Name: Photoinitiator BAPO (Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide)
Brand: Coatingsink
SKU: photoinitiator-bapo
Availability: InStock

Question 1

What is the difference between BAPO and BAPO-L (liquid)?

Accepted Answer

BAPO (solid) is phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide with a melting point of 127–133°C. BAPO-L is a liquid version formulated as a blend or ester derivative for easier cold incorporation. BAPO solid offers higher purity and is preferred when maximum photoinitiator loading is needed; BAPO-L suits applications where room-temperature liquid handling is required, such as inkjet or high-shear mixing processes.

Question 2

Why is BAPO preferred for deep-cure of pigmented and white UV inks?

Accepted Answer

BAPO has two UV absorption maxima at ~295 nm and ~370 nm, giving it broad-spectrum efficiency. Its bis-acylphosphine structure generates two radical fragments per photon absorbed, nearly doubling initiating efficiency compared to mono-acylphosphine oxides like TPO. This makes BAPO particularly effective at penetrating pigment barriers — including opaque white TiO₂ pigmented systems — to ensure through-cure in thick or heavily pigmented films.

Purity	≥98%
Appearance	yellow powder
Melting Point	127–133°C
Recommended Dosage	0.5–3.0%
UV Absorption Maxima	~295 nm, ~370 nm

Photoinitiator BAPO (Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide)

Specifications

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