Types of sealants.
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Author:DiMei
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Published time: 2018-12-01
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Do you really know the types of sealants?
Do you really know the types of sealants?
1. Classification by base polymer
Including: silicone, polyurethane, polysulfide, acrylic acid, butyl, asphalt and oil-based resin modified products. Among them, silicone, polysulfide and polyurethane are the most widely used room temperature curing elastic sealants in China, especially silicone sealant products.
Due to its special molecular structure, silicone sealants have the molecular structure of both inorganic and organic polymers. The original glue of silicone rubber is a polymer mainly composed of Si-O. The bond energy is 106 Kcal/mol, and the usual polymer materials have small CO and CC bond energies of 80 and 85.2 cal/mol, respectively. In other words, if the Si-O bond is interrupted, higher energy is inevitable. Therefore, silicone rubber is stable, with superior UV, ozone, weathering, temperature resistance and single-component, two-component applications. It can also produce products with different performance requirements according to the needs of the building. Especially in the structural bonding application of hidden frame glass curtain wall, other materials are irreplaceable. And China's raw material industry in the production of silicone sealant is relatively large and mature in terms of polysulfide and polyurethane. At present, silicone building sealant products account for more than 60% of the use of building sealant in China. Foreign modified silicone products are also used in construction. At present, China is limited to other fields.
As early as the 1960s, the polysulfide sealant used in construction was used in the oil and solvent resistance of aircraft and aviation. It was also used in the sealing of building joints in China in the 1980s due to the production cost of raw materials. High, has been basically replaced by silicone products. However, polysulfide sealant has good gas barrier properties, oil resistance and solvent resistance. It is still widely used in the manufacture of insulating glass, and is partly used in construction joint sewage, garbage dump, oil storage structure and steel structure anti-corrosion seal.
The diversity of the molecular structure of polyurethanes allows the manufacture of a wide range of different products for a wide range of materials. And because of its flexible molecular chain, it has good vibration resistance and fatigue performance, especially suitable for bonding of different materials and bonding to flexible materials, and also has excellent low temperature resistance, and is used in many industries. Very wide. In the field of construction, the application of this material in the United States, Japan, Germany and other developed countries is close to silicone products. At present, due to the backwardness of the raw material industry in China, the development of sealant products is subject to certain constraints. There are also less flexible sealing paste products including butyl, acrylic, asphalt and oil-based resins. These products have low elasticity and can be applied to parts where the mechanical joint displacement of construction joints is low.
