Anti-icing fluid

Abstract

FIELD: invention relates to compositions of anti-icing liquids.SUBSTANCE: anti-icing fluid is an aqueous solution based on glycol and includes glycol made on the basis of diethylene glycol, glycerine, a thickener made in the form of an acrylic thickener, a corrosion inhibitor and a surfactant comprising polyethylene glycol monomethyl ether, wherein the corrosion inhibitor comprises alcohol, a monobasic acid having in its composition from 5 to 15 carbon atoms, and a dibasic acid having in its composition from 5 to 15 carbon atoms, sodium and potassium salts of higher carboxylic acids with the following content of components, wt.%: diethylene glycol 10-45, glycerine 10-65, corrosion inhibitor 1-5, surfactant 3-7, thickener 0.05-0.1, the rest is water up to 100.EFFECT: high viscosity, stable thermally stable properties, and high anti-corrosion properties.6 cl, 1 tbl, 1 ex

Description

[0001] The present invention relates to the field of aviation chemistry, specifically to anti-icing fluid (AIF) compositions intended for ground treatment of aircraft surfaces to remove ice deposits (frost, hoarfrost, snow, ice) and prevent surface icing, even under conditions of super-cooled rain, for at least 30 minutes. Specifically, the invention relates to Type 4 AIF compositions.

[0002] The formation of ice deposits during ground icing of aircraft most often occurs on the fuselage, empennage, and significant portions of the wings. This phenomenon causes an increase in aircraft weight, changes in the aerodynamic shape of its surfaces, an increase in drag, and a significant deterioration in aerodynamic performance. These factors can lead to serious aviation accidents, including fatalities.

[0003] To remove ice from aircraft surfaces during operation, de-icing fluid (DIF) is sprayed through special nozzles. The fluid is first diluted with water at a ratio of 75:25 or 50:50, depending on weather conditions, and heated to a temperature of 70–80°C. If icing is predicted, preventative treatment of the surfaces is carried out without diluting the DIF or heating it.

[0004] Conventional thickened anti-icing fluids typically use high-molecular-weight polymers as thickeners. Their ability to increase viscosity is based either on the formation of spatial networks through molecular interlacing or on gelation, achieved by regulating the pH of the environment. However, such formulations have several drawbacks: after application, they can leave gel-like residues on aircraft surfaces. The volume of these residues directly depends on the amount of polymer added, as it is the key component determining the viscosity-rheological properties of the fluid.

[0005] Furthermore, most of these thickeners provide a relatively stable viscosity over a temperature range of 20°C to -30°C. This can create problems in practical applications: if the specified high viscosity is designed for a temperature range of 0°C to -10°C—the most typical operating temperature—then even at room temperature (20°C), the fluid becomes excessively viscous, complicating its preparation and delivery. At lower temperatures (below -10°C), efficiency decreases, aircraft aerodynamic performance deteriorates, and gel deposits become more common.

[0006] Type 4 anti-icing fluids are designed to provide long-term protection of aircraft against ice formation. Commercial fluids in this group must meet the requirements of the international standard SAE AMS 1424 and ISO 11075, which regulate the characteristics of non-Newtonian (pseudoplastic) compounds used for aircraft de-icing and anti-icing (including types 2, 3, and 4).

[0007] Type 3 antifreeze formulations include polyhydric alcohols, which act as antifreeze additives—components that lower the freezing point of water. Additionally, the formulation may include various auxiliary substances that improve the fluid's performance properties: surfactants, emulsifiers, acidity regulators, corrosion inhibitors, and other functional additives.

[0008] The following compounds are preferably used as the main antifreeze component: monoethylene glycol (MEG), 1,2-propylene glycol (1,2-PG), 1,3-propylene glycol (1,3-PG), diethylene glycol (DEG), dipropylene glycol (DPG), or glycerin. Thanks to these components, anti-icing fluids provide a low freezing point - down to -60 °C according to GOST 18995.5-73 and down to -40 °C according to ASTM D1177-94.

[0009] A fire extinguisher for aircraft is known from the prior art (patent for invention No. 2100398, published on 27.12.1997)

[0010] The analogue is intended for use to remove and prevent icing of aircraft surfaces. The essence of the invention: the anti-icing fluid contains alkylene polyol, dibasic alkali metal phosphate, stearic acid, water and a surfactant - benzenesulfonate of methyl diethylaminomethyl derivatives of diethylene glycol ethers of fatty alcohols in the following ratio of components, in wt.%: alkylene polyol - 30-95; dibasic alkali metal phosphate - 0.5-1.5; benzenesulfonate of methyl diethylaminomethyl derivatives of diethylene glycol ethers of fatty alcohols - 0.5-5.0; stearic acid - 0.1-1.2; water - up to 100. The liquid has low viscosity at low temperatures, easy removal from the aircraft surface and an increased service life.

