Process for producing isoolefin polymers using tertiary ethers

Abstract

The present invention relates to a process for producing isoolefin polymers using tertiary ethers. The process produces isoolefin polymers such as polyisobutene or butyl rubber by polymerizing isobutene and optionally other monomers in the presence of an initiator system comprising at least one boron or aluminum compound and at least one tertiary alkyl ether.

Description

[0001] This application is a divisional application of Chinese patent application No. 201980082982.4, entitled “Method for producing isoolefin polymers using tertiary ethers”, filed on December 16, 2019. Technical Field

[0002] The present invention relates to an efficient process for preparing isoolefin polymers such as polyisobutylene or butyl rubber by polymerizing isobutylene and optionally other monomers in the presence of an initiator system comprising at least one boron or aluminum compound and at least one secondary or tertiary alkyl ether. Background Art

[0003] Polymers containing repeating units derived from isoolefins are prepared industrially by carbocationic polymerization processes. Of particular importance are polyisobutylene and butyl rubber, which are copolymers of isobutylene and small amounts of polyolefins such as isoprene.

[0004] The carbocationic polymerization of isoolefins and their copolymerization with polyolefins is mechanistically complex. The initiator system usually consists of two components: an initiator, and a Lewis acid such as aluminum chloride which is often used in large-scale industrial processes.

[0005] Examples of initiators include proton sources such as hydrogen halides, alcohols, phenols, carboxylic acids and sulfonic acids, and water.

[0006] During the initiation step, the isoolefin reacts with the Lewis acid and the initiator to form a carbenium ion, which further reacts with the monomers to form new carbenium ions in the so-called propagation step.

[0007] The type of monomer, the type and polarity of the diluent or solvent, the polymerization temperature, and the specific combination of Lewis acid and initiator all affect the chain transfer chemistry and, therefore, the incorporation of monomer into the growing polymer chain.

[0008] The widespread use of slurry polymerization processes in methyl chloride as a diluent for the production of polyisobutylene, butyl rubber and other isoolefin polymers is generally accepted by the industry. Generally speaking, the polymerization process is carried out at low temperatures, usually below -90°C. Alkyl chlorides, particularly methyl chloride, are used for a variety of reasons, including that it dissolves the monomers and the aluminum chloride initiator without dissolving the polymer product. Methyl chloride also has suitable freezing and boiling points to allow low temperature polymerization and effective separation of the polymer from unreacted monomers, respectively. Slurry polymerization processes in methyl chloride offer the advantage that polymer concentrations of up to 40 wt% or more can be achieved in the reaction mixture, compared to the maximum 20 wt% polymer concentration that is generally technically feasible in solution polymerization, depending on the target molecular weight. The viscosity of the polymerization solution must be maintained at an acceptably low relative viscosity to allow the heat of polymerization to be removed by heat exchange across the surfaces of the reaction apparatus. Slurry and solution polymerization processes in methyl chloride or alkanes are used to produce high molecular weight polyisobutylene and isobutylene-isoprene butyl rubber polymers.

[0009] Alternatively, aliphatic solvents such as n- and isopentane and hexane and mixtures are used for the polymerization as disclosed, for example, in WO 2010 / 006983 A and WO 2011 / 089092 A, which have significant advantages in downstream processing, for example, chemical modification of the polymer.

[0010] The isoolefin polymers, for example, polyisobutylene or butyl rubber prepared during the polymerization, dissolve in these aliphatic media and these processes are therefore often referred to as solution processes.

[0011] A common feature of both slurry and solution processes is that, due to the high reactivity of the initiators used, temperature control and the avoidance of so-called "hot spots" due to the inhomogeneities of the polymerization medium are difficult, but are crucial to achieve the desired product quality and avoid reactor fouling, i.e. the formation of polymer deposits on the reactor surfaces. Such deposits, due to their insulating effect, reduce the cooling efficiency and can lead to a rapid increase in the temperature within the reactor, thereby increasing the rate of exothermic polymerization and rapidly generating further heat which again cannot be adequately removed. Ultimately, this can even lead to thermal runaway.

[0012] Several attempts have been made in the past to support external or internal cooling in order to maintain the desired (low) temperature within the reactor.

[0013] Other attempts have been made to allow a more evenly distributed heat to be generated during polymerization by replacing the commonly used aluminum and boron initiators with other less reactive initiators or by modifying them with bulky fluorinated substituents. However, these attempts have not been economically feasible.

[0014] Therefore, there remains a need to provide a general process for preparing high quality isoolefin polymers with excellent process control. Summary of the invention

[0015] According to one aspect of the present invention, there is now provided a method for preparing an isoolefin polymer, the method comprising at least the following steps:

[0016] a) providing a reaction medium comprising an organic diluent, at least one monomer which is an isoolefin, and an initiator system, the initiator system comprising

[0017] ● at least one boron or aluminum compound, and

[0018] ●At least one tertiary ether

[0019] and

[0020] b) polymerizing the at least one monomer in a reaction medium in the presence of an initiator system to produce a product medium comprising an isoolefin polymer, an organic diluent and optionally residual monomers. DETAILED DESCRIPTION

[0021] The invention also includes all preferred embodiments, range parameters disclosed below in combination with each other or with the broadest disclosed range or parameter.

[0022] Isoolefins and other monomers

[0023] In step a), a reaction medium is provided comprising an organic diluent, at least one monomer which is an isoolefin and an initiator system.

[0024] As used herein, the term isoolefin refers to a compound containing a carbon-carbon-double bond wherein one carbon atom of the double bond is substituted with two alkyl groups and the other carbon atom is substituted with two hydrogen atoms or with one hydrogen-substituted atom and one alkyl group.

[0025] Examples of suitable isoolefins include isoolefins having 4 to 16 carbon atoms, preferably 4 to 7 carbon atoms, such as isobutylene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene. The preferred olefin is isobutylene.

[0026] The reaction medium may contain other monomers copolymerizable with said at least one isoolefin. Such other monomers include polyolefins.

[0027] As used herein, the term polyene refers to a compound containing more than one conjugated or non-conjugated carbon-carbon-double bond.

[0028] Examples of suitable polyolefins include isoprene, butadiene, 2-methylbutadiene, 2,4-dimethylbutadiene, piperyline, 3-methyl-1,3-pentadiene, 2,4-hexadiene, 2-neopentylbutadiene, 2-methyl-1,5-hexadiene, 2,5-dimethyl-2,4-hexadiene, 2-methyl-1,4-pentadiene, 4-butyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene, 2,3-dibutyl-1,3-pentadiene, 2-ethyl-1,3-pentadiene, 2-ethyl-1,3-butadiene, 2-methyl-1,6-heptadiene, cyclopentadiene, methylcyclopentadiene, cyclohexadiene, and 1-vinyl-cyclohexadiene.

[0029] Preferred polyolefins are isoprene and butadiene. Isoprene is particularly preferred.

[0030] The reaction medium may additionally or alternatively contain other monomers which are copolymerizable with the at least one isoolefin and which are neither isoolefins nor polyolefins. Such other monomers include β-pinene, styrene, divinylbenzene, diisopropenylbenzene, o-, m- and p-alkylstyrenes such as o-, m- and p-methyl-styrene.

[0031] In one embodiment, isobutylene is used as the sole monomer, wherein the term "solely" as used herein means a fraction of 99.9 wt% or more of all monomers used.

[0032] In another embodiment, the monomers used in step a) may comprise 80 wt% to 99.5 wt%, preferably 85 wt% to 98.0 wt%, more preferably 85 wt% to 96.5 wt%, even more preferably 85 wt% to 95.0 wt% of at least one isoolefin and 0.5 wt% to 20 wt%, preferably 2.0 wt% to 15 wt%, more preferably 3.5 wt% to 15 wt%, and still more preferably 5.0 wt% to 15 wt% of at least one multiolefin, based on the sum of the weight of all monomers used.

[0033] In another embodiment, the monomer mixture comprises at least one isoolefin in the range of 90 wt% to 95 wt% and a multiolefin in the range of 5 wt% to 10 wt%, based on the sum of the weights of all monomers used. Still more preferably, the monomer mixture comprises at least one isoolefin in the range of 92 wt% to 94 wt% and at least one multiolefin monomer in the range of 6 wt% to 8 wt%, based on the sum of the weights of all monomers used. The isoolefin is preferably isobutylene, while the multiolefin is preferably isoprene.

