3,299?-l7 United States Patent 0 " IC€ Patented Jan. 17, 1967

1 2 amount of a norbornadiene. As determined by infrared 3,299,017 analysis, the product obtained from this polymerization COlPOLYMlERS OF 1,3-BUTADIENE AND A NORBORNADHENE reaction is a copolymer of 1,3-butadiene and a norborna Robert P. Zelinski and Floyd E. Naylor, lliartlesville, diene in which at least 85 percent, e.g., from 85 to 98 Okla, assignors to Phillips Petroleum Company, a cor percent and higher, of the butadiene units have a cis 1,4 poration of Delaware con?guration. This novel copolymer has a greatly re No Drawing. Filed Apr. 29, 1963, Ser. No. 276,166 duced tendency to cold flow while still retaining the desir 12 ‘Claims. (Cl. 26tl—82.l) able physical properties of conventional cis-polybutadi ene. Furthermore, the copolymer of this invention pos This invention relates to novel polymers of 1,3-butadi sesses improved processing characteristics. For example, ene. In one aspect, it relates to a method for producing in the compounding of the copolymers, shorter mixing a polymer of 1,3-butadiene having a reduced tendency to times are required. This results from the fact that there cold ?ow. In another aspect, it relates to a method for is a more rapid heat buildup during mixing as compared improving the processability of polymers of 1,3-butadi to conventional cis-polybutadiene, which facilitates the ene. 15 incorporation of compounding ingredients. Further A great deal of research work has been conducted dur more, the novel copolymers have better extrusion and ing the last few years with the object of producing im milling characteristics and exhibit a considerably longer proved rubbery polymers. One of the products that has scorch time than cis-polybutadienes prepared according to attracted widespread attention because of its superior previous methods. When copolymers prepared in ac properties is a polybutadiene containing a high percent cordance with the process of this invention are blended age, e.g., at least 85 percent, of cis 1,4-addition. The with other rubbers, e.g., a copolymer of butadiene ‘and physical properties of this polymer are of such a nature styrene, the resulting compositions have better processing that it is particularly suitable for the fabrication of auto characteristics than those prepared ‘with conventional cis mobile and truck tires and other articles for which con polybutadiene. Other unsaturated cyclic compounds, ventional synthetic polymers have heretofore been com 25 such as 1,5-cyclooctadiene, cyclododecatriene, dicyclopen paratively unsatisfactory. However, in the processing of tadiene, norbornylene (bicycloheptene), and cyclooctate the polymer, particularly in packaging, shipping and stor~ traene, have been added to polymerization ‘systems em age, a certain amount of dif?culty has been encountered ployed in producing cisapolybutadiene, but these mate because of the tendency of the polymer to cold ?ow when rials were found to have little, if any, effect on the prop in the unvulcanized state. For example, if cracks or 30 erties of the polymer products. It was completely unex punctures develop in the packages used in storing the pected, therefore, when it was found that the addition of polymer, polymer will flow from the packages with a re a norbornadiene to the polymerization systems resulted sulting loss or contamination and sticking together of the in the formation of a copolymer having such outstanding stacked packages. It has also been found that cis-poly properties. butadiene is often dif?cult to process. It is essential that 35 The norbornadienes, often referred to \as bicyclo(2,2, a polymer be processable, for otherwise its use is seriously 1)-hepta-2,5-dienes, employed in the practice of the pres limited. ent process can be represented by the formula It is an object of this invention, therefore, to provide a polybutadiene composition containing a high percent age of cis 1,4-addition, which has a reduced tendency to 40 cold ?ow when in the unvulcaniz-ed state and which pos sesses improved processing characteristics. Another object of the invention is to provide a method for eliminating or substantially reducing the tendency of cis-polybutadiene to cold flow when in the unvulcanized 45 state. Still another object of the invention is to provide a proc ess for improving the processability of cis~polybutadiene. A further object of the invention is to provide a novel copolymer of 1,3-butadiene and a norbornadiene. 50 Other and further objects and advantages of the inven tion will be apparent to those skilled in the art upon con sideration of the accompanying disclosure. wherein R is hydrogen or an alkyl group containing from The present invention is concerned with the production 1 to 4, inclusive, carbon atoms and wherein at least two of polymers of 1,3-butadiene having a reduced tendency 55 of the R groups are hydrogen. It is often preferred to to cold ?ow ‘and possessing improved processing charac use norbornadiene itself, i.e., the compound according to teristics. Thus, the invention relates to an improvement the foregoing formula in which each R is hydrogen. Of in a process for polymerizing 1,3-butadiene with a cata the a-lkyl derivatives, it is generally preferred to use those lyst system which forms on mixing components compris that are substituted in the 7-position. Examples of these