Butylated Hydroxytoluene (BHT) in Rubber and Plastics

Butylated hydroxytoluene (BHT, Antioxidant 264, CAS 128-37-0) is a hindered phenolic antioxidant used to protect rubber and plastics against oxidation and heat ageing. This page looks at its role in rubber and plastics specifically, and at how it compares with higher-molecular-weight phenolics.

Why BHT in rubber and plastics?

Property	Benefit
Non-staining	Does not discolour white or light-coloured materials
Good solubility	Distributes evenly through oils, polymers and compounds
Fast action	Protects early, during processing and initial service
Low cost	Economical multi-purpose antioxidant

In rubber

In rubber, BHT protects the compound against heat and oxygen ageing during processing and service. It is used in NR, SBR and other general-purpose rubbers, usually where a fast, non-staining antioxidant is wanted.

Rubber application	Why BHT
General rubber goods	Non-staining, cost-effective anti-ageing
Light-coloured products	No discolouration
Processing protection	Fast action during mixing and forming

In plastics

Function	Role of BHT
Processing stabilisation	Protects the melt during extrusion and moulding
Long-term stabilisation	Protects the finished article against ageing
Colour retention	Non-staining, so no tinting

BHT’s one limitation in plastics is volatility: at very high melt temperatures some can be lost, so for high-temperature processing or very long service life a higher-molecular-weight phenolic (such as 2246 or 1010) is often preferred – sometimes alongside BHT.

BHT vs higher-MW phenolics in polymers

Factor	BHT (264)	Higher-MW phenolic (2246, 1010)
Volatility	Relatively high	Low
Processing losses	Possible at high melt temperatures	Minimal
Cost	Low	Higher
Best for	Fast, low-cost protection; oils; food/feed	High-temperature processing; long service life

Using BHT well

Match to temperature – for hot processes, pair with or replace by a higher-MW phenolic.
Combine – use with a secondary antioxidant (phosphite/thioester) for full protection.
Dose by test – set the level on an ageing/oxidation test, not by rule of thumb.
Check the COA – purity and trace-metal limits matter, especially for sensitive uses.

Frequently Asked Questions

Does BHT discolour rubber or plastics?

No – it is non-staining and non-discolouring.

Is BHT suitable for high-temperature processing?

It is more volatile than higher-MW phenolics; for very high melt temperatures a higher-MW antioxidant is often preferred.

How much BHT is used?

Low percentages in polymers and a few phr in rubber, set by test.

Can BHT be combined with other antioxidants?

Yes – it is often paired with a secondary antioxidant for synergistic protection.

Is BHT used in food-contact materials?

BHT is authorised as a food antioxidant (E321) in many markets; confirm the grade and the permitted use for your application.