Polyol esters

Abstract

A polyol ester comprises a reaction product of a monocarboxylic acid or ester thereof and a polyol. The acid may be hexanoic acid, octanoic acid, decanoic acid, lauric acid, myristic acid, myristoleic

Description

Silicone compounds, such as polydimethylsiloxane, functionalised polydimethylsiloxanes, organosilicones, and related compounds are used widely in a range of applications and products. They may be provided in concentrate compositions, either for direct use or for later dilution priorto use. However, high concentrations of silicone compounds can cause concentrate compositions to be highly viscous and difficult to pour or pump. Furthermore, high concentrations of the silicone compound can cause concentrate compositions to be unstable when stored for extended periods of time, especially when the silicone compound is poorly soluble or poorly miscible with a diluent comprised in the concentrate composition. There are a number of disadvantages associated with the use of such silicone compounds, including their low biodegradability, which has led to environmental concerns. It is thus an object of the invention to provide an alternative to silicone compounds that can be used in a wide range of applications and uses. It is another object of the invention to provide alternatives to silicone compounds that are more biodegradable whilst having equal or improved properties. It is another object of the invention to improve the stability and / or flowability of concentrate compositions comprising such compounds. Summary of the Invention According to aspects of the present invention, there is provided a polyol ester, method and concentrate composition as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and from the description which follows. The inventors have identified that certain polyol esters have properties that are at least comparable to that provided by known silicone compounds, whilst also being more biodegradable. According to a first aspect of the invention, there is provided a polyol ester, wherein the polyol ester is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof and the or each second reactant is a polyol. According to a second aspect of the invention, there is provided a concentrate composition comprising one or more polyol esters and optionally at least one solvent, wherein the concentrate composition comprises at least 20 wt% of the one or more polyol esters, and wherein the or each polyol ester is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof and the or each second reactant is a polyol. According to a third aspect of the invention, there is provided a use of a surfactant to emulsify at least one polyol ester in an aqueous concentrate composition, wherein the aqueous concentrate composition comprises at least 20 wt% of the one or more polyol esters, and wherein the polyol ester is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof and the or each second reactant is a polyol. According to a fourth aspect of the invention, there is provided a method of emulsifying at least one polyol ester in an aqueous composition to make an aqueous polyol ester concentrate composition, wherein the aqueous polyol ester concentrate composition comprises at least 20 wt% of the one or more polyol esters, the method comprising admixing a surfactant with the polyol ester in an aqueous composition, wherein the polyol ester is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof and the or each second reactant is a polyol. Other features of the invention will be apparent from the dependent claims, and from the description which follows. Features described in relation to the second, third and fourth aspects may have any of the suitable features and advantages described in relation to the first and second aspects. Detailed Description of the Invention Unless otherwise stated, the following terms used in the specification and claims have the meanings set out below. The terms “alkyl” and “alkylene” include both straight and branched chain alkyl and alkylene groups respectively unless otherwise stated. References to individual alkyl groups such as “propyl” are specific for the straight chain version only and references to individual branched chain alkyl groups such as “isopropyl” are specific for the branched chain version only. For example, “C3-30 alkyl” includes C6-24 alkyl, Ce-s alkyl, propyl, isopropyl and t-butyl. The term “alkenyl” includes both straight and branched chain alkenyl groups. References to individual alkenyl groups such as “propenyl” are specific for the straight chain version only and references to individual branched chain alkenyl groups such as “isopropenyl” are specific for the branched chain version only. For example, “C3-30 alkenyl” includes C6-24 alkenyl, Ce-s alkenyl, propenyl and isopropenyl. Herein C3-30 means a group having from 3 to 30 carbons atoms therein, for example having 3, 4, 5 etc up to 30 carbon atoms. The term "hydrocarbyl" is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. As used in the specification and the appended claims, the singular forms "a", "an," and "the" include both singular and plural referents unless the context clearly dictates otherwise. Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of other components. The term “consisting essentially of’ or “consists essentially of’ means including the components specified but excluding other components except for components added for a purpose other than achieving the technical effect of the invention. The term “consisting of’ or “consists of’ means including the components specified but excluding other components. Whenever appropriate, depending upon the context, the use of the term “comprises” or “comprising” may also be taken to include the meaning “consists essentially of’ or “consisting essentially of’, and also may also be taken to include the meaning “consists of’ or “consisting of’. As used herein, unless otherwise expressly specified, all numbers such as those expressing values, ranges, amounts of percentages may be read as if prefaced by the word “about”, even if the term does not expressly appear. The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g. 1 to 5 can include 1,2,3,4 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.70 and 3.80, when referring to, for example, measurements). The recitation of end points also includes the end point values themselves (e.g. from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all sub-ranges subsumed therein. The optional features set out herein may be used either individually or in combination with each other where appropriate and particularly in the combinations as set out in the accompanying claims. The optional features for each exemplary aspect of the invention, as set out herein are also applicable to any other aspects or exemplary aspects of the invention, where appropriate. In other words, the skilled person reading this specification should consider the optional features for each aspect or embodiment of the invention as interchangeable and combinable between different aspects of the invention. As used herein, the term "and / or," when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a list is described as comprising group A, B, and / or C, the list can comprise A alone; B alone; C alone; A and B in combination; A and C in combination, B and C in combination; or A, B, and C in combination. The term “reactant” is used herein to refer to a compound comprising at least one reactive functional group. As reported herein, the number average molecular weight was determined by gel permeation chromatography using a polystyrene standard according to ASTM D6579-11 (“Standard Practice for Molecular Weight Averages and Molecular Weight Distribution of Hydrocarbon, Rosin and Terpene Resins by Size Exclusion Chromatography”. UV detector; 254 nm, solvent: unstabilised THF, retention time marker: toluene, sample concentration: 2mg / ml). According to a first aspect of the invention, there is provided a polyol ester, wherein the polyol ester is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof and the or each second reactant is a polyol. Suitable features of the first aspect will now be described. The polyol ester of the first aspect is the reaction product of reactants comprising one or more first reactants and one or more second reactants as defined herein. In other words, the polyol ester may be obtainable or obtained by reacting reactants comprising one or more first reactants and one or more second reactants as defined herein. By “polyol ester” we mean the ester of a polyol. The polyol may be partially or fully esterified. Preferably, the polyol ester is partially esterified. The partially esterified polyol ester comprises one or more hydroxy groups, such as two or more hydroxy groups. The polyol ester of the first aspect may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants as defined herein. In other words, the polyol ester may be obtainable or obtained by reacting reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants as defined herein. The first and second reactants may be reacted in any suitable molar ratio to make the polyol ester, as would be appreciated by a person skilled in the art. The first and second reactants may be reacted in a molar ratio of from 1:10 to 10:1, preferably from 1:6 to 6:1, for example from 1:3 to 3:1. Ratios refer to the total amounts of first reactants or second reactants if more than one first reactant or second reactant is present. The polyol ester may be prepared by any suitable method, as would be known to persons skilled in the art. References herein to a reaction product of reactants comprising the first and second reactants are intended to refer to a product of the reaction of reactants comprising the first and second reactants conducted in any suitable manner. For example, the reaction may occur between the first and second reactants in the absence of other reactant(s) or may occur in the presence of other reactant(s). References herein to a reactant are intended to refer to the compounds that react to form the polyol ester and are not intended to include a catalyst used in the reaction. The or each of the one or more first reactants used to make the polyol ester is a monocarboxylic acid or ester thereof. Mixtures of two or more different first reactants (i.e. different monocarboxylic acids or esters thereof) may be used to make the polyol ester. Any suitable monocarboxylic acid or ester thereof may be used to make the polyol ester, as would be understood by the person skilled in the art. The first reactant may be a monocarboxylic acid or an ester thereof. The monocarboxylic acid may be