Composite resin material for 3D printing and preparation method thereof

Abstract

This invention relates to a composite resin material for 3D printing and its preparation method. By weight, the raw material composition includes: 60-90 parts polylactic acid, 5-15 parts toughening agent, 5-15 parts flame retardant, 5-10 parts modified carbon nanotubes, 0.3-1 parts anti-hydrolysis agent, and 0.3-0.5 parts lubricant. This invention adds a flame retardant by introducing a phosphate ester structure, a benzene ring, and a hindered phenolic structure into 5,5'-dibromo-[2,2'-bipyridine]-3,3'-diamine. Through the multiple synergistic effects of hindered phenol-phosphorus heterocycle-bipyridine, highly efficient flame retardancy and enhanced anti-aging properties of the composite resin material are achieved. This invention adds modified carbon nanotubes as a reinforcing agent, significantly improving the mechanical properties of the composite resin material and imparting antibacterial properties.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a composite resin material for 3D printing and its preparation method. Background Technology

[0002] 3D printing is a technology that uses digital model files as a basis and employs powdered metals or plastics and other bondable materials to construct objects by stacking layers one by one. Compared with traditional injection molding and compression molding, this technology has advantages such as fast forming speed, high precision, and high material utilization, and has received widespread attention in recent years. Currently, mainstream 3D printing technologies include stereolithography (SLA), layered solid fabrication (LOM), selective laser sintering (SLS), and fused deposition modeling (FDM). Among these, FDM has become one of the most widely used 3D printing technologies due to its simple operation, low material cost, high reliability, and clean working environment.

[0003] In FDM 3D printing technology research, commonly used materials encompass a variety of polymers and their composites, with polylactic acid (PLA) being the most widely used. PLA is a biodegradable polymer material that not only possesses good biocompatibility and excellent mechanical properties but also boasts advantages such as low elongation at break, low coefficient of thermal expansion, and ease of processing and molding. Therefore, PLA is considered an ideal material for FDM 3D printing. However, PLA also has some drawbacks, such as low impact strength, high brittleness, poor aging resistance, and flammability. Furthermore, due to its biodegradable nature, it is more susceptible to bacterial and fungal attack. Therefore, research on PLA modification is particularly important in addressing these issues. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, one of the objectives of the present invention is to provide a composite resin material for 3D printing.

[0005] The second objective of this invention is to provide a method for preparing composite resin materials for 3D printing.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] This invention provides a composite resin material for 3D printing. By weight, the raw material composition of the composite resin material for 3D printing includes: 60-90 parts of polylactic acid, 5-15 parts of toughening agent, 5-15 parts of flame retardant, 5-10 parts of modified carbon nanotubes, 0.3-1 parts of anti-hydrolysis agent, and 0.3-0.5 parts of lubricant.

[0008] Preferably, the chemical structural formula of the flame retardant is as follows:

[0009] Preferably, the preparation process of the flame retardant is as follows:

[0010] (1-1) Under nitrogen protection, 5,5'-dibromo-[2,2'-bipyridine]-3,3'-diamine and triethylamine were added to dichloromethane A and dissolved completely. Then, dichloromethane B containing 5,5-dimethyl-2-chloro-1,3,2-dioxophosphorylcaprolactone phosphate was added dropwise at 0°C. After the reaction, the mixture was distilled under reduced pressure, washed and dried to obtain intermediate 1.

[0011] (1-2) Under nitrogen protection, intermediate 1, tert-butylhydroquinone and potassium carbonate are dissolved in N,N-dimethylformamide. After the reaction, the mixture is distilled under reduced pressure, washed and dried to obtain the final product.

[0012] Preferably, in step (1-1), the ratio of 5,5'-dibromo-[2,2'-bipyridine]-3,3'-diamine, 5,5-dimethyl-2-chloro-1,3,2-dioxophosphorylcaprolactone phosphate, triethylamine, and dichloromethane A is 0.05 mol: 0.1-0.12 mol: 0.1-0.12 mol: 200-250 mL; the concentration of 5,5-dimethyl-2-chloro-1,3,2-dioxophosphorylcaprolactone phosphate in dichloromethane B is 1.5-2 mol / L; and the reaction temperature is 25-30 °C and the reaction time is 10-15 h.