[0011] The analogue has a formula containing wt.%:

[0012] Alkylene polyol 30-95 Corrosion inhibitor 0,5-1,5 Water-insoluble additive 0,1-1,2 surfactants 0,5-1,0 Water Up to 100

[0013] The described anti-icing fluid (AIF) composition uses an alkali metal phosphate in dihydrogen form as a corrosion inhibitor. The surfactant is benzenesulfonate, a methyl diethylaminomethyl derivative of diethylene glycol fatty alcohol ethers. Stearic acid is included as a water-insoluble additive to ensure the required water-repellent properties.

[0014] According to the international standard ISO 11078, anti-icing fluids must meet a number of key performance characteristics. Specifically, a concentrated anti-icing fluid must maintain its physicochemical and performance parameters after aging at 70°C for 30 days. A diluted solution (50:50 by volume with water) must remain stable for a similar shelf life at 95°C. Furthermore, the fluid must demonstrate high performance in supercooled precipitation conditions for at least 30 minutes after vigorous stirring at 3500 rpm for 5 minutes.

[0015] However, the known formulation does not meet these requirements. When heated, especially to 95°C, the surfactant is released from the formulation. A significant decrease in viscosity is also observed—from 50–100 mm² / s to 14–25 mm² / s after vigorous stirring. This reduces the protection time from freezing rain to 5–15 minutes, which does not meet regulatory requirements.

[0016] An anti-icing fluid is known (USSR author's certificate No. 947169), containing 25-80 wt. isopropyl alcohol, 0.05-0.1 surfactants (non-ionic surfactants: monoalkyl ethers of polyethylene glycol based on primary fatty alcohols of formula C n H 2n+1 O(C2H4O) m H or polyethyleneglycol ethers of monoethanolamides of formula C n H 2n+1 CONHCH2CH2CH2O (C2H4O) m H or anionic surfactant salts of alkylaromatic sulfonic acids of formula C n H 2n+1C6H4SO3Na), 0.01-0.03% fragrance, 0.0005-0.0010% dye, and the remainder water. This fluid does not meet the requirements for deicing fluids for protecting aircraft from ground icing in terms of its deicing properties and its effect on paintwork, organic glass, and rubber. It causes softening and discoloration of standard acrylic and vinyl chloride paint systems used for aircraft exteriors. The fluid removes ice deposits and delays the icing process on horizontal surfaces for 1-2 minutes, which is insufficient for real-world aircraft operating conditions.

[0017] Glycerin-based compositions of type 4 POZH are widely found in patent literature.

[0018] The patent (Compositions for the prevention of the formation or accretion of ice on exposed surfaces: US Pat. 2373727 No. 19420435552; ​​filed March 20, 1942; published April 17, 1945, IPC C09K 3 / 18), entitled "Compositions for the prevention of the formation or accretion of ice on exposed surfaces", describes the composition of an anti-icing agent. Glycerin, various glycols, polyglycols, or mixtures thereof in an amount of 83 to 93 wt.% are used as the main component that lowers the freezing temperature.

[0019] To regulate viscosity, gelatin or natural rubber (7–17% by weight) are included. The composition also contains surfactants used as dispersing agents—low-molecular-weight aliphatic alcohols and sulfonic acid salts. Additionally, a third functional component—water-insoluble compounds such as mineral, vegetable, animal, or synthetic oils, as well as water-insoluble alcohols—is included in the composition in an amount of up to 5% by weight.

[0020] The patent [Anti-icing fluid for use in freezing rain: US Pat. 2948625. No. 19590829157; filed July 23, 1959; published August 9, 1960, IPC C11D 1 / 30, C11D 1 / 14, C11D 1 / 72, C11D 1 / 22, C11D 1 / 38, C11D 1 / 83, C11D 1 / 835, C11D 1 / 02, C11D 1 / 62] describes an anti-icing fluid containing a finely balanced water-in-oil emulsion. The dispersion medium is a fatty acid ester dissolved in mineral oil, and the dispersed phase is an aqueous solution of lithium chloride, used as an antifreeze component (75 wt.%). The composition also includes carboxymethyl cellulose (0.2 wt.%) as a thickener and a quaternary ammonium salt (1 wt.%), used as a corrosion inhibitor. The disadvantages of this composition include the limited duration of effective protective action.

[0021] A prior art analogue is known in the form of a Composition for removing and preventing icing of aircraft ("Aircraft de-icing and anti-icing composition" patent for invention No. 0257720 EP. No. 19870201618; filed on 08 / 27 / 1987; published on 12 / 04 / 1991, IPC C09K 3 / 18, C09K, B64F 5 / 00, B64D 15 / 00). The analogue describes the composition of an anti-icing fluid (AIF), which is a microemulsion of oil in a water-glycol solution. Its composition includes thickeners, water-insoluble emulsifiers and pH regulators, which include alkanolamines. Glycols that can be used include mono-, di-, or triethylene glycol (MEG, DEG, TEG), propylene glycol (PG), dipropylene glycol (DPG), or glycerol. Preferred thickeners in the present invention include xanthan gum, carboxymethyl cellulose, and hydroxyethyl cellulose, used in amounts ranging from 0.05 to 10% by weight.

