MS adhesive primarily consists of MS polymer, plasticizer, filler, and functional additives. The following is a detailed description:
MS polymer: MS polymer is the primary component of MS adhesive. Its backbone consists of flexible polyoxypropylene ether segments, while its side chains are end-silyl groups with capping functional groups. This molecular structure gives MS adhesive a low modulus, strong stress relaxation, and high elastic recovery, allowing it to adapt to joint expansion and shear deformation caused by environmental factors such as thermal expansion and contraction of the structure, wind loads, earthquakes, and differential settlement.
Plasticizer: Plasticizers in MS adhesive increase fluidity, reduce hardness, and adjust the modulus. Common plasticizers include dioctyl phthalate (DOP), dibenzyl phthalate (DCP), and dibutyl phthalate (DBP). However, it is important to note that the amount of plasticizer added should be moderate. Excessive amounts can cause migration and exudation, impacting the sealant's performance.
Fillers: Fillers in MS adhesives act as reinforcement, increasing the sealant's strength. For example, when preparing transparent MS adhesives, white carbon black (fumed silica) is commonly used as a reinforcing filler.
Functional Additives: MS adhesives also contain functional additives such as silane coupling agents, catalysts, anti-aging agents, and desiccant agents. Silane coupling agents act like a bridge between the sealant and the substrate, improving adhesion; catalysts accelerate crosslinking and curing at room temperature, shortening the setting time and providing good storage stability; anti-aging agents enhance the MS adhesive's aging resistance; and desiccant agents deplete moisture from the system, improving the sealant's storage stability.
MS adhesives also offer excellent environmental performance. Because their main ingredients are resin, dioctyl acrylate, and calcium powder, they are formaldehyde-free, benzene-free, solvent-free, and odor-free, making them environmentally and human-friendly. MS adhesive cures primarily through hydrolysis and dealcoholization of silane with moisture in the air, followed by condensation. This makes it a hygroscopically curable adhesive. The network structure formed after curing offers excellent weather resistance, water resistance, aging resistance, and durability.
Overall, MS adhesive, with its unique composition and performance, holds a significant position in the construction sealant market, representing a new generation of building sealants.
