Browse Prior Art Database

PROCESS FOR PREPARING WATERLESS PRINTING MASTERS

IP.com Disclosure Number: IPCOM000023511D
Original Publication Date: 1977-Dec-31
Included in the Prior Art Database: 2004-Mar-31
Document File: 2 page(s) / 256K

Publishing Venue

Xerox Disclosure Journal

Abstract

Improved waterless lithographic masters are provided com-prising an elastomeric ink releasing surface layer to which a particulate imaging material can be adhered, In conventional lithography, an aqueous fountain solution is employed to prevent the ink from wetting the nonimaged areas of the planographic plate. It has recently been discovered that the requirement for a fountain solution can be obviated by employing a planographic plate having a silicone, i.e., organopolysiloxane, elastomeric layer. Because that silicone is not wetted by the printing ink, no fountain solution is required. While the use of silicone elastomers as a printing surface has obviated the requirement for a fountain solution, it has been found that finely divided particulate material commonly referred to in the trade as "toner", is not easily attached to the silicone,

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XEROX DISCLOSURE JOURNAL

PROCESS FOR PREPARING WATERLESS Proposed Classification
PRINTING MASTERS U.S. Cl. 101/130
Richard L. Schank Int. Cl, B41f 7/00

Improved waterless lithographic masters are provided com~
prising an elastomeric ink releasing surface layer to which a
particulate imaging material can be adhered,

In conventional lithography, an aqueous fountain solution is
employed to prevent the ink from wetting the nonimaged areas
of the planographic plate. It has recently been discovered
that the requirement for a fountain solution can be obviated
by employing a planographic plate having a silicone, i.e.,
organopolysiloxane, elastomeric layer. Because that silicone
is not wetted by the printing ink, no fountain solution is
required. While the use of silicone elastomers as a printing
surface has obviated the requirement for a fountain solution,
it has been found that finely divided particulate material
commonly referred to in the trade as "toner", is not easily
attached to the silicone,

It has now been discovered that a master comprising a conven~
tional substrate and an overlying layer of a copolymer having
polydimethylsiloxane blocks with vinyl or hydroxyl groups and
organic thermoplastic blocks, can be imaged with an ink ac~
cepting particulate image material and the copolymer cross~
linked to bond the imaging material thereto and provide an
insoluble ink releasing background area so that no dampening
or fountain solution is required. In addition, the master is
more resistant to...