Additive manufacturing method of nano-reinforced hybrid photosensitive resin-based composite material

Abstract

The invention discloses an additive manufacturing method of a nano-reinforced hybrid photosensitive resin-based composite material, which comprises the following steps: firstly, carrying out mixed acid hydroxylation activation on BNNTs, and introducing hydroxyl and vacancy active sites; then, in an H3PO4 / ZrOCl2. 8H2O system, ZrP nanosheets are uniformly grown on the outer wall of the BNNTs through an in-situ hydrothermal method, and the high-dispersion ZrP-BNNTs are obtained. Adding the obtained nano material into tripropylene glycol diacrylate serving as a diluent for pre-dispersion, then mixing with an epoxy acrylate / polyurethane acrylate hybrid photosensitive prepolymer and phenyl bis (2, 4, 6-trimethylbenzoyl) phosphine oxide serving as a photoinitiator, and then adding a photoinitiator, so as to obtain a photoinitiator; and carrying out photocuring three-dimensional forming to prepare the nano-reinforced hybrid photosensitive resin-based composite material. The obtained composite material has the characteristics of light weight, high strength and high wear resistance, and is suitable for rapid manufacturing of high-precision structural parts, friction wear parts and functional customized parts.

Description

Technical Field

[0001] The present invention belongs to the field of in-situ construction of nano-functional fillers, modification of photosensitive resins and light-curing additive manufacturing, and specifically relates to an additive manufacturing method for nano-reinforced hybrid photosensitive resin-based composite materials. Background Art

[0002] With the continued expansion of additive manufacturing (3D printing) technology in high-end fields such as aerospace, precision manufacturing, and medical devices, photocurable resin-based composites have attracted widespread attention due to their high molding precision, excellent surface quality, and high processing efficiency. However, existing photosensitive resins still have significant deficiencies in mechanical properties and wear resistance, making it difficult to meet the comprehensive strength, stiffness, and durability requirements of high-end applications.

[0003] To improve the mechanical strength and wear resistance of resin matrices, researchers have attempted to introduce various nanofillers, such as carbon nanotubes, SiO2, TiO2, and graphene. Boron nitride nanotubes (BNNTs) are considered one of the most promising reinforcing phases due to their excellent mechanical properties, thermal stability, and electrical insulation properties. However, BNNTs have a smooth surface and are prone to agglomeration, making them difficult to disperse in the resin matrix. Furthermore, their interfacial bonding with organic polymers is weak, severely limiting their reinforcing effectiveness. While traditional surface modification methods, such as acid oxidation and grafting, can improve the dispersibility and interfacial compatibility of BNNTs to a certain extent, achieving highly uniform distribution of fillers within the matrix and strong interfacial bonding remains difficult.

[0004] Layered zirconium phosphate (ZrP) nanosheets have excellent thermal stability, interlayer slip properties, and wear resistance. Currently, research on in-situ synthesized ZrP-BNNTs composite nanomaterials, incorporating them into photosensitive resins for use in photocurable 3D printing, is still lacking.

[0005] Therefore, how to ensure the high dispersibility and interfacial active sites of ZrP-BNNTs while achieving efficient photocuring molding of the epoxy acrylate / polyurethane acrylate matrix in the formula and obtaining excellent mechanical, wear resistance and additive manufacturing properties is a key technical problem that needs to be solved urgently in this field. Summary of the Invention

[0006] The purpose of this section is to summarize some aspects of embodiments of the present invention and to briefly introduce some preferred embodiments.

[0007] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0008] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for additive manufacturing of nano-reinforced hybrid photosensitive resin-based composite materials.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for additive manufacturing of nano-reinforced hybrid photosensitive resin-based composite materials, comprising: Boron nitride nanotubes (BNNTs) are subjected to hydroxylation modification to obtain BNNTs-OH powder; BNNTs-OH powder is added to polyvinyl pyrrolidone and dispersed evenly to obtain a BNNTs-OH dispersion; A BNNTs-OH dispersion is mixed with phosphoric acid and zirconium oxychloride octahydrate to obtain a mixed system, and zirconium phosphate (ZrP) nanosheets are in situ grown on the surface of the BNNTs by an in situ hydrothermal method to obtain a ZrP-BNNTs nanomaterial mixed suspension, which is then centrifuged, washed, and dried to obtain ZrP-BNNTs powder. After the ZrP-BNNTs powder and the diluent are evenly mixed, a photosensitive prepolymer and a photoinitiator are added, and the mixture is stirred at a temperature of 4 to 8 hours. After the reaction is completed, the mixture is naturally cooled to obtain a nano-enhanced hybrid photosensitive resin; The nano-reinforced hybrid photosensitive resin is subjected to light-curing 3D printing to obtain a nano-reinforced hybrid photosensitive resin-based composite material.