aliphatic or aromatic. The aliphatic monocarboxylic acid may be cycloaliphatic. The aliphatic monocarboxylic acid may be saturated or unsaturated. By the term “unsaturated” we mean that the monocarboxylic acid comprises one or more carbon-carbon double bonds. Preferably the monocarboxylic acid is aliphatic. Suitably, the monocarboxylic acid does not contain more than one hydroxy group. Preferably, the monocarboxylic acid does not contain any hydroxy groups. The monocarboxylic acid may contain from 2 to 40 carbon atoms, suitably from 4 to 30 carbon atoms, preferably from 6 to 20 carbon atoms, for example from 8 to 18 carbon atoms. The monocarboxylic acid may be a fatty acid. Examples of suitable monocarboxylic acids include hexanoic acid, octanoic acid, decanoic acid, lauric acid, myristic acid, myristoleic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, linolelaidic acid, arachidic acid, arachidonic acid, behenic acid, and erucic acid. Preferably, the monocarboxylic acid is selected from hexanoic acid, octanoic acid, lauric acid, stearic acid, oleic acid, linoleic acid, or erucic acid. More preferably, the monocarboxylic acid is erucic acid. The first reactant may be an ester of the monocarboxylic acid. The ester of the monocarboxylic acid is suitably a hydrocarbyl ester, such as an alkyl ester, an alkenyl ester, an aryl ester, an aralkyl ester, or an alkaryl ester. Preferably the ester is an alkyl ester. The alkyl ester is suitably formed by reacting the monocarboxylic acid with an alkanol. The alkanol suitably contains from 1 to 10 carbon atoms, such as from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms. The alkanol is preferably methanol. The alkyl ester is preferably a methyl ester. The ester of the monocarboxylic acid may be a fatty acid methyl ester (FAME). The ester of the monocarboxylic acid may be selected from methyl hexanoate, methyl octanoate, methyl decanoate, methyl laurate, methyl myristate, methyl myristoleate, methyl palmitate, methyl palmitoleate, methyl stearate, methyl oleate, methyl elaidate, methyl linoleate, methyl linolelaidate, methyl arachidate, methyl arachidonate, methyl behenate, or methyl erucate. Preferably, the ester acid is selected from methyl octanoate, methyl laurate, methyl stearate, methyl oleate, methyl linoleate, or methyl erucate. More preferably, the ester acid is methyl erucate. The monocarboxylic acid or the ester thereof may be selected from hexanoic acid, octanoic acid, decanoic acid, lauric acid, myristic acid, myristoleic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, linolelaidic acid, arachidic acid, arachidonic acid, behenic acid, erucic acid, or an ester (preferably a methyl ester) thereof. The monocarboxylic acid or the ester thereof may be selected from hexanoic acid, octanoic acid, lauric acid, stearic acid, oleic acid, linoleic acid, erucic acid, or an ester (preferably a methyl ester) thereof. The monocarboxylic acid or the ester thereof is preferably erucic acid or an ester (preferably a methyl ester) thereof. Preferably, the monocarboxylic acid or the ester thereof may be selected from hexanoic acid, methyl octanoate, lauric acid, methyl laurate, stearic acid, methyl stearate, methyl oleate, methyl linoleate, or methyl erucate. The monocarboxylic acid or ester thereof compounds discussed herein may be commercially available or may be prepared using procedures well known in the art. The or each of the one or more second reactants used to make the polyol ester is a polyol. Mixtures of two or more different second reactants (i.e. different polyol) may be used to make the polyol ester. Any suitable polyol may be used to make the polyol ester, as would be understood by the person skilled in the art. The term polyol is used to refer to any compound including two or more hydroxy (OH) functional groups. In some embodiments the or each polyol may comprise carbon, hydrogen and oxygen atoms, and optionally additionally nitrogen atoms. In other embodiments, the or each polyol may consist essentially of or consist of carbon, hydrogen and oxygen atoms. Suitable polyols for preparing the polyol ester may be compounds having from 2 to 10, preferably from 2 to 6, more preferably 2 or 3, hydroxy groups. Most preferred polyols have from 2 to 8 hydroxy groups. Suitable polyols may include one or more of a polyol of formula (I): H-(OR1)P-OH (I) wherein each R1 is independently an optionally substituted hydrocarbylene group and p is an integer of at least 1. When p is an integer of greaterthan 1, the polyol of formula (I) may comprise groups R1 that are all the same or may comprise groups R11 that are different. Suitably, each R1 in the formula (I) may be the same. Preferably p is an integer from 1 to 140, such as from 1 to 110, from 1 to 40 or from 1 to 10. For example, suitable polyols may include one or more of a polyol of formula (IA): H-(OR2)q-OH (IA) wherein each R2 is independently an optionally substituted alkylene group and q is an integer of at least 1. When q is an integer of greater than 1, the polyol of formula (IA) may comprise groups R2 that are all the same or may comprise groups R2 that are different. Suitably, each R2 in the formula (IA) is the same. Preferably q is an integer from 1 to 140, such as from 1 to 110, from 1 to 40 or from 1 to 10. When the polyol of formula (I) or (IA) contains a substituted hydrocarbylene or alkylene group, any suitable substituent may be present, such as for example a carboxy or amido substituent. The polyol of formula (IA) may have more than 2 hydroxy groups and the group R2 may be a hydroxy substituted alkylene group. Each hydroxy substituted alkylene group R2 may have 1,2 or more hydroxy groups. Each hydroxy substituted alkylene group R2 may preferably have 1 hydroxy group. The polyol of formula (IA) may have 2 hydroxy groups and the group R2 may be an optionally substituted alkylene group wherein the optional substituent is not hydroxy. The polyol of formula (I) or of formula (IA) may be a sugar derived compound in which R1 or R2 includes one or more hydroxy residues. The or each R1 or R2 may represent a cyclic alkylene unit. One or more heteroatoms (for example oxygen atoms) may be present in the cyclic alkylene unit. For example the unit may contain an ether linkage. Suitably the or each R1 or R2 may be one or more saccharide units or may be substituted with one or more saccharide units. Suitably the or each R1 or R2 may be an unsubstituted alkylene group. Preferably the or each R1 or R2 is an optionally substituted alkylene group having from 1 to 50, such as from 1 to 40, preferably from 1 to 30, more preferably from 1 to 20, suitably from 1 to 12 or from 1 to 10, for example from 2 to 6, carbon atoms. Preferably the or each R1 or R2 is an unsubstituted alkylene group having from 1 to 50, preferably from 1 to 20, more preferably from 1 to 12 or from 1 to 10, suitably from 2 to 6 carbon atoms. Each R1 or R2 may be straight chained or branched. Suitably the or each R1 or R2 may be an ethylene, propylene, butylene, pentylene, hexylene or dodecylene group. When R1 or R2 has more than 2 carbon atoms any isomer may be present. Preferably R1 or R2 is an ethylene or a propylene group, most preferably an ethylene group. When q is 1, R2 may be a group of formula (CH2)x wherein x is from 2 to 12, preferably from 3 to 12. Suitably when q is 1, R2 may be a straight chain or branched optionally substituted alkylene group and the polyol may be selected from ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,6-hexanediol, 1,12-dodecanediol, trimethylolpropane, 2-ethyl-1,3,-hexanediol, 2,2-diethyl-1,3-propanediol, 2,2-bis(hydroxymethyl)propionic acid, pentaerythritol, sorbitol, xylitol, glycerol and neopentyl glycol (preferably selected from 1,6-hexanediol, trimethylolpropane, 2,2-bis(hydroxymethyl)propionic acid, sorbitol, xylitol and glycerol). Suitably when q is 1, R2 may be a straight chain or branched alkylene group having from 2 to 12, preferably from 3 to 12, carbon atoms. Suitable compounds of this type include ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,6-hexanediol, 1,12-dodecanediol, trimethylolpropane, 2-ethyl-1,3,-hexanediol, 2,2-diethyl-1,3-propanediol, pentaerythritol and neopentyl glycol (preferably selected from 1,6-hexanediol and trimethylolpropane). Suitably when q is 1, R2 may be a branched alkylene group having from 2 to 12, preferably from 3 to 12, carbon atoms. Suitable compounds of this type include propylene glycol, 1,2-butanediol, 1,3-butanediol, trimethylolpropane, 2-ethyl-1,3,-hexanediol, 2,2-diethyl-1,3-propanediol, pentaerythritol and neopentyl glycol (preferably trimethylolpropane). Suitably when q is 2 or more, the or each R2 may be a straight chain or branched alkylene group and the polyol may, for example, be selected from diglycerol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol and polypropylene glycol (especially from polyethylene glycol and polypropylene glycol, most especially polypropylene glycol). Suitably when q is 2 or more, the or each R2 may be a straight chain or branched alkylene group having from 2 to 4, preferably 2 or 3, carbon atoms. Suitable compounds of this type include diethylene glycol, triethylene glycol, di propylene glycol, tripropylene glycol, polyethylene glycol (PEG), for example having a number average molecular weight of from 150 to 6000, and polypropylene glycol (PPG), for example having a number average molecular weight of from 400 to 2000. Suitable polyols may include one or more of PEG 6000, PEG 1500, PEG 1000, PEG 600, PEG 400, PEG 200, PPG 2000, PPG 1000 and PPG 425. The or each R1 or R2 may comprise a mixture of isomers. For example when R1 or R2 is propylene, the polyol may include moieties -CH2CH(CH3)- and -CH(CH3)CH2- in any order within the chain. R1 or R2 may comprise a mixture of different groups for example ethylene, propylene or butylene units. The or each R2 may be an ethylene, propylene or butylene group. For example, the or each R2 may be an n-propylene or n-butylene group or an isopropylene or isobutylene group. For example the or each R11 may be -CH2CH2-, -CH2CH(CH3)-, - CH(CH3)CH2-, CH2CH2CH2-, -CH2C(CH3)2-, -CH2CH2CH2CH2-, -CH(CH3)CH(CH3)- or-CH2CH(CH2CH3)-. Preferably R2 is selected from -CH2CH2-, -CH2CH2CH2-, -CH(CH3)CH2- or -CH2CH(OH)CH2, more preferably from -CH2CH2-, and-CH2CH2CH2-. Suitably the polyol of formula (I) or (IA) may be a sugar derived alcohol, for example, xylitol, glucose, fructose, trehalose, sucrose, lactose, maltose or sorbitol. Preferably, the polyol of formula (I) or (IA) may be a sugar derived alcohol selected from glucose, fructose, trehalose, sucrose, lactose, maltose or sorbitol, preferably from sucrose, lactose, maltose, or