Patent Description:
Heat-transfer fluids are widely employed in heat exchange systems associated with internal combustion engines, solar systems, fuel cells, electrical motors, generators, electronic equipment and the like. Heat-transfer fluids are generally composed of a base fluid and one or more additives.

Historically, water has been the preferred base fluid when considering heat-transfer. In many applications, antifreeze properties are needed and a base fluid consisting of water mixed with freezing point depressants like alcohols, glycols or salts is employed. Since alcohols or glycols employed as freezing point depressant will affect the properties of the heat-transfer fluid (e.g. density, kinematic viscosity, thermal conductivity, heat capacity) differently than when salts are employed as freezing point depressants, two distinct classes of heat-transfer fluids have emerged, namely alcohol/glycol-free or alcohol/glycol-containing heat-transfer fluids.

Water and glycol mixtures are the most widely employed base fluids because such mixtures are relatively stable, are compatible with the elastomers and plastics used in modern heat exchange systems, provide cost efficient freezing and boiling protection and can be formulated with a variety of corrosion inhibitors to provide the specific corrosion protection required for particular heat exchange systems.

Heat-transfer fluids generally contain further additives which may be employed to obtain a variety of functionalities, such as improving the heat-exchange properties, inhibiting corrosion etc. Since heat-transfer fluids are in continuous contact with metal parts, such as aluminum alloys, cast iron, steel, copper, brass, solder etc., they nearly always contain one or more corrosion inhibitors.

The ability of carboxylic acids to inhibit corrosion in automotive cooling systems was first reported more than <NUM> years ago. Aromatic carboxylic acids, such as benzoic acid and its derivatives, have been extensively studied and are used in Europe as corrosion inhibitors in commercial coolants. Coolants comprising only organic acid corrosion inhibitors, sometimes referred to as OAT (organic acid technology) coolants, exhibit low depletion rates, resulting in an extended lifetime of the coolant, and are often more environmentally friendly than coolants relying on inorganic salts for corrosion inhibition.

Recent research efforts have been directed towards long chain aliphatic organic carboxylates. Aliphatic carboxylic acids comprising <NUM> or more carbon atoms have been found to act as corrosion inhibitors, although large variations in performance exist depending on the acid and the substrate. For example, <CIT> discloses the use of C<NUM>-C<NUM> dicarboxylic acids as corrosion inhibitors.

<CIT> discloses the use of glycerol-containing by-products of processing triglycerides, which can be combined with a hydroxyl-containing compound or organic acid salt to form a deicing fluid suitable for use in engine fuels.

<CIT> discloses the formulation of deicing fluids comprising hydroxyl-containing organic compounds and/or organic acid salts.

<CIT> discloses an anti-freeze composition for use in engine cooling systems.

<CIT> discloses the formulation of a corrosion inhibitor and a method of inhibiting cavitation-erosion of aluminium surfaces.

<CIT> discloses the formulation for a corrosion-inhibited antifreeze that exhibits synergistic corrosion properties for a variety of metal surfaces.

<NUM> <CIT> discloses de-icing fluids for airport runways.

Known heat transfer fluids employing organic carboxylate corrosion inhibitors, such as OAT heat transfer fluids, exhibit several disadvantages. For example, they are based on the corrosion inhibition of C<NUM> and higher carboxylates, such as C<NUM> or C<NUM> carboxylates, which are generally expensive. Additionally, the application of many higher carboxylates is limited or cannot be fully exploited because of their low water/glycol solubility.

It is an object of the present invention to provide improved glycol based heat-transfer fluids.

It is a further object of the present invention to provide glycol based heat-transfer fluids comprising reduced amounts of long-chain organic carboxylate, such as C<NUM> or higher organic carboxylate while possessing comparable or improved aluminium alloy corrosion inhibition.

It is a further object of the present invention to provide glycol based heat-transfer fluids possessing extended service life compared to known glycol based heat-transfer fluids, such as known glycol based heat-transfer fluids containing C<NUM> or higher organic carboxylates.

The present inventors have surprisingly found that one or more of these objectives can be met by employing a composition as defined in claim <NUM>.

As will be shown in the appended examples, it was surprisingly found that glycol based compositions comprising large amounts of short-chain carboxylic acid, such as more than <NUM> wt. %, preferably more than <NUM> wt. % of a short-chain organic carboxylic acid or salt thereof exhibit surprising corrosion inhibition on metal substrates such as aluminium.

Furthermore, in accordance with preferred embodiments of the invention, the present inventors have found that a glycol based composition comprising a short-chain organic carboxylic acid or salt thereof exhibits a sudden, non-linear increase in corrosion inhibition upon increasing the concentration of short-chain organic carboxylic acid or salt thereof.

