Colloid systems and wetting agents; subcombinations thereof; pro – Continuous liquid or supercritical phase: colloid systems;... – Aqueous continuous liquid phase and discontinuous phase...
Reexamination Certificate
1999-12-20
2002-06-11
Metzmaier, Daniel S. (Department: 1712)
Colloid systems and wetting agents; subcombinations thereof; pro
Continuous liquid or supercritical phase: colloid systems;...
Aqueous continuous liquid phase and discontinuous phase...
C516S038000, C106S277000, C106S278000
Reexamination Certificate
active
06403659
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The invention relates to an asphalt based sealer for asphalt pavement or metal surfaces.
II. Description of the Prior Art
There are two basic types of driveway or pavement sealer—coal tar based and asphalt based. These materials are primarily used to seal driveways and other pavement surfaces, but can also be used to seal metal surfaces, e.g., pipe coatings.
Coal tar is the premier product and has the largest market share. Driveway sealer made from coal tar is an emulsion of water, coal tar pitch, clay and additives, perhaps with emulsifier and optional ingredients such as sand. These materials are long lasting, have a pleasing black color and are resistant to gasoline and kerosene spills, but have an objectionable odor during application and contain aromatic compounds.
Asphalt based materials are made from distilled petroleum fractions, typically vacuum tower bottoms or perhaps atmospheric tower bottoms. These heavy hydrocarbon fractions are sometimes oxidized or “blown” to change the asphalt properties. Asphalt based sealers do not smell as much as the coal tar based materials and are able to withstand a wider range of temperatures. The asphalt sealers are not as toxic and some states permit only asphalt based sealers to be sold. Asphalt sealers do not have the black color desired by many users. Asphalt sealers do not last as long, and frequently must be reapplied every year or every two years.
So far as is known, the asphalt based driveway sealers are all made with asphalt produced by fractionation. There is another kind of asphalt produced in refineries by solvent deasphalting. In this process, an asphaltene containing crude is mixed with a solvent, or more properly speaking, an anti-solvent such as propane or butane. The presence of large amounts of aliphatic anti-solvent causes the highly aromatic asphaltenic material to precipitate out of solution, or at least form a separate asphalt rich phase. This material, produced as the bottoms or heavy phase in a solvent deasphalting unit, is commonly referred to as SDA or ROSE bottoms.
It is a low value product in many refineries, in some ways almost a distress product. The non-selective nature of the deasphalting process leaves large amounts of non-asphaltenic material in the SDA bottoms. The SDA asphalt is believed to make poor quality roads. Many refiners cut back this material with kerosene or other cutter stock and sell the thinned asphalt as low value fuel oil. U.S. Pat. No. 4,686,027 describes sending SDA asphalt and some solvent to a delayed coker. This shifts some of the work of solvent recovery to the coker and efficiently dispatches the SDA asphalt to the coker.
SDA asphalt has never been used to make driveway sealer because it is soft (and contaminated with heavy oily species which are not asphalt). There is concern that it would “track” asphalt into a house. A refiner or driveway sealer manufacturer may have blended some SDA asphalt into a vacuum bottoms asphalt and produced a low quality driveway sealer, but SDA asphalt was probably not more than 10 or 15% of the total asphalt content of the sealer and there is no literature reference to this application.
U.S. Pat. No. 5,059,300 disclosed use of 1 to 15 wt SDA asphalt mixed with 0.1 to 20 wt of phosphoric acid and the balance being vacuum distilled asphalt.
U.S. Pat. Nos. 5,728,291 and 5,601,697 disclosed blends of SDA asphalt, vacuum distilled asphalt and an aromatic extract for road asphalt.
Representative asphalt driveway sealer art is reviewed below.
U.S. Pat. No. 5,558,702, Chatterjee et al, ASPHALT EMULSIONS CONTAINING AMPHOTERIC EMULSIFIER, taught use of asphalt emulsions to “avoid the use of coal tar and its derivative”.