[0013] Preferably, in steps (1-2), the ratio of intermediate 1, tert-butylhydroquinone, potassium carbonate, and N,N-dimethylformamide is 2 mmol: 4-4.5 mmol: 5-6 mmol: 25-30 mL; the reaction conditions are 12-18 h at room temperature.

[0014] This invention adds a flame retardant to a composite resin material for 3D printing, thereby improving the flame retardant performance and anti-aging ability of the composite resin material. The flame retardant principle is as follows: the thermal decomposition of the phosphate ester structure not only catalyzes the formation of a dense carbon layer on the material surface but also releases phosphorus-containing free radicals (PO·, etc.) to quench active free radicals (H· / OH·) in the ignition source; the benzene ring, as a carbon-rich unit, synergistically promotes the formation of a graphitized carbon layer with the phosphate ester, further enhancing the density and thermal stability of the carbon layer; the nitrogen and other non-flammable gases released by the decomposition of the bipyridine skeleton dilute the concentration of combustible gases. This multi-element synergistic system of phosphorus-nitrogen-aromatic rings blocks the combustion chain reaction through a dual flame retardant mechanism in both the condensed and gas phases, achieving highly efficient flame retardancy.

[0015] Anti-aging properties: The hindered phenolic structure inhibits oxidative degradation of the material by efficiently capturing free radicals; the bipyridine conjugated rigid framework not only absorbs ultraviolet light but also reduces structural dissociation at high temperatures by inhibiting molecular thermal motion, while stabilizing free radical intermediates and synergistically enhancing molecular thermal stability with the phosphorus heterocyclic structure; the phosphorus heterocyclic structure can further inhibit the oxidation process by decomposing peroxides. This multiple synergistic effect of hindered phenol-phosphorus heterocyclic-bipyridine not only provides immediate free radical capture capability but also enhances the durability of the anti-aging effect through the phosphorus-nitrogen synergistic effect, significantly improving the anti-aging performance of the material.

[0016] Preferably, the preparation process of the modified carbon nanotubes is as follows:

[0017] (2-1) Amino carbon nanotubes were ultrasonically dispersed in N,N-dimethylformamide, and 2-(methyl-prop-2-ylamino)acetic acid, 1,4-dioxane and p-toluenesulfonic acid were added. After the reaction, the mixture was filtered, washed and dried to obtain intermediate 2.

[0018] (2-2) Under nitrogen protection, intermediate 2 was ultrasonically dispersed in N,N-dimethylformamide, and chloropropyltriethoxysilane and potassium iodide were added. After the reaction, the mixture was filtered, washed and dried to obtain the final product.

[0019] Preferably, in step (2-1), the ratio of amino carbon nanotubes, 2-(methyl-prop-2-ylamino)acetic acid, p-toluenesulfonic acid, N,N-dimethylformamide, and 1,4-dioxane is 1g:2-4g:0.05-0.2g:40-50mL:15-30mL; the reaction temperature is 90-100℃ and the time is 24-48h.

[0020] Preferably, in step (2-2), the ratio of intermediate 2, chloropropyltriethoxysilane, potassium iodide and N,N-dimethylformamide is 0.5g:1.8-3.6g:0.05-0.2g:40-65mL; ​​the reaction temperature is 150-160℃ and the time is 15-20h.

[0021] Preferably, the melt index of the polylactic acid is 5-25 g / 10 min at 190°C and 2.16 kg; the toughening agent is polybutylene succinate; the anti-hydrolysis agent is monomeric carbodiimide; and the lubricant is at least one of ethylene bis-stearamide, pentaerythritol stearate, and oleamide.

[0022] This invention provides a method for preparing the composite resin material for 3D printing, comprising the following steps: mixing polylactic acid, toughening agent, flame retardant, modified carbon nanotubes, anti-hydrolysis agent and lubricant evenly, followed by melt extrusion and granulation to obtain the final product.