sorbitol, more preferably from sorbitol or sucrose. Most preferably the polyol of formula (I) or (IA) may be a sugar derived alcohol that is sucrose. Suitably the polyol of formula (I) may be selected from one or more of 1,12-dodecanediol, 1,6-hexanediol, trimethylolpropane, neopentyl glycol, polyethylene glycol (such as PEG 6000, PEG 1500, PEG 1000, PEG 600, PEG 400, PEG 200), polypropylene glycol (such as PPG 2000, PPG 1000, PPG 425, especially PPG 2000), sorbitol, trimethylolpropane and xylitol. Suitably, the polyol, for example of formula (I), may be an ester of glycerol (also known as a glyceride) and a hydroxycarboxylic acid. The ester of glycerol may be a mono-, di- or triglyceride, suitably a tri-glyceride. Suitably, the hydroxycarboxylic acid comprises one or more hydroxyl groups and one or more carboxylic acid groups. The hydroxycarboxylic acid may be a monocarboxylic acid comprising one or more hydroxyl groups. The hydroxycarboxylic acid may be of the formula R3COOH, wherein R3 is a hydroxyl-substituted hydrocarbyl group. R3 is suitably a hydroxy-substituted alkyl, alkenyl or alkaryl group, preferably a hydroxy-substituted alkyl or alkenyl group. R3 suitably comprises from 1 to 25 carbon atoms, preferably from 1 to 20 carbon atoms, more preferably from 1 to 17 carbon atoms. Suitably, the hydroxycarboxylic acid may be selected from glycolic acid, lactic acid, hydroxy butyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxystearic acid (preferably 12-hydroxystearic acid), 2,2-bis(hydroxymethyl)propionic acid, mandelic acid or ricinoleic acid. Preferably, the hydroxycarboxylic acid or the cyclic ester thereof may be selected from glycolic acid, mandelic acid, ricinoleic acid, malic acid, tartaric acid or citric acid. More preferably, the hydroxycarboxylic acid or the cyclic ester thereof is ricinoleic acid. Preferably, when the polyol is an ester of glycerol, the polyol may be a mono-, di- or tri-glyceride of ricinoleic acid. Most preferably, when the polyol is an ester of glycerol, the polyol may be a tri-glyceride of ricinoleic acid, such as castor oil. Suitable polyols may include one or more of an alkoxylated polyol, such as an alkoxylated polyol of formula (I) or (IA). By an alkoxylated polyol of formula (I) or (IA) we mean the reaction product of a polyol of formula (I) or (IA) and one or more alkylene oxides, such as ethylene oxide or propylene oxide. Such alkoxylated polyols may include polyoxyethylene (80) sorbitan monooleate (also known as Tween® 80) and 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate. Preferably, the or each polyol may be independently selected from castor oil, 1,6-hexanediol, sorbitol, neopentyl glycol and a polyalkylene glycol (such as PEG 200). When the or each polyol comprises carbon, hydrogen, oxygen and nitrogen atoms, the or each polyol may comprise two or more (such as 2 or 3) hydroxy groups and one or more (suitably one) amine groups. The amine groups may suitably be secondary or tertiary amines. Preferably the amine groups are tertiary amines. These polyols may be referred to herein as nitrogen containing polyols. Preferably, the polyol is not sorbitan. For example, suitable nitrogen containing polyols may include one or more of a polyol of formula (II) or a derivative thereof: NR4R5R6 (II) wherein R4, R5 and R6 are each independently selected from hydrogen, hydroxyalkyl and hydrocarbyl, provided that at least two of R4, R5 and R6 represents a hydroxyalkyl group. Preferably, the at least two of R4, R5 and R6 that represent a hydroxyalkyl group are the same. For example, in the compounds of formula (II), R4 and R5 may each represent hydroxyalkyl and R6 may represent hydrogen, hydroxyalkyl or hydrocarbyl. In the formula (II), the hydroxyalkyl group may contain from 1 to 8, such as from 1 to 4, such as 2 or 3, carbon atoms. For example, each hydroxyalkyl group may be hydroxyethyl or hydroxypropyl, particularly hydroxyethyl. In the formula (II), the hydrocarbyl group (when present) may represent any suitable such group, such as an alkyl group, for example an alkyl group containing from 1 to 10, such as from 1 to 6 or from 1 to 4, carbon atoms. Thus, the hydrocarbyl group may represent a methyl, ethyl, propyl or butyl group (especially butyl or methyl, most especially methyl). For example, in the compounds of formula (II), R4 and R5 may each represent hydroxyalkyl and R6 may represent hydrogen, hydroxyalkyl or hydrocarbyl (especially hydrogen or hydrocarbyl, more especially hydrocarbyl). Preferably in the compounds of formula (II), R4 and R5 both represent hydroxyethyl and R6 represents hydrogen or hydrocarbyl, such as a hydrocarbyl group containing from 1 to 6, or from 1 to 4, carbon atoms. Preferably in the compounds of formula (II), R4 and R5 both represent hydroxyethyl and R6 represents hydrogen or an alkyl group containing from 1 to 6, or from 1 to 4, carbon atoms (especially methyl). Examples of suitable nitrogen containing polyols include N-methyl diethanolamine, N-butyl diethanolamine, triethanolamine and diethanolamine, and derivatives thereof. Preferred nitrogen containing polyols may include N-methyl diethanolamine and N-butyl diethanolamine (especially N-methyl diethanolamine), and derivatives thereof. References herein to nitrogen containing polyols include derivatives thereof, such as a corresponding quaternary compound. Thus, as example of a suitable derivative of a nitrogen containing polyol is tris(2-hydroxyalkyl)methylammonium compound, for example tris(2-hydroxyethyl)methylammonium methylsulfate, which is a quaternary ammonium salt of triethanolamine. Preferably, the or each nitrogen containing polyol may be independently selected from N-butyl diethanolamine, diethanolamine and N-methyl diethanolamine (especially N-methyl diethanolamine and N-butyl diethanolamine), and derivatives (for example quaternary ammonium salts) thereof. More preferably, the or each nitrogen containing polyol may be independently selected from N-butyl diethanolamine, diethanolamine and N-methyl diethanolamine (especially N-methyl diethanolamine and N-butyl diethanolamine). Further examples of suitable nitrogen containing polyols include those formed by reaction of a hydroxy substituted cyclic ester or cyclic carbonate, such as glycerol carbonate or gluconolactone, with a suitable primary or secondary amine compound, such as ethanolamine, dipropylamine, hexylamine, dodecylamine, phenethylamine, dipropylamine, ethylenediamine, or a polyether polyamine. Suitable polyether amines may include polyether monoamines (such as for example Jeffamine M-1000) and polyether polyamines (such as for example Jeffamine ED-600). As the skilled person would appreciate, the reaction of a hydroxy substituted cyclic ester or cyclic carbonate with a suitable primary or secondary amine compound will result in a ring opening reaction to form a compound such as a N-carbamoyl polyol or an amido polyol. The or each second reactant may be a polyol selected from one or more polyol of the formula (I) or (IA) as defined herein (including an ester of glycerol and a hydroxycarboxylic acid (such as castor oil)), one or more of an alkoxylated polyol of formula (I) or (IA) as defined herein, one or more nitrogen containing polyol as defined herein (including compounds of the formula (II)) and one or more polyol formed by reaction of a hydroxy substituted cyclic ester or cyclic carbonate with a suitable primary or secondary amine compound. Preferably, the or each second reactant may be a polyol selected from one or more polyol of the formula (I) or (IA) as defined herein (including an ester of glycerol and a hydroxycarboxylic acid (such as castor oil)), one or more of an alkoxylated polyol of formula (I) or (IA) as defined herein, one or more nitrogen containing polyol of the formula (II) as defined herein and one or more polyol formed by reaction of a hydroxy substituted cyclic ester or cyclic carbonate with a suitable primary or secondary amine compound. Preferably, the or each second reactant may be a polyol selected from one or more polyol of the formula (I) or (IA) as defined herein (including an ester of glycerol and a hydroxycarboxylic acid (such as castor oil)), one or more of an alkoxylated polyol of formula (I) or (IA) as defined herein, and one or more nitrogen containing polyol of the formula (II) as defined herein More preferably, the or each second reactant may be a polyol selected from one or more polyol of the formula (I) or (IA) as defined herein (such as an ester of glycerol and a hydroxycarboxylic acid , for example castor oil), and one or more nitrogen containing polyol of the formula (II) as defined herein. In one embodiment, the or each second reactant may be a polyol selected from one or more polyol of the formula (I) or (IA) as defined herein, such as an ester of glycerol and a hydroxycarboxylic acid (for example castor oil) / In another embodiment, the or each second reactant may be a polyol selected from one or more of an alkoxylated polyol of formula (I) or (IA) as defined herein. In one embodiment, the or each second reactant may be a polyol selected from one or more polyol of the formula (I) or (IA) as defined herein, such as an ester of glycerol and a hydroxycarboxylic acid (for example castor oil) and from one or more of an alkoxylated polyol of formula (I) or (IA) as defined herein. In another embodiment, the or each second reactant may be a polyol selected from one or more nitrogen containing polyol as defined herein (including compounds of the formula (II)). In another embodiment, the or each second reactant may be a polyol selected from one or more polyol formed by reaction of a hydroxy substituted cyclic ester or cyclic carbonate with a suitable primary or secondary amine compound. In one embodiment, the polyol ester may be the reaction product of reactants comprising one (i.e. a single) monocarboxylic acid or ester thereof and one (i.e. a single) polyol. In other embodiments, the polyol ester may be the reaction product of reactants comprising two different monocarboxylic acids or esters thereof and one (i.e. a single) polyol, or the polyol ester may be the reaction product of reactants comprising one (i.e. a single) monocarboxylic acid or ester thereof and two different polyols. The combined amount of the one or more first reactants and the one or more second reactants may be at least 50 mol%, suitably at least 75 mol%, preferably at least 90 mol%, for example at least 95 wt% of the reactants that are reacted to obtain the polyol ester. The polyol ester for use herein is suitably the reaction product of no more than four different reactants. Preferably, the polyol ester is the reaction