[0010] As a preferred embodiment of the additive manufacturing method of the present invention, the hydroxylation modification of boron nitride nanotubes (BNNTs) comprises: Boron nitride nanotubes (BNNTs) were added to the modified solution, reacted at 95°C for 4 hours, filtered, washed, and dried to obtain BNNTs-OH powder. The modified solution is a mixed acid solution composed of sulfuric acid and nitric acid in a volume ratio of 3:1; The ratio of boron nitride nanotubes (BNNTs) to modified solution is 100 mg to 300 mg per 60 mL. The BNNTs have an outer diameter of 20-80 nm, a length of 5-50 μm, and a purity of 90%.

[0011] As a preferred embodiment of the additive manufacturing method of the present invention, the concentration of polyvinyl pyrrolidone is 0.2 wt %.

[0012] As a preferred embodiment of the additive manufacturing method of the present invention, the BNNTs-OH dispersion is mixed with phosphoric acid and zirconium oxychloride octahydrate to obtain a mixed system, wherein the mass ratio of BNNTs-OH, H3PO4 and ZrOCl2·8H2O is 1~10:91:100.

[0013] As a preferred embodiment of the additive manufacturing method of the present invention, the mixing method of the mixed system includes: Under magnetic stirring at 600 rpm, a 1 mol / L ZrOCl2·8H2O aqueous solution was slowly added dropwise to 8 mol / L H3PO4 at a rate of 1 mL / min, maintaining the system temperature at 25±1°C to obtain a H3PO4 / ZrOCl2·8H2O mixture. The BNNTs-OH dispersion was added to the H3PO4 / ZrOCl2·8H2O mixture at a flow rate of 5 mL / min through a constant flow pump, and the stirring rate was increased to 1000 rpm and stirred for 40 min.

[0014] As a preferred embodiment of the additive manufacturing method of the present invention, the in-situ hydrothermal method comprises the following steps: the reaction temperature is 160-220°C, the reaction time is 12-36 hours, and the reaction pressure is 0.05 MPa.

[0015] As a preferred embodiment of the additive manufacturing method of the present invention, wherein: the photosensitive prepolymer is epoxy acrylate / polyurethane acrylate; According to the weight percentage of raw materials, the photosensitive prepolymer includes: 20% to 40% epoxy resin, 18% to 38% methacrylic acid, 0.1% to 1% tetramethylammonium chloride, 0.1% to 0.8% hydroquinone, and 25% to 65% polyurethane acrylate; The preparation method of the photosensitive prepolymer is as follows: heating the epoxy resin oil bath to 40-60°C and stirring, adding a methacrylic acid mixed solution mixed with tetramethylammonium chloride and hydroquinone dropwise when heated to 90-110°C, completing the addition within 1 hour, stirring at the same temperature, reacting for 6-8 hours, cooling to 40-60°C, adding polyurethane acrylate, and stirring at the same temperature for 2 hours; wherein, The epoxy resin is bisphenol F epoxy resin.

[0016] As a preferred embodiment of the additive manufacturing method of the present invention, the diluent is tripropylene glycol diacrylate TPGDA, and the photoinitiator is phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide; The weight percentage of the diluent, the mixed photosensitive prepolymer and the photoinitiator is: 12% to 50%: 50% to 85%: 0.1% to 5%; The ZrP-BNNTs powder and the diluent are mixed uniformly, comprising: stirring the ZrP-BNNTs powder and the diluent at 40-60° C. for 2 hours and ultrasonically applying the mixture for 30 minutes; The mass ratio of ZrP-BNNTs powder to photosensitive resin is 5:95.

[0017] As a preferred embodiment of the additive manufacturing method of the present invention, the 3D printing parameters include: bottom exposure of 1 layer, initial exposure time of 40-50 s, exposure delay of 3-5 s, single layer exposure time of 3 s, platform lifting height of 8 mm, and motor operating speed of 3 mm / s; Single layer printing thickness is 30~80μm; The printed sample was ultrasonically oscillated in anhydrous ethanol for 5 minutes and then UV-cured for 30 to 60 minutes.

[0018] Another object of the present invention is to overcome the deficiencies in the prior art and provide a nano-reinforced hybrid photosensitive resin-based composite material.

[0019] Beneficial effects of the present invention: The present invention uses the "in situ ion enrichment-heterogeneous nucleation-confined epitaxy" mechanism to uniformly grow ZrP nanosheets on the outer wall of BNNTs, forming a good "sheet-tube" synergistic structure, which greatly improves the dispersion of the filler in the resin matrix and the interfacial bonding force; the obtained nano-enhanced photosensitive resin is suitable for high-precision light-curing 3D printing, and the molded parts have significantly enhanced mechanical strength, stiffness and wear resistance, meeting the needs of aerospace, high-end equipment and precision manufacturing fields for high-performance additive manufacturing materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them: Figure 1 These are transmission electron microscopy (TEM) images of the ZrP-BNNTs nanomaterial dispersions prepared in Examples 1 to 3 of the present invention; wherein, (a) is a TEM image of BNNTs-OH, (b) is a TEM image of the ZrP-BNNTs prepared in Example 2, (c) is a TEM image of the ZrP-BNNTs prepared in Example 1, (d) is a TEM image of the ZrP-BNNTs prepared in Example 3, and (e) is a TEM image of a direct physical mixture of ZrP and BNNT.

