FI87228B - AVISNINGS- OCH NEDISNINGSSKYDDSMEDEL FOER FLYGPLAN. - Google Patents

Description

! 87228

Aircraft de-icer and anti-freeze agent

The invention relates to an anti-icing and anti-freezing agent for aircraft, based on glycol-5 and water and having a thickened acrylic polymer as a thickener.

Such a substance is known from U.S. Patent 4,358,389. More specifically, it consists essentially of (1) 40 to 65% by weight of a glycol which is an alkylene glycol having 2 to 3 carbon atoms or an oxalkylene glycol having 4 to 6 carbon atoms; (2) 35 to 60% by weight of water; (3) 0.05 to 1.5% by weight of a thickener which is a reticulated polyacrylate having a viscosity of 1,000 to 50,000 mPa.s in a 0.5% by weight aqueous solution at 20 ° C pH: n is 7.5 to 10 and has a laminar flow behavior in a 0.1 to 1.5% by weight aqueous solution at a temperature of +20 ° C, 0 ° C and -10 ° C at a pH of 7.5 - 10 and a shear rate of at least 20 to 20,000 s'1; (4) 0.05 to 1% by weight of water-insoluble components which are miscellaneous mineral oils; (5) 0.05 to 1% by weight of a surfactant which is an alkali metal alkylarylsulfonate; .25 (6) 0.01 to 1% by weight of at least one corrosion inhibitor; and (7) an amount of at least one basic compound which is an alkali metal carbonate, alkali metal bicarbonate, alkali hydroxide or amine such that the pH of the substance is 7.5 to 10, wherein the amount of components a) and b) in the substance is at least 94% by weight % by weight of the substance.

This well-known de-icing and anti-freeze agent for aircraft has proven to be useful and is already used in many places. It has now been shown that this substance at very low temperatures, such as those prevailing in the Arctic, for example (temperatures of about -20 to -35 ° C), still leaves much to be desired in terms of viscosity-temperature behavior. In winter temperatures in Central Europe and other similar regions (temperatures from about 0 to -15 ° C) the viscosity is of the required magnitude, 5 and this is also the case at low shear rate values, namely up to about 20 s'1 ("low shear viscosity"). However, at temperatures below about -15 ° C and especially at temperatures from about -20 to -35 ° C, especially at low shear rate values, the viscosity proves to be too high; for example, the viscosity of the substance is measured at -25 ° C as measured by a Brookfield viscometer using a rotation speed of 0.3 rpm (UpM) of 50,000 to 60,000 mPa.s (desirable values would be 10,000 to 40,000 mPa.s). How this works in practice is explained in more detail below: It is known that a liquid preparation applied to the surface of an airplane, especially in aerodynamically important parts of the surface, to remove ice and prevent re-freezing (when the airplane is standing on the ground) must completely drain during the start-up event. (above all lift) during the flight is guaranteed. With the known substance, this also takes place quite satisfactorily in all parts of the surface where high shear rates occur; in these cases, the viscosity of the substance decreases rapidly, thus it becomes low viscosity and flows away quickly and completely. But in those parts of the surface where relatively low shear rates occur (such as aerodynamically relatively calm parts of the surface, such as the rear parts of 30 wings), the known liquid preparation flows more slowly, especially at arctic temperatures, so that there is still liquid after said start-up. . It must also be borne in mind that modern aircraft 35 have, for example, wing structures which are particularly sensitive to freezing and contamination. These 3 87228 wings must therefore be absolutely free of ice and snow in order to guarantee their full buoyancy. Therefore, antifreeze is also necessary for these aircraft, even in border conditions (+1 to -2 ° C) and with a small frost. Especially in this case, the material applied is required to have optimal outflow properties, so that the full lift of the wing can be obtained already at the start, i.e. at the moment of rotation.

It is clear from the above suggestions that the known aircraft de-icing and anti-icing agent should be improved while maintaining its good "low shear viscosity" at a temperature of about 0 to -15 ° C, so that even at temperatures below -15 ° C and in particular, even at still -20 to about -35 ° C, the viscosity rises only relatively little in order to guarantee good off-flow even at low shear rates (i.e. in aerodynamically quieter places). Namely, since there is a direct link between the "holdover" time (the period during which the de-icer, during the inevitable delay between the ice-20 ton and the start, provides protection against re-freezing in freezing rain) and the "rest viscosity" at a temperature of about 0-15 ° C, this viscosity of the substance should be substantially maintained, but its resting viscosity should be significantly reduced at temperatures below -25 to 15 ° C in order for the substance to drain away during start-up to the desired extent even in aerodynamically calmer locations. Thus, an aircraft de-icing and anti-freeze agent should be available that meets the viscosity of the aircraft when starting the aircraft. 30 high requirements (based on the prevailing aerodynamic conditions) over the entire temperature range of about 0 to -35 ° C.

