US 4,701,218 A · Compositions comprising inorganic particles

Abstract

Floccular compositions comprising ultrafine inorganic particles having maximum particle dimensions of from 0.5 to 3000 (preferably 2 to 1500) nm combined with a size-stabilizer which is a lyophobic substance with lyophilic activity on its surface and also comprising a polyelectrolyte flocculating agent attached to the combination. The size-stabilizer protects the ultrafine particles against agglomeration during formation of the flocculates and the mixing of flocculates into various materials such as plastics, inks, paint or refractory materials. Also a method for making the flocculates from colloidal dispersions of particles, size-stabilizers and flocculating agents. The flocculates are particularly useful with particles of metals of the coinage and transition groups for making transparent coloring agents. Also materials containing the ultrafine particles.

Claims24

Dependent claims

A dry, free-flowing floccular composition comprising

(a) ultrafine inorganic particles in which the maximum dimension of a major proportion of the particles is from 0.5 to 3000 nm,
(b) a particulate size-stabiliser in combination with the particles, the size-stabiliser comprising a lyophobic core and a lyophilic surface and wherein the size-stabiliser is sufficiently impermeable to said liquid dispersant to prevent a reduction of more than 5% in the volume of the size-stabilizer on removal of the size-stabilizer from a dispersion of the size-stabilizer in said liquid dispersant and a flocculating agent which comprises a polyelectrolyte attached to the combination of size-stabiliser and ultrafine particles, the lyophobic/lyophilic size-stabiliser (b) functioning to resist agglomeration of the ultrafine particles during formation of the composition and during its mixing into viscous molten plastic materials which would normally cause agglomeration and the flocculating agent (c) functioning by attachment to particles (a) or a combination of (a) and (b), to cause flocculation of said particles with said size-stabiliser.

A method for making a free-flowing floccular composition comprising ultrafine inorganic particles in which the maximum dimension of a major proportion of the particles is from 0.5 to 3000 nm wherein the method comprises steps of

(a) adding a colloidal dispersion of ultrafine particles to a dispersion of a particulate size-stabiliser in liquid dispersant whereupon the ultrafine particles and the said size-stabilizer is sufficiently impermeable to the liquid dispersant to prevent a reduction of more than 5% in the volume of the size-stabilizer substance on removal of the size-stabilizer from the liquid dispersant,
(b) either, before the addition of the colloidal dispersion of ultrafine particles to the dispersion of size-stabiliser, treating the size-stabiliser with a dispersion of a polyelectrolyte flocculating agent which on the addition of the colloidal dispersion flocculates with the size-stabiliser and ultrafine particles producing a floccular composition comprising flocculating agent and size-stabiliser in combination with ultrafine particles or, after the addition of the colloidal dispersion of ultrafine particles to the dispersion of size-stabiliser, treating the size-stabiliser with a dispersion of a polyelectrolyte flocculating agent which flocculates with the size-stabiliser and the ultrafine particles producing a floccular composition comprising flocculating agent and size-stabiliser in combination with ultrafine particles.

Dependencies are inferred from the claim text.

Compositions comprising inorganic particles

Life of this patent

Compositions comprising inorganic particles

Life of this patent

Abstract

Claims24