3,205,214 United States Patent Office Patented Sept. 7, 1965

2 usual catalytic amount of the two catalytic components 3,205,214 can be used within the range of, for example, 0.2 to about PPERYLENE POLYMERZATION Thomas B. Taicott, Wadsworth Township, Ohio, assignor 20 millimoles per 100 grams of monomer. to The Firestone Tire & Rubber Company, Akron, Piperylene can be polymerized by the method of the Ohio, a corporation of Ohio 5 invention either as the sole monomer or in the presence No Drawing. Filed May 15, 1961, Ser. No. 109,814 of one or more additional ethylenically unsaturated com 2 Claims. (C. 260-94.3) pound, with which it may or may not copolymerize, de pending upon the specific monomer and the specific cata This invention relates to the polymerization of piperyl lyst combination. For instance, a mixed hydrocarbon ene, either cis-piperylene or trans-piperylene or a mixture O stream containing both piperylene and isoprene can be of the two, and other monomers may be present. The treated to polymerizing conditions in accordance with the invention relates more particularly to a process of polym-. invention to polymerize the piperylene selectively, leaving erization using a catalyst containing iodine, either in com all or most of the isoprene in the stream unpolymerized. bined or initially uncombined form. . A different catalyst ratio or combination within the scope A piperylene polymer produced by the invention con 15 of the invention can be utilized to produce a piperylene tain in the piperylene portion over 98 percent 1,4-addi isoprene copolymer. On the other hand, a hydrocarbon tion microstructure, and unexpectedly it is over 85 percent stream containing both piperylene and butadiene-1,3 can trans-1,4-addition polymer. The polymer of such high be copolymerized to a useful rubbery polymer by the in content of the trans-stereo isomer tends toward crystal vention. Other monomers can be copolymerized with linity, is tough and exceptionally strong; and the more 20 piperylene by means of the invention, including, with nearly the trans-isomer content approaches 100 percent, out limitation, styrene, alpha-methylstyrene, vinyltoluene, the more accentuated are these properties. The high con chlorostyrene, 2,3-dimethylbutadiene-1,3 and other Suit tent of trans-1,4-addition is surprising, because when able alpha-olefins. butadiene is polymerized in the same catalyst system, the Any hydrocarbon solvent for the monomer can be used, percentage of cis-1,4-addition in the product is high. :25 such as pentane, hexane, petroleum ether, heptane, octane, The catalyst of the invention comprises a hydrocarbon benzene, toluene, a xylene, isoprene or other hydrocarbon aluminum compound and a halide of titanium or zirco solvent that is liquid at the polymerization temperature. nium, there being at least about one atom of iodine present A mixture of solvents, e.g., xylene and pentane, can be for each atom of the Group IV metal in the catalyst. This used. Excess piperylene can be used as solvent. A polym iodine requirement can be met by use in the catalyst corn 30 erization temperature of about 0 to 100° C. is Satisfac bination of titanium tetraiodide, Tils, Tia, TilgCl2, tory. TilBr, TiBrC1, TiCl, TilBrand similar halides. The The following examples illustrate the invention. All iodine requirement can also be met by including in the parts and percentages are by weight unless otherwise indi catalyst makeup an iodine-containing organoaluminum cated. In Examples 3-5, trans-piperylene (substantially compound, such as an alkylaluminum diiodide, a dialkyl 35 free of cis-piperylene) was subjected to polymerization. aluminum iodide, an alkylaluminum chloroiodide and sim ‘The first example describes the preparation of this mate ilar compounds; in which case at least sufficient of the rial. aluminum compound is utilized to provide the required EXAMPLE 1-PREPARATION OF TRANS amount of iodine in the catalyst. A further alternative . catalyst is provided by addition of elemental iodine to a 40 PIPERYLENE hydrocarbon aluminum-titanium chloride or bromide (or The piperylene used was a by-product from the prep the analogous zirconium salts) catalyst, sufficient iodine aration of isoprene and had the following analysis: being provided to supply at least about one atom of iodine Percent per atom of the Group IV metal present. Mixtures of 45 Trans-piperylene ------58.6 the various catalyst combinations outlined above are op Cis-piperylene ------34.5 erable so long as the iodine requirement is met. The molar Isoprene ------1.2 ratio of aluminum compound to the Group IV metal halide Cyclopentadiene ------4. in the catalyst is generally 0.5/1.0 to 4.0/1.0, and usually Isopropenyl acetylene ------1.6 in the range of 1/1 to 3.5/1. The aluminum component of the catalyst can, for ex 50 The cyclopentadiene and isopropenyl acetylene are gen ample, be trimethyl aluminum, triethyl aluminum, any erally considered polymerization inhibitors. The former tripropyl aluminum, any tributyl aluminum or any other was removed by reaction with maleic anhydride; the lat trialkyl aluminum in which the alkyl group contains up ter was removed by admixture with a reagent containing to about 8 or 10 carbon atoms, e.g., trioctyl-, trinonyl-, and the cuprous ion. tridecyl-aluminum; tribenzylaluminum or phenyldibutyl 55 Pure trans-piperylene was produced from the purified aluminum; or it can be an alkyl aluminum chloride of the mixture of cis- and trans-isomers by the sulfone method formula alkyl, AlCly in which x and y are whole numbers of David Craig, Journal of the American Chemical So that total 3, such as dibutyl aluminum chloride, ethyl ciety, volume 65, page 1006 (1943). The product (trans aluminum dichloride, etc., and in which the alkyl group piperylene) was completely free of cis-piperylene and can be any of the foregoing alkyl groups which contain 60 contained less than 1 percent of isoprene as the only im upto 8 or 10 carbon atoms. The alkyl groups can be purity. straight or branched chain and any one aluminum com EXAMPLE 2 ponent can contain alkyl groups in which there are a different number of carbon atoms. Analogous alkenyl The piperylene used in this experiment was a mixed groups can be substituted for the alkyls named above. Any 65 piperylene which in addition to a trace of isoprene con 3,205,214 3. 4 tained about 63 percent trans-piperylene and 37 percent invention with hevea rubber, synthetic cis-polyisoprene, cis-piperylene. The details of the process and an analysis butadiene-styrene synthetic rubbers and/or with poly of the product are given in Table I. The amount of each butadiene rubbers are usefully vulcanized into pneumatic catalyst component is given as millimoles per each 100 tire treads, sidewalls and body stocks, as well as into grams of piperylene used. many mechanical rubber goods. The unvulcanized poly piperylene can be chlorinated to provide a useful sub EXAMPLES 3-5 stitute for chlorinated natural rubber in coatings and ad The trans-piperylene of Example 1 and benzene were hesives. dried by distilling off a portion and discarding the distill What is claimed is: late. Three polymerization bottles were charged with 1. The process of polymerizing piperylene which com the monomer and solvent. They were then capped, using 0. prises treating the piperylene in a hydrocarbon solvent at rubber liners; the catalyst components were injected a temperature between 0 and 100° C. with 0.2 to 20 milli through the liners so that they reacted and formed the moles of catalyst per 100 moles of monomer, the catalyst active catalyst in situ; and the bottles were turned end being composed of a trialkyl aluminum compound and a over-end in a polymerization bath. The details of the halide of titanium that includes at least one atom of iodine charges, the polymerization process, and the products are for one atom of titanium, the molar ratio of the aluminum summarized in the following table where they are des compound to the halide being within the range of 0.5/1 ignated Examples 3, 4 and 5. The charge is given in to 4/1. grams. The microstructures of the products were deter 2. The process of claim 1 in which the titanium halide mined by known infrared technique. 20 is titanium tetraiodide. Table I-Polymerization of piperylene