It has now surprisingly been found that the disadvantages of a known de-icing and antifreeze agent can be removed and a substance having said desired properties used as a thickener in a particular blend of 4,872,28 crosslinked acrylic acid homopolymer and selected crosslinked acrylamide / acrylamide / acrylamide or acrylamide alkali metal acrylate copolymer and basic (temporal) compounds for adjusting the pH of the substance from three different and compatible compounds, each of which is used in a specific amount, and these compounds are ammonia, monoethanolamine, diethanolamine and / or triethanolamine (first basic compound); potassium) hydroxide (second basic compound) and in addition (second) alkali metal hydroxide (third basic compound). It has been found that when using said special combinations of acrylic polymers, the desired viscosity can also be achieved at very low temperatures and low shear rates if three additional basic compounds are present simultaneously, each acting in its own way on both acrylic polymers, e.g. swelling and viscosity .

20 A new anti-icing and anti-icing agent for aircraft, based on glycols and water, comprising a corrosion inhibitor and an alkali metal alkyl aryl sulfonate as surfactant and acrylic lipolymers and a base as a thickener, consisting of 25 a) 40 to 70% by weight of glycol, is an alkylene glycol having 2 to 3 carbon atoms or an oxalkylene glycol having 4 to 6 carbon atoms, b) 0.1 to 1% by weight of crosslinked acrylic polymers consisting of 1 part by weight of the crosslinked structures of acrylic acid or alkali metal acrylate and acrylamide, 10 to 90% by weight of copolymerized acrylic acid or alkali metal acrylate units and 10 to 90% by weight of copolymerized acrylamide units, and 1 to 10 parts by weight of 35 acrylic homopolymers of acrylic acid or alkali metal acrylate 35 000 mPa.s and have laminar flow drives Behavior at a shear rate of 0-20,000 s'1, with viscosity and laminar flow behavior measured in each case using a 0.5% by weight aqueous solution at 5 ° C at pH 7 with a Brookfield viscometer at 20 rpm. 1 or by means of a rotary viscometer to shear rates up to 20,000 s'1, c) 0.05 to 1% by weight of a surfactant which is an alkali metal alkylarylsulfonate, 10 d) 0.01 to 1% by weight of at least one corrosion inhibitor , (e) the following three basic compounds (e): - e3, used in adjusted amounts to adjust the pH to between 7,5 and 11:15 (e1) 0,01 to 1% by weight of ammonia, monoethanolamine, diethanolamine or triethanolamine, or a mixture thereof, e2) 0.05 to 0.7% by weight of potassium hydroxide and e3) 0.01 to 0.5% by weight of other alkali metal hydroxide, and f) water which is absent in weight percent, the weight percent is calculated in each case in relation to the weight of the substance (finished substance or the weight of the total mixture, i.e. com. . the sum of components a) to f) is 100% by weight).

Component a) of the deicing and de-icing agent according to the invention is preferably ethylene glycol, propylene glycol (1,2-propylene glycol or 1,3-propylene glycol) and / or diethylene glycol.

Component b) comprises two selected crosslinked acrylic polymers in a certain weight ratio, such that the crosslinked homopolymer is made of acrylic acid or alkali metal acrylate, preferably sodium or potassium acrylate, and the crosslinked copolymer is from 10 to 90% by weight, preferably from 80% to 90% by weight, % copolymer-35 acrylamide and 10 to 90% by weight, preferably 20 to 80% by weight of copolymerized acrylic acid or copolymerized alkali metal acrylate, preferably sodium or potassium acrylate, and the weight percentages are based on the copolymer. , wherein per part by weight of the copolymer is 1 to 10 parts by weight, preferably 3 to 8 parts by weight of the homopolymer. In addition, each of the crosslinked acrylic polymers is used in each case with a certain viscosity and a special flow behavior, namely a viscosity of 5,000 to 70,000 mPa.s, preferably 10,000 to 50,000 mPa.s at 0.5% by weight. In an aqueous solution at 20 ° C at pH 7 using a Brookfield viscometer at 20 rpm and having a laminar flow behavior in a 0.5% by weight aqueous solution at 20 ° C at pH 7 at a shear rate of 0-20 000 measured on a 15 s'1 high shear rotation viscosime ter; from the obtained yield curve (viscosity curve) from a shear rate of 0 s'1 to a high value of 20,000 s "1, it is observed whether it is a laminar or a non-laminar flow.

