Waterless Inks for Coldset Printing, 1996 International Printing & Graphic Arts Conference Proceedings

R R Durand. Jr and O. Wasilewski

Sun Chemical Corporation

S. M. Chou and L. J. Bain

Rockwell Graphic Systems

E. Sanderson

Weyerhaeuser

The waterless printing process requires the ability to control ink re-lease characteristics from non-image areas in order to prevent back-ground toning. It is well known that high viscosity and cohesiveness can be built into an ink in order to maintain good release characteris-tics, as well as to improve the range of temperature before tinting occurs. At the same time, this type of rheology compromises ink transference properties within the roller train and can create a prod-uct which does not have the press stability desired for the waterless process For high speed web applications. the ink formulation should be “press” friendly as well as “plate” friendly In the case of coldset printing, the absorbent paper stocks (including newsprint) usually perform best with inks having lower viscosity and tack The control of ink rheology ensures that good printability is maintained while minimizing pick and lint behavior. The presence of water in conventional lithography is important to paper interactions for coldset printing. Thus, the development of coldset waterless inks represents considerable challenges to the ink formulator In this paper, the options for controlling ink rheology will be dis-cussed as they apply to ink release mechanisms Low viscosity prod-ucts which maintain clean printing will be described Results from printing on a variety of uncoated papers (including newsprint) will be reported The constraints of waterless web printing in coldset mode on absorbent stock will be examined