CA1134996A - Isobutylene cyclodiolefin copolymers and terpolymers - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Substantially gel free, high molecular weight, high unsaturation copolymers of isobutylene and cycloconjugated dienes having a number average molecular weight of about 30,000 to about 90,000 and a mole %
of unsaturation of about 5 to about 45 are prepared by a polymerization in a homogeneous phase, wherein the catalyst which is a hydrocarbyl aluminum dihalide or aluminum halide type catalyst dissolved in an aliphatic type solvent is added to a mixture of the isobutylene, cyclo-conjugated diene, and an aliphatic cosolvent and the polymerization reaction is carried out at a temperature of about -80 to about -110°C.

Description

BACKGROUND OF TIIE IN~ENTION
The following U.S. pa-tents were Eound to be non-applicable to the instant application. They are: 2,356,12~;
3,356,661; 3,165,503; 3,466,268; 2,772,255; 3,242,147;
3,808,177; 3,080,337; 3,239,~95; 3,242,1~7; 2,521,359 as well as British Patent 1,036,618; Japanese Patents JA27417/68 and JA27416/68, and articles, _ d. Eng. Chem. 38,~17 (1946) and Ind. Eng. Chem. 42,2407 (1950).
. . . _ . _ GENERAL DESCRIPTION
_ _ The present invention teaches a methoclf~r forming unique and novel substantially gel-free copolymers of iso-butylene-cyclodiolefin and terpolymers of isobutylene~cyclo-diolefin and acyclic diolefin as well as multipolymers where more than one cyclodiolefin is present. The cyclodi-olefins are cyclopentadiene and methylcyclopentadiene or mixtures thereof. Preferred acyclic diolefins include iso-prene and piperylene, preferably isoprene. The unsaturation ,~
can be 5 to 45 mole ~, preferably 8 -to 40 mole ~ and Mn's can be 30,000 to 90,000, preferably 50,000-90,000, more pre-ferably 60,000-90,000, most preferably 70,000-90,000, wherein the physical properties and oil extensibility of these poly-mers are ~uite wlexpectedly acceptable for major tire appli-cations and other major applications, heretofore limited to sutyl rubber or halobutyl rubber having a minimum Mn of about 120,000. These new polymers of the present application clearly solve the problem of how to reduce the Mn oE an elas-tomer while maintaining its physical properties thereby effectively crea~ing a production cost savings.
The polymerization of the co- and terpolymers of the instant invention is carried out in the presence of not more thanabout40 wt. P~, based on the total monomers plus ~ ' :

~.~3~C~

cosolvent of a cosolvent which is a solvent for the polymer at the polymerization temperature and carrylng out the re-action at a temperature of about -~0 to -110. The catalyst is selected from the group consisting of aluminum halide and hydrocarbyl aluminum dihalide as disclosed in U.S. Patent 3,856,763 wherein the aluminum halide must be introduced into the reaction zone dissolved in a polar solvent.
The quantity of cosolvent used is varied with khe temperature in order to ef:Eectively control molecular weight.
The optimum cosolvent level is determined byselecting the minimum solvent-monomer ratio at which the copolymer to be prepared remains in solution at the polymerization tempera-ture.
To possess good physical properties, it is impera-tive that the copolymers and terpolymers of the instant in-vention incorporate critical levels of cyclic diolefin.
These critical levels are related to the Mn of the polymer.
For example, at Mn of 30,000 the minimum cyclodiolefin con-tent must be about 35 mole % (e.g. 37%), while at an Mn of 20 50,000 the minimum is about 20 mole % (e.g. 23%), at Mn's of 60,000 and 70,000 the critical minimum unsaturations are about 15% (e.~. 18 mole % and 10 mole %) cyclodiolefin re-spectively~ Non-cyclic diolefins may also be present in -~
these polymers but they have littIe effect on khe relation-ship of cyclodiolefin critical levels with Mn. The cyclodiolefins include cyclopentadiene and methylcyclopenta-diene or combinations of the two. Preferred acyclic diole- ;
fins include isoprene and piperylene, preferabl,y~ isoprene.
The co- and terpolymers of the instant invention can be used as a direct replacement for Butyl rubber applications.
.~ ~

J . _ 3 _ - -The blend compositions of the co- and terpolymers with oi]s and fillers show improvement in both physical and rheologlcal properties.
The blend compositions of the co- and terpolymers with natural rubber, SBR rubbers, EPDM terpolymers, polybutadiene, butyl rubbers and halo butyL rubbers and mixtures thereof have improved physical properties as well as ozone resistance.
In the accompanying drawings which are used to illustrate the invention:
Fig. I shows the relationship between critical homogenous polymerization temperature and diene content.
Fig. II shows the effect of polymerization temperature on number average molecular weight.
Fig. III shows the effect of cosolvent concentration on molecular weight.
Fig. IV shows the effect of polymerlzation temperature on total monomer conversion.
Fig. V shows catalyst efficiency as a function of cosol-vent concentration.
Fig. VI shows the relationship between tensile strength and Mn for a base reference--Butyl rubber.
Fig. VII shows the relationship betwen tensile strength and Mn for an isobutylene-isoprene copolymer, wherein the mole % of isoprene is ~aried.
Fig. VIII shows the relationship between tensile strength and Mn for a copolymer of isobutylene cyclopentadiene wherein `
the mole % of cyclopentadiene is varied.
Fig. IX shows the comparative relationship of mole ~ di-olefin (diolefin equivalent in terminology to diene) to Mn*
x 10 3 for copolymers of isobutylene-isoprene and isobutylene-cyclopentadiene, required to maintain maximum tensile strength at the reference level.

4 _ ~' ~'ig. X shows the rela-tionship be-tween mole % of cyclo-pentadiene of copolymer of isobutylene-cyclopentadiene and Log Mn* (the number average molecular weiyh-t required to maintain maximum tensile strength at the reference level).
One of the major properties of elastomers is the level of strength which can be achieved in its networks. Strengkh of elastomers is now known to be related to many survival pro-perties of rubber materials. These survival properties include, for example, rupture, tearing, fatigue, cracking, etc. Tensile strength is considered to be a simple but excellent measure of the overall survival characteristics of elastomers. Tensile strength could thus serve as a measure to establlsh a base reference of the survival properties of polyisobutylene. This now can be achieved through the medium of Bu-tyl rubbers. It can be demonstrated that tensile strength does not vary siyni-ficantly with the compositional variations available in Butyl rubbers (- 97.5 to -99.0 mole % isobutylene), and the values for tensile strength obtained on such networks could be con-sidered representative of crosslinked polyisobutylene.
The elastomers of this invention represent a range of compositional change of isobutylene star-ting at ~ 95 mole 5~.
According to the principles of this invention, the isobutylene units can be replaced by cyclopentadiene residues until the , . :.
isobutylene content has been reduced to about 55 mole %. If the sutyl rubbers serve as an appropriate reference for the strength of polyisobutylene then use of this - 4a ~

~1 ., . . ~: ; ;

