| Ultraviolet ray (UV) hardening is the method
of using prepolymers, monomer, and light
polymerization starting dose to form ultraviolet
ray UV hardened resin, radiating light rays
(a few seconds ~ a few tens of seconds) having
200~400nm wavelength, and have it hardening
in a short span of time. |
 |
A. |
UV rays normally pertain to light rays (electromagnetic
waves) with wavelength 100 ~ 400nm. Please
refer to the figure below. If the light (electromagnetic
wave) and the wavelength are inversely proportional,
energy E will increase. |
The UV ray wavelengths used by UV ray hardening
are mainly the 254 nm and 365 nm of the emission
ray spectrum of mercury.
Property of 254 nm UV ray is
: Although it
has great amount of energy, it
is difficult
to reach the interior of the
resin. The energy
of 365 nm UV ray is smaller,
but it can better
penetrate the interior of the
UV ray resin. |
|
B. |
UV ray resin is normally formed from prepolymers,
monomers, light polymerization
starting dose,
and additives. Each has a function
as indicated
below. |
| Prepolymers |
Main ingredient of UV ray hardening resin |
| Monomer |
Reactive diluting agent used to adjust resin's
viscosity |
| Light polymerization starting dose |
A compound which starts light polymerization
reaction upon being radiated by UV rays |
| Additives |
Filling agents, coloring agents, molding
agents |
|
|
C. |
The summary of light polymer reaction is:
If radiated by UV rays, light polymerization
starting dose will become free radicals.
This reaction is close to the polymeric double
union (unsaturated radicals) of prepolymers
and monomers, letting the double union part
become activate and consequently form a chain
union. Please refer to the figure below. |
| Light polymerization reaction is hindered
by the oxygen in the air. Hence, to handle
UV ray hardening resin surface in contact
with air within a short span of time, Type
B light focusing lens having 254 nm with
higher ultraviolet ray intensity is more
effective. Also, if the film thickness of
the solidified resin is thicker (above 1mm),
Type C light focusing lens having visible
light of 405 nm and 436 nm is more effective.
Please refer to the figure below. |
| Copyright (C) SAN-EI ELECTRIC CO.,LTD. |
|
