Stabilization of polyisobutene

Abstract

The present invention relates to a novel process for stabilizing polyisobutene, to the use of a stabilizer therefor and to the polyisobutene thus stabilized.

Description

[Technical field]

[0001] The present invention relates to a novel process for stabilizing polyisobutene, to the use of a stabilizer therefor and to the polyisobutene stabilized thereby. [Background technology]

[0002] Polyisobutenes are polymers that contain isobutene in polymerized form and are used, for example, in plasters, adhesives, chewing gums and sealants. The processing of such polyisobutenes for the desired use, for example blending with other polymers or other components, is usually carried out in an extruder with the application of heat and shear energy. Exposure of such polyisobutenes to such processing conditions or atmospheric conditions leads to degradation, in particular oxidation- and light-induced depolymerization and degradation. Depolymerization of polyisobutenes results in the free isobutene content in the respective polyisobutene, but the use of such polyisobutenes in chewing gum is prohibited: the threshold value of isobutene monomer in polyisobutenes suitable for chewing gum use is currently 30 ppm.

[0003] In the past, butylated hydroxytoluene (2,6-di-tert-butyl-4-methylphenol, BHT) has often been used as a stabilizer, but BHT tends to discolor polyisobutene. BHT is also sometimes used as an ingredient in chewing gum compositions. See U.S. Pat. No. 5,800,847A.

[0004] Polyisobutene therefore requires stabilizers against such degradation, and there is a need for stabilizers that are more soluble in polyisobutene, more miscible with polyisobutene, and / or more effective.

[0005] EP 35677 A1 discloses a method for producing polyisobutene molecules with a lower average Mv of less than 200,000 in an extruder at 150-400° C., intentionally eliminating polyisobutene with an average Mv of more than 2,000,000. The use of tocopherol in amounts up to 100 ppm by weight produces polyisobutene molecules with lower molecular weights and less carbon black formation compared to the use of the same amount of 2,6-ditert.butyl-4-methylphenol.

[0006] The problem on which the present invention is based differs from that of EP-A-35677-A1 in that the molecular weight of the polyisobutene used should be maintained as far as possible in the extruder and should not be lost in accordance with the process of EP-A-35677-A1.

[0007] Further sterically hindered phenols have been disclosed as stabilizers for polyisobutene, see for example WO 2015 / 095960 A1.

[0008] Sterically hindered phenolic antioxidants such as BHT or those used in the examples of WO 2015 / 095960 A1 can generate a variety of thermal reaction or decomposition products during extrusion and processing of the polymer at high temperatures, or radiation degradation products during sterilization by gamma or electron beam irradiation.

[0009] Arvin et al. have confirmed that organic decomposition products derived from such phenolic antioxidants migrate from polyethylene pipes into drinking water (Brocca, D., Arvin, E, Mosbaek: Water Res., 36, 3675-3680, 2002), and these are commonly known as "Arvin substances" (see Figure 2 in Arvin et al.). Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, there is a need for stabilizers for polyisobutene that do not form such Arvin materials.

[0011] Sterically hindered phenols for the purposes of the present invention refer to compounds having a phenolic moiety and at least one, preferably two, sterically demanding groups in at least one ortho position to the phenolic hydroxy group. Such sterically demanding groups are preferably groups containing at least one tertiary or quaternary carbon atom and / or groups containing at least 6 carbon atoms, more preferably groups selected from the group consisting of isopropyl, tert-butyl, tert-amyl, chloropentyl and cyclohexyl.

[0012] In particular, since polyisobutene may be used in bandages or chewing gum, the improved stabilizer must not be a skin irritant, harmful, or even toxic.

[0013] For the stabilization of polymers in general, multi-component stabilizer compositions containing, inter alia, phenols or chromanols are well known, see for example WO 2013 / 188490 A1, WO 2014 / 140383 A1 or WO 2016 / 81823 A1, but these documents do not disclose their specific use for polyisobutene. [Means for solving the problem]

[0014] This problem is solved by using at least one chromanol, which is described in detail below, in the medium or high molecular weight polyisobutene which is to be protected against degradation.

[0015] This problem is solved by a process for treating polyisobutene in at least one kneader or extruder at a temperature of at least 80 to 160° C., for a time of at most 2 hours and / or with a specific shear energy of at least 0.08 kWh / kg polyisobutene, preferably at least 0.10, more preferably at least 0.15, even more preferably at least 0.15, in particular at least 0.20 kWh / kg polyisobutene, which polyisobutene comprises more than 100 to 5000 ppm of at least one chromanol or at least one chromanol is incorporated into the polyisobutene during this treatment, with a decrease in the average molecular weight (measured in the form of the Staudinger Index J0) of at most 5%. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] A particular chromanol according to the invention has the formula: [ka] (In the formula, R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 and R 14 are each independently hydrogen, C1-C4 alkyl, C1-C4 alkyloxy or C6-C 12 -aryl, In addition, R 5 is C1-C4-alkylcarbonyl, C1-C4-alkyloxycarbonyl, C6-C 12 -arylcarbonyl or C6-C 12 -aryloxycarbonyl, In addition, R 13 and R 14 is C5~C 30 -Alkyl, C5-C 30 -Alkenyl, C5-C 30 -Alkadienyl or C5-C30 -Alkatrienyl, preferably C6-C 20 -alkyl or -alkatoi- enyl, more preferably C 11 ~C 16 -alkyl or -alkatoi- enyl, especially C 16 -Alkyl or C 16 -alkatrienyl, each of the above mentioned groups may optionally be interrupted by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups or may be substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles; In addition, R 13 is chlorine).