1 reference can be continued in use to ~ollow the effects of

2 very great compositional changes both as to amount and type

3 represented by isobutylene isoprene and isobutylene-cyclo-

4 pentadiene copolymersq ~See Figure VI).
It was found that mod:iications of compo~itlons of 6 Butyl rubber by increasing the Lsoprene content at lower 7 number average molecular weights produced little efect on 8 the maximum achievable tensile strength relative to the 9 re~erences. (See Figure VII). Thus, a combination o re~
sults from copolymers with i~oprene contents in the range of 11 ~he Butyl rubbers of commerce (l.l9 to 2.68 mole ~/0), with 12 ~hose selected from the higher mole % unsatura~ion range o 13 the present inventlon continued to show minimal effect ~n 14 the maximum achievable ~ensile strength. Unexpectedly, the presence of cyclodiol~in such as cyclopentadiene in the C4-16 polymers produced marked co~po~ltional efeects on the maxi-7 mum achievable tensile strength. (See Flgure VIII and 18 FLgure IX). The ~ompositional effect of cyclopentadiene in 19 'the copolymers was found to be represen~d by the equation:
Mn* a aebX~ where ~h~ is the minimum number average molecu-~1 lar weight associated wlth reference s~rength values and a -22 number average molecular welght of the reference ("cross-23 linked" polyisobutylene) and equal to 120,000 and x ~ mole % ;-24 concentration of cyclopentadiene as determined in a s~andard~
ized test formulation. The value or b was found to be ~6 equal ~o -0O0377~ As the equation indicates, the required 27 number average molecular weight eo provide stren~th values 28 equivalent to the references decrease~ with increase of 29 cyclopentadiene content ln ~he copolymer. For example, at 8 and 4Q mole % cyclopentadiene`, the required num~er average 31 molecular weights were abou~ 89,000 and 27,000, respec~ively~
32 The terpolymer networks of isobutylene isoprene cyclopenta-'~ 3~

l diene show that the streng~h dependence on ~n i8 primarily 2 related to the cyclopentadiene content, 3 In order to obtain the desired num~er average 4 molecular weights of the co~ and terpolymer of the instant invention, the reaction must be carried out below -80C., 6 more preferably ~90C~ to ~110C. To obtain ~he deslred 7 number average molecular weight in a substantially gel-~ree 8 polymer, a homogeneous polymerization is req~ired and this 9 is achieved by car~ying out the reaction in a vehicIe which is a solvent for the copolymer at the reaction temperature~
11 ~he vehicle comprises predomi.nantly thc monomsrs to be poly- -12 merized in con~unction with an inert cosolvent or mixtures 13 of lnert cosolvents, The vehicle (monomers plus cosolvent) 14 must of course be liquid at the poly~erization temperature, It is essential in carrying out the process of 16 this invention tha~ ~he cosolvent comprise at least 5% by 7 volume and not ~ore than 40% by volume o~ the total cosol~
18 vent~monomer system. Preferably, 5 to 30 ~olume % cosol-19 vent is used, more preerably 5 to 20 volume %, most prefer~
ably 5 to 15 volume %~ e,g~, 10 volume %.
21 The optimum amount of cosolvent to be used is the 22 minimum amount necessary to avoid gelation. If too little 23 cosolvent i~ u8ed gelatlon of the product results. Too high 24 a level resuLt~ in undesirable lowering of number average molecular weight below the minimum desired ~n a~ indicated 26 in Figure X~
27 For the purposes of this invention, it is conve-28 nient to define the volume % of inert cosolvent as that cal-29 cu~ated based on the volume of monomers at about -78C, (dry ice temperature~ while ~he volume of cosolvent is determined 31 at 25C~ The volume % of cosolvent as calculated is uncor-~2 rected for volume changes and coollng of the rosolvent to - 6 ~

~ ~ - . . . :.. . , .. ... ;

reaction conditions~
The minimum quantity of a given cosolvent required to produce gel-free polymers is a function of the cosolvent, the conjugated cyclomultiolefin used and the polymerization tempera-ture. Having selected the composition of the blend of monorners and the cosolvent to be used the minimum quantity of cosolvent required is readily determined by carrying out the polymeriza-tion using varyiny amo~mts of cosolvent. The minimum quantity of cosolvent necessary is that amount required to maintain a homogeneous system; that is to prevent precipitation of polymer during polymerization.
The term "cosolvent" as used in the specification and claims means the inert solvent which, together with the monomer feed, comprises the vehicle for the reaction. The cosolvent and monomers must be mutually soluble and the blend of monomers plus cosolvent must be a solvent for the copolymer at the polymeri-zation temperature. The term "inert" means that the cosolvent will not react with the catalyst or otherwise enter into the polymerization reaction. The cosolvent must not contain sub-stituents in its molecule which will interfere with the poly-merization reaction. Aliphatic and cycloaliphatic hydrocarbons are suitable cosolvents. The preferred cosolvents are paraf~
finic hydrocarbons~ cycloaliphatic hydrocarbons and carbon disulfide and mixtures thereof. Preferably, the paraffinic hydrocarbon or cycloaliphatic hydrocarbon solvent is a C5-C10 hydrocarbon, more preferably a C5-C8 hydrocarbon. Illustrative examples of the hydrocarbon solvents are pentane, isopentane, methylp~entane, hexane, cyclohexane, methylcyclohexane, dimethyl-cyclohexane, heptane, isooctane, I,2,3,3-tetramethyl hexane, tetramethyl cyclohexane, etc. Generally any paraffin, whether normal, branched or cyclic which is a liquid under ~3~3~

polymerization conditions, may be used. The term "paraffin" as used in the specification and claim~ includes norma] paraffins, cycloparaffins and branched paraffirls. The preferred cosolvents are cycloparaffins or paraffinic mixtures containing cyclo-paraffins, preferably C6-C7 cyclopaxaffins (i.e. cyclohexane, methylcyclohexane), utilized at a~out S to 30 volume %, e.g., 10 to 20 volume %
It will be evident to those skilled in the art that since the monomers act as part of the solvent system for the polymer, the conversion level of the polymerization must not be so great as to result in precipitation of the copolymer as a result of depletion of solvent. Preferably, the conversion level is 2 to 30, more preferably about 3 to 15~, most pre~
ferably about S to about 13~, e.g. 10%.
in the practice of this invention, the catalyst is an aluminum halide or a hydrocarbyl aluminum dihalide. Where an aluminum halide is used, it must be in the form of a homogeneous solution or submicron dispersion of catalyst particles, e.g., colloidal dispersion. Therefore, the catalyst must be dispersed or dissolved in a suitable catalyst solvent or mixture of sol-vents. The catalyst solvent must be a polar solvent. Illustra- -tive examples of suitable aluminum halides are AlC13 and AlBr3.
The preferred aluminum halide catalyst is aluminum chloride.
It is essential in carrying out this invention that the aluminum halide catalyst be ln solution in the polar organic solvent prior to introduction of the catalyst to reaction medium.
Combining the polar organic solvent with the reaction medium and therea~ter adding the aluminum halide catalyst thereto will not result in the production of the desired Mn, high unsaturation polymers of this invention.

Use of the term "solution" with reference to the ~ 8 -~ .

