Composition, method and use

Abstract

A polymerisation reaction mixture comprising at least one olefinic monomer and an antifoulant additive composition;wherein the antifoulant additive composition comprises:            (i) at least one polysulfone polymer;            (ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and            (iii) at least one substituted succinic acid or anhydride thereof. 

Description

Composition, method and use Field of the Invention The present invention relates to polymerisation reaction mixtures and polymer compositions comprising an antifoulant additive composition, in particular wherein the polymerisation reaction mixtures comprise an olefinic monomer. The present invention also relates to uses of the antifoulant additive composition and to methods of using the antifoulant additive composition. Background During manufacture of polyolefins and other polymers derived from olefinic monomers, growing polymer particles can adhere to each other and / or to surfaces of the reactor (resulting in reactor fouling). This can cause blockages in the reactor, which is particularly troublesome in continuous polymerisation processes. For example, reactor blockages can reduce the efficiency of the polymerisation reaction, such as by increasing resistance to the flow of reagents and products to and from the reactor (resulting in the need for increased pumping power) and / or decreasing heat transfer efficiency (making temperature control more difficult). In some cases, reactor blockages may cause eventual shutdown of the reactor. Product quality can also be impaired, as growing polymer particles that adhere to the surfaces of the reactor can become dislodged resulting in differing reaction times and products of differing molecular weights. It is desirable to provide antifoulant additive compositions which can reduce reactor fouling during polymer manufacture. Summary According to a first aspect of the present invention, there is provided a polymerisation reaction mixture comprising at least one olefinic monomer and an antifoulant additive composition;wherein the antifoulant additive composition comprises:(i) at least one polysulfone polymer;(ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and(iii) at least one substituted succinic acid or anhydride thereof. According to a second aspect of the present invention, there is provided method of reducing fouling during a polymerisation process, the method comprising:- providing a polymerisation reaction mixture comprising at least one olefinic monomer;- contacting an antifoulant additive composition with the polymerisation reaction mixture; and- carrying out a polymerisation process to obtain a polymer composition;wherein the antifoulant additive composition comprises:(i) at least one polysulfone polymer;(ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and(iii) at least one substituted succinic acid or anhydride thereof. According to a third aspect of the present invention, there is provided a use of an antifoulant additive composition to reduce fouling during a polymerisation process; wherein the antifoulant additive composition comprises:(i) at least one polysulfone polymer;(ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and(iii) at least one substituted succinic acid or anhydride thereof. According to a fourth aspect of the present invention, there is provided a polymer composition comprising a polymer and an antifoulant additive composition; wherein the polymer is derived from at least one olefinic monomer; andwherein the antifoulant additive composition comprises:(i) at least one polysulfone polymer;(ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and(iii) at least one substituted succinic acid or anhydride thereof. According to a fifth aspect of the present invention, there is provided an antifoulant additive composition; wherein the antifoulant additive composition comprises:(i) at least one polysulfone polymer;(ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and(iii) at least one substituted succinic acid or anhydride thereof. According to a sixth aspect of the present invention, there is provided a polymerisation additive system comprising a solid support, an antifoulant additive composition, and a polymerisation catalyst; wherein the antifoulant additive composition comprises:(i) at least one polysulfone polymer;(ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and(iii) at least one substituted succinic acid or anhydride thereof. Detailed description Unless otherwise stated, the following terms used in the specification and claims have the meanings set out below. The terms “alkyl” and “alkenyl” include both straight and branched chain alkyl and alkenyl groups respectively unless otherwise stated. The term “aryl” as used herein relates to an organic radical derived from an aromatic hydrocarbon by removal of one hydrogen, and includes any monocyclic, bicyclic or polycyclic carbon ring of up to 7 members in each ring, wherein at least one ring is aromatic. The term “aralkyl” as used herein relates to alkyl radicals substituted with an aryl group, wherein the aryl group is an organic radical derived from an aromatic hydrocarbon by removal of one hydrogen, and includes any monocyclic, bicyclic or polycyclic carbon ring of up to 7 members in each ring, wherein at least one ring is aromatic. An example of an aralkyl group is a benzyl group. 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, 2.75 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. Unless otherwise mentioned all references to ppm in this specification are to parts per million by weight. According to a first aspect of the present invention, there is provided a polymerisation reaction mixture comprising at least one olefinic monomer and an antifoulant additive composition;wherein the antifoulant additive composition comprises:(i) at least one polysulfone polymer;(ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and(iii) at least one substituted succinic acid or anhydride thereof. By “polymerisation reaction mixture” we mean a composition comprising components intended to polymerise to form a polymer. The polymerisation reaction mixture may comprise a suitable reaction medium, such as a suitable polymerisation solvent. The polymerisation reaction mixture may comprise a suitable catalyst for the polymerisation reaction. The polymerisation reaction mixture may comprise oligomeric and / or polymeric reaction products that are formed during the polymerisation reaction, such that references to a polymerisation reaction mixture are intended to include those reaction mixtures that comprise reagents and / or intermediate reaction products (such as oligomeric products) and / or the desired polymeric product. The polymerisation reaction mixture may comprise any suitable olefinic monomer. Olefinic monomers are precursors to polymers such as polyolefin polymers. In some embodiments, the polymerisation reaction mixture comprises only one olefinic monomer. In such embodiments, the polymerisation reaction may produce a homopolymer. In some embodiments, the at least one olefinic monomer may comprise at least two olefinic monomers. In such embodiments, the polymerisation reaction may produce a copolymer. Suitably, the at least one olefinic monomer is selected from the group consisting of α-olefins, internal olefins (for example β- or γ-olefins), conjugated dienes (for example isoprene or butadiene), styrene, substituted styrenes (for example α-methylstyrene, 4-chloromethylstyrene or divinylbenzene), acrolein, acrylonitrile, vinyl alcohol, vinyl esters (for example vinyl acetate), vinylpyrrolidone, vinylimidazole, vinylpyridine, maleic anhydride, (meth)acrylic acid, (meth)acrylic acid derivatives (for example (meth)acrylate esters and (meth)acrylamides), vinyl halides (for example vinyl chloride) and vinylidene halides (for example vinylidene fluoride). By “(meth)acrylic” we mean “acrylic or methacrylic”. The same applies to “(meth)acrylate”, “(meth)acrylamide”, etc. Suitably, the at least one olefinic monomer is selected from the group consisting of α-olefins, internal olefins (for example β- or γ-olefins), conjugated dienes (for example isoprene or butadiene), styrene, and substituted styrenes (for example α-methylstyrene, 4-chloromethylstyrene or divinylbenzene). Suitably, the at least one olefinic monomer comprises an olefin, preferably an a-olefin. Suitably, the at least one olefinic monomer comprises a C2 to C24 a-olefin, preferably a C2 to C12 a-olefin, for example a C2 to C6 a-olefin. The at least one olefinic monomer suitably comprises ethylene, propylene, butene, hexene, octene, or a mixture thereof. The at least one olefinic monomer preferably comprises ethylene, propylene, or a mixture thereof. The at least one olefinic monomer may comprise ethylene, propylene, or a mixture thereof, and a C4 to C24 a-olefin, such as a C4 to C12 a-olefin. Suitably, the at least one olefinic monomer comprises ethylene, propylene, or a mixture thereof in an amount of at least 60 wt%, such as at least 70 wt%, such as at least 80 wt%, for example at least 90 wt% based on the total weight of the at least one olefinic monomer. In some embodiments, the at least one olefinic monomer comprises ethylene, and optionally at least one further a-olefin. In some embodiments, the at least one olefinic monomer comprises propylene, and optionally at least one further a-olefin. In some embodiments, the at least one olefinic monomer comprises a mixture of ethylene and propylene. Suitably, the at least one olefinic monomer is at least one olefin, preferably at least one a-olefin. Suitably, the at least one olefinic monomer is at least one C2 to C24 a-olefin, preferably at least one C2 to C12 a-olefin, for example at least one C2 to C6 a-olefin. The at least one olefin suitably comprises ethylene, propylene, butene, hexene, octene, or a mixture thereof. The at least one olefin preferably comprises ethylene, propylene, or a mixture thereof. The at least one olefin may consist of ethylene, propylene, or a mixture thereof, and a C4 to C24 a-olefin, such as a C4 to C12 a-olefin. Suitably, the at least one olefin comprises ethylene, propylene, or a mixture thereof in an amount of at least 60 wt%, such as at least 70 wt%, such as at least 80 wt%, for example at least 90 wt% based on the total weight of the at least one olefin. In some embodiments, the at least one olefin comprises ethylene, and optionally at least one further a-olefin. In some embodiments, the at least one olefin comprises propylene, and optionally at least one further a-olefin. In some embodiments, the at least one olefin comprises a mixture of ethylene and propylene. The at least one olefinic monomer is suitably selected from the group consisting of ethylene, propylene, and mixtures thereof. The at least one olefinic monomer is preferably ethylene or propylene. The antifoulant additive composition used in the first aspect of the invention has surprisingly been found to reduce reactor fouling during the polymerisation of an olefinic monomer. The antifoulant additive composition may be used in amounts typical of an additive. The antifoulant additive composition may be used in an amount of from 1 to 300 ppm, such as from 1 to 100 ppm, such as from 1 to 60 ppm, such as from 1 to 50 ppm, for example from 1 to 20 ppm based on the total weight of the polymerisation reaction mixture. Preferably, the antifoulant additive composition is used in an amount of from 1 to 50 ppm based on the total weight of the polymerisation reaction mixture. The antifoulant additive composition comprises at least one polysulfone polymer (i). The antifoulant additive composition may comprise two or more polysulfone polymers (i). Any suitable polysulfone polymer (i) may be included in the antifoulant additive composition.  