[0034] When at least one polyolefin is used in the reaction medium, particularly in the case of isobutylene and isoprene, the polyolefin content of the final copolymer produced is generally 0.1 mol% or more, preferably 0.1 mol% to 15 mol%, in another embodiment, 0.5 mol% or more, preferably 0.5 mol% to 10 mol%, in another embodiment, 0.7 mol% or more, preferably 0.7 mol% to 8.5 mol%, especially 0.8 mol% to 1.5 mol% or 1.5 mol% to 2.5 mol% or 2.5 mol% to 4.5 mol% or 4.5 mol% to 8.5 mol%.

[0035] In another embodiment, particularly when isobutylene and isoprene are used, the copolymers produced according to the present invention have a multiolefin content of 0.1 mol% or more, preferably 0.1 mol% to 3 mol%.

[0036] In one embodiment, the monomers are purified before use in step a), especially when they are recycled from optional step c). The purification of the monomers can be carried out by passing them through an adsorption column containing a suitable molecular sieve or an alumina-based adsorption material. In order to minimize interference with the polymerization reaction, the total concentration of water and substances that act as poisons to the reaction, such as alcohols and other organic oxygenated compounds, is preferably reduced to less than about 10 parts per million by weight.

[0037] Organic diluent

[0038] The term organic diluent encompasses organic chemicals that are diluted or dissolved to be liquid under the reaction conditions.Any suitable organic diluent that does not or will not react to a suitable extent with the monomers or components of the initiator system may be used.

[0039] However, those skilled in the art are aware of the interactions between the diluent and the monomer or initiator system components.

[0040] Furthermore, the term organic diluent includes mixtures of at least two diluents.

[0041] Examples of organic diluents include hydrochlorocarbons, such as methyl chloride, methylene chloride or ethyl chloride.

[0042] Other examples of the organic diluent include hydrofluorocarbons represented by the following formula: x H y F z , wherein x is an integer of 1-40, or 1-30, or 1-20, or 1-10, or 1-6, or 2-20, or 3-10, or 3-6, most preferably 1-3, wherein y and z are integers and are at least 1.

[0043] In one embodiment, the hydrofluorocarbon is selected from the group consisting of: saturated hydrofluorocarbons such as fluoromethane; difluoromethane; trifluoromethane; fluoroethane; 1,1-difluoroethane; 1,2-difluoroethane; 1,1,1-trifluoroethane; 1,1,2-trifluoroethane; 1,1,2,2-tetrafluoroethane; 1,1,1,2,2-pentafluoroethane; 1-fluoropropane; 2-fluoropropane; 1,1-difluoropropane; 1,2-difluoropropane; 1,3-difluoropropane; 2,2-difluoropropane; 1,1,1-trifluoropropane; 1,1,2-trifluoropropane; 1,1,3-trifluoropropane; 1,2,2-trifluoropropane; 1,2,3-trifluoropropane; 1,1,1,2-tetrafluoropropane; 1,1,1,3-tetrafluoropropane; 1, 1,2,2-tetrafluoropropane; 1,1,2,3-tetrafluoropropane; 1,1,3,3-tetrafluoropropane; 1,2,2,3-tetrafluoropropane; 1,1,1,2,2-pentafluoropropane; 1,1,1,2,3-pentafluoropropane; 1,1,1,3,3-pentafluoropropane; 1,1,2,2,3-pentafluoropropane; 1,1,2,3,3-pentafluoropropane ; 1,1,1,2,2,3-hexafluoropropane; 1,1,1,2,3,3-hexafluoropropane; 1,1,1,3,3,3-hexafluoropropane; 1,1,1,2,2,3,3-heptafluoropropane; 1,1,1,2,3,3,3-heptafluoropropane; 1-fluorobutane; 2-fluorobutane; 1,1-difluorobutane; 1,2-difluorobutane; 1,3- Difluorobutane; 1,4-difluorobutane; 2,2-difluorobutane; 2,3-difluorobutane; 1,1,1-trifluorobutane; 1,1,2-trifluorobutane; 1,1,3-trifluorobutane; 1,1,4-trifluorobutane; 1,2,2-trifluorobutane; 1,2,3-trifluorobutane; 1,3,3-trifluorobutane; 2,2,3-trifluorobutane; 1,1, 1,2-tetrafluorobutane; 1,1,1,3-tetrafluorobutane; 1,1,1,4-tetrafluorobutane; 1,1,2,2-tetrafluorobutane; 1,1,2,3-tetrafluorobutane; 1,1,2,4-tetrafluorobutane; 1,1,3,3-tetrafluorobutane; 1,1,3,4-tetrafluorobutane; 1,1,4,4-tetrafluorobutane; 1,2,2,3-tetrafluorobutane 1,2,2,4-tetrafluorobutane; 1,2,3,3-tetrafluorobutane; 1,2,3,4-tetrafluorobutane; 2,2,3,3-tetrafluorobutane; 1,1,1,2,2-pentafluorobutane; 1,1,1,2,3-pentafluorobutane; 1,1,1,2,4-pentafluorobutane; 1,1,1,3,3-pentafluorobutane; 1,1,1,3,4- Pentafluorobutane; 1,1,1,4,4-pentafluorobutane; 1,1,2,2,3-pentafluorobutane; 1,1,2,2,4-pentafluorobutane; 1,1,2,3,3-pentafluorobutane; 1,1,2,4,4-pentafluorobutane; 1,1,3,3,4-pentafluorobutane; 1,2,2,3,3-pentafluorobutane; 1,2,2,3,4-pentafluorobutane;1,1,1,2,2,3-Hexafluorobutane; 1,1,1,2,2,4-Hexafluorobutane; 1,1,1,2,3,3-Hexafluorobutane, 1,1,1,2,3,4-Hexafluorobutane; 1,1,1,2,4,4-Hexafluorobutane; 1,1,1,3,3,4-Hexafluorobutane; 1,1,1,3,4,4-Hexafluorobutane; 1,1,1,4,4,4-Hexafluorobutane; 1,1,2,2,3,3-Hexafluorobutane; 1,1,2,2,3,4-Hexafluorobutane; 1,1,2,2,4,4-Hexafluorobutane; 1,1,2,3,3,4-Hexafluorobutane; 1,1,2,3,4,4-Hexafluorobutane; 1,2,2,3,3,4 Hexafluorobutane; 1,1,1,2,2,3,3-heptafluorobutane; 1,1,1,2,2,4,4-heptafluorobutane; 1,1,1,2,2,3,4-heptafluorobutane; 1,1,1,2,3,3,4-heptafluorobutane; 1,1,1,2,3,4,4-heptafluorobutane; 1,1,1,2,4,4,4-heptafluorobutane; 1,1,1,3,3,4,4-heptafluorobutane; 1,1,1,2,2,3,3,4-octafluorobutane; 1,1,1,2,2,3,4,4-octafluorobutane; 1,1,1,2,3,4 ,4,4-octafluorobutane; 1,1,1,2,2,3,3,4,4-nonafluorobutane; 1,1,1,2,2,3,4,4,4-nonafluorobutane; 1-fluoro-2-methylpropane; 1,1-difluoro-2-methylpropane; 1,3-difluoro-2-methylpropane; 1,1,1-trifluoro-2-methylpropane; 1,1,3-trifluoro-2-methylpropane; 1,3-difluoro-2-(fluoromethyl)propane; 1,1,1,3-tetrafluoro-2-methylpropane; 1,1,3,3-tetrafluoro-2-methylpropane; 1,1,3-trifluoro-2-(fluoromethyl)propane; 1,1,1,3,3-pentafluoro-2-methylpropane; 1,1,3,3-tetrafluoro-2-( 1,1,1,3-tetrafluoro-2-(fluoromethyl)propane; 1,1,1,3-tetrafluoro-2-(fluoromethyl)propane; 1,1-difluorocyclobutane; 1,2-difluorocyclobutane; 1,3-difluorocyclobutane; 1,1,2-trifluorocyclobutane; 1,1,3-trifluorocyclobutane; 1,2,3-trifluorocyclobutane; 1,1,2,2-tetrafluorocyclobutane; 1,1,3,3-tetrafluorocyclobutane; 1,1,2,2,3-pentafluorocyclobutane; 1,1,2,3,3-pentafluorocyclobutane; 1,1,2,2,3,3-hexafluorocyclobutane; 1,1,2,2,3,4-hexafluorocyclobutane; 1,1,2,3,3,4-hexafluorocyclobutane; 1,1,2,2,3,3,4-heptafluorocyclobutane;

[0044] Particularly preferred HFC's include difluoromethane, trifluoromethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, fluoromethane and 1,1,1,2-tetrafluoroethane.

