Special high-toughness photosensitive resin for SLA3D printing and preparation method thereof

Abstract

The invention relates to the technical field of 3D printing materials, and particularly discloses SLA3D printing special-purpose high-toughness photosensitive resin, which comprises an epoxy resin prepolymer, a urethane acrylate prepolymer, a modified epoxy acrylate prepolymer, an active diluent, a flexibilizer, a pigment filler, an antifoaming agent, a leveling agent and a photoinitiator. The toughening agent can effectively improve the toughness of the photosensitive resin through a cross-linking curing group and a toughening group of the toughening agent, the cross-linking curing group is an epoxy group or a hydroxyl group, the toughening group is long straight-chain alkane or long straight-chain alkane containing an ether bond, and the invention further provides a preparation method of the high-toughness photosensitive resin. After being cured and formed, the high-toughness resin disclosed by the invention has beating resistance and good rigidity performance and toughness performance.

Description

Technical Field

[0001] This invention relates to the field of 3D printing materials technology, and in particular to a high-toughness photosensitive resin for SLA 3D printing and its preparation method. Background Technology

[0002] 3D printing technology, also known as additive manufacturing technology, is a comprehensive technical solution that combines computers, equipment, materials, software, and other aspects. It is a tool for rapidly manufacturing three-dimensional parts based on digital models, allowing for parallel design verification or functional prototyping and production. This can shorten product design and development cycles and also has disruptive capabilities for free and rapid manufacturing. Furthermore, 3D printing technology is not limited by the shape and structure of the product during the manufacturing process and can create complex three-dimensional structures of arbitrary shapes and structures. Therefore, 3D printing has driven the development of various industries, and its market size and application scope are growing rapidly.

[0003] In terms of applications, 3D printing technology is used in industrial fields such as aerospace products, automotive products, and medical and health products, as well as in daily life fields such as handicrafts, shoe materials, and children's toys. Depending on the application, the requirements for the molding materials also vary.

[0004] In terms of molding methods, 3D printing molding technologies include stereolithography (SLA), fused deposition modeling (FDM), selective laser sintering (SLS), digital light processing (DLP), and LED curing (LCD). Different molding processes correspond to materials such as polymer filaments, composite liquid resins, metal powders, ceramic powders, and biomaterials.

[0005] Among all 3D printing technologies, stereolithography (SLA) is the most mature and widely used rapid prototyping technology. This technology produces parts with the highest precision and smoothest surfaces. However, the photopolymerization process is a random polymerization process, resulting in materials with mechanical properties far inferior to traditional thermoplastic engineering plastics. Photosensitive resin 3D printed parts used in SLA printers are generally very brittle and not impact-resistant, which greatly limits the application of SLA 3D printing technology. In response to the aforementioned technologies, the inventors believe that it is necessary to develop a high-toughness photosensitive resin that has impact resistance after photocuring. Summary of the Invention

[0006] To address the technical deficiencies of existing technologies, this application provides a photosensitive resin specifically for SLA 3D printing and its preparation method.

[0007] In the first aspect, this application provides a photosensitive resin specifically for SLA 3D printing, employing the following technical solution: A high-toughness photosensitive resin for SLA 3D printing, comprising: Epoxy resin prepolymers, polyurethane acrylate prepolymers, modified epoxy acrylate prepolymers, reactive diluents, toughening agents, pigments and fillers, defoamers, leveling agents, and photoinitiators; The toughening agent includes a crosslinking curing group and a toughening group, wherein the crosslinking curing group is an epoxy group or a hydroxyl group, and the toughening group is a long straight-chain alkane or a long straight-chain alkane containing an ether bond; The epoxy resin prepolymer, polyurethane acrylate prepolymer, and modified epoxy acrylate prepolymer are described. The mass ratio of polymer, reactive diluent, toughening agent, pigments and fillers, defoamer, leveling agent and photoinitiator is: (25~90): (0~40): (0~30): (3~60): (1~40): (0.01~20): (0.01~4): (0.01~4): (0.5~6).

[0008] By employing the above-mentioned technical solution, using a specific ratio of epoxy resin prepolymer, polyurethane acrylate prepolymer, and other components, combined with a special toughening agent whose molecular chain contains epoxy / hydroxyl crosslinking groups and long-chain alkanes (or long-chain alkanes containing ether bonds) toughening groups, a unique technical solution is formed. This toughening agent has both chemical crosslinking and physical toughening functions: the crosslinking groups are covalently bonded to the resin matrix to prevent phase separation, and the toughening groups spontaneously form "island structure" elastic microregions after curing, dissipating impact energy through a dual mechanism of plastic deformation and crack deflection. Compared with traditional photosensitive resins, this solution breaks through the toughness bottleneck at the molecular design level, significantly improving impact resistance while ensuring mechanical strength, and is suitable for the fabrication of high-precision, high-toughness 3D printed components.

[0009] The preferred mass ratio of the epoxy resin prepolymer, polyurethane acrylate prepolymer, modified epoxy acrylate prepolymer, reactive diluent, toughening agent, pigments and fillers, defoamer, leveling agent and photoinitiator is: (40-70): (10-30): (5-20): (15-40): (5-20): (1-15): (0.5-2): (0.5-2): (1-4).

[0010] By adopting the above technical solution, this application preferably uses a specific ratio of three types of prepolymers compounded together, along with an active diluent and a toughening agent containing crosslinking / toughening groups. This toughening agent can form an "island structure," dissipating impact energy through plastic deformation. With the aid of an additive system, the photosensitive resin possesses both high hardness and high elongation at break, significantly improving toughness compared to traditional formulations, resulting in good printing accuracy and achieving synergistic optimization of performance and processability.

[0011] Preferably, the toughening agent is one or both of LP188 and LP208.

[0012] By adopting the above technical solution, LP188 and / or LP208 are preferably used as toughening agents. They contain crosslinking and toughening groups, which can form a chemical network with the resin matrix and self-assemble elastic micro-regions. Through plastic deformation, they dissipate impact energy, significantly improve the toughness of photosensitive resin, and achieve high performance and processability optimization.

[0013] Preferably, the epoxy resin prepolymer includes one or more of bisphenol A type epoxy resin prepolymer, hydrogenated bisphenol A type epoxy resin prepolymer, bisphenol F type epoxy resin prepolymer, and hydrogenated bisphenol F type epoxy resin prepolymer.

[0014] By adopting the above technical solutions, a single component or compound system of bisphenol A / hydrogenated bisphenol A / bisphenol F / hydrogenated bisphenol F type epoxy resin prepolymer is preferred. By utilizing the synergistic effect of rigid benzene rings and saturated hydrogenated segments of prepolymers with different structures, the crosslinking density and molecular chain flexibility of the resin are optimized, thereby improving the mechanical properties and molding stability of the printing material.

[0015] Preferably, the reactive diluent is one or more of the following: 1,6-hexanediol diacrylate, ethoxyethoxyethyl acrylate, 4-acryloylmorpholine, tripropylene glycol diacrylate, dipropylene glycol diacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, cyclotrimethylolpropane methyl acetal acrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, ethylene glycol diglycidyl ether, butylene glycol diglycidyl ether, hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and dipropylene glycol diglycidyl ether.

[0016] By adopting the above technical solutions, preferably using a single component or compound system of various acrylate and glycidyl ether reactive diluents, the resin viscosity is adjusted, the flowability is improved, and the resin participates in photocuring crosslinking, thereby avoiding curing shrinkage and maintaining the mechanical properties and molding stability of the resin.

[0017] Preferably, the pigment or filler is one or more of nano-titanium dioxide, nano-silica, nano-zinc dioxide, nano-calcium carbonate, and nano-calcium sulfate.

[0018] By adopting the above technical solutions, it is preferable to use single components or compound pigments and fillers such as nano-titanium dioxide and silicon dioxide. By utilizing the high specific surface area of ​​nanoparticles and their strong interaction with the resin matrix, the rigidity and wear resistance of the material are enhanced, while the color and light scattering properties are adjusted without affecting the resin curing and mechanical toughness.

[0019] Preferably, the photoinitiator comprises one or more of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 2-hydroxy-2-methyl-1-phenylpropanone, diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate, 1-hydroxycyclohexylbenzophenone, diphenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate, 2-isopropylthioxanthone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, bis(4-tert-butylphenyl)iodonium hexafluorophosphate, 4,4′-xylyliodonium hexafluorophosphate, and (2,4,6-trimethylbenzoyl)di(p-tolyl)phosphine oxide.

[0020] By adopting the above technical solutions, a single component or compound system of various acylphosphine oxides, benzophenones, and iodonium salts as photoinitiators is preferred. By utilizing the complementary and synergistic effects of the ultraviolet absorption spectra of different initiators, a balance between deep curing and rapid surface crosslinking can be achieved, thereby improving the photocuring efficiency and molding precision of photosensitive resins.

[0021] Secondly, this invention provides a method for preparing a high-toughness photosensitive resin specifically for SLA 3D printing, employing the following technical solution: A method for preparing a high-toughness photosensitive resin for SLA 3D printing includes the following steps: A method for preparing a high-toughness photosensitive resin, the specific steps of which are as follows: (1) Put epoxy resin prepolymer, polyurethane acrylate prepolymer and reactive diluent into a covered reactor, heat to 50-70℃, and stir at 2000-3000r / min for 90-120min. (2) Add toughening agent, pigments and fillers, defoamer and leveling agent, and stir with the cap at a speed of 2000-3000 r / min for 90-120 min; (3) Cool to 25–30°C, add photoinitiator, and stir with a capped container at 1500–2000 r / min for 40–50 min to obtain a high-toughness photosensitive resin. By adopting the above technical solution, By employing the above technical solution, a staged temperature-controlled stirring process is used to prepare high-toughness photosensitive resin for SLA 3D printing: First, the prepolymer and diluent are stirred at high speed at 50–70°C to ensure the molecular chains are fully extended and mixed; then, toughening agents and other components are added and dispersed at high speed to form a uniform "island structure"; finally, a photoinitiator is added at low temperature and stirred slowly to avoid premature polymerization. This process, through the synergistic control of temperature and shear force, achieves uniform dispersion of components and directional arrangement of the structure, improving the resin's toughness and molding stability.

[0022] In summary, this application has the following beneficial effects: 1. This application utilizes a special toughening agent containing crosslinking groups (epoxy / hydroxyl) and toughening groups (long-chain alkanes) to form a synergistic system with epoxy resin prepolymers and reactive diluents. During curing, the toughening agent self-assembles "island-structure" elastic microdomains, dissipating impact energy through plastic deformation and crack deflection. Simultaneously, the crosslinking groups form a chemical network with the resin matrix, preventing phase separation. By combining three types of prepolymers to optimize the crosslinking density, the photosensitive resin exhibits high hardness, high elongation at break, and impact resistance, overcoming the toughness bottleneck of traditional materials.