In the art, short-chain organic carboxylates are not known to exhibit significant corrosion protection. Short-chain organic carboxylates have been investigated as freezing point depressants in glycol-free heat-transfer fluids. For example, <CIT> discloses glycol-free heat transfer compositions comprising a C<NUM> organic carboxylate freezing point depressant and a C<NUM>-C<NUM> organic acid salt corrosion inhibitor.

It will be understood by the skilled person in light of the present disclosure that the compositions in accordance with the present invention effectively allow the provision of heat-transfer fluids or coolants which require less or even no further additives and/or which are capable of maintaining metal corrosion inhibition for longer periods of time than comparable compositions known in the art.

In accordance with preferred embodiments of the invention, the pitting corrosion potential as referred to herein is measured by rapid cyclic potentiokinetic polarization scanning (RCP).

In highly preferred embodiments of the invention, the pitting corrosion potential as referred to herein is measured by rapid cyclic potentiokinetic polarization scanning (RCP) in accordance with the method described in CEBELCOR (Centre Belge d'Etude de la Corrosion) publications <NPL>). This method comprises altering the potential of a rod shaped, epoxy embedded, stagnant aluminum working electrode (alloy AlMgSi0. <NUM>) having a polished (using <NUM> grit polishing silicon-carbide paper) working surface of <NUM><NUM> with a scan rate of <NUM> mV/s in steps of <NUM>. 5mV versus a solid platinum auxiliary electrode (ref. <NUM>, supplier Metroohm) while submerged in <NUM> grams of test liquid and employing a solid silver reference electrode (ref. <NUM>, supplier Methrohom); recording the density of current flowing between the working and auxilary electrode as a function of potential difference employing a potentiostat (VeraSTAT; Ametek® Scientifc Instruments); and identifying the pitting corrosion potential Ep by a sudden exponential increase in current density.

A first aspect of the invention concerns compositions according to claim <NUM>.

As used herein, the term "monoethylene glycol" means "ethane-<NUM>,<NUM>-diol", and may also be referred to as "MEG".

As used herein, the term "monopropylene glycol" means "propane-<NUM>,<NUM>-diol", and may also be referred to as "MPG".

As used herein, the term "glycerol" means "propane-<NUM>,<NUM>,<NUM>-triol" and is synonymous with glycerin.

In embodiments of the invention a composition as described herein is provided, wherein the composition comprises more than <NUM> wt. % (by total weight of the composition) of the glycol, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. % or more than <NUM> wt. % of the glycol.

In preferred embodiments of the invention a composition as described herein is provided, wherein the composition comprises more than <NUM> wt. % (by total weight of the composition) of the glycol, preferably more than <NUM> wt. %, preferably more than <NUM> wt.

In embodiments of the invention a composition as described herein is provided, wherein the composition comprises less than <NUM> wt. % (by total weight of the composition) of the glycol, such as less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. % or less than <NUM> wt. % of the glycol.

In preferred embodiments of the invention, the glycol is selected from monoethylene glycol, monopropylene glycol, and combinations thereof. In such embodiments, it is preferred that the total amount of glycols different from monoethylene glycol and monopropylene glycol, in particular the total amount of glycerol present in the composition is less than <NUM> wt. % (by total weight of the composition), preferably less than <NUM> wt. %, more preferably less than <NUM> wt. %, most preferably about <NUM> wt. In embodiments the composition is essentially free of glycerol. In particular embodiments of the invention, the low glycerol embodiments as described herein are provided wherein the short-chain organic carboxylic acid or salt thereof is selected from the group consisting of C<NUM> organic carboxylic acids or salts thereof as described herein, preferably propionic acid or a salt thereof.

In highly preferred embodiments of the invention the compositions described herein are provided wherein the short-chain organic carboxylic acids or salts thereof described herein are provided in the form of a salt consisting of the carboxylate anion and a cationic counterion. The cationic counterion is preferably selected from the group consisting of an earth alkali metal cation, an alkali metal cation, an ammonium cation or combinations thereof, more preferably an alkali metal cation, most preferably sodium or potassium or combinations thereof. In embodiments of the invention the ammonium cation is a quaternary ammonium cation represented by the formula (NRR'R"R‴)+ wherein R, R', R" and R‴ are independently selected from the group of branched or straight C<NUM>-C<NUM> alkyls and branched or straight C<NUM>-C<NUM> hydroxyalkyls, preferably from methyl, ethyl, n-propyl and isopropyl. In embodiments of the invention the ammonium cation is a tertiary amine cation represented by the formula (HNRR'R")+ wherein R, R' and R" are independently selected from the group of branched or straight C<NUM>-C<NUM> alkyls and branched or straight C<NUM>-C<NUM> hydroxyalkyls, preferably from methyl, ethyl, n-propyl and isopropyl. In embodiments of the invention the ammonium cation is a secondary amine cation represented by the formula (H<NUM>NRR')+ wherein R, and R' are independently selected from the group of branched or straight C<NUM>-C<NUM> alkyls and branched or straight C<NUM>-C<NUM> hydroxyalkyls, preferably from methyl, ethyl, n-propyl and isopropyl.

