Hoechst Aktiengesellschaft

Loni Schell

Werner Frass

Paul Stahlhofen

Inge Gros

Gunter Berghaeuser

A fountain solution and a fountain solution concentrate for use in offset printing are disclosed. The ready-to-use solution comprises 0.001 to 0.08% by weight of at least one alkanol or alkenol or of an alkanediol or alkenediol having 5 to 15 carbon atoms, which has been converted with ethylene oxide and/or propylene oxide into polyether structures having 3 to 12 ethylene oxide units and/or propylene oxide units.

Fountain solution for offset printing

A fountain composition for use in offset printing is disclosed comprising a viscosity-regulating hydrophilizing agent, a buffer substance at least one triazole and at least one non-hydroxylated dicarboxylic acid or salt thereof. By means of the invention, corrosion, in particular on the nickel-plated parts, above all the nickel-plated printing cylinders of printing machines, is considerably reduced, in particular viewed over a prolonged period.

Fountain composition for use in offset printing

A gumming solution is disclosed for use in the burning-in of irradiated and developed offset-printing plates. The gumming solution contains (a) water, (b) at least one hydrophilic polymer, and (c) at least one component derived from an organic acid. Component (b) comprises, for example, N-polyvinyl-pyrrolidone-(2) or polyacrylic acid, and component (c) comprises a water-soluble organic carboxylic acid, sulfonic acid, or phosphonic acid which has at least two acid functions and which is selected from the group consisting of benzene carboxylic acids, benzene sulfonic acids, benzene phosphonic acids, and alkane phosphonic acids, or one of the salts thereof (for example, disodium-benzene-1,3-disulfonate, mellitic acid, or methane-diphosphonic acid.) A process for the production of an offset-printing plate, using the aforesaid gumming solution in the burning-in of the plate, is also disclosed. With application of this gumming solution, washing of the printing plate prior to printing is rendered unnecessary, since the printing plate runs clean very rapidly during the printing process.

Gumming solution for use in the burning-in of offset-printing plates

An emulsion for post-treating planographic printing plates prepared by electrographic means can be used to improve the print quality of treated plates. The emulsion comprises (i) about 25% to 60% by weight of an aqueous phase comprising a phosphonic acid compound and a water-soluble hydrophilizing polymer and (ii) about 40% to 75% by weight of an organic solvent phase comprising a hydrocarbon mixture containing at least 20% by weight of aromatic components. A process for the production of planographic printing plates that employs this emulsion is simplified and less costly than conventional processes, and entails fewer environmental hazards.

Emulsion for post-treating planographic printing plates prepared by

Disclosed is a developer composition for exposed, light-sensitive, negative-working reproduction layers, which may contain an organic binder, comprising water and a salt of a substituted aromatic carboxylic acid, in particular, from about 5 to 60% by weight of at least one salt of an aromatic carboxylic acid having substituents which are immediately adjacent to the carboxyl group and represent an amino group, a hydroxyl group, and/or chlorine or bromine. Also disclosed is a process for developing the reproduction layers utilizing the disclosed developers, wherein the reproduction layer contains, in particular, a polymeric organic binder with an acetal, anhydride, amide and/or a carboxyl group.

Process for developing exposed diazo negative-working reproduction

The invention relates to a solution and a process for desensitizing lithographic printing forms based on light-hardened diazo compounds and which are ready for printing. The desensitizing solution of the invention is composed of a water-soluble, film-forming, high molecular weight organic compound, a compound which has a high light-absorption in the spectral region in which the photolysis of light-sensitive aromatic diazo compounds is initiated, and water as the solvent. The desensitizing solution protects the image stencil against the action of light and prevents any deterioration of the oleophilic character of the image stencil during storage.

Process for desensitizing diazo lithographic printing forms using

This invention relates to a developer solution for the development of exposed light-sensitive reproduction layers comprising a water-insoluble binder and a water-insoluble diazonium salt polycondensation product. As the essential constituents, this developer solution contains glycol ethers, glycol esters and water, in detail--about 30 to 80% of a compound of the formula ##STR1## wherein n=1 to 4 and m=1 to 5; about 3 to 30% of a compound of the formula ##STR2## wherein R.sup.1 and R.sup.2 are acyl groups containing 1 to 4 carbon atoms, or one of the two groups is a hydrogen atom and R.sup.3 is a hydrogen atom or a methyl group; about 0 to 15% of 1,3-dioxolane-2-one or 4-methyl-1,3-dioxolane-2-one; about 0 to 20% of a polyhydric alcohol; about 0 to 10% of an organic or inorganic salt which is soluble in the solvent mixture; and about 5 to 45% of water. The invention relates further to a process for the development of negative-working reproduction layers based on (a) water-insoluble diazonium salt polycondensation products and (b) binders which are insoluble in water and in dilute aqueous alkaline solutions. In the process, the exposed reproduction layer is treated with the above-specified developer solution in order to dissolve the unexposed layer areas.

Developer solution for the development of exposed negative-working

Disclosed is a process for manufacturing a lithographic printing form by electrophotographic means, comprising the steps of uniformly charging an oleophilic photoconductive layer which is present on an electrically conductive hydrophilic layer support and which contains a photoconductor and a binder; image-wise exposing the charged photoconductive layer to produce a charge image; developing the charge image with toner to produce a toner image comprised of imaged areas and non-image areas; fixing the toner image; decoating the non-image areas of the photoconductive layer to bare the electrically conductive layer support; coating the bared areas of the layer support with a solution comprising a water-soluble, but hydrocarbon-insoluble film-forming polymer and a vinyl phosphonic acid compound; drying the coating solution to form a uniform coating; and removing the toner image by rinsing with a hydrocarbon composition containing aromatic portions in an amount of at least about 20% by weight. Also disclosed is an improved printing form made by this process.

Process for the manufacture of a lithographic printing form by

This invention relates to an improved process for preserving a planographic printing form which is ready for printing. In the process, the planographic printing form is treated with an aqueous solution of a water-soluble, film-forming high-molecular weight organic compound and a hydrophilizing acid and is then dried. The hydrophilizing acid used is an organic phosphonic acid, in particular polyvinyl phosphonic acid, preferably in a concentration from 0.05 to 10 percent by weight. As the water-soluble, high-molecular weight organic compound gum arabic, dextrin or polyvinyl alcohol is appropriately used.

Process for preserving planographic printing forms

A process for the preparation of planographic printing forms is described, in which a light-sensitive material composed of a support having a hydrophilic surface and of a light-sensitive layer, which contains a 1,2-naphthoquinone-diazide, is exposed imagewise, developed and then heated to a temperature above 180.degree. C. for such a time and at such a temperature level that an oleophilic precipitate is formed on the hydrophilic image background, and the precipitate is then removed by treatment, for example wiping over, with an aqueous solution of about 0.01 to 50% by weight of polyvinyl phosphonic acid. The treatment has the advantage that in this case the support surface, for example anodically produced aluminum oxide, is not significantly attacked and is nevertheless completely freed from impurities.

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Hofheim-Wallau, Germany

Loni Schell