CA1130047A - High unsaturation isobutylene-isoprene-cyclopentadiene terpolymers and isobutylene-isoprene copolymers - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Substantially gel-free, high unsaturation copolymers of isobutylene and isoprene and high unsaturation terpolymers of iso-butylene, isoprene and cyclopentadiene having a number average molecular weight of at least about 90,000 and a mole percent of unsaturation of at least 5% and the process for preparing said polymers which comprises carrying out the polymerization in a homogeneous phase, introducing to the system either an aluminum halide in a soluble form or a hydrocarbylaluminum dihalide and carrying the reaction out at a temperature of less than about -100°C.

Description

~13(~0~7 .

1 Thi~ invention relates to a method for preparing

2 substantially gel-free copolymers of isobutylene and isoprene

3 and terpolymers of isobutyleneoisoprene-cyclopentadiene ~ having a number average molecular weight, as measured by membrane osmometry, of at least go, dnd a mole %
6 unsaturation of at least 5%. -7 In order to obtain the copolymers and terpolymers 8 of this in~ention, the reaction should be carried out at g less than -10~C. To ~btain the desired number average lo molecular weight in a substantially gel-free polymer, a 1I homogeneous polymerization is required. This is achieved 12 by carrying out the reaction in a vehicle which is a solvent for the copolymer at the reaction temperature. The vehicle 14 comprises predominantly the monomers to be polymerized in con~unction with an inert cosolvent or mixtures of inert 16 cosolvents plus catalyst solvent.
17 The copolymers of the instant invention are formed 18 from an isoolefin and a straight chain conjugated hydrocarbon multiolefin or a cyclic conjugated hydrocarbon multiolefin.
` The terpolymers of the instant invention are 21 onmed from an isoolefin and two conjugated hydrocarbon 22 multiolefins, wherein the two multiolefins can either be one 23 straight chain multiolefin and one cyclic multiolefin or two 24 cyclic multiolefins.
The isoolefins suitable for use in the practice of 26 the inventions are preferably hydrocarbon monomers having 27 4 to lQ carbon atoms. Illustratl~2 nonlimit~ng 28 examples of these isoolefins are isobutylene, 2-methyl-1-butene, 3-methyl-1-butene, 4-methyl-1-pentene, beta-pinene, etc. Preferably, the isoolefin is isobutylene~
31 The multiolefins suitable for use in this invention 32 are conjugated hydrocarbon multiolefin~ having 5 to 14 ;~ - 2 ~3(~()47 l carbon atoms; more preferably, the multiolefins are conju-2 gated diolefins of 5 to 9 carbon atoms. Illustrative non-3 limiting examples of these multiolefins are isoprene, piper-

4 ylene, 2,3~dimethyl butadiene, 2,5-dimethylhexadiene-2,4-ene~
S cyclopentadiene, cyclohexadiene, methylcyclopentadiene, 6 fulvene, etc and mixtures thereof.
7 It is essential in carrying out the process of 8 this invention that the cosolvent comprise at least 5% by 9 volume and not more than 40% by volume of the total reaction mixture. Preferably, 5 to 30 volume Z solvent ll iæ used; more preferably 0.5 to 25 wt. %, most prefer-12 ably 10 to 20 wt. %, e.g., 15 volu~e %. The 13 term "total reaction mixture" as used in the specification 14 and claims means total monomers plus cosolvent.
The optimum amount of cosolvent to be used is the 16 minimum amount necessary to avoid reactor fouling or gela-17 tion. I too little cosolvent is used reactor fouling or 18 gelation of the produ~t results. Too high a level results 19 in undesirable lowering of number average molecular weight.
For the purposes of this invention, it is conven-21 ient to define the volume Vh of inert cosolvent as that cal-22 culatet based on the volume of monomers at -78C. (dry ice 23 temperature? while the volume of cosolvent is determined at 24 25C. The volume a/. of cosolvent as calculated is uncorrected for volume changes and cooling of the solvent to reaction 26 conditions.
27 The minimum quantity of a given cosolvent required 28 to produce gel-free polymers is a function of the cosolvent, 29 the conjugated multiolefin used and the polymerization temp-~ erature. Having selected the composition of the blend of 31 monomers and the cosolvent to be used the minimum quantity 32 of cosolvent required is readily determined by carrying out , ~13(:~047 1 the polymerization using varying amounts of cosolvent. The 2 minimum quantity of cosolvent necessary is that amount 3 required to maintain a homo~eneous system; that is to pre-4 vent precipitation of polymer during polymerization.
S The term "cosolvent" as used in the specification 6 and claims means the inert solvent which9 together with the 7 monomer feed, comprises the vehicle for the reaction. The 8 cosolvent and monomers must be mutually soluble and the 9 blend of monomers plu8 cosolvent must be a solvent for the l copolymer at the polymerization temperature. The term ll "inert" means that the cosolvent will not react with the l2 catalyst or otherwise enter into the polymerization reac-3 tion. The cosolvent must not contain substituents in its 4 molecule which will interfere with the polymerization reac-tion. Aliphatic hydrocarbons are suitable cosolvents. The l6 preferred cosolvents are paraffinic hydrocarbons, and carbon 7 disulfide. Preferably, the paraffinic hydrocarbon solvent l8 is a Cs-Clo hydrocarbon~ more preferably a Cs to C8 hydro-l9 carbon. Illustrative examples of the hydrocarbon solvents are pentane, isopentane, methylpentane, hexane, cyclohexane, 2l methylcyclohexane, dimethylcyclohexane, heptane, isooctane, 22 1,2,3,3-tetramethyl hexane, tetramethyl cyclohexane, etc.
23 Generally any paraffin, whether normal, branched or cyclic 24 which is a liquid under polymerization conditions, may be used. The term "paraffin" as used in the specification and 26 claims includes normal paraffins, cycloparaffins and branched 27 paraffins or mixtures thereof. When the diene is a cyclo-28 diene preferred cosolvents contain cycloparaffins.
Since the monomers act as part of the solvent ~ system for the polymer~ the conversion level of the poly-31 merization must not be so great as to result in precipitation 32 of the copolymer as a result of depletion of solvent. Pre-L:

~13(~ 47 1 ferably the converslon level is ~ to 30%; more 2 preferably 3 to ~5%; most preferably 5 to 3 13c/~, e.g., lOZ- , 4 In the practice of this invention the catalyst can S be an aluminum halide or a hydrocarbylaLuminum dihalide. ~, 6 Where an aluminum halide is used9 it must be in the form of 7 a homogeneous solution or submicron dispersion of catalyst 8 particles, e~g., colloidal dispersionO Therefore, the 9 aluminum halide catalyst must be dispersed or dissolved in a suitable catalyst solvent or mixture of solvents. The 11 aluminum halide catalyst solvent must be a polar solvent.
12 Illustrative examples of suitable aluminum halides are AlCl3 13 and AlBr3. The preferred aluminum halide catalyst is alumi-14 num chloride. The term "polar solvent" as used in the specification and claims means non-aromatic, organic solvents 16 having a dielectric constant at 25C. of at least 4, prefer-17 ably 4 to 20, more preferably 6 to . . . , . _ .
~8 17; most preferably 9 to 13. These polar sol-19 vents, however, must not contain sulfur, oxygen, phosphorus or nitrogen in the molecule since compounds containing these 21 elements will react with or otherwise deactivate the catalyst.
22 The preferred polar solvents are inert halogenated 23 aliphatic hydrocarbons; more preferably halogenated p~raf-2~ ;finic hydrocarbons and vinyl or vinylidene halides; most preferably primary or secondary chlorinated paraffinic hydro-26 carbons. The halogenated hydrocarbon is preferably a Cl-C5 27 paraffin hydrocarbon; more preferably a Cl-C2 paraffin. The 28 ratio of carbon atcms to halogen atoms in the polar solvent 29 ~s preferably 5 or les~O Preferably the halogen is chlorine.
Illustrative examples of these polar organic sol-31 vents are methylchloride, ethyl chloride, propyl chloride, 32 ~ethyl bromide, ethyl bromide, chloroform, methylene chloride, ~13(304`~ 1 1 vinyl chloride9 vinylidene chlorlde, dichloroethylene, e~c.
2 Preferably, the polar soLvent is methyl chloride or ethyl 3 chloride. Generally any inert halogenated organic compound 4 which is normally liquid under poly~erization conditions and S has a dielectric constant of at least 400 may be used.
6 It is essential in carrying out this invention 7 that the aluminum halide catalyst be in solution in the polar 8 organic solvent prior to introduction of the cstalyst to 9 reaction mediumc Combining the polar organic solvent with the reaction medium and thereafter adding the aluminum halide 11 catalyst thereto will not result in the production of the 12 high Rn, high unsaturation polymers of this invention.
13 Use of the term "solution" with reference to the 14 polar organic solvent/aluminum halide systems is intended to lS include both true solutions and colloidal dispersions since 16 they may exist concurrently in the same system.
17 The aluminum halide/polar solvent catslyst prefer-18 ably comprises 0.01 to 2 wt. % aluminum halide;
19 more preferably 0.05 to 1, more preferably 0.1 to 0.8.
21 As previously noted, the catalyst may also be a 22 hydrocarbylaluminum dihalide. The hydrocarbyl group can be 23 a Cl-C18 straight chain,branched or cyclic group. Both cyclo-24 aliphatic and aromatic substituents can comprise the hydro-~5 carbyl radical. Alkyl groups, especially lower alkyl groups, .