[0021] Figure 2 This is a line graph of the tensile properties of the composite materials prepared in Examples 1 to 3 of the present invention.

[0022] Figure 3These are scanning electron microscope (SEM) images of the tensile fracture surfaces of the composite materials prepared in Examples 1 to 3 of the present invention, wherein (a) is the SEM image of Example 1, (b) is the SEM image of Example 2, and (c) is the SEM image of Example 3.

[0023] Figure 4 The friction and wear performance line diagrams of the composite materials prepared in Examples 1 to 3 of the present invention are shown, wherein (a) is the friction coefficient diagram of Examples 1 to 3, and (b) is the wear rate diagram of Examples 1 to 3.

[0024] Figure 5 These are SEM images of the wear surfaces of the composite materials prepared in Examples 1 to 3 of the present invention, wherein (a) is the SEM image of the wear surface of Example 1, (b) is the SEM image of the wear surface of Example 2, and (c) is the SEM image of the wear surface of Example 3. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0026] All raw materials in the examples of the present invention were analytically pure or industrial products, and the water used in the experiments was deionized water. The mechanical properties were tested by tensile testing at room temperature according to GB / T1040.2-2006. The friction and wear properties were tested on a reciprocating ball-plate friction tester. The wear member was a GCr15 steel ball with a diameter of 5 mm. The load was 6 N. The reciprocating frequency was 2 Hz. The reciprocating stroke was 5 mm. The friction test lasted for 30 minutes, and the friction coefficient and wear rate were measured. The friction coefficient was automatically recorded by the friction tester, and the wear rate was calculated as follows: wear volume / (normal load × total sliding displacement). The wear volume was directly measured by a three-dimensional topography instrument.

[0027] The 3D printing device used in the embodiment of the present invention is a HALOT-LITE light-curing 3D printer.

[0028] Example 1 The additive manufacturing method of the nano-reinforced hybrid photosensitive resin-based composite material described in this embodiment is a preferred process, comprising the following steps: (1) Boron nitride nanotubes (BNNTs) were hydroxylated using mixed acid oxidation. Weigh 0.20 g of BNNTs (OD 60 nm, length 40 µm, 90% purity) and disperse them in 60 mL of a 3:1 (volume ratio) H2SO4 / HNO3 mixture. Stir and reflux at 95°C for 4 h. After cooling, the mixture was filtered through a PTFE membrane, washed with deionized water until the pH of the filtrate was 7, and dried under vacuum at 60°C for 10 h to obtain BNNTs-OH powder for later use.

[0029] (2) The BNNTs-OH powder obtained in step (1) was ultrasonically dispersed in 400 mL of 0.2 wt % PVP solution at an ultrasonic power of 200 W for 30 min. Take 200 mL of 8 mol / L H3PO4, stir magnetically at 600 rpm, and keep the temperature at 25±1℃; Prepare a 1 mol / L ZrOCl2·8H2O solution and add it dropwise to H3PO4 (200 mL in total) at 1 mL / min. Then, inject the BNNTs-OH dispersion at 5 mL / min using a constant flow pump. Increase the speed to 1000 rpm and react for 40 min. The mixture was injected into a stainless steel autoclave lined with polytetrafluoroethylene (PTFE) and filled with 0.05 MPa argon back pressure after all bubbles were exhausted. The mixture was hydrothermally reacted at 160°C for 24 h. The mass ratio of BNNTs-OH, H3PO4, and ZrOCl2·8H2O was 5:91:100. The product was centrifuged at 4000 rpm for 10 min, washed alternately with water and 0.01 mol / L NH3·H2O five times, and dried in vacuum at 60°C for 10 h to obtain light gray ZrP-BNNTs powder.

[0030] (3) Preparation of hybrid photosensitive prepolymer: Heat 30g of bisphenol F epoxy resin to 100℃; add 25g of methacrylic acid containing 0.3g of tetramethylammonium chloride and 0.15g of hydroquinone dropwise within 1h, react for 7h, then reduce the temperature to 50℃, add 45g of polyurethane acrylate, and continue the reaction for 2h to obtain hybrid photosensitive prepolymer; (4) Configure nano-enhanced hybrid photosensitive resin Take 5 g of the ZrP-BNNTs nanomaterials described in step (2) and mix them with 25 g of TPGDA, stir them at 50 °C for 2 h, and continue ultrasonication for 30 min; Add 68 g of the hybrid photosensitive prepolymer described in step (3) and 2 g of photoinitiator, stir at 50°C for 6 h, and cool naturally to obtain a photosensitive resin.

[0031] (5) Using the “photocuring additive manufacturing” technology, the nano-enhanced hybrid photosensitive resin described in step (4) is subjected to photocuring 3D printing; The bottom layer was exposed for 45 s, with a delay of 3 s, a layer thickness of 50 μm, a single layer exposure of 3 s, a platform lifting height of 8 mm, and a motor operating speed of 3 mm / s; Print tensile dumbbell-shaped specimens and rectangular friction specimens; The printed parts were ultrasonicated in ethanol for 5 min and then post-cured with UV for 45 min.