[0017] One advantage of antioxidants such as vitamin E based on the chromanol structure and its derivatives according to the present invention is that they do not decompose to form Arvin substances.

[0018] For simplicity, in this document these chromanols will be referred to as stabilizers.

[0019] In this formula, C1-C4-alkyl, optionally interrupted by one or more oxygen atoms and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups, or substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles, is, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, benzyl, 1-phenylethyl, 2-phenylethyl, α,α-dimethyl. benzyl, benzhydryl, p-tolylmethyl, 1-(p-butylphenyl)ethyl, p-chlorobenzyl, 2,4-dichlorobenzyl, p-methoxybenzyl, m-ethoxybenzyl, 2-cyanoethyl, 2-cyanopropyl, 2-methoxycarbonylethyl, 2-ethoxycarbonylethyl, 2-butoxycarbonylpropyl, 1,2-di(methoxycarbonyl)ethyl, 2-methoxyethyl, 2-ethoxyethyl, 2-butoxyethyl, diethoxy dimethyl, diethoxyethyl, 1,3-dioxolan-2-yl, 1,3-dioxan-2-yl, 2-methyl-1,3-dioxolan-2-yl, 4-methyl-1,3-dioxolan-2-yl, 2-isopropoxyethyl, 2-butoxypropyl, 2-octyloxyethyl, chloromethyl, 2-chloroethyl, trichloromethyl, trifluoromethyl, 1,1-dimethyl-2-chloroethyl, 2-methoxyisopropyl, 2-ethoxyethyl, butylthiomethyl, 2-dodecylthioethyl, 2 -phenylthioethyl, 2,2,2-trifluoroethyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 4-hydroxybutyl, 2-aminoethyl, 2-aminopropyl, 3-aminopropyl, 4-aminobutyl, 2-methylaminoethyl, 2-methylaminopropyl, 3-methylaminopropyl, 4-methylaminobutyl, 2-dimethylaminoethyl, 2-dimethylaminopropyl, 3-dimethylaminopropyl, 4-dimethylaminobutyl, 2-hydroxy-2,2-dimethylethyl, 2-phenoxyethyl, 2-phenoxypropyl, 3-phenoxypropyl, 4-phenoxybutyl, 2-methoxyethyl, 2-methoxypropyl, 3-methoxypropyl, 4-methoxybutyl, 2-ethoxyethyl, 2-ethoxypropyl, 3-ethoxypropyl or 4-ethoxybutyl, C1~C 20 -alkyl is methyl, ethyl, iso-propyl, n-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-decyl, 2-propylheptyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl or n-eicosyl; C6-C optionally interrupted by one or more oxygen atoms and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups, or substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles. 12 -aryl is, for example, phenyl, tolyl, xylyl, α-naphthyl, β-naphthyl, 4-diphenyl, chlorophenyl, dichlorophenyl, trichlorophenyl, difluorophenyl, methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl, diethylphenyl, isopropylphenyl, tert-butylphenyl, dodecylphenyl, methoxyphenyl, dimethoxyphenyl, ethoxyphenyl, hexyloxyphenyl, methylnaphthyl, isopropylnaphthyl, chloronaphthyl, ethoxynaphthyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- or 4-nitrophenyl, 2,4- or 2,6-dinitrophenyl, 4-dimethylaminophenyl, 4-acetylphenyl, methoxyethylphenyl or ethoxymethylphenyl.

[0020] R 5 , R 6 , R 7 , R 8 , R 9 , R10 , R 11 , R 12 , R 13 and R 14 are each independently hydrogen or C1-C4 alkyl, more preferably hydrogen or methyl.

[0021] R 5 is preferably hydrogen, C1-C4-alkyl or C1-C4-alkylcarbonyl, more preferably hydrogen or C1-C4-alkyl, most preferably hydrogen, methyl or acetyl, especially hydrogen.

[0022] In particular, R 5 and R 9 ~R 12 are hydrogen, and R 6 , R 7 and R 8 are each independently hydrogen or methyl; R 13 and R 14 are each methyl.

[0023] R 5 and R 9 ~R 12 are, inter alia, hydrogen, R 6 , R 7 and R 8 are, inter alia, methyl, R 13 and R 14 In particular, each is methyl.

