Abstract:
A process for producing a copolymer of an isoolefin and at least one other comonomer comprising the step of polymerizing a reaction mixture comprising an isoolefin, a catalyst and at least one of a cycloconjugated muitiolefin and an unconjugated cyclic olefin in the presence of an activator comprising a carbo cation producing species, a silica cation producing species and mixtures thereof. The process can be practiced using a slurry polymerization approach. One of the main benefits achieved with the present invention is the conversion of the monomers over a shorter period of time and higher percent conversion than when the activator is not used.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an improved cationic polymerisation process and a catalyst system therefor. 
     2. Description of the Prior Art 
     Polymers and copolymers of isobutylene are well known in the art. In particular, copolymers of isobutylene with conjugated muitiolefin have found wide acceptance in the rubber field. These polymers are generally termed in the art butyl rubber. The preparation of butyl rubber is described in U.S. Pat. No. 2.356,128 (Thomas et al.), the contents of which are incorporated herein by reference. 
     The term butyl rubber as used throughout this specification is intended to encompass copolymers made from the polymerization of a reaction mixture comprising an isoolefin having from 4 to 7 carbon atoms (e.g., isobutylene) and a conjugated multiolefin having from 4 to 14 carbon atoms (e.g., isoprene). Although these copolymers arc said to contain about 0.2 to about 15% combined multiolefin, in practice the butyl rubber polymers of commerce contain from about 0.6 to about 4.5 wt % of multiolefin; more specifically from about 0.1 to about 2 mole %, the remainder of the polymer being comprised of the isoolefin component. 
     Efforts to prepare isoolefin-multiolefin polymers of higher unsaturation have met with varying degrees of success. Where substantially gel-free polymers have been prepared containing more than about 5% multiolefin, the polymers have been of low number average molecular weight. This has been true even where these polymers had high viscosity average molecular weights. In general, however, the products formed by prior art processes either high in gel content or low in number average molecular weight are of little utility. In order to have practical commercial utility as a synthetic butyl rubber, the isobutylene-isoprene copolymers must be substantially gel-free and have a number average molecular weight of at least 120,000. 
     The problem associated with the relatively low unsaturation content of conventional butyl rubber is the correspondingly low number of crosslinking sites which can bond with another rubber. Also, the crosslinking behaviour of conventional butyl rubber is different than that of other highly unsaturated rubber. These properties of conventional butyl rubber result in a weak adhesive strength which is further decreased when exposed to external shock, vibration and the like. 
     Thus, isobutene-cyclopentadicnc copolymer has been proposed in the prior art as an alternative to conventional butyl rubber. Isobutene-cyclopentadiene copolymer has an improved adhesive strength as well as excellent gas barrier properties, even at high degrees of unsaturation. Further, while the unsaturation of the cyclopentadiene moiety in the copolymer is susceptible to attack by ozone and the like, since the unsaturation is pendant to the polymer backbone (i.e., it does not form part of the polymer backbone), the polymer backbone remains substantially unaffected. Thus, the aging properties of a vulcanizate made from the copolymer arc excellent and its improved other characteristics make it highly desirable for use in tires. 
     The general problem with prior art isobutene-cyclopentadiene copolymers is in the production thereof; particularly in commercial quantities. The specific problems include one or both of the following: 
     (i) maintaining the stability of the cyclopentadiene co-monomer for a period sufficient to effect co-polymerization (the co-monomer is normally unstable against heat); 
     (ii) as the degree of unsaturation increases, there is an increase in gel formation and a decrease in the molecular weight (Mw) of the copolymer. 
     The latter problem can be addressed by using a conventional solution polymerization approach. See, for example, one or more of: 
     U.S. Pat. No. 3,808,177 (Thaler et al.); 
     U.S. Pat. No. 3,856,763 (Thaler et al.) 
     U.S. Pat. No. 4,031,300 (Thaler et al.); and 
     U.S. Pat. No. 4,139,695 (Thaler et al.); the contents of which are hereby incorporated by reference. 
     The use of a solution polymerization approach to produce an isobutene-cyclopentadiene copolymer has been criticized in International Publication Number WO 97/05181 (Youn el al.), the contents of which are hereby incorporated by reference—see, for example, page 3, line 2 to page 4, line 20 of Youn et al. Indeed, the purported point of novelty taught by Youn et al. relates to a slurry polymerization approach. 
     Notwithstanding the prior art solution and slurry polymerization approaches for the production of isobutene-cyclopentadiene copolymers, there is still room for improvement. Specifically, it would be desirable to have a polymerization process for the production of an isobutene-cyclopentadiene copolymer which could be used with a slurry approach to produce a low (or negligible) gel content copolymer at relatively high conversion rates of the cyclopentadiene comonomer in a shortened period of time, thus improving catalyst efficiency which is low compared to state of the art butyl polymerizations. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to obviate or mitigate at least one of the above-identified disadvantages of the prior art. 
     It is another object of the present invention to provide an improved catalyst system for isoolefin copolymerization and terpolymerization. 
     It is another object of the present invention to provide an improved process for isoolefin copolymerization and terpolymerization. 
     Accordingly, in one its aspects, the present invention provides a slurry process for producing a copolymer of an isoolefin and at least one other comonomer comprising the step of polymerizing a reaction mixture comprising an isoolefin a catalyst and at least one of a cycloconjugated multiolefin and an unconjugated cyclic olefin in the presence of an activator comprising a carbo cation producing species, a silica cation producing species and mixtures thereof. 
