What do you know about the properties of methyl silicone oil?
What is methyl silicone oil: [Printing and dyeing learning and exchange] dry recommendation, methyl silicone oil is generally colorless, odorless, non-toxic, non-volatile liquid, insoluble in water, methanol, ethylene glycol, and can be mutually soluble in benzene, dimethyl ether, carbon tetrachloride or kerosene, slightly soluble in acetone, dioxane, ethanol and butanol. Due to the small intermolecular force of methyl silicone oil, the molecular chain is helical and the organic groups can rotate freely, so it has excellent spreading performance, lubricity, high and low temperature resistance, weather resistance, radiation resistance, high flash point, low surface tension and physiological inertia, etc. It is widely used in daily chemical, mechanical, electrical, textile, coating, pharmaceutical and food industries.
Methyl silicone oil is a linear polyorganosiloxane with Si-O-Si as the main chain, 2 methyl groups attached to Si, and trimethylsiloxane capped, which is liquid at room temperature, and its structural formula is as follows:
Properties of Methyl Silicone Oil
Methyl silicone oil has many special properties:
■ Good heat resistance
Silicone oil molecules have excellent heat resistance because the main chain is composed of -Si-O-Si- bonds, with a structure similar to that of inorganic macromolecules, and its bond energy is very high.
■ Good oxidation stability and weathering resistance
■ Good electrical insulation
Silicone oil has good dielectric properties, with the change of temperature and the number of waves, its electrical properties change very little. The dielectric constant decreases with increasing temperature, but the change is very small. The power factor of silicone oil is low and increases with temperature rise, but there is no rule with frequency change. Volume resistivity decreases with temperature rise.
■ Good hydrophobicity
Although the main chain of silicone oil is composed of polar bonds Si-O, but because of the side chain of the non-polar group alkyl toward the outside of the directional arrangement, preventing water molecules from entering the interior, playing a hydrophobic role. The interfacial tension of silicone oil to water is about 42 dynes/cm, when diffused on top of glass, due to the water repellency of silicone oil, the formation of a contact angle of about 103 °, comparable to paraffin.
■ Viscosity and temperature coefficient is small
Silicone oil has a low viscosity and a small change with temperature, which is related to the spiral structure of the silicone oil molecule. Silicone oil is a class of oil with the best viscosity-temperature characteristics among all kinds of liquid lubricants, and this characteristic of silicone oil is very meaningful for damping equipment.
■ High compression resistance
Silicone oil has high compression resistance due to the helical structure of its molecules and the large intermolecular distances. By utilizing this property of silicone oil, it can be used as a liquid spring, which can be greatly reduced in size compared to mechanical springs.
Low surface tension
Low surface tension is a characteristic of silicone oil. Low surface tension indicates high surface activity, so silicone oils have excellent antifoaming and antifoaming properties, isolation from other substances, and lubricating properties.
■ Non-toxic, odorless and physiologically inert
From a physiological point of view, silicone polymers are among the least reactive compounds known. Dimethicones are biologically inert and have no rejection with animal organisms. Therefore, they have been widely used in the sectors of surgery and internal medicine, pharmaceuticals, food and cosmetics.
■ Good lubrication
Silicone oil has many excellent properties as a lubricant, such as high flash point, low freezing point, thermal stability, viscosity with temperature change is small, does not corrode the metal as well as rubber, plastic, paint, organic paint film has no adverse effects and low surface tension, easy to spread on the surface of the metal and other characteristics. In order to improve the steel-to-steel lubricity of silicone oil, can be added to the lubricity additives that can be miscible with silicone oil. The introduction of chlorophenyl group on the silicone chain or the replacement of dimethyl with trifluoropropyl methyl can greatly improve the lubricating properties of silicone oil.
