Methyl Silicone —- Silicone Product Encyclopedia

Methyl silicone is a methyl silicone resin dissolved in toluene. This resin has a high SiO2 content (approximately 80% SiO2 after complete oxidation, calculated as solid resin content [DSC]) and is the perfect adhesive for use in environments above 300°C.

·Contains 80% SiO2, calculated based on solid silicone content;

· High bonding strength; · Almost no smoke when decomposed by high temperature;

· Outstanding thermal stability.

Methyl silicone resin can be directly prepared by hydrolysis of methyltrichlorosilane or methyltriethoxysilane.
1 Preparation of methyl silicone resin by hydrolysis of methyltrichlorosilane
Methyl trichlorosilane reacts directly with water to generate methyl silicone resin. However, because methyltrichlorosilane contains three active Cl atoms, the hydrolysis and polycondensation reaction is extremely fast, especially when the hydrolysis reaction is carried out under the conditions of high reaction temperature and high concentration of hydrochloric acid, the resulting methyl silicone resin is often highly Cross-linked, insoluble and infusible white solid. In order to produce soluble and meltable products, hydrolysis reactions usually need to be carried out under milder conditions, such as excess ice-water or organic solvents.
1.1 Preparation of methyl silicone resin in ice-water
In an acid-resistant reaction kettle with a stirrer speed of 200 to 240 r/min, add 13 parts of the ice-water mixture, start stirring, and reduce the temperature of the kettle to 0°C. Then add 1 part of methyltrichlorosilane at a faster speed. Add evenly; the reaction temperature during the addition process must be strictly controlled not to exceed 0 ℃. After adding the materials, stir for 1 minute, and then settle for 4 to 5 hours. The temperature during the settling process is kept at about 0°C. After settling, remove the floc on the surface and pour out the upper hydrochloric acid solution; slowly add 70°C hot water with stirring. As the amount of water increases, the resin condenses into white powder. Wash the agglomerate with 70 ℃ hot water until neutral, and then�After air drying or vacuum drying, the obtained methyl silicone resin has the following properties:
Appearance: easily crushed white solid
Solubility: completely soluble in ethanol
Softening point: 40～47 ℃
Gel time (150 ℃): 9 min
Storage period (at room temperature): 2～7 d
By heating and mixing it with fillers such as asbestos and quartz powder on a double-roller machine, it can be made into a molding compound with excellent heat resistance and arc resistance, which can be used to process arc-resistant insulating electrical components.
1.2 Preparation of methyl silicone resin in organic solvent
In industrial production, the hydrolysis and polycondensation reaction of methyltrichlorosilane is carried out in organic solvents. Commonly used solvents include: toluene, xylene, isopropyl alcohol, n-butanol, etc.
The specific operation method is: add 600 parts of methyltrichlorosilane to a paste composed of 540 parts of toluene, 118 parts of water, and 27 parts of gas phase silica for hydrolysis reaction; after the reaction is completed, filter and remove acid to obtain 135 parts of methyl silicone. The product has a viscosity of 600 mPa at 25°C. s, it will solidify into an insoluble and infusible substance if left at room temperature for 3 hours; if left at low temperature (below 0 ℃) or made into a solution, the storage period can be extended to 6 to 12 months.
This product can be used as a moisture-proof, wear-resistant and weather-proof surface coating for non-transparent materials such as porous stone and wood products. [1]

Because of its unique high SiO2 content, it is used for rigid silicone resin-coated mica insulation and resistive coatings

Viscosity: Flake PaS

Shear strength: – Mpa

Working hours: – min

Operating temperature: 400 ℃

Shelf life: 12 months

Curing conditions: –