     Thus, the present inventors have surprisingly and unexpectedly discovered that the use of a specific activator in this cationic polymerization process surprisingly and unexpectedly improves the process by exhibiting an improved conversion in less time while maintaining a desirable Mw. This is indeed surprising given the teachings of Kennedy et al. ( J. Macromol. Sci. Chem . A1(6). p. 977-993 (1967), the contents of which are hereby incorporated by reference) wherein tert-butyl chloride was used as chain transfer agent and resulted in a decrease of Mw. The present process is characterized by lack of a significant decrease of Mw, especially when the process is conducted in semi-batch mode. 
     One of the main benefits achieved with the present invention is the conversion of the monomers over a shorter period of time and higher percent conversion than when the activator is not used. Further, one or more of the following advantages may also accrue: 
     1. high conversion of a second comonomer in a shortened period of time; 
     2. a low or negligible gel content; 
     3. the ability to achieve useful results at temperatures in the range of from about −110° C. to about −80° C.; 
     Other advantages will be apparent to those of skill in the art. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention relates to a method of preparing a copolymer of an isoolefin and at least one of a cycloconjugated multiolefin and an unconjugated cyclic olefin. Of course, those of skill in the art will recognize that the products of the present process may be at least any one of: a copolymer of an isoolefin and a cycloconjugated multiolefin; a copolymer of an isoolefin and an unconjugated cyclic olefin; a terpolymer of an isoolefin, a cycloconjugated multiolefin and an unconjugated cyclic olefin; a terpolymer of an isoolefin and two (or more) different cycloconjugated multiolefins; and a terpolymer of an isoolefin and two (or more) different unconjugated cyclic olefins. 
     Preferably, the copolymer has a number average molecular weight about 30,000 to about 600,000, more preferably about 50,000 to about 400,000, still more preferably about 70,000 to about 350,000 and a mole % unsaturation of at least about 1 to about 45 mole %, more preferably at least about 1 to about 40 mole %, and most preferably the unsaturation is about 2-25%. 
     Preferably, the isoolefin suitable for use in the present process is a C 4 -C 10  hydrocarbon monomer. Non-limiting examples of suitable isoolefin may be selected from the group comprising isobutylene, 2-methyl-1-butene, 3-methyl-1-butene, 4-methyl-1-pentene and mixtures thereof. The preferred isoolefin is isobutylene. 
     Preferably, the cycloconjugated multiolefin suitable for use in the present process is a C 5 -C 20  hydrocarbon monomer having at least one pair of conjugated double bonds. The monomer may comprise a 5-membered ring structure. Non-limiting examples of suitable monomers including such a ring structure may be selected from the group comprising cyclopentadiene, 1-methylcyclopentadiene, 2-methylcyclopentadiene, 1,3-dimethylcyclopentadiene and mixtures thereof. Further, the monomer may comprise a 6-membered ring structure comprising a conjugated diene. Non-limiting examples of suitable monomers including such a ring structure may be selected from the group comprising 1,3-cyclohexadiene, 1-methyl-1,3-cyclohexadiene, 1-methylene-2-cyclohexene, 2-methyl-1,3-cyclohexadiene, 1,3-dimethyl-1,3-cyclohexadiene and mixtures thereof. 
     Indene and its derivatives may also be used. 
     Preferably, the unconjugated cyclic olefin suitable for use in the present process is a bicyclic containing an unsaturated bond. Non-limiting examples of suitable such monomers may be selected from the terpenes—e.g., β-pinene. 
     In a preferred embodiment, terpolymers of an isobutylene, a cyclo-conjugated diolefin and a third monomer (e.g., unconjugated terpenes) can be prepared according to the method embodied by the present process wherein these terpolymers have a number average molecular weight (Mn) of about 30,000 to about 600,000, more preferably about 50,000 to about 400,000 and stiff more preferably about 70,000 to about 350,000; and a mole % unsaturation of cyclopentadiene at least 1 to about 45 mole %, more preferably at least 1 to about 25 mole The total unsaturation from all comonomers and cyclopentadiene is preferably between 1 and 45 mole %, more preferably between 1 and 40 mole %, and most preferably between 1 and 30 mole %. 
     It is possible and preferred to practice the present process using a slurry polymerization approach. As is known in the art, the use of a slurry polymerization allows for higher conversions than for solution polymerization (e.g., 90% to 95% or more) without a concurrent increase in viscosity in the reaction mixture. 
     The slurry polymerization approach utilizes a diluent which is a non-solvent for the polymer product. The choice of diluent is within the purview of those of skill in the art. Preferably, the diluent is a polar diluent. The term polar diluent as used in the specification and claims, means liquids having a dielectric constant at 25° C. of less than about 20, more preferably less than about 17, most preferably less than about 10. These liquids however, preferably do not contain sulfur, oxygen or phosphorus in the molecule since compounds containing these elements will react with or otherwise deactivate the catalyst. 
     The preferred polar diluents are inert halogenated aliphatic hydrocarbons, more preferably halogenated paraffinic hydrocarbons and vinyl or vinyl idene halides, most preferably primary or secondary chlorinated paraffinic hydrocarbons. The term inert means that the cosolvent will not react with the catalyst or otherwise enter into the polymerization reaction. The halogenated hydrocarbon is preferably a C 1 -C 5  paraffinic hydrocarbon, more preferably a C 1 -C 2 , paraffin. The ratio of carbon atoms to halogen atoms in the polar diluent is preferably 5 or less. Preferably the halogen is chlorine. 
     Illustrative examples of these polar diluents are methylchloride, ethyl chloride, propyl chloride, methyl bromide, ethyl bromide, chloroform, methylene chloride, vinyl chloride, vinylidine chloride, dichloroethylene, etc. Preferably, the polar diluent is methyl chloride or ethyl chloride. 
