The influence of latex type and concentration on ink gloss dynamics

The dynamics of wet ink gloss on model pigmented latex coatings is recorded immediately after printing, every 0.1 s, and followed for 60 s. Two distin ct types of latices are used with three spherical polystyrene pigment sizes , at five pigment volume concentrations (PVCs). A novel gloss-meter device is used for the first time to investigate the influence of the latex type a nd the latex level on the ink gloss dynamics. The type of latex in the coating has a dramatic influence on the print glos s dynamics at low PVC: the high interactivity latex retards print gloss dev elopment at short times and results in low print gloss. As PVC increases, t he print gloss reaches a maximum. As PVC becomes large, both latex types sh ow a decrease in print gloss. The pigment size influences the results at hi gh PVC. Two different mechanisms seem to be responsible for the gloss resul ts: (1) the leveling of the ink film defects is slowed by penetration of th e mobile phase into the coating pore structure by capillary pressure effect s, and (2) the leveling is stopped when the mobile phase diffuses into the latex matrix. (C) 2000 Elsevier Science S.A. All rights reserved.