ing an organometal component and an -containing 60 latter compounds include 7-methylnorbornadiene, 7~ethyl component. Broadly speaking, the improvement com norbornadiene, 7-n-propylnorbornadiene, 7-isopropylnor prises adding to the polymerization mixture a minor bornadiene, 7-n-butylnorbornadiene and 7-t-ert-butylnor 3,299,017 3 4 bornadiene. Other examples of norbornadienes that can and titanium tetrachloride; triphenyl be employed are l-methylnorbornadiene, 2-methylnor_ aluminum, titanium tetrachloride and iodine; tri - alpha - bornadiene, Z-ethylnorbornadiene, l-isopropylnorbornadi naphthylaluminum, titanium tetrachloride and iodine; ene, 2-n-butylnorbornadiene, and the like. tribenzylaluminum, titanium tetrabromide and iodine; di As mentioned above, only a minor amount of the nor ethylmagnesium, titanium tetrachloride and hydrogen bornadiene is added to the polymerization system. The ; diphenylmagnesium, titanium tetrabromide and actual amount used will depend, at least to some degree, ; triethylalurninum, titanium tetrachloride upon the particular type of product desired. The amount and hydrogen iodide; diethylmalgnesium, titanium tetra is usually in the range of 0.01 to 10 parts by weight, pref chloride, and ; tri-n-butylaluminum, titanium erably in the range of 0.05 to 2 parts by weight, per 100 tetrabromide and lithium iodide; diisobutylaluminum hy parts by weight of monomer. The norbornadiene can be 10 dride, titanium tetrachloride and lithium iodide; diphenyl added to the polymerization zone by itself or it can be magnesium, titanium tetrachloride and iodine trichloride; charged as a solution in a hydrocarbon, preferably similar triethylaluminum, titanium tetrachloride and iodine mono to ‘the hydrocarbon used as the polymerization diluent. ‘chloride; diphenylaluminum hydride, titanium tetra The novel copolymer of this invention can be prepared 15 bromide and iodine tribromide; triisobutylaluminum, ti \by polymerizing 1,3-butadiene and a norbornadiene with tanium tetrachloride and isobutyl iodide; triethylalurni any one of a large number of stereo-speci?c catalyst num, titanium tetrachloride an ; diethylmag systems. It is usually preferred to employ a catalyst nesium, titanium tetrabromide and methyl iodide; di which is selected from the group consisting of (1) a phenylzinc and titanium tetraiodide; di - 2 - tolylmercury catalyst which forms on mixing components comprising and titanium tetraiodide; tricyclohexylaluminum, titanium an organometal compound having the formula RmM, tetrachloride and titanium tetraiodide; ethylcyclopentyl wherein R is an alkyl, cycloalkyl, aryl, alkaryl, aralkyl, zinc and titanium tetraiodide; tri (3-isobutylcyclohexyl) alu alkylcycloalkyl, cycloalkylalkyl, arylcycloalkyl or cyclo minum and titanium tetraiodide; tetraethyllead, titanium alkylaryl radical, M is aluminum, mercury, zinc, beryl tetrachloride and titanium tetraiodide; trimethylphenyl lium, cadmium, magnesium, sodium or potassium, and 25 lead, titanium tetrachloride and titanium tetraiodide; di m is equal to the valence of the metal M, and titanium phenylmagnesium and titanium tetraiodide; di - n - propyl tetraiodide, (2) a catalyst which forms on mixing com magnesium, titanium tetrachloride and titanium tetra ponents comprising an organometal compound having iodide; dimethylmagnesium, titanium tetrachloride and the formula RnM', wherein R is an organo radical as iodine; diphenylmagnesium, titanium tetrabromide and de?ned above, M’ is aluminum, magnesium, lead, sodium 30 iodine; methylethylmagnesi-um, and titanium tetraiodide; or potassium, and n is equal to the valence of the metal dibutylberyllium and titanium tetraiodide; diethylcadmium M’, titanium tetrachloride and titanium tetraiodide, (3) a and titanium tetraiodide; diisopropylcadmium an titanium catalyst which forms on ‘mixing components comprising an tetraioide; triisobutylaluminum, titanium tetrachloride, organometal compound having the formula RaM” or and antimony triiodide; triisobutylaluminum, titanium RzAlH, wherein ‘R is an organo radical as de?ned above, 35 tetrachloride and aluminum triiodide; triisobutylalumi M" is aluminum or magnesium and a is equal to the num, titanium tetrabromide, and aluminum triiodide; tri valence of the metal M”, a compound having the formula ethylalurninum, titanium tetrachloride and phosphorus TiXb, wherein X is chlorine or bromine and b is an triiodide; tri - n - dodecylaluminum, titanium tetrachloride, integer from 2 to 4, inclusive, and elemental iodine, and tin tetraiodide; triethylgallium, titanium tetrabromide, hydrogen iodide, lithium iodide, an iodine halide, or an 40 and aluminum triiodide; tri - n - butylaluminum, titanium iodohydroca-rbon, (4) a catalyst which forms on mixing tetrachloride, and antimony triiodide; tricyclopentylalu components comprising an organometal compound having minum, titanium tetrachloride, and tetraiodide; tri the formula RXM’”, wherein R is an organo radical as phenylaluminum, titanium tetrachloride, and gallium tri de?ned above, M’” is aluminum, gallium, indium or iodide; triisobutylaluminum, titanium tetraiodide and tin thallium, and x is equal to the valence of the metal M’”, 45 tetrachloride; triisobutylaluminum, titanium tetraiodide a titanium halide having the formula TiX4, wherein X and antimony trichloride; triisobutylaluminum, titanium is chlorine or bromine, ‘and