Water-activated, exothermic chemical deicing formulations

Details Water-activated, exothermic chemical deicing formulations Water-activated, exothermic chemical deicing formulations

2002-04-18

2003-09-23

Green, Anthony J. (Department: 1755)

Compositions

Frost-preventing, ice-thawing, thermostatic, thermophoric,...

C106S013000

Reexamination Certificate

active

06623657

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATION
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
Reference to a “Computer Listing Appendix Submitted on a Compact Disc”
Not Applicable.
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The invention relates to deicing compositions for removing ice from a surface which include either succinic acid or succinic anhydride, or both, and a neutralizing base such as sodium hydroxide, potassium hydroxide, or ammonium hydroxide wherein the deicing compositions when mixed with water produce succinate salts in a reaction that rapidly releases sufficient heat to melt the ice on the surface and the succinate salts act as a deicer and freezing point depressant. In particular embodiments, the deicing compositions further include a glycol which inhibits reformation of the ice on the deiced surface. The deicing compositions are suitable and effective for airport applications in which corrosion of aircraft alloys and concrete runways are of concern.
(2) Description of Related Art
Chemical deicing is routinely used during the winter season to maintain safer mobility on highways, residential and commercial surface structures that include, parking lots, walkways, driveways, and the like. Airports and airbases also use a combination of mechanical devices and anti-icing chemicals to insure safe operations during the winter months.
Common road salt is the most widely used deicing chemical on highways. It is effective, inexpensive, reliable, and easy to store and apply. An estimated 10 million tons at $35/ton is used each year (In Highway Deicing: Comparing Salt and Calcium Magnesium Acetate, Special Report 235, Transportation Research Board Committee on the Comparative Costs of Rock Salt and CMA for Highway Deicing, Washington, D.C., (1991)). The major problem with road salt is that it is associated with costly damages to highway infrastructure, motor vehicles, and the environment. Structural damages include concrete degradation and steel corrosion leading to high maintenance expenditure. Foliage burns, soil compaction, and water contamination are some of the adverse environmental manifestations of sodium chloride use.
Due to the problems associated with the use of chloride salts as road deicing chemicals, a less harmful road deicing chemical, namely calcium magnesium acetate (CMA), has been commercialized (Miller, Ways to Help Bridges and Deicers Coexist: CMA Cuts Corrosion on Zilwaukee Bridge, Better Roads, (February 1993); Strawn, CMA has Role to Play in Critical Applications, Kuennen, Ed., Roads & Bridges, (March 1993)). Calcium magnesium acetate inhibits concrete degradation and corrosion. It is a low environmental impact deicer. The downside of CMA use is its cost, which at $925.00/ton, is 20 times as much as common road salt. Furthermore, it is not a very effective deicer.
ICEBAN is a recent development by Natural Solutions Corporation (100 Volvo Parkway, Suite 200, Chesapeake, Va. 23320). ICEBAN is a natural liquid concentrate residue prepared from the organic by-products from cheese making, the production of alcohol, or the wet milling of corn (U.S. Pat. No. 5,709,812, 5,709,813, and 5,635,101 to Janke et al. ). It is non corrosive and has good anti-icing and deicing properties. However, the most notable downside of ICEBAN is that it is formulated as a liquid deicer. Equipment currently used for spreading of deicers are configured for solid deicers. Switching to a liquid deicer requires equipment reconfigurations leading to significant capital investment in addition to the capital required for storage tanks. The viscosity of the liquid at low temperatures may pose additional problems.
European Patent EP82890136.5 to Kaes claimed that a dicarboxylic acid mixture consisting of adipic acid (30-35 wt %), glutaric acid (40-50 wt %), and succinic acid (20-25 wt %) in the form of a potash salt is suitable for airport deicing. Although this formulation, in liquid form, possesses acceptable deicing characteristics, it is corrosive to metals and, therefore, it does not comply with the standard for aircraft metals. It is four times more corrosive than potassium succinate toward dichromate treated magnesium, which is the aircraft metal alloy that is most susceptible to corrosion. Further, this product has never been commercialized.
The deicing chemicals discussed above penetrate or melt ice as a result of their tendency to form aqueous solutions that have lower freezing points. In an attempt to enhance this process, U.S. Pat. No. 4,692,259 to Roman; U.S. Pat. No. 4,400,285 to Gancy; and U.S. Pat. No. 4,425,251 to Gancy have disclosed formulations that release heat upon contact with water. The results are dual-action chemical deicers that melt ice using the heat from the exothermic reaction between the agent and water and using the freezing point depressant effect of the resulting solution.
U.S. Pat. No. 4,692,259 to Roman in its preferred embodiment presents a deicing composition that utilizes the heat of reaction of magnesium with water and the freezing point depressant effect of the resulting chloride salts.
U.S. Pat. Nos. 4,400,285 and 4,425,251 to Gancy combines the exothermicity of the contact between calcium oxide and water and the freezing point depressant effect of acetate salts to formulate dual-action deicers.
Such inventions have endeavored to formulate deicers that posses a short term exothermic response and a long term freezing point depression effect which act in a complimentary fashion to infuse a superior ice-melting function to deicers. However, the invention disclosed by U.S. Pat. No. 4,692,259 to Roman contains chloride salts. Chloride induced corrosion of metal and degradation of concrete is well documented (Miller, Ways to Help Bridges and Deicers Coexist: CMA Cuts Corrosion on Zilwaukee Bridge, Better Roads, (February 1993); Strawn, CMA has Role to Play in Critical Applications, Kuennen, Ed., Roads & Bridges, (March 1993)). In the presence of adequate moisture and oxygen, chloride ions accelerate the corrosion process by increasing the conductivity of solutions. In addition, chloride salts, especially calcium and magnesium chloride, increase the metal-moisture contact time thereby promoting the corrosion process. In addition, there is clear evidence for the cumulative and long-lasting impact of chloride salt on the environment (Strawn, CMA has Role to Play in Critical Applications, Kuennen, Ed., Roads & Bridges, (March 1993)). Salt-mist and salt solutions damage roadside vegetation. Salt solution run off causes soil compaction and high salinity reducing soil fertility and permeability leading to loss of vegetation followed by soil erosion. Both California and New York have had to take extraordinary steps to curtail the impact of road salt to the Tahoe National Forest and the Adirondack Park, respectively. Therefore, any deicer, regardless of whether it is conventional or dual-action, will have no appeal to niche markets where it is absolutely essential to minimize degradation of structures due to corrosion and minimize loss of vegetation and habitats.
The dual-action formulations disclosed in U.S. Pat. No. 4,425,251 to Gancy and U.S. Pat. No. 5,334,323 to Schrimpf et al. contain acetate salts. Acetate salts have been shown to be safer alternatives to chloride salts. Acetate-based deicers such as CMA are non corrosive toward steel and aluminum and have little or no impact on the environment. However, acetate salts are too expensive for general use on road structures and are not suitable for application on airports, airbases and airplanes.
Presently, aircraft deicing is carried out by applying propylene glycol based deicing fluids. These fluids are sprayed on aircraft to lift accumulated ice and it is believed that propylene glycol prevents ice buildup. Numerous composition and method patents exist on this application and have been disclosed in U.S. Pat. No. 4,191,348 to Holwerda; U.S. Pat. No. 4,254,821 to Matsuda et al.; U.S. Pat. No. 4,573,802 to Kerrigan et al.; U.S. Pat. No. 4,826,107 to

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