     When using the slurry polymerization approach, any of the catalysts discussed above with respect to the solution polymerization approach may be used 
     In the practice of this invention, a catalyst is used. Preferably, in the slurry polymerization approach, the catalyst has the formula AlY 3  wherein Y is a halogen. The most preferred catalyst for use in the slurry approach is AlCl 3 . However, the use of aluminum catalysts in Ziegler-Natta polymerization process is well known and alternative choices of aluminum catalyst to he used in the present process are within the purview of a person skilled in the art. For example, the aluminum catalyst may comprise at least one compound having the formula: 
      (R) p AlY q   
     wherein R is selected from the group comprising a C 2 -C 10  alkyl group, a C 2 -C 10  alkoxyl group and a C 3 -C 20  cycloalkyl group, Y is a halogen and p+q is 3. More preferably, q is not 0. Possibly, the aluminum catalyst comprises a mixture of at least two of said compounds. 
     Preferably, p is a number in the range of from about 1 to about 2, and q is a number in the range of from about 1 to about 2. In a more preferred embodiment, p is 2 and q is 1. In another more preferred embodiment, p and q are 1.5. In yet another more preferred embodiment, p is 1 and q is 2. 
     Preferably, R is ethyl. 
     Of course, the halogen Y in the preferred formula for the aluminum catalyst may he selected from the group comprising bromide, chloride, iodide and astatine. The preferred halogen moiety is chloride. If two or more halogen moieties are present on the aluminum catalyst, it is preferred that they be the same. 
     Non-limiting examples of aluminum catalysts useful in the present invention may be selected from the group comprising diethyl aluminum chloride, ethyl aluminum dichloride, ethyl aluminum sesquichloride, methyl diethoxy aluminum, methylalumninum dichloride, isobutylaluminum dichloride, methylalumninum dibromide, ethylaluminum dibromide, benzylaluminum dichloride, phenylaluminum dichioride; xylylaluminum dichloride, toluylaluminum dichloride, butylaluminum dichloride, hexylaluminum dichloride, octylaluminum dichloride, cyclohexylaluminum dichloride and mixtures thereof. The preferred catalysts are methylaluminum dichloride, ethylaluminum dichloride, isobutylaluminum dichloride, dimethylaluminum chloride, diethylaluminum chloride, diisobutylaluminum chloride and mixtures thereof. As is known to those of skill in the art, if it is desired to utilize ethyl aluminum sesquichloride as the aluminum catalyst, it is possible to produce the cocatalyst by mixing equimolar amounts of diethyl aluminum chloride and ethyl aluminum dichloride. 
     Where an aluminum halide is used, it is preferably in the form of an homogeneous solution or submicron dispersion of catalyst particles, e.g., colloidal dispersion. Therefore, the catalyst is preferably dispersed or dissolved in a suitable catalyst solvent or mixtures of solvents. The catalyst solvent preferably is a polar solvent. 
     It is preferred the aluminum halide catalyst be in solution in the polar organic solvent prior to introduction of the catalyst to the reaction medium. 
     Use of the term solution with reference to the polar organic solvent/aluminum halide systems is intended to include both true solution and colloidal dispersions since they may exist concurrently in the same system. 
     The aluminum halide/polar solvent catalyst preferably comprises about 0.01 to about 2 wt. % aluminum halide, more preferably about 0.01 to about 1, most preferably 0.04 to about 0.8. 
     The hydrocarbylaluminum dilialide catalyst may be added neat or in solution. Preferably where a catalyst solvent is used, it is a liquid paraffin solvent or cycloparaffin solvent. It is advantageous though not necessary to use paraffins of low freezing point. Methylcyclohexanc is particularly useful since catalyst solutions of about 1% concentration do not freeze at −120° C. 
     The concentration of the catalyst is not critical. Very dilute catalyst solutions, however, are not desirable since substantial fractions of the catalyst may be deactivated by impurities. Very concentrated solutions are undesirable since at polymerization temperatures catalyst may be lost by freezing out of solution. 
     In carrying out the present process, those skilled in the art will be aware that only catalytic amounts of catalyst solution are required. Preferably, the volume ratio of monomer plus diluent to catalyst solution is about 100/1 to about 9/1, more preferably about 80/1 to about 10/1, most preferably about 50/1 to about 20/1. 
     It is desirable to conduct the reaction below about −80C, more preferably about 90C to 110C. 
     Specifically preferred embodiments of this slurry approach will be illustrated in the Examples hereinbelow. For more general information, see, for example, Youn et al., referred to and incorporated by reference hereinabove. 
     In the present process, use is made of an activator comprising a carbo cation producing species, a silica cation producing species and mixtures thereof. 
     Preferably, the activator is used in an amount in the range of from about 0.0005 to about 0.2, more preferably from about 0.001 to about 0.1, most preferably from about 0.002 to about 0.06, weight % based on the total weight of the monomers. 
     In one preferred embodiment, the activator is a carbon cation producing species having the formula: 
      R 1 —X 
     wherein R 1  is a C 1 -C 40  hydrocarbon, optionally substituted with one or more heteroatoms, and X is selected from the group comprising a halogen, —OH and —OR 2 , wherein R 2  is the same or different as R 1  and is a C 1 -C 40  hydrocarbon, optionally substituted with one or more heteroatoms. In one preferred embodiment, each of R 1  and R 2  is a C 1 -C 40  straight chain or branched alkyl group, optionally having one or more unsaturations. In another preferred embodiment, each of R 1  and R 2  is a substituted or unsubstituted C 5 -C 40  aryl group. In yet another embodiment, each of R 1  and R 2  is a substituted or unsubstituted C 3 -C 40  cycloalkyl group. Preferably, X is selected from the group comprising Cl, Br and I. 
     The more preferred embodiments of X may be selected from the group comprising Cl, OH and OCH 3 . 
     In another preferred embodiment, the activator has the formula: 
     
