Preparation method and application of light-cured resin added with modified nano silicon dioxide

Abstract

The invention belongs to but not limited to the technical field of light-cured resin, and discloses a preparation method and application of light-cured resin added with modified nano silicon dioxide. The light-cured resin uses polyethylene glycol and acrylate-200 as a polymeric monomer; 2-isopropyl-9H-thioxanthene-9-ketone is used as a light absorbent to control the intensity of a light source and the light penetration depth; diphenyl (2, 4, 6-trimethylbenzoyl) phosphine oxide is used as a photoinitiator to promote a polymerization process; vinyl modified nano silicon dioxide is used as a photo-crosslinking agent to form a compact crosslinking network, the crosslinking degree is enhanced, and meanwhile, the mechanical property of the resin is improved by a rigid nano material. According to the novel light-cured resin provided by the invention, the modified nano silicon dioxide is used as a cross-linking agent in the light-cured resin, so that the mechanical property, the light-curing speed and the printing precision of the resin can be improved, and good biocompatibility can be kept, thereby widening the application of the resin in the fields of medical treatment and high-precision manufacturing.

Description

Technical Field

[0001] The present invention belongs to but is not limited to the technical field of photocurable resins, and in particular relates to a preparation method and application of a photocurable resin added with modified nano-silicon dioxide. Background Art

[0002] With the rapid development of 3D printing technology, photocurable resins have been widely used in many applications such as rapid prototyping, prototype manufacturing and medical fields. In the 3D printing process, photocurable resins use ultraviolet light to initiate the polymerization reaction of the resin, thereby quickly forming a solid structure. In recent years, with the continuous improvement of requirements for printing accuracy, speed and mechanical properties, the development of new photocurable resins has become a research hotspot.

[0003] Existing photocurable resins are mostly composed of traditional monomers and initiators. Although they can meet certain molding requirements, they still have certain limitations in terms of mechanical properties, photocuring speed and printing accuracy. In order to solve these problems, researchers have tried to improve the performance of resins by introducing different fillers or additives. For example, nanomaterials have the potential to enhance the mechanical properties of photocurable resins, improve photocuring speed and improve printing accuracy due to their unique physical and chemical properties. In particular, nanosilica (SiO2), as a common filler, has been widely used in resin modification due to its excellent mechanical strength, thermal stability and compatibility.

[0004] However, due to the lack of functional groups on the surface of traditional nano-silica, it usually leads to weak interfacial bonding with the resin matrix, affecting the comprehensive performance of the composite material. In order to improve this problem, researchers have treated nano-silica through surface modification technology, among which vinyl triethoxysilane (VTES) modification has been proven to be an effective modification method. Vinyl triethoxysilane introduces vinyl groups on the surface of nano-silica, which can not only enhance the chemical bonding between nano-silica and the resin matrix, but also improve the efficiency of the photocuring reaction.

[0005] Although some studies have explored nano-silica modified resins, the following problems still exist: First, the existing photocurable resins have the problem of uneven resin curing after adding nano-silica, which limits their application in the biomedical field; Second, the surface properties of nano-silica and resin are different, resulting in nano-silica covered with surface silanol bonds being difficult to disperse in fat-soluble resins. The dispersibility and stability still need to be further improved through surface hydrophobic modification to ensure high precision and high efficiency of the resin in the 3D printing process.

[0006] Therefore, there is an urgent need for a new photocurable resin that can improve the mechanical properties, photocuring speed and printing accuracy of the resin while maintaining good biocompatibility through the introduction of modified nano-silica, thereby broadening its application in the fields of medicine and high-precision manufacturing. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention provides a method for functionally modifying the surface of silicon dioxide nanospheres so that they can be used as a cross-linking agent and applied to three-dimensional printing in a photocurable resin.

