Method for producing polishing liquid composition
Provided is a method for producing a polishing composition capable of reducing scratches and particles of an object to be polished, after polishing. It is a method for producing a polishing composition including a step of filtering with a filtration filter a silica particle dispersion containing colloidal silica whose primary particles have an average particle diameter in a range of 1 to 100 nm, wherein the filtration filter includes diatomite cationized by use of a polyvalent amine compound having 9 to 200 cationic groups in the molecule.
1. A method for producing a polishing composition, the method comprising a step of filtering with a filtration filter a silica particle dispersion containing colloidal silica whose primary particles have an average particle diameter in a range of 1 to 100 nm,
wherein the filtration filter comprises diatomite cationized by use of a polyvalent amine compound having 9 to 200 cationic groups in the molecule.
2. The method for producing a polishing composition according to claim 1 , wherein the polyvalent amine compound is polyalkyleneimine.
3. The method for producing a polishing composition according to claim 1 , wherein the polyvalent amine compound has a number average molecular weight in a range of 400 to 9000.
4. The method for producing a polishing composition according to claim 1 , wherein an integrated pore volume of not larger than 0.15 μm of the diatomite obtained by a nitrogen adsorption method is not less than 0.3 mL/g.
5. The method for producing a polishing composition according to claim 1 , wherein the diatomite has a BET specific surface area of not less than 4.0 m 2 /g.
6. The method for producing a polishing composition according to claim 1 , wherein in the cationization treatment, the ratio in the amount of the polyvalent amine compound in use to the diatomite (weight ratio) is 1/500 to 1/1 as ('weight of polyvalent amine compound' / ‘weight of diatomite’).
7. The method for producing a polishing composition according to claim 1 , wherein a content of the cationized diatomite in the filtration filter is not less than 0.001 g/cm 2 and not more than 1 g/cm 2 .
8. The method for producing a polishing composition according to claim 1 , wherein a content of the colloidal silica in the silica particle dispersion is 1 to 50 wt %.
9. The method for producing a polishing composition according to claim 1 , wherein the number of the cationic groups in the polyvalent amine compound is not less than 20 and not more than 100.
10. The method for producing a polishing composition according to claim 1 , wherein the polyalkyleneimine is polyethyleneimine, polypropyleneimine, or polybutadieneimine.
11. The method for producing a polishing composition according to claim 1 , wherein the pH of the silica particle dispersion is 9 to 11.
12. The method for producing a polishing composition according to claim 1 , wherein in the filtration treatment, a depth filter and/or a pleats filter is used further in combination with the filtration filter.