Both acrylic polymers used in accordance with the invention are known and commercially available. Crucially, they have the above-mentioned features and characteristics. These are crosslinked polymers marketed under the trade name polyfunctionally statistical crosslinked acrylic polymers. The homopolymer is prepared, as described in detail in, for example, U.S. Patent Nos. 2,798,053 and 2,923,692, preferably by polymerizing acrylic acid or alkali metal acrylate in the presence of a radical initiator (catalyst) and a crosslinker per molecule with at least two polymerizable groups, preferably CH2. and separating the powdered polymer from the polymer dispersion using a water-immiscible organic solvent such as benzene, toluene, hexane, heptane and the like to polymerize the acrylic acid and water or a water-like liquid to polymerize the acrylate. Of the two crosslinked homopolymers, namely the homopolymer of acrylic acid and the homopolymer of alkali metal acrylate, the former is preferred within the scope of the invention. The copolymer is prepared by copolymerizing acrylamide and acrylic acid or an alkali metal acrylate in the presence of a radical initiator and one of the above crosslinkers and separating the powdered copolymer from the copolymer dispersion; the copolymerization is also carried out with suitable solvents (cf. both of the above-mentioned U.S. patents). A further process for preparing the copolymer is described in detail in U.S. Patent No. 4,237,249. to saponify a corresponding number of amide groups and thus also to obtain the desired weight percentages of alkali metal acrylate groups, followed by a powdered acrylamide / alkali metal acrylate-20 copolymer. Both crosslinked copolymers, namely a copolymer of acrylic acid and acrylamide and a copolymer of alkali metal acrylate and acrylamide, have been prepared within the scope of the invention by an alkali metal acrylate / acrylamide copolymer by the process described in U.S. Patent No. 4,237,249.

Suitable crosslinkers include, as disclosed in U.S. Patent Nos. 2,798,053, 2,923,692, and 4,237,249, polyunsaturated (preferably 2- to 5-unsaturated) hydrocarbons, such as vinylbenzene, divinylnaphthalene, and polybutadiene, preferably polyunsaturated. - 5-unsaturated) esters, such as allyl acrylate, crotyl acrylate, ethylene glycol diacrylate, glycerol diacrylate, glycerol triacrylate, diallyl phthalate, diallyl esters, diallyl oxalate, diallyl citrate and triallyl citrate, and the like 87228 mät) ethers, such as diallyl ether, diallylethylene glycol ether, diallylpropylene glycol ether, di- or triallyl ether of trimethylolethane or trimethylolpropane, succinyl ether of glycerol (also polyglycerol, preferably polyglycerol, preferably 5-di-decaglycerol), preferably erytrito-yl n, pentaerythritol, arabitol, xylitol, dulsitol, mannitol, sorbitol, glucose and sucrose, di-, tri-, tetra- or penta-allyl ether and the corresponding methyl-10-ethers. Preferred crosslinkers are polyunsaturated ethers, of which diallyl ether, di- or triallylglycerol ether, di- or triallyltrimethylolethane ether, di- or triallyltrimethylolpropane ether, tetra-allyloxyethane and trialcohol alcohols, sugar alcohols, sugar alcohols, as well as the corresponding metal ethers.

The amount of crosslinker in the homopolymer and copolymer is usually 0.1 to 10% by weight, preferably 1 to 5% by weight of the homopolymer or copolymer. The crosslinked homopolymer used according to the invention accordingly consists essentially of polymerized alkali metal acrylate (alkali metal is preferably K or Na) or polymerized acrylic acid (as main component) and 0.1 to 10% by weight, preferably 1 to 5% by weight: polymerized crosslinker, and the weight percentages are expressed relative to the polymer, or in other words 90 to 99.9% by weight, preferably 95 to 99% by weight of polymerized alkali metal acrylate or polymerized acrylic acid and 0.1 to 10% by weight, preferably 1% by weight. -5% by weight of polymerized crosslinker, and -30% by weight relative to polymer. Of the two polymers, as already mentioned above, an acrylic acid containing a major component (acrylic acid homopolymer) is preferred.

