Quick answer: Before you commit to switching, check what is driving it. If the driver is antimony cost rather than halogen policy, you do not need to leave halogenated chemistry at all — cutting antimony with zinc borate or stannate captures most of the saving at a fraction of the reformulation risk. If it is a genuine halogen-free requirement, expect roughly double the loading, some mechanical loss and a re-certification cycle.
“What can we use instead of brominated?” arrives in our inbox several times a month, and the honest answer starts with a question back: why are you switching? Because the right alternative — and whether you should switch at all — depends entirely on what is driving it. A customer mandate, a smoke requirement and an antimony price shock lead to three different answers, and one of them frequently turns out not to need a halogen-free system at all.
First: Are You Sure You Need To?
Q: Are halogenated flame retardants banned? Some specific molecules are. The chemistry class is not.
This distinction matters, because a lot of switching projects begin with a misconception. What is actually restricted is a short list of persistent substances — PBDEs, HBCD — under the Stockholm Convention and regional POPs regulations. The modern replacements, DBDPE and PolyFR among them, remain legal and widely used, and are RoHS compliant. Our article on brominated flame retardants examples lists which are restricted and which are not.
So sort your driver into one of four, because each has a different cheapest answer:
- A customer or brand policy demands halogen-free. Then you switch, full stop — this is commercial, not technical, and no amount of chemistry argument changes it.
- Smoke or corrosivity is failing. Halogen-free is usually right, since halogen systems release acid gas and more smoke. But check whether a smoke suppressant on your existing system clears the clause first — it is far cheaper.
- Antimony cost or supply is the problem. You may not need to leave halogen at all. Zinc borate replaces up to ~75% of the antimony, and zinc stannate can take flexible PVC to fully antimony-free while staying halogenated. This is the single most common case where a full halogen-free conversion is the expensive answer to a cheap problem.
- Regulatory anxiety about brominated chemistry generally. Legitimate as a long-term hedge, but move deliberately — verify what your market actually restricts rather than switching on a rumour.
The Alternatives, by What They Actually Do
| Alternative | Typical loading | Best suited to | What it costs you |
|---|---|---|---|
| Mineral hydroxides (ATH/MDH) | 50–65% | Cable compounds, smoke-critical parts, thick sections | Heavy loading — mechanics, density, line speed |
| Intumescent (APP-based) | 18–25% | PP and polyolefins, thin walls where mineral is too heavy | Char quality is resin-dependent; moisture sensitivity |
| Phosphinate + MPP | 15–20% | Glass-filled PA66, PBT, thin-wall connectors | Highest raw material cost of the group |
| Melamine cyanurate | 8–15% | Unfilled PA6/PA66 only | Fails once glass fibre enters — mechanism depends on dripping |
| Phosphate esters (BDP/RDP) | 8–14% | PC/ABS, PPO blends | Lowers heat deflection; needs anti-drip |
| Zinc stannate / zinc borate | 1–8 phr | Staying halogenated but removing antimony | Not a halogen replacement — solves a different problem |
Note the last row carefully. It is the answer to “we need to get antimony out”, not “we need to get halogen out” — and buyers conflate those two constantly. The synergist family and what each one substitutes for is mapped in our guide to flame retardant synergists.
What the Switch Actually Costs
Q: Is halogen-free more expensive than brominated? Yes, usually — and the gap is bigger than the price-per-kilogram comparison suggests.
Three costs, in the order they surprise people:
- Loading roughly doubles. A brominated system reaching V-0 at 15% might need 22–25% as an intumescent, or 55%+ as a mineral system. You are not swapping one bag for another — you are changing how much of your part is polymer.
- Mechanical properties pay for it. More additive means less polymer. Impact strength is usually the first casualty, and at mineral loadings the part’s density and stiffness change noticeably. For a part with a drop test or a snap fit, this is the real cost, not the material price.
- Requalification. New burn tests at your thickness, mechanical retesting, possibly a UL file update, and process re-tuning for the changed viscosity. For a certified product this often exceeds a year of material savings — the full accounting method is in our guide to flame retardant cost per part.
What you buy in return is real: no halogen acid gas, dramatically better smoke behaviour, compliance with customer halogen-free policies, and insulation from future brominated-chemistry regulation. Whether that is worth the cost is a business decision, not a technical one — and it is your business decision, not your supplier’s.
A Sequence That Works
- Write down the actual requirement — the customer clause, the smoke limit, the ppm threshold. “Halogen-free” without a number is not a specification; the standard limits are under 900 ppm bromine and chlorine each, under 1500 ppm total.
- Check the cheap fix first. If the driver is antimony cost or a smoke clause, a synergist change inside your existing halogenated system may solve it for a fraction of the disruption.
- Pick the route your resin dictates, not the one that sounds most modern. Unfilled nylon, glass-filled nylon and PP have three different right answers, and the resin decides, not preference.
- Run both formulations side by side. Burn test, impact, flow, at your actual wall thickness. The incumbent is your benchmark, and testing them together on the same equipment removes most arguments later.
- Budget the requalification honestly at project start rather than discovering it mid-conversion.
If you are running this conversion, send us the current formulation, the resin, the target rating and thickness, and what is driving the switch — we will propose a route and burn-test it against your incumbent. Our halogen-free range spans mineral, intumescent, phosphinate and nitrogen systems, in powder, masterbatch and ready-to-mould compound form; the full chemistry map is on our flame retardant chemicals hub, and the head-to-head reasoning in halogen-free vs halogenated.
And if the analysis says you should stay halogenated, we will tell you that too — we supply brominated systems as well, so we have no reason to push you off one.
FAQ
What is the best alternative to brominated flame retardants?
There is no single best — the resin decides. Polyolefins usually go to intumescent APP systems; glass-filled polyamide and PBT to phosphinate plus MPP; cable compounds to mineral hydroxides; PC/ABS to phosphate esters. Matching the alternative to the polymer matters more than the alternative’s general reputation.
Can I replace a brominated flame retardant without reformulating?
No. Halogen-free systems work by different mechanisms and need different loadings — often double. Treat it as a new formulation with the old one as your benchmark, not as a substitution.
Do I have to give up halogen to get rid of antimony?
No, and this is the most useful thing on this page. Zinc borate replaces a large share of antimony in halogenated systems, and zinc stannate can eliminate it entirely in flexible PVC — while the system stays halogenated. If antimony cost is your problem, this is far cheaper than a halogen-free conversion.
Are halogen-free flame retardants safer?
In fire, they produce less smoke and no halogen acid gas, which is a genuine and well-documented advantage for escape conditions and equipment survival. As chemicals, safety depends on the specific substance rather than on whether it contains halogen — each has its own toxicology profile, and “halogen-free” is not a synonym for “non-toxic”.
How urgent this migration really is depends on where the regulatory line falls, and it falls more narrowly than most coverage implies — on small aromatic additives rather than on bromine as such. The live files and their dates are in brominated flame retardant regulations.
Final Thoughts
Before you commit to switching, check what is actually driving it. If the driver is antimony cost rather than halogen policy, you can stay where you are and cut antimony instead with zinc borate or zinc stannate – far cheaper than reformulating. If the driver is a real halogen-free requirement, our halogen-free range is where to start, and we will be straight about the loading and mechanical cost.
—— Rectivas Materials 团队 老陈