Sherman & Shalloway
Coated pigment composition having improved abrasion resistance and process for preparation thereof
 A coated pigment composition having improved resistance, especially to abrasion, is disclosed, said coated pigment composition consisting essentially of particles composed mainly of an inorganic color pigment and a continuous solid glass coating layer covering the surfaces of said pigment particles, said continuous solid glass coating layer being formed of a continuous phase composed mainly of an alkali polysilicate having the following mole composition EQU MO.sub.2 : SiO.sub.2 = from 1 : 5 to 1 : 2 wherein M stands for an alkali metal component, in which the solid glass coating layer is present in an amount, as calculated as SiO.sub.2, of from 3 to 40 % by weight based on said pigment particles and the value of the specific surface area ratio, expressed by the following formula EQU R.sub.s = S.sub.c /S.sub.p PA1 wherein S stands for the specific surface area (m.sup.2 /g) of uncoated pigment particles, S.sub.c stands for the specific surface area (m.sup.2 /g) of coated pigment particles, and R.sub.s stands for the specific surface area ratio, Is within a range of from 1.00 to 1.07. 
Mizusawa Kagaku Kogyo Kabushiki Kaisha
C C C C C C C Y C C
C09C C01P C01P C01P C09C C01P C09C Y10T C01P C01P
inventional additional additional additional inventional additional inventional additional additional additional
Okitsu Kaichiro Yujiro Mamoru
Hidetika Miyazawa Sugahara Saito