Petroleum hydrocarbon binder with reduced polycyclic aromatic hydrocarbon content
A binder pitch material includes a petroleum pitch and asphalt fraction obtained from petroleum crude oil and has a significantly lower polycyclic aromatic hydrocarbon composition than a coal tar pitch having a like softening point. The pitch material is useful as a binder material for various applications such as clay pigeons.
1. A method for producing a clay pigeon including the steps of:
providing a composition comprising a filler and a thermoplastic frangible pitch material containing low concentrations of polycyclic aromatic hydrocarbons comprising:
(i) a petroleum pitch having a softening point of at least about 100° C. and
(ii) an asphalt fraction having a softening point ranging from about 70° to about 160° C., wherein the asphalt fraction is produced by distillation or solvent extraction of asphalt containing petroleum crude oil, and optionally, up to about 50% of a solvent or cut back oil, and wherein the asphalt fraction has a specific gravity ranging from about 0.90 to about 1.10:
whereby the resultant frangible pitch material has a softening point in the range of about 100° C. to about 130° C., a total identified polycyclic aromatic hydrocarbon content in the range of about 5000 mg/kg or less, and is an amorphous solid at room temperature;
molding the composition to form the clay pigeon wherein the molding is carried out at temperatures that soften the frangible pitch material;
cooling the molded clay pigeon to form a clay pigeon having dense edge portions and a thin central region.
2. A method according to claim 1 wherein the molding is carried out at temperatures of at least 100° C.
3. A method according to claim 1 wherein the molding is carried out at temperatures ranging from 100° C. to 130° C.
4. A method according to claim 1 wherein the step of cooling creates internal stress in the central region of the clay pigeon, enhancing fragility.