, ~ 3 "! ~ .X

1 polar organic solvent/aluminum halide systems is intended to 2 include both true solutions and colloidal di~persio~s since 3 they may exist concu~rently in the same system~
4 The aluminum halide/polar solvent catalyst prefer~
ably comprises 0 Ol to 2 wt. ~/O alumlnum halide, more prefer-6 ably 0.05 to l, most preferably O.l to 0.8.
7 As previously noted, the catalyst ~a~ ~180 be a 8 hydrocarbylaluminum dihalide~ Where t~e hyd~ocarbylaluminum 9 halide is the catalyst, wherein the hydrocarbyl group can bç
a Cl-Cl8 straight chain, branched or cyclic g~oup Both cycloaliphatic and aromatic substituen~ OEan comprise the 12 hydrocarbyl radicalO Alkyl groups, espeeially lower alkyl 13 groups, e.g. Cl-C4, are preferred because of their general 14 availability and econ~my of use~ The halide can be bromine or chlorine, preferably chlorine. The term ~'dihallde" as 16 used in the specification and claims means dichlorîde or di-7 bromide.
18 Illustrative examples of these hydrocarbylalumlnu~
19 dihalides are methylaluminum dichloride9 ethylaluminum di-chloride, isobutylaluminum dichloride, methyla~uminum dibror21 mide, ethylaluminum dibromide, benzylaluminum dichloride, 22 phenylaluminum dichloride, xylaluminum dichlorida, toluyl-23 aluminum dichloride, bu~ylaluminum dichloride, hexylaluminum 24 dichloride, octylaluminum dichloride, cyclohq~ylaluminum di-chloride, etc~ The preferred catalysts ar~ m~thylalumlnum 26 d~chloride, ethylaluminum dichloride and isobuty~aluminum 27 dichlorider 28 The hydrocarbylaluminum dihalide catalyst may be addèd neat or in solution. Preferably where a ca~alys~ sol-ven is used, it is a liquid paraffin solvent or cycloparaf-3i fin solvent~ It is advan~ageous though not necess~ry t~ use 32 paraffins of low freezing polnt. Methylcyclohexane is - . ~ . , .. - . ., ~ ..

,, - ~ , ,. . ;, . .. .. .

"r~

1 particularly useful since cata:Lyst solutlons of about 1%
2 concentration do no~ freeze at -120C~
3 The concentration of the catalyst i8 not critical.
4 Very dilute catalyst solutions, however, are not desirable since substantial fractions of the catalyst may be deacti~
6 vated by impurities. Very concen~rated solutions ~re unde-7 sirable since at polymerizatiol temperatures catalyst may be 8 lost by freezlng out o~ solution.
9 In carrying out the polymerizatlon of this inven-tion, those ~killed in the art will be aware that only cata-11 lytic amounts o~ catalyst solution are required, Prefer-12 ably, the volume ratio of monomer plus cosolvent to catalyst 13 solution is lO0/l to 9/l, more preerably 80/l to lO/l, most 14 preferably 50/l to 20/11 The term "polax solvant" as used in the specifica-16 tion and clalms means non~aromatic, ~rganic solvents having 17 a dielectric constant at 25C. of at least 4, preferably 4 18 to 20, more preferably 6 to 17, most preferably 9 to 137 1~ These polar solvents, however, must no~ ~ontain sulfur~ oxy~
gen, phosphorus or nitrogen in the molecule since compounds 21 containing these elements will reac~ with Qr otherwise de-22 activa~e ~he catalyst.
23 The pre~erred p~lar solvents are inert~ halogenated 24 aliphatlc hydroearbons; more preferably halogenated paraf-finic hydrocarbons and vinyl or vinylidene halides1 most 26 preferably primary or secondary chlorina~ed paraffinic hy- -:
2~ drocarbons, The halogenated hydrocarbon is preerably a :
28 Cl-C5 paraffin hydrocarbon, more preferably a Cl~C2 paraf~
29 fin~ The rat:io of carbon atoms ~o hal~gen atoms in the polar sclvent: is preerably 5 or less. Preferably the halo~ :
31 gen is chlorine. ~ :
32 Illustrat~ve exa~ple~ of these polar organic 1 sol~ents are methylchloride, ethyl chlc~ride, propyl chlo-2 ride, methyl bromide, ethyl bromide, chloroform, methylene 3 chloride, vinyl chloride, vinylidene chloride, dichlvro-4 ethylene, etc~ Preferably, the polar solvent is methyl chloride or ethyl chloride~ Generally, any inert haloge-6 nated organic compound which i~ normally liquid under poly~
7 merization conditions and has a dielec~ric constant of a~
8 least 470 may be used.
9 In practicing the process of this invention, lt l~
essent~al that the polymerization be carried out in the 11 homogeneous ph~se without the precipi~ation o polymer~
12 Conventional slurry processes are inapplicable for the pre-13 paration of the high unsaturation polymers of this invention 14 since by their nature they result in polymer precipltation with gelation of the polymer as a consequenae.
16 The amount of cosolvent required in order to main-7 tain th~ polymer~zation reactants and product in solution 18 throughout the polymerization is a unction of the cyclo-9 pentadiene and its concentration in the monomer feedO The polymerization ~emperature a~ which precipit~tion of polymer 2~1 will occur is itself a unction of the amount of and type of 22 cosolvent and the cyclopentadiene.
23 The term "cri~ioal homogeneous polymerization tem-24 perature" a~ depicted i~ Figurç I as used in the sp2cifica-tion and claims means that polymeriza~ion ~empera~ure below 26 which precipitation of polymer will occur, when no cosol~
27 vent is included in the reaction mi~ture, i.e., the only 28 solvent for the reactants and product being ~he monomer 29 feed.
3~ Chalrac~erization o polymers prepared by bulk 31 polymerization9 i.e., withou~ cosolvent, shows ~hat the 32 polymers ~ormed are low in num~er average molecular weight 11 ~

1 (Mn?. In order to increase ~n, the lowering of polymeriza-2 tion temperature is an obvious expedient. However 7 in the 3 absence of cosolvent, the resu:Lt is gelation, 4 The problem of gelat-ion i5 obviated by the addi-S tion ofacosolvent which permits the lowering vf polymeriza-6 tion temperature bçlow the critical homogeneous polymeriza-7 tion temperature~ It has been found that a polymerization 8 temp~rature below -80 is necessary in order to achieve ~n 9 values of at least 30,000 or cyclopentadiene copolymer and 10 terpolymers. At least 5 volume % inert solven~ based on the 11 mcnomer feed is necessary in order to carry out the polymer-12 i~ation in solution at these low temperatures.
13 The necessity or utilizing low polymerization 14 tempe~atures is exemplified by Figure 2 which shows the ex- -ponential decrease in number average molecuLar weight with 16 increasing temperature~ The cri~icality of selectin~ the 17 proper quantity of cosolvent is demonstrated i~ Figure 3.
18 Too little coqolvent results in precipltation of the polymer 19 with reactor fouling or gelation, Fur~her benefi~s of low : 20 temperature and proper selective of appropriately low cosol-~1 vent concentration are demonstra~a~ in Figures 4 and 5, Figure 4 show~ that reactivity is favored by low tempera- :
23 tures (in addition to the molecular welght benefit)~ Figure ~4 5 shows tha~ catalyst efficiency is favored by low cosolvent concentration (in addition to the m~olecular weight benefit)~ ~
26 In practicing the process of this invention, one ~-2~ skilled in t~he art may proceed as follows in order to deter-28 mine the pre~erred reaction conditions. -~ First, ~ convenient polymerizatlon temperature be-low about -80C. is selected~ Next the desired feed compo-31 sition, i.eL monomers and ratio of isobu~ylene to cyclopen~ :
3? tadiene and the cosalvent to be u~ed are selected.
., ' ' ~

