Use of K-containing compounds in processes for halogenating unsaturated isoolefin copolymers + Halogen recovery from oxidizing agents

Abstract

A process for producing a halogenated isoolefin copolymer includes contacting an unsaturated isoolefin copolymer binder with an aqueous solution of a halogenating agent and a potassium salt-based oxidizing agent under halogenating conditions to form a two-phase reaction medium comprising an organic phase and an aqueous phase, the oxidizing agent being capable of converting hydrogen halide to free halogen, the binder comprising an unsaturated isoolefin copolymer dissolved in an organic solvent. The process provides improved halogen recovery, is less sensitive to the presence of water, and uses a more stable and less environmentally damaging oxidizing agent.

Description

TECHNICAL FIELD

[0001] The present application relates to a process for halogenating an unsaturated isoolefin copolymer. BACKGROUND

[0002] In the standard process for brominating butyl rubber to form brominated butyl rubber, molecular bromine (Br2) is used as the brominating agent. This process results in the release of hydrogen bromide (HBr) as a byproduct, which does not further brominate the butyl rubber polymer under normal conditions. Therefore, the theoretical maximum fraction of bromine that can be introduced into the reaction mixture present in the butyl rubber polymer is 50%. However, in practice, this fraction is typically less than 45%, and less than 35% in laboratory and production plant settings.

[0003] Known processes for enhancing bromine utilization during butyl rubber bromination (WO 2020 / 124222, US2014 / 0309362, US 3,018,275, US 5,681,901) involve the application of at least 0.5 mol of a water-soluble oxidizing agent, such as an organic peracid or hydrogen peroxide, per mole of brominating agent, which re-oxidizes the hydrogen bromide back to elemental bromine. The oxidizing agent can be in aqueous solution or an aqueous emulsion in an organic solvent. Since the oxidizing agent is only soluble in water, the reaction rate is controlled by the rate at which the reactants can exchange between the organic and aqueous phases, thus requiring longer reaction times.

[0004] Furthermore, processes using hydrogen peroxide require very low concentrations of water to be present in the bromination medium. The benefits observed from using hydrogen peroxide in the bromination medium are significantly reduced with water concentrations greater than 1 wt%, thus presenting significant challenges and costs in industry, as additional equipment and energy can be required to reduce the water content in the bromination medium from 10-20 wt% to less than 1 wt%.

[0005] Furthermore, some processes involve post-halogenation recycling by neutralizing the HBr to produce sodium bromide (NaBr), washing the NaBr from the halogenated butyl rubber into the aqueous stream, and converting the NaBr to Br2 using Cl2 gas (e.g., by the blowout process). This ex situ recycling process is limited by the efficiency of NaBr extraction into the aqueous phase and dilution of the NaBr in the aqueous phase. Furthermore, performing this ex situ process is cost-inefficient and energy-intensive.

[0006] There remains a need for a cost-effective, efficient process for improving halogen utilization during halogenation of isoolefin copolymers, such as butyl rubber, particularly in the presence of significant amounts of water. SUMMARY

[0007] In one aspect, a process for producing a halogenated isoolefin copolymer is provided, the process comprising contacting, under halogenating conditions, an unsaturated isoolefin copolymer binder with an aqueous solution of a halogenating agent and a potassium salt-based oxidant capable of converting hydrogen halide to free halogen to form a two-phase reaction medium comprising an organic phase and an aqueous phase, the binder comprising an unsaturated isoolefin copolymer dissolved in an organic solvent.

[0008] The process can further comprise recovering a halogenated isoolefin copolymer containing at least 0.05 mol% chemically bound halogen.

[0009] By oxidizing the hydrogen halide (HX) formed during halogenation of the unsaturated isoolefin copolymer back to molecular halogen (X2), the halogenation process of the present invention advantageously results in improved halogen utilization. The process has lower sensitivity to the presence of water in the binder compared to similar processes (e.g., processes utilizing peracids or hydrogen peroxide), provides equally good or better bromine recovery while using less oxidant, and uses an oxidant that is more water and temperature stable and easier to handle than the oxidants previously used in similar processes. The process does not fundamentally affect the microstructure and molecular weight of the resulting halogenated isoolefin copolymer, and the ability to achieve the same or better halogenation efficiency using less oxidant further advantageously preserves the microstructure and molecular weight of the halogenated isoolefin copolymer.

[0010] Further features will be described or will become apparent in the course of the following detailed description. It should be understood that each feature described herein can be utilized with any one or more of the other described features, and that every combination of features described herein is not necessarily limited to only the combination specifically described, but is also intended to encompass any and all possible combinations of the features. BRIEF DESCRIPTION OF DRAWINGS

[0011] In order that the application can be more fully understood, preferred embodiments will now be described, by way of example, with reference to the accompanying drawings in which:

[0012] Figure 1 Is a plot of active oxygen (wt%) in a potassium peroxymonosulfate sample as a function of time (min) at 45°C for an aqueous solution of potassium peroxymonosulfate (0.1 g / mL).

[0013] Figure 2 Is a plot of functional Br (mol%) versus reaction time (min) for bromination of a butyl rubber binder comprising 20 wt% butyl rubber (IIR) and 5 wt% added water in the presence of: no oxidant and no phase transfer catalyst (triangles); 6.4 g potassium peroxymonosulfate oxidant (diamonds); and 6.4 g potassium peroxymonosulfate oxidant with 120 mg Lutensol XP-338 phase transfer catalyst (squares) at 45°C. TMPotassium peroxymonosulfate oxidant of TO5 phase transfer catalyst (squares).

[0014] Figure 3 Functional Br (mol%) versus reaction time (min) for bromination of butyl rubber binder containing 20 wt% butyl rubber (IIR), 5 wt% added water using 5 wt% added water (diamonds) and 15 wt% added water (squares) at 45 °C using the following: no oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (triangles); 3.2 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (squares); 6.4 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (triangles). 1 Part of the H NMR spectrum.

[0015] Figure 4A Functional Br (mol%) versus reaction time (min) for bromination of butyl rubber binder containing 20 wt% butyl rubber (IIR), 5 wt% added water using 5 wt% added water (diamonds) and 15 wt% added water (squares) at 45 °C using the following: no oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (triangles); 3.2 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (squares); 6.4 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (triangles). TM Plot of bromine atom efficiency (BAE) (%) versus added water concentration (wt%) for butyl rubber binder of TO5 phase transfer catalyst.

[0016] Figure 4B Functional Br (mol%) versus reaction time (min) for bromination of butyl rubber binder containing 20 wt% butyl rubber (IIR), 5 wt% added water using 5 wt% added water (diamonds) and 15 wt% added water (squares) at 45 °C using the following: no oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (triangles); 3.2 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (squares); 6.4 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (triangles). TM Plot of bromine atom efficiency (BAE) (%) versus added water concentration (wt%) for butyl rubber binder of TO5 phase transfer catalyst.

[0017] Figure 5A Functional Br (mol%) versus reaction time (min) for bromination of butyl rubber binder containing 20 wt% butyl rubber (IIR), 5 wt% added water using 5 wt% added water (diamonds) and 15 wt% added water (squares) at 45 °C using the following: no oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (triangles); 3.2 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (squares); 6.4 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (triangles). TM TO5 phase transfer catalyst (diamonds); 3.2 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (squares); 6.4 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (triangles). TM TO5 phase transfer catalyst (squares); 6.4 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (triangles). TM TO5 phase transfer catalyst (triangles).

[0018] Figure 5B Functional Br (mol%) versus reaction time (min) for bromination of butyl rubber binder containing 20 wt% butyl rubber (IIR), 5 wt% added water using 5 wt% added water (diamonds) and 15 wt% added water (squares) at 45 °C using the following: no oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (triangles); 3.2 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (squares); 6.4 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (triangles). TM TO5 phase transfer catalyst (squares); 6.4 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C16® phase transfer catalyst (triangles). TMTO5 phase transfer catalyst (triangle); 6.4 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C12® TM TO5 phase transfer catalyst (X); and 9.6 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C12® TM TO5 phase transfer catalyst (star).