[0023] 2. The preparation method of this application adopts a staged stirring process of "high-temperature dispersion-low-temperature initiation". First, the prepolymer and diluent are stirred at high speed at 50-70℃ to promote the stretching and mixing of molecular chains; then, toughening agents and other components are added to form a uniformly dispersed phase; finally, a photoinitiator is introduced at low temperature to avoid premature polymerization. This process, through the synergistic control of temperature and shear force, ensures uniform dispersion of components and directional arrangement of microstructure, improves the resin photocuring efficiency and printing accuracy, and achieves synergistic optimization of high performance and processing stability. Detailed Implementation

[0024] The present application will be further described in detail below with reference to the embodiments.

[0025] This invention provides a high-toughness photosensitive resin for SLA 3D printing, and the raw materials for preparation include the following components by weight: 25–90 parts epoxy resin prepolymer, 0–40 parts polyurethane acrylate prepolymer, 0–30 parts modified epoxy acrylate prepolymer, 3–60 parts reactive diluent, 1–40 parts toughening agent, 0.01–20 parts pigments and fillers, 0.01–4 parts defoamer, 0.01–4 parts leveling agent, and 0.5–6 parts photoinitiator.

[0026] The toughening agent includes a crosslinking curing group and a toughening group. The crosslinking curing group is an epoxy group or a hydroxyl group, and the toughening group is a long straight-chain alkane or a long straight-chain alkane containing an ether bond.

[0027] The toughening agent includes one or both of the toughening agents LP188 and LP208 developed by Guangzhou Yousu 3D Technology Co., Ltd. The crosslinking curing groups of the toughening agent LP188 are epoxy groups and hydroxy groups, and the toughening groups are long straight-chain alkanes containing ether bonds.

[0028] The toughening agent LP208 has an epoxy group as its crosslinking curing group and a long straight-chain alkane as its toughening group.

[0029] The core innovation of this system lies in the use of a toughening agent with a special molecular structure. This agent's molecular chain is designed with both cross-linking curing groups and toughening groups: the cross-linking curing groups are explicitly defined as epoxy or hydroxyl groups, while the toughening groups are specifically long-chain alkanes or long-chain alkanes containing ether bonds. This invention significantly improves the toughness of epoxy resin photocured molded bodies by precisely introducing this special toughening agent carrying specific reactive functional groups. The special toughening agent plays a crucial dual synergistic role in the system, acting as an effective component participating in the photocuring reaction, integrating into the cured network through a chemical cross-linking reaction with the photosensitive resin matrix (especially epoxy resin prepolymer); simultaneously, it functions as a highly efficient toughening modifier. Because the epoxy or hydroxyl groups contained in its molecular chain are chemically compatible with other basic components of photosensitive resin, and even have affinity in terms of intermolecular forces, the toughening agent can achieve excellent thermodynamic dissolution and kinetic dispersion effects during the resin preparation and mixing stages, ensuring the high uniformity and stability of the mixed system. At the same time, more importantly, these functional groups will actually participate in the chemical reaction and form a covalently bonded chemical cross-linking network with the matrix during the subsequent photocuring process. This not only ensures the uniform participation and distribution of the toughening agent during the curing reaction from a kinetic perspective, but also fundamentally ensures from a thermodynamic perspective that it completely avoids any form of instability such as macroscopic phase separation, component separation, layering, precipitation, sedimentation or aggregation caused by differences in solubility or compatibility issues throughout the entire life cycle of the resin system, from mixing and storage (before curing) to the photocuring process (during curing) and finally after complete curing (after curing). This provides a fundamental guarantee for the stability and reliability of the final product performance.

[0030] On the other hand, after the photocuring reaction is completed and a highly cross-linked three-dimensional rigid network is formed, the toughening groups, due to their highly compliant molecular chains, extremely low polarity, and thermodynamically slightly incompatible characteristics with the highly cross-linked rigid resin matrix, will undergo chain segment folding, aggregation, and microphase separation under the drive of molecular chain movement. They will spontaneously form a large number of uniform, tiny, highly flexible elastic microregions (dispersed phase, called "island phase") rich in long straight-chain alkanes or long straight-chain alkanes containing ether bonds inside the rigid cured resin matrix (continuous phase, called "sea phase"), thereby constructing a characteristic "island structure". When cured resin components are subjected to external impact or stress, especially under impact loads that could lead to material fracture, this carefully constructed "island structure" becomes key to energy dissipation: the flexible long-chain alkanes (or long-chain alkanes containing ether bonds) aggregated regions existing as "islands" possess extremely high flexibility and significant ductility, enabling them to undergo large-scale plastic deformation, shear yielding, curling and unfolding, or oriented stretching—energy absorption behaviors—in stress fields induced by external forces, particularly in high-stress concentration areas in front of crack tips. This process requires the consumption of a large amount of mechanical energy; simultaneously, these elastic... The presence of island phases can effectively force the path of the expanding crack tip to become blunt, deflected, branched, or bypassed, greatly increasing the energy consumption required for crack propagation and lengthening its path, thus creating a significant barrier and hysteresis effect on the high-speed propagation of the main crack. It is through this dual microscopic physical mechanism of absorbing huge impact energy and effectively inhibiting crack propagation that the toughness (i.e., the ability to resist impact damage and inhibit crack initiation and propagation) of products cured by photocuring of this photosensitive resin system is significantly and fundamentally improved, overcoming the common defect of insufficient toughness in traditional photocuring resins.

