US3954472A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Substractive developer for negative working lithographic plates
Assignee: S O Litho Corp
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Filing: 1974-08-26
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Granted: 1976-05-04
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Expires: 1994-08-26
Abstract
Abstract A subtractive developer for negative working lithographic plates comprising an aqueous solution of an alcohol, preferably n-propanol, a small quantity of ammonium sulfite, and polyvinylpyrolidone in the range of 0.05 - 0.12% by weight. The developer may also contain a small quantity of ammonium sulfate or ammonium chloride.
Inventors
- 👤 John E. Walls
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:00
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/26; G03F7/30; G03F7/32
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
60 words
A subtractive developer for negative working lithographic plates comprising a diazo resin photosensitive material on a substrate, said developer comprising an alcohol in the range of 10 - 90% by weight, ammonium sulfite in the range of 0.70 - 3.00% by weight, polyvinylpyrolidone in the range of 0.05 - 0.12% by weight, and distilled water for the balance by weight.
Claim 2
Dependent Claim
60 words
A subtractive developer for negative working lithographic plates comprising a diazo resin photosensitive material on a substrate, said developer comprising an alcohol in the range of 10 - 90% by weight, ammonium sulfite in the range of 0.70 - 3.00% by weight, polyvinylpyrolidone in the range of 0.05 - 0.12% by weight, and distilled water for the balance by weight.
Claim 3
Dependent Claim
11 words
The subtractive developer of claim 1 wherein said alcohol is n-propanol.
Claim 4
Dependent Claim
19 words
The subtractive developer of claim 2 wherein said n-propanol is in the range of 45 - 55% by weight.
Claim 5
Dependent Claim
19 words
The subtractive developer of claim 3 wherein said polyvinylpyrolidone is in the range of 0.05 - 0.10% by weight.
Claim 6
Dependent Claim
16 words
The subtractive developer of claim 4 further comprising about 0.5 % by weight of ammonium chloride.
Claim 7
Dependent Claim
19 words
The subtractive developer of claim 5 wherein the proportion of said ammonium sulfite is about 2.5 % by weight.
References Cited (Backward Citations)
US3669660A
Cited
US3738850A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-05-04 | 1979-11-03 | 1980-05-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-05-04 | 1983-11-03 | 1984-05-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-05-04 | 1987-11-03 | 1988-05-04 | $7700.00 | Window Closed / Lapsed |