Abstract:
A lithographic printing plate precursor comprises an imagable layer comprising a free radically polymerizable component, an initiator composition capable of generating free radicals upon exposure to imaging infrared radiation, an infrared radiation absorbing dye comprising an infrared radiation absorbing cation and a counter anion, and a polymeric binder. The salt formed between the infrared radiation absorbing cation and a tetraphenyl borate has solubility in 2-methoxy propanol at 20° C. that is greater than or equal to 3.5 g/l. The use of these infrared radiation absorbing dyes in the imagable layers provides a reduced tendency of these dyes to crystallize in the presence of tetraaryl borate counter anions.
Abstract:
Imageable elements can be imaged and then processed using a solution containing core-shell particles that are designed to complex with non-coalesced particles in the non-exposed regions of imaged element. A separate development step is not needed, but the non-coalesced particles and complexed core-shell particles can be removed from the resulting printing plate before using the resulting lithographic printing plate for printing.
Abstract:
Lithographic printing plates are prepared by imaging and developing negative-working lithographic printing plate precursors that include certain particulate polymeric binders in the photosensitive imageable layer. Such particulate polymeric binders are poly(urethane-acrylic) hybrids. Development is carried out using a working strength developer that includes one or more organic solvents in a total amount of at least 7 weight % and an anionic surfactant in an amount of at least 5 weight %.
Abstract:
Negative-working imageable elements have a hydrophilic substrate and a single thermally-sensitive imageable layer. This layer can include an infrared radiation absorbing compound and polymeric particles that coalesce upon thermal imaging. These coalesceable polymeric particles comprise a thermoplastic polymer and a colorant to provide improved visible contrast between exposed and non-exposed regions in the imaged element, such as lithographic printing plates.
Abstract:
The present invention provides a positive-working, thermally imageable element generally comprising a multi-layered imageable coating. The invention provides an imageable element comprising a substrate, an ink-receptive top layer, and an underlayer, the underlayer including a specific copolymer described herein. The copolymer can be a polymer comprising constitutional units derived from: a) a monomer having a cyclic urea group; b) a monomer comprising an N-substituted maleimide; c) a (meth)acrylamide or (meth)acrylate monomer; and d) a (meth)acrylic acid or vinyl benzoic acid monomer. In another embodiment, the copolymer can be a polymer comprising constitutional units derived from: a) a monomer having a cyclic urea group; b) a (meth)acrylic acid or vinyl benzoic acid monomer; c) and a (meth)acrylonitrile monomer. The imageable element may be used to prepare a lithographic printing plate that is resistant to press chemistry and can optionally be baked to increase press runlength.
Abstract:
A coating solution useful in the preparation of printing plate precursors comprises: a) a radiation sensitive composition C comprising a phenolic resin; b) at least one thermoplastic polymer P which has a solubility in aqueous alkaline media ranging from sparingly soluble to insoluble; c) a first solvent component A which is capable of solubilizing both composition C and thermoplastic polymer P; d) a second solvent component B having a volatility less than component A, wherein component B is capable of volatilizing composition C but not thermoplastic polymer P, and composition C and thermoplastic P are homogeneously dissolved in a mixture of components A and B; and e) at least one further polymer AP having a higher molecular weight than the phenolic resin of composition C, wherein polymer AB is miscible with the phenolic resin and immiscible with thermoplastic polymer P. The coating provides a radiation-sensitive layer for the substrate, and the coating contains homogeneously distributed thermoplastic polymer particles.
Abstract:
A radiation-sensitive composition, positive-working coating compositions useful for the preparation of lithographic printing plates and lithographic printing plate precursors comprising the composition are disclosed. The composition comprises at least one quinonediazide compound and at least one carboxylic copolymer. The compositions produce lithographic printing plates that show high print run stability.
Abstract:
Negative-working lithographic printing plate precursor a negative-working imagable layer and an outermost water-soluble overcoat layer that is disposed directly on the negative-working imagable layer. The outermost water-soluble overcoat layer comprises: (1) one or more film-forming water-soluble polymeric binders, and (2) organic wax particles dispersed therein. The organic wax particles have an average largest dimension of at least 0.05 μm and up to and including 0.7 μm, as determined from a scanning electron micrographic of the dried outermost water-soluble overcoat layer. Useful organic wax particles include fluorinated or non-fluorinated hydrocarbon wax particles.
Abstract:
A lithographic printing plate precursor can be used to prepare a printing plate using thermal ablation. The precursor has a non-thermally ablatable first layer on a substrate. Over the first layer is a thermally ablatable outer layer that includes an IR absorbing compound in an ablatable polymeric binder. The first layer includes a sol gel as a continuous inorganic matrix and a discontinuous inorganic phase (inorganic particles) dispersed therein.
Abstract:
Negative-working lithographic printing plate precursors can be imaged and then processed using a single processing solution in a processing apparatus without rinsing or gumming before the resulting lithographic printing plates are used for printing. The single processing solution (developer) comprises at least 2.5 weight % of a nonionic surfactant having an HLB value greater than 15 and at least 5 weight % of a polar organic solvent. Processing is accomplished without replenishment and reduced sludge formation is seen at the end of the processing cycle.