       
         X 1 —R—X 2   
       
     
     wherein R is a C 1 -C 40  hydrocarbon, optionally substituted with one or more heteroatoms, and X 1  and X 2  are the same or different and each is a halogen, —OH and —OR 3 , wherein R 3  is a C 1 -C 40  hydrocarbon, optionally substituted with one or more heteroatoms. 
     In one preferred embodiment, R is a C 1 -C 40  straight chain or branched alkyl group, optionally having one or more unsaturations. In another preferred embodiment, R is substituted or unsubstituted C 5 -C 40  aryl group. In yet another preferred embodiment, R is a substituted or unsubstituted C 3 -C 40  cycloalkyl group. 
     In one preferred embodiment, R 3  is a C 1 -C 40  straight chain or branched alkyl group, optionally having one or more unsaturations. In another preferred embodiment, R 3  is a substituted or unsubstituted C 5 -C 40  aryl group. In yet another preferred embodiment, R 3  is a substituted or unsubstituted C 3 -C 40  cycloalkyl group. 
     Preferably, X 1  and X 2  are selected from the group comprising Cl, Br and I, more preferably both X 1  and X 2  are Cl. 
     Non-limiting examples of activators which are useful in the present process as suitable carbo cation producing species include:                           
     wherein R is C 1 -C 40  hydrocarbon, optionally substituted with one or more heteroatoms,                           
     and cis and trans isomers of 
     
       
         CH 2 C—CH═CH—CH 2 Cl 
       
     
     In another preferred embodiment, the activator may be selected from the group comprising allyl chloride, tert-butylehloride, benzyl chloride, 4-methylbenzyl chloride and mixtures thereof. 
     In another preferred embodiment, the activator is a silica cation producing species having the formula: 
     
       
         R 4 R 5 R 6 SiX 
       
     
     wherein R 4 , R 5  and R 6  are the same or difference and each is a C 1 -C 40  hydrocarbon, optionally substitute d with one or more peteroatoms and X a halogen. In one preferred embodiment, each of R 4 , R 5  and R 6  is a C 1 -C 40  straight chain or branched alkyl group, optionally having one or more unsaturations. In another preferred embodiment, each of R 4 , R 5  and R 6  is a substituted or unsubstituted C 5 -C 40  aryl group. In yet another preferred embodiment, each of R 4 , R 5  and R 6  is a substituted or unsubstituted C 5 -C 40  cycloalkyl group. Preferably, X is selected from the group comprising Cl, Br and I, more preferably X is Cl. A preferred non-limiting example of a silica cation producing species is trimethyl silyl halide. 
    
