De-icing solution

Details De-icing solution De-icing solution

2001-10-04

2002-08-27

Green, Anthony (Department: 1755)

Compositions

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

C106S013000

Reexamination Certificate

active

06440325

ABSTRACT:

BACKGROUND OF THE INVENTION
The current state of the art for coping with snow and ice on roads usually involves applying a deicer material such as a salt to the road surface. Sometimes antiskid materials such as sand or other aggregates such as gravel are added with or without a salt.
The use of salt and compositions having high concentrations of salt, cause an undesirable corrosive effect on vehicles, the road surface, and the environment with respect to the run off of water containing salt which contaminates the surrounding land and water.
Considering the above problems associated with salt formulations, there has been a continuing need for a deicing composition or formulation which can effectively melt snow and ice yet which reduces the corrosion and environmental contamination referred to above. In response to the above problems associated with the use of road salt, the prior art has looked to alternative formulations which are less corrosive and more environmentally friendly.
U.S. Pat. No. 5,635,101 (Janke et al.) relates to a deicing composition containing a by-product of a wet milling process of shelled corn. Corn kernels are steeped or soaked in a hot solution containing small amounts of sulfurous acid. The corn kernels are separated from the steep water and steep water solubles are used in the production of a deicing composition.
U.S. Pat. No. 4,676,918 (Toth et al.) relates to a deicing composition which comprises a mixture containing at least one component selected from a number of chlorides or urea and an admixture of waste concentrate of alcohol distilling that has a dry substance content of from 200 to 750 g/kg and from 10% to 80% by weight of water.
U.S. Pat. No. 6,080,330 (Bloomer) teaches a composition for use in preventing the formation of ice or snow on outdoor surfaces, such as roadways or aggregate stockpiles, and also for deicing surfaces upon which snow or ice has formed. The composition is formed from a waste product of the process of removing sugar from sugar beet molasses, also known as desugared sugar beet molasses.
The Janke et al., Toth et al. and Bloomer materials are naturally occurring substances with hundreds (if not thousands) of components such as complex carbo- hydrates, starches, sugars, proteins etc. and are normally used with a salt.
The above de-icing solutions now being introduced in the field employ agricultural residues e.g., corn based distillers solubles and solubles from the corn wet milling industries. These naturally occurring substances, which also include brewers condensed solubles, are extremely variable in composition, viscosity, film forming tendency, freezing temperature, pH etc., and consequently give varying performance when used in de-icing solutions. Depending upon the source and batch, these materials at low temperatures sometimes exhibit such resistance to flow that they cannot be applied evenly to a road surface or mixed with a chloride, rendering them virtually unsuitable for use.
Furthermore, these patents utilize materials which have highly undesirable or unnecessary ingredients leading to practical difficulties by manufacturers and users, such as stratification in storage, biological degradation, odor, plugging of filters and spray nozzles and environmental difficulties e.g. high biological oxygen demand due to the very high organic contents (about 40% by weight), presence of phosphorus compounds and heavy metals.
To improve quality and performance, and to meet current mandated standards, there is an immediate need for synthetic, chemically modified thickeners, and carefully purified materials which can be substituted for the currently used agricultural residues. Such a formulation would improve performance and reduce metal corrosion, spalling of concrete, toxicity and addresses environmental concerns.
It is therefore an object of the present invention to provide a deicing formulation which exhibits improved performance standards which overcomes the prior art problems described above.
It is a further object of the present invention to provide a deicing formulation which utilizes a synergistic combination of a low molecular weight carbohydrate and an inorganic freezing point depressant.
It is another object of the present invention to provide a deicing formulation which utilizes a low molecular weight carbohydrate to provide for improved ice melting properties and exhibits less corrosion.
It is a further object of the present invention to provide a deicing formulation which provides consistent physical and chemical properties, thereby assuring consistent quality and performance.
It is another object of the present invention to provide an economical, highly effective deicing formulation.
SUMMARY OF THE INVENTION
The present invention is based upon the discovery that low molecular weight (about 180 to 1,000) carbohydrates when used with an inorganic freezing point depressant such as a chloride salt has a synergistic effect upon freezing point depression. The formulation of deicing/anti-icing compositions employs carbohydrates of less than about 1,000 molecular weight, such as glucose/fructose, disaccharides, trisaccharides, tetrasaccharides, pentasaccharides, hexasaccharides, and mixtures thereof. The broader operative range for the carbohydrate molecular weight is from about 180 to 1,500, with the range of about 180 to 1,000 being preferred.
The basic composition of the present invention consists of at least the first two of the following three components in aqueous solution depending upon ambient weather conditions, terrain, nature and amount of freezing/snow precipitation, and environmental concerns:
(1) Inorganic freezing point depressants preferably in the form of chloride salts which include magnesium chloride, calcium chloride and sodium chloride. Metal acetates e.g. calcium magnesium acetate, and other suitable acetates may also be used.
(2) Low molecular weight carbohydrates in the 180 to 1,500 range (180-1,000 preferred). These carbohydrates can be obtained from a wide range of agricultural based products such as those derived from corn, wheat, barley, oats, sugar cane, sugar beets etc.
(3) Thickeners are used in certain applications as the third key component to increase the viscosity of the composition so that the liquid remains in contact with the road surface or with the solid particles in piles of rocksalt/sand, or rocksalt/aggregates, or salt alone, or sand or aggregate. Thickeners are mainly cellulose derivatives or high molecular weight carbohydrates. Typical molecular weights for cellulose derivatives are for methyl and hydroxy propyl methyl celluloses from about 60,000 to 120,000 and for hydroxy ethyl celluloses from about 10 750,000 to 1,000,000. Carbohydrate molecular weights range from about 10,000 to 50,000.
These components are used in an aqueous solution in the following concentrations:
Weight %
Carbohydrate
3 to 60
Inorganic Freezing
5 to 35
Point Depressant
Thickener
0.15 to 10
In a further embodiment of the present invention, amino acids and/or oligopeptides may replace or be used with the carbohydrate component to provide for alternative deicing formulations.
The above described compositions provide a de-icing and anti-icing formulation which can be formulated more uniformly to provide for more consistent properties from batch to batch, while at the same time providing for increased ice melting properties.
DETAILED DESCRIPTION OF THE INVENTION
In the development of the present invention it was determined that the predominant organic constituents in the prior art formulations described above were carbohydrates, and in one series of tests, Brewers Condensed Solubles (BCS), which was selected as a test sample, was diluted with water and separated into several fractions by the addition of increasing amounts of an ethanol/methanol 85/15 v/v mix. The characteristic of the various fractions and their freezing points when mixed with 15% magnesium chloride are tabulated below.
TABLE 1
% ethanol/
Freezing
methanol
% Carbo-
Point
Sample
added
% Solids
hydrates
° F.
° C.
Brewers (BCS)
NIL
43.6

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