Uniform oxide microspheres and a process for their manufacture

Claim 2

A PROCESS FOR FORMING UNIFORM-SIZED INORGANIC MICROPARTICLES COMPRISING THE STEPS OF: A. FORMING A SOL OF UNIFORM-SIZED INORGANIC COLLOIDAL PARTICLES IN A POLAR LIQUID, SAID COLLOIDAL PARTICLES HAVING A HYDRXYLATED SURFACE AND BEING DISPERSIBLE IN SAID POLAR LIQUID, SAID COLLODAL PARTICLES BEING ISODIMENSIONAL OR ROD SHAPED PARTICLES WITH AT LEAST TWO DIMENSIONS IN THE RANGE OF 5 TO 500 MILLIMICRONS; RANGE OF 5 TO 1,000 MILLIMICRONS; B. FORMING A HOMOGENEOUS SOLUTION OF SAID SOL WITH A POLYMERIZED ORGANIC MATERIAL COMPRISING FORMALDEHYDE AND A SECOND ORGANIC MATERIAL SELECTED FROM THE GROUP CONSISTING OF UREA AND MELAMINE C. INITIATING POLYMERIZATION OF THE ORGANIC MATERIAL IN SAID SOLUTION TO CAUSE COACERVATION OF SAID ORGANIC MATERIAL AND SAID COLLOIDAL PARTICLES INTO SUBSTANTIALLY SPHERICAL MICROPARTICLES HAVING A DIAMETER OF ABOUT 0.5 TO ABOUT 20 MICRONS; D. SOLIDIFYING THE MICROPARTICLES SO FORMED; AND E. COLLECTING, WASHING AND DRYING SAID MICROPARTICLES.

Claim 3

A process for forming uniform-sized inorganic microspheres comprising the steps of: a. forming an aqueous sol containing uniform-sized colloidal inorganic particles which have hydroyxlated surfaces and which are dispersible in said aqueous sol, said colloidal particles being isodimensional or rod shaped particles with at least two dimensions in the range of 5 to 500 millimicrons and the third dimension in the range of 5 to 1,000 millimicrons; b. forming a homogeneous solution of said aqueous sol with a polymerizable material comprising formaldehyde and a second organic material selected from the group consisting of urea and melamine; c. initiating copolymerization of the organic materials in said solution to coacervation of said organic material and said colloidal particles into substantially spherical microspheres having a diameter of about 0.5 to about 20.0 microns; d. solidifying the microspheres so formed; and e. collecting, washing and drying said microspheres.

Claim 4

A process for forming uniform-sized inorganic microspheres comprising the steps of: a. forming an aqueous sol containing uniform-sized colloidal inorganic particles which have hydroyxlated surfaces and which are dispersible in said aqueous sol, said colloidal particles being isodimensional or rod shaped particles with at least two dimensions in the range of 5 to 500 millimicrons and the third dimension in the range of 5 to 1,000 millimicrons; b. forming a homogeneous solution of said aqueous sol with a polymerizable material comprising formaldehyde and a second organic material selected from the group consisting of urea and melamine; c. initiating copolymerization of the organic materials in said solution to coacervation of said organic material and said colloidal particles into substantially spherical microspheres having a diameter of about 0.5 to about 20.0 microns; d. solidifying the microspheres so formed; and e. collecting, washing and drying said microspheres.

Claim 5

The process of claim 2 wherein said inorganic colloidal particles are dispersible in an acidic medium, and wherein the step of initiating polymerization is accomplished by reducing the pH of the solution.

Claim 6

The process of claim 3 wherein said colloidal particles are colloidal silica particles.

Claim 7

The process of claim 3 wherein said inorganic colloidal particles are metallic oxide particles.

Claim 8

The process of claim 3 further comprising the step of subjecting said solution to a mixing action of sufficient intensity to prevent aggregation of the microspheres during their formation.

