Benzoyl Peroxide Paste (50% in Plasticizer)

Benzoyl Peroxide Paste at 50% active content in a non-migrating plasticizer is the standard initiator system for amine-accelerated ambient cure of unsaturated polyester and vinyl ester resins, particularly where cobalt-free curing is desired. BPO paste is activated by tertiary amine accelerators such as N,N-dimethylaniline (DMA), N,N-dimethyl-p-toluidine (DMPT), or diethylaniline (DEA), forming a redox couple that generates benzoyloxy radicals at room temperature. The paste form provides safe handling compared to dry BPO powder, reducing dust and ignition risk. At 50% concentration in plasticizer, it disperses readily into resin systems without premixing. BPO/amine systems are favored where cobalt-free laminates are required — for instance in food-contact applications, certain medical composites, and white or light-colored products where cobalt-induced yellowing is undesirable. Dosage is typically 2–4% BPO paste with 0.5–2% DMA or DMPT. Gel times of 10–25 minutes at 20°C are achievable depending on amine type and level. Post-cure heating to 60–80°C improves final properties.