Abstract: A polymer based on the reaction of an excess of diisocyanate with saturated polyolefine diols to form an oligomer and further reaction of the oligomer with hydroxyacrylates or hydroxymethacrylates is discussed. The polymer is then blended with ethylenically unsaturated monomers and a photoinitiator to produce a photosensitive composition which is useful in fabricating printing plates.

Abstract: Printing plates are formed from a layer of photo polymerizable resin by a process and assembly which includes a negative of the image or images to be formed in the printing plate. The negative is placed on a lower glass support plate and a bank of lights is disposed below the lower glass support plate. A cover film is laid down on the negative, and a very thin layer of resin, called a cap resin, is deposited on the cover film. A layer of the resin to be cross-linked is deposited on the cap resin layer, and the cross-linked resin layer is covered with a polyester sheet, on the top of which an upper glass plate is lowered. The cap resin layer and the cross-linked resin layer are both laid down on the lower glass plate assembly by meas of a carriage assembly that traverses over the lower glass plate assembly, and which carries the cross-linking resin and cap resin reservoir. The thickness of the cross-linked resin layer varies widely, while the thickness of the cap resin layer is narrowly confined.

Abstract: An assembly for producing printing plates from photopolymerizable resins includes an upper fixture assembly and a lower fixture assembly. The upper fixture assembly includes an upper glass plate, and an upper shutter box in which an upper UV light source is located. The upper fixture is mounted on a guide post so that the upper fixture assembly can be raised and lowered relative to a lower fixture assembly. The lower fixture assembly includes a lower light bank table containing a lower UV light source, and a lower glass plate on which the resin layer is cast. A doctor blade is drawn over the resin layer to smooth the latter on the lower glass plate. The resin layer is then exposed to UV light through a print pattern-defining negative so as to selectively harden the resin layer and form a printing plate that is defined by the negative pattern.

Abstract: Printing plates are formed from a layer of photopolymerizable resin by a process and assembly which involves moving a resin layer past a variable intensity light source so as to sequentially and selectively cross-link the resin layer as the resin layer moves past the light source.

Abstract: Printing plates are formed from a layer of photo polymerizable resin by a process and assembly which includes a back masking negative placed over the non-printing side of the resin layer. A connective substrate is positioned between the back mask negative and the resin layer. A negative of the image or images to be formed on the printing plate is positioned on the side of the resin layer which is to form the printing surface of the plate. Both sides of the resin layer are exposed to UV light, and the back mask negative serves to allow hardening of the resin only in the areas of the resin layer where printing surfaces are located. Thus, a plurality of isolated printing surfaces may be formed on the plate, which printing surfaces are connected together by the connective substrate. In this manner, a photo polymerized floor need not be produced on the printing plates, allowing increased resin recovery after the plate has been formed.

Abstract: A method for curing a photosensitive resin composition includes use of an especially thin gauge protective cover film, preferably incorporating a coating to permit ease of removal after imaging. The method also uses a photosensitive resin composition incorporating a photospeed modified capping layer to selectively retard image growth during exposure. To eliminate undesirable defects in the cured photopolymer, a glass plate which had previously contacted and flattened the composition, is separated from the composition by at least 0.025 inches after partially curing the composition but prior to completely curing the composition. The partial cure of the composition is achieved by directing light to the composition from a source of actinic radiation positioned about 6 to 30 inches from the resin composition, where the actinic radiation has a wavelength of maximum intensity of about 365 to about 375 nm.

Abstract: A printing plate laminate is formed of a carrier sheet, sticky back, a substrate and photopolymer layer. The substrate has a thickness of only about 0.2 mil to about 3 mil. The printing plate laminate can be formed from a process wherein photopolymerizable resin is coated onto a bilayer substrate, where one layer of the substrate is in contact with the photopolymer layer and has a thickness of about 0.2 mil to about 3 mil, and a second layer of the substrate has a thickness of about 4 mil to about 7 mil. A pressure sensitive adhesive lies between the first and second layers of the substrate, so that the second layer may be easily peeled away from the first layer after selectively curing and then developing the photopolymer layer.

Abstract: A compressible printing plate is prepared by casting liquid photopolymerizable resin directly onto a compressible material having open cells on its surface. The photopolymerizable resin is incompletely cured by exposure to actinic radiation, preferably in the absence of a coverfilm covering the photopolymerizable resin. A further layer of photopolymerizable resin is then cast onto the incompletely cured resin, and the whole exposed to actinic radiation through an image-bearing transparency. A release composition may be placed between the image-bearing transparency and the photopolymerizable resin to provide for decreased adhesion therebetween. After development, an image-bearing laminate suitable as a printing plate for flexographic printing is obtained. The printing plate achieves excellent short and long term adhesion between the compressible layer and the photopolymer plate, without the necessity of a tie layer or adhesive therebetween.

Abstract: The nonpolymerized portion of the resin on a photopolymerizable resin is recovered from a printing plate by squeezing the liquid resin off of the plate with the doctor roller. The plate is mounted on a drum and the drum is caused to rotate in a predetermined direction while the doctor roller is pushed against the surface of the plate. The liquid resin falls from the plate into a collection tray. The collection tray is divided into opposite adjacent resin repository sections, with a separate doctor roller being disposed above each repository section of the collection tray. Incompatible resins can be squeezed into the respective repository sections of the collection tray by the respective rollers by selectively rotating the drum in one direction or the other, and by selectively engaging the plate with one of the rollers while keeping the other roller away from the plate.

Abstract: A photosensitive resin composition includes a urethane oligomer prepared from a hydroxy-functionalized acrylate and/or methacrylate, at least one diol, and 2,4-toluene diisocyanate and 2,6-toluene diisocyanate in a 65:35 weight ratio. The resin composition additionally contains a monomer having at least one acrylate or methacrylate group, and a photoreactive initiator. The photosensitive resin composition may be cured to provide a soft photopolymer printing plate, particularly well suited for printing on corrugated bard.

Abstract: An aqueous-developable dry-film photopolymerizable composition is disclosed wherein the photopolymerizable composition contains a hydroxyl-modified vinyl chloride/vinyl acetate polymer.