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Question:

What is the reason that the performance of self - curing resin is lower than that of heat - curing resin?

What is the reason that the performance of self - curing resin is lower than that of heat - curing resin?

Answer:

Weather resistanceWeather resistance is one of the main characteristics of silicone resin and is widely used as base material for weather resistant coatings. The simplest way to test the weather resistance of coatings is to expose the test panels coated with silicone to the outside, and to observe the changes in gloss or color of the coating, as well as cracking. But because sunlight exposure, the specimens received in outdoor temperature changes, rain, snow, wind and frost attack, floating in the air and dust pollution of various chemical substances are not the same, so it is difficult to have strict standards. Making comparison and analysis difficult. In addition, the results of the cycle is long (in years), so the use of this method has been less, and now use accelerated aging test machine, to obtain weather resistance data. Under the condition of accelerated test, the coating gloss 60%, alkyd resin coating is 250h, containing 30% (mass fraction) silicone alkyd resin coating is 750H, containing 50% (mass fraction) silicone alkyd resin coating is 2000h, and the silicone coating after 3000h, the gloss retention is still higher than 80%. Among the many factors that cause coating aging, sunlight, especially ultraviolet radiation, is the major cause of low gloss and powder surface. It is known that the light spectrum in the wavelength spectrum of the solar spectrum on the earth's surface is very sensitive, which is the root cause of the poor weather resistance of organic resins. Known, methyl siloxane hardly absorb the ultraviolet light, containing PhSiO1.5 or Ph2SiO links are only following the absorption of 280nm silicone (including a small amount of ultraviolet light), the sun has little effect on the silicon resin, which is the main reason of silicon resin coating with excellent weatherability.
Epoxy resins refer to organic compounds containing two or more epoxy groups in the molecule. Except for some of them, the relative molecular weight of them is not high enough. (two). The molecular structure of epoxy resin is characterized by the presence of active epoxy groups in the molecular chain. The epoxy group can be located at the end of the molecular chain, intermediate or ring like structure. Because the molecular structure contains active epoxy groups, they can react with various types of curing agents to form insoluble polymers with three directions network structure. Any polymer compound with epoxy groups in its molecular structure is collectively referred to as an epoxy resin. The cured epoxy resin has excellent physical and chemical properties, it is of metal and nonmetal material surface has excellent adhesion strength, good dielectric properties, set product shrinkage of small, good dimensional stability, high hardness, good flexibility, and the most stable in alkaline solvent, which is widely used in various departments of defense the national economy, and for pouring, dipping, laminated materials, adhesives, coatings. Basic characteristics
Silicone resin is a mesh structure of highly cross-linked polyorganosiloxane, usually with various mixtures of three methyl chlorosilane, two methyl two phenyl chlorosilane and three chloro silane, two phenyl chlorosilane two or two methyl phenyl chlorosilane, in the presence of organic solvents such as toluene, water at low temperature by decomposition. The acid hydrolysate. The initial product of hydrolysis is a cyclic, linear, and crosslinked polymer mixture that usually contains quite a few hydroxyl groups. The hydrolysate is washed to remove the acid, the neutral primary polycondensation is oxidized in air or further condensed in the presence of the catalyst, and finally a highly cross-linked three-dimensional network structure is formed.

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