~ J~

1 Polymerization reac~ions are carried out using successively 2 grea~er amounts o~ solvent~ The ini~ial polymerlzation re-3 action is carried out using 5 volume % based on the total o~
4 monomer plus solvent of the cosolvent since lesser amounts will be inadequate~ In each successive run an additional 5 6 v~lume % is added~ The procedure is con~inued until the r~-7 action medium remaln~ clear throughou~ the reactlon. Tur-8 bidlty i8 indicative of precipitation of polymer which leads 9 to reactor fouling or gelation.
The polymer formed i8 charac~erized for Mn and 11 mole % unsaturation. Where a higher Mn is desired, it may 12 be achieved by either lowering the pol~merization tempera-13 ture or where possible using slightly less solvent than 14 determined by the above method3 e.g., 1-2 volume V/o less, provided ~hat turbidity does not occurO ~eduction of poly~
16 meriza~ion temperature may result in a g~ea~er cosolvent re~
17 quirementO Hence3 the aforegoing procedure of adding addl-18 tional solvent to the reaction medium must be continued un-19 til the reac~ion medium is again clear throughout the poly~
merization~
21 Where the mole % unsaturation is to be adjusted, 22 somewhat more or less of the cyclopentadiene i8 used depend-23 ing on whether a slightly higher or lower unsa~uration i8 24 desired~ Change in feed composition andlor conversion may 2$ require readjusting the cosolvent requirement. Generally, 26 increasing the cyclopen~adiene content of the monomer feed 2~ increases thP cosolvent requirement~
28 Th~ optimum ~eaction conditions are ~hosa which 2~ give the desired Mn a~ the highes~ (warmest) temperature for the desired unsaturation level~ Economic consideratiDns 31 dictate ~he use of the warmest temperature practical for 32 polymerization. Use of lower temperatures will neces~itate ~ 13 -.. ...... , .. , ~ . . . .. .. . ..... .

1 the use of greater amounts o~ cosolvent~
2 In an al~ernate approach to determine the nece~-3 sary quantity of cosolvent, the reactions are carried out in 4 bulk without using cosolvent~ For ea~h different cyclo-S pentadiene content ~onomer feed, polymerizations are carried 6 out at progressively lower temperatures until the critical 7 homogeneous polymeri~ation temperature or the feed composi-8 tion is determinedO The polymeriza~ion is repea~ed for dif-~ ferent feed compositions and the data obtained are the critical homogeneous polymerization ~emperatures as a func-11 tion of cyclopentadiene content of the feed~ A plot of 12 these data gives the critical homogeneous polymerization 13 temperature curve analogous to that of Figure I. The poly-14 mer formed is analyzed for cyclopentadiene conten~ and a determlnation is made of the correlation mole % unsatura~ion 16 in the polymer and Yolume % cyclopentadiene in the feed. The 17 polymer formed in bulk copolymerization o isobutylene and ~.
18 -cyolopentadiene i8 unsuitable for co~mercial use ~ince it 19 has a very low Mn In order to control the ~n of the poly~
20 mer between 30~000 ~o 90,0Q0, it is necessary to carry ou~ :
21 the polymerization at lower temperatures, e~g~, less than ~:
22 -80C., which requires the addition of cosolven~ to prevent ~
23 precipitation of polymer during polymerization. ~:
24 The quantity of solvent used should b~ kept to a ~:
25 minimum since ex~ess cosolvent results in the lowering of ~:
26 Mn. In determining ~he amount of solvent ~o be used, the .
27 monomer ~eed compQsition is determined. A convenient poly-28 merization temperature below o~0C~ is seleoted~ ~
The:minimum cosolvent requiremen~s for isobutylene ~ :
cyclopen~adiene may be determined by ca~rying out the poly-31 merization at the critical homogeneous polymerization tem~
32 perature for the isobutylene cyelopentadiene feedcomposi~n, ~ 3 1 terminating the polymerization by de~troying the catalyst and, with oonstant stirring, lowering the temperature of the 3 system to ~he desired polymerization temperature~ Tha poly-4 mer which, of cour~e3 i8 by de~Einition insoluble below ~he s critical homogeneou~ polymerization temperature will pre-6 cipitate out and the sy~tem wi:Ll appear turbid~ The polymer 7 will not be gelled, however, sLnce polymerization was terml-8 nated prior to preclpi~a~ion. The cosolv~nt ~elected is 9 then added in incremental amounts until the turbidity di~-lo appears. The quan~ity of solvent so added is a good ap~
11 proximation of the minimum solvent requirements for a given 12 isoolefinmultiolefin feed to be polymerized at a given tem~
13 pera~ure~
14 The t~rm "solution polyMerization" as ur~ed in the specificatlon and claims means a polymerization carried out 16 so that ~he polymer product remains di~solved throughout tbe 17 reactionO
18 Utilizing the process of this invention, it is now 19 possible to prepare such cyclodiene copolymers having as little as 5 mole % unsaturation and as high a~ 45 mole %
.
21 unsaturation 9 more preferably at least about 8 to about 40 ~2 mole % and more preferably ~he unsaturation is at least 23 about 20 mole % or polymers of Mn between 30,000 and 50~o~, 24 at leas~ about 15 mole % for Mn be~ween 50,000 and 60,000, at least about 10 mole % for Mn of about 60,000 an~ 90,000 26 and at least about 5 mole % for Mn between 70,000 and 27 90,000~ As a result of the relatively lower reactivity o 28 the olefin~c residueg copolym~rs having incorporated therein 29 about 2-4 mo:Le % c~clic diene are about as reaetive as Butyl rubber having an isoprene co~ten~ of about O~S to about 1.5 31 mole % and therefore require ultra accelera~ion for prac~ical :~
32 sulfur vulcanization. The higher unsaturation copQlymers .: - . , .
~ , -, ~ , . .
.....

1 and terpolymers 3 e.g., at least 5 mole %, preferably at 2 least 8 mole %9 of cyclopentadiene may be sulfur vulcanized 3 using the delayed action accele~ra~or cure systems.
4 In general, the eopolymers of this invention must not contain more ~han 45 mole ~, unsaturation. When the 6 multiole~in is a cyclic multiolefin above 45 mole % un~atu~
7 ration3 the glass tran~ition temperature of the polymer is 8 too high. As a result~ the polymers have poor low t~mpera-9 ture characteristics~ The ~erpolymers of ~hls invention 0 have about 5 to about 45 mole % cyclopentadiene unsaturation, 11 more preferably at least about 8 to about 40 mole %, and 12 most preferably the unsaturat~on is at least about 20 mole %
13 cyclopentadiene for polymers with ~h between 30,000 and 14 50,000, a~ least about 15 mole % for Mn between 50,000 and lS 60,000, a~ least about lO mole % for Mh between 60,000 and 16 70,000, and at least about .5 mole % for ~n between 70,000 17 and 90J0OO. The total unsaturation for i~oprene and cyclo~
18 pentadiene is preerably between 8 mol~ % and 45 mole %, 19 more preferably betwean 8 and 40 mole %, and most preferably between 12 and 30 mole %O
21 The products o this invention o~fer ~ number of 22 important advantagas over the commercially available Butyl 23 rubbers. In addi~ion to possessing superîor cold flow and 24 green s~rength properties whlle retaining the low air per-~5 meability and mechanical damping characteristics of conven-26 tional low unsaturation isoolef~n copolymers, the product~
27 of this invention offer greater versatility in vulcaniza~ion 28 techniques. Furthermore~ while the vulcanization o~ conven-~ ~ional isoolefin-multiolefin copolymers requires the u~e of ultra-accelerator type cures, e~gD, thiuram (Tuads) or ii-31 thiocarbamates (Tellurac), th¢ products of this invention 32 may be vulcanized using the thiazole, e.g., mercaptobenzo~

