CA1340377C - Aircraft de-icing and anti-icing compositions - Google Patents

Abstract

A thickened anti-icer fluid contains a release component providing a Water Content Angle Quality of at least 80° to facilitate removal of the fluid from aircraft surfaces, especially wing surfaces.

Description

AIRCRAFT DE-ICING AND ANTI-ICING CO~O~

Field of the Invention This invention relates to water/glycol compositions which have both de-icing and anti-icing properties when applied to surfaces. More particularly, it relates to compositions which can be applied to aircraft surfaces to remove ice and/or snow from the surfaces and remain on the surfaces to provide protection from ice and/or snow build-up, yet be readily removed from the surfaces by the forces generated during take-off of the aircraft.
8ackqround of the Invention Aircraft are subject to the buildup of ice, frost and/or snow on their surfaces while the aircraft are on the qround during cold weather in the presence of relatively high humidity, rain and/or snow. Because the buildup of ice, frost and/or snow on the aircraft surfaces can adversely affect the functioning of the aircraft, such buildups should be removed from the airplane prior to takeoff.
De-icing solutiong, such as those based upon ethylene glycol and water, have been used for many years to remove ice, frost and/or snow from the ~ - 2 - 1340377 aircraft surfaces. These de-icing compositions can effectively remove the buildup of ice, frost and/or snow from the surfaces but since they have low viscosities, they readily flow off the aircraft surfaces and thus provide limited protection from the formation of further frost and ice or accumulation of snow on the surfaces.
Anti-icing fluids are those that will prevent the formation of frost and ice or the accumulation of snow on surfaces over extended periods of time. The use of anti-icing fluids would be particularly desirable for overnight frost protection and for use during bad weather operation to accommodate substantial delays between the time the aircraft is deiced and takeoff.
One approach to formulating anti-icing fluids is to add thickening agents to de-icing fluids. The thickening agents are intended to increase the viscosity of the fluid and thereby reduce its tendency to run off the surfaces of the aircraft. A number of thickened fluids are commercially available in the world. These include Kilfrost Anti-icing Barrier Compound, Hoechst A.G.
Aircraft De-icing Fluid 1704, and SPCA Aircraft De-icer 84. Union Carbide Corporation introduced UCON (TM) Anti-icing Fluid E, an ethylene glycol based fluid containing polyacrylate, in 1968. In 1969, Union Carbide Europe developed a propylene glycol-based product, Aircraft De-icing fluid 251, which was a non-Newtonian fluid containing a crosslinked polyacrylic acid as a thickener.
An anti-icing fluid must meet a number of criteria. One of the most important criteria is _ 3 _ 1 34 03 77 that the anti-icing fluid be readily r~...oved from the surfaces of the aircraft during its takeoff.
This ability to be released from the aircraft surfaces must exist even if no precipitation occurs after the application of the anti-icing fluid and some of the fluid evaporates. Moreover, the fluid should have special rheological properties in that it must have sufficient viscosity to be retained on the aircraft surface yet require little force for it to be removed from the surface. Another important consideration in providing an anti-icing fluid is that the fluid should be capable of being applied using conventional spraying devices. Since these spraying devices can subject the thickened fluid to stress, the fluid must not be subject to undue shear instability and loss of thickening properties due to the application procedures. Loss of rheological properties are often experienced during the spray application of anti-icing fluids using a cross-linked polyacrylate thickener. Another concern when using thickened fluids for anti-icing agents, is the stability of the fluid during storage. For example, if an anti-icing fluid tends to gel during storage, the fluid, when applied, may be too viscous for effective removal from the aircraft or, if the gelling results in phase separation, the fluid may lose viscosity and thus not provide the desired anti-icing properties.
In addition to the foregoing requirements, a good anti-icing agent should also induce no appreciable erosive or corrosive activity, particularly towards aluminum, non-ferrous metals, _ J _ 1340377 steel, glas~ ~nd a~ryli~ sheeting. The anti-icing fluid should also be an effective de-icer resulting in rapid and complete thawing of ice, snow and frost and it sho~l~ provide a coherent liquid film after application to the aircraft surfa~es, i.e;, it should wet the surfaces wi~h which it comes in contact. Most advantageously, anti-icing fluids should be environmentally acceptable, provide minimum to~icity to plants and animals, and provide little ris~ ~f fl~mma~ility.
Recent tests using commercially available anti-icing fluids on a simulated segment of an aircraft wing indicate that the anti-icing fluids can result in appreciabl~ lift 108s as compared to de-icing (unthickened) fluids. Accordingly, substantial room for improve...~uL in anti-icing fluids for aircrafts exists.