an inorganic halide having the tetraiodide and aluminum trichloride; triisobutylalumi formula Mivlc, wherein Miv is beryllium, zinc, cadmium, num, titanium tetraiodide, and ‘tin tetrabromide; triethyl aluminum, gallium, indium, thallium, silicon, germanium, gallium, titanium tetraiodide, and aluminum tribromide; tin, lead, phosphorus, antimony, arsenic, and bismuth, 50 triethylalurninum, titanium tetraiodide, and arsenic tri and c is an integer from 2 to 5, inclusive, and (5) a chloride; and tribenzylaluminum, titanium tetraiodide, and catalyst which forms on mixing components comprising germanium tetrachloride. an organo compound having the formula RXM’”, wherein The polymerization process of this invention is general R, M’” and x are as de?ned above, titanium tetraiodide, ly carried out in the presence of a hydrocarbon diluent and an inorganic halide having the formula MvXd, where 55 which is not deleterious to the catalyst system. Exam in M" is aluminum, gallium, indium, thallium, germanium, ples of suitable diluents include aromatic, para?inic and tin, lead, phosphorus, antimony, arsenic or bismuth, X cyclopara?inic hydrocarbons, it being understood that is chlorine or bromine, and d is an integer from 2 to 5, mixtures of these materials can also be used. Speci?c inclusive. The R radicals of the aforementioned formulas examples of hydrocarbon diluents include benzene, tolu preferably contain ‘up to and including 20 carbon atoms. 60 ene, n-butane, isobutane, n-pentane, isooctane, n-dodecane, The following are examples of preferred catalyst sys cyclopentane, cyclohexane, methylcyclohexane, and the tems which can be used to polymerize 1,3-butadiene to like. It is often preferred to employ aromatic hydrocar a cis 1,4-polybutadiene; triisobutylaluminum and titanium bons as the diluent. tetraiodide; triethylaluminum and titanium tetraiodide; The amount of the catalyst employed in copolymer triisobutylaluminum, titanium tetrachloride and titanium 65 izing 1,3-butadiene and a norbornadiene can vary over tetraiodide; triethylalurninum, titanium tetrachloride and a rather wide range. The amount of the organometal titanium tetraiodide; diethylzinc and titanium tetraiodide; used in forming the catalyst composition is usually in the dibutylmercury and titanium tetraiodide; triisobutylalu range of 0.75 to 20 mols per mol of the halogen-contain minum, titanium tetrachloride and iodine; triethylalumi ing component, i.e., a metal halide with or without a num, titanium tetrabromide and iodine; n-amylsodium second metal halide or elemental iodine. The mol ratio and titanium tetraiodide; phenylsodium and titanium tetra actually used in a polymerization will depend upon the iodide; n-butylpotassium and titanium tetraiodide; phenyl particular components employed in the catalyst system. potassium and titanium tetraiodide; n-amylsodium, ti However, a preferred mol ratio is generally from 1:1 to tanium tetrachloride and titanium tetraiodide; triphenyl 12:1 of the organometal compound to the halogen~con aluminum and titanium tetraiodide; triphenylaluminum, 75 taining component. When using a catalyst prepared from 3,299,017 5 6 an organometal compound and more than one metal decantation or ?ltration. It is often preferred to add ini halide, e.g., titanium tetrachloride and titanium tetra tially only an amount of the catalyst-inactivating material iodide, titanium tetrachloride or tetrabromide and alu which is sufficient to inactivate the catalyst without caus minum iodide, the mol ratio of the tetrachloride or tetra ing precipitation of the polymer. It has been found to bromide to the iodide is usually in the range of 0.05:1 be advantageous to add an antioxidant, such as 4,4’ to 5:1. With a catalyst system formed [from an organo methylene-bis(2,6-di~tert-butylphenol), to the polymer metal compound, a titanium chloride or bromide, and solution prior to recovery of the polymer. After addi elemental iodine, hydrogen iodide, lithium iodide, an io tion ‘of the catalyst-inactivating material and the antioxi dine halide or an iodo-hydrocarbon, the mol ratio of ti dant, the polymer present in the solution can then be tanium halide to iodine-containing component is general 10 separated by the addition of an excess of a material such ly in the range of 10:1 to 0.25:1, preferably 3 :1 to 0.25: 1. as ethyl alcohol or isopropyl alcohol. It is, ‘of course, The concentration of the total catalyst composition, i.e., to be realized that it is within the scope of the invention organometal and halogen-containing component, is usual to employ other suitable methods to recover the poly ly in the range of 0.01 to 10 weight percent, preferably mer. After separation .from the water and alcohol and in the range of 0.01 to 5 weight percent, based on the 15 diluent by ?ltration or other suitable means, the poly total amount of 1,3-butadiene charged to the reactor mer is then dried. system. - The coplymers produced in accordance with this in The process of this invention can be conducted at tem vention are rubbery polymers. The polymers can be peratures varying over a rather wide range, e.g., from compounded by the various methods that have been used —100 to 250° F. It is usually preferred to operate at 20 in the past in compounding natural and synthetic rubbers. a temperature in the range of ——30 to 160° F. The Vulcanization