Performance Classification and Application of Silicone Resin Coatings

Dec 14, 2020

Silicone resin coating is a kind of elemental organic coating, which takes silicone resin or modified silicone resin as main film-forming material. Elemental organic coatings are the general name of coatings with organic polymers as the main film-forming materials, including organosilicon, organic titanium, organic fluorine, organic aluminum, organic zirconium coatings, etc. Among them, the output of silicone resin coating is the largest. Element organic coating is a kind of compound between organic polymer and inorganic compound. It has special thermal stability, insulation, high temperature resistance, chemical resistance, water resistance, weather resistance and so on. It is widely used in national defense industry, electrical industry and other industries.


Performance:
Organosilicon generally refers to polysiloxanes with - Si-O-Si - primary and organic side chains. Because the main chain of polysiloxane is SiO Si structure, it has the properties of inorganic silica, such as safety and reliability, non-toxic, pollution-free, non-corrosion, aging resistance and long service life; and because of the organic groups in the side chain, it has the characteristics of flexibility and easy processing of polymer materials. Silicone coating is a kind of coating with silicone polymer or silicone modified polymer as the main film-forming material. It has excellent heat and cold resistance, electrical insulation, corona resistance, radiation resistance, moisture and water repellency, weather resistance, stain resistance and chemical corrosion resistance.

The properties of silicone resin coating are as follows:
Silicone resin coating is a kind of insulation coating with outstanding heat resistance, cold resistance and weather resistance.
① High heat resistance of silicone resin coating
This is the biggest characteristic of silicone resin coating. The pure silicone resin varnish can withstand 200-250 ℃ high temperature, and the coating prepared with flake aluminum powder, glass frit and heat-resistant filler can withstand 300-700 ℃. The modified silicone resin and high-temperature pigment can be used to prepare the coating with high temperature resistance of 200-300 ℃. The film is resistant to boiling and superheated steam after drying.
② Excellent weatherability of silicone resin coating
The pure silicone resin coating still has good impact strength and flexibility at - 50 ℃. It can be used at - 80 ℃ after modified by polyester.
③ The insulation of silicone resin coating is outstanding
Under high temperature and humidity conditions, it has good electrical insulation, up to grade H, and breakdown voltage up to 60-100 kV / mm.
④ The silicone resin coating has strong chemical corrosion resistance
The film has no change under the conditions of 100 ℃, 3% alkali solution soaking for 100 h or 5% salt water soaking for 70 H. However, the corrosion resistance of dilute hydrochloric acid and sulfuric acid is poor, and the oil resistance is not strong. It can be used as lubricating oil, and will become soft when meeting gasoline.
⑤ Silicone resin coating has high mildew resistance
Silicone resin coating has no oil-bearing components, mold can not survive on the film, and has good mildew resistance.
⑥ The adhesion of silicone resin coating is good
Silicone resin coating is suitable for steel, glass, aluminum matrix.
⑦ The curing temperature of silicone resin coating is hig
Most silicone coatings require high temperature baking.
⑧ The organic solvent resistance of silicone resin coating is poor.
⑨ The pure silicone resin coating has low viscosity and is easy to precipitate with the enamel made of pigment.
⑩ Silicone coating has very low surface tension and excellent waterproof performance.

Classification:
(1) According to coating components
Silicone resin coatings can be divided into pure organic resin coatings and modified silicone resin coatings.
Pure silicone coating is formed by dissolving pure silicone resin in xylene. It has good heat resistance, weather resistance, corrosion resistance and insulation, but its mechanical strength and adhesion are poor, and the drying time is long. But it can be modified with other resins. The representative varieties are W30-11 and W30-12.
Modified silicone resin coating is a kind of coating with modified silicone resin as film-forming material, including the following three kinds.
① Cold mixed silicone coating is a kind of coating made by cold mixing silicone resin with other organic resins. The resins with good miscibility include phenolic resin, methacrylic acid resin, amino resin, alkyd resin, epoxy resin, polyester resin and ethyl fiber resin. After adding these resins, the curing temperature of the coating decreases and the mechanical strength increases. The representative paint grades are w61-42, w61-37, w61-34, etc.
② Polycondensation type silicone coating is a kind of coating prepared by cold mixing organic silicone intermediate containing active groups with other organic resins. The adhesion, solvent resistance, flexibility and color retention of the coatings are better than those of the cold mix coatings, but the heat resistance is reduced.
③ The copolycondensation and cold mixing silicone coatings are the coatings prepared by cold mixing the copolymerized silicone resin with other resins. The adhesion, color retention and flexibility of the coatings are similar to those of the copolycondensation coatings, and they can be dried at room temperature and are cheap. The representative paint grade is w61-1.
(2) According to the application of coating
Silicone coatings can be divided into silicone coatings, heat-resistant coatings, silicone coatings.
① Silicone heat-resistant coating is a kind of coating which can withstand more than 200 temperature for a long time. Silicone heat-resistant coatings have excellent heat-resistant properties and begin to decompose at about 300 ℃. It is widely used in heat-resistant coatings. The common silicone heat resistant coatings in China are listed in Table 2. The performance of silicone heat-resistant coating is related to the methyl / phenyl value contained in the silicone oligomer, because the phenyl group has better heat resistance and poor physical and mechanical properties than the methyl group.
The pigments used in silicone heat-resistant coatings should have heat resistance, and appropriate pigments should be selected according to the actual requirements.