~ .S. Patent No. 2,373,727, West, et al., discloses compositions to prevent or reduce the formation and/or accretion of ice on aircraft surfaces. The compositions comprise a jelly base consisting of gelatinous material and glycol or glycerol or homologs thereof or polyglycols or polyglycerols, e.q., di~thylene glycol or triethylene glycol, and from S to 20 percent by weight of a liquid which i~ iD iscible with ice or water and remains liguid at temperatures down to 10~F. The immiscible liquids sre disclosed to be mineral, vegetable and animal oils including essential oil~ ~u~h as petroleum ,?ubricating oils, castor oil~ and pine oil~, synthetic oils, the water immiscible ~lcohols and 6imilsr liquids. West, - 5- 1340~.77 et al., state that it is necessary to add a dispersing agent such as alkali metal or organic based soaps or fatty acids or oleic acid, napthanates, sulfonic acid salts, commercial soaps or monohydric alcohols. The jelly base may be prepared from any suitable material such as gelatin, glue, soap or gum which forms a heat reversible, jelly-like mass with the glycol or glycerol.
U.S. Patent No. 4,358,389, Koenig-Lummer, et al., disclose anti-icing compositions that contain 0.05 to l.S percent by weight of a particular crosslinked polyacrylate, glycol, water, 0.05 to 1 percent by weight of a water-insoluble component comprising a mixed base mineral oil comprising paraffin hydrocarbons and naphthenes, 0.05 to 1 percent by weight of a surface active agent comprising alkali metal alkylaryl sulfonate, corrosion inhibitor and a quantity of at least one alkaline compound selected from the group consisting of alkali metal carbonates, bicarbonates or hydroxides and amines, such that the pH of the composition is between about 7.5 and 10.
Koenig-Lummer, et al., disclose at column 5, line 54, et ~g , "In addition to the components..., the agent ... can also contain appropriate additives, preferably anti-oxidants and polysaccharides (gums) in effective quantities (gums are additional thickeners). ...It has been found that polysaccharides have an advantageous effect on the rheological properties of _ - 6 - 1340~77 crosslinked polyacrylates, particularly those having viscosity values in the lower range of the viscosity limits indicated above, that is within the range from about 1000 to 5000 mPas. Preferred polysaccharides are those of the type of high molecular xanthan gum."
r Koenig-Lummer, et al., disclose suitable corrosion inhibitors to include those belonging to the group comprising inorganic metal salts, alkali metal salts of fatty acids, monoalkyl amines and dialkyl amines optionally alkoxylated--and salts thereof, alkanol amines--optionally alkoxylated and salts thereof, esters of phosphorous acid or of phosphoric acid, and triazoles.
German Patent application 3,143,059, published May 5, 1983, discloses an anti-icing composition using a cellulose derivative thickener to provide a solution having a viscosity of 100 to 5000 mPa. ~ec at 20~C. The composition contains surfactant which is an alkali alkaryl sulfonate or oxyalkylated fatty alcohol, corrosion inhibitor and alkali carbonate, alkali hydroxide or amine to give a pH of 7.5 to 10. The application states that the composition may contain other thickeners, particularly polyacrylate or xanthan gum.
An anonymous disclosure in Research Disclosure, April, 1985, No. 25246, entitled "Aircraft De-icer", describes aircraft anti-icer concentrate to which water and/or glycol can be added. The anti-icer concentrate comprises water and an antifreeze as the two main components; up to S percent by weight of a thickener from the group comprising cellulosic derivatives such as alkyl, hydroxy alkyl and carboxy alkyl, ethers or mixed ethers of cellulose, crosslinked or non-crosslinked polyacrylates, xanthan gum, starch or starch derivatives and guar, it being possible for all except for the polyacrylates also to act as co-thicXeners; an active amount of a tenside, optionally in combination with a water-insoluble compound, the tenside being selected from the group comprising polyalkylene glycols, polyalkyl oxalates of alcohols, carboxylic acids, amines or amides, olefin sulfonates, fatty alcohol sulfates and alkyl benzene sulfonates, and the water-insoluble compound being selected from the group comprising fatty alcohols, fatty acid esters, fatty acid alkanolamides, mineral oils, alkyl phenols and alkyl benzenes; customary corrosion inhibitors, such as, for example, carbonates, phosphates, silicates, amines, ethanolamines and benzotriazoles; and sufficient alkali that the pH value of the agent is within the desired alkaline range.
Summary of the lnvention By this invention de-icing and anti-icing fluids are provided which have enhanced release properties from treated surfaces, e.g., aluminum surfaces such as on aircraft. In accordance with the invention, the fluids exhibit a Water Contact Angle Quality (hereinafter defined) of at least about 80~, preferably 82~ to 120~; whereby the removal of the fluid during take-off is enhanced.