The crosslinked copolymer used according to the invention, as shown above, consists essentially of 10 to 90% by weight, preferably 20 to 80% by weight, of polymerized alkali metal acrylate (alkali metal is preferably K or Na) or polymerized acrylic acid and 10 to 90% by weight %, preferably 20 to 80% by weight of polymerized acrylamide and 0.1 to 10% by weight, 5 preferably 1 to 5% by weight of polymerized crosslinker, and the weight percentages are expressed relative to the polymer (i.e. -the sum of the limerized alkali metal acrylate or acrylic acid, acrylamide and crosslinker is 100% by weight); in other words, the crosslinked copolymer consists essentially of, for example, 10 to 89.9% by weight, preferably 20 to 75% by weight of polymerized alkali metal acrylate or acrylic acid, 10 to 89.9% by weight, preferably 20 to 75% by weight. % by weight of polymerized acrylamide and 0.1 to 10% by weight, preferably 1 to 5% by weight of polymerized crosslinker, and the weight percentages are expressed relative to the polymer.

As mentioned above, of the two polymers, a preferred polymer is prepared according to U.S. Patent No. 4,237,249 from an alkali metal acrylate, an acrylamide, and a crosslinker.

Component c) of the deicing and antifreeze according to the invention is preferably a potassium and / or sodium alkylarylsulfonate having one or more, preferably 1 or 2, sulfonate groups (SO 3 K or SO 3 Na), one or more, preferably one or two alkyl groups having 5 to 18, preferably 12 to 18 carbon atoms and one or more, preferably one or two, benzene rings. Potassium and / or sodium alkyl benzene sulfonates having 12 to 18 carbon atoms in the alkyl group (having an SO 3 K or SO 3 Na group and an alkyl group) are preferred. Since hydrocarbon mixtures, such as those obtained as petroleum distillation fractions, are also used as starting materials in the preparation of alkylarylsulfonates, the alkyl group can also represent such a mixture; then the number of carbon atoms is preferably 12 to 18 (average number 35 to 15). Alkali metal alkylates used as component (c)

10 8722 R

aryl sulfonates are known and commercially available (cf. U.S. Patent 4,358,389).

Component d) comprises corrosion inhibitors useful for glycols and water-based liquids. Suitable corrosion inhibitors include alkali salts of fatty acids, preferably potassium and sodium salts of lauric, palmitic, stearic, benzoic and oleic acids; salts formed with mono- and dialkylamines (optionally alkoxylated) and their mineral and fatty acids, preferably butyl, hexyl, octyl, isononyl, oleyl, dipropyl and dibutylamine; and triazoles, preferably benzstriazole and tolytriazole. Of said corrosion inhibitors, triazoles are preferably used; particularly preferred is benzstriazole.

Component e), by means of which the pH of the substance according to the invention is adjusted to 7.5 to 11, preferably 8 to 10, consists of a representative of each of the three groups of basic compounds. The three groups are e3) ammonia, monoethanolamine, diethanolamine or triethanolamine or a combination of two or more of these compounds; e2) KOH and e3) an alkali metal hydroxide other than KOH, preferably NaOH. Representatives of the group of three basic compounds are used, as described above, in the amounts determined in each case (expressed as a percentage by weight of the finished substance). Crucial is that the stated pH is reached. Thus, if, for example, the use of the smallest amount of the three compounds in each case does not reach the stated pH value, then at least one of them must be taken in a correspondingly larger amount. If, on the other hand, when the largest amount of these three compounds is used, the pH is higher than 11, preferably higher than 10, a correspondingly smaller amount of at least one of the three compounds should be taken. It is preferred that KOH and another alkali metal hydroxide (e.g. NaOH) be used in amounts within a given range of at least 2: 1 by weight, so that one part by weight of NaOH (secondly alkali metal hydroxide) is used. 87228 as a binder) contains at least two parts by weight of KOH. Amines and ammonia as well as alkali metal hydroxides are preferably used as a 10 to 40% by weight aqueous solution.

Component f) is water. Preferably, for example, water from which the salts have been removed by means of an ion exchanger or by distillation is used.

The de-icing and anti-freezing agent according to the invention is in principle prepared by mixing the individual components together in the desired order. This can be done, for example, in a tank equipped with a stirrer, possibly by heating to a temperature of about 60 ° C.

According to a preferred method of preparation, which achieves a relatively rapid dissolution of the individual components, the procedure is as follows: Water (component f) is placed in the tank at room temperature while a thickener (component b) is added with stirring. After the addition, it is appropriate to continue stirring for some time until the solution is homogeneous. Alkylarylsulfonate (component c) and anti-corrosion agent (component d) are then added to the mixture with stirring, followed by glycol (component a) with stirring. The neutralizing agent (component e) is now added again with stirring, with potassium hydroxide being added as the last of the three neutralizing agents to adjust the given pH.

