Antimony trioxide is the main derivative of antimony metal. The metal is mined most often in China, Bolivia, Russia, and South Africa. The oxide derivative can be used in many different industries including the flame retardant industry as a synergist, the plastic manufacturing industry as a catalyst, the glass industry as a clarifying agent, and in porcelain and enamel as an opacifier or white pigment.

When you want to flame retard something the most common additives for doing so is a halogenated compound in combination with a synergist. The halogenated compound alone will provide flammability protection, but the presence of the synergist allows you to use much less halogenated product. You can use approximately half as much halogen if you also use an antimony synergist.

The antimony/halogen combination is used to flame retard a great variety of materials. You will find antimony used in the plastics, textiles, rubber, paper, and paint industries. Specific materials that use an antimony synergist include but are not limited to high impact polystyrene (HIPS), polyvinyl chloride (PVC), polypropylene (PP), acrylonitrile butadiene styrene (ABS), polyethylene (PE), propylene diene M-class rubber (EPDM), epoxies, phenolics, and polyurethanes.

Antimony trioxide is typically sold in multi-walled paper bags in powder form. The halogenated product is usually provided in a similar manner. This method of packaging causes a lot of dusting so there is an alternative. Some companies will make a specialized liquid dispersion using whatever medium you desire with the halogenated product and antimony trioxide in whatever ratio suits your process the best.

The polymerization of polyethylene terephthalate or PET requires a catalyst and one of the best choices for that job is high purity antimony trioxide. This manufacturing practice requires a more pure grade of antimony trioxide than flame-retardants. While there are other catalysts that are more efficient; antimony is still the best choice because of its optimal cost/performance ratio.

PET is used to make water bottles and other liquid containers. Because these liquids can sit in the bottle for a long time before consumption, there are some concerns about materials in the PET migrating into the PET. There have been some studies that show antimony will migrate into bottled water, but the concentrations are well below the level where we should be concerned. In addition, the toxicity of antimony is very low and its presence will not likely cause much harm.

A third use for antimony is as a clarifying agent for glass. A clarifying agent is just what it sounds like; it clears up glass during the manufacturing process. The antimony trioxide is added during the meltdown phase and will help to remove any bubbles or inclusions as well as ensure clear glass as the final product. Sand has natural impurities when left untreated would give you light blue or green glass. Antimony trioxide is a good choice because some other common clarifying agents will give you clear glass to start with, but will degrade with time. For example, manganese dioxide used to be used frequently, but scientists found that over time the manganese reacts with the ultraviolet light from the sun and turns the glass purple.

Finally, antimony oxide is a white crystalline powder. Because of its color, some small markets use it as a pigment. One such application is as an opacifier for porcelain and enamel. With uses as varied as the ones described here, antimony trioxide is a very useful product.