Photosensitive resin, commonly known as UV cured shadowless adhesive or UV resin(adhesive), is mainly composed of polymer monomers and prepolymers, with the addition of light (UV) initiators, also known as photo sensitizers. Under a certain wavelength of ultraviolet light irradiation, it will immediately trigger a polymerization reaction and complete solid-state conversion.
Photosensitive resin refers to the material used for rapid prototyping through photo-polymerization, which is liquid photo-curable resin or liquid photosensitive resin. It is mainly composed of oligomers, photo-initiators and diluents. In the past two years, photosensitive resins have been used in the emerging 3D printing industry and have been favored and valued by the industry due to their excellent characteristics.
The photosensitive resin used in 3D printing is basically composed of the following components, just like the photosensitive resin used in other industries.
1. Photosensitive prepolymer
Photosensitive prepolymers refer to low molecular weight prepolymers that can be cured by light, with a molecular weight typically between 1000 and 5000. It is the determining factor of the final performance of the material.The prepolymers of photosensitive resin materials mainly include acrylic esterified epoxy resin, unsaturated polyester, polyurethane and polysulfide, polyene photo-curable resin etc.
2. Active diluent
Active diluents mainly refer to low molecular weight epoxy compounds containing epoxy groups, which can participate in the curing reaction of epoxy resin and become part of the cross-linking network structure of epoxy resin cured products.
3. Photoinitiators and photosensitizers
Both photoinitiators and photosensitizers play a role in promoting polymerization during the polymerization process, but there is a clear difference between the two. Photoinitiators act as initiators during the reaction process, participate in the reaction, and consume during the reaction process; The photosensitizer acts as an energy transfer agent, equivalent to a catalyst, and is not consumed during the reaction process. Photoinitiators are active substances such as free radicals or cations formed by absorbing light energy to initiate reactions. The main photoinitiators include benzoin and its derivatives, acetophenone derivatives, triaryl sulfur-containing salts, etc.The mechanism of action of photosensitizers mainly includes three types: energy conversion, hydrogen extraction and generation of charge transfer complexes. The main photosensitizers include benzophenone, misoprostone, thioanthracene ketone, and benzoyl.