Main ingredients of silicone rubber treating agent

The main components of silicone rubber treatment agents can be categorized into four main groups: organosilicon compounds, crosslinkers, organic solvents, and special additives. These components work synergistically to achieve surface modification, enhanced adhesion, or curing.

Specific components are as follows:

1. Organosilicon Compounds: Core Functional Components
Silane coupling agents, such as trimethylethoxysilane and vinyltriethoxysilane, are the most critical components of silicone rubber treatment agents. The siloxane groups (Si-O-Si) in their molecular structure react chemically with silanol groups (Si-OH) on the silicone rubber surface, forming chemical bonds. The organic groups (such as vinyl or amino groups) on the other end can bond with the bonded material (such as metal or plastic), thereby enhancing bonding strength.
Siloxane polymers, such as polydimethylsiloxane (PDMS), can be coated onto the silicone rubber surface through physical adsorption or chemical bonding, improving its lubricity, weatherability, and biocompatibility.

2. Crosslinkers: Promote curing and network formation.
Metal oxide crosslinkers, such as manganese dioxide (MnO₂) and antimony trioxide (Sb₂O₃), are commonly used in high-temperature vulcanized silicone rubber (HTV). They undergo a dehydrogenation reaction with the Si-H bonds in silicone rubber, forming a crosslinked network that enhances the material's mechanical strength and heat resistance.
Organic peroxide crosslinkers, such as 2,5-dimethyl-2,5-di-tert-butyl peroxide (DBP) and benzoyl peroxide (BPO), are suitable for room-temperature vulcanized (RTV) silicone rubber. They decompose to produce free radicals, initiating crosslinking reactions within the silicone rubber's molecular chains.
Platinum-based catalysts: In addition-type silicone rubber, platinum-based compounds (such as Speier catalysts) act as catalysts to accelerate the addition reaction between Si-H bonds and vinyl groups, achieving rapid, low-temperature curing without the formation of byproducts.

3. Organic Solvents: Adjust Viscosity and Workability
Alcohol solvents, such as ethanol and isopropyl alcohol, are used to dissolve silane coupling agents or siloxane polymers and adjust the viscosity of the treatment agent for easier spraying or dipping.
Ketone solvents, such as acetone and butanone, have strong solubility and can clean oil stains from silicone rubber surfaces. They also serve as diluents to reduce treatment agent concentration.
Aromatic hydrocarbon solvents, such as toluene and xylene, are used to dissolve high-viscosity silicone resins, but their toxicity and volatility should be considered, and they are gradually being replaced by more environmentally friendly solvents.

4. Special Additives: Optimize Performance and Processing
Fillers, such as fumed silica (SiO₂), can be added to the treatment agent after surface treatment (such as hexamethyldisilazane modification) to enhance the wear resistance, hardness, and tear strength of silicone rubber.
Flame retardants, such as aluminum hydroxide (Al(OH)₃) and decabromodiphenyl ether (DBDPO), are used to improve the flame retardancy of silicone rubber and meet fire safety requirements. Plasticizers, such as dioctyl phthalate (DOP), can lower the glass transition temperature (Tg) of silicone rubber and improve its low-temperature flexibility.
Stabilizers, such as hindered amine light stabilizers (HALS), prevent silicone rubber from aging and degradation under UV exposure, extending its service life.