[0045] In a further embodiment, the hydrofluorocarbon is selected from the group consisting of unsaturated hydrofluorocarbons such as vinyl fluoride; 1,2-difluoroethylene; 1,1,2-trifluoroethylene; 1-fluoropropylene; 1,1-difluoropropylene; 1,2-difluoropropylene; 1,3-difluoropropylene; 2,3-difluoropropylene; 3,3-difluoropropylene; 1,1,2-trifluoropropylene; 1,1,3-trifluoropropylene; 1,2,3-trifluoropropylene; 1,3,3-trifluoropropylene; 2,3,3-trifluoropropylene; 3,3,3-trifluoropropylene; 2,3,3,3-tetrafluoro-1-propylene; 1-fluoro-1-butene; 2-fluoro-1-butene; 3-fluoro-1-butene; 4-fluoro-1-butene; 1,1-difluoro-1-butene; 1,2 -difluoro-1-butene; 1,3-difluoropropene; 1,4-difluoro-1-butene; 2,3-difluoro-1-butene; 2,4-difluoro-1-butene; 3,3-difluoro-1-butene; 3,4-difluoro-1-butene; 4,4-difluoro-1-butene; 1,1,2-trifluoro-1-butene; 1,1,3-trifluoro-1-butene; 1,1,4-trifluoro-1-butene; 1,2,3-trifluoro-1-butene; 1,2,4-trifluoro-1-butene; 1,3,3-trifluoro-1-butene; 1,3,4-trifluoro-1-butene; 1,4,4-trifluoro-1-butene; 2,3,3-trifluoro-1-butene; 2,3,4-trifluoro-1-butene; 2,4,4-trifluoro-1-butene; 3,3 ,4-trifluoro-1-butene; 3,4,4-trifluoro-1-butene; 4,4,4-trifluoro-1-butene; 1,1,2,3-tetrafluoro-1-butene; 1,1,2,4-tetrafluoro-1-butene; 1,1,3,3-tetrafluoro-1-butene; 1,1,3,4-tetrafluoro-1-butene; 1,1,4,4-tetrafluoro-1-butene; 1,2, 3,3-tetrafluoro-1-butene; 1,2,3,4-tetrafluoro-1-butene; 1,2,4,4-tetrafluoro-1-butene; 1,3,3,4-tetrafluoro-1-butene; 1,3,4,4-tetrafluoro-1-butene; 1,4,4,4-tetrafluoro-1-butene; 2,3,3,4-tetrafluoro-1-butene; 2,3,4,4-tetrafluoro-1-butene ; 2,4,4,4-tetrafluoro-1-butene; 3,3,4,4-tetrafluoro-1-butene; 3,4,4,4-tetrafluoro-1-butene; 1,1,2,3,3-pentafluoro-1-butene; 1,1,2,3,4-pentafluoro-1-butene; 1,1,2,4,4-pentafluoro-1-butene; 1,1,3,3,4-pentafluoro-1-butene; 1, 1,3,4,4-pentafluoro-1-butene; 1,1,4,4,4-pentafluoro-1-butene; 1,2,3,3,4-pentafluoro-1-butene; 1,2,3,4,4-pentafluoro-1-butene; 1,2,4,4,4-pentafluoro-1-butene; 2,3,3,4,4-pentafluoro-1-butene; 2,3,4,4,4-pentafluoro-1-butene;3,3,4,4,4-pentafluoro-1-butene; 1,1,2,3,3,4-hexafluoro-1-butene; 1,1,2,3,4,4-hexafluoro-1-butene; 1,1,2,4,4,4-hexafluoro-1-butene; 1,2,3,3,4,4-hexafluoro-1-butene; 1,2,3,4,4,4-hexafluoro-1-butene; 2,3,3,4,4,4-hexafluoro-1-butene; 1,1,2,3,3,4,4-hexafluoro-1-butene; 1,1,2,3,3,4,4-hexafluoro-1-butene; 1,1,2,3,4,4,4-hexafluoro-1-butene; ,3,3,4,4,4-heptafluoro-1-butene; 1,2,3,3,4,4,4-heptafluoro-1-butene; 1-fluoro-2-butene; 2-fluoro-2-butene; 1,1-difluoro-2-butene; 1,2-difluoro-2-butene; 1,3-difluoro-2-butene; 1,4-difluoro-2-butene; 2,3-difluoro-2-butene; 1,1,1-trifluoro-2-butene; 1,1,2-trifluoro-2-butene; 1,1,3-trifluoro-2-butene; 1,1,4-trifluoro-2-butene; 1,2,3-trifluoro-2- Butene; 1,2,4-trifluoro-2-butene; 1,1,1,2-tetrafluoro-2-butene; 1,1,1,3-tetrafluoro-2-butene; 1,1,1,4-tetrafluoro-2-butene; 1,1,2,3-tetrafluoro-2-butene; 1,1,2,4-tetrafluoro-2-butene; 1,2,3,4-tetrafluoro-2-butene; 1,1,1,2,3-pentafluoro-2-butene; 1,1,1,2,4-pentafluoro-2-butene; 1,1,1,3,4-pentafluoro-2-butene; 1,1,1,4,4-pentafluoro-2-butene; 1,1,2,3,4-pentafluoro-2-butene; 1,1,2,4,4-pentafluoro-2-butene; 1,1,1,2,3,4-hexafluoro-2-butene; 1,1,1,2,4,4-hexafluoro-2-butene; 1,1,1,3,4,4-hexafluoro-2-butene; 1,1,1,4,4,4-hexafluoro-2-butene; 1,1,2,3,4,4-hexafluoro-2-butene; 1,1,1,2,3,4,4-hexafluoro-2-butene; 1,1,1,2,3,4,4-hexafluoro-2-butene; 1,1,1,2,4,4,4-heptafluoro-2-butene; and mixtures thereof. ;

[0046] Further examples of organic diluents include hydrochlorofluorocarbons.

[0047] Further examples of organic diluents include hydrocarbons, preferably alkanes, which in a further preferred embodiment are selected from n-butane, isobutane, n-pentane, methylcyclopentane, isohexane, 2-methylpentane, 3-methylpentane, 2-methylbutane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methylhexane, 3-methylhexane, 3-ethylpentane, 2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, 3,3-dimethyl ...3-dimethylpentane, 2,3-dimethylpentane, 2,3-dimethylpentane, 2,3-dimethylpentane, 2,3-dimethylpentane, 2,3-dimethylpentane, 2,3-dimethylpentane, 2,3- those in the group consisting of 2,5-dimethylhexane, 2,2,4-trimethylpentane, octane, heptane, butane, nonane, decane, dodecane, undecane, hexane, methylcyclohexane, cyclopentane, methylcyclopentane, 1,1-dimethylcyclopentane, cis-1,2-dimethylcyclopentane, trans-1,2-dimethylcyclopentane, trans-1,3-dimethyl-cyclopentane, ethylcyclopentane, cyclohexane, methylcyclohexane.

[0048] Other examples of hydrocarbon diluents include benzene, toluene, xylene, ortho-xylene, para-xylene, and meta-xylene.

[0049] Suitable organic diluents also include mixtures of at least two compounds selected from the group consisting of hydrochlorocarbons, hydrofluorocarbons, hydrochlorofluorocarbons and hydrocarbons. Specific combinations include mixtures of hydrochlorocarbons and hydrofluorocarbons, such as mixtures of methyl chloride and 1,1,1,2-tetrafluoroethane, especially mixtures of 40vol%-60vol% methyl chloride and 40vol%-60vol% 1,1,1,2-tetrafluoroethane, whereby the sum of the two aforementioned diluents is 90vol%-100vol%, preferably 95vol%-100vol% of the total diluent, whereby the potential remainder to 100vol% includes other halogenated hydrocarbons; or mixtures of methyl chloride and at least one alkane or alkane mixture, such as mixtures of alkane mixtures containing at least 90wt%, preferably 95wt% of alkanes having a boiling point of -5°C-100°C or 35-85°C at a pressure of 1013hPa. In another embodiment, at least 99.9 wt%, preferably 100 wt% of the alkanes have a boiling point of 100°C or lower, preferably in the range of 35-100°C, more preferably 90°C or lower, even more preferably in the range of 35-90°C at a pressure of 1013 hPa.

[0050] Depending on the nature of the polymerization intended for step b), the organic diluent is chosen so as to allow a slurry polymerization or a solution polymerization.

[0051] Initiator system

[0052] The monomers in the reaction medium are polymerized in the presence of the initiator system to form a product medium comprising the isoolefin polymer, an organic diluent and optionally residual monomers.

[0053] The initiation system includes

[0054] ● at least one boron or aluminum compound, and

[0055] ●At least one tertiary ether

[0056] Optionally there is

[0057] ●At least one other activating compound

[0058] Suitable boron or aluminum compounds are those represented by the formula MX3, wherein M is boron or aluminum and X is a halogen. Examples of such compounds include aluminum trichloride, aluminum tribromide, boron trifluoride, boron trichloride and boron tribromide, with aluminum trichloride being preferred.

