Stabilized slurry of polyisoolefin homo- or copolymer

Abstract

The invention relates to a process for preparing a polyisoolefin homo- or copolymer, preferably selected from butyl rubber, polyisobutylene and poly(isobutylene-co-para methyl styrene), the process comprising the step of polymerizing at least one isoolefin monomer and optionally at least one copolymerizable monomer, preferably multiolefin monomer, in the presence of a preformed polymeric stabilizer. The preformed polymeric stabilizer comprises repeating units derived from styrene and repeating units having pendant linear or branched saturated alkyl groups with at least 3 carbon atoms. Preferably, the repeating units with the pendant alkyl groups are derived from monoterpenes, especially myrcene or ocimene, or sesquiterpenes, especially farnesene, and subsequently hydrogenated. The preformed polymeric stabilizer advantageously stabilizes the slurry of the polyisoolefin homo- or copolymer, preferably selected from butyl rubber, polyisobutylene and poly(isobutylene-co-para methyl styrene), that is formed during polymerization in a solvent.

Description

Stabilized slurry of polyisoolefin homo- or copolymer

[0001] The invention relates to a process for preparing a polyisoolefin homo- or copolymer, preferably selected from butyl rubber, polyisobutylene and poly(isobutylene-co-para methyl styrene), the process comprising the step of polymerizing at least one isoolefin monomer and optionally at least one copolymerizable monomer, preferably multiolefm monomer, in the presence of a preformed polymeric stabilizer. The preformed polymeric stabilizer comprises repeating units derived from styrene and repeating units having pendant linear or branched saturated alkyl groups with at least 3 carbon atoms. Preferably, the repeating units with the pendant alkyl groups are derived from monoterpenes, especially myrcene or ocimene, or sesquiterpenes, especially famesene, and subsequently hydrogenated. The preformed polymeric stabilizer advantageously stabilizes the slurry of the polyisoolefin homo- or copolymer, preferably selected from butyl rubber, polyisobutylene and poly(isobutylene-co-para methyl styrene), that is formed during polymerization in a solvent.

[0002] Butyl rubber (IIR) is a copolymer of an isoolefin monomer, typically isobutene, with comparatively small amounts of a multiolefm polymer, typically isoprene, to impart reactivity in curing and functionalization. The copolymerization of isobutene and isoprene is cationically initiated and is usually performed at reaction temperatures below -90 °C.

[0003] Copolymerization of isoprene results in ethylenic unsaturations in the butyl rubber. Commercial grades often have isoprene contents of from 0.5 to 2.5 mol.-% thus providing ethylenically unsaturated groups along the polymer backbone for curing or further functionalization reactions.

[0004] The reaction is typically performed as a slurry polymerization in a polar solvent, especially methyl chloride, wherein the butyl rubber that is formed is suspended. Methyl chloride is a very polar molecule in comparison to the non-polar growing butyl rubber chains, resulting in a suspension of glassy butyl rubber particles in the methyl chloride diluent, as the polymerization is conducted below the Tg of butyl rubber.

[0005] A Friedel-Crafts catalyst is typically used as part of the polymerization initiator. Methyl chloride as solvent offers the advantage that AICI3. a relatively inexpensive Friedel-Crafts catalyst, is soluble, as are the isobutylene and isoprene comonomers. However, the butyl rubber polymer is insoluble in methyl chloride and precipitates out of solution as fine particles (slurry).For details, reference is made to Ullmanns Encyclopedia of Industrial Chemistry, volume A 23, 1993, pages 288-295.

[0006] US 4,252,710 A, US 4,358,560 and US 4,474,924 A disclose that polymerization slurries of elastomeric isoolefin homopolymers and copolymers, such as butyl rubber, in diluents such as methyl chloride, are effectively stabilized against agglomeration of polymer particles through addition of minor proportions of a preformed copolymer stabilizer having both a lyophobic or lyophilic portion. The process is especially adaptable to the production of isobuteneisoprene butyl rubber.

[0007] US 5,071,913 relates to a substantially gel free C4 to C7 isoolefin homopolymer rubber, butyl copolymer rubber, halogenated butyl rubber, or mixtures thereof, comprising a molecular weight distribution such that the ratio of the moments of said molecular weight distribution, Mz / Mw, is equal to or exceeds 2.0, and that portion of said molecular weight distribution which is equal to and greater than 4 times the peak molecular weight, Mp, comprises greater than 8 percent of the total polymer species, and Mp is greater than about 250,000 and wherein said polymer species of molecular weight less than Mp are substantially branch free.

[0008] US 7,402,636 relates to a slurry polymerization system and method to decrease polymer deposition on reactor surfaces using an oxygenate such as alcohol supplied to the polymerization medium separate from the catalyst feed.

[0009] US 9,079,990 relates to the formation of a copolymer by polymerizing C4 to C7 isoole-fin monomers and alkyl-styrene monomers.

[0010] CN 1 417234 relates to a cation polymerization process of preparing isoolefine polymer or copolymer.

[0011] CN 111 040063 discloses a production process of food-grade butyl rubber.

[0012] CN 111 234 077 relates to a high-single-concentration and high-conversion-rate production method of butyl rubber.

[0013] CN 111 393 556 provides a preparation method of an isomonoolefin-alkylstyrene copolymer, which is characterized in that isomonoolefm and alkylstyrene are used as polymerization monomers, alkylamine and / or aromatic amine are used as slurry stabilizers, and an initiation system consisting of a main initiator and an auxiliary initiator initiates polymerization reaction to obtain the isomonoolefin-alkylstyrene copolymer.

[0014] CN 112409522 provides a preparation method of butyl rubber comprising the following steps: a) mixing mono-olefin with a solvent to obtain a mixed solution; b) dissolving a slurry stabilizer in diolefin to obtain a slurry stabilizer solution; c) and mixing the mixed solution, the slurry stabilizer solution and the catalyst solution for reaction to form the butyl rubber.

[0015] CN 115 975 090 provides butyl rubber and a preparation method thereof, and the preparation method comprises the following steps: in the presence of a catalyst, mixing the slurry stabilizer solution, monoolefme, diolefin and a reaction solvent to obtain a reactant solution, reacting, and adding a terminator to obtain butyl rubber; the slurry stabilizer is selected from styrene-isobutene block copolymer and / or styrene-isobutene-styrene block copolymer.

[0016] US 2015 0197588 Al relates to a hydrogenated block copolymer including a polymer block (A) containing a constitutional unit derived from an aromatic vinyl compound and a polymer block (B) containing from 1 to 100% by mass of a constitutional unit (bl) derived from famesene and from 99 to 0% by mass of a constitutional unit (b2) derived from a conjugated diene other than the famesene, in which 50 mol % or more of carbon-carbon double bonds in the polymer block (B) are hydrogenated.

[0017] D.H. Lamparelli et al., ChemPlusChem 2022, 87, e202100366, review stereoregular polymerization of acyclic terpenes.

