Controlled molecular weight distribution of isobutylene-based elastomeric compositions and methods related thereto

Abstract

The invention relates to a method for controlling the molecular weight distribution of an elastomer composition, and in particular an isobutylene-based elastomer composition, particularly for use in a tire composition such as an inner liner. A polymerization medium comprising a monomer, a diluent, and a catalyst system is polymerized in a reactor. The molecular weight distribution is controlled using post-polymerization processing to achieve a Mooney relaxation index of greater than about 2.5.

Description

[0001] Inventor :Sunny Jacob, Ramki Mattupalli, Lili Li, Stephen A. Lassard

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 405,925, filed on September 13, 2022, and entitled CONTROLLED MOLECULAR WEIGHT DISTRIBUTION OF ISOBUTYLENE-BASED ELASTOMER COMPOSITIONS AND METHODS RELATED THERETO, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0004] The present application relates to methods of controlling the molecular weight distribution of elastomeric compositions, and in particular isobutylene-based elastomeric compositions, particularly for use in tire compositions such as innerliners. Background Art

[0005] Tires contain many rubber compounds and other materials that need to operate safely under a wide range of harsh conditions such as passenger cars, trucks, buses and aircraft vehicles. They are expected to run thousands of miles while maintaining their basic performance and safety properties. Tire performance depends at least in part on their ability to retain air or inflation pressure. Butyl rubber (e.g., elastomers based on isobutylene) is particularly suitable for retaining air and can be formulated for specific tire applications (e.g., tire inner tubes or inner liners, the innermost layer of tires). The specific butyl rubber composition (including additional additives) selected for the inner liner is selected to achieve suitable properties related to processability and uncured and cured physical properties (including mechanical strength, surface appearance and splicing integrity). Many factors can affect these properties.

[0006] Molecular weight distribution (MWD = Mw / Mn), also known as the polydispersity index, has a significant impact on the mechanical and physical bulk properties of the polymer and the resulting compounded product, including properties that are integral to the manufacture of commercially viable tire innerliners - processability and uncured and cured physical properties. For innerliner applications, butyl rubber compound Mooney viscosity and Mooney relaxation are important for producing a rubber with innerliner splicing properties that result in suitable splice strength integrity after curing. A balance of MWD in butyl rubber (high and low molecular weight butyl rubbers) is required to achieve these properties while maintaining processability; the high molecular weight portion contributes to mechanical properties such as tensile break, elongation, impact strength, etc., while the low molecular weight portion contributes to processability factors such as low melt viscosity, plasticizer quality, etc. Therefore, a broad MWD of butyl rubber is important for producing commercially viable tire innerliners and ultimately the finished tire product.

[0007] Butyl rubber polymerization is conventionally performed using appropriate monomers and a Lewis acid catalyst (and initiator). However, widespread inconsistency in the MWD of butyl rubber throughout the tire industry has been previously documented. It has also been observed that currently produced innerliner tire products typically exhibit narrow MWD, e.g., MWD less than about 2.5. As described above, narrow MWD can lead to processing difficulties and / or undesirable physical and mechanical properties.

[0008] The present disclosure provides methods and systems for producing isobutylene-based elastomeric compositions having controlled MWD, particularly for use as tire innerliners. Summary of the invention

[0009] In a non-limiting aspect of the present disclosure, a method is provided of polymerizing a polymerization medium in a reactor, the polymerization medium comprising a monomer, a diluent, and a catalyst system, and the catalyst system comprising a Lewis acid and an initiator, thereby producing a reactor overflow; contacting the reactor overflow with a quencher; and controlling the quenching of the reactor overflow to obtain a Mooney Relaxation Index (MRI) greater than about 2.5, thereby producing a quenched reactor overflow.

[0010] These and other features and attributes of the disclosed controlled MWD methods and systems for producing the isobutylene-based elastomeric compositions of the present disclosure and their advantageous applications and / or uses will be apparent from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] To assist one of ordinary skill in the relevant art in making and using the subject matter herein, reference is made to the accompanying drawings. The following drawings are included to illustrate certain aspects of the present disclosure and should not be construed as an exclusive configuration. The disclosed subject matter is capable of significant modifications, alterations, combinations, and equivalences in form and function as will occur to one of ordinary skill in the art having the benefit of this disclosure.

[0012] Figure 1 is a schematic flow diagram of a simplified aggregation system 100 according to one or more aspects of the present disclosure.

[0013] Figure 2 is a graph showing MRI values ​​under experimental phase conditions according to one or more aspects of the present disclosure.

[0014] Figure 3 is a gel permeation chromatography graph showing MWD values ​​under experimental phase conditions according to one or more aspects of the present disclosure.

[0015] Figure 4 is a graph showing isobutylene conversion values ​​under experimental stage conditions according to one or more embodiments of the present disclosure.

[0016] Figure 5 is a graph showing isobutylene conversion values ​​under experimental stage conditions according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION

[0017] The present application relates to methods of controlling the molecular weight distribution of elastomeric compositions, and in particular isobutylene-based elastomeric compositions, particularly for use in tire compositions such as innerliners.

[0018] The present disclosure provides methods for controlling the MWD of isobutylene-based elastomeric compositions by modifying certain polymerization characteristics. Specifically, the present disclosure provides controlled MWD broadening during butyl polymer production by modifying post-polymerization reactor conditions to change the concentration of the low molecular weight fraction, the modification being achieved by controlling reaction quenching to promote post-reactor polymerization. According to the present disclosure, quenching can be controlled by one or more of: varying the amount of quenching agent; controlling mixing efficiency by one or more of the speed of the reactor blender and / or the viscosity of the reactor overflow; and / or increasing the temperature at the reactor outlet. The methods presented herein allow isobutylene-based elastomeric compositions to have controlled MWD, including controlled broadening of the MWD for use in the production of tire innerliners.

[0019] In various aspects of the present disclosure, the Mooney relaxation index (MRI) is used as an indicator for evaluating the MWD of an isobutylene-based elastomeric composition. Mooney viscometer readings (MRI) are commonly used to measure downstream polymer products and are related to MWD, as described below. The method of the present disclosure provides an isobutylene-based elastomeric composition having an MRI greater than about 2.5. In fact, standard isobutylene-based elastomeric compositions have an MRI value of less than about 2.5.