The deicing and antifreeze agent according to the invention is characterized by a long "holdover" time, good viscosity behavior, optimal theological properties, good thermostability and high shear stability. It also has a relatively high pour point reduction, good wetting effect, only low hydrophilicity, good heat resistance, very long shelf life even at high temperatures and good corrosion resistance. In general, it is perfectly compatible with all 35 aircraft materials required by aircraft manufacturers. In addition, when applied to aircraft, the silicon i2 87228 has been shown to have good sprayability and very advantageous drainage properties during aircraft start-up. In addition, the new substance meets the requirements mentioned at the beginning for use at temperatures of -15 ° C and below. It is also available without problems in the Arctic and has the special properties necessary at these low temperatures. In particular, it also has an optimal viscosity behavior at low temperatures and low shear rates, and in this way guarantees the desired rapid outflow start-up time na even under these extreme conditions.

When using the deicing and antifreeze agent according to the invention, it is expedient to further dilute it with water, preferably in a ratio of 75:25 (substance: water) or 50:50. In this diluted form, it is sprayed onto the surfaces to be treated using conventional equipment. When removing ice from aircraft, the diluted solution is usually heated to 50-95 ° C before spraying. To preserve de-iced surfaces, they are treated with undiluted product.

The invention is further clarified by means of examples.

Example 1

The substance according to the invention was prepared by mixing 25 components by weight of a): 40.00% by weight of diethylene glycol and 10.00% by weight of propylene glycol, b) 0.03% by weight of a crosslinked sodium acrylate / acrylamide copolymer consisting essentially of 20% by weight. % by weight of polymerized potassium acrylate, 78% by weight of polymerized 30 acrylamide and 2% by weight of polymerized crosslinker (prepared according to U.S. Patent 4,237,249), and 0.20% by weight of a crosslinked acrylic acid polymer which consists essentially of 98% by weight of polymerized acrylic acid and 2% by weight of polymerized crosslinker 35 (the weight ratio of polymers is thus 1: 6.6); the Brookfield viscosity of each polymer at 20 rpm in 87.58% aqueous solution in 0.5% w / w at 20 ° C at pH 7 was 45,000 mPa.s and the flow behavior was laminar up to a shear rate of 20,000 s'1. , c) 0.15% by weight of sodium alkylbenzenesulfonate having an average number of carbon atoms of 5 alkyl groups of 15, d) 0.03% by weight of benztriazole, e) 0.05% by weight of triethanolamine, 0.03% by weight of sodium hydroxide and 0.11% by weight of potassium hydroxide and f) 49.40% by weight of water.

Mixing of components a) to f) was performed at room temperature in a tank equipped with a stirrer. Most of the water was placed in the tank and a thickener, i.e. both reticulated acrylic polymers, was added with stirring. After this addition, stirring was continued until the solution was homogeneous. The alkylbenzenesulfonate, glycol, anti-corrosion and neutralizing agent were now additionally mixed and mixed again until the solution was homogeneous. The three neutralizing agents were mixed in the order given, with sodium hydroxide and potassium hydroxide being added as a 30% to 20% aqueous solution prepared from the remaining water.

The pH of the finished solution was 8.

The deicing and antifreeze agent of the present invention had the following properties: According to the High Humidity Holdover Test (hereinafter referred to as Test 1), the "Holdover" time was more than 8 hours. The "Holdover" time according to the Freezing Rain Endurance experiment (hereinafter referred to as Experiment 2) was 37 min (performance of both experiments on page 21). The flow behavior in the rotary viscometer up to a shear rate of 30 up to 20,000 s * 1 was laminar.

Viscosity values at different temperatures and very low shear rate values (Brookfield viscosities at 0.3 rpm, corresponding to a shear rate of 0.08 s-1) are shown below: 87228 Temperature Brook field viscosity (° C) at 0.3 rpm (mPa.s) 5 +20 9,000 0 15,000 -10 20,000 -25 30,000 -35 45,000 10

Example 2

The substance according to the invention was prepared by mixing the following components: a) 58.00% by weight of diethylene glycol, b) 0.08% by weight of a crosslinked sodium acrylate / acrylamide copolymer consisting essentially of 37% by weight of polymerized sodium acrylate, 60% by weight % polymerized acrylamide and 3% by weight polymerized crosslinker (prepared according to U.S. Patent 4,237,249), and 0.62% by weight of a crosslinked acrylic acid polymer consisting essentially of 97% by weight of polymerized acrylic acid. and 3% by weight of a polymerized crosslinker (thus the weight ratio of polymers is 1: 7.8); the Brookfield viscosity of each polymer at 20 rpm in 0.5% w / w aqueous 25 at 20 ° C at pH 7 was 15,000 mPa.s and the flow behavior was laminar up to a shear rate of 20,000 s -1, c) 0.50% by weight of sodium alkylbenzenesulfonate having an average number of carbon atoms in the alkyl group of 15, d) 0.10% by weight of benzstriazole, e) 0.40% by weight of triethanolamine, 0.08% by weight of sodium hydroxide and 0 , 35% by weight of potassium hydroxide and f) 39.87% by weight of water.