- . . - , . - , 1 thiazole~ type cure~ currently used in the vulcanization of 2 general purpose rubbers, e.g~, natural rubber, SBR, poly-3 butadiene, etc. Because of cert:ain ~actors o~' which pre-4 mature vulcanization (scorch) i~ a prime example, modern practice has tended t~wards the use of a ~p~cial class of 6 thiazoles called delayed action accelerators, These delayed 7 action accelera~ors permit ~he processing o~ the compounded 8 rubber (including vulcanizing agen~s) at elevated tempera-~ ~ure for a predetermined p~riod of time before vulcanization commenees. Such cure techniques are not po~ible with con-11 ventional isoolefin copolymers, The delayed action a~cele-12 rator9 ar~9 however, used advantageously in ~he vulcaniza-i3 tion of the isoolein capolymers of ~hls inven~ion~
14 The delayed action accelerators suit~le for use in vulcanizing the product~ of this i~ven~ion include the 16 benzathiole sulfenaLmides having the general formulao ~8 / C ~ / S
19 ~ C
S-X
20l ~c// \ND

~3 wherein X is an amino group~ The amino grouLp is mono~ or 24 diorganosubstituted and may be cyclic including heterocyclice For example, X may be ~ ~ or ~ N-R2 where Rl is H or R

26 and R is organo or cycloorg~no, R2 is a divalent organo 27 radical~ Illustrative examples of X are cyelohe~ylamino, 28 tertiary butyl am~no, diisopropyl amino, dicyclohexyl amino, pentamethylene~2mino, morpholino, 2-(2,6^dimethyl morpho-lino), etc. Speciflc illustr~tivs examples of these sulfen-31 amides are NgN~diet,hylbenzo~hiazole-2-sulfenamlde, N-N-di-32 isopropyl ben~othiazole-2~sul~enamide, N-tertiary butyl ~ 17 -- .

benzothiazole-2-slllfenamlcle, N-cyclohexyl benzothiazole~2-sulfenamide, N,N-dicyclohexyl benzothiazole 2-sulfenamide, 2-(morpholino) benzothiazole sulfenamide, 2-(2,6-dimethyl morpholino) benzothiazole sulfenamicle, 2-piperdinyl benzo--thiazole sulfenamide. In general, any benzothiazole sul~en-amide may be used as a delayed action accelerator for the sulfur vulcaniza-tion of the polymer oE this invention.
The delayed action accelerator is incorporated into the vulcanizable polymer composition at preferably 0.1 to

5 wt. % based on the polymer; more preferably 0.25 -to 3.5;
most preferably 0.5 to 3.0 wt. %, e.c~. 0.5 to 2.5 wt. %.
It is, of course, obvious -to those skilled in the art that the delayed action cures are sulfur cures and sul-fur must be incorporated into the polymer blend either as elemental sulfur or as nonelemental sulfur. Suitable non-elemental sulfur is in the form of those compounds which will release sulfur to the polymer under vulcanization con-ditions. For a description of these nonelemental sulfur compounds, generally, see Vulcanization of Elastomers, Ch. 4, J.C. Ambelang, Reinhold, New York 1964. Illustrative examples of these nonelemental sulfur compounds are dimor-pholvinyl disulfide and alkyl phenol disulfides. The term "sulfur donor" as used hereinafter in the specification and claims means elemental sulfur as well as the aforementioned nonelemental sulfur compounds. The ~uantity of sulfur donor required for vulcanization is well known to those skilled in the art. Where the sulfur donor is elemental sulfur, it is incorporated into the polymer at 0.1 to 5 wt. % based on the polymer; more preferably 0.25 to 3.5 wt. %; most preferably 0.5 to 3.0 wt. %, e.g., 0.5 to 2.5 wt. %. Where the sulEur donor is a nonelemental sulur compound, it is incorporated at a wt. % of about three ~, , . ~
.
.: :
, : ~

1 ~imes that required for elemental sulfur. The term "nonele-2 mental sulfur compounds" means organic compounds containing 3 sulfur and capable of donating the sulfur to a vulcanization 4 rea~tion, e.g~, disulfides and polysul~ides.
S The delayed action accelerator~ may be modi~ied by

6 retarders and activators which will respectively retard or

7 activate the sulfur vulcan~zation. The addition o~ the

8 retarder will further delay the time at which vulcanization

9 occurs while ~he ac~ivator will cause vulcanization ~o occur sooner, e.g., shorter delay time.
11 The retarders suitable for use in the practice of 12 this invention includes organic compounds having a pKa f 13 about 2 to less tha~ 7; preferably about 3 to abou~ 6.5;
14 more preferably abou~ 4 ~o about 6, e.g., 5, The t~rm PKa is the dissociation c~nstant as measured in aprotic sol-16 vents, see for example ~ vents NBS Monograph 105, August 1968.
18 The ac~ivators suitable for use in the practice o~
19 this in~ention are metallie oxides, hydroxides and alkoxides ~0 o~ &roups IA and IIA me~als of the Periodic Table of Elew 21 ments and organic compounds hav~ng a PKa ~ about 8 to about ~2~ 14, preferably about 9 to about 12; more preerably about 23 9 . 5 to abou~ 11, e ~ g, 10 .
24 Illustrative exa~ples ~f retarders are N-nitroso 2j5 diphenylamine, N-cyclohexyl thiophthalamideg phthallc anhy-~6 d~ide, salicyc:lic aeid, benzoic acid, etc~ Generally, the 27 preferred retalrders are nitroso compoundsg phthalimides, ?8 anhydrides ancl acids, 29 Illustrative examples o~ activator$ are MgO, di-~ phenylguanidine, hexane-l-amine7 l,~-hexane diamine, sodium 31 methoxide, etcO The preferred ac~iva~ors are guanidines 32 and amines.

. :
:, . ~ . ..

l The retarders and activators are preferably incor-2 ported into the polymer at 0.1 to 5 wt. %; more preferably 3 0.25 ~o 3~5 wt. %; mo~t preera~bly 0.5 to 3.0 wt. %, e.g., ~ 0.5 to 2.5 wt. %.
These copolymers of isoolefin3 and cyclodienes, 6 e.g., isobu~ylene and cyclopent,adiene possess markedly im-7 p~oved resistance to degradation by ozone over the acy~lic 8 diene copolymers. Althollgh it has been postulated ~hat ~uch 9 copolymers would have such improved proper~ie8 as a result lO of having the unsaturation located in a side chain rather ~ -ll than in the backbone~ it has heretofore not been possible to 12 prepare substantially gel-free isoolefin-cyclodiene copoly~
13 mers having number average molecular weigh~ below about 14 90,000 which are commercially acceptable as direct replace~
ments ~or Butyl rubber.
16 The highly unsaturated polymers of this invention l7 are subs~antially as impermeable to air as are~commercial l8 low ùnsaturates, e,g" 1.5 mole % Butyl rubbersO Surpris-19 ingly, isoolein copolymers af CPD or terpolymers of an iso-20 012fin CPD and isoprene are less permeable to air at the 21 higher unsatura~ion level~ than is the low unsatura~ion 22 Butyl rubber of commerceO
23 The term "substantially ~el-free" as used in the 24 specification and claims means copolymers containing less 2S tha~ 2 wt~ % ~el; more preferably less ~an 1% gel, e~gO9 26 1/2% gel. The ~erm '1D#!l~ wherein ~ ls an integer means the 27 volume % cyclopentadiene in a monom~r mixture, wherein D
28 represent~ cyclopen~ad~ene and the integer is ~he volume %
diene.
~ The copolymers and terpolymers of the instant in~
3l vention can be readily blended with other rubber~ for modi-32 ~ication o physical and chemical properties by ~echniqu2s ~, ~r "~.b (~

