Resin for UV3D printed dental repair model and preparation method thereof

Abstract

The invention discloses a resin for a UV3D printing dental repair model and a preparation method thereof, and belongs to the technical field of epoxy resin materials. Comprising the following steps: synthesizing a core functional monomer, blending an active diluent and epoxy resin, carrying out microwave-assisted nano silicon dioxide in-situ generation, carrying out ultrasonic-assisted MOF loaded initiator preparation, carrying out ultraviolet light-plasma composite surface treatment, and carrying out variable-frequency near-infrared rapid curing to obtain the model resin for UV3D printing dental repair. Through innovative synthesis of a core functional monomer, multi-component synergistic blending and a special preparation process, the performance defects of traditional dental 3D printing light-cured resin are effectively overcome, and the mechanical property, curing stability and printing precision of the material are greatly improved; and a reliable technical scheme is provided for high-precision and high-performance 3D printing of the dental repair model.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin materials technology, specifically to a resin for UV 3D printing dental restoration models and its preparation method. Background Technology

[0002] In the field of dental 3D printing, the performance of photocurable resin materials directly determines the precision, mechanical strength, and biocompatibility of the restoration. Current mainstream photocurable resin systems typically employ a strategy of combining multifunctional monomers with monofunctional / difunctional monomers. Multifunctional monomers (such as BisGMA and UDMA), containing at least two polyacrylate functional groups, can form a high-density network structure through photo-initiated crosslinking, endowing the material with excellent rigidity and wear resistance. However, high functionality leads to strong intermolecular forces and high system viscosity, requiring the use of low-viscosity monomers to adjust printing flowability. Monofunctional / difunctional monomers (such as THFA and IBOA), with their single crosslinking site and low molecular weight, can effectively reduce resin viscosity, but their crosslinking contribution is low, and excessive use can lead to material strength degradation.

[0003] However, there is an inherent contradiction in the copolymerization behavior of the two types of monomers. The reactivity ratio of multifunctional monomers is usually higher than that of monofunctional monomers. This leads to the preferential and rapid crosslinking of multifunctional monomers in the early stages of polymerization, forming crosslink-rich microdomains, while monofunctional monomers are repelled to the interstices of the microdomains, forming crosslink-poor regions. This kinetic incompatibility can trigger nanoscale phase separation, resulting in a "hard core-soft shell" structure inside the material.

[0004] This can lead to the following consequences: fluctuations in material strength, making it prone to cracking in stress concentration areas (such as the edges of the prosthesis) during clinical applications; and inconsistent curing shrinkage rates due to phase separation, resulting in increased dimensional errors in printed parts, affecting the fit and thus the accuracy.

[0005] Based on this, the present invention designs a resin for UV 3D printing dental restoration models and its preparation method to solve the above problems. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the existing technology, the present invention provides a resin for UV 3D printing dental restoration models and its preparation method.

[0007] A method for preparing a resin for UV 3D printing dental restoration models includes the following steps: Step 1: Synthesis of core functional units; 1.1 Synthesis of camphorquinone-modified acrylate prepolymer; Camphorquinone, acrylate monomers, and Lewis acid catalyst are added to a solvent, and the mixture is heated and stirred to react. Solvent was removed under reduced pressure to obtain camphorquinone-modified acrylate prepolymer; 1.2 Synthesis of benzyloxazoline reactive diluent; Benzyl chloride and oxazoline, along with the catalyst and solvent N,N-dimethylformamide, are mixed, heated, and filtered to remove potassium carbonate, yielding a benzyl oxazoline active diluent. 1.3 Synthesis of triazine-modified bisphenol A type epoxy resin; Bisphenol A type epoxy resin, melamine, and catalyst are heated and melted; Cool to room temperature to obtain triazine-modified epoxy resin; Step 2: Blending of reactive diluent and epoxy resin; Triazine-modified epoxy resin, camphorquinone-modified acrylate prepolymer, oxazoline reactive diluent, and styrene were mixed and ultrasonically dispersed; hydroquinone was added to obtain a blend. Step 3: Microwave-assisted in-situ generation of nano-silica; After uniformly mixing tetraethyl orthosilicate, the blend liquid, and the catalyst, the mixture is microwaved to remove ethanol, thus obtaining a nano-reinforced prepolymer. Step 4: Preparation of ultrasound-assisted MOF-loaded initiator; ZIF-8 and the initiator were added to anhydrous acetonitrile, ultrasonically treated, and separated and dried to obtain a nanoscale dispersed MOF-supported initiator. Step 5: Ultraviolet-plasma composite surface treatment; MOF-supported initiator and nano-reinforced prepolymer are uniformly mixed to obtain a coating solution, which is then irradiated with ultraviolet light; Step 6: Variable frequency near-infrared rapid curing yields resin for UV 3D printing of dental restoration models.