[0023] Preferably, the temperature of the melt extrusion is 150-200°C.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention provides a polylactic acid-based composite resin material for 3D printing, in which modified carbon nanotubes are added as a reinforcing agent, significantly improving the mechanical properties of the composite resin material and endowing it with antibacterial properties. In the preparation of the modified carbon nanotubes, this invention first introduces tertiary amino groups by reacting amino carbon nanotubes with 2-(methyl-prop-2-ylamino)acetic acid, and then further reacts them with chloropropyltriethoxysilane to successfully prepare modified carbon nanotubes containing both quaternary ammonium salt groups and siloxane structures. The quaternary ammonium salt groups endow the material with excellent antibacterial properties, while the siloxane structure not only significantly improves the dispersibility of carbon nanotubes in the polylactic acid matrix, but also, through enhanced interfacial interactions, produces a synergistic reinforcing effect with the inherent high strength properties of carbon nanotubes, improving the tensile strength and impact strength of the material.

[0026] This invention adds a flame retardant to polylactic acid-based composite resin materials for 3D printing, which not only significantly improves the flame retardant properties of the composite resin material but also effectively enhances its anti-aging ability. In the preparation of the flame retardant, this invention first introduces a phosphate ester structure by substituting the amino group of 5,5-dimethyl-2-chloro-1,3,2-dioxophosphoryl caprolactone phosphate with that of 5,5'-dibromo-[2,2'-bipyridine]-3,3'-diamine. Further, a substitution reaction is conducted between the bromine atom on 5,5'-dibromo-[2,2'-bipyridine]-3,3'-diamine and tert-butylhydroquinone, introducing a benzene ring and a hindered phenolic structure. On the one hand, the introduction of the phosphate ester structure and the benzene ring enhances the flame retardant effect; on the other hand, the introduction of the hindered phenolic structure improves the material's anti-aging properties.

[0027] This invention provides a method for preparing composite resin materials for 3D printing. The preparation process is simple to operate and suitable for industrial production and application. Attached Figure Description

[0028] Figure 1 The infrared spectra of the modified carbon nanotubes and amino carbon nanotubes in Example 1 of this invention are shown. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments shall be performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0030] Example 1

[0031] This embodiment provides a composite resin material for 3D printing. By weight, the raw material composition of the composite resin material for 3D printing includes: 75 parts of polylactic acid (NatureWorks 3001D, melt index of 20g / 10min at 190℃ and 2.16kg), 10 parts of toughening agent (polybutylene succinate, Showa Denko 3001MD), 10 parts of flame retardant, 8 parts of modified carbon nanotubes, 0.6 parts of anti-hydrolysis agent (monomer carbodiimide, HyMax 1010), and 0.4 parts of lubricant (oleamide).

[0032] The preparation process of the flame retardant in this embodiment is as follows:

[0033]

[0034] (1-1) Under nitrogen protection, 5,5'-dibromo-[2,2'-bipyridine]-3,3'-diamine and triethylamine were dissolved completely in dichloromethane A. Then, dichloromethane B containing 5,5-dimethyl-2-chloro-1,3,2-dioxophosphorylcaprolactone phosphate was added dropwise at 0°C. The dichloromethane B contained 5,5'-dibromo-[2,2'-bipyridine]-3,3'-diamine, 5,5-dimethyl-2-chloro-1,3,2-dioxophosphorylcaprolactone phosphate, and triethylamine were dissolved in the dichloromethane A. The molar ratio of ethylamine to dichloromethane A was 0.05 mol: 0.11 mol: 0.11 mol: 230 mL; the concentration of 5,5-dimethyl-2-chloro-1,3,2-dioxophosphoryl caprolactone phosphate in dichloromethane B was 1.8 mol / L; after reacting at 30 °C for 12 h, the solvent was removed by vacuum distillation, and the product was washed successively with distilled water, toluene, and anhydrous ethanol, and then dried under vacuum to obtain intermediate 1 (yield 88.6%); the obtained intermediate 1... 1 HNMR: (C 20 H 26 N4O6P2Br2, 400MHz, DMSO-d6) δ: 0.89 (s, 12H), 3.88-3.90 (d, 8H), 5.45 (s, 2H), 7.60 (s, 2H), 8.16 (s, 2H). MS(ESI)m / z=639.97[M].

