Pinneberg/Germany,April 2023–It has been proven numeroustimes that liquid pigment dispersions offer added value in manyapplications due to their high color strength and homogeneousincorporation in plastics processing. But that‘s not all of theadvantages: When it comes to the TOPtopic of recycling, liquidcolors can score points with several of their properties.
The use of recycled plastics is becoming increasingly importantwith simultaneously increasing demands on the properties. In addition to the mechanical characteristics, the color is also playing anincreasingly important role, since recyclates are increasingly beingused in consumer goods and food packaging – a trend that will definitely continue to gain in relevance.
Post-Industrial Recycled (PIR) plastics are processed according totype and color and can be colored with comparatively little effort. Although the post-consumer recyclates (PCR) are also sorted bymaterial, they also contain foreign materials and arealways a colored mix, which usually resultsin a shade of gray without the addition of colorants. Over-coloring this efficiently and homogeneously is a challenge that is made for liquid colors. Because theliquid concentrate already wets the recyclate chips in the feedarea, so that the colorant isevenly distributed before the polymeris melted in the extruder. Moreover, it is irrelevant whether therecyclate contains different fr
actions, e.g. with regard to meltindex and plastic type, since the universalcarrier is well compatible with all materials. And since this is based on renewable rawmaterials, the proportion of fossil components in the product isalso reduced in this way.
The illustration shows an example of PCR chips made of HD-PE, which were directly injection molded with different liquid colors. The plate at the front of the picture shows the original color of the recyclate, from which four attractive earth tones could still beproduced despite the dark green basic tone.
Much more potential can be exploited if liquid single pigment dispersions are mixed by the user himself to create the finished color. The color formulation can then be quickly and efficiently adapted to the changing color of the PCR with minimal effort. And in the case of an upstream regranulation of the recyclate, e.g. on a twin-screw extruder, inline color correction is even possible by feeding the „monos“ separately.