August 10, 2005

Interference Pigment
● Patent No. U.S. 6,500,251 B1
This patent, awarded to Merck
Patent Gesellschaft, Darmstadt,
Germany, covers a multilayer interference
pigment. The pigment is comprised
of a platelet shaped titanium
dioxide as carrier material, coated
with alternating layers of metal oxides
of low refractive index and colorless
non-absorbing metal oxides of high
refractive index, each layer having a
thickness of from 20 to 500 nm, the
difference in the refractive indices
being at least 0.1, which is obtained by
solidification and hydrolysis of an
aqueous solution of a thermally
hydrolyzable inorganic titanium compound
on a continuous belt, detachment
of the resulting coat, whereby a
platelet shaped titanium dioxide pigment
is formed, coating of the resulting
titanium dioxide platelets, with or
without drying in between, by a wet
method with, alternately, a metal
oxide hydrate of low refractive index
and a colorless non-absorbing metal
oxide hydrate of high refractive index
by hydrolysis of the corresponding,
water soluble inorganic metal compounds,
separation, drying and,
optionally, calcining of the material
blog comments powered by Disqus