The compositions comprise glycol ~e.g., about 5 to 85 weight percent of the total composition) and water (e.g., about 5 to 95 weight percent of the total composition), at least one polymeric, water-miscible viscosity thickening agent in an amount sufficient to increase the viscosity of the composition, and at least one release component in homogeneous admixture in said composition, having a hydrophobic property and being preferentially associated with aluminum surfaces as compared to the viscosity thickening agent, wherein said composition exhibits a Water Contact Angle Quality of at least about 80~.
Water Contact Anqle Ouality For the purposes herein, the relative effect of compositions on aluminum surfaces is reported in terms of the Water Contact Angle Quality. The Water Contact Angle Quality is determined by contacting an untreated sheet of aluminum exhibiting a water contact angle (at room temperature, about 25~C) of between about 5~ and 90~
with the anti-icer composition for approximately 3 hours at room temperature (about 25~C), washing the composition from the aluminum using a gentle stream of distilled water (such as from a sgueeze bottle), and then determining the water contact angle at room temperature (about 25~C), which is hereby reported as the Water Contact Angle Quality. The absolute value of the water Contact Angle Quality indicates the degree of hydrophobicity of the surface and the relative change between the water contact angle of the fresh aluminum and the Water Contact Angle Quality implies performance characteristics. An increase suggests that the anti-icer composition is one in which release i8 facilitated and a decrease suggests that the anti-icer composition may be more resistant to removal from the aluminum surface. The water contact angle of a fresh aluminum sheet will depend upon the history of the aluminum sheet, e.g., its relative cleanness and the type of material that it may have been previously subjected. For the sake of consistency in determining the Water Contact Angle Quality, the aluminum curface is preferably cleaned prior to determining the water contact angles. When the aluminum surface is precleaned, the water contact angle of the cleaned aluminum surface is frequently in the range of about 5~ to 35~. The cleaning may be done with a chromic acid or chromic-sulfuric acid fiolution. The cleaning may be effected by immersion in the acid solution from about 1 to 5 minutes, often 2 minutes. The aluminum is thereafter liberally rinsed with deionized water and dried. Measurements of water contact angles are promptly conducted to minimize the time during which the aluminum surface can become dry. The use of deionized water tends to provide lower contact angles on well cleaned-aluminum surfaces than does tap water. Often the droplet size to determine the water contact angle is about 0.02 to 0.001, say, 0.002, milliliters. Desirably, more than one droplet is used in the measurement. Often, the water contact angles of 3 to 5 droplets are measured and averaged.
The Water Contact Angle Quality and the direction of change in water contact angle before 134037~
and after contact, of course, cannot be the only factor~ in formulating an advantageous thickened anti-icer composition. The composition must still provide desirable rheological properties to serve as an anti-icer The composition should also exhibit desirable hold-over time and must be capable of being applied to the surface in a convenient and reliable manner. It should also have suitable storage stability and induce no appreciable erosive or corrosive activity, particularly toward aluminum, non-ferrous metals, steel, glass and acrylic sheeting.
Discussion of the Invention As discussed above, an essential characteristic of an anti-icing fluid for aircraft is its property to be removed from the aircraft surfaces such as wing surfaces, during take-off.
Much attention has been directed to the rheological properties, especially yield value, of the thickened fluids. Yield value is the minimum amount of force required to initiate a flow of a fluid from its rest state. Rheological properties alone have not been found to be predictive of the ease of removal of a fluid from an aircraft surface. We have found that an interaction between the fluid and the surface can occur which can materially affect the removal of the thickened anti-icing fluid from the surface. Hence, even though the fluid itself may have a low yield value, the forces between the surface and the fluid may affect the ease at which the ~luid ~heds from a surface. Moreover, these forces can lead to a residual film on the surface. For instance, some ., , 1~40377 commercially-available, polyacrylate-containing anti-icing fluids have been found to leave visibly observable, residual films on aluminum surfaces.
While not wishing to be bound by theory the following discussion is provided. Many material~ of construction of the exterior surfaces of aircraft are hygroscopic in nature. For instance, paints such as polyurethanes have polar groups that are hydrophyllic. Aluminum surfaces are oxidized into aluminum oxide which is hydrophyllic. For instance, aluminum surfaces, if very clean, are hygroscopic, ...
that is, water tends to become bound or associated with the surface as evidenced by a low water contact angle. The precise mechanism of this binding or association is not known to us, but it is believed to involve attraction of the polar water molecular to the oxidized surface of the aluminum. Other materials, including many polymers used as thickening agents, contain polar groups such as carboxylic, alcoholic, ~ulfonic, amino and amido groups, that exhibit attraction, e.g., by Van der Waal's forces, polar forces, ionic forces, electrostatic forces, and the li~e. These attractive forces can potentially interact with the surfaces, directly or through water molecules, to provide resistance to release of the composition from the surfaces.
While very clean aluminum ~urfaces may be hygroscopic, it is readily apparent that aircraft surfaces are not typically found ,in pristine condition. Normally, the surfaces, especially of the wings, are dirty and may have films of oil, jet - 12 - 1 3 ~ 0 3 7 7 fuel, and the like thereon. Anti-icing compositions may contain components, such as surfactants and emulsifiers and even the thickening agent itself, that actually tend to clean the surface and reveal the hygroscopic properties of the surface or they may deposit a layer on the surface that is hygroscopic. For example, a commercial anti-icer fluid containing polyacrylate thickener has been found to provide a more hygroscopic surface than that existing on fresh commercially-available aluminum sheet metal.
In accordance with this invention, at least one release component is incorporated into an anti-icer composition containing a viscosity thickening polymer to provide a relatively non-hygroscopic surface and enhance the release of the thickened fluid from the surface. Preferably, the residual film rendering the surface non-hygroscopic is thin, e.g., less than 1 micron in thickness. The film should be less associative with the viscosity thickening agent than is water.
Thus, the viscosity thickening agent will preferentially bind with water as opposed to the film on the surface.
The specific release component or combination of release components to provide the sought Water Contact Angle Quality can vary depending upon the nature of the remaining components of the anti-ice composition. Indeed, a release component that may be desirable in one formulation may be unacceptable o~ less effective in another due to, e.g., the effects of other materials .. , . . . .. _ - 13 - 13 403~ ~

