Lithographic water based fountain solution concentrates
First Claim
1. In a method of lithographic or web-offset printing comprising the preparation of a fountain solution by mixing a water dilutable fountain solution concentrate in an amount of about 1.0 wt.% to 6.0 wt.% with water wherein said fountain solution concentrate contains water, a buffer, a polyol and surfactant, and treating a planographic plate with said fountain solution such that the non-image areas of said plate are rendered hydrophilic, thereby inhibiting the deposition of ink on said areas and improving the printing process, the improvement comprising, asthe buffer, at least one salt of (a) a polycarboxylic acid and (b) an organic amine, wherein the polycarboxylic acid has a pKa between about 3 and about 6, the organic amine has a pKb between about 2 and about 9, said fountain solution having a pH between about 4.7 and about 5.3, a surface tension between about 32×
- 10-3 Newton/m and about 52×
10-3 Newton/m and sufficient buffer effect such that the pH variation will be less than about one pH unit when 5 cc of the decinormal HCl is added to 100 cc of said fountain solution.
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Abstract
Lithographic fountain solution concentrates which are combined with water to form improved fountain solutions. The concentrates contain specific quantities of buffer salts resulting in improved printing process characteristics. The buffer salts are the salts of polycarboxylic acids and organic bases such as amines. The use of alcohol in the fountain solutions is eliminated or substantially reduced.
3 Citations
7 Claims
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1. In a method of lithographic or web-offset printing comprising the preparation of a fountain solution by mixing a water dilutable fountain solution concentrate in an amount of about 1.0 wt.% to 6.0 wt.% with water wherein said fountain solution concentrate contains water, a buffer, a polyol and surfactant, and treating a planographic plate with said fountain solution such that the non-image areas of said plate are rendered hydrophilic, thereby inhibiting the deposition of ink on said areas and improving the printing process, the improvement comprising, as
the buffer, at least one salt of (a) a polycarboxylic acid and (b) an organic amine, wherein the polycarboxylic acid has a pKa between about 3 and about 6, the organic amine has a pKb between about 2 and about 9, said fountain solution having a pH between about 4.7 and about 5.3, a surface tension between about 32× - 10-3 Newton/m and about 52×
10-3 Newton/m and sufficient buffer effect such that the pH variation will be less than about one pH unit when 5 cc of the decinormal HCl is added to 100 cc of said fountain solution. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- 10-3 Newton/m and about 52×
Specification