Chemicals That Thicken Coal Tar Emulsion Asphalt Sealer

Emulsions

• An emulsion consists of two liquids that do not mix, such as oil and vinegar, where small globules of one liquid are suspended in the other. The suspension is held in place by an emulsifier. This mixture is known as a colloid, where one substance is disbursed evenly throughout the other. The main purpose of an emulsion thickener is to stabilize such a mixture, but it can also be used to increase viscosity.

Polymers and Copolymers

• Asphalt sealer thickeners are composed of polymers or copolymers. A polymer is a substance composed of a chain of chemical elements, or monomers, linked together on a molecular level. Copolymers' chains consist of two or more types of monomers.

Styrene-Butadiene Copolymer

• Certain varieties of asphalt sealer thickener contain styrene-butadiene copolymer. Styrene is a mostly synthetic chemical that is used in the making of rubber, plastics and resins. It also is referred to as vinylbenzene, ethenylbenzene, cinnamene and phenylethylene. The EPA lists it as a Hazardous Air Pollutant, or HAP. Butadiene is a petroleum byproduct, high quantities of which are produced in the United States each year. It is primarily used in the making of synthetic rubber but can also be found to a lesser degree in plastics and fuel. Exposure to 1,3-Butadiene is associated with eye, nose, throat and lung irritation, and the EPA has classified it as a known human carcinogen.

Synthetic Resin Emulsion

• A resin is a yellowish liquid or soft solid of plant origin that also can be made synthetically. Resins are used in lacquers, varnishes and a variety of other products. Synthetic resin emulsions are found in some asphalt sealer thickeners. The ingredients in synthetic resins are known to be toxic in some cases.

Modified Acrylonitrile

• Acrylonitrile, in its pure form, is very flammable and is listed by the Occupational Safety and Health Administration, or OSHA, as a toxic and hazardous substance. It can be absorbed through the skin and has to be washed off immediately after exposure to skin. Since it is absorbed through clothing -- even shoes -- exposed clothing should be removed as soon as possible. Acrylonitirile can be found in a variety of polymers, resins, rubbers and plastics. It is used in modified form in the manufacture of some asphalt sealer thickeners.