The effect of adding talcum powder into the pulp

Talc is a hydrate of magnesium silicate. The requirement of talc in papermaking industry is high whiteness, generally 75-90%. The particle size requirement is 325 and the pass rate of 200 mesh sieve is 98%. Iron and calcium content should be small, loss of stability, generally in 10-15%, moisture is not greater than 1%, dust limit in 0.5 ~ 1.0mm/g..

Talc powder can be divided into two types: ground talc powder and fine talc powder according to their particle size. According to different industrial purposes, divided into 9 varieties, paper grade talc powder code named ZZ. Talc is actually a kind of fine particles with negative charge, especially talc which is well moistened by water and shows higher double-layer potential.

On the other hand, due to the surface properties of talc is low, the air and surface hydrophilic hydrophobic, gas-solid contact interfacial tension is less than the interfacial tension of liquid-solid two-phase flow, so the talcum powder is not easy to be wetted by water from the air, thus affecting its dispersion, which in the fiber on the left a.

According to the research data, the retention of fillers is also related to filtration, flocculation and adsorption, but most of them are the effect of flocculation, followed by filtration. Therefore, to improve the retention rate of talcum powder, you must first let the surface of talc was good and sufficient moist, and the bending of the surface charge, so that it can be fully dispersed in the pulp and fiber (by retention agent) complexation and flocculation.

To this end, such as the use of talc as filler and to achieve high retention rate, we must pay attention to the choice of additional process and retention agent choice.