[0008] Furthermore, step 1.1 specifically involves adding camphorquinone and acrylate monomers in a molar ratio of 1:1.2-1.5, along with 5-10% by mass of Lewis acid catalyst (camphorquinone), to a solvent of toluene / dichloroethane, wherein the volume of the solvent is 5-10 times the total volume of the reactants. Heat to 50-100℃ and reflux in an oil bath, stirring at 200-300 rpm for 6-12 hours; The solvent was removed by vacuum distillation, and the residue was recrystallized from cyclohexane 2-3 times to obtain a pale yellow crystalline prepolymer, namely camphorquinone-modified acrylate prepolymer.

[0009] Furthermore, step 1.2 specifically involves: adding benzyl chloride and oxazoline in a molar ratio of 1:1.1-1.3, along with the catalyst potassium carbonate and the solvent N,N-dimethylformamide, to a reaction vessel, mixing and stirring to dissolve, heating to 80-120°C, and reacting for 2-3 hours; The total mass of the reactants accounts for 30-50% of the mass of the solvent N,N-dimethylformamide; The amount of potassium carbonate used is 15-20% of the mass of benzyl chloride; Potassium carbonate was removed by filtration, and DMF was recovered by vacuum distillation to obtain benzyloxazoline active diluent.

[0010] Furthermore, step 1.3 specifically involves adding bisphenol A type epoxy resin and melamine in a molar ratio of 3-5:1, along with the catalyst toluenesulfonic acid, to a reaction vessel and heating the mixture to 80-120°C to melt it. The reaction was stirred for 3-4 hours, and the amount of catalyst used was 0.5-2% of the mass of the epoxy resin. Upon cooling to room temperature, a pale yellow viscous liquid is obtained, which is triazine-modified epoxy resin.

[0011] Furthermore, step 2 specifically involves: mixing triazine-modified epoxy resin, camphorquinone-modified acrylate prepolymer, oxazoline reactive diluent, and styrene in a mass ratio of 45-55:15-25:10-15:30-40 at 50-60°C and 300-400 rpm, and then dispersing the mixture for 15-20 minutes with the assistance of an ultrasonic disperser with a power of 200-300W. Add 0.3-0.5% hydroquinone and continue ultrasonic dispersion for 5-10 minutes to obtain a blend.

[0012] Furthermore, step 3 specifically involves: mixing tetraethyl orthosilicate and the blend in a molar ratio of 0.1-0.3:1, along with 1-2% by mass of TEOS catalyst dibutyltin dilaurate, until homogeneous, and then transferring the mixture into a microwave reactor; React at 100-150W microwave power for 1-2 hours. When the system viscosity is 300-500mPa·s, remove ethanol by vacuum distillation for 5-10 minutes to obtain nano-reinforced prepolymer.

[0013] Furthermore, step 4 specifically involves adding ZIF-8 and the initiator diphenyliodonium hexafluorophosphate at a mass ratio of 0.2-0.3:1 to anhydrous acetonitrile and treating the mixture in an ultrasonic cell disruptor with a power of 400-500W for 2-3 hours. Centrifugation and vacuum drying yielded nanoscale dispersed MOF-supported initiators.

[0014] A resin prepared according to the above-described method for preparing a resin for UV 3D printing dental restoration models.

[0015] Compared with the prior art, the beneficial effects of this invention are as follows: 1. This invention introduces camphorquinone-modified acrylate prepolymer, utilizing the stereobridged ring structure of camphorquinone to regulate the acrylate polymerization rate, avoiding preferential and rapid crosslinking of multifunctional monomers, reducing nanoscale phase separation and the formation of a "hard core-soft shell" structure, and fundamentally solving the problem of strength reduction caused by stress concentration. At the same time, the addition of triazine ring-modified bisphenol A epoxy resin increases the crosslinking point density, improves the crosslinking network structure, enhances the overall rigidity and bending resistance of the material, and effectively reduces the risk of edge cracking of the restoration in clinical applications.

[0016] 2. This invention employs multiple technologies for synergistic optimization. The steric hindrance effect of camphorquinone suppresses the difference in double bond conversion rates, reduces localized excessive cross-linking, and avoids the accumulation of shrinkage stress. The rigid aromatic ring structure of the triazine ring restricts the free volume of the molecular chain, reducing the degree of curing shrinkage. Microwave-assisted in-situ generation technology of nano-silica effectively avoids nanoparticle agglomeration, enhances the interfacial bonding force between nanoparticles and the resin matrix, and reduces stress concentration and uneven interlayer leveling caused by agglomerated particles. In addition, ultraviolet light-plasma composite surface treatment and frequency conversion near-infrared rapid curing process further enhance surface activity and cross-linking efficiency, optimize shrinkage consistency during curing, significantly reduce dimensional errors in printed parts, and improve the in-situ fit and overall accuracy of the restoration.

