Yellow iron oxide pigments

Abstract

The present invention relates to improved yellow iron oxide pigments and to their use.

1 . Yellow iron oxide pigment having
 an oil absorption value <25 and either   an a* value of >4.3 measured by CIELAB units in white reduction in L64 to DIN 6174 and/or a b* value of >34 measured by CIELAB units in white reduction L64 to DIN 6174 or   an a* value >10 measured by CIELAB units in full shade to DIN 6174 and/or a b* value of >45 measured by CIELAB units in full shade to DIN 6174,   
       and a reduction ratio for standard depth of shade B 1/9 to DIN 53235 Part 1 and 2 of >−6.5. 
     
     
         2 . Yellow iron oxide pigment according to  claim 1 , wherein the yellow iron oxide pigment has a dispersibility to EN 21524/DIN ISO 1524 (2002) in the extended “3-box method” form of better than 30-50-70. 
     
     
         3 . Yellow iron oxide pigment according to  claim 1 , wherein the yellow iron oxide pigment has a water absorption value <50. 
     
     
         4 . Yellow iron oxide pigment according to  claim 1 , wherein the yellow iron oxide pigment has a BET >14. 
     
     
         5 . Yellow iron oxide pigment according to  claim 1 , wherein the yellow iron oxide pigment has a bulk density >0.4. 
     
     
         6 . Yellow iron oxide pigment according to  claim 1 , wherein the yellow iron oxide pigment has a tamped density >0.7. 
     
     
         7 . Yellow iron oxide pigment according to  claim 1 , wherein the yellow iron oxide pigment has a viscosity in MAP <−25 against Bayferrox® 3910. 
     
     
         8 . Process of using the yellow iron oxide pigment according to  claim 1 , wherein the yellow iron oxide pigment is mixed with organic or inorganic dispersions, products of the ink, paint, coating, building-material, plastics and paper industries, foods or products of the pharmaceutical industry such as tablets.