In the selection of photoinitiators for UV-curable applications, understanding the specific properties of each compound is crucial for optimal formulation and performance. Ethyl Phenyl(2,4,6-trimethylbenzoyl)phosphinate, commonly known as TPO-L, is a highly valued liquid Type-I photoinitiator. This article outlines its key characteristics, making it easier for researchers and formulators to appreciate its utility and to buy TPO-L with confidence.

Chemical Identity and Structure

TPO-L has the chemical formula C18H21O3P and a molecular weight of approximately 316.33 g/mol. Its CAS number is 84434-11-7. The molecule features a phosphinate ester group and a benzoyl moiety substituted with methyl groups, contributing to its unique reactivity and absorption properties. Its structure allows it to efficiently absorb UV light and generate free radicals, initiating the polymerization process in UV-curable systems.

Physical Properties:

• Appearance: TPO-L is typically described as a clear, yellowish liquid. This liquid form is a significant advantage for ease of handling and incorporation into formulations compared to solid photoinitiators.
• Solubility: It exhibits good solubility in most common organic solvents, monomers, and oligomers used in UV-curable systems. However, it is generally insoluble in water. This broad solubility ensures easy integration into various resin matrices.
• Density: The density of TPO-L is approximately 1.13-1.14 g/cm³ at 20°C.
• Boiling Point: TPO-L has a high boiling point, reported around 456°C at 760 mmHg, indicating low volatility under typical processing conditions.
• Melting Point: While primarily used as a liquid, its melting point is around 144.5-147°C, suggesting it remains solid at lower temperatures but is typically handled as a liquid.
• Flash Point: The flash point is typically above 240°C, indicating good thermal stability and safety in handling.

Performance Properties:

• UV Absorption: A key feature of TPO-L is its absorption in the longer wavelength range of the UV spectrum (around 380 nm). This allows it to penetrate deeper into pigmented or thicker coatings, ensuring efficient through-cure, which is vital for applications like white inks and coatings.
• Reactivity: TPO-L is a highly efficient photoinitiator, leading to fast curing speeds. This contributes to increased productivity in manufacturing processes.
• Low Yellowing: It is known for its low tendency to cause yellowing in cured films, making it ideal for clear coats, white formulations, and light-colored systems where color stability is paramount.
• Recommended Concentration: Typically used in concentrations ranging from 0.3% to 5.0% by weight, depending on the specific formulation and desired curing speed.

Applications:

The favorable properties of TPO-L make it suitable for a wide range of applications, including UV curable inks, coatings for graphic arts, wood, plastics, 3D printing resins, and photoresists. Its ability to perform well in challenging systems makes it a staple ingredient for many formulators.

Sourcing High-Quality TPO-L

As a professional supplier, we ensure that the TPO-L we provide meets high purity standards and consistent specifications. Understanding these properties empowers you to make informed decisions for your formulations. If you are seeking a reliable supplier to buy TPO-L, we offer competitive pricing and dedicated support. Contact us for a quote and to learn more about how TPO-L can benefit your UV curing applications.