Methyl Silicone Resin

Apr 27, 2020

Methyl silicone resin is a kind of methyl silicone resin dissolved in toluene. This resin has a very high SiO2 content (about 80% SiO2 after complete oxidation, calculated according to the solid resin content [DSC]). It is the perfect adhesive for environments above 300 ° C.
Features
· Contains 80% SiO2, calculated according to solid silicone resin content;
· High bonding strength; · High temperature decomposition hardly smokes;
· Outstanding thermal stability.
preparation
Methyl silicone resin can be directly prepared by hydrolysis of methyl trichlorosilane or methyl triethoxysilane.
1 Preparation of methyl silicone resin by hydrolysis of methyl trichlorosilane
Methyl trichlorosilane reacts directly with water to form methyl silicone resin. However, because methyl trichlorosilane contains three active Cl atoms, the hydrolysis polycondensation reaction speed is extremely fast, especially when the hydrolysis reaction is carried out under the conditions of high reaction temperature and high hydrochloric acid concentration, the resulting methyl silicone resin is often highly Crosslinked, insoluble and infusible white solid. In order to produce soluble and fusible products, the hydrolysis reaction is usually 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 200-240 r / min, add 13 parts of ice-water mixture and start stirring to reduce the temperature of the kettle to 0 ℃, and then 1 part of methyltrichlorosilane at a faster speed Add it evenly; the reaction temperature must not exceed 0 ℃ during the feeding process. After the addition, the mixture was stirred for 1 min, and then settled for 4 ~ 5 h. The temperature during the settlement was kept at about 0 ℃. After sedimentation, remove the flocs on the surface, and pour out the upper hydrochloric acid solution; slowly add 70 ℃ hot water under stirring. With the increase of the amount of water, the resin aggregates into a white powder. Wash the coagulum with 70 ℃ hot water until neutral, and then air-dry or vacuum-dry. The resulting methyl silicone resin has the following properties:
Appearance: easy to crush white solid
Solubility: fully soluble in ethanol
Softening point: 40 ~ 47 ℃
Gel time (150 ℃): 9 min
Storage period (at room temperature): 2 ~ 7 d
By heating and kneading it with asbestos, quartz powder and other fillers on a double-roller, it can be made into a molding compound with excellent heat resistance and arc resistance, which is used to process arc-resistant insulated electrical components.
1.2 Preparation of methyl silicone resin in organic solvents
In industrial production, the hydrolysis polycondensation reaction of methyltrichlorosilane is carried out in an organic solvent. Commonly used solvents are: toluene, xylene, isopropanol, n-butanol, etc.
The specific operation method is: add 600 parts of methyl trichlorosilane to a paste composed of 540 parts of toluene, 118 parts of water, and 27 parts of gas-phase white carbon black for hydrolysis reaction; after the reaction, filter and remove acid to obtain 135 Parts methyl silicone resin. The product has a viscosity of 600 mPa at 25 ° C. s, placed at room temperature for 3 hours to solidify into insoluble and infusible materials; if placed at low temperature (below 0 ℃) or formulated 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.
application
Because of its unique high SiO2 content characteristics, it is used for mica insulation coated by rigid silicone resin, resistance coating
performance
Viscosity: sheet PaS
Shear strength:-Mpa
Working time:-min
Working temperature: 400 ℃
Shelf life: 12 months
Curing conditions:-