FI111548B - Means for de-icing and preventing icing of aircraft - Google Patents

Abstract

The invention relates to a novel unthickened deicing agent and antiicing agent for aircraft which essentially comprises glycols and water as principal components, at least one nonionic surfactant from the group consisting of fatty alcohols and low-molecular-weight alkoxylates thereof and preferably a further anionic surfactant from the group consisting of alkali metal alkylarylsulphonates, corrosion inhibitors and optionally pH regulators. The new agent has a relatively long holdover time and therefore combines the advantages of unthickened and thickened aircraft deicing agents.

Description

111548 De-icing and Antifreeze for Aircraft De-icing and anti-icing agents for aircraft (hereinafter referred to simply as "de-icing agents or de-icing fluids" for short purposes) are used to remove ice, snow and / or mist from certain airborne layers. The time the de-icing fluid provides protection against the formation of ice, snow and / or frost on 10 aircraft is called the anti-icing time or duration.

GB-A 1 026 150 describes a deicing fluid consisting essentially of glycol and water as the main components and a relatively small amount of a tertiary amine of the fatty amines and at least one corrosion inhibitor. The reinforcing effect of water-soluble surfactants on thawing snow and ice is also referred to in US-A 3,412,030.

US-A-4,585,571 discloses an antifreeze-20 consisting of a glycol as the main component and a combination of three specific surfactants with one hydrophilic surfactant group of mono- or polyalcoholamines and one anionically hydrophilic surfactant group of sulfated or sulfonated compounds. .. 25 as a substance for hydrophobic groups in fatty acid diamine and hydrophilic alcoholamine. Although this anti-icing agent is said to provide long-lasting protection against freezing, it still leaves much to be desired, due, among other things, to the complex tenside system.

In the field of de-icing and antifreeze for aircraft, among the publications dealing, among other things, with extending the shelf life, thickeners are recommended for this purpose, since it has been clearly demonstrated that only the thickening agents can be achieved. US-A 4 358 389, DE-A 3 142 059 (Derwent Ref. AN 44404K / 19), US-A 4 744 913 and EP-B 0 360 183 (Derwent Ref. AN 90/092789/13). The de-icing agents described herein are thus essentially composed of glycol and water, at least one thickener, for example a group of polyacrylates, at least one tenside such as a group of alkylarylsulfonates and oxyalkylated alcohols, corrosion inhibitors and optionally pH adjusters. These thickened antifreeze agents, which are pseudoplastic fluids with non-Newtonian flow behavior, are typically characterized by a significantly longer reflux protection time compared to non-thickeners.

15 The AEA (Association of European Airlines) publication "De- / Anti-Icing of Aircraft on the Ground" (March 1993) defines two types of aircraft residual liquid. Type AEA type I fluids consist essentially of glycol, water, corrosion inhibitors, and optionally tensides and pH adjusters, and type AEA type II fluids also contain a thickener. AEA type I antifreeze fluids are liquids known as "Military Specification Fluids", which contain sodium ··· 25 mg sodium di- (2-ethylhexyl) sulfosuccinate.

The most important technical characteristics of an aircraft de-icing agents are as long as possible protection against re-freezing of carrier planes before departure in extreme weather conditions and good drainage of de-icing agent from run-30 and carrier platforms at the departure of the aircraft. In addition, the properties of de-icing fluids must not be impaired when stored at temperatures up to 100 ° C or when pumped and sprayed through a nozzle. Today, when thickened de-icing agents meet 35 requirements well in terms of durability, they tend to flow out of the carrier bases at a slower rate than the thickening towers. Because of their polymeric thickener, Type II de-icing agents are also substantially more sensitive to transfer and heat, requiring special technically difficult spraying devices. In contrast to these, Type I non-thickening de-icing agents are generally not sensitive to displacement and temperature and will rapidly flow away from the carrier planes upon departure. However, they have the essential disadvantage that they have only a short protection time against freezing. In the test methods described in the AEA Recommendations for Determining Duration, namely the "Water Spray Endurance Test" (which simulates freezing rain) and the "High Humidity Test" 15 (which simulates frost formation), Type I fluids only require at least 3 minutes or 20 minutes. minutes, but for Type II fluids under the same conditions for at least 30 minutes to 240 minutes.