[0032] The TEM microstructure of the ZrP-BNNTs dispersion solution prepared in this example is shown in the attached Figure 1 (c).

[0033] (6) The tensile properties and friction and wear properties of the nano-reinforced hybrid photosensitive resin-based composite material prepared above were tested. Each group of tests was conducted 5 times, and the valid data were taken for analysis and characterization.

[0034] The tensile properties of the stereolithography samples obtained in this example are shown in Figure 2 and Figure 3 , the tensile strength and elongation at break are 49MPa and 18% respectively, the fracture cross-section morphology is complex, with a large number of plastic deformation traces, showing strong and tough fracture characteristics; The friction and wear properties of the stereolithography samples obtained in this example are shown in Figure 4 and Figure 5 , the friction coefficient and wear rate are 0.51 and 2.81×10 -4 mm 3 ·N -1 ·m -1 ; It shows that the nano-reinforced hybrid photosensitive resin-based composite material prepared in this embodiment has the best comprehensive performance.

[0035] Example 2 The additive manufacturing method of the nano-reinforced hybrid photosensitive resin-based composite material described in this embodiment includes the following steps: (1) Boron nitride nanotubes (BNNTs) were hydroxylated using mixed acid oxidation. Weigh 0.4 g of BNNTs (OD 60 nm, length 40 µm, 90% purity) and disperse in 60 mL of H2SO4 / HNO3 mixed acid (volume ratio 3:1). Reflux at 95°C with stirring for 4 h. After cooling, filter through a PTFE membrane, wash with deionized water until the filtrate has a pH of 7, and dry under vacuum at 60°C for 10 h to obtain BNNTs-OH powder for later use.

[0036] (2) Dispersing the modified BNNTs-OH obtained in step (1) using 0.2 wt % polyvinylpyrrolidone (PVP) as a dispersant in a 200 W ultrasonic bath for 30 min to obtain a BNNTs-OH dispersion; It was then mixed with phosphoric acid (H3PO4) and zirconium oxychloride octahydrate (ZrOCl2·8H2O) with a mass ratio of BNNTs-OH, H3PO4, and ZrOCl2·8H2O of 10:91:100; Under magnetic stirring at 600 rpm, a 1 mol / L ZrOCl2·8H2O aqueous solution was slowly added dropwise to 8 mol / L H3PO4 at a rate of 1 mL / min, maintaining the system temperature at 25±1°C. The BNNTs-OH dispersion was added to the H3PO4 / ZrOCl2·8H2O mixture at a flow rate of 5 mL / min using a constant flow pump. The stirring rate was increased to 1000 rpm and the reaction was continued for 40 min. A stainless steel high-pressure reactor with a polytetrafluoroethylene (PTFE) liner was used to react at 210° C. for 30 h, and ZrP-BNNTs nanopowder was finally obtained for later use.

[0037] (3) Preparation of hybrid photosensitive prepolymer: Heat 30 g of bisphenol F epoxy resin to 100 °C; add 25 g of methacrylic acid containing 0.3 g of tetramethylammonium chloride and 0.15 g of hydroquinone dropwise within 1 h, react for 7 h, then cool to 50 °C, add 45 g of polyurethane acrylate, and continue to react for 2 h to obtain a hybrid photosensitive prepolymer.

[0038] (4) Configure nano-enhanced hybrid photosensitive resin 7 g of the ZrP-BNNTs nanomaterial described in step (2) was mixed with 15 g of TPGDA, stirred at 50 ° C for 2 h, and then ultrasonicated for 30 min; Add 76 g of the hybrid photosensitive prepolymer described in step (3) and 2 g of photoinitiator, stir at 50° C. for 6 h, and cool naturally to obtain a photosensitive resin.

[0039] (5) Using the “photocuring additive manufacturing” technology, the nano-enhanced hybrid photosensitive resin described in step (4) is subjected to photocuring 3D printing; The bottom layer was exposed for 50 s, with a delay of 3 s, a layer thickness of 40 μm, a single layer exposure of 3 s, a platform lifting height of 8 mm, and a motor operating speed of 2.5 mm / s; Print tensile dumbbell-shaped specimens and rectangular friction specimens; the printed parts are ultrasonically treated with ethanol for 5 minutes and then UV-cured for 60 minutes.

[0040] The TEM microstructure of the ZrP-BNNTs dispersion solution prepared in this example is shown in the attached Figure 1 (b); The tensile properties and friction and wear properties of the nano-reinforced hybrid photosensitive resin-based composite material prepared above were tested. Each group of tests was conducted 5 times, and the valid data were taken for analysis and characterization.

[0041] The tensile properties of the stereolithography samples obtained in this example are shown in Figure 2 and Figure 3 , the tensile strength and elongation at break are 32 MPa and 15% respectively, and the fracture cross section shows a layered tearing morphology, which is caused by the agglomeration of a large number of ZrP nanosheets; The friction and wear properties of the stereolithography samples obtained in this example are shown in Figure 4 and Figure 5 , the friction coefficient and wear rate are 0.63 and 5.65×10 -4 mm 3 ·N -1 ·m -1 .

