Acetylacetone Peroxide (TBCP, Post-Cure)

Acetylacetone Peroxide (AAP), sometimes referred to by older trade designations like TBCP, is a versatile organic peroxide used primarily as a secondary or post-cure initiator for unsaturated polyester resins. Unlike MEKP, acetylacetone peroxide has a milder reactivity profile and generates fewer active free radical species per unit weight, making it useful for adjusting cure rates, extending gel times, or providing supplementary curing action after an initial MEKP-initiated cure. In composites, it is often blended with MEKP in a ratio of 1:3 to 1:1 to modify the cure profile — reducing peak exotherm, extending working time, or improving through-cure in thick laminates. It is also used as a stand-alone initiator in cold-cure casting systems where long open times are required. The formulation typically contains AAP at 38–42% active content in a plasticizer solution. Compatible with cobalt octoate and cobalt naphthenate accelerators. Dosage is 1–3% blended with or replacing a portion of MEKP.