Polaroid Corporation

Yi-Hua Tsao

Rong-Chang Liang

Tung-Feng Yeh

John M Hardin

Joseph Hanlon

Yee-Ho Chia

Chieh-Min Cheng

Eugene L Langlais

The present invention provides a method for developing a lithographic plate on a printing press without the requirement of bath processing, the printing press equipped with means for delivering ink and aqueous fountain solutions to the plate, the preferred plate having in order (a) a substrate; and (b) a photoresist photohardenable upon imagewise exposure to actinic radiation, the photoresist comprising (i) a macromolecular organic binder; (ii) a photopolymerizable ethylenically unsaturated monomer having at least one terminal ethylenic group capable of forming a high polymer by chain-propagated polymerization, (iii) a polymerization initiator activatable by actinic radiation, and (iv) a disperse hydrophilic microgel. According to a product aspect, the present invention also provides a lithographic plate, configured as indicated, with the further combination therewith of an on-press removable polymeric overcoat.

On-press lithographic development methodology facilitated by the use of

The present invention is directed to a method for the on-press development and printing of images. The method generally comprises the steps of providing a lithographic printing plate precursor element comprising a lithographic hydrophilic printing plate substrate, a photohardenable photoresist, and a layer of polymeric protective overcoat; imagewise exposing the precursor element to actinic radiation through said photoresist and overcoat layer sufficiently to photoharden the photoresist in exposed regions and provide a latent image in said photoresist layer; placing the precursor element onto a lithographic printing press; and running the press, whereby printing fluid effects removal of the overcoat and development of said latent image. In particular modes of practices, the method utilizes an overcoat having incorporated therein a water or fountain soluble or dispersible crystalline compound. The overcoat can be used as an oxygen barrier and/or to provide a non-tacky surface on the printing plate. By the incorporation of the crystalline compound, on-press removability of the overcoat is facilitated.

On-press development of an overcoated lithographic plate

The present invention provides a quenching overcoat useful for application onto a lithographic printing plate, the overcoat having incorporated therein a water or fountain soluble or dispersible crystalline compound. The overcoat may be used as an oxygen barrier and/or to provide a non-tacky surface on the printing plate. By the incorporation of the crystalline compound, on-press removability of the overcoat is facilitated.

On-press removable quenching overcoat for lithographic plates

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Waltham, MA, United States of America

Yi-Hua Tsao