[0017] 3. In summary, this invention effectively solves the performance defects of traditional dental 3D printing light-curing resins through innovative synthesis of core functional monomers, synergistic blending of multiple components, and special preparation processes. It significantly improves the mechanical properties, curing stability, and printing accuracy of the material, providing a reliable technical solution for high-precision and high-performance 3D printing of dental restoration models. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0019] Figure 1 The infrared spectra of the resins prepared in Example 3 and Comparative Examples 1-4 are shown. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Example 1: This example provides a method for preparing resin for UV 3D printing dental restoration models, including the following steps: Step 1: Synthesis of core functional units; 1.1 Synthesis of camphorquinone-modified acrylate prepolymer (Diels-Alder reaction, i.e., diene addition reaction). Reactants: camphorquinone (L-camphorquinone), acrylate monomers (methyl acrylate); Molar ratio: camphorquinone: acrylate = 1:1.2; The catalyst is a Lewis acid, used at 5% of the mass of camphorquinone; Solvent: Toluene / dichloroethane, volume 5 times the total volume of reactants; Add the reactants, catalyst and solvent to a three-necked flask and purge with nitrogen three times. Heat to 50°C and reflux in an oil bath, stirring at 200 rpm for 6 hours; The solvent was removed by vacuum distillation, and the residue was recrystallized twice with cyclohexane to obtain a pale yellow crystalline prepolymer, namely camphorquinone-modified acrylate prepolymer. 1.2 Synthesis of benzyloxazoline reactive diluent; Reactants: benzyl chloride, oxazoline (2-methyl-oxazoline); Molar ratio: benzyl chloride: oxazoline = 1:1.1; Solvent: N,N-dimethylformamide (DMF), the total mass of reactants accounts for 30% of the mass of solvent; Catalyst: Potassium carbonate, used at 15% of the mass of benzyl chloride; Add benzyl chloride, oxazoline, and DMF to the reaction vessel and stir to dissolve. Add potassium carbonate, heat to 80℃, and react for 2 hours (infrared monitoring shows the characteristic peak of the oxazoline ring at 1620 cm⁻¹). -1 (Intensity decrease) Potassium carbonate was removed by filtration, and DMF was recovered by vacuum distillation to obtain benzyloxazoline active diluent; 1.3 Synthesis of triazine-modified bisphenol A type epoxy resin; Reactants: Bisphenol A type epoxy resin, melamine; Molar ratio: epoxy resin: melamine = 3:1; Catalyst: p-Toluenesulfonic acid, used at 0.5% of the epoxy resin mass; Epoxy resin and melamine are added to a reaction vessel and heated to 80°C to melt. Add the catalyst and stir the reaction for 3 hours; Cooling to room temperature yields a pale yellow, viscous liquid, which is triazine-modified epoxy resin. Step 2: Blending of reactive diluent and epoxy resin; Raw materials: Triazine-modified epoxy resin, camphorquinone-modified acrylate prepolymer, benzyl oxazoline reactive diluent, styrene; Mass ratio: 45:15:10:30; Stir and mix at 50℃ and 300rpm, and disperse for 15min with the assistance of an ultrasonic disperser (200W power); Add 0.3% hydroquinone and continue ultrasonic dispersion for 5 minutes to obtain a blend. Step 3: Microwave-assisted in-situ generation of nano-silica; Raw materials: Tetraethyl orthosilicate (TEOS), blending solution; Molar ratio: TEOS: epoxy resin = 0.1:1; Catalyst: Dibutyltin dilaurate (1% TEOS mass); TEOS and the catalyst were added to the solution, mixed evenly, and then transferred to a microwave reactor. The reaction was carried out at 100W microwave power for 1 hour. When the viscosity of the system was 300mPa·s, the ethanol was removed by vacuum distillation for 5 minutes to obtain the nano-reinforced prepolymer. Step 4: Preparation of ultrasound-assisted MOF-loaded initiator; Raw materials: ZIF-8 (2-methylimidazolium zinc MOF), diphenyliodonium hexafluorophosphate; Load ratio: 0.2:1 (mass ratio); ZIF-8 and the initiator were added to anhydrous acetonitrile and treated in an ultrasonic cell disruptor (power 400W, frequency 20kHz) for 2 hours. Centrifugation (5000 rpm, 10 min) and vacuum drying (60 ° C, 2 h) yielded nanoscale dispersed MOF-supported initiators; Step 5: Ultraviolet-plasma composite surface treatment; The MOF-supported initiator and the nano-reinforced prepolymer were uniformly mixed by ultrasonic dispersion (400W power, 20kHz frequency, 5min treatment) to obtain the coating solution; the MOF-supported initiator accounted for 2wt% of the mass of the nano-reinforced prepolymer. Coating: The coating is applied using a slot coater (50μm thickness) and immediately transferred to an ultraviolet-plasma composite treatment chamber. UV parameters: light intensity 200mW / cm 2 Irradiation for 10 seconds (total energy 300 mJ / cm²) 2 ); Plasma-assisted: Simultaneous introduction of argon plasma (50W power, 5s processing time) to enhance surface activity and cross-linking efficiency; Step 6: Variable frequency near-infrared rapid curing; Light source: Adjustable power near-infrared laser (wavelength 1.3μm) Rapid heating phase: heating to 70℃ at a rate of 15℃ / min (power density 1.0W / cm³). 2 ), maintain for 5 minutes (activation of initial ring opening of oxazoline); Uniform curing section: temperature decreases to 5℃ / min and then increases to 110℃ (power density 0.5W / cm³). 2 Keep warm at 110℃ for 30 minutes; Cooling: Forced air cooling (wind speed 5m / s) to room temperature, control the cooling rate ≤10℃ / min to avoid internal stress.