[0020] definition

[0021] As used herein, the term "catalyst system" and its grammatical variants refer to and include any Lewis acid(s) or other metal complex(s) and optionally at least one initiator for catalyzing the polymerization of hydrocarbon monomers. Other additives, such as catalyst modifiers, may be included. The catalyst system is combined with a diluent for polymerization, collectively referred to as a "polymerization medium". As used herein, "polymerization system" and its grammatical variants refer to the use of a polymerization medium to produce a polymer.

[0022] As used herein, the term "diluent" and its grammatical variations refer to a diluting or dissolving agent, including mixtures thereof (e.g., two or more separate diluents). A diluent can also be used to affect reactor mixing (using an overhead blender) since it acts as a diluting agent.

[0023] As used herein, the term "solvent" and grammatical variations thereof refer to a chemical agent that can dissolve the resulting polymer.

[0024] As used herein, "reactor" and its grammatical variants refer to any container (one or more) in which a chemical reaction (e.g., polymerization) occurs. Examples of butyl polymerization reactors include continuous flow-stirred tank reactors using continuous kettle agitation, and draft tube reactors. Various cooling jackets, pipelines, etc. can be used in combination with the reactor (and can be integral) to control or otherwise maintain the reactor temperature during polymerization. Commercial reactors can generally be well-mixed containers with a high circulation rate provided by an axial flow pump having a volume (excluding jackets) greater than 1,000 to 10,000 liters. Both polymerization and pumps can generate heat, and in order to keep the slurry cool, the reaction system can include a heat exchanger. In some reactors, the slurry can be circulated through the tubes of the heat exchanger. Cooling can be provided, for example, by boiling ethylene on the shell side. The slurry temperature can be set by the boiling ethylene temperature, the required heat flux, and the overall heat transfer resistance.

[0025] As used herein, the term "slurry" and grammatical variations thereof refer to an amount of diluent comprising polymer precipitated from the catalyst system and the diluent. The slurry concentration is the weight percent of partially or fully precipitated polymer based on the total slurry.

[0026] As used herein, the term "quench" and grammatical variations thereof refer to the process of rapidly heating and mixing a reactor effluent stream with a quench medium, wherein further polymerization is terminated.

[0027] As used herein, the term "polymer" and its grammatical variants refer to homopolymers, copolymers, interpolymers, terpolymers, etc. The term "copolymer" and its grammatical variants are meant to include polymers having two or more monomers. The term "interpolymer" and its grammatical variants mean any polymer or oligomer having a number average molecular weight of 500 or more prepared by polymerization or oligomerization of at least two different monomers. As used herein, when a polymer is referred to as "comprising" a monomer, the monomer is present in the polymer in the polymerized form of the monomer or in the form of a derivative of the monomer. Similarly, when a catalyst component is described as comprising a neutral stable form of a component, it will be fully understood by those skilled in the art that the ionic form of the component is the form that reacts with the monomer to produce a polymer.

[0028] As used herein, the term "olefin" and its grammatical variants refer to hydrocarbons containing carbon-carbon double bonds. "Isoolefin" and its grammatical variants refer to any olefin monomer having two substituents on the same carbon. The term "diolefin" and its grammatical variants refer to any olefin monomer having two double bonds.

[0029] As used herein, "elastomer" or "elastomeric composition" and grammatical variations thereof refer to any polymer or composition of polymers consistent with the definition of ASTM D1566-21A (November 2021). Elastomer may be used interchangeably with the term "rubber(s)" herein.

[0030] As used herein, "Mooney viscosity" and its grammatical variants are the Mooney viscosity of a polymer or polymer composition. The polymer composition analyzed for the determination of Mooney viscosity should be substantially free of diluents and solvents. For example, the sample can be placed on a boiling water vapor table in a hood to evaporate most of the diluent and unreacted monomers, and then dried overnight in a vacuum oven (12 hours, 90°C), and then tested according to laboratory analytical techniques, or the sample for testing can be taken from a devolatilized polymer (i.e., devolatilization after the polymer in an industrial scale process). Unless otherwise noted, the Mooney viscosity is measured using a Mooney viscometer according to ASTM D1646-19A (November 2019, but with the following modifications / explanations of the procedure). First, the sample polymer is pressed between two hot plates of a compression molding press before testing. The plate temperature is 125°C + / - 10°C instead of 50 + / - 5°C as recommended in ASTM D1646-17, because 50°C cannot cause sufficient aggregation. Further, while ASTM D1646-17 allows several options for die protection, if any two options provide conflicting results, PET 36 microns is used as the die protection. Further, ASTM D1646-17 does not specify sample weight in Section 8; therefore, in cases where results may vary based on sample weight, the Mooney viscosity determined according to the D1646-17 Section 8 procedure using a sample weight of 21.5 + / - 2.7 grams (g) will prevail. Finally, the pre-test standing procedure set forth in D1646-17 Section 8 is 23 + / - 3°C in air for 30 minutes; the Mooney values ​​reported herein are determined after standing at 24°C + / - 3°C in air for 30 minutes. Samples are placed on either side of the rotor according to the ASTM D1646-17 test method; the torque required to rotate the viscometer motor at 2 rpm is measured by the sensor used to determine the Mooney viscosity. The results are reported as Mooney units (ML, 1+4 at 125°C or ML, 1+8 at 125°C), where MU is the Mooney viscosity number, L represents the large spindle (defined as ML in ASTM D1646-17), 1 is the warm-up time in minutes, 4 or 8 is the sample run time in minutes after the motor is started, and 125°C is the test temperature. Thus, a Mooney viscosity of 90 determined by the foregoing method would be reported as a Mooney viscosity of 90MU (ML, 1+8 at 125°C) or 90MU (ML, 1+4 at 125°C). Alternatively, the Mooney viscosity may be reported as 90MU; in such cases, it should be assumed that such viscosity was determined using the (ML, 1+4 at 125°C) method just described, unless otherwise noted. In some cases, a lower test temperature (e.g., 100°C) may be used, in which case the Mooney is reported as Mooney viscosity (ML, 1+8 at 100°C), or at T°C, where T is the test temperature.