[0008] The present invention is achieved by providing a method for preparing a photocurable resin with modified nano-silica added thereto, wherein the photocurable resin uses polyethylene glycol acrylate-200 (PEGDA200) as a polymerization monomer; 2-isopropyl-9H-thioxanthen-9-one (ITX) as a light absorber to control the light source intensity and light penetration depth; diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) as a photoinitiator to promote the polymerization process; synthetic vinyl-modified nano-silica (V-SNP) as a photocrosslinking agent to form a dense crosslinking network and enhance the crosslinking degree, while the rigid nano-material improves the mechanical properties of the resin; The method for preparing the photocurable resin added with modified nano-silicon dioxide comprises weighing the above raw materials, stirring and dissolving them, and performing ultrasonic dispersion.

[0009] Furthermore, the preparation method of the vinyl-modified nano-silica (V-SNP) comprises: Step 1, add anhydrous ethanol to a round-bottom flask, the addition amount is 50-300 ml, preferably 143 ml; add deionized water 1-10 ml, add ammonia water (25%) 1-20 ml, preferably 8 ml; Step 2, heating the oil bath to 40-80°C, preferably 65°C. When the temperature reaches 65°C, add 2-8ml, preferably 6ml, of tetraethyl orthosilicate (TEOS) and react for 0.5-4h, preferably 2h. Step 3, adding vinyl triethoxysilane (VTES) in an amount of 20%-50%, preferably 40%, of the volume fraction of tetraethyl orthosilicate (TEOS), and continuing the reaction for 2 hours to obtain vinyl-modified nano-silica (V-SNP).

[0010] Furthermore, the amount of ITX added to the photocurable resin is 0.5%-3% of the mass volume fraction of PEGDA200.

[0011] Furthermore, the added amount of diphenyl (2, 4, 6-trimethylbenzoyl) phosphine oxide (TPO) is 0.1%-0.5% of the mass volume fraction of PEGDA200.

[0012] Furthermore, the amount of the vinyl-modified nano-silica (V-SNP) added is 0.5%-5% of the mass volume fraction of PEGDA200.

[0013] Further, the mixture was dissolved by stirring for 2 h and ultrasonically dispersed for 15 min.

[0014] Furthermore, Solidworks (2019b) was used for 3D modeling, and the files were exported to STL format and imported into the slicing software, and the sliced ​​files were imported into the 3D printer for printing.

[0015] Another object of the present invention is to provide a photocurable resin prepared by a method for preparing a photocurable resin with added modified nano-silicon dioxide.

[0016] Another object of the present invention is to provide an application of the photocurable resin in 3D printing.

[0017] Furthermore, the three-dimensional printing includes 3D printing mechanical tensile and compression models, 3D printing microfluidic chips, 3D printing biological microneedles, etc.

[0018] First, the present invention uses silica material as a crosslinking agent. After modifying the surface with photocurable groups, it has the ability to photopolymerize and participate in the crosslinking network of PEGDA200. It has been proven that a large number of crosslinking sites modified on the surface of nano-silica promote the process of photopolymerization and accelerate the speed of 3D printing. The microneedle printing experiment proves that the resin improves the printing accuracy. Due to the addition of rigid nano-silica material, the performance of the resin itself has been greatly improved. The printed material has significantly improved mechanical properties, such as compressive strength and hardness. Most importantly, the strong physical adsorption ability of the nano-material itself and the fixation of toxic small molecule monomers after surface modification reduce the toxicity of the material and expand the direct cell application field.

[0019] The present invention solves the problems of insufficient mechanical properties, poor uniform dispersibility and low photopolymerization efficiency of photocurable resin in the prior art by optimizing the preparation conditions of vinyl-modified nanosilica (V-SNP) and the composition ratio of photocurable resin. The uniform synthesis of nanosilica particles is achieved by controlling the ratio of anhydrous ethanol, deionized water and ammonia water and the reaction temperature (40-80°C); the surface functionalization modification by vinyl triethoxysilane (VTES) improves the photosensitive reaction activity of the particles and the dispersibility in the resin matrix. In addition, by adding photoinitiators ITX and TPO and V-SNP to PEGDA200 at a specific mass volume fraction, the curing rate and mechanical properties of the resin are optimized, overcoming the technical bottlenecks of slow curing speed, uneven filler and low molding precision of traditional photocurable resin.