If the short-chain organic carboxylic acid or salt thereof is employed in the form of a salt, the amount of organic carboxylic acid or salt thereof as used in this document refers to the amount of organic carboxylate anion and the cationic counterion (i.e. inclusive of the weight of the cationic counterion).

In embodiments of the invention the C<NUM> organic carboxylic acid or salt thereof is selected from the group consisting of acetic acid, oxalic acid, glycolic acid, glyoxylic acid or a salt thereof, or combinations thereof, more preferably potassium acetate or sodium acetate, most preferably potassium acetate.

In embodiments of the invention the C<NUM> organic carboxylic acid or salt thereof is selected from the group consisting of propionic acid, acrylic acid, propiolic acid, malonic acid, tatronic acid, mesoxalic acid, dihydroxymalonic acid, pyruvic acid, lactic acid, hydracrylic acid, glyceric acid, glycidic acid, <NUM>-aminopropanoic acid or a salt thereof, or combinations thereof; preferably the C<NUM> organic carboxylic acid or salt thereof is selected from the group consisting of propionic acid or lactic acid and combinations thereof; more preferably the C<NUM> organic carboxylic acid or salt thereof is selected from the group consisting of propionic acid or a salt thereof; more preferably the C<NUM> organic carboxylic acid or salt thereof is selected from potassium propionate or sodium propionate; most preferably the C<NUM> organic carboxylic acid or salt thereof is selected from potassium propionate.

In preferred embodiments the short-chain organic carboxylic acid or salt thereof is a C<NUM> organic carboxylic acid or a salt thereof as described herein.

In preferred embodiments the short-chain organic carboxylic acid or salt thereof is a C<NUM> organic carboxylic acid or a salt thereof as described herein. In embodiments of the invention a composition as described herein is provided, wherein the composition comprises more than <NUM> wt. % (by total weight of the composition) of the short-chain organic carboxylic acid or salt thereof, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt.

In embodiments of the invention a composition as described herein is provided, wherein the composition comprises less than <NUM> wt. % (by total weight of the composition) of the short-chain organic carboxylic acid or salt thereof.

In embodiments of the invention a composition as described herein is provided, wherein the combined amount of the glycol and the short-chain organic carboxylic acid or salt thereof is more than <NUM> wt. % (by total weight of the composition), more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. % or more than <NUM> wt.

In preferred embodiments of the invention a composition as described herein is provided, wherein the combined amount of the glycol and the short-chain organic carboxylic acid or salt thereof is more than <NUM> wt. % (by total weight of the composition), preferably more than <NUM> wt. %, preferably more than <NUM> wt.

In embodiments of the invention a composition as described herein is provided, wherein the combined amount of the glycol and the short-chain organic carboxylic acid or salt thereof is less than <NUM> wt. % (by total weight of the composition), preferably less than <NUM> wt. %, preferably less than <NUM> wt.

In highly preferred embodiments of the invention, a composition as described herein is provided, wherein the combined amount of the glycol and the short-chain organic carboxylic acid or salt thereof is in the range of <NUM>-<NUM> wt. % (by total weight of the composition), preferably in the range of <NUM>-<NUM> wt. %, more preferably in the range of <NUM>-<NUM> wt.

In embodiments of the invention a composition as described herein is provided, wherein the composition comprises more than <NUM> wt. % (by combined weight of the glycol and the short-chain organic carboxylate) of the short-chain organic carboxylate, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, or more than <NUM> wt. % of the short-chain organic carboxylic acid or salt thereof.

In preferred embodiments of the invention a composition as described herein is provided, wherein the composition comprises more than <NUM> wt. % (by combined weight of the glycol and the short-chain organic carboxylate) of the short-chain organic carboxylic acid or salt thereof, preferably more than <NUM> wt.

As is illustrated in the appended examples and explained herein before, the inventors have surprisingly found that a glycol based composition comprising a short-chain organic carboxylic acid or salt thereof exhibits a sudden, non-linear increase in corrosion inhibition upon increasing the concentration of short-chain organic carboxylic acid or salt thereof. However, the present inventors have also found that extremely high proportions of short-chain organic carboxylic acid to glycol such as may be employed in particular de-icing fluids are not necessary to obtain the improved corrosion effect. Hence, in embodiments of the invention a composition as described herein is provided, wherein the composition comprises less than <NUM> wt. % (by combined weight of the glycol and the short-chain organic carboxylate) of the short-chain organic carboxylate, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. %, or less than <NUM> wt. % of the short-chain organic carboxylic acid or salt thereof.

In preferred embodiments of the invention a composition as described herein is provided, wherein the composition comprises less than <NUM> wt. % (by combined weight of the glycol and the short-chain organic carboxylate) of the short-chain organic carboxylic acid or salt thereof, preferably less than <NUM> wt.