[0035] (1-2) Under nitrogen protection, intermediate 1, tert-butylhydroquinone, and potassium carbonate were dissolved in N,N-dimethylformamide, wherein the molar ratio of intermediate 1, tert-butylhydroquinone, potassium carbonate, and N,N-dimethylformamide was 2 mmol:4.2 mmol:5.5 mmol:28 mL. After reacting at room temperature for 16 h, the reaction was quenched with 6 mol / L hydrochloric acid, and the filtrate was filtered. The pH of the filtrate was adjusted to neutral, the solvent was removed by vacuum distillation, and the filtrate was washed with distilled water and ethyl acetate, and then dried under vacuum to obtain the flame retardant (yield 83.6%). The obtained flame retardant... 1 HNMR: (C 40 H 52 N4O 10 P2, 400MHz, DMSO-d6) δ: 0.89 (s, 12H), 1.40 (s, 18H), 3.88-3.90 (d, 8H), 5.45 (s, 2H), 6. 54-6.58 (d, 2H), 6.68 (s, 2H), 6.74-6.78 (d, 2H), 6.80 (s, 2H), 7.83 (s, 2H), 9.68 (s, 2H). MS(ESI)m / z=810.32[M].

[0036] The preparation process of the modified carbon nanotubes in this embodiment is as follows:

[0037]

[0038] (2-1) Aminocarbon nanotubes were ultrasonically dispersed in N,N-dimethylformamide, and 2-(methyl-prop-2-ylamino)acetic acid, 1,4-dioxane, and p-toluenesulfonic acid were added. The ratio of aminocarbon nanotubes, 2-(methyl-prop-2-ylamino)acetic acid, p-toluenesulfonic acid, N,N-dimethylformamide, and 1,4-dioxane was 1 g: 3 g: 0.1 g: 45 mL: 20 mL. After reacting at 100 °C for 36 h, the mixture was filtered, washed with deionized water and acetone, and dried under vacuum to obtain intermediate 2.

[0039] (2-2) Under nitrogen protection, intermediate 2 was ultrasonically dispersed in N,N-dimethylformamide, and chloropropyltriethoxysilane and potassium iodide were added. The ratio of intermediate 2, chloropropyltriethoxysilane, potassium iodide, and N,N-dimethylformamide was 0.5 g: 2.7 g: 0.1 g: 55 mL. After reflux reaction at 160 °C for 18 h, the mixture was filtered, washed with deionized water and acetone, and vacuum dried to obtain modified carbon nanotubes. The infrared spectrum of the obtained modified carbon nanotubes is shown below. Figure 1 As shown. By Figure 1 It can be seen that the modified carbon nanotubes at 1748 cm⁻¹... -1 1176cm -1 1045cm -1The presence of characteristic peaks for C=O, Si-O, and Si-C in the vicinity indicates that the carbon nanotube modification was successful.

[0040] The preparation method of the composite resin material for 3D printing in this embodiment includes the following steps: polylactic acid, toughening agent, flame retardant, modified carbon nanotubes, anti-hydrolysis agent and lubricant are added to a high-speed mixer and mixed evenly, then added to a twin-screw extruder, melt-extruded at 180°C and granulated to obtain the final product.

[0041] Example 2

[0042] This embodiment provides a composite resin material for 3D printing. By weight, the raw material composition of the composite resin material for 3D printing includes: 90 parts of polylactic acid (NatureWorks 3001D), 15 parts of toughening agent (polybutylene succinate, Showa Denko 3001MD), 15 parts of flame retardant, 10 parts of modified carbon nanotubes, 1 part of anti-hydrolysis agent (monomer carbodiimide, HyMax1010), and 0.5 parts of lubricant (pentaerythritol stearate).