[0018] R. Marzocchi et al., Macromol. Rapid Commun. 2024, 2400641, relates to synthesis and characterization of [3-myrcene-styrene copolymers and [3-ocimene-styrene copolymers.

[0019] A problem that occurs in the polyisoolefin homopolymer such as polyisobutylene and polyisoolefin copolymer including butyl rubber and poly(isobutylene-co-para methyl styrene) polymerization is called "hot spot" due to the inhomogeneity of the temperature in the polymerization medium. When hot spot occurs, the local microcosmic temperature of polymerization reaction mixture increases. As a result, the butyl rubber slurry particles become sticky and tend to agglomerate. As the polymerization is exothermic, without the addition of slurry stabilizer, the agglomerated particles will further aggregate with the increase of the reaction temperature, which can negatively affect the heat and mass transfer in the reactor as these aggregates can be deposited on the surface of the reactor. Meanwhile, the presence of the slurry particles aggregate can block the pipelines and cause fouling issues. For example, when the draft tube of the reactor is blocked by a slurry particle aggregates with 20-30 cm in diameter, rapid amp failure can occur. Rapid amp failures have several negative impacts on a butyl production plant,including reducing capacity by requiring unscheduled reactor warm up and washing, and could increase the potential for overpressure incidents in the reactor.

[0020] There is a demand to increase the slurry stability to suppress the deposit of slurry particle aggregates on the reactor surface, reduce the fouling in the reactor and minimize the occurrence of rapid amp failures.

[0021] Improvement of the interface between the polar solvent, e.g. methyl chloride, and the polyisoolefin homo or copolymer should reduce fouling and rapid amp failures in a polyiso-olefin polymers production facility. The invention aims at improving the polyisoolefin homo or copolymer - solvent (methyl chloride) interaction in order to decrease the likelihood of large agglomerates of rubber particles that are formed during the polymerization. If the compatibility between nonpolar polyisoolefin homo or copolymer and polar solvent (methyl chloride) were improved, the slurry stability of polyisoolefin homo or copolymer could be improved. This could result in less agglomeration of rubber particles during the polymerization, and thus less deposit of rubber aggregates on the surface of reactor, less fouling issues, and also less rapid amp failures.

[0022] It is an object of the invention to provide a process for the preparation of polyisoolefin homo- or copolymer having advantages compared to the prior art. The process should suppress the deposit of rubber aggregates on the surface of reactor, reducing the fouling issues and minimize rapid amp failures.

[0023] This object has been achieved by the subject-matter of the patent claims.

[0024] It has been surprisingly found that copolymers of styrene and monomers having pendant linear or branched saturated alkyl groups with at least 3 carbon atoms, especially hydrogenated polyfamesene, advantageously interact with butyl rubber and have utility as slurry stabilizer.

[0025] A first aspect of the invention relates to a process for preparing a polyisoolefin homo-or copolymer, preferably selected from butyl rubber, polyisobutylene and poly(isobutylene-co-para methyl styrene), more preferably butyl rubber, the process comprising the step of polymerizing at least one isoolefin monomer and optionally at least one copolymerizable monomer, preferably multiolefin monomer, in the presence of a preformed polymeric stabilizer; wherein said preformed polymeric stabilizer comprises or essentially consists of(i) repeating units according to general formula (IA), (IB) or (IC)whereinRa, Rb, Rc, Rd, Re, and Rf independently of one another mean -H, -Hal, -CH3 or -CH2CH3; and-Hal means -F, -Cl, or -Br;and(ii) repeating units according to general formula (II) and / or (III)wherein in each casen means 0 or 1 ;R1 means linear or branched saturated alkyl group having at least 3 carbon atoms; and R2 means -H, -CH3or -CH2CH3.

[0026] The process according to the invention is for the preparation of a polyisoolefin homo-or copolymer, preferably selected from butyl rubber, polyisobutylene and poly(isobutylene-co-para methyl styrene), more preferably butyl rubber.

[0027] When the polyisoolefin homo- or copolymer according to the invention is butyl rubber, it is prepared by polymerizing at least one isoolefin monomer and at least one multiolefm monomer.

[0028] When the polyisoolefin homo- or copolymer according to the invention is polyisobutylene, it is prepared by polymerizing isobutylene.

[0029] When the polyisoolefin homo- or copolymer according to the invention is poly(isobu-tylene-co-para methyl styrene), it is prepared by polymerizing isobutylene and para methyl styrene.

[0030] The polymerization according to the invention is performed in the presence of a preformed polymeric stabilizer. The polymeric stabilizer is preformed, i.e. it is already present in polymeric form when it is combined with the at least one isoolefin monomer and optionally at least one copolymerizable monomer, preferably multiolefin monomer.

[0031] Preferably, the preformed polymeric stabilizer is inert and free of cationically active unsaturation or functional group under the conditions for polymerizing the at least one isoolefin monomer and optional at least one copolymerizable monomer, preferably multiolefin monomer. Thus, the preformed polymeric stabilizer preferably does not react with the at least one isoolefin monomer and the optional at least one copolymerizable monomer, preferably mul-tiolefin monomer, when they are polymerized in order to afford the polyisoolefin homo- or copolymer according to the invention, preferably selected from butyl rubber, polyisobutylene and poly(isobutylene-co-para methyl styrene), more preferably butyl rubber.

[0032] The preformed polymeric stabilizer according to the invention comprises or essentially consists of repeating units according to general formula (IA) or (IB) or (IC), and repeating units according to formula (II) and / or (III).

[0033] In preferred embodiments, the preformed polymeric stabilizer comprises or essentially consists of repeating units according to general formula (IA) or (IB) or (IC) and repeating units according to formula (II). Preferably, the preformed polymeric stabilizer does not comprise repeating units according to general formula (III).

[0034] In other preferred embodiments, the preformed polymeric stabilizer comprises or essentially consists of repeating units according to general formula (IA) or (IB) or (IC) and repeating units according to formula (III). Preferably, the preformed polymeric stabilizer does not comprise repeating units according to general formula (II).

[0035] In further preferred embodiments, the preformed polymeric stabilizer comprises or essentially consists of repeating units according to general formula (IA) or (IB) or (IC), and repeating units according to formula (II), and repeating units according to formula (III).

[0036] Preferably, R1 has at least 4 carbon atoms, preferably at least 5 carbon atoms, more preferably at least 6 carbon atoms, still more preferably at least 7 carbon atoms, yet morepreferably at least 8 carbon atoms, even more preferably at least 9 carbon atoms, most preferably at least 10 carbon atoms, and in particular at least 11 carbon atoms.

[0037] Preferably, R1 is branched.

[0038] In preferred embodiments, R2 means -H.

[0039] In other preferred embodiments, R2 means -CH3.

[0040] In further preferred embodiments, R2 means -CH2CH3.