In highly preferred embodiments of the invention a composition as described herein is provided, wherein the composition comprises <NUM>-<NUM> wt. % (by combined weight of the glycol and the short-chain organic carboxylate) of the short-chain organic carboxylic acid or salt thereof, preferably <NUM>-<NUM> wt. %, more preferably <NUM>-<NUM> wt.

In accordance with the invention the composition as described herein is further comprises a long-chain organic carboxylic acid corrosion inhibitor selected from the group consisting of C<NUM>-C<NUM> organic carboxylic acids or salts thereof, preferably C<NUM>-C<NUM> organic carboxylic acids or salts thereof. Preferred C<NUM>-C<NUM> organic carboxylic acids include hexanoic acid, heptanoic acid, isoheptanoic acid, octanoic acid, <NUM>-ethylhexanoic acid, <NUM>,<NUM>,<NUM>-trimethylhexanoic acid, nonanoic acid, isononanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, neodecanoic acid, cyclohexylbutyl acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and salts thereof.

In certain embodiments of the invention a composition as described herein is provided, wherein the composition further comprises a high carboxylic acid corrosion inhibitor selected from the group consisting of.

Without wishing to be bound by any theory, the present inventors believe these corrosion inhibitors generally do not exhibit any solubility problems at the concentrations commonly employed in glycolbased heat-transfer fluids.

In certain embodiments of the invention a composition as described herein is provided, wherein the composition further comprises a long-chain organic carboxylic acid corrosion inhibitor selected from the group consisting of C<NUM>-C<NUM> aliphatic carboxylic acids and salts thereof, preferably C<NUM>-C<NUM> aliphatic dicarboxylic acids and salts thereof, preferably C<NUM>-C<NUM> aliphatic dicarboxylic acids and salts thereof, most preferably C<NUM>-C<NUM> aliphatic dicarboxylic acids and salts thereof.

In embodiments of the invention the long-chain organic carboxylic acid corrosion inhibitors described herein are provided in the form of a salt consisting of the carboxylate anion and a cationic counterion. The cationic counterion is preferably selected from the group consisting of an earth alkali metal cation, an alkali metal cation, an ammonium cation or combinations thereof, more preferably an alkali metal cation, most preferably sodium or potassium or combinations thereof. In embodiments of the invention the ammonium cation is a quaternary ammonium cation represented by the formula (NRR'R"R‴)+ wherein R, R', R" and R‴ are independently selected from the group of branched or straight C<NUM>-C<NUM> alkyls and branched or straight C<NUM>-C<NUM> hydroxyalkyls, preferably from methyl, ethyl, n-propyl and isopropyl. In embodiments of the invention the ammonium cation is a tertiary amine cation represented by the formula (HNRR'R")+ wherein R, R' and R" are independently selected from the group of branched or straight C<NUM>-C<NUM> alkyls and branched or straight C<NUM>-C<NUM> hydroxyalkyls, preferably from methyl, ethyl, n-propyl and isopropyl. In embodiments of the invention the ammonium cation is a secondary amine cation represented by the formula (H<NUM>NRR')+ wherein R, and R' are independently selected from the group of branched or straight C<NUM>-C<NUM> alkyls and branched or straight C<NUM>-C<NUM> hydroxyalkyls, preferably from methyl, ethyl, n-propyl and isopropyl. If the long-chain organic carboxylic acid or salt thereof is employed in the form of a salt, the amount of long-chain organic carboxylic acid or salt thereof as used in this document refers to the amount of organic carboxylate anion and the cationic counterion (i.e. inclusive of the weight of the cationic counterion).

In preferred embodiments of the invention a composition as described herein is provided, wherein the composition further comprises more than <NUM> wt. % (by total weight of the composition) of the long-chain organic carboxylic acid corrosion inhibitor described herein, preferably more than <NUM> wt. %, preferably more than <NUM> wt. % of the long-chain organic carboxylic acid corrosion inhibitor.

In certain embodiments of the invention a composition as described herein is provided, wherein the composition comprises less than <NUM> wt. % (by total weight of the composition) of the long-chain organic carboxylic acid corrosion inhibitor described herein, preferably less than <NUM> wt. %, preferably less than <NUM> wt. %, preferably less than <NUM> wt. %, preferably less than <NUM> wt. % of the long-chain organic carboxylic acid corrosion inhibitor.

In preferred embodiments of the invention a composition as described herein is provided, comprising the long-chain organic carboxylic acid corrosion inhibitor described herein in an amount within the range of <NUM>-<NUM> wt. % (by total weight of the composition), preferably in the range of <NUM>-<NUM> wt. %, preferably in the range of <NUM>-<NUM> wt.