product of no more than three different reactants. For example, the polyol ester may be the reaction product of two different first reactants and one second reactant as disclosed herein. In some preferred embodiments, the polyol ester is the reaction product of only two different reactants, i.e. one first reactant and one second reactant as disclosed herein (and no further reactants). In one embodiment, the polyol ester may be the reaction product of reactants consisting essentially of or consisting of one (i.e. a single) monocarboxylic acid or ester thereof and one (i.e. a single) polyol. In other embodiments, the polyol ester may be the reaction product of reactants consisting essentially of or consisting of two different monocarboxylic acids or esters thereof and one (i.e. a single) polyol, or the polyol ester may be the reaction product of reactants consisting essentially of or consisting of one (i.e. a single) monocarboxylic acid or ester thereof and two different polyols. The polyol esters may be prepared from the first and second reactants by any suitable method, as would be known to the person skilled in the art. The esterification reaction will typically be conducted in the presence of a suitable polyol esterification catalyst, such as tin(ll) ethylhexanoate, tin(ll) oxalate, p-toluenesulfonic acid, methanesulfonic acid, or sulfuric acid. The reaction may be carried out for any suitable length of time, such as at least 1 hour, preferably at least 3 hours, for example at least 5 hours. The reaction may be carried out at any suitable temperature, such as from 50 to 300°C, preferably from 100 to 200°C. References herein to a reactant are intended to refer to the compounds that react to form the polyol and are not intended to include a catalyst used in the reaction. Suitable molar ratios of the first and second reactants may be used to prepare the polyol esters. Suitably, the polyol ester is not further reacted after the reaction of the reactants. The one or more monocarboxylic acids or esters thereof and the one or more polyols may be reacted in a molar ratio of from 1:1 to 10:1, such as from 1:1 to 8:1, for example from 1:1 to 6:1. Ratios refer to the total amounts of monocarboxylic acids or esters thereof or polyols if more than one monocarboxylic acid or ester thereof or polyol is present. The one or more monocarboxylic acids or esters thereof and the one or more polyols may be reacted in a molar ratio of from 0.5:1 to 1.5:1, such as a molar ratio of 1:1. The one or more monocarboxylic acids or esters thereof and the one or more polyols may be reacted in a molar ratio of from 1.5:1 to 2.5:1, such as a molar ratio of 2:1. The one or more monocarboxylic acids or esters thereof and the one or more polyols may be reacted in a molar ratio of from 2.5:1 to 3.5:1, such as a molar ratio of 3:1. The one or more monocarboxylic acids or esters thereof and the one or more polyols may be reacted in a molar ratio of from 3.5:1 to 4.5:1, such as a molar ratio of 4:1. The one or more monocarboxylic acids or esters thereof and the one or more polyols may be reacted in a molar ratio of from 5.5:1 to 6.5:1, such as a molar ratio of 6:1. Suitably, at least one of the monocarboxylic acids or esters thereof may be a fatty acid having from 6 to 28 carbon atoms, such as from 10 to 22 carbon atoms, or an ester thereof. At least one of the monocarboxylic acids or esters thereof may be a saturated fatty acid having from 6 to 28 carbon atoms, such as from 10 to 22 carbon atoms, or an ester thereof. The polyol ester may be the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a fatty acid having from 6 to 28 carbon atoms or a methyl ester thereof; and the or each second reactant is a polyol selected from an ester of glycerol and a hydroxycarboxylic acid (such as castor oil); an alkoxylated polyol (such as Tween 80); a nitrogen containing polyol; and a polyol of formula (IA) wherein each R2 is independently an optionally substituted alkylene group and q is an integer of at least 1. The polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a fatty acid having from 6 to 28 carbon atoms or a methyl ester thereof; and the or each second reactant is a polyol selected from an ester of glycerol and a hydroxycarboxylic acid (such as castor oil), an alkoxylated polyol (such as Tween 80), a nitrogen containing polyol, and a polyol of formula (IA) wherein each R2 is independently an optionally substituted alkylene group and q is an integer of at least 1. The polyol ester may be the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a fatty acid having from 6 to 28 carbon atoms or a methyl ester thereof; and the or each second reactant is a polyol selected from an ester of glycerol and a hydroxycarboxylic acid (such as castor oil); a nitrogen containing polyol; and a polyol of formula (IA) wherein each R2 is independently an optionally substituted alkylene group ora saccharide unit and q is an integer of at least 1. The polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a fatty acid having from 6 to 28 carbon atoms or a methyl ester thereof; and the or each second reactant is a polyol selected from an ester of glycerol and a hydroxycarboxylic acid (such as castor oil), a nitrogen containing polyol, and a polyol of formula (IA) wherein each R2 is independently an optionally substituted alkylene group or a saccharide unit and q is an integer of at least 1. The polyol ester may be the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a saturated fatty acid having from 6 to 28 carbon atoms or a methyl ester thereof; and the or each second reactant is a polyol selected from an ester of glycerol and a hydroxycarboxylic acid (such as castor oil), an alkoxylated polyol (such as Tween 80), a nitrogen containing polyol, and a polyol of formula (IA) wherein each R2 is independently an optionally substituted alkylene group and q is an integer of at least 1. The polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester that is a saturated fatty acid having from 6 to 28 carbon atoms or a methyl ester thereof; and the or each second reactant is a polyol selected from an ester of glycerol and a hydroxycarboxylic acid (such as castor oil), an alkoxylated polyol (such as Tween 80), a nitrogen containing polyol, and a polyol of formula (IA) wherein each R2 is independently an optionally substituted alkylene group and q is an integer of at least 1. The polyol ester may be the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a fatty acid having from 6 to 28 carbon atoms or a methyl ester thereof; and the or each second reactant is a polyol selected from an alkoxylated polyol (such as Tween 80), a nitrogen containing polyol, and a polyol of formula (IA) wherein each R2 is independently an optionally substituted alkylene group and q is an integer of at least 1. The polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a fatty acid having from 6 to 28 carbon atoms or a methyl ester thereof; and the or each second reactant is a polyol selected from an alkoxylated polyol (such as Tween 80), a nitrogen containing polyol, and a polyol of formula (IA) wherein each R2 is independently an optionally substituted alkylene group and q is an integer of at least 1. Suitably, the polyol ester may be the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof selected from hexanoic acid, decanoic acid, lauric acid, stearic acid, erucic acid, methyl octanoate, methyl decanoate, methyl laurate, methyl stearate, methyl linoleate, or methyl erucate; and the or each second reactant is a polyol selected from castor oil, Tween 80, trimethylolpropane, sucrose, lactose, maltose, sorbitol, xylitol, N-methyldiethanolamine, glycerol, 2,2-bis(hydroxymethyl) propionic acid, PPG 2000, or 1,6-hexanediol. Suitably, the polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof selected from hexanoic acid, decanoic acid, lauric acid, stearic acid, erucic acid, methyl octanoate, methyl decanoate, methyl laurate, methyl stearate, methyl linoleate, or methyl erucate; and the or each second reactant is a polyol selected from castor oil, Tween 80, trimethylolpropane, sucrose, lactose, maltose, sorbitol, xylitol, N-methyldiethanolamine, glycerol, 2,2-bis(hydroxymethyl) propionic acid, PPG 2000, or 1,6-hexanediol. Suitably, the polyol ester may be the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or esterthereof selected from hexanoic acid, lauric acid, stearic acid, erucic acid, methyl octanoate, methyl laurate, methyl oleate, methyl stearate, methyl linoleate, or methyl erucate; and the or each second reactant is a polyol selected from castor oil, Tween 80, trimethylolpropane, sucrose, lactose, maltose, sorbitol, xylitol, N-methyldiethanolamine, glycerol, 2,2-bis(hydroxymethyl) propionic acid, PPG 2000, or 1,6-hexanediol. Suitably, the polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or esterthereof selected from hexanoic acid, lauric acid, stearic acid, erucic acid, methyl octanoate, methyl laurate, methyl oleate, methyl stearate, methyl linoleate, or methyl erucate; and the or each second reactant is a polyol selected from castor oil, Tween 80, trimethylolpropane, sucrose, lactose, maltose, sorbitol, xylitol, N- methyldiethanolamine, glycerol, 2,2-bis(hydroxymethyl) propionic acid, PPG 2000, or 1,6-hexanediol. Suitably, the polyol ester may be the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof selected from hexanoic acid, decanoic acid, lauric acid, stearic acid, oleic acid, erucic acid, methyl octanoate, methyl decanoate, methyl laurate, methyl stearate, methyl oleate, methyl linoleate, and methyl erucate; and the or each second reactant is a polyol selected from Tween 80, trimethylolpropane, sucrose, lactose, maltose, sorbitol, xylitol, N-methyldiethanolamine, glycerol, 2,2-bis(hydroxymethyl) propionic acid, PPG 2000, and 1,6-hexanediol. Suitably, the polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof selected from hexanoic acid, decanoic acid, lauric acid, stearic acid, oleic acid, erucic acid, methyl octanoate, methyl decanoate, methyl laurate, methyl stearate, methyl oleate, methyl linoleate, or methyl erucate; and the or each second reactant is a polyol selected from Tween 80, trimethylolpropane, sucrose, lactose, maltose, sorbitol, xylitol, N-methyldiethanolamine, glycerol, 2,2-bis(hydroxymethyl) propionic acid, PPG 2000, or 1,6-hexanediol. Suitably, at least one of the monocarboxylic acids or esters thereof may be selected from decanoic acid, lauric acid, stearic acid, oleic acid, erucic acid, methyl decanoate, methyl laurate, methyl stearate, methyl oleate or methyl erucate. Suitably, at least one of the monocarboxylic acids or esters thereof may be selected from decanoic