A novel, non-mechanical method for producing matte and dull papers with exceptional print gloss.

Application: The technology described here could result in a new grade of paper and add value to low gloss paper grades.

In the manufacture of low-gloss coated paper it is very difficult to achieve both low sheet gloss and high print gloss. The reason is found in the technical approaches used for the production of low gloss coated papers. These include the use of fine pigments with little or no calendering, coarse pigments with calendering, a bimodal mixture pigment approach, the use of a shrinkable binder, and special calendering techniques. with most of the pigment and binder approaches, the effect is not limited to the surface but extends through the bulk of the coating. The micro-roughness that produces the low sheet gloss usually includes a high level of micro-porosity, making high ink gloss difficult to achieve. Special calendering techniques, such as those using sand blasted or etched roll surfaces, can make it difficult to achieve high levels of smoothness.

The technique described in this paper involves the application of a very light weight, pigmented coating to a previously coated paper. The result is a partial layer or "less-than-mono-layer" of pigments bound to the surface, which suppresses sheet gloss. The associated surface micro-roughness, while coarse enough to suppress sheet gloss, is fine enough to be covered by the ink film. This provides for a low gloss, mark-resistant paper surface that produces good print gloss and exceptional delta gloss.

Fu and Brown are with Rohm and Hess Co., 727 Norristown Road, Spring House, PA 19477. Email Fu at [e-mail] or Brown at [e-mail].