[0024] Preferred 6-chromanol derivatives of formula (I) are 2,2,5,7,8-pentamethyl-6-chromanol, 2,2,5,7-tetramethyl-6-chromanol, 2,2,5,8-tetramethyl-6-chromanol, 2,2,7,8-tetramethyl-6-chromanol, 2,2,5-trimethyl-6-chromanol, 2,2,7-trimethyl-6-chromanol and 2,2,8-trimethyl-6-chromanol, particularly preferred are 2,2,5,7,8-pentamethyl-6-chromanol, 2,2,5,7-tetramethyl-6-chromanol, 2,2,5,8-tetramethyl-6-chromanol and 2,2,7,8-tetramethyl-6-chromanol, very particularly preferred is 2,2,5,7,8-pentamethyl-6-chromanol.

[0025] In one embodiment, according to the invention, the chromanol is preferably a tocopherol, more preferably α-, β-, γ- or δ-tocopherol, even more preferably α-, γ- or δ-tocopherol, especially α- or γ-tocopherol.

[0026] These tocopherols are also referred to as E306, E307, E308 and E309 according to the European food additive numbering system. α-Tocopherol is also referred to as Vitamin E, which may be of natural or synthetic origin.

[0027] In one embodiment of the present invention, the stabilizer preferably consists of α-tocopherol.

[0028] In another embodiment of the invention, the stabilizer comprises, and preferably consists of, gamma-tocopherol.

[0029] In another embodiment of the invention, the stabilizer comprises, and preferably consists of, synthetic or preferably natural vitamin E. Such vitamin E may, in addition to one or more α-, β-, γ- or δ-tocopherols as mentioned above, further comprise one or more α-, β-, γ- or δ-tocotrienols.

[0030] The tocopherols can be used alone or in mixtures, and in enantiomerically pure or enantiomerically enriched form, or as racemic mixtures of enantiomers.

[0031] For purposes of clarification, tocopherols and tocotrienols are compounds of formula (I) shown below: α-Tocopherol: R 5 =H, R 6 = methyl, R 7 = methyl, R 8 = methyl, R 9 ~R 12 =H, R 13 = methyl, R 14 =(4R,8R)-4,8,12-trimethyltridecyl, where C2 is in the (R)-configuration. β-Tocopherol: R 5 =H, R 6 = methyl, R 7 =H, R 8 = methyl, R 9 ~R 12 =H, R 13 = methyl, R 14 =(4R,8R)-4,8,12-trimethyltridecyl, where C2 is in the (R)-configuration. γ-Tocopherol: R 5 =H, R 6 =H, R 7 = methyl, R 8 = methyl, R 9 ~R 12 =H, R 13 = methyl, R 14 =(4R,8R)-4,8,12-trimethyltridecyl, where C2 is in the (R)-configuration. δ-tocopherol: R 5 =H, R 6=H, R 7 =H, R 8 = methyl, R 9 ~R 12 =H, R 13 = methyl, R 14 =(4R,8R)-4,8,12-trimethyltridecyl, where C2 is in the (R)-configuration. α-Tocotrienol: R 5 =H, R 6 = methyl, R 7 = methyl, R 8 = methyl, R 9 ~R 12 =H, R 13 = methyl, R 14 = 4,8,12-trimethyltridecetri(3,7,11)enyl, where C2 is in the (R)-configuration. β-Tocotrienol: R 5 =H, R 6 = methyl, R 7 =H, R 8 = methyl, R 9 ~R 12 =H, R 13 = methyl, R 14 = 4,8,12-trimethyltridecetri(3,7,11)enyl, where C2 is in the (R)-configuration. γ-Tocotrienol: R 5 =H, R 6 =H, R 7 = methyl, R 8 = methyl, R 9 ~R 12 =H, R 13 = methyl, R 14 = 4,8,12-trimethyltridecetri(3,7,11)enyl, where C2 is in the (R)-configuration. δ-Tocotrienol: R 5 =H, R 6 =H, R 7 =H, R 8 = methyl, R 9 ~R 12 =H, R 13 = methyl, R 14 = 4,8,12-trimethyltridecetri(3,7,11)enyl, where C2 is in the (R)-configuration.

[0032] This structure is well known in the chemical literature.

[0033] Another object of the invention is a polyisobutene as a whole, preferably a high molecular weight polyisobutene, which comprises at least one stabilizer according to the invention.

[0034] Polyisobutene The present invention relates to the stabilization of high molecular weight polyisobutene. In this specification, high molecular weight polyisobutene means one having a viscosity average molecular weight Mv of 20,000 to 10,000,000 that can be obtained by polymerizing isobutene or an isobutene-containing monomer mixture.

[0035] The viscosity average molecular weight Mv is calculated from the Staudinger index J0 as shown below: Mv = (J0 × 100 / 3.06) 1 / 0.65 It is calculated as follows: Or the number average molecular weight Mn is: Mn = (J0 × 1000 / 2.27) 1 / 0.94 It is calculated as follows.