[0031] As used herein, the term "Mooney relaxation index" or "MRI" and grammatical variations thereof refer to a value related to the MWD of an isobutylene-based elastomer. It is based on the Mooney relaxation determination and can be determined according to the following Equation 1:

[0032] MRI=[(k / (a+1)][60 (a+1) -4 (a+1) ],

[0033] where a is the regression slope and k is the regression intercept, in terms of Mooney relaxation in units of 1 second.

[0034] Numerical ranges used herein include the values ​​recited within the range. For example, a numerical range of "1 wt % to 10 wt %" includes 1 wt % and 10 wt % within the recited range.

[0035] Aggregation System

[0036] The present disclosure provides methods for controlling MWD (and MRI) using post-polymerization control and modification of polymerization systems. In one or more aspects described herein, the present disclosure provides methods for varying the low molecular weight portion of an isobutylene-based elastomer, thereby controlling the ratio of the low molecular weight portion compared to the high molecular weight portion of an isobutylene-based elastomer as part of a polymerization system.

[0037] Before describing the methods of the present disclosure in more detail, a brief overview of an example polymerization system for producing isobutylene-based elastomers is provided so that various aspects of the present disclosure may be better understood.

[0038] The polymerization system for producing isobutylene-based elastomers is typically carried out using a continuous slurry polymerization system, wherein the polymerization reactor temperature is less than 0° C., such as in the range of about −105° C. to about 0° C. However, it should be appreciated that a batch polymerization system may be used in accordance with one or more aspects described herein without departing from the scope of the present disclosure.

[0039] Reference now Figure 1 , illustrates a schematic flow diagram of a polymerization system 100 according to one or more aspects of the present disclosure. Catalyst system 102 and monomer 104 are fed to polymerization reactor 108. In some cases, catalyst system 102 and monomer 104 can be blended in a blending unit (not shown) prior to feeding to polymerization reactor 108. Furthermore, in some cases, if necessary, monomers 104 can be treated to remove impurities before being introduced into polymerization reactor 108 (or blending unit).

[0040] The catalyst system 102 and the monomer 104 can be fed to the polymerization reactor 108 simultaneously or separately. The monomer 104 is fed to the polymerization reactor 108 separately or together with the catalyst system 102 at a temperature less than 0°C, for example, in the range of about -105°C to about 0°C. The catalyst system 102 and the monomer 104 are mixed in the polymerization reactor 108 and can initially exist as a single phase dissolved in the diluent 106. The diluent 106 serves to dissolve the catalyst system 102 and the monomer 104 without dissolving the polymerization product (polymer), and thus allows them to precipitate and form a slurry. When one or more of the inputs are fed to the polymerization reactor 108 simultaneously, a single pump impeller can be used. The reactor pump impeller is generally capable of one or both of upward pumping or downward pumping, and generally includes a motor with a measurable ampere number. The pump impeller serves to maintain a constant flow of monomers, catalyst systems and diluents (including reacted and unreacted substances (e.g., monomers) in the reactor), and provides high shear mixing to prevent reactor fouling.

[0041] The polymerization reactor 108 can be any suitable reactor for polymerization to produce an isobutylene-based elastomer. In one or more aspects, the polymerization reactor 108 is a draft tube or continuous draft tube reactor with a circulation pump 108a (for efficient stirring). Typically, the polymerization reactor 108 is equipped with an external cooling jacket 108c and associated internal cooling (or heat exchange) pipes to remove the heat generated during the polymerization and maintain the desired reaction temperature. In one or more aspects, the cooling pipe can include liquid ethylene to extract heat from the polymerization reaction. The polymerization system also includes a steam jacket 122 for assisting in controlling the molecular weight distribution, as described herein. The steam jacket 122 can be a pipeline that receives a reactor effluent stream and provides heat thereto; that is, the reactor effluent stream flows through the steam jacket 122.

[0042] In one or more aspects, the polymerization reactor can have a volume (including the jacket and associated internal cooling pipes) in the range of about 1,000 liters (L) to about 10,000 L, including any values ​​and subsets therebetween. The volume facilitates large-scale volume polymerization reactions in accordance with the various aspects described herein. Thus, reactors with larger volumes (and smaller volumes, although smaller volumes are preferred) can be used to facilitate scale-up without departing from the scope of the present disclosure.

[0043] Typically, the polymerization temperature within the polymerization reactor 108 for producing the isobutylene-based elastomer of the present disclosure is in the range of about -105°C to about 0°C, including any values ​​and subsets therebetween, such as -100°C to -50°C or -98°C to -92°C, etc., preferably from 0°C to the freezing point of the polymerization medium (e.g., diluent and monomer mixture) and then quenching the reaction by adding a quenching agent to the polymerization medium.

[0044] During polymerization, the catalyst system 102 and the monomer 104 react and the resulting polymer precipitates from the diluent 106. A reactor effluent stream 110 comprising polymer (produced during polymerization), diluent 106, unreacted monomer 104, and unreacted catalyst system 102 exits the reactor from the reactor outlet, which may be collectively referred to herein as "reactor overflow". For an isobutylene-based elastomer polymerization system 100, the reactor effluent stream 110 may be warmed to room temperature (RT) or otherwise heated, for example, from a temperature at or below 0°C (within the polymerization reactor 108) to a temperature in the range of, for example, about -50°C to about 20°C, encompassing any values ​​and subsets therebetween. A steam jacket 122 may be used to provide such heat.