in the formulation on the surface or on the release component. For instance, carrageenan, a viscosity thickening agent, tends to be attracted to the aluminum surface. Release components that normally provide a high Water Contact Angle Quality, e.g., in polyacrylate- or xanthan gum-containing compositions, are, in the presence of carrageenan, generally less effective at the same concentrations.
The release component comprises substantially water-insoluble, partially polar compound. The release components may be salts or polar esters of carboxylic acids, sulfonic acids and/or phosphonic acids having hydrocarbyl substituents of at least 6, often 10 to 40, e.g., 10 to 18, carbon atoms. The salts may be inorganic, such as alkali metal, especially potassium and sodium, or ammonium, phosphonium, sulfonium, amine or phosphine. Exemplary of such salts include quaternary ammonium, tertiary amine (especially triethanolamine), secondary amine, primary amine, phosphonium, tertiary phosphine, secondary phosphine, and primary phosphine. Often these organic cations have hydrocarbyl-containing substituents, e.g., of one to about 10 carbon atoms which may further contain hydroxyl or ether groups.
Polar esters include hydroxyalkyls and alkyl ethers, e.g., of 1 to 10 carbons, as the ester group.
Illustrative of the release components are salts of carboxylic acids having 10 to 18 carbons, such salts being of sodium, potassium, triethanolamine, diethanolamine, monoethanolamine and the like, and polyacrylates having hydrocarbyl substituents, e.g., .