Claim 9

A process for forming uniform-sized porous inorganic microspheres having a diameter of about 0.5 to about 20.0 microns, said process comprising the steps of: a. forming an aqueous dispersion containing uniformsized refractory metallic oxide particles, said particles being isodimensional or rod shaped particles with at least two dimensions in the ranges of 5 to 500 millimicrons and the third dimension in the range of 5 to 1,000 millimicrons; b. forming a solution of said aqueous dispersion with a polymerizable organic material comprising formaldehyde and a second material selected from the group consisting of urea and melamine; c. reducing the pH of said solution to initiate copolymerization of said organic material and coacervation of said organic material and said colloidal particles into substantially spherical microparticles having a diameter of about 0.5 to about 20.0 microns; d. solidifying the microparticles so formed; and e. collecting, washing and drying said microparticles.

Claim 10

A process for forming uniform-sized porous inorganic microspheres having a diameter of about 0.5 to about 20.0 microns, said process comprising the steps of: a. forming an aqueous dispersion containing uniformsized refractory metallic oxide particles, said particles being isodimensional or rod shaped particles with at least two dimensions in the ranges of 5 to 500 millimicrons and the third dimension in the range of 5 to 1,000 millimicrons; b. forming a solution of said aqueous dispersion with a polymerizable organic material comprising formaldehyde and a second material selected from the group consisting of urea and melamine; c. reducing the pH of said solution to initiate copolymerization of said organic material and coacervation of said organic material and said colloidal particles into substantially spherical microparticles having a diameter of about 0.5 to about 20.0 microns; d. solidifying the microparticles so formed; and e. collecting, washing and drying said microparticles.

Claim 11

The process of claim 7 wherein said refractory metallic oxide particles are composed of material selected from the group consisting of silica, alumina, titania, zirconia, ferric oxide, tin oxide, antimony oxide, or combinations thereof.

Claim 12

A powder comprising uniform-sized microspheres having an average diameter oF about 0.5 to about 20 microns, substantially all of said microspheres having a diameter ranging from 0.5 to 1.5 times the average diameter of the microspheres in said powder, said microspheres consisting essentially of a plurality of uniform-sized inorganic colloidal ultimate particles having a hydroxylated surface in a matrix of a polymer selected from the group consisting of urea-formaldehyde and melamine formaldehyde, said colloidal ultimate particles being isodimensional or rod shaped particles, with at least two dimensions in the range of 5 to 500 millimicrons and one dimension in the range of 5 to 1,000 millimicrons, and said ultimate particles being linked together into a coherent three-dimensional network of interconnected particles.

Claim 13

A powder comprising uniform-sized microspheres having an average diameter oF about 0.5 to about 20 microns, substantially all of said microspheres having a diameter ranging from 0.5 to 1.5 times the average diameter of the microspheres in said powder, said microspheres consisting essentially of a plurality of uniform-sized inorganic colloidal ultimate particles having a hydroxylated surface in a matrix of a polymer selected from the group consisting of urea-formaldehyde and melamine formaldehyde, said colloidal ultimate particles being isodimensional or rod shaped particles, with at least two dimensions in the range of 5 to 500 millimicrons and one dimension in the range of 5 to 1,000 millimicrons, and said ultimate particles being linked together into a coherent three-dimensional network of interconnected particles.

Claim 14

A powder of uniform-sized microspheres having an average diameter of about 0.5 to about 20 microns, said microspheres being formed by a process comprising the steps of: a. forming a sol of uniform-sized inorganic colloidal particles in a polar liquid, said colloidal particles having a hydroxylated surface and being dispersible in said polar liquid, said colloidal particles being isodimensional or rod shaped particles with at least two dimensions in the range of 5 to 500 millimicrons and the third dimension in the range of 5 to 1,000 millimicrons; b. forming a homogeneous solution of said sol with a polymerizable organic material comprising formaldehyde and a second organic material selected from the group consisting of urea and melamine; c. initiating polymerization of the organic material in said solution to cause coacervation of said organic material and said colloidal particles into microspheres having a diameter of about 0.5 to about 20 microns; d. solidfying the microspheres so formed; and e. collecting washing and drying said microspheres.

