What is dimethicone and its application?
Dimethicone is also known as methyl silicone oil and polydimethylsiloxane liquid. Colorless transparent viscous liquid. Tasteless. Odorless. Non-toxic. The molecular formula is CH3[Si(cH3)2]nSi(CH3)3. The average molecular weight is 5000-100000. Depending on the molecular weight, the kinematic viscosity ranges from 1.0×10-6 to 100000×10-6 square meters per second. The long-term use temperature range is -50～180℃, and it can be used for a long time at 200℃ under the isolation of air or in inert gas. The viscosity coefficient is 0.31～0.61. The surface tension is 1.59～2.15×10-4N/cm. Dielectric constant (23℃, 100Hz) 2.18～2.17. Volume resistivity (23°C) 1.0×1014～1.0×1016Ωcm3. Dielectric loss tangent value (23℃, 100Hz) 0.00002～0.00004. The breakdown voltage intensity is 13.7～17.7kV/mm. It is soluble in benzene, toluene, xylene, ether, partially soluble in ethanol, butanol, acetone, and insoluble in cyclohexanol, methanol, paraffin oil, and vegetable oil. It has excellent water repellency and moisture resistance, good light transmittance, and chemical stability. It is widely used as insulating, heat-resistant, moisture-proof filler, high-efficiency defoamer, mold release agent, lubricant and surface treatment agent. It is prepared by reacting octamethylcyclotetrasiloxane and hexamethyldisiloxane under the action of concentrated sulfuric acid or tetramethylammonium hydroxide catalyst.
It is widely used in skin care creams, hand creams, skin cleansers, sunscreen products, shaving creams, deodorants, bath lotions, hair conditioners and other cosmetics. It can also be used as a polishing agent and also used as a defoamer. It has the ability to dissolve a variety of vitamins, hormones, fungicides, and anti-inflammatory agents. It has good compatibility with various components of cosmetics and can form a thin layer on the skin surface. It has hydrophobicity, which can keep vitamins and drugs on the skin surface. For a long time, it has a stable nutritional effect, can also make hair soft and smooth, improve combing and increase gloss.
Dimethicone is widely used as a release agent for various materials such as plastics and rubber. It has excellent high and low temperature resistance, light permeability, electrical properties, water repellency, moisture resistance and chemical stability. Generally used for high-temperature release of large molded objects, such as phenolic resin and unsaturated polyester laminates. In order to meet the needs of different uses, silicone oil is usually processed into the form of solution, emulsion and silicone paste, and its composition and use are as follows.
The solution is prepared by dissolving silicone oil in organic solvents such as carbon tetroxide, toluene or xylene, and the concentration is generally 0.5-2%. Suitable for use at 60～110℃.
The emulsion is prepared from silicone oil, emulsifier and water, and is diluted to 0.5-2.0% during use. It is suitable for processing occasions above 120°C and products with complex shapes.
Silicone paste is smelted from silicone oil and ultra-fine silica. Good heat resistance, suitable for products with large surface area, smooth and simple shape.
Simethicone is a polymer of dimethyl siloxane. There are different grades of products depending on the degree of polymerization. As a condensing agent for dripping pills, dimethyl silicone with appropriate relative density and viscosity should generally be selected according to the nature of the matrix. Silicone oil. All water-soluble substrates can be well formed in it, but the cost is relatively high.