[0031] In this invention, the epoxy resin prepolymer forms the basis for the mechanical properties of the photosensitive resin. Its epoxy groups undergo ring-opening cross-linking during photocuring, forming a rigid three-dimensional network that imparts high hardness and rigidity to the resin. Simultaneously, the heterocyclic rings, such as the benzene rings, in the structure enhance intermolecular forces, improving the material's compressive and flexural strength. The epoxy resin prepolymer includes one or more of bisphenol A type epoxy resin prepolymers, hydrogenated bisphenol A type epoxy resin prepolymers, bisphenol F type epoxy resin prepolymers, and hydrogenated bisphenol F type epoxy resin prepolymers.

[0032] The polyurethane acrylate prepolymer in this invention possesses both flexibility and rigidity. The flexible segments impart toughness to the resin and buffer stress; the acrylate functional groups, after polymerization, enhance tensile strength. Furthermore, it reduces curing shrinkage and improves weather resistance and corrosion resistance. The polyurethane acrylate prepolymer is one or more of the following: Guangzhou Songda SD7541, Guangzhou Songda SD867, Guangzhou Songda SD1223, Guangzhou Songda SD7559C, Guangdong Ketian 3271, Guangdong Ketian 3250, Hengzhiguang 7203, Hengzhiguang 7200, and Hengzhiguang 7224-1.

[0033] In this invention, the modified epoxy acrylate prepolymer has improved photoreactivity through modification, which can accelerate curing speed and shorten printing time. The optimized structure reduces resin viscosity, improves molding accuracy and surface finish, and enhances the mechanical properties of the cured body. The modified epoxy acrylate prepolymer is one or more of the following: Guangdong Ketian 4267, Guangdong Ketian 4269, Guangzhou Songda SD7201, Hengzhiguang 6118, and Hengzhiguang 9104.

[0034] The reactive diluent in this invention reduces resin viscosity, improves flowability, and facilitates 3D printing. Unlike ordinary diluents, it contains active functional groups that can participate in photocuring crosslinking, preventing volume shrinkage after curing and maintaining resin performance stability. The reactive diluent is one or more of the following: 1,6-hexanediol diacrylate, ethoxyethoxyethyl acrylate, 4-acryloylmorpholine, tripropylene glycol diacrylate, dipropylene glycol diacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, cyclotrimethylolpropane methyl acetal acrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, ethylene glycol diglycidyl ether, butylene glycol diglycidyl ether, hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and dipropylene glycol diglycidyl ether.

[0035] In this invention, pigments and fillers impart color, conductivity, and wear resistance to the resin, and can also adjust density and coefficient of thermal expansion. Properly dispersed pigments and fillers can enhance the mechanical properties of the material. The pigments and fillers are one or more of nano-titanium dioxide, nano-silica, nano-zinc dioxide, nano-calcium carbonate, and nano-calcium sulfate.

[0036] In this invention, the defoamer reduces the surface tension of air bubbles, eliminating bubbles generated during resin mixing, preventing voids after curing, and ensuring the mechanical properties and surface quality of the molded parts. The defoamer used is either Dongguan Guozhong DU-304 or Shanghai Ziyi ZY-283.

[0037] The leveling agent in this invention reduces the surface tension of the resin, improves its spreading ability on the substrate surface or between printed layers, and allows the resin to level quickly before curing, eliminating surface defects such as brush marks and orange peel. During the 3D printing process, it helps improve the smoothness and gloss of the printed surface, and some leveling agents can also enhance the anti-blocking and abrasion resistance of the coating, optimizing the appearance and performance of the final product. The leveling agent used is one of silicon carbide 350, silicon carbide 354, or silicon carbide 355.

[0038] In this invention, the photoinitiator is a key raw material for initiating resin curing and a core catalyst component. Without the photoinitiator, the resin cannot be cured and molded. The photoinitiator decomposes under ultraviolet light to generate free radicals, initiating the polymerization and curing of acrylic resin. The photoinitiator includes one or more of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 2-hydroxy-2-methyl-1-phenylpropanone, diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate, 1-hydroxycyclohexylbenzophenone, diphenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate, 2-isopropylthioxanthraphenone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, bis(4-tert-butylphenyl)iodonium hexafluorophosphate, 4,4′-xylyliodonium hexafluorophosphate, and (2,4,6-trimethylbenzoyl)di(p-tolyl)phosphine oxide.

[0039] Example 1 A high-toughness photosensitive resin for SLA 3D printing is prepared by means of the following components: 500g epoxy resin prepolymer, 50g polyurethane acrylate prepolymer, 250g reactive diluent, 200g toughening agent, 5g pigments and fillers, 1g defoamer, 2g leveling agent and 25g photoinitiator.

[0040] In this embodiment, the epoxy resin prepolymer is a blend of bisphenol A type epoxy resin prepolymer and hydrogenated bisphenol A type epoxy resin prepolymer, with a mass ratio of 2:3.

[0041] The polyurethane acrylate prepolymer is Guangdong Ketian 3250.

