Abstract:
A lithographic printing plate precursor comprises an imageable 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 that is defined by Structure (I) shown in the disclosure, which dyes comprise one or more ethylenically unsaturated polymerizable groups in an organic group that is attached to the methine chain. These infrared radiation absorbing dyes exhibit a reduced tendency to crystallize in the imageable layers in the presence of tetraaryl borate counter anions and therefore provide improved shelf life.
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:
A radiation-sensitive composition for use in printing plates is described. The composition comprises: (a) at least one novolak; (b) at least one naphthoquinone diazide derivative; and (c) a copolymer comprising units A, B, and a unit C comprising a cyclic terminal urea group, wherein unit A is present in an amount of about 5 to about 50 mol % and has the formula is represented by wherein R1 is selected such that the homopolymer of A is alkali-soluble, unit B is present in an amount of about 20 to about 70 mol % and has the following formula is represented by wherein R2 is selected such that the homopolymer of B has a glass transition temperature greater than 100° C., preferably a glass transition temperature in the range from about 100 to about 380° C., and the unit C comprising a cyclic terminal urea group is present in an amount of about 10 to about 50 mol % and has the formula is represented by wherein X is a spacer group which is preferably selected from the group consisting of (a) a —(CR2)m— chain, (b) a —[CH2—CH2—O]m— chain; and (c) a —[Si(R2)—O]m— unit, wherein m is an integer greater than or equal to 1, more preferably between 2 and 12, the spacer group is connected to one of the carbon ring atoms of the cyclic urea unit or to one of the nitrogen atoms of the cyclic urea unit, and n is an integer greater than or equal to 1, more preferably between 1 and 5; and Y is a group selected from the group consisting of: wherein each R in units A, B, and C, the —(CR2)m— chain, the —[Si(R2)—O]m— unit, and group Y represents a bond between the cyclic urea and the spacer group X, or is independently selected from hydrogen, aryl, (C1-C12) alkyl, and or halogen.
Abstract:
Single layer IR-sensitive negative-working imageable elements include thermally coalesceable core-shell particles without a polymeric binder in an imageable layer. Thermal imaging causes coalescence of the particles in imaged regions while non-imaged regions can be removed with plain water or an aqueous solution containing an acidic polymer.
Abstract:
A radiation-sensitive composition for use in printing plates is described. The composition comprises: (a) at least one novolak; (b) at least one naphthoquinone diazide derivative; and (c) a copolymer comprising units A, B, and a unit C comprising a cyclic terminal urea group, wherein unit A is present in an amount of about 5 to about 50 mol % and has the formula wherein R1 is selected such that the homopolymer of A is alkali-soluble, unit B is present in an amount of about 20 to about 70 mol % and has the following formula wherein R2 is selected such that the homopolymer of B has a glass transition temperature greater than 100° C., preferably a glass transition temperature in the range from about 100 to about 380° C., and the unit C comprising a cyclic terminal urea group is present in an amount of about 10 to about 50 mol % and has the formula wherein X is a spacer group which is preferably selected from the group consisting of (a) a —(CR2)m— chain, (b) a —[CH2—CH2—O]m— chain; and (c) a —[Si(R2)—O]m— unit, wherein m is an integer greater than or equal to 1, more preferably between 2 and 12, the spacer group is connected to one of the carbon ring atoms of the cyclic urea unit or to one of the nitrogen atoms of the cyclic urea unit, and n is an integer greater than or equal to 1, more preferably between 1 and 5; and Y is a group selected from the group consisting of: and wherein each R in units A, B, and C, the —(CR2)m— chain, the —[Si(R2)—O]m— unit, and group Y is independently selected from hydrogen, aryl, (C1-C12) alkyl, and halogen.
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.
Abstract:
Images can be provided using a method comprising thermally imaging a negative-working imageable element to provide an imaged element with exposed regions and non-exposed regions, the exposed regions consisting essentially of coalesced core-shell particles, and developing the imaged element on-press to remove only the non-exposed regions using a lithographic printing ink, fountain solution, or both. The imageable element comprises a single thermally-sensitive imageable layer consisting essentially of an infrared radiation absorbing compound and core-shell particles that coalesce upon thermal imaging. The core of the core-shell particles is composed of a hydrophobic thermoplastic polymer, the shell of the core-shell particles is composed of a hydrophilic polymer that is covalently bonded to the core hydrophobic thermoplastic polymer, and the thermally-sensitive imageable layer comprises less than 10 weight % of free polymer.
Abstract:
Lithographic printing plates can be provided by imagewise exposing a negative-working lithographic printing plate precursor comprising an aluminum-containing substrate having thereon an imageable layer, to provide exposed and non-exposed regions in the imageable layer. This imaged element is then processed to remove the non-exposed regions in the imageable layer and to gum the resulting image in a single step without an intermediate rinsing step by using an aqueous alkaline solution having a pH of at least 9. The aqueous alkaline solution includes an organic amine having a boiling point of less than 300° C., a film-forming hydrophilic polymer, and optionally an anionic or nonionic surfactant.