OPTICAL PRINT QUALITY OF COATED PAPERS

We are investigating how the optical properties of paper and prints re late to print quality. Using angle-resolved tight scattering, we obtai ned in-plane light-scattering distributions for both image and nonimag e areas of different printed coated papers. These distributions were u sed to calculate the contrast between the levels of scattering intensi ties as a function of incidence angle. The scattering contrast is defi ned as the ratio of the difference in intensity between a nonimage are a and an image area Of a print, over the sum of these two intensities. As the angle of incidence is increased, the contrast decreases and ev en becomes negative over a larger and larger interval. The positive sc attering contrast range (PSCR) is defined as the interval, in degrees, over which the scattering contrast is positive. PSCR values discrimin ated the samples in terms of both coating composition and coat weight. Gloss Variation measurements correlated well with the full-width-half -maxima of the scattering distributions of the prints. The nonimage an d image portions of the print have different topographical and, theref ore,different optical properties. This affects the contrast we can see between them.