

[0063] Step 1: Weigh short carbon fibers, continuous carbon fibers, nylon 6 in the raw materials, and carbon nanotubes in the composite treatment agent raw materials;

[0064] Step 2: adding carbon nanotubes to a nitric acid solution, subjecting the carbon nanotubes to water bath ultrasonic treatment for 7.5 hours, centrifugally filtering, washing to neutrality, and drying to obtain modified carbon nanotubes;

[0065] Step 3: adding the modified carbon nanotubes and short carbon fibers into deionized water, ultrasonically treating for 1.5 hours, washing and drying to obtain a mixture B;

[0066] Step 4: Add nylon 6 to mixed material B, heat and melt it, and stir it for 1.5 hours to obtain modified material C;

[0067] Step 5: The modified material C is used as a matrix and the continuous carbon fiber is used as a fiber. The modified material C is fed into the fiber-matrix mixing module for mixing and fully mixed under the action of the heating block to form a synchronously reinforced composite filament; then, the synchronously reinforced composite filament is extruded by the roller in the roller impregnation module and enters the wire shaping module, and under the shaping action of the wire shaping module, a carbon fiber reinforced 3D printing wire is formed; finally, the carbon fiber reinforced 3D printing wire is uniformly collected on the wire winding drum through the dragging action of the winding module;

[0068] In step 1, short carbon fiber and continuous carbon fiber are put into deionized water and subjected to water bath ultrasonic cleaning for 30 minutes, the water bath temperature is 55°C, the ultrasonic frequency is 1.6MHz, and the ultrasonic power is 500W; in step 2, the concentration of nitric acid solution is 70%, the weight ratio of carbon nanotubes to nitric acid solution is 1:50, the water bath temperature is 75°C, the ultrasonic frequency is 70KHz, and the ultrasonic power is 500W; deionized water is used for repeated washing until the washing solution is neutral, and drying is performed at 75°C; in step 4, the carbon fiber and continuous carbon fiber are subjected to water bath ultrasonic cleaning for 30 minutes, the water bath temperature is 55°C, the ultrasonic frequency is 1.6MHz, and the ultrasonic power is 500W; The weight ratio of the total weight of the carbon nanotubes and short carbon fibers to the deionized water is 1:95, the ultrasonic frequency is 1.6 MHz, and the ultrasonic power is 500 W; in step 4, the mixing speed is 450 r / min; in step 5, the spinning speed is 120 cm / min, and the diameter of the forming mold in the wire shaping module is 0.8 mm; nylon 6 is selected as the thermoplastic resin, and the melting temperature in step 4 is 300°C; in step 5, the temperatures of the fiber-matrix mixing module, the roller impregnation module and the wire shaping module are all selected to be 270°C.

[0069] The carbon fiber reinforced 3D printing wires in the comparative examples and embodiments of the present invention were tested and processed:

[0070] The test standard for tensile strength and tensile modulus is ASTM D4018-11;

[0071] The shear strength test standard is ASTM D4475-2002 (R2016);

[0072] The results are shown in Table 1:

[0073] Table 1:

[0074]

[0075] It can be seen from the above table that the carbon fiber reinforced 3D printing wire of the present invention can effectively improve the mechanical properties of continuous carbon fiber and resin matrix, can effectively ensure the full transfer of internal load of the composite material, and ensure the improvement of the overall performance of the composite material. At the same time, short carbon fibers are added to the carbon fiber reinforced 3D printing wire, which can effectively ensure the improvement of the fluidity of the short carbon fibers in the molten matrix, reduce the voids in the matrix, and effectively ensure the mechanical properties of the carbon fiber reinforced 3D printing wire.

[0076] In the present invention, the composite treatment agent can effectively carry out blending modification treatment on short carbon fibers and continuous carbon fibers, and can effectively enhance the surface modification treatment effect on short carbon fibers and continuous carbon fibers, so that the bonding effect between short carbon fibers and continuous carbon fibers and thermoplastic resin is better; the carbon nanotubes in the composite treatment agent are surface-modified under the action of strong acid to obtain carboxyl-modified carbon nanotubes, and then the carboxyl-modified carbon nanotubes are grafted on the surface of short carbon fibers, and the modified carbon nanotubes are grafted on the surface of carbon fibers to obtain carbon nanotube-carbon fiber multi-scale reinforcement, which can effectively improve the bonding effect between short carbon fibers and thermoplastic resin matrix; the nickel hydroxide in the composite treatment agent is surface-modified on short carbon fibers under the blending treatment of urea, which can effectively realize the nickel hydroxide of short carbon fibers. After the modification treatment, processing grooves appeared on the surface of the short carbon fibers after the sizing agent was applied, the depth of the surface grooves varied, and the surface of the short carbon fibers had a large roughness; after the nickel hydroxide modification treatment, the surface grooves of the short carbon fibers basically disappeared and were covered by a white mesh substance; the modified carbon nanotubes and dopamine hydrochloride were used together to modify the surface of the short carbon fibers after the nickel hydroxide surface modification treatment. Both nickel hydroxide and further polydopamine modification would fill the defects of the short carbon fibers and improve the interface bonding state between the short carbon fibers and the thermoplastic resin. Accordingly, the ability to resist deformation under external force loading would be stronger, and the interlaminar shear strength would be improved to varying degrees. The polydopamine modification would fill the mesh structure of the surface of the short carbon fibers after the nickel hydroxide surface modification treatment, and the surface improvement effect of the short carbon fibers would be stronger.

