Colored plastics are used every day in a huge range of applications and settings, but very few people know — much less stop to consider — how these hues are achieved. With the help of Penn Color, a knowledgeable and experienced local colorant manufacturer who has a longstanding partnership with The Rodon Group, we have gathered information and insights into how the plastic products we know and use every day get their colors.
Plastics can be colored using various coloring systems, each of which offers its own unique properties, benefits, and drawbacks. Masterbatches,”salt and pepper” blends, Liquid Color, and precolored resins are four of the most common coloring techniques.
To color the injection-molded products we produce at The Rodon Group, we purchase “natural” polymers, such as Nylon, LDPE, ABS or Polypropylene, for instance, in pellet form. We then blend color concentrates, many from Penn Color through a dosing unit to dispense the colorant at anywhere from 1% to 4% typically. The dispensing unit is calibrated and then set to provide the exact amount of colorant to color any of the natural polymers we buy.
The Color Matching Process
To pinpoint the desired color for each plastic product or part, a color matching process must be completed, which allows engineers to develop a specific color concentrate for a particular application. Typically, a chip, plaque, or Pantone number provides an approximate idea of the desired hue, and information about the specific polymer being used helps determine the formulation for the color concentrate.
For each polymer being color matched, various factors must be taken into consideration, including viscosity and melt processing temperatures. For example, a laboratory may use formulation guidelines to determine what carrier resins, pigment systems, stabilizers, or other additives would be suitable for the specific product and application at hand, as prescribed on the color match request form. It’s also important to keep in mind that colors will look different depending on the polymers’ gloss, appearance, and filler content; a color in nylon is going to look different from the same color in acrylic, for example. Environmental conditions, chemical resistance, and FDA suitability must all be taken into consideration when preparing a color match.
Penn Color can color match in any polymer system, some of which include nylon, polypropylene, polyethylene, polyesters, PVC, and acrylics. A color spectrophotometer is used to measure, store, and formulate colors using a computer color matching system. All colors and polymer systems are stored electronically in the color matching system — as well as in chip files or plaques produced in a laboratory during the color matching process.
Successful plastic coloring depends on close attention to minute details and adherence to unique application-specific requirements. For instance, Rodon has completed injection molding processes for small window components; to ensure optimal functionality, such components require colorants that are resistant to fading as well as heat buildup. Or, for certain car components requiring an exact color match with other parts, our team must be sure that colors match precisely — under all types of lighting conditions and in comparison with very similar hues; white door handles must be an exact match with white-painted metal doors, for instance. And for any items that will come into contact with food or any plastics used in hygiene-critical medical applications or toys, strict regulatory requirements must be met to ensure optimal end-user safety.
Specializing in high volume injection molding orders of more than 1,000,000 pieces, The Rodon Group is proud to offer processes for a wide range of industries and applications — including medical, food and beverage, and window and door. To learn more about our turnkey injection molding and thermoforming capabilities, check out our comprehensive eBook today.
Founded in 1964, Penn Color develops and manufactures a diverse product line of thermoplastic color and additive masterbatches, in addition to liquid dispersions for various ink, coating, and thermoplastic applications. For over fifty years, Penn Color has maintained a commitment to surpass the expectations of our customers and has expanded and diversified to develop innovative solutions in the many markets that they serve. With over 700 employees, Penn Color is privately held with manufacturing facilities in the U.S., Europe, and India as well as a sales office and research lab in China. Through carefully planned diversification, Penn Color can address constantly changing industry requirements for new, fully customized products and solutions. Visit their website by clicking here for more information on colorants.