U.S. Pat. No. 5,667,576, Chatterjee et al, ASPHALT EMULSIONS, taught forming an asphalt emulsion from AC-20 asphalt and an emulsifier and mixing with varying amounts of a lime/clay/sand/carbon black mixture.
The '576 patent has a goal of “identifying satisfactory asphalt emulsions which are free of coal tar and coal tar derivatives . . . ” It discloses as suitable “either a naturally-occurring asphalt . . . It can be a coal tar or coal tar derivative” (or) “straight-run asphalts, propane asphalts, air-blown asphalts, thermal asphalts, blended asphalts, and the like.” While many asphalts are recited, only AC-20 was chosen. AC-20 was, at the time this application was filed on Mar. 24, 1995, an asphalt produced by distillation.
The driveway sealer art and commercial activity could be summarized as follows. Most sales and work reported in the patent literature is of or about coal tar based material. The much smaller sales volume and research work on asphalt based material is believed limited to asphalts obtained by distillation. There is little or no work on use of SDA asphalts for driveway sealers.
We wanted to see if acceptable driveway sealers could be made from SDA asphalts. This would permit a better use of the S DA asphalt and permit production of a low cost driveway sealer with acceptable properties. The SDA asphalt based sealer is not intended to equal in quality the coal tar based product. The SDA, or other solvent derived asphalt product, is intended to be an acceptable substitute for existing driveway sealers made from asphalts obtained by distillation.
The key to successful use of SDA asphalts and the like was use of a relatively high softening point asphalt material and careful mixing with a cutter solvent, preferably a highly aromatic solvent such as an aromatic extract or cycle oil.
BRIEF SUMMARY OF THE INVENTION
Accordingly, the present invention provides a method of making a binder or sealer base of solvent deasphalted asphalt comprising heating a solvent deasphalted (SDA) asphalt having a softening point above 60° C. to a temperature sufficient to maintain a molten state, blending a liquid hydrocarbon cutter oil having less than 10 wt % material boiling below 300° C. with said molten asphalt to form a mixture of molten asphalt and cutter oil.
In another embodiment the present invention provides driveway sealer emulsion of water, clay and sealer base, wherein said sealer base is prepared by the method of the preceding paragraph.
DETAILED DESCRIPTION
For clarity, and to avoid the confusing terminology used in many patents, several terms will be defined. This “definition” section is intended as an overview, with detailed specification for each material provided later.
Driveway sealer means a driveway or paving sealer comprising:
water,
clay,
emulsifier and
“sealer base” or “binder”.
The sealer base or “binder” is the hydrocarbon portion of the driveway sealer. This bonds with or acts as a “binder” for the pavement or driveway. Sealer base of the prior art was coal tar pitch for coal tar based driveway sealers and an asphalt obtained by distillation for prior art asphalt driveway sealers.
Sealer base or “binder” of the invention comprises a blend of:
asphalt (or bitumen) produced by solvent deasphalting, and
a cut-back oil.
Prior art driveway sealers used asphalt (or bitumen) obtained as the heavy fraction left after distilling an asphaltic crude. Usually two stages of distillation are used, the first at atmospheric pressure and the second under vacuum distillation to produce a vacuum bottoms asphalt product from which distillable hydrocarbons have been removed. Tar sands from Lake Athabasca and the like may also be eventually conventionally processed and distilled to produce a heavy residue fraction which qualifies as “asphalt” or “bitumen.”
Driveway sealers of the invention will use significant amounts of asphalt obtained by a solvent deasphalting process, such as propane deasphalting or the ROSE process. For convenience, such materials will usually be referred to hereafter as SDA asphalt.
It is possible to blend SDA asphalts and asphalts obtained by distillation, and in many instances it will be beneficial to add a pitch component as well. Pitch is defined below.
Pitch could generically be defined as a heavy thermal tar resulting from thermal polymerization of lighter
Boyer D. Chris
Doolin Patricia K.
Marathon Ashland Petroleum LLC
Metzmaier Daniel S.
Stone Richard D.
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