By a “polysulfone polymer” we mean a polymer that contains sulfone groups. The at least one polysulfone polymer (i) is suitably an alternating copolymer and may be prepared by copolymerisation of sulfur dioxide with an olefin, such as an α-olefin. Means for carrying out such reactions will be well known to those skilled in the art and are described, for example, in US3917466 and US4416668. For example, the at least one polysulfone polymer (i) may comprise a copolymer of sulfur dioxide with one or more α-olefins (which may be linear and / or branched) having from 2 to 36, for example from 2 to 24, such as from 6 to 12, carbon atoms.  Suitably, the at least one polysulfone polymer (i) may comprise a linear copolymer of sulfur dioxide with one or more α-olefins having from 2 to 36, for example from 2 to 24, such as from 6 to 12, carbon atoms. Examples of suitable α-olefins having from at least one 2 to 36 carbon atoms include ethene, propene, 1-butene, isobutene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 1-heneicosene, 1-docosene, 1-tricosene, 1-tetracosene and mixtures thereof. The at least one polysulfone polymer (i) may comprise a copolymer of sulfur dioxide with one or more linear α-olefins having from 6 to 12 carbon atoms. Examples of suitable linear α-olefins having from 6 to 12 carbon atoms include 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene and mixtures thereof. For example, the at least one polysulfone polymer (i) may comprise a copolymer comprising from 40 to 60 mol % of sulfone units (for example derived from sulfur dioxide) and from 60 to 40 mol % of olefin units (such as a-olefin units). For example, the at least one polysulfone polymer (i) may comprise a copolymer comprising from 50 to 60 mol % of sulfone units (for example derived from sulfur dioxide) and from 50 to 40 mol % of olefin units (such as a-olefin units). Suitably, the at least one polysulfone polymer (i) may comprise a copolymer of sulfur dioxide with a mixture of two or more α-olefins. The at least one polysulfone polymer (i) may comprise a copolymer of sulfur dioxide with one or more α-olefins (which may be linear and / or branched) and one or more additional monomers. Examples of additional monomers that can be included include vinyl alcohol, vinyl acetic acid, acrylic acid, methacrylic acid, maleic acid or fumaric acids and their esters and / or anhydrides. For example, the at least one polysulfone polymer (i) may comprise a copolymer comprising from 50 to 60mol % of sulfur dioxide or sulfone units, from 40 to 50 mol % of olefin units and from 0 to 10 mol % of units derived from an additional monomer. Suitably, the at least one polysulfone polymer (i) has a number-average molecular weight of from 2,000 to 1,000,000, especially from 4,000 to 100,000, in particular from 6,000 to 25,000. The polydispersity (PDI=Mw / Mn) is generally in the range from 1.1 to 30, especially from 1.5 to 20, in particular from 2 to 10, most preferably from 2.3 to 5.  Suitably, the at least one polysulfone polymer (i) is an alternating 1:1 copolymer in which one sulfone unit generally follows one olefin unit. The at least one polysulfone polymer (i) may also comprise sequences of two or more olefin units. Suitably, the at least one polysulfone polymer (i) comprises an alternating copolymer of one or more olefins (suitably a-olefins) and sulfone groups. For example, the at least one polysulfone polymer (i) may comprise a 1:1 alternating copolymer of sulfur dioxide and 1-decene, preferably having a number average molecular weight of about 10,000.  The antifoulant additive compositions may comprise the at least one polysulfone polymer (i) in any suitable amount. The at least one polysulfone polymer (i) may be present in the antifoulant additive composition in an amount of from 1 to 50 %, such as from 4 to 25 %, for example 5 to 22%, by weight based on the total weight of the antifoulant additive composition. The at least one polysulfone polymer (i) may comprise from 10 to 60 % by weight of the total active components in the antifoulant additive composition. By this we mean the % by weight based on the total active components, i.e. excluding solvent. Suitably, the weight ratio of the at least one polysulfone polymer (i) to the at least one polymeric polyamine or the sulfonic acid salt thereof (ii) is from 99:1 to 1:99, preferably from 19:1 to 1:19, for example from 9:1 to 1:9. Suitably, the weight ratio of the at least one polysulfone polymer (i) to the at least one substituted succinic acid or anhydride thereof (iii) is from 19:1 to 1:19, preferably from 9:1 to 1:9. The antifoulant additive composition comprises at least one polymeric polyamine, or a sulfonic acid salt thereof (ii). The antifoulant additive composition may comprise two or more polymeric polyamines or sulfonic acid salts thereof (ii). By a “polyamine” we mean a compound that comprises two or more amino groups. By “polymeric polyamine” we mean a compound that is a polymer or comprises a polymeric moiety, wherein the polymer or polymeric moiety comprises two or more amino groups. Any suitable polymeric polyamine may be included in the antifoulant additive composition.  The polymeric polyamine may comprise hydroxyl groups. Suitably, the polymeric polyamine is selected from the group consisting of:(a) a reaction product of a reaction mixture comprising epichlorohydrin and an aliphatic primary monoamine or a N-aliphatic hydrocarbyl alkylene diamine;(b) a reaction product of a reaction mixture comprising a polyethyleneimine and a polyisobutenylsuccinic anhydride;(c) a reaction product of a reaction mixture comprising an ethylene-vinyl acetate-amino(meth)acrylate terpolymer;(d) an olefin-maleic anhydride copolymer derivatised with a polyamine; and(e) a polyalkylene polyamine. Suitably, the polymeric polyamine is selected from the group consisting of:(a) a reaction product of a reaction mixture comprising epichlorohydrin and an aliphatic primary monoamine or a N-aliphatic hydrocarbyl alkylene diamine;(b) a reaction product of a reaction mixture comprising a polyethyleneimine and a polyisobutenylsuccinic anhydride;(c) a reaction product of a reaction mixture comprising an ethylene-vinyl acetate-amino(meth)acrylate terpolymer; and(d) an olefin-maleic anhydride copolymer derivatised with a polyamine. Suitably, the polymeric polyamine may be a reaction product of a reaction mixture comprising epichlorohydrin and an aliphatic primary monoamine or a N-aliphatic hydrocarbyl alkylene diamine (a). Means for carrying out such reactions will be well known to those skilled in the art and are described, for example, in US3917466.  Suitable aliphatic primary monoamines that can be used to prepare the polymeric polyamines by reaction with epichlorohydrin may have at least 8 carbons, such as from 8 to 18 or from 12 to 18 carbons. Suitable aliphatic primary monoamines that can be used to prepare the polymeric polyamines by reaction with epichlorohydrin may be straight chain or branched chain. Examples of suitable aliphatic primary monoamines that can be used to prepare the polymeric polyamines by reaction with epichlorohydrin include octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, nonadecylamine, eicosylamine, heneicosylamine, docosylamine, tricosylamine, tetracosylamine and the corresponding alkenyl analogs. Mixtures of two or more aliphatic primary monoamines may be used in the preparation of the polymeric polyamines. Commercially available sources of mixtures of two or more aliphatic hydrocarbyl groups that may be used to prepare the primary monoamines may include tall oil, tallow, soybean oil, coconut oil, cotton seed oil and other oils of vegetable and animal origin. Suitable N-aliphatic hydrocarbyl alkylene diamines that can be used to prepare the polymeric polyamines by reaction with epichlorohydrin include N-octyl, N-nonyl, N-decyl, N-undecyl, N-dodecyl, N-tridecyl, N-tetradecyl, N-pentadecyl, N-hexadecyl, N-heptadecyl, N-octadecyl, N-nonadecyl, N-eicosyl, N-heneicosyl, N-docosyl, N-tricosyl, N-tetracosyl diamines, as well as the corresponding N-alkenyl derivatives of ethylenediamine, propylenediamine, butylenediamine, pentylenediamine and hexylenediamine. Mixtures of two or more N-aliphatic hydrocarbyl alkylene diamines may be used in the preparation of the polymeric polyamines.  Suitable N-aliphatic hydrocarbyl alkylene diamines that can be used to prepare the polymeric polyamines by reaction with epichlorohydrin include N-aliphatic hydrocarbyl 1,3-propylenediamines. Examples of suitable N-aliphatic hydrocarbyl 1,3-propylenediamines include N-tallow-1,3-propylenediamine (wherein "tallow" represents predominantly mixtures of alkyl and alkenyl groups of 16 to 18 carbon atoms which can contain small amounts of alkyl and alkenyl groups of 14 carbon atoms), N-oleyl-1,3-propylenediamine and N-cocoyl-1,3-propylene diamine.  