Process for the preparation of colored polymer powders of controlled charge and printing characteristics

Claim 2

0.001 to 1 parts by weight, per part of polymer, of a coloring agent selected from the group consisting of carbon black, phthalocyanine blue, pHthalocyanine green, cadmium sulfide, cadmium sulfide selenide, titanium dioxide, calcined iron oxide, chromic oxide and zinc oxide, and

Claim 3

0.00001 to 0.25 parts by weight, per part of polymer, of a charge-directing agent, which is a dye selected from the group consisting of azines, nigrosines, oxazines, thiazines, azos, diazos, cyanines, indigosols, anthraquinones, ketonimines, xanthines, indamines and indophenols; B. dispersing the blend in an inert dispersing liquid in the presence of 0.1 to 2 parts by weight, per part of blend, of a nonionic surfactant; C. subjecting the dispersion to agitation at a temperature above the melting temperature of the polymer, but below the decomposition temperatures of the various constituents, while forming the polymer in particle form with the coloring agent and charge-directing agent uniformly distributed in or on the particles; D. continuing the agitation for a time sufficient to shape the particles, and control their size at less than about 1,000 microns; and then E. cooling the colored particles so as to solidify them and stabilize them in that shape and size, and size distribution.

Claim 4

A process according to claim 2 in which the polymer is molten, and the polymer blend thus obtained is dispersed in the liquid while molten.

Claim 5

A process according to claim 1 in which the particles are brought to a regular shape and surface configuration and average size within the range from about 1 to about 1,000 microns, with an average particle diameter from about 3 to about 300 microns.

Claim 6

A process according to claim 1 in which particle size is controlled by heating the dispersion at a temperature within the range from about 230* to about 500* F.

Claim 7

A process according to claim 1 in which particle size is controlled by control of the degree of agitation within the range from about 400 to about 4,000 linear feet per minute.

Claim 8

A process according to claim 1 in which particle size is controlled by control of the amount of surfactant in the dispersion within the range from about 0.1 to about 2 parts per part of polymer/coloring agent.

Claim 9

A process according to claim 1 in which particle size is controlled by maintaining the dispersion temperature at at least from about 25* to about 60* F. above the melting point of the polymer blend.

Claim 10

A process according to claim 8 in which particle size is controlled so as to spherize the particles.

Claim 11

A process according to claim 1 in which the polymer is a thermoplastic synthetic resin.

Claim 12

A process according to claim 10 in which the polymer is polyethylene.

Claim 13

A process according to claim 10 in which the polymer is an ethylene-vinyl acetate copolymer.

Claim 14

A process according to claim 1 in which the charge-directing agent is a nigrosine dye.

Claim 15

A process according to claim 1 in which the charge-directing agent is a Nile Blue.

Claim 16

A process according to claim 1 in which the charge-directing agent is a Algosol Blue.

Claim 17

A process according to claim 1 in which the charge-directing agent is a Diamine Black.

Claim 18

A process according to claim 1 in which the coloring agent is carbon black.

Claim 19

A process according to claim 1 in which the coloring agent is present in an amount between 0.005 and 0.2 parts by weight, per part of polymer; the charge-directing agent is present in an amount between 0.0001 and 0.10 parts by weight, per part of polymer; and the surfactant is present in an amount between 0.2 and 1 parts by weight, per part of blend.