Claim 15

A powder of uniform-sized microspheres having an average diameter of about 0.5 to about 20 microns, said microspheres being formed by a process comprising the steps of: a. forming a sol of uniform-sized inorganic colloidal particles in a polar liquid, said colloidal particles having a hydroxylated surface and being dispersible in said polar liquid, said colloidal particles being isodimensional or rod shaped particles with at least two dimensions in the range of 5 to 500 millimicrons and the third dimension in the range of 5 to 1,000 millimicrons; b. forming a homogeneous solution of said sol with a polymerizable organic material comprising formaldehyde and a second organic material selected from the group consisting of urea and melamine; c. initiating polymerization of the organic material in said solution to cause coacervation of said organic material and said colloidal particles into microspheres having a diameter of about 0.5 to about 20 microns; d. solidfying the microspheres so formed; and e. collecting washing and drying said microspheres.

Claim 16

A powder of uniform-sized microspheres having an average diameter of about 0.5 to about 20 microns, said microspheres being formed by a process comprising the steps of: a. forming an aqeuous sol containing uniform-sized colloidal inorganic particles which have hydroxylated surfaces and which are dispersible in said aqueous sol, said colloidal particles being isodimensional or rod shaped particles with at least two dimensions in the range of 5 to 500 millimicrons and the third dimension in the range of 5 to 1,000 millimicrons; b. forming a homogeneous solution of said aqueous sol with a polymerizable material comprising formaldehyde and a second organic material selected from the group consisting of urea and melamine; c. initiating copolymerization of the organic materials in said solution to coacervation of said organic material and said colloidal particles into microspheres having a diameter of about 0.5 to about 20.0 microns; d. solidifying the microspheres so formed; and e. collecting, washing and drying said microspheres.

Claim 17

A powder of uniform-sized microspheres having an average diameter of about 0.5 to about 20 microns, said microspheres being formed by a process comprising the steps of: a. forming an aqeuous sol containing uniform-sized colloidal inorganic particles which have hydroxylated surfaces and which are dispersible in said aqueous sol, said colloidal particles being isodimensional or rod shaped particles with at least two dimensions in the range of 5 to 500 millimicrons and the third dimension in the range of 5 to 1,000 millimicrons; b. forming a homogeneous solution of said aqueous sol with a polymerizable material comprising formaldehyde and a second organic material selected from the group consisting of urea and melamine; c. initiating copolymerization of the organic materials in said solution to coacervation of said organic material and said colloidal particles into microspheres having a diameter of about 0.5 to about 20.0 microns; d. solidifying the microspheres so formed; and e. collecting, washing and drying said microspheres.

Claim 18

The powder of claim 11 wherein said colloidal ultimate particles are composed of a material selected from the group consisting of silica, alumina, titania, zirconia, ferric oxide, tin oxide, zinc oxide or combinations thereof.

Claim 19

The powder of claim 11 wherein said colloidal particles are colloidal silica particles.

Claim 20

The powder of claim 11 wherein said microspheres have an average diameter of about 1.0 to about 10 microns.

Claim 21

The powder of claim 11 wherein said microspheres have a uniform density and a uniform pore distribution.

Claim 22

The powder of claim 11 wherein each of said microspheres has a diameter of from about 0.8 to about 1.2 times the average diameter of the microspheres in said powder.

Claim 23

The process of claim 2 wherein the second organic material is urea.

Claim 24

The process of claim 3 wherein said inorganic colloidal particles are composed of materials selected from the group consisting of silica, alumina, titania, zirconia, ferric oxide, tin oxide, antimony oxide or combinations thereof.

Claim 25

The powder of claim 9 wherein said colloidal ultimate particles are composed of a material selected from the group consisting of silica, alumina, titania, zirconia, ferric oxide, tin oxide, antimony oxide or combinations thereof.

Claim 26

The powder of claim 9 wherein said colloidal particles are colloidal silica particles.

Claim 27

The powder of claim 9 wherein said microspheres have an average diameter of about 1.0 to 10 microns.

Claim 28

The powder of claim 9 wherein each of said microspheres have a diameter of from about 0.8 to about 1.2 times the average diameter of the microspheres in said powder.