[0077] In step 2, the carbon nanotubes are added to a strong acid and ultrasonically treated in a water bath, which can effectively modify the surface of the carbon nanotubes to obtain carboxyl-modified carbon nanotubes, which can effectively improve the subsequent grafting treatment of the carbon nanotubes with the surfaces of short carbon fibers and continuous carbon fibers, and can further strengthen the bonding effect of the subsequent short carbon fibers and continuous carbon fibers with thermoplastic resins, thereby improving the mechanical properties of carbon fiber-reinforced 3D printing wires; in step 3, after nickel hydroxide is added to deionized water, short carbon fibers are added for ultrasonic treatment, and urea is added for ultrasonic treatment at the same time, which can effectively achieve nickel hydroxide modification of the surface of the short carbon fibers; in step 4, the modified carbon nanotubes and dopamine hydrochloride are added to deionized water for ultrasonic treatment, and then the pH value is adjusted after the mixture A is added. The ultrasonic treatment can effectively deposit polydopamine on the surface of the nickel hydroxide-modified short carbon fibers; in step 5, the thermoplastic resin and the mixture B (nickel hydroxide-modified short carbon fibers with polydopamine deposited on the surface) are heated, melted and stirred to prepare modified material C; in In step six, there is a large area of ​​unimpregnated area in the prepreg wire prepared by the in-situ mixing process route, and with the addition of the shaping module and the roller impregnation module in the process route, more short carbon fiber matrix material is impregnated into the continuous carbon fiber bundle, and the unimpregnated area in the prepreg wire gradually decreases, and the degree of impregnation gradually increases; at the same time, the matrix material fully impregnates the continuous carbon fiber bundle; the roller impregnation module can provide sufficient impregnation pressure and impregnation pressure action distance through the extrusion action of two rollers, ensuring the full impregnation of the continuous fiber and the matrix material, thereby achieving a substantial improvement in the tensile strength of the synchronously reinforced prepreg wire; and the wire shaping module can only provide a certain impregnation pressure through the wedge structure inside its channel, with the help of the excess matrix material attached to the synchronously reinforced composite wire; the synchronously reinforced prepreg wire prepared by the "mixing-impregnation-shaping" process route (successively through the fiber-matrix mixing module, the roller impregnation module and the wire shaping module) has almost no fiber pullout at the break, and its tensile strength is the highest.

[0078] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A carbon fiber reinforced 3D printing wire, characterized in that: The composition is calculated by weight percentage as follows: 14.4-15.4% of short carbon fibers, 19.6-20.6% of continuous carbon fibers, 1.8-2.2% of composite treatment agent, and the rest is thermoplastic resin.

2. The carbon fiber reinforced 3D printing wire according to claim 1, characterized in that: The raw materials of the composite treatment agent are calculated by weight percentage as follows: 8.4-9.4% urea, 5.0-5.8% dopamine hydrochloride, 35.0-37.0% carbon nanotubes, and the rest is nickel hydroxide.

3. The carbon fiber reinforced 3D printing wire according to claim 2, characterized in that: Calculated by weight percentage: 14.7-15.1% of short carbon fibers, 19.9-20.3% of continuous carbon fibers, 1.9-2.1% of composite treatment agent, and the rest is thermoplastic resin; the raw materials of the composite treatment agent are calculated by weight percentage: 8.7-9.1% urea, 5.3-5.5% dopamine hydrochloride, 35.5-36.5% carbon nanotubes, and the rest is nickel hydroxide.

