Frequently Asked Questions about Silicones for Release Agents applications
What is a release agent?
Release agents are materials that allow for control or elimination of adhesion between two surfaces.
Release agents are made of materials that provide low surface tension to objects that inherently present higher surface tensions. They need to be applied in thin films on the surface of these objects to be efficient.
If they should mainly provide release or anti-adhesion between surfaces, they should also provide a slip effect. This is required in most cases to be fully able to avoid any sticking at the interface. For this reason, release agents are also known as surface lubricants, slip aids, anti-blocking agents or parting agents.
Release agents are widely used in manufacturing processes. Primarily we find them used in the manufacturing of plastic & elastomeric objects that are transformed by molding. The object being molded must not stick to the mold surface, and the release agent prevents this from happening.
They further allow for easy release, even from complex mold designs, thanks to their slip effect, allowing the molded pieces to easily slip from their mold.
A certain permanency / adhesion of the release agent on the mold surface is necessary to ensure a perfectly continuous release film persists even under shear induced by flowing material.
The release film will also be able to provide perfect separation of the molded piece from its mold, necessary to avoid residues of molded material in the mold, also called mold fouling.
Do you need mold release for silicone molds?
There are different types of release agents. Those that need to be applied before each release cycle are called “single release agents”. Those who remain on the mold surface for multiple release cycles/moldings are called “semi-permanent” or “multi-release agents”. Those that form a durable film on the mold surface are called “permanent release agents” or “release coatings”.
There are also products called “internal release agents”. These are added to the formulation of the material that is to be released from the mold. Internal release agents must be incompatible with the material's matrix so that they migrate to the surface of the piece during the molding operation, thereby creating a release film at the interface.