Due to its special structural composition, silane has been successfully used as an adhesion promoter and surface treatment agent. Silane has gradually become an indispensable component in coatings and ink systems. Whether used as an additive or as a separate primer, it will give excellent performance to coatings and inks. For example, improve the physical and mechanical strength, adhesion, durability, weather resistance, scrub resistance, scratch resistance and abrasion resistance of the coating, high pigment dispersion, etc.
How do silanes work in coatings and inks?
Silane is a compound that can combine with polar and non-polar substances at the same time. It is characterized by having both polar and non-polar parts in the molecule, such as amino, epoxy, alkyl, phenyl and other organic functional groups. , often chemically combined with organic functional groups in the matrix resin; methoxy, ethoxy, etc.
These groups are easily hydrolyzed into silanol and react with oxides and hydroxyl groups on the surface of inorganic substances (glass, silica, metal, clay, etc.) to form stable silicon-oxygen bonds. The two different reactive groups of silane form a bonding layer of "inorganic phase - silane coupling agent - organic phase" at the interface, forming a "molecular bridge" between the polymer and the substrate, firmly connecting the two. stick together.
For example, inorganic fillers are often added to improve certain properties of coatings (such as durability, weather resistance, surface hardness, etc.), or to reduce the cost of coatings and inks. If the filler is treated with a silane coupling agent in advance, the hydroxyl groups on the surface of the filler will react with the silane first.
What are the specific applications of silanes in coatings and inks?
Common applications of silane in coatings and inks are: compatibilizer for mutual modification of various resins; improving the wettability and dispersion of pigments and fillers; increasing the adhesion between coatings and substrates. Specific applications are as follows:
Silane primer
Silanes are used to improve or increase the adhesion between inorganic substrates and organic coatings. Silane combines the coating and the substrate in the form of a chemical chain through "molecular bridges", which can improve the coating's adhesion, durability, weather resistance, thermal shock resistance, moisture resistance, corrosion resistance, etc.
Adhesion promoter
After coating and ink systems containing silane are applied, the silane will migrate to the interface between the coating and the substrate and firmly adhere to each other through "molecular bridges".
Surface modification of pigments and fillers
Pigments and fillers are important components of coatings and inks. After surface modification with silane, their dispersibility and wettability are greatly improved, and they can effectively bind to the matrix resin and significantly reduce the viscosity of the coating.
Silane as hardener
Aminosilanes can be used as hardeners for traditional epoxy resins and polyurethane. In addition, there is also a condensation reaction between silanol groups. Aminosilanes can improve the strength and wear resistance of coatings.
Silane as comonomer
Silane is used as a comonomer in solvent-based resin synthesis. The Y group of silane must react with the monomer and bond with the substrate through Si-OH to produce cross-linking. Used as cross-linking accelerator and adhesion promoter in solvent-based coatings.
Silane couples are used in emulsion synthesis and water-based coatings
Although silanes will hydrolyze in the presence of water, this does not mean that they cannot be used in water-based systems. Aminosilane is a very good adhesion promoter and hardener. It is completely soluble in water, very stable in aqueous solution, and is compatible with a variety of organic resins.
For example, acrylic acid and styrene monomers can be copolymerized with silane to synthesize silylated acrylate emulsions to produce room-temperature cross-linked and cured acrylic paints. After curing, a hard and highly cross-linked coating can be obtained. Silanes are very stable in this water-based system and will not react or cross-link before the coating sets.