Calcium carbonate gives paper different characteristics by being mixed into it (filler) or by being applied onto its surface (pigment).
Calcium carbonate is an important raw material for manufacturing paper.
When mixing into paper as a filler, calcium carbonate gives the paper whiteness, opacity (makes it hard to see through the paper), surface smoothness, and flexibility. Spindle-shaped calcium carbonate is mainly used as a filler.
When applied to the paper surface as a pigment (coating), calcium carbonate will create glossiness in addition to whiteness and opacity. By controlling the shape of the calcium carbonate used in this process, we can increase gloss (glossy) or decrease gloss (matte). We use fine cubic particles for high gloss and large aggregate particles for low gloss.
Moreover, since the majority of paper is used for printing, it is important to have high quality after printing and good workability such as ink absorbency. For example, because fine pores are formed between fine particles, the particles can be used to easily absorb ink via capillary action. In the case of aggregated particles, absorbency can be achieved by creating pores inside the aggregates. By controlling the shape and size of particles, Shiraishi Central Laboratories develops products and proposes usages that meet the customers’ needs.