[0041] In preferred embodiments, n means 1.

[0042] In other preferred embodiments, n means 0.

[0043] Repeating units according to general formula (IA)are preferably derived from styrene (Ra = Rb = Rc =Rd = Re = Rf = -H). Thus, the preformed polymeric stabilizer according to the invention may be regarded as a styrene copolymer, preferably a styrene block copolymer. Unsubstituted styrene, monosubstituted styrene, disubstituted styrene and trisubstituted styrene are preferred, unsubstituted styrene is most preferred.

[0044] Other repeating units according to general formula (IA) are preferably derived from alpha-methyl-styrene (Ra = Rb = Rc =Rd = Re = -H; Rf = -CH3).

[0045] Further repeating units according to general formula (IA) are preferably derived from 4-chloro-styrene (Ra = Rb = Rd = Re = Rf = -H; Rc = -Cl).

[0046] Repeating units according to general formula (IB)are preferably derived from vinyl chloride (Hal = -Cl) or vinyl bromide (Hal = -Br). Thus, the preformed polymeric stabilizer according to the invention may be regarded as a polyvinylchloride copolymer, preferably a polyvinyl chloride block copolymer, or a polyvinyl bromide copolymer, preferably a polyvinyl bromide block copolymer.

[0047] Repeating units according to general formula (IC)are preferably derived from chloroprene (Hal = -Cl) that is subsequently hydrogenated. Thus, the preformed polymeric stabilizer according to the invention may be regarded as a hydrogenated chloroprene copolymer, preferably a hydrogenated chloroprene block copolymer.

[0048] Repeating units according to general formula (II)are preferably derived from alkenes, preferably from terpenes, more preferably monoterpenes (CIO) or sesquiterpenes (Cl 5).

[0049] When n means 0, repeating units according to general formula (II) are according to general formula (Il-a):

[0050] Repeating units of general formula (Il-a) are preferably derived from 1 -alkenes, preferably with the general structure CH2=CR1*R2*, wherein Rl* means linear or branched, unsaturated or saturated alkyl group having at least 3 carbon atoms; and R2* means -H, -CH3, -CH=CH2 or -CH2CH3. When Rl* means unsaturated alkyl group and / or when R2* means -CH=CH2, the ethylenic unsaturation is preferably subsequently hydrogenated.

[0051] Preferred 1-alkenes of this type, i.e. in accordance with the general structure CH2=CR1*R2*, are linear and contain a single ethylenic unsaturation, which preferably reacts in the preformation of the preformed polymeric stabilizer. Preferred examples include but are not limited to 1 -pentene, 1 -hexene, 1 -heptene or 1 -octene.

[0052] Further preferred 1-alkenes of this type, i.e. in accordance with the general structure CH2=CR1*R2*, are branched and contain a single ethylenic unsaturation, which preferablyreacts in the preformation of the preformed polymeric stabilizer. Preferred examples include but are not limited to 3,7-dimethyl-l-octene, 4-methy 1-1 -hexene, 4,4-dimethyl-l-pentene, and 2,4,4-trimethyl-l -pentene (DIB).

[0053] Still further preferred 1 -alkenes of this type, i. e. in accordance with the general structure CH2=CR1*R2*, are branched and contain multiple ethylenic unsaturations. Preferred examples include terpenes, preferably monoterpenes (CIO) and sesquiterpenes (Cl 5). Preferred examples, wherein the CH2=CH-Rl*groups have been highlighted that preferably react in the preformation of the preformed polymeric stabilizer, include but are not limited to• myrcene, i.e.a -myrcene P-myrcene• ocimene, preferably a-ocimene or P-ocimene (in each case including Z- and E-isomers), i.e.trans-oc-ocimene trans- -ocimenecis-oc-ocimene cis-P-ocimene• allocimene (including Z- and E-isomers), i.e.trans-trans-allocimene cis-trans- allocimene• famesene, preferably a-famesene or -famesene (in each case including Z- and E-isomers), i.e.

[0054] The additional ethylenic unsaturations, which preferably do not react in the preformation of the preformed polymeric stabilizer, are preferably subsequently hydrogenated.

[0055] For example, when -famesene reacts with its ethylenic unsaturation at position Cl, the following intermediate repeating unit is obtained, which according to the invention is preferably subsequently hydrogenated:

[0056] Under these circumstances, in the hydrogenated productR1 means -CH(CH3)CH2CH2CH2CH(CH3)CH2CH2CH2CH(CH3)2andR2 means -H.

[0057] Similarly, when -famesene reacts with its ethylenic unsaturation at position C3, the following intermediate repeating unit is obtained, which according to the invention is preferably subsequently hydrogenated:

[0058] Under these circumstances, in the hydrogenated productR1 means -CH2CH2CH2CH(CH3)CH2CH2CH2CH(CH3)2 andR2 means -CH2CH3.

[0059] When n means 1, repeating units according to general formula (II) are according to general formula (Il-b):(II-b)

[0060] Preferably, when in the repeating units according to general formula (II) n means 1, R2 means -H, and the repeating units according to general formula (Il-b) are according to general formula (II-b'):

[0061] Repeating units of general formula (II-b1) are preferably derived from 1,3-alkadienes, preferably with the general structure CH2=CH-CR1*=CH-, wherein Rl* means linear or branched, unsaturated or saturated alkyl group having at least 3 carbon atoms. The additional ethylenic unsaturations, which preferably do not react in the preformation of the preformed polymeric stabilizer, are preferably subsequently hydrogenated.

[0062] Preferred 1,3-alkadienes of this type, i.e. in accordance with the general structure CH2=CH-CR1*=CH-, are branched and contain multiple ethylenic unsaturations. Preferred examples include terpenes, preferably monoterpenes (CIO) and sesquiterpenes (Cl 5). Preferred examples, wherein the CH2=CH-CRl*=CH-groups have been highlighted that preferably react in the preformation of the preformed polymeric stabilizer, include but are not limited myrcene, i.e.myrcene• famesene, preferably -famesene (including Z- and E-isomers), i.e.

[0063] The additional ethylenic unsaturations, which preferably do not react in the preformation of the preformed polymeric stabilizer, are preferably subsequently hydrogenated.

[0064] For example, when [3-famesene reacts with its two ethylenic unsaturations at positions Cl and C3, the following intermediate repeating unit is obtained, which according to the invention is preferably subsequently hydrogenated:

[0065] Under these circumstances, in the hydrogenated productR1 means -CH2CH2CH2CH(CH3)CH2CH2CH2CH(CH3)2 andR2 means -H.

[0066] Repeating units according to general formula (III)are preferably also derived from alkenes, preferably terpenes, more preferably monoterpenes (CIO) or sesquiterpenes (Cl 5).

