Title: Icing inhibitor composition Technical Field The present invention relates to compositions that can be used as icing inhibitors or deicing compositions. The invention further relates to the use of deicing compositions for the preventive treatment or deicing of surfaces, in particular surfaces exposed to considerable mechanical stress, particularly surfaces on railroad parts, and the preventive treatment or deicing of outer train parts.

Background

Ice formation on outer surfaces is a serious problem in a range of industries. Ice formed on wind turbines and wind turbine blades, off-shore installations and ships is a major concern, especially in the transport sector where ice disrupts the correct functioning of various essential parts of the transport machinery. Icing on the outer parts of transport machinery thus constitutes a significant security problem as well as a considerable resource problem. Icing on the underframe parts of trains continues to cause destruction of a vast amount of train components, and the repair procedure is often complicated by the fact that it may take several hours of heat treatment before the actual repair may begin. Hence, icing on the underframe parts of trains results in many trains being out of order for longer periods of time which has huge economic impacts as well as high negative impacts on train schedules and customer satisfaction.

In addition, ice formed on outer surfaces, e.g. on the underframe parts of trains, adds tremendous weight to the train and consequently results in an excess use of energy. In order to prevent icing or to make possible the removal of ice already formed, deicing compositions may be applied to or sprayed onto the outer parts of e.g. trains. It is known from literature that such compositions may be based on e.g. potassium formate.

The already known formate-based icing inhibitors are, however, problematic.

Formate-based icing inhibitors or deicing compositions cause corrosion and tear of the metal surfaces on which the compositions are sprayed, especially when applied to the underframe parts of trains. This poses a huge problem as the correct function of these components is a considerable security concern to the train sector. In order to remedy this disadvantage, corrosion inhibitors are often added to the compositions. Formate-based compositions used as deicing compositions are thus known in general and it is also known that such deicing compositions may contain corrosion inhibitors. For example, the commercially available deicing composition Aviform L 50 is composed of potassium formate, corrosion inhibitors and water.

However, known deicing compositions containing corrosion inhibitors do not give satisfactory results when e.g. applied to the underframe parts of trains. This is, among other factors, due to the fact that the underframe parts are composed of a variety of different materials. Among these component materials are several types of metal but also rubber, plastic, cables, grease etc. Thus, there is a need in the art for deicing compositions being less corrosive and aggressive towards several types of material, in particular when applying such compositions to the underframe parts of trains.

Another problem with the known formate-based deicing compositions is that they do not stick to the surfaces to which they are applied. By way of example, Aviform L 50 vanishes rapidly at wind speeds of above 50 km/t, and this composition is thus suited for application in the aviation industry, but problematic in almost any other industry. In other industry sectors, a stress-resistant deicing composition with a long-lasting effect would be highly preferred. Formate-based deicing compositions have therefore not been used in practice on train parts.

Known deicing compositions are also problematic when used e.g. on areas exposed to mechanical stress.

In practice, deicing treatment of transport machinery, and particularly of trains, is currently performed using compositions based on propylene glycol, also called 1, 2- propanediol or propane-1, 2-diol, an agent which is not aggressive towards a range of materials. An example of such a deicing composition is known as TDIce from Kilfrost.

However, the currently used propylene glycol deicing inhibitors are problematic in several ways. The currently used propylene glycol deicing inhibitors must be applied 3-4 times at a temperature of 40-60 °C to provide a suitable coverage of the transport machinery. Apart from being time-consuming and costly, this application procedure requires suitable equipment and can only be applied to the underframe parts of trains at stationary facilities. There is thus a need in the art for compositions that can be applied at very low temperature (-40 to 0°C) as well as at low or moderate temperatures (0 to 40 °C) , and which preferably require only one application procedure.

Further, currently used propylene glycol deicing inhibitors (TDIce) are problematic in that they have been shown to be rapidly (momentaneously) and completely removed from transport machinery moving at speeds of above 120 km/hour. Thus, these deicing compositions must be re-applied frequently to high-speed trains, e.g. after each time the train reaches its final destination. There is thus a need in the art for compositions that can resist mechanical stress and wind speeds of above 120 km/hour.