26 e.g., Cl-C4, are preferred because of their general availabil-27 ity and economy of use. T he halide can be bromine or chlor-28 ine, preferably chlorine. The term "dihalide" as used in the~ specification and claims means dichloride or dibromide.
Illustrative examples of these hydrocarbyl alumi-31 num dihalides are methylaluminum dichloride, ethylaluminum 32 dichloride, isobu~ylaluminum dichloride, methylaluminum di-_ ~ _ 1131~ 47 , 1 bromide, ethylaluminum dibromide9 benzylaluminum dichloride, 2 phenylaluminum dichloride9 xylylsluminum dichloride~ toluyl-3 aluminum dichloride~ butylaluminum dichloride, hexylaluminum 4 dichloride9 octylaluminum dichloride~ cyclohexylaluminum di-S chloride, etc. The preferred catalysts are methylaluminum 6 dichloride9 ethylaluminum dichloride ~nd isobutylaluminum 7 dichlorideO
8 The hydrocarbyl aluminum dihalide catalyst may be 9 added neat or in solution. Preferably where a catalyst sol-vent is used9 it is a liquid paraffin solvent or cycloparaf-ll fin solvent. It i8 advantageous though not necessary to use 12 paraffins at low freezing point. Methylcyclohexane is par-l3 ticularly useful since catalyst solutions of about 1% con-l4 centration do not freeze at -120Co The concentration of the catalyst is not critical.
l6 Very dilute catalyst solutions, however, are not desirable l7 since substantial fractions of the catalyst may be deacti-l8 vated by impurities. Very concentrated solutions are unde-l9 sirable since at polymerization temperatures catalyst may be lost by freezing out of solution.
2l In carrying out the polymerization of this inven-22 tion those skilled in the art will be aware that only cata-23 lytic amounts o~ catalyst solution are required. Preferably 24 the volume ratio of monomer plus cosolvent to catalyst solu-tion is 100/l to 9/1; m0re preferably 80/1 26 to 10/1; most prefera~ly 20/1 to 20/l.
27 In ~racticing the process of this invention, it is 28 essential that the polymerization be carried out in the 29 homogeneous phase without the precipitation of polymer. Con-ventional slurry processes are inapplicable for the prepar-31 ation of the high unsaturation polymers of this invention 32 since by theLr nature they resule in polymer precipLtation ,,, , . , , .. ",, .",,, .. , .. . . .. .. . .. . .. 1 ~i300~7 with gelat~on of the polymer as a consequence.
~ he amo~nt of cosolvent required in order to main-tain the polymerization reactants and product ln solution throughout the polymerization is a function of the multi-olefin selected for polymerization and its concentration in the monomer feed. The polymerization temperature at which precipitation of polymer will occur i~ itself a function of the smount of snd type of cosolvent'and'the particular multi-olefin being copolymerized.
The term "critical homogeneous polymerization temperature" as used in the specification and claims means that polymerization temperature below whlch precipltation of polymer will occur when no cosolvent i8 included in the reaction mixture, i.e., the only solvent for the reactants and product being the monomer feed.
~' Characterization of polymers prepared by bulk poly-merization, i.e., without cosolvent, shows that the polymers formed are low in number average molecular weight (Mn). In order to increase Rn, the lowering of polymerization temper- : 20 ature i8 an obvious expedient. ~owever, in the absence of cosolvent, the resultl i8 not greater Mn but gelation;
;The problem of gelation is obviated by the addition of a cosolvent which perm~ts the lowering of polymerization temperature below the critical homogeneous polymerization temperature. It has been found that a polymeriza~ion temp-erature below -100C. is necesEary ln order to achieve ~n v~lues of at least 90,000 for the copolymer and terpolymers of the present invention. At least 5 volume % inert solvent ba~ed on the monomer feed is necessary in order to csrry out th~ polymerization in solution at the8e low temperature8.

Bi' -8- ' ~13~04`7 BRIEF DESCRIPTION OF DRAWINGS
Fig. I shows the relation~hip between critical homogeneous polymerization temperature and diene content.
Fig. Il shows the effect of polymerization temp-erature on number average molecular weight.
Fig. III shows th~ effect of cosolvent concentra-tion on molecular weight.
F~g. IV ~hows the effect of polymerization temp-erature on conversion.
o Fig. V shows catalyst efficiency as a function of cosolvent concentration.
Fig. VI shows the relationship between mole %
cyclopentadiene ~n the feed as compared to mole /0 cyclo-pentad~ene in the polymer.
Fig. VII shows the relationship between gla~s transition temperature and mole % cyclopentadlene enchain-ment in the copolymer.
Flg. ~III ls a correlation of D# (vol. ~ CPD in monomer) with mole ~ cyclopentadiene in the monomer ~eed.

Referring now to Figure I, the volume % of multi-olefln (isoprene) ln the monomer blend (B~) i8 plotted as a -8a-~B
- .

~130047 1 function of the polymerization temperature below which pre-2 cipitation of polymer and as a consequence gelation occurs 3 in the absence of cosolventO The curve represents the crit-4 ical homogeneous polymerization temperatures for isobutylene-isoprene systemsO
6 The process of this invention incorporates the 7 isobutylene and isoprene into the copolymer in substantially 8 the same ratio aæ it exists in the feed. For example, where 9 an isobutylene-~soprene monomer feed comprises 15 volume ~/0 o isoprene the polymer formed therefrom comprises about lZ.5 11 mole Z unsaturation. Characterization of polymers prepared 12 by bulk polymerization9 iOe., without cosolvent, shows that 13 the polymers formed are low in number average molecular 14 weight ~Mn). In order to increase Mn~ the lowering of poly-merization temperature is an obvious expedient. However, in l6 the absence of cosolvent, the result is not greater ~n but gelation.
l8 The term "unsaturation" or "multiolefin content"
9 as used with reference to the amount of multiolefin enchain-ment in the product are equivalent terms. The composition 21 of the copolymer (mole X u~saturation ~ mole % diene content) 22 i8 substantially the same as the composition o~ the feed for 23 acyclic dienes such as isoprene and piperylene. However, 24 where the diene is a cyclic diene such as cyclopentadiene, it is present in considerably higher amounts, e.g., 3 to 4 26 times, in the copolymer as in the feed.
27 The necessity for utilizing low polymerization 28 temperatures i8 exemplified by Figure II which shows the 29 exponential decrease in number average molecular weight with ~ increasing temperature. The criticality of selecting the 31 proper quantity of cosolvent is demonstrated in Figure III.
32 Too llttle cosolvent results ln precipitation of the polymer _ 9 _ ,,, ,,", ,",",,,""," ,, ,.~. ,,.. ,,,, .~ ,......... ...

