Process for the preparation of pigmented polymer powders of controlled particle shape and size and size distribution and product

Claim 2

A process according to claim 1 in which the pigmented polymer is in solid bulk or particle form in the dispersing liquid and is heated above its melting point to form a mass that is sub-divided by agitation into particle form, and modifying and controlling the size of the particles in subsequent stages.

Claim 3

A process according to claim 1 in which the pigmented polymer is in solid particle form in the dispersing liquid and is heated with agitation to above its melting point without losing its particulate form and is further heated and agitated with or without sub-dividing to modify and control the size of the particles in subsequent stages.

Claim 4

A process according to claim 1 in which the average size is controlled within the range from about 1 to about 10 microns, and the GSD at less than 1.4.

Claim 5

A process according to claim 1 in which the average size is controlled within the range of about 10 to about 20 microns and the GSD is less than 1.35.

Claim 6

A process according to claim 1 in which particle size is controlled by heating the pigmented polymer in the inert liquid in at least one stage at a temperature within the range from about 100* to about 500*F. 8 A process according to claim 1 in which particle size is controlled by control of the degree of agitation in at least one stage within the range of from about 100 to about 5,000 linear feet per minute. 9 A process according to claim 1 in which particle size is controlled by control of the concentration of polymer in the dispersion within the range of from about 2.5 to 10 parts of dispersing liquid to one part of polymer. 10 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 of from about 0.1 to about 1 parts per part of polymer.

Claim 7

A process according to claim 1 in which particle size and size distribution are controlled by separation of the process into at least two stages at different dispersion temperatures, each at or above the melting temperature of the polymer.

Claim 8

A process according to claim 1 in which particle size is controlled in an initial heating stage so as to sub-divide the pigmented polymer to a small particle size by maintaining the dispersion temperature at at least from about 50*F. to about 250*F. above the melting temperature of the polymer, and then, in a subsequent heating stage, paRticle size is controlled so as to agglomerate and coalesce the particles, and increase their size and narrow their size distribution, while at the same time forming them into a regular shape and surface configuration, by maintaining the dispersion at a higher temperature of at least from about 75*F. to about 500*F. above the melting temperature of the polymer.

Claim 9

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

Claim 10

A process according to claim 13 in which the polymer is polyethylene.

Claim 11

A process according to claim 13 in which the polymer is a methacrylate-styrene copolymer.

Claim 12

A process according to claim 1 in which the polymer is an ethylene copolymer.

Claim 13

A process according to claim 1 in which the polymer is an ethylene-vinyl acetate copolymer.

Claim 14

A process according to claim 1 in which the surfactant is a nonionic polyoxyalkylene glycol surfactant.

Claim 15

A process according to claim 1 in which the surfactant is a polyoxyethylene oxypropylene glycol block copolymer surfactant.

Claim 16

A process according to claim 1 in which the pigment is a white metal oxide.

Claim 17

A process according to claim 1 in which the pigment is carbon black. 22 A process for preparing finely divided pigmented polymer powders, containing from about 0.001 to 1 part by weight of pigment, having controlled particle size and/or shape and/or size distribution, comprising agitating a molten pigmented polymer in from about 1 to about 40 parts per part of polymer of an inert dispersing liquid which is a nonsolvent for said polymer in the presence of from about 0.05 to 2 parts by weight per part of polymer of a nonionic surfactant at a first temperature from at least about 50*F. to about 250*F. above the melting temperature of the polymer for a time sufficient to form finely divided pigmented polymer particles dispersed in the liquid, and then in a second stage heating the dispersion with agitation at a second temperature above the melting temperature of the polymer but below the decomposition temperature of any component and different from the first temperature for a time sufficient to shape the particles, and control their average size to within the range of from about 1 to about 30 microns, and narrow their size distribution to less than 1.5 GSD, whereby about 68.3 percent of said particles are within a size range determined by the particle diameters of the mean size divided by the GSD value and the mean size multiplied by the GSD value, and then cooling the pigmented particles so as to solidify them and stabilize them in that shape, average size and size distribution.

Claim 18

A process according to claim 22 in which the size distribution is controlled within the average size range from about 1 to about 10 microns, at less than 1.4 GSD.

Claim 19

A process according to claim 22 in which the size distribution is controlled within the average size range of from about 10 to 20 microns at less than 1.35 GSD.

Claim 20

A process according to claim 22 in which the particles are brought to a spherical shape and surface configuration.

Claim 21

A process according to claim 22 in which particle size is controlled by heating the dispersion in a first stage at a temperature within the range from about 100* to about 175*F., and in a second stage at a temperature within the range from about 150* to about 250*F. 27 A process according to claim 22 in which particle size is controlled by control of the degree of agitation within the range of from about 100 to about 5000 linear feet per minute. 28 A process according to claim 22 in which particle size is controlled by control of the concentration of polymer in the dispersion within the range of from about 2.5 to 10 parts of dispersing liquid to 1 part of polymer. 29 A process according to claIm 22 in which particle size is controlled by control of the amount of surfactant in the dispersion within the range of from about 0.1 to about 1 parts per part of pigmented polymer.

Claim 22

A process according to claim 22 in which particle size is controlled in the second stage by maintaining the dispersion temperature at at least about 75*F. up to about 500*F. above the melting temperature of the polymer.