METHOD OF PRODUCING MODIFIED SILICA AND MODIFIED SILICA

PROBLEM TO BE SOLVED: To provide a method of producing modified silica having high dispersibility into a rubber composition and capable of providing the rubber composition having lower heat generating property.SOLUTION: There is provided the method of producing modified silica including a step of polymerizing at least one monomer selected from a group consisting of a conjugated diene monomer and a non-conjugated olefin in the presence of a polymerization catalyst composition consisting of a first element which is a rare earth element compound or a rare earth element-containing compound containing the rare earth element compound and a Lewis base, a second element containing a compound represented by the general formula (X) and a third element containing silica and having a water content of 0.1 wt.% or more, the blended weight of the silica being equal to or more than the blended weight of the monomer. The general formula (X): YRRR(X), where Y is a metal selected from the group I, the group II, the group XII and the group XIII in the periodic table, Rand Ris a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom, Ris a hydrocarbon group having 1 to 10 carbon atoms, provided that Ror Rmay be the same or different, a is 1 and b and c are 0 when Y is a metal selected from the group I in the periodic table, a and b are 1 and c is 0 when Y is a metal selected from the group II and the group XII in the periodic table, and a, b and c are 1 when Y is a metal selected from the group XIII in the periodic table.