[0045] The unreacted catalyst system 102 in the reactor effluent stream 110 can form undesirable substances that interfere with downstream processing of the polymer produced during polymerization (e.g., functionalization thereof). During warming or heating, but before heating above about -50°C to about 20°C, the reactor effluent stream 110 can be quenched 118 using a quencher. The quenching serves to terminate the reactivity of all unreacted catalyst systems 102 (i.e., the catalyst (s) in the catalyst system 102) before any significant warming or heating of the reactor effluent stream 110, so as to prevent continuous polymerization and crosslinking reactions from occurring when the reactor effluent stream 110 is heated, which may interfere with downstream processing. Conventional quenchers include steam and / or hot water introduced into the reactor effluent stream 110. Other conventional quenchers include alcohols (linear or branched), such as ethanol, tert-butyl alcohol, methanol, triethylene glycol (TEG), and any combination thereof. During the quench, the reactor effluent stream 110 can be combined with solvent 116 and a mechanical agitator located inside the overflow tube of 110 is used to dissolve and fractionate the desired polymer stream 118 (for downstream processing 120 (e.g., halogenation or other functionalization, etc.)) away from the diluent(s) 106, solvent(s) 116, and any unreacted monomer 104 or diluent or solvent to a tank or other storage container (not shown). The contents of the tank can be recycled in one or more aspects of the present disclosure.

[0046] Polymerization system for controlling MWD (and MRI) of isobutylene-based elastomers

[0047] The methods of the present disclosure for producing isobutylene-based elastomers with controlled MWD (and MRI) generally utilize existing polymerization systems, such as those described in Figure 1The present disclosure is of the type described herein, but using unconventional post-polymerization (post-reactor) methods. These post-polymerization methods can be advantageously used to broaden the MWD of the resulting isobutylene-based elastomeric product by producing low molecular weight polymers while preventing polymer degradation. Although the present disclosure is described with reference to tire innerliners of isobutylene-based elastomers having a desired wide MWD, it should be appreciated that the present disclosure can be applicable to other types of retained air products or can be applicable to other products having a desired wide MWD. ​​That is, various aspects of the present disclosure can be generally used to control the MWD (and MRI) of isobutylene-based elastomers without departing from the scope of the present disclosure.

[0048] In one or more aspects, the present disclosure provides a polymerization system for polymerizing a polymerization medium comprising one or more monomers, a diluent, and a catalyst system.

[0049] One or more monomers for use in the present disclosure may include any hydrocarbon monomer. Suitable examples of hydrocarbon monomers include, but are not limited to, one or more of olefins, alpha-olefins, disubstituted olefins, isoolefins, conjugated dienes, non-conjugated dienes, styrene, substituted styrene, vinyl ethers, and any combination thereof. In one or more aspects of the present disclosure, exemplary monomer combinations include isobutylene and p-methylstyrene. In one or more aspects of the present disclosure, exemplary monomer combinations include isobutylene and isoprene, thereby forming, for example, polyisobutylene-co-isoprene (or, when halogenated, halogenated polyisobutylene-co-isoprene). In each exemplary combination, and in any monomer combination used in the polymerization system of the present disclosure, a homopolymer of isobutylene may be additionally included.

[0050] When two or more monomers (homopolymers with or without isobutylene) are used in various aspects of the present disclosure, they may be present in equal or unequal amounts without departing from the scope of the present disclosure. For example, in the various examples described below, the monomers selected are isobutylene and isoprene, wherein isobutylene is the predominant monomer present in concentration, thereby forming, for example, polyisobutylene-co-isoprene (or, when halogenated, halogenated polyisobutylene-co-isoprene).

[0051] In one or more aspects, the monomer can be present in the polymerization medium in an amount ranging from about 30 wt% to about 40 wt%, such as about 30 wt% to about 35 wt% or about 35 wt% to about 40 wt%, encompassing any values ​​and subsets therebetween.

[0052] The diluent is selected to dissolve the catalyst and monomer (one or more) in the catalyst system and allow the precipitation of the polymer product (polymer). An acceptable relatively low viscosity of the polymerization medium is obtained, so that the polymerization heat can be more effectively removed by surface heat exchange. Suitable diluents include organic compounds, particularly organic compounds with affinity for hydrocarbon fluids. Examples of suitable diluents for use in the present disclosure include but are not limited to hydrocarbons, such as hexane, heptane, halogenated hydrocarbons, such as chlorinated hydrocarbons, such as ethyl chloride, methyl chloride, CHCl , CCl , n-butyl chloride, chlorobenzene, etc., and any combination thereof. Methyl chloride is a commercially acceptable diluent for example due to its suitable freezing point and boiling point, and tends to produce relatively high molecular weight butyl rubber polymers.

[0053] According to one or more aspects of the present disclosure, a diluent such as methyl chloride or hexane is selected for use in the polymerization system described herein to control MWD (and MRI), and an isobutylene-based elastomeric polymer product concentration in the range of about 25% to about 40% by volume, such as about 26% to about 37% by volume, including any values ​​and subsets therebetween, such as about 30% to about 35% by volume, can be advantageously achieved. In some cases, the isobutylene-based elastomeric polymer product concentration is about 30% by volume.

[0054] The amount of diluent may be adjusted according to one or more aspects of the present disclosure to adjust the viscosity of the reactor overflow, as defined herein, to control the MWD (and MRI).

[0055] The catalyst system of the present disclosure includes Lewis acid (one or more) or metal complex (one or more) and initiator.Lewis acid (one or more) or metal complex (one or more) is intended to catalyze cationic polymerization to produce an elastomer based on isobutylene. Lewis acids based on aluminum can be used in various aspects of the present disclosure. Suitable examples of Lewis acids based on aluminum include but are not limited to aluminum chloride, aluminum bromide, ethylaluminum dichloride (EADC), ethylaluminum sesquichloride, diethylaluminum chloride, methylaluminum dichloride, methylaluminum sesquichloride, dimethylaluminum chloride, etc., and any combination thereof alone or with other suitable Lewis acids. Other suitable examples include Lewis acids based on boron such as boron trifluoride and Lewis acids based on titanium such as titanium tetrachloride, etc., and any combination thereof alone or with other suitable Lewis acids. In the exemplary aspects of the present disclosure, the Lewis acids (one or more) selected include ethylaluminum dichloride and ethylaluminum sesquichloride, which can be combined.

[0056] According to one or more aspects of the present disclosure, ethylaluminum dichloride (EADC) is selected for use in the polymerization system described herein to control MWD (and MRI). In one or more aspects, the EADC Lewis acid and initiator can be present in the polymerization system described herein in a range of about 3, about 2.5 to about 3 on a molar basis, covering any value and subset therebetween. Such ratios are equally applicable to any Lewis acid (one or more) or metal complex (one or more) to initiator ratio, as described herein, without departing from the scope of the present disclosure.

