Abstract:
A photopolymer printing plate precursor comprising a photosensitive coating on a support, wherein said photosensitive coating comprises a composition that is photopolymerizable upon absorption of light, said composition comprising at least one binder, a polymerizable compound, a sensitizer and a photoinitiator, characterized in that said binder is a copolymer that has a Tg of less than 70 °C, and wherein 1 to 50 mol-% of the monomeric units of said copolymer are substituted by at least one acidic group, has a very high sensitivity and resistence of the exposed image parts against alkaline developers, when exposed with a laser, even if no pre-heat step is performed.
Abstract:
A gum solution is provided which comprises a film- forming hydrophilic polymer or surfactant, and a salt formed by reaction of an acid, selected from phosphoric acid and phosphorous acid, with a di- or tri-alkanolamine. The gum solution is suitable for developing and gumming a lithographic photopolymer printing plate precursor. Also provided is a method for preparing a lithographic printing plate wherein this gum solution is used, and whereby printing plates are obtained which exhibit an improved clean-out performance.
Abstract:
A method of making a lithographic printing plate comprising the steps of : a) providing a lithographic printing plate precursor comprising (i) a support having a hydrophilic surface or which is provided with a hydrophilic layer, (ii) a coating on said support, comprising a photopolymerizable layer, and, optionally, an intermediate layer between the photopolymerizable layer and the support, wherein said photopolymerizable layer comprises a polymerizable compound and a polymerization initiator, b) image-wise exposing said coating in a plate setter, c) optionally, heating the precursor in a preheating unit, d) developing the precursor off -press in a gumming unit by treating the coating of the precursor with a gum solution, thereby removing the non-exposed areas of the photopolymerizable layer from the support , wherein said photopolymerizable layer further comprises a polymer containing an acid group and a basic nitrogen-containing compound capable of neutralizing said acid group, or wherein said photopolymerizable layer further comprises a polymer containing an acid group which is neutralized by a basic nitrogen-containing compound.
Abstract:
A method of preparing a lithographic printing plate in which no pre-heat step is used comprising the steps of: - providing a lithographic printing plate precursor comprising a support and a photopolymerizable image-recording layer, the image- recording layer comprising a monomer and a binder; - image-wise exposing the precursor in an exposure unit; - off press developing the exposed precursor with an aqueous solution in a processing unit; characterized in that the ratio of the total amount of monomer to the total amount of binder is at least 1 and the time lapse between exposing an image-area of the precursor and contacting the image-area with the aqueous solution is at least 1 minute.
Abstract:
The method of preparing a lithographic printing plate precursor according to the present invention comprises the steps of: providing an aluminum support; graining and anodizing the aluminum support; without applying a hydrophilic layer on the anodized aluminum support, coating a composition which is photopolymerizable upon absorption of light having a wavelength in the range of from 350 nm to 450 nm and comprising a polymerizable monomer or oligomer, a binder and a photo-initiator on the grained and anodized aluminum support to form a photopolymerizable layer; coating an overcoat on the photopolymerizable layer; characterized in that the ratio of the total solid amount of polymerizable monomer and oligomer to the total solid amount of binder is from 1.0 to 2.0.
Abstract:
A method of making a lithographic printing plate comprising the steps of : a) providing a lithographic printing plate precursor comprising (i) a support having a hydrophilic surface or which is provided with a hydrophilic layer, (ii) a coating on said support, comprising a photopolymerizable layer, and, optionally, an intermediate layer between the photopolymerizable layer and the support, wherein said photopolymerizable layer comprises a polymerizable compound and a polymerization initiator, b) image-wise exposing said coating in a plate setter, c) optionally, heating the precursor in a preheating unit, d) developing the precursor off -press in a gumming unit by treating the coating of the precursor with a gum solution, thereby removing the non-exposed areas of the photopolymerizable layer from the support , wherein said photopolymerizable layer further comprises a polymer containing an acid group and a basic nitrogen-containing compound capable of neutralizing said acid group, or wherein said photopolymerizable layer further comprises a polymer containing an acid group which is neutralized by a basic nitrogen-containing compound.
Abstract:
A method for making a lithographic printing plate is disclosed which comprises the steps of: (1) providing a heat-sensitive lithographic printing plate precursor comprising on a support having a hydrophilic surface or which is provided with a hydrophilic layer, a heat-sensitive coating, (2) image-wise exposing said precursor with IR-radiation or heat, and (3) developing said image-wise exposed precursor with an alkaline developing solution, characterised in that an antisludge agent is present in said precursor or in said developing solution or in said precursor and said developing solution, and wherein said antisludge agent is a 5-membered heteroaromatic compound, comprising a -NH-group wherein said hydrogen is capable of being deprotonated in said alkaline developing solution, selected from the group consisting of an optionally substituted benztriazole, 1, 2 , 3-triazole, tetrazole or indazole compound. According to the above method, the formation of sludge is inhibited or reduced.
Abstract:
A method for making a negative-working heat-sensitive lithographic printing plate precursor is provided which comprises the steps of (i) providing a support having a hydrophilic surface or which is provided with a hydrophilic layer, and (ii) applying on said support a coating which comprises a product DQ, wherein DQ is obtained by - the step of coating a solution or dispersion comprising a nucleophilic compound Q and a dye D selected from the list consisting of di- or tri-arylmethane dyes, cyanine dyes, styryl dyes and merostyryl dyes; or by - the step of coating a solution or dispersion comprising said compound Q and coating another solution or dispersion comprising said dye D; wherein D and Q interact to form interaction product DQ, having a white light optical density which is lower than the white light optical density of dye D, and wherein said interaction product DQ is capable of at least partially releasing a dye directly after exposure to infrared light or heat, thereby forming a visible image in said coating.