# US 5,700,319 A · Method for extending pigments

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- Number: US 5,700,319 A
- Document ID: US5700319A
- Status: Granted
- Kind: A
- Application number: 08/535,374
- Filed: 1995-09-28
- Granted: 1997-12-23
- Earliest claimed: 1995-09-28
- Assignees: Southern Clay Products, Inc.
- Inventors: Carl J. Bauer; Benjamin W. Knesek
- Web page: https://patentgrep.com/patent/US5700319A

## CPC

- C09D 7/61: inorganic
- C08K 3/346: {Clay}
- Y10S 106/04: Bentonite
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

Unusually high loading levels of smectite minerals are found to provide excellent pigment spacing in aqueous-based coatings, as will enable desired improved hiding, thereby extending the pigment. The level of smectite used in accordance with the invention is sufficiently high that the high gelling efficiency smectites previously used as thixotropes would be inappropriate, and would yield viscosities so high as to render the aqueous coating composition lacking in desired flowability properties. Thus in accordance with the present invention, there is mixed with the aqueous carrier and pigment at least 0.5% by weight of the total composition, of a particulate water swellable smectite which has a gelling efficiency such as to display a 20 rpm Brookfield viscosity of less than 900 cps when subjected to the standard gelling test herein, with the amount of the smectite in the composition not exceeding that which would raise the viscosity of the composition above 110 Krebs Units (KU).

## Claims

### Claim 1

A method for extending the ability of a pigment which is suspended in an aqueous carrier of a coating composition, to obscure an underlying surface upon which said composition has dried to a film, comprising:
admixing with said composition a particulate water swellable smectite in an amount of between 0.5 to 1.5% by weight based on the weight of the total composition, wherein said smectite; has a gelling efficiency such that a dispersion of 5% by weight of the smectite in water at 25.degree. C. displays a 20 rpm Brookfield viscosity of less than 900 cps.

### Claim 2

An aqueous pigment-containing composition having high hiding power to obscure a surface when the composition is applied on said surface and dried to a film; said composition comprising an aqueous carrier; a pigment suspended in said carrier; and particulate water swellable smectite in an amount of between 0.5 to 1.5% by weight based on the weight of the total composition, wherein said smectite; has a gelling efficiency such that a dispersion of 5% by weight of the smectite in water at 25.degree. C. displays a 20 rpm Brookfield viscosity of less than 900 cps.

### Claim 3 (depends on 1)

A method in accordance with claim 1, wherein said smectite is a bentonite.

### Claim 4 (depends on 3)

A method in accordance with claim 3, wherein said bentonite is added to said composition in an amount of between 0.7 to 1.5% by weight.

### Claim 5 (depends on 2)

A composition in accordance with claim 2, wherein said smectite is a bentonite.

### Claim 6 (depends on 5)

A composition in accordance with claim 5, wherein said bentonite is present in said composition in an amount of between 0.7 to 1.5% by weight.