| Résumé : |
In lithographic printing, an ink maker relies heavily on the quality of his varnish, primarily to provide a "vehicle" to transfer and direct the pigment to the substrate. It must be as wise as a "professor," knowing when to emulsify just enough to transfer down an ink train but only adhere to the image area on a printing plate. Then, as polished as a "palace guard," this varnish, after being mixed, pushed and squeezed at various shear rates, must stand tall, dry and be resilient to the elements. Finally, the varnish must also act as a "make-up artist" allowing only the best visual properties to be seen upon presentation to the end use customer. How can a varnish perform all of these tasks ?
The backbone of a good offset varnish consists of strategically selected hard resins chosen due to their economical, structural and compatibiIity attributes they contribute to the final product. Since the polymers are generally solid at ambient temperatures, fully judging the resin's characteristics require dispersion into a fluid medium. The choice of solution formulation has been the basis for many a lively conversation.
The purpose of this paper is to give an ink or varnish maker a useful sketch or "fingerprint" of a prospective resin concentrating on specific properties critical to producing a high quality varnish. This will allow the user to look at a wide range of resins, objectively making relative comparisons using equipment and/or terminology commonly used in this industry. |
Aller sur edunet
Accueil
Modern characterisation methods on modern offset resins in PAINTINDIA, Vol. L, N° 1 (01/2000)