[0020] The present invention significantly improves the comprehensive performance of the material by combining nano-scale fillers with photocurable resins. The prepared photocurable resin has high strength, high toughness and excellent dimensional stability, meeting the dual requirements of material mechanical properties and printing accuracy in 3D printing. By combining ultrasonic dispersion and high-efficiency initiator systems, the present invention further improves the uniformity and photopolymerization efficiency of the resin system, reduces the structural defects and errors existing in traditional resins, significantly improves the reproducibility and application range of printed products, and provides technical support for the application of photocurable resins in high-end fields such as precision manufacturing and biomedicine.

[0021] Second, the expected benefits and commercial value of the technical solution of the present invention after transformation are: The technical solution of the present invention provides a photocurable resin with excellent mechanical properties, fast photocuring ability, good printing accuracy and no cytotoxicity, which has broad application prospects, especially in the fields of three-dimensional printing, personalized medical devices, precision manufacturing, etc. This resin not only improves the performance of existing photocurable resins, but also has potential in the fields of biomedicine and bioprinting due to its non-cytotoxicity, and can meet the application requirements of medical, dental, orthopedic and other fields that require high biocompatibility of materials. After commercialization, it can meet the needs of rapid prototyping and high-precision printing, and is expected to bring significant market value in industries such as biomedicine, 3D printer accessories manufacturing, precision model making, microfluidic biochips, etc., with high market demand and economic benefits.

[0022] Third, the present invention proposes a photocurable resin system prepared and applied based on vinyl-modified nano-silica (V-SNP), which solves the problem of insufficient mechanical properties and stability of photocurable resins in the prior art. By introducing V-SNP into the photocurable resin, the mechanical strength, toughness and shrinkage control ability of the system during the photocuring process are significantly improved. At the same time, the addition ratio of the photoinitiator (ITX and TPO) is optimized to ensure that the resin has high photoreaction efficiency and uniformity during the curing process.

[0023] The present invention optimizes the preparation process and addition amount of V-SNP, clarifies the range and preferred values ​​of reaction conditions (such as temperature 65°C, ratio of TEOS to VTES 6 ml and 40%), and achieves the best balance between mechanical properties and photoreaction properties through the addition ratio of the photocuring system (such as ITX 0.5%-3%, TPO 0.1%-0.5%). In addition, through reasonable stirring and ultrasonic dispersion steps, the uniform distribution of V-SNP in PEGDA200 is ensured, the problem of easy agglomeration of nanoparticles is overcome, thereby improving the transparency and mechanical properties of the resin system.

[0024] Compared with traditional resin systems, the photocurable resin of the present invention exhibits higher tensile strength and fracture toughness after adding V-SNP, while reducing the curing shrinkage rate and improving the dimensional accuracy and stability of the 3D printed structure. By introducing the process of combining Solidworks modeling with 3D printing, the present invention achieves high-precision printing of complex structures and provides a new solution for the application of functional photocurable resins in medical devices, optical components and high-precision manufacturing. This comprehensive technological innovation fills the gaps in the performance and application fields of traditional photocurable resins and has significant industrial value and technological advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a flow chart of the preparation method of vinyl-modified nano-silica provided in an embodiment of the present invention; Figure 2 1 is a SEM image of the nano-silicon dioxide before and after modification provided by an embodiment of the present invention; Figure 3 It is a schematic diagram of the effect of adding nano silicon dioxide before and after modification on resin molding provided by an embodiment of the present invention; Figure 4 This is a toxicity test diagram of V-SNP added at different contents compared with a molecular cross-linking agent provided in an embodiment of the present invention; Figure 5 This is a microscopic comparison of the needle tip of the microneedle printing before and after modification provided by the embodiment of the present invention; Figure 6 It is a V-SNP and SNP dispersion diagram provided by an embodiment of the present invention; Figure 7 is a SEM image provided by an embodiment of the present invention; Figure 8 is a tensile stress-strain curve of a material with added V-SNP provided in an embodiment of the present invention; Fig. 9 It is a 2d and 3d observation diagram of cell culture provided by an embodiment of the present invention; Fig.10 This is a printing effect diagram of the resin provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] The embodiment of the present invention provides a preparation method of a photocurable resin added with modified nano-silica, wherein the surface of the nano-silica is modified by vinyl triethoxysilane to obtain nano-silica with vinyl functional groups, so that the nano-silica is used as a crosslinking agent in the photocurable resin and can be stably dispersed in a fat-soluble solvent, the photocurable resin uses polyethylene glycol and acrylate-200 (PEGDA200) as a polymerization monomer, 2-isopropyl-9H-thioxanthen-9-one (ITX) as a light absorber to control the light source intensity and light penetration depth, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) as a photoinitiator to promote the photopolymerization process, and the addition of vinyl-modified nano-silica (V-SNP) solves the problems in the prior art, thereby obtaining a new type of photocurable resin, effectively improving the comprehensive performance of the resin, and expanding the direct application in the cell field.

