WO2009122265A1

WO2009122265A1 - Improved anti-icing composition

Info

Publication number: WO2009122265A1
Application number: PCT/IB2009/005141
Authority: WO
Inventors: Fernando H. Garcia; Maria Fernanda Garcia
Original assignee: La Perla Srl
Priority date: 2008-03-31
Filing date: 2009-03-31
Publication date: 2009-10-08
Also published as: WO2009122228A1

Abstract

An anti-icing composition adapted to prevent ice layers from forming on surfaces where vehicles travel and/or pedestrian walk, such as roads, highways, pavements, airport runways, and the like, and to melt ice layers formed on said surfaces. The composition comprises preferably a first additive, which is a polyhydroxylated compound with at least two hydroxyl groups, such as glycerine, to reduce slipperiness of treated surfaces, and a second additive which is an hydroxyethilamine, in particular commercial or pure triethanolamine, i.e. tris(2-hydroxyethyl)-amine (TEA), to reduce composition corrosiveness. The additive weight percentage of both additive is set between 1 % and 20%, in particular between 2 and 5%, most preferably bout 3%.

Description

TITLE

IMPROVED ANTI-ICING COMPOSITION DESCRIPTION

Field of the invention The present invention relates to a composition for preventing ice from forming (anti-icing), or removing a layer of already formed ice (de-icing), for use on surfaces of different type, in particular, surfaces for transit of vehicles, or pedestrians, such as roads, airport runways, pavements, and the like.

Description of the prior art As well known, the method traditionally used for preventing, or removing, the production of ice from roads, pavements, airport runways, etc. provides solid salt, usually sodium chloride, calcium chloride or magnesium chloride.

The process through which salt lowers the freezing point of water comprises, in summary, the dissociation of the molecules of salt into ions and their electrostatic bonding to the water molecules. When the temperature drops below 0°C, water exhibits the first ice crystals, which, however, cannot grow due to the presence of salt ions.

Furthermore, the substances conventionally used as a surface antifreeze have a high environmental impact. In fact, once dissolved the salts are adsorbed by the ground and can then reach the roots of plants jeopardizing the absorption of water.

The above described compositions are very aggressive to metal and concrete materials due mainly to their acidity. This can cause serious corrosion attack to part of vehicles that use the roads, highways and the like, where salt has been scattered.

In particular, sodium chloride is preferred with respect to calcium chloride for its lower cost and its easier availability. The use of calcium chloride is, furthermore, limited to dissolve the ice already formed, since on a dry road such salt tends to form a slippery layer. However, sodium chloride can be used only for extremely or quite low temperatures. Moreover, beside being corrosive, calcium chloride can lead to serious environmental problems when used in large amounts. Organic substances are also known that are commonly used as anti-icing agents, such as potassium acetate, sodium acetate, ammonium phosphate, ammonium nitrate, low molecular weight alcohols, and urea. However, also these substances have a high environmental impact. In particular, low molecular weight alcohols easily volatilize and, even if they are not particularly hazardous for the soil, they can be an atmospheric pollutant.

A general drawback of the anti-icing agents, furthermore, is their capacity of forming a slippery patina on treated surfaces, in particular on road surfaces, in such a way that they reduce their positive anti-icing or de-icing capabilities. Another type of anti-icing composition for surfaces is described in

WO2007113658, in the name of the same applicant. This composition solves different drawbacks of the above described compositions of prior art.

In particular, the composition described is effective also in conditions of very cold temperatures and has a low environmental impact. However, also this anti-icing composition, like the similar above- mentioned products, has the disadvantage of making the treated surface very slippery.

In particular, a parameter for measuring surface slipperiness is the slipperiness coefficient. In general, the lower is the friction coefficient of a surface, the higher is the slipperiness coefficient of that surface.

A surface which has a high slipperiness coefficient causes relevant disadvantages. For example, in case of tarred surfaces, such as roads, airport runways, etc., a high slipperiness coefficient affects the adherence of the vehicles. Even the safety of the pedestrians who walk on a portion of a road, or of a pavement, which has a high slipperiness coefficient, can be seriously endangered.

Therefore, the compositions of the prior art, which is used for preventing layers of ice from forming on a surface, or for melting ice which has already formed on a surface, are not suitable for use on surfaces where vehicles travel, or where pedestrians walk.

Summary of the invention

It is therefore a feature of the invention to provide an anti-icing composition that is suitable to melt an ice layer formed on surfaces, such as roads, pavements, airport runways, etc., or for preventing ice from forming on such surfaces,, which does not appreciably cause slipperiness of treated surface treated with the composition.

