Introduction
Di-(2,4-dichlorobenzoyl) peroxide, commonly known as DCBP or 2,4-dichlorobenzoyl peroxide (CAS 133-14-2), is a halogenated diacyl peroxide with distinct properties that make it valuable for specialized crosslinking and vulcanization applications. The presence of chlorine substituents on the aromatic rings modifies the peroxide’s decomposition kinetics and the reactivity of the resulting radicals.
Key Facts
- CAS Number: 133-14-2
- Molecular Formula: C14H6Cl4O4
- Molecular Weight: 380.01 g/mol
- Appearance: White to off-white powder or paste
- Active Oxygen: ~4.2% (theoretical)
- 10-Hour Half-Life Temperature: ~53-55 deg C
- Storage: Water-wet or phlegmatized formulation
Key Applications
Silicone Rubber Vulcanization
DCBP is widely used as a crosslinking agent for silicone rubber (VMQ, PVMQ) compounds. It provides effective curing without the need for post-cure treatment in many applications, yielding silicone elastomers with excellent transparency and low compression set. DCBP is particularly valued for hot air vulcanization (HAV) processes where its decomposition temperature profile enables efficient curing without surface tack issues.
Specialty Elastomer Crosslinking
DCBP is also applicable to the crosslinking of fluorocarbon elastomers (FKM) and certain other specialty elastomers where its specific decomposition characteristics provide processing advantages.
Safety
DCBP is typically supplied as a 50% paste in silicone oil or as a water-wet powder to ensure safe handling. The dry material is sensitive to impact and friction. Standard organic peroxide safety protocols apply, with emphasis on maintaining the phlegmatized state and avoiding desiccation of water-wet formulations.
Q: Why are chlorinated peroxides used for silicone curing?
A: The chlorine substituents on DCBP modify the electronic properties of the benzoyloxy radicals generated during decomposition. These chlorinated radicals exhibit different hydrogen abstraction selectivity compared to non-halogenated benzoyloxy radicals (from BPO), which can translate to more efficient crosslinking of silicone polymers. Additionally, DCBP’s decomposition products are less likely to cause discoloration in transparent silicone compounds.
Key Takeaways
- DCBP (CAS 133-14-2) is a chlorinated diacyl peroxide specialized for silicone rubber vulcanization.
- It is supplied in phlegmatized form (paste or water-wet) for safe handling.
- The chlorine substituents modify decomposition chemistry for improved silicone crosslinking efficiency.
- Shandong Do Sender Chemicals supplies DCBP for silicone and specialty elastomer applications.