US2302037A - Printing plate and printing unit made from superpolyurethanes - Google Patents

Description

Patented Nov. 17, 1942 PRINTING PLATE AND PRINTING UNIT MADE FROM SUPERPOLYURETHANES Leo Kollek, Ludwigshafen-on-the-Rhine, Germany; vested in the Alien Property Custodian No Drawing. Application August 10, 1940, Serial No. 352,113. In Germany September 15, 1939 2 Claims.

This invention relates to printing plates and printing units made from superpolyurethanes.

It is known to make printing plates and printing units therefor, as for example clichs and types, from organic plastic materials by pressureor injection-molding processes. The majority of plastic materials, however, are not sufliciently resistant to heat and by reason of their inferior surface hardness are worn out in a pretty short time when printing large circulations. The plates must be resistant to cleansing agents such as petroleum or benzene hydrocarbons applied after use and must be capable of being repeatedly recast and used over again, the same as printing metals. For these reasonscellulose derivatives or hardenable artificial resin compositions were un suitable for general adoption for practical use in the above field.

I have now found that superpolyurethanes, i. e.

high-molecular film-forming u'rethanes containing a plurality of adjoining groups wherein X and Y stand for divalent organic radicals and which are obtainable for example by heating organic diisocyanates together with compounds having 2 hydroxy groups according to the copending U. S. application Serial No. 239,456 filed November 8, 1939, are excellently suitable as materials for printing plates and component parts therefor.

Suitable superpolyurethanes are for example those from mand p-phenylenediisocyanate,

are separated by more than 4 carbon atoms, say from 6- to 10.

These materials, which may also be incorporated with fillers or pigments, are pale in color and hence facilitate the legibility of the printing block. Their specific gravity is only slightly above 1.

The superpolyurethanes may be used for the preparation of printing profiles of most elaborate design, individual types, composed types, typelines or clichs. They may be produced for this purpose principally by injection-moulding. However, they may also be formed by casting and pressure-moulding or with suitable cutting tools, for example engravers. Even very thin lines, for example the finest lines of etchings, may be reproduced with great sharpness. After moulding they solidify very rapidly and then possess great toughness, strength and surface hardness which remain constant over a wide range of temperatures. For these reasons the printing plates are highly fracture-proof and therefore thin printing plates therefrom may be easily bent and immediately used in rotary printing. Owing to their great surface hardness very large circulations may be printed without the profiles of the types becoming markedly worn out.

As the superpolyurethanes are insoluble in the standard solvents, the printing plates made therefrom can be easily cleaned afteruse or when soiled with printing ink, The cliches, printing plates etc. after use may also be re-cast or re-moulded. In addition, the superpolyurethanes have the most desirable property of being non-inflammable and resistant to most chemicals.

What I claim is:

l. A printing form composed essentially of a superpolyurethane.

2. A printing letter type composed essentially of a superpolyurethane.

LEO KOLLEK.