[0042] The active diluent is a compound of tripropylene glycol diacrylate and dipropylene glycol diglycidyl ether, with a mass ratio of 4:1.

[0043] The toughening agent is LP188, the pigment and filler is nano titanium dioxide, the defoamer is DU-304, and the leveling agent is silicon carbide rat 355.

[0044] The photoinitiator is a combination of 2-hydroxy-2-methyl-1-phenylpropanone and diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate, with a mass ratio of 1:4.

[0045] This embodiment also provides a method for preparing a high-toughness photosensitive resin, the specific steps of which are as follows: (1) Put epoxy resin prepolymer, polyurethane acrylate prepolymer and reactive diluent into a covered reactor, heat to 70°C, and stir at 3000 r / min for 120 min. (2) Add toughening agent, pigments and fillers, defoamer and leveling agent, and stir with cap at 3000 r / min for 120 min; (3) Cool down to 30°C, add photoinitiator, and stir at 1500r / min for 40min to obtain high toughness photosensitive resin.

[0046] Printing mechanical specimens: Place the obtained photosensitive resin into the material cylinder of the SLA 3D printer, set the liquid level, input the printing model slice, and set the printing parameters as follows: power 350mW, support scanning speed 1300mm / s, infill scanning speed 6000mm / s, layer thickness 0.1mm, scanning interval 0.06mm, and carry out the printing operation. The printing process parameters can be adjusted up and down according to the printing effect. After printing, clean the model with alcohol and place it in the post-curing chamber for 10 minutes to obtain the printed product.

[0047] Example 2 A high-toughness photosensitive resin for SLA 3D printing is prepared by means of the following components: 600g epoxy resin prepolymer, 30g modified epoxy acrylate prepolymer, 220g reactive diluent, 150g toughening agent, 50g pigments and fillers, 1g defoamer, 2g leveling agent and 20g photoinitiator.

[0048] The epoxy resin prepolymer is a blend of bisphenol F type epoxy resin prepolymer and bisphenol A type epoxy resin prepolymer, with a mass ratio of 1:1 between the two.

[0049] The modified epoxy acrylate prepolymer is Guangdong Ketian 4269.

[0050] The reactive diluent is a mixture of dipropylene glycol diacrylate and ethoxyethoxyethyl acrylate, with a mass ratio of 10:1.

[0051] The toughening agent is LP208, the pigment and filler is nano-silica, the defoamer is DU-304, and the leveling agent is silicon carbide 355.

[0052] The photoinitiator is a combination of 2-hydroxy-2-methyl-1-phenylpropanone and diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate, with a mass ratio of 1:3.

[0053] This embodiment also provides a method for preparing a high-toughness photosensitive resin, the specific steps of which are as follows: (1) Put epoxy resin prepolymer, modified epoxy acrylate prepolymer and reactive diluent into a covered reactor, heat to 50°C, and stir at 2500 r / min for 90 min. (2) Add toughening agent, pigments and fillers, defoamer and leveling agent, and stir with cap at 2500 r / min for 90 min; (3) Cool down to 25°C, add photoinitiator, and stir at 1500r / min for 40min to obtain high toughness photosensitive resin.

[0054] Printing mechanical specimens: Place the obtained photosensitive resin into the material cylinder of the SLA 3D printer, set the liquid level, input the printing model slice, and set the printing parameters as follows: power 280mW, support scanning speed 1400mm / s, infill scanning speed 7000mm / s, layer thickness 0.1mm, scanning interval 0.06mm, and carry out the printing operation. The printing process parameters can be adjusted up and down according to the printing effect. After printing, clean the model with alcohol and place it in the post-curing chamber for 10 minutes to obtain the printed product.

[0055] Example 3 A high-toughness photosensitive resin for SLA 3D printing is prepared by means of the following components: 250g epoxy resin prepolymer, 200g polyurethane acrylate prepolymer, 50g modified epoxy acrylate prepolymer, 150g reactive diluent, 50g toughening agent, 100g pigments and fillers, 5g defoamer, 0.1g leveling agent and 5g photoinitiator.

[0056] The epoxy resin prepolymer is a blend of bisphenol F type epoxy resin prepolymer and hydrogenated bisphenol F type epoxy resin prepolymer, with a mass ratio of 2:3.

[0057] The polyurethane acrylate prepolymer is a blend of Guangzhou Songda SD7541 and Guangzhou Songda SD867, with a mass ratio of 1:1.

[0058] The modified epoxy acrylate prepolymer is Guangdong Ketian 4267.

[0059] The reactive diluent is a compound of 1,6-hexanediol diacrylate, 4-acryloylmorpholine, and hydroxyethyl acrylate, with a mass ratio of 3:1:1.

[0060] The toughening agent is LP188, the pigment and filler is nano zinc dioxide, the defoamer is ZY-283, and the leveling agent is silicon carbide 350.

[0061] The photoinitiator is a combination of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide and 1-hydroxycyclohexylbenzophenone, with a mass ratio of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide to 1-hydroxycyclohexylbenzophenone of 2:3.

[0062] This embodiment also provides a method for preparing a high-toughness photosensitive resin, the specific steps of which are as follows: (1) Add epoxy resin prepolymer, polyurethane acrylate prepolymer, modified epoxy acrylate prepolymer and reactive diluent to a covered reactor, heat to 60°C, and stir at 2000 r / min for 100 min. (2) Add toughening agent, pigments and fillers, defoamer and leveling agent, and stir with cap at 2000 r / min for 100 min; (3) Cool down to 27°C, add photoinitiator, and stir at 2000r / min for 45min to obtain high toughness photosensitive resin.