[0067] When n means 0, repeating units according to general formula (III) are according to general formula (Ill-a):(m-a)

[0068] When n means 1, repeating units according to general formula (III) are according to general formula (Ill-b):

[0069] Repeating units of general formula (Ill-b) are preferably derived from 1,3-alkadienes, preferably with the general structure CH2=CH-CR2*=CR1*-, wherein Rl* means linear or branched, unsaturated or saturated alkyl group having at least 3 carbon atoms and R2* means -H, -CH3, -CH=CH2 or -CH2CH3. The additional ethylenic unsaturations, which preferably do not react in the preformation of the preformed polymeric stabilizer, are preferably subsequently hydrogenated.

[0070] Preferred 1,3-alkadienes of this type, i.e. in accordance with the general structure CH2=CH-CR1*=CH-, are branched and contain multiple ethylenic unsaturations. Preferred examples include terpenes, preferably monoterpenes (CIO) and sesquiterpenes (Cl 5). Preferred examples, wherein the CH2=CH-CRl*=CH-groups have been highlighted that preferably react in the preformation of the preformed polymeric stabilizer, include but are not limited famesene, preferably a-famesene (including Z- and E-isomers), i.e.a-farnesene• ocimene, preferably a-ocimene or -ocimene (in each case including Z- and E-isomers), i.e.a-ocimene P-ocimene

[0071] The additional ethylenic unsaturations, which preferably do not react in the preformation of the preformed polymeric stabilizer, are preferably subsequently hydrogenated.

[0072] For example, when P-ocimene reacts with its two ethylenic unsaturations at positions Cl and C3, the following intermediate repeating unit is obtained, which according to the invention is preferably subsequently hydrogenated:

[0073] Under these circumstances, in the hydrogenated productR1 means -CH2CH2CH(CH3)2; andR2 means -CH3.

[0074] In preferred embodiments, the preformed polymeric stabilizer comprises repeating units according to general formula (II), whereinn means 0;R1 is selected from -CH2CH2CH3, -CH2CH2CH2CH3, -CH2CH2CH2CH2CH3, -CH2CH2CH2CH2CH2CH3-CH(CH3)CH2CH2CH2CH(CH3)2, -CH2CH(CH3)CH2CH3, -CH2C(CH3)3, and -CH(CH3)CH2CH2CH2CH(CH3)CH2CH2CH2CH(CH3)2; andR2 means -H.

[0075] In other preferred embodiments, the preformed polymeric stabilizer comprises repeating units according to general formula (II), whereinn means 0;R1 means -CffeC CHs andR2 means -CH3.

[0076] In further preferred embodiments, the preformed polymeric stabilizer comprises repeating units according to general formula (II), whereinn means 0;R1 means -CH2CH2CH2CH(CH3)2; andR2 means -CH2CH3.

[0077] In still further preferred embodiments, the preformed polymeric stabilizer comprises repeating units according to general formula (II), whereinn means 1;R1 means -CH2CH2CH2CH(CH3)2 or -CH2CH2CH2CH(CH3)CH2CH2CH2-CH(CH3)2; preferably-CH2CH2CH2CH(CH3)CH2CH2CH2CH(CH3)2; andR2 means -H.

[0078] In yet further preferred embodiments, the preformed polymeric stabilizer comprises repeating units according to general formula (III), whereinn means 1;R1 means -CH2CH2CH(CH3)2 or -CH2CH2CH(CH3)CH2CH2CH2CH(CH3)2; andR2 means -CH3.

[0079] In preferred embodiments, the preformed polymeric stabilizer is a block copolymer comprising or essentially consisting of at least one block essentially consisting of a multitude of p repeating units according to general formula (IA)preferably wherein p means 3 to 1000;and at least one block essentially consisting of a multitude of q' repeating units according to general formula (IIA)whereinRl' independently of one another means linear or branched saturated alkyl group having at least 3 carbon atoms; preferably branched saturated alkyl group having at least 22 carbon atoms, more preferably a -polyisobutene chain; andq' preferably means 3 to 1000.

[0080] Highly reactive polyisobutene (HR-PIB) having an a-olefin content of greater than 75% or even greater than 85% is commercially available e.g. from BASF under the tradename Glis-sopal® or from TPC Group under the trade designation TPC 545. Preferably, said multitude of q' repeating units according to general formula (IIA) is derived from polymerizing such highly reactive polyisobutene. The individual meaning of Rl' in the above definition reflects a certain degree of poly dispersity of the highly reactive polyisobutene such that the individual length of -polyisobutene chain may vary from unit to unit.

[0081] In other preferred embodiments, the preformed polymeric stabilizer is a block copolymer comprising or essentially consisting of at least one block essentially consisting of a multitude of p repeating units according to general formula (IA)preferably wherein p means 3 to 1000;and at least one block essentially consisting of a multitude of q repeating units according to general formula (II)preferably wherein q means 3 to 1000.

[0082] In further preferred embodiments, the preformed polymeric stabilizer is a triblock copolymer comprising or essentially consisting of a block essentially consisting of a multitude of q repeating units according to general formula (II)preferably wherein q means 3 to 1000;between two blocks each independently of one another essentially consisting of a multitude of p repeating units according to general formula (IA)preferably wherein p independently of one another means 3 to 1000.

[0083] The preformed polymeric stabilizer according to the invention is preferably essentially free of ethylenic unsaturations.

[0084] In preferred embodiments, the preformed polymeric stabilizer is a hydrogenated styrene terpene copolymer; preferably a hydrogenated styrene terpene block copolymer. In preferred embodiments, said terpene is a monoterpene. In other preferred embodiments, said terpene is a sesquiterpene.

[0085] In preferred embodiments, the preformed polymeric stabilizer is a hydrogenated styrene myrcene copolymer; preferably a hydrogenated styrene myrcene block copolymer.

[0086] In other preferred embodiments, the preformed polymeric stabilizer is a hydrogenated styrene ocimene copolymer; preferably a hydrogenated styrene ocimene block copolymer.

[0087] In further preferred embodiments, the preformed polymeric stabilizer is a hydrogenated styrene famesene copolymer; preferably a hydrogenated styrene famesene block copolymer.

[0088] Preferably, the preformed polymeric stabilizer has a weight content of repeating units according to general formula (IA) within the range of at least 10 wt.-%, preferably at least 12.5 wt.-%, more preferably at least 15 wt.-%, still more preferably at least 17.5 wt.-%, yet more preferably at least 20 wt.-%, even more preferably at least 22.5 wt.-%, most preferably at least 25 wt.-%, and in particular within the range of from 25 to 75 wt.-%, relative to the total weight of the preformed polymeric stabilizer.

[0089] Preferably, the preformed polymeric stabilizer has a weight content of repeating units according to general formula (II) and / or (III) within the range of at most 90 wt.-%, preferably at most 87.5 wt.-%, more preferably at most 85 wt.-%, still more preferably at most 82.5 wt.-%, yet more preferably at most 80 wt.-%, even more preferably at most 77.5 wt.-%, most preferably at most 75 wt.-%, and in particular within the range of from 25 to 75 wt.-%, relative to the total weight of the preformed polymeric stabilizer.