[0022] Example 2: This example provides a method for preparing resin for UV 3D printing dental restoration models, including the following steps: Step 1: Synthesis of core functional units; 1.1 Synthesis of camphorquinone-modified acrylate prepolymer (Diels-Alder reaction, i.e., diene addition reaction). Reactants: camphorquinone (DL-camphorquinone), acrylate monomers (ethyl acrylate); Molar ratio: camphorquinone: acrylate = 1:1.5; The catalyst is Lewis acid, used in an amount equal to 10% of the mass of camphorquinone; Solvent: Toluene / dichloroethane, volume 10 times the total volume of reactants; Add the reactants, catalyst and solvent to a three-necked flask and purge with nitrogen three times. Heat to 100℃ and reflux in an oil bath, stirring at 300 rpm for 12 hours; The solvent was removed by vacuum distillation, and the residue was recrystallized three times with cyclohexane to obtain a pale yellow crystalline prepolymer, namely camphorquinone-modified acrylate prepolymer. 1.2 Synthesis of benzyloxazoline reactive diluent; Reactants: benzyl chloride, oxazoline (2-propyl-2-oxazoline); Molar ratio: benzyl chloride: oxazoline = 1:1.3; Solvent: N,N-dimethylformamide (DMF), the total mass of reactants accounts for 50% of the mass of solvent; Catalyst: Potassium carbonate, used at 20% of the mass of benzyl chloride; Add benzyl chloride, oxazoline, and DMF to the reaction vessel and stir to dissolve. Add potassium carbonate, heat to 120°C, and react for 3 hours; Potassium carbonate was removed by filtration, and DMF was recovered by vacuum distillation to obtain benzyloxazoline active diluent; 1.3 Synthesis of triazine-modified bisphenol A type epoxy resin; Reactants: Bisphenol A type epoxy resin, melamine; Molar ratio: epoxy resin: melamine = 5:1; Catalyst: p-Toluenesulfonic acid, used at 2% of the epoxy resin mass; Epoxy resin and melamine are added to a reaction vessel and heated to 120°C to melt. Add catalyst and stir to react for 4 hours; Cooling to room temperature yields a pale yellow, viscous liquid, which is triazine-modified epoxy resin. Step 2: Blending of reactive diluent and epoxy resin; Raw materials: Triazine-modified epoxy resin, camphorquinone-modified acrylate prepolymer, benzyl oxazoline reactive diluent, styrene; Mass ratio: 55:25:15:40; Stir and mix at 60℃ and 400rpm, and disperse for 20min with the assistance of an ultrasonic disperser (300W). Add 0.5% hydroquinone and continue ultrasonic dispersion for 10 min to obtain a blend. Step 3: Microwave-assisted in-situ generation of nano-silica; Raw materials: Tetraethyl orthosilicate (TEOS), blending solution; Molar ratio: TEOS: epoxy resin = 0.3:1; Catalyst: Dibutyltin dilaurate (2% TEOS by mass); TEOS and the catalyst were added to the solution, mixed evenly, and then transferred to a microwave reactor. The reaction was carried out at 150W microwave power for 2 hours. When the viscosity of the system was 500mPa·s, the ethanol was removed by vacuum distillation for 10 minutes to obtain the nano-reinforced prepolymer. Step 4: Preparation of ultrasound-assisted MOF-loaded initiator; Raw materials: ZIF-8 (2-methylimidazolium zinc MOF), diphenyliodonium hexafluorophosphate; Load ratio: 0.3:1 (mass ratio); ZIF-8 and the initiator were added to anhydrous acetonitrile and treated in an ultrasonic cell disruptor (power 500W, frequency 20kHz) for 3 hours. Centrifugation (5000 rpm, 10 min) and vacuum drying (60 ° C, 2 h) yielded nanoscale dispersed MOF-supported initiators; Step 5: Ultraviolet-plasma composite surface treatment; The MOF-supported initiator and the nano-reinforced prepolymer were uniformly mixed by ultrasonic dispersion (400W power, 20kHz frequency, 5min treatment) to obtain the coating solution; the MOF-supported initiator accounted for 5wt% of the mass of the nano-reinforced prepolymer. Coating: The coating is applied using a slot coater (200μm thickness), and the sample is immediately transferred to an ultraviolet-plasma composite treatment chamber. UV parameters: light intensity 250mW / cm 2 Irradiation for 20 seconds (total energy 500 mJ / cm²) 2 ); Plasma-assisted: Simultaneous introduction of argon plasma (100W power, 10s processing time) to enhance surface activity and cross-linking efficiency; Step 6: Variable frequency near-infrared rapid curing; Light source: Adjustable power near-infrared laser (wavelength 1.3μm) Rapid heating phase: heating to 80℃ at a rate of 20℃ / min (power density 1.5W / cm³). 2 ), maintain for 5 minutes (activation of initial ring opening of oxazoline); Uniform curing stage: temperature decreases to 8℃ / min and then increases to 120℃ (power density 0.8W / cm³). 2 Keep warm at 120℃ for 40 minutes; Cooling: Forced air cooling (wind speed 10m / s) to room temperature, control the cooling rate ≤10℃ / min to avoid internal stress.

