Lithographic Plate and Photoresist Having Photosensitive Layers of Diazo and Cinnamoylated Polyvinyl Alcohol Materials

This application incorporates by specific reference U.S. Pat. No. 3,808,004 issued Apr. 30, 1974, having Daniel C. Thomas and Jack L. Sorkin as inventors and assigned to the Richardson Graphics Company, Chicago, Ill. Said patent is based on application Ser. No. 829,149 filed May 29, 1969.

An abstract of said reference follows:

In such patent a photopolymerizable coating over a diazo resin is used to provide high-speed lithographic plate or a photoresist while also improving the run length of the plate incorporating the combination. Additionally, improved development of the plate occurs. The photopolymer comprises a cinnamoylated resin.

A brief summary of the referenced patent follows:

The invention of said referenced patent generally resides in a two layer lithographic or photoresist plate in which a cinnamoylated photopolymer is placed over a diazo resin base in order to engender the above stated advantageous properties.

There are no drawings in the referenced patent.

A representative claim in the referenced patent is as follows:

A high-speed presensitized plate for lithography or photoresist etching comprising in combination, a plate base, a sub-base coating over the plate base, a light sensitive diazo resin condensation product of an aldehyde and a diazonium compound layer over the sub-base coating and a phenoxy cinnamate photopolymer coating over the diazo resin layer.

Regarding the present invention, in Example 7 of the referenced patent lithograph printing plates were made with either an alkyd resin or an aryl allyl ester resin placed over a diazo resin layer. Thereafter plates containing these resins were exposed and tested for bench and press results. The data in Example 7 indicate that the aryl allyl ester and diazo combination when exposed and developed in a standard method yielded a run length of about 35,000 copies.

Compared to the present invention (cinnamoylated polyvinyl alcohol polymer over a diazo resin) the system of an aryl allyl ester over diazo resin was inferior as illustrated by the reported data in columns 13-14 of said U.S. Pat. No. 3,808,004 for plates 28b, 28c, 28d, 29b, 29c, 29d, 30b and 32b which showed an improved run length associated with the claimed system. More particularly, plate 28d showed that for a 10 second exposure over 110,000 copy run lengths could be attained. Compared to the 35,000 copy run length for the aryl allyl ester over a diazo resin, a substantial improvement was realized.

The degree of cinnamoylation of the polyvinyl alcohol resin, as shown by the above data, reflects the degree of improvement achieved regarding press test run lengths. More particularly, plates 28c, 28d and 29b, which were essentially 100% cinnamoylated, had run lengths for exposure times varying from 10 seconds to 2 minutes of all over 100,000 copies. This illustrates, more particularly, the improved results for the claimed invention especially when compared to the aryl allyl ester system.