accelerators, vulcanizing agents, reinforc polymerization reaction can be carried out under autog ing agents, and ?llers such as have been employed in enous pressure or at any suitable pressure suf?cient to natural or synthetic rubbers can likewise be used in com maintain the reaction mixture substantially in the liquid pounding the rubbers of this invention. It is also within phase. The pressure will thus depend upon the particu 25 the scope of this invention to blend the polymers with lar diluent employed and the temperature at which the other polymeric material such as natural rubber, cis 1,4 polymerization is conducted. However, higher pressures polyisoprene, polyethylene and the like. As mentioned can be employed if desired, these pressures being ob previously, the polymers of this invention have a very tained by some such suitable method as the pressuriza high cis-content, and this property renders them very suit tion of the reactor with a gas which is inert with respect 30 able for applications requiring low hysteresis, high re to the polymerization reaction. silience and low freeze point. In general, the products The process of this invention can be carried out as a have utility in applications where natural and synthetic batch process by charging 1,3-‘butadiene and the norborna rubbers are used. They are particularly suitable for use diene to a reactor containing catalyst and diluent. Al~ in the manufacture of automobile and truck tires and though any suitable charging procedure can be used, it 35 other rubbery articles, such as gaskets. is often preferred to add the monomers to a reactor con A more comprehensive understanding of the invention taining diluent and thereafter introduce the catalyst com can be obtained by referring to the following illustrative ponents. It is to be understood that it is within the scope examples which are not intended, however, to be unduly of the invention to preform the catalyst by mixing the limitative of the invention. catalyst components within a separate catalyst prepara 40 tion vessel. The resulting mixture can then be passed EXAMPLE I into the reactor containing the monomers and diluent, or these latter materials can be added after the catalyst. A series of runs was carried out in which 1,3-butadiene The process can also be carried out continuously by main Was copolymerized with variable quantities of norborna taining the above-mentioned concentrations of reactants 45 diene using a catalyst formed by mixing triisobutylalumi in the reactor for a suitable residence time. In a con num, titanium tetrachloride and iodine. Control runs tinuous process the residence time will, of course, vary were also conducted in which no norbornadiene was pres within rather wide limits, depending upon such variables ent in the polymerization system. The following recipe as temperature, pressure, the ratio of catalyst components was employed in the runs: and the catalyst concentration. The residence time in 50 a continuous process usually falls within the range of Recipe one second to two hours when conditions within the spec Parts by weight i?ed ranges are employed. When a batch process is 1,3-butadiene ______100 utilized, the time for the reaction can be as high as 24 Toluene ______1000 hours or more. Norbornadiene (NBD) ______Variable Various materials are known to be detrimental to the Triisobutylaluminum (TBA) ______Variable catalyst employed in the present process. These materials Iodine (I2) ______Variable include carbon dioxide, oxygen and water. It is usually Titanium tetrachloride (TTC) ______Variable desirable, therefore, that the butadiene, the norbornadiene TBA/Iz/TTC mol ratio ______6/2/1 and diluent be freed of these materials as well as other 60 Temperature, ° F ______41 materials which may tend to inactivate the catalyst. Fur Time, hours ______2 thermore, it is desirable to remove air and moisture from the reaction vessel in which the polymerization is to be The procedure followed in each of the runs was to conducted. charge the toluene ?rst to the reactor. After purging the Upon completion of the polymerization in which the 65 reactor with nitrogen, the l,3—'butadiene was introduced. copolymer ‘of butadiene and a norbornadiene is prepared, The norbornadiene was then added, followed by the tri the reaction mixture is then treated to inactivate the iso'butylaluminum and iodine, each of the three materials catalyst and recover the rubbery polymer. Any suitable being in toluene solution. The mixture was then cooled method can be employed in carrying out the treatment of to 41° F., after which titanium tetrachloride was charged. the reaction mixture. In one method the polymer is re 70 After a two hour polymerization period, the reaction was covered by steam stripping the diluent from the polymer. terminated by adding one part by weight of 2,2’~methyl In another suitable method, a catalyst-inactivating mate ene-bis(4-methyla6-tert-butylphenol) dissolved in a mix rial, such as an alcohol, is added to the mixture so as ture of equal volumes of isopropyl alcohol and toluene. to inactivate the catalyst and cause precipitation of the The polymer was then coagulated in isopropyl alcohol, polymer. The polymer is then separated from the al— 75 separated and dried. The results of the runs are shown cohol and diluent by any suitable method, such as by below in Table I. 3,299,017

