Compositions – Frost-preventing – ice-thawing – thermostatic – thermophoric,...
Reexamination Certificate
2001-11-12
2003-04-08
Green, Anthony J. (Department: 1755)
Compositions
Frost-preventing, ice-thawing, thermostatic, thermophoric,...
C106S013000
Reexamination Certificate
active
06544434
ABSTRACT:
The present invention relates to a deicing fluid composition. More particularly the present invention relates to a deicing fluid composition which is environmentally benign. Most particularly the present invention relates to an environmentally benign deicing fluid composition which is obtained from various industrial waste streams or from the pure components.
BACKGROUND OF THE INVENTION
Freezing point lowering compositions are in widespread use for a variety of purposes, especially to reduce the freezing point of an aqueous system so that ice cannot be formed or to melt formed ice. Generally, freezing point lowering compositions depend for their effectiveness upon the molar freezing point lowering effect, the number of ionic species which are made available and the degree to which the composition can be dispersed in the liquid phase in which the formation of ice is to be precluded and/or ice is to be melted.
The most pervasive of the commonly used products for deicing are common salt, calcium chloride and urea, with common salt (sodium chloride) being the least expensive and most commonly used. Common salt is widely used to melt ice on road surfaces and the like. In this manner the salt forms a solution with the available liquid in contact with the ice and thereby forms a solution with a lower freezing point than the ice itself so that the ice is melted. Chloride salts however suffer from relatively severe drawbacks, such as the harmful effects on surrounding vegetation by preventing water absorption in the root systems, and its corrosive effects on animal skin such as the feet of animals, clothing, roadways and motor vehicles.
Other inorganic salts are also known to be useful as freezing point lowering agents such as magnesium chloride, potassium phosphates, sodium phosphates, ammonium phosphates, ammonium nitrates, alkaline earth nitrates, magnesium nitrate, ammonium sulfate, alkali sulfates.
Typical of solutions of low freezing points include brines, ethylene glycol and propylene glycol solutions. Brines are used to transfer heat at temperatures below the normal freezing point of water, and the ethylene glycol solutions are well known for use as coolants for automobiles and the like in regions in which the temperature may fall below the normal freezing point of water. Ethylene and propylene glycols are used in relatively large quantities at major airports in northern climates in order to keep air traffic flowing during inclement weather. The fluids are generally applied to the wings, fuselage and tail of aircrafts as well as the runways to remove ice. However, these glycol compounds likewise have environmental drawbacks and can be detrimental to sewage treatment processes.
Other prior art deicing fluids such as alcohols have toxic effects and high volatility particularly in the low molecular weight range and may be the cause of offensive smell of fire danger. Furthermore, mono- and polyhydric alcohols oxidize in the presence of atmospheric oxygen to form acids, which can increase corrosion of materials.
Due to the problems associated with deicing agents as described above there have been attempts to prepare even more deicing agents. For, example, Kaes, U.S. Pat. No. 4,448,702 discloses the use of a freezing-point lowering composition and method which calls for the addition of a water soluble salt of at least one dicarboxylic acid having at least three carbon atoms, such as a sodium, potassium, ammonium or organoamine salt of adipic, glutaric, succinic or malonic acid.
Peel, U.S. Pat. No. 4,746,449 teaches the preparation of a deicing agent comprising 12-75% acetate salts, trace-36% carbonate salts, 1-24% formate salts and 1-32% pseudolactate salts which is prepared from a pulp mill black liquor by fractionating the black liquor into a molecular weight fraction and concentrating the collected low molecular weight fraction to produce the deicing agent.
U.S. Pat. No. 4,960,531, teaches that small amounts of methyl glucosides, i.e. less than 10%, can be employed as a trigger to conventional salt deicers.
However, all of these disclosures still require the presence of salts. Accordingly there still exists in the art a need for a deicing and/or anti-icing agent which is environmentally benign and relatively inexpensive to obtain.
SUMMARY OF THE INVENTION
Accordingly the present invention comprises a deicing and/or anti-icing agent which is environmentally benign and can be produced from relatively inexpensive feedstocks. In one embodiment of the present invention the deicing agent comprises a water soluble solution of hydroxycarboxylic acid based esters which are preferably prepared from waste process streams such as from the admixture of components of a pulp mill black liquor with distiller grain solubles and/or whey; the acid treatment of pre-distilled wood, agricultural and/or milk fermentation; the alcoholysis of distiller grain solubles or any combination thereof.
The compositions of the present invention can be applied to a wide variety of surfaces, particularly metallic and non-metallic surfaces of aircraft, which prevents icing, removes frozen water from the surface and prevents its reformation. The invention provides for a deicing composition which can be used on airplanes, runways, bridges, streets and the like. Further, the compositions can be used in heat transfer applications and to applications in which it is vital to maintain a liquid in the unfrozen state, e.g., as in a fire extinguisher. Additionally, the present invention provides for an anti-icing composition which can be applied to a surface, such as bridges, prior to the onset of icing conditions in order to prevent icing from occurring.
The present invention further provides deicing and/or anti-icing agents which are prepared from the pure components, hydroxycarboxylic acid esters, hydrocarbyl aldosides, and or combinations thereof. In one further embodiment of the present invention there is provided a method for deicing and/or anti-icing a surface, the method comprising applying to the surface a composition comprising (a) a deicing and/or anti-icing agent comprising at least about 15 weight percent of a hydrocarbyl aldoside and (b) water. In another further embodiment, there is provided a deicing and/or anti-icing agent composition comprising (a) a hydroxycarboxylic acid salt, (b) a hydrocarbyl aldoside and (c) water.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
The present invention provides a novel composition useful as a deicing agent and/or an anti-icing agent and a novel method of preparing the deicing and/or anti-icing agents.
The deicing agents of the present invention comprise a hydroxycarboxylic acid ester, a hydrocarbyl aldoside, or both.
Hydroxycarboxylic acid esters are well known to those of ordinary skill in the art and typically comprise hydroxyformate, hydroxyacetate, hydroxypropionate, hydroxybutyrate, hydroxylaurate, hydroxypalmitate, hydroxyoleate, hydroxybenzoate as well as others. Preferred for use in the practice of the present invention are deicing agents comprising &agr;-hydroxypropionate type esters such as alkyl lactates.
Hydrocarbyl aldosides are well known to those of ordinary skill in the art. Preferably the hydrocarbyl aldosides comprise alkyl aldosides and/or sorbitols.
The alkyl aldosides can be prepared by a continuous alcoholysis process for making mixed aldoside from polysaccharides, and more particularly, for making mixed alkyl glycosides directly from starch, as described in U.S. Pat. No. 4,223,129. A further process of producing aldosides for use in the practice of the present invention is described in U.S. Pat. No. 4,329,449.
Typical of the alkyl aldosides useful in the practice of the present invention are alpha-methyl glucoside, beta-methyl glucoside, methyl furanosides, methyl maltosides, methyl maltotriosides, mixtures thereof and the like.
In addition to the hydroxycarboxylic acid esters and/or hydrocarbyl aldosides, a wide variety of other components may be included in the deicing and/or anti-icing compositions of the present invention. Along with the free hydr
Green Anthony J.
Hedman & Costigan ,P.C.
Metss Corporation
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