[0063] Printing mechanical specimens: Place the obtained photosensitive resin into the material cylinder of the SLA 3D printer, set the liquid level, input the printing model slice, and set the printing parameters as follows: power 250mW, support scanning speed 1400mm / s, infill scanning speed 7000mm / s, layer thickness 0.1mm, scanning interval 0.06mm, and carry out the printing operation. The printing process parameters can be adjusted up or down according to the printing effect.

[0064] Example 4 A high-toughness photosensitive resin for SLA 3D printing is prepared from the following raw materials: 400g epoxy resin prepolymer, 300g polyurethane acrylate prepolymer, 300g modified epoxy acrylate prepolymer, 400g reactive diluent, 10g toughening agent, 0.1g pigments and fillers, 40g defoamer, 20g leveling agent, and 10g photoinitiator.

[0065] The epoxy resin prepolymer is a blend of hydrogenated bisphenol A type epoxy resin prepolymer and hydrogenated bisphenol F type epoxy resin prepolymer, with a mass ratio of 1:1.

[0066] The polyurethane acrylate prepolymer is a blend of Guangzhou Songda SD1223 and Guangzhou Songda SD7559C, with a mass ratio of 1:1.

[0067] The modified epoxy acrylate prepolymer is Guangzhou Songda SD7201.

[0068] The active diluent is a compound of hydroxyethyl methacrylate, cyclotrimethylolpropane methyl acetal acrylate, and trimethylolpropane triacrylate, with a mass ratio of 2:3:5.

[0069] The toughening agent is LP208, the pigment and filler is nano-calcium carbonate, the defoamer is ZY-283, and the leveling agent is silicon carbide 350.

[0070] The photoinitiator is a compound of phenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate and 2-isopropylthioxanthanone, with a mass ratio of 4:1.

[0071] This embodiment also provides a method for preparing a high-toughness photosensitive resin, the specific steps of which are as follows: (1) Add epoxy resin prepolymer, polyurethane acrylate prepolymer, modified epoxy acrylate prepolymer and reactive diluent to a covered reactor, heat to 70°C, and stir at 3000 r / min for 120 min. (2) Add toughening agent, pigments and fillers, defoamer and leveling agent, and stir with cap at 3000 r / min for 120 min; (3) Cool down to 30°C, add photoinitiator, and stir at 1500r / min for 40min to obtain high toughness photosensitive resin.

[0072] Printing mechanical specimens: Place the obtained photosensitive resin into the material cylinder of the SLA 3D printer, set the liquid level, input the printing model slice, and set the printing parameters as follows: power 350mW, support scanning speed 1300mm / s, infill scanning speed 6000mm / s, layer thickness 0.1mm, scanning interval 0.06mm, and carry out the printing operation. The printing process parameters can be adjusted up and down according to the printing effect. After printing, clean the model with alcohol and place it in the post-curing chamber for 10 minutes to obtain the printed product.

[0073] Example 5 A high-toughness photosensitive resin for SLA 3D printing is prepared from the following raw materials: 700g epoxy resin prepolymer, 400g polyurethane acrylate prepolymer, 200g modified epoxy acrylate prepolymer, 30g reactive diluent, 400g toughening agent, 10g pigments and fillers, 0.1g defoamer, 5g leveling agent, and 60g photoinitiator.

[0074] The epoxy resin prepolymer is a bisphenol A type epoxy resin prepolymer.

[0075] The polyurethane acrylate prepolymer is a blend of Guangdong Ketian 3271 and Hengzhiguang 7203, with a mass ratio of 1:2.

[0076] The modified epoxy acrylate prepolymer is Hengzhiguang 6118.

[0077] The active diluent is a compound of ethoxylated trimethylolpropane triacrylate and ethylene glycol diglycidyl ether, with a mass ratio of ethoxylated trimethylolpropane triacrylate to ethylene glycol diglycidyl ether of 2:1.

[0078] The toughening agents are LP188 and LP208, with a mass ratio of 1:1. The pigments and fillers are nano-calcium sulfate, the defoamer is ZY-283, and the leveling agent is silicon carbide 354.

[0079] The photoinitiator is a compound of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and ethyl 2,4,6-trimethylbenzoylphenylphosphonate, with a mass ratio of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide to ethyl 2,4,6-trimethylbenzoylphenylphosphonate of 1:1.

[0080] This embodiment also provides a method for preparing a high-toughness photosensitive resin, the specific steps of which are as follows: (1) Put epoxy resin prepolymer, polyurethane acrylate prepolymer, modified epoxy acrylate prepolymer and reactive diluent into a covered reactor, heat to 50°C, and stir at 2500 r / min for 90 min. (2) Add toughening agent, pigments and fillers, defoamer and leveling agent, and stir with cap at 2500 r / min for 90 min; (3) Cool down to 25°C, add photoinitiator, and stir at 1800r / min for 45min to obtain high toughness photosensitive resin.