[0023] Example 3: This example provides a method for preparing resin for UV 3D printing dental restoration models, including the following steps: Step 1: Synthesis of core functional units; 1.1 Synthesis of camphorquinone-modified acrylate prepolymer (Diels-Alder reaction, i.e., diene addition reaction). Reactants: camphorquinone (L-camphorquinone), acrylate monomers (ethyl acrylate); Molar ratio: camphorquinone: acrylate = 1:1.3; The catalyst is a Lewis acid, used at 8% of the mass of camphorquinone; Solvent: Toluene / dichloroethane, with a volume of 7 times the total volume of the reactants; Add the reactants, catalyst and solvent to a three-necked flask and purge with nitrogen three times. Heat to 80℃ and reflux in an oil bath, stirring at 240 rpm for 8 hours; The solvent was removed by vacuum distillation, and the residue was recrystallized three times with cyclohexane to obtain a pale yellow crystalline prepolymer, namely camphorquinone-modified acrylate prepolymer. 1.2 Synthesis of benzyloxazoline reactive diluent; Reactants: benzyl chloride, oxazoline (2-phenyl-2-oxazoline); Molar ratio: benzyl chloride: oxazoline = 1:1.2; Solvent: N,N-dimethylformamide (DMF), the total mass of reactants accounts for 45% of the solvent mass; Catalyst: Potassium carbonate, used at 18% of the mass of benzyl chloride; Add benzyl chloride, oxazoline, and DMF to the reaction vessel and stir to dissolve. Add potassium carbonate, heat to 113℃, and react for 3 hours; Potassium carbonate was removed by filtration, and DMF was recovered by vacuum distillation to obtain benzyloxazoline active diluent; 1.3 Synthesis of triazine-modified bisphenol A type epoxy resin; Reactants: Bisphenol A type epoxy resin, melamine; Molar ratio: epoxy resin: melamine = 4:1; Catalyst: p-Toluenesulfonic acid, used at 1.2% of the epoxy resin mass; Epoxy resin and melamine are added to a reaction vessel and heated to 100°C to melt. Add the catalyst and stir the reaction for 3.5 hours; Cooling to room temperature yields a pale yellow, viscous liquid, which is triazine-modified epoxy resin. Step 2: Blending of reactive diluent and epoxy resin; Raw materials: Triazine-modified epoxy resin, camphorquinone-modified acrylate prepolymer, benzyl oxazoline reactive diluent, styrene; Mass ratio: 52:21:13:37; Stir and mix at 58℃ and 380rpm, and disperse for 18min with the assistance of an ultrasonic disperser (power 260W); Add 0.4% hydroquinone and continue ultrasonic dispersion for 9 minutes to obtain a blend. Step 3: Microwave-assisted in-situ generation of nano-silica; Raw materials: Tetraethyl orthosilicate (TEOS), blending solution; Molar ratio: TEOS: epoxy resin = 0.2:1; Catalyst: Dibutyltin dilaurate (1.6% TEOS by mass); TEOS and the catalyst were added to the solution, mixed evenly, and then transferred to a microwave reactor. The reaction was carried out at 120W microwave power for 1.8h. When the viscosity of the system was 410mPa·s, the ethanol was removed by vacuum distillation for 8min to obtain the nano-reinforced prepolymer. Step 4: Preparation of ultrasound-assisted MOF-loaded initiator; Raw materials: ZIF-8 (2-methylimidazolium zinc MOF), diphenyliodonium hexafluorophosphate; Load ratio: 0.23:1 (mass ratio); ZIF-8 and the initiator were added to anhydrous acetonitrile and treated in an ultrasonic cell disruptor (power 470W, frequency 20kHz) for 2.5h. Centrifugation (5000 rpm, 10 min) and vacuum drying (60 ° C, 2 h) yielded nanoscale dispersed MOF-supported initiators; Step 5: Ultraviolet-plasma composite surface treatment; The MOF-supported initiator and the nano-reinforced prepolymer were uniformly mixed by ultrasonic dispersion (400W power, 20kHz frequency, 5min treatment) to obtain the coating solution; the MOF-supported initiator accounted for 4wt% of the mass of the nano-reinforced prepolymer. Coating: Apply coating using a slot coater (100μm thickness), then immediately proceed to the UV-plasma composite treatment chamber; UV parameters: light intensity 230mW / cm 2 Irradiation for 16 seconds (total energy 430 mJ / cm²) 2 ); Plasma-assisted: Simultaneous introduction of argon plasma (60W power, 9s processing time) to enhance surface activity and cross-linking efficiency; Step 6: Variable frequency near-infrared rapid curing; Light source: Adjustable power near-infrared laser (wavelength 1.3μm) Rapid heating phase: heating to 77℃ at a rate of 16℃ / min (power density 1.2W / cm³). 2 ), maintain for 5 minutes (activation of initial ring opening of oxazoline); Uniform curing stage: temperature decreases to 7℃ / min and then increases to 116℃ (power density 0.7W / cm³). 2 The temperature is maintained at 120℃ for only 34 minutes (by eliminating intermediate heat preservation, the total time is reduced by 60%). Cooling: Forced air cooling (wind speed 7m / s) to room temperature, control the cooling rate ≤10℃ / min to avoid internal stress.

