Hydroxyl silicone oil (α, ω-dihydroxy polydimethylsiloxane) has become a key component of the modern sealant system due to the high reactivity of the terminal hydroxyl group and the high and low temperature resistance, weather resistance, hydrophobicity, electrical insulation and other characteristics of the silicone backbone. Its role runs through all aspects of formula design, process operation and final performance.
1. Chemical mechanism and formula role
1. Crosslinking core: Hydroxyl silicone oil condenses with silane coupling agent or curing agent to form a three-dimensional crosslinking network. It is the base glue of single/two-component room temperature vulcanized silicone rubber (commonly known as 107 glue).
2. Structural control: Low-viscosity hydroxyl silicone oil (25-100 MPa·s) reacts preferentially with the hydroxyl groups on the surface of silica during the mixing stage to inhibit the structure of the filler, maintain the plasticity of the rubber material, and extend the construction period.
3. Performance adjustment: By adjusting the hydroxyl content (0.5–8%) and molecular weight (50,000–100,000), a balance can be achieved between curing speed, modulus, and elongation; it can be combined with dimethyl silicone oil, fluorosilicate oil, etc., which can simultaneously improve oil resistance, solvent resistance and low temperature flexibility.
2. Process advantages
1. Curing at room temperature: Combined with deketoxime type or deol type curing agent, the surface curing can be completed within 5-35℃ and 30-120 min to meet the needs of on–site rapid assembly.
2. Solvent-free system: medium and high viscosity hydroxyl silicone oil itself can provide initial viscosity and thixotropic properties, avoid the use of organic solvents, and comply with VOC regulations.
3. Easy-to-pump glue injection: Customized products with a viscosity of about 5000 MPa·s can be matched with the beat of automatic dispensing and glue injection equipment to improve the efficiency of automotive and photovoltaic module production lines.
3. Performance contribution
1. Weather resistance and aging resistance: long-term use from -60℃ to 200℃, elasticity is still maintained under the action of ultraviolet light, ozone, and salt spray, and the service life can reach more than 20 years.
2. Bonding and sealing: It is firmly bonded to glass, aluminum, concrete and other substrates in collaboration with the coupling agent, with a displacement capacity of ±25%, which meets the dynamic sealing requirements of curtain wall, door and window joints.
3. Function expansion: In the cable tunnel fireproof sealant, hydroxyl silicone oil cooperates with inorganic fillers and flame retardant to expand in case of fire to form a ceramic heat insulation layer, which can achieve fire-resistant sealing for more than 2 hours.
Four, typical application scenarios
· Construction: The curtain wall and hollow glass are sealed in two ways, and the roof expansion joints are waterproof.
· Automobile: windshield glass bonding, lamp sealing, battery pack shell sealing.
· Electronics: LED drive power supply potting, PCB moisture-proof coating, photovoltaic frame sealing.
· Electric power: fireproof sealant for cable tunnels and substations, resistant to aging and electrical corrosion.
· Household use: kitchen and bathroom mildew-proof glue, refrigerator freezer box sealing.
In summary, hydroxyl silicone oil achieves excellent durability, adhesion and construction adaptability through the triple mechanism of chemical crosslinking, structural control and performance adjustment. It is the preferred matrix material for reliable sealing and long-term protection in many industries such as construction, automobiles, electronics, and electric power.
For more information, please click： IOTA 107 V5000-V80000 - IOTA CORPORATION LTD.
