I. Definition and Characteristics of Silicone Oil
Silicone oil is a type of linear polysiloxane liquid with a silicon-oxygen bond (Si-O) as the backbone and organic groups (such as methyl and phenyl groups) in the side chains. Its general chemical structure is (R₂SiO)ₙ, where R is an organic group. Silicone oil has the following unique properties:
Thermal stability: Maintains stable performance over a wide temperature range of -50°C to 250°C.
Low surface tension: Easy to spread, provides excellent lubrication and defoaming properties.
Chemically inert: Resistant to oxidation and weathering, and unreactive with most chemicals.
High compressibility: Minimal viscosity change with temperature, stable physical properties.
Electrical insulation: High dielectric strength, suitable for use in electrical and electronic applications.
II. Silicone Oil Manufacturing Process
The industrial production of silicone oil primarily utilizes the following methods:
1. Hydrolysis-condensation method (traditional process)
Raw materials: Organochlorosilane (e.g., dimethyldichlorosilane)
Process:
a. Hydrolysis: R₂SiCl₂ + 2H₂O → R₂Si(OH)₂ + 2HCl
b. Condensation: R₂Si(OH)₂ → (R₂SiO)ₙ + nH₂O
Features: Mature process, but byproduct hydrochloric acid requires disposal, and the molecular weight distribution is relatively wide.
2. Ring-Opening Polymerization (Mainstream Process)
Raw Materials: Cyclic siloxane (e.g., D4: octamethylcyclotetrasiloxane)
Process:
a. Ring opening under the action of a catalyst (acid or base)
b. Molecular weight control using hexamethyldisiloxane (MM) as an end-capping agent
c. Polymerization: (SiO(CH₃)₂)₄ + MM → Methyl silicone oil
Reaction Equation:
[Ring-Opening Polymerization Reaction Schematic]
Features: Controllable molecular weight, high product purity, suitable for large-scale production
3. Purification and Post-Processing
Catalyst Removal: Neutralization and filtration to remove residual acid/base catalyst
Low-Molecular-Weight Removal: Use a thin-film evaporator or molecular distillation unit to remove cyclic byproducts
Product Formulation: Add functional additives or perform modifications based on specific applications
III. Main Applications of Silicone Oil
1. Daily Chemicals and Pharmaceuticals
Skin Care Products: Excipients and lubricants for a refreshing feel
Shampoos: Hair conditioning agents to improve combing properties
Defoamers: Used in fermentation, papermaking, and wastewater treatment processes
Pharmaceutical Excipients: Ointment bases, medical device lubricants
2. Industrial
Release Agents: Mold release for plastic and rubber products
Lubricants: Mechanical lubrication in high and low temperature environments
Damping Fluids: Filling media for instruments and shock absorption systems
Heat Transfer Media: High-temperature thermal oils for solar systems
3. Electrical and Electronics
Insulating Oil: Filling media for transformers and capacitors
Thermal Grease: Heat dissipation interface material for electronic components
Moisture-Proof Coatings: Protective coatings for circuit boards
4. Special Applications
Diffusion Pump Oil: Working Fluid for High Vacuum Systems
Aerospace: Gyroscope Damping Fluid, Sealing Materials
Auto Care: Main Component of Car Wax and Protective Agents
IV. The Value of Molecular Distillation in Silicone Oil Production
Molecular distillation equipment plays a key role in the refining process of silicone oil production:
Efficient Removal of Low-Molecular-Weight Compounds: Precisely separates cyclic siloxanes (D4-D6) under high vacuum conditions, reducing the low-molecular-weight content in silicone oil products to below 100 ppm.
Maintaining Product Quality: Low-temperature operation prevents oxidation and cross-linking caused by high temperatures.
Improving Product Yield: Through a multi-stage separation system, the recovery rate of by-products such as D4 can be significantly improved. Reaching over 95%
Typical Case: After adopting the Anyan molecular distillation system at a 10,000-ton silicone oil production line, the product's volatile matter (150°C x 24 hours) dropped from 1.5% to below 0.3%.
V. Development Trends
Modified Silicone Fluids: Growing demand for specialty products such as amino silicone fluids and epoxy silicone fluids.
Green Processes: Developing solvent-free synthesis processes to reduce environmental impact.
High-Purification Technology: Purification requirements for electronic-grade and pharmaceutical-grade silicone fluids continue to rise.
Application Expansion: Developing applications in emerging fields such as new energy and biomedicine.
Conclusion
As an important chemical material, silicone oil's manufacturing process has evolved over many years to form a comprehensive system. By providing efficient molecular distillation and purification equipment, Anyan Instruments helps silicone oil manufacturers improve product quality and meet the demands of increasingly high-end applications. With the upgrading of downstream industries, the silicone oil industry will continue to develop towards high-performance, refined, and green products.