The Properties of the Finished Silicone Resin Products

Jan 18, 2022

Curing is usually accomplished by condensation of silanols to form siloxanes. When the condensation reaction is in progress, due to the gradual decrease of the silanol concentration, the steric hindrance is increased, and the fluidity is poor, resulting in a decrease in the reaction rate. Therefore, in order to fully cure the resin, the reaction must be accelerated by heating and adding a catalyst. Many substances can catalyze the silanol condensation reaction, including acids and bases, soluble organic salts of lead, cobalt, tin, iron and other metals, organic compounds such as dibutyltin dilaurate, and the like.

The properties of the finished silicone resin products depend on the number of organic groups contained (ie, the ratio of R to Si). Generally, the silicone resin with practical value has a ratio of R to Si in its molecular composition between 1.2 and 1.6. The general rule is that the smaller the value of R:Si, the better the obtained silicone resin can be cured at a lower temperature; the larger the value of R:Si, the better the obtained silicone resin needs to be cured at 200~250 After being baked for a long time at a high temperature of ℃, the hardness of the obtained paint film is poor, but the thermoelasticity is much better than the former.
In addition, the ratio of methyl groups to phenyl groups in organic groups also has a great influence on the properties of silicone resins. The lower the phenyl content in the organic group, the softer the resulting paint film and the faster the condensation, and the higher the phenyl content, the harder and more thermoplastic the resulting paint film. The phenyl content is between 20% and 60%, and the paint film has the best bending resistance and heat resistance. In addition, the introduction of phenyl groups can improve the compatibility of silicone resins with pigments, the compatibility of silicone resins with other silicone resins, and the adhesion of silicone resins to various substrates.

Silicone resin coatings are organic silicon resins or modified organic silicon resins as the main film-forming substances, which are elemental organic coatings, referred to as organic silicon coatings. Elemental organic coatings are the general term for coatings with elemental organic polymers as the main film-forming substances, including organic silicon, organic titanium, organic fluorine, organic aluminum, and organic zirconium coatings. Among them, the output of silicone resin coatings is the largest. Element organic coating is a compound between organic polymer and inorganic compound. It has special thermal stability, insulation, high temperature resistance, chemical resistance, water resistance, weather resistance, etc. It is widely used in the defense industry. , Electrical industry and other industries.

Performance: Voice
Organosilicon generally refers to a polysiloxane with a -Si-O-Si-main bond and organic side chains. Because the main chain of polysiloxane is -SiO-Si-structure, it has the safety, reliability, non-toxic, non-pollution, non-corrosion, aging resistance and long service life of inorganic silica; it also contains organic compounds in the side chain. The group has the characteristics of flexibility and easy processing of polymer materials. Silicone coating is a coating with silicone polymer or silicone modified polymer as the main film-forming substance. It has excellent heat and cold resistance, electrical insulation, corona resistance, radiation resistance, moisture and hydrophobicity, weather resistance, and Contamination and chemical resistance and other characteristics.

The performance of silicone resin coating is as follows:
Silicone resin coating is a relatively expensive insulating coating with outstanding heat resistance, cold resistance and weather resistance.
① The silicone resin coating has strong heat resistance
This is the biggest feature of silicone resin coatings. Pure silicone resin varnish can withstand high temperature of 200-250 ℃, when it is formulated with flake aluminum powder, glass frit, heat-resistant filler, etc., it can withstand high temperature of 300-700 ℃. Modified silicone resin and high temperature resistant pigment can be made Coatings resistant to high temperatures of 200-300 ℃. After the paint film is dried, it is resistant to boiling water and superheated steam.
② Excellent weather resistance of silicone resin coating
Pure silicone resin coatings still have good impact strength and flexibility at -50 ℃. After being modified with polyester, they can be used at low temperatures of -80 ℃.
③ Outstanding insulation of silicone resin coating
It has good electrical insulation under high temperature and humidity conditions, up to class H, and breakdown voltage of 60-100 kV/mm.
④ The organic silicon resin coating has strong chemical resistance
There is no change in the paint film under the condition of 100 ℃, 3% lye immersion for 100 h or 5% saline immersion for 70 h. However, the corrosion resistance of dilute hydrochloric acid and dilute sulfuric acid is not good, and the oil resistance is not strong. It can be used as lubricating oil, and it will become soft when it meets gasoline.
⑤ The silicone resin coating has high mildew resistance
Silicone resin coatings do not contain oily ingredients, mold cannot survive on the paint film, and has better anti-mold performance.
⑥ The silicone resin coating has better adhesion
Silicone resin coatings are suitable for steel, glass, and aluminum as substrates.
⑦ The curing temperature of silicone resin coating is high
Most silicone resin coatings require high temperature baking.
⑧ The silicone resin coating has poor resistance to organic solvents.
⑨ Pure silicone resin coating has low viscosity, and the enamel made with pigment is easy to precipitate.
⑩Silicone coating has very low surface tension and excellent waterproof performance.
Table 1 lists the main performance indicators of mica bonded insulating varnish.
Table 1 Main performance indexes of mica bonded insulating paint