[0043] The preparation process of the flame retardant in this embodiment is as follows:

[0044] (1-1) Under nitrogen protection, 5,5'-dibromo-[2,2'-bipyridine]-3,3'-diamine and triethylamine were dissolved completely in dichloromethane A. Then, dichloromethane B containing 5,5-dimethyl-2-chloro-1,3,2-dioxophosphorylcaprolactone phosphate was added dropwise at 0°C. The dichloromethane B contained 5,5'-dibromo-[2,2'-bipyridine]-3,3'-diamine, 5,5-dimethyl-2-chloro-1,3,2-dioxophosphorylcaprolactone phosphate, and triethylamine were added dropwise. The ratio of triethylamine to dichloromethane A was 0.05 mol: 0.12 mol: 0.12 mol: 250 mL; the concentration of 5,5-dimethyl-2-chloro-1,3,2-dioxophosphorylcaprolactone phosphate in dichloromethane B was 2 mol / L; after reacting at 30 °C for 10 h, the solvent was removed by vacuum distillation, and the mixture was washed successively with distilled water, toluene, and anhydrous ethanol, and then dried under vacuum to obtain intermediate 1 (yield 87.9%); the obtained intermediate 1... 1 HNMR is the same as in Example 1.

[0045] (1-2) Under nitrogen protection, intermediate 1, tert-butylhydroquinone, and potassium carbonate were dissolved in N,N-dimethylformamide, wherein the molar ratio of intermediate 1, tert-butylhydroquinone, potassium carbonate, and N,N-dimethylformamide was 2 mmol:4.5 mmol:6 mmol:30 mL. After reacting at room temperature for 18 h, the reaction was quenched with 6 mol / L hydrochloric acid, and the filtrate was filtered. The pH of the filtrate was adjusted to neutral, the solvent was removed by vacuum distillation, and the filtrate was washed with distilled water and ethyl acetate, and then dried under vacuum to obtain a flame retardant (yield 83.1%).1 HNMR is the same as in Example 1.

[0046] The preparation process of the modified carbon nanotubes in this embodiment is as follows:

[0047] (2-1) Aminocarbon nanotubes were ultrasonically dispersed in N,N-dimethylformamide, and 2-(methyl-prop-2-ylamino)acetic acid, 1,4-dioxane, and p-toluenesulfonic acid were added. The ratio of aminocarbon nanotubes, 2-(methyl-prop-2-ylamino)acetic acid, p-toluenesulfonic acid, N,N-dimethylformamide, and 1,4-dioxane was 1 g: 4 g: 0.2 g: 50 mL: 30 mL. After reacting at 100 °C for 24 h, the mixture was filtered, washed with deionized water and acetone, and dried under vacuum to obtain intermediate 2.

[0048] (2-2) Under nitrogen protection, intermediate 2 was ultrasonically dispersed in N,N-dimethylformamide, and chloropropyltriethoxysilane and potassium iodide were added. The ratio of intermediate 2, chloropropyltriethoxysilane, potassium iodide and N,N-dimethylformamide was 0.5 g: 3.6 g: 0.2 g: 65 mL. After reflux reaction at 160 °C for 15 h, the mixture was filtered, washed with deionized water and acetone, and vacuum dried to obtain modified carbon nanotubes.

[0049] The preparation method of the composite resin material for 3D printing in this embodiment includes the following steps: polylactic acid, toughening agent, flame retardant, modified carbon nanotubes, anti-hydrolysis agent and lubricant are added to a high-speed mixer and mixed evenly, then added to a twin-screw extruder, melt-extruded at 200°C and granulated to obtain the final product.

[0050] Example 3

[0051] This embodiment provides a composite resin material for 3D printing. By weight, the raw material composition of the composite resin material for 3D printing includes: 60 parts of polylactic acid (NatureWorks 3001D), 5 parts of toughening agent (polybutylene succinate, Showa Denko 3001MD), 5 parts of flame retardant, 5 parts of modified carbon nanotubes, 0.3 parts of anti-hydrolysis agent (monomer carbodiimide, HyMax1010), and 0.3 parts of lubricant (ethylene bis-stearamide).