[0090] Preferably, the preformed polymeric stabilizer has a melt flow rate determined according to ISO 1133 (230°C, 2.16 kg) of at most 500 g / 10 min, preferably at most 400 g / 10 min, more preferably at most 300 g / 10 min, still more preferably at most 200 g / 10 min, yet more preferably at most 100 g / 10 min, even more preferably at most 75 g / 10 min, most preferably at most 50 g / 10 min, and in particular at most 25 g / 10 min.

[0091] Preferably, the ratio of the sum of the total weight of the at least one isoolefin monomer and the total weight of the optional at least one copolymerizable monomer, preferably mul-tiolefin monomer, relative to the weight of the preformed polymeric stabilizer is at least 5, preferably at least 10, more preferably at least 15, still more preferably at least 20, yet more preferably at least 25, even more preferably at least 30, most preferably at least 35, and in particular at least 40.

[0092] Preferably, the at least one isoolefin monomer is selected from C4 to Ci6 isoolefins; preferably from C4 to Cs isoolefins; more preferably from the group consisting of isobutene, 2-methyl-1 -butene, 3-methyl-l -butene, 2-methyl-2-butene, 4-methyl-l -pentene and mixtures thereof; most preferably isobutene.

[0093] Preferably, the total weight content of the at least one isoolefin monomer in the prepared polyisoolefin homo- or copolymer, preferably selected from butyl rubber, polyisobutylene and poly(isobutylene-co-para methyl styrene), more preferably butyl rubber, is within the range offrom 70 to 99.5 wt.-%, preferably 80 to 99.5 wt.-%, more preferably 90 to 99.5 wt.-%, relative to the total weight of the prepared poly isoolefin homo- or copolymer, preferably selected from butyl rubber, polyisobutylene and poly(isobutylene-co-para methyl styrene).

[0094] Preferably, the optional at least one copolymerizable monomer, preferably multiolefm monomer, is selected from conjugated C4 to C14 multiolefms or para methyl styrene; preferably from conjugated C4 to C10 diolefins or para methyl styrene; more preferably from the group consisting of isoprene, para methyl styrene, butadiene, 2-methylbutadiene, 2,4-dimethylbuta-diene, piperyline, 3-methyl-l,3-pentadiene, 2,4-hexadiene, 2-neopentylbutadiene, 2-methyl-1,5-hexadiene, 2,5-dimethyl-2,4-hexadiene, 2-methyl-l,4-pentadiene, 2-methyl-l,6-heptadi-ene, cyclopentadiene, methylcyclopentadiene, cyclohexadiene, 1-vinyl-cyclohexadiene and mixtures thereof; most preferably isoprene and para methyl styrene.

[0095] Preferably, the total weight content of the optional at least one copolymerizable monomer, preferably multiolefm monomer, is within the range of from 0.5 to 30 wt.-%, preferably 0.5 to 20 wt.-%, more preferably 0.5 to 10 wt.-%, relative to the total weight of the prepared polyisoolefin homo- or copolymer, preferably selected from butyl rubber, polyisobutylene and poly(isobutylene-co-para methyl styrene), more preferably butyl rubber.

[0096] Preferably, the polymerization is performed as a slurry process.

[0097] Preferably, the polymerization is performed in a solvent selected from the group consisting of hydrofluorocarbons and chlorinated hydrocarbons and mixtures thereof, preferably from chlorinated hydrocarbons, preferably from methyl chloride, methylene chloride, vinyl chloride, ethyl chloride, and mixtures thereof; preferably methyl chloride.

[0098] It is possible to include an optional third monomer to produce a butyl terpolymer. For example, it is possible to include a styrenic monomer in the monomer mixture, preferably in an amount up to about 15 wt.-% of the monomer mixture. The preferred styrenic monomer may be selected from the group comprising p-methylstyrene, styrene, a-methylstyrene, p-chlorosty-rene, p-methoxystyrene, cyclopentadiene, methylcyclopentadiene, indene, indene derivatives and mixtures thereof. The most preferred styrenic monomer may be selected from the group comprising styrene, p-methylstyrene and mixtures thereof.

[0099] Suitable polymerization processes for producing butyl rubber polymers are known and are further described in e.g. US 2,356,128.

[0100] Preferred Friedel-Crafts catalysts include but are not limited to AlCh, TiCh, VCh, VCI3 and BCI3. It is desirable that a catalyst is selected that is soluble in the polymerization fluid. A preferred catalyst is AlCh.

[0101] Preferably, the process according to the invention comprises the additional step of halogenating the butyl rubber.

[0102] Preferably, the halogenated butyl rubber comprises a halogen in the amount of from about 0.1 to about 8 wt.-% of the butyl rubber. More preferably, the halogenated butyl polymer comprises a halogen in the amount of from about 0.5 to about 4 wt.-% of the butyl rubber. Most preferably, the halogenated butyl polymer comprises a halogen in the amount of from about 1.5 to about 3.0 wt.-% of the butyl rubber. The butyl rubber may be halogenated either after it is produced or while dissolved in the polymerization fluid using techniques known to persons skilled in the art, such as those described in Ullmann's Encyclopedia of Industrial Chemistry (5th completely revised edition, Volume A23; Editors Elvers et al.).

[0103] Preferably, the process according to the invention comprises the additional step of curing the butyl rubber.

[0104] The butyl rubber may thus be cured or uncured. When cured, the butyl rubber may comprise components derived from a curing system. The choice of curing system suitable for use is not particularly restricted. The curing system may be sulfur-based or peroxide-based.

[0105] A typical sulfur-based curing system comprises: (i) a metal oxide, (ii) elemental sulfur and (iii) at least one sulfur-based accelerator. The use of metal oxides as a component in the curing system is well known in the art. A suitable metal oxide is zinc oxide, which is typically used in the amount of from about 1 to about 10, preferably from about 2 to about 5, parts by weight per hundred parts by weight butyl rubber. Elemental sulfur, comprising component (ii) of the preferred curing system is typically used in amounts of from about 0.2 to about 2 parts by weight, per hundred parts by weight butyl rubber. Suitable sulfur-based accelerators (component (iii) of the preferred curing system) are typically used in amounts of from about 0.5 to about 3 parts by weight, per hundred parts by weight butyl rubber. Non-limiting examples of useful sulfur-based accelerators may be selected from the thiuram sulfides such as tetramethyl thiuram disulfide (TMTD), the thiocarbamates such as zinc dimethyl dithiocarbamate (ZDC) and the thiazyl and benzothiazyl compounds such as mercaptobenzothiazyl disulfide (MBTS). Preferably, the sulphur based accelerator is mercaptobenzothiazyl disulfide.

