A silica filler for a heat sensitive recording paper.

摘要

The principal object of the present invention is to solve the problem of high viscosity arising in the case of the high concentration dispersion of a coating liquid composition for a heat sensitive recording paper, using the high oil absorptivity amorphous silica of the prior art as a filler. This object can be attained by using a silica filler for a heat sensitive recording paper, consisting of amorphous silica having a pore volume of 1.5 to 2.8 ml/g with a pore radius of at most 75000 ANGSTROM . Preferred embodiments consist in a silica filler for a heat sensitive recording paper, consisting of amorphous silica having a pore volume of 1.5 to 2.5 ml/g with a pore radius of at most 75000 ANGSTROM and nitrogen adsorption external surface area (calculated by the t-method) of 20 to 70 m<2>/g and a silica filler for a heat sensitive recording paper, consisting of amorphous silica having a pore volume of 1.5 to 2.8 ml/g with a pore radius of at most 75000 ANGSTROM and a pH in a 5 % suspension of 7.0 to 9.0.