1 well known in the art~ These o~her rubbers are ~elected 2 from the group consisting of non-polar crystallizable -rub-3 bers ~i.e. crystallization either included by low tempera-d ~ure or strain or a mix~ure thereof~, polar crystallizable rubbers, non-polar, non-crystallizable rubbers, and polar 6 non-crystallizable rubbers. These rubbers are contained in 7 the blend cOmpQSitiOnS at a concentration level o 5 to 900 8 parts by weight per lO0 parts o~ the polymer, more pre~erably ~ 25 to 500 and most pre~erably 50 t~ 300O Typical, but non~
limiting examples of each class are: non~pola~ crystalllæ-11 able rubbers, natural rubber, low isoprene Butyl rubbers;
12 polar crystallizable rubbers polychloroprene rubberg (i.,e"
13 the neoprene types), non~polar non-crystallizable rubbers-14 styrene butadiene copolymers, polybutadienes and more highly unsa~ura~ed Bu~yl ru~bers; and polar non-crystallizable rub-16 bers~bu~adiene acrylonitrile copolymers.
7 The fillers employed in the presen~ inven~ion are 18 selected from the group consisting of carbon blacks, silica, 19 talcs5 ground calcium carbonate, water precipitated calcium carbonata9 or delaminated, calcined or hydrated clays and ~1 mixtures thereof~ These fillers are inco'rporated into the 22 blend composition at 5 to 350 parts by weight per hundred 23 parts o polymer9 more pre~erably at 25 ~o 350, and most 24 preferably at 50 to 300O Typically, these filler~ have a 2s particle size of 0.03 to 20 microns, more preferably 0.3 to ~6 10, and mos~ preferably abou~ 0.5 to about 10~ The oil ab~
27 sorp~ion as me,asured by gr~ms of oil absorbed ~y 100 grams 2~ of filler is lO to lO0, more preferably 10 to 85 and most ~Y preferably 10 to 75.
~ The oils employed in the present invention are 31 non-polar process oils ha~ing le~s than 2 wt. % poIar type 3? compounds as mea~ured by molecular type clay gel analysis.

, ~

1 These oils are selected from paraffillics ASTM Type 104B a~
2 defined in ASTM~D~2226-70, aromatics ASTM Type 102 or naph-3 thenics ASTM Type 104A, wherein the oil has a flash polnt 4 by the Cleveland open cup of at least 350F., a pour point Qf less than 40~., a viscosity o~ 70 to 3000 ~.squ.'~ at 6 100F. and a number average molecular weight of 300 to 1000, 7 and more preferably 300 to 750. The preerréd proces~ oils 8 are paraffinics.
9 The oils are incorporated into thç blend composi~
tion at a concentration level of 5 to ~00 part~ by weight 11 pqr hundred parts o~ polymer; more preferably a~ 25 to 150, 12 and mo~t preferabïy at 50 to 150.
13 Other plast~cizers suitable for u~e in the present 14 invention are medium viscosity ester plasticizers for spe-1~ cial high eficiency in increaslng resilience particularly 16 at low temperature. Some examples 9 which are not intended 17 to be limiting in scope are dioctyl phthalate, dioctyl aze-l8 late, dioctyl sebacate or dibutyl phthalate, The ester 19 plasticizer is incorporated into the blend composition at a çoncentration level ~ 5 to 100 parts by weight per hundred 21 of pol~mer, more pre~erably 5 to 759 and most p~e~erably 5 2? to 50~
23 The practice of ~his invention can i~volve batch 24 or `continuous polymeriæations either isothermal or mULti-?5 temperature. ContinuQus polyme~ization is preferred since 26 it is more co~venient for commercial operation and gives 2~ m~re unifonm (homogeneous) pro~ucts. Molecular weight dis 28 tributions ~Mw/~n) are pre~erably betwee~ 2.0 and 20.
DETAILED DESCRIPTION
~ The advantages of the physical proper~lss of ~he 31 co~position~ o~ the present inventicn can be more readily 32 appreciated by reference to the ~ollowing examples andtable.

, . ~ .
- . . , -, . i. ~ ~

a~

The quantlties of reactants utilized in the preparation of these copolymers and terpolymers were measured as volume at -78C. Cosolvent (MCH) was measured at 25 C.

~,.
'c' .~ . .

1 Monomer mixes comprisi.ng varylng quantities of 2 isobutylene and eyclopentadiene and in some cases isoprene 3 also, were polymerized in the presence of an appropriate 4 quantity of methylcyclohexane (MCH) cosolvent. The polymer-S izations were initiated using an 0~061M 801ution of ethyl-6 aluminum dichloride ~EADC~ in MCH (volume measured at 25C.) 7 added at a rate such as to maintain th~ reactor temperature 8 to within 2C~ of the indicated polymerization temperature~
9 In some instances small quantities of an 0.031M solution of lo HCl in MCH (volume measured at 78C.) were added to the 11 reactor wherein the HCl serves as a cocatalyst for the poly-12 ~erizationO All polymeriza~ions were conducted in a dry 13 inert atmosphere~ The reactions were carried out for the 14 indicated time period at which time they were terminated by the addition of a 3mall quantity of cold 10% propanol in~
16 pentane~ The reactor solutions were then treated briefly 17 with gaseous ~H3 and coagula~ed by pouring them into hot 18 methanol'containing an antloxidant~ Polymer samples were 19 dried in vacuo at about 60C. Polymerization details or some rspresentative producks are presented in Tabl0 I, ~ 24 ~

d~L d~ f ~ " 7) "

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l ~d O Ç~ O ~ ~ oo ao o cr~ o o o F~ ~ a ~,,~,, .,, ,,"_"_,,,_, V
.
. ~ o~O~o~o~oo~o Pq . ~ ~ o o c~ o o~ ~ o o ~ ,~
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~; ~ ~_~ ~IIIIIIIIIII~`I ~IS~ ~.

