Iron oxide yellow pigments having a low silking effect and a process for production thereof
Patent 4620879 Issued on November 4, 1986. Estimated Expiration Date: 
July 11, 2004. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
July 11, 2004. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 2388659 3867516 3918985 Yellow pigments stable at high temperatures Preparation of improved heat stable yellow iron oxide pigments Heat resistant yellow iron oxide pigment Yellow iron oxide pigment and method for manufacture thereof Patent #: 4459276 InventorsApplicationNo. 06/629654 filed on 07/11/1984US Classes:106/432, Lead compound containing, e.g., litharge, etc. (Pb)106/435, Silicon containing106/456, Iron compound containing (Fe)106/457, Silicon containing, e.g., slag, turkey umber, Fullers earth, etc.106/459With other metal compoundExaminersPrimary: Lieberman, PaulAssistant: Thompson, Willie J. Attorney, Agent or FirmInternational ClassesC01G 49/06 (20060101)C01G 49/02 (20060101) C09C 1/22 (20060101) C09C 1/24 (20060101) Foreign Application Priority Data1983-07-23 DEAbstractIron oxide yellow pigments having a silking effect ƊE1 *, less than or equal to 0.5, and having color values which range for L* from 52-63, for a* from 8 to 14 and for b* from 40 to 48 CIELAB units are produced by a process by first, forming needle-shaped -FeOOH yellow pigment nuclei in the presence of compounds containing the elements B, Al, Ga, Si, Ge, Sn or Pb present in a quantity of from 0.05 to 10% by weight, where the quantity is calculated as the tri- or tetra-valent oxides of the compounds and based on the -FeOOH which is precipitated during nucleation, and second, growing iron oxide yellow pigments on the thus formed iron oxide yellow nuclei.Other References
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