The invention relates to the field of PS/CTP (Computer to Plate) printing and particularly relates to protective glue for wear-resistant long-acting CTP and a preparation method of the protective glue. The protective glue is prepared from the following raw materials in parts by weight: 2-3 parts of Arabic gum, 1-3 parts of peach gum, 2-4 parts of polyvinyl alcohol, 1-2 parts of carboxymethyl chitosan, 0.2-0.5 part of organic bentonite, 10-15 parts of propylene glycol, 50-60 parts of deionized water, 0.01-0.02 part of nano diamond, 0.1-0.2 part of tween 80 and 1-2 parts of auxiliaries. The proactive glue provided by the invention is good in equalization. The organic bentonite can be used for improving the thixotropy and the thermal stability of sol, so that the coating performance is improved. The nano diamond powder has high heat conductivity and low frictional coefficient, so that a glue solution is dried in an accelerating manner, and thus the abrasion to the plate surface is reduced and the printing resistance of the plate surface is improved. The protective glue is free from toxicity, environmental friendly, convenient to prepare, easy to clean and time- and labor-saving when used.

Protective glue for wear-resistant long-acting CTP (Computer to Plate) and preparation method of protective glue

PURPOSE: To ensure that only a specified image part is erased without giving any adverse effect to an adjacent important image part by adding a 4 to 6C lactone and a specific compound to a correction fluid for a lithographic printing plate. CONSTITUTION: In the formula, R 1 is 1 to 4C alkyl group or phenyl group; R 2 is hydrogen atom or a 1 to 4C alkyl group, and n is an integer of 1 to 3. The correction fluid contains lactone and a chemical compound shown by the formula [I]. In addition, the fluid contains an organic solvent, an acid material, a water-soluble polymer compound, a surfactant, water, a coloring agent and/or a viscosity adjustment agent. The 4 to 6C lactone contains butylolactone, valerolactone and hexanolactone. On the other hand, the compound expressed by the formula [I] are propyleneglycolmonomethylether, tripropyleneglycolmonophenyl ether, etc. COPYRIGHT: (C)1992,JPO&Japio

Correction fluid for lithographic printing plate

PROBLEM TO BE SOLVED: To increase viscosity, and thereby solve problems such as the deterioration of wiping properties or gum removing properties by preparing a printing plate protecting agent used for protection of a printing plate for lithography with the addition of gum arabic and an organic reducing agent. SOLUTION: When manufacturing a printing plate protecting agent for a lithographic printing plate, rubber arabic and an organic reducing agent are added. In this case, the gelation of the printing plate protecting agent is prevented from occurring by using the rubber arabic with a moisture content of not more than 15%. Further, if the rubber arabic with a moisture content of 15% or more needs to be used, the gelation can be prevented from occurring by preparing the printing plate protecting agent at 60 deg.C or higher. Besides, it is preferable that as the organic reducing agent, a combination of 3- pyrazolidons and dihydroxybenzenes, a combination of aminophenols and dihydroxybenzenes or a combination of 3-pyrazolidons and ascorbic acid or a combination of aminophenols and ascorbic acid be used. This organic reducing agent is usually used at a dose of 0.001-1.4mol/l.

Protecting agent for printing plate of lithography and its manufacturing

PURPOSE:To allow good plate surface retouching and erasing of the photosensitive planographic printing plate contg. a quinonediazide compd. and a vinyl polymer resin contg. a phenolic hydroxyl group by using a retouching agent contg. specific cyclic amide. CONSTITUTION:The retouching agent contg. 4-6C latcone/4-7C cyclic amide is used. The 4-6C lactone includes butyrolactone, valerolactone, hexanolactone, alpha/beta-angelicalactone, etc. The 4-7C cyclid amide includes 2-pyrrolidone, N- methyl-2-pyrrolidone, N-ethyl-2-pyrrolidine, epsilon-caprolactam, N-methyl-epsilon- caprolactam, etc. The ratio at which the lactone and the cyclic amide occupy in the retouching liquid is adequately 2-80wt.%. The good plate surface retouching and erasing are enabled in this way.

Noguchi Kazuo

Papers

Protecting agent for printing plate of lithography and its manufacturing

Method of processing planographic printing plate