METHOD OF MAKING COLORED PIGMENTS HAVING PEARLESCENT QUALITIES

• US 3,647,492 A
• Filed: 11/20/1970
• Issued: 03/07/1972
• Est. Priority Date: 11/20/1970
• Status: Expired due to Term

• Current Assignee: Mallinckrodt Incorporated (Mallinckrodt plc)
• Original Assignee: Douglas W. Chapman, Richard Dean Overley, Robert D. Rands Jr, Ronald S. Schreiber
• Inventors: Chapman, Douglas W., Overley, Richard Dean, Rands, Robert D. Jr., Schreiber, Ronald S.
• Primary Examiner(s): Poer, James E.
• Application Number:
  US05/091,585
• Time in Patent Office: 473 Days
• Field of Search: 106/291,300,38F,38P
• US Class Current: 106/418
• CPC Class Codes: C01P 2004/84 one phase coated with the other
• CPC Class Codes: C09C 1/0015 Pigments exhibiting interference colours, e.g. transparent platelets of appropriate thinness or flaky substrates, e.g. mica, bearing appropriate thin transparent coatings
• CPC Class Codes: C09C 1/0081 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 Class Codes: C09C 2200/401 Inorganic protective coating
• CPC Class Codes: C09C 2200/403 Low molecular weight materials, e.g. fatty acids
• CPC Class Codes: C09C 2220/10 Wet methods, e.g. co-precipitation

Abstract

Pearlescent substrate may be modified with finely divided insoluble pigments by dispersing an adhesive binder substance in an aqueous suspension of the said substrate and pigment, effecting precipitation of the said binder, and recovering from the reaction mixture a modified, e.g., colored, product which substantially retains the pearlescent luster of the substrate. The product comprises the said substrate to which particles of the finely divided pigment are intimately bound by means of the binder. For example, the substrate may be a pearlescent bismuth oxychloride. The binder material may be selected from fatty acids or insoluble salts of fatty acids, silicic acid or insoluble salts of silicic acid, insoluble salts of alginic acid or suitable water-dispersible polymeric adhesives. Simple mixtures of the base with the pigment but without the binder of the present invention generally fail to exhibit the pearlescent qualities of the unpigmented substrate.

Claims

2. A method according to claim 1 wherein the adhesive binder substance is selected from the group consisting of fatty acids, silicic acid, alginic acid, and the water-insoluble salts thereof.

3. A method according to claim 1 wherein the precipitation of the adhesive binder substance is effected by dispersing in the aqueous suspension of the pearlescent substrate and the modifying pigment a soluble salt of an acid selected from the group consisting of fatty acids, alginic acid and silicic acid, and thereafter adding to the said suspension a reactant, selected from strong acids and soluble salts, which combines with the said acid to form an insoluble compound.

4. A method according to claim 1 wherein the adhesive binder substance is a water-dispersible adhesive polymer.

5. A method according to claim 1 wherein the pearlescent substrate is selected from nacreous bismuth oxychloride and mica platelets coated with an epitaxial deposit of bismuth oxychloride.

6. A colored pigment comprising a pearlescent substrate to which is intimately bound by means of an adhesive binder substance particles of a finely divided water-insoluble pigment of a selected color.

7. A pigment according to claim 6 wherein the said substrate is selected from nacreous bismuth oxychloride, mica platelets coated with an epitaxial deposit of bismuth oxychloride, and mica platelets coated with titanium dioxide.

8. A pigment according to claim 6 wherein the said water-insoluble pigment is bound to the said substrate by means of an adhesive binder substance selected from fatty acids, silicic acid, alginic acid, and the water-insoluble salts thereof.

9. A pigment according to claim 6 wherein the proportion of water-insoluble pigment to pearlescent substrate is just sufficient to impart the selected color.

10. A pigment according to claim 6 wherein the particles of water-insoluble pigment are bonded to the substrate by the binder without concealing the pearlescent luster of the substrate.

11. A pigment according to claim 6 wherein the substrate is mica coated with an epitaxial deposit of bismuth oxychloride and the water-insoluble pigment is titanium dioxide.