For professionals in the chemical industry, particularly those involved in procurement and R&D for UV-curable applications, a deep understanding of photoinitiators is essential. These compounds are the catalysts that enable the rapid transformation of liquid formulations into solid materials when exposed to UV light. NINGBO INNO PHARMCHEM CO.,LTD., a leading manufacturer and supplier of specialty chemicals from China, aims to demystify photoinitiators and highlight the value they bring to various industries.

What Exactly Are Photoinitiators?

Photoinitiators are molecules that, upon absorbing photons of specific wavelengths (typically in the UV or visible light spectrum), undergo a chemical transformation. This transformation leads to the generation of reactive species, most commonly free radicals or cations. These reactive species then initiate a polymerization reaction of monomers and oligomers within a formulation, leading to rapid cross-linking and curing. This technology is widely used in UV-curable inks, coatings, adhesives, and 3D printing resins.

Key Types of Photoinitiators

Photoinitiators are broadly classified based on their mechanism of action:

  • Norrish Type I Photoinitiators: These molecules undergo unimolecular bond cleavage upon excitation, directly generating free radicals. Examples include alpha-hydroxy ketones and acylphosphine oxides. They are often highly efficient and suitable for both thin and thick films.
  • Norrish Type II Photoinitiators: These require a co-initiator (a hydrogen donor, often an amine) to generate free radicals through a bimolecular process. Benzophenones and thioxanthones are common examples. They are generally less expensive but may require careful formulation.
  • Cationic Photoinitiators: These generate Brønsted or Lewis acids upon UV exposure, which then initiate cationic polymerization. They are known for low shrinkage and good adhesion but can be inhibited by basic substances.

Factors to Consider When Purchasing Photoinitiators

When a chemical buyer or R&D scientist decides to purchase photoinitiators, several critical factors are considered:

  • Absorption Wavelength vs. Light Source: The photoinitiator must absorb strongly at the wavelengths emitted by the UV curing equipment.
  • Initiation Efficiency: A measure of how effectively the photoinitiator generates initiating species. Higher efficiency means faster cure.
  • Through-Cure Capability: Especially important for pigmented or thick coatings, ensuring the entire depth of the film cures.
  • Surface Cure Properties: The ability to cure the surface layer effectively, preventing tackiness.
  • Solubility and Compatibility: Ensuring the photoinitiator dissolves well and is compatible with the resin system.
  • Yellowing and Odor: Minimizing yellowing and odor from photolysis products is crucial for many applications.
  • Cost and Availability: Procurement managers will always weigh the cost-effectiveness and reliable supply from manufacturers.

NINGBO INNO PHARMCHEM CO.,LTD. as Your Trusted Supplier

At NINGBO INNO PHARMCHEM CO.,LTD., we understand the importance of selecting the right photoinitiator for optimal results. Our product range, including LSD-25 Bitartrate (CAS 113-41-7), is manufactured to high standards, offering excellent performance for a variety of UV curing applications. As a leading manufacturer and supplier in China, we are committed to providing quality chemicals at competitive prices. We invite procurement professionals to contact us for quotes and to explore our comprehensive range of photoinitiators and other specialty chemicals.