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What is a Photoinitiator and How Does It Work?
2023/5/24
A photoinitiator is a chemical compound that can absorb light and generate reactive species, such as free radicals or cations, that can initiate a polymerization reaction. Photoinitiators are widely used in various industries that rely on light-curing systems, such as coatings, adhesives, printing inks, dental materials, and 3D printing.
Cationic photoinitiators can produce cations when exposed to light, which can then react with cyclic ethers or epoxides to form polymers. Cationic photoinitiators are suitable for UV and visible light curing systems, and can offer high thermal stability, high chemical resistance, and low shrinkage. Some examples of cationic photoinitiators are diaryliodonium salts, triarylsulfonium salts, and iron-arene complexes.
The type and concentration of the monomer or oligomer
The desired curing speed and depth
The presence of oxygen or other inhibitors
The compatibility with other additives or pigments
The cost and availability of the photoinitiator
High productivity and efficiency
Low temperature and pressure requirements
Spatial and temporal control of curing
Improved performance and quality of the products
Photoinitiators can be classified into two main types: free radical photoinitiators and cationic photoinitiators.
Free radical photoinitiators can produce free radicals when exposed to light, which can then react with unsaturated monomers or oligomers, such as acrylates or methacrylates, to form polymers. Free radical photoinitiators are suitable for UV and visible light curing systems, and can offer fast curing speed, low odor, and good compatibility with various substrates. Some examples of free radical photoinitiators are benzophenone, benzoin, thioxanthone, and acylphosphine oxide.Cationic photoinitiators can produce cations when exposed to light, which can then react with cyclic ethers or epoxides to form polymers. Cationic photoinitiators are suitable for UV and visible light curing systems, and can offer high thermal stability, high chemical resistance, and low shrinkage. Some examples of cationic photoinitiators are diaryliodonium salts, triarylsulfonium salts, and iron-arene complexes.
The selection of a photoinitiator depends on several factors, such as:
The type and wavelength of the light sourceThe type and concentration of the monomer or oligomer
The desired curing speed and depth
The presence of oxygen or other inhibitors
The compatibility with other additives or pigments
The cost and availability of the photoinitiator
Photoinitiators are essential components for light-curing systems that can offer many advantages over conventional thermal curing systems, such as:
Energy saving and environmental protectionHigh productivity and efficiency
Low temperature and pressure requirements
Spatial and temporal control of curing
Improved performance and quality of the products
Photoinitiators are innovative and versatile chemicals that can enable various applications and technologies that rely on light-curing systems. They are expected to have a growing demand in the future due to their superior performance and environmental benefits.