[0019] Figure 5C is a plot of functional Br (mol%) versus reaction time (min) for bromination of a butyl rubber binder comprising 20 wt% butyl rubber (IIR), 15 wt% added water using the following at 45°C: no oxidant and 240 mg Lutensol XP C12® TM TO5 phase transfer catalyst (square); 1.6 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C12® TM TO5 phase transfer catalyst (X); 3.2 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C12® TM TO5 phase transfer catalyst (diamond); 6.4 g potassium peroxymonosulfate oxidant and 240 mg Lutensol XP C12® TM TO5 phase transfer catalyst (triangle).

[0020] Figure 6 is a plot of functional Br (mol%) versus reaction time (min) for bromination of a butyl rubber binder comprising 20 wt% butyl rubber (IIR), 15 wt% added water using the following at 45°C: no oxidant and 240 mg Lutensol XP C12® TM TO5 phase transfer catalyst for bromination of a butyl rubber binder comprising 20 wt% butyl rubber (IIR), 10-25 wt% added water versus concentration of butyl rubber (IIR) (wt%).

[0021] Figure 7 is a plot of functional Br (mol%) versus reaction time (min) for bromination of a butyl rubber binder comprising 20 wt% butyl rubber (IIR), 15 wt% added water using the following at 45°C: no oxidant and 240 mg Lutensol XP C12® TM TO5 phase transfer catalyst for bromination of a butyl rubber binder (diamond) showing the effect of adding oxidant to the binder as a solid after the addition of water and phase transfer catalyst but before the start of bromination versus reaction time (min).

[0022] Figure 8 is a plot of functional Br (mol%) versus reaction time (min) for bromination of a butyl rubber binder comprising 20 wt% butyl rubber (IIR), 15 wt% added water using the following at 45°C: no oxidant and 240 mg Lutensol XP C12® TMPlot of functional Br (mol%) versus reaction time (min) for bromination of a butyl rubber binder comprising 20 wt% butyl rubber (IIR), 5 wt% added water in the presence of TO5 (circle).

[0023] Figure 9 at 45 °C in 6.5 mL sodium hypochlorite (square) and 6.5 mL sodium hypochlorite and 240 mg Lutensol XP C 14 (triangle). TM Plot of functional Br (mol%) versus reaction time (min) for bromination of a butyl rubber binder comprising 20 wt% butyl rubber (IIR), 5 wt% added water in the presence of TO5 (circle).

[0024] Figure 10 at 45 °C in 6.5 mL sodium hypochlorite (square) and 6.5 mL sodium hypochlorite and 240 mg Lutensol XP C 14 (triangle). TM Plot of functional Br (mol%) versus reaction time (min) for bromination of a butyl rubber binder comprising 20 wt% butyl rubber (IIR), 5 wt% added water in the presence of TO5 (circle). DETAILED DESCRIPTION

[0025] The process includes polymerizing at least one isoolefin monomer and at least one copolymerizable unsaturated monomer in an organic diluent to produce a halogenatable isoolefin copolymer in an organic medium. The polymerization reaction is conducted in a polymerization reactor. Suitable polymerization reactors include flow-through polymerization reactors, plug flow reactors, moving belt or drum reactors, and the like. The process preferably includes slurry polymerization of the monomers.

[0026] The halogenatable isoolefin copolymer preferably includes repeating units derived from the at least one isoolefin monomer and repeating units derived from the at least one copolymerizable unsaturated monomer, and optionally repeating units derived from one or more other copolymerizable monomers. The halogenatable isoolefin copolymer preferably includes an unsaturated isoolefin copolymer.

[0027] Suitable isoolefin monomers include hydrocarbon monomers having from 4 to 16 carbon atoms. In one embodiment, the isoolefin monomer has from 4 to 7 carbon atoms. Examples of suitable isoolefins include isobutylene (iso-butylene), 2-methyl-1 -butene, 3-methyl-1 -butene, 2-methyl-2-butene, 4-methyl-1 -pentene, 4-methyl-1 -pentene, and mixtures thereof. The preferred isoolefin monomer is isobutylene (iso-butylene).

[0028] Suitable copolymerizable unsaturated monomers include multiolefins, p-methylstyrene, beta-pinene, or mixtures thereof. Multiolefin monomers include hydrocarbon monomers having from 4 to 14 carbon atoms. In some embodiments, the multiolefin monomer is a conjugated diene. Examples of suitable conjugated diene monomers include isoprene, butadiene, 2-methylbutadiene, 2,4-dimethylbutadiene, piperylene, 3-methyl-l,3-pentadiene, 2,4-hexadiene, 2-neopentylbutadiene, 2-methyl-l,5-hexadiene, 2,5-dimethyl-2,4-hexadiene, 2-methyl-l,4-pentadiene, 4-butyl-l,3-pentadiene, 2,3-dimethyl-l,3-pentadiene, 2,3-dibutyl-l,3-pentadiene, 2-ethyl-l,3-pentadiene, 2-ethyl-l,3-butadiene, 2-methyl-l,6-heptadiene, cyclopentadiene, methylcyclopentadiene, cyclohexadiene, l-ethenyl-cyclohexadiene, and mixtures thereof.

[0029] The halogenatable isoolefin copolymers can optionally include one or more additional copolymerizable monomers. Suitable additional copolymerizable monomers include, for example, styrenic monomers, such as alkyl-substituted vinyl aromatic copolymerizable monomers, including but not limited to C1-C4 alkyl-substituted styrenes. Specific examples of additional copolymerizable monomers include, for example, alpha-methylstyrene, p-methylstyrene, chlorostyrene, cyclopentadiene, and methylcyclopentadiene. Indene and other styrene derivatives can also be used. In one embodiment, the halogenatable isoolefin copolymer can comprise a random copolymer of isobutylene, isoprene, and p-methylstyrene.

[0030] In one embodiment, the halogenatable isoolefin copolymer can be formed by copolymerization of a monomer mixture. Preferably, the monomer mixture comprises from about 80 to 99.9 mol% of at least one isoolefin monomer and from about 0.1 to 20 mol% of at least one copolymerizable unsaturated monomer, based on the monomers in the monomer mixture. More preferably, the monomer mixture comprises from about 90 to 99.9 mol% of at least one isoolefin monomer and from about 0.1 to 10 mol% of at least one copolymerizable unsaturated monomer. In one embodiment, the monomer mixture comprises from about 92.5 to 97.5 mol% of at least one isoolefin monomer and from about 2.5 to 7.5 mol% of at least one copolymerizable unsaturated monomer. In another embodiment, the monomer mixture comprises from about 97.4 to 95 mol% of at least one isoolefin monomer and from about 2.6 to 5 mol% of at least one copolymerizable unsaturated monomer.

[0031] If the monomer mixture comprises an additional monomer copolymerizable with the isoolefin and / or the copolymerizable unsaturated monomer, the additional copolymerizable monomer preferably replaces a portion of the copolymerizable unsaturated monomer. When a multiolefin monomer is used, the monomer mixture can also comprise from 0.01 to 1 % by weight of at least one multiolefin crosslinking agent, and the amount of multiolefin monomer is correspondingly reduced when the multiolefin crosslinking agent is present.

[0032] The unsaturated isoolefin copolymers can be prepared by any suitable method, of which a number are known in the art. For example, polymerization of the monomers can be carried out in the presence of an initiator system (e.g., a Lewis acid catalyst and a proton source) capable of initiating the polymerization process in a diluent. Suitable proton sources for use in the present application include any compound that will generate a proton when added to a Lewis acid or a composition containing a Lewis acid. The proton can be generated from the reaction of a Lewis acid with a proton source to produce a proton and a corresponding byproduct. This reaction can be preferred in cases where the reaction of the proton source with the protonating additive is faster than its reaction with the monomers. Reactants that generate a proton include, for example, water, alcohols, phenols thiols, carboxylic acids, or any mixture thereof. Water, alcohols, phenols, or any mixture thereof are preferred. The most preferred proton source is water. The preferred ratio of Lewis acid to proton source is from 5: 1 to 100: 1 by weight, or from 5: 1 to 50: 1 by weight. The initiator system, including catalyst and proton source, is preferably present in the reaction mixture in an amount of 0.02-0.1 wt% based on the total weight of the reaction mixture.