It is another feature of the invention to provide such an anti-icing composition, which is substantially not corrosive with respect to materials that are commonly used to make motor vehicle bodies, chassis, and other exposed parts, as well as motorcycle body parts and motors.

It is still a feature of the present invention to provide such a composition which is not aggressive towards asphalt concrete and other materials used for building highways, roads, airport runways, pavements, and the like.

It is also a feature of the invention to provide such an anti-icing composition that is adapted to overcome the other drawbacks of the compositions of the prior art.

These and other features are accomplished with one exemplary anti-icing composition that is applicable on surfaces of different type, in particular, surfaces for vehicles, or pedestrians, for preventing ice from forming, or dissolving ice already formed, the composition comprising an anti-icing solution and a first additive that is mixed to the anti-icing solution in a predetermined weight percentage, the first additive containing a polyhydroxylated compound, i.e. a compound which has at least two hydroxyl groups -OH, such that the first additive is adapted to reduce slipperiness of the anti-icing composition. The main feature of the anti-icing composition is that it further comprises a second additive that is mixed to the anti-icing solution in a predetermined weight percentage, the second additive containing a hydroxyalkilamine, such that the second additive is adapted to reduce corrosiveness of the anti-icing composition.

The polyhydroxylated compound increases the solvation of the anti-icing composition. This way, a production is avoided of gelatinoid compounds that cause slipperiness as observed on the surfaces treated with the products of the prior art.

In particular, the second additive is selected from the group comprised of a secondary hydroxyalkilamine, a tertiary hydroxyalkilamine or a mixture thereof.

Advantageously, the second additive comprises at least a - A - hydroxyethylamines, in particular a β-hydroxyethylamines.

Said β-hydroxyethylamines of the second additive preferably comprise at least 60 weight percent of triethanolamine, i.e. tris(2-hydroxyethyl)-amine, i.e. TEA. Advantageously, the second additive comprises at least 80 weight percent of TEA.

Advantageously, the polyhydroxylated compound to mix to the anti-icing solution is selected from the group comprised of glycerol, mannitol, sorbitol, lactulose, xylitol, levulose, sucrose, glucose, or a combination thereof.

Preferably, the weight percentage of the first additive in the final anti-icing composition is set between 1% and 20%, in particular this weight percentage is set between 2% and 15%. Preferably, the weight percentage of. the first additive in the final anti-icing composition is set between between 2% and 12%, most preferably between 2% and 12%, advantageously between 2,7% and 3,3%. Preferably, the weight percentage of the second additive in the final anti- icing composition is set between 1 % and 20%, in particular this weight percentage is set between 2% and 15%. Preferably, the weight percentage of the second additive in the final anti-icing composition is set between between 2% and 12%, most preferably between 2% and 12%, advantageously between 2,7% and 3,3%.

Advantageously, between the weight percentage of the first additive and the weight percentage of the second additive is set between 0,5 and 1 ,5, preferably the ratio is set between 0,8 and 1 ,2.

In particular, a synergistic effect of an ethanolamine like TEA, and glycerine, to reduce slipperiness, is particularly important at relatively low TEA and glycerine percentage, with substantially equivalent amounts of TEA and glycerine. Preferably, said first additive is Glycerine and the second additive is TEA, and the weight percentage of both additives in the final anti-icing composition is substantially equal to 3%. Amounts of TEA and Glycerine both equal to about 3% are to be preferred, since they appears to maximize the synergistic effect of the two additives to reduce the slipperiness of the anti- icing solution.

In particular the aqueous solution has a pH set between 7.2 and 9.5, in particular the pH is set between 7,5 and 9. Although an alkaline environment helps to control composition corrosiveness, the pH should be low enough to avoid basic Chlorides precipitation, which would lower anti-icing effectiveness. In particular, the anti-icing solution has an alkaline pH, and comprises at least one of the following dissolved ions: Bromide (Br^"), Bicarbonate (HCO^3'), Borate (BO₃ ^3"), Silicate (SiO^3"), Fluoride (F), Iodine (I ).

Advantageously, the or each ion species of the aqueous solution having an alkaline pH has the following concentration:

- Bromide ions(Br ): set between 10 mg/l and 500 mg/l;

- Bicarbonate ions(HCO₃ ): set between 0.1 mg/l and 500 mg/l. - Borate ions(BO₃ ^3"): set between 10 mg/l and 200 mg/l;

- Silicate ions(SiO³ ): set between 0,01 mg/l and 5 mg/l;

- Fluoride ions(F ): set between 0,01 mg/l and 5 mg/l; Iodine ions(l^"): set between 0,01 mg/l and 5 mg/l.