The reaction between the aliphatic primary monoamine or the N-aliphatic hydrocarbyl alkylene diamine amine and epichlorohydrin is suitably carried out in the presence of a solvent such as benzene, toluene or xylene which can also contain a proportion of protic cosolvent such as ethanol, isopropanol, or butanol. After the initial reaction between the amine and epichlorohydrin to form an aminochlorohydrin intermediate, the reaction mass is treated with a strong inorganic base, such as sodium, potassium or lithium hydroxide, to form an aminoepoxide, which under continued heating undergoes polymerisation to yield the desired product. Inorganic chloride formed in the reaction is removed by filtration. The solvent used to facilitate the reaction can be removed if desired, e.g. by distillation, but generally it is more convenient to use the polymeric polyamine as a solution. Suitably, the polymeric polyamine may be a reaction product of a reaction mixture comprising a polyethyleneimine and a polyisobutenylsuccinic anhydride (b). Suitably, the polymeric polyamine may be an ethylene-vinyl acetate-amino(meth)acrylate terpolymer (c). Suitably, the polymeric polyamine may be an olefin-maleic anhydride copolymer derivatised with a polyamine (d). An example of an olefin-maleic anhydride copolymer derivatised with a polyamine (d) may be an α-olefin-maleimide copolymer with at least one basic nitrogen atom. The structure and the preparation process for such α-olefin-maleimide copolymers with at least one basic nitrogen atom are as described in US4416668. For example, such α-olefin-maleimide copolymers are obtainable by free-radical polymerisation of one or more linear or branched α-olefins having from 6 to 50 carbon atoms with maleic anhydride and subsequent reaction with one or more aliphatic polyamines. The α-olefin-maleic anhydride copolymers and the α-olefin-maleimide copolymers prepared therefrom may be 1:1 copolymers alternating in the main polymer chain, wherein one maleic acid unit always follows one α-olefin unit. Comb structures generally arise due to the relatively long-chain branched or linear hydrocarbon radicals.  Suitable α-olefins for preparing the α-olefin-maleimide copolymers may include 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octa-decene, 1-nonadecene, 1-eicosene, 1-heneicosene, 1-docosene, 1-tricosene, 1-tetracosene, 1-triacontene, 1-tetracontene, 1-pentacontene and mixtures thereof. For example, linear α-olefins having from 12 to 30, for example 16 to 24, carbon atoms, and mixtures thereof may be preferred. Methods for carrying out free-radical polymerisation of the α-olefins with maleic anhydride will be well known to those skilled in the art. For example, well known free-radical initiators may be used, such as those based on peroxides or azo compounds, for example di-tert-butyl peroxide, tert-butyl peroxypivalate or azobisisobutyronitrile. Suitable temperature and pressure ranges are well known, such as temperatures of from 50 to 150° C at standard pressure. The reactions are suitably performed in solvents such as aromatic hydrocarbons.  Following polymerisation, the resulting α-olefin-maleic anhydride copolymers are reacted with one or more aliphatic polyamines to give the corresponding imide. Polyamines with a primary amino group are required for the imide formation, and at least one further primary, secondary or tertiary amino group for the basic nitrogen atom. Examples of suitable polyamines include ethylenediamine, 1,3-propylenediamine, 3-(N,N-dimethylamino)propylamine (DMAPA), bis[3- (N,N-dimethylamino)propyl]amine (bis-DMAPA), N-tallow-1,3-propylenediamine and N-oleyl-1,3-propylenediamine. Methods for preparing the imide compounds will be well known to those skilled in the art.  Suitable olefin-maleic anhydride copolymers derivatised with a polyamine (d) may have a number average molecular weight Mn of from 500 to 50,000, for example from 1,000 to 10,000.  Suitably, the polymeric polyamine may be a polyalkylene polyamine (e). Polyalkylene polyamines (e) may contain branching, or even be dendrimeric in nature, and may comprise primary, secondary and tertiary amino groups. For example, a suitable polyalkylene polyamine (e) may comprise a polyethylene polyamine. Polyethylene polyamines (e) may consist of linear or branched oligomers or polymers of aziridine. Oligomeric polyethylene polyamines may be linear and comprise primary or secondary amino groups. Examples of suitable polyethylene polyamines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and hexaethyleneheptamine. A preferred polyethylene polyamine comprises tetraethylenepentamine. The sulfonic acid salt of the polymeric polyamine is formed from a polymeric amine as described herein and a sulfonic acid. Suitable sulfonic acids may have from 6 to 40, such as from 8 to 32 or from 10 to 24, carbon atoms. For example, suitable sulfonic acids may comprise optionally substituted alkyl or alkenyl radicals (for example n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, 2-propylheptyl, n-undecyl, n-dodecyl, n-tridecyl, isotridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, n-eicosyl, n-heneicosyl, n-docosyl, n-tricosyl, n-tetracosyl, oleyl, linolyl or linolenyl), optionally substituted cycloalkyl radicals (for example cyclohexyl, methyl-cyclohexyl or dimethylcyclohexyl), optionally substituted aryl radicals (for example phenyl or naphthyl, or tolyl, xylyl, n-nonylphenyl, n-decylphenyl, n-dodecylphenyl, isotridecylphenyl, n-nonylnaphthyl, di-n-nonyl-naphthyl, n-decylnaphthyl, di-n-decylnaphthyl, n-dodecylnaphthyl, di-n-dodecylnaphthyl, isotridecylnaphthyl or diisotridecylnaphthyl), aralkyl radicals (for example benzyl or 2-phenylethyl). In the monosubstituted phenyl radicals, the alkyl groups may be in the ortho, meta or para position to the sulfonic acid group, with the para position being preferred.  Examples of suitable sulfonic acids include n-nonylbenzenesulfonic acid, n-decyl-benzenesulfonic acid, n-dodecylbenzenesulfonic acid, isotridecylbenzenesulfonic acid, n-nonylnaphthylsulfonic acid, di-n-nonylnaphthylsulfonic acid, n-decylnaphthylsulfonic acid, di-n-decylnaphthylsulfonic acid, n-dodecylnaphthylsulfonic acid, di-n-dodecyl-naphthylsulfonic acid, isotridecylnaphthylsulfonic acid and diisotridecylnaphthyl sulfonic acid. Preferred sulfonic acid compounds are n-dodecylbenzenesulfonic acid and di-n-nonylnaphthylsulfonic acid. In some embodiments, component (ii) of the antifoulant additive composition is the sulfonic acid salt of the polymeric polyamine. In some embodiments, component (ii) of the antifoulant additive composition is the polymeric polyamine (i.e. in the form of a free base). In some embodiments, component (ii) of the antifoulant additive composition comprises a mixture of the polymeric polyamine (i.e. free base) and a sulfonic acid salt thereof. The weight ratio of the polymeric polyamine to the sulfonic acid salt thereof may be from 1:99 to 99:1. In some embodiments, the weight ratio of the polymeric polyamine to the sulfonic acid salt thereof may be up to 50:1. such as up to 1:1, for example up to 1:50. In some embodiments, the weight ratio of the polymeric polyamine to the sulfonic acid salt thereof may be at least 1:50, such as at least 1:1, for example at least 50:1. The antifoulant additive composition may comprise the at least one polymeric polyamine or the sulfonic acid salt thereof (ii) in any suitable amount. The at least one polymeric polyamine or the sulfonic acid salt thereof (ii) may be included in the antifoulant additive composition in an amount of from 1 to 50%, such as from 5 to 25 %, for example from 6 to 22%, by weight based on the total weight of the antifoulant additive composition. The at least one polymeric polyamine or the sulfonic acid salt thereof (ii) may comprise from 15 to 50 % by weight of the total active components in the antifoulant additive composition. By this we mean the % by weight based on the total active components, i.e. excluding solvent. Suitably, the weight ratio of the at least one polymeric polyamine or the sulfonic acid salt thereof (ii) to the at least one substituted succinic acid or anhydride thereof (iii) is from 19:1 to 1:19, preferably from 9:1 to 1:9. In some embodiments, the antifoulant additive composition is substantially free of sulfonic acids or salts thereof, such as sulfonic acid salts of polymeric polyamines. By “substantially free” of sulfonic acids or salts thereof we mean that the antifoulant additive composition contains less than 10,000, preferably less than 1,000, more preferably less than 100, parts per million (ppm) of sulfonic acids or salts thereof. In some embodiments, the polymerisation reaction mixture is substantially free of sulfonic acids or salts thereof, such as sulfonic acid salts of polymeric polyamines. By “substantially free” of sulfonic acids or salts thereof we mean that the polymerisation reactive mixture contains less than 3, preferably less than 1, more preferably less than 0.1, parts per million (ppm) of sulfonic acids or salts thereof. The antifoulant additive composition comprises at least one substituted succinic acid or anhydride thereof (iii). The antifoulant additive composition may comprise two or more substituted succinic acids or anhydrides thereof (iii). Any suitable substituted succinic acid or anhydride thereof may be included in the antifoulant additive composition. By “substituted succinic acid or anhydride thereof” we also mean to refer to polymers comprising a succinic acid or succinic anhydride moiety as a repeat unit. The substituted succinic acid or anhydride thereof may be of formula (A1) or (B1):(A1) (B1) wherein Ra and Rb independently represent hydrogen or an optionally substituted hydrocarbyl group, provided that Ra and Rb are not both hydrogen. For example, Ra and Rb may independently represent an optionally substituted C1 to C500 alkyl or alkenyl group, such as a C2 to C100 alkyl or alkenyl group, preferably a C6 to C50 alkyl or alkenyl group, preferably a C8 to C40 alkyl or alkenyl group, more preferably a C8 to C38 alkyl or alkenyl group. Ra and Rb may independently represent a group R1 as defined further herein. Preferably, one of Ra and Rb represents a group R1 and the other represents hydrogen. Ra and Rb may independently represent a residue of an olefin-maleic acid copolymer or anhydride thereof. Preferably, both of Ra and Rb independently represent a residue of an olefin-maleic acid copolymer or anhydride thereof. In such embodiments, Ra and Rb may independently represent a substituted alkyl group, preferably an alkyl group substituted at the β-position. The alkyl group is suitably substituted by a residue of an olefin-maleic acid copolymer or anhydride thereof. Suitably, the at least one substituted succinic acid or anhydride thereof (iii) is selected from the group consisting of:(a) a hydrocarbyl substituted succinic acid or anhydride thereof; and(b) an olefin-maleic acid copolymer or anhydride thereof. The at least one substituted succinic acid or anhydride thereof (iii) may comprise at least one hydrocarbyl substituted succinic acid or anhydride thereof (a). Any suitable hydrocarbyl substituted succinic acid or anhydride thereof may be used. For example, the hydrocarbyl substituted succinic acid or anhydride thereof (a) may be of formula (A2) or (B2):(A2) (B2) wherein R1 represents an optionally substituted hydrocarbyl group, for example an optionally substituted alkyl or alkenyl group. When R1 is an optionally substituted alkyl or alkenyl group, the alkyl or alkenyl group may be linear or branched. Preferably, the alkyl or alkenyl group is branched. For example, R1 may represent an optionally substituted C1 to C500 alkyl or alkenyl group, such as a C2 to C100 alkyl or alkenyl group, preferably a C6 to C50 alkyl or alkenyl group, preferably a C8 to C40 alkyl or alkenyl