[0033] Aluminum alkyl halide catalysts are a particularly preferred class of Lewis acids for use in catalyzing the solution polymerization reactions according to the present application. Examples of aluminum alkyl halide catalysts include methyl dibromide aluminum, methyl dichloride aluminum, ethyl dibromide aluminum, ethyl dichloride aluminum, butyl dibromide aluminum, butyl dichloride aluminum, dimethyl bromide aluminum, dimethyl chloride aluminum, diethyl bromide aluminum, diethyl chloride aluminum, dibutyl bromide aluminum, dibutyl chloride aluminum, methyl aluminum sesquibromide, methyl aluminum sesquichloride, ethyl aluminum sesquibromide, ethyl aluminum sesquichloride, and any mixture thereof. Preferred are diethyl chloride aluminum (Et2AlCl or DEAC), ethyl aluminum sesquichloride (Et 1.5 AlCl 1.5 or EASC), ethyl dichloride aluminum (EtAlCl2or EADC), diethyl bromide aluminum (Et2AlBr or DEAB), ethyl aluminum sesquibromide (Et 1.5 AlBr 1.5 or EASB), and ethyl dibromide aluminum (EtAlBr2or EADB), and any mixture thereof. In a particularly preferred initiator system, the catalyst comprises ethyl aluminum sesquichloride, preferably produced by mixing equimolar amounts of diethyl chloride aluminum and ethyl dichloride aluminum, preferably in a diluent. The diluent is preferably the diluent used to carry out the copolymerization reaction.

[0034] The diluent can include an organic diluent. Suitable organic diluents can include, for example, alkanes, chloroalkanes, cycloalkanes, aromatics, hydrofluorocarbons (HFCs), or any mixture thereof. The chloroalkanes can include, for example, methyl chloride, dichloromethane, or any mixture thereof. Methyl chloride is particularly preferred. The alkanes and cycloalkanes can include, for example, isopentane, cyclopentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane, n-hexane, methylcyclopentane, 2,2-dimethylpentane, or any mixture thereof. The alkanes and cycloalkanes are preferably C6solvents, which include n-hexane or hexane isomers, such as 2-methylpentane or 3-methylpentane, or mixtures of n-hexane and such isomers as well as cyclohexane. These monomers are typically cationically polymerized in the diluent at temperatures ranging from -120°C to +20°C, preferably -100°C to -50°C, more preferably -95°C to -65°C. The temperature is preferably about -80°C or colder.

[0035] In the case where the diluent comprises a chloroalkane (e.g., methyl chloride) in a slurry polymerization process, the diluent, as well as any residual monomer, can be removed from the unsaturated isoolefin copolymer by flash separation using steam. Removal of the diluent and residual monomer in this 'wet' process leaves the polymer containing a significant amount of water. This polymer is dissolved in an organic solvent to provide a polymer binder having a significant water content (e.g., 1 wt% or more, or 1.5 wt% or more, based on the total weight of the binder). In some embodiments, the water content of the binder can be 0-30 wt%, or 0-25 wt%, 1-30 wt%, or 1.5-15 wt%, or 2-30 wt%, or 2-20 wt%, or 2-15 wt%, or 5-20 wt%, or 5-15 wt%, or 5-10 wt%, or 10-15 wt%, based on the total weight of the binder.

[0036] When the diluent comprises a chloroalkane (e.g., methyl chloride) or an alkane (e.g., hexane) in a slurry or solution polymerization process, the diluent, as well as any residual monomer, can be removed from the unsaturated isoolefin copolymer by flash separation using heated organic solvents in which the unsaturated isoolefin copolymer is soluble or by simple distillation. When simple distillation is used, some of the organic diluent can remain in the binder as an organic solvent. Removal of the diluent and residual monomer in this 'dry' process provides a polymer binder containing less water, e.g., less than 1 wt%, or even 0 wt%, based on the total weight of the binder.

[0037] To form the halogenated isoolefin copolymer, a halogenation process can be performed on the unsaturated isoolefin copolymer using a halogenating agent under halogenation conditions. The halogenation can be performed by adapting methods known to those skilled in the art (e.g., procedures described in Rubber Technology, 3rd Ed., Edited by Maurice Morton, Kluwer Academic Publishers, pp. 297-300 or U.S. Patent No. 5,886,106 (published March 23, 1999), the contents of both of which are incorporated herein by reference), and altering the methods as described herein.

[0038] To improve the efficiency of halogenation, the halogenation process is altered by contacting the unsaturated isoolefin copolymer binder dissolved in an organic solvent with a halogenating agent and an aqueous solution of a potassium salt-based oxidizing agent. A two-phase reaction medium is formed comprising an organic phase and an aqueous phase. The oxidizing agent oxidizes the halide produced in the halogenation process back to molecular halogen in situ to improve the halogen atom efficiency of the halogenation process.

[0039] The halogenating agent that can be used to halogenate the unsaturated isoolefin copolymer can comprise molecular chlorine (CI2) or molecular bromine (Br2) and / or organic or inorganic halide precursors thereof, such as dibromo-dimethylhydantoin, trichloroisocyanuric acid (TClA), n-bromosuccinimide, sodium bromide, hydrogen bromide, and the like. Preferably, the halogenating agent comprises chlorine (CI2) or bromine (Br2), more preferably bromine. Preferably, the halogenation comprises bromination. The amount of halogenating agent is controlled to provide a final halogen content of at least 0.05 mol%, preferably 0.05-2.5 mol% in the halogenated isoolefin copolymer. The amount of halogenating agent used has a linear relationship with the final halogen content (i.e., the amount of functional halogen) on the halogenated isoolefin copolymer. Greater amounts of halogenating agent result in greater amounts of functional halogen in the halogenated isoolefin copolymer.

[0040] The halogenation is performed in a reaction medium comprising an organic solvent. The organic solvent is preferably an aliphatic solvent. The organic solvent preferably comprises an alkane, more preferably hexane or pentane.

[0041] The halogenation can be performed for a period of time to achieve the desired level of halogenation. The length of time is preferably 60 minutes or less. Significant halogenation of the unsaturated isoolefin copolymer can be achieved even in 20 minutes or less or 10 minutes or less or 5 minutes or less. Preferably, the halogenation is performed for a minimum of 1 minute. Preferably, the halogenation time is 1-60 minutes, or 1-20 minutes, or 1-10 minutes, or 1-5 minutes.

[0042] The halogenation can be carried out at any suitable temperature and preferably at a temperature up to about 90 °C. In some embodiments, the temperature can be up to about 80 °C. In other embodiments, the temperature can be up to about 65 °C. The increased efficiency of halogenation at lower temperatures is more pronounced at higher concentrations of the unsaturated isoolefin copolymer in the reaction medium. Preferably the temperature is in the range of 0-70 °C or 0-50 °C or 0-45 °C or 15-45 °C or 20-45 °C or 40-45 °C or 30-70 °C or 20-60 °C or 23-54 °C or 23-45 °C or 10-35 °C or 20-30 °C. In one embodiment, the unsaturated isoolefin copolymer is cooled prior to contacting the unsaturated isoolefin copolymer binder solution with the aqueous solution of halogenating agent and oxidizing agent.

[0043] The unsaturated isoolefin copolymer is preferably present in the reaction medium in an amount of 1-60 wt% based on the total weight of the reaction medium. More preferably, the unsaturated isoolefin copolymer is present in an amount of 5-50 wt%, even more preferably 5-40 wt%, still more preferably 10-33 wt%, even more preferably 10-30 wt%, such as 20 wt%, based on the total weight of the reaction medium.

[0044] The aqueous phase is formed from the aqueous solution of oxidizing agent, water produced by the halogenation reaction, and any additional water contained in the unsaturated isoolefin polymer binder. This aqueous solution of oxidizing agent, together with the water produced by the halogenation reaction, typically forms less than 1 wt% of the reaction medium, such as 0.03-0.3 wt%, based on the total weight of the reaction medium.

