Looped, elongate letterpieces printing plate for use on rotary presses, and method of preparation

A method of preparing a letterpress printing plate for use on a rotary press of the kind having a plate cylinder for printing on paper or the like against an impression cylinder, the plate cylinder having a series of sprockets formed on its surface along at least one edge thereof, and a guide cylinder disposed in parallel spaced relation to the plate cylinder, the method comprising the steps of:

• (a) providing an elongate flexible band comprising a base layer and a photosensitive layer attached to each other;
• (b) exposing the photosensitive layer to light through a negative to cause selective hardening at portions thereof defining a printing image and a series of positioning markings along at least one marginal side edge portion thereof while leaving unhardened the remaining portions of the photosensitive layer;
• (c) dissolving away the unhardened portions of the photosensitive layer in one and the same process to leave in relief the printing image and the series of positioning markings in the form of annular projections protruding from the base layer, the annular projections being disposed along at least one marginal side edge portion of the base layer;
• (d) forming a series of sprocket holes, each hole being formed through both the base layer and one of said annular projections;
• and
• (e) joining the ends of the band to form a loop which is to be wrapped around the plate cylinder and guide cylinder of the rotary press so that the sprockets on the plate cylinder can be engaged in the sprocket holes in the looped band.

A method of preparing a letterpress printing plate capable of being joined together at its opposite ends to form an endless loop for looping around a plate cylinder and a guide cylinder of a rotary press, the method of comprising the steps of:

• providing an elongate flexible band comprised of a base layer and a photosensitive layer overlying and secured to the base layer;
• exposing the photosensitive layer to light through a patterned negative to create hardened portions of the photosensitive layer corresponding to a printing image and a series of annularly-shaped positioning markings extending lengthwise along at least one marginal side edge portion thereof while leaving unhardened the remaining portions of the photosensitive layer;
• dissolving away the unhardened portions of the photosensitive layer in one dissolving process to leave in relief on the base layer both the printing image and the series of positioning markings in the form of annular projections defined by the hardened portions of the photosensitive layer;
• and thereafter forming a series of perforations, each perforation being formed through both the base layer and one of said annular projections.