In certain embodiments of the invention a composition as described herein is provided, wherein the composition comprises less than <NUM> wt. % (by total weight of the composition) C<NUM>-C<NUM> aliphatic carboxylic acid and salts thereof, preferably less than <NUM> wt. %, preferably less than <NUM> wt. %, more preferably less than <NUM> wt.

In accordance with the invention, the composition as described herein exhibits an aluminium pitting corrosion potential of more than <NUM> mV when determined by rapid cyclic potentiokinetic polarization scanning (RCP), preferably employing an AlMgSi0. <NUM> alloy working electrode.

In highly preferred embodiments of the invention, a composition as described herein is provided exhibiting an aluminium pitting corrosion potential of more than <NUM> mV when determined in accordance with the method described in CEBELCOR (Centre Belge d'Etude de la Corrosion) publications <NPL>).

In highly preferred embodiments of the invention, a composition as described herein is provided exhibiting an aluminium pitting corrosion potential of more than <NUM> mV when determined by altering the potential of a rod shaped, epoxy embedded, stagnant aluminum working electrode (alloy AlMgSi0. <NUM>) having a polished (using <NUM> grit polishing silicon-carbide paper) working surface of <NUM><NUM> with a scan rate of <NUM> mV/s in steps of <NUM>. 5mV versus a solid platinum auxiliary electrode (ref. <NUM>, supplier Metroohm) while submerged in <NUM> grams of test liquid and employing a solid silver reference electrode (ref. <NUM>, supplier Methrohom); recording the density of current flowing between the working and auxilary electrode as a function of potential difference employing a potentiostat (VeraSTAT; Ametek® Scientifc Instruments); and identifying the pitting corrosion potential Ep by a sudden exponential increase in current density.

As will be understood by the skilled person, and as shown in the appended examples, depending on the presence and the amount of other corrosion inhibitors, the minimum amount of low carboxylic acid or salt thereof required to attain an aluminium pitting corrosion potential of more than <NUM> mV when determined by rapid cyclic potentiokinetic polarization scanning (RCP) will vary. It is within the routine capabilities of the skilled person, in light of this disclosure, to formulate compositions exhibiting an aluminium pitting corrosion potential corrosion of more than <NUM> mV when determined by rapid cyclic potentiokinetic polarization scanning (RCP).

In certain embodiments of the invention the composition as defined herein further comprises one or more additives selected from the group consisting of further corrosion inhibitors, antioxidants, anti-wear agents, surfactants and/or antifoam agents. In this context, further corrosion inhibitors should be interpreted to mean corrosion inhibitors other than the low and long-chain organic carboxylic acids and salts thereof described herein. Preferred further corrosion inhibitors are selected from the group consisting of inorganic corrosion inhibitors, phosphonate corrosion inhibitors, azole corrosion inhibitors and thiazole corrosion inhibitors.

In certain embodiments of the invention the composition further comprises more than <NUM> wt. % (by total weight of the composition) of said additives, preferably more than <NUM> wt. %, preferably more than <NUM> wt.

In preferred embodiments the composition of the invention further comprises one or more additives selected from the group consisting of thiazoles, triazoles, polyolefins, polyalkylene oxides, silicon oils, mineral oils, silicates, molybdates, nitrates, nitrites, phosphonates and phosphates. In preferred embodiments the composition of the invention further comprises one or more of said additives in an amount within the range of <NUM>-<NUM> wt. % (by total weight of the composition), preferably <NUM>-<NUM> wt.

In preferred embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises a triazole, a thiazole or a combination thereof, preferably an aromatic triazole, an aromatic thiazole or a combination thereof. In preferred embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises a corrosion inhibitor in the form of one or more triazoles selected from the group consisting of tolyltriazole, benzotriazole or combinations thereof.

In embodiments of the invention, a composition as defined herein is provided, wherein the composition comprises the triazole or thiazole in an amount of more than <NUM> wt. % (by total weight of the composition), preferably more than <NUM> wt. %, preferably more than <NUM> wt. % and/or less than <NUM> wt. %, preferably less than <NUM> wt. %, preferably less than <NUM> wt.

In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises a defoaming agent. Preferably, the defoaming agent is selected from the group consisting of a polyolefin, a polyalkylene oxide, a silicon polymer (such as a 3D silicon polymer) or a silicon oil.

In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises the defoaming agent in an amount of more than <NUM> wt. % (by total weight of the composition), preferably more than <NUM> wt. %, preferably more than <NUM> wt. % and/or less than <NUM> wt. %, preferably less than <NUM> wt. %, preferably less than <NUM> wt.

In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises a corrosion inhibitor in the form of a molybdate, preferably an inorganic molybdate in an amount of more than <NUM> ppm (by total weight of the composition) molybdate, preferably more than <NUM> ppm, preferably more than <NUM> ppm molybdate and/or less than <NUM> ppm, preferably less than <NUM> ppm, preferably less than <NUM> ppm.