[0024] Comparative Example 1: The difference between this comparative example and Example 3 is that ethyl acrylate was not modified by L-camphorquinone in step 1.1.

[0025] Comparative Example 2: The difference between this comparative example and Example 3 is that melamine-modified bisphenol A epoxy resin was not used in step 1.3.

[0026] Comparative Example 3: The difference between this comparative example and Example 3 is that microwave assistance was not used when preparing the nano-reinforced prepolymer in step 3.

[0027] Comparative Example 4: The difference between this comparative example and Example 3 is that: 1. In step 1.1, ethyl acrylate was not modified by L-camphorquinone; 2. The melamine-modified bisphenol A epoxy resin was not used in step 1.3; 3. Microwave assistance was not used in step 3.

[0028] Experimental Example 1: Infrared spectroscopy was performed on the resins prepared in Example 3 and Comparative Examples 1-4. The results are as follows: Figure 1 As shown; Example 3 has the following characteristic peaks: 1680-1720cm -1 (Strong, sharp): The stretching vibration peak of C=O in the camphorquinone structure.

[0029] 1630-1650cm -1 (Medium-strong, sharp): C=C double bond stretching vibration peak of acrylate monomers.

[0030] 1620cm -1 (Weak, broadened): The characteristic peak of the oxazoline ring in the benzyl oxazoline reactive diluent, but the peak intensity is significantly reduced due to the ring opening of oxazoline during the subsequent curing process.

[0031] Reason: Camphorquinone and ethyl acrylate form a conjugated structure via the Diels-Alder reaction, enhancing the absorption intensity of C=O and C=C. The oxazoline ring partially opens during the near-infrared curing stage, resulting in an absorption intensity of 1620 cm⁻¹. -1 The peak weakens.

[0032] 804cm -1 (Sharp): Characteristic absorption peak of the triazine ring.

[0033] 1250-1650cm -1 (Broad peaks): Stretching vibration peaks of C-NH-C and N-(C)3, originating from the triazine ring structure in melamine-modified epoxy resin.

[0034] Reason: Melamine reacts with epoxy resin to form a triazine ring, introducing a new heterocyclic structure that enhances the absorption in this region.

[0035] 1090cm -1(Strong, sharp): Stretching vibration peak of Si-O-Si bond, from microwave-assisted generated nano-silica.

[0036] 800cm -1 (Medium-strong, sharp): The bending vibration peak of the Si-O bond reflects the three-dimensional network structure of silicon dioxide.

[0037] Reason: Microwave-assisted hydrolysis and condensation of TEOS promotes the formation of uniformly dispersed nano-silica, which enhances the absorption intensity of Si-O-Si bonds.

[0038] 1500-1600cm -1 (Medium-strong, broad peak): The aromatic ring skeletal vibration peak of 2-methylimidazole in ZIF-8.

[0039] 236 nm (ultraviolet absorption): The characteristic absorption peak of diphenyliodonium hexafluorophosphate, but there is no obvious corresponding peak in the infrared spectrum.

[0040] Reason: The aromatic ring structure of ZIF-8 is located at 1500-1600 cm⁻¹ -1 Absorption occurs at the spectral density, while the infrared absorption of iodonium salt is weak and does not significantly affect the spectrum.

[0041] In Comparative Example 1, 1680-1720cm -1 Peak disappearance: lack of the C=O peak of camphorquinone.

[0042] 1630-1650cm -1 Peak intensity decreased: The C=C peak of ethyl acrylate was not conjugated with camphorquinone, resulting in weakened absorption.

[0043] 1620cm -1 Stronger peaks: The oxazoline ring was not affected by camphorquinone modification, and the degree of ring opening was relatively low.

[0044] Reason: The absence of camphorquinone structure leads to the loss of C=O and conjugated C=C peaks, resulting in a decrease in the ring-opening efficiency of the oxazoline ring.

[0045] In Comparative Example 2, 804cm -1 Peak disappearance: lack of triazine ring structure.