- l~ - 134~377 of from about 6 to 40 carbon atoms. The reléase component often comprises about 0.1 to 10, e.g., about 0.1 to 2.5, say, about 0.1 to 1.0, percent by weight based on the total composition.
The compositions of the present invention are characterized by a continuous phase comprising water and glycols. This combination can vary from a water concentration of from 25% to 95% by weight based on the total weight of the composition. The preferred water concentration range for the de-icer and anti-icer compositions usually is from about 40%
to 50% by weight of the total composition.
The glycols useful in the compositions of this invention include those heretofore suggested for de-icing, representative of which are ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol (1,2-propanediol and 1,3-propanediol), dipropylene glycol, glycerol and mixtures thereof. See, for instance, U.S. Patents Nos. 2,373,~27; 3,940,389 and 4,358,389.
The water-dispersible thickening agents useful in the present invention to improve the anti-icinq characteristics of the composition include polyacrylates, polyacrylamides, starches, modified starches and starch derivatives, as well as natural and artificial gums, cellulose ether, carboxymethylcellulose, hydroxyethylcellulose, methylcellulose and their derivatives, ethylene oxide/propylene oxide copolymers, polyvinyl alcohol and their related products. The water-dispersible thickening agent is often water-soluble. The amount of such thickening agent can vary from 0.05% to 10.0% by weight based on the total weight of the composition. The preferred range is from 0.05% to 5%
by weight based on the total weight of the composition.
The de-icing and anti-icing composition of this invention should have a pH of between 7 and 10 with a preferred range between 7 or 7.5 and 9. The desired pH can be obtained using inorganic base such as sodium hydroxide and potassium hydroxide and amines such as triethanol amine, diethanol amine or monoethanol amine. Buffers can be included in the composition to provide this pH range. De-foamers may also be employed in the composition. Any commercially available defoamer or anti-foamer can be used, but a particularly preferred defoamers are a silicone defoamer of Union Carbide Corporation sold under the trade mark SAG and FORMBANTM defoamer available from ~ltra Additives Inc., Patterson, NJ. The amount of this defoamer to be used is preferably in the range of from 0.05% to 0.5% by weight based on the weight of the total composition.
The composition can optionally contain at least one non-polar oil such as aliphatic and aromatic oils such as mineral oil, paraffin oil, silicon oil, and propylene oxide/ethylene oxide copolymers. The oil may be in an amount up to about 5% by weight based on the total composition and when present they are often in amounts of at least about 0.01% by weight of the total composition. The amount of such oil is frequently in the range of from 0.01% to 5.0% by weight based on the total weight of the composition. The preferred range is between 0.1% to 1.0% by weight based on the total weight of the composition.

- 16 - 13 4 ~ ~ 7 7 The effectiveness of the release component is generally enhanced when the composition is homogeneous. By the term homogeneous, it i6 meant that the relatively insoluble release compo~ent, which may form a discontinuous phase, is uniformly dispersed throughout the composition in at least an emulsion, preferably a microemulsion. Often, the average particle size of any discontinuous phase is below about 1 micron, preferably below about 0.1 micron. Microemulsions are characterized by having the insoluble phase dispersed in micro-droplets in the aqueous solution. These droplets are smaller than the wavelength of visible light and consequently the microemulsion appears transparent.
Procedures for preparing microemulsions are fully described in the textbook "Microemulsion Theory and Practice", Leon M. Prince, Editor (Academic Press, Inc. 1977).
In order to maintain the release component in a homogeneous admixture in the composition, emulsifiers are frequently employed. The amount and nature of the emulsifier should be such that the release component can form a very thin film on the surface to provide the desired Water Contact Angle Quality. Because of the hydrophobic and hydrophillic properties of the release components, the release components themselves can provide some emulsifying activity. The emulsifier~ used in the present composition can include any of a wide range of anionic surfactants such as or,gano-phosphates, phosphonates, sulfates and sulfonates, as well as fatty acid salt~ and non-ionic surfactants 6uch as . - 17 - 1340377 alcohols, phenols, amines, fatty acids and their alkoxylated derivatives, and the like. The above anionic and non-ionic surfactants can be used singly or preferably in a combination of at least two surfactants to facilitate emulsification. The amount of emulsifier to produce the desired emulsion i~
between 0.1 times to about 100 times the concentration by weight of the total release component and oil present in the composition. The preferred range is from about 2 times to 20 times the concentration by weight of the total release component and oil. Most desirably, the emulsifier comprises the combination of non-ionic surfactants with alkanolamine. The alkanolamine may be primary, but preferably is secondary or tertiary and each substituent may contain from 1 to about ~ carbons, preferably, 2 or 3 carbons. The alkanolamine is often present in an amount of about 0.1 to 5, say, 0.5 to 2, weight percent of the total composition.
The anti-icing property of the invention can be measured by the use of the following procedure. A mixture of ethylene glycol and water at a ratio of 88:12 will be used as a reference material because of its known anti-icing property.
Under the set condition of -8~C and at a precipitation rate of 1.08 mm/hr, the reference material was measured to have 15 minutes of anti-icing time.
As an illustration, both the reference material and a composition of the above invention were applied to the surfaces of two separate aluminum panels (approximately 2 feet by 5 feet in -- 18 - 134037~
size and positioned at an 8~ angle to horizontal) cooled to -20~C. A mist of freezing water was then sprayed onto the surfaces until frost occurred in both cases. The times elapsed were recorded. The panel treated with reference material is completely frosted within about 15 minutes.
While, the anti-icing time of any composition varied as a function of the temperature and precipitation rates, it was estimated that a de-icing, anti-icing fluid of a yield value of a dyne/cm2 in some instances gives approximately 2 hours of anti-icing protection under the temperature and precipitation conditions as mentioned above. The yield value is defined as the minimum amount of force required to initiate the flow of a fluid from its rest state. In general practice, it can be approximated by the use of Brookfield LVT viscosities.
The following example of de-icing and anti-icing compositions of the present invention are set forth for purposes of illustrations, but are in no way intended to limit the scope of the invention.