TABLE I

TBA, I’, TTO, NBD, Conv., Cold ML~4 4 Run No. mhm.l mhm 1 mhm.l phm.? percent Flow,3 at 212° F. lug/min.

2. 2 0. 734 0. 367 0 72 7. 3 43 2. 4 0.8 0. 4 0 64 21 23 2. 6 0. 866 0. 433 0 62 30 20 2. 8 0. 933 0. 467 0 62 34 17 2. 2 0. 734 0. 367 0. 1 66 5. 5 34 2. 4 0.8 0.4 0. 1 60 13 29 2. 6 0. 866 0.433 O. 1 62 17 24 2. 8 0. 933 0.467 0. 1 62 23 18 2. 2 0. 734 0. 367 0. 2 70 1. 7 48 2. 4 0.8 0. 4 0.2 65 5. 3 33 2. 6 0. 866 0.433 0. 2 62 9. 3 27 2.8 0. 933 0.467 0. 2 60 15 20 2. 4 0.8 0.4 0.4 65 2.0 30 2. 6 0. 866 0.433 O. 4 58 7. 7 28 2. 8 0. 933 0.467 0. 4 58 9. 2 22 3. 0 1. 0 0. 5 0.4 58 15 19 2. 4 0.8 0.4 0.6 67 0.0 60 2. 6 0.866 0. 433 0.6 60 1.1 42 2. 8 0.933 0.467 0. 6 56 3. 1 27 3. 0 1. 0 0. 5 0. 6 60 9. 4 22 2. 6 0. 866 0. 433 0. 8 58 0. 0 43 2. 8 0. 933 0. 467 0. 8 58 0. 6 34 3.0 2.0 0. 5 0.8 90 0.0 ______3. 2 1.07 0.533 0.8 59 3. 6 25

l Millimols per 100 grams of butadiene. 2 Parts by weight per 100 parts by weight of butadiene. 3 Cold flow was measured by extruding the rubber through a M-inch ori?ce at 3.5 psi. pressure and a temperature of 50° 0. (122° F.). After allowing 10 minutes to reach steady state, the rate of extrusion was measured and the values reported in milligrams per minute. 4 ASTM-Dl646-61, Mooney viscometer, large rotor, 212° F., 4 minutes.

The data in the foregoing table show that by copolym- 30 The procedure followed in the runs was the same as that erizing 1,3-butadiene with norbornadiene a product hav- described in Example I. The results obtained are set forth ing a greatly reduced tendency to cold flow is obtained. below in Table II.

TABLE II

NBD, Time, Conv., Cold Inh.2 Gel, ML~4 1 Run No. phm. Hours Percent Flow,1 Vise. Percent at 212° rug/min. F.

0 1.0 70 19 0 2.0 73 12 0 2.5 75 10 0 3.0 70 8.1 0 19 93 2.9 0.1 1.0 68 7.3 0.1 2.0 72 5.1 0.1 2.5 75 4. 0 0.1 3.0 70 3. 0 0.1 10 95 0. 0

1 See appropriate footnote to Table I. Z One-tenth gram of polymer was placed in a wire cage made from 80 mesh screen and the cage was placed in 100 ml. of toluene contained in a wide-mouth, 4-ounce bottle. After standing at room temperature (approximately 77° F.) for 24 hours, the cage was removed and the solution was ?ltered through a sulfur absorption tube of grade 0 porosity to remove any solid particles present. The resulting solution was run through a Medalia type vis cometer supported in a 77° F. bath. The viscometer was previously calibrated with toluene. The relative viscosity is the ratio of the viscosity of the polymer solution to that of toluene. The inherent viscosity is calculated by dividing the natural logarithm of the relative vis cosity by the weight of the soluble portion of the original sample.

EXAMPLE II The data in the foregoing table demonstrate that the cold flow tendency of each of the products was reduced TWO series 0f runs Were Carried out in Which the polyllh- as the polymerization time was extended. Each control erization times were varied. In one series of runs a mix- 60 run (Runs 1 to 5) had a considerably higher cold ?ow ‘(We of 1,343“tadiene and horborhadiehe Was polymerized value than the corresponding run in which norbornadiene while in the other series there was no norbornadiene pres- was present :11}; sin the system. The following recipe was used in the EXAMPLE In

Real. 65 A run was carried out in which a mixture of butadiene pe and norbornadiene. was polymerized. 1n. the presence of a Paris ‘by Weight catalyst formed by mixing triisobutylaluminum, titanium 1,3-butadiene, parts by weight ______-- 100 tetrachloride and iodine. A control run was also con Toluene, parts by weight ______1000 ducted in which there was no norbornadiene present in Triiso‘butylaluminum (TBA), mhm ______2.5 70 the system. The recipe used was the same as that used in Iodine (I2), mhm ______0.8 Example II except that 0.5 iphm or norbornadiene was Titanium tetrachloride (TIC), mhm ______0.4 used instead of 0.1 phm. The polymerization tempera Norbornadiene (NBD), phm ______0.1 or 0 ture used was 41° F. and the polymerization time was 2 Temperature, ° F. ______41 hours. The results of the runs are shown below in Table Time, hours ______Variable 75 III. 3,299,017 10 TABLE III