It is therefore an object of the invention to provide an AEA Type I antifreeze agent having a simple structure and an extended service life. Thus, the new antifreeze agent must combine the advantages of Type I and Type II fluids without having their harmful properties. It must also be such that the used liquid can be regenerated in a simple way and it must be reusable.

The de-icing agent and antifreeze-30 according to the invention for aircraft based on glycols and water consists essentially of * ♦ · a) 60 to 97% by weight, preferably 80 to 95% by weight of at least one glycol of alkylene glycols having 2 to 3 carbon atoms a group of oxyalkylene glycols having an atom.

B) 0.01 to 1% by weight, preferably 0.1 to 0.5% by weight, of at least one nonionic surfactant selected from the group consisting of fatty alcohols and lower alkoxylated fatty alcohols having from 1 to 5 to 10 alkoxide units, preferably 1-8 alkoxide units, c) 0.01-0.8 weight percent, preferably 0.03 -0.5 weight percent at least one corrosion inhibitor, and d) water supplemented to 100 weight percent, wherein the weight percent is based on the weight of the material.

It was further discovered that an even longer duration of use can be achieved when a combination of the nonionic surfactant b) and the anionic surfactant b ') which is a group of alkali-limestone alkylarylsulfonates is used as the surfactant component, also in the amount of 0.01-1. by weight, preferably 0.1 to 0.5% by weight. The two surfactant components b) and b '), whereby the surfactant b') acts primarily as a spreading agent, are preferably used in a weight ratio of about 1: (0.5 to 1) and more preferably in a weight ratio of about 1: 1.

Component a) of the liquid of the invention is preferably ethylene glycol, propylene glycol (1,2-propylene glycol or 1,3-propylene glycol), diethylene glycol, dipropylene glycol or a mixture of two or more of these glycols, with propylene glycols being particularly preferred. Glycols act primarily to lower the solidification point and, in addition to water, are the main component of the liquid.

Component b) is a fatty alcohol having from 6 to 24 C atoms, preferably from 8 to 18 C atoms, an alcohol in its alkyl group or an alkoxylate thereof having from 1 to 10 molecules, preferably from 1 to 8 molecules, of a small molecule alkylene oxide in an alkoxylated fat alcohol. The low molecular weight alkylene oxide is preferably ethyleneoxy-35 di, propylene oxide or a mixture thereof, with ethylene oxide being preferred. Said alkyl group in the fatty alcohol may be straight-chain or branched, whereby the straight-chain is preferred and saturated or unsaturated with 1 to 3 double bonds. Examples include: octyl, decyl, dodecyl, isotridecyl and stearyl alcohol, in addition oleyl, coconut alkyl and tallow alkyl alcohol. Component b) may also be a mixture of said fatty alcohols and / or fatty alcohol alkoxylates, for example a fatty alcohol mixture having a C12-C10 alkyl group and a C14 alkyl group (C12 / C14 fatty alcohol).

Component b ') is preferably potassium and / or sodium alkylaryl sulfonate having one or more, preferably one or two sulfonate groups (SO3K or SO3Na groups), one or more, preferably one or two alkyl groups having 5 to 18 C atoms, preferably 12 to 18 C atoms, and one or more, preferably one or two, benzene rings. Alkali metal (potassium and / or sodium) alkylbenzene sulfonates having an alkyl group of 12 to 18 carbon atoms are preferred. Since the preparation of alkyl-20 arylsulfonates also uses mixtures of hydrocarbons as starting materials, for example, as fractions in petroleum refining, the alkyl group may also mean such mixtures. The number of carbon atoms is preferably 12 to 18 (average number 25 to 15).

