Compositions – Frost-preventing – ice-thawing – thermostatic – thermophoric,...
Reexamination Certificate
2002-05-06
2003-05-13
Green, Anthony J. (Department: 1755)
Compositions
Frost-preventing, ice-thawing, thermostatic, thermophoric,...
C106S013000
Reexamination Certificate
active
06562256
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to self-dispersing particulate materials, and more particularly, to self-dispersing particulate materials containing pressurized gas that is trapped in discrete cavities or pockets inside a continuous matrix. The matrix material is solid prior to use but is partially dissolved during use to spontaneously liberate pockets of the entrapped, pressurized gas. When liberated during use, the gas exerts sufficient force to propel or rapidly reposition the particle from which the gas is expelled. This repositioning causes random scattering and dispersion of the particulate material. Useful applications for the composition include, for example, deicers, drain cleaners, fertilizers, insecticides, floor cleaners, and the like.
2. Description of Related Art
The use of particulate deicers such as mineral salts for melting ice and snow is well known. Such particulate materials are typically scattered by hand or with a broadcast-type spreader over an icy surface. Unfortunately, the coverage achieved with such distribution methods is often irregular, especially when the materials are broadcast manually. Ice contacted by the deicer particles typically melts in a crater around the particle, forming a small pool of water that can insulate the particle from further contact with the surrounding ice, thereby slowing melting. Although liquid deicer compositions are also available and provide good coverage, they are most often applied using mechanical sprayers and often exhibit the associated disadvantage of producing a surface that is more slippery, and therefore more hazardous to pedestrian or vehicular traffic, than an icy surface having a particulate mineral composition scattered over it. A dry particulate deicer composition is therefore needed that includes at least one component capable of melting ice and at least one other component capable of continually dispersing and redistributing the melting component across an icy surface to achieve improved particle dispersion. Other systems for thermochemical ice melting are disclosed in U.S. Pat. No. 5,176,210. Prior art patents such as, for example, U.S. Pat. Nos. 3,012,893, 3,985,909 and 3,985,910, disclose the manufacture of flavored and colored, gas-containing, candy particles that “pop” or “explode” whenever entrapped pockets of compressed carbon dioxide gas are liberated as the sugary material dissolves upon contact with saliva or other liquids. Generally speaking, such candies are made by injecting gas into heated sugar syrup while under pressure, thereafter cooling to solidify the syrup, releasing the pressure and fracturing the glassy candy into particles. Such novelty items do not, however, serve any other beneficial purpose or perform any other function or utility that is worthwhile in connection with other consumer, commercial, governmental, institutional, industrial, recreational or environmental needs or objectives.
Other prior art relating to gasified candies and methods and apparatus for making them include, for example, U.S. Pat. Nos. 4,001,457; 4,262,029; 4,273,793; and 4,289,794.
SUMMARY OF THE INVENTION
The self-dispersing particulate composition of the invention is desirably a product in the form of pellets, prills, flakes or granules that comprises particles containing a first functional component capable of releasing pressurized gas in combination with particles containing a second functional component, or special-use component, having at least one additional utility. Such additional utilities can vary widely, depending upon the chemical makeup of the special-use component, and can include, for example, the capability for functioning as a deicer, a fertilizer, a drain cleaner, an insecticide, or the like. According to one embodiment of the invention, the subject composition is a mixture of dispersing particles and special-use particles. According to another, particularly preferred, embodiment of the invention, the subject composition contains only a single type of particle, which embodies both the self-dispersing and special-use components.
The advantages of using the self-dispersing particulate compositions of the invention in comparison to other conventional, commercially available products can vary according to the particular use that is intended. Where the special-use component is a deicer, for example, the dispersing component causes the special-use component to be spread to other nearby areas where no melting has yet occurred. Besides deicers, other commonly used products consisting of particulate materials can also be made more effective by providing an innate or collateral ability for the particles to randomly reposition themselves during use. Such products can include, for example, particulate fertilizers, insecticides, and the like. In other applications, such as where the special-use component is a drain cleaner, the pressurized gas released by particles containing the dispersing component at the point of use, such as inside a P-trap, can assist in dislodging matter clogging the drain as it is being dissolved or otherwise acted upon by the special-use component.
According to one preferred embodiment of the invention, a self-dispersing particulate product intended for use as a deicer, the composition comprises particles having a solid phase containing an alkaline earth metal salt such as calcium chloride or magnesium chloride dissolved or dispersed in a glassy, sugary material, and finely divided bubbles of pressurized gas disposed within the fused, glassy material. During use of the subject composition, the particles are initially scattered across an icy surface to be treated. As melting occurs due to hydration of the salt, the resultant water also causes the glassy, sugary material to begin dissolving away, eventually exposing pockets of pressurized gas disposed inside the particles. As the glassy part of the particles begins dissolving, pressurized gas escapes forcibly from each successively exposed cavity in which it was previously entrapped during manufacture. This successive, forcible liberation of gas from cavities inside the particles, as the wall around each cavity dissolves, repeatedly causes the particles to be propelled to other positions, sometimes inches or even feet away. For illustrative purposes, the resultant effect is similar to the way popcorn kernels are propelled when moisture inside them is vaporized during cooking, causing the kernels to “pop” around to different positions. The subject composition is useful for melting ice from surfaces such as sidewalks, steps, ramps, roadways, runways, bridges and the like. Alternatively, the dispersing and special-use components can be disposed in different particles, which are then intermixed to form the subject composition.
According to another embodiment of the invention, the dispersing component of the subject composition preferably contains sufficient finely divided, dispersed, trapped, compressed gas that, when liberated upon contact with moisture, the gas will exert a force adequate to move the particle from which the propellant is released to a different position on an underlying surface. Although not preferred, dispersing components can also be made that contain reactants capable of rapidly generating a quantity of pressurized gaseous propellant that is sufficient to relocate or reposition a particle when contacted by moisture or another substance present in the use environment. Preferably, the force generated through release of the propellant will be sufficient to relocate the propelled particle a distance that is at least several times the maximum particle dimension. When the dispersing component and the special-use component of the invention are contained in separate particles, the particles containing the dispersant will desirably move with sufficient momentum when activated to collide with particles containing the special-use component and cause repositioning of those particles as well. In the latter case, the use of from at least about 5 to about 50 percent or more, a
Fleming Wayne Anthony
Holdar Robert Martin
Pearce, III Robert Clarence
Green Anthony J.
Locke Liddell & Sapp LLP
NCH Corporation
Ross Monty L.
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