RECYCLING | ADDITIVES
Recycled polymer blends with and without a Ken-React additive
Source: Kenrich
infrastructure and economics, as well as incompat- ible materials. The solutions are not simple and require more investment in research. In the end, it will be technologies that make recycling viable, and Kenrich’s additive can be part of that solution,” Monte says.
Rising demand
Demand for high-quality rPET is increasing as brands commit to using more PCR in their pack- ages. A challenge, however, is that when PET is processed and reprocessed, the thermal degrada- tion through these multiple heat histories causes viscosity breakdown and yellowing. A new intrinsic- viscosity (IV)-building additive from Techmer PM counteracts this degradation, says Steve Smith, Market Manager for Rigid Packaging at the spe- cialty compounder. The pelletised additive concentrate is intended to be used by converters making, for example, bottles or thermoformed sheets. It is said to rebuild PET polymer chains, which increases viscosity and removes the chemical species that generate yellowness. Yellowness of the rPET is reduced to virgin-level or, in some cases, even less yellow than virgin PET, according to Smith. Although the IV-builder does not compatibilise
the PET with other polymers that could be contami- nating the rPET feedstream, it does help stabilise the polymer and can improve overall quality so that small amounts of contaminant have less of an effect, Techmer says. The additive is suitable for food-contact applica-
tions. It is already being used in thermoformed sheet and is being evaluated in bottles, where results to date are described as positive. Smith also sees interest from processors making fibre for carpet and apparel, for example, where decreased viscosity causes processing problems and limits the
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amount of rPET that can be added. Smith says that the chemistry is sensitive and
requires careful processing to create the optimal concentrate. He says Techmer’s studies have identified what parameters need to be controlled during masterbatch production. “Although proces- sors may have not had good experiences with chain-extenders in the past, this technology is different,” he says. “We are seeing good results at both lab scale and at commercial scale.” Techmer uses in-house IV testing to help determine the appropriate let-down ratio of the concentrate for specific applications.
Bridging the gap Performance of recycled PP (rPP) is a limiting factor in brands and converters meeting their commit- ments to incorporate recycled material in products. “Additives are a means by which to bridge the gap between current performance of recycled material and performance that is expected from the brands, as well as performance that is expected from virgin
Recycled PET (rPET) containing 2.5% of Techmer PM’s IV Building additive concentrate (right) shows increased viscosity and reduced yellowing compared to rPET without the additive (left)
October 2022 | COMPOUNDING WORLD 57
IMAGE: TECHMER PM
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