US 5,412,019 AGranted

Polymer-modified particulate titanium dioxide

AssigneeImperial Chemical Industries PLC

InventorsBrian J. Roulstone, Julian A. Waters

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Abstract

The tendency for hard and irregular particles of titanium dioxide pigment to adversely affect the sheen and coin mar resistance of a dried coating into which they have been incorporated is reduced by modifying the particles with polymer particles which have been preformed and are therefore of a more pre-determinable shape and size. The polymer particles are chemically bonded to a polymeric water-soluble compound containing moieties which are adsorbable onto the titanium dioxide particles so that on mixing a colloidally stabilised aqueous dispersion of the polymer particles with a colloidally stabilised aqueous dispersion of titanium dioxide particles, the moieties adsorb onto the titanium dioxide to form a colloidally stable aqueous dispersion of polymer-modified titanium dioxide which is useful in coating compositions.

Claims21

Dependent claims

A polymer-modified or copolymer-modified particulate titanium dioxide (TiO.sub.2) comprising particles of organic polymer attached to particles containing titanium dioxide which titanium dioxide particles have a number average particle size (Dt) of from 100 to 400 nm (nanometer) and which polymer particles have a number average particle size, Dp wherein

a) the polymer particles are pre-formed prior to their attachment to the titanium dioxide particles and have a Dp such that when
(i) Dp>Dt, their Dp is ##EQU8## where ##EQU9## Vt=the volume of the TiO.sub.2 particles and Vp=the volume of the polymer particles or
(ii) Dp.ltoreq.Dt, the number ratio of polymer particles to titanium dioxide particles exceeds whichever is the greater of ##EQU10## b) the polymer particles are pre-formed either by (i) a free radical initiated aqueous emulsion or dispersion polymerization performed in the presence of a water-soluble compound which bonds chemically to the polymer as the polymer is being formed, or
(ii) a polymerization which is followed by the chemical bonding of a water-soluble compound to the polymer and
c) the water-soluble compound is a polymeric material having a weight average molecular weight of at least 1500 and which is chemically bondable to the polymer and which contains at least one moiety adsorbable onto the titanium dioxide particles.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/189,279Filed 31 Jan 1994 · continuation
Priority: GB 912729323 Dec 1991
Granted: 2 May 1995
Term ends: Not estimatedThe source records don’t support an estimate.

Classification19 codes

C08J 3/215
The polymer being premixed with a liquid phase: at least one additive being also premixed with a liquid phase
B82Y 30/00
Nanotechnology for materials or surface science
C09C 1/0084
Composite particulate pigments or fillers, i.e. containing at least two solid phases, except those consisting of coated particles of one compound:…
C09C 1/3676
Titanium dioxide: treatment with macro-molecular organic compounds