Europaisches Patentamt J European Patent Office Publication number: 0 215 256 Office europeen des brevets A1 EUROPEAN PATENT APPLICATION © Application number: 86110619.3 C08F © int. Ci.<: 236/10 , C08F 4/48 ® Date of filing: 31.07.86 © Priority: 03.09.85 US 771749 © Applicant: THE FIRESTONE TIRE & RUBBER COMPANY @ Date of publication of application: 1200 Firestone Parkway 25.03.87 Bulletin 87/13 Akron, Ohio 4431 7(US) 0 Designated Contracting States: © Inventor: Hall, James E. BE DE FR GB IT NL 2940 Mayfair Road Akron OH 4431 2(US) Inventor: Malani, Shrikant R. 460 Treeside Drive AKron OH 4431 3(US) 0 Representative: Kraus, Walter, Dr. et al Patentanwalte Kraus, Weisert & Partner Thomas-Wimmer-Ring 15 D-8000 Miinchen 22(DE) 0 Oligomeric oxolanyl alkanes as randomizers for copolymerization. © A process is disclosed herein for preparing ran- domized copolymers of conjugated dienes and vinyl aromatic hydrocarbons by utilizing oligomeric ox- olanyl alkanes in amounts which effectively promote the randomization of the copolymers so produced. CO in e>i in Ol w Xerox Copy Centre 0 215 256 OL1GOMERIC OXOLANYL ALKANES AS RANDOMIZERS FOR COPOLYMERIZATION pound and an oligomeric oxolanyl alkane. At least BACKGROUND OF THE INVENTION one of the two monomers is selected from the group consisting of conjugated dienes having from The use of oligomeric oxolanyl alkanes and four to 12 carbon atoms per molecule. The other hydrocarbyl alkali metal compounds such as butyl- 5 monomer is selected from the group consisting of lithium as co-initiators in the copolymerizations of vinyl aromatic hydrocarbons having from eight to dienes such as butadiene with styrene is well 20 carbon atoms per molecule. known as disclosed in U.S. 4,429,090 and U.S. The oligomeric oxolanyl alkane randomizing 4,429,091, to James E. Hall. agents of the present invention are extremely sta- Styrene and 1,3-butadiene form block w ble at high polymerization temperatures such as copolymers when polymerized anionically in non- temperatures exceeding 90 °C thus allowing poly- polar solvents. Modifiers for anionic polymerization merizations to be run in an economical low cost are known which will randomize 1,3- manner while eliminating detrimental side reac- butadiene/styrene copolymerizations however tions. many of these modifiers are not suitable for use at 75 The oiigomeric oxolanyl alkane is present in higher temperatures. the polymerization reaction in a quantity sufficient This invention relates to the use of oligomeric to promote formation of random copolymers, it oxolanyl alkanes as randomizers for being considered that in the absence of the butadiene/styrene copolymerizations. oiigomeric oxolanyl alkane or other randomizers, 20 substantially no random copolymers are produced but that block polymers are formed. The oligomeric SUMMARY OF THE INVENTION oxolanyl alkane randomizers reduce or eliminate both terminal and branch blocking of the conju- A process is disclosed herein for preparing gated diene and vinyl aromatic hydrocarbons used randomized copolymers of conjugated dienes and 25 to prepare the copolymers of the present invention. vinyl aromatic hydrocarbons by utilizing oligomeric In the preferred embodiment of this invention oxolanyl alkanes in amounts which effectively pro- the two monomers, the conjugated dienes and the mote the randomization of the copolymers so pro- vinyl aromatic hydrocarbons, are present in a mon- duced. omer ratio of from about 90 to 10 to about 40 to 60. 30 The oligomeric oxolanyl alkanes hereinafter al- ternatively referred to as oxoianyl alkanes which DESCRIPTION OF THE INVENTION are used as randomizers in the present invention are represented by the structural formulas I and II: According to this invention there is provided a process for preparing randomized copolymers 35 which comprises contacting at least two different monomeric materials with an organolithium com- 40 45 so 0 215 256 (I) O | » " «r S, ^ k«, -»/ (II) wherein R, and R2 independently are hydrogen or The cyclic oxolanyl oligomer randomizer pre- an alkyl group and the total number of carbon 20 cursors are formed only by the reaction of a furan atoms in -CR,Rj-is between one and nine inclusive; compound which is unsubstituted in the 2,5-posi- y is an integer of I to 5 inclusive, y1 is an integer of tion with one or more aldehydes, or one or more 3 to 5 inclusive, Rr, R3, R, and R5 independently ketones, or a mixture thereof. are -H or -CnH2n+1 wherein n = l to 6. Suitable oligomeric randomizers for use in the While the randomizers of structural formula I 25 catalyst system include but are not limited to: bis- linear are oligomers and the modifiers represented (2-oxolanyl) methane; 2,2-bis(2-oxolanyl) propane; by structural formula II are cyclic oligomers, l,l-bis(2-oxolanyl) ethane; 2,2-bis(2-oxolanyl) bu- hereinafter the term oxolanyl randomizers is con- tane; 2,2-bis(5-methyl-2-oxolanyl) propane; 2,2-bis- templated to encompass the randomizers of both (3,4,5-trimethyl-2-oxolanyl) propane. These ran- structural formulas. 