How to Distinguish Ordinary Silicone Curing Agents from Intermediate Layer Curing Agents

How to Distinguish Ordinary Silicone Curing Agents from Intermediate Layer Curing Agents
1. Ordinary Silicone Curing Agents
Main Ingredients:
Based on the type of silicone, they are divided into two categories:
One-component Room Temperature Vulcanizing (RTV-1) Silicones: The curing agent is often an organotin compound (such as dibutyltin dilaurate) or a titanate, which reacts with the hydroxyl groups (-OH) in the silicone to release small molecules (such as methanol and ethanol), completing the crosslinking process.
Two-component Room Temperature Vulcanizing (RTV-2) Silicones: The curing agent is often a crosslinking agent (such as tetraethyl orthosilicate) plus a catalyst (such as an organotin). After mixing, the two components crosslink and cure via siloxane bonds (-Si-O-Si-), with no (or minimal) release of small molecules.
Mechanism of Action: It only crosslinks the silicone molecular chains internally and does not actively bond to the substrate (such as metal or plastic). Interfacial adhesion relies on the silicone's own physical adsorption (weak strength and easy to peel). 2. Intermediate Layer Curing Agent
Base: A common silicone curing agent (such as organotin or titanate) serves as the base, supplemented with an interfacial coupling agent (core functional component) and an adhesion promoter.
Common coupling agents: Silane coupling agents (such as KH-550 and KH-560)-one end of the molecule contains a siloxane group (which reacts with the hydroxyl groups in the silicone and integrates into the silicone crosslinking network) and the other end contains an amino or epoxy group (which can form chemical bonds with the hydroxyl groups of metals or polar groups of plastics).
Common accelerators: Organic anhydrides and amine derivatives-they reduce the activation energy of the interfacial reaction and enhance the bonding efficiency between the coupling agent and the substrate.
Mechanism of Action: "Dual Action"-
Internal Curing: The base ingredient (such as organotin) completes the crosslinking of the silicone molecular chains.
Interfacial Bonding: The coupling agent forms a chemical bridge at the interface between the silicone and substrate (silicone-coupling agent-substrate), transforming physical adsorption into chemical bonding, significantly improving interlayer adhesion.