[0022] An analogue is known from the prior art in the form of a Composition for combating icing and protecting aircraft from icing (patent for invention No. EP 0257720, published 1988-03-02).

[0023] The analog describes a composition that consists of a microemulsion of oil in a water-glycol solution containing certain thickeners, emulsifiers, carboxylic acids containing from 10 to 18 carbon atoms, and alkanolamines to provide the desired viscosity and shear stability necessary to obtain a composition with effective anti-icing properties.

[0024] The analogue contains a liquid lubricant of the following composition (wt.%):

[0025] Alkylene polyol 5-85

[0026] Water 5-95

[0027] Dibasic alkali metal phosphate 2.0

[0028] Alkanoamine 0.1-2.5

[0029] Surfactant (nonionic, anionic or a mixture of both) 0.25-3.0

[0030] Stearic acid 0.1-2.5

[0031] Cellulose ethers, carboxymethyl cellulose, etc. 0.05-10.0

[0032] Mineral oil 0.1-1.0.

[0033] The disadvantages of this analogue include its failure to meet established requirements for the duration of protective action under icing conditions, as well as its shelf life. The use of carboxymethyl cellulose as a thickener results in unsatisfactory viscosity, reduced ice protection effectiveness, and a violation of aerodynamic compatibility and aerodynamic suitability requirements.

[0034] In the analogue in the form of an Aviation anti-icing fluid containing carrageenan (“Aircraft anti-icing fluid containing carrageenan” patent for invention “4698172 US. No. 06 / 892,980; published 06.10.1987, IPC C09K 3 / 18, B64D 15 / 00, B64F 5 / 00) carrageenan (seaweed extract) is used as a thickener.

[0035] This analogue is a deicing fluid suitable for ground application on aircraft. It is a glycol solution containing gelling carrageenan in an amount less than 5% by weight. The carrageenan is present in the glycol solution in a quantity sufficient to thicken the fluid and improve its adhesion to aircraft surfaces when applied to a stationary aircraft. The use of this thickened deicing fluid does not adversely affect the lift characteristics of the wing profile during takeoff, as the fluid liquefies under shear and easily flows off the aircraft surfaces under the influence of wind shear during takeoff.

[0036] The described composition has satisfactory anti-icing properties, but its practical application is complicated by the uneven distribution of the extract and the high cost of the purification process.

[0037] An analogue in the form of a means for combating icing and protecting against icing is known from the prior art (“Agent for de-icing and protecting against icing-up” invention patent US4358389A; published 09.11.1982, IPC B64D 15 / 00, C09K 3 / 18).

[0038] The analogue offers a glycol-based anti-icing and protection fluid composition (MEG, PG, DEG). A liquid anti-icing and protection agent is described, which can, in particular, quickly and completely clean the metal surface of aircraft from ice, frost, snow and similar deposits, and also protect the surface from further deposit formation over a relatively long period of time. The agent essentially consists of several components, namely: (a) glycols, (b) water, (c) thickeners, (d) substances insoluble in water, (e) surfactants, (f) corrosion inhibitors and (g) alkaline compounds, in strictly defined quantities in each case, wherein the amount of components (a) and (b) is at least 94% of the total weight of the agent. The pH of the agent is from 7.5 to 10.

[0039] It is noted that the most preferred polysaccharide is high-molecular-weight xanthan gum. The viscosity of the proposed polysaccharide, measured using a Brookfield viscometer, is 50,000–60,000 mPa s at -25°C and 0.3 rpm.

[0040] De-icing and anti-icing agent for aircraft is known (patent for invention No. 4744913 US. No. 07 / 011,266; published 05 / 17 / 1988, IPC C09K 3 / 18).

[0041] The analogue is a glycol-based and water-based product containing cross-linked acrylic polymers as a thickener, as well as conventional corrosion inhibitors, surfactants belonging to the alkali metal alkyl aryl sulfonate group, and a neutralizing agent for adjusting the pH to a basic value, contains, as a thickener, two selected cross-linked acrylic polymers in a certain ratio by weight to each other, namely, a selected cross-linked homopolymer of acrylic acid or alkali metal acrylate and a selected cross-linked copolymer of acrylic acid / acrylamide or alkali metal acrylate / acrylamide in a weight ratio of from 2 to 10:1, and as a neutralizing agent, three alkaline compounds, each in a selected amount, namely, ammonia, monoethanolamine, diethanolamine and / or triethanolamine as the first alkaline compound,potassium hydroxide as the second alkali compound and another alkali metal hydroxide as the third alkali compound.,

[0042] The analogue uses a mixture of thickeners, which allows achieving the desired viscosity values ​​and the required rheological profile of the fluid even at very low temperatures and shear rates. Thus, a mixture of cross-linked homopolymers of acrylic acid and copolymers of acrylic acid with acrylamide is used as a thickener (0.1–1 wt.%). In addition, this analogue proposes using a mixture of three neutralizing agents: ammonia, monoethanolamine / diethanolamine / triethanolamine (0.03–1 wt.%), potassium hydroxide (0.1–0.7 wt.%), and another alkali metal hydroxide (0.02–0.5 wt.%).