4. The carbon fiber reinforced 3D printing wire according to claim 2, characterized in that: The weight percentage is: 14.9-15.4% of short carbon fibers, 20.1-20.6% of continuous carbon fibers, 2.0-2.2% of composite treatment agent, and the rest is thermoplastic resin; the raw materials of the composite treatment agent are calculated as follows: 8.9-9.4% urea, 5.4-5.8% dopamine hydrochloride, 36.0-37.0% carbon nanotubes, and the rest is nickel hydroxide.

5. The carbon fiber reinforced 3D printing wire according to claim 2, characterized in that: The weight percentage is: 14.9% short carbon fiber, 20.1% continuous carbon fiber, 2.0% composite treatment agent, and the rest is thermoplastic resin; the raw materials of the composite treatment agent are calculated as follows: 8.9% urea, 5.4% dopamine hydrochloride, 36.0% carbon nanotubes, and the rest nickel hydroxide.

6. The carbon fiber reinforced 3D printing wire according to claim 1, characterized in that: The thermoplastic resin is one or a combination of polyamide, polyetheretherketone, polyphenylene sulfide, polyimide and polyetherimide.

7. A method for preparing a carbon fiber reinforced 3D printing wire, characterized in that: The specific preparation steps are as follows: Step 1: weigh short carbon fibers, continuous carbon fibers, thermoplastic resins in the raw materials, and urea, dopamine hydrochloride, carbon nanotubes, and nickel hydroxide in the composite treatment agent raw materials; Step 2: adding carbon nanotubes to a strong acid, subjecting them to water bath ultrasonic treatment for 7 to 8 hours, centrifugation filtering, washing to neutrality, and drying to obtain modified carbon nanotubes; Step 3: Add nickel hydroxide to deionized water, perform ultrasonic treatment for 10 to 20 minutes, add short carbon fiber, perform ultrasonic treatment for another 10 to 20 minutes, then add urea, perform water bath ultrasonic treatment for 3 to 5 hours, wash and dry to obtain a mixture A; Step 4: adding the modified carbon nanotubes and dopamine hydrochloride to deionized water, ultrasonically treating for 10 to 20 minutes, adding mixed material A, adjusting the pH to 7.2 to 7.8, ultrasonically treating for 1 to 2 hours, washing and drying to obtain mixed material B; Step 5: Adding mixed material B to the thermoplastic resin, heating and melting it, and then stirring it for 1 to 2 hours to obtain modified material C; Step 6: The modified material C is used as a matrix and the continuous carbon fiber is used as a fiber. The modified material C is fed into the fiber-matrix mixing module for mixing, and the mixed materials are fully mixed under the action of a heating block to form synchronously reinforced composite yarns. Then, after being squeezed by the rollers in the roller impregnation module, the synchronously reinforced composite filament enters the wire shaping module, and under the shaping action of the wire shaping module, a carbon fiber reinforced 3D printing wire is formed; finally, through the dragging action of the winding module, the carbon fiber reinforced 3D printing wire is collected on the wire winding drum at a uniform speed.

8. The method for preparing a carbon fiber reinforced 3D printing wire according to claim 7, characterized in that: In step one, short carbon fibers and continuous carbon fibers are put into deionized water for water bath ultrasonic cleaning for 20 to 40 minutes, the water bath temperature is 50 to 60° C., the ultrasonic frequency is 1.5 to 1.7 MHz, and the ultrasonic power is 400 to 600 W; in step two, the strong acid is one or a combination of nitric acid and concentrated sulfuric acid, the weight ratio of carbon nanotubes to strong acid is 1:40 to 60, the water bath temperature is 70 to 80° C., the ultrasonic frequency is 60 to 80 KHz, and the ultrasonic power is 400 to 600 W; the deionized water is used for repeated washing until the washing liquid is neutral, and then the drying is carried out at 70 to 80° C.

9. The method for preparing a carbon fiber reinforced 3D printing wire according to claim 8, characterized in that: In step three, the weight ratio of nickel hydroxide to deionized water is 1:90-110, the ultrasonic frequency is 1.5-1.7 MHz, the ultrasonic power is 400-600 W, the water bath temperature is 50-60° C., and the cleaning treatment is performed with deionized water; in step four, the weight ratio of the total weight of the modified carbon nanotubes and dopamine hydrochloride to deionized water is 1:90-100, the ultrasonic frequency is 1.5-1.7 MHz, and the ultrasonic power is 400-600 W; and dilute hydrochloric acid is used to adjust the pH value.

10. The method for preparing a carbon fiber reinforced 3D printing wire according to claim 9, characterized in that: In step five, the mixing speed is 300-600 r / min; in step six, the wire making speed is 110-130 cm / min, and the diameter of the shaping die in the wire shaping module is selected to be 0.7-0.9 mm.

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