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US 5,851,735 AGranted
Alkaline developing composition and method of use to process lithographic printing plates
AssigneeKodak Polychrome Graphics LLC
InventorsGary Roger Miller, Melanie Ann Felker
Life of this patent
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Abstract
An alkaline developing composition for processing a lithographic printing plate includes an alkali metal silicate and at least 6 weight % of a thickener such as glycerine. The lithographic printing plate can be either positive- or negative-working, and includes negative-working thermal plates.
Claims16
A method for processing comprising:
- developing an imagewise exposed positive-working or negative-working lithographic printing plate with an aqueous alkaline developing composition having a pH of at least about 12 and comprising:
- a) an alkali metal silicate, and
- b) at least 5 weight % of glycerine.
A method for providing an image comprising:
- developing an imagewise exposed negative-working thermal lithographic printing plate with an aqueous alkaline developing composition having a pH of from about 12 to about 14 and comprising:
- a) a potassium silicate in an amount to provide from about 40 to about 60 g SiO.sub.2 per 1000 g of composition, and a weight ratio of SiO.sub.2 to K.sub.2 O of from about 0.7 to about 1.0, and
- b) from 6 to about 18 weight % of glycerine.
Dependencies are inferred from the claim text.