[0043] An analogue in the form of a polymer-thickened deicing composition and anti-icing composition for aircraft is known from the prior art (“Polymer-thickened deicing composition and anti-icing composition for aircraft”, patent for invention No. 5,718,834 US. No. 08 / 730,968; published 02 / 17 / 1998, IPC C09K 3 / 18, C09K 5 / 20, C09K 5 / 00).

[0044] The described analog composition includes, as a thickener, water-soluble cross-linked acrylic homopolymers with an average molecular weight of 750,000 to 1,250,900 and a viscosity in the form of a 0.5% by weight aqueous solution with a pH of 7.0 and a temperature of 20°C from 1,000 to 13,000 mPa s, measured using a Brookfield viscometer at 20 rpm, as well as from 0.02 to 1.5% by weight of at least one non-ionic surfactant formed from an alcohol with 6-22 carbon atoms, which reacts with 1-10 molecules of low molecular weight alkylene oxide, and from 0.03 to 1% by weight of at least one water-soluble salt compound of an inorganic acid or carboxylic acid or a mixture thereof. The described anti-icing fluid is characterized by a long action time and good fluidity.

[0045] Water-soluble alkali metal salts of inorganic acids (boric, phosphoric, sulfuric, nitric or acetic), as well as imidazoles or triazoles (benzotriazole, tolyltriazole) in an amount of 0.01 - 1 wt. % are used as a corrosion inhibitor; oxyethylated higher fatty alcohol is used as a non-ionic surfactant (0.02 - 1.5 wt. %). The thickener of this POZH is water-soluble cross-linked polyacrylic or polymethacrylic acid with an average molecular weight of 750,000 - 1,250,000 or a mixture of them (0.05 - 1.5 wt. %). The viscosity of a 0.5% aqueous solution of the thickener, measured using a Brookfield viscometer at a temperature of 20 °C, pH = 7 and a shear rate of 5.6 s-1, is 1000 – 13000 mPa⋅s.

[0046] The specified anti-icing fluids (AIFs) do not meet the requirements for spraying through nozzles. This is due to the fact that when using a polymer with a molecular weight over 700,000 as a thickener, especially at temperatures of 20°C and below, a so-called "spinning" effect occurs. As the fluid is dispensed through the spray equipment, polymer threads are formed, which is unacceptable, as it leads to a loss of fluidity and uneven application.

[0047] An analogue in the form of an anti-icing liquid is known from the prior art (patent for invention RU 2100398, patent holder VIAM, Published: 12 / 27 / 1997).

[0048] The anti-icing fluid contains alkylene polyol, dibasic alkali metal phosphate, stearic acid, water and a surfactant - benzenesulfonate of methyl diethylaminomethyl derivatives of diethylene glycol ethers of fatty alcohols in the following ratio of components, in wt.%: alkylene polyol - 30-95; dibasic alkali metal phosphate - 0.5-1.5; benzenesulfonate of methyl diethylaminomethyl derivatives of diethylene glycol ethers of fatty alcohols - 0.5-5.0; stearic acid - 0.1-1.2; water - up to 100. The liquid has low viscosity at low temperatures, easy removal from the aircraft surface and an increased service life.

[0049] The analogue has the following composition of the POZH (wt.%):

[0050] Alkyl polyol 30-95

[0051] Dibasic alkali metal phosphate (disodium phosphate doubly aqueous GOST 41-72-76 or dipotassium phosphate trihydrate GOST 2493-75) 0.5-1.5

[0052] Cationic surfactants: benzenesulfonate methyl diethylaminomethyl derivatives of diethylene glycol ethers of fatty alcohols (alkamone OS-2 GOST 10106-75) 0.5-5.0

[0053] Stearic acid (GOST 6484-64) 0.1-1.2

[0054] Water (softened, with a hardness of 1.5 mg-eq. / l) up to 100.

[0055] The liquid has the following characteristics: a) high humidity test (HHET), not less than 4 hours;

[0056] b) Freezing rain test (WSET), not less than 30 min.

[0057] The proposed chemical composition of the anti-icing fluid allows for an increase in the anti-icing protection time (up to 12 hours), and will be highly effective when tested at high humidity (at least 8 hours) and in freezing rain conditions (at least 80 minutes).

[0058] Known compositions for combating icing (patent for invention No. US8562854B2, published 2013-10-22).

[0059] Non-toxic anti-icing fluid contains at least 20% by weight of a freeze-point depressant selected from short-chain polyols with 3 to 5 carbon atoms. The fluid also contains at least 10% by weight of water, a thickener, a surfactant, and a pH adjuster. The fluid meets the requirements of SAE / AMS 1428 or its revisions for Type II, III, or IV non-Newtonian aircraft anti-icing fluids.

