At the upcoming Fakuma 2026 International Plastics Processing Exhibition, to be held from October 12 to 16, Wacker Group will present for the first time its post-cure-free self-adhesive liquid silicone rubber, ELASTOSIL LR 5471. According to Wacker, this is the first liquid silicone rubber product to combine both post-cure-free and self-adhesive properties.

Core Technical Breakthrough: Post-Cure-Free + Self-Adhesive

ELASTOSIL LR 5471 is a two-component addition-cure material that crosslinks to form an elastomer with extremely low volatile content. The product's core innovation lies in the fact that hard/soft composite components made from it can be used in the food and medical industries as well as baby care, in many cases without the need for post-curing.

Conventional standard liquid silicone rubbers typically require several hours of heat treatment to meet the volatile content requirements of sensitive applications such as food contact, medical, or baby care. This post-curing step adds to the production cycle, particularly affecting application scenarios with high efficiency demands. ELASTOSIL LR 5471 reduces the volatile content of the cured elastomer to a level far below what post-curing treatment would normally be required to achieve by incorporating an additional step during the manufacturing process, thereby making post-curing optional in applications compliant with German Federal Institute for Risk Assessment (BfR) regulations.

Key Performance Data

Wacker's internal test data demonstrate the product's outstanding performance:

• Adhesion strength: 28 N/mm to polybutylene terephthalate (PBT) (ISO 813), with similar results for polyethylene terephthalate (PET)

• Volatile content: After heating a 2 mm thick test specimen at 200°C for 4 hours, the specified volatile content of the cured silicone rubber is less than 0.4%, compliant with BfR food contact guidelines

• Elongation at break: Up to 570%

• Tear strength: 38 N/mm (ASTM D 624 B)

• Hardness grades: Shore A hardness 40 and 50

Application Scenarios and Process Advantages

The internal adhesive of self-adhesive liquid silicone rubber is added directly to the silicone polymer, enabling rigid components to be directly overmolded with liquid silicone rubber in an injection molding machine without any surface treatment. This facilitates cost-effective mass production of composite components based on thermoplastic or metal materials.

ELASTOSIL LR 5471 is suitable for a variety of hard/soft composite applications:

• Food contact applications: Gaskets and flexible spatulas for cookware, baking, and kitchen utensils

• Medical applications: Medical mask liners, therapeutic devices

• Baby care: Soft components for pacifiers and baby bottles

Implications for Downstream Enterprises

For companies engaged in LSR injection molding, the significance of post-cure-free technology lies in the simplification of production processes and improvement in efficiency. Eliminating the post-curing step not only shortens the production cycle but also reduces energy costs. At the same time, the product's excellent adhesion to metals and thermoplastic materials provides a more reliable material solution for integrated molding of hard/soft composite materials. It is recommended that relevant companies consider the feasibility of applying such post-cure-free self-adhesive LSR in their product development.

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