Further, the propylene glycol deicing inhibitors have been shown to vanish within 3-5 days even from transport machinery which is not in motion. Thus, as a general rule, the currently used propylene glycol deicing inhibitors must, in the winter season, be re-applied every time the train reaches its final destination, and be applied at least every 5 days as a preventive treatment when operating in weather conditions where temperatures below 0°C are contemplated in the near future. This has tremendous implications e.g. for the planning of deicing and preventive deicing treatments especially in the train sector. There is thus a need in the art for compositions that have a long-lasting effect and stay effectively on the machinery for more than 5 days.

Further, the currently used propylene glycol deicing compositions are not sufficiently biodegradable, and national legislation in several countries prescribe that spill of propylene glycol deicing compositions during application must be recollected and discharged at suitable facilities. Thus, there is also a need in the art for compositions that minimize the amount of spill when applied, especially to the underframe parts of trains.

Further, propylene glycol deicing compositions cannot be discharged directly into the public sewer system. This has the further implications that the application of the propylene glycol deicing inhibitors must be performed at stationary facilities specifically designed for deicing purposes. There is thus a need in the art for compositions which are sufficiently biodegradable for safe discharge directly into the environment, whereby application can be performed at non-stationary sites. An optimal long-lasting deicing composition for use in the preventive and deicing treatment of surfaces exposed to mechanical and wind induced stress, such as surfaces in transport machinery, in particular the underframe parts of trains, should thus fulfill the following criteria:

^■ Can be used on transport machinery at low temperatures and have a long- lasting effect (preferably more than 5 days) .

^■ Is resistant to mechanical stress and wind-generated stress (preferably resistant to wind speeds of more than 120 km/hour) .

^■ Is non-corrosive or provides only a minimal corrosive effect on a number of different material types known to be present in the underframe parts of trains. Moreover, the composition should preferably also be resistant to storage, i. e. resistant to degradation or separation caused by precipitation of individual components of the composition. This is important as large amounts of the composition must be stored and be ready for rapid application based e.g. on weather forecasts. In addition, the composition should preferably also be able to be used on transport machinery at any location, i. e. the composition should be bio-degradable and applicable at low or moderately low temperatures. Further, preferred compositions should be applicable with a minimal amount of spill, which is a major problem with current glycol-based deicing compositions.

Finally, a deicing composition applied to the underframe parts of trains by e.g. automative spray application will also be applied to the free surfaces of break parts. Thus, these compositions must be removable by e.g. safety break blockage procedures routinely performed after any underframe treatment procedure. Hence, in general, there is a demand for new and improved deicing compositions and icing inhibiting compositions, including in particular compositions resistant to wear and mechanical stress while still providing sufficient deicing and protection against further icing and providing a sufficient corrosion protection while also being applicable as deicing compositions.

Summary of the invention It is an object of the invention to provide an icing inhibitor or deicing composition which is long-lasting and which can be used on areas exposed to significant stress, e.g. in the form of mechanical stress or in the form of wind-induced stress.

It is a further object of the invention to provide an icing inhibitor or deicing composition with improved corrosion-inhibiting properties.

It is a further object of the invention to provide an icing inhibitor or deicing composition with improved icing-inhibiting properties, particularly on a number of different surfaces.

It is a further an object of the invention to provide an icing-inhibiting composition or deicing composition with improved deicing properties, particularly on the underframe surfaces of trains. It is a further object of the invention to provide an icing inhibitor or deicing composition which is bio-degradable and applicable at low or moderately low temperatures.

It is a further object of the invention to provide an icing inhibitor or deicing composition which minimizes the amount of spill during application.

It is a further object of the invention to provide an icing inhibitor or deicing composition that will stay effectively on the machinery for more than five days.

It is a further object of the invention to provide an icing inhibitor or deicing composition that can be applied to transport machinery and that have a long-lasting effect (preferably more than five days) . It is a further object of the invention to provide an icing inhibitor or deicing composition that is resistant to storage-induced degradation or separation caused by the precipitation of individual components of the composition.

Detailed description of the Invention

It has now surprisingly been shown that a formate-based deicing composition fulfilling the above objects of the invention could be produced by adding a thickener to a formate-based solution and further adding corrosion inhibitors in a suitable solvent to the formate solution.

