Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-10-20
2002-11-26
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S376000, C524S377000, C524S378000
Reexamination Certificate
active
06486249
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to the field of release agents for use in preventing asphalt and other sticky compounds such as rubbers from sticking to the transporting vehicles such as dump truck beds and processing tools, and equipment, and more particularly to a novel release agent applied to metal surfaces prior to use for promoting free release of sticky hot-mix asphalt materials from the metal or plastic tools and equipment used in road construction applications.
DESCRIPTION OF THE PRIOR ART
Many roads are paved with asphalt produced on site or an asphalt plant in close proximity to an asphalt plant and is transported to the construction site in large trucks with metal beds, typically referred to as “dump trucks”. There the asphalt is spread and applied to existing asphalt pavement or a rock or concrete base, with shovels, rakes, and other metal tools usually in addition to a large paving machine and or grader. Problems occur due to the asphalt tending to stick on contact to any surface preventing total emptying of the load from a dump truck bed and adding unneeded weight to tools used to form and compress the asphalt in the selected areas. Since the asphalt is usually heated and is transported and applied in the hot state, the differentiation in temperatures between the asphalt and metal surfaces serves to cause sticking problems. Thus, the main disadvantage is that the sticking of the asphalt to the surface of the truck bed prevents the asphalt from smoothly sliding out of the metal truck bed as the dump truck attempts to discharge its asphalt load onto the road surface or into a paving machine. Time is wasted coaxing the asphalt out of the truck bed and the workers are exposed to hot asphalt which may contain petroleum based chemicals creating undesirable exposure to workers. Coating of the asphalt on to drums, storage tanks, trailers, piping, tires, and rollers causes cleanup and maintenance problems.
Conventional asphalt release agents known in the art to prevent asphalt from sticking to metallic surfaces were often based on chemicals commonly available at the construction site. For instance, kerosene or diesel fuel was often used to provide a release agent; however, these fuel oil based chemicals are flammable and often act as a solvent to dilute or cut the asphalt impairing the structural integrity of the asphalt product applied to the road surface. There are also environmental concerns relating to the use of fuel oil based release agents due to application and absorption of the oil based release agents into the ground and the evaporation of same especially in light of the exposure to the workers. Moreover, these traditional oil based cutting agents are not always effective against modern asphalt compositions.
An important consideration of the present invention is its effectiveness as an asphalt release agent for various compositions of asphalt in view of new types of asphalt mixes such as rubber based asphalt, asphalt containing polymers as well as conventional asphalt.
In the case of paving asphalt, a typical paving asphalt mixture comprises a mixture of components. The principal ingredients of the paving asphalt mixture being an asphalt composition or cement and aggregate or aggregate material usually containing rock and/or gravel. In such mixtures, the ratio of asphalt composition to the aggregate material varies, for example, according to the aggregate material type and the nature of the asphalt composition. As used herein, the terms “asphalt composition” or “asphalt cement” are understood to refer to any of a variety of organic materials, solid or semi-solid at room temperature, which gradually liquefy when heated, and in which the predominant constituents are naturally occurring bitumens or residues commonly obtained in petroleum, synthetic petroleum, or shale oil refining, or from coal tar, or the like. For example vacuum tower bottoms produced during the refining of conventional or synthetic petroleum oils is a common residue material useful as asphalt composition. A “paving asphalt composition” or “paving asphalt cement”, accordingly, is an asphalt composition or asphalt cement having characteristics which dispose the composition for use as a paving material, as contrasted, for example, with an asphalt composition suited for use as a roofing material. “Roofing asphalt”, for example, usually have a higher softening point, and are thus more resistant to flow from heat on roofs. The higher softening point is generally imparted to the material by the air blowing processes used for producing the material. Although the present invention can be used with any type of asphalt composition or aggregate mix therewith, paving grade asphalt are typically utilized with the present invention. Paving asphalt mixtures may be formed and applied in a variety of ways. For example, the paving asphalt composition and the aggregate are typically mixed and applied at elevated temperatures at the fluid state of the paving asphalt composition to form the pavement or road surface. However, the asphalt composition may also be applied in alternating layers with the aggregate mix.
The paving grade asphalt compositions may be composed of any know bituminous or asphaltic substance obtained from natural sources and/or derived from petroleum, shale oil, coal tar, and the like, as well as mixtures of two or more of such materials. The paving asphalt compositions are often referred to as viscosity or penetration grade asphalt, having original penetrations up to 400 as measured by ASTM method D%. Preferred asphalt are the normal paving asphalt such as AC2.5, AC5, AC10, AC20, AC30, and AD40. The designation “AC” in the title define the “asphalt cement” and the number indicates the viscosity at 60° C. in poise multiplied by 100. Typical of such asphalt are the straight run asphalt derived from the atmospheric, steam and/or vacuum distillation of crude oils, or those asphalt derived from solvent precipitation treatments or raw lubricating oils and their fractions. Also included, are the thermal or “cracked” asphalt which are separated as cracker bottom residues from refinery cracking operations and the asphalt produced as by-products in hydro-refining operations. A preferred asphalt is the vacuum tower bottoms that are produced during the refining of synthetic or petroleum oils. The asphalt may be treated or modified before use in the invention.
Inventions taught by the prior art typically employ an approach to formulation by providing a release agent which contains components capable of attacking asphalt material and therefore soften the asphalt in immediate contact with coating of the release agent applied on the surface of the transporting vehicles such as the bed of a dump truck used for hauling the hot-mix asphalt in road constructions. Such components include petroleum base oils such as diesel and biodegradable vegetable oils and animal fats. Although vegetable oils and animal fats are less aggressive than diesel whose use as an asphalt release agent is prohibited by law, they can still strip asphalt from the hot-mix at an elevated temperature commonly observed in road constructions and hence weaken the strength of the construction material which must meet strict criteria set between governmental and/or technical organizations such as the Department of Transportation (DOT) of US Government and local states. The stripping of asphalt from the hot-mix aggregates by release agents based on petroleum products or vegetable oils and animal fats often possess an unpleasant odor, attracting insects such as flies and therefore presenting a health hazard to the surrounding area nearby.
SUMMARY OF THE INVENTION
The invention is a composition for a release agent for use in preventing asphalt and other sticky compounds such as rubbers from sticking to the transporting vehicles such as dump truck beds and processing tools, and equipment, and more particularly to a biodegradable release agent applied to metal surfaces prior to use for promoting free release of sticky hot-mix asphalt materi
Dituro Michael A.
Dotson Daniel J.
Fang Jiafu
Lockwood Frances E.
Ashland Inc.
Carrithers David W.
Carrithers Law Office
Nutter Nathan M.
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