[0028] The method for preparing the photocurable resin added with modified nano-silicon dioxide comprises fully stirring the above raw materials and then ultrasonicating them.

[0029] like Figure 1 As shown, a method for preparing a vinyl-modified nano-silica (V-SNP) provided in an embodiment of the present invention comprises: S101, add 50-300 ml of anhydrous ethanol, preferably 143 ml, to a round-bottom flask; add 1-10 ml of deionized water and 1-20 ml of ammonia water (25%), preferably 8 ml of ammonia water; S102, heating the oil bath to 40-80°C, preferably 65°C, adding 2-8ml, preferably 6ml, of tetraethyl orthosilicate (TEOS) when the temperature reaches 65°C, and reacting for 0.5-4h, preferably 2h; S103, adding vinyl triethoxysilane (VTES) in an amount of 20%-50%, preferably 40%, of the volume fraction of tetraethyl orthosilicate (TEOS), and continuing the reaction for 2 hours to obtain vinyl-modified nano-silica (V-SNP).

[0030] The added amount of ITX in the photocurable resin provided in the embodiment of the present invention is 0.5%-3% of the mass volume fraction of PEGDA200.

[0031] The added amount of diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) provided in the embodiment of the present invention is 0.1%-0.5% of the mass volume fraction of PEGDA200.

[0032] The added amount of the vinyl-modified nano-silica (V-SNP) provided in the embodiment of the present invention is 0.5%-5% of the mass volume fraction of PEGDA200.

[0033] The stirring dissolution provided in the embodiment of the present invention is 2 hours, and the ultrasonic dispersion is 15 minutes.

[0034] An embodiment of the present invention provides 3D modeling using Solidworks (2019b), exporting the file into STL format and then importing it into slicing software, and then importing the sliced ​​file into a 3D printer for printing.

[0035] The present invention provides a method for preparing vinyl-modified nano-silica (V-SNP), and the synthesis and surface vinyl functionalization of silica particles are achieved by a sol-gel method. First, anhydrous ethanol is used as a solvent, and deionized water and ammonia water are added to form an alkaline catalytic system, which is heated to a target temperature in an oil bath. Tetraethyl orthosilicate (TEOS) undergoes hydrolysis and condensation reactions in this system to form nano-silica particles. Subsequently, vinyl triethoxysilane (VTES) is added to achieve surface vinyl modification of the silica particles, thereby preparing nano-silica (V-SNP) with photosensitivity.

[0036] The main components of the photocurable resin include polyethylene glycol diacrylate (PEGDA200), initiator and modified filler. Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) and isopropylthioxanthone (ITX) are added to PEGDA200 at a certain mass volume fraction as initiators to enhance its photosensitivity. Vinyl-modified nanosilica (V-SNP) is used as a functional filler, which is fully stirred and mixed with PEGDA200 and dispersed by ultrasound to ensure that the filler is evenly distributed in the matrix resin, thereby giving the photocurable resin higher mechanical properties and stability.

