Document ZJqxyGQYvYLjVx2D70bx4mLmY

Evaluation results of alternative elastomer materials to Fluor-Elastomers (FKM) with regard to the ECHA proposal to prohibit PFAS substances July 2023 Dichtungstechnik Wallstabe & Schneider GmbH & Co. KG Strasse-der-Dichtungstechnik 2 D-94559 Niederwinkling, Germany 12th July 2023 date Dr. Christian Gntner, Head of Material Department Christian Buhrow, Material Development, Focus PFAS Table of Contents Introduction ......................................................................................................................... 2 VW TL52708 - FKM elastomer seals for EGR application............................................. 3 Mercedes Benz DBL1364.40 - FKM with resistance to engine oils, fuels, diesel........ 5 BMW GS 93010-3 5505 - FKM with resistance to fuel ................................................... 6 Porsche PN707-2 BK 12-1 - FKM with resistance to blow by ....................................... 7 Summary and Evaluation.................................................................................................... 8 Appendix.............................................................................................................................. 9 Normative References......................................................................................................... 9 Introduction The company Wallstabe & Schneider GmbH & Co. KG is a producer of elastomer materials and manufacturer of seals for automotive applications. For automotive applications, especially in the area of the engine with high temperatures, but also for different aggressive media, e.g. fuels, exhaust gases, high performance elastomer materials are needed to ensure the function of the system. In this respect, Fluor Elastomers (FKM) have established over the last years and decades to fulfill all necessary requirements. For sure, there are also other elastomer materials, as Acrylic-Rubbers (AEM, ACM), Silicone Rubbers (VMQ), etc., that in some properties may be comparable to FKMs, but the following study should show, the behavior of these materials in comparison to FKMs for the specific automotive demands and applications. Therefore, the alternatives have been tested acc. conditions defined in OEM (VW, Mercedes-Benz, BMW and Porsche) specifications designed for high performance materials, i.e. FKM. 2 VW TL52708 - FKM elastomer seals for EGR application The VW specification for Exhaust-Gas-Recirculation (EGR) TL527081) requires a hot air aging of the material at 200 C over a period of 1008 h, simulating the actual temperature load of an elastomer gasket over the whole lifetime of its application. After the aging different material properties as change in hardness and change in mechanical properties of the materials have to be measured and are limited due to the specification requirements. Therefore, at least two requirements only can be met with a FKM material: - the change of hardness/hardness increase after air aging 1008 h at 200 C must be at maximum +8 Shore A. change in hardness [Shore A] change in hardness after air aging 1008h/200C 30 29 25 20 20 20 18 17 15 13 10 5 2 0 FKM AEM ACM HNBR EPDM VMQ NBR figure 1: change in hardness of FKM and alternative elastomer materials after heat aging acc. VW TL52708; specification limit max. change +8 Shore A shown as red dotted line; The changes in hardness of all possible alternative materials do not meet the requirements. 3 - the elongation at break after air aging 1008 h at 200 C must be at least still 200 % elongation at break after air aging 1008h/200C 250 225 200 elongation at break [%] 150 100 81 50 2 2 8 2 2 0 FKM AEM ACM HNBR EPDM VMQ NBR figure 2: elongation at break of FKM and alternative elastomer materials after heat aging acc. VW TL52708; specification limit min. elongation at break 200 % shown as red dotted line; The elongations at break of the alternative materials are always lower than 200 %, so no alternative material meets the requirement. Only FKM fulfills all specification limits regarding heat aging requirements and hence can be seen as a suitable material for EGR applications. 4 Mercedes Benz DBL1364.40 - FKM with resistance to engine oils, fuels, diesel The Mercedes Benz material specification for elastomer gasket materials DBL13642) defines in the application code .40 FKM materials with resistance to high temperatures, engine oils, and fuels. Testing alternative materials with reference of this specification at least one requirement that can only be met with FKM material. - the change of volume after aging in reference fuel FAM-B 72h at 23C must be at maximum +30 %. aging in reference fuel FAM-B 72 h / 23 C change in volume [%] 200 184 180 163 160 147 140 127 120 106 100 89 80 60 40 20 20 0 FKM AEM ACM HNBR EPDM VMQ NBR figure 3: change in volume of FKM and alternative elastomer materials after reference fuel aging