[0036] Staudinger index J0 [cm 3 / g] is calculated from the flow time of capillary tube I of the Ubbelohde viscometer at 20°C according to the Schulz-Blaschke equation: J0=η sp / (c×(1+0.31η sp ))[cm 3 / g] It is calculated using Here, the specific viscosity η sp is η sp = (t / t0)-1, During the ceremony, t = solution flow time (after Hagenbach-Couette correction) t0 = solvent flow time (after Hagenbach-Couette correction) c=solution concentration (g / cm 3 (units).

[0037] In the context of the present invention, for simplicity, high molecular weight polyisobutenes according to this molecular weight will be referred to as polyisobutenes.

[0038] Suitable isobutene sources for preparing isobutene polymers or for polymerizing isobutene-containing monomer mixtures are C4 fractions, more particularly pure isobutene, generally containing less than 0.5% by volume of residual impurities such as 1-butene, 2-butene, butane, water and / or C1-C4-alkanols.

[0039] The source of C4 compounds is usually selected from the group consisting of: (a) A C4 compound material having an isobutene content adjusted to 50-75% by weight, obtained by adding high-purity isobutene having an isobutene content of 90-100% by weight to C4 raffinate-1, which is the residue after extracting 1,3-butadiene from C4 compounds obtained in a naphtha cracking process; (b) A C4 compound material having an isobutene content adjusted to 50-75% by weight, obtained by adding a high isobutene content mixture having an isobutene content of 80-97% by weight, which is produced in an olefin conversion unit (OCU) process for producing propylene by metathesis of ethylene and 2-butene, to C4 raffinate-1, which is the residue after extracting 1,3-butadiene from C4 compounds obtained in a naphtha cracking process; (c) A C4 compound material having an isobutene content adjusted to 50-75% by weight, obtained by adding high-purity isobutene having an isobutene content of 90-100% by weight to butane-butene oil (BB oil) obtained from a crude oil refining process; (d) A C4 compound material having an isobutene content adjusted to 50-75% by weight, obtained by adding a high isobutene content mixture having an isobutene content of 80-97% by weight, which is produced in an olefin conversion unit (OCU) process for producing propylene by metathesis of ethylene and 2-butene, to butane-butene oil (BB oil) obtained from a crude oil refining process; (e) a C4 compound material having an isobutene content adjusted to 50 to 75% by weight, obtained by adding a dilution solvent to high-purity isobutene having an isobutene content of 90 to 100% by weight; (f) a C4 compound material obtained by adding a dilution solvent to a high isobutene content mixture having an isobutene content of 80 to 97% by weight produced in an olefin conversion unit (OCU) process for producing propylene by metathesis of ethylene and 2-butene, and having an isobutene content adjusted to 50 to 75% by weight; (g) A C4 compound material having an isobutene content adjusted to 50 to 75% by weight, obtained by adding high-purity isobutene having an isobutene content of 90 to 100% by weight to a mixture produced by a dehydrogenation reaction for converting isobutane to isobutene; and (h) A C4 compound material having an isobutene content adjusted to 50-75% by weight, obtained by adding a high isobutene content mixture having an isobutene content of 80-97% by weight, which is produced in an olefin conversion unit (OCU) process for producing propylene by metathesis of ethylene and 2-butene, to a mixture produced by a dehydrogenation reaction for converting isobutane to isobutene.

[0040] Preferably, isobutene-containing technical C4 hydrocarbon streams are used, such as C4 raffinates, C4 fractions obtained from the dehydrogenation of isobutane, C4 fractions obtained from steam crackers and from FCC catalytic crackers (fluid catalytic cracking), provided that the 1,3-butadiene present therein has been substantially removed. Suitable C4 hydrocarbon streams generally contain less than 500 ppm, preferably less than 200 ppm, of butadiene.

[0041] In the present specification, isobutene obtained from such industrial C4-hydrocarbon streams is substantially selectively polymerized to the desired isobutene homopolymers without significant incorporation of other C4-monomers in the polymer chain. Typically, the isobutene concentration of the above-mentioned industrial C4-hydrocarbon streams is in the range of 40-60% by weight. However, polyisobutenes according to the invention can in principle also be obtained from isobutene-containing C4-hydrocarbon streams having a lower isobutene content, for example only 10-20% by weight. Isobutene-containing monomer mixtures may contain small amounts of contaminants such as water, carboxylic acids or mineral acids, which do not cause a significant decrease in the yield or selectivity. In order to avoid the accumulation of these impurities, it is suitable to remove these harmful substances from the isobutene-containing monomer mixture by adsorption on solid adsorbents, such as activated carbon, molecular sieves or ion exchangers.