[0059] Other suitable boron or aluminum compounds are of the formula MR (m) X (3-m) Those represented by, wherein M is boron or aluminum, X is halogen, and R is selected from C1-C 12 Alkyl and C7-C 14 and m is 1 or 2. The term "alkaryl" refers to a group containing aliphatic and aromatic structures, the group being located at the aliphatic position.

[0060] Examples of such compounds include methylaluminum dibromide, methylaluminum dichloride, ethylaluminum dibromide, ethylaluminum dichloride, butylaluminum dibromide, butylaluminum dichloride, dimethylaluminum bromide, dimethylaluminum chloride, diethylaluminum bromide, diethylaluminum chloride, dibutylaluminum bromide, dibutylaluminum chloride, methylaluminum sesquibromide, methylaluminum sesquichloride, ethylaluminum sesquibromide, and ethylaluminum sesquichloride.

[0061] Preferred are diethylaluminum chloride (Et2AlCl or DEAC), ethylaluminum sesquichloride (Et 1.5 AlCl 1.5 or EASC), ethylaluminum dichloride (EtAlCl2 or EADC), diethylaluminum bromide (Et2AlBr or DEAB), ethylaluminum sesquibromide (Et 1.5 ABr 1.5 or EASB) and ethylaluminum dibromide (EtAlBr2 or EADB).

[0062] A particularly preferred aluminum compound is aluminum trichloride.

[0063] Ethers

[0064] As used herein, tertiary ethers are those which carry at least one tertiary alkyl or tertiary aralkyl group, preferably only one tertiary alkyl or tertiary aralkylaryl group, at the ether oxygen.

[0065] Preferred tertiary alkyl groups include tert-butyl and tert-amyl.

[0066] Preferred tertiary arylalkylaryl groups include cumyl.

[0067] Examples of tert-alkyl ethers include methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), methyl tert-amyl ether (MTAE) and phenyl tert-butyl ether (PTBE) or mixtures thereof, wherein methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), methyl tert-amyl ether (MTAE) or mixtures thereof are preferred, and thus methyl tert-butyl ether (MTBE) is more preferred.

[0068] Other activating compounds suitable for use in the present invention are selected from those capable of reacting with the selected boron or aluminum compound to form a complex which reacts with the monomer to form a growing polymer chain.

[0069] In a preferred embodiment, such activating compound is selected from the group consisting of water, alcohols, phenols, hydrogen halides, carboxylic acids, acyl halides, carboxylic acid esters, carboxylic acid amides, sulfonic acids, sulfonyl halides, alkyl halides, alkylaryl halides and polymeric halides.

[0070] Preferred alcohols include methanol, ethanol, propanol, 2-propanol, 2-methylpropan-2-ol, cyclohexanol and benzyl alcohol.

[0071] Preferred phenols include phenol; 2-methylphenol; 2,6-dimethylphenol; p-chlorophenol; p-fluorophenol; 2,3,4,5,6-pentafluorophenol; and 2-hydroxynaphthalene.

[0072] Preferred hydrogen halides include hydrogen chloride, hydrogen bromide and hydrogen iodide. A particularly preferred hydrogen halide is hydrogen chloride.

[0073] Preferred carboxylic acids include aliphatic carboxylic acids and aromatic carboxylic acids. Examples of carboxylic acids suitable for use in the present invention include acetic acid, propionic acid, butyric acid; cinnamic acid, benzoic acid, 1-chloroacetic acid, dichloroacetic acid, trichloroacetic acid, trifluoroacetic acid, p-chlorobenzoic acid and p-fluorobenzoic acid. Particularly preferred carboxylic acids include trichloroacetic acid, trifluoroacetic acid and p-fluorobenzoic acid.

[0074] The acyl halide applicable to the present invention is similar in structure to the carboxylic acid except that the OH group of the acid is replaced by a halide. The halide may be a fluoride, chloride, bromide or iodide, preferably a chloride.

[0075] Suitable acyl halides for the present invention include acetyl chloride, acetyl bromide, cinnamoyl chloride, benzoyl chloride, benzoyl bromide, trichloroacetyl chloride, trifluoroacetyl chloride, trifluoroacetyl chloride and p-fluorobenzoyl chloride. Particularly preferred acyl halides include acetyl chloride, acetyl bromide, trichloroacetyl chloride, trifluoroacetyl chloride and p-fluorobenzoyl chloride.

[0076] Carboxylic acid esters include methyl acetate, ethyl acetate, vinyl acetate, propyl acetate, allyl acetate, benzyl acetate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, dimethyl maleate, diethyl maleate, dipropyl maleate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, allyl benzoate, butyl benzoate, benzyl benzoate, phenylethyl benzoate, dimethyl phthalate, diethyl phthalate, dipropyl phthalate, dibutyl phthalate, dipentyl phthalate, dihexyl phthalate, diheptyl phthalate, and dioctyl phthalate.

[0077] Carboxylic acid amides include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide and N,N-diethylacetamide. Preferred tertiary alkyl and aralkyl initiators include tertiary compounds represented by the following formula: wherein X is a halogen, pseudohalogen, ether or ester, or a mixture thereof, preferably a halogen, preferably a chloride, and R1, R2 and R3 are independently any linear, cyclic or branched alkyl, aryl or aralkyl, preferably containing 1-15 carbon atoms and more preferably 1-8 carbon atoms. n is the number of initiator sites and is a number greater than or equal to 1, preferably a number from 1 to 30, more preferably n is a number from 1 to 6. Aralkyl groups may be substituted or unsubstituted. For the purposes of the present invention, aralkyl groups are defined to refer to compounds containing aromatic and aliphatic structures. Preferred examples of the initiator include 2-chloro-2,4,4-trimethylpentane; 2-bromo-2,4,4-trimethylpentane; 2-chloro-2-methylpropane; 2-bromo-2-methylpropane; 2-chloro-2,4,4,6,6-pentamethylheptane; 2-bromo-2,4,4,6,6-pentamethylheptane; 1-chloro-1-methylethylbenzene; 1-chloroadamantane; 1-chloroethylbenzene; 1,4-bis(1-chloro-1-methylethyl )benzene; 5-tert-butyl-1,3-bis(1-chloro-1-methylethyl)benzene; 2-acetoxy-2,4,4-trimethylpentane; 2-benzoyloxy-2,4,4-trimethylpentane; 2-acetoxy-2-methylpropane; 2-benzoyloxy-2-methylpropane; 2-acetoxy-2,4,4,6,6-pentamethylheptane; 2-benzoyl-2,4,4,6,6-pentamethylheptane; 1-ethyl Acyloxy-1-methylethylbenzene; 1-acetoxyadamantane; 1-benzoyloxyethylbenzene; 1,4-bis(1-acetoxy-1-methylethyl)benzene; 5-tert-butyl-1,3-bis(1-acetoxy-1-methylethyl)benzene; 2-methoxy-2,4,4-trimethylpentane; 2-isopropoxy-2,4,4-trimethylpentane; 2-methoxy-2-methylpropane; 2-benzyloxy-2-methylpropane ; 2-methoxy-2,4,4,6,6-pentamethylheptane; 2-isopropoxy-2,4,4,6,6-pentamethylheptane; 1-methoxy-1-methylethylbenzene; 1-methoxyadamantane; 1-methoxyethylbenzene; 1,4-bis(1-methoxy-1-methylethyl)benzene; 5-tert-butyl-1,3-bis(1-methoxy-1-methylethyl)benzene and 1,3,5-tris(1-chloro-1-methylethyl)benzene.

[0078] The sulfonic acid used as the initiator in the present invention includes aliphatic and aromatic sulfonic acids. Examples of preferred sulfonic acids include methanesulfonic acid, trifluoromethanesulfonic acid, trichloromethanesulfonic acid and p-toluenesulfonic acid.

[0079] The sulfonyl halides suitable for use in the present invention are similar in structure to sulfonic acid, except that the OH of the parent acid is replaced by a halide. The halide can be a fluoride, chloride, bromide or iodide, and chloride is preferred. It is known in the prior art to prepare sulfonyl halides from parent sulfonic acid, and those skilled in the art should be familiar with these procedures. Preferred sulfonyl halides suitable for use in the present invention include methanesulfonyl chloride, methanesulfonyl bromide, trichloromethanesulfonyl chloride, trifluoromethanesulfonyl chloride and p-toluenesulfonyl chloride.

[0080] Suitable alkyl halides for use in the present invention include 2-chloro-2,4,4-trimethylpentane and 2-chloro-2-methylpropane.

