US5364566A — Process for making electroconductive powders

Claim 1

Independent Claim 173 words

A method for making an electroconductive powder composition comprising an amorphous silica shell or an amorphous silica coated particle in association with a surface coating comprising a conducting network of antimony-containing tin oxide crystallites, said method comprises the steps of: (a) providing an aqueous suspension comprising a particulate substrate; (b) preparing separate aqueous solutions comprising hydrolyzable tetravalent tin and trivalent antimony salts, optionally adding at least one cation selected from Groups IA, IIA and IIIA; (c) combining the tin and antimony salt solutions, and adjusting the pH of the combined solution to about -0.5; (d) applying a coating layer comprising hydrous oxides of antimony and tin onto the substrate surface of said particulate substrate by adding the combined salt solution to the suspension; (e) recovering solids from step (d), optionally washing the recovered solids substantially free from water soluble species and drying; and (f) calcining the recovered solids thereby obtaining said powder composition, wherein the quantity of antimony in said powder composition is less than about 3 weight % based upon tin oxide.

Claim 2

Independent Claim 173 words

A method for making an electroconductive powder composition comprising an amorphous silica shell or an amorphous silica coated particle in association with a surface coating comprising a conducting network of antimony-containing tin oxide crystallites, said method comprises the steps of: (a) providing an aqueous suspension comprising a particulate substrate; (b) preparing separate aqueous solutions comprising hydrolyzable tetravalent tin and trivalent antimony salts, optionally adding at least one cation selected from Groups IA, IIA and IIIA; (c) combining the tin and antimony salt solutions, and adjusting the pH of the combined solution to about -0.5; (d) applying a coating layer comprising hydrous oxides of antimony and tin onto the substrate surface of said particulate substrate by adding the combined salt solution to the suspension; (e) recovering solids from step (d), optionally washing the recovered solids substantially free from water soluble species and drying; and (f) calcining the recovered solids thereby obtaining said powder composition, wherein the quantity of antimony in said powder composition is less than about 3 weight % based upon tin oxide.

Claim 3

Independent Claim 152 words

A method for making a substantially white electroconductive powder composition comprising at least one substrate particle in association with a surface coating comprising antimony-containing tin oxide crystallites, said method comprises the steps of: (a) providing an aqueous suspension comprising a particulate substrate, (b) preparing an aqueous solution comprising a source of antimony and tin, optionally adding at least one cation selected from Groups IA, IIA and IIIA; (c) adjusting the pH of said solution to be less than about -0.5, (d) applying a coating layer comprising hydrous oxides of antimony and tin onto the substrate surface of said particulate substrate by adding the solution to the suspension; (e) recovering solids from step (d), and; (f) heating the recovered solids at a temperature and for a time sufficient to form said powder composition, wherein the quantity of antimony in said powder composition is less than about 3 weight % based upon tin oxide.

Claim 4

Independent Claim 152 words

A method for making a substantially white electroconductive powder composition comprising at least one substrate particle in association with a surface coating comprising antimony-containing tin oxide crystallites, said method comprises the steps of: (a) providing an aqueous suspension comprising a particulate substrate, (b) preparing an aqueous solution comprising a source of antimony and tin, optionally adding at least one cation selected from Groups IA, IIA and IIIA; (c) adjusting the pH of said solution to be less than about -0.5, (d) applying a coating layer comprising hydrous oxides of antimony and tin onto the substrate surface of said particulate substrate by adding the solution to the suspension; (e) recovering solids from step (d), and; (f) heating the recovered solids at a temperature and for a time sufficient to form said powder composition, wherein the quantity of antimony in said powder composition is less than about 3 weight % based upon tin oxide.

Claim 5

Dependent Claim 52 words

The method of claim 1 or 2, wherein the substrate particles comprise at least one member selected from the group consisting of silica coated oxides of; titanium, magnesium, calcium, barium, strontium, zinc, tin, nickel and iron; mica, cordierite, enorthite and pyrophyllite; carbonates and sulfates of calcium, barium and strontium, and mixtures thereof.

Claim 6

Dependent Claim 152 words

The method of claim 1, wherein step (d) further comprises adding the combined solution of tin and antimony salts to a suspension comprising said substrate, wherein said substrates comprises particles having an amorphous silica surface; while maintaining the pH of the suspension in the range of about 1.5 to 3.5 and the temperature of the suspension in the range of from about 25° to 100° C. and maintaining the aqueous suspension at about 25° to 100° C. with continuous agitation over a period of about 30 to 60 minutes; and depositing a substantially uniform layer of antimony-containing tin oxide crystallites about 5 to about 20 nm thick; step (e) further comprises recovering the solids, washing the recovered solids substantially free from chloride ions, and drying the washed product, and; step (f) further comprises calcining the washed product at a temperature of about 550° to about 900° C., for at least one hour.

Claim 7

Dependent Claim 17 words

The method of claim 1 or 2, wherein the substrate particles comprise hollow shells of amorphous silica.

Claim 8

Dependent Claim 17 words

The method of claim 1 or 2, wherein the substrate particles comprise amorphous silica coated titanium dioxide.

Claim 9

Dependent Claim 16 words

The method of claim 1 or 2, wherein the substrate particles comprise amorphous silica coated mica.

Claim 10

Dependent Claim 32 words

The method of claim 1 or 2, wherein the powder composition comprises antimony-containing tin oxide crystallites in association with a substrate particle, and said powder has a reflectance greater than about 82%.

Claim 11

Dependent Claim 20 words

The method of claim 8, wherein the powder composition has a dry powder resistance of less than about 2,000 ohms.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1997-11-14	1998-05-16	1998-11-15	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2001-11-14	2002-05-16	2002-11-15	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2005-11-14	2006-05-16	2006-11-15	$7700.00	Window Closed / Lapsed

Process for making electroconductive powders

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