I. What Is Dimethyl Silicone Oil?

Dimethyl silicone oil is a polymer composed of an inorganic silicon-oxygen backbone with methyl side groups. It is a colorless, transparent liquid at room temperature and is insoluble in water.

Dimethyl silicone oil has a wide range of applications due to its broad viscosity range (0.65–1,000,000 mm²/s), low viscosity-temperature coefficient, high coefficient of thermal expansion, high flash point, excellent resistance to both high and low temperatures, outstanding weatherability, resistance to chemical corrosion and radiation, low surface tension, high electrical insulation, and excellent shear stability.

II. Applications of Dimethyl Silicone Oil

1. Textile Auxiliary Agent

Dimethyl silicone oil is widely used as a lubricant for raw fibers and cotton, a spinning lubricant, and a sewing thread smoothing agent. Low-viscosity methyl silicone oil is commonly used for lubricating raw yarns and cotton fibers, while medium- to high-viscosity methyl silicone oil is used as a sewing thread smoothing agent. Owing to its excellent thermal stability and low viscosity-temperature coefficient, dimethyl silicone oil is extensively used in the formulation of spinning lubricants, particularly in the spinning of nylon and polyester fibers, where it helps prevent yarn breakage and fiber loosening.

2. Defoamer Production

Because of its low surface tension, insolubility in water, vegetable oils, and high-boiling mineral oils, as well as its excellent chemical stability and non-toxic nature, dimethyl silicone oil is widely used as a raw material for defoamers. It can be blended with fumed silica to form silicone paste, which is then emulsified to produce water-based silicone emulsion defoamers.

Silicone defoamers are extensively used in the petroleum, chemical, pharmaceutical, food processing, textile, printing and dyeing, and paper industries. The addition of only 10–100 ppm is sufficient to achieve excellent defoaming performance.

3. Mold Release Agent Production

Due to its non-stick properties toward rubber, plastics, and metals, as well as its excellent film-forming ability, dimethyl silicone oil is widely used in the manufacture of mold release agents for various rubber and plastic products.

4. Lubricant

Dimethyl silicone oil can be used as a lubricant for rubber and plastic bearings and gears. Lubricants based on dimethyl silicone oil are generally formulated in the form of silicone grease to provide superior lubrication and durability.

5. Other Applications

Thanks to its high flash point, colorless and transparent appearance, odorless and non-toxic characteristics, dimethyl silicone oil is widely used as a heat transfer medium in oil baths and thermostatic systems in industries such as steel, glass, and ceramics, as well as in scientific research applications.

Its excellent shear stability also makes it suitable for use as hydraulic fluid, particularly in aviation hydraulic systems. In addition, treating rayon spinning heads with dimethyl silicone oil can eliminate static electricity and improve yarn drawing quality.