A comparison between the straight lines which were found for the different printing inks shows that the flow limits of the SiO2 -containing pigment compositions c and d and the thus-made printing inks are distinctly lower in spite of higher viscosity than the printing inks which were made with the oxide-free pigment and had a lower viscosity,mobile coal crusher. The following table shows the shear stress (dyn/cm2) of the various flow limits of the tested printing inks: When comparing conventional and castor oil-wetted pigments, it was found that in case of the wetting with castor oil the density increase or volume decrease took place substantially more rapidly than in case of the conventional wetting with mineral oil.
With prints of printing inks containing Milori blue VC 705 E, the following degrees of gloss were found: Composition e: Pre-wetted with 10 percent mineral oil (sold under the designation PKWF 4/7 by the Haltermann Company of Germany) 51-53% Composition f:stone crushing process. After wetting with 9 percent castor oil and including 1 percent of a pyrogenic silicic acid (sold under the tradename "Aerosil 200" by the Degussa Corporation of Germany) 57-60%
As FIG. 4 shows, the flow limit is substantially lower in a printing ink made with a pigment that has been wetted with castor oil and this in spite of the increase of the viscosity. This confirms the better dispersibility and wetting action of the pigment in case of castor oil. This example concerns the effects of the addition of an SiO2 /A12 O3 co-coagulate to a carbon black pigment composition containing a liquid wetting agent in regard to color depth and color brightness of printing inks. The carbon black pigment employed was a product made by the German so-called gas-carbon black process and sold under the trademark "Printex U" by the Degussa Corporation of Germany. This product has the following specifications.
With prints of printing inks containing Milori blue VC 705 E, the following degrees of gloss were found: Composition e: Pre-wetted with 10 percent mineral oil (sold under the designation PKWF 4/7 by the Haltermann Company of Germany) 51-53% Composition f:stone crushing process. After wetting with 9 percent castor oil and including 1 percent of a pyrogenic silicic acid (sold under the tradename "Aerosil 200" by the Degussa Corporation of Germany) 57-60%
As FIG. 4 shows, the flow limit is substantially lower in a printing ink made with a pigment that has been wetted with castor oil and this in spite of the increase of the viscosity. This confirms the better dispersibility and wetting action of the pigment in case of castor oil. This example concerns the effects of the addition of an SiO2 /A12 O3 co-coagulate to a carbon black pigment composition containing a liquid wetting agent in regard to color depth and color brightness of printing inks. The carbon black pigment employed was a product made by the German so-called gas-carbon black process and sold under the trademark "Printex U" by the Degussa Corporation of Germany. This product has the following specifications.
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