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1 EXAMPLE 2 ; MAXIMUM ~TT~INABLE TENSILE 5TRENGTH
2 The maximum attainable ~ensile s~reng~h for a 3 given elastomer with a given number average molecular weight 4 in a given compound formulation i~ determined as follows.
After selection of a suitable curlng temperature, one vul-6 canizes ~he compound at several varying time~ o~ curing~
7 Tensile strengths and crosslink densities are measured on 8 ~he resultant samples. The directlon in which the level o~
9 the tensile strength trends with changing crosslink density is notedD Further curing times are ~hen employed to allow 11 amplifica~ion of ~he trend until a maximum in the tensile 12 strength level is obtainedO This is the maximum attainable 13 tensile strength ~or the material in question. The strength 4 is dependent on the number average molecular weigh~ ~f the original polymer and the cros~linke density o~ the speci~ic 16 vulcanizate. The crosslink density is virtually independe~t 17 of the choice of curing temperature provided extreme high 18 temperatur~s and extreme duration of CULing times are 19 avoided~ Such extremes can lead to a reversion in ~he crosslinking resultin~ ultimately in a process o~ "devulca-21 nization"~
22 Some examples of the data developed to appralse 23 the maxlmum attalnable tensile strength in the pr~s~nt in-24 stance for two copolymers and one terpol~mer composition ~ :
are given as follows:

w 26 -~ o ~ o o .~ ~ ~S> ~ ~D ~
q~ . ~ ~ ~ ~1 _I ~1 U~
~ ~ ~ E~
o ~1 ~1 ~o .~
,~
u~ C) O a~
~ a~
o ~c . . . . C3 u~ ~ ~ ~
,( o o .,~

~4 5~1 ~' . ~ c~J ~ o IJ ~q ~
~ ., a~ ~d P~ C) o o P~O ~ ~
H ~ O O 4-~ .C '`
_I
X ~ O C`l o~
O
P _ ~ C
5~
C~
.~ ,~

O a),~

o , ~
U~ ~ ~1 _1 11.,.1 ~ q3 E~

O O O h tdQ~
Q ~ o r rlV ~ ~ I ~~ I t ~ O O 1 P~ ~1 ~ 00 ~ O
X c~ 5 - ~7 -.
. . , , , ~

This me-thod was utilized to determine the maximum tensiles for the various types of co- and terpolymers as a function of unsaturation and Mn. The data are presented in Figures VI, VII ~nd VIII.
The compound formulation used to prepare the vulcarl-izates for test of these experimental elastomers was as follows: polymer 100, zinc stearate 1.65, H~F* carbon b]ack 60, hydrocarbon plasticizer oil (Flexon 8~5*, ASTM Type ~) 20, antioxidant (Thermaflex A*) 1.11, zinc oxide 5, sulfur 2.5, sulfenamide accelerator (Santocure NS*) 0.75. For the compositions containing the "crosslinkable polyisobutylenes"
(i.e., the isoprene copolymers with unsaturations in the range of the Butyl rubbers - 1.19 to 2.68 mole percent) the formulation was modified with respect to the curative system.
The accelerator (Santocure NS*) was replaced by the ultra-accelerator combination, Tellurac* plus Altax*, both at 1.0 phr. The sulfur content was reduced to 1.5 phr. These modi-fications were in keeping with the reduced crosslinking capabilities of the indicated isoprene copolymers.
The compound formulation chosen for test of the experimental elastomers was selected on the basis that it represents a practical system with the added attra~tive economic and commerical feature of being relatively extended in terms of oil plasticizer and carbon black content.
However, this test formulation can be varied quite broadly to achieve properties at specific levels related to some end use. Relative to the maximuln attainable tensile strength, the trend~. that would be observed with changes in test formu-lations would be consistent with information well known in the art. Examples of such trends are given as follows.

Changing the concentration of carbon black in either direc-tion from the 60 phr level would entail a reduction in the *Trade ~ark 1 tensile strength. Changlng the type of carbon black would 2 affeç~ the tensile strength relative to the particle siæe of 3 the black. A change to a carbon black o~ large par~icle 4 size would result in a reduction in the tensile strength, A
change to a carbon black of finer particle ~ize would result 6 in an increase in the tensile ~t:rength. Oil plasticizers of 7 l~w to medium viscosity general3.y reduce tensile strength as 8 the concentration is increased. Very viscous or r~sinous 9 liquid materials in the formulation tend ~o increase the tensile strength. This is also true of resin~3. The eura-11 tive system used for preparation of the vulcanlzates can 12 afect the maximum a~ainable tensile strength. As a broad 13 general rule, the simpler the crosslink a~ the juncture 14 point which results from a given curatlve system, the lower the tensile strength. Tensile strengths for e~ample tend to 16 increase as the bond simplicity dacreases from C-C~ C-S~C, 7 C-S2-C3 C~S3~C, etc. and S3~. As practical examples~ a 18 peroxide cure would give a simple crosslink juncture ~G-C)~
19 Next in line of reduced bond simplicity would be a single sulfur atom ~uncture (Sl) resulting ~rom curing a formula~
21 tion with relatively high accelerator and l~w sul~ur con~
22 ten~s. Conversely, curing with 'low accelerator and hi~h 23 sulfur contents results in a complex type of bond (S3+~o 24 Ma~ima in curves relating tensile strength to crosslink density are evident in ~he results of Gee3, Flory, 26 Rabjohn and Shafer4 and Dudek and Bueche~
27 The isoole~ins which can be employed in the instant 28 inven~ion are selec~ed from the group comprising isobutylene~
29 2~methyl-1-bu~ene, 3-methyl-1-butene or 4-methyl~l-pen~ene, wherein lsobut~ylene is preferred. The conjuga~ed dienes 31 wh~ch can be e~ployed in the instant invention are ~elected 32 from ~he group comprising isoprene, piperylene, 2-3 dimethyl `;`, 1 .` . .

1 butadiene, 2 5 dimethyl hexadl-2,4~ene, cyclopentadiene, 2 cyclohexadiene or methyl cyclohexadiene and mixtures thereof, 3 wherein isoprene, cyclopentadiene or methyl cyclopentadiene 4 and mlxtures thereof are preferred.
S REFERENCES
6 1. P~J. Flory and JO Rehner, J,. ChemO Phys., Il, 512, 521 7 (19~3)o 8 29 P.J. Flory, Ind. Eng. Chem., 38~ 417 (1946~o 9 3. G9 Gee, J. Polymer Sci~, , 451 (1947).
4, P.~. Flory, N. Rabjohn and M~C. Shaffer, J. Polymer Sico~
ll 4~ 435 (1~49~
12 5. T.J. ~udek and F. Bueche, J. Appl. Polymer Scio ~ 8~ 555 13 (1964~o 14 Since many modifications and variations of thls invention ~ay be made without depar~ing from ~he spiri~ or 16 scope of the. invention thereof, it is not intended to limit 17 the spirit or scope thereof to the specific examples thereo~O

~ 30 ~

Claims (41)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A substantially gel free copolymer consisting of a major portion of an isoolefin having about 4 to about 10 carbon atoms and about 5 to about 45 mole % of one cyclic conjugated diene of about 5 to about 9 carbon atoms, wherein said cyclic conjugated diene is selected from the group consisting of cyclopentadiene or methylcyclopentadiene, said copolymer having an ?n of about 30,000 to less than 90,000.

2. The copolymer of claim 1, wherein the isoolefin is iso-butylene, 2-methyl-1-butene, 3-methyl-1-butene or 4-methyl-1-pentene.

3. The copolymer of claim 1, wherein the isoolefin is iso-butylene and the diene is cyclopentadiene.

4. The copolymer of claim 1, wherein the cyclic conjugated diene content is from about 10 to 45 mole %.

5. A substantially gel free copolymer consisting of a major portion of an isoolefin having about 4 to about 10 carbon atoms and from about 20 to 45 mole % of a cyclic conjugated diene having about 5 to about 9 carbon atoms, said cyclic conjugated diene selected from the group consisting of cyclopentadiene or methyl-cyclopentadiene, said copolymer having an ?n of about 30,000 to about 50,000.