acid, lauric acid, stearic acid, erucic acid, methyl decanoate, methyl laurate, methyl stearate, or methyl erucate. Suitably, at least one of the polyols has at least 3 hydroxy groups, for example at least 4 hydroxy groups. At least one of the polyols may have from 3 to 8 hydroxy groups, for example from 4 to 8 hydroxy groups. Suitably, at least one of the polyols may be selected from an ester of glycerol and a hydroxycarboxylic acid (such as castor oil), an alkoxylated polyol (such as Tween 80), and a polyol of formula (IA) wherein each R2 is independently an optionally substituted alkylene group and q is an integer of at least 1, and wherein at least one R2 is a hydroxy-substituted alkylene group. Suitably, at least one of the polyols may be selected from an ester of glycerol and a hydroxycarboxylic acid (such as castor oil), and a polyol of formula (IA) wherein each R2 is independently an optionally substituted alkylene group and q is an integer of at least 1, and wherein at least one R2 is a hydroxy-substituted alkylene group. Suitably, at least one of the polyols may be selected from an alkoxylated polyol (such as Tween 80), and a polyol of formula (IA) wherein each R2 is independently an optionally substituted alkylene group and q is an integer of at least 1, and wherein at least one R2 is a hydroxysubstituted alkylene group. Suitably, at least one of the polyols may be selected from an ester of glycerol and a hydroxycarboxylic acid (such as castor oil), Tween 80, a sugar derived compound (such as sucrose, maltose or lactose including hydrates thereof), or trimethylolpropane. Suitably, at least one of the polyols may be selected from castor oil and a sugar derived compound (preferably sucrose). The polyol may be castor oil. When the polyol is castor oil, the one or more monocarboxylic acid or esters thereof and the polyol may be reacted in a molar ratio of from 0.5:1 to 1.5:1, preferably a molar ratio of 1:1. The polyol ester may be the reaction product of reactants comprising one or more first reactants and a second reactant, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a fatty acid having from 6 to 28 carbon atoms (such as from 10 to 22 carbon atoms) or a methyl ester thereof; and the second reactant is castor oil. The polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and a second reactant, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a fatty acid having from 6 to 28 carbon atoms (such as from 10 to 22 carbon atoms) or a methyl ester thereof; and the second reactant is castor oil. When the polyol has at least 4 hydroxy groups (such as when the polyol is Tween 80 or a sugar derived compound), the one or more monocarboxylic acid or esters thereof and the polyol may be reacted in a molar ratio of from 2:1 to 10:1, preferably a molar ratio of from 2:1 to 6:1. Suitably, at least one of the polyols may be selected from Tween 80, a sugar derived compound (such as sucrose, maltose or lactose including hydrates thereof), or trimethylolpropane. The polyol ester may be the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a fatty acid having from 10 to 22 carbon atoms or a methyl ester thereof; and the or each second reactant is a polyol having from 3 to 8 hydroxy groups. The polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a fatty acid having from 10 to 22 carbon atoms or a methyl ester thereof; and the or each second reactant is a polyol having from 3 to 8 hydroxy groups. The polyol ester may be the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a saturated fatty acid having from 10 to 22 carbon atoms or a methyl ester thereof; and the or each second reactant is a polyol having from 3 to 8 hydroxy groups. The polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a saturated fatty acid having from 10 to 22 carbon atoms or a methyl ester thereof; and the or each second reactant is a polyol having from 3 to 8 hydroxy groups. The polyol ester may be the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a fatty acid having from 10 to 22 carbon atoms or a methyl ester thereof; and the or each second reactant is a polyol having from 4 to 8 hydroxy groups. The polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof that is a fatty acid having from 10 to 22 carbon atoms or a methyl ester thereof; and the or each second reactant is a polyol having from 4 to 8 hydroxy groups. Suitably, the polyol ester may be the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof selected from decanoic acid, lauric acid, stearic acid, oleic acid, erucic acid, methyl decanoate, methyl laurate, methyl stearate, methyl oleate or methyl erucate; and the or each second reactant is a polyol selected from castor oil, Tween 80, trimethylolpropane, sucrose, lactose or maltose. Suitably, the polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof selected from decanoic acid, lauric acid, stearic acid, oleic acid, erucic acid, methyl decanoate, methyl laurate, methyl stearate, methyl oleate or methyl erucate; and the or each second reactant is a polyol selected from castor oil, Tween 80, trimethylolpropane, sucrose, lactose or maltose. Suitably, the polyol ester may be the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or esterthereof selected from decanoic acid, lauric acid, stearic acid, erucic acid, methyl decanoate, methyl laurate, methyl stearate, or methyl erucate; and the or each second reactant is a polyol selected from castor oil, Tween 80, trimethylolpropane, sucrose, lactose or maltose. Suitably, the polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or esterthereof selected from decanoic acid, lauric acid, stearic acid, erucic acid, methyl decanoate, methyl laurate, methyl stearate, or methyl erucate; and the or each second reactant is a polyol selected from castor oil, Tween 80, trimethylolpropane, sucrose, lactose or maltose. Suitably, the polyol ester may be the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or esterthereof selected from decanoic acid, lauric acid, stearic acid, oleic acid, erucic acid, methyl decanoate, methyl laurate, methyl stearate, methyl oleate or methyl erucate; and the or each second reactant is a polyol selected from Tween 80, trimethylolpropane, sucrose, lactose or maltose. Suitably, the polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or esterthereof selected from decanoic acid, lauric acid, stearic acid, oleic acid, erucic acid, methyl decanoate, methyl laurate, methyl stearate, methyl oleate or methyl erucate; and the or each second reactant is a polyol selected from Tween 80, trimethylolpropane, sucrose, lactose or maltose. Suitably, the polyol ester may be the reaction product of reactants comprising one or more first reactants and a second reactant, wherein the or each first reactant is a monocarboxylic acid or ester thereof selected from decanoic acid, lauric acid, stearic acid, oleic acid, erucic acid, methyl decanoate, methyl laurate, methyl stearate, methyl oleate or methyl erucate; and the second reactant is sucrose. Suitably, the polyol ester may be the reaction product of reactants consisting essentially of or consisting of one or more first reactants and a second reactant, wherein the or each first reactant is a monocarboxylic acid or ester thereof selected from decanoic acid, lauric acid, stearic acid, oleic acid, erucic acid, methyl decanoate, methyl laurate, methyl stearate, methyl oleate or methyl erucate; and the second reactant is sucrose. Preferably, the polyol ester is the reaction product of reactants comprising: (i) stearic acid and castor oil, preferably in a molar ratio of 1:1; (ii) methyl stearate and lactose (such as D-lactose monohydrate), preferably in a molar ratio of 4:1; (iii) methyl erucate and sucrose, preferably in a molar ratio of 4:1; (iv) lauric acid and Tween 80, preferably in a molar ratio of 3:1; (v) decanoic acid and trimethylolpropane, preferably in a molar ratio of 1:1; (vi) methyl oleate and sucrose, preferably in a molar ratio of 6:1; (vii) methyl erucate and sucrose, preferably in a molar ratio of 2:1; (viii) methyl laurate and sucrose, preferably in a molar ratio of 6:1; (ix) methyl oleate and maltose (such as D-maltose monohydrate), preferably in a molar ratio of 4:1; or (x) methyl erucate and maltose (such as D-maltose monohydrate), preferably in a molar ratio of 4:1. Preferably, the polyol ester is the reaction product of reactants consisting essentially of or consisting of: (i) stearic acid and castor oil, preferably in a molar ratio of 1:1; (ii) methyl stearate and lactose (such as D-lactose monohydrate), preferably in a molar ratio of 4:1; (iii) methyl erucate and sucrose, preferably in a molar ratio of 4:1; (iv) lauric acid and Tween 80, preferably in a molar ratio of 3:1; (v) decanoic acid and trimethylolpropane, preferably in a molar ratio of 1:1; (vi) methyl oleate and sucrose, preferably in a molar ratio of 6:1; (vii) methyl erucate and sucrose, preferably in a molar ratio of 2:1; (viii) methyl laurate and sucrose, preferably in a molar ratio of 6:1; (ix) methyl oleate and maltose (such as D-maltose monohydrate), preferably in a molar ratio of 4:1; or (x) methyl erucate and maltose (such as D-maltose monohydrate) , preferably in a molar ratio of 4:1. Preferably, the polyol ester is the reaction product of reactants comprising: (i) stearic acid and castor oil, preferably in a molar ratio of 1:1; (ii) lauric acid and Tween 80, preferably in a molar ratio of 3:1; or (iii) decanoic acid and trimethylolpropane, preferably in a molar ratio of 1:1. Preferably, the polyol ester is the reaction product of reactants consisting essentially of or consisting of: (i) stearic acid and castor oil, preferably in a molar ratio of 1:1; (ii) lauric acid and Tween 80, preferably in a molar ratio of 3:1; or (iii) decanoic acid and trimethylolpropane, preferably in a molar ratio of 1:1. Preferably, the polyol ester is the reaction product of reactants comprising methyl erucate and sucrose, preferably in a molar ratio of 2:1. Preferably, the polyol ester is the reaction product of reactants consisting essentially of or consisting of methyl erucate and sucrose, preferably in a molar ratio of 2:1. Preferably, the polyol ester is substantially free of silicon atoms. By substantially free of silicon atoms we mean that the polyol ester contains less than 1 wt% of silicon in the polyol ester, preferably less than 0.5 wt% of silicon in the polyol ester. More preferably, the polyol ester is free of silicon atoms, by which we mean that it is not possible to detect silicon in the polyol ester. Suitable methods of measuring the amount of silicon in a polyol ester are well known to those skilled in art and include elemental analysis and inductively