How are silicone resins formed?
Since the hydrolysis process of imported silicone resins is an exothermic process, the hydrolysis temperature of silicone resins has a great relationship with the formation of gels. Gels are more likely to be produced at lower temperatures, because the difunctional group is monotonic when the hydrolysis temperature is low. There is a large gap between the activity of the trifunctional group and the activity of the trifunctional group. The difunctional monomer is more likely to self-polymerize to form a highly crosslinked gel. As the reaction temperature increases, the activity of the difunctional monomer increases and it also participates in the reaction with stirring. . As the reaction temperature of the silicone resin is further increased, the silanol formed is easily further cross-linked to form the silicone resin.
A special-effect catalyst is used to catalyze the condensation reaction of methylphenyl hydrolyzed silanol. The selective catalytic characteristics of the nucleophilic reaction make the phenyl substitution position in the methylphenyl silanol molecular chain preferentially activated, thereby triggering the silicon at the phenyl substitution position. The hydroxyl group undergoes a condensation reaction before the silyl hydroxyl group at the methyl substitution position to form a polymer chain of methylphenyl silicone resin. In this way, the silyl hydroxyl group at the methyl substitution position is partially retained in the polymer. The reactivity is significantly higher than the silyl group corresponding to the phenyl group, so a highly reactive methylphenyl silicone resin is obtained. The large proportion of low-steric hindrance and high-reactive methyl-substituted silyl groups retained in the silicone polymer makes the adhesion properties of such silicone resin cured products to the substrate improved.
With the development of the coatings industry, powder coatings have been widely used in the coating of metal substrates. In recent years, the development and application of functional products such as antibacterial, high wear resistance, and heat resistance have become powder coatings. Direction of development. Heat-resistant powder coating refers to a powder coating that can withstand temperatures above 200 ° C for a long time, has a good coating film, and enables the protected object to function normally in a high-temperature environment. From the thermal stability mechanism of polymers, the heat resistance of polymers mainly depends on their molecular structure. The thermal stability of polymers can be improved by introducing larger or more polar side groups on the main chain and increasing the intermolecular interaction force. Another way to improve the heat resistance of powder coatings is to add heat resistant pigments and fillers to the polymer. Commonly used pigments and fillers are aluminum powder, mica powder, stainless steel powder, cadmium powder, silicon dioxide, and the like.