[0057] Various initiators may be used in the polymerization system of the present disclosure for controlling the MWD (and MRI) of the isobutylene-based elastomer, provided that they are compatible with the other components of the polymerization medium. The initiator for use in the present disclosure is selected so that it can be complexed with the selected Lewis acid(s) or other metal complex(s) in a suitable diluent to produce a complex that reacts rapidly with the hydrocarbon monomer(s) to thereby form a growing polymer chain (polymerization). Suitable examples of initiators for use in the present disclosure include, but are not limited to, Bronsted acids such as H2O, HCl, RCOOH (wherein R is an alkyl group), alkyl halides such as (CH3)3CCl, C6H5C(CH3)2Cl, 2-chloro-2,4,4-trimethylpentane and 2-chloro-2-methylpropane, hydrogen halides, and any combination thereof. Other suitable initiators may also be used as known to those skilled in the art.

[0058] According to one or more aspects of the present disclosure, hydrogen chloride (HCl) is selected as an initiator for use in the polymerization system described herein in order to control MWD (and MRI). In one or more aspects, the HCl initiator is diluted in a diluent (e.g., hexane, methyl chloride) at a concentration of about 70 parts per million (ppm) to about 300 ppm, encompassing any values ​​and subsets therebetween, such as about 100 ppm to about 250 ppm or about 150 ppm to about 200 ppm or about 125 ppm, etc. The diluted initiator can be present on a weight basis at a ratio to monomer (one or more) (e.g., isobutylene) of about 30 ppm to about 60 ppm, encompassing any values ​​and subsets therebetween, such as about 40 ppm to about 50 ppm, such as about 40 ppm, etc. Such concentrations in diluents and ratios to monomer (one or more) are equally applicable to any initiator, as described herein, without departing from the scope of the present disclosure.

[0059] Method for controlling MWD (and MRI) of isobutylene-based elastomers

[0060] In one or more aspects of the present invention, methods are provided in which post-polymerization control and modification of the polymerization system are used to promote post-polymerization by controlling certain characteristics of the reaction quench. These post-polymerization control and modification may include one or more (including all) of the following: changing the amount and / or quenching efficiency of the quenching agent and specifically TEG to broaden the molecular weight distribution of the produced polymer, and / or increasing the polymerization reactor outlet (e.g. Figure 1 , where the reactor effluent stream 110 leaves the polymerization reactor 108). Manipulation of quench efficiency may be achieved using one or more (including all) of the following: adjusting the blending speed of the overhead blender, the amount of processing aid to change the viscosity of the reactor overflow, and / or changing the reactor conditions to affect the viscosity of the reactor overflow, such as by increasing the temperature at the reactor outlet.

[0061] Such post-polymerization control produces low molecular weight polymer and prevents degradation of the polymer and downstream processing problems.

[0062] In one or more aspects of the present disclosure, the amount of quencher can be adjusted based on the concentration of the catalyst. In one or more aspects, the molar ratio of quencher to catalyst is reduced compared to conventional polymerization processes and can be in the range of about 0.4 to about 0.8, such as about 0.4 to about 0.6, or about 0.6 to about 0.8, encompassing any values ​​and subsets therebetween.

[0063] In one or more aspects of the present disclosure, the top blender can be reduced to facilitate post-polymerization by lowering the top blender (see Figure 1 , 108a) speed, or stopping the top blender by completely shutting it off at one or more stages during polymerization or quenching.

[0064] In one or more aspects of the present disclosure, the steam jacket of the top pipe can be controlled so that the temperature is increased, especially at the reactor outlet, thereby widening its MWD. ​​For example, the steam jacket can be adjusted so that the temperature is greater than about -40°C, such as in the range of about -40°C to about 0°C, or about -20°C to about 0°C, or about -40°C to about -20°C, or about -30°C to about -10°C, encompassing any values ​​and subsets therebetween.

[0065] The method for controlling the MWD (and MRI) of an isobutylene-based elastomer is further described below with reference to the Examples.

[0066] Example Implementation

[0067] Non-limiting example embodiments of the present disclosure include:

[0068] Embodiment A: A method comprising: polymerizing a polymerization medium in a reactor, the polymerization medium comprising a monomer, a diluent, and a catalyst system, and the catalyst system comprising a Lewis acid and an initiator, thereby producing a reactor overflow; contacting the reactor overflow with a quencher; and controlling the quenching of the reactor overflow to obtain a Mooney relaxation index (MRI) greater than about 2.5, thereby producing a quenched reactor overflow.

[0069] Non-limiting example embodiment A may include one or more of the following elements:

[0070] Element 1: wherein the MRI is in the range of about 2.5 to about 4.5.

[0071] Element 2: wherein the controlling comprises adjusting the amount of the quencher such that the molar ratio of the quencher to the Lewis acid is in the range of about 0.4 to about 0.8.

[0072] Element 3: wherein the controlling comprises adjusting the amount of the quencher such that the molar ratio of the quencher to the Lewis acid is in the range of about 0.4 to about 0.6.

[0073] Element 4: wherein the reactor comprises an overhead blender and the controlling comprises reducing the speed or shutting down the overhead blender during one or both of polymerization and quenching.

[0074] Element 5: wherein the reactor outlet comprises a steam jacket and the controlling comprises heating the steam jacket so that the temperature at the reactor outlet is in the range of about -40°C to about 0°C.

[0075] Element 6: wherein the reactor outlet comprises a steam jacket and the controlling comprises heating the steam jacket so that the temperature at the reactor outlet is in the range of about -30°C to about -10°C.

[0076] Element 7: wherein the reactor comprises an overhead blender and the controlling comprises (1) reducing the speed or shutting down the overhead blender during one or both of polymerization and quenching and (2) adjusting the amount of quenching agent such that the molar ratio of quenching agent to Lewis acid is in the range of about 0.4 to about 0.8.

