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US4592977A Expired / Lapsed US ⏱️ 0.0 years remaining

Lithographic printing plate

Assignee: Toppan Inc
•
Filing: 1984-06-19
•
Granted: 1986-06-03
•
Expires: 2004-06-19
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Abstract

Abstract The present invention relates to a lithographic printing plate which can eliminate disadvantages of conventional zinc oxide master papers and has sensitivity sufficient for practical use in respect of long wavelength laser light. The invention contemplates to provide the lithographic printing plate which is fabricated by charging an electrophotographic plate involving a photoconductive layer on a conductive substrate, the photoconductive layer being prepared by dispersing a mixture containing 50 wt % or less of a phthalocyanine pigment/(zinc oxide and zinc sulfide) into a binder resin, exposing the electrophotographic plate to an image to form the electrostatic latent image, developing the exposed electrophotographic plate by the use of an ink receptive toner, and fixing the plate thus developed.

Inventors

  • 👤 Tsutomu Naganuma
  • 👤 Sigeru Hirayama
  • 👤 Hiroji Kumagai
  • 👤 Manabu Sawada
  • 👤 Tsuneo Tanaka
  • 👤 Isao Kumano

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-28 17:24
CPC Classifications
G; G03; G03G; G03G13/00; G03G13/26

Claims Analysis

Total Claims: 5
Claim 1
Independent Claim 125 words
A lithographic printing plate comprising an electrophotographic plate having a photoconductive layer on a conductive substrate, said photconductive layer being prepared by dispersing a mixture containing from about 20-45% by weight of a phthalocyanine pigment to the amount of photoconductive zinc oxide and zinc sulfide into a binder resin, said photoconductive zinc oxide being 20-60% by weight of a mixture of said phthalocyanine pigment, zinc oxide, zinc sulfide, and binder resin, said electrophotographic plate being charged, an electrostatic latent image formed when said charged electrophotographic plate is exposed to an image, the exposed electrophotographic plate being developed by the use of an ink receptive toner for developing said exposed electrophotographic plate, and the developed electrophotographic plate being fixed thereby to fabricate said lithographic printing plate.
Claim 2
Dependent Claim 125 words
A lithographic printing plate comprising an electrophotographic plate having a photoconductive layer on a conductive substrate, said photconductive layer being prepared by dispersing a mixture containing from about 20-45% by weight of a phthalocyanine pigment to the amount of photoconductive zinc oxide and zinc sulfide into a binder resin, said photoconductive zinc oxide being 20-60% by weight of a mixture of said phthalocyanine pigment, zinc oxide, zinc sulfide, and binder resin, said electrophotographic plate being charged, an electrostatic latent image formed when said charged electrophotographic plate is exposed to an image, the exposed electrophotographic plate being developed by the use of an ink receptive toner for developing said exposed electrophotographic plate, and the developed electrophotographic plate being fixed thereby to fabricate said lithographic printing plate.
Claim 3
Dependent Claim 36 words
A lithographic printing plate as claimed in claim 1 wherein said ratio of zinc oxide to mixture of said phthalocyanine pigment, zinc oxide, zinc sulfide, and binder resin is within a range of 35-50 wt %.
Claim 4
Dependent Claim 24 words
A lithographic printing plate as claimed in claim 1 or 2 wherein said zinc sulfide/zinc oxide are in a ratio of 10-50 wt %.
Claim 5
Dependent Claim 26 words
A lithographic printing plate as claimed in claim 1, 2 or 3 wherein said image exposure is conducted with semiconductor laser light modulated by electrical signal.

References Cited (Backward Citations)

CA639318A Cited
US3816118A Cited
DE2054118A1 Cited
US4076528A Cited
JPS5374430A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1989-06-02 1989-12-02 1990-06-03 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1993-06-02 1993-12-02 1994-06-03 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1997-06-02 1997-12-02 1998-06-03 $7700.00 Window Closed / Lapsed

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