What is a Silane Coupling Agent Exactly?

Silane coupling agent is an adhesion promoter for composites and coatings. Silane has the ability to form covalent bonds with inorganic substrates and epoxy resins.

I. General formula of silane coupling agent

The general formula of silane coupling agent usually shows two kinds of functional groups. X is a hydrolyzable group, usually alkoxy, acyloxy, halogen or amine. After hydrolysis, an active silanol group is formed, which can be condensed with other silanol groups (e.g., the surface of siliceous filler) to form a siloxane bond.

Silane coupling agents can also form stable condensation products with other oxides such as aluminum, zirconium, tin, titanium and nickel, or form less stable bonds with oxides of boron, iron and carbon. Alkali metal oxides and carbonates do not form stable bonds with Si-O -. R group is a non hydrolyzable organic free radical. It may be a functional group with some special functions to produce some expected functions.

Most widely used organosilanes have one organic substituent and three hydrolyzable substituents. In most surface treatment applications, the alkoxy group of trialkoxysilane is hydrolyzed to form silanol.

The reaction of these silanes is divided into four steps. Initially, hydrolysis of three unstable groups occurred. This is followed by condensation of oligomers. The oligomer is then hydrogen bonded to the OH group of the substrate. Finally, during drying or curing, a covalent connection is formed with the substrate, accompanied by the loss of water. 

Although described as a step-by-step process, these reactions can occur simultaneously after the initial hydrolysis step. At the interface, there is usually only one bond to the substrate surface for each organosilane silicon. The two remaining silanol groups exist in condensed or free form. Covalent reaction or physical interaction between R group and other phases. If you need this kind of products, Zhongtian provides a reasonable silane coupling agent price for you.

II. Application of silane coupling agent

Silane coupling agent is often used to treat inorganic fillers such as silicon dioxide and carbon black. It plays the role of active agent, coupling agent, crosslinking agent and reinforcing agent in polymers such as rubber and silicone rubber. It has special functions as metal surface antirust agent. Treating metal surface with silane coupling agent can effectively improve its corrosion resistance, oxidation resistance and adhesion with polymer materials such as resin.


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