Method for developing positive acting light-sensitive planographic printing plate
First Claim
1. A development method which comprises imagewise exposing a positive acting light-sensitive planographic printing plate comprising an aluminum support and a light-sensitive layer of an o-quinonediazide compound formed thereon, and then developing the exposed plate with a developer comprising an aqueous solution of an alkali metal silicate, adding a supplementary solution comprising an aqueous solution of an alkali metal silicate to the developer to compensate for the degradation of the developer brought about by development and/or by carbon dioxide in the air;
- wherein said developer comprises an aqueous solution of an alkali metal salt having an [SiO2 ]/[M] ratio of from 0.5 to 0.75 and an SiO2 concentration of from 1 to 4% by weight based on the total weight of the developer, where [SiO2 ] represents the concentration of SiO2 per unit volume expressed as gram-molecules, and [M] represents the concentration of the alkali metal per unit volume expressed as gram-atoms, and said supplementary solution comprises an aqueous solution of an alkali metal silicate having an [SiO2 ]/[M] ratio of from 0.25 to 0.75.
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Abstract
A development method which comprises imagewise exposing a positive acting light-sensitive planographic printing plate comprising an aluminum support and a light-sensitive layer of an o-quinonediazide compound formed thereon, and then developing the exposed plate with a developer, comprising an aqueous solution of an alkali metal silicate, adding a supplementary solution comprising an aqueous solution of an alkali metal silicate to the developer to compensate for the degradation of the developer brought about by development and/or by carbon dioxide in the air; wherein the developer comprises an aqueous solution of an alkali metal salt having an [SiO2 ]/[M] ratio of from 0.5 to 0.75 and an SiO2 concentration of from 1 to 4% by weight based on the total weight of the developer, where [SiO2 ] represents the concentration of SiO2 per unit volume expressed as gram-molecules, and [M] represents the concentration of the alkali metal per unit volume expressed as gram-atoms, and the supplementary solution comprises an aqueous solution of an alkali metal silicate having an [SiO2 ]/[M] ratio of from 0.25 to 0.75.
45 Citations
38 Claims
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1. A development method which comprises imagewise exposing a positive acting light-sensitive planographic printing plate comprising an aluminum support and a light-sensitive layer of an o-quinonediazide compound formed thereon, and then developing the exposed plate with a developer comprising an aqueous solution of an alkali metal silicate, adding a supplementary solution comprising an aqueous solution of an alkali metal silicate to the developer to compensate for the degradation of the developer brought about by development and/or by carbon dioxide in the air;
- wherein said developer comprises an aqueous solution of an alkali metal salt having an [SiO2 ]/[M] ratio of from 0.5 to 0.75 and an SiO2 concentration of from 1 to 4% by weight based on the total weight of the developer, where [SiO2 ] represents the concentration of SiO2 per unit volume expressed as gram-molecules, and [M] represents the concentration of the alkali metal per unit volume expressed as gram-atoms, and said supplementary solution comprises an aqueous solution of an alkali metal silicate having an [SiO2 ]/[M] ratio of from 0.25 to 0.75.
- View Dependent Claims (2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 31, 33, 35, 36)
- 5. A development method which comprises imagewise exposing a number of positive acting light-sensitive planographic printing plates each consisting of an aluminum plate having an anodically oxidized surface and a light-sensitive layer of an o-quinonediazide compound formed thereon, and developing the exposed plates with a developer comprising an aqueous solution of an alkali metal silicate to remove the exposed areas of the light-sensitive layer, wherein development is performed while said developer is continuously compensated with a supplementary solution comprising an aqueous solution of an alkali metal silicate having an [SiO2 ]/[M] ratio of from 0.25 to 0.75 such that said developer has an [SiO2 ]/[M] ratio of from 0.5 to 0.75 and an SiO2 concentration of from 1 to 4% by weight, in which [SiO2 ] represents the concentration of SiO2 per unit volume expressed as gram-molecules, and [M] represents the concentration of alkali metal per unit volume expressed as gram-atoms, and wherein the content of potassium in the developer, in gram-atoms based on the total alkali metal content, is at least 20%.
Specification