113()047 I, 1 with reactor fouling or gelation. Too much cosolvent results 2 in a low molecular weight product. Further benefits of low 3 temperature and proper selection of appropriately low cosol-4 vent concentration are demonstrated in Figures IV and V.
Figure IV shows that reactivity is favored by low tempera-6 tures (in sddition to the molecular weight benefit). Figure 7 V shows that catalyst efficiency is favored by low cosolvent 8 concentration (in addition to the molecular weight benefit).
9 In practicing the process of this invention, one skilled in the art may proceed as follows in order to deter-11 mine the preferred reaction conditions.
~2 First, a convenient polymerization temperature 13 below -100C. is selected. Next the desired feed compo-14 sition, i.e. monomers and ratio of isoolefin to conjugated dienes and the cosolvent to be used are selected. Polymer-16 ization reactions are carried out using successively greater 17 amounts of solvent. The initial polymerization reaction is 18 carried out using 5 volume % based on the total of monomer 9 plus solvent of the cosolvent since lesser amounts will be inadequateO In each successive run an additional 5 volume 21 % is added. The procedure is continued until the reaction 22 medium remains clear throughout the reac~ion. Turbidity i9 23 indicative of precipitation of polymer which leads to reactor 24 fouling or gelation.
The polymer formed is characterized for Rn and 26 mole % unsaturation. Where a higher Mn is desired it may 27 be achieved by either lowering the polymerization temperature 28 or where possible using slightly less solvent than determined 29 by the above method, e.g.9 1 2 vol. Z less, provided that turbidity does not occurO Reduction of polymerization temp-31 erature may result in a greater ccsolvent requirement.
32 Hence, the aforegoing procedure of adding additional solvent - 10 - `

~13(~(~47 1 to the reaction medium must be continued until the reaction 2 medium is again clear throughout the polymerization.
3 Where the mole % unsaturation is to be adjusted 4 somewhat more or less of the diene is used depPnding on whether a slightly higher or lower u~saturation is desired.
6 Change in feed composition may require readjusting the co-7 solvent requirementO GenerallyD increasing the multiolefin lB content of the monomer feed decreases the cosolvent require--~9 ments of the system with acyclic diene~like isoprene and ~ increases the cosolvent requirement with cyclicdiene such as ~1 cyclopentadiene.
2 The optimum reaction conditions are those which 3 give the maximum Rn at the highest (warmest) temperature for 4 the desired unsaturation level. The smaller the quantity of lS cosol~ent used the greater the MnO Economic considerations 16 dictate the use of the warmest temperature practical for ,~ 17 polymerization. Use of lower temperatures wLll necessltste 18 the use of greater amounts of cosolvent. Preferably the 19 polymerization temperature is above -110C.
In an alternate approach to determine the neces-21 sary quantity of cosolvent~ the reactions are carried out in :, .
22 bulk without using cosolvent. For each different multiolefin ~23 content monomer feed, polymerizations are carried out at 24 progressively lower temperatures until the critical homo ~
geneous polymerization temperature for the feed composition 26 i8 determined. The polymerization is repeated for different 27 feed compositions and the data obtained are the critical 28 homogeneous polymerization temperatures as a function of 29 multiolefin content of the feed. A plot of these data gives the critical homogeneous polymerization temperature curve 31 analogous to that of Figure I. The polymer formed is ana~-32 yzet for multiolefin content and a detenmination is made of ~13~4q 1 the correlation mole % unsaturation in the polymer and 2 volume % ~ultiolefin in the feed. The polymers formed in 3 bulk copolymerization of isobutylene and ~soprene or iso-4 -butylene-isoprene~cyclopentadiene are unsuitable for commer-clal use since they have a very low MnO In order to increase 6 the Mn of the polymer it is necessary to carry out the poly-7 merization at lower temperatures9 e.g., less than -100C.
8 which requires the addition of cosolvent to prevent precip-9 itation of polymer during polymerization.
~ The quantity of solvent used should be kept to a 11 minimum since excess cosolvent results in the lowering of 12 ~n. In determining the amount of solvent to be used the l3 monomer feed composition is determined. A convenient poly-14 merization temperature below -100C. is selected.
The minimum cosolvent requirements for a particular 16 isoolefin-multiolefin may be determined by carrying out th~
17 polymerization at the critical homogeneous polymerization 18 temperature for the isoolefin-multiolefin feed composition, 19 terminating the polymerization by destroying the catalyst and, with constant stirring, lowering the temperature of the 21 system to the desired polymerization temperature. The poly-22 mer which, of course, is by definition insoluble below the 23 critical homogeneous polymerization temperature will precip-24 itate out and the system will appear turbid. The polymer will not be gelled, however, since polymerization was ter-26 m~nated prior to precipitation. The cosolvent selected is 27 then added in incremental amounts until the turbidity dis-28 appears. The quantity of solvent so added is a good approxi-29 mation of the minimum solvent requirements for a given iso-olefin-multiolefin feed to be polymerized at a given temp-31 erature.
32 The term ~solution polymerization" as used in the ~13Q047 l specification and claims means a polymerization carried out 2 æo that the polymer product remains dissolved throughout the 3 reaction.
4 Where the diene to be polymerized is isoprene, ~he preferred cosolvents are hexane~s), heptane(s), cyclohexane, 6 and methylcyclohexane or mixtures thereof utillzed at 7 5 to 30 volume %; more preferably at 10 to 8 25 volume %, e~gO, 10 volume %. Where the diene is cyclo-9 pentadiene the preferred cosolvents are methylcyclohexane (MCH) and cyclohexane or paraffin mixtures containing one of l~ these materials utilized at about 10 to about 30 volume %, l2 e.g., 20 to about 25 volume V/o.
13 The products of this invention offer a number of 4 important advantages over the commercially available butyl rubbers. In addi~ion to possessing superior cold flow and 16 green strength properties while retaining the low air per-meability and mechanical damping characterist~cs of conven-l8 tional low unsaturation isoolefin copolymers, the products 9 of this invention offer greater versatility in vulcanization ~ techniques. Furthermore while the vulcanization of conven-l tional isoolefin-multiolefin copolymers requires the use of 22 ultra-accelerator type cures~ e g ~ thluram (Tuads) or di-23 thiocarbamates (Tellurac), the products of this invention 24 may be vulcanized using the thiazole, e~g., mercaptobenzo-thiazole, type cures currently used in the vulcanization of 26 general purpose rubbers, e.g., natural rubber, SBR, poly-27 butadiene, etc. Because of certain factors of ~hich pre-mature vulcanJzation (scorch~ is a prime example, modern ~ practice has tended towards the use of a special class of thiazoles called delayed action acceleratorsO These delayed 3l action accelerators permit the processing of the compounded 32 rubber (including w lcanizing agents~ at the vulcanization ~ r~