30 domizer compounds represent a few of the dimer The oxolanyl randomizers are prepared by compounds represented by structural formula I and methods known to those skilled in the art. Typically other linear and cyclic oligomer randomizers are the modifiers are prepared by reacting furan, which apparent from their structural formulas. is unsubstituted in either or both of the 2-or 5- The preferred oxolanyl randomizers for use in positions, with either an aldehyde or a ketone, such 35 the present invention are the dimeric 2,2-bis(2- as acetone, in the presence of an acid such as oxolanyl) propane and the trimeric 2,5-bis(2- hydrochloric acid. Careful control of the reaction oxolanyl-2-propyl) oxolane. parameters allows for the production of a product The oligomeric oxolanyl alkane can be intro- containing up to 95 percent of dimers, trimers, and duced into the polymerization in any manner. It can tetramers. Once the linear oligomers or cyclic 40 be introduced together with hydrocarbyllithium in- structures are formed these reaction products are itiator into the polymerization reaction or the hydrogenated in the presence of suitable hydroge- oligomeric oxolanyl alkane can be introduced into nation catalysts such as nickel based catalysts. the polymerization reaction mixture into which the Any suitable hydrogenation process known in the hydrocarbyllithium has been introduced as an in- art be may employed to produce the randomizer 45 itiator. In either embodiment, the oligomeric ox- compounds of structural formulas I or II. olanyl alkanes can be employed individually or as While unsubstituted furans are the preferred mixtures with other oxolanyl alkanes. reactant, 2-alkyl-furans containing up to six carbon The oligomeric oxolanyl alkanes employed in atoms in the alkyl group can be employed in the accordance with the method of this invention in of production the oxolanyl oligomers of structural 50 polymerization reactions which are conducted un- formula I. When 2-alkyl-furans are employed in the der any of those reaction conditions conventionally production of randomizers furfuryl dimers are the employed in solution polymerization with hydrocar- main reaction product. The 2-alkyl-furan also may byllithium initiators which involve the copolymeriza- end cap any oligomers formed if furan is used as a tion of two monomeric materials, i.e., conjugated coreactant. 55 diolefins, including butadiene and isoprene and vi- nyl aromatic hydrocarbons such as styrene and related hydrocarbons. If the polymerization mix- tures into which an oligomeric oxolanyl alkane has 0 215 256 been introduced are to be treated with polymer dimethyl-l-vinylnaphthalene; 2,4,6-trivinyltoluene; coupling agents or other reagents which depend and 2,4,6-triisopropenyl-toluene. Again reference is upon the presence of terminal polymer-lithium made to U.S. Patent No. 3,377,404 for disclosures groups, the coupling agent or other reagent should of additional vinyl-substituted aromatic compounds be added as soon as practicable, for example, 5 which are incorporated herein by reference. within 15 minutes, after the desired monomer con- In the process of the present invention the version has been attained. randomization of the conjugated dienes and vinyl- Regardless of the method of their employment, substituted aromatic monomers is effective in mon- that is, whether they are reacted with the hydrocar- omer ratios ranging from 10-50% vinyl-substituted byllithium and introduced in the form of the reac- to aromatic hydrocarbons to 90-50% conjugated tion product or whether they are introduced, as diene. The randomization process is especially ef- such, into the reaction mixture, the oligomer ox- fective when the monomer ratio is from 30-40% olanyl alkanes will be employed in quantities suffi- vinyl-substituted aromatic hydrocarbon to 70-60% cient to provide from about 0.004 to about 2.0, conjugated diene. preferably 0.006 to I.5, parts per I00 parts of mon- 75 Any organolithium catalyst which are known in omers for polymers of 1,000 to 500,000 M n. the art as being useful in the polymerization of If introduced into the reaction mixture as such, vinyl aromatic hydrocarbons and conjugated dienes the oligomeric oxolanyl alkane is conveniently intro- can be employed in the present invention . Suitable duced in a hydrocarbon, e.g., hexane, solution. catalysts which initiate polymerization of the mon- As previously discussed at least one of the two 20 omer system include organolithium catalysts which monomers which is to be randomized in the have the formula R(Li)X" wherein R represents a present invention is selected from the group con- hydrocarbyl radical of I to 20, preferably 2-8, car- sisting of one or more conjugated dienes having bon atoms per R group, and x" is an integer of 1-4. from four to 12 carbon atoms per molecule.