Dispersion color compounding

In some instances, additional functions are the attraction of pollinating or seed-dispersing animals, for example, by colored compounds such as betalains (within the Centrospermae), anthocyanins, carotenoids, and flavonoids or by fragrances such as terpenes, amines, and aldehydes 15,17). Physiological roles, such as UV protection [by fiavonoids or cou-marins 4,17)], nitrogen transport or storage 14,36,37), or photosynthesis (carotenoids), may be an additional function. 

As the versatile applicability of these compounds increased, more manufacturers began to make them, with the resulting multitude of trade names. The tetrasodium salt of ethylenediaminetetraacetic acid appears to be the most versatile complexing agent, with one mole reacting with one mole of a divalent metal ion. It is used in scouring textile material, in preparation of print pastes, in dyeing with disperse colors when hard water is used in the process, etc. 

Suspensions of polyacetylene were prepared as burrs or fibers (46) by using a vanadium catalyst. When the solvent was removed, films of polyacetylene were formed with densities greater than that prepared by the Shirakawa method. These suspensions were mixed with various fillers to yield composite materials. Coatings were prepared by similar techniques. Blends of polypyrrole, polyacetylene, and phthalocyanines with thermoplastics were prepared (47) by using the compounding techniques typically used to disperse colorants and stabilizers in conventional thermoplastics. Materials with useful antistatic properties were obtained with conductivities from 10" to 10" S/cm. The blends were transparent and had colors characteristic of the conducting polymer. For example, plaques containing frans-polyacetylene had the characteristic violet color exhibited by thin films of solid trans-polyacetylene. 

The recent acquisition of Colortech by PPM, a German color compounder, presented an opportunity to eonduet a direct comparison of thermo-kinetic and conventional twin screw compounding technologies. The goal was to run identical color concentrate formulations on commercial scale processing equipment operated by individuals skilled in the art. Primary performance criteria were to include dispersion quality and color strength. Secondary characteristics such as melt index, ash content and product density were also evaluated. 

Color Concentrate (Masterbatch). Expert compounders disperse colorants at 20 to 60 percent concentration in a carrier polymer, using high shear to break down agglomerates and produce uniform dispersion of maximum coloring efficiency. This color concentrate is used by processors, simply blending it with virgin (natural color) resin ( letdown with natural ). Typical ratios of concentrate/natural are 1/20 to 1/100. This technique is low in cosL does not create inventory problems, and is most commonly used with commodity resins. 

To assist dispersion of colorant in the polymer melt the use of screw back pressure is recommended. The barrel temperatures at the hopper zone should be set lower than that at the nozzle to allow for additional mixing to take place within the feed section of the screw. PS is also sold as color compounded material and a color matching service is available but many processors purchase natural (clear) polymer and color in-house. 

To form a colored compound in a spot test with a paint film, lead ions must be leached or separated from the lead-containing species. Dissolution of lead ions depends on the type, concentration, and dispersion of lead-containing compounds in the film and the binder, and the position of the lead-containing layer(s) in the composite film. Lead pigments used in relatively high concentrations provide hiding or control corrosion and in lower concentrations, they provide color in still lower concentrations, they facilitate drying. 

Product COSAN 91 is a liquid organic compound which is water soluble and recommended for use as an industrial preservative against bacterial deterioration in water-based systems such as resin emulsions, adhesives, dispersed colors, and ready-mixed joint cements. 

Nickel also has been used as a dye site in polyolefin polymers, particularly fibers. When a nickel compound, eg, the stearate or bis(p-alkylphenol) monosulfide, is incorporated in the polyolefin melt which is subsequently extmded and processed as a fiber, it complexes with certain dyes upon solution treatment to yield bright fast-colored fibers which are useful in carpeting and other appHcations (189). Nickel stearate complexing of disperse mordant dyes has been studied (190). 

Carotenoids are also present in animal products such as eggs, lobsters, greyflsh, and various types of hsh. In higher plants, they occur in photosynthetic tissues and choloroplasts where their color is masked by that of the more predominant green chlorophyll. The best known are P-carotene and lycopene but others are also used as food colorants a-carotene, y-carotene, bixin, norbixin, capsanthin, lycopene, and P-apo-8 -carotenal, the ethyl ester of P-apo-8-carotenic acid. These are Upid-soluble compounds, but the chemical industry manufactures water-dispersible preparations by formulating coUoid suspensions by emulsifying the carotenoids or by dispersing them in appropriate colloids. ... 

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