6. The copolymer of claim 5, wherein the isoolefin is iso-butylene, 2-methyl-1-butene, 3-methyl-1-butene or 4-methyl-1-pentene.

7. The copolymer of claim 5, wherein the isoolefin is iso-butylene and the diene is cyclopentadiene.

8. A substantially gel free copolymer consisting of a major portion of an isoolefin having about 4 to about 10 carbon atoms and from about 15 to 45 mole % of a cyclic conjugated diene having about 5 to about 9 carbon atoms, said cyclic conjugated diene selected from the group consisting of cyclopentadiene and methyl-cyclopentadiene, said copolymer having an Mn of about 50,000 -to about 60,000.

9. The copolymer of claim 8, wherein the isoolefin is iso-butylene, 2-methyl-1-butene, 3-methyl-1-butene or 4-methyl-1-pentene.

10. The copolymer of claim 8, wherein the isoolefin is iso-butylene and the diene is cyclopentadiene.

11. A substantially gel free copolymer consisting of a major portion of an isoolefin having about 4 to about 10 carbon atoms and from about 10 to 45 mole % of a cyclic conjugated diene having about 5 to about 9 carbon atoms, said cyclic conjugated diene selected from the group consisting of cyclopentadiene and methyl-cyclopentadiene, said copolymer having an Mn of about 60,000 to about 70,000.

12. The copolymer of claim 11, wherein the isoolefin is iso-butylene, 2-methyl-1-butene, 3-methyl-1-butene or 4-methyl-1-pentene.

13. The copolymer of claim 11, wherein the isoolefin is iso-butylene and the diene is cyclopentadiene.

14. A substantially gel free copolymer consisting of a major portion of an isoolefin having about 4 to about 10 carbon atoms and from about 8 to 45 mole % of one cyclic conjugated diene having about 5 to about 9 carbon atoms, said cyclic conjugated diene selected form the group consisting of cyclopentadiene and methyl-cyclopentadiene, said copolymer having an Mn of about 70,000 to less than 90,000.

15. The copolymer of claim 14, wherein the isoolefin is iso-butylene, 2-methyl-1-butene, 3-methyl-1-butene or 4-methyl-1-pentene.

16. The copolymer of claim 14, wherein the isoolefin is iso-butylene and the diene is cyclopentadiene.

17. A substantially gel free terpolymer consisting of a major portion of an isoolefin having about 4 to about 10 carbon atoms and a minor portion of an acyclic conjugated diene having about 5 to about 9 carbon atoms and a cyclic conjugated diene having about 5 to about 9 carbon atoms, said cyclic conjugated diene selected from the group consisting of cyclopentadiene and methyl-cyclopentadiene, a mole % unsaturation of said cyclic conjugated diene being from about 20 to 45 mole %, an Mn of said terpolymer being about 30,000 to about 50,000.

18. The copolymer of claim 17, wherein said isoolefin is iso-butylene and said acyclic conjugated diene is isoprene and said cyclic conjugated diene is cyclopentadiene.

19. The copolymer of claim 17, wherein said acyclic conjugated diene is isoprene.

20. The copolymer of claim 17, wherein said cyclic conjugated diene is cyclopentadiene.

21. A substantially gel free terpolymer consisting of a major portion of an isoolefin having about 4 to about 10 carbon atoms and a minor portion of an acyclic conjugated diene having about 5 to about 9 carbon atoms and a cyclic conjugated diene having about 5 to about 9 carbon atoms, said cyclic conjugated diene selected from the group consisting of cyclopentadiene and methyl-cyclopentadiene, a mole % unsaturation of said cyclic conjugated diene being from about 15 to 45 mole %, an Mn of said terpolymer being about 50,000 to about 60,000.

22. The copolymer of claim 21, wherein said isoolefin is iso-butylene, said acyclic conjugated diene is isoprene, and said cyclic conjugated diene is cyclopentadiene.

23. The copolymer of claim 21, wherein said acyclic conju-gated diene is isoprene.

24. The copolymer of claim 21, wherein said cyclic conjugated diene is cyclopentadiene.

25. A substantially gel free terpolymer consisting of a major portion of an isoolefin having about 4 to about 10 carbon atoms and a minor portion of an acyclic conjugated diene having about 5 to about 9 carbon atoms, and a cyclic conjugated diene having about 5 to about 9 carbon atoms, said cyclic conjugated diene selected from the group consisting of cyclopentadiene and methylcyclopentadiene, a mole % unsaturation of said cyclic con-jugated diene being from 10 to 45 mole %, an ?n of said terpolymer being about 60,000 to about 70,000.

26. The copolymer of claim 25, wherein said isoolefin is iso-butylene, said acyclic conjudated diene is isoprene and said cyclic conjugated diene is cyclopentadiene.

27. The copolymer of claim 25, wherein said acyclic conjugated diene is isoprene.

28. The copolymer of claim 25, wherein said cyclic conjugated diene is cyclopentadiene.

29. A substantially gel free terpolymer consisting of a major portion of an isoolefin having about 4 to about 10 carbon atoms and a minor portion of one acyclic conjugated diene having about 5 to about 9 carbon atoms and one cyclic conjugated diene having about 5 to about 9 carbon atoms, said cyclic conjugated diene selected from the group consisting of cyclopentadiene and methyl-cyclopentadiene, a mole % unsaturation of said cyclic conjugated diene being from 8 to 45 mole %, an ?n of said terpolymer being about 70,000 to less than 90,000.

30. The copolymer of claim 29, wherein said isoolefin is iso-butylene, said acyclic conjugated diene is isoprene and said cyclic conjugated diene is cyclopentadiene.

31. The copolymer of claim 29, wherein said acyclic conjugated diene is isoprene.

32. The copolymer of claim 29, wherein said cyclic conjugated diene is cyclopentadiene.

33. A substantially gel free terpolymer consisting of a major portion of an isoolefin having about 4 to about 10 carbon atoms and a minor portion of an acyclic conjugated diene having about 5 to about 9 carbon atoms and a cyclic conjugated diene having about 5 to about 9 carbon atoms, said cyclic conjugated diene selected from the group consisting of cyclcpentadiene and methyl-cyclopentadiene, a mole % unsaturation of said cyclic conjugated diene being from about 10 to 45 mole %, an Mn of said terpolymer being about 30,000 to less than 90,000.

34. The copolymer of claim 33, wherein said isoolefin is iso-butylene, said acyclic conjugated diene is isoprene, and said cyclic conjugated diene is cyclopentadiene.

35. The copolymer of claim 33, wherein said acyclic conjugated diene is isoprene.

36. The copolymer of claim 33, wherein said cyclic conjugated diene is cyclopentadiene.

37 The copolymer of claim 19, wherein said cyclic conjugated diene is cyclopentadlene.

38. The copolymer of claim 23, wherein said cyclic conjugated diene is cyclopentadiene.

39. The copolymer of claim 31, wherein said cyclic conjugated diene is cyclopentadiene.

40. The copolymer of claim 28, wherein said acyclic conjugated diene is isoprene.

41. The copolymer of claim 29, wherein said cyclic conjugated diene is cyclopentadiene.