Search results
Results From The WOW.Com Content Network
A common functional group used in negative resists is epoxy functional groups. An example of a widely used polymer of this class is SU-8. SU-8 was one of the first polymers used in this field, and found applications in wire board printing. [17] In the presence of a cationic photoinitiator photopolymer, SU-8 forms networks with other polymers in ...
UV stabilizers in plastics usually act by absorbing the UV radiation preferentially, and dissipating the energy as low-level heat. The chemicals used are similar to those in sunscreen products, which protect skin from UV attack. They are used frequently in plastics, including cosmetics and films. Different UV stabilizers are utilized depending ...
Cationic polymerization is used in the curing of epoxy resins in the presence of UV in the industry. [16] Light energy from UV breaks apart photoinitiaters, forming an acidic solution which then donates a proton to the polymer. The monomers then attach themselves to the polymer, forming longer and longer chains leading to a cross-linked network.
In chemistry, a photoinitiator is a molecule that creates reactive species (free radicals, cations or anions) when exposed to radiation (UV or visible). Synthetic photoinitiators are key components in photopolymers (for example, photo-curable coatings, adhesives and dental restoratives).
SU-8 is a commonly used epoxy-based negative photoresist. Negative refers to a photoresist whereby the parts exposed to UV become cross-linked, while the remainder of the film remains soluble and can be washed away during development. As shown in the structural diagram, SU-8 derives its name from the presence of 8 epoxy groups.
It has good chemical and heat resistance, high gloss, good antistatic properties, and is tough and rigid. It is used in applications requiring weatherability, e.g. commercial siding, outside parts of vehicles, or outdoor furniture. [4] ASA is compatible with some other plastics, namely polyvinyl chloride and polycarbonate. ASA-PVC compounds are ...
One very common positive photoresist used with the I, G and H-lines from a mercury-vapor lamp is based on a mixture of diazonaphthoquinone (DNQ) and novolac resin (a phenol formaldehyde resin). DNQ inhibits the dissolution of the novolac resin, but upon exposure to light, the dissolution rate increases even beyond that of pure novolac.
UV LEDs are also used in digital print applications and inert UV curing environments. Power densities approaching 3 W/cm 2 (30 kW/m 2 ) are now possible, and this, coupled with recent developments by photo-initiator and resin formulators, makes the expansion of LED cured UV materials likely.