Stability of pigments

Escribano-Bailon, T. et al.. Color and stability of pigments derived from the acetaldehyde-mediated condensation between malvidin 3-O-glucoside and (-t-)-catechin, J. Agric. Food Chem., 49, 1213, 2001. 

Stabilization of Pigmented Polypropylene With Zinc Salts... 

The specific requirements for organic pigments in terms of heat stability result from the temperature levels at which individual polyolefins are processed. Standards have been developed to test the heat stability of pigments in polyolefins [33] (see also Sec. 1.6.7). 

Dry spinning. The polymer, dissolved in a suitable solvent and filtered, is pressed through spinnerettes and, in an oxygen-free atmosphere, pulled by vacuum through a heated shaft, where the polymer solidifies as the solvent evaporates. The requirements of this process regarding the heat stability of pigments are much less... 

The photochemical properties of titania surfaces are of interest for several reasons. They determine the stability of pigmented paint systems [76], the rate at which pollutants can be degraded in systems designed to purify air and water [77], and are the root cause of poorly understood phenomena such as water photolysis [78] and super hydrophilicity [79]. Using thin rutile epilayers with five low index orientations, it has been shown that the relative rates of photochemical reactions catalyzed by titania depend on the surface orientation [80]. In this chapter, experiments used to map the complete orientation dependence of the relative photochemical reactivity of TiO are described [81-83]. In this case, the relevant reactions are carried out at room temperature and this gives us the opportunity to fix both the surface morphological structure and stoichiometry. For the reactions described here, all of the surfaces were... 

The adsorbed polymer sterically stabilizes particles of 1 in polymer solution, resulting in a stable squaraine-polymer dispersion Analogous steric stabilization of pigment particles via specific... 

Numerous articles of a general interest have appeared on photocatalytic chemistry. These include nanoparticles, protection of buildings, antibacterial properties, ageing of pigment blends, modified titanium dioxides, photocatalytic paints, stabilization of pigmented systems, sensitization of acid dyes " and clay masterbatches. Anatase has been found to have a detri-... 

Thus, the stability of aqueous dispersions of CuPc depends on the efficiency of the stabilizer adsorption on its surface. Treatment in an ultrasonic field allows to increase the efficiency of the stabilizer adsorption and therefore to increase the stability of pigment dispersions. 

As a rule, pigments can easily be dispersed in water-soluble binders because the water-soluble binder molecules promote wetting and stabilization of the pigments. The dispersion and stabilization of pigments in polymer dispersions is, however, more difficult because the dispersions form a continuous phase in water and uniform distribution of the dispersed pigment particles in the paint film is hindered by coalescence of the polymer particles. To overcome such problems new dispersion additives have been developed in recent years. 

Some of the following conclusions were drawn in an excellent review and current knowledge of the influence of pigments on the light stability of pigments [144] ... 

Another complicating factor is that optimized electrostatic stabilization of pigment particles in water-based formulations may lead to sub-optimization when... 

Isostearic acid is used in applications which require thermal stability in the case of a lubricant, odor stability for a cosmetic formulation, and oxidation stability for products with long shelf-life requirements. The branched structure of isostearic acid also enhances its dispersing power, and it is used in cosmetic and industrial applications for the stabilization of pigments and mineral particles in oils and solvents. 

This area has recently been extensively investigated by flow adsorption microcalorimetry, mostly in respect of the strength of adsorption of surfactants and resins on the surfaces of the above materials and the effect on the stability of pigment dispersion and adhesion properties as a function of the surface chemistry of solids. A major contribution in this field has been made by the late Prof. F. Fowkes whose work was recently summarised by D. P. Ashton and D. Briggs [30],... 

Finally, there are a number of applications where resistance to both heat and light is required, and it is necessary to study the influence of UV stabilisers on the heat stability of pigmented PP. 

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