[0060] An analogue in the form of an anti-icing pseudo-plastic liquid is known from the prior art (patent for invention 2230091 RU. No. 20030101703; published 10.06.2004, IPC C09K 3 / 18).

[0061] The analogue relates to the creation of an anti-icing fluid (AI) for removing ice deposits and preventing surface icing, used to protect aircraft or other types of equipment from icing while parked on the ground. The anti-icing fluid contains an alkylene polyol, a corrosion inhibitor, a non-ionic surfactant (surfactant), a water-insoluble additive, a thickener, an alkali metal and / or ammonium hydroxide, and water. Oleic acid is contained as a water-insoluble additive. The thickener is a copolymer of methyl methacrylate and methacrylic acid containing from 70 to 80% methacrylic acid, with an average molecular weight of from 500,000 to 700,000. The anti-icing fluid according to the invention is effective and retains the properties of the liquid after exposure to temperatures of 70 and 95 °C for 30 days.

[0062] The developed anti-icing fluid (AIF) includes the following components: an anti-freeze agent - individual compounds (monoethylene glycol, propylene glycol, diethylene glycol, glycerin) or their mixtures, a corrosion inhibitor, a non-ionic surfactant (surfactant), a water-insoluble additive, a thickener, an alkali metal or ammonium hydroxide, and water.

[0063] Oleic acid is used as a water-insoluble additive. The thickener is a copolymer of methyl methacrylate and methacrylic acid in a ratio of 70–80% by weight, with an average molecular weight in the range of 500,000–700,000.

[0064] The resulting composition retains its rheological properties after prolonged thermal exposure (maintained at 70–95°C for 30 days). However, according to test results, it does not meet established requirements for the anti-corrosion protection of aircraft structural materials.

[0065] It is well known that one of the key requirements for anti-icing fluids (AIFs) is the stability of their viscosity-rheological properties over a wide temperature range and under various mechanical stresses. Several patents note that the use of surfactants in combination with hydrophobically modified thickeners significantly influences the formation of the composition's rheological properties.

[0066] However, the use of such combinations is associated with a number of challenges. Hydrophobic thickeners typically form associative bonds with surfactant molecules, which can alter the structure of the liquid phase, reduce its storage stability, and lead to unpredictable system behavior under external factors such as temperature changes, shear stress, or dilution with water. This, in turn, negatively impacts the performance characteristics of the liquid protection fluid, including protection time, spray uniformity, and compatibility with aircraft structural materials.

[0067] Furthermore, known formulations containing a combination of surfactants and modified thickeners are often prone to the formation of gel-like residues on aircraft surfaces, which impairs its aerodynamic properties and increases the risk of corrosive destruction of materials.

[0068] Therefore, it seems relevant to develop a new anti-icing fluid composition in which the combination of surfactants and thickener provides stable rheological properties without deteriorating other important performance indicators, including anti-corrosion protection and compatibility with structural materials.

[0069] The patent [Anti-icing compositions having alkylphenol ethoxylate nonionic surfactant and alkylaryl sulfonate hydrotrope: US Pat. 5,273,673. No. 07 / 937,011; filed 08 / 31 / 1992; published 12 / 28 / 1993, IPC C09K 3 / 18, C09K 3 / 00] presents an anti-icing composition based on an aqueous solution of glycols (MEG, PG, DEG, DPG or mixtures thereof). A mixture of cross-linked polyacrylic acid and a copolymer of acrylic acid with a hydrophobic monomer (0.2 - 0.8 wt.%) is used as a thickener. The proposed liquid has a long retention time of the solution on the surface due to the addition of low-molecular non-ionic surfactants (alkyl phenol ethoxylates) to the composition in an amount of 0.1 - 1 wt. % and alkyl aryl sulfonate as a hydrotrope.

[0070] In the patent [Deicing or antiicing fluids for aircraft: pat. 5334323 US. No. 07 / 687,209; declared 18.04.1991; published 02.08.1994, IPC C09K 3 / 18] individual substances are used as an antifreeze component: PG, 1,3-propylene glycol, DEG or a mixture thereof in an amount of 40 - 70 wt. %. According to the presented patent data, the composition of the antifreeze fluids includes a cross-linked homopolymer of acrylic acid (0.1 - 1 wt. %) acting as a rheology modifier in combination with a non-ionic surfactant from the group of alkoxylated higher alcohols (0.02 - 1.5 wt. %). Viscosity of a 0.5% aqueous solution of thickener measured using a Brookfield viscometer at 20 o C and 20 rpm, at a pH of 7, is 5,000–60,000 mPa s. The patent also states that neutralization of polyacrylic acid is preferably carried out with a mixture of NaOH and KOH, taken in a ratio of 2.5:1–1:2.5, which improves the "flowability" of the resulting PLF from the aircraft surface.

