(19) TZZ_ZZZ_T (11) EP 1 709 090 B1 (12) EUROPEAN PATENT SPECIFICATION (45) Date of publication and mention (51) Int Cl.: of the grant of the patent: C08F 36/04 (2006.01) C08F 297/04 (2006.01) 23.03.2016 Bulletin 2016/12 C08F 4/48 (2006.01) (21) Application number: 04784675.3 (86) International application number: PCT/US2004/030890 (22) Date of filing: 22.09.2004 (87) International publication number: WO 2005/030816 (07.04.2005 Gazette 2005/14) (54) ANIONIC POLYMERIZATION DIINITIATOR AND PROCESS FOR PREPARING SAME VERFAHREN ZUR HERSTELLUNG VON DIFUNKTIONELLEN ANIONISCHEN POLYMERISATIONSINITIATOREN BI-INITIATEUR DE POLYMERISATION ANIONIQUE ET SON PROCEDE DE PREPARATION (84) Designated Contracting States: • HADDIX, Grant, W. AT BE BG CH CY CZ DE DK EE ES FI FR GB GR Katy, TX 77450 (US) HU IE IT LI LU MC NL PL PT RO SE SI SK TR • TUTUNJIAN, Pierre, N. Houston, TX 77042 (US) (30) Priority: 24.09.2003 US 505670 P • COCCHIARA, Joy, P. Houston, TX 77077 (US) (43) Date of publication of application: • ATWOOD, Harvey, E. 11.10.2006 Bulletin 2006/41 Kingwood, TX 77345 (US) • STEVENS, Craig, A. (73) Proprietor: Kraton Polymers U.S. LLC Katy, TX 77494 (US) Houston, Texas 77084 (US) (74) Representative: EP&C (72) Inventors: P.O. Box 3241 • WILLIS, Carl, L. 2280 GE Rijswijk (NL) Houston, TX 77084 (US) • GOODWIN, Daniel, E. (56) References cited: Katy, TX 77450 (US) US-A- 5 750 055 US-A1- 2002 198 343 Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 1 709 090 B1 Printed by Jouve, 75001 PARIS (FR) EP 1 709 090 B1 Description BACKGROUND OF THE INVENTION 5 1. Field of the Invention [0001] The present invention relates to anionic polymerization diinitiators and a process for preparing same. The present invention particularly relates to such initiators that are useful for the production of vinyl aromatic block copolymers . 10 2. Background of the Art [0002] The use of anionic initiators to prepare block copolymers is well known. In a synthetic method, an initiator compound is used to start the polymerization of one monomer. The reaction is allowed to proceed until all of the monomer is consumed resulting in a living homopolymer. To this living homopolymer is added a second monomer that is chemically 15 different from the first. The living end of the first polymer serves as the site for continued polymerization, thereby incor- porating the second monomer as a distinct block into the linear polymer. The block polymer so grown is living until terminated. [0003] Termination converts the living end of the block copolymer into a non-propagating species, thereby rendering the polymer unreactive toward additional monomers. A polymer so terminated is commonly referred to as a diblock 20 copolymer. Initiators are commonly monofunctional. That is they have only one site that can initiate polymerization so that, in effect, the initiator is at one end of the polymer chain that builds in a single direction, that direction being away from the initiator. Exemplary monoinitiators include, for example, sec-butyl lithium. [0004] Preparing a polymer using a diinitiator can offer advantages over preparing a similar polymer using a monoin- itiator. By using a diinitiator, the polymer can be grown in both directions at the same time, thereby reducing the polym- 25 erization time. But the use of such diinitiators can also be troublesome. For example, U. S. Pat. No. 3,734, 973, to Farrar, describes the production of anionic polymerization diinitiators by reacting diisopropenylbenzene compounds with organo monolithium compounds and then carrying out anionic copolymerization of styrene and butadiene using the diinitiators. [0005] Unfortunately, the chemistry involved in the reaction of the diisopropenylbenzene and the lithium alkyl is prone to suffer from a competing side reaction that forms oligomers of diisopropenylbenzene. The oligomers consume diiso- 30 propenylbenzene and this limits the yield of the lithium initiator. In addition and perhaps more importantly, the oligomers have more than two lithium centers per molecule. If all of the lithium centers in the oligomers initiate polymerization, a nonlinear, star, or radial polymer will result. The branching in such star and radial polymers leads to an increase in the melt viscosity of the polymer. This is undesirable if the desired polymer is a linear, difunctional anionic polymer. [0006] One possible solution to the problem of oligomers having multiple initiation sites is disclosed in U. S. Patent 35 No. 6,217, 798 B1 to Willis, et al. Therein it is disclosed that combining the components in a particular order, carrying out the reaction within a narrow temperature range, and carrying out the reaction in the presence of the appropriate amount of diethyl ether provides the advantage of minimizing the oligomerization of the diisopropenylbenzene. [0007] US2002198343 concerns an improvement in a method of anionically polymerizing monomers by contacting them with an anionic polymerization initiator which is an organo-substituted alkali metal compound in the presence of 40 low amounts of an accelerator/promoter and/or a highly active microstructure modifier. The improvement comprises adding from 0.1 to 1.0 equivalents of a metal alkyl compound per equivalent of alkali metal initiator wherein alkyl groups of the metal alkyl compound are chosen so that they will not exchange with the organo substituents of the alkali metal compound. The preferred initiator for use herein is the sec-butyl lithium adduct of diisopropenylbenzene and the preferred metal alkyl is triethyl aluminum. 