Appliance Design - August 2008 - (Page 15)

PLASTICS Bayer MaterialScience released four new special effects pigments to its LEDA line of mold-in colors. LEDA is part of the company’s Fantasia line of colorful products. method of how to add colors to plastics. Colors can come in many forms, as powders, pellets and even liquids. Many raw pigment and dye materials come as a powder, and are usually converted by the color or resin supplier into pellet form for easier handling and improved color consistency. The powders can be used on their own, however, but color consistency can be an issue. Often a color specialist is needed to get the appropriate ratio of powdered pigments and dyes to plastic resin in order to achieve a good color match and ensure color uniformity from part to part. Before molding, powders must first be dispersed throughout the resin in a mixing operation. Many molding machines do not have the capability and special mixing equipment is required. On the positive side, of all of the options available, buying pigments in powder form offers low inventory costs, fast color changes, and the ability for a company to create custom colors on their own. Most often, however, molders use materials that have been converted into pellets or in some cases into liquid colors because of their ease of use and superior color consistency. Masterbatches and www.applianceDESIGN.com precolored resins are two options for designers to consider. Of these, masterbatches, which are also called color concentrates, are considered to be the most often used. Comparatively, they are more economical, and can be delivered in small volumes. They offer very consistent color uniformity and can be used with a wide range of natural resins. Masterbatches typically come in pellet form, but are available as liquid colors. Each pellet contains all of the pigments, dyes, and additives needed for a specific job. They are then “let down” into natural resins in precise ratios. Let down ratios are normally from 3 percent to 5. If 100 lbs of resin is needed for a run, then 3 lbs of masterbatch is added. This typically requires metering equipment and the ability to heat and mix the pellets into the resin. During the mixing process, Scott Sabreen, president of The Sabreen Group, a Plano, Texas-based secondary plastics manufacturer, says that shear forces are created and these can have an effect on the colorants being mixed and may cause a slight color aberration. He adds that results are typically good and within tolerance. Liquid colors sometimes have somewhat less opacity or bril- liance, Sabreen says, but they are easy to use. They require initial mixing to get good dispersion, but will usually keep properly dispersed over time. To ensure dispersion, some molding operations agitate the liquid prior to molding, especially with special effects pigments that have greater densities. An easier, but more expensive method, is to use precolored resins. In this case, the colorants are added to the resin by the supplier LLC The NR Family Reduced internal oxidation, increased structural integrity. Draws less current, lights gas at a lower temperature. Easy install. Completely interchangeable with 4100 series valve. Freedom from early igniter aging Contact us today for special pricing: info@surfaceigniter.com www.surfaceigniter.com SPECIAL INTRODUCTION ON PAGE 21 applianceDESIGN August 2008 15 6/13/08 10:04:15 AM 800-321-4147 AD07084Surf1.indd 1 http://www.surfaceigniter.com http://www.surfaceigniter.com http://www.appliancedesign.com

Table of Contents Feed for the Digital Edition of Appliance Design - August 2008

Appliance Design - August 2008 Contents Editorial Shipments/Forecasts News Watch Plastics Switches Noise & Vibration Control Joining New Products Design Marts Association Report: CEA Advertiser’s Index

Appliance Design - August 2008

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