[0042] Efficient preparation methods that meet the requirements for obtaining isobutene homopolymers with relatively high molecular weights generally require very low polymerization temperatures. A typical method for preparing such isobutene homopolymers is the so-called "BASF belt process", which consists in passing liquid isobutene together with boron trifluoride as polymerization catalyst and a large excess of liquid ethene over an endless steel belt with a width of 50-60 cm, arranged in a trough shape by suitable guiding, present in an airtight cylindrical casing. The temperature is fixed at -104°C by continuously evaporating the ethene under standard pressure. As a result, the heat of polymerization is completely removed. The evaporated ethene is recovered, purified and reused. The resulting polyisobutene is degassed to remove the still adhering ethene and residual monomers. By carrying out the polymerization in this manner, the isobutene is practically completely converted.

[0043] In the BASF belt process, the polymerization temperature can be easily and reliably controlled by evaporative cooling, i.e. by creating large steam passages. However, a disadvantage of the BASF belt process is that the reactants are not mixed well because they are not moved on the belt, and therefore the surface of the product is not exchanged, which can have a negative effect on the product properties. This can lead, for example, to an inhomogeneous distribution of the ethene used for evaporative cooling, with the attendant local overheating of the reaction mixture immediately after the ethene has evaporated. Furthermore, bumping of the reaction mixture can occur when an overheated area and a cold area rich in ethene come into contact with each other, fouling the reactor walls with the polymerizing reaction mixture. Another disadvantage is that the heat distribution is inhomogeneous, leading to an undesirable broadening of the molecular weight distribution of the polymer, which leads to unfavourable product properties. A further disadvantage of the BASF belt process is that the steel belt is subject to wear and therefore high maintenance costs. A further disadvantage of the BASF belt process is that the reactor walls and the product inlet of the downstream workup section (usually an extruder) are not cooled; polyisobutene becomes very sticky above its glass transition temperature, leading to significant sticking of the polymer to the reactor walls and increased cleaning efforts. A further disadvantage of the BASF belt process is that the boron trifluoride present in the recycled ethene stream becomes very corrosive at relatively high temperatures, requiring high maintenance of the ethene workup circuit.

[0044] Another commonly used method for preparing isobutene homopolymers with relatively high molecular weights is the "Exxon slurry process", in which the polymerization is carried out in a stirred tank at -80 to -85°C equipped with a cooling jacket filled with liquid ethene. The catalyst system used is anhydrous aluminum chloride in methyl chloride. By very vigorous stirring, the polymer is obtained as a slurry of small droplets, which flows through an intermediate tank into a degassing tank. Here, the slurry is treated with steam and hot water so that it can be freed of volatile constituents (essentially unconverted isobutene and methyl chloride) and sent for reprocessing. The remaining liquid slurry of polymer particles is worked up by removing residual catalyst, residual solvent and residual isobutene.

[0045] In the Exxon slurry process, although there is vigorous mixing and product surface turnover, it is difficult to control the polymerization temperature by jacket cooling alone. It is impossible to completely prevent polymer from adhering to the walls of the reactor and equipment, so the reactor and equipment must be cleaned from time to time.

[0046] Details of the BASF belt process and the Exxon slurry process are found in Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, Vol. A21, pp. 555-561, under "Polyisobutylenes."

[0047] Further polymerization processes are disclosed in WO 15 / 095960 and WO 16 / 000074, where the polymerization is carried out in an organic solvent and polyisobutene particles are obtained as an aqueous slurry.

[0048] Further preferred methods for the polymerization of polyisobutene are those described in WO 2017 / 216022 A1, preferably from page 2, line 22 to page 5, line 42.

[0049] Generally, the amount of the stabilizer is more than 100 to 5000 ppm by weight, preferably 110 to 3000 ppm by weight, more preferably 125 to 2000, even more preferably 150 to 1000 ppm by weight, and particularly preferably 200 to 500 ppm by weight, relative to the weight of polyisobutene, to be effective in the method according to the present invention, while at the same time the molecular weight is basically maintained.

[0050] The stabilizer can be added to the polyisobutene in solid or molten form or as a solution in at least one solvent, which is preferably removed when incorporated into the polyisobutene. Preferably, the stabilizer is added as a solid or melt, more preferably in liquid or molten form.

[0051] Preferably, the stabilizer is incorporated into the polyisobutene by means of shear forces, utilizing at least one kneader or extruder, more preferably at least one extruder.

[0052] The extruder or extruders are preferably heated to a temperature above 80° C., especially above 100° C. The temperature should not exceed a temperature of 160° C., and is preferably below 150° C.

[0053] To incorporate the stabilizer into the polyisobutene, it is possible in principle to use all conventional single-screw, twin-screw and multi-screw extruders. In the case of twin-screw and multi-screw extruders, the shafts can be operated in a co-rotating or counter-rotating manner. The shafts of single-screw and multi-screw extruders are usually equipped with kneading and / or conveying elements. These devices are usually self-cleaning. The shaft speed is generally in the range of 10 to 500, in particular 15 to 350 revolutions per minute.