    
     Embodiments of the present invention will now be described with reference to the following Examples which should not be construed as limiting the scope of the invention. 
     EXAMPLE 1 
     At −30° C., 0.0267 g AlCl 3  (purity 99.99% &lt;100 ppm H 2 O) was dissolved in 55.4 mL methylchloride (&lt;20 ppm H 2 O) to form a catalyst solution. The solution was stirred for 30 minutes at −30° C. and then cooled down to −95° C. 
     In a 500 mL 3-necked reaction flask equipped with an overhead stirrer, a reaction mixture consisting of 0.66 g cyclopentadiene, 38.5 mL isobutene and 161 mL methylchloride was stirred at −95° C. The temperature of the mixture was brought to −93° C. and the catalyst solution was added at once to start the polymerization. All temperature changes during the reaction are followed by a thermocouple. 
     After 20 minutes, the reaction was stopped by addition to the reaction mixture of 3 mL of a solution of NaOH in ethanol (1.0 wt. %). 
     The polymerization was carried out in a Braun dry box under dry nitrogen atmosphere (&lt;5 ppm H 2 O, &lt;20 ppm O 2 ). 
     Solvent, unreacted monomers and ethanol were removed under vacuum and the polymer yield was determined by gravimetry to be 16.3 wt. %. 
     By dissolving in hexane and reprecipitation from ethanol, the polymer was cleaned. After 3 days of drying in a vacuum oven at room temperature.the molecular weight, determined by GPC (UV-detection), was Mn=130000; Mw=195000, the cyclopentadiene content in the polymer was determined to 7.2 mol % by  1 H-NMR. 
     This Example represents a control reaction without addition of an accelerator, and thus is provided for comparative purposes only. 
     EXAMPLE 2 
     The methodology of Example 1 was repeated except that the reaction mixture consisted of 1.65 g cyclopentadiene, 37 mL isobutene and 161 mL, methylchloride. The polymer yield was 13.9 wt. %, the molecular weight if Mn=53000; Mw=130000 and the cyclopentadiene content in the polymer was 17.9 mol %. This Example represents a control reaction without addition of an accelerator, and thus is provided for comparative purposes only. 
     EXAMPLE 3 
     The methodology of Example 1 was repeated except that the reaction mixture consisted of 0.81 g methylcyclopentadiene, 38.5 mL isobutene and 161 mL methylchloride. The polymer a yield was 49.0 wt. %, the molecular weight is Mn=57000; Mw=327000 and the methylcyclopentadiene content in the polymer was 4.0 mol %. This Example represents a control reaction without addition of an accelerator, and thus is provided for comparative purposes only. 
     EXAMPLE 4 
     The methodology of Example 1 was repeated except that the reaction consisted of 0.33 g cyclopentadiene, 0.40 g methylcyclopentadiene, 38.5 mL isobutene and 161 mL methylchloride. The polymer yield was 25.8 wt. %, the molecular weight was Mn=52000; Mw=182000, the cyclopentadiene content in the polymer was 2.8 mol % and the methylcyclopentadiene content in the polymer was 3.5 mol %. This Example represents a control reaction without addition of an accelerator, and thus is provided for comparative purposes only. 
     EXAMPLE 5 
     The methodology of Example 1 was repeated except that 9.3 mg tert-butylchloride were added to the reaction mixture before starting the reaction. The polymer yield was 77.4 wt. %, the molecular weight was Mn 47000; Mw=109000 and the cyclopentadiene content in the polymer was 2.9 mol %. 
     EXAMPLE 6 
     The methodology of Example 5 was repeated except that 18.6 mg tert-butylchloride was added to the reaction mixture before starting the reaction. The polymer yield was 98.5 wt. %, the molecular weight was Mn=37000; Mw=75000 and the cyclopentadiene content in the polymer was 1.9 mol %. 
     EXAMPLE 7 
     The methodology of Example 5 was repeated except that 4.6 mg tert-butylchloride was added to the reaction mixture before starting the reaction. The polymer yield was 50.3 wt. %, the molecular weight was Mn=69000; Mw=134000 and the cyclopentadiene content in the polymer was 3.7 mol %. 
     EXAMPLE 8 
     The methodology of Example 3 was repeated except that 9.3 mg tert-butylchloride was added to the reaction mixture before starting the reaction. The polymer yield was 70.5 wt. %, the molecular weight was Mn=65000; Mw=310000 and the methylcyclopentadiene content in the polymer was 2.6 mol %. 
     EXAMPLE 9 
     The methodology of Example 4 was repeated except that 9.3 mg tert-butylchloride was added to the reaction mixture before starting the reaction. The polymer yield was 53.1 wt. %, the molecular weight was Mn=32000; Mw=120000. The cyclopentadiene content in the polymer was 1.8 mol % and the methylcyclopentadiene content in the polymer was 2.1 mol %. 
     EXAMPLE 10 
     The methodology of Example 5 was repeated except that 12.7 mg benzylchloride was added to the reaction mixture before starting the reaction. The polymer yield was 27.0 wt. %, the molecular weight was Mn=91000: Mw=176000 and the cyclopentadiene content in the polymer was 5.6 mol %. 
     EXAMPLE 11 
     The methodology of Example 5 was repeated except that 14.1 mg 4-methylbenzylchloride was added to the reaction mixture before starting the reaction. The polymer yield was 20.2 wt. %, the molecular weight was Mn=115000; Mw=185000 and the cyclopentadiene content in the polymer was 6.2 mol %. 
     EXAMPLE 12 
     The methodology of Example 5 was repeated except that 6.2 mg cis-1,4-dichloro-2-butene was added to the reaction mixture before starting the reaction. The polymer yield was 52.9 wt. %, the molecular weight was Mn=72000; Mw=263000 and the cyclopentadiene content in the polymer was 2.8 mol %. 
     EXAMPLE 13 
     The methodology of Example 5 was repeated except that 6.2 mg trans-1,4-dichloro-2-butene was added to the reaction mixture before starting the reaction. The polymer yield was 100 wt. %, the molecular weight was Mn=193000; Mw=1429000 and the cyclopentadiene content in the polymer was 2.0 mol %. 
     EXAMPLE 14 
     The methodology of Example 5 was repeated except that 15.1 mg 4-vinylbenzylchloride was added to the reaction mixture before starting the reaction. The polymer yield was 86.7 wt. %, the molecular weight was Mn=62000; Mw=140000 and the cyclopentadiene content in the polymer was 2.3 mol %. 