[0042] Example 3 The additive manufacturing method of the nano-reinforced hybrid photosensitive resin-based composite material described in this embodiment includes the following steps: (1) Boron nitride nanotubes (BNNTs) were hydroxylated using mixed acid oxidation. Weigh 0.05 g of BNNTs (OD 60 nm, length 40 µm, 90% purity) and disperse in 60 mL of H2SO4 / HNO3 mixed acid (volume ratio 3:1). Reflux at 95°C with stirring for 4 h. After cooling, filter through a PTFE membrane, wash with deionized water until the filtrate has a pH of 7, and dry in a vacuum at 60°C for 10 h to obtain BNNTs-OH powder for later use.

[0043] (2) Dispersing the modified BNNTs-OH obtained in step (1) using 0.2 wt % polyvinylpyrrolidone (PVP) as a dispersant in a 200 W ultrasonic bath for 30 min to obtain a BNNTs-OH dispersion; It was then mixed with phosphoric acid (H3PO4) and zirconium oxychloride octahydrate (ZrOCl2·8H2O), with the mass ratio of BNNTs-OH, H3PO4 and ZrOCl2·8H2O being 1:91:100; Under magnetic stirring at 600 rpm, a 1 mol / L ZrOCl2·8H2O aqueous solution was slowly added dropwise to 8 mol / L H3PO4 at a rate of 1 mL / min, maintaining the system temperature at 25±1°C. The BNNTs-OH dispersion was added to the H3PO4 / ZrOCl2·8H2O mixture at a flow rate of 5 mL / min using a constant flow pump. The stirring rate was increased to 1000 rpm and the reaction was continued for 40 min. The reaction was then carried out at 160°C for 18 h in a stainless steel autoclave lined with polytetrafluoroethylene (PTFE) to obtain ZrP-BNNTs nanopowders for later use.

[0044] (3) Preparation of hybrid photosensitive prepolymer: Heat 30 g of bisphenol F epoxy resin to 100 °C; add 25 g of methacrylic acid containing 0.3 g of tetramethylammonium chloride and 0.15 g of hydroquinone dropwise within 1 h, react for 7 h, then cool to 50 °C, add 45 g of polyurethane acrylate, and continue to react for 2 h to obtain a hybrid photosensitive prepolymer.

[0045] (4) Configure nano-enhanced hybrid photosensitive resin Take 2.5 g of the ZrP-BNNTs nanomaterial described in step (2) and mix it with 50 g of TPGDA, stir it at 50 ° C for 2 h, and continue ultrasonication for 30 min; Add 45 g of the hybrid photosensitive prepolymer described in step (3) and 2 g of photoinitiator, stir at 50° C. for 6 h, and cool naturally to obtain a photosensitive resin.

[0046] (5) Using the “photocuring additive manufacturing” technology, the nano-enhanced hybrid photosensitive resin described in step (4) is subjected to photocuring 3D printing; The bottom layer was exposed for 40 s, with a delay of 3 s, a layer thickness of 60 μm, a single layer exposure of 3 s, a platform lifting height of 8 mm, and a motor operating speed of 3 mm / s; Tensile dumbbell-shaped specimens and rectangular friction specimens were printed; the printed parts were ultrasonically treated with ethanol for 5 minutes and then UV-cured for 30 minutes.

[0047] The TEM microstructure of the ZrP-BNNTs dispersion solution prepared in this example is shown in the attached Figure 1 (d); The tensile properties and friction and wear properties of the nano-reinforced hybrid photosensitive resin-based composite material prepared above were tested. Each group of tests was conducted 5 times, and the valid data were taken for analysis and characterization.

[0048] The tensile properties of the stereolithography samples obtained in this example are shown in Figure 2 and Figure 3 , the tensile strength and elongation at break were 21 MPa and 12.8% respectively, and the fracture cross section showed a layered tearing morphology, which was caused by the agglomeration of a large number of ZrP nanosheets; The friction and wear properties of the stereolithography samples obtained in this example are shown in Figure 4 and Figure 5 , the friction coefficient and wear rate are 0.68 and 6.18×10 -4 mm 3 ·N -1 ·m -1 .

[0049] Comparative Example 1 The test method, instrument and evaluation index of this comparative example are consistent with those in the embodiment, and only the type of nanofiller or the preparation route is changed.

[0050] (1) BNNTs powder was directly ultrasonically dispersed in 400 mL of 0.2 wt % PVP solution at an ultrasonic power of 200 W for 30 min. Take 200 mL of 8 mol / L H3PO4, stir magnetically at 600 rpm, and keep the temperature at 25±1℃; Prepare a 1 mol / L ZrOCl2·8H2O solution and add it dropwise to H3PO4 (200 mL in total) at a rate of 1 mL / min. Then, inject the BNNTs dispersion using a constant flow pump at a rate of 5 mL / min. Increase the speed to 1000 rpm and react for 40 min. The mixture was injected into a stainless steel autoclave lined with polytetrafluoroethylene (PTFE). After all bubbles were exhausted, the reaction was heated at 160°C under 0.05 MPa argon back pressure for 24 h. The mass ratio of BNNTs, H3PO4, and ZrOCl2·8H2O was 5:91:100. The product was centrifuged at 4000 rpm for 10 min, washed alternately with water and 0.01 mol / L NH3·H2O five times, and dried in vacuum at 60°C for 10 h to obtain ZrP-BNNTs powder.