[0054] The incorporation of the stabilizer into the polyisobutene can be combined with a process step of degassing the product of volatile constituents such as residual monomers and solvents. The degassing and purification of the product can be promoted by applying a vacuum; more specifically, for this purpose, pressures of less than 700 mbar, in particular less than 200 mbar, in particular less than 100 mbar are used.

[0055] In certain designs, the shafts can be configured as screw shafts whose grooves intermesh, and the inside diameter of the shafts is preferably constant throughout its length. The preferred materials of construction for the extruders described herein are steel or stainless steel. It may also be advantageous to introduce an inert gas, such as nitrogen, into one or more zones of the extruder to facilitate the degassing operation.

[0056] Extruders are usually used to incorporate other components required for the desired use of polyisobutene or to mix it with other polymers or components. This method has the disadvantage that polyisobutene can decompose due to shear stress and / or thermal strain. As a result, the average molecular weight of the product is reduced or light volatile by-products are produced or colored due to the decomposition of the polymer chains.

[0057] An advantage of the present invention is that the stabilizers described above are effective in reducing or even preventing such degradation during compounding or extrusion processes.

[0058] Another object of the present invention is therefore a process for treating polyisobutene in at least one kneader or extruder at a temperature of at least 80, preferably at least 100, more preferably at least 120° C. and / or at a specific shear energy of at least 0.08 kWh / kg polyisobutene, preferably at least 0.10, more preferably at least 0.15, even more preferably at least 0.15, in particular at least 0.20 kWh / kg polyisobutene, in which the polyisobutene comprises more than 100 to 5000 ppm of at least one stabilizer according to the invention or at least one stabilizer is incorporated into the polyisobutene during the process. Preferred amounts of stabilizer are 110 to 3000 ppm by weight, more preferably 125 to 2000, even more preferably 150 to 1000 ppm by weight, in particular 200 to 500 ppm by weight.

[0059] The upper limit of the temperature of the at least one kneader or extruder is 160°C, preferably below 150°C, more preferably below 140°C.

[0060] The residence time in the at least one kneader or extruder at a given temperature is at most 2 hours, preferably at most 1.5 hours, more preferably at most 1.25 hours, especially at most 1 hour.

[0061] The at least one stabilizer can be introduced into the polyisobutene in one or more portions, preferably in one portion.

[0062] The at least one stabilizer may be introduced into the polyisobutene prior to the addition of other components required for the application or together with such components.

[0063] The decrease in the average molecular weight (measured in terms of the Staudinger index J0) under these conditions is at most 5%, preferably at most 4%, more preferably at most 3%, even more preferably at most 2.5%, and especially at most 2%.

[0064] The stabilized polyisobutene products according to the present invention have been found to be particularly useful in the preparation of compounds for use in certain applications.

[0065] Such applications include sealants, adhesives, coatings and roofing materials as well as white and black filled sheeting.

[0066] Thus, the present invention also includes the use of polyisobutylenes according to the invention in or as sealants, adhesives, coatings and roofing materials, as well as sheeting filled with white and black fillers.

[0067] The polymer products are also useful in tire sidewall and tread compounds, where the polyisobutylene properties impart good ozone resistance, crack and cut growth properties and appearance to the sidewall.

[0068] Particularly preferably, the stabilized polyisobutene according to the invention is used as a chewing gum or as an ingredient of a chewing gum, since the stabilizer is non-toxic and approved as a food ingredient. In a preferred embodiment, the chromanol of formula (I) is used as an ingredient of a chewing gum, more preferably, the stabilizer comprises, preferably consists of, one or more of the above-mentioned α-, β-, γ- or δ-tocopherols and / or one or more of the α-, β-, γ- or δ-tocotrienols. Among these compounds, α- and γ-tocopherols are preferred.

[0069] In a particularly preferred embodiment, the stabilizer comprises, and preferably consists of, synthetic or preferably natural vitamin E.

[0070] Another object of the invention is a chewing gum comprising polyisobutene comprising at least one stabilizer, the at least one stabilizer comprising, preferably consisting of, one or more α-, β-, γ- or δ-tocopherols and / or one or more α-, β-, γ- or δ-tocotrienols, preferably one or more α- and γ-tocopherols, in particular synthetic or preferably natural vitamin E.

[0071] In a preferred embodiment, polyisobutenes for use in chewing gum have a free isobutene monomer content of less than 30 ppm by weight, preferably less than 25 ppm by weight, more preferably less than 20 ppm by weight, even more preferably less than 15 ppm by weight, especially less than 10 ppm by weight.

