摘要:
A dampening water composition for lithographic printing which comprises 0.1 to 5% by weight of at least one member selected from the group consisting of monoalcohols or diols of alkanes or alkenes having 5 to 11 carbon atoms, to which 1 to 10 moles of ethylene oxide and/or propylene oxide are added. The dampening water composition is not toxic, has not a possiblity of causing a fire and pollution of working atmosphere and, therefore, the use of a local exhaust installation is not necessary. Moreover, it is excellent in characteristics as dampening water such that it does not cause contamination of metering roll, has good bleeding properties, emulsifying properties and stability in continuous processing as well as low foaming properties. Thus, the composition makes printing operation quite stable.
摘要:
Disclosed is a dampening solution composition for lithographic printing. The solution has a dynamic surface tension ranging from 20 to 50 dyne/cm at 15.degree. C. at most 1.times.10.sup.-1 seconds after a new surface of the solution is formed on the surface of a printing plate; a viscosity ranging from 1.05 to 5.0 cSt at 15.degree. C.; and an emulsification ratio when mixed with ink which is higher by 2 to 30% than that of pure water mixed with ink.
摘要:
A dampening water composition for lithographic printing plate comprises a hydrophilic polymer having a film-forming ability, a pH-buffering substance and at least one compound selected from the group consisting of benzimidazole and derivatives thereof. The dampening water composition can effectively suppress the corrosion of copper or copper alloy-plated rolls of a printing press as well as cast iron or nickel-plated cast iron parts thereof without impairing printing effects and printability.
摘要:
The present invention relates to a concentrated dampening water for a lithographic printing plate characterized by comprising:(a) 0.5 to 50% by weight of, as a nonionic surfactant, at least one compound selected from the group consisting of ethylene oxide and/or propylene oxide adduct of 2-ethyl-1,3-hexanediol and ethylene oxide and/or propylene oxide adduct of acetylene alcohol or acetylene glycol,(b) 1 to 30% by weight of 4-hydroxy-4-methyl-2-pentanone and/or a compound of the following formula [I], [III] or [III]: ##STR1## wherein R represents a methyl group, an ethyl group, a propyl group or a butyl group, and(c) 30 to 75% by weight of water.According to the present invention, an excellent concentrated dampening water is obtained, which has substantially no toxicity: does not pollute the working environment and causes no fire; necessitates no local exhaust device; and is excellent from the viewpoints of fouling of the metering roll, bleeding, emulsifiability, stability for continuous operation and anti-foaming property. Thus, with the concentrated dampening water of the present invention, the stable printing is possible.
摘要:
A method for manufacturing lithographic printing plates which comprises developing a presensitized plate for use in making lithographic printing plates imagewise opposed to light with an alkaline developer utilizing an automatic developing machine and then treating the developed presensitized plate with a finisher, wherein an initial pH of the finisher ranges from 2 to 8 and a pH of the finisher is controlled during running in proportion to concentration of the developer included in the finisher. The method makes it possible to prevent the formation of gel-like insoluble matters in the bath for treatment with the finisher due to the presence of the developer carried over from a developing bath and to stably process a large amount of lithographic printing plates over a long time period.
摘要:
A photo-sensitive printing plate processing apparatus for processing a photo-sensitive printing plate upon which an image has been exposed is provided wherein, adjacent to a main developing tank where the photo-sensitive printing plate is conveyed, immersed in developing solution and developed, on either the upstream or downstream side with respect to the direction of conveyance of the photo-sensitive printing plate, an auxiliary developing tank is provided for applying developing solution to the photo-sensitive printing plate and performing auxiliary developing thereof and therefore allowing definite developing of the photo-sensitive printing plate to be achieved.
摘要:
An emulsion type desensitizing gum comprises at least one polybasic acid monoester derivative of polysaccharide. The desensitizing gum exhibits high shelf stability and the lithographic printing plate to which the desensitizing gum has been applied hardly causes the background contamination of printed matters and is excellent in both the ink receptivity of the image areas and the desensitizing ability of the non-image areas.
摘要:
A concentrated dampening water composition for lithographic printing comprises a) 0.1 to 10% by weight of a hydrophilic polymeric compound having a film-forming ability; b) 0.01 to 15%, by weight of a pH buffering agent; c) 5 to 80% by weight of a water-miscible organic solvent having a boiling point of not less than 140.degree. C. and whose 1% by weight aqueous solution has a surface tension of not more than 60 dynes/cm; d), 0.05 to 10% by weight of a compound, for instance, represented by the following general formula (III); and e) 30 to 80% by weight of water:R.sup.8 --Z.sup.1 (R.sup.9)(R.sup.10)--R.sup.7.X.sup.1 (III)wherein R.sup.7 to R.sup.10 each represents a C.sub.1-12 alkyl, cyclic alkyl, hydroxyalkyl, benzyl or substituted or unsubstituted phenyl group; Z.sup.1 represents N, P or B; X.sup.1 represents an anion or cation selected from the group consisting of halogen, nitrate, sulfate, phosphate, hydroxyl, PF.sub.6.sup.-, BF.sub.4.sup.-, Li.sup.+, Na.sup.+, K.sup.+ and NH.sub.4.sup.+. The composition shows good printing properties and does not impair image areas of printing plates although it comprises a high boiling point solvent. Further, it provides dampening water having excellent stability with time, satisfies the requirements stipulated in the Japanese Fire Services Act as well as Industrial Safety and Health Law and thus can steadily provide good copies.
摘要:
A method for supplementing a replenisher for developer which comprises developing a large number of PS plates imagewise exposed to light with a developer composed of an aqueous solution containing electrolytes in an automatic developing machine, characterized by determining an AC impedance of the developer contained in the automatic developing machine, obtaining a correction impedance from the measured impedance value and rate of replacement and supplementing a desired amount of the replenisher to the developer when the correction impedance reaches a predetermined value. This method makes it possible to maintain a desired activity of the developer even when a large number of PS plates are processed and to relax the restriction on the incorporation of optional devices such as an autofeeder into the automatic developing machine.
摘要:
An electrophotographic lithographic printing plate is described, comprising an electrically conductive support and a photoconductive layer on the support, said layer being made mainly of a photoconductive zinc oxide and a resin binder, wherein in the surface of the photoconductive layer, the degree of exposure of photoconductive zinc oxide is from 10% to 70%.