Factors Governing Print Performance in Offset Printing of Matt Papers, 1998 Coating Conference Proceedings

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Matt and low gloss papers form a significant and increasing segment of the coated paper sector because they fulfill the demand for a paper with less glare and easy readability. Traditionally, matt papers have been produced by compromising between gloss, brightness and print abrasion. In matt applications, kaolins result in good print abrasion and delta gloss but low brightness. Conversely, carbonates give good brightness, but relatively poor delta gloss and print abrasion. Fine pigments can give too high a sheet gloss value or, if the paper is uncalendered, can result in a tendency to mark. Coarse pigments do give the required paper gloss but can result in low print gloss and high print abrasion. Blends of pigments are therefore used to try to reach a balance of properties.

This paper presents a new approach to matt pigments design based on bimodal blends of coarse and ultrafine components. It is shown that the new pigment system, can give an improved balance of properties, resulting in either improved print abrasion or in improved brightness without affecting sheet gloss or print performance. The new pigment system has to be tailored for particular applications e.g single coated paper will require a different pigment / binder package compared to a double coated paper.