Cold h/Iierostructurc, Percent 2 Run No. NBD, Conv., Flow, 1 ML--41 Inh.I Gel, phni. Percent rug/min. at 212° F. Vise. Percent C is Trans. V inyl

1 ______._ 0 84 0. 7 40 2. 42 0 94. 0 2. 1 3. 3 2 ______0.5 77 0.0 61 2.75 0 .0 1.8 3.2

1 See appropriate footnote to Tables I and II. 2 Samples of the polymers were dissolved in carbon disul?de to form a solution having 25 grams of polymer per liter of solution. The infrared spectrum of each of the solutions (percent transmission) was then determined in a conventional infrared spectrometer. The percent of the total uusaturation present as trans 1,4-was cal culated according to the following equation and consistent units: e= g , where e =extinetion eoeilicient (liters mols'l-centimeters'l); E=extinetion (log Iu/l); l=path length (centimeters); and c=concentration (mols double bond/liter). The extinction was determined at the 10.35 micron band and the extinction coo?icient was 146 (liters-mols-l-centimeters-l) . The percent of the total unsaturation present as 1,2- (or vinyl) was calculated according to the above equation using, the 11.0 micron band and an extinction coctiicient of 209 (liters-mols-l centimeters“). The percent of the total unsaturation present as cis 1,4‘ was obtained by subtracting the trans 1,4- and 1,2- (vinyl) determined according to the above procedure from the theoretical unsaturation, assuming one double bond per each 04 unit in the polymer. The data in the foregoing table demonstrate that the co- 20 Recipe-Continued P t b _ ht polymer of this invention contained about the same _ M S y Welg amount of cis 1,4-addition as conventional cis-polybuta- Flmfamlnez ——————————————————————————————— —— 1 diam Resin 731 3 ______5 EXAMPLE IV Philric h 5 4 ______-— __ —-- 5 ‘ _ _ _ 25 Sulfur ______1.75 Three runs were carried out in which a mixture of 1,3- NOBS special 5 ______1_() buta-diene and norbornadiene was polymerized m the pres- :I~Iigh.ab1-3~Si.r0n furnace mack _ ence of a triisobutylaiuminum-iodme-titamum tetrachlo- 'Ph-iislcul mlxtul‘e CQHtammg 65 Percent of a Complex (11‘ ride_ catalyst system. The mol ratlo. of these ingredlents. . nrylamine-ketonedlplhepyl-p-phe'nylene(1ja1nine_ reaction product _ and 35 percent of N,N’ in each of the runs was 6/ 1.5/1. A cis-polybutadiene 30 jgglgggocl'gioln?ted D1116 I'OSIII stable to heat and light was also prepared by polymerizing butadiene with a same 5 N,oxydiethyléne_2_benzothiazyl sulfenamide_

TABLE IV

1 2 3 Control

Nonbornadiene, phnl ______. 0. 4 0. 4 0. 5 0. 0 Conversion, percent ______79 84 62 ______._ Mooney (ML-4 at 212° F.)1_.. _ 47 37 33. 5 45 Cold 110w, 1ng./n1in.1 ______. _ 0. 5 0. 6 1. 2 1. 4 compounded Mooney (MS-1% at 212 F.)-_ . 38. 5 32 30. 5 43 Scorch time, min. to 5 point Mooney rise 3 ______23. 8 25. 4 26. 4 16. 0 Extrusion at 250°F.‘*: Inches/minute ...... _ 29 30. 5 35 34. 5 Grams/minute ______90. 5 94 99. 5 95 Rating (Garvey Die) ______._ ___ —8 -—11 —12 +5 B anbnry mixing time to 300° F. dump tempera ture, sec ...... s. 350 285 270 305

Physical Properties of Vulcanizates

u)<104,m01s./cc.5 ______2. 02 1. 90 1. 93 2.13 300 percent Modulus, p.s.i 6 _ 1, 250 1, 180 1, 170 1, 320 Tensile, psi.“ ______- 2, 590 2, 730 2, 730 2, 720 Elongation, percent 5... _ 480 520 530 485 Heat Buildup A T,° FF - 45. 2 47. 7 49. 2 45. 5 Resilience, percent 8 ______76. 5 76. 3 76. 0 76. 5 Shore A hardness 9 ______61 60. 5 61 64

