Method for producing polymerization catalyst composition, polymerization catalyst composition, method for producing polymer composition, and polymer composition

A method for producing a polymer composition, comprising:

• forming a polymer component by polymerizing at least one of a conjugated diene compound and a unconjugated olefin in the presence of a polymerization catalyst composition obtained by
• mixing and aging a second element and a third element, and then adding a first element to the mixture to react the first element with the mixture,
• wherein the first element is a compound that contains a rare earth element (REE-containing compound) wherein the REE-containing compound contains a rare earth element compound (REE compound) or a reactant of the REE compound with a Lewis base,
• the second element contains a compound represented by the following formula (X):
• YR1aR2bR3c (X)
• wherein:
• Y is a metal selected from Group 1, Group 2, Group 12, and Group 13 of the periodic table;
• R1 and R2 are hydrogen atoms or hydrocarbon groups each having 1 to 10 carbon atoms;
• and R3 is a hydrocarbon group having 1 to 10 carbon atoms, R1, R2, and R3 are the same as or different from each other, with a being 1 and b and c both being 0 when Y is a metal selected from Group 1 of the periodic table, a and b being 1 and c being 0 when Y is a metal selected from Group 2 and Group 12 of the periodic table, and a, b, and c are all 1 when Y is a metal selected from Group 13 of the periodic table, and the third element contains silica;
• wherein the first element contains a complex represented by the following general formula (i) or (ii):
• MX2·Lw (i)
• MX3·Lw (ii)
• wherein:
• M represents a lanthanoid element, scandium, or yttrium;
• X each independently represent a hydrogen atom, a halogen atom, an alkoxy group, a thiolate group, an amide group, a silyl group, an aldehyde residue, a ketone residue, a carboxylic acid residue, a thicarboxylic acid residue, a phosphorous compound residue, a substituted or unsubstituted cyclopentadienyl, or a substituted or unsubstituted indenyl;
• L represents a Lewis base;
• and w represents 0 to 3;
• and
• wherein water content of the third element is 0.1 wt % or more.