Zinc Borate

TCC’s zinc borate is an Environmental Protection Agency (EPA) approved non-halogen flame retardant. The product can be used as a fire retardant in PVC, polyolefins, elastomers, polyamides, and epoxy resins.

In halogen-containing systems, zinc borate is used in conjunction with antimony oxide. In halogen-free systems, it is normally used in conjunction with alumina trihydrate, magnesium hydroxide, or red phosphorus. In some particular applications, zinc borate can be used alone.

Zinc borate is an anti-dripping and char-promoting agent, and suppresses the afterglow. In electrical insulator plastics it suppresses arcing and tracking. Zinc borate has a synergistic effect with zinc phosphate or barium borate as a corrosion inhibitor pigment. It acts as a broad-spectrum fungicide in plastics and wood products. It can be used as a flux in some ceramics. In electrical insulators, it improves the ceramics properties.

Zinc borate has a refractive index similar to most polymer systems, which results in the retention of considerable translucence. This allows the use of lower pigment loading as compared to antimony oxide.

Zinc borate has a specific gravity of 2.77 and is considered to be low toxicity.

The most commonly used variety of zinc borate is 3.5 water zinc, also known as ZB-2335 flame retardant.

Applications

TCC’s zinc borate is primarily used as a flame retardant in plastics and cellulose fibers, paper, rubbers and textiles. It is also used in paints, adhesives, and pigments. As a flame retardant, it can replace antimony trioxide as a synergist in both halogen-based and halogen-free systems. It is an anti-dripping and char-promoting agent, and suppresses the afterglow. In electrical insulator plastics it suppresses arcing and tracking.

In halogen-containing systems zinc borate is used together with antimony trioxide and alumina trihydrate. It catalyzes formation of char and creates a protective layer of glass. Zinc catalyzes the release of halogens by forming zinc halides and zinc oxyhalides.

In halogen-free systems, zinc borate can be used together with alumina trihydrate, magnesium hydroxide, red phosphorus, or ammonium polyphosphate. When burning the plastics, a porous borate ceramic is formed that protects the underlying layers. In presence of silica, borosilicate glass can be formed at plastic burning temperatures.

As the partial, or completely EPA approved substitute for containing halogen and other flame retardants, zinc borate is being directly applied to a wide range of plastics and rubber processing such as PVC, PE, PP, and to enhance polyamide, PVC resin, polyphenylene ethylene, epoxy resin, polyester resin, acid ethylene and natural rubber, styrene butadiene rubber, and chloroprene rubber. It can also be applied to the production of paper, fiber fabric, decorative panels, floor leather, wallpaper, carpet, ceramic glaze, fungicides, and paint production to improve flame retardant performance.