[0106] A typical peroxide-based curing system comprises a peroxide curing agent, for example, dicumyl peroxide, di -tert. -butyl peroxide, benzoyl peroxide, 2, 2'-bis(tert. -butylperoxy diisopropylbenzene (Vulcup.RTM. 40KE), benzoyl peroxide, 2,5-dimethyl-2,5-di(tert-bu-tylperoxy)-hexyne-3,2,5-dimethyl-2,5-di(benzoy- lperoxy)hexane, (2, 5-bis(tert. -butylperoxy )-2,5-dimethyl hexane and the like. A preferred peroxide curing agent comprising dicumyl peroxide is commercially available under the trademark DiCup 40C. The peroxide curing agent is suitably used in an amount of 0.2 to 7 parts per hundred parts of butyl rubber (phr), preferably 1 to 6 phr, more preferably about 4 phr. Peroxide curing co-agents can also be used. Mention is made of triallyl isocyanurate (TAIC), commercially available under the trademark DIAK 7 from DuPont or N,N'-m-phenylene dimaleimide know as HVA-2 (DuPont Dow), triallyl cy-anurate (TAC) or liquid polybutadiene known as Ricon D 153 (supplied by Ricon Resins). Amounts can be equivalent to those of the peroxide curing agent, or less.

[0033] Stabilizers, anti-oxidants and tackifiers may also be added in the usual way and in the normal amounts for compounding butyl-type rubbery polymers.

[0107] Another aspect of the invention relates to a composition comprising a polyisoolefin homo- or copolymer, preferably selected from butyl rubber, polyisobutylene and poly(isobu-tylene-co-para methyl styrene), more preferably butyl rubber, obtainable by the process according to the invention as described above. The composition will typically comprise or essentially consist of- the polyisoolefin homo- or copolymer according to the invention, preferably selected from butyl rubber, polyisobutylene and poly(isobutylene-co-para methyl styrene), more preferably butyl rubber, this produced by polymerizing the at least one isoolefin monomer and the optional at least one copolymerizable monomer, preferably multiolefin monomer; and - the preformed polymeric stabilizer according to the invention.

[0108] Another aspect of the invention relates to the use of a preformed polymeric stabilizer according to the invention as described above as a dispersant in a process according to the invention as described above.

[0109] EXAMPLES

[0110] The following examples further illustrate the invention but are not to be construed as limiting its scope.

[0111] Materials:

[0112] Methyl chloride (99.5%, methyl chloride) was purchased from Linde. Isobutene (99.5%) was purchased from Air Liquide. Isoprene (2-methyl-l,3-butadiene), aluminum chloride (99.99%), methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK) and ethyl acetate were purchased from Sigma Aldrich.

[0113] Isoprene was distilled over calcium hydride before use; A1CL, methyl ethyl ketone (MEK) and ethyl acetate were used as received. Irganox® 1076 was purchased from Ciba and used as received. Hexanes and ethanol were used as received from VWR. TPC 1105 (liquid PIB) was used as received from TPC. HiSil 233 was used as received from PPG.

[0114] Different additives were used as received from a variety of suppliers as follows: oleic acid, sodium stearate, palmitic acid, lauric acid, gelatin (VWR); oleyl alcohol, methyl oleate, famesol, adipic acid, octanoic acid, linoleic acid, ethyl cellulose, pectin, hydroxyethyl starch, polyvinyl stearate, polyvinyl acetate (Sigma Aldrich); Piccolyte® Al 15, Cl 15, Ml 15, SI 15 (DRT / Pinova); styrenated terpene resin, hydrogenated terpene resin, hydrogenated terpene phenolic resin, terpene resin (Forev erest); Methyl Cellulose F4M, J12MS (DuPont); FX Lignin A, B, C (McMaster University); cocoyl isethionate, glycerol oleate (Soaps and More); KR01 (Ineos); Septon® BIO 902, 903, 904, Hybrar® 7125F, 7133F, FSBR 203, LIR 290, ISOBAM® 04, ISOBAM® 104 (Kuraray); SIBSTAR® 073T, 103T (Kaneka); Krasol® F 3000 (polyfamesene), Krasol® F 3100 (hydrogenated polyfamesene), Ricon® 130 (Total-Cray Valley); Levapren® 600, Levamelt® 800 (ARLANXEO). Ozonated butyl was prepared by exposure of RB301 to ozone in hexanes for 9 h.

[0115] Example 1 - slurry stability tests:

[0116] Part a)

[0117] The slurry stability test approximates the polarity of the butyl rubber system in an environment easier to handle in a laboratory setting. Methyl chloride was replaced by methyl ethyl ketone, and a growing butyl rubber chain was replaced by low molecular weight PIB (TPC 1105), a butyl rubber or liquid polybutadiene (Ricon 130).

[0118] 0.25 g (or 0.05 g or 0.02 g as specified) of additive was dissolved in 15 mL of methyl ethyl ketone on a shaker overnight. 15 g of TPC 1105 (or Ricon® 130 or RB301 in hexanes as specified) was added and the solution was capped. The solution was allowed to shake for 1 h, followed by observation for separation time.

[0119] The table here below summarizes results of additive screening:< <<<<<>>

[0120] Many different categories of additives were examined as broken down in the above table. Solubility and separation time were recorded including images for additives that did not dissolve fully and any interfaces that could not be easily explained by a time to separate. In some of the polymer examples it appeared that the polymer was dissolved, but a powder, possibly a talc or other pellet stabilizer was insoluble.

[0121] As demonstrated, some additives such as sodium stearate had already separated at 1 minute, but KR01 (SBS) and Septon® BIO SF 902 were fully emulsified. Other additives suchas PF (poly famesene) and H-PF (hydrogenated polyfamesene) had started to separate, but there is some emulsion at the interface.

[0122] Septon® BIO SF 902 and SF 903 were the best performers under these conditions, Septan® BIO SF 903 having a separation time >190 x longer than the rest of the additives.

[0123] A system with no additive typically separated in 2-3 minutes and a system with a traditional additive, such as KR01, a styrene-butadiene-styrene block copolymer (SBS) (US 4,252,710 A, US 4,474,924 A), separated in approximately 10 minutes.

[0124] Part b)

[0125] Some of the more promising additives from the above chart were tested again in accordance with part a) but at lowered levels (0.05 g and 0.02 g vs. 0.25 g), and the separation time was measured.

[0126] The results are compiled in the table here below:

[0127] The above table shows that Septon® BIO SF 903 outperformed anything else tested. At 8% of the stabilizer level initially added, Septon® BIO SF 903 had double the separation time (30 minutes) than any other additive at full loading. Ethyl cellulose also showed promise as a stabilizer outside of the amphiphilic polymer category, with a separation time of 6 minutes at 8% of the initial level.

[0128] Part c)

[0129] The interface separation test was also completed with a few of the additives in accordance with part a) and b), but in methyl isobutyl ketone (MIBK) and ethyl acetate instead of methyl ethyl ketone (MEK) to confirm the stabilization applied across other polar solvents. Unfortunately, the low molecular weight PIB dissolved in MIBK, so this was not able to be tested for separation time. The table below shows the solubility of the additives and phase separation time in ethyl acetate.

