Wacker: Post-Cure-Free Silicone Rubber with Self-Adhesive Properties

At Fakuma 2026, Wacker will present “Elastosil LR 5471” for the first time. The liquid silicone rubber is self-adhesive, enabling highly efficient production of hard-soft composite components. Vulcanizates made from the material can also be used in medical technology or food-contact applications without the need for extensive post-treatment - (Photo: Wacker).

At Fakuma 2026, Wacker Chemie will present the self-adhesive liquid silicone rubber “Elastosil LR 5471.” The addition-curing two-component system is designed for hard-soft composite components and, after curing, is intended for use in food-contact applications, medical technology and infant care without the need for subsequent thermal treatment.

The material contains internal adhesion promoters and, according to the supplier, adheres to various metals as well as thermoplastics. In internal tests conducted in accordance with ISO 813, an adhesion strength of 28 N/mm was measured on polybutylene terephthalate (PBT). Comparable adhesion values were also achieved on polyethylene terephthalate (PET). This allows the rigid component to be overmolded with the liquid silicone rubber in the injection-molding process without additional surface pretreatment. The material is therefore particularly suitable for thermoplastic-silicone elastomer and metal-silicone elastomer composite components as well as for co-molding processes.

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A key focus of the development was achieving a low content of volatile substances. Conventional liquid silicone rubbers for sensitive applications often have to undergo several hours of post-curing in an oven after vulcanization in order to reduce volatile substances. With “Elastosil LR 5471,” this step is intended to be eliminated thanks to an additional processing step during production. According to Wacker, the specified volatile content of the cured silicone is below 0.4 percent. This figure is based on measurements carried out in accordance with the method of the German Federal Institute for Risk Assessment (BfR) using two-millimeter-thick test sheets after four hours at 200°C.

According to the manufacturer, the material therefore complies with the relevant BfR recommendation for silicones used in food-contact applications without requiring subsequent post-curing. Wacker also cites regulatory requirements for food-contact and baby-care applications as part of the intended application range.

The mechanical properties have also been tailored for use without post-curing. Non-post-cured vulcanizates achieve an elongation at break of 570 percent and a tear strength of 38 N/mm in accordance with ASTM D 624 B. Potential applications cited by Wacker include seals and flexible scrapers for cookware and kitchen utensils, cushions for medical masks and therapy devices, as well as soft components for pacifiers and baby bottle nipples.

“Elastosil LR 5471” is available in hardness grades of 40 and 50 Shore A. The material is primarily designed for high-volume production of overmolded thermoplastic-elastomer components as well as for co-molding processes.

Fakuma 2026
Friedrichshafen, Germany
October 12–16, 2026
Hall A6, Booth 6212

More information: www.wacker.com

Wacker Chemie AG, Munich, Germany

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