Mixing of components a) to f) was performed. . as in Example 1.

The pH of the reconstituted solution was 9.5.

The deicing and antifreeze according to the invention had the following properties: According to Experiment 1, the "holdover" time was more than 8 hours. The "Holdover" time was 33 min according to Experiment 2 is 87228. The flow behavior in a rotary viscometer up to a shear rate of 20,000 s-1 was laminar.

Viscosity values measured as in Example 1 are shown below: 5 Temperature Brookfield viscosity (° C) at 0.3 rpm (mPa.s) 10 +20 11,000 0 15,000 -10 17,000 -25 25 000 -35 40 000 15

Example 3

The substance according to the invention was prepared by mixing the following components: a) 40.00% by weight of propylene-niglycol, b) 0.04% by weight of a crosslinked sodium acrylate / acrylamide copolymer consisting essentially of 10% by weight of polymerized sodium acrylate, 89% by weight % polymerized acrylamide and 1% by weight polymerized crosslinker (prepared according to U.S. Patent No. 4,253,237,249), and 0.10% by weight of a crosslinked acrylic acid polymer consisting essentially of 97% by weight of polymerized acrylic acid. and 3% by weight of a polymerized crosslinker (thus the weight ratio of polymers is 1: 2.5); the Brookfield viscosity of both polymers at 30 rpm in a 0.5 wt% aqueous solution at 20 ° C at pH 7 was 8,000 mPa.s or 50,000 mPa.s, respectively, and the flow behavior was laminar to shear rate. Up to 20,000 s'1, c) 0.07% by weight of sodium alkylbenzenesulfonate, if the average number of carbon atoms of the alkyl group is 15, d) 0.02% by weight of benztriazole, e) 0.03% by weight of monoethanolamine, 0.02% by weight of sodium hydroxide and 0.10% by weight of potassium hydroxide and f) 59.62% by weight of water.

16 87228

Mixing of components a) to f) was performed as in Example 1.

The pH of the finished solution was 8.

The de-icing and de-icing agent according to the invention had the following properties: According to Experiment 1, the "holdover" time was more than 8 hours. The "Holdover" time according to Experiment 2 was 32 min. The flow behavior in a rotary viscometer up to a shear rate of 20,000 s'1 was laminar.

Viscosity values measured as in Example 10 cat 1 are shown below: Temperature Brookfield viscosity (° C) at 0.3 rpm (mPa.s) 15 +20 9,000 0 17,000 -10 21,000 - 25 36 000 20 -35 47 000

Example 4

The substance according to the invention was prepared by mixing 25 components of the following components: a) 45.00% by weight of diethylene glycol and 24.00% by weight of propylene glycol, b) 0.15% by weight of a crosslinked sodium acrylate / acrylamide copolymer consisting essentially of 48 % by weight of polymerized sodium acrylate, 50% by weight of polymerized acrylamide and 2% by weight of polymerized crosslinker (prepared according to U.S. Patent 4,237,249), and 0.75% by weight. a crosslinked acrylic acid polymer consisting essentially of 95% by weight of polymerized acrylic acid and 5% by weight of polymerized crosslinker (thus the weight ratio of polymers is 1: 5); the Brookfield viscosity of each polymer at 20 rpm in a 0.5% w / w aqueous solution at 20 ° C at pH 7 was 60,000 mPa.s and the flow behavior was laminar up to a shear rate of 20,000 ι · 7 87228 s'1 , c) 0.80% by weight of sodium alkylbenzenesulfonate having an average number of carbon atoms of the alkyl group of 15, d) 0.04% by weight of benztriazole, e) 0.80% by weight of diethanolamine, 0.12% by weight of sodium hydroxide and 0.30% by weight of potassium hydroxide and f) 28.04% by weight of water.

Mixing of components a) to f) was performed as in Example 1.

The pH of the finished solution was 10.5.

The deicing and antifreeze agent according to the invention had the following properties: According to Experiment 1, the "holdover" time was more than 8 hours. The "Holdover" time according to Experiment 2 was 36 min. The flow behavior in a rotary viscometer up to a shear rate of 20,000 s'1 was laminar.

