Presidential Green Chemistry Challenge: 2004 Designing Greener Chemicals Award
Engelhard Corporation (now BASF Corporation)
Engelhard RightfitTM Organic Pigments: Environmental Impact, Performance, and Value
Innovation and Benefits: RightfitTM azo pigments contain calcium, strontium, or barium; they replace conventional heavy-metal-based pigments containing lead, hexavalent chromium, or cadmium. Because of their low potential toxicity and very low migration, most of the RightfitTM azo pigments have received U.S. Food and Drug Administration (FDA) and Canadian Health Protection Branch (HPB) approval for indirect food contact applications. By 2004, Engelhard expects to have replaced all 6.5 million pounds of its heavy-metal-based pigments with RightfitTM pigments.
Summary of Technology: Historically, pigments based on lead, chromium(VI), and cadmium have served the red, orange, and yellow color market. When the U.S. EPA began regulating heavy metals, however, color formulators typically turned to high-performance organic pigments to replace heavy-metal-based pigments. Although high-performance pigments meet performance requirements, they do so at the expense of the following: (1) their higher cost often acts as a deterrent to reformulation; (2) their production uses large volumes of organic solvents; (3) some require large quantities of polyphosphoric acid, resulting in phosphates in the effluent; and (4) some are based on dichlorobenzidine or polychlorinated phenyls.
Engelhard has developed a wide range of environmentally friendly RightfitTM azo pigments that contain calcium, strontium, or sometimes barium instead of heavy metals. True to their name, the RightfitTM pigments have the right environmental impact, right color space, right performance characteristics, and right cost-to-performance value. Since 1995, when Engelhard produced 6.5 million pounds of pigments containing heavy metals, it has been transitioning to RightfitTM azo pigments. In 2002, Engelhard produced only 1.2 million pounds of heavy-metal pigments; they expect to phase them out completely in 2004.
RightfitTM pigments eliminate the risk to human health and the environment from exposure to heavy metals such as cadmium, chromium(VI), and lead used in the manufacture of cadmium and chrome yellow pigments. They are expected to have very low potential toxicity based on toxicity studies, physical properties, and structural similarities to many widely used food colorants. Because they have low potential toxicity and very low migration, most of the RightfitTM pigments have been approved both by the U.S. Food and Drug Administration (FDA) and the Canadian Health Protection Branch (HPB) for indirect food contact applications. In addition, these pigments are manufactured in aqueous medium, eliminating exposure to the polychlorinated intermediates and organic solvents associated with the manufacture of traditional high-performance pigments.
RightfitTM pigments have additional benefits, such as good dispersibility, improved dimensional stability, improved heat stability, and improved color strength. Their higher color strength achieves the same color values using less pigment. RightfitTM pigments also cover a wide color range from purple to green-shade yellow color. Being closely related chemically, these pigments are mutually compatible, so two or more can combine to achieve any desired intermediate color shade.
RightfitTM pigments meet the essential performance characteristics at significantly lower cost than high-performance organic pigments. Thus, formulators get the right performance properties at the right cost, resulting in a steadily increasing market for these pigments. RightfitTM pigments provide environmentally friendly, value-added color to packaging used in the food, beverage, petroleum product, detergent, and other household durable goods markets.
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