coupled plasma (ICP) spectroscopy. Preferably, the polyol ester is substantially free of fluorine atoms. The polyol ester may be substantially free of halogen atoms. By substantially free of fluorine or halogen atoms we mean that the polyol ester contains less than 1 wt% of fluorine or halogen in the polyol ester, preferably less than 0.5 wt% of fluorine or halogen in the polyol ester. More preferably, the polyol ester is free of fluorine atoms. The polyol ester may be free of halogen atoms. By free of fluorine or halogen atoms we mean that it is not possible to detect fluorine or halogen in the polyol ester. Suitable methods of measuring the amount of fluorine or halogen in a polyol ester are well known to those skilled in art and include elemental analysis and inductively coupled plasma (ICP) spectroscopy. Preferably, the polyol ester is substantially free of quaternary ammonium moieties. By substantially free of quaternary ammonium moieties we mean that the polyol ester contains less than 1 wt% of quaternary nitrogen atoms in the polyol ester, preferably less than 0.5 wt% of quaternary nitrogen atoms in the polyol ester. More preferably, the polyol ester is free of quaternary ammonium moieties, by which we mean that it is not possible to detect quaternary ammonium moieties in the polyol ester. According to a second aspect of the invention, there is provided a concentrate composition comprising one or more polyol esters and optionally at least one solvent, wherein the concentrate composition comprises at least 20 wt% of the one or more polyol esters, and wherein the or each polyol ester is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof and the or each second reactant is a polyol. The concentrate composition may comprise at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt%, at least 70 wt%, or at least 80 wt% of the one or more polyol esters based on the total weight of the concentrate composition. The concentrate composition additionally may comprise 99 wt% or less, such as 95 wt% or less, for example 90 wt% or less of the one or more polyol esters based on the total weight of the concentrate composition. The concentrate composition may comprise from 20 to 99 wt%, preferably from 20 to 95 wt%, for example from 50 to 90 wt%, of the one or more polyol esters based on the total weight of the concentrate composition. References herein to the amount of polyol ester in the concentrate composition are intended to refer to the total of the or each polyol ester as defined herein that is included in the composition, i.e. based on the total weight of the concentrate composition. Suitably, the concentrate composition may be stable for at least 1 week, preferably at least 4 weeks, most preferably at least 8 weeks under ambient conditions (for example, at atmospheric pressure and at a temperature of 20°C). The stability of the concentrate composition may be determined visually. Suitably, the concentrate composition is unstable when it shows creaming, sedimentation, separation, ora combination thereof. Suitably, the concentrate composition may comprise at least 20 wt%, such as at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt%, at least 70 wt%, or at least 80 wt% of the polyol ester and the concentrate composition may be stable for at least 1 week, preferably at least 4 weeks or at least 8 weeks, most preferably at least 3,6, 12 or 24 months, under ambient conditions. Suitably, the concentrate composition may be flowable. The meaning of a “flowable” composition is well known to those skilled in the art. Typically, flowable compositions are pourable from a container at 20°C. Flowable compositions may be poured without needing to heat the composition above 20°C or manually scraping the composition. Suitably, the concentrate composition has a viscosity of 7,000 cP or less, preferably 3,500 cP or less at 20°C. Suitably, the concentrate composition may comprise at least 20 wt%, such as at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt%, at least 70 wt%, or at least 80 wt% of the polyol ester and the concentrate composition may be flowable. Suitably the concentrate composition of the second aspect is substantially free of silicon atoms. By substantially free of silicon atoms we mean that the composition contains less than 1 wt%, preferably less than 0.5 wt%, of silicon in the composition. More preferably, the composition is free of silicon atoms, by which we mean that it is not possible to detect silicon in the composition. Suitable methods of measuring the amount of silicon in a composition are well known to those skilled in art and include elemental analysis and inductively coupled plasma (ICP) spectroscopy. Features of the polyol ester, and of the first and second reactants, in relation to the second aspect of the invention are as set out herein in relation to the first aspect of the invention. The concentrate composition of the second aspect may optionally comprise any suitable solvent, such as for example a polar solvent, such as a polar protic solvent. Preferably, the concentrate composition comprises at least one solvent. The solvent may be an aqueous solvent. Thus, the concentrate composition may be an aqueous composition. The term “aqueous solvent” herein is considered to mean water or mixtures of water and at least one water miscible solvent. Water miscible solvents may include alcohols and substantially water-miscible organic solvents. Preferably the aqueous solvent is water. When the solvent is an aqueous solvent, the concentrate composition may be in the form of an emulsion. The solvent may be a non-aqueous solvent. The non-aqueous solvent suitably comprises an organic solvent, such as an alcohol. The non-aqueous solvent preferably does not comprise any surfactant. Suitable such alcohols for use in the solvent include monohydric alcohols, polyhydric alcohols, alkoxy alcohols and aryloxy alcohol. Suitable alcohols are monohydric alcohols, polyhydric alcohols and alkoxy alcohols. Preferred alcohols are miscible with water. Suitable simple monohydric alcohols include methanol, ethanol, isopropanol and butanol. The solvent may comprise a polyhydric alcohol or an alkoxyalcohol. Suitable alkoxy alcohols include diethylene glycol monobutyl ether, 3-methoxy-3-methyl-1-butanol and 2-butoxyethanol. Suitable aryloxy alcohols include 2-phenoxyethanol. Suitable polyhydric alcohols include glycerol, ethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol and 2-methylpentanediol. Suitable polyhydric alcohols include glycerol, ethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol and polypropylene glycol. Preferably, the non-aqueous solvent comprises a monohydric alcohol such as isopropanol. The concentrate composition may comprise at least 20 wt%, at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt% or at least 70 wt% of the at least one solvent (when present) based on the total weight of the concentrate composition. The concentrate composition additionally may comprise 80 wt% or less, such as 70 wt% or less, of the at least one solvent (when present) based on the total weight of the concentrate composition. The concentrate composition may comprise from 20 to 80 wt%, preferably from 20 to 75 wt%, such as from 50 to 80 wt% or from 50 to 75 wt%, of the at least one solvent (when present) based on the total weight of the concentrate composition. The concentrate composition of the second aspect may additionally comprise one or more surfactants (in particular when the solvent is an aqueous solvent). Preferably, the concentrate composition of the second aspect comprises one or more surfactants (in particular when the solvent is an aqueous solvent). Any suitable surfactant(s) may be included, such as for example one or more surfactants selected from anionic surfactants, cationic surfactants, non-ionic surfactants, and amphoteric or zwitterionic surfactants. One or more non-ionic surfactant(s) are preferred. The concentrate composition may comprise an anionic surfactant. Suitable anionic surfactants may include sulfate surfactants (such as mono- or di-alkyl sulfates or alkyl ether sulfates), sulfonate surfactants, alkyl ether carboxylate surfactants, sarcosinate surfactants, phosphate surfactants, succinate surfactants, sulfosuccinate surfactants, sulfoacetate surfactants, isethionate surfactants, taurate surfactants, amino acid surfactants such as glutamates and glycinates, lactylate surfactants, and fatty acid salts. Particularly exemplary salts of the above, where applicable, are the sodium, potassium, ammonium, magnesium and triethanolamine salts. The concentrate composition may comprise a cationic surfactant. The cationic surfactant may be an ammonium salt such as an alkyl trimethyl ammonium salt, a dialkyl dimethyl ammonium salt, an alkyl-(N-hydroxyethyl)-dimethyl ammonium salt, or an alkyldimethylbenzylammonium salt (i.e. a benzalkonium salt). The salt may be a halide, hydroxide, sulfate, hydrogensulfate, phosphate, or carboxylate salt. The salt is suitably a halide salt, such as a fluoride, chloride, or bromide salt. The salt may be a carboxylate salt, such as formate or acetate salt. Preferably, the salt is chloride. The concentrate composition may comprise a non-ionic surfactant. Suitable non-ionic surfactants for use herein include alcohol alkoxylates (such as alcohol ethoxylates, alcohol propoxylates, and ethylene oxide / propylene oxide copolymer derived surfactants), aliphatic esters, aromatic esters, sugar esters (such as sorbitan esters), glycolipids (such as sophorolipids, rhamnolipids and alkyl (poly)glycosides), fatty acid alkoxylates (such as fatty acid ethoxylates and fatty acid propoxylates), or polyethylene glycol esters (including partial esters), glycerol esters (including glycerol partial esters and glycerol triesters), fatty alcohols (such as cetearyl alcohol, lauryl alcohol, stearyl alcohol, behenyl alcohol), castor oil, alkanolamides, fatty amine alkoxylates (such as fatty amine ethoxylates and fatty amine propoxylates), fatty acid alkoxylates (such as fatty acid ethoxylates and fatty acid propoxylates), and polyglyceryl fatty acid esters. For example, suitable non-ionic surfactants for use herein may include castor oil, alcohol alkoxylates (such as alcohol ethoxylates, alcohol propoxylates, and ethylene oxide / propylene oxide copolymer derived surfactants), aliphatic esters, aromatic esters, sugar esters (such as sorbitan esters), alkyl (poly)glycosides, fatty acid alkoxylates (such as fatty acid ethoxylates and fatty acid propoxylates), or polyethylene glycol esters (including partial esters), glycerol esters (including glycerol partial esters and glycerol triesters), fatty alcohols (such as cetearyl