Thus, the present invention provides a deicing composition comprising a formate, a thickener, one or more corrosion inhibitors, a corrosion inhibitor solvent and water.

Formate (IUPAC name: methanoate) is the anion derived from formic acid. Its formula is represented in various equivalent ways: CHOO- or HCOO- or HC02- . It is the product of deprotonation of formic acid. A formate (compound) is a salt or ester of formic acid.

The present invention thus provides a deicing composition and an icing-inhibiting composition, said composition being more long-lasting and resistant against e.g. wear and mechanical stress than hitherto known compositions and providing an improved deicing and protection against further icing, said composition providing an improved corrosion protection while also being applicable as a deicing composition.

It was surprisingly observed that improved characteristics of the deicing composition, in particular in terms of long-lasting corrosion inhibition and in terms of storage properties, were achieved by adding a corrosion inhibitor solubilised in a suitable solvent to a formate-based composition.

Preferably, the corrosion inhibitor solvent is selected from the group comprising triethylamine, glycols and glycol acetates.

According to a highly preferred aspect of the present invention, a formate-based deicing composition is thus provided, said composition being characterised by containing one or more thickeners, and one or more corrosion inhibitors, where the corrosion inhibitors are solubilised in a suitable triethylamine- , or glycol- or glycolacetate-based solvent prior to addition to the formate composition. The addition of the hydrocolloid thickener and the particular solubilised corrosion inhibitors has surprisingly turned out to give the product a number of advantageous properties, and the product has thus turned out to be markedly superior to corresponding deicing compositions currently used. Without wishing to be limited thereto, it is believed that the advantageous properties of the formulation according to the invention may be ascribed in part to the presence of the hydrocolloid thickener which possibly increases the tixotrophic properties of the composition, and in part to the particular corrosion inhibitors which, when present in a homogeneous mixture, have been shown to provide a longer lasting deicing effect and less corrosive effect when applied to the nderframe parts of trains.

The deicing composition according to the invention is thus based on a solution of a formate in water. Preferably the formate is a salt. Preferred formate salts according to the invention are calciumformate, sodiumformate or potassiumformate. Potassium formate is the most preferred formate applied in the present invention.

The deicing composition according to the invention is thus preferably based on a solution of potassium formate in water.

Unless otherwise stated, all percentage indications described herein will be based on per cent by weight of the total composition. In case the stated percentages in total do not add up to 100% of the total composition, it is to be understood that water preferably constitutes the rest.

Preferably, the composition comprises between 40 - 90% formate. It is preferred that the compositions according to the invention contain 41 - 80% formate, such as 42 - 70% formate or such as 45 - 60% formate. Even more preferred is the range between 47 - 52% formate. In the most preferred embodiment, the compositions according to the invention contain approx. 50% potassium formate.

It is preferred that the compositions according to the invention further contain 0.01 - 30% of a thickener. Preferred thickeners are hydrocolloid thickeners or other agents enhancing the tixotrophic properties of the product. Such thickeners may e.g. constitute or be based on plant pulp, cellulose, polyurethane, alginate, carrageenan, cellulose gum, carob pure wheat flour, micro crystalline cellulose (MCC) , pectin, xanthane gum or the like. Guar gum has, however, turned out to be best suited as thickener according to the invention.

A particularly preferred hydrocolloid thickener is thus guar gum or guaran. The addition of thickener is essential in order to provide the desired properties of the deicing composition. Further, it was found that the amount of thickener was important for the contemplated application method and the desired properties of the resulting compositions. Thus, for application as a spray, the suitable amount of thickener was observed to be less than 5% and preferably less than 3%.

For application as paint, the suitable amount of thickener was observed to be less than 8% and preferably less than 6%.

For application as a paste, the most suitable amount of thickener was observed to be between 5 and 30% and preferably between 8 and 30%.

When used as a deicing composition for underframe parts of trains, it is for practical reasons preferred to apply the composition as a spray or as paint. Most preferred is the application as a spray.

Application as a paste is preferred for application on surfaces on which a very long- lasting effect is desired and where the ease of application is of less importance compared to the desired long-lasting effect.

