摘要:
Lithographic printing plates for wet or waterless offset printing are disclosed which can be imagewise exposed using a digitally controlled IR laser. The invention comprises a laser imagable lithographic printing plate comprising a substrate (201), a photosensitive coating (202) on the substrate, and a water soluble laser ablatable top coating (264) containing dyes or polymers that absorb infra-red, ultraviolet and visible light. Laminated transparent polymer films and/or peelable polymeric coatings films (203) can be interposed between the coated substrate and a water soluble and/or organic solvent soluble laser ablatable top layer to augment plate production or image inscription on the plate.
摘要:
Presensitised lithographic plates are prepared which permit direct formation of printable images on plates by digital computerization without the intervening formation of a photographic image with a quality that allows the plates to be used for high volume printing applications. The lithographic printing plate has a structure which contains a substrate; a positive or negative working photosensitive layer; and a thermally sensitive masking layer which is opaque to the actinic radiation but which is soluble in an aqueous medium. The masking layer contains a heat softenable disperse phase which is insoluble in the aqueous medium; a polymeric continuous phase which is soluble or swellable in the aqueous medium; and a colorant which strongly absorbs radiant energy and converts the radiant energy to heat. In use, the masking layer is digitally exposed to a computer controled laser beam so that exposed images areas of the masking are insolubilized in the aqueous medium; soluble mask image areas of the mask layer are then removed to form an opaque image mask on the photosensitive layer which is then exposed to actinic radiation passing through the mask to solubilize or insolubilize exposed areas of the photosensitive layer; the photosensitive layer is then developed with the developer liquid to remove the soluble image areas and any overlying mask areas to form the lithographic printing plate. Both wet and waterless lithographic printing plates may be digitally prepared in this manner.
摘要:
A waterless or driographic printing plate which can be thermally imaged by an infrared laser is composed of a substrate; a thermal imaging layer containing a photothermal conversion material, such as an infrared absorbing material, and a thermoplastic polyurethane with pendent allyl groups; and a cross-linked silicone polymer top layer. It was discovered that when the imaging layer contains an allyl functional polyurethane mixed with an infrared absorbing dye or pigment, the polymeric layer will have enhanced solubility in certain solvents when exposed to infrared radiation. In addition, the polymeric layer continues to exhibit excellent adhesion to the silicone in unexposed areas so that the infrared absorbing layer can endure development with a suitable organic solvent, or a solvent mixture. Mild brushing or rubbing with the developing solvent readily removes laser-struck portions of the infrared imaging layer while unexposed areas remain firmly intact.
摘要:
The present invention includes an imageable element, comprising a substrate and a thermally imageable composition which includes a graft copolymer having hydrophobic and hydrophilic segments. Upon imagewise exposure to thermal energy, the graft copolymer produces exposed regions that are less soluble in a developer than the unexposed regions. Also included is a method of producing an imaged element which includes a graft copolymer according to the present invention.
摘要:
Presensitised lithographic plates are prepared which permit direct formation of printable images on plates by digital computerization without the intervening formation of a photographic image with a quality that allows the plates to be used for high volume printing applications. The lithographic printing plate has a structure which contains a substrate; a positive or negative working photosensitive layer; and a thermally sensitive masking layer which is opaque to the actinic radiation but which is soluble in an aqueous medium. The masking layer contains a heat softenable disperse phase which is insoluble in the aqueous medium; a polymeric continuous phase which is soluble or swellable in the aqueous medium; and a colorant which strongly absorbs radiant energy and converts the radiant energy to heat. In use, the masking layer is digitally exposed to a computer controled laser beam so that exposed images areas of the masking are insolubilized in the aqueous medium; soluble mask image areas of the mask layer are then removed to form an opaque image mask on the photosensitive layer which is then exposed to actinic radiation passing through the mask to solubilize or insolubilize exposed areas of the photosensitive layer; the photosensitive layer is then developed with the developer liquid to remove the soluble image areas and any overlying mask areas to form the lithographic printing plate. Both wet and waterless lithographic printing plates may be digitally prepared in this manner.
摘要:
Multilayer, positive working, thermally imageable, bakeable imageable elements are disclosed. The elements have a substrate, an underlayer, and a top layer. The underlayer comprises a polymeric material that comprises, in polymerized form about 5 mol% to about 30 mol% of methacrylic acid; about 20 mol% to about 75 mol% of N-phenylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, or a mixture thereof; optionally, about 5 mol% to about 50 mol% of methacrylamide; and about 3 mol% to about 50 mol% of a compound represented by the formula: CH2C(R2)C(O)NHCH2OR1, in which R1 is C1 to C12 alkyl, phenyl, C1 to C12 substituted phenyl, C1 to C12 aralkyl, or Si(CH3)3; and R2 is H or methyl. Other materials, such as a resin or resins having activated methylol and/or activated alkylated methylol groups, such as a resole resin, may be present in the underlayer. The elements produce bakeable lithographic printing plates that are resistant to press chemistries.
摘要:
The present invention also includes an imageable element, comprising a substrate and a thermally imageable composition comprising a thermally sensitive polymer which exhibits an increased solubility in an aqueous developer solution upon heating. The thermally sensitive polymer includes at least one covalently bonded unit and at least one thermally reversible non-covalently bonded unit, which includes a two or more centered H-bond within each of the non-covalently bonded unit. The present invention also includes a method of producing the imaged element. The present invention still further includes a thermally imageable composition comprising a thermally sensitive polymer according to the present invention and a process for preparing the thermally sensitive polymer, which is a supramolecular polymer. The process includes contacting a hydrocarbly-substituted isocytosine and a diisocyanate to produce a mono-adduct and contacting the mono-adduct and a polyfunctional material to produce the supramolecular polymer.
摘要:
Lithographic printing plates for wet or waterless offset printing are disclosed which can be imagewise exposed using a digitally controlled IR laser. The invention comprises a laser imageable lithographic printing plate comprising a substrate, a photosensitive coating on the substrate, and a water-soluble laser ablatable top coating containing dyes or polymers that absorb infrared, ultraviolet and visible light. Laminated transparent polymer films and/or peelable polymeric coatings films can be interposed between the coated substrate and a water-soluble and/or organic solvent soluble laser ablatable top layer to augment plate production or image inscription on the plate.