Green pigment soluble dyes

Dyes can be used to obtain transparent colours in polyester resins. Considerable care in their selection needs to be taken as most will quickly fade on the addition of catalyst to the liquid resin or on exposure of the cured resin outdoors. However, certain quinone-type aromatic-soluble dyes in the yellow-red range are extremely lightfast and transparent blues and greens can be satisfactorily produced using small quantities of the corresponding phthalocyanine pigments. 

Chlorophyll. Chemically pure chlorophyll is difficult to prepare, since it occurs mixed with other colored substances such as carotenoids. Commercially it is solvent extracted from the dried leaves of various plants such as broccoli or spinach. Chlorophyll is water-iosoluble. It has none of the characteristics of a dye in that it has no aflinity for the usual libers such as cotton or wool. Chlorophyll is properly classified as a pigment tCI Natural Green 3 Cl 75810), As such. It finds use lor coloring soaps, waxes, inks. fats, or nils. Chlorophyll is an ester composed of an acidic pint, chlorophyllin, esterilied by an aliphatic alcohol known as phylol. Hydrolysis of chlorophyll using sodium hydroxide produces the moderately water-soluble sodium salts of chlorophyllin. phytol. and methanol. The magnesium in chlorophyllin may be replaced by copper. The sodium copper chlorophyllin salt is heat-stable, and is ideal for coloring foods where heat is involved, such as in canning. 

Basic dyes are water-soluble in the form of their salts and are used for colouring paper, leather, cellulose- and polyacrylonitrile fibres. The free bases dissolve in many organic solvents and find application similar to that of the solvent dyes. Basic dyes can function as pigments in lacquer form. Mixtures of basic dyes are usually responsible for brown, green and black tones. 

Copper phthalocyanine 67 is an important example of a group of blue to green organic pigments. Phthalocyanines may be made water soluble by sulfonation, and the soluble phthalocyanine sulfates are important as direct dyes in the dyestuffs industry. 

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