Alkaline developing composition and method of use to process lithographic printing plates
AssigneeKodak Polychrome Graphics LLC
InventorsGary R. Miller, Melanie A. Felker
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Abstract
An alkaline developing composition for processing a lithographic printing plate includes an alkali metal silicate, at least 6 weight % of a thickener such as glycerine, and a nonionic fluorosurfactant or a phosphate ester hydrotrope. Lithographic printing plates that can be developed using this composition are either positive- or negative-working, and include both positive- and negative-working thermal plates.
Claims16
An aqueous alkaline developing composition that is useful in developing lithographic printing plates, said composition having a pH of at least 12 and comprising:
- a) an alkali metal silicate,
- b) at least 6 weight % of glycerine, and
- c) at least 0.0005 weight % of a nonionic fluorosurfactant, a phosphate ester hydrotrope, or a mixture thereof.
An aqueous alkaline developing composition that is useful in developing either a positive-working or negative-working thermal lithographic printing plate, said composition having a pH of from about 12 to about 14 and comprising:
- a) potassium silicate in an amount to provide from about 40 to about 65 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,
- b) from about 6 to about 18 weight % of glycerine, and
- c) from about 0.0005 to about 0.4 weight % of a nonionic fluorosurfactants having the formula ##STR3## wherein z is 4 to 20 and R.sub.f is ##STR4##
An aqueous alkaline developing composition that is useful in developing either positive-working or negative-working thermal lithographic printing plates, said composition having a pH of at from about 12 to about 14 and comprising:
- a) potassium silicate in an amount to provide from about 40 to about 65 g SiO.sub.2 to K.sub.2 O of from about 0.7 to about 1.0;
- b) from about 6 to about 18 weight % of glycerine;
- and
- c) from about 0.0005 to about 0.4 weight % of a nonionic fluorosurfactant.
Dependencies are inferred from the claim text.