Dispersion of Organic Pigments with Modern Dispersion Equipment

Abstract

A previous paper had shown that milling organic pigments at elevated temperatures often improves colour development through better wetting. The present investigation shows that heat can, nevertheless, have an overall adverse effect on colour strength and hue of pigments which partially dissolve (and subsequently recrystallise) in a vehicle system under the combined action of heat and impact. Likewise, metastable polymorphic pigments should be dispersed at the lowest possible temperature to minimise hue shifts and/or loss of colour strength.

Assessment of the factors affecting the weathering properties of Pigment Yellow 74 in decorative paint

“…The dispersions processed at high temperature (without cooling water circulation) might have lost their stability/crystal structure and hence the inferior ATLAS and QUV performance. It is known that certain organic pigments are sensitive to high temperature and impact during grinding results in inferior color strength 15 . The trend of the data shown in Figure 10 is quite similar to the trend of Figure 8 in terms of increase in difference of Δ E as a function of ATLAS and QUV exposure time.…”

Laser diffraction measurements of pigment size distributions of coatings and mill bases: implications of dilution medium and dispersion process parameters

“…However, the grind gauge does not provide information on how the average diameter and the entire particle size distribution (PSD) develop during the dispersion process. An optimal average particle size and PSD improve coating properties, such as color strength, transparency, and hiding power [18][19][20][21]55], and more details of the PSD allow for the design of better products. Consequently, a more informative and reliable method, focusing on the entire PSD and average particle size, is needed for fast industrial quality control.…”

Three-Dimensional Characterization of Pigment Dispersion in Dried Paint Films Using Focused Ion Beam–Scanning Electron Microscopy

“…(For a 2D system, e.g., a cross-section image, the sheets are reduced to lines and the volumes are reduced to areas.) The efficiency of light scattering is dependent on the quality of the dispersion of the pigment in the binder (Herbst, 1973; Auger et al, 2009), where “quality of dispersion” is the tendency toward uniform pigment particle sizes/shapes as well as uniform spatial distribution. Narrower distributions of binder sheet thickness and binder cluster diameter represent more-uniform dispersion of the binder.…”

“…The dispersion of inorganic pigments during paint production is a well-known issue in the coatings industry (Herbst, 1973; Patton, 1979). Since the hiding power, texture, and color of dried paint films are greatly affected by the dispersion of pigments, a more uniform distribution can enhance both the color and texture of paints while reducing the use of pigment material.…”