摘要:
A method for eliminating unwanted ink-receptive sections in positive working printing plates resulting from shading of the surface layer during exposure by the clamps holding the plate on the exposure apparatus following development of an imagewise exposed precursor. Accordingly the areas that are shaded are identified prior to development and the surface layer is scored in those areas to a depth and density sufficient to result in the scored layer being removed during development but not deep enough to damage the underlying hydrophilic layer.
摘要:
A method for eliminating unwanted ink-receptive sections in positive working printing plates resulting from shading of the surface layer during exposure by the clamps holding the plate on the exposure apparatus following development of an imagewise exposed precursor. Accordingly the areas that are shaded are identified prior to development and the surface layer is scored in those areas to a depth and density sufficient to result in the scored layer being removed during development but not deep enough to damage the underlying hydrophilic layer.
摘要:
Apparatus and method for exposing a lithographic printing plate wherein the apparatus includes a plurality of laser diodes emitting light of wavelength between 350 nm and 450 nm. The light from each of the laser diodes is directed onto the lithographic printing plate such that each spot on the lithographic printing plate receives light emitted from at least one of the laser diodes. Preferably, the lithographic printing plate is a violet-sensitive lithographic member and the lithographic member is a printing press plate. The power of each laser diode may be between 5 mW and 30 mW, and preferably the laser diodes emit light of wavelength between 390 nm and 430 nm.
摘要:
A thermally imageable element, useful as a lithographic printing plate precursor is disclosed. The element comprises a hydrophilic substrate; an underlayer comprising a first polymeric material; and an ink-receptive top layer comprising a second polymeric material. Preferably, the top layer comprises a compound that functions as a solubility-suppressing component. The solubility-suppressing component may be a separate dissolution inhibitor compound and/or the second polymeric material may also function as a solubility-suppressing component. On thermal exposure the exposed regions of the top layer becomes more readily soluble in an aqueous developer, allowing the developer to remove the top layer and reveal the surface of the hydrophilic substrate. The lithographic printing plate thus formed has excellent properties, including the absence of sludging of the developer.
摘要:
An imageable element comprises: (A) a substrate; and (B) an imageable composition applied to the substrate comprising: (1) a first layer, comprising: (a) a photosensitive composition capable of absorbing actinic radiation; and (b) a photothermal converter; and (2) an ablatable second layer contiguous to the first layer, wherein the second layer is opaque to the actinic radiation. This imageable element advantageously is useful in both positive and negative working printing plate applications, increases the efficiency of use of mask-generating radiation such as IR radiation and eliminates the need for chemicals and additional time to create a mask.
摘要:
A thermally imageable element, useful as a lithographic printing plate precursor is disclosed. The element comprises a hydrophilic substrate; an underlayer comprising a first polymeric material; and an ink-receptive top layer comprising a second polymeric material and a solubility-suppressing component. The solubility-suppressing component may be a separate dissolution inhibitor compound and/or the second polymeric material may also function as a solubility-suppressing component. On thermal exposure the exposed regions of the top layer becomes more readily soluble in an aqueous developer, allowing the developer to remove the top layer and reveal the surface of the hydrophilic substrate. The lithographic printing plate thus formed has excellent properties, including the absence of sludging of the developer.
摘要:
Imageable elements useful as lithographic printing members are disclosed. The elements contain a substrate, an underlayer, and a top layer. The underlayer contains a combination of polymeric materials that provides resistance both to fountain solution and to aggressive washes, such as a UV wash. The underlayer can be used in either thermally imageable or photochemically imageable elements.
摘要:
A positive working, multi-layer thermally imageable element is disclosed. The element comprises a substrate, an underlayer, and a top layer. The top layer comprises a crosslinked polymeric material. The element may be thermally imaged and developed to form a lithographic printing plate.
摘要:
A thermal lithographic printing plate, which can be imaged by thermal energy typically by imagewise exposure with an infrared emitting laser, a thermal printing head, etc., is made up of a hydrophilic substrate, and a composite layer structure composed of two layer coatings. Preferably, the first layer of the composite is composed of an aqueous developable polymer mixture containing a solubility inhibiting material and a photothermal conversion material which is contiguous to the hydrophilic substrate. The second layer of the composite is insoluble in the aqueous solution, is ink receptive, and is composed of one or more non-aqueous soluble polymers which are soluble or dispersible in a solvent which does not dissolve the first layer. The plate is exposed with an infrared laser or a thermal print head, and upon aqueous development of the imaged plate, the exposed portions are removed exposing hydrophilic substrate surfaces receptive to conventional aqueous fountain solutions. The unexposed portions contain the ink-receptive image areas. The second layer may also contain a photothermal conversion material. Alternatively, the composite layer may be free of photothermal conversion material when thermal imaging is carried out using a thermal printing head.
摘要:
The present invention relates to negative-working imageable elements that can be used for the manufacture of printing plates. These imageable elements can be developed on on-press by the action of a lithographic printing ink used in combination with either water or a fountain solution. The imageable elements comprise an imageable layer that is not removable in water or fountain solution alone. The imageable layer includes a free radically polymerizable compound, a free radical initiator composition, an infrared radiation absorbing compound, and a polymeric binder comprising poly(alkylene oxide) pendant groups, and preferably additionally pendant cyano groups.