group, more preferably a C8 to C38 alkyl or alkenyl group. For example, R1 may represent an optionally substituted C6 to C40 alkenyl group, such as a C8 to C20 or C8 to C16 alkenyl group. For example, R1 may represent an optionally substituted C2 to C100 alkyl group, such as a C6 to C50 alkyl group, preferably a C8 to C40 alkyl group. R1 may, for example, have at least 8, or at least 10, carbon atoms. R1 may have less than 30 carbon atoms, such as less than 28 carbon atoms, suitably less than 26 carbon atoms. For example, R1 may have less than 15 carbon atoms. R1 may be substituted with any suitable substituent, such as with one or more groups selected from halo (for example chloro, fluoro or bromo), nitro, hydroxy, mercapto, amino, acyl, carboxy, alkyl (for example C1 to C4 alkyl), alkoxy (for example C1 to C4 alkoxy), amido, keto, and cyano. Preferably, R1 is an unsubstituted hydrocarbyl group. Suitably, R1 is an unsubstituted alkyl or alkenyl group. Suitably, R1 may have a number average molecular weight of from 100 to 5,000, such as from 300 to 4,000, suitably from 450 to 2,500, for example from 500 to 2,000 or from 600 to 1,500. The hydrocarbyl substituted succinic acid or anhydride thereof (a) may comprise a mixture of compounds including groups R1 of different lengths. In such cases any reference to the molecular weight of the group R1 relates to the number average molecular weight (Mn) for the mixture. R1 may comprise a mixture of (preferably unsubstituted) alkenyl groups. The mixture of alkenyl groups is suitably selected from C12 to C14 alkenyl groups, C14 to C16 alkenyl groups, C16 to C18 alkenyl groups, and C20 to C24 alkenyl groups. The mixture of alkenyl groups is preferably selected from C12 to C14 alkenyl groups, C14 to C16 alkenyl groups, and C16 to C18 alkenyl groups. R1 may be a mixture of C16 to C18 alkenyl groups. Suitably, R1 may represent a polyisobutenyl group, for example having a number average molecular weight of from 100 to 5,000, such as from 200 to 2,000, suitably from 220 to 1,300, for example from 240 to 900. For example, R1 may represent a polyisobutenyl group having a number average molecular weight of from 180 to 400. The hydrocarbyl substituted succinic acid or anhydride thereof (a) may be selected from one or more of tetrapropenylsuccinic acid, tetrapropenylsuccinic anhydride, dodecenylsuccinic acid, dodecenylsuccinic anhydride, 2-octene-1-yl-succinic acid, 2-octene-1-yl-succinic anhydride, hexadecenylsuccinic acid, hexadecenylsuccinic anhydride, octadecenylsuccinic acid, octadecenylsuccinic anhydride, polyisobutylenesuccinic acid, and polyisobutylenesuccinic anhydride, wherein the polyisobutylene group has a number average molecular weight of about 260, 450, 750, or 1,000.  The hydrocarbyl substituted succinic acid or anhydride thereof (a) may be selected from one or more of tetrapropenylsuccinic acid, tetrapropenylsuccinic anhydride, dodecenylsuccinic acid, dodecenylsuccinic anhydride, 2-octene-1-yl-succinic acid, 2-octene-1-yl-succinic anhydride, hexadecenylsuccinic acid, hexadecenylsuccinic anhydride, octadecenylsuccinic acid, and octadecenylsuccinic anhydride.  Suitably, R1 may be the residue of an internal olefin. In such embodiments the compound of formula (A2) or (B2) is suitably obtained by the reaction of maleic acid with an internal olefin. R1 may be the residue of a mixture of C16 to C18 internal olefins. An internal olefin as used herein means any olefin containing predominantly a non-alpha double bond that is a beta or higher olefin. Preferably such materials are substantially completely beta or higher olefins, for example containing less than 10% by weight alpha olefin, more preferably less than 5% by weight or less than 2% by weight. Typical internal olefins include Neodene 1518IO available from Shell. Internal olefins are sometimes known as isomerised olefins and can be prepared from alpha olefins by a process of isomerisation known in the art, or are available from other sources. The fact that they are also known as internal olefins reflects that they do not necessarily have to be prepared by isomerisation. The at least one substituted succinic acid or anhydride thereof (iii) may comprise at least one olefin-maleic acid copolymer or anhydride thereof (b). Any suitable olefin-maleic acid copolymer or anhydride thereof may be used.  By a “olefin-maleic acid copolymer or anhydride thereof” we mean a copolymer comprising maleic acid or anhydride derived units and olefin derived units. The olefin-maleic acid copolymer or anhydride thereof is suitably an alternating copolymer and may be prepared by reacting maleic anhydride with an α-olefin. Means for carrying out such reactions will be well known to those skilled in the art and are described, for example, in US4240916, US3560456 and US4151069. The olefin-maleic acid copolymer or anhydride thereof may for example be prepared by reacting maleic anhydride with an α-olefin in a molar ratio of from 3:1 to 1:3, such as from 2:1 to 1:2, for example from 1.5:1 to 1:1.5, preferably about 1:1. The olefin-maleic acid copolymer or anhydride thereof may be prepared from at least one α-olefin that has from 6 to 40 carbon atoms, for example from 10 to 36 carbon atoms, such as from 12 to 36 carbon atoms, for example from 16 to 32 or from 18 to 30 carbon atoms. To form the olefin-maleic acid copolymer or anhydride thereof a mixture of α-olefins may be used. For example, a mixture of α-olefins having 20 to 24 carbon atoms, or having 24 to 28 carbon atoms, or having 26 to 28 carbon atoms, for example 14 to 18, or 16 to 18, or 14 to 16, or 12 to 14 carbon atoms, may be used. The copolymer directly obtained from the reaction of an α-olefin and maleic anhydride comprises alkyl chains and anhydride functional groups. Suitably, the anhydride groups may be hydrolysed to provide carboxylic acid functional groups. Preferably the maleic acid or anhydride derived units of the copolymer contain anhydride groups. Preferably the olefin-maleic acid copolymer or anhydride thereof is an olefin-maleic anhydride copolymer. Suitably the olefin-maleic anhydride copolymer may be obtained directly from the reaction of an α-olefin with maleic anhydride. The olefin-maleic acid copolymer or anhydride thereof may have a number average molecular weight of from 1,000 to 50,000, preferably from 2,000 to 40,000, suitably from 2,500 to 30,000, for example from 3,000 to 25,000. The olefin-maleic anhydride copolymer may comprise a 1:1 (molar ratio) alternating copolymer of maleic anhydride and a C18 α-olefin having Mn of from 2,000 to 10,000, for example of about 3,000. Preferably, the at least one substituted succinic acid or anhydride thereof (iii) is least one hydrocarbyl substituted succinic acid or anhydride thereof (a). The antifoulant additive compositions used herein may comprise the at least one substituted succinic acid or anhydride thereof (iii) in any suitable amount. The at least one substituted succinic acid or anhydride thereof (iii) may be included in the antifoulant additive composition in an amount of from 1 to 50 %, such as from 3 to 25 %, for example from 6 to 22%, by weight based on the total weight of the composition. The at least one substituted succinic acid or anhydride thereof (iii) may comprise from 10 to 50% by weight of the total active components in the antifoulant additive composition. By this we mean the % by weight based on the total active components, i.e. excluding solvent. The at least one substituted succinic acid or anhydride thereof (iii) may be used as an isolated compounds or diluted in a suitable solvent.  In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine, or a sulfonic acid salt of said polymeric polyamine; and(iii) at least one substituted succinic acid or anhydride thereof that is selected from the group consisting of:(a) a hydrocarbyl substituted succinic acid or anhydride thereof; and(b) an olefin-maleic acid copolymer or anhydride thereof. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine, or a sulfonic acid salt of said polymeric polyamine; and(iii) a hydrocarbyl substituted succinic acid or anhydride thereof. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine, or a sulfonic acid salt of said polymeric polyamine; and(iii) a compound of formula (A2) or a compound of formula (B2) as defined herein wherein R1 represents an optionally substituted C8 to C16 alkenyl group. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine, or a sulfonic acid salt of said polymeric polyamine; and(iii) a compound of formula (A2) or a compound of formula (B2) as defined herein wherein R1 represents a mixture of alkenyl groups selected from C12 to C14 alkenyl groups, C14 to C16 alkenyl groups, and C16 to C18 alkenyl groups. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine, or a sulfonic acid salt of said polymeric polyamine; and(iii) an olefin-maleic acid copolymer or anhydride thereof. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a 1:1 alternating copolymer of sulfur dioxide with one or more a-olefins (such as 1-decene);(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine, or a sulfonic acid salt of said polymeric polyamine; and(iii) at least one substituted succinic acid or anhydride thereof that is selected from the group consisting of:(a) a hydrocarbyl substituted succinic acid or anhydride thereof; and(b) an olefin-maleic acid copolymer or anhydride thereof. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a 1:1 alternating copolymer of sulfur dioxide with one or more a-olefins (such as 1-decene);(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine, or a sulfonic acid salt of said polymeric polyamine; and(iii) a hydrocarbyl substituted succinic acid or anhydride thereof. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a 1:1 alternating copolymer of sulfur dioxide with one or more a-olefins (such as 1-decene);(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine, or a sulfonic acid salt of said polymeric polyamine; and(iii) a compound of formula (A2) or a compound of formula (B2) as defined herein wherein R1 represents an optionally substituted C8 to C16 alkenyl group. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a 1:1 alternating copolymer of sulfur dioxide with one or more a-olefins (such as 1-decene);(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine, or a sulfonic acid salt of said polymeric polyamine; and(iii) a compound of formula (A2) or a compound of formula (B2) as defined herein wherein R1 represents a mixture of alkenyl groups selected from C12 to C14 alkenyl groups, C14 to C16 alkenyl groups, and C16 to C18 alkenyl groups. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl 1,3-propylenediamine, or an alkyl substituted aryl sulfonic acid salt of said polymeric polyamine; and(iii) at least one substituted succinic acid or anhydride thereof that is selected from the group consisting of:(a) a hydrocarbyl substituted succinic acid or anhydride thereof; and(b) an olefin-maleic acid copolymer or anhydride thereof. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl 1,3-propylenediamine, or an alkyl substituted aryl sulfonic acid salt of said polymeric polyamine; and(iii) a hydrocarbyl substituted succinic acid or anhydride thereof. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl 1,3-propylenediamine, or an alkyl substituted aryl sulfonic acid salt of said polymeric polyamine; and(iii) a compound of formula (A2) or a compound of formula (B2) as defined herein wherein R1 represents an optionally substituted C8 to C16 alkenyl group. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl 1,3-propylenediamine, or an alkyl substituted aryl sulfonic acid salt of said polymeric polyamine; and(iii) a compound of formula (A2) or a compound of formula (B2) as defined herein wherein R1 represents a mixture of alkenyl groups selected from C12 to C14 alkenyl groups, C14 to C16 alkenyl groups, and C16 to C18 alkenyl groups. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one sulfonic acid salt of a polymeric polyamine, wherein the polymeric polyamine is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine; and(iii) at least one substituted succinic acid or anhydride thereof that is selected from the group consisting of:(a) a hydrocarbyl substituted succinic acid or anhydride thereof; and(b) an olefin-maleic acid copolymer or anhydride thereof. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one sulfonic acid salt of a polymeric polyamine, wherein the polymeric polyamine is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine; and(iii) a hydrocarbyl substituted succinic acid or anhydride thereof. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one sulfonic acid salt of a polymeric polyamine, wherein the polymeric polyamine is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine; and(iii) a compound of formula (A2) or a compound of formula (B2) as defined herein wherein R1 represents an optionally substituted C8 to C16 alkenyl group. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one sulfonic acid salt of a polymeric polyamine, wherein the polymeric polyamine is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine; and(iii) a compound of formula (A2) or a compound of formula (B2) as defined herein wherein R1 represents a mixture of alkenyl groups selected from C12 to C14 alkenyl groups, C14 to C16 alkenyl groups, and C16 to C18 alkenyl groups. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one sulfonic acid salt of a polymeric polyamine, wherein the polymeric polyamine is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine; and(iii) an olefin-maleic acid copolymer or anhydride thereof. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine, wherein the polymeric polyamine is in the form of a free base; and(iii) at least one substituted succinic acid or anhydride thereof that is selected from the group consisting of:(a) a hydrocarbyl substituted succinic acid or anhydride thereof; and(b) an olefin-maleic acid copolymer or anhydride thereof. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine, wherein the polymeric polyamine is in the form of a free base; and(iii) a hydrocarbyl substituted succinic acid or anhydride thereof. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine, wherein the polymeric polyamine is in the form of a free base; and(iii) a compound of formula (A2) or a compound of formula (B2) as defined herein wherein R1 represents an optionally substituted C8 to C16 alkenyl group. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine, wherein the polymeric polyamine is in the form of a free base; and(iii) a compound of formula (A2) or a compound of formula (B2) as defined herein wherein R1 represents a mixture of alkenyl groups selected from C12 to C14 alkenyl groups, C14 to C16 alkenyl groups, and C16 to C18 alkenyl groups. In preferred embodiments, the antifoulant additive composition comprises: (i) at least one polysulfone polymer that is a copolymer of sulfur dioxide with one or more a-olefins;(ii) at least one polymeric polyamine that is a reaction product of epichlorohydrin and a N-aliphatic hydrocarbyl alkylene diamine, wherein the polymeric polyamine is in the form of a free base; and(iii) an olefin-maleic acid copolymer or anhydride thereof. The antifoulant additive composition may comprise any suitable additional components. For example, the antifoulant additive composition may further comprise: (iv) at least one quaternary ammonium salt. Any suitable quaternary ammonium salt may be included in the antifoulant additive composition. For example, the quaternary ammonium salt may be of formula (G):(G) wherein R11, R12, R13 and R14 each independently represent a C1 to C24 alkyl group, a C2 to C24 alkenyl group, a benzyl group, or an alkoxylate or polyalkoxylate group (e.g. arising from reaction of a secondary or tertiary amine with an alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide or mixtures thereof); andY is an anion. The anion Y of the quaternary ammonium compound may be any anion of a salt forming acid. Examples of suitable anions include chloride, bromide, iodide, sulfate, bisulfate, alkylsulfate, arylsulfate, alkanesulfonate, arenesulfonate, nitrate, nitrite, phosphate, monoalkyl phosphate, dialkyl phosphate, monoaryl phosphate, diarylphosphate, borate and carboxylate (such as salicylate). Suitably, the anion Y of the quaternary ammonium compound may be chloride, bromide or nitrite. For example, useful tetraalkyl ammonium salts include di(hydrogenated tallow)dimethylammonium chloride, dicocodimethylammonium chloride, dioctadecyldimethyl ammonium chloride, octadecyltrimethyl ammonium chloride, dodecyltrimethyl ammonium chloride, the C12-C14 alkyl trimethyl ammonium chlorides, the di-C12-C14 alkyldimethyl ammonium chlorides, hexadecyltrimethyl ammonium bromide, hexadecyltrimethyl ammonium iodide, dioctadecyldimethyl ammonium bromide, dioctadecylmethyl benzyl ammonium chloride, octadecyldimethylbenzyl ammonium chloride, and oxtadecyldimethyl(phenylethyl) ammonium chloride. Similarly, nitrites, sulfates, alkyl-sulfates, phosphates, carboxylates corresponding to the above quaternary ammonium halides may be used.  Suitably each of the at least one quaternary ammonium salt(s) (iv) is a tetraalkyl ammonium salt. A suitable quaternary ammonium salt may be dicocodimethylammonium nitrite or dicocodimethylammonium chloride. The quaternary ammonium salts are commercially available or can be readily prepared using procedures well known to those skilled in the art.  The antifoulant additive composition may comprise the at least one quaternary ammonium salt (iv) (when present) in any suitable amount. The at least one quaternary ammonium salt (iv) (when present) may be included in the antifoulant additive composition in an amount of from 0.2 to 7 %, such as from 0.5 to 5 %, for example from 1 to 3 %, by weight based on the total weight of the antifoulant additive composition. The at least one quaternary ammonium salt (iv) may comprise from 0.5 to 10 %, such as from 1 to 7 %, by weight of the total active components in the antifoulant additive composition. By this we mean the % by weight based on the total active components, i.e. excluding solvent. Suitably, the weight ratio of the at least one quaternary ammonium salt (iv) to the at least one polysulfone polymer (i) is from 1:99 to 1:1, preferably from 1:50 to 1:2. Suitably, the weight ratio of the at least one quaternary ammonium salt (iv) to the at least one polymeric polyamine or the sulfonic acid salt thereof (ii) is from 1:99 to 1:1, preferably from 1:50 to 1:2. Suitably, the weight ratio of the at least one quaternary ammonium salt (iv) to the at least one substituted succinic acid or anhydride thereof (iii) is from 1:99 to 1:1, preferably from 1:50 to 1:2. In some embodiments, the antifoulant additive composition is substantially free of quaternary ammonium salts. By “substantially free” of quaternary ammonium salts we mean that the antifoulant additive composition contains less than 10,000, such as less than 2,000, particularly less than 500, parts per million (ppm) of quaternary ammonium salts.  In some embodiments, the polymerisation reaction mixture is substantially free of quaternary ammonium salts. By “substantially free” of quaternary ammonium salts we mean that the polymerisation reaction mixture contains less than 3, such as less than 1, particularly less than 0.2, parts per million (ppm) of quaternary ammonium salts.  The antifoulant additive composition may further comprise at least one solvent. The solvent may be selected by a person skilled in the art depending on the intended use of the antifoulant additive composition. A suitable solvent may comprise an aliphatic or cycloaliphatic hydrocarbon solvent (which may be saturated or unsaturated). Examples of such solvents include pentane, hexane, heptane, octane, cyclohexane and methylcyclohexane, or α-olefins such as 1-heptene and 1-octene. α-olefin solvents may participate in the polymerisation reaction thus reducing the amount of solvent residue in the resultant polymer. The antifoulant additive compositions described herein may find use in hydrocarbon liquids, for example solvents or fuels, or refinery operations, such as petroleum refining. Suitable examples of fuels may include kerosene, gasoline, or diesel fuels. The antifoulant additive compositions described herein may be used to impart at least one advantageous property to the hydrocarbon liquid, for example to enable safe handling by increasing the conductivity thereof. According to a second aspect of the present invention, there is provided method of reducing fouling during a polymerisation process, the method comprising:- providing a polymerisation reaction mixture comprising at least one olefinic monomer;- contacting an antifoulant additive composition with the polymerisation reaction mixture; and- carrying out a polymerisation process to obtain a polymer composition;wherein the antifoulant additive composition comprises:(i) at least one polysulfone polymer;(ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and(iii) at least one substituted succinic acid or anhydride thereof. The method of the second aspect of the present invention may comprise:- providing a polymerisation reaction mixture comprising at least one olefinic monomer;- mixing an antifoulant additive composition into the polymerisation reaction mixture; and- carrying out a polymerisation process to obtain a polymer composition;wherein the antifoulant additive composition comprises:(i) at least one polysulfone polymer;(ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and(iii) at least one substituted succinic acid or anhydride thereof. Preferred features