~13~0~7 1 temperature for a predetermined period of tLme before vul-2 canization commences. Such cure techniques are not possible 3 with conventional isoolefin copolymers. The delayed action 4 accelerators are, however9 used advantageously in the vulcan-ization of the isoolefin copolymers of this invention.
6 The delayed action accelerators suitable ~or use 7 in vulcanizing the products of this invention include the 8 benzathiole sulfenamides having the general formula:
H
H - C / ~ C / \

H - C ~ C

, .

wherein X is an amino group. The ~mino group is mono or di-16 organosubstituted ant may be cyclic including heterocyclic.
17 For example, X may be ^ N~Rl or - N - R2 where Rl is H or 18 R, R is organo or cycloorgano, and R2 is a divalent organo 19 radical. Illustrative examples of X are cyclohexylamino, tertiary butyl amino, diisopropyl amino, dicyclohexyl amino, 21 pentamethylene-amino, morpholino, 2-(2,6-dimethyl morpholino) 22 etc. Specific illustra~ive examples of these ~ulienamides 23 are N,N-diethylbenzothiazole~2-sulfenamide, N-N-diisopropyl ;24 benzothiazole-2~sulfenamide, Notertiary butyl benzothiazole-2-sulfenamide, N-cyclohexyl benzothiazole~2-sulfenamide, N, 26 N-dicyclohexyl benzothiazole~2~sulfenamide, 2~(morpholino) 27 benzothiazole sulfenamide~ 2 (2,60dimethyl morpholino) ben-28 zothiazole sulfenamide9 2~piperdinyl benzothiazole sulfena-29 mide. In general9 any benzothiazole sulfenamide may be used as a delayed action accelerator for the sulfur vulcanization 31 of the polymers of this lnvention.
32 The delayed action ~ccelerator is incorporated 13~04q l into the vulcanizable polymer composition at preferably 2 0.1 to 5 wt. %, baæd on the polymer; morepre-3 ferably 0.25 to 3.5; most preferably 0.5 4 to 3.0 wt. %, e.~., 0.5 to 2.5 wt. ~.
s As it is well known9 the delayed action cures are 6 sulfur cures and sulfur must be incorporated into the polymer 7 blend either as elemental sulfur or as nonelemental sulfur.
8 Suitable nonelemental sulfur is in the form of those com-` - 9 pounds which will release sulfur to the polymer under vul-canization conditions~ For a description of these nonele-ll mental sulfur compounds9 generally, see Vulcanization of 12 Elastomers9 Ch. 4, J. C. Ambelang, Reinhold, New York, 196~.
13 Illustrative examples of these nonelemental sulfur compounds 14 are dimorpholvinyl disulfide and alkyl phenol disulfides.
The term "sulfur donor" as used hereinafter in the specifi-16 cation and claims means elementsl sulfur as well as the ; 17 aforementioned nooelemental sulfur compounds. The quantity 18 of sulfur donor required for vulcanizstion is well known.
19 Where the sulfur donor is elemental sulfur, it is incorpor-~20 ated into the polymer at a~out 0.1 to about 5 wt. ~ based on :: .
2l the polymer; more preferably about 0.25 to about 3~5 wt. X;
22 most preferably about 0.5 to about 3.0 wt. ~b, e~g., 0.5 to 23 about 2.5 wt. ~. Where the sulfur donor is a nonelemental 24 sulfur compound, it i8 incorporated at a weight X of about three times that required for elemental sulfur. The term 26 "nonelemental sulfur compounds" means organic compounds 27 containing sulfur and capable of donating the sulfur to a 28 vulcanization reaction~ e.g.9 disu~fides and polysulfides.
29 The delayed action accelerators may be modified by retarders and activators which will respectively retard or 3l activate the sulfur vulcanization. The addition of the re-32 tarder will further delay the time at which vulcanization l occurs while the acti~ator will csuse vulcanization to occur 2 sooner, eOgO~ shorter delay time~
3 The retarders suitable for use in the practice of 4 this invention include organic compounds having a pKa of s 2 to lessthan 7 ; preferably 3 to 6,5 6 more preferably ~ to 6, e.g.,~5. The term ~Ka 7 i8 the dissociation const$nt a~ measured in aprotic solvents, 8 see for example Acid~Base Behavior in Aprotic Solvents NBS
9 Monograph 105, August 19680 o The activators suitable for use in the practice of ll this invention are metallic oxides~ hydroxides and alkoxides l2 of Group Ia and Group IIa metals of the Periodic Table of 3 the Elements and organic compounds having a pKa of 8 14 to 14; preferably 9 to 12; more preferably 9.5 to 11, e.g., 10. ~ ~
