- ▸ Type II chlorinated-benzophenone photoinitiator with shifted absorption for surface cure of UV coatings (Coatings & Construction)
- ▸ Used with amine synergists in UV inks and varnishes (Industrial Manufacturing)
- ▸ Cures UV-curable plastics and adhesives (Plastics & Polymers)
A grade-specific Safety Data Sheet (SDS) — with the complete hazard classification, handling precautions, and transport information — is supplied with every shipment and available on request. Confirm all safety and regulatory details against the SDS for your specific grade.
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4-Chlorobenzophenone is a Type II benzophenone-derivative photoinitiator. The chlorine substituent raises reactivity over plain benzophenone, giving faster surface cure of clear UV systems — but, like all Type II initiators, it works with an amine synergist. Identity: CAS 134-85-0.
What it is
4-Chlorobenzophenone (CAS 134-85-0) is a chloro-substituted diaryl ketone, a crystalline solid. It is one of several substituted benzophenones used to tune reactivity, solubility and volatility in UV-curable surface-cure packages.
How it cures
As a Type II initiator it does not cleave; on UV excitation it abstracts a hydrogen from an amine co-initiator to form the curing radicals. The chlorine substituent increases its activity relative to benzophenone, so it is chosen where a faster, more reactive benzophenone is wanted. Always paired with an amine synergist such as EDB or EHA.
Applications
Used for surface cure of UV coatings, overprint varnishes and inks where higher reactivity than benzophenone is needed, typically alongside a Type I initiator such as TPO for through cure. Compare 4-methylbenzophenone and benzophenone.
Forms, grades and handling
4-Chlorobenzophenone is supplied as a crystalline solid. Photoinitiators are light-sensitive — store cool, dry and dark, away from light and ignition sources. Handle per the current Safety Data Sheet (SDS); each lot ships with a Certificate of Analysis (CoA) and Technical Data Sheet (TDS).
Bulk supply and RFQ
RawSource sources 4-Chlorobenzophenone direct from producers in bulk, with CoA, TDS and SDS per lot. Tell us your lamp (mercury or LED wavelength), system (clear or pigmented) and cure target, and we will quote the right grade. Compare the full range and selection logic in the photoinitiators guide.
Typical Properties
Typical reference values, not a specification; the Certificate of Analysis (CoA) for the lot governs.
| Property | Typical Value |
|---|---|
| Chemical / type | Photoinitiator (Type II, benzophenone derivative) |
| Photoinitiator type | Type II (H-abstraction) |
| Absorption | UV (mercury-lamp range) |
| CAS Number | 134-85-0 |
| Molecular Formula | C13H9ClO |
| Molecular Weight | 216.66 g/mol |
| Handling | Light-sensitive; refer to the current SDS |
Regulatory & registration requirements
- TSCA (US):
- REACH (EU):
- EC number: 205-160-7
Source: EPA TSCA Inventory (July 2025 release) · ECHA CHEM — retrieved 2026-07-12
Frequently Asked Questions
What is 4-chlorobenzophenone used for?
4-Chlorobenzophenone (CAS 134-85-0) is a Type II photoinitiator for surface cure of UV coatings and inks; the chlorine substituent makes it more reactive than benzophenone. It is used with an amine synergist and usually with a Type I initiator for through cure.
Does 4-chlorobenzophenone need an amine?
Yes — as a Type II initiator it cures by hydrogen abstraction and requires an amine synergist (such as EDB or EHA) to generate radicals.
How is bulk 4-chlorobenzophenone supplied and quoted?
RawSource supplies 4-chlorobenzophenone in bulk with CoA, TDS and SDS per lot. Pricing is quote-based on grade and volume; submit an RFQ with your target quantity.
What is the REACH and TSCA regulatory status of 4-Chlorobenzophenone (CBZ)?
4-Chlorobenzophenone (CBZ) (CAS 134-85-0) is subject to U.S. TSCA Inventory requirements; supplying it into the EU requires valid REACH registration ((EC) No 1907/2006). RawSource cannot verify a third-party supplier's registrations — buyers should require documented TSCA and REACH compliance for their jurisdiction and volume (EC 205-160-7).