of the polymerisation reaction mixture and antifoulant additive composition in relation to the second aspect of the invention are as set out herein in relation to the first aspect of the invention. The polymerisation process according to the second aspect of the invention comprises polymerisation of olefinic monomers, such as ethylene and / or propylene, to form a polymer, for example a polyolefin polymer such as polyethylene and / or polypropylene. The polymerisation reaction may provide a homo or a co-polymer. Optionally, higher alpha olefins can be included to modify the density and / or other physical properties of the produced polyolefin polymer. Any suitable catalyst may be used in the polymerisation reaction. The catalyst may comprise a transition metal belonging to one of the groups IV, V or VI of the Periodic Table of the Elements. The catalyst used in the polymerisation process may be homogenous or heterogenous (e.g. solid supported). Preferably, the catalyst is heterogeneous, further preferably heterogeneous solid supported. Examples of suitable catalysts for the polymerisation of olefins include Ziegler-Natta (ZN) catalysts, chromium-based catalysts (such as chromium oxide catalysts) and single site catalysts (SSC) (such as metallocene catalysts). Suitably, the metal centre of a single site catalyst typically includes titanium, zirconium or hafnium. Suitable single site catalysts may be homogenous or heterogenous (e.g. solid supported). Typical solid supports for solid supported single site catalysts include zeolites, partially dehydroxylated silica, silica-alumina, alumina substrates and magnesium oxides. Processes used for polymer manufacture include bulk polymerization, gas phase, solution phase and slurry processes. Suitably, the polymerisation reaction is conducted in the gaseous phase. The polymerisation process may be carried out in the presence of a scavenger and / or co-catalyst. Such compounds are typically organometallic compounds. Examples of suitable scavengers and / or co-catalysts include alkylaluminium compounds such as triethylaluminium. In particular, alkylaluminium compounds such as triethylaluminium may be used as co-catalysts. The polymerisation process according to the second aspect of the invention may be carried out in the gas phase in a stirred and / or fluidised bed reactor. Alternatively, the polymerisation process may be carried out as suspension polymerisation in a loop reactor (e.g. slurry loop reactor) or a stirred tank reactor (e.g. slurry stirred tank reactor). The polymerisation process may be carried out in a reaction system comprising a main reactor and optionally one or more auxiliary units. The antifoulant additive composition may be added directly to the main reactor or to one or more auxiliary units such as transfer lines, gas cycle lines, or upstream of slurry or gas heat exchangers. Preferably, the antifoulant additive composition is mixed into the polymerisation reaction mixture. Alternatively, the antifoulant additive composition may be carried on a solid support. Suitably, the polymerisation process is carried out by contacting the polymerisation reaction mixture with a solid support, wherein the solid support carries the antifoulant additive composition, and a polymerisation catalyst. The solid support may optionally carry a co-catalyst. The antifoulant additive composition, polymerisation catalyst, and optional co-catalyst (when present) may be adsorbed onto the solid support. Suitable polymerisation catalysts include Ziegler-Natta (ZN) catalysts, chromium-based catalysts (such as chromium oxide catalysts) and single site catalysts (SSC) (such as metallocene catalysts) as described herein. Suitable co-catalysts include alkylaluminium compounds as described herein. Suitable solid supports include zeolites, partially dehydroxylated silica, silica-alumina, alumina substrates and magnesium oxides. The solid support and antifoulant additive composition may be an antifoulant additive system according to the sixth aspect of the present invention. Preferably, the antifoulant additive composition is used in an amount of from 1 to 50 ppm based on the total weight of the polymerisation reaction mixture before addition of the antifoulant additive composition. In preferred embodiments, the at least one olefinic monomer comprises ethylene and optionally at least one further a-olefin; the antifoulant additive composition is used in an amount of from 1 to 50 ppm based on the total weight of the polymerisation reaction mixture before addition of the antifoulant additive composition; and the polymerisation process is carried out using a Ziegler-Natta, chromium or metallocene catalyst in a gas fluidised bed reactor. In preferred embodiments, the at least one olefinic monomer comprises ethylene and optionally at least one further a-olefin; the antifoulant additive composition is used in an amount of from 1 to 50 ppm based on the total weight of the polymerisation reaction mixture before addition of the antifoulant additive composition; and the polymerisation process is carried out using a Ziegler-Natta, chromium or metallocene catalyst in a slurry loop reactor. In preferred embodiments, the at least one olefinic monomer comprises ethylene and optionally at least one further a-olefin; the antifoulant additive composition is used in an amount of from 1 to 50 ppm based on the total weight of the polymerisation reaction mixture before addition of the antifoulant additive composition; and the polymerisation process is carried out using a Ziegler-Natta, chromium or metallocene catalyst in a slurry stirred tank reactor. In preferred embodiments, the at least one olefinic monomer comprises propylene and optionally at least one further a-olefin; the antifoulant additive composition is used in an amount of from 1 to 50 ppm based on the total weight of the polymerisation reaction mixture before addition of the antifoulant additive composition; and the polymerisation process is carried out using a Ziegler-Natta or metallocene catalyst in a gas fluidised bed reactor. In preferred embodiments, the at least one olefinic monomer comprises propylene and optionally at least one further a-olefin; the antifoulant additive composition is used in an amount of from 1 to 50 ppm based on the total weight of the polymerisation reaction mixture before addition of the antifoulant additive composition; and the polymerisation process is carried out using a Ziegler-Natta or metallocene catalyst in a gas stirred bed reactor. In preferred embodiments, the at least one olefinic monomer comprises propylene and optionally at least one further a-olefin; the antifoulant additive composition is used in an amount of from 1 to 50 ppm based on the total weight of the polymerisation reaction mixture before addition of the antifoulant additive composition; and the polymerisation process is carried out using a Ziegler-Natta or metallocene catalyst in a slurry loop reactor. The polymer composition obtained by the polymerisation process according to the second aspect of the invention comprises a polymer derived from the at least one olefinic monomer, for example a polyolefin polymer such as a polyethylene and / or polypropylene polymer. The polymer composition may also comprise residual olefinic monomers and other components of the polymerisation reaction mixture, such as the antifoulant additive composition. The polymer composition may be purified to separate the polymer from other components. According to a third aspect of the present invention, there is provided a use of an antifoulant additive composition to reduce fouling during a polymerisation process; wherein the antifoulant additive composition comprises:(i) at least one polysulfone polymer;(ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and(iii) at least one substituted succinic acid or anhydride thereof. Preferred features of the antifoulant additive composition in relation to the third aspect of the invention are as set out herein in relation to the first aspect of the invention. Preferred features of the polymerisation process in relation to the third aspect of the invention are as set out herein in relation to the second aspect of the invention. The use according to the third aspect of the invention may comprise contacting the antifoulant additive composition with a polymerisation reaction mixture. Suitably, the use according to the third aspect of the invention comprises mixing the antifoulant additive composition into a polymerisation reaction mixture. Preferred features of the polymerisation reaction mixture are as set out herein in relation to the first aspect of the invention. According to a fourth aspect of the present invention, there is provided a polymer composition comprising a polymer and an antifoulant additive composition; wherein the polymer is derived from at least one olefinic monomer; andwherein the antifoulant additive composition comprises:(i) at least one polysulfone polymer;(ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and(iii) at least one substituted succinic acid or anhydride thereof. Preferred features of the antifoulant additive composition in relation to the fourth aspect of the invention are as set out herein in relation to the first aspect of the invention. The polymer composition according to the fourth aspect is preferably obtained according to a polymerisation process as defined herein in relation to the second aspect of the invention. Suitably, the polymer composition according to the fourth aspect is obtained by carrying out a polymerisation process on a polymerisation reaction mixture comprising at least one olefinic monomer and the antifoulant additive composition. The polymer composition comprises a polymer derived from at least one olefinic monomer. In some embodiments, the polymer is a homopolymer. In such embodiments, the polymer is derived from only one olefinic monomer. In some embodiments, the polymer is a copolymer. In such embodiments, the polymer is derived from at least two olefinic monomers. Suitably, the at least one olefinic monomer is selected from the group consisting of α-olefins, internal olefins (for example β- or γ-olefins), conjugated dienes (for example isoprene or butadiene), styrene, substituted styrenes (for example α-methylstyrene, 4-chloromethylstyrene or divinylbenzene), acrolein, acrylonitrile, vinyl alcohol, vinyl esters (for example vinyl acetate), vinylpyrrolidone, vinylimidazole, vinylpyridine, maleic anhydride, (meth)acrylic acid, (meth)acrylic acid derivatives (for example (meth)acrylate esters and (meth)acrylamides), vinyl halides (for example vinyl chloride) and vinylidene halides (for example vinylidene fluoride). Suitably, the at least one olefinic monomer is selected from the group consisting of α-olefins, internal olefins (for example β- or γ-olefins), conjugated