[0037] Solidworks (2019b) was used to design the three-dimensional structural model, and the model file was exported to STL format and then imported into the slicing software for processing. The slicing software decomposed the model into a layered structure and generated a printing path file that can be recognized by the 3D printer. The light-curing resin is cured and superimposed layer by layer through the precise control of the 3D printing equipment. PEGDA200 is used as the base resin, combined with photoinitiator and vinyl-modified nano-silica to ensure that the resin is quickly polymerized and cured under ultraviolet light during the printing process, thereby achieving high-precision and high-performance 3D printed products.

[0038] By optimizing the composition ratio of the photocurable resin, the introduction of V-SNP significantly improves the mechanical properties, heat resistance and dimensional stability of the material, while maintaining the excellent printing accuracy of the photocurable resin. The products obtained by 3D printing have broad application potential in many fields, such as precision manufacturing, biomedical devices and microfluidic chips. In addition, the preparation and printing method of the present invention has simple process, adjustable material properties, can meet the needs of high-performance 3D printing materials, and provides a new solution for the application expansion of photocurable resins.

[0039] The present invention prepares vinyl-modified nano-silica (V-SNP) by a sol-gel method. First, in a mixed solution of anhydrous ethanol, deionized water and ammonia water, the solution is heated by an oil bath to maintain the stability of the solution and provide a suitable reaction environment. Subsequently, tetraethyl orthosilicate (TEOS) is added as a silicon source to generate primary silicon oxide particles through hydrolysis and condensation reactions. Next, vinyl triethoxysilane (VTES) is added, and its vinyl properties are utilized to covalently bond and modify the surface of the generated silicon oxide particles, thereby giving the surface of the nanoparticles vinyl functional groups to form uniform and stable V-SNPs.

[0040] The prepared V-SNP nanoparticles were added to the PEGDA200-based photocurable resin at a mass volume fraction of 0.5%-5%. To ensure the uniform dispersion of V-SNP, a treatment process of stirring and dissolving for 2 hours and ultrasonic dispersion for 15 minutes was adopted. This method promotes the initial dispersion of nanoparticles through mechanical stirring, and uses ultrasonic waves to break up agglomerates, so that V-SNP is evenly distributed in the resin matrix, further improving the mechanical properties and optical transparency of the photocurable resin, and providing a stable material basis for subsequent 3D printing.

[0041] ITX and TPO are added to the photocurable resin formula as a dual photoinitiator system. Among them, the addition amount of ITX is 0.5%-3% of the mass volume fraction of PEGDA200, and TPO is 0.1%-0.5%. TPO, as the main initiator, generates free radicals under UV light to start the photopolymerization reaction; ITX, as a photosensitizer, can extend the life of free radicals and improve the curing efficiency. The synergistic effect of the dual photoinitiator system ensures the rapid curing of the resin under light, controls the curing shrinkage, and significantly improves the dimensional accuracy and mechanical properties of the 3D printed model.

[0042] The 3D model was designed based on Solidworks (2019b) software. After the design was completed, the file was exported to STL format and imported into the slicing software for layering. The sliced ​​data was transmitted to the 3D printer through the interface. During the printing process, the prepared photocurable resin was used as the printing material, and the resin was cured layer by layer by UV light source to form a high-precision three-dimensional structure model. Since the addition of V-SNP enhances the strength and toughness of the material, this method is not only suitable for industrial parts manufacturing, but also can be used in high-demand fields such as medical devices and optical components.

[0043] like Figure 3 Example 1: Preparation of photocurable resin for 3D printing Take 143 ml of anhydrous ethanol as solvent, add 8 ml of ammonia water (25%) and 3 ml of deionized water, stir and heat to 60 ° C, add 6 ml of TEOS and react for 2 hours, add 1.5 ml of VTES, continue to react for 2 hours, filter, wash and dry to obtain V-SNP, weigh 2% of V-SNP with a mass volume fraction, 2% of ITX, and 0.5% of TPO, stir and dissolve for 2 hours, and ultrasonically disperse for 15 minutes to obtain a resin curing precursor solution.

