Adhesion promoter - chemical bridge between rubber and carrier material 

What are adhesion promoters?

Adhesion promoters are chemical substances or systems that enable a permanent bond between rubber and another material, e.g. Metal Composite Parts, Plastic Composite Parts or Fabric Composite Parts. They play a central role in the production of rubber composite parts by Adhesion between dissimilar materials and prevent detachment under load.

 

What are the functions of adhesion promoters?

By nature, rubber adheres poorly to smooth, non-polar materials such as steel, Aluminium or Polyamide. Adhesion promoter (also known as bonding agents) act as a chemical bridge between the rubber and the substrate:

  • They cross-link with the rubber during Vulcanisation process
  • At the same time, they adhere to the substrate, e.g. through chemical bonding or microscopic anchoring
  • Depending on the system, they consist of a Primer-Schicht und einer Deckschicht, die nacheinander aufgetragen werden, oder Einschichtsystemen, sogenannten „self-priming Adhesives“
  • Due to diffusion processes during the Vulcanisation results in a continuous gradient of the modulus of elasticity in the transition from substrate to rubber, which prevents localised increases in stress

 

Typical adhesion promoter systems are based on resorcinol-formaldehyde latex (RFL), phenolic resins, epoxies, organic Silanes or Polyurethanes - each matched to the material pairing. These are mixtures of substances that provide functional groups for bonding with both the substrate and the rubber. The surface preparation (e.g. Degreasing, roughening) and the correct processing temperature.

 

Where are adhesion promoters used?

Adhesion promoters are used in the manufacture of the following components: