The methyl silicone resin can be directly prepared by hydrolysis of methyltrichlorosilane or can be prepared from methyltriethoxysilane.
1 Preparation of methyl silicone resin by hydrolysis of methyltrichlorosilane
Methyltrichlorosilane reacts directly with water to form methyl silicone resin. However, since methyltrichlorosilane contains three active Cl atoms, the hydrolysis polycondensation reaction rate is extremely fast, especially in the case of high reaction temperature and high hydrochloric acid concentration, and the obtained methyl silicone resin is often highly Crosslinked, insoluble and infusible white solid. In order to produce a soluble meltable product, it is usually necessary to carry out the hydrolysis reaction under milder conditions such as an excess of ice-water or an organic solvent.
1.1 Preparation of methyl silicone resin in ice-water
In an acid-resistant reactor with a stirrer speed of 200-240 r/min, add 13 parts of ice-water mixture, start stirring, reduce the temperature of the kettle to 0 °C, and then transfer 1 part of methyltrichlorosilane at a faster rate. Add evenly; the feeding process must be strictly controlled to a temperature not exceeding 0 °C. After the addition, the mixture was stirred for 1 min, then settled for 4 to 5 h, and the temperature of the sedimentation process was maintained at about 0 °C. After settling, the floc on the surface was removed, and the upper hydrochloric acid solution was decanted; the hot water at 70 ° C was slowly added under stirring, and the resin was agglomerated into a white powder as the amount of water increased. The coagulum is washed with 70 ° C hot water to neutrality, then air dried or vacuum dried, and the resulting methyl silicone resin has the following properties:
Appearance: easy to crush white solid
Solubility: Total dissolution in ethanol
Softening point: 40 ~ 47 °C
Gel time (150 °C): 9 min
Storage period (at room temperature): 2 to 7 days
It is heated and kneaded on a twin-roller with a filler such as asbestos and quartz powder, and can be used as a molding compound excellent in heat resistance and arc resistance for processing arc-resistant insulating electrical components.
1.2 Preparation of methyl silicone resin in organic solvent
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 and the like.
The specific operation method is as follows: 600 parts of methyltrichlorosilane is added to a paste composed of 540 parts of toluene, 118 parts of water, and 27 parts of fumed silica to carry out a hydrolysis reaction; after the reaction, filtration and acid removal are carried out to obtain 135. Methyl silicone resin. The product has a viscosity of 600 mPa at 25 °C. s, after standing at room temperature for 3 h, it will solidify into insoluble and infusible; if it is placed at low temperature (below 0 °C) 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, weatherproof surface coating for non-transparent materials such as porous stone and wood products.
Contact：Sharon Song(Sales manager)
Zhejiang Runhe Organosilicone New Material Co.,Ltd(Factory)
Zhejiang Runhe Chemical New Material Co.,Ltd(Exporter)
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