Component c) comprises corrosion inhibitors such as those used in glycol and water based fluids. Suitable corrosion inhibitors include alkali metal phosphates, lower alkyl phosphates such as ethyl phosphate, dimethyl phosphate, isopropyl phosphate and the like, imidazoles. .

Component d) is water. Preferably, degassed hydrogen is used.

111548 6 The pH of the AEA Type I and Deactivation fluids should be 6.5 to 10, preferably 7 to 9. As long as the fluid of the invention does not of course have such a value, the value may be adjusted using suitable pH adjusters.

5 Usually, a basic compound must be added to the liquid. Suitable basic compounds include those from the group of alkali metal hydroxides such as NaOH and KOH, alkylamines such as butylamine, hexylamine, octylamine and isononylamine, and alkanolamines such as mono-, di- and triethanolamine. Alkali metal hydroxides are preferred.

The de-icing agent and antifreeze agent of the invention are prepared by mixing the individual (known and commercially available) components in an arbitrary order, for example in a tank equipped with a stirrer.

The de-icing agent of the invention has all the advantages of non-thickening de-icing fluids and further has a life time well above the value required for fluids of AEA type 20 silicon I. It thus combines the advantages of both non-thickened and thickened liquids. This is a surprising result. Until recently, experts have clearly begun to see a longer lifespan for those based on glycols and water. 25 for liquids can only be achieved with thickeners.

When used for de-icing and treating airplane surfaces to be treated, the de-icing agent is used as such, i.e. concentrated or diluted with water, preferably in a ratio of 1: 1. The application of de-icing agent to the surfaces to be treated can be effected by spraying using conventional equipment such as spray nozzles and the like.

The invention will be further elucidated by means of examples and comparative examples.

i Ϊ 111548 7

Example 1

The de-icing agent and anti-icing agent of the invention were prepared by mixing the following components (concentrate): · 80.00% w / w 1,2-propylene glycol 0.05% w / w benzotriazole 0.25% w / w sodium alkylbenzenesulfonate having an average number of C atoms of the alkyl group. 15 10 0.20 wt% C12 / C14 fatty alcohol ethoxylated with 2 moles ethylene oxide 0.015 wt% potassium hydroxide 19.485 wt% water.

The pH of this deicing agent is 9. The shelf life was determined by means of the "AEA Water Spray Endurance Test" (Test 1) and the "AEA High Humidity Endurance Test" (Test 2) for concentrated formulations and 1: 1 diluted formulation with water. The values are summarized in the following table: Example 1 Experiment 1 Experiment 2 Concentrated 12 min More than 180 min 50: 50 7 min More than 50 min

Comparative Example 1

Example 1 was repeated, but ethoxylated fatty alcohol was omitted. Thus, the following components were mixed: 80.00 wt% 1,2-propylene glycol 0.05 wt% benzotriazole 0.25 wt% alkylbenzenesulfonate of Example 1 * 0.015 wt% potassium hydroxide 19.685 wt% water.

The substance having a pH of 9 was tested as in Example 1: 111548 8

Comparative Experiment 1 Experiment 2 Example 1 Concentrated 5 min 25 min 50: 50 3 min 20 min 5 Example 2 The following components were mixed in this example according to the invention: 90.00 wt% diethylene glycol 0.04 wt% benzotriazole 10 0.25 wt -% of alkylbenzene sulfonate of Example 1 0.20 wt.% C12 / C14 fatty alcohol ethoxylated with 2 moles of ethylene oxide 0.015 wt.% potassium hydroxide 9.495 wt.% water.

The substance having a pH of 9 was tested as in Example 1:

Example 2 Experiment 1 Experiment 2 Concentrated 11 min Over 180 min 20 50: 50 5 min Over 60 min

Comparative Example 2

Example 2 was repeated but ethoxylated fatty alcohol was omitted. Thus, the following components were mixed: 90.00 wt% diethylene glycol 0.04 wt% benzotriazole 0.25 wt% alkylbenzene sulfonate of Example 1 0.015 wt% potassium hydroxide 9.695 wt% water.