If the molybdate is employed in the form of a salt, the amount of molybdate as used in this document refers to the amount of molybdate anion (i.e. exclusive of the weight of the cationic counterion).

In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises a nitrate, preferably an inorganic nitrate in an amount of more than <NUM> ppm (by total weight of the composition) nitrate, preferably more than <NUM> ppm, preferably more than <NUM> ppm nitrate and/or less than <NUM> ppm, preferably less than <NUM> ppm, preferably less than <NUM> ppm.

If the nitrate is employed in the form of a salt, the amount of nitrate as used in this document refers to the amount of nitrate anion (i.e. exclusive of the weight of the cationic counterion).

In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises a nitrite, preferably an inorganic nitrite in an amount of more than <NUM> ppm (by total weight of the composition) nitrite, preferably more than <NUM> ppm, preferably more than <NUM> ppm nitrite and/or less than <NUM> ppm, preferably less than <NUM> ppm, preferably less than <NUM> ppm.

If the nitrite is employed in the form of a salt, the amount of nitrite as used in this document refers to the amount of nitrite anion (i. e exclusive of the weight of the cationic counterion).

In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises a phosphonate, preferably an inorganic phosphonate in an amount of more than <NUM> ppm (by total weight of the composition) phosphonate, preferably more than <NUM> ppm, preferably more than <NUM> ppm phosphonate and/or less than <NUM> ppm, preferably less than <NUM> ppm, preferably less than <NUM> ppm.

If the phosphonate is employed in the form of a salt, the amount of phosphonate as used in this document refers to the amount of phosphonate anion (i.e. exclusive of the weight of the cationic counterion).

In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises a corrosion inhibitor in the form of a phosphate, preferably an inorganic phosphate in an amount of more than <NUM> ppm (by total weight of the composition) phosphate, preferably more than <NUM> ppm, preferably more than <NUM> ppm phosphate and/or less than <NUM> ppm, preferably less than <NUM> ppm, preferably less than <NUM> ppm.

If the phosphate is employed in the form of a salt, the amount of phosphate as used in this document refers to the amount of phosphate anion (i.e. exclusive of the weight of the cationic counterion).

In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises a corrosion inhibitor in the form of a silicate, preferably an inorganic silicate, preferably sodium metasilicate in an amount more than <NUM> ppm Si (by total weight of the composition), preferably more than <NUM> ppm Si, most preferably more than <NUM> ppm Si and/or less than <NUM> ppm, preferably less than <NUM> ppm, preferably less than <NUM> ppm.

In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises an antioxidant. Preferably, the antioxidant is selected from the group consisting of phenols, such as <NUM>,<NUM> di-t-butyl methylphenol and <NUM>,<NUM>'-methylene-bis(<NUM>,<NUM>-di-t-butylphenol); aromatic amines, such as p,p-dioctylphenylamine, monooctyldiphenylamine, phenothiazine, <NUM>,<NUM>-dioctylphenothiazine, phenyl-<NUM>-naphthylamine, phenyl-<NUM>-naphthylamine, alkylphenyl-<NUM>-naphthatalamines and alkyl-phenyl-<NUM>-naphthal-amines, as well as sulphur containing compounds, e.g. dithiophosphates, phosphites, sulphides and dithio metal salts, such as benzothiazole, tin-dialkyldithiophosphates and zinc diaryldithiophosphates.

In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises the antioxidant in an amount more than <NUM> wt. % (by total weight of the composition), preferably more than <NUM> wt. %, preferably more than <NUM> wt. % and/or less than <NUM> wt. %, preferably less than <NUM> wt. %, preferably less than <NUM> wt.

In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises an antiwear agent. Preferably, the antiwear agent is selected from the group consisting of phosphate esters, phosphites, thiophosphites, e.g. zinc dialkyl dithiophosphates, zinc diaryldithiophosphates, tricresyl phosphates, chlorinated waxes, sulphurised fats and olefins, such as thiodipropionic esters, dialkyl sulphides, dialkyl polysulphides, alkylmercaptanes, dibenzothiophenes and <NUM>,<NUM>'-dithiobis(benzothiazole); organic lead compounds, fatty acids, halogen substituted organosilicon compounds, and halogen-substituted phosphorus compounds.

In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises the antiwear agent in an amount of more than <NUM> wt. % (by total weight of the composition), preferably more than <NUM> wt. %, preferably more than <NUM> wt. % and/or less than <NUM> wt. %, preferably less than <NUM> wt. %, preferably less than <NUM> wt.

In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises a surfactant. Preferably, the surfactant is selected from the group consisting of anionic surfactants, such as anionic surfactants which are the salt of a compound represented by R-X; wherein X represents a sulfate group, a phosphate group, a sulfonate group, or a carboxylate group, preferably a sulfate group; and wherein R is selected from:.

