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

Question 1

Why must benzophenone be used with an amine co-initiator?

Accepted Answer

Benzophenone operates via a Type II photoinitiator mechanism: UV excitation generates a triplet state that abstracts a hydrogen atom from a co-initiator amine (e.g. MDEA, TEA), producing an aminoketyl radical and an α-amino radical. Both radicals initiate polymerization. Without the amine, quantum yield for radical generation is too low for practical cure speeds.

Question 2

What is the recommended use level of benzophenone in UV coatings?

Accepted Answer

Typical loading is 1–4% by weight on total formulation, combined with 1–3% amine synergist. Surface cure (oxygen-inhibition layer) benefits most; for through-cure of pigmented or thick films, blend with an acylphosphine oxide Type I initiator such as TPO or BAPO for improved depth of cure.

Question 3

Does benzophenone cause yellowing in clear and white UV coatings?

Accepted Answer

Unreacted benzophenone can cause slight yellowing on UV exposure due to photoproduct accumulation, particularly in very white or clear coatings. Using the minimum effective dose and selecting a high-purity grade (≥99% GC) minimises this. For non-yellowing requirements, consider blending with a thioxanthone or switching to a non-yellowing acylphosphine oxide initiator.

Purity	≥99% (GC)
Appearance	White crystalline powder
Melting Point	47–49°C
Molecular Weight	182.2 g/mol
UV Absorption λmax	~340 nm (in EtOH)

Benzophenone Photoinitiator BP

Specifications

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