[0044] like Figure 4 Example 2: 3D printing mechanical tensile and compression model The photocurable resin was synthesized and configured by the method in Example 1; and different concentrations of resin were added according to different V-SNP addition ratios (0.5%, 1%, 2%, 3%, and 4%), and a mechanical tensile and compressive model was modeled in Solidworks (2019b). The slice file was exported to the MSLA (mask stereolithography) printer Elegoo Mars4Ultra, with a bottom layer exposure of 65 s, a layer exposure of 4 s, a lifting speed of 75 mm / min, and a lifting distance of 2 mm. The printed model was cured under a 405 nm ultraviolet post-curing lamp for 8 h to obtain a dumbbell-shaped tensile model and a cylindrical compression model with a pre-designed structure.

[0045] Example 3: 3D printed microfluidic chip The photocurable resin was synthesized and configured by the method in Example 1; and the resin was added according to the optimal ratio. A microfluidic chip model was modeled in Solidworks (2019b), and the slice file was exported to the MSLA printer Elegoo Mars4Utral. The bottom layer was exposed for 65 s, the layer was exposed for 4 s, the lifting speed was 75 mm / min, and the lifting distance was 2 mm. The printed model was cured under a 405 nm ultraviolet post-curing lamp for 8 h to obtain a microfluidic chip model with a pre-designed structure.

[0046] like Figure 5 Example 4: 3D Printing Biological Microneedles The photocurable resin was synthesized and configured by the method in Example 1; and the resin was added according to the optimal ratio. The microfluidic chip model was modeled in Solidworks (2019b), and the slice file was exported to the MSLA printer Elegoo Mars4Utral. The bottom layer exposure was 65 s, the layer exposure was 4 s, the lifting speed was 75 mm / min, the lifting distance was 2 mm, and the printed model was cured under a 405 nm ultraviolet post-curing lamp for 8 h to obtain a microneedle model with a pre-designed structure.

[0047] 1. Specific application fields or related products of the present invention.

[0048] 1. 3D printing materials The photocurable resin of the present invention can be widely used in three-dimensional printing technology, especially in the manufacture of high-precision models. Since the resin has fast photocuring ability and excellent mechanical properties, it can greatly improve the molding efficiency and product quality of 3D printing. Specific applications include but are not limited to high-precision industrial prototype design, rapid prototyping of complex structural parts, and the manufacture of precision assembly parts.

[0049] 2. Medical models and personalized medical devices Since the photocurable resin of the present invention has the property of being non-cytotoxic, it can be used to print precise models and personalized medical devices in the medical field. For example: Customized dentures, dental restoration models, and precision human anatomical models for surgical planning 3. Bioprinting and tissue engineering The resin of the present invention is suitable for the field of bioprinting due to its non-cytotoxicity and excellent mechanical properties. For example, when printing biological scaffold materials, it can support cell growth and provide the necessary mechanical strength for constructing tissue engineering scaffolds, skin repair materials and other biomedical applications.

[0050] 4. Manufacturing of high-performance optical components and microstructures The high curing accuracy of the present invention makes it suitable for the manufacture of microstructures in the optical field, such as complex lenses, diffractive optical elements, microfluidic chips, etc. These structures require extremely high surface smoothness and precision, and the photocurable resin of the present invention can meet such requirements and improve printing efficiency.

[0051] 2. Relevant evidence of the technical effects obtained by the embodiments of the present invention.

[0052] PEGDA-200 is an oily molecule with a large number of double bonds. The presence of double bonds makes it difficult to disperse SNPs with silanol bonds on the surface. Therefore, V-SNPs with vinyl modified surfaces theoretically have stronger dispersibility than SNPs. Figure 6(a) shows the dispersion of two nanoparticles in water. It can be seen that SNP has strong dispersibility in water due to the presence of silanol bonds. Compared with V-SNP, it does not dissolve and disperse in water even under strong ultrasonic conditions, which shows the difference in surface properties of the two nanoparticles. Through modification, a lipid-soluble nanomaterial is obtained, such as Figure 6 As shown in (b), V-SNP is evenly dispersed in PEGDA-200. In 3D printing, the uniformity of the resin material is very important and determines the overall printing effect. For the resin added with V-SNP, the concentrations of 0.5%, 1%, 2%, 3%, and 4% (w / v) were set on the basis of avoiding the deposition of a large number of nanospheres, as shown in Figure 6 (b), No. 1 is PEGDA200, a transparent oily substance, 2 is a resin with PETTA / PETTA added, which is oily and transparent, and groups 3-7 are resins with modified nanospheres added. It can be observed that with the addition of nanospheres, they present a gradient milky white color and have good dispersibility.

