The use of minerals in papermaking is a practice that has long been known. Owing to the acidic conditions of paper making in former times, kaolin clay and talc were the main materials used as filler. But highly cost efficient and abundant calcium carbonate with its whiteness and rhomboedrical particle shape changed the process conditions from acidic to neutral and alkaline some 30 years ago.
Its use spread and today it is the most important filler and coating pigment for the paper making process. There are good reasons for this development. Calcium carbonate fillers and coating pigments lend paper a high degree of whiteness, opacity, gloss and a good printability at attractive prices.
Thanks to higher mineral contents of 50% and more with calcium carbonate, the amount of precious fibrous raw material can be reduced without any loss in paper strength.
The use of calcium carbonate also pays off in production. The paper machines can operate at higher speeds and the finished paper dries more quickly. These improvements save costly energy.
Today it is natural that almost all paper and cardboard contain calcium carbonate: coated and uncoated, wood-free and to an increasing extent, wood-containing papers.
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