Furthermore, the aqueous solution having an alkaline pH can comprise the, or each, of the following ions in the indicated concentration:

- Cl^" ions: set between 15000 mg/l and 30000 mg/l;

- Na⁺ ions: set between 5000 mg/l and 20000 mg/l;

- SO₄ ^2" ions: set between 1000 mg/l and 5000 mg/l;

- Mg²⁺ ions: set between 500 mg/l and 3000 mg/l; - Ca²⁺ ions: set between 100 mg/l and 1000 mg/l;

- K⁺ ions: set between 100 mg/l and 1000 mg/l.

Advantageously, the anti-icing solution comprises at least one metal chloride.

In particular, the chloride is an alkaline metal chloride or an alkaline earth metal chloride.

Advantageously, the or each chloride is selected from the group comprised of calcium chloride, magnesium chloride, sodium chloride, potassium chloride, lithium chloride, a combination of calcium chloride and magnesium chloride, another combination thereof. The anti-icing composition can provide: calcium chloride: in an amount set between 5% and 50% by weight;

- magnesium chloride: in an amount set between 5% and 50% by weight;

- aqueous solution having alkaline pH: in an amount set between 50% and 95% by weight. Advantageously, the anti-icing composition provides:

- calcium chloride, in an amount set between 10% and 40% by weight;

- magnesium chloride, in an amount set between 5% and 40% by weight; aqueous solution having alkaline pH, in an amount set between 50% and 80% by weight.

Preferably, the anti-icing composition provides:

- calcium chloride, in an amount set between 25% and 35% by weight; magnesium chloride, in an amount set between 5% and 15% by weight;

- aqueous solution having alkaline pH, in an amount set between 55% and 65% by weight.

In particular, the aqueous solution can be obtained from seawater.

The above mentioned features are still accomplished by an anti-icing composition applicable on surfaces of different type, in particular, surfaces for vehicles, or pedestrians, for preventing ice from forming, or for dissolving ice already formed, the composition comprising:

- an anti-icing solution;

- an additive that is mixed to the anti-icing solution in a predetermined weight percentage, the additive being a polyhydroxylated compound, i.e. a compound which has at least two hydroxyl groups -OH, whereby the additive is adapted to reduce slipperiness of the anti-icing composition;

- at least one metal chloride, said anti-icing composition comprising also an aqueous solution having an alkaline pH in which at least one of the following ions is dissolved: Bromide (Br^"), Bicarbonate (HCO^3"), Borate (BO₃ ^3"), Silicate (SiO^3"), Fluoride (F^"), Iodine (I ). The above mentioned features are still accomplished by an anti-icing composition applicable on surfaces of different type, in particular, surfaces for vehicles, or pedestrians, for preventing ice from forming, or for dissolving ice already formed, the composition comprising:

- an anti-icing solution; - an additive that is mixed to the anti-icing solution in a predetermined weight percentage, the additive being a polyhydroxylated compound, i.e. a compound that has at least two hydroxyl groups -OH, such that the additive is adapted to reduce slipperiness of the anti-icing composition;

- at least one metal chloride; wherein the additive is selected from the group comprised of: mannitol, sorbitol, lactulose, xylitol, levulose, sucrose, glucose, a secondary hydroxyalkil amine, a tertiary hydroxyalkilamine, in particular a triethanolamine, a combination thereof.

Each of the last two above defined anti-icing solutions can comprise an additive as previously described.

The above-mentioned metal chlorides, are strong electrolytes. Therefore, in an aqueous solution they dissociate completely into metal ions; in the cases of calcium chloride and magnesium chloride, they dissociate into Ca²⁺ and Cl^', and Mg²⁺ and Cl^", respectively. In an aqueous solution, these ions are surrounded by the weak electrolytes having an opposite charge, such as bromide ions and bicarbonate ions, that provide the so-called "shield" effect according to the Debye-Hϋckel theory. The "shield" effect of the weak electrolytes increases, in particular, the distance between calcium ions (Ca²⁺) and chloride ions (Cl^") on the one hand, and between magnesium ions (Mg²⁺) and chloride ions (Cl^") on the other hand. Therefore, in accordance with the Coulomb's law, the electrostatic force between the ions is reduced, therefore these ions remain in solution also at temperatures lower than respective crystallization temperatures.