[0130] The results with ethyl acetate (0.25 g in 15 mL) are compiled in the table here below:>

[0131] Again, Septon® BIO SF 903 outperformed any other additive for interface stabilization, having a separation time >40x longer than any other additive.

[0132] Part d)

[0133] In another interface stabilization test with these additives, the ability to stabilize liquid poly butadiene (Ricon 130) instead of low molecular weight PIB in methyl ethyl ketone (MEK) was tested. Ricon 130 is much more polar than PIB, so it was fully soluble in methyl ethyl ketone. Interestingly, the additives that stabilized PIB in solution, caused Ricon 130 to fall out of solution.

[0134] This destabilization was fastest with the Septon® BIO SF series indicating that the polyfamesene portion, which interacted with PIB to keep it emulsified in methyl ethyl ketone, repelled butadiene rubber and pushed it out of methyl ethyl ketone.

[0135] This was consistent with butadiene and butyl rubber preferring not to mix together in the solid state.

[0136] Example 2 - addition of additives to glovebox polymerizations

[0137] Glovebox Warm-Up Test: Typical reactions were performed as follows in an MBRAUN® glovebox (MB 200G). A catalyst solution of approximately 0.3 g of A1CL in 100 mL of methyl chloride was prepared in a pentane bath cooled to -30°C and allowed to stir for 30 minutes. Potential slurry stabilizers were then dissolved in methyl chloride at -30°C at 0.05 g in 50 mL by stirring for up to 1 hour. A second pentane bath was cooled to -95°C and a 600 mL stainless steel reactor was allowed to cool. 180 mL of total liquid methyl chloride (corrected for volume added with additive) was added to the reactor, followed by 20 mL of liquid isobutene, the additive solution if required and 0.7 mL of isoprene at room temperature.

[0138] Polymerization reactions were initiated using 3-15 mL of the catalyst solution once the reactor temperature was below -90°C. Polymerizations were allowed to continue for 5 minutes, at which point they were poured into a precooled stainless-steel tray and videoed by go-pro asthey warmed outside of the pentane bath. The temperature was manually recorded for different times on the go-pro to correlate photo snapshots from video with warm up temperatures for analysis.

[0139] As well as many of the highest performers from the screening study, some commonly available additives such as oleic acid and sodium stearate were tested in the glovebox. In order for an additive to be applicable in butyl rubber polymerization, it must dissolve in methyl chloride or mixed feeds and it must not poison the carbocationic polymerization.

[0140] The summary of the additives tested, their solubility in methyl chloride and their impact on the amount of initiator required for polymerization at 0.05 g on polymerization is included in the table here below:

[0141] For all examples the stabilizer was added at 0.05 g relative to 20 mL of isobutene, 0.7 mL isoprene and 180 mL methyl chloride.

[0142] It was observed that many additives poisoned the polymerization, but sodium stearate and Septon® BIO SF 903 did not.

[0143] Some of the reactions that proceeded without very much poisoning were assessed for slurry stability upon warming up. Because the slurry stability was difficult to monitor during areaction, the reaction was allowed to run for 5 minutes, followed by transfer to a precooled tray without the addition of the NaOH / EtOH shortstopping solution. Photos were taken every 5 °C during the warmup to assess when the slurry collapsed. Due to the sensitivity of this test and slurry stability in general, results were only compared within a single day using the same initiator solution and atmosphere conditions.

[0144] The first test demonstrated that Septon® BIO SF 903 added at 0.01g provided some slurry stabilization up to -70 °C, and 0.05 g provided stabilization up to -55 °C as compared to -75 °C in the control without additives. A run on a different day also demonstrated that Septon® BIO SF 903 stabilizes the slurry much better than Hybrar® 7125F, another hydrogenated styrene block copolymer with a different nonpolar fraction, in which the slurry started to destabilize at -70 °C.

[0145] KR01 (SBS) showed only average times in the methyl ethyl ketone test (9 minutes), but it did demonstrate good slurry stability upon polymerization warm up. Although this is true, the mechanism of action for slurry stabilization was different than with Septon® BIO SF. The butadiene fraction of KR01 (SBS) was incorporated into the cationic polymerization, so the styrene block copolymer was chemically bound to the butyl rubber rather than favorably interacting with the non-polar butyl rubber as in the hydrogenated versions of stabilizers.

[0146] In addition, 4 mL of initiator (vs. a standard 3 mL) was needed for this reaction because of the additional double bonds in KR01 (SBS). Although the slurry looked stable up to -60 °C with 4 mL of initiator in this test with KR01, the butyl rubber product was quite different.

[0147] Figure shows GPC traces demonstrating that Septon® BIO SF did not incorporate into butyl rubber, whereas KR01 (SBS) resulted in a high molecular weight Branched fraction.

[0148] As demonstrated addition of KR01 (SBS) resulted in a branched butyl rubber polymer with a high molecular weight shoulder in the GPC and with the styrene groups incorporated. In contrast, Septon® BIO SF 902 and Septon® BIO SF 903 did not create a branched fraction in butyl rubber or change the molecular weight of the main polymer peak. The molecular weight of Septon® BIO SF 903 overlaps with butyl rubber so if difficult to be observed in the GPC, but the second peak in the GPC trace for the Septon® BIO SF 902 reaction appeared as a low molecular weight shoulder, that upon further inspection lined up with pure Septon® BIO SF 902 polymer.

[0149] Another interesting result from the test in methyl ethyl ketone of Example 1 was that ethyl cellulose stabilized the slurry. It was the best candidate for polar / non polar interfacestabilization that was not a styrenic block copolymer. Unfortunately, the addition of ethyl cellulose to the polymerization caused some poisoning. Slurry stability was achieved with 0.05 g ethyl cellulose beyond -55 °C, but 15 mL of initiator was required rather than the usual 3 mL. There were also some solubility issues where ethyl cellulose gelled instead of dissolving in methyl chloride.

[0150] Since ethyl cellulose poisoned the polymerization, addition of additive at the end of the polymerization was also explored. There was slurry stabilization up to -60 °C achieved with Septon® BIO SF 903 being added at the end of the polymerization instead of prior to the polymerization, which further supported that it stabilizes without being incorporated during polymerization. In contrast, ethyl cellulose collapsed the slurry upon addition at the end of the polymerization. This is likely due to its poison effect by stopping the active sites of the reaction rather than stabilizing the active slurry.

[0151] A few other additives were also tested in the butyl polymerization. However, neither hydrogenated polyfamesene, nor oleic acid were able to demonstrate slurry stabilization for a growing butyl rubber chain. Oleic acid also demonstrated some poisoning of the cationic polymerization.