Thus, in preferred embodiments of the invention, the compositions contain 0.01 - 30% thickener, such as 0.01 - 8% thickener or such as 0.1 - 7% thickener or such as 0.1 - 6% thickener or such as 0.1 - 5% thickener or such as 0.1 - 4% thickener or such as 0.2 - 5% thickener or such as 0.3 - 4% thickener or such as 0.3 - 2% thickener.

In another preferred embodiment of the invention, the compositions contain 0.01— 30% thickener, such as 1 - 8% thickener or such as 2 - 8% thickener or such as 3 - 8% thickener or such as 4 - 8% thickener or such as 5 - 8% thickener or such as 5 - 7% thickener.

In another preferred embodiment of the invention, the compositions contain 5 - 30% thickener, such as 8 - 30% thickener or such as 10 - 30% thickener or such as 8 - 25% thickener or such as 8— 20% thickener.

The compositions according to the invention further preferably contain 0.01 - 5% of one or more corrosion inhibitors, such as 0.05 — 4% of one or more corrosion inhibitors or such as 0.1— 3.5% of one or more corrosion inhibitors. Even more preferred is the range between 0.2 - 3% of one or more corrosion inhibitors.

Corrosion inhibitors that can be used according to the invention comprise in principle a number of various corrosion inhibitors, including corrosion inhibitors based on 2-butan-l, 4-diol, polyether phosphate, alkanolamine salts of nitrogen- containing organic acids, propargyl alcohol alkoxylate, alkylphosphate, polyether phosphate or oleoyl sarcosine acid or mixtures thereof.

Applicable corrosion inhibitors are known e.g. under the trademark Korantin®. In one embodiment, the composition contains a corrosion inhibitor which is based on and contains 2-butan-l ,4-diol. Such corrosion inhibitors are e.g. Korantin® BH Solid or Korantin® BH 50 which contains 2-butan-l, 4-diol.

In another embodiment, the composition contains a corrosion inhibitor which is based on and contains polyether phosphate, such as e.g. Korantin® LUB which contains polyether phosphate.

In a preferred embodiment, the composition contains a corrosion inhibitor which is based on and contains an alkanolamine salt of a nitrogen- containing organic acid. An example thereof is Korantin® MAT or Korantin® PAT which contains an alkanolamine salt of a nitrogen-containing organic acid.

In another preferred embodiment, the composition contains a corrosion inhibitor which is based on and contains propargyl alcohol alkoxylate, such as e.g. Korantin® PM and Korantin PP which contain propargyl alcohol alkoxylate.

In another preferred embodiment, the composition contains a corrosion inhibitor which is based on and contains an alkyl phosphate, such as e.g. Korantin® SMK which contains alkyl phosphate. When this corrosion inhibitor is applied, it should preferably first be solubilised in triethylamine.

In another embodiment, the composition contains a corrosion inhibitor which is based on and contains oleoyl sarcosine acid, such as e.g. Korantin® TC- SH which contains oleoyl sarcosine acid.

The most preferred corrosion inhibitors are selected among a group consisting of corrosion inhibitors containing an alkyl phosphate, inhibitors containing an alkanolamine salt of a nitrogen-containing organic acid and inhibitors containing an propargyl alcohol alkoxylate. Preferably the corrosion inhibitors comprise a mixture of two of the above corrosion inhibitors, even more preferably a mixture of all of the above preferred corrosion inhibitors.

In a highly preferred aspect of the invention, the deicing compositions comprise a combination of corrosion inhibitors. For application on the underframe part of trains, it was surprisingly observed that a combination of the corrosion inhibitors Korantin® SMK, Korantin® PAT and Korantin® PP resulted in a remarkable corrosion inhibiting effect on a number of surface parts present on the underframe part of trains. The test results in this respect can be seen in the examples (table 2) .

Thus, in a highly preferred aspect of the invention the deicing compositions comprise a combination of corrosion inhibitors based on Korantin® SMK, Korantin® PAT and Korantin®PP.

