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US4530897A
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Process for desensitizing diazo lithographic printing forms using desensitizing solution with light absorbing compound
Assignee: Hoechst AG
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Filing: 1983-11-02
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Granted: 1985-07-23
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Expires: 2003-11-02
Abstract
Abstract The invention relates to a solution and a process for desensitizing lithographic printing forms based on light-hardened diazo compounds and which are ready for printing. The desensitizing solution of the invention is composed of a water-soluble, film-forming, high molecular weight organic compound, a compound which has a high light-absorption in the spectral region in which the photolysis of light-sensitive aromatic diazo compounds is initiated, and water as the solvent. The desensitizing solution protects the image stencil against the action of light and prevents any deterioration of the oleophilic character of the image stencil during storage.
Inventors
- 👤 Gunter Berghaeuser
- 👤 Loni Schell
- 👤 Werner Frass
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 05:27
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/26; G03F7/40; B; B41; B41N; B41N3/00; B41N3/08
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
145 words
A process for desensitizing lithographic printing forms based on light-hardened diazo compounds selected from the group consisting of diazonium salt condensation product and p-quinone diazides and which forms are ready for printing, said process comprising treating a lithographic printing form with an aqueous desensitizing solution and then drying the printing form, said aqueous solution comprising an admixture of about 4 to 40 percent, relative to the weight of said solution, of a water-soluble, film-forming, high molecular weight organic compound selected from the group consisting of gum arabic, dextrin, polyvinyl alcohol and a water-soluble acrylamide polymer, and about 0.1 to 10 percent, relative to the weight of said solution, of a compound having a high absorption of light in the spectral region of 300 to 450 nm and being selected from the group consisting of pyrazoline derivatives, 2-chloro-3-methyl-2-pyrone-6-(phenyl-4-sulfonic acid) or a salt thereof, and quinoline derivatives.
Claim 2
Dependent Claim
145 words
A process for desensitizing lithographic printing forms based on light-hardened diazo compounds selected from the group consisting of diazonium salt condensation product and p-quinone diazides and which forms are ready for printing, said process comprising treating a lithographic printing form with an aqueous desensitizing solution and then drying the printing form, said aqueous solution comprising an admixture of about 4 to 40 percent, relative to the weight of said solution, of a water-soluble, film-forming, high molecular weight organic compound selected from the group consisting of gum arabic, dextrin, polyvinyl alcohol and a water-soluble acrylamide polymer, and about 0.1 to 10 percent, relative to the weight of said solution, of a compound having a high absorption of light in the spectral region of 300 to 450 nm and being selected from the group consisting of pyrazoline derivatives, 2-chloro-3-methyl-2-pyrone-6-(phenyl-4-sulfonic acid) or a salt thereof, and quinoline derivatives.
Claim 3
Dependent Claim
12 words
A process according to claim 1 wherein the light-absorbing compound is water-soluble.
Claim 4
Dependent Claim
16 words
A process according to claim 1 in which the aqueous solution additionally comprises a hydrophilizing agent.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-07-22 | 1989-01-21 | 1989-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-07-22 | 1993-01-21 | 1993-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-07-22 | 1997-01-21 | 1997-07-23 | $7700.00 | Window Closed / Lapsed |