A little knowledge of silicone building sealant


Silicone building sealant mainly consists of base glue, filler, cross-linking agent, catalyst and other additives. Base adhesive is the basic material of sealant, which determines the performance of sealant. The base rubber is 107 room temperature vulcanized silicone rubber, the chemical structure is hydroxyl terminated polydimethylsiloxane, the filler is some inorganic powder, such as silica, calcium carbonate, calcium bicarbonate, etc., the role of the filler is to provide strength, hardness, rheological properties, etc. Crosslinking agent and catalyst are the curing system of sealant. Sealant changes from liquid state to elastomer through the reaction of base glue, crosslinking agent, catalyst and water in air.


The production process of sealant is to mix all components of sealant evenly. The common production method is to mix the base material and filler with kneader, and grind with grinder if necessary, and then mix the crosslinking agent, catalyst and other auxiliaries with planetary machine under vacuum.






Compared with other types of sealant, silicone building sealant has good elasticity, high temperature resistance and low temperature flexibility, good weather resistance, ozone resistance and UV resistance, long service life, but the cost of silicone is relatively high, which is usually a little more expensive than other types of sealant, with poor strength, especially tear resistance. It is introduced that water resistance is better than polymerization Polyurethane sealant is poor, and its oil resistance is inferior to polysulfide sealant.






Building sealants can be classified according to different methods. The usual classification method is to classify according to chemical composition. According to the chemical composition of the basic sealant, the sealant can be divided into polysulfide, polyurethane, organosilicon, neoprene, butyl rubber, acrylic rubber, etc. At present, organosilicon, polyurethane and polysulfide are widely used in the market.


The construction sealant is divided into single component and two-component packaging according to the packaging method. Single component packaging is to mix all the raw materials that make up the sealant together and seal them in a plastic bottle or soft packaging aluminum film. When using, the product can be printed out of the packaging with a glue gun. The two-component package is composed of two components a and B. generally, component A is the basic rubber material and component B is the curing agent. Fillers and other additives are added into component A and component B as required. When using, special mechanical equipment (two-component gluer) shall be used to mix component A and component B evenly according to the specified proportion. Component A and component B will undergo chemical reaction and solidify. Neither component a nor component B alone can be used.






According to curing characteristics, sealant can be classified into chemical reaction type, solvent volatile type and heat capacity cold curing type. Silicone sealant belongs to chemical reaction type.


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