[0071] The analogous patent presents anti-icing fluids for aircraft thickened by associative polymers (“Aircraft deicing / anti-icing fluids thickened by associative polymers” patent for invention 5708068 US. No. 08 / 586,970; published 01 / 13 / 1998, IPC C07C 31 / 20, C07C 31 / 22, C08F 8 / 44, C09D 5 / 00, C09K 3 / 18).

[0072] The analogue describes a "universal" aviation fluid based on glycol and / or glycerin (i.e., suitable for use as any of the Type I, II, III, or IV fluids) that exhibits resistance to viscosity breakdown and other critical properties caused by heat and / or shear. The fluid can be formulated as a concentrate and then significantly diluted in the field for various applications. Improved performance is achieved by neutralizing the latex of the hydrophobic polymer thickener with a base, preferably an alkali metal hydroxide, preferably in combination with a weak base, such as a salt of a weak acid, and a surfactant that binds to the thickener.

[0073] The analog contains a method for producing anti-icing fluids (AIFs) intended for use as universal compounds on aircraft. The anti-freeze components in these fluids include individual compounds—monoethylene glycol (MEG), diethylene glycol (DEG), propylene glycol (PG), and glycerin—as well as mixtures of various compositions.

[0074] These liquids contain a polymer latex thickener, a copolymer of acrylic acid that forms a mixed-type associative complex with a surfactant in the aqueous phase. The thickener content in the composition is at least 0.5% by weight. Neutralization of the polymer's acid groups is achieved using an alkali metal hydroxide in combination with a weak base (amine). The use of sodium hydroxide also improves the thermal stability of the finished composition.

[0075] Both anionic surfactants (higher alcohol sulfates) and nonionic compounds, such as octyl and nonylphenol ethoxylates, can be used as surfactants.

[0076] The patent for the invention “Deicing agent and / or anti-icing agent” 7875203 US. No. 12 / 310,318; published on 01 / 25 / 2011, IPC C09K 3 / 18, proposes a deicing agent based on MEG, PG, DEG or dipropylene glycol in an amount of 35 - 95 wt.%.

[0077] The main thickener in the composition is a dendrimer in an amount of 0.001 to 5 wt.%, which is used together with a co-thickener in a concentration range of 0.01–5 wt.%. Water-soluble copolymers of acrylic acid, polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycols, or xanthan gum can serve as co-thickeners.

[0078] The anti-icing fluid presented in this invention is characterized by an extended shelf life, minimal toxicity and high resistance to deformation under shear loads.

[0079] Based on the analysis of the above data, it can be concluded that synthetic polymer thickeners are used in the vast majority of cases in the production of Type IV deicing fluids. Among the most common are cross-linked homo- and copolymers of (meth)acrylic acid and their modified derivatives, as well as compounds such as cellulose ethers, polyethylene glycols, polyvinylpyrrolidones, polyvinyl alcohols, and polyethylene oxides.

[0080] However, all of the listed substances are prone to partial or complete irreversible degradation under mechanical stress, which negatively impacts the fluid's performance stability. Furthermore, residues of these thickeners, under certain environmental conditions, can form gel-like deposits on aircraft surfaces, negatively impacting its aerodynamic performance and maneuverability.

[0081] To eliminate the above-mentioned drawbacks in the analogue, which is an anti-icing compound and an anti-icing composition thickened with sheet silicates (patent US 7037442 published on 02.05.2006; IPC B64D 15 / 06, C09K 3 / 18, B64D 15 / 00), owned by the company "CLARIANT GMBH", it is proposed to use layered silicates as thickeners in an amount of 0.05 to 10 wt. %. Anti-icing liquids obtained on their basis retain a stable viscosity when exposed to mechanical stress, and the residues formed after drying completely dissolve upon repeated contact with water.

[0082] An analogue in the form of an anti-icing liquid is known from the prior art (patent for invention GB559172A, published 1944-02-08).

[0083] Similar to Anti-icing Fluid ANGLO-SAXON PETROLEUM CO., Ltd. and JAPES, DH July 10, 1942, No. 9584. [Class 29] An anti-icing fluid which has no solvent action on aircraft finishes consists of a water-miscible polyhydric alcohol such as glycerin or ethylene glycol and a spreading agent consisting of a monohydric alcohol such as diacetone alcohol, secondary butyl alcohol or isopropyl alcohol, the viscosity of the fluid at -40°C not exceeding 500 centistokes, the pour point below -40°C, the flash point above 90°F and the spreading pressure, expressed as the advance angle of contact between the fluid and the aircraft surfaces, not exceeding 45 degrees.Corrosion inhibitors such as sodium nitrite or various other metal salts, oxidation inhibitors such as β-naphthol, fire retardants such as carbon tetrachloride, and wetting agents such as an alkali metal salt of a sulfated higher alcohol may be added. One example uses 35 parts ethylene glycol, 55 parts secondary butyl alcohol, 10 parts water, 0.2 parts β-naphthol, and 0.2 parts sodium nitrite.

