In this article we will learn that the silane coupling agent and silicon used in the polysulfide sealant.
The polysulfide sealant has excellent oil and solvent resistance, low air permeability, good elasticity and superior mechanical properties, can achieve good bond strength to both metal and non-metal. The polysulfide sealant is an important adhesive in many applications, such as aerospace, construction, automobile, ship, machinery, petrochemical and electrical instruments and many other areas. Especial, the polysulfide sealant can be used in the sealing of hollow glass and waterproofing of expansion joints in large water conservancy projects.
Polysulfide sealant is made of liquid polysulfide rubber as the main agent, with appropriate amount of plasticizer, viscosifier, filler, reinforcing agent, coupling agent, curing agent, accelerator, etc. As a kind of formulated chemical, polysulfide sealant is actually a mixture of organic and inorganic material and in order to improve the bonding strength on the surface of substance, the silane coupling agent is needed. The silane coupling agent is a compound contains organic group and hydrolyzable alkoxide group in one molecule. The hydrolysable alkoxide group, which always being the silicon-functional ethoxy-group or methoxy-group hydrolyze in the presence of water to form reactive silanols, which can be bonded to an inorganic substrate; the organophilic group can interact with a suitable polymer. Therefore, the silane coupling agent can improve the bonding strength of surface between organic and inorganic materials, even the dosage is very small (maybe only a few thousandths or a few hundredths of a percent), but significant. Commonly use products at present are HD-E8133, HD-M3133, HD-M2133, etc.
HD-E8133：γ-Aminopropyltrimethoxy silane which contains -NH group can react with many organic group such as epoxy group , can soluble with water and easy to use.
HD-M3133：γ-Glycidoxypropyltrimethoxy silane which contains epoxy group and can bond to various kinds of polymer. As epoxy resin is the common tackifier for polysulfide sealant， adding epoxy resin into polysulfide sealant can exert an auxiliary effect on viscosity increasing. The reinforcement of effect use HD-M3133, sometimes, is better than the amino group silane.
HD-M2133：γ-Methacryloxypropyltrimethoxy silane, suitable for composites filled with inorganic materials and can improve properties of mechanical strength and translucency, especially can improve the wet properties of polysulfide sealant.