Macdermid Imaging Technology

Kenneth M Strong

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. The carriage assembly is provided with a cap resin doctor blade that is maintained a constant distance above the lower glass plate, irregardless of the spacing between the cross-linked resin layer reservoir on the carriage assembly and the lower glass plate. In this manner, a constant thickness cap resin layer can be deposited on the lower glass plate in conjunction with different thickness cross-linking resin layers.

Method and apparatus for producing consistent thickness cap resin layers

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. In order to maintain the flatness of the lower glass plate, and thus the thickness of the resin layer during the doctor blade step, a support post is positioned in the lower fixture to support the center of the lower glass plate. The support post has transparent portions so as not to interfere with subsequent light transmission to the resin layer.

Assembly and method for producing flat printing plates

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.

Method and assembly for producing printing plates

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.

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Hockessin, DE, United States of America

Kenneth M Strong