Accelerator CZ (CBS) in Rubber Vulcanization
Accelerator CZ (CBS, CAS 95-33-0) is a sulfenamide delayed-action accelerator used to control the sulfur vulcanization of rubber. This page explains what it does in the cure system, where it is used and how it compares with the other sulfenamides.
What it does in the cure system
Vulcanization crosslinks rubber chains with sulfur; without an accelerator it would be far too slow. CZ makes the reaction fast and controllable:
| Stage | What happens |
|---|---|
| Mixing / processing | CZ is stable at processing temperature, so the compound does not cure early (scorch safety) |
| Heating to cure temperature | The sulfur-nitrogen bond breaks, releasing the active thiazole and an amine activator |
| Cure | The released accelerator, with zinc oxide/stearic acid and sulfur, forms crosslinks quickly |
This delayed action is why sulfenamides are the accelerators of choice for large components: the compound can be mixed, shaped and stored, then cured quickly in the mould.
Where CZ is used
| Product | Role of CZ |
|---|---|
| Tyre compounds | Delayed-action acceleration with fast cure |
| Belts and hoses | Cure control for thick, technical goods |
| Moulded goods | Seals, gaskets and mechanical parts |
| General rubber | NR, SBR, BR and blends |
What CZ needs to work
- Sulfur – the crosslinker (conventional, semi-EV or EV level).
- Activators – zinc oxide and stearic acid.
- Optional co-accelerator or retarder – to fine-tune cure rate and scorch (for example a thiuram, DPG or PVI).
CZ vs the other sulfenamides
| Accelerator | Delay | Best for |
|---|---|---|
| CZ (CBS) | Medium | General tyres and technical goods |
| TBBS (NS) | Medium-high | Tyres; the most common sulfenamide |
| DCBS | High | Thick sections, longest scorch safety |
All three are sulfenamides; the difference is how strongly delayed they are. CZ sits in the middle.
Frequently Asked Questions
Is CZ the same as CBS?
Yes – CZ and CBS are two names for N-cyclohexyl-2-benzothiazolesulfenamide (CAS 95-33-0).
Why is CZ called delayed action?
Because it stays largely inactive at processing temperature and releases the active accelerator only at cure temperature, giving scorch safety.
Does CZ need sulfur?
Yes – it works in a sulfur cure system with zinc oxide and stearic acid activators.
Is CZ a skin sensitiser?
Yes – like most accelerators it is a potential skin sensitiser; avoid skin contact.
When should I use TBBS instead?
When more scorch safety is needed (larger or thicker parts) – TBBS is slightly more delayed.
Related reading
- Accelerator CZ (CBS, CAS 95-33-0): properties and applications
- Rubber antioxidants and accelerators: selection guide
- Accelerator TBBS (NS): properties and applications
- Accelerator CZ (CBS, CAS 95-33-0) – product page
PolyBlueChem supplies Accelerator CZ (CBS, CAS 95-33-0) for rubber vulcanization, with per-batch COA and SDS. Contact us with your application and tonnage.