45 [0008] In US5750055 a process is disclosed for the preparation of an efficient industrial organolithium diinitiator, comprising the reaction of two equivalents of a mono-organolithium initiator with one equivalent of 1,3-diisopropenyl- benzene at a temperature in the range of from -20 to 60 °C., in an apolar hydrocarbon solvent, and in the presence of a monofunctional tertiary amine in a molar ratio relative to mono-organolithium initiator from 0.5 to 2, followed by addition to the reaction mixture of a small amount of conjugated diene monomer, at a temperature in the range of from 0 to 30 50 °C., to form a solution of an alpha, omega -dilithio poly(conjugated diene), having an apparent molecular weight in the range of from 1000 to 3000. [0009] While the diinitiators prepared according to U. S. Patent No. 6,217, 798 B1 are clearly superior to the prior art diinitiators, they are not trouble free and require both time and resources to produce. It would be desirable in the art of preparing diinitiators for use in anionic polymerization to develop diinitiators that are more stable, less nucleophilic and 55 less basic, and to prepare diinitiators that have primary anionic polymerizations sites of substantially equal reactivity. 2 EP 1 709 090 B1 SUMMARY OF THE INVENTION [0010] In one aspect, the present invention is an anionic polymerization diinitiator comprising a diinitiator prepared by admixing a diisopropenylbenzene compound selected from the group 1,2-diisopropenylbenzene; 1,3-diisopropenylben- 5 zene; 1,4-diisopropenylbenzene; 3,4,5,6-tetramethyl-1,2-diisopropenylbenzene; 2,4,5,6-tetraethyl-1,3-diisopropenyl- benzene; 2,3,5,6-tetra-n-hexyl-1,4-diisopropenylbenzene; 3,4-dicyclohexyl-1, 2-diisopropenylbenzene; 5-(3-methyl-cy- clopentyl)-1,3-diisopropenylbenzene; 3-cyclopentyl-methyl-6-n-propyl-1,4-diisopropenylbenzene; 4-(2-cyclo-butyl-1- ethyl)-1,2-diisopropenylbenzene; 3-(2-n-propylcyclopropyl)-1,4-diisopropenylbenzene; 2-methyl-5-n-hexyl-1,3-diiso- propenylbenzene; 4-methyl-1,2-diisopropenylbenzene; 5-ethyl-1,3-diisopropenylbenzene; 3-methyl-1,4-diisopropenyl- 10 benzene; and mixtures thereof, with diethyl ether, ethylene, an organolithium compound, and a solvent at a temperature whithin the range of 0°C to 150° under reaction conditions sufficient to prepare a diinitiator having primary lithium alkyl reactive sites. [0011] In another aspect, the present invention is an anionic polymerization diinitiator having the general formula : 15 20 25 wherein R1 has the general formula : 30 35 wherein R3 is an aliphatic, cycloaliphatic, aromatic or alkyl-substituted aromatic hydrocarbon radical having from 1 to about 20 carbon atoms, each n is independently an integer having a value from 1 to 10, and R 2 is hydrogen or an alkyl or cycloalkyl radical containing from 1 to 6 carbon atoms. [0012] In still another aspect, the present invention is a process for preparing a an anionic polymerization diinitiator 40 comprising admixing a diisopropenylbenzene compound selected from the group 1,2-diisopropenylbenzene; 1,3-diiso- propenylbenzene; 1,4-diisopropenylbenzene; 3,4,5,6-tetramethyl-1,2-diisopropenylbenzene; 2,4,5,6-tetraethyl-1,3-di- isopropenylbenzene; 2,3,5,6-tetra-n-hexyl-1,4-diisopropenylbenzene; 3,4-dicyclohexyl-1,2-diisopropenylbenzene; 5-(3- methyl-cyclopentyl)-1,3-diiso-propenylbenzene; 3-cyclopentyl-methyl-6-n-propyl-1,4-diisopropenylbenzene; 4-(2-cyclo- butyl-1-ethyl)-1,2-di-isopropenylbenzene; 3-(2-n-propylcyclopropyl)-1,4-diisopropenylbenzene; 2-methyl-5-n-hexyl-1,3- 45 diisopropenylbenzene; 4-methyl-1,2-diisopropenylbenzene; 5-ethyl-1,3-diisopropenylbenzene; 3-methyl-1,4-diisopro- penylbenzene; and mixtures thereof, with diethyl ether, ethylene, an organolithium compound, and a solvent at a tem- perature within the range of 0°C to 150°C under reaction conditions sufficient to prepare a diinitiator having primary lithium alkyl reactive sites. [0013] Another aspect of the present invention is a block copolymer prepared using a diinitiator prepared by admixing 50 a diisopropenylbenzene compound with diethyl ether, ethylene, an organo lithium compound and a solvent at a temper- ature within the range of 0°C to 150°C under reaction conditions sufficient to prepare a diinitiator having primary lithium alkyl reactive sites.