· Substance at pH 9 was tested as in Example 1:

Comparative Experiment 1 Experiment 2 Example 2 35 Concentrated 4 min 45 min 50: 50 3 min 23 min 111548 9

Example 3

An anti-icing agent and antifreeze agent of the invention were prepared by mixing the following components: 90.00 wt% diethylene glycol 5 0.04 wt% benzotriazole 0.25 wt% alkylbenzenesulfonate of Example 1 0.40 wt% tallow fatty alcohol which is ethoxy- 8 moles of ethylene oxide 10 0.015 mass% potassium hydroxide 9.295 mass% water.

This de-icing agent has a pH of 9. It was tested only for major test 1:

Example 3 Experiment 1 15 Concentrated 16 min 50: 50 4 min

Example 4 In this example according to the invention, the following components were mixed: 90.00% by weight diethylene glycol 0.04% by weight benzotriazole 0.25% by weight alkylbenzenesulfonate of Example 1 0.40% by weight coconut fatty alcohol which is ethoxy. 25 moles of ethylene oxide 0.015 mass% potassium hydroxide 9.295 mass% water.

This de-icing agent has a pH of 9. It was tested only for the more important experiment 1: 30 Example 4 Experiment 1 Concentrated 17 m V · · 50: 50 4 m

Claims (8)

1. Defrosting agent and icing protection agent for aircraft on the basis of glycols and water, characterized in that it consists essentially of a) 60 to 97% by weight of at least one glycol from the group of alkylene glycols having 2 to 3 C atoms and oxalkylene glycols having 4 to 6 C atoms, b) 0.01 to 1% by weight of at least one non-ionic surfactant from the group of fatty alcohols and the lower alkoxylated fatty alcohols having 1 to 10 alkoxide units, c) 0.01 to 0.8% by weight of at least one corrosion inhibitor and d) water which has traveled up to 100% by weight by weight of the agent. Agent according to claim 1, characterized in that it consists essentially of a) 60 to 97% by weight of at least one glycol from the group alkylene glycols having 2 to 3 C atoms and oxalkylene glycols having 4 to 6 C atoms , b) 0.01 to 1% by weight of at least one non-ionic surfactant from the group of fatty alcohols and those low molecular weight alkoxide alkoxylated fatty alcohols of 1 to 10 alkoxide units, b1) 0.01 to 1% by weight of at least an anionic surfactant from the group of alkali metal alkylarylsulfonates, c) 0.01 to 0.8% by weight of at least one corrosion inhibitor, and d) water remaining up to 100% by weight. 3. An agent according to claim 1, characterized in that it contains components a) to d) in the amounts specified below: a) 80 to 95% by weight, b) 0.1 to 0.5% by weight, c D) water which has traveled up to 100% by weight. 4. An agent according to claim 2, characterized in that it contains components a) to d) in the amounts given below: 7. a) 80 to 95% by weight, b) 0.1 to 0.5% by weight, b ' ) 0.1 to 0.5% by weight, c) 0.03 to 0.5% by weight, and d) water remaining up to 100% by weight. 5. An agent according to claim 2 or 4, characterized in that component b1) is an anionic surfactant from the group of alkali metal alkylbenzenesulfonates having 12 to 18 C atoms in the alkyl group. Agent according to claims 1 to 5, characterized in that component b) consists of a nonionic surfactant from the group C8 to C18 fatty alcohols and C8 to C18 fatty alcohols ethoxylated with 1 to 8 ethylene oxide units. Agent according to claims 1 to 6, characterized in that component c) is a corrosion inhibitor 20 from the group of alkali metal phosphates, lower alkyl phosphates, imidazoles and triazoles. An agent according to claim 1 to 7, characterized in that it has a pH of 7 to 9.