US3929488A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light sensitive diazo composition with azo dye formed from a diazonium salt and a novolak resin
Assignee: Howson Algraphy Ltd
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Filing: 1974-06-25
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Granted: 1975-12-30
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Expires: 1994-06-25
Abstract
Abstract A light-sensitive positive-working composition for printing plate manufacture comprises, in admixture, a diazonium salt of a strong acid, a novolak resin and an azo-dye which undergoes a colour change in the presence of the light decomposition products of the diazonium salt. The azo-dye is obtained by coupling together a diazonium salt and a novolak resin in alkaline conditions and may be formed in situ. Optionally, the material also includes an ortho-quinone diazide.
Inventors
- 👤 Peter John Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 08:10
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/004; G03F7/016
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
78 words
A LIGHT-SENSTIVE POSITIVE-WORKING COMPOSITION WHICH EXHIBITS A COLOUR CHANGE UPON EXPOSURE TO LIGHT AND WHICH IS SUITABLE FOR THE PRODUCTION OF A PRINTING PLATE BY A PHOTOMECHANICAL TECHNIQUE, WHICH COMPOSITION COMPRISES IN ADMIXTURE A DIAZONIUM SALT, A NOVOLAK RESIN, AND AN AZO-DYE WHICH UNDERGOES A COLOUR CHANGE IN THE PRESSURE OF THE LIGHT DECOMPOSITION PRODUCTS OF THE DIAZOMIUM SALT, SAID AZO-DYE BEING THE PRODUCT OBTAINED BY COUPLING TOGETHER A DIAZONIUM SALT AND A NOVOLAK RESIN IN AKALINE MEDIUM.
Claim 2
Dependent Claim
78 words
A LIGHT-SENSTIVE POSITIVE-WORKING COMPOSITION WHICH EXHIBITS A COLOUR CHANGE UPON EXPOSURE TO LIGHT AND WHICH IS SUITABLE FOR THE PRODUCTION OF A PRINTING PLATE BY A PHOTOMECHANICAL TECHNIQUE, WHICH COMPOSITION COMPRISES IN ADMIXTURE A DIAZONIUM SALT, A NOVOLAK RESIN, AND AN AZO-DYE WHICH UNDERGOES A COLOUR CHANGE IN THE PRESSURE OF THE LIGHT DECOMPOSITION PRODUCTS OF THE DIAZOMIUM SALT, SAID AZO-DYE BEING THE PRODUCT OBTAINED BY COUPLING TOGETHER A DIAZONIUM SALT AND A NOVOLAK RESIN IN AKALINE MEDIUM.
Claim 3
Dependent Claim
19 words
A light-sensitive composition as claimed in claim 1, wherein the diazonium salt in the mixture is a diphenylamine-4-diazonium salt.
Claim 4
Dependent Claim
18 words
A light-sensitive composition as claimed in claim 2, wherein the diazonium salt in the mixture is diphenylamine-4-diazonium fluoroborate.
Claim 5
Dependent Claim
25 words
A light-sensitive composition as claimed in claim 1, wherein the diazonium salt in the mixture is 2,4,5-triethoxy diphenyl diazonium oxalate or 4-diethylamino benzene diazonium fluoroborate.
Claim 6
Dependent Claim
28 words
A light-sensitive composition as claimed in claim 1, wherein the diazonium salt from which the azo dye is derived is a diphenylamine-4-diazonium salt, or a 2,5-diethoxy-4-(4''-tolyl)-mercaptobenzene diazonium salt.
Claim 7
Dependent Claim
16 words
A light-sensitive composition as claimed in claim 1, which further includes an ortho-naphthoquinone diazide sulphonyl ester.
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US3199981A
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US3674495A
Cited
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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) | 1978-12-29 | 1979-06-30 | 1979-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-29 | 1983-06-30 | 1983-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-29 | 1987-06-30 | 1987-12-30 | $7700.00 | Window Closed / Lapsed |