As a core material in photopolymer additive manufacturing, the production of 3D resin involves multiple stages, including raw material selection, synthesis and modification, formulation, quality inspection, and filling and storage. The process must ensure the material's photosensitive properties and molding performance while also considering stability, safety, and environmental requirements, thus exhibiting a high degree of systematicity and standardization in its design and execution.
Raw material preparation and pretreatment are the starting point of the process. Commonly used matrix resins include epoxy acrylates, polyurethane acrylates, and polyester acrylates, while photoinitiators are selected based on curing wavelength and efficiency, such as 1173, 819, and TPO. Before production, the purity of monomers and additives must be tested and moisture controlled to prevent impurities or moisture from affecting the curing reaction and storage stability. Some special functional resins also require the introduction of heat-resistant, toughening, or flexible segment monomers to meet the performance requirements of different application scenarios.
The synthesis and modification stage involves molecular design based on the target performance. Through free radical polymerization or stepwise polymerization, functional monomers are introduced into the matrix resin skeleton to control viscosity, hardness, flexibility, and reactivity. For transparent or high-toughness resins, crosslinking density and segment distribution are optimized; for heat-resistant or chemically resistant resins, aromatic or fluorinated structures are introduced. The synthesis process requires strict control of temperature, time, and inert atmosphere to prevent side reactions and color changes, ensuring batch consistency.
Formulation preparation involves mixing the synthetic resin with photoinitiators, leveling agents, defoamers, and other additives in precise proportions. This step demands extremely high dispersion uniformity and typically employs high-speed shearing or planetary stirring equipment under constant temperature conditions to avoid uneven curing or storage stratification caused by localized concentration differences. For washable resins, hydrophilic modifiers are added, and their compatibility with the matrix is verified.
Filtration and degassing are critical steps in ensuring product quality. The prepared slurry undergoes multi-stage filtration to remove particulate impurities and prevent nozzle or molding platform clogging; vacuum degassing eliminates dissolved bubbles, preventing pinholes and internal defects on the molded parts. This process must be carried out in a clean environment, and viscosity changes must be monitored to ensure compliance with the process window.
Quality inspection is conducted throughout the entire process and concentrated in the finished product stage. Testing items include viscosity, curing rate, hardness, tensile/flexural strength, heat distortion temperature, light transmittance, and odor. Small-sample printing is also required to verify molding accuracy, interlayer adhesion, and post-curing stability. For resins used in medical or food contact applications, biocompatibility or migration testing must be conducted according to industry standards to ensure compliance.
The filling and storage processes emphasize sealing and light protection. Finished resins are generally packaged in dark or opaque containers, filled with nitrogen or with polymerization inhibitors to extend shelf life. Storage conditions require controlled temperature and humidity, avoiding direct sunlight and high temperatures that could trigger pre-curing. Label information and batch records are verified again before shipment to ensure traceability.
Overall, the 3D resin production process integrates polymer synthesis, precise formulation, and strict quality control, with each step interconnected, aiming to provide a stable and high-quality material foundation for photopolymer additive manufacturing. As market demand for high-performance, low-odor, and environmentally friendly resins grows, the process is continuously optimized to balance efficiency, quality, and sustainable development requirements.
