Which adhesive is suitable for rubber?
With second-generation adhesive, contact adhesive or an elastic mounting adhesive based on plastic (polyurethane or hybrid adhesive), rubber parts can be glued. Second-generation adhesive is suitable for small areas, contact adhesive for large areas, and mounting adhesive for connections that remain flexible or are used outdoors. Rubber parts made of silicone and weather-resistant sealing rubber EPDM, Like window and door seals, silicone or instant adhesive requires a pre-treatment liquid (activator), as conventional adhesive hardly adheres to them.
Which adhesive do I need for which purpose?
| Application | Suitable adhesive | Note |
|---|---|---|
| small adhesive areas, e.g. rubber ring, rubber foot, torn rubber edge | Second-generation adhesive, preferably in gel form | Hardens in seconds; adhesive area hardens and can break when bent |
| large areas, e.g. rubber mat on the floor, rubber coating on wood | Contact adhesive | remains flexible; both sides are drawn in |
| Rubber on metal, wood or plastic with movement or in outdoor areas | Elastic mounting adhesive (polyurethane or hybrid adhesive) | durable elastic, moisture resistant, cures more slowly |
| Gaskets and profiles made of EPDM | Instant adhesive with pre-treatment liquid that makes the surface adhesive (activator) | The activator is applied to the adhesive surface before the adhesive is applied. |
| Parts made of silicone | Silicone adhesive | Normal adhesive does not adhere to silicone |
Why does adhesive not stick to some rubber parts?
Silicone and EPDM have a smooth, water-repellent surface on which adhesive does not spread evenly and therefore hardly adheres. Plasticiser And oils that contribute to the elasticity of the rubber will migrate to the surface over time, forming a film between the rubber and the adhesive, which can also impair adhesion even after weeks. Soft, shiny or oily-looking rubber parts often contain larger amounts of these substances. Additionally, release agents used in the production of the rubber parts to release them from the mold prevent reliable adhesion of the adhesive.
How do you properly glue rubber?
The adhesive surfaces should first be degreased with cleaning alcohol (isopropanol) or spirit. Subsequently, a light sanding with fine sandpaper is recommended, followed by a further cleaning to remove the sanding dust. Second-generation adhesive is applied thinly to one side, then the parts are immediately joined together and pressed firmly for a few seconds. In the case of contact adhesive, both surfaces are coated and the adhesive must dry for several minutes before the parts are pressed firmly together, as they will no longer move thereafter. Mounting adhesive requires fixation until complete curing, and the final strength of the bond is achieved within a few minutes to a day, depending on the adhesive.
For connections that must withstand permanently high forces, vibrations, or temperatures, such as in motor bearings or vibration dampers, rubber is not adhesively bonded afterwards. Instead, the metal part is coated with a special adhesive layer (Adhesion promoter) coated and at the Vulcanisation connected directly to the rubber under heat and pressure. The resulting Rubber-Metal Composite Parts are significantly more durable than any adhesive.