Viscosity values measured as in Example 15 are shown below: Temperature Brookfield viscosity (° C) at 0.3 rpm (mPa.s) 20 +20 10,000 0 18,000 -10 22,000 - 25 32 000 25 -35 48 000

Example 5

Example 2 was repeated with the difference that a crosslinked sodium acrylate / acrylamide copolymer consisting essentially of 78% by weight of polymerized sodium acrylate, 20% by weight of polymerized acrylamide and 2% by weight of polymerized crosslinker (prepared According to U.S. Pat. No. 4,353,237,249), and as component e) 0.40% by weight of ammonia, 0.08% by weight of sodium hydroxide and 0.35% by weight of potassium hydroxide.

The finished solution had the same values and properties with respect to pH, holdover time and flow behavior in the rotary viscometer ib 87228 as the mixture of Example 2. Its viscosity values, measured as in Example 1, are as follows: 5 Temperature Brookfield viscosity (° C) at 0.3 rpm (mPa.s) +20 10,000 10 0 14,000 -10 16,000 -25 20,000 -35 32,000 15 Example 6

Example 4 was repeated with the difference that a crosslinked sodium acrylate / acrylamide copolymer consisting essentially of 88% by weight of polymerized sodium acrylate, 10% by weight of 20% by weight of polymerized acrylamide and 2% by weight of polymerized crosslinker (prepared According to U.S. Patent No. 4,237,249), and as component e) 0.80% by weight of ammonia, 0.12% by weight of sodium hydroxide and 0.30% by weight of potassium hydroxide.

The finished solution had the same values and properties in terms of pH, holdover time and flow behavior in a rotary viscometer as the mixture of Example 4.

Its viscosity values, measured as in Example 1, are as follows: 30 Temperature Brookfield viscosity (° C) at 0.3 rpm (mPa.s) 35 +20 9,000 0 16,000 -10 20,000 -25 25,000 -35 32,000 40 19 87228

Comparative Example

The material of U.S. Patent 4,358,389 was prepared by mixing the following components: a) 58.00% by weight of diethylene glycol, b) 0.70% by weight of a crosslinked acrylic acid polymer consisting essentially of 97% by weight of polymerized acrylic acid and 3 % by weight of polymerized crosslinker; the Brookfield viscosity of the polymer at 20 rpm in a 0.5% w / w aqueous solution at 20 ° C at pH 7 was 10 to 15,000 mPa.s and the flow behavior was laminar up to a shear rate of 20,000 s'1, c) 0.50% by weight of sodium alkylbenzenesulfonate having an average number of carbon atoms in the alkyl group of 15, d) 0.10% by weight of benzstriazole, e) 0.43% by weight of potassium hydroxide and f) 40.27% by weight of water .

Mixing of components a) to f) was performed as in Example 1.

The pH of the finished solution was 9.4.

The deicer and antifreeze had the following 20 properties: According to Experiment 1, the "Holdover" time was more than 8 hours. The "Holdover" time according to Experiment 2 was 36 min. The flow behavior in a rotary viscometer up to a shear rate of 20,000 s -1 was laminar.

Viscosity values at different temperatures and very low in shear values (Brookfield viscosities at 0.3 rpm, corresponding to a shear rate of 0.08 s'1) are shown below: Temperature Brookfield viscosity 30 (° C) at 0 .3 rpm (mPa.s) +20 11 000 0 18 000 35 -10 27 000 -25 58 000 -35 85 000 2o 87228 The "holdover" time was determined according to the latest, very strict method, namely the Association of European Airlines (AEA), "Recommendations for de-icing / anti-icing of aircraft on ground", 2nd edition, 1.

September 5, 1983, Part 1, "Material Specification de / an-ti-icing fluid, aircraft". According to it, for type II fluids (de-icing and anti-freezing fluids) the "holdover" time is determined according to the so-called "High Humidity Holdover" test and the "Freezing Rain Endurance" test. 10 The first test is passed if the "holdover" time is at least 8 hours and the second test is passed if the "holdover" time is at least 30 minutes.

The results given by the examples and comparative example according to the invention are shown below.

Admittedly, the de-icing and anti-freezing agent known from U.S. Pat. No. 4,358,389 has the required laminar flow behavior and good holdover times, and also meets the currently required viscosity at very low shear rates of 0.08 ~ 12 (corresponding to Brookfield viscometer rotation speed 0.3 rpm) up to -15 ° C; however, its viscosity at temperatures below about -15 ° C and especially at temperatures from about -20 to -35 ° C at said low shear rate values is well above the required values. Thus, the viscosity of a known substance at -25 ° C at said low shear rate value is well above 50,000 mPa.s (according to the Association of European Airlines, this value should not exceed 50,000 mPa.s).