[0081] Alkaryl halides suitable for use in the present invention include 1-chloro-1-methylethylbenzene.

[0082] Polymeric halides useful in the present invention include those having at least two halogenated tertiary carbons located at the polymer chain ends or along or within the polymer backbone.

[0083] The preferred molar ratio of the tertiary ether to the sum of the boron and aluminum atoms of the boron or aluminum compound used is usually 0.001 to 0.500, preferably 0.005 to 0.500, more preferably 0.001 to 0.200, still more preferably 0.002 to 0.200.

[0084] Preferably, the initiator system comprising a Lewis acid and an initiator is present in the reaction mixture in an amount of 0.002 wt% to 5.0 wt%, preferably 0.1 wt% to 0.5 wt%, based on the weight of the monomers used.

[0085] In another embodiment, in particular in the case of using aluminum chloride, the weight ratio of the monomer used to the boron or aluminum compound, in particular aluminum chloride, is in the range of 500-20,000, preferably 1,500-10,000.

[0086] In a particularly preferred initiator system, the boron or aluminum compound is ethylaluminum sesquichloride, preferably produced by mixing equimolar amounts of diethylaluminum chloride and ethylaluminum dichloride, preferably in an organic diluent. The organic diluent is preferably the same as the organic diluent used for the polymerization in step b).

[0087] The above-described initiator systems are also encompassed by the present invention whether or not combined with an organic diluent.

[0088] In one embodiment, water is additionally used as a further activating compound. In this embodiment, in particular when using the formula MR as described above (m) X (3-m)In the case of boron or aluminum compounds, the amount of water is in the range of 0.1-4.0 mol water / mol boron or aluminum compound, preferably 0.2-2 mol water / mol boron or aluminum compound, most preferably 0.5-1 mol water / mol boron or aluminum compound.

[0089] In one embodiment, in case an aluminum halide, in particular aluminum trichloride, is used as the boron or aluminum compound, water and / or an alcohol, preferably water, is used as a further activating compound.

[0090] Reaction medium

[0091] The monomer may be present in the reaction medium in an amount of 0.01 wt% to 80 wt%, preferably 0.1 wt% to 65 wt%, more preferably 10.0 wt% to 65.0 wt%, still more preferably 25.0 wt% to 65.0 wt%, or in another embodiment 5.0 wt% to 55.0 wt%.

[0092] The organic diluent may be present in the reaction medium in an amount of 0.01 wt% to 80 wt%, preferably 0.1 wt% to 65 wt%, more preferably 10.0 wt% to 65.0 wt%, still more preferably 25.0 wt% to 65.0 wt%, or in another embodiment 10.0 wt% to 40.0 wt%.

[0093] The amounts of organic diluent, monomer and initiator system are chosen so that they constitute at least 95 wt%, preferably 97 wt% to 100 wt%, more preferably 99 wt% to 100 wt% of the reaction medium used in step b).

[0094] The remainder making up to 100% may, if present, comprise other organic or inorganic compounds, preferably those which do not substantially affect the polymerization reaction.

[0095] In one embodiment, the reaction medium comprises 10.0wt%-65.0wt% of monomer, 20.0wt%-89.9wt% of organic diluent and 0.1wt%-15.0wt% of carbon dioxide, whereby the amount of organic diluent, monomer and carbon dioxide is selected so that they constitute at least 95wt% of the reaction medium, preferably 97wt%-100wt%, more preferably 99wt%-100wt%. From the perspective of throughput and efficiency, it is desirable to increase the concentration of monomer relative to diluent, i.e., the reactive portion of the reaction medium relative to the non-reactive portion. However, this has the side effect of increasing the heat load of the reactor, potentially greatly exceeding its ability to remove the heat of reaction. In addition to reducing the performance of the reactor, this can also lead to adverse effects on product performance, including but not limited to the molecular weight distribution of the polymer.

[0096] Aggregation conditions

[0097] In one embodiment, the organic diluent and monomer used are substantially free of water. As used herein, substantially free of water is defined as less than 30 ppm, preferably less than 20 ppm, more preferably less than 10 ppm, even more preferably less than 5 ppm, and most preferably less than 1 ppm based on the total weight of the reaction medium.

[0098] It is known to those skilled in the art that the water content in the diluent and the monomers needs to be low to ensure that the initiator system is not affected by additional amounts of water which is not added for the purpose of, for example, acting as an initiator.

[0099] Steps a) and b) can each be carried out in a continuous or batchwise process, whereby continuous operation is preferred. In general, providing the reaction medium in step a) and initiating the polymerization in b) can be effected simultaneously.

[0100] In one embodiment of the invention, the polymerization according to step b) is carried out using a polymerization reactor. Suitable reactors are those known to those skilled in the art and include flow-through polymerization reactors, plug flow reactors, stirred tank reactors, moving belt or drum reactors, jet or nozzle reactors, tubular reactors and autorefrigeration boiling pool reactors. Specific suitable examples are disclosed in WO 2011 / 000922A and WO 2012 / 089823A.

[0101] Depending on the choice of the organic diluent, the polymerization according to step b) is carried out as a slurry polymerization or as a solution polymerization.

[0102] In a slurry polymerization, the monomers and initiator system are generally soluble in the diluent or diluent mixture, i.e., constitute a single phase, and the copolymer precipitates from the organic diluent as it is formed. Ideally, reduced or absent polymer "swelling" is manifested by little or no suppression of the polymer Tg and / or little or no organic diluent mass absorption.

[0103] In solution polymerization, the monomers, initiator system are usually soluble in the diluent or diluent mixture, ie constitute a single phase as do the copolymers formed during the polymerization.

[0104] The solubility of the desired polymers in the abovementioned organic diluents as well as their swelling behavior under the reaction conditions are well known to the person skilled in the art.

[0105] The advantages and disadvantages of solution polymerization over slurry polymerization are extensively discussed in the literature and are therefore known to those skilled in the art.

[0106] Step b) is preferably carried out as a slurry process.

[0107] In one embodiment, step b) is carried out at a temperature in the range of -100°C to -60°C, preferably in the range of -98°C to -80°C, more preferably in the range of -97°C to -90°C.

[0108] The reaction pressure in step b) is generally 500-100,000 hPa, preferably 1100-20,000 hPa, more preferably 1300-5,000 hPa.

[0109] When the polymerization according to step b) is carried out as a slurry process, the solids content of the slurry in step b) is preferably in the range of 1 wt%-45 wt%, more preferably in the range of 3 wt%-40 wt%, even more preferably in the range of 15 wt%-40 wt%.

[0110] As used herein, the term "solids content" or "solids level" refers to the weight percentage of isoolefin polymer in the product medium comprising isoolefin polymer, organic diluent and optionally residual monomers obtained according to step b).

[0111] In one embodiment, the reaction time in step b) is 2 minutes to 2 hours, preferably 10 minutes to 1 hour, and more preferably 20-45 minutes.

[0112] The process can be carried out batchwise or continuously. When a continuous reaction is carried out, the reaction times given above represent average residence times.

[0113] In one embodiment, the reaction is terminated by a quencher, for example, a 1 wt % solution of sodium hydroxide in water, methanol or ethanol.

[0114] In another embodiment, the reaction is quenched by contacting with an aqueous medium in step c), which in one embodiment may have a pH value of 5-11, preferably 6-10, more preferably 8-9 measured at 20°C and 1013 hPa.

[0115] If necessary, the pH can be adjusted by adding acids or basic compounds which preferably do not contain polyvalent metal ions. The pH is adjusted to higher pH values, for example, by adding sodium hydroxide or potassium hydroxide.

[0116] Specifically, for solution polymerization, the conversion is usually stopped after the monomer consumption is 5 wt% to 25 wt%, preferably 10 wt% to 20 wt%, of the monomer initially used.

[0117] Monomer conversion can be followed by online viscometry or spectroscopic monitoring during polymerization.

[0118] In one embodiment, in optional step c), particularly in the case where step b) is implemented as a slurry process, the product medium obtained in step b) is contacted with an aqueous medium and the organic diluent is at least partially removed and to the extent that the residual monomers and carbon dioxide are removed at least partially to obtain an aqueous slurry containing the isoolefin polymer in the form of fine particles, commonly referred to as rubber crumb, present in the medium. The contacting can be carried out in any container suitable for this purpose and can be carried out intermittently or continuously, whereby a continuous process is preferred. In industry, such contacting is usually carried out in a stripping tower, a flash tank or any other container known to be used for separating liquid phase and steam.