[0045] The reaction medium can contain 0-20 wt% additional water based on the total weight of the reaction medium, the additional water originating from water contained in the unsaturated isoolefin polymer binder, depending on the method used to prepare the polymer binder. The additional water is water from the unsaturated isoolefin polymer binder and does not include water used to prepare the aqueous solution of oxidizing agent or water produced by the halogenation reaction. An advantage of the method of the present invention is that the reaction medium can contain a significant amount of additional water, such as 1-20 wt% additional water, based on the total weight of the reaction medium. In some embodiments, the additional water can comprise 1.5 wt% - 15 wt% or 2 wt% - 20 wt% or 2 wt% - 15 wt% or 5 wt% - 20 wt% or 5 wt% - 15 wt% or 5 wt% - 10 wt% of the reaction medium, based on the total weight of the reaction medium. Even so, in some embodiments, the reaction medium can contain an insignificant amount of additional water, such as less than 1 wt% additional water, or even 0 wt% additional water, based on the total weight of the reaction medium.

[0046] The potassium salt-based oxidizer preferably includes a salt of potassium cation with one or more peroxygen anions, which has the ability to act as an oxidizer against halogen ions (e.g., chloride or bromide ions, especially bromide ions). Mixed salts with one or more other cations (e.g., sodium, lithium, etc.) can be used therein, but salts with potassium cation only are preferred. In some embodiments, the potassium salt-based oxidizer includes KHSO5, K2S2O8, KClO, KBrO, KBrO3, KIO3, KClO3, KClO4, KIO4, a compound that produces the above potassium salt-based oxidizers, or mixtures thereof. Preferably, the potassium salt-based oxidizer includes KHSO5or a compound that produces KHSO5. Potassium peroxymonosulfate is particularly preferred. Potassium peroxymonosulfate produces KHSO5as the effective oxidizer species.

[0047] Potassium peroxymonosulfate (KHSO5-0.5KHSO4-0.5K2SO4) is a commercially available water-soluble potassium triply salt. Potassium peroxymonosulfate is an easy-to-handle, non-toxic, odorless, stable, and inexpensive white crystalline stable solid. Aqueous solutions of potassium peroxymonosulfate have a pH of 2 and are stable at 45°C for at least 1 hour, but undergo decomposition when the pH is greater than 3. Potassium peroxymonosulfate produces only KHSO4as a byproduct of oxidation. Table 1 compares the properties of potassium peroxymonosulfate with other known oxidizers. The standard oxidation potential of potassium peroxymonosulfate is 1.85 V, which is close to H2O2and peracetic acid, indicating that potassium peroxymonosulfate can oxidize halides to halogens. Potassium peroxymonosulfate has a higher decomposition temperature compared to H2O2and peracetic acid, which can facilitate storage and transportation and extend the shelf life. Potassium peroxymonosulfate is a solid, which facilitates handling and maintaining the desired stoichiometry. Potassium peroxymonosulfate produces KHSO4as the only byproduct, which is easily washed away during neutralization. Potassium peroxymonosulfate has no odor, so it will not impart any odor to the finished product.

[0048] Table 1

[0049]

[0050] Because potassium salt-based oxidants are substantially insoluble in organic solvents, a phase transfer catalyst is preferably used. The phase transfer catalyst preferably complexs potassium ions to facilitate transfer of the oxidant into the organic phase and emulsify the aqueous phase in the organic phase to increase surface area contact between the organic and aqueous phases. Use of a phase transfer catalyst in conjunction with a potassium salt-based oxidant increases bromine recovery efficiency to more than that reported in prior art methods. The phase transfer catalyst preferably provides a host-guest interaction with potassium ions, in which the potassium ions complex with multiple complexing sites on a molecule of the phase transfer catalyst. The complexing sites can comprise atoms (e.g., O, N, S) that have one or more lone pair electrons available for complexing with potassium ions. Preferably, a molecule of the phase transfer catalyst comprises 5 or more complexing sites, more preferably 6 or more complexing sites, still more preferably 7 or more complexing sites. If the phase transfer molecule is large enough and has a sufficient number of complexing sites, one phase transfer molecule can form a complex with two or more potassium ions. The phase transfer molecule can be acyclic or cyclic, or comprise both acyclic and cyclic portions. The acyclic molecule or portions thereof can be straight-chained or branched. The phase transfer molecule is preferably a non-ionic surfactant. The phase transfer catalyst preferably includes multiple ethylene oxide units therein, preferably 3-20 ethylene oxide units. The phase transfer catalyst preferably comprises at least one hydrocarbon chain. Preferably, the phase transfer catalyst comprises multiple oxygen atoms with which potassium ions complex. The phase transfer catalyst preferably comprises a polyalkylene oxide ether, such as polyethylene glycol. The polyalkylene oxide ether is preferably alkylated to increase solubility in the organic phase.

[0051] In some embodiments, the phase transfer catalyst comprises Lutensol TM series of compounds, Tween TM series of compounds, Triton TM X-100, polyglyceryl polyricinoleate, Poloxamer TM 407, Poloxamer TM , Polidocanol TM , pentaethylene glycol monododecyl ether, PEG-10 sunflower glycerides, octaethylene glycol monododecyl ether, NP-40, Nonoxynol TM -9, Isoceteth TM -20, Cetomacrogol TM 1000, or mixtures thereof.

[0052] The oxidizing agent and phase transfer catalyst are preferably present in the aqueous solution in a molar ratio ranging from 1 :3 to 100: 1, or 1 :3 to 75: 1. Preferably, the oxidizing agent and phase transfer catalyst are present in the aqueous solution in a 1 : 1 molar ratio, especially where there are sufficient complexing sites on the phase transfer molecule to accommodate only a single potassium ion.

[0053] The oxidizing agent and phase transfer catalyst are preferably pre-mixed in the aqueous solution prior to introducing the aqueous solution into the reaction medium binder, but in some cases the oxidizing agent and phase transfer catalyst can be introduced separately into the reaction medium containing the binder, preferably by first adding the phase transfer catalyst followed by the oxidizing agent. The oxidizing agent and phase transfer catalyst are preferably added to the reaction medium prior to the introduction of the halogenating agent.

[0054] The concentration of oxidizing agent present in the reaction medium is preferably at least 0.06 moles oxidizing agent per mole of halogenating agent, or at least 0.1 moles oxidizing agent per mole of halogenating agent. The concentration of oxidizing agent present in the reaction medium is preferably 0.2-5 moles, more preferably 0.25-4 moles, still more preferably 0.5-3 moles of oxidizing agent per mole of halogenating agent. The desired concentration of oxidizing agent is a function of the desired halogenation time. For a halogenation time of 5 minutes, 0.5-2 moles, for example 2 moles, of oxidizing agent per mole of halogenating agent is preferred. Lower concentrations of oxidizing agent can be offset by longer halogenation times. Adjusting the stirring rate of the reaction medium can result in an improvement in halogenation efficiency.

[0055] In the process of the present application, all or some of the halogenating agent can comprise hydrogen halide (HX) added to the aqueous phase. Because HX is converted to molecular halogen (X2) by the oxidizing agent in the aqueous phase, the added HX can serve as a source of halogenating agent.

[0056] Example

[0057] Scheme 1 shows an example of a process for producing a halogenated isoolefin copolymer. As shown in Scheme 1, Br2 is used as the halogenating agent, KHSO5 as the effective oxidizing agent, and Lutensol TO5 as the phase transfer catalyst. The oxygen atom complexing sites on the phase transfer catalyst form an ionic dipole interaction with the potassium ion of KHSO5. In addition, a hydrogen bond interaction is formed between HSO5"and the oxygen atom and hydroxyl hydrogen atom of the phase transfer catalyst. In this way, the phase transfer catalyst is able to extract the oxidizing agent from the aqueous phase to effect the oxidation of HBr produced in the organic phase back to Br2. In addition, bromide ions that migrate into the aqueous phase can be oxidized by the oxidizing agent to reform Br2, which will preferentially transfer back into the organic phase. In this way, the efficiency of bromine use in the bromination reaction can be improved. TM TO5 as the phase transfer catalyst, the oxygen atom complexing sites on the phase transfer catalyst form an ionic dipole interaction with the potassium ion of KHSO5. In addition, a hydrogen bond interaction is formed between HSO5"and the oxygen atom and hydroxyl hydrogen atom of the phase transfer catalyst. In this way, the phase transfer catalyst is able to extract the oxidizing agent from the aqueous phase to effect the oxidation of HBr produced in the organic phase back to Br2. In addition, bromide ions that migrate into the aqueous phase can be oxidized by the oxidizing agent to reform Br2, which will preferentially transfer back into the organic phase. In this way, the efficiency of bromine use in the bromination reaction can be improved.

