COLOUR | PIGMENTS
Above: New from Shepherd Color, Oxide Green 30C659 offers very good IR reflective properties
tion process, which results in increased heat stability, the new Colortherm Yellow 5 pigment is based on iron oxide and Colortherm Yellow 26 is based on zinc ferrites. Both are designed for cost-effective colouring in the 220-260°C temperature range. The new grades are intended to fill the tempera-
ture performance gap between regular pigments and the company’s higher performance Colortherm Yellow 20 and Colortherm Yellow 30, which are based on iron oxide and zinc ferrite and are heat stable to 300°C. “With equally high colour strength at the same colour space, they offer plastics manufacturers and processors an excellent compromise,” says Bartolucci. He adds that this Colortherm Yellow range covers the colour spectrum of light, saturated yellow shades as well as orange tones. The colour strength of the zinc ferrites — Colortherm Yellow 26 and Colortherm Yellow 30 — is up to 20% higher than comparable products due to their manufactur- ing process, claims Bartolucci. With higher colour strength, a corresponding lower level of pigment addition is required to colour the plastic. Oxide Green 30C659 is a new dark green colour pigment from Shepherd Color that is said to offer excellent infrared reflective properties and to be suitable for use in a range of plastics applications, particularly thin films and fibres. Part of the com- pany’s Dynamix ED pigment line, Oxide Green 30C659 is specially processed to provide a tight particle size distribution and is treated to greatly improve wetting and dispersibility, according to Mark Ryan, Marketing Manager at the company. “In thin films [these characteristics] reduce the chances of outsized or undispersed particles causing defects or streakers,” Ryan says. “In fibres the overall improved dispersion reduces filter-pack values and leads to less defects.” Another recent addition to the Dynamix ED line is Yellow 30C133, which is a PY184 bismuth
22 COMPOUNDING WORLD | September 2021
vanadate yellow that complements the company’s NTP Yellow and RTZ Orange pigments. Ryan says this pigment range offers “a complete coverage of the yellow colour space with high-performance pigments with high-heat stability, excellent disper- sion properties, and bright chromatic colours.” Ferro recently introduced its 6000 Series, a high dispersibility (low Filter Test Value) range of red iron oxides designed for film, fibre and other demanding applications, according to Global Marketing Manager for Plastics at Ferro, Daniel Lladó. He says that the company is also currently working on encapsulation and surface modification technologies to enhance pigment properties such as processability, heat and weather-fastness, as well as resistance to chemicals.
Pandemic effects Over the past 18 months, the Covid pandemic has seen a huge increase in the use of sanitising solutions on surfaces, presenting pigment users with a new potential challenge of colour fading. Sun Chemical says it has seen an increase in requests to test colour stability, leading to the decision to carry out a study of several organic pigments by directly exposing them to sanitising solutions. Global Plastics Technical Lab Manager Michael Willis says: “This study provided a com- parison of colour stability for chips versus dry pigment exposure to four sanitising solutions. The results were impressive, showing little to minimal catastrophic failure of colour, especially in the high-performance pigment category.” Mechanical recycling plays a key role in reduc- ing plastics waste. However, it generates multiple challenges, one of which is the need for robust colorants that are able to withstand the multiple heat cycles that post-consumer recycle (PCR) may be subjected to. Multiple processing steps with high tempera-
tures may potentially lead to material degradation, explains Sun Chemical’s Kujat. “If PCR contains chemical substances of concern, like degraded impurities, it is limited in its ability to replace virgin polymer. Therefore, lower quality PCR could hinder the industry in its target to achieve high recycled content in products. That’s why we see a trend in starting with purer, safer, and more robust color- ants for plastics to ensure further recycles,” he says. Sun Chemical offers a portfolio of pigments that
are suitable for mechanical recycling of polyolefins, including HDPE, Kujat says. These include the Eupolen and Microlen product ranges (formerly BASF brands) that are claimed to offer very good dispersion, low warping and improved pigment
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IMAGE: SHEPHERD COLOR
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