Titanium dioxide dispersibility

A method of producing a titanium dioxide product comprising the steps of:

• (a) forming a mixture comprising a titanium dioxide material in an aqueous medium, wherein said titanium dioxide material comprises titanium dioxide, said titanium dioxide material further comprises an amount of alumina in the range of from about 0.05 parts to about 10 parts by weight per 100 parts by weight of said titanium dioxide present in said titanium dioxide material, said titanium dioxide material is an agglomerated, pigmentary titanium dioxide material which has been produced from titanium tetrachloride using a vapor phase oxidation process, said alumina was formed along with said titanium dioxide in said vapor phase oxidation process, and, other than said alumina and any other inorganic oxides formed in said vapor phase oxidation process along with said titanium dioxide, substantially no inorganic oxides have been deposited on said titanium dioxide material;
• (b) wet milling said agglomerated, pigmentary titanium dioxide material in said aqueous medium such that at least 30% by weight but no more than 70% by weight of said wet milled titanium dioxide material has a particle size smaller than 0.5 micron;
• (c) after step (b), reducing the pH of said mixture to a value not exceeding 4.0;
• (d) after step (c), increasing the pH of said mixture to a value in the range of from about 5 to about 8 such that said titanium dioxide material flocculates;
• (e) after step (d), removing said titanium dioxide material from said mixture;
• and
• (f) after step (d), washing said titanium dioxide material,
• wherein, other than any redeposited inorganic oxides originally formed along with said titanium dioxide in said vapor phase oxidation process, substantially no inorganic oxides are deposited during said method on said titanium dioxide material.

A process for producing a plastic product comprising the step of dispersing a titanium dioxide product in a plastic material to form a plastic composition, said titanium dioxide product having been produced by a titanium dioxide production method comprising the steps of:

• (a) forming a mixture comprising a titanium dioxide material in a liquid medium, said titanium dioxide material being an agglomerated titanium dioxide material which has been produced by a reaction process and wherein, other than any inorganic oxides formed in said reaction process along with said titanium dioxide material, substantially no inorganic oxides have been deposited on said titanium dioxide material;
• (b) wet milling said agglomerated titanium dioxide material in said liquid medium;
• (c) after step (b), reducing the pH of said mixture to a value not exceeding 4.0;
• (d) after step (c), adding an effective amount of a base to said mixture to cause said titanium dioxide material to flocculate;
• (e) after step (d), removing said titanium dioxide material from said mixture;
• and
• (f) after step (d), washing said titanium dioxide material,
• wherein, other than any redeposited inorganic oxides originally formed in said reaction process along with said titanium dioxide material, substantially no inorganic oxides are deposited during said titanium dioxide production method on said titanium dioxide material.