alcohol, lauryl alcohol, stearyl alcohol, behenyl alcohol), and alkanolamides. Suitable fatty amine alkoxylates may include fatty amine ethoxylates and fatty amine propoxylates. Fatty amine ethoxylates are preferred. The fatty amine alkoxylates may be based on any suitable fatty alcohol. An example of a preferred fatty amine alkoxylate is a fatty amine ethoxylate such as Empilan® AMT 11, which is a fatty amine ethoxylate containing 11 moles of ethylene oxide. Preferably, the non-ionic surfactant may be selected from one or more of a sugar ester (such as a sorbitan ester) and a polyglyceryl fatty acid ester. Suitable sugar esters may include alkoxylated (such as ethoxylated) sugar esters. For example, the sugar ester may comprise an alkoxylated (such as ethoxylated) sugar ester of a fatty acid, such as oleic acid. Examples of preferred sugar ester surfactants include Tween® 20 and Tween® 80. The polyglyceryl fatty acid ester may have any suitable number of glyceryl repeat units and be based on any suitable fatty acid. An example of a preferred polyglyceryl fatty acid ester is polyglyceryl-10 caprylate. The concentrate composition may comprise an amphoteric or zwitterionic surfactant. The amphoteric or zwitterionic surfactant may be selected from betaines (such as alkyl betaines and alkylamidopropyl betaines), amphoacetates, diamphoacetates, and amine oxides (such as alkylamine oxides and alkylamidopropyl amine oxides). Suitable amphoteric or zwitterionic surfactants include lauryl betaine, cocamidopropyl betaine, sodium lauroamphoacetate, sodium cocoamphoacetate, disodium cocoamphodiacetate, lauramine oxide, C12-18 alkyldimethylamine oxide, myristamine oxide, and cocamidopropyl amine oxide. The one or more surfactants may be selected from a fatty alkyl amphoacetate (for example cocoyl amphoacetate, lauryl amphoacetate), an alkyl (poly)glycoside (for example lauryl glycoside), an acyl glycinate (for example cocoyl glycinate), a sulfosuccinate, an amphodiacetate and a fatty alcohol ether carboxylate (for example C8-12 alkyl ether (6-11 moles EO) carboxylate). The concentrate composition may comprise at least 1 wt%, at least 3 wt%, at least 5 wt%, of the one or more surfactants (when present) based on the total weight of the concentrate composition. The concentrate composition additionally may comprise 15 wt% or less, such as 10 wt% or less, of the one or more surfactants (when present) based on the total weight of the concentrate composition. The concentrate composition may comprise from 1 to 15 wt%, preferably from 3 to 10 wt% of the one or more surfactants (when present) based on the total weight of the concentrate composition. The concentrate composition of the second aspect may comprise the one or more surfactants in an amount of from 1 to 100 wt%, suitably from 5 to 50 wt%, preferably from 5 to 25 wt% or from 10 to 25 wt% based on the total weight of the one or more polyol esters. When the concentrate composition comprises the one or more polyol esters, the at least one solvent and the one or more surfactants, the composition may comprise: (i) from 20 to 60 wt% of the one or more polyol esters; (ii) from 35 to 60 wt% of the at least one solvent; and (iii) from 1 to 15 wt% of the one or more surfactants; based on the total weight of the concentrate composition. When the concentrate composition comprises the one or more polyol esters, the at least one solvent and the one or more surfactants, the composition may comprise: (i) from 20 to 45 wt% of the one or more polyol esters; (ii) from 50 to 75 wt% of the at least one solvent; and (iii) from 1 to 15 wt% of the one or more surfactants; based on the total weight of the concentrate composition. When the concentrate composition comprises the one or more polyol esters, the at least one solvent and the one or more surfactants, the composition may comprise: (i) from 20 to 40 wt% of the one or more polyol esters; (ii) from 50 to 75 wt% of the at least one solvent; and (iii) from 3 to 10 wt% of the one or more surfactants; based on the total weight of the concentrate composition. According to a third aspect of the invention, there is provided a use of a surfactant to emulsify at least one polyol ester in an aqueous concentrate composition, wherein the aqueous concentrate composition comprises at least 20 wt% of the one or more polyol esters, wherein the polyol ester is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof and the or each second reactant is polyol. The polyol ester referred to in relation to the third aspect may comprise the reaction product of reactants comprising one or more first reactants and one or more second reactants as defined herein. The polyol ester referred to in relation to the third aspect may be the reaction product of reactants consisting of one or more first reactants and one or more second reactants as defined herein. Features of the polyol ester, and of the first and second reactants, in relation to the third aspect of the invention are as set out herein in relation to the first aspect of the invention. Features of the surfactant in relation to the third aspect of the invention are as set out herein in relation to the second aspect of the invention. According to a fourth aspect of the invention, there is provided a method of emulsifying at least one polyol ester in an aqueous composition to make an aqueous polyol ester concentrate composition, wherein the aqueous polyol ester concentrate composition comprises at least 20 wt% of the one or more polyol esters, the method comprising admixing a surfactant with the polyol ester in an aqueous composition, wherein the polyol ester is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof and the or each second reactant is a polyol. The polyol ester referred to in relation to the fourth aspect may comprise the reaction product of reactants comprising one or more first reactants and one or more second reactants as defined herein. The polyol ester referred to in relation to the fourth aspect may be the reaction product of reactants consisting of one or more first reactants and one or more second reactants as defined herein. Features of the polyol ester, and of the first and second reactants, in relation to the fourth aspect of the invention are as set out herein in relation to the first aspect of the invention. Features of the surfactant in relation to the fourth aspect of the invention are as set out herein in relation to the second aspect of the invention. Examples The invention will now be further described with reference to the following non-limiting examples. Example 1 - general method for esterification of saccharides or polysaccharides (polyols) The saccharide or polysaccharide and monocarboxylic acid (or ester thereof) were dissolved in DMF (15 mL, for 10 mmol of saccharide or polysaccharide) in the presence of potassium carbonate (4 wt% relative to the total mass of reactants). The reaction mass was heated at 140°C for 8 hours, then DMF was removed in vacuo. The reaction product was redissolved in toluene, which was then removed in vacuo to provide the saccharide ester or polysaccharide ester. Example 2 - general method for esterification of polyols The monocarboxylic acid (or ester thereof) was combined with the polyol. Tin(ll) ethylhexanoate (0.5 wt% relative to the total weight of reactants) was added. The reaction mass was heated at 160°C for 6 hours. The resulting polyol ester was decanted from the reaction flask, and no further purification was carried out. Esters 1 to 32 were prepared, using the reactants, reaction stoichiometries and synthesis methods as set out in Table 1. Table 1 Compound Monocarboxylic acid (or ester) 1 Polyol 1 Prepared according to General Example Molar ratio of reactants 1 Lauric acid Castor oil 2 1 : 1 2 Lauric acid Castor oil 2 1 : 1 3 Hexanoic acid Castor oil 2 1 : 1 4 Hexanoic acid Castor oil 2 1 : 1 5 Hexanoic acid Castor oil 2 1 : 1 6 Stearic acid Castor oil 2 1 : 1 7 Stearic acid Castor oil 2 1 : 1 8 Methyl stearate D-Lactose monohydrate 1 4 : 1 9 Methyl erucate Sucrose 1 4 : 1 10 Hexanoic acid Tween 80 2 2 : 1 11 Lauric acid Tween 80 2 3 : 1 12 Decanoic acid Trimethylolpropane 2 1 : 1 13 Methyl oleate Sucrose 1 4 : 1 14 Methyl oleate Sucrose 1 6 : 1 15 Methyl erucate Sucrose 1 2 : 1 16 Methyl stearate Sucrose 1 2 : 1 17 Methyl laurate Sucrose 1 2 : 1 18 Methyl laurate Sucrose 1 6 : 1 19 Methyl oleate D-Lactose monohydrate 1 4 : 1 20 Methyl erucate D-Lactose monohydrate 1 4 : 1 21 Methyl oleate D-Maltose monohydrate 1 4 : 1 22 Methyl erucate D-Maltose monohydrate 1 4 : 1 23 Methyl stearate Sorbitol 2 4 : 1 24 Methyl octanoate Xylitol 2 4 : 1 25 Erucic acid Trimethylolpropane 2 3 : 1 26 Erucic acid N-methyl diethanolamine 2 1 : 1 27 Erucic acid Glycerol 2 3 : 1 28 Erucic acid 2,2- Bis(hydroxymethyl) propionic acid 2 1 : 1 29 Erucic acid PPG 2000 2 2 : 1 30 Erucic acid 1,6-Hexanediol 2 2 : 1 31 Methyl linoleate D-Maltose monohydrate 1 4 : 1 32 Methyl linoleate D-Lactose monohydrate 1 2 : 1 33 Methyl erucate Sucrose 1 6 : 1 34 Hexanoic acid Castor oil 2 3 : 1 35 Hexanoic acid Castor oil 2 2 : 1 Table 2 - abbreviations and chemical names PPG Poly(propylene glycol) DMF N,N-dimethylformamide Tween 80 An ethoxylated sorbitan ester based on a natural fatty acid (oleic acid) commercially available from Croda International Plc (Goole, UK) Example 3 - Preparation of further concentrated aqueous emulsions. A polyol ester (20 wt%), surfactant (5 wt% active unless otherwise indicated in table 3) and deionized water (balance, i.e. 75 wt% when surfactant is 5 wt%) were combined with a vortex mixer. The resulting mixture was left to stand at ambient temperature and the emulsion quality overtime was observed. The results are shown in Table 3. If the resulting mixture formed a stable emulsion, this is entered as “Stable”. If recorded as “Stable”, the stability time indicates the last time-point which was assessed. 15 Table 3 Polyol ester Surfactant Amount of surfactant (wt% active) Result Stability time 15 Polyglyceryl-10 caprylate 5 Stable 7 months 15 Tween 20* 5 Stable 7 months ’Tween 20 is an ethoxylated sorbitan ester based on a natural fatty acid (lauric acid) commercially available from Croda International Plc (Goole, UK). Unless otherwise stated herein, the reference to “liquid”, “gel” and “solid” refer to a state at 25 °C and standard pressure (101,325 Pa). Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All of the features disclosed in this specification (including any accompanying claims, and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A polyol ester, wherein the polyol ester is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof and the or each second reactant is a polyol.