     EXAMPLE 15 
     The methodology of Example 5 was repeated except that 15.1 mg α,α′-dichloro-pxylene was added to the reaction mixture before starting the reaction. The polymer yield was 99.5 wt. %, to the molecular weight was Mn=84000; Mw=202000 and the cyclopentadiene content in the polymer was 2.1 mol %. 
     EXAMPLE 16 
     The methodology of Example 5 was repeated except that 9.7 mg α,α,α′,α′-tetramethyl-1,4-benzenedimethanol was added to the reaction mixture before starting the reaction. The polymer yield was 25.4 wt. %, the molecular weight was Mn=87000; Mw=215000 and the cyclopentadiene content in the polymer was 6.0 mol %. 
     EXAMPLE 17 
     At −30° C., 0.0267 g AlCl 3  (purity 99.99%, &lt;100 ppm H 2 O) were dissolved in 55.4 mL methylchloride (&lt;20 ppm H 2 O) to form the catalyst solution. The solution was stirred for 30 minutes at −30° C. and then cooled downed to −95° C. 
     In a 500 mL 4-necked reaction flask equipped with an overhead stirrer and two jacketed addition funnels, 150 mL of methylchloride was stirred at −93° C. After cooling down the addition funnels to −93° C., one was filled with 50 mL of the catalyst solution and the other was filled with 50 mL of a reaction solution consisting of 0.66 g cyclopentadiene, 38.5 mL isobutene and 11 mL methylchloride. The catalyst and reaction solutions were added to the reaction flask at a constant rate of 1.4 ml/min. All temperature changes during the reaction were followed with a thermocouple. 
     One minute after complete addition of the catalyst and reaction solutions, the reaction was slopped by adding 3 mL of a solution of NaOH in ethanol (1.0 wt. %) to the reaction mixture. 
     The polymerization was carried out in a Braun™ dry box under dry nitrogen atmosphere (&lt;5 ppm H 2 O, &lt;20 ppm O 2 ). 
     Solvent, unreacted monomers and ethanol were removed under vacuum and the polymer yield was determined by gravimetry to 12.3 wt. %. 
     By dissolving in hexane and reprecipitation from ethanol, the polymer was cleaned. After 3 days of drying in a vacuum oven at room temperature, the molecular weight, determined by GPC (Rl-detection), was Mn=101000; Mw=184000 and the cyclopentadiene content, determined by  1 H-NMR spectroscopy, in the polymer was 7.3 mol. %. 
     This Example represents the semicontinuous control reaction without addition of an accelerator, and thus is provided for comparative purposes only. 
     EXAMPLE 18 
     The methodology of Example 17 was repeated except that the reaction mixture consisted of 0.66 g cyclopentadiene, 38.5 mL isobutene, 9.3 mg tert-butylchloride and 11 mL methylchloride. The polymer yield was 73.6 wt. %, the molecular weight was Mn=75000; Mw=210000; and the cyclopentadiene content in the polymer was 2.5 mol-%. 
     EXAMPLE 19 
     The methodology of Example 17 was repeated except that the reaction mixture consisted of 0.33 g cyclopentadiene, 0.40 g methylcyclopentadiene, 38.5 mL isobutene and 11 mL methylchloride. The polymer yield was 26.5 wt %, the molecular weight was Mn=94000; Mw=198000; the cyclopentadiene content in the polymer was 2.6 mol-% and the methylcyclopentadiene content was 5.8 mol-%. 
     This Example represents the semicontinuous control reaction without addition of an accelerator, and thus is provided for comparative purposes only. 
     EXAMPLE 20 
     The methodology of Example 17 was repeated except that the reaction mixture consisted of 0.33 g cyclopentadiene, 0.40 g methylcyclopentadiene, 38.5 mL isobutene, 9.3 mg tert-butylchloride and 11 mL methylchloride. The polymer yield was 61.1 wt. %, the molecular weight was Mn=98000; Mw=205000; the cyclopentadiene content in the polymer was 1.3 mol-% and the methylcyclopentadiene content was 2.8 mol-%. 
     EXAMPLE 21 
     The methodology of Example 17 was repeated except that the reaction mixture consisted of 0.81 g methylcyclopentadiene, 38.5 mL isobutene and 11 mL methylchloride. The polymer yield was 26.7 wt. %, the molecular weight was Mn=151000; Mw=397000; and the methylcyclopentadiene content was 5.7 mol-%. 
     This Example represents the semicontinuous control reaction without addition of an accelerator, and thus is provided for comparative purposes only. 
     EXAMPLE 22 
     The methodology of Example 17 was repeated except that the reaction mixture consisted of 0.81 g methylcyclopentadiene, 38.5 mL isobutene, 9.3 mg tert-butylchloride and 11 mL methylchloride. The polymer yield was 56.3 wt. %, the molecular weight was Mn=135000; Mw365000; and the methylcyclopentadiene content was 2.8 mol-%. 
     In each of the foregoing Examples, the weight ratio of solvent to monomers was 8.4, the wt. % of the catalyst solution was 0.047, the weight ratio of the catalyst solution to the monomers was 1.96, the reaction temperature was −93° C. and the reaction time was 20 minutes in Examples 1-16 and 36 minutes in Examples 17-22. Various other parameters of the process of the foregoing Examples and various properties of the polymers produced in the Examples are provided in the attached tables (Note: PDI=polydispersity index). The results reported in the attached tables, illustrate advantages of the present process. Specifically, higher polymer yields and catalyst efficiencies are achieved using the accelerator (i.e., the activator) of the present process when compared to not using it. This is especially seen in Examples 17-22 where there is a lack of a significant decrease of Mw for Examples 18, 20 and 22 compared to Examples 17, 19 and 21, respectively. 
     While the invention has been described hereinabove with reference to various preferred embodiments and specific Examples, it will be clearly understood by those of skill in the art that modifications to and variations of the preferred embodiments and specific Examples are possible which do not depart from the spirit and scope of the present invention. Accordingly, it is contemplated that such modifications to and variations of the preferred embodiments and specific Examples are encompassed by the invention. 
     