[0052] The preparation process of the flame retardant in this embodiment is as follows:

[0053] (1-1) Under nitrogen protection, 5,5'-dibromo-[2,2'-bipyridine]-3,3'-diamine and triethylamine were dissolved completely in dichloromethane A. Then, dichloromethane B containing 5,5-dimethyl-2-chloro-1,3,2-dioxophosphorylcaprolactone phosphate was added dropwise at 0°C. The dichloromethane B contained 5,5'-dibromo-[2,2'-bipyridine]-3,3'-diamine, 5,5-dimethyl-2-chloro-1,3,2-dioxophosphorylcaprolactone phosphate, and triethylamine were added dropwise. The ratio of triethylamine to dichloromethane A was 0.05 mol: 0.1 mol: 0.1 mol: 200 mL; the concentration of 5,5-dimethyl-2-chloro-1,3,2-dioxophosphoryl caprolactone phosphate in dichloromethane B was 1.5 mol / L; after reacting at 25 °C for 15 h, the solvent was removed by vacuum distillation, and the product was washed successively with distilled water, toluene, and anhydrous ethanol, and then dried under vacuum to obtain intermediate 1 (yield 87.4%); the obtained intermediate 1... 1 HNMR is the same as in Example 1.

[0054] (1-2) Under nitrogen protection, intermediate 1, tert-butylhydroquinone, and potassium carbonate were dissolved in N,N-dimethylformamide, wherein the molar ratio of intermediate 1, tert-butylhydroquinone, potassium carbonate, and N,N-dimethylformamide was 2 mmol:4 mmol:5 mmol:25 mL. After reacting at room temperature for 12 h, the reaction was quenched with 6 mol / L hydrochloric acid, and the filtrate was filtered. The pH of the filtrate was adjusted to neutral, the solvent was removed by vacuum distillation, and the filtrate was washed with distilled water and ethyl acetate, and then dried under vacuum to obtain a flame retardant (yield 82.3%). 1 HNMR is the same as in Example 1.

[0055] The preparation process of the modified carbon nanotubes in this embodiment is as follows:

[0056] (2-1) Aminocarbon nanotubes were ultrasonically dispersed in N,N-dimethylformamide, and 2-(methyl-prop-2-ylamino)acetic acid, 1,4-dioxane, and p-toluenesulfonic acid were added. The ratio of aminocarbon nanotubes, 2-(methyl-prop-2-ylamino)acetic acid, p-toluenesulfonic acid, N,N-dimethylformamide, and 1,4-dioxane was 1 g: 2 g: 0.05 g: 40 mL: 15 mL. After reacting at 90 °C for 48 h, the mixture was filtered, washed with deionized water and acetone, and dried under vacuum to obtain intermediate 2.

[0057] (2-2) Under nitrogen protection, intermediate 2 was ultrasonically dispersed in N,N-dimethylformamide, and chloropropyltriethoxysilane and potassium iodide were added. The ratio of intermediate 2, chloropropyltriethoxysilane, potassium iodide and N,N-dimethylformamide was 0.5 g: 1.8 g: 0.05 g: 40 mL. After reflux reaction at 150 °C for 20 h, the mixture was filtered, washed with deionized water and acetone, and vacuum dried to obtain modified carbon nanotubes.

[0058] The preparation method of the composite resin material for 3D printing in this embodiment includes the following steps: polylactic acid, toughening agent, flame retardant, modified carbon nanotubes, anti-hydrolysis agent and lubricant are added to a high-speed mixer and mixed evenly, then added to a twin-screw extruder, melt-extruded at 150°C and granulated to obtain the final product.

[0059] Comparative Example 1

[0060] The difference between this comparative example and Example 1 is that the flame retardant is replaced with a direct mixture of 5,5-dimethyl-2-chloro-1,3,2-dioxophosphoryl caprolactone phosphate and tert-butylhydroquinone, with the same dosage relationship as in Example 1.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 1 is that the modified carbon nanotubes are replaced with amino carbon nanotubes.

