Chemistry of carbon compounds – Miscellaneous organic carbon compounds
Patent
1976-09-29
1978-09-26
Woodberry, Edward M.
Chemistry of carbon compounds
Miscellaneous organic carbon compounds
96 48R, 101463, 260 296WB, 260 296E, 260 296HN, 260 296M, C08L 128, B41M 300, B41N 300
Patent
active
041168968
ABSTRACT:
Precipitation at relatively high pH levels, e.g. above about 4 or more, in an acidic water/alcohol type fountain composition containing polyvalent metal cations and, as an active polymer component for rendering the non-image areas of a lithographic plate hydrophilic, a polyacrylamide-based polymer having a weight average molecular weight (M.sub.w) of from about 5,000 to about 1,000,000 and having from about 3 to about 70 percent of the carbonyl sites as carboxyl groups, or a blend of polyacrylamide and polyacrylic acid, or the like, is controlled by providing in the fountain composition an effective amount of an organic chelating agent for polyvalent metal cations which is substantially inert with respect to the active polymer component. The suitable chelating agents are further characterized in that at 25.degree. C, each (A) has a 1:1 stability constant with zinc of at least about 10.sup.7.5 ; (B) has a solubility of at least about 0.001 moles per liter in the water/alcohol solvent system over the pH range of from about 3 to about 7; and (C) when in a stable complexed form with polyvalent metal cation(s), has a solubility of at least about 0.001 moles per liter in the water/alcohol solvent system over the pH range of from about 3 to about 7. A preferred chelating agent is the pentasodium salt of diethylenetriaminepentaacetic acid.
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Offset Printing, Journ., No. 85, p. 17, Feb. 28, 1976.
American Newspaper Publishers Assoc., - "Research Bulletin, " 9/16/74.
Chem. Absts., 80:151208b, "Photosensitive Composition for Lithographic Plates," Sato et al.
Chem. Absts., 73:30677a, "Acrylamide Photosensitive Layers for Printing Plates," Adams et al.
Czerepinski Ralph G.
Friedrich Ralph E.
Garrett Walter L.
Halldorson Burke M.
Korfhage Glenn H.
The Dow Chemical Company
Woodberry Edward M.
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