US3725035A
Expired / Lapsed
US
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Process for making gold powder
Assignee: EIDP Inc
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Filing: 1971-07-02
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Granted: 1973-04-03
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Expires: 1991-07-02
Abstract
Abstract A process for producing precipitated gold powder comprised of gold flakes, gold spheres or mixtures thereof by reducing a gold salt solution with selected reducing agents, in the presence of a protective colloid, at an elevated temperature. The process parameters provide a means for controlling the size and shape of the precipitated gold powder which has specific applications in the decorative and/or electronics industries (i.e., metallizing compositions).
Inventors
- 👤 O Short
- 👤 R Weaver
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 22:22
CPC Classifications
C; C01; C01G; C01G7/00; C01G7/003; B; B22; B22F; B22F9/00; B22F9/16; B22F9/18; B22F9/24; C22; C22B; C22B3/00; C22B3/20; C22B3/26; C22B3/262; C22B3/32; C22B3/322; C22B3/40; C22B3/402; C01P; C01P2004/00; C01P2004/20; C01P2004/30; C01P2004/32; C01P2004/60; C01P2004/61; C01P2004/62; H; H05; H05K; H05K1/00; H05K1/02; H05K1/09; H05K1/092; Y; Y02; Y02P; Y02P10/00; Y02P10/20; Y10; Y10S; Y10S75/00; Y10S75/953; Y10S75/954
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
14 words
A process in accordance with claim 1 wherein the protective colloid is gum arabic.
Claim 2
Dependent Claim
75 words
A process in accordance with claim 1 wherein the precipitated gold powder consists essentially of gold flakes, said flakes being approximately 1-50 microns across their widest surface, wherein the gold is precipitated from an acidic gold chloride solution with a reducing agent selected from the group consisting of oxalic acid, the alkali metal salts of oxalic acid, and mixtures thereof, in the presence of a protective colloid, at a temperature within the range of 50*-100*C.
Claim 3
Dependent Claim
14 words
A process in accordance with claim 3 wherein the protective colloid is gum arabic.
Claim 4
Dependent Claim
26 words
A process in accordance with claim 3 wherein the gold flakes are approximately 1-15 microns across their widest surface and the reducing agent is oxalic acid.
Claim 5
Dependent Claim
68 words
A process in accordance with claim 1 wherein the gold powder contains relatively spherical particles approximately 0.5-2 microns in diameter, wherein the gold is precipitated from an acid gold chloride solution with reducing agent selected from the group consisting of hydroquinone, and bromo, chloro, and lower alkyl substituted derivatives thereof, and mixtures thereof, in the presence of a protective colloid, at a temperature within the range of 50*-100*C.
Claim 6
Dependent Claim
14 words
A process in accordance with claim 6 wherein the protective colloid is gum arabic.
Claim 7
Dependent Claim
13 words
A process in accordance with claim 7 wherein the temperature is approximately 85*-100*C.
Claim 8
Dependent Claim
109 words
A process in accordance with claim 1 wherein the gold powder consists essentially of a mixture of gold flakes approximately 1-50 microns across their widest surface and relatively spherical gold particles approximately 0.5-2 microns in diameter, wherein the gold is precipitated from an acid chloride solution by reaction with reducing agents comprising (a) at least one membEr selected from the group consisting of oxalic acid and the alkali metal salts of oxalic acid, and (b) at least one member selected from the group consisting of hydroquinone, bromo, chloro, and lower alkyl substituted derivatives thereof, in the presence of a protective colloid, at a temperature within the range of 50*-100*C.
Claim 9
Dependent Claim
14 words
A process in accordance with claim 9 wherein the protective colloid is gum arabic.
Claim 10
Dependent Claim
13 words
A process in accordance with Claim 10 wherein the temperature is approximately 85*-100*C.
Claim 11
Dependent Claim
31 words
A process in accordance with Claim 10 wherein the gold flakes are approximately 1-15 microns across their widest surface and the reducing agent is a mixture of hydroquinone and oxalic acid.
Claim 12
Dependent Claim
24 words
A process in accordance with claim 12 wherein the ratio of oxalic acid to hydroquinone is approximately 10 to 1 on a weight basis.
Claim 13
Dependent Claim
20 words
A process in accordance with claim 9 wherein foaming and frothing are controlled by the presence of a defoaming agent.
Claim 14
Dependent Claim
14 words
A process in accordance with claim 14 wherein the defoaming agent is octyl alcohol.
Claim 15
Dependent Claim
110 words
A process in accordance with claim 1 wherein the gold powder consists essentially of relatively spherical gold particles approximately 0.5-2 microns in diameter, wherein the gold is precipitated from an acid gold chloride solution by reaction with reducing agents comprising (a) at least one member from the group consisting of oxalic acid and the alkali salts of oxalic acid, and (b) at least one member selected from the group consisting of hydroquinone, bromo, chloro, and lower alkyl substituted derivatives thereof, in the presence of a protective colloid, at a temperature within the range of 50*-100*C., said reaction being performed by slowly adding the gold chloride solution to the reducing agent.
Claim 16
Dependent Claim
26 words
A process in accordance with claim 16 wherein the gold chloride solution is added to the reducing agent at the rate of 1-500 cc. per minute.
Claim 17
Dependent Claim
20 words
A process in accordance with claim 17 wherein the gold chloride solution is added in increments over a 1-hour period.
Claim 18
Dependent Claim
15 words
A process in accordance with claim 17 wherein the gold chloride solution is added continuously.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-02 | 1976-10-02 | 1977-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-02 | 1980-10-02 | 1981-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-02 | 1984-10-02 | 1985-04-03 | $7700.00 | Window Closed / Lapsed |