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Method of making laser imaged printing plates utilizing ultraviolet absorbing layer

  • US 5,925,500 A
  • Filed: 08/21/1997
  • Issued: 07/20/1999
  • Est. Priority Date: 06/25/1993
  • Status: Expired due to Term
First Claim
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1. A method of making a laser imaged printing plate, the steps comprising(a) providing a solid, uncured, photocurable printing plate consisting essentially of:

  • 1) a backing;

    2) at least one photocurable layer on said backing, said photocurable layer comprising a photopolymer which is unaffected by radiation at a selected wavelength in the range of 300-400 nm and an initiator activatable at the selected wavelength; and

    ;

    3) an ultra-violet radiation absorbing layer over said photocurable layer, said absorbing layer comprising a polymeric matrix that is transparent to ultraviolet radiation and a dopant which is soluble in said polymeric matrix and has a high extinction coefficient in the wavelength range of 300-400 nm, wherein said ultra-violet radiation absorbing layer is capable of being photoablated by a laser operating at a first energy level in the wavelength range of 300-400 nm, and wherein unablated areas of said absorbing layer are capable of absorbing at least 95% of irradiated light in the wavelength range of 300-400 nm from an ultra-violet light source operating at a second energy level lower than said first energy level;

    (b) photoablating said absorbing layer using a laser, thereby providing ablated and unablated areas forming an image;

    (c) flood exposing said laser imaged printing plate to UV light in the wavelength range of 300-400 nm, without a negative, thereby curing the photocurable layer in areas under ablated areas of said absorbing layer; and

    (d) developing said exposed, laser imaged plate.

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