Petroleum hydrocarbon binder with reduced polycyclic aromatic hydrocarbon content
View Patent ↗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 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.
2. The pitch material of claim 1 wherein the petroleum pitch asphalt fraction comprises about 20% to about 40% petroleum pitch and about 60 to about 80% asphalt.
3. The pitch material of claim 1 wherein the petroleum pitch asphalt fraction comprises about 40 to 60% petroleum pitch and about 40 to 60% asphalt.
4. The pitch material of claim 1 wherein a ratio of petroleum pitch to asphalt is based on analysis of polycyclic aromatic hydrocarbons of all components and the ratio is about 50% petroleum pitch and about 50% other asphalt components.
5. The pitch material of claim 1 wherein the petroleum pitch comprises an amorphous solid exhibiting friability at room temperature.
6. The pitch material of claim 1 , wherein the asphalt fraction has a minimum softening point of about 71° C. (160° F.).
7. The pitch material of claim 1 , wherein the asphalt fraction has a softening point less than about 160° C.
8. A pitch material as described and claimed in claim 1 , wherein the pitch material is adaptable for use as a binder for clay pigeon targets.