[0063] Test case

[0064] The composite resin materials for 3D printing obtained in Examples 1-3 and Comparative Examples 1-2 were printed into test strips using a 3D printer, and the following performance tests were conducted. The results are shown in Table 1.

[0065] 1. The tensile strength was tested according to GB / T1040.1-2018 "Determination of tensile properties of plastics".

[0066] 2. The notched impact strength was tested according to GB / T1843-2008 "Determination of Impact Strength of Plastic Cantilever Beams".

[0067] 3. Aging resistance: at 0.55W / m 2 After irradiation for 1000 hours under ultraviolet light conditions of 340 nm and 60 nm, the tensile strength and notched impact strength were measured, and the retention rate of tensile strength and notched impact strength after aging was calculated.

[0068] 4. The limiting oxygen index was tested according to GB / T2406.1-2008 "Determination of Combustion Behavior by Oxygen Index Method for Plastics".

[0069] 5. According to GB / T23763-2009 "Evaluation of the antibacterial properties of photocatalytic antibacterial materials and products", the antibacterial rate was determined using Escherichia coli and Staphylococcus aureus as bacterial strains.

[0070] Table 1

[0071] Group Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Tensile strength (MPa) 69.4 67.6 64.3 61.8 54.2 <![CDATA[Notched impact strength (KJ / m 2 )]]> 16.7 15.3 14.8 12.5 8.6 Tensile strength after aging (MPa) 60.5 58.7 55.4 42.6 44.3 <![CDATA[Notched Izod impact strength after aging (KJ / m 2 )]]> 15.8 14.2 13.7 9.4 7.3 Tensile strength retention rate (%) 87.2 86.8 86.2 68.9 81.7 Notched impact strength retention rate (%) 94.6 92.8 92.6 75.2 84.9 Limiting oxygen index (%) 33.9 33.7 33.4 22.5 30.6 Antibacterial (E. coli) rate (%) 99.3 98.6 98.4 96.7 90.5 Antibacterial (Staphylococcus aureus) rate (%) 98.4 97.7 97.5 95.3 90.2

[0072] As shown in Table 1, the composite resin materials for 3D printing obtained in Examples 1-3 of this invention exhibit better mechanical properties, flame retardancy, anti-aging properties, and antibacterial properties compared to Comparative Examples 1-2. Specifically, this invention adds modified carbon nanotubes as a reinforcing agent, and simultaneously contains quaternary ammonium salt groups and siloxane structures, significantly improving the mechanical properties of the composite resin materials and endowing them with antibacterial properties. The quaternary ammonium salt groups impart excellent antibacterial properties to the material, while the siloxane structure not only improves the dispersion of carbon nanotubes in the polylactic acid matrix, but also, through strengthening interfacial interactions, produces a synergistic reinforcing effect with the inherent high strength characteristics of carbon nanotubes, improving the tensile strength and impact strength of the material. This invention adds a flame retardant by introducing a phosphate ester structure, a benzene ring, and a hindered phenolic structure into 5,5'-dibromo-[2,2'-bipyridine]-3,3'-diamine. On the one hand, the introduction of the phosphate ester structure and the benzene ring enhances the flame retardant effect; on the other hand, the introduction of the hindered phenolic structure improves the anti-aging properties of the material. Simultaneously, the nitrogen and other non-flammable gases released from the decomposition of the bipyridine skeleton dilute the concentration of combustible gases. This multi-element synergistic system of phosphorus-nitrogen-aromatic rings blocks the combustion chain reaction through a dual flame-retardant mechanism in both the condensed and gas phases, achieving highly efficient flame retardancy. Furthermore, the multiple synergistic effects of hindered phenol-phosphorus heterocycles-bipyridine provide immediate free radical scavenging capabilities, enhancing the durability of the anti-aging effect through the phosphorus-nitrogen synergistic effect, and significantly improving the anti-aging performance of the composite resin material.