[0051] (2) Preparation of hybrid photosensitive prepolymer: Heat 30 g of bisphenol F epoxy resin to 100 °C; add 25 g of methacrylic acid containing 0.3 g of tetramethylammonium chloride and 0.15 g of hydroquinone dropwise within 1 h, react for 7 h, then cool to 50 °C, add 45 g of polyurethane acrylate, and continue to react for 2 h to obtain a hybrid photosensitive prepolymer.

[0052] (3) Configure nano-enhanced hybrid photosensitive resin Take 5 g of the ZrP-BNNTs nanomaterial described in step (1) and mix it with 25 g of TPGDA, stir it at 50°C for 2 hours, and continue ultrasonication for 30 minutes; add 68 g of the hybrid photosensitive prepolymer described in step (2) and 2 g of photoinitiator, stir it at 50°C for 6 hours, and cool it naturally to obtain a photosensitive resin.

[0053] (4) Using the “photocuring additive manufacturing” technology, the nano-enhanced hybrid photosensitive resin described in step (3) is subjected to photocuring 3D printing; The bottom layer was exposed for 45 s, the delay was 3 s, the layer thickness was 50 µm, the single layer was exposed for 3 s, the platform lifting height was 8 mm, and the motor operating speed was 3 mm / s; tensile dumbbell-shaped specimens and rectangular friction specimens were printed; the printed parts were ultrasonically treated with ethanol for 5 min and then UV-cured for 45 min.

[0054] (5) The tensile properties and friction and wear properties of the nano-reinforced hybrid photosensitive resin-based composite material prepared above were tested. Each group of tests was conducted 5 times, and the valid data were taken for analysis and characterization.

[0055] The tensile properties of the stereolithography specimens obtained in this comparative example, the tensile strength and elongation at break, were reduced by 124% and 79% respectively compared to those in Example 1; The friction coefficient and wear rate increased by 47% and 172% respectively compared with Example 1; This indicates that the active sites provided by hydroxylation are crucial for the formation of dense and uniform ZrP coating.

[0056] Comparative Example 2 (1) Boron nitride nanotubes (BNNTs) were hydroxylated using mixed acid oxidation. Weigh 0.20 g of BNNTs (OD 60 nm, length 40 µm, 90% purity) and disperse them in 60 mL of a 3:1 volume ratio H2SO4 / HNO3 mixture. Stir and reflux at 95°C for 4 h. After cooling, the mixture was filtered through a PTFE membrane, washed with deionized water until the pH of the filtrate was 7, and dried under vacuum at 60°C for 10 h to obtain BNNTs-OH powder for later use.

[0057] (2) Preparation of hybrid photosensitive prepolymer: Heat 30 g of bisphenol F epoxy resin to 100 °C; add 25 g of methacrylic acid containing 0.3 g of tetramethylammonium chloride and 0.15 g of hydroquinone dropwise within 1 h, react for 7 h, then cool to 50 °C, add 45 g of polyurethane acrylate, and continue to react for 2 h to obtain a hybrid photosensitive prepolymer.

[0058] (3) Configure nano-enhanced hybrid photosensitive resin Take 5 g of the BNNTs-OH nanomaterial described in step (1) and mix it with 25 g of TPGDA, stir it at 50°C for 2 h, and continue ultrasonication for 30 min; add 68 g of the hybrid photosensitive prepolymer described in step (2) and 2 g of photoinitiator, stir it at 50°C for 6 h, and cool it naturally to obtain a photosensitive resin.

[0059] (4) Using the “photocuring additive manufacturing” technology, the nano-enhanced hybrid photosensitive resin described in step (3) is subjected to photocuring 3D printing; The bottom layer was exposed for 45 seconds, with a delay of 3 seconds, a layer thickness of 50 µm, and a single layer exposure of 3 seconds. The platform lifting height was 8 mm, and the motor speed was 3 mm / s. Tensile dumbbell-shaped specimens and rectangular friction specimens were printed. The printed parts were ultrasonically treated with ethanol for 5 minutes and then UV-cured for 45 minutes. The tensile properties and friction and wear properties of the nano-reinforced hybrid photosensitive resin-based composite material prepared above were tested. Each group of tests was conducted 5 times, and the valid data were taken for analysis and characterization.

[0060] The tensile properties of the stereolithography specimens obtained in this comparative example, the tensile strength and elongation at break, were reduced by 86% and 43% compared to those in Example 1, respectively. The friction coefficient and wear rate increased by 65% ​​and 208% respectively compared with Example 1, indicating that the two-dimensional synergy and interface strengthening effect of ZrP play an outstanding role in friction reduction and wear resistance.