[0072] In another embodiment, the stabilized polyisobutene according to the invention is used as or as a component of architectural sealants, plumbing and / or roofing materials, since the stabilizers are non-toxic, approved as food ingredients and do not form so-called Arvin substances in drinking water or storm water or wastewater, which are derived from the reaction and decomposition of phenolic antioxidants during polymer processing. In a preferred embodiment, the chromanols of formula (I) are used as or as a component of architectural sealants, plumbing and / or roofing materials, more preferably the stabilizers comprise, preferably consist of, one or more of the above-mentioned α-, β-, γ- or δ-tocopherols and / or one or more of the α-, β-, γ- or δ-tocotrienols. Among these compounds, α- and γ-tocopherols are preferred.

[0073] In a particularly preferred embodiment, the stabilizer comprises, and preferably consists of, synthetic or preferably natural vitamin E.

[0074] Another object of the invention is a sealant comprising polyisobutene comprising at least one stabilizer, the at least one stabilizer comprising, preferably consisting of, one or more α-, β-, γ- or δ-tocopherols and / or one or more α-, β-, γ- or δ-tocotrienols, preferably one or more α- and γ-tocopherols, in particular synthetic or preferably natural vitamin E.

[0075] The present invention will be further described in the following non-limiting examples. EXAMPLES

[0076] analysis Polyisobutene sample in 2,2,4-trimethylpentane solution (concentration 0.002-0.01 g / cm 3 The Staudinger index J0 of the viscosity modulus was determined at 20° C. in accordance with DIN 51562 using an Ubbelohde capillary microviscometer (AVS PRO III, supplied by Schott Geraete GmbH), Capillary Ic, No. 53713.

[0077] component Polyisobutene 1 (PIB1): commercially available as Oppanol N50 from BASF SE, Ludwigshafen, has a viscosity average molecular weight (Mv) of 425,000 g / mol and a Staudinger index J0 = 128-150 cm 3 / g of high molecular weight polyisobutene. Polyisobutene 2 (PIB2): commercially available as Oppanol B15 from BASF SE, Ludwigshafen, has a viscosity average molecular weight (Mv) of 85,000 g / mol and a Staudinger index J0 of 45.9-51.6 cm 3 / g of medium molecular weight polyisobutene. Stabilizer 1: 2,6-di-tert-butyl-4-methylphenol, BHT (for comparison) Stabilizer 2: α-tocopherol (European food additive E307)

[0078] Example 1 - Stability in the Extrusion Process The initial value of J0 is 133.1 cm 3 Polyisobutene 1, having a molecular weight of 1000 g / g, was extruded in a laboratory extruder (ThermoFischer Haake Rheomix OS, twin-screw, volume 120 cm 3 ) at the temperatures, rotational speeds and residence times shown in the table.

[0079] After extrusion of the control and stabilized samples, the Staudinger index J0 [cm 3 / g] was determined and listed in the table.

[0080] The Staudinger index value J0 of the initial sample is 133.1 cm 3 / g, and a lower J0 value after kneading means that the polymer chains have been broken due to the harsh process conditions.

[0081] [Table 1]

[0082] Example 2 - Stability of high molecular weight polyisobutene in the extrusion process and depolymerization to isobutene The initial value of J0 is 141.8 cm 3 Polyisobutene 1 having a molecular weight of 1000 g / g was extruded in a laboratory extruder (ThermoFischer Haake Rheomix OS, twin-screw, volume 120 cm 3 ) at the temperatures, rotational speeds and residence times shown in the table.

[0083] After extrusion of the control and stabilized samples, the Staudinger index J0 [cm 3 / g] was determined and listed in the table.

[0084] The Staudinger index value J0 of the initial sample is 141.1 cm 3 / g, and a lower J0 value after kneading means that the polymer chains have been broken due to the harsh process conditions.

[0085] [Table 2]

[0086] Example 3 - Stability of Medium Molecular Weight Polyisobutene in an Extrusion Process and Depolymerization to Isobutene The initial value of J0 is 47.9 cm 3 Polyisobutene 2, 0.01 g / g, was extruded in a laboratory extruder (ThermoFischer Haake Rheomix OS, twin-screw, 120 cm volume). 3 ) at the temperatures, rotational speeds and residence times shown in the table.

[0087] After extrusion of the control and stabilized samples, the Staudinger index J0 [cm 3 / g] was determined and listed in the table.

[0088] The Staudinger index value J0 of the initial sample is 47.9 cm 3 / g, and a lower J0 value after kneading means that the polymer chains have been broken due to the harsh process conditions.

[0089] [Table 3]

[0090] Example 4 - Oxidation Induction Time The Oxidative Induction Time or OIT is a standardized test performed by Differential Scanning Calorimetry (DSC) to measure the degree of thermal stabilization of a test material. It measures the time from melting to the onset of decomposition under isothermal conditions. A nitrogen atmosphere is used up to the melting point, then changed to an oxygen atmosphere. The lower this value, the faster the decomposition.

[0091] The initial value of J0 is 133.1 cm 3 Polyisobutene 1, having a molecular weight of 1000 g / g, was extruded in a laboratory extruder (ThermoFischer Haake Rheomix OS, twin-screw, volume 120 cm 3 ) at the temperature, rotation speed and residence time shown in the table, and then the OIT was measured.

