Surface of pigments

Pigments Aftertreatments. The surfaces of pigment particles can have different properties and composition than the particle centers. This disparity can be caused by the absorption of ions during wet milling, eg, the —OH groups, on the surface. In some cases, surfaces are modified intentionaHy to improve the pigments appHcation properties, interaction with the organic matrix, and weather resistance. 

Use of pigmented coatings (e.g. oil and emulsion paints, synthetic resin-based plaster) They leave dry surfaces of pigmented films, the permeability of which to water and water vapour will depend upon the amount of synthetic resin present They clog the pores... 

K 5. Konifi, O., Z. Pelzbauer, and F. KaSpar Estimation of particle size, of its distribution and the specific surface of pigments for the formulation of paints. Chem. prftmyd 10, 274 (1960). 

The particle surface of pigment Ti02 was treated with the oxides of aluminium, silicon and zirconium, and the surface of pigment Fe203 - with aluminium and silicon oxides. Pure phthalocyanine pigment - p-CuPc was used in the work. 

The evidence of the polymer adsorption on the surface of pigment particles and the formation of protective layers has been obtained by ESA method by experiments on measuring the -potential of the TiC>2 surface in aqueous dispersions in the presence of EFIEC (Table 2). It can be seen from the table that -potential becomes less negative in the presence of EHEC and still more approaches zero as a result of the treatment of dispersions in an ultrasonic field. This indicates the activation of polymer adsorption and the formation of stabilizing layers due to mechanochemical modification of particles. From the table it is also seen that as a consequence of mechanochemical treatment, the size of pigment particles in dispersions decreases, and dispersion becomes structurally more uniform, which leads to an increase of its stability even at increased temperature (experiment 4). 

Additional evidences of the intensification of the polymer adsorption on the surface of pigment particles as a result of ultrasonic treatment, which were obtained using spectral techniques of analysis, have been published earlier [7],... 

Organic pigments commonly used for the coloration of polypropylene fibres exhibit nucleating ability toward polypropylene crystallisation. The rough surface of pigments ... 

The properties of the surface of pigment particles are commonly controlled in industrial products by the use of additives that attach to the surfaces and modify the surface character. The use of tailor-made additives to enhance specific aspects of application performance, traditionally on the basis of trial and error experimentation, has been extensively investigated and many such additives are now commonly used. The molecular structures of the additives may be... 

As with almost all other resin classes, work has been done to make alkyd resins for coatings that can be reduced with water. One approach that has been more extensively studied in Europe than in the United States is the use of alkyd emulsions (25,26). The emulsions are stabilized with surfactants and can be prepared with little, if any, volatile solvent. Some problems limit use of alkyd emulsions (27). Coatings prepared using alkyd emulsion loose dry time on storage because of absorption of cobalt drier on the surface of pigments and precipitation of cobalt hydroxide. Best results were obtained with a combination of cobalt neodecanoate... 

Autoradiographic studies with l-labeled holo-RBP have provided data that have been interpreted as showing the presence of binding sites for RBP on the surface of pigment epithelial cells. These studies were carried out both in vivo (injecting rats with holo-RBP Bok and Heller, 1976) and in vitro... 

The quality of a pigment is also determined by the size distribution of the particles since pigment must fill all the interstices. In the case of a broad distribution, the presence of a little quantity of particles smaller than 500 nm does not affect the uniformity of coloring, but a distribution too close to the colloidal domain results in the formation of spots [12]. The surface of pigment particles affects also rheological properties of suspensions or plastisols [13]. 

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