Silane coupling agent
It is a type of organic silicon compound that contains two different chemical properties at the same time. It is used to improve the actual bonding strength between polymers and inorganic substances. This may refer either to an increase in true adhesion or to improvements in wetting, rheology and other handling properties. Coupling agents may also modify the interface region to enhance the boundary layer between the organic and inorganic phases.
Therefore, silane coupling agents are widely used in adhesives, coatings and inks, rubber, casting, fiberglass, cables, textiles, plastics, fillers, surface treatment and other industries.
The classic product can be represented by the general formula XSiR3.
In the formula, X is a non-hydrolyzable group, including alkenyl groups (mainly Vi) and hydrocarbon groups with Cl, NH2 and other functional groups at the end, that is, carbon functional groups ;R is a hydrolyzable group, including OMe, OEt, etc.
X The functional groups in During hydrolysis, Si-R is converted into Si-OH, and by-product HR is produced, such as MeOH, EtOH, etc. Si-OH can undergo condensation and dehydration reactions with Si-OH in other molecules or Si-OH on the surface of the substrate to be treated to form Si-O-Si bonds, and can even react with certain oxides to form stable Si-O bonding allows silane to connect with inorganic substances or metals.
Common silane coupling agents are:
Sulfur-containing silanes: bis-[3-(triethoxysilane)-propyl]-tetrasulfide, bis-[3-(triethoxysilane)-propyl]- disulfide
Aminosilane: γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane
Vinyl silanes: vinyl triethoxysilane, vinyl trimethoxysilane
Epoxysilane: 3-glycidyloxypropyltrimethoxysilane
Methacryloyloxysilane: γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriisopropoxysilane
The mechanism of action of silane coupling agent:
Silane cross-linking agent
Refers to silanes containing two or more silicon functional groups, which can play a bridging role between linear molecules, therebymaking multiple linear molecules or Slightly branched macromolecules and polymers are bonded and cross-linked with each other to form a three-dimensional network structure, which promotes or mediates the formation of covalent bonds or ionic bonds between polymer molecular chains.
Cross-linking agent is the core part of one-component room temperature vulcanized silicone rubber and is the basis for determining the cross-linking mechanism and classification naming of products.
According to the different condensation reaction products, single-component room temperature vulcanized silicone rubber can be divided into deacidification type, deketoxime type, dealcoholization type, deamination type, deamidation type, and deacetone type. and other different types, among which the first three are general-purpose products produced in large quantities.
Take methyltriacetoxysilane cross-linking agent as an example. Since the condensation reaction product is acetic acid, it is called deacetic acid room temperature vulcanization silicone rubber.
Generally speaking, cross-linking agents and silane coupling agents are different, but there are exceptions. For example, the α series silane coupling agents represented by anilinomethyltriethoxysilane are listed in single Component dealcoholization type room temperature vulcanization silicone rubber has been widely used.
Common silane cross-linking agents are:
Dealcoholized silanes: alkyltriethoxy, methyltrimethoxy
Deacidified silanes: triacetoxy, propyltriacetoxysilane
Deketoxime-type silanes: vinyl tributyl ketone oxime silane, methyl tributyl ketone oxime silane
The mechanism of action of silane cross-linking agent:
Simply put, cross-linking agents connect the same things; coupling agents connect different things. So, do you now know how to distinguish silane coupling agents and silane cross-linking agents?
