Pigment dispersion, electrostatic image developing toner and process for the formation of microcapsule utilizing isocyanate-containing organosilicon coated pigment

An electrostatic image developing toner, comprising a pigment incorporated in a binder resin, wherein said pigment is one treated with at least one isocyanate-containing organosilicon compound selected from silylisocyanate derivatives represented by formulae (I), (II) and (III) and condensates thereof:

• R.sub.p R'.sub.q R".sub.r Si(NCO).sub.4-p-q-r (I)
• (RO).sub.p (R'O).sub.q (R"O).sub.r Si(NCO).sub.4-p-q-r (II)
• R.sub.x (R'O).sub.y Si(NCO).sub.z (III)
• wherein R, R' and R" each represents an alkyl group, an aryl group or an alkenyl group;
• p, q and r, which each represents 0 or an integer of from 1 to 3, satisfy the relationship (p+q+r<3);
• and x, y and z, which each represents an integer 1 or 2, satisfy the equation (x+y+z=4).

A process for forming a microcapsule which comprises allowing at least a first capsule shell-forming monomer and a second capsule shell-forming monomer to undergo reaction inside and/or on the interface of oil drops to form capsule shells, said oil drops containing a pigment, an organic solvent, and at least one isocyanate-containing organosilicon compound selected from silylisocyanate derivatives represented by formulae (I), (II) and (III) and condensates thereof:

• R.sub.p R'.sub.q R".sub.r Si(NCO).sub.4-p-q-r (I)
• (RO).sub.p (R'O).sub.q (R"O).sub.r Si(NCO).sub.4-p-q-r (II)
• R.sub.x (R'O).sub.y Si(NCO).sub.z (III)
• wherein R, R' and R" each represents an alkyl group, an aryl group or an alkenyl group;
• p, q and r, which each represents 0 or an integer of from 1 to 3, satisfy the relationship (p+q+r<3);
• and x, y and z, which each represents an integer 1 or 2, satisfy the equation (x+y+z=4).