US4391897A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Diazo lithographic printing plate developing process
Assignee: Individual
•
Filing: 1981-06-17
•
Granted: 1983-07-05
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Expires: 2001-06-17
Abstract
Abstract Process for removing unexposed diazo from a silicated aluminum lithographic printing plate having a hydrophilic, anionic, negatively charged surface and a layer of a light sensitive, cationic diazo material which has been selectively exposed to actinic light in an image area. The plate is contacted after exposure with a solution of an anionic material in water. Anionic material from the solution ionically couples with unexposed diazo material and the solution still containing anionic material dissolves the coupled product from the unexposed areas producing a clean, hydrophilic background.
Inventors
- 👤 Robert F. Gracia
- 👤 Howard A. Fromson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 19:06
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/26; G03F7/30; G03F7/32
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
109 words
Process for removing unexposed diazo from a lithographic printing plate comprising a silicated aluminum substrate having a hydrophilic, anionic, negatively charged surface and on and bonded to the substrate, a light sensitive, cationic, positively charged, water-soluble diazo material which has been selectively exposed to actinic light in an image area which comprises contacting the plate after exposure with a solution consisting essentially of an anionic material in water in a quantity and for a time sufficient to couple the diazo with the anionic material and dissolve the coupled product from the non-image area thereby overcoming the bond between the diazo and the substrate leaving a clean, hydrophilic non-image area.
Claim 2
Dependent Claim
109 words
Process for removing unexposed diazo from a lithographic printing plate comprising a silicated aluminum substrate having a hydrophilic, anionic, negatively charged surface and on and bonded to the substrate, a light sensitive, cationic, positively charged, water-soluble diazo material which has been selectively exposed to actinic light in an image area which comprises contacting the plate after exposure with a solution consisting essentially of an anionic material in water in a quantity and for a time sufficient to couple the diazo with the anionic material and dissolve the coupled product from the non-image area thereby overcoming the bond between the diazo and the substrate leaving a clean, hydrophilic non-image area.
Claim 3
Dependent Claim
14 words
Process of claim 1 wherein the plate after exposure is immersed in said solution.
Claim 4
Dependent Claim
13 words
Process of claim 1 wherein the exposed surface is flooded with said solution.
Claim 5
Dependent Claim
17 words
Process of claim 1 wherein said solution is at a temperature of from 18° to 90° C.
Claim 6
Dependent Claim
37 words
Process of claim 1 wherein the anionic material is selected from the group of alkali metal salts of alkylaryl sulfonates, alkali metal salts of alkyl sulfonates and alkali metal and ammonium salts of sulfated higher fatty alcohols.
Claim 7
Dependent Claim
119 words
Process for removing unexposed diazo from a lithographic printing plate consisting essentially of providing a silicated aluminum substrate having a hydrophilic, anionic, negatively charged surface and on and bonded to the substrate, a light sensitive coating consisting essentially of a cationic, positively charge, water-soluble diazo material which has been selectively exposed to actinic light in an image area, contacting the plate after exposure with a solution consisting essentially of an anionic material in water in a quantity and for a time sufficient to couple the diazo with the anionic material and dissolve the coupled product from the non-image area thereby overcoming the bond between the diazo and the substrate leaving a clean, hydrophilic non-image area and rinsing with water.
Claim 8
Dependent Claim
119 words
Process for removing unexposed diazo from a lithographic printing plate consisting essentially of providing a silicated aluminum substrate having a hydrophilic, anionic, negatively charged surface and on and bonded to the substrate, a light sensitive coating consisting essentially of a cationic, positively charge, water-soluble diazo material which has been selectively exposed to actinic light in an image area, contacting the plate after exposure with a solution consisting essentially of an anionic material in water in a quantity and for a time sufficient to couple the diazo with the anionic material and dissolve the coupled product from the non-image area thereby overcoming the bond between the diazo and the substrate leaving a clean, hydrophilic non-image area and rinsing with water.
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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) | 1986-07-04 | 1987-01-03 | 1987-07-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-04 | 1991-01-03 | 1991-07-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-04 | 1995-01-03 | 1995-07-05 | $7700.00 | Window Closed / Lapsed |