Abstract: A retouching agent for lithographic printing plate containing an admixture of (a) a lactone having 4 to 6 carbon atoms and (b) a glycol ether or ketone.

Abstract: A light-sensitive lithographic printing plate comprising a support having on at least one surface thereof a light-sensitive layer, said light-sensitive layer exhibiting a higher oleophilicity (high affinity to grease) at the outermost surface thereof than in the balance of the light-sensitive layer. This light-sensitive lithographic printing plate is capable of beginning the printing operation with a relatively small number of spoilages and exhibits not only excellent press life but also high developability and excellent storage stability.

Abstract: A photosensitive lithographic printing plate comprising a support having thereon a photosensitive layer composed of a photosensitive diazo-oxide resin containing a hydroxystyrene unit and a hydroxystyrene unit having an o-quinoediazide group bonded through the oxygen of the hydroxystyrene. The photosensitive layer can contain an alkali-soluble resin. The photosensitive lithographic printing plate is stable mechanically, provides a large difference in solubility between the exposed areas and the unexposed areas of the layer, and has improved printability and sensitivity.

Abstract: A light-sensitive lithographic printing plate comprising a support with a hydrophilic surface having thereon a light-sensitive layer comprising a light-sensitive polyester containing o-quinonediazido groups as terminal groups.

Abstract: A presensitized lithoprinting plate which needs no fountain solution on printing comprising a support and a coating layer of a mixture of a photosensitive material and a silicone rubber.

Abstract: A dry presensitized planographic plate composed of a support having coated thereon one or two layers of (a) a silicone rubber, (b) a photosensitive azide compound, (c) a cyclized rubber, and (d) a copolymer of vinylidene chloride and acrylonitrile, the uppermost layer, when the planographic plate has two layers, containing at least the component (a) and (b) and the lower layer containing at least the component (c).

Abstract: A presensitized planographic printing plate which can be used in both negative and positive work comprising a support, a layer formed on the support of a photosensitive substance prepared by the reaction at a pH of not more than 7.5 of a diazonium compound with a coupling agent, e.g., hydroxybenzophenone, and a layer formed on the photosensitive layer of a "one-package" silicone rubber curable at room temperature. A planographic printing plate per se is produced by imagewise exposing the presensitized plate through a negative or positive film, and treating the exposed plate with a treating liquid capable of removing those portions of the presensitized plate which correspond to the image area of the original. Dampening water is not required when printing is carried out using the resulting printing plate.