Name: Benzophenone Photoinitiator BP
Brand: Coatingsink
SKU: photoinitiator-bp
Availability: InStock

Question 1

Why must benzophenone be paired with an amine synergist?

Accepted Answer

Benzophenone is a Type II photoinitiator that abstracts a hydrogen atom from a co-initiator (typically a tertiary amine such as MDEA or EDB) to generate the reactive carbon-centered radical. Without an amine synergist the quantum yield is very low, giving insufficient cure speed. The amine also acts as an oxygen scavenger, suppressing surface inhibition.

Question 2

What is the typical loading level of BP in a UV offset ink versus a UV wood coating?

Accepted Answer

In UV offset inks, BP is typically used at 2–4% alongside 1–2% amine synergist due to the thin film and high lamp intensity. In UV wood coatings (thicker films, 50–150 µm), loadings of 3–5% BP plus 2–4% amine are common to ensure through-cure; for pigmented or white coatings, supplement with a Type I PI such as TPO to improve deep-cure performance.

Question 3

Does benzophenone cause yellowing in clear UV coatings?

Accepted Answer

BP itself has low inherent yellowing, but unreacted benzophenone and its photoproduct benzopinacol can migrate and cause slight yellowing on prolonged UV or thermal exposure. This is most visible in clear high-gloss systems. For critical non-yellowing applications (e.g., optical films, white UV coatings), consider replacing part of the BP loading with a non-migrating polymeric PI or with TPO.

Purity	≥99.0%
Melting Point	47–50°C
Molecular Weight	182.22 g/mol
UV Absorption Max	~340 nm
Recommended Dosage	1–5% (with amine synergist)

Benzophenone Photoinitiator BP

Specifications

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