[0081] Printing mechanical specimens: Place the obtained photosensitive resin into the material cylinder of the SLA 3D printer, set the liquid level, input the printing model slice, and set the printing parameters as follows: power 280mW, support scanning speed 1400mm / s, infill scanning speed 7000mm / s, layer thickness 0.1mm, scanning interval 0.06mm, and carry out the printing operation. The printing process parameters can be adjusted up and down according to the printing effect. After printing, clean the model with alcohol and place it in the post-curing chamber for 10 minutes to obtain the printed product.

[0082] Example 6 A high-toughness photosensitive resin for SLA 3D printing is prepared from the following raw materials: 900g epoxy resin prepolymer, 100g polyurethane acrylate prepolymer, 150g modified epoxy acrylate prepolymer, 600g reactive diluent, 250g toughening agent, 150g pigments and fillers, 20g defoamer, 40g leveling agent, and 40g photoinitiator.

[0083] The epoxy resin prepolymer described in this embodiment is a hydrogenated bisphenol F type epoxy resin prepolymer.

[0084] The polyurethane acrylate prepolymer is a blend of Hengzhiguang 7200 and Hengzhiguang 7224-1, with a mass ratio of 2:3.

[0085] The modified epoxy acrylate prepolymer is Hengzhiguang 9104.

[0086] The active diluent is a compound of glycol diglycidyl ether, hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether, with a mass ratio of 1:1:1.

[0087] The toughening agent is LP208, and the pigment / filler is a blend of nano-titanium dioxide and nano-calcium sulfate, with a mass ratio of 1:1. The defoamer is DU-304, and the leveling agent is silicon carbide 354.

[0088] The photoinitiator is a compound of bis(4-tert-butylphenyl)iodonium hexafluorophosphate, 4,4′-dimethyliodonium hexafluorophosphate, and (2,4,6-trimethylbenzoyl)di(p-tolyl)phosphine oxide, with a mass ratio of 3:3:2.

[0089] This embodiment also provides a method for preparing a high-toughness photosensitive resin, the specific steps of which are as follows: (1) Put epoxy resin prepolymer, urethane acrylate prepolymer, modified epoxy acrylate prepolymer and reactive diluent into a covered reactor, heat to 60°C, and stir at 2000 r / min for 100 min. (2) Add toughening agent, pigments and fillers, defoamer and leveling agent, and stir with cap at 2000 r / min for 100 min; (3) Cool down to 27°C, add photoinitiator, and stir at 2000r / min for 50min to obtain high toughness photosensitive resin.

[0090] Printing mechanical specimens: Place the obtained photosensitive resin into the material cylinder of the SLA 3D printer, set the liquid level, input the printing model slice, and set the printing parameters as follows: power 250mW, support scanning speed 1400mm / s, infill scanning speed 7000mm / s, layer thickness 0.1mm, scanning interval 0.06mm, and carry out the printing operation. The printing process parameters can be adjusted up or down according to the printing effect.

[0091] To verify the performance of the high-toughness photosensitive resin for SLA 3D printing of the present invention, comparative examples 1-2 were set up based on Example 2.

[0092] Comparative Example 1 A photosensitive resin for SLA 3D printing, which differs from the photosensitive resin of Example 2 in that the photosensitive resin of this comparative example does not contain toughening agents.

[0093] The preparation method of the photosensitive resin in this comparative example is the same as that of the photosensitive resin in Example 2.

[0094] The printing parameters of the photosensitive resin printed product in this comparative example are the same as those in Example 2.

[0095] Comparative Example 2 A photosensitive resin for SLA 3D printing, which differs from the photosensitive resin of Example 2 in that the photosensitive resin of this comparative example uses PESE3010MR polyethersulfone (PES) toughening agent from BASF Germany instead of LP208.

[0096] The preparation method of the photosensitive resin in this comparative example is the same as that of the photosensitive resin in Example 2.

[0097] The printing parameters of the photosensitive resin printed product in this comparative example are the same as those in Example 2.

[0098] Performance testing The mechanical properties of the photosensitive resin-printed mechanical specimens of Examples 1-6 and Comparative Examples 1-2 were tested according to the standards ASTM D638, ASTM D790, and ASTM D256. The Shore hardness of the mechanical specimens was tested using a Shore hardness tester. The results are detailed in Table 1.

[0099] Table 1 Performance Test Results Based on the test data in Table 1, the mechanical specimens made from the photosensitive resin of this invention using SLA 3D printing all exhibited elongation at break exceeding 22%, and notched impact strength consistently above 73 MPa. Elongation at break reflects the material's plastic deformation capacity; a higher value indicates better basic toughness. Notched impact strength reflects the material's resistance to instantaneous impact damage; a high value signifies excellent impact toughness. The superior performance of these two core indicators fully demonstrates that the photosensitive resin of this invention possesses excellent comprehensive toughness. Under external force, it can absorb energy through plastic deformation, craze formation, and shear band generation, effectively resisting cracking and breakage, and exhibiting significant impact resistance.

[0100] Comparative Example 2 and Comparative Examples 1-2: Mechanical specimens made of photosensitive resin were compared. Comparative Example 1, without added toughening agent, lacked "stress dispersion and energy absorption units," making its molecular chains prone to rigid fracture under external force. Test data showed a sharp drop in elongation at break to 7.84%, and a notched impact strength of only 17.51 ​​MPa. The printed product exhibited typical brittle characteristics, cracking or even breaking upon slight impact, demonstrating extremely poor drop resistance and failing to meet the requirements of toughness-demanding applications.