In contrast, the deicing and antifreeze agent of the invention not only has good holdover time values, the required laminar flow behavior and very good (low) viscosity values at low shear rates up to temperatures down to about -15 ° C, but also meets all other initial requirements. and the requirements of the AEA to an unexpected extent. The 87228 material of the invention has viscosity values (low shear viscosity at -25 ° C) at -25 ° C at a shear rate of 0.08 s'1 (corresponding to a speed of 0.3 min "in a Brookfield viscometer) of well below 50 ° C. 000 5 mPa.s. The substance according to the invention is characterized, inter alia, by the fact that it also has a relatively low viscosity at -35 ° C (a temperature which is no longer included in the AEA regulations at all) even at very low shear rate values of 0.08 s. Under these extreme conditions, its viscosity is somewhat below 50,000 mPa.s Thus, the de-icing and anti-freeze agent of the invention ensures a safe departure of the aircraft even at temperatures down to -35 ° C.

Claims (8)

1. Aircraft de-icing and icing protectants based on glycols and water, and containing a corrosion inhibitor and as surfactant an alkali metal alkylarylsulfonate and thickener cross-linked acrylic polymers and a base, characterized by a 40 - 70% by weight glycol, which is an alkylene glycol of 2-3 carbon atoms or an oxalkylene glycol of 4-6 carbon atoms; crosslinked acrylamide copolymer having 10 - 90 wt. copolymerized acrylic acid or alkali metal acrylate units and 10 - 90 wt.% copolymerized acrylamide units, and of 1 to 10 parts by weight of acrylic acid or alkali metal acrylate crosslinked homopolymer the monopolymer and copolymer are in each case 5,000 20 - 70,000 mPa.s and they have laminar flow feet at cutting property of 0-20,000 s'1, viscosity and the laminar flow footer is measured in each case using a 0.5% by weight aqueous solution at a temperature of 20 ° C at a pH of 7 using a Brookfield viscometer at a rotational speed of 20 min'1 or by means of a rotational viscometer all the way to the cutting speed of 20,000 s'1, c) 0.05 - 1% by weight of surfactant, which is alkali metal alkylaryl sulfonate, d) 0.01-1% e) at least one corrosion inhibitor, e) three following basic compounds e1 - e3 used in given amounts for adjusting the pH to 7.5 - 11: e1) 0.01-1 wt% ammonia, monoethanolamine , diethanolamine or triethanolamine or a mixture thereof, e2) 0.05 - 0.7% by weight of potassium hydroxide and (e) 0.01 - 0.5% by weight of another alkali metal hydroxide and f) water, which constitute the remaining weight percentages, in which case the weight percent in each case is calculated in proportion to the weight of the agent. Agent according to claim 1, characterized in that the cross-linked copolymer consists of 20-80% by weight copolymerized units of the acrylic acid or alkali metal acrylate and 20-80% by weight of the copolymerized units of acrylamide 10. Agent according to claim 1 or 2, characterized in that per one part by weight of the cross-linked copolymer there are 3-8 parts by weight of the cross-linked homopolymer. 4. A composition according to any one of claims 1 to 3, characterized in that the homopolymer and the crosslinked copolymer in each case have a viscosity of 10,000 - 50,000 mPa.s. 5. An agent according to any one of claims 1 to 4, characterized in that the cross-linked homopolymer is a cross-linked acrylic acid homopolymer and the cross-linked copolymer is a cross-linked alkali metal acrylate / acrylamide copolymer. 6. An agent according to any one of claims 1 to 5, characterized in that the cross-linked homopolymer and the cross-linked copolymer contain from 0.1 to 10% by weight of cross-linking agent based on the homo or copolymer. Agent according to any one of claims 1 to 5, characterized in that the cross-linked homopolymer and the cross-linked copolymer contain from 1 to 5% by weight of cross-linking agent based on the homo or copolymer. 27 87228 An agent according to any one of claims 1 to 7, characterized in that it contains components a) - f) in the following amounts: a) 50.00 - 60.00% by weight, b) 0.20 - 0 , 70% by weight, c) 0.10 - 0.70% by weight, d) 0.03 - 0.50% by weight, ex) 0.05 - 0.50% by weight, e2) 0.07 - 0.40 wt%, e3) 0.03 - 0.15 wt% and f) the remainder water.