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Flame Retardent List Heading

Flame Retardants

Zinc borate
1332-07-6

Where is it Commonly Found?

Zinc borate is used in PVC, cellulosics, unsaturated halogenated polyesters (Kirk-Othmer 1991), as well as EVA, PP, and PE. It is also used in nylon plastics in electronic components in combination with other halogen-free flame retardants (EFRA 2006) as well as wire and cable, waterborne emulsions and coatings, and shipping pallets. It may be used in place of antimony trioxide and is synergistic with aluminum trihydroxide (Danish EPA 1999). Zinc borate is also used for non-flame retardant purposes such as anti-corrosion and as a fungicide for wood preservation (EFRA 2006).

HEALTH EFFECT SUMMARY

Zinc borate has low acute toxicity via ingestion, dermal contact, and inhalation. The dust is a respiratory irritant, and may also be irritating to eyes and skin (U.S. Coast Guard 1984), but this form of zinc borate is not encountered in products that contain it as a flame retardant. The European Union has classified zinc borate as “Very toxic to aquatic organisms/May cause long-term effects in the aquatic environment” (European Union 2006).

Extremely high exposures to borates, such as those caused by ingestion of large quantities of the substance, can cause serious poisonings, but are unlikely to occur from use of this compound as a flame retardant (EFRA 2006). Zinc borate is not a developmental or reproductive toxicant at exposures likely to be encountered, nor is it a carcinogen. Neither zinc nor borate will bioaccumulate to any significant extent and are not expected to be problematic as water contaminants. Zinc borate dissolves in water and biological systems to form zinc hydroxide and boric acid, thus the toxicity properties of both are relevant.

How is it Categorized?

Inorganic synergist

Abbreviation

4ZnO.6B2O3. 7H2O

Additional Facts

Zinc borate, the most widely used zinc flame retardants, is commonly used as substitute for antimony trioxide. A white crystalline or amorphous powder, Zinc borate has a synergistic effect with aluminium trihydroxide and is often used in combination with other flame retardants. (A synergist is a compound which enhances the performance of a flame quencher [usually a bromine- or chlorine-based halogen systems that can interfere with the reactions in a flame])

What are its Synonyms?

ALCANEX FR 100
BONREX FC
BORATE DE ZINC (DOT FRENCH)
BORATO DE ZINC (DOT SPANISH)
BORAX 2335
BORIC ACID, ZINC SALT
FRC 600
HA 1
HA 1 (BORATE)
JS 9502
XPI 187
ZB 112
ZB 237
ZB 467 LITE
ZINC BORATE (ZN3(BO3)2)
ZINC ORTHOBORATE
ZINC ORTHOBORATE (ZN3(BO3)2)
ZN 100