Thermogravimetric Analysis of Pigments and Fillers for Papermaking

Abstract

Thermogravimetric analysis was applied to several kinds of pigments and fillers for papermaking to examine exact temperatures from which mass reduction commences. Clay and talc began to reduce mass from about 350°C and 450°C respectively. Clay contained in coated paper began to reduce mass from about 350°C. Therefore, “Other fillers and pigments (than calcium carbonate) such as clay and titanium dioxide are also unaffected by ashing at 525°C.” stated in ISO 1762: 2001, “Paper, board and pulps-Determination of residue (ash) on ignition at 525°C” was found to be apparently wrong. Calcium carbonate began to reduce mass from about 580°C, suggesting no decomposition at 525°C specified in JIS P 8251: 2002. The result also suggests no decomposition even at the ashing temperature 575°C specified in the previous edition of ISO 1762. However, the standard tolerates an accuracy of ±25°C due to technical difficulty in temperature control of muffle furnaces. So, it is appropriate that the ashing temperature was lowered from 575 to 525°C in the revision. There was no mass reduction for titanium dioxide below 1, 000°C.