Example 1 A microemulsion composition of the invention can be prepared by mixing ethylene glycol, water and mineral oil vigorously at up to 70~C
together with the other components to form the de-icer and anti-icing composition. The microemulsion was allowed to cool slowly to room temperature (25~C).
The resulting product had a clear bright appearance and contained the following components in - lg- 13~377 percentages by weight based on the total weight of the composition:
(a) B4.0% ethylene glycol (b) 2.0% dipotassium hydrogen phosphate (c) 0.1% xanthan gum .
(d) 6.9% water (e~ 1.0% white mineral oil 10 cst (f) 1.5% carboxylic acid having from 10 -18 carbon atoms (q) 1.5% triethanolamine (h) 3.0% of a mixture of non-ionic surfactants of HLB 5-14 Example 2 A microemulsion was prepared to demonstrate the synergistics of the following components, the percentages given are percents by weight based on the total weight of the composition:
(a) 40.0% ethylene glycol (b) 14.0% diethylene glycol (c) 41.7% water (d) 2.0% dipotassium hydrogen phosphate (e) 0.1% xanthan gum (f) 0.25% mineral oil (g) 1.0% carboxylic acid having from 10 -18 carbon atoms (h) 0.7% triethanolamine (i) 0.2S% of a mixture of non-ionic surfactants of HLB 5-14 The yield value of the de-icing and anti-icing agent at -5~C in the absence of components (f) through (j) was found to be 0.14 dyne/cm2 while a composition containing all of the ..
above components gives a yield value of 1.0 dyne/cm2 under the same temperature conditions.
This corresponds to a significant improvement in rheological properties due to the synergistic activity between the xanthan gum and the microemulsion.
Example 3 A de-icing and anti-icing composition containing silicone oil was proposed by mixing the following components in a microemulsion. Again, the amounts are in percent by weight based on the total weight of the composition:
(a) 40.0% ethylene glycol (b) 14.0% diethylene glycol (c) 41.4% water (d) 0.1% xanthan gum .
(e) 0.2% tolyltriazole (f) 1.0% carboxylic acid having from 10 to 18 carbon atoms (g) 1.0% triethanolamine (h) 1.0% of a mixture of non-ionic surfactants of HLB S-14 (i) 0.3% potassium hydroxide (j) 1.0% dimethyl polysiloxane (10 - 20 cst) This composition had substantially the same yield value as in Example 2.
Example 4 A de-icing and anti-icing composition ~imilar to the ~ample prepared in Example 3 can be obtained by replacing the dimethyl polysiloxane with ,.