[0046] 1250-1650cm -1 Peak weakening: C-NH-C and N-(C)3 vibration peaks decreased.

[0047] 910cm -1 Peak enhancement: Characteristic peaks of epoxy groups in epoxy resin (not modified by melamine).

[0048] Reason: Melamine was not introduced, the triazine ring did not form, the epoxy group was retained, resulting in an enhanced epoxy peak.

[0049] In Comparative Example 3, 1090cm -1 The peak intensity decreased significantly: the formation of nano-silica was incomplete, and the Si-O-Si bonds were reduced.

[0050] 800cm -1 Peak broadening and weakening: silica agglomeration leads to structural disorder.

[0051] The viscosity peak shift in the system was due to the lack of microwave-assisted TEOS hydrolysis, resulting in uneven dispersion of nanoparticles.

[0052] Reason: Microwave-assisted hydrolysis and condensation of TEOS can accelerate the formation of silica. When not in use, the amount of silica generated is small and agglomerates, which leads to a weakening of the Si-O-Si peak.

[0053] In Comparative Example 4, 1680-1720cm -1 Peak disappearance: No camphorquinone C=O peak.

[0054] 804cm -1 Peak disappearance: No triazine ring is present.

[0055] 1090cm -1 Extremely weak peak: No microwave assistance, very little nano-silica.

[0056] 1620cm -1 Stronger peak: Oxazoline ring opening is insufficient.

[0057] Cause: The simultaneous absence of camphor quinone modification, epoxy resin modification, and microwave assistance leads to the loss of key functional group peaks and the loss of nano-reinforcement effect.

[0058] 2. The following data were measured on the resins prepared in Examples 1-3 and Comparative Examples 1-4: According to T / CAMDI 111-20232 "Additive Manufacturing Light-Cure Dental Prosthetic Resins", specimens (25mm × 2mm × 2mm) were prepared with three layout orientations: 0°, 45°, and 90°. Three-point bending test results: Flexural strength: XY plane strength (MPa) ≥ 120 MPa; Z-axis strength ≥ 85 MPa 100 Vickers hardness: The difference in hardness between the XY axis and the Z axis (%) ≤ 8%; 10 Using the density bottle method (ASTM-D792-2022), the density change before and after curing was compared, and the curing shrinkage rate (%) was calculated to be ≤1.8%. According to T / CAMDI 086-20222 "Additive Manufacturing Light-Cure Temporary Crown and Bridge Resins", a standard dental crown model was used for printing, and the marginal fit (μm) was measured to be ≤30μm; The results are shown in the table below:

[0059] Comparative Example 1: Acrylates modified with camphorquinone deficiency; The strength decreased because the stereobridged ring structure of camphorquinone was not introduced, and the acrylate polymerization rate increased. Multifunctional monomers preferentially crosslink to form phase-separated microdomains; Stress concentration leads to a decrease in Z-axis strength; Increased shrinkage: lack of steric hindrance inhibition effect of camphorquinone, uneven double bond conversion rate, accumulation of shrinkage stress in local over-crosslinked areas, and deterioration of precision: phase separation causes interlayer shrinkage difference, resulting in warping of printed parts and increased edge gaps; Comparative Example 2: Melamine-modified epoxy resin; Crosslinking network defects, such as the failure of the triazine ring to be integrated into the epoxy backbone, lead to a decrease in crosslinking point density and a decrease in flexural strength. Increased shrinkage: The absence of the rigid aromatic ring structure of the triazine ring leads to an increase in the free volume of the molecular chain, thereby exacerbating curing shrinkage; Interlayer bonding weakens: The lack of triazine ring synergy in the deep oxazoline ring opening results in insufficient Z-axis crosslinking. Comparative Example 3: Lack of microwave-assisted synthesis of nano-SiO2; Nanoparticle agglomeration: Conventional stirring preparation of SiO2 particle size results in stress concentration sources and increased intensity fluctuations; Interface bonding failure: Gaps exist at the interface between non-in-situ generated SiO2 and the resin, resulting in reduced hardness; Agglomerated particles lead to uneven interlayer leveling and increased adhesion error; Comparative Example 4 (completely missing): An imbalance in the reactivity ratio leads to a sparse cross-linked network and a sharp drop in strength; The shrinkage rate is significantly increased, the anisotropy ratio is increased, and the crown margin gap is significantly increased.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a resin for UV 3D printing dental restoration models, characterized in that, Includes the following steps: Step 1: Synthesis of core functional units; 1.1 Synthesis of camphorquinone-modified acrylate prepolymer; Camphorquinone, acrylate monomers, and Lewis acid catalyst are added to a solvent, and the mixture is heated and stirred to react. Solvent was removed under reduced pressure to obtain camphorquinone-modified acrylate prepolymer; 1.2 Synthesis of benzyloxazoline reactive diluent; Benzyl chloride and oxazoline, along with the catalyst and solvent N,N-dimethylformamide, are mixed, heated, and filtered to remove potassium carbonate, yielding a benzyl oxazoline active diluent. 1.3 Synthesis of triazine-modified bisphenol A type epoxy resin; Bisphenol A type epoxy resin, melamine, and catalyst are heated and melted; Cool to room temperature to obtain triazine-modified epoxy resin; Step 2: Blending of reactive diluent and epoxy resin; Triazine-modified epoxy resin, camphorquinone-modified acrylate prepolymer, oxazoline reactive diluent, and styrene were mixed and ultrasonically dispersed; hydroquinone was added to obtain a blend. Step 3: Microwave-assisted in-situ generation of nano-silica; After uniformly mixing tetraethyl orthosilicate, the blend liquid, and the catalyst, the mixture is microwaved to remove ethanol, thus obtaining a nano-reinforced prepolymer. Step 4: Preparation of ultrasound-assisted MOF-loaded initiator; ZIF-8 and the initiator were added to anhydrous acetonitrile, ultrasonically treated, and separated and dried to obtain a nanoscale dispersed MOF-supported initiator. Step 5: Ultraviolet-plasma composite surface treatment; MOF-supported initiator and nano-reinforced prepolymer are uniformly mixed to obtain a coating solution, which is then irradiated with ultraviolet light; Step 6: Variable frequency near-infrared rapid curing yields resin for UV 3D printing of dental restoration models.

