# US 8,785,550 B2 · Method for improving rheological properties of an aqueous pigment slurry and a dispersion agent

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- Number: US 8,785,550 B2
- Document ID: US8785550B2
- Status: Granted
- Kind: B2
- Application number: 12/493,660
- Filed: 2009-06-29
- Published: 2010-06-24
- Granted: 2014-07-22
- Earliest claimed: 2009-06-29
- Assignees: Kemira Oyj
- Applicants: Esko Aarni; Perttu Heiska; Kimmo Huhtala
- Inventors: Esko Aarni; Perttu Heiska; Kimmo Huhtala
- Web page: https://patentgrep.com/patent/US8785550B2

## CPC

- C09D 17/004: {containing an inorganic pigment}
- C09D 7/45: Anti-settling agents
- C09D 17/001: {in aqueous medium (C09D17/003, C09D17/004 take precedence)}
- D21H 19/58: Polymers or oligomers of diolefins, aromatic vinyl monomers or unsaturated acids or derivatives thereof
- C08K 2003/265: {Calcium, strontium or barium carbonate}
- 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)
- D21H: PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)

## Abstract

The invention relates to a method for improving rheological properties of an aqueous pigment slurry. In the method dispersion agent is added to an aqueous phase of a slurry comprising pigment particles or to the aqueous phase into which the pigment particles are to be added. The dispersion agent comprises styrene acrylate copolymer. The invention also relates to a dispersion agent for a pigment slurry comprising a first component comprising styrene acrylate copolymer and a second component comprising a conventional dispersion agent, such as a straight-chain polyacrylate.

## Claims

### Claim 1

A method for improving rheological high shear properties of an aqueous pigment slurry comprising calcium carbonate, kaolin, calcinated kaolin, talc, titanium dioxide, gypsum, chalk, satine white, barium sulphate, sodium aluminium silicate, aluminium hydroxide or any of their mixture, the aqueous pigment slurry having a solids content about 68%, the method comprising adding a dispersion agent to an aqueous phase of a slurry comprising pigment particles or to the aqueous phase into which the pigment particles are to be added, the dispersion agent comprising styrene acrylate copolymer, wherein the styrene acrylate copolymer comprises starch, wherein the dispersion agent improves the rheological properties of the slurry, and wherein the dispersion agent decreases the high shear viscosity of the slurry, and further comprising adding also a conventional dispersion agent comprising straight-chain polyacrylate to the aqueous phase.

### Claim 2 (depends on 1)

The method according to claim 1, comprising adding at least 0.1 parts dispersion agent comprising styrene acrylate copolymer per 100 parts pigment in the slurry.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the dispersion agent comprising the styrene acrylate copolymer is used in the form of an aqueous polymer dispersion having a solids content of 10-50%.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the proportion first component: second component is in the range 50:50-99:1.

### Claim 5

A dispersion agent for a pigment slurry, where the pigment slurry comprises calcium carbonate, kaolin, calcinated kaolin, talc, titanium dioxide, gypsum, chalk, satine white, barium sulphate, sodium aluminium silicate, aluminium hydroxide or any of their mixture, comprising
a first component comprising styrene acrylate copolymer wherein the styrene acrylate copolymer decreases the high shear viscosity of the slurry, wherein the styrene acrylate copolymer comprises starch, the aqueous pigment slurry having a solids content of about 68%,
a second component comprising conventional dispersion agent comprising straight-chain polyacrylate.

### Claim 6 (depends on 5)

The dispersion agent according to claim 5, wherein the proportion first component:second component is in the range 50:50-99:1.

### Claim 7 (depends on 5)

The dispersion agent according to claim 5, wherein the mean particle size of the styrene acrylate copolymer is 20-300 nm.