Omnidirectional structural color paint
View Patent ↗A paint composition is disclosed, the paint having a binder and an omnidirectional structural color pigment dispersed throughout the binder. The omnidirectional structural color pigment can be made from a plurality of flakes that have a multilayer structure, the pigment and the paint having a reflection band of less than 200 nanometers when viewed from angles between 0 to 45 degrees.
1. A paint composition comprising:
a binder and an omnidirectional structural color pigment dispersed throughout said binder to form a paint, said omnidirectional structural color pigment made from a plurality of flakes having a multilayer structure with a first layer of first material having a first predefined thickness d H and a first index of refraction n H between 1.75 and 3, and a second layer of a second material having a second predefined thickness d L and a second index of refraction n H between 1 and 3:
said first predefined thickness d H and said second predefined thickness d L predefined such that said multilayer structure has a reflection band of less than 200 nanometers and a dispersion of a center wavelength Δλ c of said reflection band defined as:
Δλ
c
=
λ
c
θ
0
=
0
°
-
λ
c
θ
0
=
45
°
=
2
(
n
H
d
H
1
+
n
L
d
L
1
-
n
H
d
H
1
-
n
0
2
n
H
2
-
n
L
d
L
1
-
n
0
2
n
L
2
)
is less than 200 nm when said multilayer stack is viewed from 0 degrees and 45 degrees and where λ c at θ 0 =0° is a center wavelength of said reflection band when said multilayer stack is viewed from 0°, λ c at θ 0 =45° is a center wavelength of said reflection band when said multilayer stack is viewed from 45° and n 0 is a refractive index of a medium beyond said multilayer structure.
2. The paint composition of claim 1 , wherein said binder is selected from a group consisting of a natural resin, a synthetic resin, a dry oil and water.
3. The paint composition of claim 2 , wherein said synthetic resin is selected from a group consisting of an acrylic, a vinyl-acrylic, a vinyl acetate/ethylene, a polyurethane, a polyester, a melamine resin, an epoxy and combinations thereof.
4. The paint composition of claim 1 , wherein said first layer and said second layer have a refractive index contrast between 0.2 and 1.0.
5. The paint composition of claim 4 , wherein at least a portion of said plurality of flakes have an intervening layer between a pair of multilayer structures, said intervening layer selected from a group consisting of an absorbing layer and a reflecting layer.
6. The paint composition of claim 1 , further comprising a solvent.
7. The paint composition of claim 6 , wherein said paint is a spray paint.
8. The paint composition of claim 6 , wherein said solvent is selected from a group consisting of an organic solvent and water.
9. The paint composition of claim 8 , wherein said organic solvent is selected from a group consisting of an aliphatic, an aromatic, an alcohol, a ketone, white spirit, a petroleum distillate, an ester, a glycol ether and combinations thereof.
10. The paint composition of claim 1 , further comprising an additive selected from a group consisting of a surface tension modifier, a flow modifier, a surface finish modifier, a wet edge modifier, a pigment stability modifier, an antifreeze modifier, a foam control modifier, a catalyst, a thickener, a stabilizer, an emulsifier, a texture modifier, an adhesion modifier, a flattener, a biocide and combinations thereof.
11. The paint composition of claim 1 , further comprising a non-structural color pigment dispersed throughout said binder.
12. The paint composition of claim 1 , wherein said structural color pigment is between 1 and 20 wt % of an overall composition.
13. The paint composition of claim 1 , wherein said paint is a base coat.
14. The paint composition of claim 1 , wherein said paint is a base coat of a self-stratifying paint coating.