[0077] Element 8: wherein the reactor comprises an overhead blender and the controlling comprises (1) reducing the speed or shutting down the overhead blender during one or both of polymerization and quenching, (2) adjusting the amount of quenching agent such that the molar ratio of quenching agent to Lewis acid is in the range of about 0.4 to about 0.8, and wherein the reactor outlet comprises a steam jacket, and wherein the controlling further comprises (3) heating the steam jacket such that the temperature at the reactor outlet is in the range of about -40°C to about 0°C.

[0078] Element 9: wherein the reactor comprises a steam jacket, and the controlling comprises (1) heating the steam jacket so that the temperature at the reactor outlet is in the range of about -40°C to about 0°C, and (2) adjusting the amount of the quenching agent so that the molar ratio of the quenching agent to the Lewis acid is in the range of about 0.4 to about 0.8.

[0079] Element 10: wherein the reactor comprises an overhead blender and a reactor outlet comprising a steam jacket, and the controlling comprises (1) closing the overhead blender during one or both of polymerization and quenching, and (2) heating the steam jacket so that the temperature at the reactor outlet is in the range of about -40°C to about 0°C.

[0080] Element 11: wherein the monomer is one or more of olefins, α-olefins, disubstituted olefins, isoolefins, conjugated dienes, non-conjugated dienes, styrene, substituted styrenes and vinyl ethers.

[0081] Element 12: The monomer is isobutylene, isoprene or a combination thereof.

[0082] Element 13: wherein the monomer is present in the polymerization medium in an amount ranging from about 30 wt % to about 40 wt %.

[0083] Element 14: wherein the diluent is one or more of a hydrocarbon, a halogenated hydrocarbon and a chlorinated hydrocarbon.

[0084] Element 15: wherein the diluent is present in the polymerization medium in an amount ranging from about 60 volume % to about 70 volume %.

[0085] Element 16: The Lewis acid is one or more of aluminum trichloride, aluminum tribromide, ethylaluminum dichloride, ethylaluminum sesquichloride, diethylaluminum chloride, methylaluminum dichloride, methylaluminum sesquichloride and dimethylaluminum chloride.

[0086] Element 17: wherein the Lewis acid is ethylaluminum dichloride.

[0087] Element 18: The initiator is one or two of Bronsted acid, alkyl halide and hydrogen halide.

[0088] Element 19: wherein the quencher is at least one alcohol.

[0089] Element 20: wherein the quencher is triethylene glycol.

[0090] Element 21: wherein the reactor is a continuous reactor.

[0091] Element 22: Also included: separating a polymer portion from the quenched reactor overflow.

[0092] Element 23: wherein the monomers are isobutylene and isoprene and are polymerized to form polyisobutylene-co-isoprene.

[0093] Element 24: wherein the monomers are isobutylene and isoprene, and the polymerization forms polyisobutylene-co-isoprene, and further comprises halogenating the polyisobutylene-co-isoprene to form halogenated polyisobutylene-co-isoprene.

[0094] Each of elements 1 to 24 may be combined in any combination without limitation.

[0095] In order to facilitate a better understanding of the embodiments of the present invention, the following examples of preferred or representative embodiments are given. The following examples should in no way be construed as limiting or defining the scope of the present invention.

[0096] Example

[0097] In the following non-limiting examples, a staged approach (stages 1-5) was used to adjust the post-polymerization reactor conditions using one or more of the factors described above. In some cases, the previous stage conditions were retained for the next stage, as indicated below. The adjustments at each stage were made using data from the samples and the MRI (an indicator of MWD trend) was determined, as defined below. MWD was determined using gel permeation chromatography (GPC).

[0098] All examples were conducted under standard conditions and included polymerization systems comprising isobutylene and isoprene monomers, a Lewis acid catalyst of EADC, and a hexane diluent. The quencher used was TEG.

[0099] Example 1: Phase 1

[0100] In this example, stage 1 conditions were used in which the quencher to catalyst ratio was reduced compared to conventional ratios. The molar ratio of quencher to catalyst (TEG / EADC) for stage 1 was greater than 0.6 and less than or equal to about 1.2 (see, for example, samples P1-4, -7, -8, -11, and -16). Reactor conditions, MRI, and Mooney viscosity results are provided in Table 1; samples were approximately 1 hour apart.

[0101] Table 1

[0102]

[0103]

[0104] Table 1, continued

[0105]

[0106]

[0107] The distribution of MRI values ​​for the Phase 1 samples (having a TEG / EADC of approximately 1.2) had a median of 2.70 and a mean of 2.70 (in Figure 2 (Fig. 1A) Stage 1 MRI sample.

[0108] Example 2: Phase 2

[0109] In this example, stage 2 conditions were used in which the quencher to catalyst ratio was further reduced compared to stage 1 conditions. The molar ratio of quencher to catalyst (TEG / EADC) for stage 2 was equal to about 0.6 (see, e.g., samples P2-2, -7, -10, -12). Reactor conditions, MRI, and Mooney viscosity results are provided in Table 2; samples were 2 hours apart.

[0110] Table 2

[0111]

[0112] Table 2, continued

[0113]

[0114] The distribution of MRI values ​​for stage 2 samples (having a TEG / EADC of approximately 0.6) had a median of 2.74 and a mean of 2.77 (in Figure 2 MRI of the Stage 2 sample is plotted in ). Thus, using a post-processing approach that reduces the quencher to catalyst ratio, a broader MWD (indicated by a higher MRI) is obtained—representing an increase in the amount of low molecular weight polymer fraction compared to Stage 1.

[0115] Example 3: Stage 3

[0116] In this example, stage 3 conditions were used where the reduced quencher to catalyst ratio (TEG / EADC = ~0.6) of stage 2 was combined with shutting down the reactor's overhead blender, thereby affecting the mixing of catalyst and quencher. Reactor conditions, MRI, and Mooney viscosity results are provided in Table 3; samples were approximately 2 hours apart.

[0117] Table 3

[0118]

[0119] Table 3, continued

[0120]

[0121]

[0122] The distribution of MRI values ​​for the Stage 3 samples (with TEG / EADC of about 0.6 and top blender off) had a median of 2.93 and a mean of 2.97 (in Figure 2 ). Thus, using a post-processing approach that reduces the quencher to catalyst ratio in addition to shutting down the reactor's overhead blender, a broader MWD (indicated by a higher MRI) is obtained—representing an increase in the amount of low molecular weight polymer fraction compared to Stage 1 and Stage 2 conditions.

