专利类型:  发明专利
申请号:  EP13168620
申请日期:  2013-05-21
公开号:  EP2740770B1
公开日期:  2016-09-14
申请人:  NAT TITANIUM DIOXIDE CO LTD CRISTAL
发明人:  VAKAYIL AHMED YASIR;JOMHA AHMED J
地址:  
摘要:  A method is provided for the wet surface treatment of titanium dioxide, in order to produce durable universal grade titanium dioxide rutile pigment with superior optical properties. The method is characterized in that, a hydrous zirconia and silica composite layer is co-precipitated at acidic pH. Then, a layer of alumina is precipitated under a range of pH required for complete precipitation above the initial composite layer. The upper pH limit of the slurry during the alumina precipitation can be well controlled to avoid any chance for dissolution or damage of the composite zirconia-silica layer formed. Zirconia-silica composite layers and alumina thus precipitated advantageously improve the competence of the layers formed over a TiO2 base and provide improved durability with superior optical performance. The total surface treatment cycle time and chemicals used are minimal compared to conventional methods. Improvements in throughput and washing efficiency are also realized.
主权项:  A method for post treatment of titanium dioxide pigment particles comprising, in sequence: a) preparing an aqueous slurry of titanium dioxide pigment core particles with a pH value of about 4.0 to about 6.0, b) adding to the aqueous slurry of titanium dioxide pigment core particles a sufficient quantity of water soluble compounds of zirconia and silica, in sequence, to co-precipitate hydrous zirconia-silica as a composite layer on the core particles, at an acidic pH and without any pH adjustment, to form a mixture, c) digesting the mixture for about 10 to about 30 minutes to complete the precipitation and form a suspension, d) adding a sufficient quantity of water soluble alkaline alumina compound to the suspension in a single step, without any pH adjustment, to form a resulting slurry, e) adjusting the pH of the resulting slurry, if needed, to achieve a pH from about 8.0 to about 8.5 and form a resultant mixture, f) digesting the resultant mixture for about 10 to about 30 minutes to complete the precipitation of hydrous alumina and form a second suspension comprising treated pigment, g) adjusting the pH of the second suspension, if needed, to achieve a pH value of from about 6.0 to about 8.0, h) filtering the second suspension, and i) drying the treated pigment.
专利分类号:  B05D1/18;C09D7/12;C09C1/36
专利状态:  有效专利
代理人:  
代理机构:  Serjeants
国家及地区:  
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