[0119] The removal of organic diluent and optional monomers may also employ other types of distillation, so that residual monomers and organic diluents are subsequently or jointly removed to the desired extent. Distillation methods for separating liquids of different boiling points are well known in the art and are described, for example, in Encyclopedia of Chemical Technology, Kirk Othmer, 4th edition, pp. 8-311, which is incorporated herein by reference. In general, unreacted monomers and diluents may be recycled individually or together to step a) of the process according to the invention.

[0120] The pressure in optional step c) and in one embodiment in the stripping column or flash tank depends on the organic diluent and the monomers used in step b).

[0121] The temperature in optional step c) is chosen to be sufficient to at least partially remove the organic diluent to such an extent that residual monomers are still present.

[0122] The organic diluent and / or monomer removed in step c) can be recycled once again into step a) and / or b).

[0123] In one embodiment, the temperature is 10-100°C, preferably 50-100°C, more preferably 60-95°C, even more preferably 75-95°C.

[0124] In case step b) is carried out as a solution polymerization in contact with water, then the organic diluent is evaporated and the isoolefin polymer forms discrete particles suspended in the aqueous slurry.

[0125] In a further optional step d), the isoolefin polymer may be obtained by isolating the isoolefin polymer contained in the aqueous slurry obtained according to step c).

[0126] The separation can be carried out by flotation, centrifugation, filtration, dewatering in a dewatering extruder or by any other means known to those skilled in the art for separating solids from fluids.

[0127] In a further optional step e), the isoolefin polymer particles obtained according to step d) are dried, preferably to a residual content of volatiles of 7,000 or less, preferably 5,000 or less, more preferably 4,000 or less, and in another embodiment 2,000 ppm or less, preferably 1,000 ppm or less.

[0128] As used herein, the term volatiles refers to compounds having a boiling point below 250°C, preferably 200°C or less, at standard pressure, and includes water and other organic diluents.

[0129] Drying can be carried out using conventional means known to those skilled in the art, including drying on a heated mesh conveyor belt or in an extruder.

[0130] Surprisingly, it has been discovered that isoolefin polymers prepared in accordance with the present invention, particularly when isobutylene and isoprene are used as monomers, commonly referred to as butyl rubber, exhibit a unique microstructure.

[0131] When isoprene is incorporated into the isobutylene backbone, this incorporation occurs primarily in two different ways, resulting in two different structures.

[0132] One structure is the so-called 1,4-isoprene structure

[0133] 1,4-Isoprene

[0134] Another structure is a branched structure

[0135] Branched

[0136] A suitable method for distinguishing these structures is nuclear magnetic resonance (NMR) spectroscopy. The proton NMR spectrum contains peaks that can be assigned to each of the above structures. The integration of these peak areas gives the results of the molar percentages that can be converted to each structure.

[0137] A maximum level of 1,4-isoprene is desirable because it allows the isoolefin polymer to be more readily cured or otherwise chemically modified, such as halogenated to chloroprene and bromobutyl rubbers.

[0138] However, the typical molar ratio of 1,4-isoprene structures to branched structures of known and commercial butyl rubbers is 8.0-12.5. Surprisingly, the butyl rubbers obtainable according to the above process have said ratio of 14.0-20.0, preferably 14.0-17.0, and thus move into a more ideal range than previously known.

[0139] A further surprising effect of the process according to the invention is that the formation of harmful by-products is reduced to a minimum.

[0140] Whether the polymerization is carried out as a slurry process or a solution process, the cyclic oligomer 1-isopropenyl-2,2,4,4-tetramethylcyclohexane (hereinafter referred to as C 13 ) and 1,1,5,5-tetramethyl-2-(1-methylvinyl)-3-(2,2,4-trimethylpentyl)-cyclohexane (hereinafter referred to as C 21 ) is produced as a by-product and remains in butyl rubber in amounts ranging from 1000 to up to 2500 ppm depending on the commercial source.

[0141]

[0142] These cyclic oligomers are undesirable in certain applications, for example, in pharmaceutical seals, closures, blood draw stops, medical devices, and food grade applications, because these cyclic oligomers have the potential to migrate into / into the drug or food and then interact or react with the product and / or be introduced into the patient. Therefore, reducing the level of cyclic oligomers in butyl rubber, especially where subsequent halogenation is contemplated, is highly desirable, as halogenated oligomers are more of a concern due to their reactivity.

[0143] It has been found that according to the process of the invention, in particular after carrying out step c) or optionally also step d), C 13 and C 21 The sum of is usually less than 800 ppm, preferably 50-800 ppm, and more preferably 200-700 ppm.

[0144] Butyl rubber C 13 The content is usually less than 350 ppm, preferably 20-300 ppm, and more preferably 50-300 ppm.

[0145] Butyl rubber C 21 The content is usually less than 450 ppm, preferably 30-450 ppm, and more preferably 50-400 ppm.

[0146] Butyl rubber C 21 With C 13The weight ratio is generally between 0.9 and 2.0, preferably between 1.2 and 2.0, while for known butyl rubbers from different commercial sources, this ratio is generally between 2.3 and 4.0.

[0147] Preferred butyl rubbers according to the present invention are those already covered in the process section above and include c-butyl rubbers comprising repeating units derived from isobutylene and isoprene.

[0148] Generally speaking, the isoprene content of the butyl rubber according to the present invention is 0.1 mol% or more, preferably 0.1 mol%-15 mol%, in another embodiment 0.5 mol% or more, preferably 0.5 mol%-10 mol%, in another embodiment 0.7 mol% or more, preferably 0.7 mol%-8.5 mol%, especially 0.8 mol%-2.0 mol% or 1.5 mol%-2.5 mol% or 2.5 mol%-4.5 mol% or 4.5 mol%-8.5 mol%.

[0149] In another embodiment, the isoprene content of the butyl rubber according to the present invention is 0.001 mol% or more, preferably 0.001 mol% to 3 mol%, preferably 0.8 mol% to 3 mol%.

[0150] In one embodiment, the weight average molecular weight of the butyl rubber according to the present invention is in the range of 10-2,000 kg / mol, preferably in the range of 20-1,000 kg / mol, more preferably in the range of 50-1,000 kg / mol, even more preferably in the range of 200-800 kg / mol, still more preferably in the range of 375-550 kg / mol, and most preferably in the range of 400-500 kg / mol. If not mentioned otherwise, the molecular weight is obtained using gel permeation chromatography in tetrahydrofuran (THF) solution using polystyrene molecular weight standards.

[0151] In one embodiment, the polydispersity of the butyl rubber according to the invention is in the range of 1.5-4.5, preferably in the range of 2.5-3.5, as measured by the ratio of the weight average molecular weight to the number average molecular weight determined by gel permeation chromatography.

[0152] The butyl rubber according to the present invention for example and usually has a Mooney viscosity of at least 10 (ML 1+8, 125° C., ASTM D 1646), preferably 10-80, more preferably 20-80, and even more preferably 25-60 (ML 1+8, 125° C., ASTM D 1646).

[0153] In one embodiment, the butyl rubber according to the present invention has an ash content of 0.25 wt% or less, preferably 0.15 wt% or less, more preferably 0.10 wt% or less and still more preferably 0.05 wt% or less, measured according to ASTM D5667.

[0154] Rubber products

[0155] The one or more butyl rubbers according to the invention may be blended with one another or additionally or alternatively with at least one secondary rubber, preferably selected from the group consisting of natural rubber (NR), epoxidized natural rubber (ENR), polyisoprene rubber, polyisobutylene rubber, poly(styrene-co-butadiene) rubber (SBR), chloroprene rubber (CR), polybutadiene rubber (BR), perfluoroelastomers (FFKM / FFPM), ethylene vinyl acetate (EVA) rubber, ethylene acrylate rubber, polysulfide rubber (TR), poly(isoprene-co-butadiene) rubber (IBR), styrene-isoprene-butadiene rubber (SIBR), ethylene propylene rubber (EPR), ethylene-propylene-diene M-grade rubber (EPDM), polyphenylene sulfide, nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), propylene oxide polymers, star-branched butyl rubbers and halogenated star-branched butyl rubbers, butyl rubbers which are not the subject of the present invention (i.e., having different level of polyvalent metal ions or purity grades), brominated butyl rubber and chlorinated butyl rubber, star-branched polyisobutylene rubber, star-branched brominated butyl (polyisobutylene / isoprene copolymer) rubber; poly(isobutylene-co-p-methylstyrene) and halogenated poly(isobutylene-co-p-methylstyrene), halogenated poly(isobutylene-co-isoprene-co-p-methylstyrene), poly(isobutylene-co-isoprene-co-styrene), halogenated poly(isobutylene-co-isoprene-co-styrene), poly(isobutylene-co-isoprene-co-α-methylstyrene), halogenated poly(isobutylene-co-isoprene-co-α-methylstyrene).

