Which adhesive bonds to silicone?

Cured silicone rubber has a very low surface energy. That is exactly what makes it non-stick and durable – and why epoxy, polyurethane or cyanoacrylate adhesives bond poorly or not at all. As a rule, silicone is therefore reliably bonded with silicone.

Silicone to silicone

One-part silicone adhesives (RTV-1) join cured silicone parts permanently while staying elastic:

• ELASTOSIL E41 – clear, high-strength universal silicone adhesive.
• ELASTOSIL E43 – flowable, excellent mechanical properties.
• ELASTOSIL E50 N – low viscosity and flowable, for gaps and joints.
• ELASTOSIL N2199 – neutral-curing, clear; suitable where acetoxy products could attack metals or sensitive substrates.
• ELASTOSIL E14 – for high temperatures up to 250 °C.

Silicone to metal, glass or plastic

For a reliable bond between silicone and other materials, the substrate is pre-treated with a primer:

• Grundierung G718 x – adhesion promoter for one-part silicones on metal and plastics.
• Grundierung G790 TF – toluene-free primer for addition-curing two-part silicones on metal, glass and plastic.
• ELASTOSIL AUX G 3243 – primer for heat-vulcanizing silicones.

In electronics manufacturing, heat-curing one-part silicones such as SEMICOSIL 989/1K adhere to many substrates even without primer.

Practical tips

• Prepare clean, dry and grease-free surfaces, e.g. with isopropanol.
• Apply primer very thinly and let it flash off completely.
• RTV-1 adhesives cure with atmospheric moisture from the outside in – allow for layer thickness and cure time.
• Always check adhesion with a preliminary test on the original part.

Questions about choosing a product? Call us on +41 61 322 42 24 (Mon–Fri 08:15–12:00 and 13:30–17:00) or write to info@ameba.ch.