The thermal decomposition products of silicone resin depend on its original composition.The thermal aging life of silicone resin insulation paint is often evaluated using the bending assessment method, which involves coating a thin copper sheet with a thickness of 0 08 0 After aging at a predetermined temperature for a certain period of time, a 10mm insulation paint is bent and tested on a round rod with a diameter of 3mm until the paint layer cracks.The performance of silicon paint used for coil impregnation does not change much under conditions of 250 ° C X 1008h, and is suitable as an insulation material for H-class (180 ° C high temperature resistance) motors and electrical appliances.
The heat resistance of organic silicone resin is much better than that of general organic polymers, and its heat resistance can be measured by thermogravimetric method.
polymer | Weight loss at different temperatures for 24 hours/% |
| 250℃ | 300't | 350℃ | 400℃ | 450℃ |
Polydimethylphenylsiloxane Institute | 7.2 | 12 | 32.8 | 36 | 44.7 |
Polydiethylphenylsiloxane kang | 8.3 | | 30. 2 | 38 | |
polyamide | 55.5 | | 94.3 | | |
epoxy resin | 22. 7 | | 93. 1 | | |
polystyrene | 65 | | | | |
alkyd resin | 93.4 | | | | |
The heat resistance of modified silicone resin is worse than that of pure silicone resin, but better than organic resin, generally between silicone resin and corresponding organic resin. Organic silicon coatings still have good light retention after high-temperature use. For example, white organic silicon coatings have a weight loss rate of 10% per 100 hours at 200 ℃, while amino alkyd coatings have a weight loss rate of about 65%.
The heat resistance of silicone resin can also be demonstrated by measuring the thermal elasticity, yellowing resistance, and gloss retention of silicone resin paint films.
For example:
L-Pure methylphenyl silicone resin; 2-Siloxane (75%) polyester copolymer; 3-Siloxane (50%)
Polyester copolymer; 4-Alkyd resin; 5-epoxy resin (TiQ pigment, 1:2 pigment to base ratio).
Comparing the thermal elasticity, yellowing resistance, and gloss retention of the five resins mentioned above, alkyd resin and epoxy resin can maintain elasticity without cracking at 120 ℃. However, under conditions of 180 ℃ and 230 ℃, the paint film cracks and becomes brittle in just a few hours, indicating poor heat resistance of this type of resin.
At 180 ℃ thermal aging, the elastic change of siloxane (75%) polyester copolymer is smaller than that of pure methylphenyl silicone resin and siloxane (50%) polyester copolymer. But at 230 ℃, the elastic change of pure methylphenyl silicone resin is the smallest.
The experiment shows that the thermal elasticity, anti yellowing and gloss retention of the above 5 resins decrease in the following order: pure methylphenyl silicone resin>silica fired polyester copolymer>organic resin.When all resin paint films are heated for a long time at high temperatures, it will lead to further binding of residual active groups (such as - OH) and cracking of organic groups, making the coating hard, cracked, and stripped off the surface of the substrate, losing its proper protective performance.
Our main products are Methyl MQ Silicone Resin Powder,MQ Methyl Silicone Resin Liquid,MQ Silicone Resin,MQ Silicone Resin Powder,Liquid MQ Silicone Resin,Vinyl MQ Silicone Resin,Heat Resistance Silicone Resin.If you have any questions about slicone resin,please contact us.
