Fluidized granulation of pigments using organic granulating assistant
AssigneeCiba-Geigy Corporation
InventorsSimon G. Lawrence, James Hossack
Life of this patent
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Abstract
A process for producing a substantially dry, low dusting, free flowing granular pigment composition comprises (a) contacting a fluidized bed of pigment and a granulating assistant, (b) optionally contacting the granules so obtained with a surfactant and (c) removing the dry granules from the bed.
Claims18
An improved process for producing a substantially dry, low-dusting, free-flowing granular pigment product by treating a pigment in a fluidized bed with a granulating assistant wherein the improvement comprises the steps of
- (a) forming a fluidized bed consisting essentially of pigment powder by blowing a stream of gas through the pigment powder;
- (b) dispensing onto the fluidized bed of pigment a nonaqueous granulating assistant selected from the group consisting of:
- (i) a high boiling organic liquid;
- (ii) a mixture of a high boiling organic liquid and a resin;
- (iii) a mixture of a high boiling organic liquid and a wax;
- (iv) a mixture of a high boiling organic liquid, a resin and a wax;
- and
- (v) a molten wax;
- said assistant being one which:
- (.alpha.) wets out the pigment powder surface sufficiently to allow agglomeration of pigment particles so wetted out;
- (.beta.) binds the granules so formed sufficiently strongly to enable them to resist breakdown during the process of the invention, and during subsequent handling and storage, but without adversely affecting dispersibility of the pigment product in any final application medium into which the pigment is to be incorporated;
- and
- (.gamma.) is compatible with the final application medium;
- (c) contacting the granules formed in step (b) with a surfactant;
- and
- (d) removing the granular pigment so formed, which still contains the granulating assistant uniformly incorporated therein, from the fluidized bed.
An improved process for producing a substantially dry, low-dusting, free-flowing granular pigment product by treating a pigment in a fluidized bed with a granulating assistant wherein the improvement comprises the steps of
- (a) forming a fluidized bed consisting essentially of pigment powder by blowing a stream of gas through the pigment powder, wherein said pigment powder has low dusting properties;
- (b) dispensing onto the fluidized bed of pigment a nonaqueous granulating assistant selected from the group consisting of:
- (i) a high boiling organic liquid;
- (ii) a mixture of a high boiling organic liquid and a resin;
- (iii) a mixture of a high boiling organic liquid and a wax;
- (iv) a mixture of a high boiling organic liquid, a resin and a wax;
- and
- (v) a molten wax;
- said assistant being one which:
- (.alpha.) wets out the pigment powder surface sufficiently to allow agglomeration of pigment particles so wetted out;
- (.beta.) binds the granules so formed sufficiently strongly to enable them to resist breakdown during the process of the invention, and during subsequent handling and storage, but without adversely affecting dispersibility of the pigment product in any final application medium into which the pigment is to be incorporated;
- and
- (.gamma.) is compatible with the final application medium;
- and
- (c) removing the granular pigment so formed, which still contains the granulating assistant uniformly incorporated therein, from the fluidized bed.
Dependencies are inferred from the claim text.