0.25% by weight of propylene oxide based synthetic oil of 300 SUS viscosity to give the same magnitude of synergistic thickening activity as in Example 2.
Example 5 ..
Another composition containing anionic surfactants was prepared by mixing the following components in a microemulsion:
(a) 36.0% ethylene glycol (b) 18.0% diethylene glycol (c) 42.27$ water (d) 0.3% potassium hydroxide (e) 0.2% tolyltriazole (f) 0.13% xanthan gum (g) 1.0% carboxylic acid having from 10 to 18 carbon atoms (h) 1.0% triethanola~ine (i) 0.5% sodium arylalkylsulfonate (j) 0.5% phosphorester 600 anionic surfactant (k) 0.1% mineral oil The yield value calculated based on the Brookfield viscosities at -5~C is 1.26 dyne/cm2.
Example 6 A de-icer and anti-icing composition having a relatively high yield value of 17.0 dyne/cm2 can be prepared by use of the following components in percent by weight based on the total weight of the composition to demonstrate the increase in shear stability of the microemulsified~fluid:
(a) 36.0% ethylene glycol (b) 18.0% diethylene glycol 134~377 (c) 41.95% water (d) 0.3% potassium hydroxide (e) 0.2% tolyltriazole (f) 0.3% xanthan gum (g) 1.0% carboxylic acid having 10 - 18 . carbon atoms (h) 1.0% triethanolamine (i) 1.0% of a mixture of non-ionic surfactants of HLB 5-14 (j) 0.25% mineral oil When sheared by the use of a Brookfield counter-rotating mixer for 5 minutes at 3500 rpm, the yield value reduced to 14.4 dyne/cm2 while the composition without microemulsion gives a yield value of only 12 dyne/cm2 Example 7 A similar composition can also be prepared by microemulsifying the following components in percent by weight based on the total weight of the composition to demonstrate the synergistic thickening activity using a water soluble polymer other than xanthan gum:
(a) ~0.0% ethylene glycol (b) 1~.0% diethylene glycol (c) 41.65% water (d) 0.3% potassium hydroxide (e) 0.2% benzotriazole (f) 0.5% carboxy methyl cellulose (g) 1.0% carboxylic acid having 10 - 18 carbon atoms '~
(h) 1.0% triethanolamine - 23 - 13~ 03 77 (i) 1~0% of a mixture of non-ionic -surfactants of HLB 5-14 (j) 0.35% mineral oil The yield value of the composition in the absence of components (g) through (j) at -18~C i6 zero. While incorporating components (g) to (~) gives a value of 0.~0 dyne/cm2. The use of the microemulsion with the mineral oil, carboxylic acid and other components has in fact rendered a desired rheological property to the polymer in the water/glycol solution.
The following table sets forth additional compositions of this invention that have desirable de-icing and anti-icing properties and advantageous rheological properties with shear stability and storage stability.

- 13403~7 TABLE I

(all percentages are by weight based on the total eomposition) Compos~t~on Compos~t~on Compos~tlon Compound A ~ B ~ C
Monoethylene glycol 36 37 D~ethylene glycol 18 18 Tr~ethylene glycol - - 55 ~ater 42.3 41.9 41.87 Xanthan Gum 0.13 0.1 0.1 Ammonium polyacrylate 0.5 Isostear~c Ac~d 1.0 1.0 1 0 Tr~ethanol Am~ne 1.0 1.0 1.0 Non-~on~c surfactants, HLB 5-14 1.0 1.0 1.0 Potass~um hydrox~de (50~) 0.06 0.04 0.04 Table II sets forth the effeet of various release eomponents in various anti-ieing fluid formulations. All pereentages are by weight unless otherwise noted. The aluminum surfaees are not cleaned prior to determining the Water Contaet Angle Quality.
It should be noted that variability in water eontaet angles ean be observed from droplette to droplette on a given aluminum surfaee. The precise reason for such variations is not known but may be due to one or more of many potential reasons. Henee more than one droplette should be observed on a given surfaee. Note that item 33 in Table II reports for fluid C a Water Contact Angle - 25 - 13 4 ~ ~ 77 Quality of 72~. Yet the same fluid in the experiment reported in ~able III has a Water Contact Angle Quality of ~7-, ~hicb is consistent with other observed measurements and performance of the fluid The reason for the low value in Table III is not known.