[0061] Comparative Example 3 (1) Boron nitride nanotubes (BNNTs) were hydroxylated using mixed acid oxidation. Weigh 0.03 g of BNNTs (OD 60 nm, length 40 µm, 90% purity) and disperse them in 60 mL of a 3:1 (volume ratio) H2SO4 / HNO3 mixture. Stir under reflux at 95°C for 4 h. After cooling, the mixture was filtered through a PTFE membrane, washed with deionized water until the pH of the filtrate was 7, and dried under vacuum at 60°C for 10 h to obtain BNNTs-OH powder for later use.

[0062] (2) Dispersing the modified BNNTs-OH obtained in step (1) with 400 mL of 0.2 wt % polyvinylpyrrolidone (PVP) as a dispersant in a 200 W ultrasonic bath for 30 min to obtain a BNNTs-OH dispersion; Then, it was mixed with phosphoric acid (8 mol / L, H3PO4) and zirconium oxychloride octahydrate (1 mol / L, ZrOCl2·8H2O) with a mass ratio of BNNTs-OH, H3PO4, and ZrOCl2·8H2O of 0.5:91:100; Under magnetic stirring at 600 rpm, a 1 mol / L ZrOCl2·8H2O aqueous solution was slowly added dropwise to 8 mol / L H3PO4 at a rate of 1 mL / min, maintaining the system temperature at 25±1°C. The BNNTs-OH dispersion was added to the H3PO4 / ZrOCl2·8H2O mixture at a flow rate of 5 mL / min using a constant flow pump. The stirring rate was increased to 1000 rpm and the mixture was reacted for 40 min. The reaction was then carried out at 180°C for 6 h in a stainless steel autoclave lined with polytetrafluoroethylene (PTFE) to obtain ZrP-BNNTs nanopowders for later use.

[0063] (3) Preparation of hybrid photosensitive prepolymer: Heat 30 g of bisphenol F epoxy resin to 100 °C; add 25 g of methacrylic acid containing 0.3 g of tetramethylammonium chloride and 0.15 g of hydroquinone dropwise within 1 h, react for 7 h, then reduce the temperature to 50 °C, add 45 g of polyurethane acrylate, and continue the reaction for 2 h to obtain a hybrid photosensitive prepolymer.

[0064] (4) Configure nano-enhanced hybrid photosensitive resin 5 g of the ZrP-BNNTs nanomaterial described in step (2) was mixed with 25 g of TPGDA, stirred at 50°C for 2 h, and then ultrasonicated for 30 min; 68 g of the hybrid photosensitive prepolymer described in step (3) and 2 g of the photoinitiator were added, stirred at 50°C for 6 h, and naturally cooled to obtain a photosensitive resin; (5) Using the “photocuring additive manufacturing” technology, the nano-enhanced hybrid photosensitive resin described in step (4) was subjected to photocuring 3D printing; the bottom layer was exposed for 45 s, the delay was 3 s, the layer thickness was 50 μm, the single layer was exposed for 3 s, the platform lifting height was 8 mm, and the motor operating speed was 3 mm / s; the tensile dumbbell-shaped specimens and the rectangular friction specimens were printed; the printed parts were ultrasonically treated with ethanol for 5 min, and UV secondary curing was performed for 45 min.

[0065] The tensile properties and friction and wear properties of the nano-reinforced hybrid photosensitive resin-based composite material prepared above were tested. Each group of tests was conducted 5 times, and the valid data were taken for analysis and characterization.

[0066] The tensile properties of the photocurable stereolithography specimens obtained in this comparative example, the tensile strength and elongation at break were respectively reduced by 106% and 63% compared with those in Example 1; the friction coefficient and wear rate were respectively increased by 58% and 194% compared with those in Example 1; this indicates that the low content of BNNTs leads to insufficient one-dimensional force transmission skeleton, insufficient hydrothermal time, and difficulty in forming continuous epitaxy of the ZrP sheet.

[0067] The above comparative cases show that unhydroxylated BNNTs (Comparative Example 1) or only hydroxylated BNNTs-OH without adding synthetic ZrP components (Comparative Example 2) are limited in improving the interfacial bonding and dispersibility between nanomaterials and resin matrices; hydroxylation is a prerequisite for ensuring uniform epitaxy of ZrP; simply enhancing the photosensitive resin with BNNTs-OH is not sufficient to effectively improve its comprehensive performance; under inappropriate parameters (Comparative Example 3), the ZrP-BNNTs nanocomposite structure does not grow sufficiently, easily agglomerates, and has limited performance improvement; compared with the implementation cases (optimal parameters, "in situ ion enrichment-heterogeneous nucleation-confined epitaxy" mechanism), the tensile, friction reduction, and wear resistance of each comparative case are significantly lower, verifying the necessity and superiority of the parameters and processes of the present invention.

[0068] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of these should be included in the scope of the present invention.

