Coating processes – Coating pavement or the earth
Reexamination Certificate
2000-02-15
2001-11-20
Beck, Shrive P. (Department: 1762)
Coating processes
Coating pavement or the earth
C427S188000, C427S196000, C427S214000, C427S421100, C427S426000
Reexamination Certificate
active
06319545
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of Invention
The present invention relates generally to construction of resilient surfaces and more particularly to a new and improved method of constructing resilient athletic surfaces and an apparatus for carrying out said method.
B. Description of Related Art
It has been known for some time that surfaces for the performance of athletic or similar activities are beneficially constructed with a coating of rubber particles bound by binding agents such as liquid latex material to result in a surface on which a variety of activities can take place. The resulting surface is resilient, impervious or resistant to damage by exposure to the elements, and has the capability of absorbing and draining off water without creating standing puddles. See, for example, U.S. Pat. Nos. 4,474,833 and 4,529,622, both of which are directed to a method of constructing an all-weather surface comprising essentially the steps of initially coating the surface with a tack-coat of hot asphaltic emulsion or other suitable liquid binder, followed by repetitive cycles of first spreading particulate rubber, and then spraying a liquid binding substance over the particulate rubber layer. After allowing the binder to dry, the spreading particulate and spraying binder steps are repeated until a sufficient thickness is obtained. The known method of constructing such surfaces is therefore time consuming and requires multiple pieces of machinery. The alternative methods of constructing such surfaces have been tried, specifically, mixing a slurry of rubber particulate with a liquid binder and spreading the pre-mixed slurry to the surface. This method, however, has been found to be cumbersome and difficult to apply with consistent results. The need is for a method of constructing particulate rubber surfaces in an economical and efficient operation and an apparatus for carrying out the method.
SUMMARY OF THE INVENTION
The present invention comprises a method of constructing a resilient, all-weather surface that combines the particulate dispersal and binder application steps into one operation. The method essentially comprises spreading particles by evenly dropping the particles from a spreader assembly and coating the particles with a liquid binder as they are falling toward the base surface. In the present invention, rubber particles, usually recycled from sources such as used tires, are used, although a variety of substances could be used with performance or binding characteristics varying according to the substitute materials used. The particles are small enough to produce as relatively smooth surface as is desired and sufficiently large and irregularly shaped that when coated with binder and dropped on a surface, the particles do not pack tightly together and significant interstitial spaces remain. The resulting surface is generally even but sufficiently irregular to provide traction to users. The resilience of the resulting surface is the result of both the inherent resilience of the particle material itself as well as the flexibility of the binder joining the particles at their contact points. The dry, uncoated particles are easily handled and may be spread over the surface by a variety of commercially available particulate matter spreaders, such as are used to spread fertilizer, seeds, or other agricultural products. As the particles are falling from the spreader, they are sprayed with a liquid binder material such as a mixture or emulsion of a suitable binding material such as latex and a solvent such as water. The method of the present invention may be performed by means of an apparatus which combines the particulate spreader assembly with a binder sprayer system. A commercially available spreader may be used to spread the particles in a uniform layer by controlling an even flow of particles from a hopper onto a conveyor belt. A hopper gate extends across the width of the belt to allow a controlled amount of particles to be deposited evenly across the width of the belt. The particles are conveyed by the belt to the rear of the apparatus where the belt passes over an end roller. In the illustrated preferred embodiment, a roller brush, rotating in the opposite direction, clockwise when viewed from the right side, from the end roller uniformly brushes the particles off the belt and toward the ground or base surface. The rubber particles are dropped at a uniform rate in a row from the spreader which is moved over the surface at a uniform rate. The spraying operation preferably is performed evenly and gently enough that a uniform layer of binder coated particles is spread.
The sprayer system for coating the particles with a liquid binding solution prior to the particles hitting the ground comprises a conventional power source, a source tank of liquid binder, double rows of upper spray nozzles and a lower spray nozzle, and tubing to connect the elements. Each row of upper spray nozzles comprises two nozzles, which are preferably designed to providing an even and cone like spray of liquid binder material. The spray nozzles are directed and positioned such that the spray cones of adjacent nozzles overlap slightly. The rows of upper spray nozzles are positioned serially above and behind the end roller and brush, with the upper spray nozzles directed downward and forward. The position and direction of the upper spray nozzles is such that the flow of particles is subjected to and must pass through a relatively continuous spray of liquid binder, between the conveyor belt to the base surface. A lower spray nozzle is positioned below the end roller and brush with a single spray nozzle directed upward and rearward. The spray of binder provided by the lower spray nozzle is generally in opposition to the spray provided by the upper spray nozzles, and the particles must pass through the spray of binder provided by the lower sprayer, on the way from the belt to the ground or base surface. Each of the spray nozzles in the preferred embodiment is a common nozzle with appropriately sized orifices for the viscosity of the liquid binder and available spray pressure. The spray pressure and nozzle direction are adjustable to accommodate different conditions and materials to accomplish a uniform and complete coating of the particulate by the liquid binder material before the particulate is deposited on the surface. Adjustments may also be required to avoid over or miss directed spray.
The rubber particle spreading assembly, comprising the hopper, conveyor belt system, and brush roller, is integrated with the sprayer system comprising the power source and array of nozzle heads with associated tubing. The integrated apparatus is mobile and may be self propelled or configured as a trailer to be pulled behind a tractor.
The method of the present invention utilizes the described apparatus to deposit a uniform layer of binder coated particles, preferably rubber, for each pass of the apparatus over a base surface, without need for significant raking of loose particles or separate spraying of the loose particles. Multiple passes are made as needed to achieve the desired thickness of surface material. The method of the present invention assumes that adequate surface preparation has been accomplished before the deposition of a layer of binder coated particulate by this method. The method may be applied to resurface existing tracks or other surfaces without significant advance preparation, providing the surface is as flat and level as will be desired. Since both sides of the particles are sprayed and coated with binder, it is not necessary to use an initial tack coating on the surface to ensure adherence of the particles to the surface. As currently practiced, the method of the present invention includes a final, top coat of latex with materials added to provide protection from ultraviolet light. Either the tack coat or the top coat, or both could be added to the operation without requiring a modification of the method.
The principal aim of the present invention is to provide a new and improved method of appl
Beck Shrive P.
Calcagni Jennifer
Lee Philip J.
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