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US4414196A
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Method of producing single crystalline, acicular α-ferric oxide
Assignee: Sakai Chemical Industry Co Ltd
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Filing: 1981-11-18
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Granted: 1983-11-08
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Expires: 2001-11-18
Abstract
Abstract A method of producing single crystalline, acicular α-ferric oxide particles of narrow particle size distribution is provided. The method comprises heating an aqueous suspension of ferric hydroxide at temperatures of 100°-250° C. at an alkaline pH in the presence both a water soluble organic or inorganic compound capable of forming complexes with iron as a growth regulating agent and α-ferric oxide seed crystals of minor axes not larger than 0.4 microns in average in amounts of 0.1-25 mole % in terms of the Fe content thereof in relation to the ferric hydroxide.
Inventors
- 👤 Seiji Matsumoto
- 👤 Tadashi Koga
- 👤 Kiyoshi Fukai
- 👤 Hideji Yamamoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:29
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; C; C01; C01G; C01G49/00; C01G49/02; C01G49/06; C30; C30B; C30B29/00; C30B29/10; C30B29/16; C30B29/60; C30B29/62; C30B7/00; C01P; C01P2004/00; C01P2004/10; C01P2004/51; C01P2004/60; C01P2004/62
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
173 words
A method of producing single crystalline, acicular α-ferric oxide of narrow particle size distribution which comprises: heating an aqueous suspension of amorphous ferric hydroxide at an elevated temperature from 100° C. to 250° C. at an alkaline pH in the presence of an effective amount of at least one growth regulating agent dissolved in the suspension and α-ferric oxide seed crystals of minor axes not more than 0.4 microns in average in amounts of 0.1-25 mole % in terms of Fe content in relation to the ferric hydroxide in the suspension, the growth regulating agent being selected from the group consising of an organic phosphonic acid, a hydroxycarboxylic acid, a polybasic acid, an aminocarboxylic acid, an aminosulfonic acid, an aromatic sulfonic acid, a thiocarboxylic acid, a water soluble salt of any one of the acids, a water soluble ester of any one of the acids, a polyamine, a thioalcohol, a polyhydric alcohol and a β-dicarbonyl compound, for a length of time sufficient to convert the amorphous ferric hydroxide into the acicular α-ferric oxide.
Claim 2
Independent Claim
173 words
A method of producing single crystalline, acicular α-ferric oxide of narrow particle size distribution which comprises: heating an aqueous suspension of amorphous ferric hydroxide at an elevated temperature from 100° C. to 250° C. at an alkaline pH in the presence of an effective amount of at least one growth regulating agent dissolved in the suspension and α-ferric oxide seed crystals of minor axes not more than 0.4 microns in average in amounts of 0.1-25 mole % in terms of Fe content in relation to the ferric hydroxide in the suspension, the growth regulating agent being selected from the group consising of an organic phosphonic acid, a hydroxycarboxylic acid, a polybasic acid, an aminocarboxylic acid, an aminosulfonic acid, an aromatic sulfonic acid, a thiocarboxylic acid, a water soluble salt of any one of the acids, a water soluble ester of any one of the acids, a polyamine, a thioalcohol, a polyhydric alcohol and a β-dicarbonyl compound, for a length of time sufficient to convert the amorphous ferric hydroxide into the acicular α-ferric oxide.
Claim 3
Dependent Claim
30 words
The method as claimed in claim 1 wherein the organic phosphonic acid has the formula: ##STR4## wherein n is an integer of 2-6, and m is an integer of 0-5.
Claim 4
Dependent Claim
39 words
The method as claimed in claim 1 wherein the organic phosphonic acid has the formula: ##STR5## wherein X and Y are hydrogen, hydroxy, amino or C 1 -C 6 alkyl or aryl, and q is an integer of 1-6.
Claim 5
Dependent Claim
26 words
The method as claimed in claim 1 wherein the organic phosphonic acid has the formula: ##STR6## wherein R is hydrogen or C 1 -C 5 alkyl.
Claim 6
Dependent Claim
41 words
The method as claimed in claim 1 wherein the hydroxycarboxylic acid is an aliphatic α-hydroxycarboxylic acid selected from the group consisting of citric acid, tartaric acid, glycolic acid, malic acid, dihydroxyglutaric acid, propyltartronic acid, agaritic acid, norcaperatic acid and desoxalic acid.
Claim 7
Dependent Claim
14 words
The method as claimed in claim 1 wherein the polybasic acid is propane-1,2,3-tricarboxylic acid.
Claim 8
Dependent Claim
13 words
The method as claimed in claim 1 wherein the aminocarboxylic acid is tyrosine.
Claim 9
Dependent Claim
12 words
The method as claimed in claim 1 wherein the polyamine is tris(2-aminoethyl)amine.
Claim 10
Dependent Claim
13 words
The method as claimed in claim 1 wherein the polyhydric alcohol is pentaerythritol.
Claim 11
Dependent Claim
15 words
The method as claimed in claim 1 wherein the aromatic sulfonic acid is sulfophenyliminodiacetic acid.
Claim 12
Dependent Claim
13 words
The method as claimed in claim 1 wherein the thioalcohol is mercaptoethyliminodiacetic acid.
Claim 13
Dependent Claim
13 words
The method as claimed in claim 1 wherein the aminosulfonic acid is taurine.
Claim 14
Dependent Claim
15 words
The method as claimed in claim 1 wherein the pH ranges from 8.0 to 12.5.
Claim 15
Dependent Claim
35 words
The method as claimed in claim 1 wherein the growth regulating agent is present in the suspension at a concentration of 1×10 -5 to 3 moles per mole of the ferric hydroxide in the suspension.
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) | 1986-11-07 | 1987-05-09 | 1987-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-11-07 | 1991-05-09 | 1991-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-11-07 | 1995-05-09 | 1995-11-08 | $7700.00 | Window Closed / Lapsed |