In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises the surfactant in an amount of more than <NUM> wt. % (by total weight of the composition), preferably more than <NUM> wt. %, preferably more than <NUM> wt. % and/or less than <NUM> wt. %, preferably less than <NUM> wt. %, preferably less than <NUM> wt. In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises a scale inhibitor. Preferably, the scale inhibitor is selected from the group consisting of chelants, threshold precipitation inhibitors or combinations thereof. In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises a scale inhibtor which is a chelant selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), citric acid, and gluconic acid. In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises a scale inhibitor which is a threshold precipitation inhibitor selected from the group consisting of polyphosphates (e.g. sodium triphosphate or sodium hexametaphosphate ); phosphonates (e.g. aminotrimethylene phosphonic acid (ATMP), ethylenediaminetetramethylene phosphonic acid (EDTMP), diethylenetriaminepentamethylene phosphonic acid (DETPMP), pentaethylenehexamineoctakismethylene phosphonic acid (PEHOMP), <NUM>-hydroxyethylidene-<NUM>,<NUM>-diphosphonic acid (HEDP), <NUM>-phosphonobutane-<NUM>,<NUM>,<NUM>-tricarboxylic acid (<NUM>-PBTCA), polyvinyl phosphonic acid (PPA), phosphino-carboxylic acids (PCA) such as poly(phosphino-acrylic acid) (PPCA) or sulfonated phosphino-carboxylic acid (SPOCA)); polycarboxylic acids and their derivatives (e.g. polymers of maleic anhydride, of maleic acid, of acrylic acid or of methacrylic acid; copolymers of said polymers employing a further monomer such as acrylamide, vinyl sulfonic acid, sulfonated styrene, and itaconic acid; polymers of epoxycarboxylic acids such as polyepoxysuccinic acid or polymers of amino acids such as polyaspartic acid. In embodiments of the invention, a composition as defined herein is provided, wherein the composition further comprises the scale inhibitor in an amount of more than <NUM> wt. % (by total weight of the composition), preferably more than <NUM> wt. %, preferably more than <NUM> wt. % and/or less than <NUM> wt. %, preferably less than <NUM> wt. %, preferably less than <NUM> wt.

As will be understood by the skilled person, depending on (for example) the intended application, the compositions in accordance with the invention may be formulated and used at various concentrations. Hence, the invention is not particularly limited by the maximum concentration of the glycol or the short-chain organic carboxylic acid, or by the concentration of the other additives described herein. Thus, depending on the envisaged application, the compositions described herein may be suitable for use as is, or may require dilution by base fluid before use. However, the present inventors have found that it is particularly advantageous to provide the compositions of the invention in the form of a ready-to-use composition which may be suitable for use as a combustion engine coolant or in the form of a concentrate which is suitable to prepare said ready-to-use composition.

In a highly preferred embodiment of the invention, the composition as described herein is provided in the form of a ready-to-use composition wherein the composition further comprises water and wherein.

In preferred embodiments of the invention the ready-to-use composition is provided, wherein the ready-to-use composition comprises more than <NUM> wt. % (by total weight of the composition) water, such as more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, more than <NUM> wt. %, or more than <NUM> wt.

Hence, in highly preferred embodiments of the invention, a composition is provided comprising:.

In preferred embodiments of the invention, a composition is provided comprising:.

In preferred embodiments of the invention, a composition, preferably a ready-to-use composition as defined herein is provided, wherein the composition has a pH between <NUM> and <NUM>.

In another aspect of the invention there is provided a composition as defined herein, in the form of a concentrate suitable to prepare the ready-to-use composition described herein before.

In preferred embodiments, the concentrate is suitable to prepare the ready-to-use composition described herein by addition of water and/or alcohol; preferably by addition of water, monoethylene glycol, monopropylene glycol, <NUM>,<NUM>-propanediol and/or glycerol; most preferably by addition of water. In highly preferred embodiments, the concentrate is suitable to prepare the ready-to-use composition solely by addition of water and/or alcohol; preferably solely by addition of water, monoethylene glycol, monopropylene glycol, <NUM>,<NUM>-propanediol and/or glycerol; most preferably solely by addition of water (i.e. no other ingredients need to be added in order to prepare the ready-to-use composition described herein from the concentrate).

In certain embodiments of the invention the concentrate comprises more than <NUM> wt. % (by total weight of the concentrate) of a polyalcohol, preferably a polyalcohol selected from the group consisting of monoethylene glycol, monopropylene glycol, <NUM>,<NUM>-propanediol and glycerol.

In another aspect of the disclosure which is not claimed there is provided a method to prepare a composition as defined herein, comprising the steps of:.

In accordance with the disclosure the order of addition of the compounds is not particularly limited.

In another aspect of the disclosure which is not claimed there is provided a method to prepare a ready-to-use composition as defined herein, comprising the steps of:.