       
         
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
               
               
                   
                   
                 Wt. % IB in 
                 Wt. % CP in 
                 Wt. % MeCP in 
                 wt.-% accelerator 
                   
               
               
                 Example 
                 Reaction 
                 monomer feed 
                 monomer fed 
                 Monomer feed 
                 in monomer feed 
                 Type of accelerator 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 Batch 
                 97.6 
                 2.4 
                 0 
                 0 
                 none 
               
               
                 2 
                 Batch 
                 94.2 
                 5.8 
                 0 
                 0 
                 none 
               
               
                 3 
                 Batch 
                 97.2 
                 0 
                 2.8 
                 0 
                 none 
               
               
                 4 
                 Batch 
                 97.5 
                 1.1 
                 1.4 
                 0 
                 none 
               
               
                 5 
                 Batch 
                 97.6 
                 2.4 
                 0 
                 0.032 
                 tert-butylchloride 
               
               
                 6 
                 Batch 
                 97.6 
                 2.4 
                 0 
                 0.065 
                 tert-butylchloride 
               
               
                 7 
                 Batch 
                 97.6 
                 2.4 
                 0 
                 0.016 
                 tert-butylchloride 
               
               
                 8 
                 Batch 
                 97.2 
                 0 
                 2.8 
                 0.032 
                 tert-butylchloride 
               
               
                 9 
                 Batch 
                 97.5 
                 1.1 
                 1.4 
                 0.032 
                 tert-butylchloride 
               
               
                 10 
                 Batch 
                 97.6 
                 2.4 
                 0 
                 0.044 
                 benzylchloride 
               
               
                 11 
                 Batch 
                 97.6 
                 2.4 
                 0 
                 0.049 
                 4-methylbenzylchloride 
               
               
                 12 
                 Batch 
                 97.6 
                 2.4 
                 0 
                 0.022 
                 cis-1,4-dichloro-2-butene 
               