Examples

Tables I and Il shows a comparison between prior art anti-icing composition A (as taught in WO2007113658), and a first group of anti-icing compositions B,C,D;E, according to the invention obtained by adding various amounts of glycerol.

TABLE I

The slipperiness coefficient of plates of concrete treated were studied, to investigate the effect of glycerine. To reproduce a real situation, concrete plates with an irregular surface were used. The upper surface of the concrete plate were wetted with a known volume (66 ml) of each compositions A-E of table I. Then, the slipperiness coefficient of the treated surface was evaluated by computing the static friction coefficient μ₀. This was found by positioning on the treated surface a prismatic shaped body P, the weight of which was 384.20 g, and which was connected to a container filled of sand.

The static friction coefficient (μ₀), defined as the minimum force that is necessary to displace the body, was then evaluated through the well-known equation: F = F_p*μ₀, where F_p is the weight force applied by the body P on the treated concrete surface, and F was the component, perpendicular to the surface, of resultant forces globally acting on the body.

After testing a compositions, the plate of concrete was abundantly washed with water and completely dried in a stove at 105⁰C. Then the plate was cooled up to ambient temperature T_am_b, before applying another composition of table I.

The results are shown in table II, together with a dry friction coefficient which was evaluated, in conditions of dry surface and after wetting the surface with distilled water and with each compositions A-E.

TABLE Il

Higher values (μ_o=0.508) of the static friction coefficient were detected in dry surface conditions. This value is slightly decreased (μ_o=0.440) after wetting the plate of concrete with distilled water, and then was drastically reduced (μ_o=0.251 ) after treating the surface of the concrete plate with the composition A according to the prior art. This confirms that such composition is therefore not well suited for treating surfaces where vehicles travel and/or where pedestrians walk.

The value of the friction coefficient was measured, after the application of the composition with (containing?) salt, and a value of 0.434 was obtained if the surface was treated with composition B, according to the invention. This shows that, even at a very low amount (1% in weight), the additive has a strong positive effect on slipperiness; in particular, a slipperiness coefficient is obtained which is comparable to water treated surfaces coefficient, and is therefore about 85% of the dry slipperiness coefficient.

These effects are further enhanced by increasing the ratio of the additive in the anti-icing composition. The friction coefficient increases up to 0.437 in case of composition C (2% Glycerol), to 0.450 in case of composition D (4% Glycerol), to 0.455 for composition E (10% Glycerol). The latter two values were even higher than the water treated surfaces coefficient, and only 10% less than the dry surface coefficient.

This shows clearly that by introducing the additive, in this case glycerol, to the composition, is quite helpful to overcome the typical drawbacks that are observed with a composition of the prior art, i.e., surface slipperiness. Moreover, It is important to highlight that the addition of glycerol to the composition does not penalize the improved aspects that this composition shows with respect to other prior art compositions, in particular it does not affect the low freezing temperature that was achieved by composition E, i.e. -65°C. This allows to use this composition even in extreme environmental conditions.

The effect of a hydroxyalkilamine, which is introduced in a glycerine- containing anti-icing composition like compositions B to E of table I for anticorrosive purposes, to obtain respectively similar compositions F to J was also investigated. To this scope, compositions F to J that are shown in table III were prepared and used to treat a 384,2 g prismatic shaped body, and to evaluate its slipperiness coefficient, as above explained.

The results of the investigation are given in table IV. The positive effect of glycerine is to a further extent confirmed by this set of results, in particular by the data concerning compositions F and G.

TABLE III

Surprisingly, the presence of TEA appears to further enhance antislippery effect of glycerine on anti-icing compositions. This is shown by antislippery coefficients value of compositions H to J₁ respectively, that are 27% to 36% higher than the coefficients of compositions that have a same percent of Glycerine. A further evidence is given of such a synergistic behaviour Glycerine and TEA to reduce slipperiness is given by composition J, where the highest value of 0,653 is reached with only 3% TEA and 3% glycerine.

TABLE IV

The foregoing description of specific examplrs will so fully reveal the invention according to the conceptual point of view, that others, by applying current knowledge, will be able to modify and/or adapt for various applications such example without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific examples. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Claims

1. Anti-icing composition applicable on surfaces of different type, in particular, surfaces for vehicles, or pedestrians, for preventing ice from forming, or dissolving ice already formed, said composition comprising: - an anti-icing solution; a first additive that is mixed to said anti-icing solution in a predetermined weight percentage, said first additive containing a polyhydroxylated compound, i.e. a compound which has at least two hydroxyl groups -OH, such that said first additive is adapted to reduce slipperiness of said anti-icing composition; characterised in that it comprises, furthermore: a second additive that is mixed to said anti-icing solution in a predetermined weight percentage, said second additive containing a hydroxyalkilamine, such that said second additive is adapted to reduce corrosiveness of said anti-icing composition.

