Solvochromic effect pigments, method of production and use thereof

Patent metadata

Field	Value
Publication number	US-12584022-B2
Application number	US-202118016600-A
Country	US
Kind code	B2
Filing date	Jul 22, 2021
Priority date	Jul 23, 2020
Publication date	Mar 24, 2026
Grant date	Mar 24, 2026

Abstract

The present invention is directed to effect pigments with solvochromic properties. These effect pigments have a structure comprising a substrate in platelet form and a coating applied to the substrate, wherein the coating comprises: optionally a layer ( 1 ) comprising or consisting of at least one of tin oxide, tin hydroxide and/or tin oxide hydrate, a layer ( 2 ) comprising at least one of metal oxide, metal hydroxide and/or metal oxide hydrate, and a layer ( 3 ) comprising at least one of metal oxide, metal hydroxide and/or metal oxide hydrate, wherein the layers ( 2 ) and ( 3 ) comprise in their metal oxide, metal hydroxide and/or metal oxide hydrate in a majority two different metal ions from the group consisting of Ti, Fe, Sn or Zr and a further spacer layer ( 4 ) being located in between layers ( 2 ) and ( 3 ), wherein layer ( 4 ) has a porous structure comprising cavities and connectors. The solvochromic properties denote to the effect pigment having a first interference color under ambient atmosphere which changes reversibly to a second interference color, when the effect pigment comes into contact with a solvent.

First claim

The invention claimed is:

1 . An effect pigment having solvochromic properties comprising substrates in platelet form and a coating applied to the substrates, wherein the coating comprises
an optional layer 1 comprising at least one of tin oxide, tin hydroxide and/or tin oxide hydrate, a layer 2 comprising at least one of metal oxide, metal hydroxide and/or metal oxide hydrate, a layer 3 comprising at least one of metal oxide, metal hydroxide and/or metal oxide hydrate, wherein a majority of the metal oxide, metal hydroxide and/or metal oxide hydrate of the layers 2 and 3 comprise two different metal ions selected from Ti, Fe and Zr, and a spacer layer 4 located in between layers 2 and 3 , wherein the layer 4 has a porous structure comprising cavities and connectors and a median area of cavity size distribution A 50 in a range of 80 to 600 nm 2 .

2 . The effect pigment having solvochromic properties according to claim 1 , wherein the solvochromic properties denote to the effect pigment having a first interference color under ambient atmosphere which changes reversibly to a second interference color, when the effect pigment comes into contact with a solvent.

3 . The effect pigment having solvochromic properties according to claim 1 , wherein the layers 2 and 3 are mainly composed of TiO 2 .

4 . The effect pigment having solvochromic properties according to claim 1 , wherein metal ions comprised in the connectors in the spacer layer 4 are mainly Fe or Zr.

5 . The effect pigment having solvochromic properties according to claim 1 , wherein the molar ratio of Ti to any of Fe or Zr in layers 2 , 3 and 4 is in a range of 1.5 to 4.0.

6 . The effect pigment having solvochromic properties according to claim 1 , wherein the substrates in platelet form include any one or more of metal platelets, natural mica platelets, synthetic mica platelets, iron mica, glass platelets, SiO 2 platelets, Al 2 O 3 platelets, kaolin platelets, talc platelets, and bismuth oxychloride platelets.

7 . An effect pigment having solvochromic properties according to claim 1 , wherein the average thicknesses of layers 2 or 3 independently are in a range of 40 to 160 nm.

8 . The effect pigment having solvochromic properties according to claim 1 , wherein the spacer layer 4 has a geometric thickness h a in a range of 100 to 400 nm.

9 . A process for manufacturing an effect pigment having solvochromic properties comprising substrates in platelet form and a coating applied to the substrates, wherein the coating comprises
an optional layer 1 comprising at least one of tin oxide, tin hydroxide and/or tin oxide hydrate, a layer 2 comprising at least one of metal oxide, metal hydroxide and/or metal oxide hydrate, a layer 3 comprising at least one of metal oxide, metal hydroxide and/or metal oxide hydrate, wherein a majority of the metal oxide, metal hydroxide and/or metal oxide hydrate of the layers 2 and 3 comprise two different metal ions selected from—Ti, Fe and Zr, and a spacer layer 4 located in between layers 2 and 3 , wherein the layer 4 has a porous structure comprising cavities and connector and a median area of cavity size distribution A 50 in a range of 80 to 600 nm 2 , the process comprising:
(i) optionally applying an uncalcined layer comprising at least one of tin oxide, tin hydroxide and/or tin oxide hydrate to the substrates in platelet form,
(ii) sequentially applying three uncalcined layers A, B and C each consisting essentially of a single metal oxide, metal hydroxide and/or metal oxide hydrate, where the layers A, B and C are arranged directly one on top of another and wherein the metal ions of layers A, B and C are selected from Ti, Fe and Zr, wherein the metal ion from layer B is different to the metal ions of layers A or C,
(iii) separating the effect pigment obtained in (ii) from the liquid phase and drying the product,
(iv) calcining the dried effect pigment obtained from (iii) at a temperature in a range of 300° C. to 600° C., wherein the metal ions present in layer B diffuse at least partly into layer A and/or layer C during the calcination step to form the layer 4 .

10 . The process for manufacturing an effect pigment having solvochromic properties as claimed in claim 9 , wherein layers A and C are TiO 2 and layer B is Fe 2 O 3 or ZrO 2 .

11 . The process for manufacturing an effect pigment having solvochromic properties as claimed in claim 9 , wherein drying the product commences at a temperature ranging from 70° C. to 160° C.

12 . The process for manufacturing an effect pigment having solvochromic properties as claimed in claim 9 , wherein thicknesses of the layers A and C are independently in a range of more than 50 to 240 nm.

13 . The process for manufacturing an effect pigment having solvochromic properties as claimed in claim 9 , wherein a stack of the uncalcined layers A, B and C and the optional uncalcined layer comprising at least one of tin oxide, tin hydroxide and/or tin oxide hydrate does not have an additional layer adjacent to the uncalcined layer A or the optional uncalcined layer and/or the uncalcined layer C, the additional layer being composed of any metal oxide including a metal ion selected from Ti, Fe, Sn, Mn, Zr, Ca, Sr, Ba, Ni, Ag, Zn, Cu, Ce, Cr and Co.

14 . An article comprising a coating which contains an effect pigment having solvochromic properties as claimed in claim 1 .

15 . The effect pigment having solvochromic properties according to claim 1 , wherein the substrates in platelet form comprise metallic substrates coated with at least one of metal oxide, metal hydroxide and/or metal oxide hydrate.

16 . The process for manufacturing an effect pigment having solvochromic properties as claimed in claim 9 , wherein the substrates in platelet form are nonmetallic.

17 . A bronzing composition comprising a binder and the effect pigment having solvochromic properties according to claim 1 .

18 . A coating application comprising a plurality of layers, a top coating of the plurality of layers comprising the effect pigment having solvochromic properties according to claim 1 .

Assignees

• Eckart Gmbh

Inventors

• Grüner Michael
• Kaupp Günter
• Malz Miriam

Classifications

• C09C2220/106

  comprising only a drying or calcination step of the finally coated pigment · CPC title

• C09C2200/401

  Inorganic protective coating · CPC title

• C09C2200/1004

  the core comprising at least one inorganic oxide, e.g. Al2O3, TiO2 or SiO2 · CPC title

• C09C3/043

  Drying, calcination · CPC title

• C09C3/006

  Combinations of treatments provided for in groups C09C3/04 - C09C3/12 · CPC title