As stated previously, it was observed that the effect of the compositions was markedly improved by adding the corrosion inhibitors to the formate solution after the corrosion inhibitors have been solubilised in a suitable solvent. Thus, in a highly preferred aspect, the invention provides a method of producing a deicing composition wherein the composition is produced by adding a solution comprising one or more corrosion inhibitors to a solution containing a formate as well as deicing compositions obtainable by that process.

A preferred embodiment is a deicing composition, said composition containing 40- 90% formate salt, preferably potassium formate, 0.01-30% of a thickener, preferably guar gum, 0.01 - 5% of one or more corrosion inhibitor, and 0.01 - 10% of a corrosion inhibitor solvent, the rest mainly being water.

Other components such as for example clearing agents may also be present. Lugalvan BPC 48 (Benzylpyridine-3-carboxylate) is a suitable clearing agent.

The inventive deicing composition according to the invention was further shown to have a markedly increased shelf-life depending on the method of manufacture of the composition. Thus, it was observed to be important that the ingredients were mixed thoroughly to provide the most homogeneous composition possible.

This homogeneous composition is preferably achieved by mixing potassium formate, water and hydrocolloid thickener in one composition, and mixing the corrosion inhibitors and corrosion inhibitor solvent in another separate composition, each composition being mixed until a homogeneous mixture is achieved. Thereafter, the two compositions are combined in a suitable ratio and mixed until a homogeneous deicing composition is obtained. Most preferred corrosion inhibitor solvents according to the invention are selected from the group comprising trietylamine, glycols and glycol acetates or mixtures thereof. The most preferred corrosion inhibitor solvent is a propylenglycol, preferably monopropylenglycol. The invention also relates to a method of producing a deicing composition containing water, formate, a thickener, one or more corrosion inhibitors, and one or more corrosion inhibitor solvents, the method comprising the steps of a) providing a homogeneous solution of a formate salt, water and a thickener, b) providing a homogeneous solution of one or more corrosion inhibitors in one or more suitable solvents, c) adding the solubilised corrosion inhibitors to the formate solution of step a) under agitation until a homogeneous transparent composition is produced, as well as to the products obtainable by that method.

In order to provide improved shelf-life, it was observed that the compositions comprising potassium formate and the above composition comprising corrosion inhibitors should preferably be stored as a kit of parts and mixed prior to use as a deicing composition.

Thus the invention also relates to a kit of parts comprising a) a solution of a formate salt, water and a thickener, and b) a solution comprising one or more corrosion inhibitors solubilised in a suitable solvent.

The inventive composition of the present invention can in principle be used for the deicing or preventive deicing treatment of any surface. The composition is, however, especially suited for the treatment of surfaces exposed to wind-induced stress of more than 50 km/hour.

It is further especially suited for use in the treatment of underframe parts of trains, railway points, off-shore installations, wind turbine blades and ships.

In a highly preferred aspect of the invention, the inventive compositions are used for the deicing or preventive deicing treatment of the underframe parts of trains. Example 1

An ice-inhibiting composition containing the ingredients listed in Table 1 below was prepared by the following procedure: A composition (" C omposition 1 ") was produced by adding guar gum (0.5% final concentration) to a solution of 50% potassium formate in water (98.5% of the composition giving a final concentration of potassium formate of approx. 50%) . C omposition 1 was kept under constant agitation for 4 hours until complete dissolution (transparent composition) .

Separately, another composition (" C omposition 2") comprising one part by weight of korantin SMK (Alkyl phosphate based corrosion inhibitor) and four parts by weight of triethanolamin was prepared. Then, yet another composition ("Composition 3") comprising two parts by weight of Composition 2 above, five parts of monopropylene glycol, 0.5 part by weight of korantin PP (Alkyl phosphate based corrosion inhibitor) , one part by weight of korantin PAT (Alkyl phosphate based corrosion inhibitor) and two parts by weight of L galvan BPC 48 was prepared.

Composition 3 (approximately one part by weight) was added to Composition 1 (approximately 99 parts by weight) under agitation for 1 hour until a transparent composition was obtained. It was controlled that the pH was below 9.

Hence, the final homogeneous and transparent deicing composition had the following composition:

Tabel 1. The contents of the final composition in % by weight.

