THERMOPLASTIC ELASTOMERS | MATERIALS


enabling them to be used in applications such as floor mats, cup holder liners, fascia mats and HVAC components. “They display low odour with results 2.0 to 3.0 [on a scale from 1 to 5 beginning with ‘detectable’ and ending with ‘disturbing’] in standards such as VDA 270,” Köppl says. “They achieve VOC results from 60 to 120 µg/g and Fog from 200 to 600 µg/g. According to gravimetric fogging standard DIN 75201 they achieve conden- sate less than 1.0 mg.” Kraiburg TPE says it has speeded up its


application-specific development of TPEs in response to increasing demand for the materials in high-quality exterior applications. The latest developments include TPE-S compounds in its Thermolast K series with improved adhesion to EPDM rubber and high UV resistance (see also automotive feature in Injection World Nov/Dec 2017). Target applications include two-component window trims and sealing profiles, where they go up against styrenic block copolymers and TPVs. The first two compounds are TC7EAZ and


TC7EFZ, both with a hardness of 70 Shore A. “Weathering tests have shown that the surface quality of Kraiburg TPE compounds is superior to that of competing materials,” the company says. For the first of the two new compounds, the company focused its development attention on adhesion, while the second scores higher on low fogging values.


Improved adhesion to EPDM Kraiburg carried out EPDM/TPE adhesion tests in accordance with the VDI-2019 standard (at ambient temperature and after 1,500 hours at 90 °C) and also ISO 37. It assessed tensile stress and elonga- tion, as well as the force required to destroy the specimen.


In these adhesion tests, the new materials


received good results with both foamed and compact EPDM workpieces. The tests showed that adhesion mainly depends on the cleanness of the inserted EPDM profiles, and that the best and most consistent results are obtained when the EPDM profile parts are cut as shortly as possible before the TPE component is over-moulded. Kraiburg TPE partnered with LWB Steinl in its


tests. LWB Steinl is one of the world’s leading global manufacturers of vertical transfer moulding presses and horizontal injection moulding ma- chines for rubbers. Kraiburg TPE adds that its new EPDM adhesion compounds also feature economical processing. They are moulded at relatively low temperatures of 200°C to 220°C, so cooling times are relatively


www.injectionworld.com


short and holding pressure time can also be reduced. The initial good adhesion of the com- pounds to EPDM also ensures that the finished parts can be removed from the mould earlier and more easily than with other TPEs. “Together with LWB Steinl, we have managed to optimise the material and process technologies in such a way that they meet the requirements of different automotive window systems,” says Kraiburg TPE CEO Franz Hinterecker. Several companies highlight sustainability issues in connection with new material developments. Says Klas Dannäs, Global R&D manager at Hexpol TPE: “Dryflex PCW TPE compounds demonstrate how we can turn waste into a resource. The materials contain a volume of post-consumer recyclate from 33% to 80% by weight. Recyclate consists of polypropylene drawn from automotive mouldings, or rubber tyre crumb from both OEM and after-market tyres.”


Sustainability trend Compounds exhibit excellent UV and weathering resistance (conforming to EN ISO 4892-2:2006 and VW PV 3929 : 2008 Kalahari Test), Dannäs says. They are already being used in applications such as automotive mud flaps, sidesteps and antidrag lips. Dannäs also points to Dryflex Green, a family of TPE compounds based on raw materials from renewable resources such as plant and vegetable crops. “To give the right balance or renewable content, performance and mechanical properties, we continue to investigate new sources of raw materials as they become available,” he says. These include products and by-products from agriculture that are rich in carbohydrates, especially saccha- rides such as grain, sugar beet and sugar cane. “We’re also working with suppliers and custom- ers to discuss how we can improve life cycle


May 2018 | INJECTION WORLD 45


Above:


TPE-EPDM test piece is put through a


tensile test by Kraiburg TPE. With its new TPEs, adhesion is excellent, even with a small contact surface, the company says


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62