[0152] Summary and Conclusions

[0153] Different additives were investigated using methyl ethyl ketone and low molecular weight polyisobutene at room temperature to model the interaction between butyl rubber and methyl chloride at -95 °C. It was found that a block copolymer of styrene and polyfamesene (Septon® BIO SF) had improved ability to stabilize this interface beyond any other tested compatibilizers by more than 100 x. This improvement in interface stabilization was also carried over to a system of polyisobutene in ethyl acetate to demonstrate that it was applicable across different polar solvents (Example 1). Interface stabilization was observed to be lOOx longer than other additives in polar solvents with liquid polyisobutene.

[0154] In the methyl chloride polymerization at -95 °C, Septon® BIO SF 903 was also able to stabilize a butyl rubber slurry in methyl chloride upon warm up. A polymerization containing 0.05 g of Septon® BIO SF 903 was stable to approximately -55 °C, while a control polymerization was only stable to -75 °C. The interface stabilization of Septon® BIO SF 903 is particularly special because it did not alter the rubber polymer to form a branched product like some traditional additives do._This stabilization has also been shown to be specific to a butylrubber / polyisobutene polymer and specific to when Septon® BIO SF 903 is dissolved in the liquid state. Growing butyl rubber chains in polymerizations in methyl chloride remained stable up to 20 °C warmer in the presence of Septon® BIO SF 903 than a control without. As it is hydrogenated, Septon® BIO SF 903 stabilizes by means of interface stabilization alone, without branching or incorporation into the butyl rubber polymer and hence no change in the microstructure is noted.

Claims

1. Claims:

1. A process for preparing a polyisoolefin homo- or copolymer, preferably selected from butyl rubber, polyisobutylene and poly(isobutylene-co-para methyl styrene), more preferably butyl rubber, the process comprising the step ofpolymerizing at least one isoolefin monomer and optionally at least one copolymerizable monomer, preferably multiolefm monomer, in the presence of a preformed polymeric stabilizer;wherein said preformed polymeric stabilizer comprises or essentially consists of (i) repeating units according to general formula (IA), (IB) or (IC)whereinRa, Rb, Re, Rd, Re, and Rf independently of one another mean -H, -Hal, -CH3 or-CH2CH3; preferably -H; and-Hal means -F, -Cl, or -Br;and(ii) repeating units according to general formula (II) and / or (III)wherein in each casen means 0 or 1 ;R1 means linear or branched saturated alkyl group having at least 3 carbon atoms; andR2 means -H, -CH3or -CH2CH3.

2. The process according to claim 1, wherein R1 has at least 4 carbon atoms, preferably at least 5 carbon atoms, more preferably at least 6 carbon atoms, still more preferably at least 7 carbon atoms, yet more preferably at least 8 carbon atoms, even more preferably at least 9 carbon atoms, most preferably at least 10 carbon atoms, and in particular at least 11 carbon atoms.

3. The process according to any of the preceding claims, wherein R1 is branched.

4. The process according to any of the preceding claims, wherein R2 means -H.

5. The process according to any of the preceding claims, wherein said preformed polymeric stabilizer comprises or essentially consists of repeating units according to general formula- one of (IA) or (IB) or (IC); and (II), but not (III);- one of (IA) or (IB) or (IC); and (III), but not (II); or- one of (IA) or (IB) or (IC); and (II), and (III).

6. The process according to any of the preceding claims, wherein the preformed polymeric stabilizer is a block copolymer comprising or essentially consisting of at least one block essentially consisting of a multitude of p repeating units according to general formula (IA)preferably wherein p means 3 to 1000;and at least one block essentially consisting of a multitude of q repeating units according to general formula (II)preferably wherein q means 3 to 1000.

7. The process according to any of the preceding claims, wherein the preformed polymeric stabilizer is a triblock copolymer comprising or essentially consisting of a block essentially consisting of a multitude of q repeating units according to general formula (II)preferably wherein q means 3 to 1000;between two blocks each independently of one another essentially consisting of a multitude of p repeating units according to general formula (IA)preferably wherein p independently of one another means 3 to 1000.

8. The process according to any of the preceding claims, wherein the preformed polymeric stabilizer is essentially free of ethylenic unsaturations.

9. The process according to any of the preceding claims, wherein the preformed polymeric stabilizer is- a hydrogenated styrene myrcene copolymer; preferably a hydrogenated styrene myrcene block copolymer;- a hydrogenated styrene ocimene copolymer; preferably a hydrogenated styrene oci- mene block copolymer; or- a hydrogenated styrene famesene copolymer; preferably a hydrogenated styrene far- nesene block copolymer.

10. The process according to any of the preceding claims, wherein the ratio of the sum of the total weight of the at least one isoolefin monomer and the total weight of the optional at least one copolymerizable monomer, preferably multiolefm monomer, relative to the weight of the preformed polymeric stabilizer is at least 5, preferably at least 10, more preferably at least 15, still more preferably at least 20, yet more preferably at least 25, even more preferably at least 30, most preferably at least 35, and in particular at least 40.

11. The process according to any of the preceding claims, wherein the at least one isoolefin monomer is selected from C4 to Ci6 isoolefins; preferably from C4 to Cs isoolefins; more preferably from the group consisting of isobutene, 2-methyl-l -butene, 3 -methyl- 1 -butene, 2-methyl-2-butene, 4-methyl-l -pentene and mixtures thereof; most preferably isobutene.

12. The process according to any of the preceding claims, wherein the optional at least one copolymerizable monomer, preferably multiolefm monomer, is selected from conjugated C4 to C14 multiolefins or para methyl styrene; preferably from conjugated C4 to C10 diolefins or para methyl styrene; more preferably from the group consisting of isoprene, para methyl styrene, butadiene, 2-methylbutadiene, 2,4-dimethylbutadiene, piperyline, 3 -methyl- 1,3 -pentadiene, 2,4-hexadiene, 2-neopentylbutadiene, 2-methyl-l,5-hexadi- ene, 2,5-dimethyl-2,4-hexadiene, 2-methyl-l,4-pentadiene, 2-methyl-l, 6-heptadiene, cyclopentadiene, methylcyclopentadiene, cyclohexadiene, 1 -vinyl-cyclohexadiene and mixtures thereof; most preferably isoprene and para methyl styrene.

13. The process according to any of the preceding claims, wherein polymerization is performed as a slurry process.

14. The process according to any of the preceding claims, wherein polymerization is performed in a solvent selected from hydrofluorocarbons and chlorinated hydrocarbons and mixtures thereof, preferably from chlorinated hydrocarbons, preferably from methyl chloride, methylene chloride, vinyl chloride, ethyl chloride, and mixtures thereof; preferably methyl chloride.

15. A composition comprising a polyisoolefin homo- or copolymer, preferably selected from butyl rubber, polyisobutylene and poly(isobutylene-co-para methyl styrene), more preferably butyl rubber, obtainable by the process according to any of the preceding claims.

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