2. An anti-icing composition according to claim 1 , wherein said second additive is selected from the group comprised of: a secondary hydroxyalkilamine a tertiary hydroxyalkilamine - a mixture thereof.

3. An anti-icing composition according to claim 1 , wherein said second additive comprises at least a hydroxyethylamines, in particular a β-hydroxyethylamines, preferably said second additive comprises at least 60 weight percent of triethanolamine, i.e. tris(2-hydroxyethyl)-amine, i.e. TEA, in particular at least 80 weight percent of TEA.

4. An anti-icing composition, according to claim 1 , wherein said first additive is selected from the group comprised of: glycerol; mannitol; - sorbitol; lactulose; xylitol; levulose; sucrose; glucose; a combination thereof.

5. An anti-icing composition, according to claim 1 , wherein the weight percentage of said first additive in said anti-icing composition is set between 1 % and 20%, in particular said weight percentage is set between 2% and 15%, preferably between 2% and 12%, most preferably between 2% and 6%, advantageously between 2,7% and 3,3%.

6. An anti-icing composition, according to claim 1 , wherein the weight percentage of said second additive in said anti-icing composition is set between 1 % and 20%, in particular said weight percentage is set between 2% and 15%, preferably between 2% and 12%, most preferably between 2% and 10%, advantageously between 2,7% and 3,3%.

7. An anti-icing composition, according to claim 1 , wherein the ratio between the weight percentage of said first additive and the weight percentage of said second additive is set between 0,5 and 1 ,5, in particular said ratio is set between 0,8 and 1 ,2.

8. An anti-icing composition according to claim 7 wherein said first additive is Glycerine and said second additive is TEA.

9. An anti-icing composition, according to claim 1 , wherein said aqueous solution has a pH set between 7.2 and 9.5, in particular said pH set between 7,5 and 9.

10. An anti-icing composition, according to claim 9, wherein said anti-icing solution has an alkaline pH, and comprises at least one of the following dissolved ions: Bromide (Br^"), Bicarbonate (HCO³ ), Borate (BO₃ ^3"),

Silicate (SiO^3"), Fluoride (F), Iodine (I ).

11. An anti-icing composition, according to claim 1 , wherein said anti-icing solution comprises at least one metal chloride, in particular said or each chloride is selected from the group comprised of: a alkaline metal chloride, an alkaline earth metal chloride.

12. An anti-icing composition, according to claim 11 , wherein said at least one metal chloride is selected from the group comprised of:

- Sodium Chloride; Magnesium Chloride; Calcium Chloride; Potassium Chloride;

- Lithium chloride; - a combination of calcium chloride and magnesium chloride;

- another combination thereof.

13. An anti-icing composition applicable on surfaces of different type, in particular, surfaces for vehicles, or pedestrians, for preventing ice from forming, or for dissolving ice already formed, said composition comprising: an anti-icing solution;

- an additive that is mixed to said anti-icing solution in a predetermined weight percentage, said additive being a polyhydroxylated compound, i.e. a compound which has at least two hydroxyl groups -OH, whereby said additive is adapted to reduce slipperiness of said anti-icing composition;

- at least one metal chloride; characterised in that it comprises, furthermore:

- an aqueous solution having an alkaline pH in which at least one of the following ions is dissolved: Bromide (Br ), Bicarbonate (HCO^3"), Borate (BO₃ ^3"), Silicate (SiO^3"), Fluoride (F), Iodine (I^").

14. An anti-icing composition applicable on surfaces of different type, in particular, surfaces for vehicles, or pedestrians, for preventing ice from forming, or for dissolving ice already formed, said composition comprising: - an anti-icing solution;

- an additive that is mixed to said anti-icing solution in a predetermined weight percentage, said additive being a polyhydroxylated compound, i.e. a compound that has at least two hydroxyl groups -OH, such that the additive is adapted to reduce slipperiness of the anti-icing composition; - at least one metal chloride; characterised in that said additive is selected from the group comprised of: mannitol; sorbitol; lactulose;

- xylitol;

- levulose; sucrose; - glucose; a secondary hydroxyalkil amine

- a tertiary hydroxyalkilamine, in particular a triethanolamine; a combination thereof.

15. An anti-icing composition according to claim 13 or 14 wherein a further additive is comprised according to claims 1 to 12.