[0123] Example 4: Stage 4

[0124] In this example, stage 4 conditions were used, with a further reduced quencher to catalyst ratio compared to stage 3 combined with shutting down the reactor's overhead blender, thereby affecting the mixing of catalyst and quencher. The molar ratio of quencher to catalyst (TEG / EADC) for stage 4 was about 0.5 (see, for example, samples P4-1, -7, -9, -10, -11). Reactor conditions, MRI, and Mooney viscosity results are provided in Table 4; samples were approximately 2 hours apart.

[0125] Table 4

[0126]

[0127]

[0128] Table 4, continued

[0129]

[0130] The distribution of MRI values ​​for the Stage 4 samples (with TEG / EADC of about 0.5 and top blender off) had a median of 3.17 and a mean of 3.20 (in Figure 2 ). Thus, using a post-processing approach that reduced the quencher to catalyst ratio to about 0.5 in addition to shutting down the reactor's overhead blender, a broader MWD (indicated by a higher MRI) was obtained—representing an increase in the amount of low molecular weight polymer fraction compared to each of the Stages 1-3 conditions.

[0131] Example 5: Stage 5

[0132] In this example, stage 5 conditions were used, in which all stage 4 conditions were combined with an elevated temperature of the reactor overhead stream (e.g., via steam) to promote post-polymerization reactions. It should be noted that the lowest temperature in stage 5 was about -30°C, as shown below. Reactor conditions, MRI, and Mooney viscosity results are provided in Table 5; samples were approximately 2 hours apart.

[0133] Table 5

[0134]

[0135]

[0136] Table 5, continued

[0137]

[0138] The distribution of MRI values ​​for the Stage 5 sample (with TEG / EADC of about 0.5, overhead blender turned off, and the temperature of the overhead stream increased) had a median of 3.24 and a mean of 3.24 (at Figure 2 5 MRI sample is plotted in ). Thus, using a post-processing approach that reduces the quencher to catalyst ratio to about 0.5 in addition to shutting off the reactor's overhead blender and increasing the temperature at the reactor outlet, a broader MWD (indicated by a wider MRI) is obtained—representing an increase in the amount of low molecular weight polymer fraction compared to each of the Stages 1-4 conditions.

[0139] With reference to Examples 1-5, Figure 2 is a graph showing the MRI values ​​for each of the stages 1-5 described above. The average MRI range between stage conditions was 2.7-3.24. Again, it is important to note that MRI is an indicator of MWD, but the absolute values ​​between MRI and MWD are not equal; an increasing trend in MRI indicates an increasing trend in MWD. ​​In fact, now refer to Figure 3 , which is a gel permeation chromatography graph showing the MWD of the results of Example 1 herein (Stage 1) and Example 4 herein (Stage 4). As shown, the MWD of Stage 1 is 3.1, with the MWD of Stage 4 shifting significantly to 3.8. Thus, by employing one or more of the post-polymerization methods of the present disclosure in the resulting butyl rubber, both the MRI and the MWD are significantly increased, which is believed (without being bound by theory) to represent an increase in lower molecular weight polymer.

[0140] Furthermore, Examples 1-5 show an overall increase in conversion of starting materials for similar reactant residence times. Figure 4 is a graph showing isobutylene conversion values ​​under experimental stage conditions according to one or more embodiments of the present disclosure. Figure 5 is a graph showing isobutylene conversion values ​​under experimental stage conditions according to one or more embodiments of the present disclosure.

[0141] Example 6

[0142] In this example, commercially available butyl rubber of a copolymer of isobutylene and isoprene was prepared according to confidential specifications (control samples C1-C12) and thereafter prepared according to Stage 5 conditions (all other conditions were maintained unchanged) (experimental samples E1-E12). MRI and Mooney viscosity results are shown in Table 6 below.

[0143] Table 6

[0144]

[0145]

[0146] The distribution of MRI values ​​for the control sample had a median of 3.22 and a mean of 3.23, while the distribution of MRI values ​​for the experimental sample (processed as described herein in Stage 5) had a median of 4.00 and a mean of 4.02. This example again shows that use of the post-processing methods of the present disclosure results in a broader MWD (indicated by a higher MRI) - representing an increase in the amount of low molecular weight polymer fraction.

[0147] Example 7

[0148] In this example, commercially available halogenated (functionalized) butyl rubbers of copolymers of isobutylene and isoprene were prepared according to confidential specifications (control samples C13-C24) and thereafter prepared according to Stage 5 conditions (all other conditions were maintained unchanged) (experimental samples E13-E24). MRI and Mooney viscosity results are shown in Table 7 below.

[0149] Table 7

[0150]

[0151]

[0152] The distribution of MRI values ​​for the control samples had a median of 3.3 and a mean of 3.4, while the distribution of MRI values ​​for the experimental samples (processed as described herein in Stage 5) had a median of 4.1 and a mean of 4.1. This example again shows that use of the post-processing methods of the present disclosure results in a broader MWD (indicated by a higher MRI) - representing an increase in the amount of low molecular weight polymer fraction, including when processing halogenated butyl rubber.

[0153] Thus, the present disclosure shows that post-polymerization control and modification of the polymerization system according to one or more methods of the present disclosure can be used to broaden the molecular weight distribution of the resulting polymer.

[0154] Unless otherwise indicated, all numerical values ​​used in this specification and the associated claims expressing the amounts of ingredients, properties such as molecular weight, reaction conditions, etc., are to be understood as being modified in all instances by the term "about". Therefore, unless indicated to the contrary, the numerical parameters listed in the following specification and the appended claims are approximate values ​​that may vary depending on the desired properties sought to be obtained by embodiments of the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be interpreted in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0155] One or more illustrative embodiments including one or more inventive elements are proposed herein. For the sake of clarity, all features of physical embodiments are not described or shown in this application. It should be understood that in the development of physical embodiments including one or more elements of the present invention, in order to achieve the goal of the developer, many specific decisions of the embodiments must be made, such as complying with system-related, business-related, government-related and other constraints, which change from time to time with the embodiment. Although the efforts of the developer may be time-consuming, such efforts are routine tasks for those of ordinary skill in the art who benefit from the present disclosure.