[0053] First, the present invention compares the curing effects of the three materials. Using a mold, under the same mass concentration conditions, irradiation is performed under a 405nm UV lamp for 30 minutes. Since the molecular cross-linking agent generates a large amount of heat during the polymerization process and there is no medium to disperse the heat, local overheating occurs, thus generating a large number of cavities in the sample, which has a certain impact on the stability and molding rate of the printing process. SEM observations Figure 7 It can be seen that the cross-section surface is smooth, and the addition of SNP destroys the cross-linking environment and there is no cross-linking site itself, so the resin is broken during the post-processing process. From the SEM cross-section, it can be found that a large number of SNPs are locally aggregated, which is the reason for its fragility. However, V-SNP is a fat-soluble nanomaterial that not only has better dispersibility in fat-soluble resins, but also its surface vinyl photocuring groups provide more cross-linking sites. The addition of V-SNP not only stabilizes the curing process, but also provides a heat transfer medium, reduces the thermal effect during the curing process, and avoids the excessive photopolymerization reaction of a certain part to produce cavities. It can be seen from the SEM image of the cross-section, such as Figure 2 It was observed that the dispersion in the resin was relatively uniform and there was very little agglomeration.

[0054] The tensile stress-strain curve of the material with V-SNP added is shown in Figure 8As shown, in general, among the different contents of V-SNP, the 2% group showed relatively good tensile strength, which was related to the large number of cross-linking sites modified on the surface. Compared with the resin through the molecular cross-linking agent, the modified material increased by about 40%, and the compressive strength was better. Since nano-silica is a high-rigidity material, the compressive strength was significantly improved. Similar to the previous report, with the addition of nanospheres, especially at 4%, the tensile and compressive properties decreased. This is because the addition of a large amount of high-rigidity materials destroyed the uniformity of the material, resulting in excessive or poor local stress, and local aggregation prevented local cross-linking. Therefore, a suitable concentration is crucial, which is why the addition concentration is controlled below 4%. In addition, the resin with added V-SNP showed better toughness and had a positive effect on the molding rate and printing speed of the printing. Finally, the hardness of the material was tested. Compared with the control group, there was a slight increase, with a maximum hardness of 98HA. This is also because of the addition of high-rigidity nano-silica. Therefore, the control group of the molecular cross-linking agent has a greater hardness. As Figure 8 (i) shown.

[0055] In order to conduct cytotoxicity experiments on materials, a co-culture method was used. First, a ring structure suitable for a 96-well plate was printed out by a 3D printer, and then a CCK-8 experiment was performed after sterilization. According to previous reports, although the cell survival rate was within the specified range and was around 80%, the material still had slight cytotoxicity. However, for microfluidic micron-scale experiments, even slight cytotoxicity can have a greater impact, especially for some environmentally sensitive cells, which are uncertain. Fig. 9 As shown in (a) and (b), the cell culture was observed for 2d and 3d. The cell activity of the material without V-SNP added decreased, while the cell activity of the material using the nano cross-linker showed a positive growth trend, and the cell survival rate was almost no significant difference from the control group. The maximum cell survival rate was 109%. In addition, the present invention observed that the addition of different concentrations of nanomaterials did not change the activity of the cells. The addition of lower concentrations of nanomaterials has fixed the free monomers, whether by physical adsorption or free radical polymerization, so the addition of more non-toxic nanoparticles will not affect the activity.