[0156] One or more butyl rubbers according to the present invention or their blends with the above-mentioned secondary rubbers can additionally or alternatively, for example, simultaneously or separately, be further blended with at least one thermoplastic polymer, preferably selected from the group consisting of polyurethane (PU), polyacrylate (ACM, PMMA), thermoplastic polyester polyurethane (AU), thermoplastic polyether polyurethane (EU), perfluoroalkoxyalkane (PFA), polytetrafluoroethylene (PTFE) and polytetrafluoroethylene (PTFE).

[0157] The butyl rubber according to the invention or its blend with the secondary rubber and / or thermoplastic polymer may or may not contain other components commonly used in the rubber industry, such as fillers and curing agents. They are usually compounded with one or more fillers, and all of them are collectively referred to as rubber products below.

[0158] application

[0159] The rubber products according to the present invention are very useful in a wide range of applications. Low permeability to gases, unsaturated sites that can be used as modification sites for crosslinking, curing or polymerization, and their low level of interfering additives are the greatest uses of these rubber products.

[0160] Therefore, the present invention also covers the use of the rubber product according to the present invention for liners, air bags, catheters, air cushions, pneumatic springs, bellows, accumulator bags, hoses, conveyor belts and drug closures. The present invention also covers the above products containing the rubber product according to the present invention, whether cured or / uncured.

[0161] The rubber product according to the present invention also exhibits high damping and has a uniquely wide damping and shock absorption range in both temperature and frequency.

[0162] Therefore, the present invention also covers the use of the rubber product according to the present invention in automobile suspension bumpers, automobile exhaust hangers, body brackets and shoe soles.

[0163] The rubber product of the present invention can also be used in tire sidewall and tread compounds. In the sidewall, the butyl rubber properties impart good ozone resistance, crack cut growth and appearance.

[0164] The rubber products according to the present invention can be formed into desired articles before curing. Articles containing cured butyl rubber according to the present invention include, for example, belts, hoses, shoe soles, gaskets, O-rings, wires / cables, films, rollers, air bags (e.g., cured air bags), tire liners, tire treads, shock absorbers, mechanical devices, balloons, balls, golf balls, protective clothing, medical catheters, tank liners, electrical insulation materials, bearings, medical plugs, adhesives, containers (e.g., bottles, totes, tanks, etc.); container closures or lids; seals or sealants, such as gaskets or caulking compounds; material handling apparatus, such as auger or conveyor belts; power belts, cooling towers; metalworking equipment, or any equipment that comes in contact with metalworking fluids; engine components, such as fuel lines, fuel filters, fuel tanks, gaskets, seals, etc.; membranes for fluid filtration or tank sealing.

[0165] The present invention is further illustrated hereinafter by examples, but is not limited thereto.

[0166] Experimental part:

[0167] X.1 Batch Polymerization

[0168] The polymerization was carried out in an MBraun MB-200G glove box equipped with a pentane cooling bath, reactor and bath temperature recorder. Isoprene (>99%) was purchased from Sigma-Aldrich and further purified by drying with CaH2 under nitrogen atmosphere for 24 h, then distilled with CaH2 under nitrogen into an oven-dried receiving bottle and then transferred to the glove box and stored at -2°C until use. Methyl tert-butyl ether (MTBE, anhydrous, 99.8%) was dried over 3A molecular sieves before use. AlCl3 (99.99%) was purchased from Sigma Aldrich and used as received.

[0169] Example 1 AlCl3: Preparation of initiator solution

[0170] Fresh AlCl3 initiator solution was prepared every day and used for all experiments performed on the same day. In a glove box, AlCl3 (0.30 g, 2.25 mmol) dissolved in MeCl (100 mL) was loaded into a 100 mL Erlenmeyer flask and cooled to -30 ° C. A mechanical stirrer was used to stir the solution at 450 rpm for 30 minutes at -30 ° C. Stirring was stopped, the flask was sealed, and the solution was cooled to -95 ° C until use.

[0171] Example 2: General Slurry Polymerization Procedure

[0172] A 500mL stainless steel beaker equipped with a temperature probe is placed in a pentane bath cooled to -95°C and pre-cooled methyl chloride (MeCl, 180mL) is loaded. Isobutylene (20mL, 14.24g, 25.0mmol) is condensed into a pre-cooled measuring cylinder as a liquid and transferred to the reaction flask. Isoprene (0.8mL, 0.54g, 7.92mmol) is transferred to the reaction by a pipette. The solution is mechanically stirred at 800rpm until the temperature stabilizes. The pre-prepared AlCl3 initiator solution (3mL, 0.0090g, 0.0675mmol) is transferred to the reaction by a pre-cooled pipette to initiate the reaction. Unless otherwise stated, polymerization is stirred at 800rpm for 5 minutes. The polymerization is terminated by adding NaOH (1.0mL, 1wt%, 0.01mmol) ethanol solution. The polymer cement was taken out from the glove box, diluted with hexane (about 300 mL) and antioxidant (1.0 mL, 1 wt% Irganox 1076 in hexane), and left to stand overnight in a fume hood to remove volatiles. The cement was solidified with ethanol (about 500-1000 mL), and the resulting polymer (7.9800 g, 53.7%) was collected and dried in a vacuum oven at 60° C. for 48 hours. The conversion was determined by gravimetric analysis. The initiator efficiency was calculated to be 887 g polymer / g AlCl3. The results are shown in Table 1.

[0173] Table 1: Slurry Polymerization without MTBE

[0174]

[0175]

[0176] Example 3: Preparation of MTBE solution

[0177] A 100 mL conical flask was placed in a pentane bath cooled to -95 °C and charged with pre-cooled MeCl (100 mL). Methyl tert-butyl ether (MTBE, 5 L, 0.0037 g, 0.042 mmol) was transferred to the flask via a micropipette. The flask was stirred to disperse the MTBE into the MeCl, then sealed and the solution stored at -95 °C until use.

[0178] Example 4: Slurry polymerization with MTBE added to the reactor

[0179] A 500 mL stainless steel beaker equipped with a temperature probe was placed in a pentane bath cooled to -95 ° C and pre-cooled MeCl (180 mL) was loaded. Isobutylene (20 mL, 14.24 g, 25.0 mmol) was condensed in a pre-cooled measuring cylinder as a liquid and transferred to a reaction flask. Isoprene (0.8 mL, 0.54 g, 7.92 mmol) was transferred to the reaction by a pipette. A portion of the previously prepared MTBE solution was transferred to the reaction flask by a pre-cooled pipette. The amount of MTBE added is shown in Table 2. The solution was mechanically stirred at 800 rpm until the temperature stabilized. A prefabricated AlCl3 initiator solution (3 mL, 0.0090 g, 0.0675 mmol) was transferred to the reaction by a pre-cooled pipette to initiate the reaction. Unless otherwise stated, the polymerization was stirred at 800 rpm for 5 minutes. The polymerization was terminated by adding an ethanol solution of NaOH (1.0 mL, 1 wt%, 0.01 mmol). The polymer cement was removed from the glove box, diluted with hexane (about 300 mL) and antioxidant (1.0 mL, 1 wt% Irganox 1076 in hexane), and allowed to stand overnight in a fume hood to remove volatiles. The cement was coagulated with ethanol (about 500-1000 mL), and the resulting polymer was collected and dried in a vacuum oven at 60°C for 48 hours. The conversion was determined by gravimetric analysis. The results are shown in Table 2.

[0180] Table 2: Slurry Polymerization with MTBE Added to Reactor

[0181]

[0182]

[0183] Example 5: Slurry polymerization with addition of MTBE to initiator

[0184] A portion of the previously prepared AlCl initiator solution (20 mL, 0.06 g, 0.45 mmol) was transferred to a new 100 mL conical flask and kept in a cooling pentane bath at a temperature of -95°C. Methyl tert-butyl ether (MTBE, 4 L, 0.0029 g, 0.034 mmol) was transferred to the flask via a micropipette. The flask was stirred to disperse MTBE in the initiator solution, then sealed and the solution stored at -95°C until use.