               
                 13 
                 Batch 
                 97.6 
                 2.4 
                 0 
                 0.022 
                 trans-1,4-dichloro-2-butene 
               
               
                 14 
                 Batch 
                 97.6 
                 2.4 
                 0 
                 0.053 
                 4-vinylbenzylchloride 
               
               
                 15 
                 Batch 
                 97.6 
                 2.4 
                 0 
                 0.031 
                 α,α′-dichloro-p-xylene 
               
               
                 16 
                 Batch 
                 97.6 
                 2.4 
                 0 
                 0.035 
                 α,α,α′,α′-tetramethyl-1,4-benzenedimethanol 
               
               
                 17 
                 Semi 
                 97.6 
                 2.4 
                 0 
                 0 
                 none 
               
               
                 18 
                 Semi 
                 97.6 
                 2.4 
                 0 
                 0.032 
                 tert-butylchloride 
               
               
                 19 
                 Semi 
                 97.5 
                 1.1 
                 1.4 
                 0 
                 none 
               
               
                 20 
                 Semi 
                 97.5 
                 1.1 
                 1.4 
                 0.032 
                 tert-butylchloride 
               
               
                 21 
                 Semi 
                 97.2 
                 0 
                 2.8 
                 0 
                 none 
               
               
                 22 
                 Semi 
                 97.2 
                 0 
                 2.8 
                 0.032 
                 tert-butylchloride 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                   
                 Yield 
                 Catalyst efficiency 
                   
                   
                 Mol % CP in 
                 Mol % MeCP in 
                 Gel 
               
               
                 Example 
                 (%) 
                 (kg polymer/g cat) 
                 Mw 
                 PDI 
                 polymer 
                 polymer 
                 content 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 16.3 
                 0.17 
                 195000 
                 1.5 
                 7.2 
                 0.0 
                 not visible 
               
               
                 2 
                 13.9 
                 0.15 
                 130000 
                 2.5 
                 17.9 
                 0.0 
                 not visible 
               
               
                 3 
                 49.0 
                 0.52 
                 327000 
                 5.7 
                 0.0 
                 4.0 
                 not visible 
               
               
                 4 
                 25.8 
                 0.28 
                 182000 
                 3.5 
                 2.8 
                 3.5 
                 not visible 
               
               
                 5 
                 77.4 
                 0.82 
                 109000 
                 2.3 
                 2.9 
                 0.0 
                 not visible 
               
               
                 6 
                 98.5 
                 1.07 
                 75000 
                 2.0 
                 1.9 
                 0.0 
                 not visible 
               
               
                 7 
                 50.3 
                 0.54 
                 134000 
                 1.9 
                 3.7 
                 0.0 
                 not visible 
               
               
                 8 
                 70.5 
                 0.76 
                 310000 
                 4.8 
                 0.0 
                 2.6 
                 not visible 
               
               
                 9 
                 53.1 
                 0.57 
                 120000 
                 3.8 
                 1.8 
                 2.1 
                 not visible 
               
               
                 10 
                 27.0 
                 0.29 
                 176000 
                 1.9 
                 5.6 
                 0.0 
                 not visible 
               
               
                 11 
                 20.2 
                 0.22 
                 185000 
                 1.6 
                 6.2 
                 0.0 
                 not visible 
               
               
                 12 
                 52.9 
                 0.56 
                 263000 
                 3.7 
                 2.8 
                 0.0 
                 not visible 
               
               
                 13 
                 100.0 
                 1.07 
                 1429000 
                 7.4 
                 2.0 
                 0.0 
                 not visible 
               
               
                 14 
                 86.7 
                 0.92 
                 140000 
                 2.3 
                 2.3 
                 0.0 
                 not visible 
               
               
                 15 
                 99.5 
                 1.05 
                 202000 
                 2.4 
                 2.1 
                 0.0 
                 not visible 
               
               
                 16 
                 25.4 
                 0.27 
                 215000 
                 2.5 
                 6.0 
                 0.0 
                 not visible 
               
               
                 17 
                 12.3 
                 0.13 
                 184000 
                 1.8 
                 7.3 
                 0.0 
                 not visible 
               
               
                 18 
                 73.6 
                 0.78 
                 210000 
                 2.8 
                 2.5 
                 0.0 
                 not visible 
               
               
                 19 
                 26.5 
                 0.28 
                 198000 
                 2.1 
                 2.6 
                 5.8 
                 not visible 
               
               
                 20 
                 61.1 
                 0.65 
                 205000 
                 2.1 
                 1.3 
                 2.8 
                 not visible 
               
               
                 21 
                 26.7 
                 0.28 
                 397000 
                 2.6 
                 0.0 
                 5.7 
                 not visible 
               
               
                 22 
                 56.3 
                 0.60 
                 365000 
                 2.7 
                 0.0 
                 2.8 
                 not visible