Coating processes – Removable protective coating applied
Reexamination Certificate
2001-04-13
2003-07-08
Beck, Shrive P. (Department: 1762)
Coating processes
Removable protective coating applied
C427S156000, C427S421100, C427S426000, C118S699000, C118S706000, C239S087000, C239S099000, C239S398000, C239S407000
Reexamination Certificate
active
06589595
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of preventing asphalt from sticking to paving equipment, utilizing a device that will apply a release coating to paving equipment surfaces, said coating is a diluted mixture of a viscous concentrate, and said coating is a viscous solution. The method comprises:
1) coating a paving equipment surface by spraying, rolling or brushing with a release agent,
2) adding or contacting tar or asphalt to the equipment or otherwise handling or using the asphalt with the sprayed equipment, and
3) separating the asphalt from the equipment by releasing it at its point of intended use or
4) otherwise releasing the tar or asphalt from the paving equipment.
The method utilizes a piece of equipment that makes it possible to spray on highly-viscous dilutions of highly-active asphalt release agents. The device consists essentially of:
1) a carbonator pump or other vaned, positive-displacement pump which produces a minimum flow of about one gallon per minute (“1 GPM”) and 200-300 pounds per square inch (“psi”) pressure; and associated electric motor to drive the pump,
2) a timer relay to control the pump and motor,
3) an induction/injection valve with a high induction capacity resulting in a dilution ratio of to concentrate as low as about a 10/1 dilution ratio, even with viscous concentrates,
4) a spray gun with an appropriately-sized nozzle, (or a spray bar and a multiplicity of nozzles) and
5) necessary tubing, fittings, connections, control buttons, a box to enclose the apparatus, as well as a pressure relief valve and/or bypass valve, freeze protection, a particulate-filtering screen or screens, a solenoid to prevent non-pumped release of the release coating as optional ancillary devices.
The singular advantages of the instant invention are that the system utilizes only one pump, the components are very durable, so the system is therefore robust, and the system is able to deliver effective sprays of highly-viscous release coatings, in the right and adjustable dilution ratio, and from viscous concentrates.
2. Prior Art
2.1. General Considerations
It is well-known in the industry that tar and asphalt, used in their molten or liquid state, have a strong tendency to adhere to surfaces of the equipment used to handle, transport and otherwise use them. This buildup can be severe, rendering the equipment completely unsuitable for its purpose.
One traditional way to address this problem has been to spray the equipment with diesel fuel, which forms a lubricating layer in between the asphalt and the equipment. However, for regulatory and other reasons, this has become an obsolete method.
2.2. Examples of Prior and/or Related Art
One response to the regulatory pressure to stop using diesel fuel has been to use other, less environmentally-unacceptable alternative solvents. An example of this type is “004”, a citrus-based solvent sold by the Zep Company. It is used to clean paving equipment and to prevent tar or asphalt from sticking to the equipment in the first place. This type of solvent suffers from several drawbacks, at least one of which is the increased cost compared to diesel fuel.
Another drawback to this approach is that frequently the solvents chosen have a detrimental effect on the asphalt or tar in its final location, leading to a decreased strength of the resultant surface. For this reason, most such solvents can not be approved by state departments of transportation (DOT) for use as truck bed release agents, and so cannot be used on truck beds that are carrying asphalt to pave on state roads.
Typically, the tests are rather severe, for instance allowing contact between asphalt and solvent for 24 hours, and determining if there is any discoloration whatsoever in the solvent mixture. Most solvents used for release agents are unable to pass such a test.
Another response has been to utilize water-dilutable formulations. The major solvent in this situation is water, which is cheap and plentiful, and known to repel asphalt. However, many of these materials suffer from serious drawbacks, leading to a reputation in the industry that they are ineffective. The major drawback with such poorly-performing formulations is that they are mostly water to begin with, and the resultant highly-dilute water film is insufficiently persistent.
Other water-dilutable formulations, such as LiquiSlip by the Dubois Corporation utilize a combination of these two methods. The concentrate contains a petroleum solvent and emulsifiers, and a special machine combines the concentrate with water to form a creamy emulsion, which the apparatus sprays on the surfaces to be release coated, and the coating acts to prevent asphalt from sticking. The major problems associated with this approach are that it involves petroleum-based solvents, and that two pumps and a specialized delivery system are required to make it work.
The petroleum solvent in the product makes it unacceptable to accidentally spray it on the ground. The emulsified product is highly-viscous when diluted, and so spraying it requires two pumps, one to pump the concentrate, and another to pump the diluted mixture. This approach can be undesirable, moreover, due to the increased costs associated with utilizing two pumps, both in terms of initial capital, and in terms of difficulty, frequence and cost of maintenance, balancing the outputs of the two pumps, etc.
A formulation recently patented by Chemtek, Inc., is the subject of U.S. Pat. No. 6,126,757. This formulation comprises primarily fatty acids neutralized by organic nitrogenous bases, and fatty acid amides. The formulation is rather viscous, and the resulting dilutions are very viscous.
No device currently known to be on the market is able to adequately and inexpensively deliver dilutions of these formulations, and so a special device was required. It is the object of this invention to provide such a device, to be able to utilize the above-mentioned formulation. This device utilizes only one pump, and so minimizes the expense and difficulty associated with the products' delivery.
SUMMARY
An object of the present invention is to provide a method to prevent tar or asphalt from sticking to paving equipment, but without resorting to using solvents that may attack the asphalt. Another object of the present invention is to provide a method of utilizing water as a diluent, a cheap, plentiful diluent that also repels asphalt. It is another object of the present invention to provide a method to protect equipment from getting tar or asphalt stuck to them without resort to petroleum-based, natural-origin or chlorine-containing solvents.
These and other objects of the present invention have been attained by the present inventors' discovery of a method for preventing asphalt and tar from sticking to paving equipment, comprising contacting the surfaces with a dilution of a concentrated solution by spraying the diluted concentrate on the equipment prior to contacting the equipment with asphalt or tar, said spraying equipment to include, but not be limited to:
1) a carbonator pump or other vaned, positive-displacement pump which produces a minimum flow of about one gallon per minute (“1 GPM”) and 200-300 pounds per square inch (“psi”) pressure; and associated electric motor to drive the pump,
2) a timer relay to control the pump and motor,
3) an induction/injection valve with a high induction capacity of as low as about a 10/1 dilution ratio, even with viscous concentrates,
4) a spray gun with an appropriately-sized nozzle, (or a spray bar and a multiplicity of nozzles) and
5) necessary tubing, fittings, connections, control buttons, a box to enclose the apparatus, as well as a pressure relief valve and/or bypass valve, freeze protection, a particulate-filtering screen or screens, a solenoid to prevent non-pumped release of the release coating as optional ancillary devices.
DESCRIPTION OF THE INVENTION
This invention relates to a method of preventing tar and asphalt from sticking to paving equipment. The method comprises coating a
Beck Shrive P.
Chemtek, Inc.
Kolb Michener Jennifer
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