A process for treating a lamella-type mineral in the form of particles constituted of stacks of sheets, in order to obtain a functional filler for a polymer material. The mineral is suspended in a liquid with a predetermined initial particle size, after which the suspension is subjected to a delamination procedure in order to separate the sheet from the particles, and obtain a particle size smaller than the initial particle size. The suspension is then subjected to selection in order to eliminate the particles larger in size than the predetermined size; it is subsequently dried, and the mineral particles are treated so as to restrict the creation amongst them of strong irreversible bonds. The talcum powder obtained can be incorporated into a thermoplastic material as a functional filler in order to increase the flexural modulus in proportions significantly higher than what is obtained with known fillers, without diminishing the shock resistance of the final material (with respect to the values obtained with said known fillers).
CROSS REFERENCE TO RELATED APPLICATION
This is the 35 USC 371 national stage of International application PCT/FR98/00569 filed on Mar. 20, 1998, which designated the United States of America.
The invention provides high surface area talc compositions by a novel hybrid milling method or soaking method. The hybrid milling method comprises dry milling talc powder followed by mixing with water and wet milling to provide a nano-talc slurry with high surface area, also of the invention. The soaking method comprises dry milling talc powder followed by mixing with water and soaking the powder for a period of time to provide high surface area nano-talc slurry, also of the invention. The slurry may be dewatered and dried to provide dry nano-talc powder. The nano-talc powder provided by the invention is a novel hydrophilic talc composition also of the invention.