[0185] A 500 mL stainless steel beaker equipped with a temperature probe was placed in a pentane bath cooled to -95 ° C and loaded with pre-cooled methyl chloride (MeCl, 180 mL). Isobutylene (20 mL, 14.24 g, 25.0 mmol) was condensed into a pre-cooled measuring cylinder as a liquid and transferred to the reaction flask. Isoprene (0.8 mL, 0.54 g, 7.92 mmol) was transferred to the reaction via a pipette. The solution was mechanically stirred at 800 rpm until the temperature stabilized. A pre-made AlCl3 initiator solution containing MTBE (3 mL, AlCl3 = 0.0090 g, 0.0675 mmol; MTBE = 0.0004 g, 0.0050 mmol) was transferred to the reaction via a pre-cooled pipette to initiate the reaction. Unless otherwise stated, polymerizations were stirred at 800 rpm for 5 minutes. The polymerization was terminated by adding an ethanol solution of NaOH (1.0 mL, 1 wt%, 0.01 mmol). The polymer cement was taken out from the glove box, diluted with hexane (about 300 mL) and antioxidant (1.0 mL, 1 wt% Irganox 1076 in hexane), and left to stand overnight in a fume hood to remove volatiles. The cement was solidified with ethanol (about 500-1000 mL), and the resulting polymer (12.3520 grams, 83.2%) was collected and dried in a 60° C. vacuum oven for 48 hours. The conversion was determined by gravimetric analysis. The initiator efficiency was calculated to be 1287 g polymer / g AlCl3. The results are shown in Table 3.

[0186] Table 3: Slurry Polymerizations Using an Initiator System Containing MTBE

[0187]

[0188]

[0189] X.2 Polymer Analysis

[0190] The polymerization was monitored using a digital thermocouple to track temperature changes. NMR spectroscopy was performed using a Bruker 500 MHz NMR spectrometer using a solution of the polymer in CDCl3 (concentration of about 5 mg / mL). A delay time of 10 seconds was used to collect 32 transients with a pulse angle of 90°. The relative concentration of tetramethylsilane (TMS) (δ = 0) was 1.3 %. 1 Chemical shifts for H spectra are reported in ppm.

[0191] Further experiments were performed to confirm the required structural features to obtain the desired benefits. The experiments were performed as above, but the ether component was varied. It was found that a tertiary alkyl group was required to achieve peak initiator efficiency. The results for initiator efficiency are given in Table 4:

[0192] Table 4: Slurry polymerization using initiator systems containing different ethers

[0193]

[0194] X.3—Continuous Aggregation

[0195] Embodiment 6:

[0196] In experiments to demonstrate the ability of tertiary alkyl ethers to facilitate the continuous cationic polymerization of isobutylene-isoprene rubber, the following experiments were conducted.

[0197] A polymerization feed consisting of 62% methyl chloride, 37% isobutylene, 1% isoprene and 10 ppm MTBE was prepared (stream 1) and cooled to about -100°C. An initiator solution of aluminum trichloride (-0.2 wt%) and water (trace) in methyl chloride was prepared separately (stream 2) and similarly cooled to -100°C. Streams 1 and 2 were continuously fed to a steel reaction vessel also cooled to -100°C, which was equipped with a stirrer and a temperature probe. When the two streams were contacted in the stirred vessel, the monomers reacted to form isobutylene-isoprene rubber in a yield of 60% to 90%, which was determined by the mass of polymer produced relative to the mass of isobutylene injected. The contents of the stirred reaction vessel were continuously overflowed into a second vessel, where the remaining active initiator material from stream 2 was neutralized with sodium hydroxide. The ratio between stream 1 and stream 2 was constantly adjusted in response to temperature changes within the cooled reaction vessel, with the goal of maintaining the temperature between -100°C and -85°C. The second vessel was sampled periodically for subsequent analysis. After stream 1 was depleted, the experiment was stopped and the neutralized sample was devolatilized and analyzed.

[0198] Control experiments were performed as described above, but MTBE was omitted.

[0199] In this way it was demonstrated that in the presence of MTBE it is possible to continuously form isoprene isobutylene elastomers using a portion of the initiator solution normally required for polymer formation. This is expressed in the following table as g AlCl3 / g polymer formed:

[0200]

[0201] Analysis of samples collected in the MTBE and control experiments revealed a number of distinct product advantages conferred by the use of MTBE. These advantages include reduced polydispersity of the product, reduction in cyclic oligomer byproducts, and reduction in non-reactive "branching" components of intrachain unsaturation of the product. The results are provided in Tables 5-7

[0202] Table 5:

[0203] The molecular weight distribution measured by the polydispersity index decreases

[0204]

[0205]

[0206] Table 6:

[0207] C measured by gas chromatography 13 H 24 and C 21 H 40 Reduction of oligomers and C 21 / C 13 Reduction of oligomer ratio

[0208]

[0209] Table 7:

[0210] Reduction in the relative contribution of branched unsaturation (non-reactive) to total unsaturation

[0211]

Claims

1. A method for preparing an isoolefin polymer, the method comprising the steps of: a) providing a reaction medium comprising an organic diluent, at least one monomer that is an isoolefin, other monomers, and an initiator system, wherein the other monomer is a multiolefin, and the initiator system comprises ● at least one aluminum compound, and ●at least one tertiary ether, The molar ratio of the tertiary ether to the total aluminum atoms of the aluminum compound used is 0.01-0.200, and b) polymerizing said at least one monomer that is an isoolefin and said other monomers in said reaction medium in the presence of said initiator system at a temperature in the range of -100°C to -60°C to form a product medium comprising an isoolefin polymer, said organic diluent and optionally residual monomers, wherein the tertiary ether is methyl tertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETBE), methyl tertiary amyl ether (MTAE) and phenyl tertiary butyl ether (PTBE) or a mixture thereof, and The isoolefin polymer comprises a molar ratio of 1,4-isoprene structure to branched unsaturated structure of 14.0 to 20.

0.

2. The process according to claim 1, wherein the isoolefin is isobutylene.

3. The method according to claim 1 or 2, wherein the multiolefin is selected from isoprene, butadiene, 2-methylbutadiene, 2,4-dimethylbutadiene, piperine, 3-methyl-1,3-pentadiene, 2,4-hexadiene, 2-neopentylbutadiene, 2-methyl-1,5-hexadiene, 2,5-dimethyl-2,4-hexadiene, 2-methyl-1,4-pentadiene, 4-butyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene, 2,3-dibutyl-1,3-pentadiene, 2-ethyl-1,3-pentadiene, 2-ethyl-1,3-butadiene, 2-methyl-1,6-heptadiene, cyclopentadiene, methylcyclopentadiene, cyclohexadiene or 1-vinyl-cyclohexadiene or a mixture of the foregoing.

4. The method of claim 3, wherein the polyolefin is isoprene.

5. The process according to any one of claims 1 to 4, wherein the reaction medium further comprises a monomer which is copolymerizable with at least one of the isoolefins and which is neither an isoolefin nor a multiolefin.

6. The method according to any one of claims 1 to 5, wherein the diluent comprises a hydrochlorocarbon, such as methyl chloride, methylene chloride or ethyl chloride; a hydrofluorocarbon represented by the formula: x H y F z , wherein x is an integer from 1 to 40, and wherein y and z are integers and are at least 1; an unsaturated hydrofluorocarbon; a hydrocarbon, preferably an alkane.

7. The process according to any one of claims 1 to 6, wherein the aluminum compound is those represented by the formula MX3, wherein M is aluminum and X is a halogen, preferably aluminum chloride or by the formula MR (m) X (3-m) Those represented by, wherein M is aluminum, X is halogen, and R is selected from C1-C 12 Alkyl and C7-C 14 a monovalent hydrocarbon group from the group consisting of an alkaryl group; and m is 1 or 2.

8. The process according to any one of claims 1 to 7, wherein the tertiary ether is methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), methyl tert-amyl ether (MTAE) or a mixture thereof, and wherein methyl tert-butyl ether (MTBE) is preferred.

9. The method of any one of claims 1-8, wherein the isoolefin polymer comprises a molar ratio of 1,4-isoprene structures to branched unsaturated structures of 14.0 to 17.

0.

10. The method according to any one of claims 1 to 9, wherein the isoolefin polymer comprises 0.9 to 2.0, preferably 1.2 to 2.0 C 21 With C 13 weight ratio.

11. The method according to claim 9 or 10, wherein the isoolefin polymer contains C in an amount of less than 800 ppm, preferably 50-800 ppm, and more preferably 200-700 ppm. 13 Structure and C 21 structure.

12. The method of any one of claims 1-11, wherein the isoolefin polymer comprises a polydispersity index of 1.5 to 4.5 as measured by the ratio of weight average molecular weight to number average molecular weight as determined by gel permeation chromatography.

13. The method of any one of claims 1-12, wherein the method further comprises forming the isoolefin polymer into a rubber product and optionally curing the rubber product.

14. The method of any one of claims 1-12, wherein the method further comprises blending the isoolefin polymer with at least one secondary rubber, optionally forming the isoolefin polymer and secondary rubber into a rubber product, and optionally curing the rubber product.

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