16 , Illustrative examples of retarders are N-nitroso 7 diphenylamine, ~-cyclohexyl thiophthalim~de, phthalic anhy-l8 dride, salic~lic acid, benzoic acid, etc. Generally, the 9 preferred retarders are nitroso compounds, phthalimides, anhydrides and acids.
2l Illustrative examples of activators are MgO, di-22 phenylquanidine, hexane-l-amine, 1,6-hexane diamine, sodium 23 methoxide, etc. The preferred activators are quanidines and 24 amines.
2s The retarders and activators are pre~erably incor-26 porated into the polymer at O.1 to 5 wt. %; more 27 preferably 0.25 to 3.5 wt. %; most preferably 2B O~5 to 3.0 wt. %, e.~.J 0.5 to ~Dout 2.5 wt. Z~ _ _ 29 As it is well known in the elastomeric art9 the copolymers ~ and terpolymers of the instant invention can be readily ex-31 tended with fillers and oils ior further modification of the 32 phys~cal properties of the resultant articles of commerce, . ` ' 1~3004q 1 The copolymexs and terpolymers of the instant in-2 vention can be readily blended with other rubbers for modi-3 fication of physical and chemical properties by techniques 4 well known in the art. These other rubbers are selected from the group consisting of non~polar crystallizable rub-6 bers (i.e. crystallization either deduced by low temperature 7 or strain or a mixture thereof)~ polar crystallizable rub-8 bers, non-polar non~crys~allizable rubbers9 and polar non-9 crystallizable rubbers. These rubbers are contained in the lo blend compositions at a concentration level of 5 to 11 ~5 parts by weight per 100 parts of the total of the ~
12 rubber plus copolymer and/or terpolymer, more preferably 13 ~0 to 50 and most preferably 10 to 14 30. Typical, but non-limiting examples of each class are:
lS non-polar crystallizable rubbers, natural rubber, low iso-16 prene butyl rubbers having less than loO mole percent i80-7 prene; polar crystallizable rubbers-polychloroprene rubber~
8 (i.e., the neoprene types), non~polar non-crystallizable 1~ rubbers-styrene butadiene copolymers, polybutadienes and butyl rubbers containing more than loO mole percent isoprene;
21 and polar non-crystallizable rubberQ~styrene acrylonitrile 22 copolymers.
23 The fillers employed in the present invention are 24 selected from the group consisting of carbon blacks, silica, ~5 talcs, ground calcium carbonate, water precipitated calcium 26 carbonate, or delaminated, calcined or hydrated clays and 27 mixtures thereofO These fillers are incorporated into the 28 blend composition at 5 to 350 ~arts by weight per hundred parts of polymerp more preferably at 25 to 350; and most preferably at 50 to 300~
31 Typically, these ~illers have a particle size of 0.03 32 to 20 microns, more preferably 0.3 to 10, ~~` 1 1 3~ 09~7 1 and most preferably 0.5 to lO. The oil absorp~
2 tion as measured by grams of oil absorbed by 100 grEms of 3 filler is 10 to 100, more preferably 10 4 to 85 and most preferably 10 to 75.
The compounding and plasticizer oils employed in 6 the present invention are non~polar prccess oils having less 7 than 2 wt. % polar type compounds as measured by mol-8 ecular type clay gel analysis. These oilæ are selected from paraffinics ASTM Type 104B as defined in ASTM~D-2226~70, aromatics ASTM Type 102 or n~phthenics ASTM Type 104A~
ll wherein the oil has a flash point by the Cleveland open cup 12 of at least 350Fo~ a pour point of less than 40F., a vis-13 cosity of 7~ to 3000 S.S.U.'s at 100F. and a 14 number average molecular welght of 300 to 1000~
ant more preferably 300 to 750. The preferred process l6 oils are paraffinics.
17 The oils are incorporated into the blend composi-l tion at a concentration level of 5 to 200 parts 19 by weight per hundred parts of polymer; more preferably at 25 to 150, and most preferably at 50 to 2l 150 ~2 Other plasticizers suitable for use in the present 23 invention are medium viscosity ester plasticizers for special 24 high efficiency in increasing resilience particularly at low te~perature. Some examples~ which are not intended to be 26 limiting in scope are dioctyl phthalate, dioctyl azelate, 27 dioctyl sebacate or dibutyl phthalate. The ester plasti-28 cLzer is incorporated into the blend compocition at a con-29 centration level of 5 to 100 parts by weight per hundred of polymerD more preferably 5 to 75J and 31 most preferably 5 to 50.
32 Terpolymers of isoolefins and cyclodienes, e.g~, .

