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US3607271A Expired / Lapsed US ⏱️ 0.0 years remaining

Phloroglucinol developer for lingt-sensitive planographic plates

Assignee: Van der Grinten NV
•
Filing: 1969-01-09
•
Granted: 1971-09-21
•
Expires: 1989-01-09
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Abstract

Abstract Planographic printing plates sensitized with a benzene diazonium salt are converted into offset printing forms by imagewise exposure and subsequent development with an aqueous phloroglucinol solution buffered to a pH between 4 and 8 and containing 1-10 percent by volume of water-miscible organic solvent having a molecular weight greater than 50. The organic solvent avoids or greatly reduces a problem of initial prints being blemished by ink held on blank (background) areas of the printing forms. Especially effective solvents, such as propyl glycol, acetonyl acetone, diacetone alcohol, and Nmethylpyrrolidone-2, having boiling points above 90* C. A high salt content in the developing solution inhibits any bleeding of the azo-dyestuff during development.

Inventors

  • 👤 Aloysius Henricus Jac Hilhorst
  • 👤 Paul Joseph Hubert Tummers

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-26 23:29
CPC Classifications
G; G03; G03C; G03C5/00; G03C5/18; G03F; G03F7/00; G03F7/26; G03F7/30; G03F7/32

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 59 words
THE ORGANIC SOLVENT AVOIDS OR GREATLY REDUCES A PROBLEM OF INITIAL PRINTS BEING BLEMISHED BY INK HELD ON BLANK (BACKGROUND) AREAS OF THE PRINTING FORMS. ESPECIALLY EFFECTIVE SOLVENTS, SUCH AS PROPYL GLYCOL, ACETONYL ACETONE, DIACETONE ALCOHOL, AND N-METHYLPYRROLIDONE-2, HAVING BOILING POINTS ABOVE 90*C. A HIGH SALT CONTENT IN THE DEVELOPING SOLUTION INHIBITS ANY BLEEDING OF THE AZO-DYESTUFF DURING DEVELOPMENT.
Claim 2
Dependent Claim 19 words
A process according to claim 1, wherein said solvent is one also having a boiling point above 90* C.
Claim 3
Dependent Claim 22 words
A process according to claim 1, said solvent being selected from the group consisting of n-propylgylcol, acetonyl acetone, diacetone alcohol and N-methylpyrrolidone-2.
Claim 4
Dependent Claim 56 words
A process according to claim 1, further characterized in that said solution contains as buffering salt at least one alkaline-reacting salt of weak acid and in addition contains 1-10 percent by weight of at least one water-soluble inorganic salt of a strong acid, which salts do not react together to form a precipitate in said solution.
Claim 5
Dependent Claim 63 words
A composition for developing into an oleophilic azo-dyestuff image an imagewise exposed, light-sensitive planographic printing surface sensitized with a benzene diazoniUm compound, comprising an aqueous solution of phloroglucinol containing buffering salt giving the solution a pH between 4 and 8 and containing 1-10 percent by volume of water-miscible organic solvent selected from the group consisting of n-propylglycol, acetonyl acetone, diacetone alcohol and N-methylpyrrolidone-2.
Claim 6
Dependent Claim 51 words
A composition according to claim 5, said buffering salt comprising at least one alkaline-reacting salt of a weak acid, said solution also containing 1-10 percent by weight of at least one water-soluble inorganic salt of a strong acid, which salts do not react together to form a precipitate in said solution.

References Cited (Backward Citations)

US1821281A Cited
US1841653A Cited
US2113944A Cited
US2531004A Cited
US2702242A Cited
GB1082889A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1974-09-20 1975-03-22 1975-09-21 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1978-09-20 1979-03-22 1979-09-21 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1982-09-20 1983-03-22 1983-09-21 $7700.00 Window Closed / Lapsed

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