[0058]

[0059] Materials and Methods

[0060] Isobutylene-isoprene polymer (IIR) and epoxidized soybean oil (ESBO) were obtained from ARLANXEO (Sarnia, Ontario, Canada site). Remaining materials were used as received: Potassium oxymonosulfate (Oxone TM , with greater than 4 wt% active oxygen, from Sigma Aldrich), potassium bromate (Sigma Aldrich), sodium hypochlorite (available chlorine 10-15%), Lutensol TM TO3 (BASF), Lutensol TM TO5 (BASF), Lutensol TM TO8 (BASF), Tween TM 20 (Taiko), hexane (VWR), isopentane (Sigma Aldrich), sodium hydroxide (VWR), 99.99% bromine (Sigma Aldrich), 30 wt% hydrogen peroxide (Sigma Aldrich), 32 wt% peracetic acid solution (Sigma Aldrich), calcium stearate (Alfa Aesar), and Irganox TM 1010 (BASF).

[0061] Bromination Reaction

[0062] A 250 g piece of isobutylene-isoprene copolymer (butyl rubber, IIR) was cut into small pieces and added to a 5 L jacketed reactor equipped with an overhead stirrer and pre-filled with “X” mL of hexane or isopentane. The stir speed was set to 150 rpm while the base material pieces were added to the reactor. This solution was stirred for 24 hours to completely dissolve the butyl rubber. After the isobutylene-isoprene copolymer had completely dissolved, “Y” mL of water was added to the reactor via a pipette to provide a butyl rubber cement. In embodiments where an oxidizing agent was used for bromine recovery, the oxidizing agent was first dissolved in “Z” mL of water, then the resulting aqueous solution was added to the reactor. In embodiments where both a phase transfer catalyst and an oxidizing agent were used, the phase transfer catalyst and the oxidizing agent were first dissolved in “Z” mL of water, then the resulting aqueous solution was added to the reactor. The amounts of oxidizing agent and phase transfer catalyst are shown in the examples. The values of X, Y, and Z were chosen in the following examples to provide a butyl rubber cement with a water content.

[0063] The circulating bath connected to the jacketed reactor was set to the desired temperature to heat the reactor and the butyl rubber binder was stirred at 350 rpm for 30 minutes at the desired temperature shown in the examples. Bromine (Br2) (2.15 mL, 6.71 g, 0.042 mole) was then added with a syringe and the reaction was stirred for 1 hour.

[0064] During the 1 hour period, 10 mL samples of the reaction medium were pipetted at 5, 20, 40 and 60 minutes and added to vials containing 10 mL of 2.5 M NaOH at which time the vials were shaken vigorously to quench residual bromine, HBr and oxidant. The halogenated polymer samples in the vials were then collected by precipitating the polymer solution into ethanol and drying the precipitate at 60 °C under vacuum for 48 h.

[0065] After the 1 hour period, a predetermined amount of 2.5 M NaOH solution was added to the remaining reaction medium to quench the reaction. An additional 250 mL of water was added to aid mixing. The mixture was continued to be stirred at 350 rpm for 5 minutes. An additional 1 L of water was added and allowed to stir for another 5 minutes at 350 rpm. The stirring was reduced to 150 rpm and the stirring was continued for another 5 minutes. The reactor stirring was stopped and the aqueous phase was drained through the bottom drain valve. The binder of brominated isobutylene-isoprene copolymer was washed with additional water until the pH was 7 to remove any residual inorganic salts. A solution of polymer stabilizers (4.52 g calcium stearate, 0.125 g Irganox 1010 and 3.25 g ESBO) in hexane was added to the reactor and the binder was stirred for 5 minutes. The binder was drained and steam coagulated using low pressure steam for about 1 hour. Small pieces of the brominated polymer sample were cut from the final product and dried in a vacuum oven at 60 °C overnight. TM -1010 and 3.25 g ESBO) in hexane was added to the reactor and the binder was stirred for 5 minutes. The binder was drained and steam coagulated using low pressure steam for about 1 hour. Small pieces of the brominated polymer sample were cut from the final product and dried in a vacuum oven at 60 °C overnight.

[0066] The 1 H-NMR spectroscopy was used to analyze the microstructure and bromine content of the dried samples.

[0067] Bromine utilization calculation

[0068] Bromine utilization during the bromination process can be measured using the bromine atom efficiency (BAE) which is given by the following equation:

[0069]

[0070] The atomic Br on the polymer is given by 1¹H-NMR calculations. The number of Br atoms in the bromine added to the reaction is calculated from the volume of bromine used in the reaction. From the equation, it is clear that ideal conditions would produce 50% BAE, where 50% of the Br is in the waste HBr. Therefore, the theoretical maximum amount of bromine that can be present in the reaction mixture that can be introduced into this butyl rubber polymer is 50%. However, in practice, BAE is typically less than 45%, for example, 30%–45% or 35%–45%.

[0071] In some prior methods (e.g., in US 3,018,275 and US 5,681,901), bromine utilization was measured using the molecular weight of bromine added to the reaction, which provided a numerical result twice that of BAE because there are two bromine atoms in each bromine molecule. Furthermore, these prior methods used X-ray diffraction to estimate the amount of Br bound to the polymer. However, this method also measures NaBr produced by the neutralization process, which is trapped within the polymer matrix. The trapped NaBr does not necessarily measure the amount of Br chemically bonded to the polymer and often provides a bromine utilization efficiency number that is higher than the actual efficiency.

[0072] Stability of potassium persulfate

[0073] The temperature stability of potassium persulfate in aqueous solution was determined to evaluate its suitability as an oxidant for bromine recovery during the bromination of butyl rubber.

[0074] 10 mL of a 0.1 mg / L potassium persulfate aqueous solution was placed in a water bath preheated to 45 °C. At different time intervals, 1.0 mL of a 0.1 g / mL potassium persulfate aqueous solution was added to a tare 250 mL Erlenmeyer flask, and the mass of the solution was recorded. The solution was then titrated with 0.1 N standard sodium thiosulfate solution. The titration procedure was based on Oxone. TM The data table is described below.

[0075] Add 75 mL of deionized water, 10 mL of 20% (v / v) sulfuric acid, and 10 mL of 25% (w / w) potassium iodide solution to a 250 mL Erlenmeyer flask containing 1.0 mL of 0.1 mg / mL potassium persulfate aqueous solution. Immediately titrate the sample with 0.1 N sodium thiosulfate solution until a pale yellow color is reached. Then, add 3 mL of starch indicator solution and adjust the solution to a deep blue color. Continue titrating to a colorless endpoint for at least 30 seconds. Calculate the reactive oxygen species content according to the following equation:

[0076]

[0077] where mLthio is the volume of the sodium thiosulfate solution and Nthio is the normality of the sodium thiosulfate solution.

[0078] The results are shown in Figure 1 Figure 1 It is shown that the active oxygen is 5 wt%, which is in line with the technical data sheet from the supplier, and that the active oxygen does not change over one hour. Thus, the potassium peroxymonosulfate is stable at the temperature of the bromination process of butyl rubber at 45°C and during the time period of the bromination process.

[0079] Example 1 : role of potassium peroxymonosulfate in the bromination of IIR

[0080] The bromination reaction was performed as described above, wherein the amount of butyl rubber (IIR) was 20 wt% based on the total weight of the reaction medium, and the amount of water added was 5 wt% based on the total weight of the reaction medium. The IIR had an unsaturation of 1.78 mol%.

[0081] Method P1 is a control, wherein no bromine recovery was attempted, as no oxidizing agent was added. Method P2 used 6.4 g of potassium peroxymonosulfate as oxidizing agent to recycle bromine, which provided a 1 :2 molar ratio of oxidizing agent:Br2, which is 0.5 equivalent of oxidizing agent per bromine molecule. Method P3 used 6.4 g of potassium peroxymonosulfate as oxidizing agent and 120 mg of Lutensol TM TO5 as phase transfer catalyst (PTC). Lutensol TM TO5 is isotridecanol polyoxethylene ether, which is a derivative of polyethylene glycol (PEG). Table 2 provides the results of samples extracted from the reaction medium at the 60 minute time mark for the corresponding processes P1, P2 and P3.