In preferred embodiments there is provided a method to prepare a ready-to-use composition as defined herein, consisting of the following steps:.

In highly preferred embodiments the alcohol of step (ii) is selected from the group consisting of monoethylene glycol, monopropylene glycol, <NUM>,<NUM>-propanediol, glycerol and combinations thereof. In preferred embodiments step (ii) consists of providing water.

In preferred embodiments step (ii) comprises providing more than <NUM> wt. % (by weight of the concentrate) water, alcohol or a mixture thereof, preferably more than <NUM> wt. %, more than <NUM> wt. % more than <NUM> wt. % or more than <NUM> wt. % water, alcohol or a mixture thereof.

In another aspect of the invention there is provided the use of claim <NUM>.

In another aspect of the disclosure which is not claimed there is provided a method of inhibiting corrosion comprising contacting the composition, preferably the ready-to-use composition provided herein with a metal surface.

In another aspect of the disclosure which is not claimed there is provided a combustion engine, a turbo cooler, an exhaust gas recovery cooler, a brake heat recovery system, a solar system, a fuel cell, an electrical motor, a generator, or electronic equipment comprising the composition, preferably the ready-to-use composition as described herein.

In another aspect of the disclosure which is not claimed there is provided a method of exchanging heat, comprising:.

In another aspect of the disclosure which is not claimed there is provided the use of a short-chain organic carboxylic acid selected from the group consisting of C<NUM> organic carboxylic acids or salts thereof, C<NUM> organic carboxylic acids or salts thereof, and combinations thereof, preferably selected from the group consisting of propionic acid and salts thereof, acetic acid and salts thereof, and combinations thereof; for increasing the corrosion inhibition of a composition comprising more than <NUM> wt. % (by total weight of the composition) of a glycol selected from the group consisting of monoethylene glycol, monopropylene glycol, <NUM>,<NUM>-propanediol, glycerol or combinations thereof; preferably for increasing the pitting corrosion potential, most preferably for increasing the pitting corrosion potential of aluminum. In preferred embodiments of the invention there is provided the use of a short-chain organic carboxylic acid selected from the group consisting of C<NUM> organic carboxylic acids or salts thereof, C<NUM> organic carboxylic acids or salts thereof, and combinations thereof, preferably selected from the group consisting of propionic acid and salts thereof, acetic acid and salts thereof, and combinations thereof; for increasing the corrosion inhibition of a composition comprising more than <NUM> wt. % (by total weight of the composition) of a glycol selected from the group consisting of monoethylene glycol, monopropylene glycol, and combinations thereof; preferably for increasing the pitting corrosion potential, most preferably for increasing the pitting corrosion potential of aluminum.

% values in Tables <NUM>-<NUM> are based on the total weight of the composition (unless indicated otherwise). The corrosion inhibitor solution consists of <NUM> wt. % of a mixture of C<NUM> and C<NUM> carboxylic acid salts (wherein the wt. % is calculated based on the organic carboxylate anion (i.e. exclusive of the weight of the cationic counterion)) in water. The corrosive water comprises <NUM> milligram sodium sulphate, <NUM> milligram sodium chloride, <NUM> sodium hydrogencarbonate and <NUM> calcium chloride dihydrate dissolved in <NUM> liter water. The pitting corrosion potential is measured through Rapid Cyclic Potentiokinetic Polarization Scanning (RCP) in accordance with the method described in CEBELCOR (Centre Belge d'Etude de la Corrosion) publications <NPL>) described herein earlier. A higher Ep value indicates a more effective prevention of localized corrosion. Examples A1-A7, A11, A12, B1-B4, C1-C5 and D1-D4 are comparative examples not according to the invention.

Claim 1:
A composition comprising:
• more than <NUM> wt.% (by total weight of the composition) of a glycol selected from the group consisting of monoethylene glycol, monopropylene glycol, <NUM>,<NUM>-propanediol, glycerol or combinations thereof; and
• more than <NUM> wt.% (by total weight of the composition) of a short-chain organic carboxylic acid or salt thereof selected from the group consisting of C2 organic carboxylic acids or salts thereof, C3 organic carboxylic acids or salts thereof and combinations thereof;
wherein the combined amount of the glycol and the short-chain organic carboxylic acid or salt thereof is more than <NUM> wt.% (by total weight of the composition);
wherein the composition exhibits an aluminium pitting corrosion potential of more than <NUM> mV when determined by rapid cyclic potentiokinetic polarization scanning (RCP), preferably employing an AlMgSi0.<NUM> alloy working electrode;
wherein the composition further comprises a long-chain organic carboxylic acid corrosion inhibitor selected from the group consisting of C6-C16 organic carboxylic acids or salts thereof, preferably C6-C11 organic carboxylic acids or salts thereof; and wherein the composition comprises less than <NUM> wt.% (by total weight of the composition) of the short-chain organic carboxylic acid or salt thereof.