Smart Molding International 2-2021

materials 44 smart_molding international 2/2021 S peaking of the development Dr. Thomas Köppl, group product manager HEXPOL TPE comment - ed; “There are several processingmeth - ods and materials on the market that allow production of automotive interior surfaces such as instrument panels and door trims. However, these processes can be costly, and the materials are not recyclable. OEMs are looking to improve their sustainability practices while also managing system costs. This is why we developed Dryflex HiF TPE.” TPEmaterials are alreadywidely used in automotive interiors, for example in mats, grips and sealings. However, until recently, TPEs have not been vi - able for large scale trim because these applications have much higher specifi - cations regarding abrasion behaviour, processability and heat resistance. The new Dryflex HiF TPE grades fulfil these requirements and are injection mouldable, making them an interest - ing alternative to PU coating, PVC slush moulding or TPO foil processes. In a production trial, 1.1 mm thin skins for the soft surface of a complete instrument panel were moulded and back-foamed with PU, demonstrating that even very large, thin parts can be produced via injection moulding due to the high flowability of the Dryflex HiF TPE. Testing demonstrates that Dryflex HiF TPEs pass the stringent lightfastness and heat resistance requirements for instrument panels (for example 120°C for 1000 hours). A low-gloss, matt sur - face with no visible weld lines is achiev - able as well as themoulding of different leather grains. Surface performance is confirmed by the testing of Erichsen scratch resistance and Crock abrasion. Injection moulding TPE is a faster process and consumes less energy than materials traditionally used in these applications. For example, producing a skin via PVC slush moulding can take 5 to 6 minutes whereas an injection moulded TPE skin can take around 80 seconds. The lower density of Dryflex HiF TPEs (0.9 g/cm3) can decrease part weight, helping OEMs to meet light-weighting and CO2 emissions targets. Additionally, TPE materials are recyclable in processing, which all sup - ports the market need for sustainable manufacturing. Dryflex HiF TPEs can be used inmulti- component applications with direct overmoulding to polypropylene. Com - pared to existing TPU or PU-RIM pro - cesses, which often use PC/ABS as the rigid component, the material’s ability to adhere to PP can deliver further cost and weight reduction in 2K processes. Dr. Köppl concluded: “In developing these materials we worked in close collaboration with Kraton Corporation, based on Kraton IMSS™ technology, Dryflex HiF TPEs deliver a combination of high-performance, soft-touch appeal, processing optimisation and recyclabil - ity. They are part of our growing port - folio of materials bringing new possibili - ties to the automotive industry”. HEXPOL TPE www.hexpol.com Dryflex HiF is a family of very high melt-flow and scratch resistant TPS-SEBS materials recently launched by polymer compounding group HEXPOL TPE. The grades open possibilities to produce large scale parts via injection moulding, including automotive interior surfaces, trims and skins. Super high-flow TPEs enable sustainable solutions for large scale mouldings Dryflex HiF TPE skin and PP carrier backfoamed with PU (Pictures: HEXPOL TPE)