[0082] As shown in Table 2, comparing P1 with P2, when only 0.5 equivalent of potassium peroxymonosulfate was used as oxidizing agent, the functional Br increased from 0.61 mol% to 0.72 mol% at the 60 minute mark, which indicates that bromine recycling occurs in the presence of the potassium peroxymonosulfate oxidizing agent. However, the inclusion of the phase transfer catalyst Lutensol TM TO5 further increased the functional Br to 0.85% (P3), which is an 18% improvement over the potassium peroxymonosulfate alone.

[0083] Table 2 - IIR (20 wt%), water (5 wt%), temperature (45°C), Br2 (0.042 moles)

[0084] Method Oxidant (g) PTC (mg) Functional Br (mol%) BAE (%) P1 0 0 0.61 32.4 P2 6.4 0 0.72 38.2 P3 6.4 120 0.85 45.1

[0085] ​By analyzing samples of each method P1, P2, and P3 acquired at time markers of 5-minute, 20-minute, 40-minute, and 60-minute intervals, the functional Br was determined as a function of reaction time. Figure 2 The results show that in the control method (P1, triangle), the functional Br does not increase over time, while for both methods P2 (rhombus) and P3 (square) using potassium peroxymonosulfate as the oxidant, the functional Br increases. The maximum increase in functional Br over time occurs when the oxidant is complexed with the phase-transfer catalyst (P3, square).

[0086] For 60-minute-marked brominated butyl rubber from P2 1 ¹H NMR spectroscopy was used to analyze the microstructure to see if it was identical to that of the brominated butyl rubber sample from P1. Figure 3 As shown, for butyl rubber from method P2, the resonance signals at 5.4 ppm, 5.02 ppm, and 4.34 ppm indicate the formation of brominated butyl rubber. The integral ratio of a:b:c is 1:1:1, which also matches the chemical structure of brominated butyl rubber from P1. It is known that when potassium persulfate is used to epoxidize olefins, the resulting chemical shift is 2.7 ppm. In the sample from P2... 1 This peak was not observed in the H NMR spectrum, indicating that no epoxidized butyl rubber contaminants were generated.

[0087] Example 2: Water sensitivity of potassium persulfate in IIR bromination

[0088] To determine the water sensitivity of potassium persulfate oxidant, bromination methods P4 and P5 were performed as described above, except for the condition variations shown in Table 3. The IIR had an unsaturation of 1.78 mol%. Samples from P4 and P5 were extracted from the reaction medium at the 60-minute time mark of the respective methods. See Table 3 and... Figure 4A As shown, when using 240mg of Lutensol TM When using the TO5 phase transfer catalyst (PTC) (from the sample of P4), compared with when using 120 mg of Lutensol... TM The functional Br increased to 0.92 mol% compared to 0.85 mol% at TO5 (from sample P3 in Table 2). Furthermore, a larger amount of Lutensol was used. TM TO5 accelerates bromination and bromine recovery because the functional bromine level reaches a plateau after 20 minutes (see [link]). Figure 4A This is different from P3 (see P3). Figure 2 (The functional Br needs one hour to reach the plateau. From Table 3 and...) Figure 4AIt is apparent that the ability of potassium peroxymonosulfate to recycle bromine is not very sensitive to the amount of water added to the butyl rubber bromination process.

[0089] Table 3 - IIR (20 wt%), Temperature (45°C), Br2 (0.042 moles)

[0090] Method Water (wt%) Oxidant (g) PTC (mg) Functional Br (mol%) BAE (%) P4 5 6.4 240 0.92 48.8 P5 15 6.4 240 0.98 52.0

[0091] In another experiment, the water concentration added to the butyl rubber adhesive was 0 to 25 wt% to provide a formulation containing 20 wt% IIR, 3.2 g potassium peroxymonosulfate oxidant, 240 mg Lutensol TM TO5 phase transfer catalyst and 0.042 moles of Br2. The bromination was carried out at 45°C for a period of 60 minutes. Samples were taken at 5 minutes (P6) and 60 minutes (P7) and the bromine atom efficiency (%) was determined for each sample. As shown in Table 3, the BAE increased slightly between 0 wt% and 10 wt% added water and then tapered off back to the same BAE as the 0 wt% water sample. Overall, the ability of potassium peroxymonosulfate to recycle bromine was not very sensitive to the amount of water added to the butyl rubber bromination process. Figure 4B

[0092] Example 3: Effect of the amount and type of phase transfer catalyst on the bromination of IIR.

[0093] As shown in the bromination method P8-P10 in Table 4A, Lutensol TM TO5 was first tested at 60 mg (P8) and the BAE was 97.6%. The amount of Lutensol TM TO5 was increased to 240 mg (P9) and the BAE increased. Further increasing the Lutensol TM TO5 to 480 mg (P10) resulted in a slight decrease in the BAE, but it was still higher than the sample where no Lutensol TM TO5 was added (P7). TM TO5 was added (P7).

[0094] Table 4A - IIR (20 wt%), Water (10 wt%), Temperature (45°C), Br2 (0.042 moles), Oxidant (0.01 mol)

[0095] Method Oxidant (g) PTC (mg) PTC (type) BAE (%) P8 3.2 60 Lutensol XP 1000 TM TO5 45.1 P9 3.2 240 Lutensol TM TO5 48.8 P10 3.2 480 Lutenso l TM TO5]] 45.6

[0096] Lutensol​TM The product is a non-ionic molecule of general formula: RO(CH2CH2O) n H, wherein R is iso-C 13 H 27 and n is 3, 5, 6, 6.5, 7, 8, 10, 12, 15 or 20, wherein n defines the degree of ethoxylation. In Lutensol TM TO3, n is 3. In Lutensol TM TO5, n is 5. In Lutensol TM TO8, n is 8. The structure of the Lutensol TM series compounds is:

[0097]

[0098] In addition to Lutensol TM TO5, Lutensol TM TO8 and Lutensol TM TO3 were also tried for bromination (P12 and P13 in Table 4B). The results at 60 minute nark were compared with P11 using Lutensol TM TO5. (P11 is the same experiment as P5). 240 mg Lutensol TM TO5, 209 mg Lutensol TM TO8 and 316.3 mg Lutensol TM TO3. The number of ethylene glycol units was the same. As shown in Table 4B, the BAE remained the same when using Lutensol TM TO5 compared to Lutensol TM TO8 and Lutensol TM TO3. It is reported that a minimum number of 7 ethylene glycol units is required to achieve good complexation with potassium ions. However, when the ethylene glycol chain is shorter, the partitioning of the phase transfer catalyst in the organic phase is improved because it becomes less water soluble, which can explain the bromination results when using Lutensol TM TO3.

[0099] Table 4B - IIR (20 wt%), water (15 wt%), temperature (45°C), Br2(0.042 moles), oxidant (0.02 mol)

[0100] Method Oxidant (g) PTC (mg) PTC (type) BAE (%) P11 (P5) 6.4 240 Lutensol TM TO5 52.0 P12 6.4 209 Lutensol TM TO8 50.4 P13 6.4 316.3 Lutensol TM TO3 52.5

[0101] Tween TM20 also known as PEG (20) sorbitan monolaurate or polysorbate 20, is a non-ionic molecule based on polyethylene glycol. Tween TM The structures of the series of compounds are as follows, where w+x+y+z for Tween TM 20 is 20 and for Tween TM 80 is 80:

[0102]

[0103] For a 1 h reaction, bromination in the presence of Tween TM 20 (P15) indicates that when Tween TM 20 (P15) is used instead of Lutensol TM TO5, the bromine recovery is slightly improved.

[0104] Table 4C - IIR (20 wt%), water (15 wt%), temperature (45 °C), Br2(0.042 moles), oxidant (0.01 mol)

[0105] Method Oxidant (g) PTC (mg) PTC (type) BAE (%) P14 3.2 240 Lutensol TM TO5 45.6 P15 3.2 172 Tween TM 20]]> 49.3

[0106] Example 4: Effect of the amount of potassium peroxymonosulfate in the bromination of IIR

[0107] To determine the effect of the amount of potassium peroxymonosulfate oxidant, three sets of bromination were performed, which were bromination with 20 wt% IIR and 5 wt% water (Table 5A, Figure 5A ), bromination with 20 wt% IIR and 10 wt% water (Table 5B, Figure 5B ), and bromination with 20 wt% IIR and 15 wt% water (Table 5C, Figure 5C ).