2. The polyol ester according to claim 1, wherein the or each first reactant is a monocarboxylic acid that contains from 2 to 40 carbon atoms, suitably from 4 to 30 carbon atoms, preferably from 6 to 20 carbon atoms, for example from 8 to 18 carbon atoms, or an ester thereof.

3. The polyol ester according to any preceding claim, wherein the or each first reactant is a monocarboxylic acid selected from one more of hexanoic acid, octanoic acid, decanoic acid, lauric acid, myristic acid, myristoleic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, linolelaidic acid, arachidic acid, arachidonic acid, behenic acid, and erucic acid, or an ester thereof.

4. The polyol ester according to any preceding claim, wherein the or each first reactant is an ester of the monocarboxylic acid, preferably an alkyl ester, even more preferably a methyl ester.

5. The polyol ester according to any preceding claim, wherein the or each second reactant is a polyol having from 2 to 10, preferably from 2 to 6, hydroxy groups.

6. The polyol ester according to any preceding claim, wherein the or each second reactant is a polyol selected from one or more polyol of the formula (I) or (IA), one or more of an alkoxylated polyol of formula (I) or (IA), one or more nitrogen containing polyol, and one or more polyol formed by reaction of a hydroxy substituted cyclic ester or cyclic carbonate with a suitable primary or secondary amine compound, wherein the polyol of formula (I) is of the formula H-(OR1)P-OH, wherein each R1 is independently an optionally substituted hydrocarbylene group and p is an integer of at least 1, and wherein the polyol of formula (IA) is of the formula H-(OR2)q-OH, wherein each R2 is independently an optionally substituted alkylene group and q is an integer of at least 1.

7. The polyol ester according to any preceding claim, wherein the or each first reactant is a monocarboxylic acid or ester thereof selected from hexanoic acid, decanoic acid, lauric acid, stearic acid, oleic acid, erucic acid, methyl octanoate, methyl decanoate, methyl laurate, methyl stearate, methyl oleate, methyl linoleate, and methyl erucate; and the or each second reactant is a polyol selected from Tween 80, trimethylolpropane, sucrose, lactose, maltose, sorbitol,xylitol, N-methyldiethanolamine, glycerol, 2,2-bis(hydroxymethyl) propionic acid, PPG 2000, and 1,6-hexanediol.

8. The polyol ester according to any preceding claim, wherein the polyol ester is substantially free of silicon atoms.

9. A concentrate composition comprising one or more polyol esters and optionally at least one solvent, wherein the concentrate composition comprises at least 20 wt% of the one or more polyol esters, and wherein the or each polyol ester is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a monocarboxylic acid or ester thereof and the or each second reactant is a polyol.

10. The concentrate composition according to claim 9, wherein the composition comprises at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt%, at least 70 wt%, or at least 80 wt% of one or more polyol esters.

11. The concentrate composition according to claim 9 or 10, wherein the composition additionally comprises one or more surfactants.

12. The concentrate composition according to claim 11, wherein the one or more surfactants are independently selected from anionic surfactants, cationic surfactants, non-ionic surfactants, and amphoteric or zwitterionic surfactants.

13. The concentrate composition according to claim 12, wherein the one or more surfactants are independently selected from one or more of a fatty alkyl amphoacetate, an alkyl (poly)glycoside, an acyl glycinate, a sulfosuccinate, an amphodiacetate and a fatty alcohol ether carboxylate.

14. The concentrate composition according to any of claims 9 to 13, wherein the concentrate composition is stable for at least 3, 6, 12 or 24 months under ambient conditions.

15. The concentrate composition according to any of claims 9 to 14, wherein the concentrate composition is flowable.

16. The concentrate composition according to claim 15, wherein the concentrate composition has a viscosity of 7,000 cP or less, preferably 3,500 cP or less at 20°C.