Colorant including a mixture of pigments

Patent metadata

Field	Value
Publication number	US-2018044534-A1
Application number	US-201715790854-A
Country	US
Kind code	A1
Filing date	Oct 23, 2017
Priority date	Oct 1, 2012
Publication date	Feb 15, 2018
Grant date	—

Abstract

A colorant including a mixture of pigments is disclosed. The pigments have a similar coloration but different resistance to corrosion. The mixing ratio is selected to optimize the corrosion resistance against color brightness, and/or acidic corrosion resistance against alkali corrosion resistance of the colorant.

First claim

What is claimed is:

1 . A colorant comprising a mixture of a first pigment P 1 and a second pigment P 2 having chroma C* 1 and C* 2 , respectively, wherein each of C* 1 and C* 2 is at least 10 units in L*a*b* color space under illumination by a D65 standard light source using a 10 degree observer function, wherein a color difference between the first and second pigments is no more than 30 hue degrees in a polar projection of the L*a*b* color space;
wherein the first pigment P 1 undergoes a corrosion-induced color change ΔE*(P 1 ) when immersed into a corrosive solution, and wherein the second pigment P 2 undergoes a corrosion-induced color change ΔE*(P 2 ) when immersed into the corrosive solution, wherein ΔE*(P 2 )<ΔE*(P 1 ). whereby a corrosion-induced color change ΔE*(P 1 +P 2 ) of the colorant upon immersion into the corrosive solution satisfies the condition ΔE*(P 1 +P 2 )<ΔE*(P 1 ), wherein the corrosive solution is selected from the group consisting of 2% by weight aqueous solution of H 2 SO 4 , 2% by weight aqueous solution of NaOH, 1.2% by weight aqueous solution of sodium hypochlorite, and water.

2. The colorant of claim 1 , wherein the first and second pigments comprise first and second color-shifting interference pigments, respectively, wherein each of C* 1 and C* 2 and the color difference between the first and second pigments are measured using a d/8° integrating sphere geometry.

3 . The colorant of claim 2 , wherein the corrosion-induced color changes of the first and second pigments and the colorant comprise base-induced color changes ΔE* B (P 1 ), ΔE* B (P 2 ), and ΔE* B (P 1 +P 2 ), respectively, upon immersion into the 2% by weight aqueous solution of NaOH.

4 . The colorant of claim 3 ,
wherein the first pigment P 1 undergoes an acid-reduced color change ΔE* A (P 1 ), upon immersion into the 2% by weight aqueous solution of H 2 SO 4 , wherein ΔE* A (P 1 )<ΔE* B (P 1 ); wherein the second pigment P 2 undergoes an acid-induced color change ΔE* A (P 2 ) upon immersion into the 2% by weight aqueous solution of H 2 SO 4 , wherein ΔE* A (P 2 )>ΔE* B (P 2 ), wherein ΔE* A (P 2 )>ΔE* A (P 1 ), whereby an acid-induced color change ΔE* A (P 1 +P 2 ) of the colorant upon immersion into the 2% by weight aqueous solution of H 2 SO 4 satisfies the condition ΔE* A (P 1 +P 2 )<ΔE* A (P 2 ).

5 . The colorant of claim 2 , wherein C* 1 >C* 2 , whereby chroma of the colorant C* c satisfies the condition C* c >C* 2 .

6 . The colorant of claim 5 , wherein C* 1 and C* 2 are each at least 15 units in the L*a*b* color space.

7 . The colorant of claim 6 , wherein C* 1 and C* 2 are each at least 25 units in the L*a*b* color space.

8 . The colorant of claim 1 , wherein the proportion of the first and second pigments in the colorant is between 25:75 and 75:25 by weight.

9 . The colorant of claim 2 , wherein ΔE*(P 1 +P 2 )<½ΔE*(P 1 ).

10 . The colorant of claim 2 , wherein the color difference between the first and second pigments is no more than 20 hue degrees in the polar projection of the L*a*b* color space.

11 . The colorant of claim 10 , wherein the color difference between the first and second pigments is no more than 15 hue degrees in the polar projection of the L*a*b* color space.

12 . The colorant of claim 2 , wherein the first and second color-shifting interference pigments each comprise a plurality of color-shifting interference flakes having at least five layers including a metal layer, wherein the color-shifting interference flakes of the first color-shifting interference pigment comprise chromium in their outer layers, and the color-shifting interference flakes of the second color-shifting interference pigment comprise bismuth or iron in their outer layers.

13 . The colorant of claim 12 , wherein the metal layer of the color-shifting interference flakes of the first and/or second pigments comprise chromium, aluminum, and/or ferrochrome.