[0156] Although compositions and methods are described herein in terms of "comprising" various components or steps, the compositions and methods may also be "consisting essentially of" or "consisting of" various components and steps. Therefore, the present invention is well adapted to obtain the results and advantages mentioned and inherent therein. The specific embodiments and configurations disclosed above are merely illustrative, as it is apparent to those skilled in the art having the benefit of the teachings herein that different but equivalent means may be employed to modify and implement the present invention. In addition, it is not intended to limit the details of the configuration or design shown herein, except as described in the following claims. It is therefore apparent that the specific illustrative embodiments disclosed above may be changed, combined or modified, and all such changes are considered to be within the scope and spirit of the present invention. The invention disclosed illustratively herein may be suitably implemented in the absence of any element not specifically disclosed herein and / or any optional element disclosed herein. Although compositions and methods are described in terms of "comprising", "containing" or "including" various components or steps, the compositions and methods may also be "consisting essentially of" or "consisting of" various components and steps. All numerical values ​​and ranges disclosed above may be changed to some extent. Whenever a numerical range with a lower limit and an upper limit is disclosed, any value and any included range falling within the range is specifically disclosed. In particular, each value range disclosed herein (having the following form "from about a to about b", or equivalently "from about a to b", or equivalently "from about ab") should be understood to enumerate each value and range included in the wider range of values. In addition, the terms in the claims have their ordinary, general meaning unless otherwise explicitly and clearly defined by the patentee. In addition, the indefinite article "a" or "an" as used in the claims is defined herein to mean one or more than one of the elements it introduces.

Claims

1. Methods, including: polymerizing a polymerization medium comprising monomer, diluent, and a catalyst system in a reactor, wherein the catalyst system comprises a Lewis acid and an initiator, thereby producing a reactor overflow; contacting the reactor overflow with a quenching agent; and The quenching of the reactor flooding is controlled to obtain a Mooney Relaxation Index (MRI) greater than about 2.5, thereby producing a quenched reactor flooding.

2. The method of claim 1, wherein the MRI is in the range of about 2.5 to about 4.

5.

3. The method of claim 1, wherein controlling comprises adjusting the amount of the quencher such that a molar ratio of the quencher to the Lewis acid is in a range of about 0.4 to about 0.

8.

4. The method of claim 3, wherein the molar ratio of the quencher to the Lewis acid is in the range of about 0.4 to about 0.

6.

5. The process of claim 1 wherein the reactor comprises an overhead blender and controlling comprises reducing the speed or shutting down the overhead blender during one or both of polymerization and quenching.

6. The process of claim 1, wherein the reactor outlet comprises a steam jacket and the controlling comprises heating the steam jacket so that the temperature at the reactor outlet is in the range of about -40°C to about 0°C.

7. The process according to claim 5, wherein the temperature at the reactor outlet is in the range of about -30°C to about -10°C.

8. The method of claim 1, wherein the reactor comprises an overhead blender and the controlling comprises (1) reducing the speed or shutting down the overhead blender during one or both of polymerization and quenching and (2) adjusting the amount of quenching agent such that the molar ratio of quenching agent to Lewis acid is in the range of about 0.4 to about 0.

8.

9. The method of claim 8, wherein the reactor outlet comprises a steam jacket, and wherein controlling further comprises (3) heating the steam jacket so that the temperature at the reactor outlet is in the range of about -40°C to about 0°C.

10. The method of claim 1, wherein the reactor outlet comprises a steam jacket, and the controlling comprises (1) heating the steam jacket so that the temperature at the reactor outlet is in the range of about -40°C to about 0°C, and (2) adjusting the amount of the quenching agent so that the molar ratio of the quenching agent to the Lewis acid is in the range of about 0.4 to about 0.

8.

11. The process of claim 1 , wherein the reactor comprises an overhead blender and a reactor outlet comprising a steam jacket, and the controlling comprises (1) reducing the speed or shutting down the overhead blender during one or both of polymerization and quenching, and (2) heating the steam jacket so that the temperature at the reactor outlet is in the range of about -40°C to about 0°C.

12. The method of claim 1, wherein the monomer is one or more of an olefin, an alpha-olefin, a disubstituted olefin, an isoolefin, a conjugated diene, a non-conjugated diene, styrene, a substituted styrene, and a vinyl ether.

13. The method of claim 1, wherein the monomer is isobutylene, isoprene, or a combination thereof.

14. The method of claim 1, wherein the monomer is present in the polymerization medium in an amount ranging from about 30 wt% to about 40 wt%.

15. The method of claim 1, wherein the diluent is one or more of a hydrocarbon, a halogenated hydrocarbon, and a chlorinated hydrocarbon.

16. The process of claim 1, wherein the diluent is present in the polymerization medium in an amount ranging from about 60 volume % to about 70 volume %.

17. The method according to claim 1, wherein the Lewis acid is one or more of aluminum trichloride, aluminum tribromide, ethylaluminum dichloride, ethylaluminum sesquichloride, diethylaluminum chloride, methylaluminum dichloride, methylaluminum sesquichloride and dimethylaluminum chloride.

18. The process of claim 1 wherein the Lewis acid is ethylaluminum dichloride.

19. The method according to claim 1, wherein the initiator is one or both of Bronsted acid, alkyl halide and hydrogen halide.

20. The method of claim 1, wherein the quencher is at least one alcohol.

21. The method of claim 1, wherein the quencher is triethylene glycol.

22. The process of claim 1, wherein the reactor is a continuous reactor.

23. The method of claim 1, further comprising: The polymer fraction is separated from the quenched reactor overflow.

24. The method of claim 1 wherein the monomers are isobutylene and isoprene and are polymerized to form polyisobutylene-co-isoprene.

25. The method of claim 24, further comprising halogenating the polyisobutylene-co-isoprene to form halogenated polyisobutylene-co-isoprene.

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