[0101] In Comparative Example 2, the photosensitive resin used a polyethersulfone (PES) toughening agent instead of the toughening agent of this application. Although the elongation at break and notched impact strength of the mechanical specimens were improved compared to those of Comparative Example 1 due to the flexibility of the PES molecular chain and the effect of the dispersed phase, the compatibility and synergistic effect of this toughening agent with the resin system of this invention were inferior to those of the toughening agent of this application, resulting in a bottleneck in performance improvement. Compared with the mechanical specimen data of Example 2, the elongation at break and notched impact strength of the mechanical specimens of Comparative Example 2 still showed a significant difference, indirectly confirming the unique advantages of the toughening agent of this invention in terms of molecular structure compatibility and synergistic toughening mechanism with resin components, which can precisely enhance the toughness of photosensitive resins.

[0102] Furthermore, the tensile strength, flexural modulus, and Shore hardness of the mechanical specimens printed with the high-toughness photosensitive resin for SLA 3D printing of this invention are similar to those of the mechanical specimens in Comparative Example 1 (without toughening agent). This is because the toughening agent mainly optimizes toughness through methods such as "island structure" and "crazing," contributing little to the material's rigidity, thus ensuring that the basic mechanical stability is not significantly affected when the resin enhances toughness. Although its flexural strength decreased somewhat (65.09 MPa in Example 2 and 90.55 MPa in Comparative Example 1), it remained stable above 63 MPa. In accordance with engineering application standards, the high-toughness photosensitive resin for SLA 3D printing of this invention achieves a breakthrough in toughness while still meeting practical requirements in terms of rigidity, thus achieving a performance balance between rigidity and toughness.

[0103] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A high-toughness photosensitive resin specifically for SLA 3D printing, characterized in that, include: Epoxy resin prepolymers, polyurethane acrylate prepolymers, modified epoxy acrylate prepolymers, reactive diluents, toughening agents, pigments and fillers, defoamers, leveling agents, and photoinitiators; The toughening agent includes a crosslinking curing group and a toughening group, wherein the crosslinking curing group is an epoxy group or a hydroxyl group, and the toughening group is a long straight-chain alkane or a long straight-chain alkane containing an ether bond; The mass ratio of the epoxy resin prepolymer, polyurethane acrylate prepolymer, modified epoxy acrylate prepolymer, reactive diluent, toughening agent, pigments and fillers, defoamer, leveling agent and photoinitiator is (25-90): (0-40): (0-30): (3-60): (1-40): (0.01-20): (0.01-4): (0.01-4): (0.5-6).

2. The high-toughness photosensitive resin for SLA 3D printing according to claim 1, characterized in that: The mass ratio of the epoxy resin prepolymer, polyurethane acrylate prepolymer, modified epoxy acrylate prepolymer, reactive diluent, toughening agent, pigments and fillers, defoamer, leveling agent and photoinitiator is: (40-70): (10-30): (5-20): (15-40): (5-20): (1-15): (0.5-2): (0.5-2): (1-4).

3. The high-toughness photosensitive resin for SLA 3D printing according to claim 1, characterized in that: The toughening agent is one or both of LP188 and LP208.

4. The high-toughness photosensitive resin for SLA 3D printing according to claim 1, characterized in that: The epoxy resin prepolymer includes one or more of bisphenol A type epoxy resin prepolymer, hydrogenated bisphenol A type epoxy resin prepolymer, bisphenol F type epoxy resin prepolymer, and hydrogenated bisphenol F type epoxy resin prepolymer.

5. The high-toughness photosensitive resin for SLA 3D printing according to claim 1, characterized in that: The active diluent is one or more of the following: 1,6-hexanediol diacrylate, ethoxyethoxyethyl acrylate, 4-acryloylmorpholine, tripropylene glycol diacrylate, dipropylene glycol diacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, cyclotrimethylolpropane methyl acetal acrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, ethylene glycol diglycidyl ether, butylene glycol diglycidyl ether, hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and dipropylene glycol diglycidyl ether.

6. The high-toughness photosensitive resin for SLA 3D printing according to claim 1, characterized in that: The pigments and fillers are one or more of nano titanium dioxide, nano silicon dioxide, nano zinc dioxide, nano calcium carbonate, and nano calcium sulfate.

7. The high-toughness photosensitive resin for SLA 3D printing according to claim 1, characterized in that: The photoinitiator includes one or more of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 2-hydroxy-2-methyl-1-phenylpropanone, diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate, 1-hydroxycyclohexylbenzophenone, diphenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate, 2-isopropylthioxanthraphenone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphine, bis(4-tert-butylphenyl)iodonium hexafluorophosphate, 4,4'-xylyliodonium hexafluorophosphate, and (2,4,6-trimethylbenzoyl)di(p-tolyl)phosphine oxide.

8. A method for preparing a high-toughness photosensitive resin for SLA 3D printing according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Put epoxy resin prepolymer, polyurethane acrylate prepolymer and reactive diluent into a covered reactor, heat to 50-70℃, and stir at 2000-3000r / min for 90-120min. (2) Add toughening agent, pigments and fillers, defoamer and leveling agent, and stir with the cap at a speed of 2000-3000 r / min for 90-120 min; (3) Cool down to 25-30℃, add photoinitiator, and stir with capping at 1500-2000r / min for 40-50min to obtain high toughness photosensitive resin.

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