Properties color

The test methods used by industry to determine if a sample of maleic anhydride is within specifications (165) ate ASTM methods D2930, D1493, and D3366. These methods describe procedures for the determination of maleic acid content, the crystallization point, and the color properties of the maleic anhydride sample, respectively. By quantitative deterrnination of these properties, a calculation of the overall purity of the maleic anhydride sample can be made. 

The other two methods used by industry to examine the purity of maleic anhydride are the crystallization point (168) and color deterrnination of the sample (169). These tests determine the temperature at the point of solidification of the molten sample and the initial color properties of the melt. Furthermore, the color test also determines the color of the sample after a two-hour heat treatment at 140°C. The purpose of these tests is to determine the deviation in properties of the sample from those of pure maleic anhydride. This deviation is taken as an indication of the amount of contaminants in the maleic anhydride sample. 

Color Properties Required. Colorants must be chosen to permit formulation of a coating that can meet performance requirements such as exterior durability and resistance to solvents, chemicals, and heat. Health and safety regulations may also affect colorant choice. 

Properties of Colorants. Properties of a number of colorants are shown ia Tables 5—9. Eor other properties see Refereace 15. Most values are from the Hterature and, ia geaeral, refer to commercial colorants and not pure compounds. The composition of certified colorants can vary substantially with regard to the amounts of pure dye, salt, moisture, subsidiary dyes, trace metals, etc. that they contain, and of course the properties of color additives are affected by their composition. 

These coatings provide the most effective fire-resistant system available but originally were deficient in paint color properties. Since, historically, the intumescence producing chemicals were quite water-soluble, coatings based thereon did not meet the shipping can stability, ease of application, environmental resistance, or aesthetic appeal required of a good protective coating. 

Oliveira, J. et al., Color properties of four cyanidin-pyruvic acid adducts, J. Agric. Food Chem., 54, 6894, 2006. 

Kammerer, D., Carle, R., and Schieber, A., Quantification of anthocyanins in black carrot extracts Daucus camta ssp. sativus var. atrorubens Alef.) and evaluation of their color properties, Eur. Food Res. TechnoL, 219, 479, 2004. 

Caramel color is a result of a complex chemical composition. The color properties are characterized by hue index and tinctorial power, calculated via the following formulas ... 

According to EU purity criteria, color intensity is defined as the absorbance of a 0.1% (w/v) solution of caramel color solids in water in a 1 cm cell at 610 nm. The color intensity must be 0.01 to 0.12 for class I (E 150a), 0.05 to 0.13 for class II (E 150b), 0.08 to 0.36 for class III (E 150c), and 0.10 to 0.60 for class IV (E 150d). Ammonia caramels show the highest tinctorial power and are most commonly used as food colorants. Class I has the weakest coloring properties and is mostly used as flavor. 

Figueiredo, P. et al., Anthocyanin intramolecular interactions a new mathematical approach to account for the remarkable colorant properties of the pigments extracted from Matthiola incana, J. Am. Chem. Soc., 118, 4788, 1996. 

Thousands of polyphenols from fruits (grapes, apples, etc.), vegetables (horse beans), and teas have been identified, many having good coloring properties, especially anthocyanins and some flavonoids. Well-documented reviews discuss the coloring capacities of some polyphenols including procyanidins. - Detailed presentations of anthocyanin and flavonoid properties and analysis are included in Sections 2.3, 4.3, and 6.3. The soluble proanthocyanidins of the colored horse bean Viciafaba L. seed coats were isolated and separated by solvent partition. 

Despite the new orientation toward utilization of natural compounds, synthetic colorants are still used as food additives. Synthetic colorants are easy to produce, stable, less expensive, and have better coloring properties than natural colorants. Still, synthetic colorants are considered to belong to concern level III, a category... 

For preparing lakes, a solution of aluminium sulfate (or chloride) is mixed with sodium carbonate, forming fresh alumina Al(OH)3. The colorant is then added and adsorbed on the surface of alumina. Usually the content of colorant in the lake ranges from 10 to 40%." The product is filtered, washed with water, dried, and milled. The product is allowed to contain unreacted alumina but must not contain more than 0.5% HCl-insoluble matter and not more than 0.2 % ether-extractable matter. - Lakes are insoluble in most solvents used for pure dyes, and they have high opacity and better stability to light and heat. Lakes impart their color by dispersion of solid particles in the food. The coloring properties of lakes depend on particles, crystal structures, concentrations of dye, etc. 

Table 4.3 Color properties of pigments synthesized in two different micro reactors compared with the batch standard [55],...

The ideal composition of Prussian blue is Fe(III)4[Fe(II)(CN)g]3.15H2O. The crystal structure is cubic. All Fe(III) lattice sites are occupied, whereas those of Fe(II) are only 75% occupied. At low temperatures the paramagnetic Fe(III) ions order ferromagnetically (T = 5.6 K). Finally we note that upon replacing Fe(II) by Ru(II) or Os(II) the color properties are not drastically influenced. 

The effect of particle size, and hence dispersion, on the coloring properties of aluminum lake dyes has been studied through quantitative measurement of color in compressed formulations [47], It was found that reduction in the particle size for the input lake material resulted in an increase in color strength, and that particles of submicron size contributed greatly to the observed effects. Analysis of the formulations using the parameters of the 1931 CIE system could only lead to a qualitative estimation of the effects, but use of the 1976 CIEL m v system provided a superior evaluation of the trends. With the latter system, the effects of dispersion on hue, chroma, lightness, and total color differences were quantitatively related to human visual perception. 

Electronic chemicals (see Section 11.4) provide another illustrative example of the difference between fine and specialty chemicals Merck KGaA produces a range of individual fine chemicals as active substances for liqnid crystals in a modern multipurpose plant in Darmstadt, Germany. An example is (trans,trans)-A-[difluoromethoxy)-3,5-difluorophenyl]-4 -propyl-l,l -bicyclohexyl. Merck ships the active ingredients to its secondary plants in Japan, Sonth Korea, and Taiwan, where they are compounded into liquid crystal formulations. These specialties have to comply with stringent use-related specifications (electrical and color properties, etc.) of the Asian producers of consumer electronics such as cellular phones, DVD players, and flat-screen TV sets. 

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