dienes (for example isoprene or butadiene), styrene, and substituted styrenes (for example α-methylstyrene, 4-chloromethylstyrene or divinylbenzene). Suitably, the at least one olefinic monomer comprises an a-olefin. Suitably, the at least one olefinic monomer comprises a C2 to C24 a-olefin, preferably a C2 to C12 a-olefin, for example a C2 to C6 a-olefin. The at least one olefinic monomer suitably comprises ethylene, propylene, butene, hexene, octene, or a mixture thereof. The at least one olefinic monomer preferably comprises ethylene, propylene, or a mixture thereof. The at least one olefinic monomer may comprise ethylene, propylene, or a mixture thereof, and a C4 to C24 a-olefin, such as a C4 to C12 a-olefin. Suitably, the at least one olefinic monomer comprises ethylene, propylene, or a mixture thereof in an amount of at least 60 wt%, such as at least 70 wt%, such as at least 80 wt%, for example at least 90 wt% based on the total weight of the at least one olefinic monomer. In some embodiments, the at least one olefinic monomer comprises ethylene, and optionally at least one further a-olefin. In some embodiments, the at least one olefinic monomer comprises propylene, and optionally at least one further a-olefin. In some embodiments, the at least one olefinic monomer comprises a mixture of ethylene and propylene. The polymer is suitably a polyolefin polymer. In such embodiments, the at least one olefinic monomer is at least one olefin, preferably at least one a-olefin. In some embodiments, the polyolefin polymer is a homopolymer. In such embodiments, the polyolefin polymer is derived from only one olefin. In some embodiments, the polyolefin polymer is a copolymer. In such embodiments, the polyolefin polymer is derived from at least two olefins. Suitably, the at least one olefin is at least one C2 to C24 a-olefin, preferably at least one C2 to C12 a-olefin, for example at least one C2 to C6 a-olefin. The at least one olefin suitably comprises ethylene, propylene, butene, hexene, octene, or a mixture thereof. The at least one olefin preferably comprises ethylene, propylene, or a mixture thereof. The at least one olefin may consist of ethylene, propylene, or a mixture thereof, and a C4 to C24 a-olefin, such as a C4 to C12 a-olefin. Suitably, the at least one olefin comprises ethylene, propylene, or a mixture thereof in an amount of at least 60 wt%, such as at least 70 wt%, such as at least 80 wt%, for example at least 90 wt% based on the total weight of the at least one olefin. In some embodiments, the at least one olefin comprises ethylene, and optionally at least one further a-olefin. In some embodiments, the at least one olefin comprises propylene, and optionally at least one further a-olefin. In some embodiments, the at least one olefin comprises a mixture of ethylene and propylene. The at least one olefin is suitably selected from the group consisting of ethylene, propylene, and mixtures thereof. The at least one olefin is preferably ethylene or propylene. The polyolefin polymer is preferably a polyethylene polymer or a polypropylene polymer. By “polyethylene polymer” we mean a homopolymer of ethylene or a copolymer of ethylene and at least one other a-olefin, wherein greater than 50% by weight of the repeat units in the copolymer are derived from ethylene. By “polypropylene polymer” we mean a homopolymer of propylene or a copolymer of propylene and at least one other a-olefin, wherein greater than 50% by weight of the repeat units in the copolymer are derived from propylene. The polyolefin polymer may be an ethylene-propylene copolymer. The polymer composition comprises an antifoulant additive composition. The antifoulant additive composition may be present in a residual amount. The antifoulant additive composition may be present in the polymer composition in an amount of from 1 to 300 ppm, such as from 1 to 100 ppm, such as from 1 to 60 ppm, such as from 1 to 50 ppm, for example from 1 to 20 ppm based on the total weight of the polymer composition. Preferably, the antifoulant additive composition is present in an amount of from 1 to 50 ppm based on the total weight of the polymer composition. The polymer composition may comprise at least one olefinic monomer. The at least one olefinic monomer is suitably as described above. The at least one olefinic monomer may be present in a residual amount. The at least one olefinic monomer may be present in the polymer composition in an amount of from 0.001 to 5 %, such as from 0.002 to 1 %, for example from 0.005 to 0.5 % by weight based on the total weight of the polymer composition. In some embodiments, the polymer composition is substantially free of sulfonic acids or salts thereof, such as sulfonic acid salts of polymeric polyamines. By “substantially free” of sulfonic acids or salts thereof we mean that the polymer composition contains less than 3, preferably less than 1, more preferably less than 0.1, parts per million (ppm) of sulfonic acids or salts thereof. In some embodiments, the polymer composition is substantially free of quaternary ammonium salts. By “substantially free” of quaternary ammonium salts we mean that the polymerisation reaction mixture contains less than 3, such as less than 1, particularly less than 0.2, parts per million (ppm) of quaternary ammonium salts.  According to a fifth aspect of the present invention, there is provided an antifoulant additive composition; wherein the antifoulant additive composition comprises:(i) at least one polysulfone polymer;(ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and(iii) at least one substituted succinic acid or anhydride thereof. Preferred features of the antifoulant additive composition according to the fifth aspect of the invention are as set out herein in relation to the first aspect of the invention. According to a sixth aspect of the present invention, there is provided a polymerisation additive system comprising a solid support, an antifoulant additive composition, and a polymerisation catalyst; wherein the antifoulant additive composition comprises:(i) at least one polysulfone polymer;(ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and(iii) at least one substituted succinic acid or anhydride thereof. The system may optionally comprise a co-catalyst. Preferred features of the solid support, antifoulant additive composition, polymerisation catalyst, and co-catalyst in relation to the sixth aspect of the invention are as set out herein in relation to the first and second aspects of the invention. Suitably, the solid support carries the antifoulant additive composition, polymerisation catalyst, and optional co-catalyst (when present). The antifoulant additive composition, polymerisation catalyst, and optional co-catalyst (when present) may be adsorbed onto the solid support. Suitable polymerisation catalysts include Ziegler-Natta (ZN) catalysts, chromium-based catalysts (such as chromium oxide catalysts) and single site catalysts (SSC) (such as metallocene catalysts) as described herein in relation to the second aspect. Suitable co-catalysts include alkylaluminium compounds as described herein in relation to the second aspect. Suitable solid supports include zeolites, partially dehydroxylated silica, silica-alumina, alumina substrates and magnesium oxides. Brief Description of the Drawings For a better understanding of the invention, and to show how example embodiments may be carried into effect, reference will now be made to the accompanying drawings in which: Figure 1 shows photographs of (a) reactor internal surfaces and (b) an agitator after carrying out a polymerisation reaction in the absence of an inventive additive. Figure 2 shows photographs of (a) reactor internal surfaces and (b) an agitator after carrying out a polymerisation reaction in the presence of 1 ppm of an inventive additive. Figure 3 shows photographs of (a) reactor internal surfaces and (b) an agitator after carrying out a polymerisation reaction in the presence of 3 ppm of an inventive additive. The invention will now be further described with reference to the following non-limiting examples. Examples The following antifoulant additive composition was prepared comprising the components as set out in Table 1. Table 1ExampleComponent (wt% active)Total active content (wt%)PSPPDDSA111.215.414.841.4PS = 1:1 alternating copolymer of sulfur dioxide and 1-decene having Mn of about 10,000 prepared according to US3917466 and provided as an approximately 40 wt% solution in heptane.PP = Polymeric reaction product of oleyl-1,3-propanediamine and epichlorohydrin prepared according to US3917466 and provided as an approximately 50 wt% solution in heptane.DDSA = dodecenylsuccinic anhydride (undiluted). A reactor fouling test was carried out as follows. A 1.8 L stainless steel reactor is fitted with a double helix agitator, catalyst feeder, thermocouple and a pressure measurement device. The feed of input gases (N2, H2 and ethylene) and liquid monomers (eg 1-hexene) is regulated by mass flow controllers. In the process, H2 is used as a chain transfer agent (CTA). When used, the additives of the invention are prepared as solutions in n-pentane and continuously injected during the polymerization process to provide the required concentration (ppm by weight relative to ethylene monomer).  The polymerisation conditions are summarised as follows:Table2: Reactor polymerization conditionsProcess parameters CatalystGrace ActiveCat® 201Catalyst amount [mg]10Pressure [bar]22Temperature [°C]80Polymerisation time [min]60RPM [rev / min]540Ethylene [bar]7.2Hydrogen [bar]0.041-hexene [g]0.3n-pentane [g]17.0Nitrogen [bar]±11.0Hydrogen / ethylene feed ratio [g / g]0.000041-hexene / ethylene feed ratio [g / g]0.06* A product of W. R. Grace and Co, Maryland, United States Fouling is assessed by visual inspection of the internal reactor surface and agitator. Results For all reactions, the expected amount of ethylene – hexene copolymer was formed indicating no deleterious effect of the inventive additive on polymerization catalyst activity. In the absence of the inventive additive, the reactor was significantly fouled (by the formed copolymer particles) across its entire internal surface and on the agitator. At both of the treat rates evaluated for the inventive additive (1 ppm and 3 ppm of Example 1), the adherence of the copolymer particles to the reactor internal surface and agitator was significantly reduced. This was clearly apparent by visual inspection. The greatest reduction in fouling was achieved by a treat rate of 3 ppm of Example 1. Photographs of the (a) reactor internal surfaces and (b) agitator, with inventive additive treat rates of 0 ppm (absent), 1 ppm and 3 ppm are shown in Figures 1, 2, and 3, respectively. The present 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, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. 