The composition according to Example 1 is biodegradable and may be applied to transport machinery at temperatures of between -40°C to 40°C . Surprisingly, it was observed that the provision of a homogeneous final deicing composition was best achieved by the separate preparation of compositions comprising corrosion inhibitors (Composition 3) and the bulk potassium formate composition (Composition 1) and that rapid agitation was required in order to fully obtain the desired properties of the final deicing composition.

Further it was observed that long-term storage of the composition was best done by keeping Composition 1 and Composition 3 apart until just prior to usage as a kit of parts, thereby preventing the formation of precipitates.

Example 2

Corrosion tests on different materials provided by Mediator A/S, Centervej 2, DK- 6000 Kolding, Denmark.

The compatibility of the composition provided in Example 1 with several material types known to be present on the underframe surface of trains was tested with the following results. A = excellent, B = Good - minor corrosion or discolouring, C = acceptable— moderate effect, not recommended for continuous use. No other deicing composition known to the applicant or to DSB Danish Rails has passed this test without any "C" results.

Table 2

Material C compatibility

Stainless steel B

ABC plastic A

Acetal B

Aluminium A

Bronze B

Buna N A Material C compatibility

Carbon steel B

Carpenter B

Cast iron B

Ceramic A

Chem raz A

Copper A

CPVC B

EPDM B

Epoxy A

Fluor carbon A

Hastelloy-cr B

Hypalonr A

Kalrez A

LPDE A

Natural rubber A

Neoprene A

Polycarbonate B

Polypropylene A

PTFE B

PVC A

Silicone A

Titanium B

Viton B

It was concluded that applying the composition to common surfaces on the underframe parts of trains was exceptionally suitable in terms of corrosive effect. Several different compositions were tested and it was observed that the corrosion inhibitor listed in Example 1 was the most suitable. Further, it was observed that the manufacturing process of the composition according to the invention was of considerable importance, i. e. it was essential that a homogeneous final composition was produced. It was observed that improvements in terms of providing the most homogeneous and long-lasting composition) were achieved by adding corrosion inhibitors to suitable solvents prior to adding the formate solution. It was further observed that the storage shelf-life of the composition could be markedly increased by storing the formate solution and the corrosion inhibitor solution separately.

Example 3

The composition of Example 1 was compared to known ice-inhibiting compositions and was found to have a number of advantageous properties.

As a first test, it was found that the composition of Example 1 possessed excellent properties as a deicing composition. The composition of Example 1 was observed to have a deicing capacity of 1.8 g ice/1 g composition.

Further, the composition of Example 1 was tested in a test setup provided by DSB Danish Rails. The composition of Example 1 was applied by spray to the underframe part of a single carrier wagon of an entire train set operated for 10 days under winter conditions. After application, the break system of the train was tested by accelerating the train to 25 km/hour followed by applying the emergency break (as required by security procedures) . It was observed that it was necessary to apply two additional emergency break procedures in order to remove the composition of Example 1 compared to the usual number of break procedures necessary to remove conventional propylene-glycol based compositions from the break systems. The results demonstrate that the composition of Example 1 is more resistant to mechanical stress than conventional deicing compositions, but that it is possible to remove it from break parts by conventionally controlled emergency break procedures. After 10 days of operation, it was observed that the nderframe part of the carrier wagon containing the deicing composition according to the invention was practically free of ice, while other wagons contained heavy ice coverage (up to one ton ice per wagon) .

It was further observed that the composition was present and effective on the underframe part of the carrier for at least 21 days. Example 4

Wind resistance test (test nr. 111-34622/revA) performed at Force Technologies facilities in Lyngby, Denmark. The composition of Example 1 was sprayed onto the surface of a smooth aluminium plate. After spray application, the plate was tested in a wind tunnel at a temperature of up to 42°C and at a wind speed of 248 km/hour for 10 minutes. These conditions (high temperature, high wind speed, blank surface) are considered extreme in terms of removing the composition from the surface. At these conditions, conventional propylene-glycol based compositions vanish momentarily from the aluminium plate.

After 10 minutes of wind treatment, the aluminium plates were removed and examined. The plates were still completely covered with deicing composition according to the invention.