Example 2 Example 3 Example 4 Example 5

Mixed Piperylenes (g).------Trans-Piperylene (g.)-- 00. Benzene (g.)------200. Al(CH5)3(mm. perf100 g. monomer). 4.4. Ti4 (mm. perf100 g. monomer)------O. 1.76. Molar Ratio, Al(CH5)3/Til------3.0------2.5------2.5. Temperature (C.) and Time (hours).------72hrs. at 30 20 hrs. at 5°; 24 hrs. at 5°; 52 hrs. at 48 hrs., at Appearance of Polymer Solution------ser st Conversion, percent------774------REso...I SESs. Microstructure: cis-1,4 percent.------16.2------10.7------4.4. trans-1.4 percent------83.8--- 88.4------. 94.8 1,2 percent------0.0------0.9------0.8.

In Examples 3-5, polymerization was slight at 5 C., References Cited by the Examiner but was substantial at about room temperature, and po 40 lymerization in the range of about 15 to 50 C. is pre UNITED STATES PATENTS ferred. The high content of trans-1,4-addition polymer 2,959,576 11/60 Payne ------260-94.9 is characteristic of all of these products. 2,979,488 4/61 Carpenter ------260-79 The polypiperylene of the invention, its copolymers 2,999,087 9/61 Thomas et al. ------290-94.3 with other diolefins and its copolymers in which it pre 45 3,050,513 8/62 Zelinski et al. ------260-94.3 dominates are ethylenically unsaturated polymers, more FOREIGN PATENTS or less rubbery in nature, and capable of being vulcanized to a more elastic, less thermoplastic condition by means 827,365 2/60 Great Britain. of known curing agents of natural rubber and butadiene OTHER REFERENCES styrene synthetic rubber. Vulcanization accelerators use 50 Natta et al.; “Stereospecific Catalysts and Stereoregular ful in these prior art general purpose rubbers are gen erally effective in speeding the cure of the novel piperylene Addition Polymers,” volume III, article No. 80, 1958. polymers. The polymers of the invention, especially in JOSEPH L. SCHOFER, Primary Examiner. the vulcanized state, exhibit excellent resistance to ozone. Blends of the unvulcanized piperylene polymers of the 55 L. H. GASTON, LEON J. BERCOVITZ, Examiners.