Opaque pigments

Two blue pigments can be prepared in transparent form cyanide iron blue and cobalt aluminum blue. These pigments are used in achieving a blue shade of the metal effect pigments in metallic paints. Transparent cyanide iron blue is prepared by a precipitation reaction similar to the one used for the preparation of the opaque pigment, but considerably lower concentrations of solutions are used. It is produced by Degussa (Germany), Manox (U.K), and Dainichiseika (Japan). 

A number of diarylide yellow pigments are also available in the form of very opaque products with small specific surface areas. These are used to an appreciable extent in Chrome Yellow free paints, in packaging printing inks, and other media. Fastness to light and weather are much improved in opaque varieties, compared to the corresponding transparent types their rheological characteristics are superior. Opaque pigments are not resinated. 

P.Br.42 affords somewhat dull, yellowish shades of brown in industrial finishes, such as alkyd melamine resin systems. The coating shows a certain opacity, the pigment, however, is recommended to be used in metallics and as opaque pigment as well. 

Opacity At typical colorant loadings. At low loadings, many opaque pigments will appear translucent. 

Grade II Dot-like, opaque pigment stellate pattern forms. 

In the case of reflective or opaque pigment particles, the screening effect can be made very effective, especially when very finely divided... 

Due to their own color these aluminum pigments offer unique styling possibilities. The best effects are achieved in combination with dark colorants including black at a colored aluminum pigment level of 1.5%. In general, it is recommended to combine aluminum pigments with transparent colorants because opaque pigments will hide the metallic effect. 

Add a peariescent pigment to the product, in very small percentages (0.2% to 0.5%), with opaque pigments, for example Ti02, to cover up the pearl effect. This has no negative effect on the laser marking result. 

In the co-extrusion of multilayer films, opaque pigments in the outer layers provide not only aesthetics but also an opportunity to conceal off-color recycled material used in the inner layers. 

Resistance to photooxidative degradation can be improved by incorporating UV absorbers or opaque pigments into the polymer film. 

Ultraviolet stability for outdoor use can be improved by opaque pigments that reflect the UV light before it can penetrate the polymer titanium dioxide and aluminum flake are frequently used for this purpose. Ultraviolet absorbers (UVAs) such as hydroxybenzotriaz-oles and hydroxybenzophenones are sometimes used, and hindered amine light stabilizers (HALS) are becoming more popular. 

When white light shines on a plastic material, it may be absorbed, reflected, and/or transmitted. Absorption removes certain wavelengths those that remain are the color we see. Opaque pigments, insoluble in the polymer, reflect an opaque color to the eye. Transparent organic dyes, soluble in the polymer, transmit a see-through color to the eye. 

Titanium dioxide is used in tremendous tonnage (270 million pounds per year) both as opaque pigment and as white colorant in plastics. This is 90 percent of the inorganic... 

Transparent painting n. Painting with transparent pigments as opposed to opaque ones, e.g., glazing, water color painting. Transparent pigment is converted to opaque pigment by the addition of white. 

Opacity is particularly important in thin-section applications, where a highly opaque pigment can serve well, even at a lower concentration. In thicker sections it may be less important - but it is as well to remember the other side of the coin lower concentrations of Ti02 pigment may detract from durability. 

Opaque pigments can have a valuable screening effect if incorporated into a plastic and can help to confine the photodegradation to the extrane surface layers, thus protecting the inner part of the plastic. The most effective of such pigments is carbon black. However, some care must be exercised in the choice of the grade of carbon black and its concentration to ensure maximum protection while avoiding side effects in other polymer characteristics. 

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