Treated mineral filler products, process for the preparation thereof and uses of same

A treated mineral filler product obtained by the process comprising the steps of:

• (a) providing at least one calcium carbonate-containing mineral filler, wherein the calcium carbonate-containing mineral matter is a dry ground mineral filler or a wet ground mineral filler that has been dried and has a total surface moisture level of below 1.0 mg/g if exposed to an atmosphere of 50% of relative humidity for 48 hours at a temperature of 23° C.;
• (b) providing a first treatment agent consisting of at least one saturated aliphatic carboxylic acid having from 6 to 9 carbon atoms;
• (c) contacting the at least one calcium carbonate-containing mineral filler of step (a), in one or more steps, with the first treatment agent of step (b), such that the added amount of the at least one saturated aliphatic carboxylic acid corresponds to a theoretical total number of molecules of between 1×1018 and 1×1020/m2 on the surface of the calcium carbonate-containing mineral filler, and at a temperature such that the at least one saturated aliphatic carboxylic acid is in a liquid or molten state;
• and
• (d) mixing the at least one calcium carbonate-containing mineral filler and the at least one saturated aliphatic carboxylic acid from step (c) to form a treatment layer comprising the at least one saturated aliphatic carboxylic acid and/or reaction products of the at least one saturated aliphatic carboxylic acid on the surface of the at least one calcium carbonate-containing mineral filler, and to obtain a treated mineral filler product having a volatile onset temperature of at least 260° C. and a total surface moisture level of below 1.0 mg/g if exposed to an atmosphere of 50% of relative humidity for 48 hours at a temperature of 23° C.