Claims

1. A method for additive manufacturing of nano-reinforced hybrid photosensitive resin-based composite materials, characterized by: include, Boron nitride nanotubes (BNNTs) are subjected to hydroxylation modification to obtain BNNTs-OH powder; BNNTs-OH powder is added to polyvinyl pyrrolidone and dispersed evenly to obtain a BNNTs-OH dispersion; A BNNTs-OH dispersion is mixed with phosphoric acid and zirconium oxychloride octahydrate to obtain a mixed system, and zirconium phosphate (ZrP) nanosheets are in situ grown on the surface of the BNNTs by an in situ hydrothermal method to obtain a ZrP-BNNTs nanomaterial mixed suspension, which is then centrifuged, washed, and dried to obtain ZrP-BNNTs powder. After the ZrP-BNNTs powder and the diluent are evenly mixed, a photosensitive prepolymer and a photoinitiator are added, and the mixture is stirred at a temperature of 4 to 8 hours. After the reaction is completed, the mixture is naturally cooled to obtain a nano-enhanced hybrid photosensitive resin; The nano-reinforced hybrid photosensitive resin is subjected to light-curing 3D printing to obtain a nano-reinforced hybrid photosensitive resin-based composite material.

2. The additive manufacturing method according to claim 1, wherein: The boron nitride nanotubes BNNTs are subjected to hydroxylation modification treatment, comprising: Boron nitride nanotubes (BNNTs) were added to the modified solution, reacted at 95°C for 4 hours, filtered, washed, and dried to obtain BNNTs-OH powder. The modified solution is a mixed acid solution composed of sulfuric acid and nitric acid in a volume ratio of 3:1; The ratio of boron nitride nanotubes (BNNTs) to modified solution is 100 mg to 300 mg per 60 mL. The BNNTs have an outer diameter of 20-80 nm, a length of 5-50 μm, and a purity of 90%.

3. The additive manufacturing method according to claim 1 or 2, wherein: The concentration of the polyvinyl pyrrolidone is 0.2 wt %.

4. The additive manufacturing method according to claim 3, wherein: The BNNTs-OH dispersion is mixed with phosphoric acid and zirconium oxychloride octahydrate to obtain a mixed system, wherein the mass ratio of BNNTs-OH, H3PO4 and ZrOCl2·8H2O is 1-10:91:

100.

5. The additive manufacturing method according to claim 1 or 4, wherein: The mixing method of the mixed system includes, Under magnetic stirring at 600 rpm, a 1 mol / L ZrOCl2·8H2O aqueous solution was slowly added dropwise to 8 mol / L H3PO4 at a rate of 1 mL / min, maintaining the system temperature at 25±1°C to obtain a H3PO4 / ZrOCl2·8H2O mixture. The BNNTs-OH dispersion was added to the H3PO4 / ZrOCl2·8H2O mixture at a flow rate of 5 mL / min through a constant flow pump, and the stirring rate was increased to 1000 rpm and stirred for 40 min.

6. The additive manufacturing method according to claim 5, wherein: The in-situ hydrothermal method comprises the following steps: the reaction temperature is 160-220° C., the reaction time is 12-36 h, and the reaction pressure is 0.05 MPa.

7. The additive manufacturing method according to claim 1, wherein: The photosensitive prepolymer is epoxy acrylate / polyurethane acrylate; According to the weight percentage of raw materials, the photosensitive prepolymer includes: 20% to 40% epoxy resin, 18% to 38% methacrylic acid, 0.1% to 1% tetramethylammonium chloride, 0.1% to 0.8% hydroquinone, and 25% to 65% polyurethane acrylate; The preparation method of the photosensitive prepolymer is as follows: heating the epoxy resin oil bath to 40-60°C and stirring, adding a methacrylic acid mixed solution mixed with tetramethylammonium chloride and hydroquinone dropwise when heated to 90-110°C, completing the addition within 1 hour, stirring at the same temperature, reacting for 6-8 hours, cooling to 40-60°C, adding polyurethane acrylate, and stirring at the same temperature for 2 hours; wherein, The epoxy resin is bisphenol F epoxy resin.

8. The additive manufacturing method according to claim 1, wherein: The diluent is tripropylene glycol diacrylate TPGDA, and the photoinitiator is phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide; The weight percentage of the diluent, the mixed photosensitive prepolymer and the photoinitiator is: 12% to 50%: 50% to 85%: 0.1% to 5%; The ZrP-BNNTs powder and the diluent are mixed uniformly, comprising: stirring the ZrP-BNNTs powder and the diluent at 40-60° C. for 2 hours and ultrasonically applying the mixture for 30 minutes; The mass ratio of ZrP-BNNTs powder to photosensitive resin is 5:

95.

9. The additive manufacturing method according to claim 1 or 8, wherein: The 3D printing parameters include: bottom exposure of 1 layer, initial exposure time of 40-50 s, exposure delay of 3-5 s, single layer exposure time of 3 s, platform lifting height of 8 mm, and motor operating speed of 3 mm / s; Single layer printing thickness is 30~80μm; The printed sample was ultrasonically oscillated in anhydrous ethanol for 5 minutes and then UV-cured for 30 to 60 minutes.

10. A nano-reinforced hybrid photosensitive resin-based composite material produced by the additive manufacturing method according to any one of claims 1 to 9.

Images