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US4533736A
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Process for the prevention or reduction of discoloration of sodium pyrithione
Assignee: Arch Chemicals Inc
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Filing: 1984-07-02
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Granted: 1985-08-06
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Expires: 2004-07-02
Abstract
Abstract Disclosed is a process for producing a zinc pyrithione product having an acceptable white or off-white color and preventing or reducing discoloration of sodium pyrithione solutions by treating said sodium pyrithione solutions (which are precursors to zinc pyrithione) with an effective amount of a selected reducing agent to prevent or reduce the discoloration, said reducing agent selected from the class consisting of alkali metal sulfites, alkali metal bisulfites, hydrazine, and mixtures thereof.
Inventors
- 👤 Samuel I. Trotz
- 👤 Douglas A. Farmer, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 09:23
CPC Classifications
C; C07; C07F; C07F3/00; C07F3/06; C07D; C07D213/00; C07D213/02; C07D213/89
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
52 words
A process for preventing or reducing discoloration of aqueous sodium pyrithione solutions comprising treating a sodium pyrithione solution with an effective amount of a selected reducing agent to prevent or reduce the discoloration, said reducing agent selected from the class consisting of alkali metal sulfites, alkali metal bisulfites, hydrazine, and mixtures thereof.
Claim 2
Dependent Claim
52 words
A process for preventing or reducing discoloration of aqueous sodium pyrithione solutions comprising treating a sodium pyrithione solution with an effective amount of a selected reducing agent to prevent or reduce the discoloration, said reducing agent selected from the class consisting of alkali metal sulfites, alkali metal bisulfites, hydrazine, and mixtures thereof.
Claim 3
Dependent Claim
14 words
The process of claim 1 wherein said reducing agent is an alkali metal sulfite.
Claim 4
Dependent Claim
13 words
The process of claim 2 wherein said alkali metal sulfite is sodium sulfite.
Claim 5
Dependent Claim
14 words
The process of claim 1 wherein said reducing agent is an alkali metal bisulfite.
Claim 6
Dependent Claim
13 words
The process of claim 4 wherein said alkali metal bisulfite is sodium bisulfite.
Claim 7
Dependent Claim
18 words
The process of claim 1 wherein said sodium pyrithione is made by reacting 2-chloropyridine-N-oxide with NaSH and NaOH.
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) | 1988-08-05 | 1989-02-04 | 1989-08-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-08-05 | 1993-02-04 | 1993-08-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-08-05 | 1997-02-04 | 1997-08-06 | $7700.00 | Window Closed / Lapsed |