More than a carrier: combining PET compatibility with functional performance
When developing a masterbatch, attention naturally focuses on the pigment or functional additive. However, the carrier resin can be just as important in determining how effectively the masterbatch processes and how it influences the properties of the final material.
The right carrier needs to disperse pigments and additives effectively, process efficiently and remain compatible with the polymer it is added to. For transparent applications, it also needs to minimize its impact on optical performance.
As the plastics value chain moves toward greater use of recycled materials and increasingly demanding regulatory requirements, carrier selection influences more than processing alone. It can affect the performance, appearance, compatibility and suitability of the final material.
Explore Akestra™ for masterbatches
A carrier designed for transparent polyester systems
Akestra™ is an amorphous copolyester combining glass-like clarity with heat resistance and processing versatility. It is compatible with a range of amorphous polymers and can be used in processes including extrusion, injection molding and compounding.
This makes Akestra™ a versatile carrier platform for functional and color concentrates designed for demanding transparent applications. Potential applications include masterbatches containing:
- Color pigments
- UV stabilizers
- Antiblock agents
- Antistatic agents
- Antimicrobial agents
- Nucleating agents
- Mold-release agents
Designed to work with PET and rPET
For PET applications, carrier compatibility is especially important. An incompatible carrier can negatively affect haze, transparency and the overall appearance of the finished article.
Akestra™ offers a polyester-based carrier option for PET and PETG applications, helping masterbatch producers formulate concentrates while maintaining the optical properties expected from transparent polyester products. Akestra™ 90 is particularly suitable for PET and PETG masterbatch applications. This also makes it a relevant carrier option for masterbatches intended for transparent PET and rPET-based solutions, subject to validation in the specific masterbatch and final application.
This becomes increasingly relevant as converters and brand owners look to combine high-quality appearance with greater use of recycled PET.
More than compatibility: contributing functional performance
Akestra™ is not only a transparent carrier compatible with PET and rPET. It can also contribute functional performance to the final formulation. Depending on the Akestra™ grade, addition level and formulation, it can be used to modify melt behavior and decrease melt viscosity, potentially supporting improved processing and performance of the polyester system. This gives Akestra™ a dual role in the masterbatch: it enables the efficient delivery of pigments or functional additives while also contributing to the performance of the final polymer formulation.
Efficient masterbatch delivery with minimal impact on the base polymer
An effective carrier must accommodate sufficient concentrations of pigments or functional additives while supporting stable formulation and processing. Depending on the selected pigment and formulation, Akestra™ can support pigment loadings of approximately 20 to 50 wt% in color masterbatches.
In masterbatch formulations evaluated for transparent PET-based food-contact applications, Akestra™ represents approximately 50 to 80 wt% of the masterbatch as carrier resin. The formulated masterbatch is typically added to the PET resin at approximately 1 to 3%, depending on the required color or functionality and the performance requirements of the final application.
This enables the development of concentrated masterbatches while limiting the total amount of carrier introduced into the final polymer.
Processing flexibility for sensitive additives
The processing characteristics of Akestra™ make it suitable for standard polymer-processing technologies, including extrusion and compounding. Its processing flexibility can be particularly valuable in formulations containing pigments or functional additives that are sensitive to prolonged thermal exposure.
For selected formulations, processing at temperatures below those commonly used for PC may help reduce the thermal exposure of sensitive additives. Actual processing conditions should be established for the specific formulation and equipment.
Supporting the next generation of food-contact packaging
Food-contact applications add another dimension to carrier selection. It is not enough for the base polymer to be suitable for food contact. Every component of the material formulation needs to be considered as part of the compliance assessment of the finished article.
Akestra™ is suitable for defined food-contact applications and is supported by regulatory documentation for applicable markets and conditions of use. This provides a strong starting point for masterbatch producers developing color and functional concentrates for transparent PET and PETG food packaging.
The timing is particularly relevant. The EU Packaging and Packaging Waste Regulation, PPWR, Regulation (EU) 2025/40, has applied since 12 August 2026 and places greater emphasis on packaging circularity, recyclability, recycled content and the management of substances of concern.
For packaging producers and brand owners, materials therefore increasingly need to deliver performance, circularity and regulatory readiness at the same time.
Beyond PET: masterbatch solutions for polycarbonate
Akestra™ can also be used in polycarbonate applications where transparency, heat resistance and processing performance are important. Akestra™ 100 and 110 provide options for formulating transparent PC-based systems while offering a polyester route to modify processing, melt flow behavior and performance.
The carrier is part of the solution
Masterbatch performance is ultimately determined by more than the active ingredient. Selecting a carrier that combines polymer compatibility, optical performance, processing flexibility and food-contact suitability can help masterbatch producers create formulations that meet the changing requirements of converters, packaging producers and brand owners.
For transparent PET and rPET applications, Akestra™ provides more than a compatible carrier platform. It helps masterbatch producers introduce color and functionality while preserving clarity and compatibility, and can contribute functional benefits such as improved melt behavior and reduced melt viscosity in the final polyester formulation.
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