Tetrabromobisphenol A, abbreviated as TBBA, has the CAS number 79-94-7. It is a white crystalline powder, soluble in methanol and ether, but insoluble in water. It is primarily used as a reactive flame retardant, often in combination with antimony trioxide. As a multifunctional flame retardant, TBBA can be incorporated into plastics through chemical reactions or used directly as an additive. It achieves high flame retardancy primarily by capturing key free radicals during combustion, interrupting the chain reaction of combustion, and supplemented by physical covering and dilution effects. When used in combination with antimony trioxide, it produces a synergistic effect, greatly enhancing flame retardant performance, and is widely used in electronics, printed circuit boards, and other fields.

I. Basic Information

English Name: Tetrabromobisphenol A (TBBA)

CAS No.: 79-94-7

Molecular Weight: 543.87

Molecular Formula: C15H12Br4O2

Melting Point: 178℃

Boiling Point: 250℃

II. Flame Retardant Mechanism

The flame retardant effect of tetrabromobisphenol A mainly occurs in the gas phase. Its mechanism can be understood from both chemical and physical perspectives:

1. Capturing Free Radicals and Interrupting the Combustion Chain Reaction

This is the core of its flame retardant effect. When materials containing Tetrabromobisphenol A(TBBA) are thermally decomposed, the C-Br bonds (carbon-bromine bonds) in its molecules break due to their low bond energy, generating bromine free radicals. These bromine free radicals combine with highly reactive free radicals (such as HO· and H·) generated during polymer combustion to form stable molecules (such as H2O and H₂) and hydrogen bromide (HBr).HBr itself is a dense, non-flammable gas. More importantly, it can continue to react with highly reactive HO· free radicals to regenerate Br·. This cycle continuously consumes the key free radicals that sustain combustion, rapidly inhibiting the chain reaction of combustion, weakening the flame until it extinguishes.

2. Dilution and Covering of Combustible Materials: During combustion, tetrabromobisphenol A decomposes to produce a large amount of flame-retardant hydrogen bromide gas. This gas dilutes the concentration of oxygen and combustible gases in the surrounding air, making it difficult to reach the concentration range required for combustion. The generated hydrogen bromide gas is denser than air and can form a gas film covering the material surface, isolating oxygen and heat transfer to a certain extent.

3. Synergistic Effect: In practical applications, Tetrabromobisphenol A(TBBA)is almost always used in combination with antimony trioxide. There is a significant synergistic effect between the two. Antimony trioxide can react with HBr at high temperatures to produce antimony bromide (SbBr₃). Antimony bromide vapor has an extremely high density, allowing it to remain in the combustion zone for a longer period and more effectively isolate oxygen. Simultaneously, it promotes the capture of free radicals in the flame, thus maximizing the flame-retardant effect.

III. Examples of Some Flame-Retardant Formulations

1. Flame-Retardant ABS (UL94V 0, 1.6mm)

ABS Resin: 100

Tetrabromobisphenol A: 15~18

Sb₂O₃(ATO): 5~6

Antioxidant 1010/168: 0.3~0.5

Calcium Stearate: 0.3~0.5

2. Flame-Retardant HIPS

HIPS: 100

TBBA: 12~15

Sb2O3(ATO): 4~5

Antioxidant: 0.3

Lubricant: 0.4

Features: Good compatibility, excellent processing flow, suitable for appliance casings, toys, etc.

IV. Quality Standards

Appearance: White powder

Main content≥99.0%

Br content≥58.0%

Moisture≤0.1%

Melting point≥180°C

V. Packaging

25kg/bag, 500kg/bag, 1000kg/bag

Tetrabromobisphenol A (TBBA) is mainly used in EP, PC, PBT, PET, phenolic resins, PU, etc. It is also used in PS, ABS, and unsaturated polyesters, primarily as a flame retardant additive. Most circuit boards used in electrical appliances are made of epoxy resin containing tetrabromobisphenol A (TBBA). Additionally, it is used in the potting epoxy resin for television high-voltage transformers.