2. The method for preparing the resin for UV 3D printing dental restoration models according to claim 1, characterized in that, Step 1.1 specifically involves adding camphorquinone and acrylate monomers in a molar ratio of 1:1.2-1.5, along with 5-10% by mass of Lewis acid catalyst (camphorquinone) to a solvent of toluene / dichloroethane, wherein the volume of the solvent is 5-10 times the total volume of the reactants. Heat to 50-100℃ and reflux in an oil bath, stirring at 200-300 rpm for 6-12 hours; The solvent was removed by vacuum distillation, and the residue was recrystallized from cyclohexane 2-3 times to obtain a pale yellow crystalline prepolymer, namely camphorquinone-modified acrylate prepolymer.

3. The method for preparing the resin for UV 3D printing dental restoration models according to claim 1, characterized in that, Step 1.2 specifically involves: adding benzyl chloride and oxazoline in a molar ratio of 1:1.1-1.3, along with potassium carbonate as a catalyst and N,N-dimethylformamide as a solvent, to a reaction vessel, mixing and stirring to dissolve, heating to 80-120℃, and reacting for 2-3 hours. The total mass of the reactants accounts for 30-50% of the mass of the solvent N,N-dimethylformamide; The amount of potassium carbonate used is 15-20% of the mass of benzyl chloride; Potassium carbonate was removed by filtration, and DMF was recovered by vacuum distillation to obtain benzyloxazoline active diluent.

4. The method for preparing the resin for UV 3D printing dental restoration models according to claim 1, characterized in that, Step 1.3 specifically involves adding bisphenol A epoxy resin and melamine in a molar ratio of 3-5:1, along with toluenesulfonic acid as a catalyst, to a reaction vessel and heating the mixture to 80-120°C to melt it. The reaction was stirred for 3-4 hours, and the amount of catalyst used was 0.5-2% of the mass of the epoxy resin. Upon cooling to room temperature, a pale yellow viscous liquid is obtained, which is triazine-modified epoxy resin.

5. The method for preparing resin for UV 3D printing dental restoration models according to claim 1, characterized in that, Step 2 specifically involves mixing triazine-modified epoxy resin, camphorquinone-modified acrylate prepolymer, oxazoline reactive diluent, and styrene in a mass ratio of 45-55:15-25:10-15:30-40 at 50-60°C and 300-400 rpm, and then dispersing the mixture for 15-20 minutes with the assistance of an ultrasonic disperser with a power of 200-300W. Add 0.3-0.5% hydroquinone and continue ultrasonic dispersion for 5-10 minutes to obtain a blend.

6. The method for preparing the resin for UV 3D printing dental restoration models according to claim 1, characterized in that, Step 3 specifically involves: mixing tetraethyl orthosilicate and the blend solution with a molar ratio of 0.1-0.3:1, and 1-2% of the mass of TEOS catalyst dibutyltin dilaurate, and then transferring the mixture into a microwave reactor. React at 100-150W microwave power for 1-2 hours. When the system viscosity is 300-500mPa·s, remove ethanol by vacuum distillation for 5-10 minutes to obtain nano-reinforced prepolymer.

7. The method for preparing the resin for UV 3D printing dental restoration models according to claim 1, characterized in that, Step 4 specifically involves adding ZIF-8 and the initiator diphenyliodonium hexafluorophosphate at a mass ratio of 0.2-0.3:1 to anhydrous acetonitrile and treating the mixture in an ultrasonic cell disruptor with a power of 400-500W for 2-3 hours. Centrifugation and vacuum drying yielded nanoscale dispersed MOF-supported initiators.

8. A resin prepared by the method for preparing a UV 3D printed dental restoration model according to any one of claims 1-7.

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