Non-conductive pigments in a multi-layer film and methods of making

Patent metadata

Field	Value
Publication number	US-2025383490-A1
Application number	US-202318834617-A
Country	US
Kind code	A1
Filing date	Jan 31, 2023
Priority date	Jan 31, 2022
Publication date	Dec 18, 2025
Grant date	—

Abstract

Non-conductive pigments, coatings, films, articles, methods of manufacture thereof, and methods of use thereof are provided. The non-conductive pigment comprises a flake comprising at least four layers comprising alternating low index of refraction layers and high index of refraction layers. A difference in an average index of refraction between adjacent layers as measured over a wavelength range of 400 nm to 700 nm is at least 1.5. In certain examples, the high index of refraction layers have a Q value of at least 0.930, such as, at least 0.950 or at least 1.000. The pigment has an average visible specular reflectance of at least 80% and the pigment exhibits and the flake has a bandwidth of at least 300 nm between an upper wavelength and a lower wavelength at which a specular reflectance drops below 50%.

First claim

1 - 21 . (canceled)

22 . A non-conductive pigment comprising:
a flake comprising at least four layers comprising alternating low index of refraction layers and high index of refraction layers, wherein a difference in an average index of refraction between adjacent layers as measured over a wavelength range of 400 nm to 700 nm is at least 1.5, wherein the high index of refraction layers have a Q value of at least 0.930, which is given by

Q
=

(

3
/
2

)

×

(

n
ave

-

(

k
ave

/
2

)

)

/

(

n
ave

+
2

)

,

where
k ave is an average extinction coefficient of the high index of refraction layers over the wavelength range of 400 nm to 700 nm; and
n ave is an average index of refraction of the high index of refraction layers over the wavelength range of 400 nm to 700 nm, and

the non-conductive pigment has an average visible specular reflectance of at least 80%, and the flake has a bandwidth of at least 300 nm between an upper wavelength and a lower wavelength at which a specular reflectance drops below 50%.

23 . The non-conductive pigment of claim 22 , having a near infrared specular reflectance less than 40% with a near infrared transmittance greater than 60% at at least one of a wavelength of 905 nm or 1550 nm.

24 . The non-conductive pigment of claim 22 , wherein the high index of refraction layers, individually, comprise crystalline silicon, hydrogenated amorphous silicon, polycrystalline silicon, hydrogenated silicon, gallium arsenide, gallium phosphide, iron sulfide, germanium, indium phosphide, or a combination thereof and the low index of refraction layers, individually, comprise silicon oxide, silicon nitride, indium tin oxide, magnesium fluoride, tantalum oxide, zirconium oxide, a polymer, or a combination thereof.

25 . The non-conductive pigment of claim 22 , wherein the low index of refraction layers, individually, comprise a polymer.

26 . The non-conductive pigment of claim 22 , wherein the high index of refraction layers comprise silicon, and the low index of refraction layers comprise silicon oxide.

27 . The non-conductive pigment of claim 22 , wherein the high index of refraction layers are inorganic.

28 . The non-conductive pigment of claim 22 , wherein the low index of refraction layers are organic, or a combination of organic and inorganic.

29 . The non-conductive pigment of claim 22 , wherein the pigment has a resistivity of at least 1 Ωcm.

30 . The non-conductive pigment of claim 22 , wherein each of the high index of refraction layers have a thickness in a range of 10 nm to 110 nm, and the low index of refraction layers each have a thickness in the range of 80 nm to 180 nm.

31 . The non-conductive pigment of claim 22 , wherein each layer in that at least four layers has an average extinction coefficient as measured over the wavelength range of 400 nm to 700 nm of less than 2.0.

32 . The non-conductive pigment of claim 22 , wherein at least two of the high index of refraction layers have different average indexes of refractions, thicknesses, compositions, or a combination thereof.

33 . The non-conductive pigment of claim 22 , wherein at least two of the low index of refraction layers have different average indexes of refractions, thicknesses, compositions, or a combination thereof.

34 . The non-conductive pigment of claim 22 , wherein the non-conductive pigment is shaped as a flake having an aspect ratio of at least five, the aspect ratio being an average lateral size of the pigment divided by an average thickness of the pigment.

35 . A coating composition comprising:
the non-conductive pigment of claim 22 ; and a film-forming resin.

36 . A coating layer comprising the non-conductive pigment of claim 22 , wherein, when applied to a substrate, the coating layer has:
(i) an L 15 value of at least 70, as measured using a multi-angle spectrophotometer at the measurement angle of 15° relative to a specular direction, with D65 illumination and 10° observer; (ii) a flop index of at least 10, as measured using a multi-angle spectrophotometer, with D65 illumination and 10° observer according to the following equation:

Flop
⁢

Index

=

2.69

(

L
15

-

L
110

)

1.11

/

(

L
45

)

0.86

,

wherein:
L 15 is CIE L* value measured at a aspecular angle of 15°;
L 45 is CIE L* value measured at a aspecular angle of 45°; and
L 110 is CIE L* value measured at a aspecular angle of 110°; and

(iii) one-way radar transmission loss of no greater than 1.5 dB, as measured using a radar transmission system at a wavelength in a range of 76 GHz to 81 GHz.

37 . A method for improving radio detection and ranging in an electromagnetic radiation frequency range of 76 GHz to 81 GHz, with automotive radar sensors that are mounted behind metallic effect-coated articles, the method comprising:
applying a coating composition comprising the non-conductive pigment of claim 22 to an automotive substrate; and curing the applied coating composition to form a coated automotive substrate.

38 . A method of making a non-conductive pigment, the method comprising:
depositing four or more alternating layers of a high index of refraction layer and a low index of refraction layer over a substrate to form a composite, wherein the high index of re

Assignees

• Ppg Ind Ohio Inc

Inventors

• Decker Eldon L
• Harris Rachel Dory
• Duarte Nicolas Benjamin
• Connor Daniel

Classifications

• C09C2210/10

  Optical properties in the IR-range, e.g. camouflage pigments · CPC title

• C09C2200/303

  Thickness of a layer with low refractive material · CPC title

• C09C2200/302

  Thickness of a layer with high refractive material · CPC title

• C09C1/0051 Primary

  comprising a stack of coating layers with alternating low and high refractive indices, wherein the first coating layer on the core surface has the low refractive index · CPC title

• C08K9/08

  Ingredients agglomerated by treatment with a binding agent · CPC title