acc.DBL1364.40; specification limit max. change in volume +30 % shown as red dotted line; The changes of volume of the alternative materials are significant higher (>3x to 6x higher) as the specification allows, no other elastomer than FKM does meets this requirement. As a high swelling of a gasket material can cause an extreme failure of the gasket itself but a leakage, in this case of fuel, the use of inappropriate materials can cause a major failure of the whole system and an environmental pollution. According the DBL1346, there are also other application codes, as .26 or .46 that requests high performance materials with excellent resistance to different, partly aggressive automotive fluids and high temperatures, that only can be met with Fluor-Elastomer materials. 5 BMW GS 93010-3 5505 - FKM with resistance to fuel Also with the common BMW specification for elastomer gasket materials, GS 93010-33) there are requirements regarding fuel resistance, e.g. application code 5505, where the change of volume after aging in reference fuel FAM-B for 168 h at 23 C must be lower than +20 %. Testing FKM as well as the alternative elastomers with regard to this specification, yields in analogue results to the Mercedes-Benz aging tests: aging in reference fuel FAM-B 72 h / 23 C change in volume [%] 200 189 184 180 160 147 140 128 120 106 100 89 80 60 40 20 20 0 FKM AEM ACM HNBR EPDM VMQ NBR figure 4: change in volume of FKM and alternative elastomer materials after reference fuel aging acc. BMW GS 93010-3 5505; specification limit max. change in volume +20 % shown as red dotted line; As well as the aging test results acc. DBL13642), all alternative materials show significant higher changes in volume/swelling after the testing period. Already described above, this high swelling can cause a major failure of the gasket function. 6 Change in volume [%] Porsche PN707-2 BKL 12-1 - FKM with resistance to blow by Porsche material specification for elastomer gasket materials PN707-24) defines in the resistance class 12-1 FKM materials with resistance to blow by. Testing alternative materials with reference of this specification at least one requirement that can only be met with FKM material. Aging in Blow by medium 1 72h/120C to Porsche PN707-2 BKL 12-1 250 200 150 100 50 0 FKM AEM ACM HNBR EPDM VMQ NBR figure 5: change in volume of FKM and alternative elastomer materials after blow by aging acc. Porsche PN 707-2 BKL 12-1; specification limit max. change in volume +35 % shown as red dotted line; All alternative materials show significant higher changes in volume/swelling after the testing period. Already described above, this high swelling can cause a major failure of the gasket function. 7 Summary and Evaluation On the basis of all the tests carried out in this study, it is clear that there are specific applications in the automotive industry where an FKM elastomer material is definitely required for sealing functions. As an alternative to these high performance materials, there are no commercially available elastomer materials. Therefore, the impact on the automotive industry as a whole would be very critical if fluoro-elastomers such as FKM or FVMQ were restricted. Therefore, we strongly advise against banning FKM, PTFE and FVMQ as polymer materials, and to remove them from the ECHA proposal. 8 Appendix Table 1: Test results of FKM compared to AEM, ACM an HNBR with view of different OEM elastomer materials specifications for seals and gaskets specification VW TL52708 Mercedes-Benz DBL1364.40 BMW GS93010-3 5505 Porsche PN 707-2 12-1 conditions air aging 1008 h / 200 C FAM B 72 h / 23 C FAM B 168 h / 23 C Blow By 1 72 h / 120 C characteristics change in hardness [Shore A] elongation at break [%] change of volume [%] change of volume [%] change of volume [%] requirements -2 to +8 min. 200 -10 to +30 max. +20 max. +35 FKM +2 225 +20 +20 +6 AEM +20 2 +147 +147 +46 ACM +18 2 +189 +189 +64 HNBR +17 8 +106 +106 +89 Table 2: Test results of FKM compared to EPDM, VMQ and NBR with view of different OEM elastomer materials specifications for seals and gaskets specification VW TL52708 Mercedes-Benz DBL1364.40 BMW GS93010-3 5505 Porsche PN 707-2 12-1 conditions air aging 1008 h / 200 C FAM B 72 h / 23 C FAM B 168 h / 23 C Blow By 1 72 h / 120 C characteristics change in hardness [Shore A] elongation at break [%] change of volume [%] change of volume [%] change of volume [%] requirements -2 to +8 min. 200 -10 to +30 max. +20 max. +35 FKM +2 225 +20 +20 +6 EPDM +20 2 +127 +128 +128 VMQ +13 81 +163 +184 +195 NBR +29 2 +89 +89 +69 Normative References 1) VW TL 52708 - FKM elastomer gaskets for EGR applications (2017-01) 2) DBL1364 - O-Rings and Molded Seals Manufactured from Elastomers (2022-03) 3) BMW GS 93010-3 - Elastomers, Material specifications, application keys, test media (2022-12) 4) Porsche PN 707-2 - O Rings and Molded Seals, Material requirements (2022-02) 9