1 See appropriate footnotes to Table I. 2 ASTM D1046-01, Mooney Viscorneter, small rotor, 212° F., 1.5 minutes. 3 ASTM D1046-01, Mooney viscometer, large rotor, Scorch in minutes to 5 point rise above minimum Mooney. 4 No. % Royle Extruder with Garvey die. See Ind. Eng. Chem. 34, 1309 (1042). As regards the “rating” ?gure, 12 designates an extruded product considered to be perfectly formed whereas lower numerals indicate less perfect products. 5 Determined by the swelling method of Kraus as given in Rubber World, October, 1956. This value is the number of effective network chains per unit volume of rubber. The higher the number, the more the rubber is crosslinked (vulcanized). 1‘ ASTM D412'61T. Scott Tensile Machine L-G. Tests are made at 80° F. unless other wise designated. 7ASTM D623-58. Method A, Goodrich Flexometer, 143 lbs/sq. inch load, 0.175 inch stroke. Test specimen is a right circular cylinder 0.7 inch in diameter and 1 inch high. 8 ASTM D945-59 (modified). Yerzley oscillograph. Test specimen is a right circular cylinder 0.7 inch in diameter and 1 inch high. 9 ASTM D676-59T. Shore Durometer, Type A. catalyst system but in the absence of norbornadiene. The Physical properties of the raw polymers, processing four polymers obtained were compounded in accordance data, and properties of the vulcanizates (stocks cured with the recipe shown below. for 30 minutes at 307° F.) are presented above in Table IV. Recipe 70 The three polymers prepared in accordance with the Parts by weight present invention had lower cold ?ow values and better Polymer ______100 processing properties than the control polymer. The Carbon black 1 ______50 scorch time was ‘longer, the extrusion rating was better, . . 3 the Banbury mixing time was shorter, and mill handling Stearic acid ______1 75 was better for these three rubbers than for the control 3,299,017

rubber. The physical properties of the four vulcanized TABLE VI stocks were similar. EXAMPLE V Run N 0. Catalyst Component Monomers

The three polymers_of this invention and the control 5 1 ______Triisobutylaluminum, 1,3-butadienc, 7-mcthyl polymer, as described 1n Example IV, were each blended 2 Ttittalrlullniltetraiodide. 1 sngrbtorinadiene. b t l with- a butadiene-styrene~ rubber that was plastrcized- - w1th- ______r1ctitanium y a u1ninum, tetrachloride’ , norbomadienes_- u a iene, 7-11- u y - a highly aromat1c processlng 011. The butadlene/styrene 3 Dtltlamugntetraiodide. 1 3b t d_ 1 th 1 rubber, wh1ch~ was prepared gby emulsion- polymenzatlon- - ______?mnmm1p leny magnesium, tetrachloride, 'norbomadienc_- u a lene, -e y at 41° F., had a bound styrene content of 23.5 welght 10 4 Tigdnlljet l1 _ 13} t d, 2 th 1 Percent and ‘a M0On§y_ Val“? (ML_4 at 212° of 51' ______>> l'llSOtitanium?’ 11 tetrachloride,21 1111111111111, , norbornadiene.-)L1 {1 10110, 1110 y - The amount of plast1c1zer o1l employed was 37.50 parts 5 Talurréintullultriiodide. 1 31 t d‘ 2_ 1 by weight~ per 100 parts by welght- of the butadiene/sty--v ______. r1150titanium 11 Y 31111111111111,tptmcmoride' norbomadicne., -)H a 19116, 11- p 1'0 “Y - rene rubber. Each of the blends was compounded, and 6 Thygrogeln loghde- 1 3b t d, 1 the processing properties were determined. The cotn- 15 """" " rfiistl’uinui?ii‘auciii’oade, 'dielrliea. me’ 1101 mm. poundmg recipe employed and the processmg properues wdme observed are shown below in Table V.

TABLE V

1 2 3 Control

Compounding Recipe, Parts by Weight

Butadiene/norbomadiene copolymer ...... _ 50 50 50 ______Cis-P olybutadiene- _ 50 Butadiene/styieno rubber 1 ______68.75 68. 75 68. 75 68.75 High abrasion furnace black ______5O 50 50 50 Zinc oxide 3 3 3 3 Stearic acid ______2 2 2 2 Wingstay 100 Z... 1 1 l 1 Age-Rite Resin D a- 2 2 2 2 Para?in wax ______3 3 3 3 Sulfur 1. 75 1. 75 1. 75 1. 75 NOBS Special 4 ______-_ 1. 0 1. 0 1. 0 1. 0

Processing Properties

Banbmy mixing time to 300° F. dump temp, sec 300 280 270 420 Total power, Watt Hours 5 ______- 560 510 490 790 Compounded Mooney (MS-1% at 212 28. 5 25. 0 25.0 30.0 Extrusion at 250° F 8: Inches/minute. 44. s 45. 2 46. 0 4e. 8 Grams/ruinutm 13s. 0 138. 0 140. 0 139. 5 Rating (Garve ll —12 —12 10 Mill banding 1 10 10 1o 3 Mix rating ______- 7 8 8 3

1 The 68.75 parts used contained 50 parts by weight rubber and 18.75 parts by weight highly aromatic processing oil. 2 Mixture of diary1-p—phenylene diamines. 3 Polymerized trimethyldihydroquinoline. 4 N-oxydiethylene-2-benzothiazyl sultenamide. 5 Total power required for mixing operation. 6 See appropriate footnotes to Table IV. 7 Based on a 0-10 rating scale with a high number being best.

