Packaging pigments

Film or sheet generally function as supports for other materials, as barriers or covers such as packaging, as insulation, or as materials of constmction. The uses depend on the unique combination of properties of the specific resins or plastic materials chosen. When multilayer films or sheets are made, the product properties can be varied to meet almost any need. Further modification of properties can be achieved by use of such additives or modifiers as plasticizers (qv), antistatic agents (qv), fire retardants, sHp agents, uv and thermal stabilizers, dyes (qv) or pigments (qv), and biodegradable activators. 

The FD C certified colors are all water-soluble dyes, but can be transformed into insoluble pigments known as lakes by precipitating the dyes with alurninum, calcium, or magnesium salts on a substrate of aluminum hydroxide. The lakes are useful in appHcations that require color whereas in dry form, such as cake mixes, or where water may be present and bleeding is a problem, such as food packaging. FD C Red Lake No. 3 was deHsted in Febmary... 

Black Pigments. The only black pigment used to an appreciable extent in inks is carbon black It is used in newsprinting, pubHcation, commercial and packaging printing therefore, in large quantities. Black pigments ate offered in fluffy or beaded forms and in a variety of particle sizes and physical properties. 

Purple Pigments. Methyl violet is the most commonly used purple pigment. It is also widely used for toning black inks. In packaging, although very expensive, Carbazole and Vat violets are used where permanence and resistance properties are needed. 

During storage, natural pigments often deteriorate with time because of exposure to light, heat, air, and moisture or because of interaction of the components of the food with each other or with the packaging material. The color of maraschino cherries, for example, fares so poorly with storage that they are routinely bleached then artificially colored. 

The two most important pieces of chemical control legislation enacted affecting the dye and pigment industries are the United States Toxic Substance Control Act (TSCA) and EEC s Classification, Packaging, and Labeling of Dangerous Substances and its amendments. Table 2 is a comparison of TSCA and the 6th Amendment of the EEC classifications. 

This type of pigment is the precipitate formed when molybdic oxide is dissolved in aqueous sodium hydroxide with the addition of sodium chromate. The resulting mixture is reacted with a solution of lead nitrate. The precipitate formed is further processed through filtration, washing, drying, milling, and packaging. 

Polyvinyl chloride resin, because of its inherent thermal instability and wide range of applications, requires us to develop additive recipes based on specific application and processing requirements. Typical additive packages include stabilizers, plasticizers, waxes, processing aids, pigments, and mineral additives. 

Colorants have been developed for special effects. Pearlescent or iridescent give an attractive appearance. They are often used for coating paper (e.g., cosmetic packaging). The pigment consists of thin platelets, less than 1 pm thickness, which have a high refractive index, e.g., mica coated with Ti02. 

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