113C~04~

1 Isobutylene-isoprene and cyclopentadiene possess markedly 2 ~mproved resistance to degradation by ozone over the acyclic 3 diene copolymersO Although it has been postulated that such 4 terpolymers would have such improved properties as a result S of having the unsaturation located in a side chain rather 6 than in the backbone, it has heretofore not been possible to 7 prepare substantially gel~free isoolefin~cyclodiene terpoly-8 mers of high number average molecular weight even at low 9 levels of unsaturation.
Vtilizing the process of this invention, it is now ~1 possible to prepare such cyclodiene terpolymers having as 12 little as O.S mole b unsaturation and as high as 45 mole Z
13 unsaturation~ Preferably~ the polymers contain 5% to 14 45~; more preferably 5 to 40 mole % unsat-15 uration; still more preferably B to 40; an~ most 1 16 preferably 8 to 30 mole Z, e.g., 12 to ~¦
17 30 mole Z I¦
~ . . . , . . __ 18 As a result of the relatively lower reactivity of 19 the unsaturation as compared to the isoprene copolymers, copolymers having incorporated therein about 2-4 mole %
21 cyclopentadiene are about as reactive as butyl rubber having 22 an isoprene content of 0.5 to 1.5 mole ~ and 23 require ultra acceleration for sulfur vulcanization. By 24 contrast the higher unsaturation copolymers, e.g., at least S mole %, preferably at least 8 mole ~, may be sulfur vul-26 canized using the delayed action accelerator cure systems 27 described above.
28 In general, the copolymers of this invention must 29 not contain more than 45 mole ~ unsaturation. Above 45 mole ~ unsaturatibn, polymers prepared from acyclic ~1 multiolefins are intractable and unstable9 eOg., gel on 32 standing. Whcre the multio1sfin i9 a cyclic multiolefin ~130047 1 above 45 mole Z unsaturation~ the glass transition tempera-2 ture of the polymer is too higho As a result, the polymers 3 ~ave poor low temperature characteristicsO Preferably, the 4 copolymers of this in~ention have 5 to 45 mole C/o unsaturation, more preferably 5 to 40 mole ~;
6 8till more preferably 8 to 40 and most pre~er-7 ably about 8 to 30 mole %; e-g-, 12 to 30 mole /O-8 The permeability o~ isobutylene~isoprene copoly~
9 mers increases exponentially with isoprene content - it de-creases exponentially with cy lopentadiene content in iso-ll butylene~cyclopentadiene copolymeræ - it i8 almost additive l2 for terpolymers of isobutylene-isoprene~cyclopentadiene.
13 Thus, the effect of the addition of one unit of isoprene to 14 the isobutylene chain can be counteracted by the effect of addition of one unit of cyclopentadiene in the resultant l6 impermeability value. Thus if the permeability of poly-isobutylene (or the low isoprene unsaturates, i.e. the butyl 8 rubbers) is found to be about 1 x 10~8 (cm2 secl) under l9 given-test conditions it will remain unchanged at isoprene/
cyclopentadiene levels of 5/5, 10/10, 20/20 etc. If the 21 ratio iæ changed, e.gO, to 10/20 then the permeability would 22 resemble more the behavior of the predominate structure 23 (i.e. cyclopentadiene). The reverse would hold for a ratio 24 e.g. of 20/10.
2s Thus, the process of this invention penmits the 26 preparation of isoolefin copolymers and terpolymers, hereto-27 fore unattainable9 which surprisingly retain all the advan-28 tageous characteristics of conventional low unsaturation 29 butyl ru~ber while exhibiting improved vulcanization char-acteristics and in some case~9 eOgO, cyclodiene containing ~1 copolymers and terpolymers, improved ozone resistance and 32 air impermeability.

, li3(~047 The tenm "substantially gel free" a8 used in the specification and claims means copolymers containing less than 2 wt. % gel; m~re preferably less than 1% gel~ e.g., l/Z7. gel. The term "~" where ~ is an integer means the volume % cyclopentadiene in a monomer mixture wherein D
represents cyclopentadiene and the integer is the volume X diene.

DETAILED DESCRIPTION
The sdvantages of the physical properties of the o compositions of the present lnvention cgn be more readily appreciated by reference to the following examples and tables.

B

113(~047 The quantities of the reactants used in the pre-3 parations of these copolymers and terpolymers were measured 4 as volumes at -78C and the volumes converted to moles were needed using well certified density values~
6 Monomer mixes comprising varying amounts of iso-7 butylene and isoprene and in some experiments cyclopenta-8 diene also, were polymerized in the presence of an appropriate 9 quantity of methylcyclohexane cosolvent. The polymerization was initiated using an 0.06LM solution of ethylaluminum 11 dichloride added at a rate ~uch as to maintain the reactor 12 temperature within 2 of the indicated polymerization temp-13 erature. In some instances small quantities of an 0.031M
14 solution of ~Cl were utilized wherein the ~Cl serves as a cocatalyst for the polymerization. All polymerizations were 16 conducted in a dry inert atmosphere. The reactors were 17 carried out over about a 40 minute period at which time they - 18 were terminated by the addition of a small quantity of 10%
19 propanol in pentane. The reactor solutions were then treated briefly with gaseous NH3 and coagulated by pouring them into -21 hot methanol containing an antioxidant. Polym~r samples 22 were tried in vacuo at about 60C. Polymerization details 23 are presented in Table l.
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P~ ~ _l o~ o~ ~o 00 1 o~ o :