[0084] The analog contains information on corrosion inhibitors. Any substance with anti-corrosion properties in an aqueous system can be used for this purpose, provided it is soluble in the deicing fluid within the temperature range in which the fluid will be used. Examples of corrosion inhibitors that can be used include sodium, nitrites, cadmium and zinc salts such as zinc sulfate 90, cadmium sulfate, zinc acetate, cadmium acetate, and zinc salt of diisopropylsalicylic acid (the advantage of which is that it simultaneously acts as an oxidation inhibitor), as well as alkali metal phosphates 95, such as trisodium phosphate.

[0085] Some patents also describe de-icers for aircraft, containing glycerin as an anti-freeze component. For example, the patent (Environmentally friendly de-icer and anti-icer compositions: Pat. 2387923 CA. No. 2387923; filed 18.10.2000; published 26.04.2001, IPC C09K 3 / 18, C12N 11 / 04, C12N 9 / 00] presents a de-icer containing glycerin, a non-ionic surfactant, a polysaccharide thickener and water.

[0086] An analogue in the form of Compositions for combating icing (“Compositions for deicing / anti-icing” patent for invention No. 8562854 US. No. 13 / 578,924; published 10.22.2013, IPC C09K 3 / 18) is known from the prior art.

[0087] The analog is an anti-icing fluid that contains at least 20% by weight of a freezing point depressant selected from short-chain polyols with 3-5 carbon atoms. The fluid also contains at least 10% by weight of water, a thickener, a surfactant, and a pH adjuster. The fluid meets the requirements of SAE / AMS 1428 or its revisions for Type II, III, or IV non-Newtonian anti-icing fluids for aircraft. The Type IV anti-icing fluid described in this patent has a HOT time of greater than 80 minutes. It is also noted that it can be used as a Type II anti-icing fluid.

[0088] An analogue is known, which is an anti-icing fluid (patent for invention GB1272464A, published 1972-04-26). The analogue contains one or more of the following components: ethylene glycol, propylene glycol and glycerin; polyethylene glycol ether of diisoalkylphenol; and a copolymer of acrylic or methacrylic acid with alkyl acrylate or methacrylate as a thickener. The compositions may contain sodium or potassium hydroxide to dissolve the polymer, as well as sodium hydrogen phosphate or guanidine chromate as a corrosion inhibitor. In this case, the analogue contains an aqueous solution of an alcohol component including one or more of ethylene glycol, propylene glycol and glycerin; polyethylene glycol ether of diisoalkylphenol; and a thickener, which is a copolymer of acrylic acid or methacrylic acid and an alkyl ester of acrylic acid or methacrylic acid.

[0089] An example of an analogue is the following composition by mass. %: Ethylene glycol 80.0%, Polyethylene glycol diisooctylphenol ether containing 7 ethoxy groups 0.2, Copolymer of methacrylic acid and methyl methacrylate (molar ratio of acid and ester 4:1; viscosity of the copolymer solution) 130 centistokes) 1.9, Sodium hydroxide 0.4 Disodium hydrogen phosphate 1.6, Water 15.9.

[0090] The closest technical solution to the claimed invention is the formulation of anti-icing liquid in the form of the Formulation of anti-icing liquid type 4 (patent for invention RU2686172C1, Published: 04 / 24 / 2019 Bulletin No. 12).

[0091] This analog relates to anti-icing fluid compositions for ground handling of aircraft. The anti-icing fluid includes water, a mixture of diethylene glycol and glycerin, or pure glycerin; a hydrophobically modified acrylic thickener; and a surfactant, which is a mixture of polyoxyethylene glycol ethers of synthetic primary higher fatty alcohols of fraction C. 12 -WITH 14 ; a corrosion inhibitor, which is a mixture of methanol, secondary fatty alcohols and ketones of the C6-C9 fraction, which is a product of the oxidation process of the C6-C9 n-alkanes fraction with an aqueous solution of hydrogen peroxide on encapsulated titanium silicate; sodium soaps of higher carboxylic acids isolated from soap effluents.

[0092] The technical objective of the invention is to create an anti-icing fluid that has a relatively higher viscosity, has stable thermally stable properties, improved anti-corrosion properties and performance characteristics.

[0093] Anti-icing fluid which is an aqueous glycol-based solution including glycol made from diethylene glycol, glycerin, a thickener made in the form of an acrylic thickener, a corrosion inhibitor and a surfactant containing polyethylene glycol monomethyl ether.

[0094] The corrosion inhibitor contains alcohol, a monobasic acid containing 5 to 15 carbon atoms, and a dibasic acid containing 5 to 15 carbon atoms, sodium and potassium salts of higher carboxylic acids.

[0095] The anti-icing fluid contains diethylene glycol and glycerin in a ratio of 4:1.

[0096] It also contains a corrosion inhibitor selected from the group consisting of alkali metal borates, alkali metal silicates, alkali metal benzoates, alkali metal nitrates, alkali metal nitrites, and alkali metal molybdates.

[0097] In this case, a liquid-swellable polymer thickener containing hydrophobic groups can be used as a thickener.