Claims

1. A polymerisation reaction mixture comprising at least one olefinic monomer and an antifoulant additive composition; wherein the antifoulant additive composition comprises: (i) at least one polysulfone polymer; (ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and (iii) at least one substituted succinic acid or anhydride thereof.

2. A method of reducing fouling during a polymerisation process, the method comprising:- providing a polymerisation reaction mixture comprising at least one olefinic monomer;- contacting an antifoulant additive composition with the polymerisation reaction mixture; and - carrying out a polymerisation process to obtain a polymer composition; wherein the antifoulant additive composition comprises: (i) at least one polysulfone polymer; (ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and (iii) at least one substituted succinic acid or anhydride thereof.

3. The polymerisation reaction mixture or method according to claim 1 or claim 2, wherein the at least one olefinic monomer is selected from the group consisting of α-olefins, internal olefins, conjugated dienes, styrene, substituted styrenes, acrolein, acrylonitrile, vinyl alcohol, vinyl esters, vinylpyrrolidone, vinylimidazole, vinylpyridine, maleic anhydride, (meth)acrylic acid, (meth)acrylic acid derivatives, vinyl halides and vinylidene halides.

4. The polymerisation reaction mixture or method according to any preceding claim, wherein the at least one olefinic monomer comprises a C2 to C24 a-olefin.

5. The polymerisation reaction mixture or method according to claim 4, wherein the at least one olefinic monomer is selected from the group consisting of ethylene, propylene and mixtures thereof.

6. The use of an antifoulant additive composition to reduce fouling during a polymerisation process; wherein the antifoulant additive composition comprises: (i) at least one polysulfone polymer; (ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and (iii) at least one substituted succinic acid or anhydride thereof.

7. A polymer composition comprising a polymer and an antifoulant additive composition; wherein the polymer is derived from at least one olefinic monomer; andwherein the antifoulant additive composition comprises: (i) at least one polysulfone polymer; (ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and (iii) at least one substituted succinic acid or anhydride thereof.

8. A polymerisation additive system comprising a solid support, an antifoulant additive composition, and a polymerisation catalyst; wherein the antifoulant additive composition comprises: (i) at least one polysulfone polymer; (ii) at least one polymeric polyamine, or a sulfonic acid salt thereof; and (iii) at least one substituted succinic acid or anhydride thereof.

9. The polymerisation reaction mixture, method, use, polymer composition, or polymerisation additive system according to any preceding claim, wherein the at least one polysulfone polymer (i) comprises an alternating copolymer of one or more olefins (suitably a-olefins) and sulfone groups.

10. The polymerisation reaction mixture, method, use, polymer composition, or polymerisation additive system according to any preceding claim, wherein the weight ratio of the at least one polysulfone polymer (i) to the at least one substituted succinic acid or anhydride thereof (iii) is from 19:1 to 1:19, preferably from 9:1 to 1:9.

11. The polymerisation reaction mixture, method, use, polymer composition, or polymerisation additive system according to any preceding claim, wherein the polymeric polyamine is selected from the group consisting of:(a) a reaction product of a reaction mixture comprising epichlorohydrin and an aliphatic primary monoamine or a N-aliphatic hydrocarbyl alkylene diamine;(b) a reaction product of a reaction mixture comprising a polyethyleneimine and a polyisobutenylsuccinic anhydride;(c) a reaction product of a reaction mixture comprising an ethylene-vinyl acetate-amino(meth)acrylate terpolymer; and(d) an olefin-maleic anhydride copolymer derivatised with a polyamine.

12. The polymerisation reaction mixture, method, use, polymer composition, or polymerisation additive system according to any preceding claim, wherein component (ii) of the antifoulant additive composition is the sulfonic acid salt of the polymeric polyamine.

13. The polymerisation reaction mixture, method, use, polymer composition, or polymerisation additive system according to any one of claims 1 to 11, wherein component (ii) of the antifoulant additive composition is the polymeric polyamine (i.e. in the form of a free base).

14. The polymerisation reaction mixture, method, use, polymer composition, or polymerisation additive system according to any preceding claim, wherein the weight ratio of the at least one polymeric polyamine or the sulfonic acid salt thereof (ii) to the at least one substituted succinic acid or anhydride thereof (iii) is from 19:1 to 1:19, preferably from 9:1 to 1:9.

15. The polymerisation reaction mixture, method, use, polymer composition, or polymerisation additive system according to any preceding claim, wherein the at least one substituted succinic acid or anhydride thereof (iii) is selected from the group consisting of: (a) a hydrocarbyl substituted succinic acid or anhydride thereof; and (b) an olefin-maleic acid copolymer or anhydride thereof.

16. The polymerisation reaction mixture, method, use, polymer composition, or polymerisation additive system according to claim 15, wherein the hydrocarbyl substituted succinic acid or anhydride thereof (a) is of formula (A2) or (B2): (A2) (B2) wherein R1 represents an optionally substituted hydrocarbyl group.

17. The polymerisation reaction mixture, method, use, polymer composition, or polymerisation additive system according to claim 15, wherein the olefin-maleic acid copolymer or anhydride thereof is prepared from at least one α-olefin that has from 6 to 40 carbon atoms.

18. The polymerisation reaction mixture, method, use, polymer composition, or polymerisation additive system according to any preceding claim, wherein the antifoulant additive composition further comprises: (iv) at least one quaternary ammonium salt.

19. The polymerisation reaction mixture, method, use, polymer composition, or polymerisation additive system according to claim 18, wherein the weight ratio of the at least one quaternary ammonium salt (iv) to the at least one substituted succinic acid or anhydride thereof (iii) is from 1:99 to 1:1, preferably from 1:50 to 1:2.

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