Silicone oil production formulations utilize chlorosilanes and alcohols as primary raw materials, proceeding through three reaction stages: hydrolysis, condensation, and telomerization (or equilibration). Molecular weight and purity are precisely controlled via the choice of catalyst, mixing ratios, and reaction conditions.
Raw Material Selection
Primary materials: Chlorosilanes (e.g., dimethyldichlorosilane, purity ≥99%) and alcohol solvents (e.g., methanol, ethanol).
Auxiliary materials: End-capping agents (to regulate molecular chain length), acidic catalysts (e.g., acid-activated clay or resin to accelerate condensation), and neutralizing agents (e.g., sodium carbonate to treat residual acidic substances).
Formulation Examples
High-hydrogen silicone oil formulation: Mix high-hydrogen silicone oil, octamethylcyclotetrasiloxane, and hexamethyldisiloxane in a ratio of 1–5 : 10–100 : 2–10; add catalyst at 1–10% of the total mass.
Cyclic telomerization/equilibration formulation: Charge heptamethyltrisiloxane and octamethylcyclotetrasiloxane at a ratio of 5–30 : 10–100; catalyst dosage as above.
Process Flow
Hydrolysis reaction: Chlorosilane reacts with water at 40–60°C to produce silanols; control the removal of the hydrochloric acid byproduct.
Condensation reaction: Silanols condense in the presence of an acidic catalyst; the temperature is raised to 80–120°C to form siloxane chains.
Telomerization/Modification: Add end-capping agents and cyclic siloxanes; adjust the degree of polymerization using tetramethylammonium hydroxide as a catalyst; reaction time is 2–6 hours.
Post-processing: Neutralization, water washing, and dehydration distillation; separate low-boiling components to obtain the final product (viscosity range: 50–100,000 cSt).
Precautions
Toxicity protection: Chlorosilane vapors must be contained and collected; the operating area must be equipped with eyewash stations and gas masks.
Parameter control: Maintain the pH at 2–3 during the hydrolysis stage; the heating rate during the condensation stage must be ≤5°C/min.
Catalyst regeneration: The acid-activated clay catalyst requires calcination at 500°C for 2 hours after each batch to restore its activity.