[0073] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A composite resin material for 3D printing, characterized by, The raw material composition of the composite resin material for 3D printing, by weight, includes: 60-90 parts polylactic acid, 5-15 parts toughening agent, 5-15 parts flame retardant, 5-10 parts modified carbon nanotubes, 0.3-1 part anti-hydrolysis agent, and 0.3-0.5 parts lubricant. The preparation process of the modified carbon nanotubes is as follows: (2-1) Amino carbon nanotubes were ultrasonically dispersed in N,N-dimethylformamide, and 2-(methyl-prop-2-ylamino)acetic acid, 1,4-dioxane and p-toluenesulfonic acid were added. After the reaction, the mixture was filtered, washed and dried to obtain intermediate 2. (2-2) Under nitrogen protection, intermediate 2 was ultrasonically dispersed in N,N-dimethylformamide, and chloropropyltriethoxysilane and potassium iodide were added. After the reaction, the mixture was filtered, washed and dried to obtain the final product. The chemical structural formula of the flame retardant is .

2. The composite resin material for 3D printing according to claim 1, characterized by, The preparation process of the flame retardant is as follows: (1-1) Under nitrogen protection, 5,5'-dibromo-[2,2'-bipyridine]-3,3'-diamine and triethylamine were added to dichloromethane A and dissolved completely. Then, dichloromethane B containing 5,5-dimethyl-2-chloro-1,3,2-dioxophosphorylcaprolactone phosphate was added dropwise at 0°C. After the reaction, the mixture was distilled under reduced pressure, washed and dried to obtain intermediate 1. (1-2) Under nitrogen protection, intermediate 1, tert-butylhydroquinone and potassium carbonate are dissolved in N,N-dimethylformamide. After the reaction, the mixture is distilled under reduced pressure, washed and dried to obtain the final product.

3. The composite resin material for 3D printing according to claim 2, characterized by, In step (1-1), the ratio of 5,5'-dibromo-[2,2'-bipyridine]-3,3'-diamine, 5,5-dimethyl-2-chloro-1,3,2-dioxophosphorylcaprolactone phosphate, triethylamine, and dichloromethane A is 0.05 mol: 0.1-0.12 mol: 0.1-0.12 mol: 200-250 mL; the concentration of 5,5-dimethyl-2-chloro-1,3,2-dioxophosphorylcaprolactone phosphate in dichloromethane B is 1.5-2 mol / L; the reaction temperature is 25-30 °C, and the time is 10-15 h.

4. The composite resin material for 3D printing according to claim 2, wherein In steps (1-2), the ratio of intermediate 1, tert-butylhydroquinone, potassium carbonate, and N,N-dimethylformamide is 2 mmol: 4-4.5 mmol: 5-6 mmol: 25-30 mL; the reaction conditions are 12-18 h at room temperature.

5. The composite resin material for 3D printing according to claim 1, wherein In step (2-1), the ratio of amino carbon nanotubes, 2-(methyl-prop-2-ylamino)acetic acid, p-toluenesulfonic acid, N,N-dimethylformamide and 1,4-dioxane is 1g:2-4g:0.05-0.2g:40-50mL:15-30mL; the reaction temperature is 90-100℃ and the time is 24-48h.

6. The composite resin material for 3D printing according to claim 1, wherein In step (2-2), the ratio of intermediate 2, chloropropyltriethoxysilane, potassium iodide and N,N-dimethylformamide is 0.5g:1.8-3.6g:0.05-0.2g:40-65mL; ​​the reaction temperature is 150-160℃ and the time is 15-20h.

7. The composite resin material for 3D printing according to claim 1, wherein The melt index of the polylactic acid is 5-25 g / 10 min at 190°C and 2.16 kg; the toughening agent is polybutylene succinate; the anti-hydrolysis agent is monomeric carbodiimide; and the lubricant is at least one of ethylene bis-stearamide, pentaerythritol stearate, and oleamide.

8. The method of claim 1-7, wherein, The process includes the following steps: mixing polylactic acid, toughening agent, flame retardant, modified carbon nanotubes, anti-hydrolysis agent and lubricant evenly, then melting and extruding at 150-200℃ and granulating to obtain the final product.

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