14 . The colorant of claim 2 , further comprising a third pigment P 3 having chroma C* 3 of at least 10 units in the L*a*b* color space under illumination by the D65 standard light source using the 10 degree observer function, wherein a color difference between the first, second, and third pigments is no more than 30 hue degrees in a polar projection of the L*a*b* color space;
wherein the third pigment P 3 undergoes a corrosion-induced color change ΔE*(P 3 ) when immersed into the corrosive solution, wherein ΔE*(P 3 )<ΔE*(P 2 ).

15 . A method of manufacture of a colorant, the method comprising:
(a) providing a first pigment P 1 and second pigment P 2 each having chroma C* 1 and C* 2 , respectively, wherein each of C* 1 and C* 2 is at least 10 units in L*a*b* color space under illumination by a D65 standard light source using the 10 degree observer function, wherein a color difference between the first and second pigments is no more than 30 hue degrees in the polar projection of the L*a*b* color space; wherein the first pigment P 1 undergoes a corrosion-induced color change ΔE*(P 1 ) upon immersion into a corrosive solution, and wherein the second pigment P 2 undergoes a corrosion-induced color change ΔE*(P 2 ) upon immersion into the corrosive solution, wherein ΔE*(P 2 )<ΔE*(P 1 ); (b) mixing together the first and second pigments to obtain the colorant having a corrosion-induced color change ΔE*(P 1 +P 2 ) upon immersion into the corrosive solution satisfying the condition ΔE*(P 1 +P 2 )<ΔE*(P 1 ), wherein the corrosive solution is selected from the group consisting of 2% by weight aqueous solution of H 2 SO 4 , 2% by weight aqueous solution of NaOH, 1.2% by weight aqueous solution of sodium hypochlorite bleach, and water.

16 . The method of claim 15 , wherein in step (a), the first and second pigments comprise first and second color-shifting interference pigments, respectively, wherein each of C* 1 and C* 2 and the color difference between the first and second pigments are measured using a d/8° integrating sphere geometry.

17 . The method of claim 16 , wherein, in step (a),
the corrosion-induced color changes of the first and second pigments and the colorant comprise base-induced color changes ΔE* B (P 1 ), ΔE* B (P 2 ), and ΔE* B (P 1 +P 2 ) respectively, upon immersion into the 2% by weight aqueous solution, of NaOH; the first pigment undergoes an acid-induced color change ΔE* A (P 1 ) upon immersion into the 2% by weight aqueous solution of H 2 SO 4 , wherein ΔE* A (P 1 )<ΔE* B (P 1 ); and the second pigment undergoes an acid-induced color change ΔE* A (P 2 ) upon immersion into the 2% by weight aqueous solution of H 2 SO 4 , wherein ΔE* A (P 2 )>ΔE* B (P 2 ); wherein ΔE* A (P 2 )>ΔE* A (P 1 ), whereby an acid-induced color change ΔE* A (P 1 +P 2 ) of the colorant upon immersion into the 2% by weight aqueous solution of H 2 SO 4 satisfies the condition ΔE* A (P 1 +P 2 )<ΔE* A (P 2 ).

18 . The method of claim 17 , wherein in step (a), the first color-shifting interference pigment comprises a plurality of multi-layer color-shifting interference flakes having chromium in outer layers thereof, and the second color-shifting interference pigment comprises a plurality of multi-layer color-shifting interference flakes having bismuth or iron in outer layers thereof.

19 . The method of claim 16 , wherein step (b) includes mixing in a third pigment P 3 having chroma C* 3 of at least 10 units in the L*a*b* color space under illumination by the D65 standard light source using the 10 degree observer function, wherein a color difference bet

Assignees

• Viavi Solutions Inc

Inventors

• Delst Cornelis Jan
• Raksha Vladimir P
• De La Fuente David

Classifications

• C01P2006/66

  Hue (H*) · CPC title

• C01P2006/65

  Chroma (C*) · CPC title

• C09C3/04 Primary

  Physical treatment, e.g. grinding or treatment with ultrasonic vibrations {(C09C3/006 takes precedence)} · CPC title

• C09C1/0015 Primary

  Pigments exhibiting interference colours, e.g. transparent platelets of appropriate thinness or flaky substrates, e.g. mica, bearing appropriate thin transparent coatings · CPC title

• C09C1/0081

  Composite particulate pigments or fillers, i.e. containing at least two solid phases, except those consisting of coated particles of one compound (C09C1/0015, C09C1/0078 take precedence) · CPC title