[0108] As shown in Figure 5A compared to P16, where no oxidant was added. P17 and P18 (P18 is the same experiment as P4) show increased functional Br and BAE, indicating the occurrence of bromine recovery. Moreover, reducing the amount of potassium peroxymonosulfate by half does not reduce the functional Br much (compare P17 (squares) with P18 (triangles)). Furthermore, only 0.25 equivalents of potassium peroxymonosulfate (i.e. 1 :4 molar ratio) is needed compared to Br2to achieve 0.9 mol% of functional Br (see P17 (squares), which is advantageously compared to the use of peracetic acid (PAA) which requires 0.5 equivalents (1 :2 molar ratio) to achieve 0.9 mol% of functional Br.

[0109] Table 5A - IIR (20 wt%), water (5 wt%), temperature (45 °C), Br2(0.042 moles)

[0110] Method Oxidant (g) PTC BAE (%) P16 0 240 mg Lutensol XP-80 TM TO5 38.2 P17 3.2 240 mg Lutensol XP-80 TM TO5 46.2 P18 (P4) 6.4 240 mg Lutensol XP-80 TM TO5 48.8

[0111] A second set of bromination methods P19, P20, P21, P22, and P23 with 10 wt% were performed as described above except for the condition changes shown in Table 5B. Method P19 was a control method without the use of oxidant. As shown, increasing the amount of potassium peroxymonosulfate generally increased functional Br. Similar to the first set of experiments, reducing the amount of potassium peroxymonosulfate by half did not reduce functional Br much (compare P21 (triangles) and P22 (Xs)). Moreover, only 0.25 equivalents of potassium peroxymonosulfate (i.e., 1 :4 molar ratio) was needed compared to Br2 to achieve 0.9 mol% functional Br (see P21 (triangles)). Figure 5B

[0112] Table 5B - IIR (20 wt%), water (10 wt%), temperature (45 °C), Br2 (0.042 moles)

[0113] Method Oxidant (g) PTC BAE (%) P19 0 240 mg Lutensol XP-80 TM TO5 38.2 P20 1.6 240 mg Lutensol XP-80 TM TO5 40.3 P21 3.2 240 mg Lutensol XP-80 TM TO5 49.3 P22 6.4 240 mg Lutensol XP-80 TM TO5 49.9 P23 9.6 240 mg Lutensol XP-80 TM TO5 54.6

[0114] A third set of bromination methods P24, P25, P26, and P27 (with 15 wt%) were performed as described above except for the condition changes shown in Table 5C (P26 was the same experiment as P14). Method P24 was a control method without the use of oxidant. As shown in Table 5C and Table 5C, increasing the amount of potassium peroxymonosulfate generally increased functional Br and BAE. Moreover, only 0.25 equivalents of potassium peroxymonosulfate (i.e., 1 :4 molar ratio) was needed compared to Br2 to achieve 0.86 mol% functional Br (see P26 (diamonds)). By comparing BAE from P17 (46.2%), P21 (49.3%), and P26 (45.6%), it was apparent that bromine recovery was not compromised when water concentration was increased from 5 wt% to 15 wt%, indicating that bromine recovery was not sensitive to water concentration in the binder, which was consistent with the results from Example 2. Figure 5C

[0115] Table 5C - IIR (20 wt%), water (15 wt%), temperature (45 °C), Br2 (0.042 moles)

[0116] Method Oxidant (g) PTC BAE (%) P24 0 240 mg Lutensol XP-80 TM TO5 39.8 P25 1.6 240 mg Lutensol XP-80 TM TO5 42.5 P26 (P14) 3.2 240 mg Lutensol XP-80 TM TO5 45.6 P27 6.4 240 mg Lutensol XP-80 TM TO5 49.9

[0117] Example 5: Effect of binder concentration in bromination of IIR.

[0118] ​​Butyl rubber binders were obtained from slurry polymerization of isobutylene and isoprene in chloromethane according to known methods to provide binders having a water content of 10 wt% and a butyl rubber (IIR) content of 10-33 wt%. These binders were brominated at 45°C according to the above procedure using 3.2 g of potassium peroxymonosulfate and 240 mg of Lutensol XP-DB® TO5. TM TO5 were used. Figure 6 The peak in bromination efficiency was shown at an IIR concentration of about 20 wt%. This result is consistent with the bromination results using peracid as oxidant.

[0119] Method P28: Bromination for 5 minutes, binder concentration of 10, 15, 20 and 25 wt%, 10 wt% water, 3.2 g of potassium peroxymonosulfate, 240 mg of Lutensol XP-DB® TO5. TM TO5.

[0120] Method P29: Bromination for 60 minutes, binder concentration of 10, 15, 20 and 25 wt%, 10 wt% water, 3.2 g of potassium peroxymonosulfate, 240 mg of Lutensol XP-DB® TO5. TM TO5.

[0121] Example 6: Role of oxidant / PTC complex formation in bromination of IIR

[0122] To determine if the initial formation of oxidant / phase transfer catalyst complex is important for bromine recovery, bromination method P30 was performed with the conditions shown in Table 6 and compared to a control bromination (P1) where neither oxidant nor phase transfer catalyst was present. The IIR had 1.78 mol% unsaturation. Method P30 was performed as above except for the following sequence of process steps:

[0123] Method P30: 1) Preparation of IIR binder; 2) Dissolution of Lutensol XP-DB® TO5 in water; 3) Addition of Lutensol XP-DB® TO5 aqueous solution to the binder; 4) Stirring for 30 minutes to reach 45°C; 5) Addition of solid potassium peroxymonosulfate to the binder; 6) Addition of bromine to the binder. TM TO5 in water; 3) Addition of Lutensol XP-DB® TO5 aqueous solution to the binder; 4) Stirring for 30 minutes to reach 45°C; 5) Addition of solid potassium peroxymonosulfate to the binder; 6) Addition of bromine to the binder. TM TO5 in water; 3) Addition of Lutensol XP-DB® TO5 aqueous solution to the binder; 4) Stirring for 30 minutes to reach 45°C; 5) Addition of solid potassium peroxymonosulfate to the binder; 6) Addition of bromine to the binder.

[0124] In fact, the potassium peroxymonosulfate was added as a solid to the binder rather than as part of an aqueous solution, providing less time for the potassium peroxymonosulfate to complex with the Lutensol XP-DB® TO5 before the bromination was started. TM TO5 in water; 3) Addition of Lutensol XP-DB® TO5 aqueous solution to the binder; 4) Stirring for 30 minutes to reach 45°C; 5) Addition of solid potassium peroxymonosulfate to the binder; 6) Addition of bromine to the binder.

[0125] As in Example 5, the bromination of IIR was performed using the conditions shown in Table 6. Figure 7As seen in Table 2 and Figure 2, when potassium peroxymonosulfate is added as a solid (diamonds) to the binder, the functional Br is 0.70 mol%, which is less efficient than when potassium peroxymonosulfate is added as part of an aqueous solution with a phase transfer catalyst to the binder (see Table 2 and Figure 2, P3). Thus, pre-formation of the oxidant / PTC complex before adding them to the binder is important to maintain higher levels of bromine recovery. Figure 2

[0126] Table 6 - IIR (20 wt%), water (5 wt%), temperature (45°C), Br2(0.042 moles)

[0127] Method Oxidant (g) PTC (mg) PTC (type) BAE (%) P30 6.4 120 Lutensol TM TO5 37.7

[0128] Example 7: Effect of Temperature in Bromination of IIR

[0129] To determine the effect of reaction temperature, bromination methods P31, P32, and P33 (P33 is the same experiment as P21) were performed as described above, except for the changes in conditions shown in Table 7. The IIR had 1.78 mol% of unsaturation.

