Temperature stability depends on the type of pigment and the surface treatment.
Goldbronze STANDART® Resist and MASTERSAFE® Gold are stable up to approximately 270°C.
MASTERSAFE MP® is temperature-resistant up to a maximum of 300°C.
STAPA® WM can be processed up to approximately 270°C.
LUXAN® and SYMIC® pearlescent pigments are highly temperature-stable at temperatures above 300°C.
Effect pigments require gentle processing, as high shear forces can crush metal pigments or damage the coatings on pearlescent pigments. Optimal conditions include higher processing temperatures, late addition (side feeding), low shear forces, and shear-sensitive screw geometries. In some cases, the use of a single-screw extruder is advantageous.
Lightfastness depends on the type of pigment, the coating, and the polymer.
Encapsulated types such as SYMIC® OEM, LUXAN® CFX, and EDELSTEIN® CFX are suitable for the most demanding applications.
In-house testing in the final polymer system is recommended.
Here, too, differences depending on the polymer apply; conducting your own weathering tests is advisable.
In general, flake-shaped effect pigments such as aluminum, bronze, or glass flakes do not create flow lines or weld lines; rather, they simply make existing flow- and process-induced structures visible through their orientation-dependent reflection.
Flow lines and weld lines can be reduced through several measures. The most important approach is optimized mold design, particularly through appropriate gate positions, harmonized flow paths, and a surface texture that masks lines. Additionally, a film gate can be used, as it spreads the melt flow widely, thereby reducing flow lines and making weld lines more uniform and less visible.
The use of coarser effect pigments reduces contrast effects, as these orient themselves less strongly along flow and weld line areas.
A pigment dosage tailored to particle size and particle size distribution is crucial for a homogeneous surface appearance. Excessively high pigment concentrations generally increase the likelihood that pigments will align preferentially along the flow paths, which can lead to visible flow lines. Conversely, excessively low pigment concentrations can make weld lines more visible, as there is insufficient pigment in the weld area to visually mask them.
Since the optimal balance between effect intensity, dispersibility, and flow behavior always depends on the polymer, the part geometry, and the pigment type, it is common practice to conduct concentration series. This allows the dosage to be determined at which the desired optical effect is achieved without exacerbating the formation of flow lines or weld lines.
An increased injection speed and higher injection pressure improve the welding of the melt fronts, thereby reducing the visibility of weld lines.
Aluminum pigments with optimized geometry and a low L/D ratio (e.g., MASTERSAFE® ZP 33-05, MASTERSAFE® MP 55-20 B, and MASTERSAFE® 100-20 B) exhibit more stable alignment in the melt flow and significantly less edge orientation, making flow lines and weld lines less visible.
MASTERSAFE® Silvershine makes it possible to replace paint finishes and metallization in plastics with mass coloring. The pigments produce highly brilliant silver shades, smooth and glossy metallic effects, and a homogeneous, non-textured surface. They offer high opacity, are very cost-effective, and process exceptionally well in injection molding and extrusion processes. Grades 40820 B and 41220 B are particularly fine and opaque, delivering an excellent, low-texture metallic effect with very good flop behavior.
STAPA® AC Reflexal was originally developed for engineering plastics, but offers a wide range of applications and is also very well suited for polyolefins. The series is based on slightly thicker aluminum silver-dollar pigments with a very narrow particle size distribution, resulting in clearly defined, technically precise metallic effects with very high flop behavior. The special preparation ensures optimal pigment orientation at the surface, thereby delivering high-quality metallized effects directly through mass coloring.
LASERSAFE® 040 – Typical Marking Pattern
LASERSAFE® 040 produces a dark, high-contrast marking pattern through carbonization of the polymer. The result is dark lines with sharp, clearly defined edges. The additive is particularly suitable for transparent as well as light to medium-light shades and enables precise markings such as codes or serial numbers.
LASERSAFE® 020 – typical marking pattern
LASERSAFE® 020 produces a light marking pattern through microporous foaming of the surface. The result is a light, easily recognizable laser marking that stands out particularly well on dark colors or black backgrounds.
LASERSAFE® 040 is typically used at a concentration of 0.01–0.1%.
For transparent or translucent colors, a range of 0.01–0.05% is recommended; for opaque colors, 0.05–0.1%.
LASERSAFE® 020 is used in concentrations of 0.05–0.5%.
In dark shades, a dosage of 0.05–0.2% is usually sufficient, while 0.2–0.5% is recommended for black shades. The additive is always used in combination with carbon black for black formulations. The carbon black content should be below 0.1% to ensure good markability.
LASERSAFE® 040 is highly versatile and, thanks to its polyolefin carrier, is particularly well suited for PP and PE. Due to its low usage concentration, it also delivers excellent results in many engineering plastics, particularly PC, ABS, PA, PBT, PET, and PVC.
LASERSAFE® 020 is suitable for nearly all common thermoplastics. Typical applications include PP, PE, PA, ABS, PBT, PET, PVC, and many other polymer systems. It produces a highly visible, light-colored marking pattern, particularly in dark or black formulations.
LASERSAFE® 040 and LASERSAFE® 020 are ideal for fiber lasers and Nd:YAG lasers operating at 1064 nm in the near-infrared range. Depending on the polymer, both additives can also be used with CO₂ lasers.
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