[0056] Finally, the present invention experiments on the printing effect of the resin, tests the minimum printing time of the two resins, and observes whether the incorporation of V-SNPs with a large number of cross-linking sites improves the photopolymerization efficiency. The results show that only 1.2s of layer exposure is required to complete the printing of the predetermined structure, while the control group requires a minimum of 1.8s. For the final molding effect, the present invention selects 1.5s for exposure, and the effect is as follows Fig.10As shown in the figure, after the same post-treatment, V-SNP has a clearer structure display, while cracks appear on the surface of the control group. This is because the minimum printing time was not reached. This also confirms that the addition of V-SNP can accelerate the printing process and improve the printing molding effect.

[0057] At the same time, in order to prove the application in biomaterials, combined with the previous material characterization data, the present invention conducted a microneedle printing experiment to see if it has a better printing effect. The results show that the resin with modified nanospheres added not only has a faster printing speed, but also improves the printing accuracy to a certain extent, reduces the instability of printing, and improves the molding rate of printing. Fig.10 As shown in (a), the unmodified resin on the left has certain printing defects, and the failure rate of printing the higher-level needle tip is very high. The resin with added V-SNP has significant stability and can print higher-level needle tip parts, such as Fig.10 (b) shown.

[0058] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a photocurable resin containing modified nano-silicon dioxide, characterized in that: The photocurable resin uses polyethylene glycol acrylate-200 (PEGDA200) as a polymerization monomer; 2-isopropyl-9H-thioxanthen-9-one (ITX) as a light absorber to control the light source intensity and light penetration depth; diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) as a photoinitiator to promote the polymerization process; synthetic vinyl-modified nano-silica (V-SNP) as a photocrosslinker to form a dense crosslinking network and enhance the crosslinking degree, while the rigid nano-material improves the mechanical properties of the resin; The method for preparing the photocurable resin with modified nano-silicon dioxide is as follows: the above raw materials are fully stirred and then ultrasonicated; The preparation method of the vinyl-modified nano-silica (V-SNP) comprises: Step 1, add 50-300 ml of anhydrous ethanol to a round-bottom flask; add 1-10 ml of deionized water and 1-20 ml of ammonia water (25%); Step 2, heat the oil bath to 40-80°C. When the temperature reaches 65°C, add 2-8 ml of tetraethyl orthosilicate (TEOS) and react for 0.5-4 hours. Step 3, adding vinyl triethoxysilane (VTES) in an amount of 20%-50% of the volume fraction of tetraethyl orthosilicate (TEOS), and continuing the reaction for 2 hours to obtain vinyl-modified nano-silica (V-SNP).

2. The method for preparing a photocurable resin containing modified nano-silicon dioxide as claimed in claim 1, characterized in that: The added amount of ITX in the photocurable resin is 0.5%-3% of the mass volume fraction of PEGDA200.

3. The method for preparing a photocurable resin containing modified nano-silicon dioxide as claimed in claim 1, characterized in that: The added amount of diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) is 0.1%-0.5% of the mass volume fraction of PEGDA200.

4. The method for preparing a photocurable resin containing modified nano-silicon dioxide as claimed in claim 1, characterized in that: The added amount of the vinyl-modified nano-silica (V-SNP) is 0.5%-5% of the mass volume fraction of PEGDA200.

5. The method for preparing a photocurable resin containing modified nano-silicon dioxide as claimed in claim 1, characterized in that: Stir and dissolve for 2 hours, and ultrasonically disperse for 15 minutes until fully dispersed.

6. The method for preparing a photocurable resin containing modified nano-silicon dioxide as claimed in claim 1, characterized in that: Use Solidworks (2019b) for 3D modeling, export the file to STL format and import it into the slicing software, and then import the sliced ​​file into the 3D printer for printing.

7. A photocurable resin prepared by the method for preparing a photocurable resin with added modified nano-silicon dioxide as claimed in any one of claims 1 to 6.

8. Use of the photocurable resin as claimed in claim 7 in 3D printing.

9. The use according to claim 8, characterized in that The three-dimensional printing includes 3D printing mechanical tensile and compression models, 3D printing microfluidic chips, and 3D printing biological microneedles.

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