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FLUID POLYMER ADDITIVE ANGLE WATER FILM
BEFORE, ~ CONTACT
ANGLE
QUALITY, 30Hoechst LTV Acrylic Acid 1% TEA 69 73 Very Light 31Hoechst LTV Acrylic Acid ME 73 94 No 32 Be 71 96 No 33 cm 50 72 ~ - 1340.377 Notes:
a Fluid A comprises 54 wt.% ethylene glycol/diethylene glycol in a 36:18 weight ratio, 0.5 wt.% SandocorinTM 8132B
available from 8andoz Chemical Corp., Charlotte, North Carolina, 0.5 wt.%
Polyresin 5545 available from Polyresin Corporation, Ardsley, N.Y., Toronto, Ont., 0.05 wt.% potassium hydroxide (pH 8-9), balance water.
b Polyresin is Polyresin 5545 contained in Fluid A.
c TEA is triethanol amine.
d Isostearic and ISO refer to isostearic acid.
e ICS-l is AcrysolTM IC8-1 thickener, an alkali-soluble acrylic polymer available from the Rohm and Haas Company, Philadelphia, PA.
f ME is an additive which in the final composition provides:
1 wt.% isostearic acid 1 wt.% triethànol amine 1 wt.% non-ionic surfactants, HLB 5-14 g GE202 is DapralTM GE202 partial ester of a branched carboxylic acid copolymer with average molecular weight of 20,000 having a comb-like structure avaiiable from Akzo Chemie America, Chicago, IL. Both ICS-l and GE202 are present in the final composition in amounts of 1 wt.% each.

- 1340~?~77 h Surfactants is non-ionic surfactants, HLB 5-14 676 is CarbopolTM 676 acrylic acid polymer cross-linked with an allyl ether of pentaerythritol or sucrose available from the B.F. Goodrich Company, Cleveland, OH.
SAAS is sodium arylalkylsulfonate.

k Carrageenan is GelcarinTM GP379 carrageenan, a calcium iota carrageenan available from FMC Corporation's Marine Colloids Division (Philadelphia, PA) described in U.S. Patent No. 4,698,172.
Fluid B is Composition A in Table I.

m Fluid C is Composition C in Table I. The xanthan gum is K-lA-96 modified xanthan gum available from Gelco Co., San Diego, CA.

Using fluids reported in Table II, the Water Contact Angle Quality is determined using precleaned aluminum surfaces. The cleaning is effected by immersing the aluminum surface into a chromic acid-cont~ining bath (Chromosulfuric Acid cleaning solution available under catalogue number SO-C-88B from Fisher Scientific Co., Pittsburgh, Pennsylvania). The data are prescribed in Table III.
All parts and percentages are by weight unless otherwise noted. The abbreviations in Table III are the same as in Table II.

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Claims (9)

1. A de-icer and anti-icer two-phase composition comprising from about 5% to 85% by weight based on the weight of the total composition of glycol selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, glycerol and mixtures thereof; from about 5% to 95% by weight of water based on the weight of the total composition; a pH adjusting agent sufficient to provide a pH of 7 to 10 and at least one polymeric, water-dispersible viscosity thickening agent in an amount sufficient to increase the viscosity of the composition, an emulsifier selected from anionic or non-ionic surfactants, said composition further comprising at least one water-insoluble oil selected from aliphatic oils, aromatic oils, paraffin oils, silicone oils, and propylene oxide/ethylene oxide copolymers, in homogeneous admixture in said composition, having a hydrophobic property and being preferentially associated with aluminum surfaces as compared to the viscosity thickening agent, wherein and said composition exhibits a Water Contact Angle Quality of at least about 80°.

2. A composition of claimed in claim 1 wherein said release component comprises salt or polar ester of carboxylic acid having 10 to 18 carbon atoms.

3. A composition as claimed in claim 1 wherein the thickening agent comprises xanthum gum.

4. A composition as claimed in claim 1 wherein the emulsifier comprises non-ionic surfactant.

5. A composition as claimed in claim 4 wherein the non-ionic surfactant provides an HLB of 5 to 14.

6. A composition as claimed in claim 1 having a pH
of from 7 to 9.

7. A composition as claimed in claim 1 further comprising a defoamer.

8. A composition as claimed in claim 1 wherein said release component comprises salts or polar esters of at least one of carboxylic acid, sulfonic acid and phosphonic acid having hydrocarbyl substituent of at least 6 carbon atoms per group.

9. A composition in claim 8 wherein the release component comprises an amine salt.