[0092]

Table 4

Claims

1. 1. A process for treating polyisobutene in at least one kneader or extruder at a temperature of at least 80 to 160° C. for a time of at most 2 hours and / or with a specific shear energy of at least 0.08 kWh / kg polyisobutene, preferably at least 0.10, more preferably at least 0.15, even more preferably at least 0.15, especially at least 0.20 kWh / kg polyisobutene, wherein the polyisobutene contains more than 100 to 5000 ppm by weight of at least one chromanol or the at least one chromanol is incorporated into the polyisobutene during the treatment and the average molecular weight (Staudinger index J ０ wherein the at least one chromanol has the formula: 【Chemistry 1】 (In the formula, R ５ , R ６ , R ７ , R ８ , R ９ , R １０ , R １１ , R １２ , R １３ and R １４ are each independently hydrogen, C １ ~C ４ -Alkyl, C １ ~C ４ -Alkyloxy or C ６ ~C １２ -aryl, In addition to this, R ５ is C １ ~C ４ - alkylcarbonyl, C １ ~C ４ - alkyloxycarbonyl, C ６ ~C １２ -arylcarbonyl or C ６ ~C １２ -aryloxycarbonyl, In addition to this, R １３ and R １４ is C ５ ~C ３０ -Alkyl, C ５ ~C ３０ -alkenyl, C ５ ~C ３０ -alkadienyl or C ５ ~C ３０ - alkatrienyl, preferably C ６ ~C ２０ -alkyl or -alkatrienyi, more preferably C １１ ~C １６ -alkyl or -alkatrienyl, especially C １６ -Alkyl or C １６ - may be alkatrienyl, each of the above-mentioned groups may optionally be interrupted by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups, or may be substituted with functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and / or heterocycles; In addition to this, R １３ is chlorine) The method is represented by

2. 2. The process according to claim 1, wherein the at least one chromanol of formula (I) is selected from the group consisting of 2,2,5,7,8-pentamethyl-6-chromanol, 2,2,5,7-tetramethyl-6-chromanol, 2,2,5,8-tetramethyl-6-chromanol, 2,2,7,8-tetramethyl-6-chromanol, 2,2,5-trimethyl-6-chromanol, 2,2,7-trimethyl-6-chromanol and 2,2,8-trimethyl-6-chromanol, particularly preferably 2,2,5,7,8-pentamethyl-6-chromanol, 2,2,5,7-tetramethyl-6-chromanol, 2,2,5,8-tetramethyl-6-chromanol and 2,2,7,8-tetramethyl-6-chromanol, very particularly preferably 2,2,5,7,8-pentamethyl-6-chromanol.

3. 2. The method of claim 1, wherein the at least one chromanol comprises at least one compound selected from the group consisting of α-, β-, γ-, or δ-tocopherol or α-, β-, γ-, and δ-tocotrienol.

4. 2. The method of claim 1, wherein the at least one chromanol comprises α- or γ-tocopherol.

5. 2. The method of claim 1, wherein the at least one chromanol is vitamin E of natural or synthetic origin.

6. 2. The method of claim 1, wherein the at least one chromanol is a tocopherol, which may be used alone or in mixtures, in enantiomerically pure or enriched form, or as a racemic mixture of the enantiomers.

7. 2. Polyisobutene having a viscosity-average molecular weight Mv of 20,000 to 10,000,000, a content of free isobutene monomer of 30 ppm by weight, and comprising more than 100 to 5,000 ppm by weight of at least one chromanol according to claim 1.

8. 8. Use of the polyisobutylene of claim 7 in or as a sealant, adhesive, coating, roofing material, and sheet material filled with white and black fillers.

9. 8. Use of the polyisobutylene of claim 7 as a chewing gum or as an ingredient of a chewing gum.

10. 8. Use of the polyisobutylene according to claim 7 in a bandage or adhesive for a bandage.

11. 10. Use according to claim 9, wherein the polyisobutene has a free isobutene monomer content of less than 25 ppm by weight, more preferably less than 20 ppm by weight, even more preferably less than 15 ppm by weight, especially less than 10 ppm by weight.

12. 12. Use according to any one of claims 8 to 11, wherein the at least one chromanol comprises, preferably consists of, one or more α-, β-, γ- or δ-tocopherols and / or one or more α-, β-, γ- or δ-tocotrienols, preferably one or more α- and γ-tocopherols, especially synthetic or preferably natural vitamin E.

13. 1. Chewing gum comprising polyisobutene having a content of free isobutene monomer of less than 30 ppm by weight and comprising at least one chromanol, said at least one chromanol comprising, preferably consisting of, one or more α-, β-, γ- or δ-tocopherols and / or one or more α-, β-, γ- or δ-tocotrienols, preferably one or more α- and γ-tocopherols, especially synthetic or preferably natural vitamin E.

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