Heat stability, of pigments

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... 

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. 

Table 4 Relation between the heat stability of azo pigments in an alkyd-melamine resin baked system, their fastness to overpainting in this paint system, and their bleed resistance in plasticized PVC.

P.O.72 is as well suitable for the application in polystyrene and ABS. Colorations of PS in 1/3 SD, requiring only 0.15% pigment, exhibit a heat stability of 280°C, colorations of ABS are stable up to 290°C. In these media the lightfastness equals step 8 on the Blue Scale. Pigment concentration of less than 0.1% in poly-oxymethylen (POM, polyacetales) may lead to coating of the manufacturing equipment (see plate out, Sec. 1.6.4.1). 

P.R.190 has a relatively small impact on the market. It is a specialty product for industrial paints, especially for automotive finishes, but offers no advantage over other members of its class. Its shade is dull and referred to as scarlet. In white reductions, the commercial type is very bluish and equally dull. The particle sizes of this product are too coarse for it to be used in metallic finishes. P.R.190 is very durable and very fast to organic solvents and to migration. The pigment is heat stable up to processing temperatures of 200°C. Despite its good heat stability, the pigment possesses only limited commercial value as a colorant for plastics. 

The heat stability of P.O.73 is good, but deteriorates somewhat in white reductions. The pigment exhibits good weatherfastness, but performs poorer in this respect than P.R.254 and P.R.264. 

P.Y.193 is tinctorially equal weak in plastics. Colorations of HDPE in 1/3 SD (1% TiOz) require 0.43% pigment, the heat stability of the colorations reaches 300°C. 

Heat stability -of inorganic pigments [PIGMENTS - INORGANIC] (Vol 19)... 

Aw Condensation Pigments. A further improvement in heat stability of azo pigments was achieved by the condensation disazo pigments due to an enlarged molecular framework and higher molecular weight. Formally they are composed of two monoazo or more accurately two monohydrazone units, which are attached to each other by an aromatic dicarbonamide bridge. 

The moderate lightfastness and poor exterior durability in conjunction with a moderate, short dwell time and heat stability of 500°F (240°C) are the major factors restricting the more widespread use of this pigment. 

There is a lot of competition among plastics manufacturers for car interior components although, however, this area is not expected to show much growth [26,27]. ABS plastics continue to dominate the instrument panel market, while newer materials like Dow Chemical s pulse PC/ABS and Bayer s Bayblend PC/ABS alloys have been introduced for use in dashboard housings, interior mirror surrounds, and steering column covers. The alloy s high heat stability allows pigmentation in pastel colors. 

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