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113(~4~

2 The polymers of Example I were formulated as 3 follows:
4 Polymer: 100 parts by weight Zinc stearate 1.65 6 HAF Carbon black 60 . `
7 Hydrocarbon oil plasticizerl20 8 Antioxidant 1.11 9 . Zinc oxide 5 - 10 Sulfur 2.5 11 Sulfenamide accelerator3 0.75 12 lFIexon 845; ASTM Type 4 13 2Thermoflex~A; 50% N-phenyl-beta-naphthylamino; 25%
14 p,p'dimethoxy-diphenyl amine; 25~/o diphenyl-p-phenylene diamine 16 3Santocure NS; N-tertiary butylbenzothiazole-2-17 sulfenamide.
18 Samples were vulcanized at 336F to provide approx-19 imately equivalent crosslink densities. The physical pro-perties of the vulcanized samples from Table 1 are presented 21 in Table 2.
~ r~ ~k _ 24 -1~3~47 o ~ ~ ~ ~o ~ ~ 1 6~ ,1 O ~ _I ~1 ~1 1 ~1 æ I t t ~ u~ o ~ O ~ ~ ~ C~ CO j ~ ~
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i~i ~ ~ u~ o u~ o o I ~ o ~ u~ ~ o ~ ~ a~
~ ~ ~ s~

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_ 25 ~

' .

113~4q 1 Since many modifications and variations of this 2 invention may be made without departing from the spirit or 3 scope of the invention thereof, it is not intended to limit 4 the spirit or scope thereof to the specific examples thereof.
The practice of this invention can involve batch 6 or continuous polymerizations either isothermal or multi-7 temperature. Continuous polymerization is preferred since 8 it i8 more convenient for commercial operation and gives 9 more uniform (homogeneous) products. Molecular weight dis-tributions (Mw/Mn) are preferably between 2.0 and 20.

Claims (20)

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

1. A substantially gel free polymer consisting essen-tially of a major portion of an isoolefin having 4 to 10 carbon atoms and 5 to 45 mole % of at least one conjugated diolefin of 5 to 9 carbon atoms, said polymer having a number average molecular weight of 90,000 to 120,000.

2. The product of claim 1, wherein the isoolefin is isobutylene, 2-methyl-1-butene, 3-methyl-1-butene or mixtures thereof and the diolefin is 4-methylcyclopentadiene, cyclo-pentadiene or mixtures thereof.

3. The product of claim 1, wherein the isoolefin is isobutylene and the diene is isoprene, piperylene, methylcyclo-pentadiene or cyclopentadiene.

4. The product of claim 1, wherein the isoolefin is isobutylene and the diene comprises a blend of cylcopentadiene as a first diene and a second diene which is isoprene, pipery-lene or methylcyclopentadiene.

5. The product of claim 4, wherein the polymer com-prises at least 5 mole % cyclopentadiene.

6. The product of claim 4, wherein the diene content is 8 to 40 mole %.

7. The product of claim 1, wherein the diene is present in the polymer at 8 to 40 mole %.

8. A vulcanizable composition which comprises:
(a) a major portion of a substantially gel-free polymer consisting essentially of an isoolefin having 5 to 10 carbon atoms and 5 to 45 mole % of at least one conjugated diene, said polymer having a number average molecular weight of 90,000 to 120,000;
(b) a vulcanizing amount of a sulfur donor; and (c) a delayed action accelerator.

9. The composition of claim 8, wherein the isoolefin is isobutylene and the diene is isoprene, piperylene, methylcyclopentadiene, or cyclopentadiene.

10. The composition of claim 8, wherein the isoolefin is isobutylene and the diene comprises a blend of cyclopentadiene as a first diene and a second diene which is isoprene, piperylene or methylcyclopentadiene.

11. The composition of claim 10, wherein the polymer comprises at least 5 mole % cyclopentadiene.

12. The composition of claim 10, wherein the diene content is about 8 to about 40 mole %.

13. The composition of claim 10, wherein the first diene content is about 8 to about 30 mole %.

14. The composition of claim 8, wherein the delayed action accelerator is a benzothiazole sulfenamide present at 0,5 to 3 wt. % based on the polymer.

15. The composition of claim 8, wherein a retarder having a pKa value of less than 7 is incorporated therein.

16. The composition of claim 8, wherein an activator is included said activator being selected from the group con-sisting of:
(1) oxides, hydroxides and alkoxides of metals of Groups IA and IIA of the Periodic Table of Elements; and (2) organic compounds having a pKa value of 8 to 14.

17. The composition of claim 8, further including a filler at 5 to 350 parts by weight per one hundred parts of said polymer.

18. The composition of claims 8, further including a non-polar process oil at 5 to 200 parts by weight based on one hundred parts of said polymer.

19. The composition of claims 8, 17 and 18, further including an ester plasticizer at a concentration level of 5 to 100 parts by weight per one hundred parts of said polymer.

20. The composition of claims 8, 17 and 18 further including a rubber at a concentration level of 5 to 95 parts by weight per one hundred parts of the total of said rubber and said polymer, said rubber being selected from the group consist-ing of non-polar crystallizable rubbers, polar crystallizable rubbers, non-polar, non-crystallizable rubbers, and polar non-crystallizable rubbers.