[0130] As shown in Table 7 and Figure 3, reaction temperatures of 23°C (P31, squares), 35°C (P32, triangles), and 45°C (P33, diamonds) resulted in essentially the same bromine recovery, with the functional Br still much higher than the control where no oxidant was used. Figure 8

[0131] Table 7 - IIR (20 wt%), water (10 wt%), Br2(0.042 moles)

[0132] Method T(℃) Oxidant (g) PTC BAE (%) P31 23 3.2 240 mg Lutensol XP-80® TM TO5 48.3 P32 35 3.2 240 mg Lutensol XP-80 TM TO5 46.7 P33 (P21) 45 3.2 240 mg Lutensol XP-80® TM TO5 49.3

[0133] Example 8: Comparison of Bromination in Hexane and Isopentane

[0134] To investigate the effect of solvent on bromine recovery, two brominations P34 and P35 were performed in isopentane with water concentrations of 5 wt% and 15 wt%, respectively. Table 8 provides the results for samples extracted from the reaction medium at the 60 minute time mark for methods P34 and P35, respectively. Due to the low boiling temperature of isopentane, both brominations were performed at 23°C. Although slightly less efficient compared to hexane (P31 and P34), both P34 and P35 showed improvements in BAE when compared to control experiments (P1, P16, and P24) where no oxidant was added.

[0135] Table 8 - IIR (20 wt%), water (10 wt%), Br2(0.042 moles)

[0136] ​​

[0137] Example 9: Comparison with peracetic acid and hydrogen peroxide

[0138] To compare bromine recovery efficiency with potassium peroxymonosulfate (PPMS) with that of peracetic acid (PAA) and hydrogen peroxide (H2O2), bromination processes P36, P37, and P38 were performed as described above except for the condition changes shown in Table 9. The IIR had 1.78 mol% unsaturation.

[0139] It is apparent from Table 9 that hydrogen peroxide is not nearly as effective in terms of bromine recovery as potassium peroxymonosulfate in the presence of added water, even when used in a molar amount that is more than 4 times greater than the molar amount of potassium peroxymonosulfate. It is further apparent from Table 9 that peracetic acid must be used in a molar amount that is twice that of potassium peroxymonosulfate to achieve the same bromine recovery efficiency as potassium peroxymonosulfate.

[0140] Table 9 - IIR (20 wt%), water (10 wt%), temperature (45°C), Br2 (0.042 moles)

[0141] Method Oxidant Oxidant (mol) PTC Functional Br (mol%) P36 H2O2 0.042 None 0.7 P37 PAA 0.02 None 0.9 P38 PPMS 0.01 240 mg Lutensol XP-80 TM TO5 0.9

[0142] Example 10: Potassium-containing K + oxidizing agents

[0143] In addition to potassium peroxymonosulfate, potassium bromate, KBrO3, was also investigated as another K + oxidizing agent. Bromination processes P39 and P40 were performed as described above except for the condition changes shown in Table 10. The IIR had 1.78 mol% unsaturation. Table 10 provides the results for samples withdrawn from the reaction medium at the 60 minute time mark for the corresponding processes P39 and P40. It is apparent from Table 10 and Figure 9 that the addition of Lutensol TM TO5 improves the bromine recovery rate compared to the use of KBrO3 alone. While KBrO3 provides a high bromine recovery efficiency, KBrO3 is more difficult to handle than potassium peroxymonosulfate. Therefore, potassium peroxymonosulfate is considered the preferred K + oxidizing agent.

[0144] Table 10 - IIR (20 wt%), water (5 wt%), temperature (45°C), Br2 (0.042 moles)

[0145] Method Oxidant Oxidant (mol) PTC Functional Br (mol%) P39 KBrO3 0.01 None 0.97 P40 KBrO3 0.01 240 mg Lutensol XP-80 TM TO5 1.08

[0146] Example 11: Effect of other metal salts as oxidizing agents

[0147] To determine the effect of sodium-based oxidants on bromine recovery in the presence of a phase-transfer catalyst, bromination methods P41 and P42 were performed as described above, in addition to the condition variations shown in Table 11. For P42, Lutensol was used... TM TO5 was mixed with 6.5 mL of NaClO and stirred for 5 minutes, then the NaClO solution was added to the reaction medium. Bromine was added to the reaction medium immediately after the NaClO solution was added. The IIR concentration had an unsaturation of 1.78 mol%.

[0148] like Figure 10 As shown, NaClO oxidant (P41, square) and NaClO oxidant with 240 mg Lutensol were added separately. TM The TO5 phase transfer catalyst (P42, Xs) provided very similar bromine recovery efficiency. Therefore, when using NaClO as the oxidant, Lutensol... TM Adding TO5 does not improve bromine recovery. Furthermore, although NaClO offers relatively high bromine recovery efficiency, it is more difficult to handle than potassium-based oxidants, and therefore less ideal.

[0149] Table 11 - IIR (20 wt%), Water (10 wt%), Temperature (45 °C), Br2 (0.042 mol)

[0150] Method Oxidant Oxidant (mol) PTC Functional Br (mol%) P41 NaCI O 0.01 0 0.82 P42 NaCI O 0.01 240 mg Lutensol XP-80 TM TO5 0.82

[0151] Upon examination of this application specification, the novel features will become apparent to those skilled in the art. However, it should be understood that the scope of the claims should not be limited to these embodiments, but rather should be given the broadest interpretation consistent with the wording of the claims and the specification (as a whole).

Claims

1. A method for producing a halogenated isoolefin copolymer, the method comprising contacting an unsaturated isoolefin copolymer binder with an aqueous solution of a halogenating agent and a potassium salt-based oxidant under halogenation conditions to form a two-phase reaction medium comprising an organic phase and an aqueous phase, said binder comprising an unsaturated isoolefin copolymer dissolved in an organic solvent, wherein the water content of said binder is 2-20 wt% based on the total weight of said binder, and said oxidant is capable of converting hydrogen halides into free halogens, wherein... The aqueous solution further contains a phase transfer catalyst.

2. The method according to claim 1, wherein, The oxidizing agents include KHSO5, K2S2O8, KClO, KBrO, KBrO3, KIO3, KClO3, KClO4, KIO4, compounds that produce the potassium salt-based oxidizing agents, or mixtures thereof.

3. The method according to claim 1, wherein, The oxidant includes potassium persulfate.

4. The method according to claim 1, wherein, The oxidant includes KHSO5.

5. The method according to claim 1, wherein, The phase transfer catalyst comprises a molecule having at least seven oxygen atoms, which are capable of forming a complex with potassium ions.

6. The method according to claim 1, wherein, The phase transfer catalyst comprises polyepoxide ether.

7. The method according to claim 1, wherein, The phase transfer catalyst comprises a nonionic surfactant having at least one hydrocarbon chain and 3-20 ethylene oxide units.

8. The method according to claim 1, wherein, The oxidant and phase transfer catalyst are present in the aqueous solution in a molar ratio ranging from 1:3 to 100:

1.

9. The method according to claim 1, wherein, The oxidant and phase transfer catalyst are present in the aqueous solution in a 1:1 molar ratio.

10. The method according to any one of claims 1 to 4, wherein, The unsaturated isoolefin copolymer binder is produced by polymerizing at least one isoolefin monomer and at least one copolymerizable unsaturated monomer in an organic diluent and removing the organic diluent and residual monomer by steam flash separation.

11. The method according to claim 10, wherein, The at least one isoolefin monomer is isobutylene, and the at least one copolymerizable unsaturated monomer is isoprene, p-methylstyrene, or β-pinene.

12. The method of claim 10, wherein the at least one isoolefin monomer is isobutylene and the at least one copolymerizable unsaturated monomer is isoprene, and the unsaturated isoolefin copolymer further comprises one or more additional copolymerizable monomers selected from the group consisting of α-methylstyrene, p-methylstyrene, chlorostyrene, cyclopentadiene, methylcyclopentadiene, and indene.

13. The method according to claim 10, wherein, The organic diluent includes chloromethane.

14. The method according to any one of claims 1 to 4, wherein the halogenating agent is Br2.

15. The method according to any one of claims 1 to 4, wherein, Based on the total weight of the reaction medium, the unsaturated isoolefin copolymer exists in the reaction medium in an amount of 10-33 wt%.

16. The method according to any one of claims 1 to 4, wherein, The contact between the unsaturated isoolefin copolymer binder and the halogenating agent is carried out at a temperature in the range of 20-60°C for 1-60 minutes.

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