[0098] In this case, a hydrophobically modified acrylic thickener can be used as a thickener.

[0099] The thickener is soluble in liquid.

[0100] It contains a thickener in an amount sufficient to thicken the liquid.

[0101] The anti-icing fluid has the following component content, wt.%:

[0102] Diethylene glycol - 10-45

[0103] Glycerin - 10-65

[0104] Corrosion Inhibitor - 1-5

[0105] Surfactant - 3-7

[0106] Thickener - 0.05-0.1

[0107] Water – supplemented to 100

[0108] The proposed anti-icing fluid differs from the prototype by introducing new components and a new ratio of components. The use of new components in the proposed anti-icing fluid composition and the determined ratio of all ingredients provides properties that are unique to the stated technical solution, namely, a relatively higher viscosity, stable thermal stability, and improved anti-corrosion properties and performance characteristics. The proposed anti-icing fluid, while complying with the stated composition, has properties that meet the requirements of SAE AMS 1424 and ISO 11075.

[0109] An example of the execution of the Declared Anti-icing liquid is the Anti-icing liquid produced by IC Composite LLC.

[0110] The anti-icing fluid was produced in accordance with the declared component content.

[0111] When developing the Anti-icing Fluid, the influence of not only surfactant additives but also the corrosion inhibitor on the properties of the system was taken into account, and this influence was corrected by optimizing its content in the mixture, along with the selection of the optimal thickener and surfactant.

[0112] The obtained data showed that the use of the proposed substance as a corrosion inhibitor and thickener can be considered optimal for ensuring the required level of viscosity, achieving anti-corrosion properties and performance characteristics, while the produced composition had stable thermally stable properties.

[0113] The method for producing the proposed de-icing fluid includes the following steps: a corrosion inhibitor, surfactant, and thickener are dissolved in water at a temperature of 10 to 70°C. The resulting aqueous solution is mixed with diethylene glycol and glycerin, or with pure glycerin. The mixture is then filtered, after which the finished product is packaged and used.

[0114] All components used in the anti-icing fluid formula are readily available, are not scarce materials, and are mass-produced by industrial enterprises.

[0115] The resulting anti-icing fluid meets the requirements of SAE AMS 1424 and ISO 11075 standards.

[0116] Tables 1 and 2 show the compositions of the proposed anti-icing fluid samples and their properties compared to similar products. The data in Table 2 demonstrates that the proposed anti-icing fluid has a higher viscosity, stable thermal properties, and improved anti-corrosion properties than the prototype.

[0117] The proposed anti-icing fluid has performance characteristics no lower than those of the prototype.

[0118] Table 1 – Main characteristics of the developed models of anti-icing fluids

[0119] Recipe 1 Appearance Viscous liquid of light green color Warp Glycerol Mass fraction of base, % 55 Mass fraction of thickener, % 0,06 Mass fraction of surfactant 2 Mass fraction of corrosion inhibitor, % 1 pH 7,8 Viscosity at 20 ºС, mPa s 6400 Viscosity at -20 ºС, mPa s 61200 Crystallization temperature, ºС -70 Surface tension at 20 ºС, mN / m 37 Refractive index at 20 ºС 1,367

[0120] A special advantage of the new composition is its relatively low viscosity, which ensures rapid and complete drainage of the product during aircraft takeoff.

[0121] The data in the table showed that the declared Anti-icing fluid has a higher viscosity, stable thermal properties, improved anti-corrosion properties and performance characteristics.

Claims

1. An anti-icing fluid which is an aqueous glycol-based solution comprising glycol made from diethylene glycol, glycerin, a thickener made in the form of an acrylic thickener, a corrosion inhibitor and a surfactant containing polyethylene glycol monomethyl ether, wherein the corrosion inhibitor contains an alcohol, a monobasic acid having from 5 to 15 carbon atoms in its composition, and a dibasic acid having from 5 to 15 carbon atoms in its composition, sodium and potassium salts of higher carboxylic acids, with the following content of components, wt.%: diethylene glycol 10-45 glycerol 10-65 corrosion inhibitor 1-5 surfactant 3-7 thickener 0,05-0,1 water the rest up to 100 2. The anti-icing fluid according to paragraph 1, characterized in that diethylene glycol and glycerin are contained in the mixture in a ratio of 4:1 by weight.

3. The anti-icing fluid according to claim 1, characterized in that the corrosion inhibitor additionally contains at least one component selected from the group consisting of alkali metal borates, alkali metal silicates, alkali metal benzoates, alkali metal nitrates, alkali metal nitrites, and alkali metal molybdates.

4. An anti-icing fluid according to claim 1, characterized in that a liquid-swelling polymer thickener containing hydrophobic groups is used as a thickener.

5. The anti-icing liquid according to paragraph 1, characterized in that the thickener is soluble in the liquid.

6. The anti-icing fluid according to paragraph 1, characterized in that it contains a thickener in an amount sufficient to thicken the fluid.