Steven Allen Derrick

US Patent:

53506235, Sep 27, 1994

Filed:

Sep 21, 1992

Appl. No.:

7/945480

Inventors:

Steven L. Derrick - Dallas TX

International Classification:

B32B 702

US Classification:

428217

Abstract:

A void-free, latex rubber cushion layer is interposed between the blanket cylinder and the base layer of a compressible printing blanket in an offset printing press. The latex cushion layer has a thickness of from 8 to 12 mils, and has a spring modulus which is substantially less than the spring modulus of the compressible layer in the printing blanket. The latex cushion layer will compress slightly, about 1 mil, in response to preloading at typical preload impression pressure. This means that a good quality print may be obtained at a substantially reduced impression pressure level, since it is not necessary to preload the blanket. During a printing operation, the latex cushion layer is under preload compression and applies a back pressure force which assures a quality imprint. The compressible layer of the blanket, which has a greater spring constant, is not compressed at the typical printing pressure setting. However, the compressible layer in the printing blanket is yieldable and will compress by about 3-4 mils when the loading is increased in response to a misfeed situation, for example, when two sheets or two envelopes are fed through simultaneously.