DLP desktop resin (castable)
Performance characteristics: it is a low viscosity liquid photosensitive resin specially developed for DLP desktop. It has the characteristics of fast curing speed, high precision, high hardness, no ash, low shrinkage, no residue and good lost wax casting effect. It can continuously print non-stick bottom (silica gel or release film) for a long time, and is suitable for most imported or domestic DLP desktops.
Application: jewelry, dentistry and other fields.
DLP desktop photosensitive resin (not cast)
Performance characteristics: it is a low viscosity liquid photosensitive resin specially developed for DLP desktop. It has the characteristics of fast curing speed, high molding accuracy, good surface effect, low odor, low shrinkage and storage resistance. It can continuously print non-stick bottom (silica gel or release film) for a long time, and is suitable for most imported or domestic DLP desktops.
Application scope: small model, hand board making, personalized design DIY, 3D education promotion, jewelry casting and film pasting.
Curing principle
The photocurable resin is mainly composed of monomers (which can be regarded as small molecules), oligomers (which can be regarded as middle molecules) and photoinitiators. (Of course, there may be more than ten kinds of chemical raw materials in the actual formula). The system composed of these three parts is liquid, which is beneficial to industrial operations, such as coating and injection. Then under illumination (usually ultraviolet light), the photoinitiator is excited to generate free radicals, which initiate the polymerization of monomers and oligomers, and finally form ultra-molecular-weight polymers, similar to what we call plastic solids. I drew the following sketch casually:
This field is relatively new, and the classification can only be divided from two aspects: photoinitiator and deoxidizer to improve the surface drying effect.
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Why does light-cured resin feel sticky after curing? The so-called long difference?
A: This is the ontological characteristic of light-cured resin, which is a chemical law and cannot be avoided. Manufacturers all over the world can only minimize the impact, but cannot completely eliminate it. Why? Because photo-curing polymerization is initiated by free radicals, free radicals can easily combine with oxygen to generate oxygen secondary radicals, which is equivalent to losing activity and quenching free radicals. The surface resin is the layer that has the most contact with oxygen, so the more surface resin, the more difficult it is to cure. To do it well, on the one hand, we can find ways to block oxygen. For example, Egger LPCleaner cleaning solution is used, which is actually to soak the resin in the cleaning solution to isolate oxygen. Or directly use the closed system to fill nitrogen to isolate oxygen.
The second method is to add oxygen atoms that can capture oxygen-secondary free radicals to the resin formula and re-release high-activity free radicals. This substance is usually active amine (with poor effect and cheap price, and the resin turns yellow) or mercaptan, which has a good effect, but it will stink. Some so-called surface drying resins usually add mercaptan. Don't use this advice if you can. You'd rather use detergent or nitrogen.