# US 2003/0111417 A1 · System and method for controling uniformity of colloidal silica particle size

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- Number: US 2003/0111417 A1
- Document ID: US20030111417A1
- Status: Published application
- Kind: A1
- Application number: 10/307,002
- Filed: 2002-11-30
- Published: 2003-06-19
- Earliest claimed: 2000-09-01
- Assignees: Chemical Products Corporation
- Inventors: Andrew Joseph Paszkowski
- Web page: https://patentgrep.com/patent/US20030111417A1

## CPC

- B01D 61/16: Feed pretreatment
- B01D 61/145: {Ultrafiltration}
- B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites
- C01B 33/18: Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof (preparation of aerogels by dehydrating gels C01B33/158; treatment to enhance the pigmenting or filling properties C09C)
- C01B 33/193: of aqueous solutions of silicates
- C09G 1/02: containing abrasives or grinding agents {(abrasives as such C09K3/14; polishing of semi-conductors H10P52/40)}
- B01D 2311/04: Specific process operations in the feed stream; Feed pretreatment
- C01P 2002/02: Amorphous compounds
- C01P 2004/04: obtained by TEM, STEM, STM or AFM
- C01P 2004/32: Spheres
- C01P 2004/62: Submicrometer sized, i.e. from 0.1-1 micrometer
- C01P 2004/64: Nanometer sized, i.e. from 1-100 nanometer
- C01P 2006/80: Compositional purity
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C09G: POLISHING COMPOSITIONS (French polish C09F11/00); SKI WAXES
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

A system and method are disclosed for producing uniform size silica particles by the steps of providing preformed colloidal silica particles having a surface area, adding an alkali metal silicate and a cation exchange resin to produce a quantity of feed silica at a feed rate which is less than a nucleation rate, and increasing the feed rate as the feed silica is added wherein the feed rate is less than the nucleation rate.

## Claims

### Claim 1

A method for producing silica particles comprising the steps of:
providing preformed colloidal silica particles having a surface area;
adding an alkali metal silicate and a cation exchange resin to produce a quantity of feed silica at a feed rate which is less than a nucleation rate, and
increasing said feed rate as said feed silica is added wherein said feed rate is less than said nucleation rate.

### Claim 2 (depends on 1)

The method of claim 1, further comprising the step of measuring the surface area of said preformed particles.

### Claim 3 (depends on 2)

The method of claim 2, wherein the step of measuring said surface area is completed using the Sears method or the Nitrogen Absorption method.

### Claim 4 (depends on 2)

The method of claim 2, further comprising the step of calculating a total silica surface area consisting of both said feed silica and said preformed colloidal silica.

### Claim 5 (depends on 4)

The method of claim 4, wherein said feed rate is 10 or less grams of silica per 1000 meters squared of said total silica surface area per hour.

### Claim 6 (depends on 5)

The method of claim 5, wherein said feed rate is 10 or less grams of silica per 1000 meters squared of said total silica surface area per hour at 90° C.

### Claim 7 (depends on 5)

The method of claim 5, wherein a computer is used to continuously recalculate said total surface area.

### Claim 8 (depends on 7)

The method of claim 7, wherein said computer continuously adjusts said feed rate.

### Claim 9 (depends on 1)

The method of claim 1, wherein said alkali metal silicate is selected from the group consisting of potassium silicate, lithium silicate, magnesium silicate, and calcium silicate.

### Claim 10 (depends on 1)

The method of claim 1, wherein said cation exchange resin is selected from the group consisting of carboxylic resins, sulfonated natural materials, and sulfonated styrene-dibenzene copolymers.

### Claim 11 (depends on 1)

The method of claim 1 further including the step of washing said silica particles using ultrafiltration to remove a portion of sodium therefrom.

### Claim 12

A silica sol comprising of,
silica particles having a particle size distribution with a coefficient of dispersion between 0.16 and 0.5 and a sodium content less than 10 ppm.

### Claim 13 (depends on 12)

The silica sol of claim 12 wherein said coefficient of dispersion is between 0.16 and 0.25.

### Claim 14 (depends on 12)

The silica sol of claim 12 wherein said silica particles have a sodium content less than 1 ppm.