The data in Table V show that the blends prepared with the polymers of this invention gave compositions having much better processing properties than the com Infrared analysis of the products of the foregoing runs position prepared with the control polymer. Thus, the shows the presence of units in the polymer attributable blends prepared with the present copolymers required to the cyclic compound, thereby indicating that the prod a shorter mixing time and less power input for mixing, 60 ucts are copolymers of 1,3-butadiene and a norbornadiene. broke down more readily as shown by compounded The copolymers have a reduced tendency to cold How in Mooney values, had a higher extrusion rating, better mill the unvulcanized state and possess good processing prop banding, and a higher mix rating. When the stocks were erties. cured for 30 minutes at 307° F., physical properties of As will be evident to those skilled in the art, many the rvulcanizates were similar. 65 variations and modi?cations of the invention can be practiced in view of the foregoing disclosure. Such var EXAMPLE VI iations and modi?cations are believed to come within the Runs are carried out in which mixtures of 1,3-buta spirit and scope of the invention. diene and various norbornadienes are polymerized with We claim: catalyst systems formed by mixing an organo-metal and 70 1. In a process for polymerizing 1,3-butadiene with an iodine-containing component. The procedure fol an iodine containing catalyst which forms on mixing com lowed in carryingpout the runs is essentially the same ponents comprising an organometal component and a as that described in Example I. The components used titanium halide component, the improvement which coin in preparing the catalyst and the monomers copolymer prises polymerizing said 1,3-‘butadiene with a minor ized in the runs are shown below in Table VI. 75 amount of a norbornadiene having the following formula 3,299,017 14 4. A process according to claim 2 in which said catalyst is one which forms on mixing components consisting essentially of a trialkylaluminum, titanium tetrachloride and titanium tetraiodide. 5. A process according to claim 2 in which said catalyst is one which forms on mixing components consisting essentially of a trialkylaluminum, titanium tetraiodide. 6. A process according to claim 2 in which said catalyst wherein R is selected from the group consisting of hydro is one which vforms on mixing components consisting essentially of a trialkylaluminum, titanium tetrachloride gen and an alkyl group containing from 1 to 4, inclusive, 10 carbon atoms and wherein at least two of said R groups and hydrogen iodide. are hydrogen, to produce a polymer wherein at least 85 7. A process according to claim 2 in which said catalyst percent of the butadiene units have a cis 1,4-con?gura is one which forms on mixing components consisting tion. essentially of a trialkylaluminum, titanium tetrachloride 2. In a process for polymerizing 1,3-butadiene in the 15 and methyl iodide. presence of a hydrocarbon ‘diluent with an iodine con 8. A process according to claim 2 in which said taining catalyst which forms on mixing an organometal norbornadiene is norbornadiene. component and a titanium halide component, the im 9. A process according to claim 2 in which said provement which comprises polymerizing said 1,3-buta norbornadiene is 7-methylnorbornadiene. diene within the range ‘of 0.01 to 10 parts ‘by weight per 10. A process according to claim 2 in which said 100 parts by Weight of said 1,3-butadiene of a norborna norbornadiene is l-ethylnorbornadiene. diene having the following formula: 11. A process according to claim 2 in which said R norbornadiene is 2-methylnorbornadiene. 12. In a process for polymerizing 1,3-butadiene with 25 an iodine containing catalyst which forms on mixing com ponents comprising an organo-metal component and a H~G/(L\C—RHi H R ‘LL11 titanium halide component, the improvement which com~ \ / prises polymerizing said 1,3-butadiene with 0.01 to 10 | parts by weight of norbornadiene, based on 100 parts by H 30 weight of 1,3-butadiene, in the presence of a hydro wherein R is selected from the group consisting of hydro cat'bon diluent at a temperature in the range of —30 to gen and an alkyl group containing from 1 to 4, inclusive, 160° F. and at a pressure sui?cient to maintain said carbon atoms and wherein at least two of said R groups hydrocarbon diluent in liquid phase; and recovering a are hydrogen, said polymerizing occurring at a tempera copolymer of 1,3-butadiene and norbor-nadiene wherein ture in the range of —l00 to 250° F. and at a pressure 35 at least 85 percent of the butadiene units have a cis 1,4 su?icient to maintain said hydrocarbon diluent in liquid con?guration. phase; and recovering a product having a reduced tend ency to cold ?ow in the unvulcanized state wherein at References Cited by the Examiner least 85 percent of the butadiene units have a cis 1,4~ UNITED STATES PATENTS con?guration. 40 3. A process according to claim 2 in which said catalyst 3,220,999 11/1965 Duck et al. ______260——94.3 is one which forms on mixing components consisting JOSEPH L. SCHOFER, Primary Examiner. essentially of a trialkylaluminum, titanium tetrachloride and iodine. E. J. SMITH, Assistant Examiner.