Groundbreaking innovation in colorants for plastics has enabled personal care maker Conair Corp. (Stamford, CT, U.S.) to manufacture hair dryers that display brilliant iridescent effects previously only found in nature. Using new Variocrom™ color-variable pigments developed by BASF Corp., Teknor Color (Pawtucket, RI, U.S.) has produced concentrates that impart to the Conair dryers a shimmering, kaleidoscope play of bright colors that merge from one into another as the viewing angle changes. The hair dryers are the first North American application of the BASF technology.

"While the hand-held hair dryer pioneered by Conair has long since become an everyday necessity for people around the world, striking design and color remain as important for this appliance as functionality," says Paulette Heller, director of Marketing for Conair. "By bringing an exciting new visual flair to our hair dryers, color-variable effects make them stand out from other personal care products and add a new dimension of enjoyment to everyday use."

The key to these effects is the development by BASF of formulations of pigment flakes or platelets that, in plastics processing, form multi-layer structures whose reflection, refraction, and interference properties yield what BASF describes as "angle-dependent color play." Teknor Color developed concentrates that incorporate this complex optical system and worked with Conair to maximize economy in using the concentrates.

Dramatic Special Effects

The effects provided by the new Variocrom pigments differ from conventional angle-dependent or "flip-flop" effects in the intensity of their colors and the complexity of their shifting hues, according to Jennifer Bailey, BASF account manager. "For precedents, the scientists who developed our new pigments have pointed to the brilliantly iridescent shells of exotic insects like the rose beetle, and to the constantly changing colors in soap bubbles," Ms. Bailey says.

Intrigued by the new pigments, Teknor Color brought them to the attention of George Murray, Jr., Conair's director of Tooling and Plastics Technology. "Drawing on its experience with other flip-flop pigments containing platelets that cause color shifts with changes in viewing angle, Teknor Color developed concentrates that maximize the special effects of the Variocrom pigments at minimal loadings," Mr. Murray says. "They accomplished this without compromising other color characteristics."

Based on technology developed in Germany 2 years ago by BASF AG, Variocrom pigments come in four colors: Magic Gold, Magic Red, Magic Purple, and Magic Green. The intensity of the color-variable effect depends on the clarity of the natural resin used, and the shift in hue is most pronounced in large parts with multiple curves. "These can be combined with organic pigment and dyes to produce an infinite variety of colors," says Ms. Bailey. "Possibilities range from dramatic color shifts, such as from rose to green, to many kinds of subtle effects. For example, a part might be transparent when viewed at an angle of 90 degrees, colored at 15 degrees, and opaque at 180 degrees."

"The eye-catching effects are particularly attractive to people in the 15- to 30-year-old category," notes Ms. Bailey. She says that all Variocrom pigments are approved by the U.S. Food and Drug Administration for food-contact uses.