Iron oxide pigments properties

The exceUent adhesion to primed films of polyester combined with good dielectric properties and good surface properties makes the vinyhdene chloride copolymers very suitable as binders for iron oxide pigmented coatings for magnetic tapes (168—170). They perform very weU in audio, video, and computer tapes. 

Since then, these materials have been increasingly supplanted by their synthetic analogues. The latter can be produced in very pure form with extremely consistent properties. Today, natural iron oxide pigments account for only around 20% of world consumption. The main producers of natural iron oxide pigments are France, India, Cyprus, Iran, Italy and Australia (Buxbaum Printzen, 1993). 

The hematite platelets show a predominantly metallic effect. Very thin particles with a thickness of 50 to 400 nm display a pale copper gloss, which is indicative of interference. The shade can be varied and the properties of the platelets can be controlled by doping. A1 or Mn are incorporated by substitution of Fe in the hematite lattice, and Si is incorporated interstitially [5.240]. Laminar iron oxide pigments are interesting because of their excellent fastness to light, outdoor exposure and their good mechanical stability. Main applications up to now are automotive lacquers and cosmetics. 

Fig. 5.13 Particle size and properties of iron oxide pigments based on a a-Fe203 [5.101].

Transparent iron oxides have the same fastness properties as opaque iron oxide pigments, but much higher color strength and significantly higher color purity. Table 5.19 summarizes the properties of selected transparent iron oxide pigments [5.192]. 

Z. Zhang, H. Du, W. Wang and Q. Wang, Property changes of wood-fiber/HDPE composites colored by iron oxide pigments after accelerated UV weathering. J. Forest Res. 21(1),... 

In special applications, it is desirable to increase the hydrophilic properties of fillers and pigments for easy dispersion in water. With polyetherfiinctional silanes, it is possible to obtain, for example, self-dispersing iron oxide pigments [38]. Furthermore, the polyether silanes display a very significant reduction in the viscosity of unsaturated polyester systems [47] when high filler loadings are required. 

The effect of pigment shape on the properties of an industrial latex coating was studied in detail. Two red iron oxide pigments with similar properties were studied - one rhombohedral (produced by precipitation) and the other spheroidal (produced by calcination). They were added in the same volume concentration to the coating formulations and several liquid, dry-film, wet film and free-film properties were determined. 17 refs. 

Synthetic iron oxide pigments are more popular because of their better color purity, consistent properties, and superior tinting strength compared to natimal iron oxide pigments, which is a result of their higher chemical pinity. They are available in red, yellow, brown and black colors. 

Cornell Schwertmann (1996) Cornell, R.M. Schwertmann, U. The Iron Oxides. Structure, Properties, Reactions, Occurrence and Uses New York VCH (1996) CoRNMAN (1986) Cornman, M. Cobalt Yellow (Aureohn) Artists Pigments. A Handbook of their History and Characteristics 1 Feller, R.L. (ed.) National Gallery of Art, Washington CUP (1986) 37-46... 

Iron oxide pigments are low-cost, high-opacity pigments that impart excellent properties to coatings. These pigments are easy to disperse in both water and oil, are alkali- and chemical-resistant, and hence can be utilized... 

Although yellow iron oxide pigments give a series of rather dull colors, they have excellent properties relatively easy to disperse, nonbleeding, good opacity, fine heat resistance, and low cost. Since their chemical and alkali resistance is excellent, they can be used in both water- and solvent-based paints. 

Uses Dispersant for iron oxide pigments, slurry vise, reduction Features General purpose keeps hydrophilic particles dispersed in aq. systems Properties Colorless to straw cl. liq. m.w. 3500 vise. 375 mPa S pH 8 (10%) Narlex LD 41 [Akzo Nobel Surf Chem.j Chem. Descrip. Sodium salt of a polyacrylic acid homopolymer, aq. sol n. 

Uses Emollient for cosmetics and toiletries, creams, lotions, anhyd. oils imparts smooth spreading chars. wetting agent for iron oxide pigments for liq. makeup, pressed powds., makeup removers min. oil replacement Regulatory Approved in US, EC, Japan, Australia, Canada, Mexico, etc. Properties Yel. liq., typ. odor sol. 5% in peanut oil, min. oil, 95% ethanol, IPM, oleyl alcohol insol. in water, glycerin, propylene glycol acid no. 2 max. iodine no. 45-60 sapon. no. 130-145 ref. index 1.454 100% act. 

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