CA2168499A1

CA2168499A1 - Alkyllithium compounds containing cyclic amines and their use in polymerization

Info

Publication number: CA2168499A1
Application number: CA002168499A
Authority: CA
Inventors: David F. Lawson; Thomas A. Antkowiak; James E. Hall; Mark L. Stayer, Jr.; John R. Schreffler
Original assignee: Bridgestone Corp
Current assignee: Bridgestone Corp
Priority date: 1995-02-01
Filing date: 1996-01-31
Publication date: 1996-08-02
Also published as: DE69606892T2; ES2143674T3; DE69606892D1; JPH08245638A; JP4157170B2; US5792820A; US5496940A; EP0725069B1; EP0725069A1

Abstract

An organolithium compound according to the present invention containing a cyclic amino group, has the general formula:

wherein R1 is a divalent alkylene, an oxy- or amino-alkylene, or substituted alkylene having from 6 to about 20 carbon atoms; R2 is a linear-, branched-, or cyclo-alkylene having from about 2 to about 20 carbon atoms; and the lithium, Li, is bonded directly to a carbon atom of R2. A method of preparing an organolithium compound containing a cyclic amino group, comprising reacting a cyclic amino organo halide having the general formula

Description

216~499 9408053 (P-112) ALKYLLITHIUM COMPOUNDS CONTAINING CYCLIC AMINES
AND THEIR USE IN POLYMERIZATION

TECHNICAL FIELD
The subject invention relates to polymers made by anionic initiation with alkyllithium compounds containing cyclic amines, such as polymerizations of dienes and diene/comonomer mixtures resulting in diene polymer and copolymer elastomers. Polymers prepared with the compounds of the present invention exhibit improved characteristics such as for example, improved hysteresis loss characteristics, and reproducible, relatively narrow range molecular weight distributions.

BACKGROUND ART
When conducting polymerizations on a co..,.,.elcial basis, it is 15 important to utilize process conditions and components which will allow the molecular weight of the end products to be narrowly and reproducibly defined.
The characteristics of a given polymer and its usefulness, are dependent, among other things, upon its molecular weight. Hence, it is desirable to be able to predict with some certainty the molecular weight of the end product of the 20 polymerization. When the molecular weight is not narrowly definable, or is not reproducible on a systematic basis, the process is at a commercial disadvantage.Further, it is desirable to produce elastomeric compounds exhibiting improved characteristics such as reduced hysteresis loss characteristics. Such elastomers, when compounded to form articles such as tires, power belts and the 25 like, will show an increase in rebound, a decrease in rolling resistance and less heat build-up when mechanical stresses are applied.
A major source of hysteretic power loss has been established to be due to the section of the polymer chain from the last cross link of the vulcanizate to the end of the polymer chain. This free end cannot be involved in an efficient 30 elastic recovery process, and as a result, any energy transmitted to this section of the cured sample is lost as heat. It is known in the art that this type of mechanism can be reduced by preparing higher molecular weight polymers which will have fewer end groups. However, this procedure is not useful because -2 9408053 (P-112) processability of the rubber with compounding ingredients and during shaping operations decreases rapidly with increasing molecular weight of the rubber.
The present invention provides polymers made by anionic initiation with novel alkyl lithium compounds containing cyclic amines. Use of the compounds of the present invention allows the incorporation of a functionality from the initiator to be incorporated at least at the head of the polymer chain.The initiators used in the invention not only provide for improved polymerizations, but also result in polymers having a relatively predictable, controllable and reproducible molecular weight range distribution. Because of the incorporated functionality, the polymers and products of the invention exhibit improved (that is, reduced) hysteresis loss characteristics.
Certain aminoalkyllithium compounds are known in the art. For example, U.S. Pat. No. 4,935,471 discloses dialkylamino oligoalkenyl lithiums including piperidinyl and pyrrolidinyl oligoalkenyl lithiums. It has been found that when compounded with conventional vulcanizable rubber components, some of these materials do not interact effectively with carbon black. Others possessan odor which makes their commercial use undesirable. The present invention provides polymers derived from aminoalkyllithium compounds with improved interaction with carbon black and which do not have the objectionable odor associated with the piperidinyl and pyrrolidinyl compounds.

DISCLOSURE OF THE INVENTION
It is therefore, an object of the present invention to provide anionic polymerization initiators.
It is a further object of the present invention to provide a method of preparing such anionic polymerization initiators.
It is still a further object of ~he invention to provide an initiator which will reproducibly result in a polymer within a narrow, predictable molecular weight range.
It is an additional object of the invention to provide an initiator which will allow for the incorporation of a functional group at least at the head of the resulting polymer.

216~99 3 9408053 (P-1 12) It is another object of the present invention to provide methods of using such polymerization initiators to form improved elastomers.
It is yet another object of the present invention to use such initiators to provide elastomers having a plurality of polymer molecules wherein 5 substantially each molecule has a functional group from the initiator.
It is also an object of certain embodiments of the present invention to provide anionic initiators which will produce diene polymers and copolymers having reduced hysteresis characteristics.
At least one or more of these objects together with the advantages 10 thereof over the existing art, which shall become apparent from the specification which follows, are accomplished by the invention as hereinafter described and claimed.
In general, the present invention relates to alkyl lithium compounds containing cyclic amines, comprising the general formula:

R~N--R2--Li wherein R1 is a divalent alkylene, an oxy- or amino-alkylene, or substituted alkylene having from 6 to about 20 carbon atoms; R2 is a linear-, branched-, or cyclo-alkylene having from about 2 to about 20 carbon atoms; and, Li is a lithium atom bonded directly to a carbon atom of R2. The compound may be useful, for 25 example, as an anionic polymerization initiator. The resulting polymers and compounds formed therefrom exhibit improvements such as reduced hysteresis loss characteristics.
A method of preparing a cyclic amine compound according to the invention comprises reacting a cyclic amino halide having the general formula R,~ ~N--R2--X

2168~99 4 9408053 (P-1 12) wherein R1 and R2 are as defined above and X is chlorine or bromine, with a lithium reactant selected from the group consisting of elemental lithium metal and RLi wherein R is selected from the group consisting of alkyls, cycloalkyls, alkenyls, aryls and aralkyls having from 1 to about 20 carbon atoms and short chain length low molecular weight polymers from diolefin and vinyl aryl monomers having up to about 25 units.
Another embodiment of a cyclic amine compound according to the invention has the general formula R4R2Li, where R2 is as defined above, and R4 is a cyclic amino radical having the general formula R,~ ~N--where Rs is selected from the group consisting of a divalent alkylene, an oxy- or amino-alkylene, and a substituted alkylene having from 4 to about 20 carbon atoms, a substituted nitrogen having the general formula R6N where R6 is selected from the group consisting of an alkyl having from 1 to about 12 carbon atoms; a cycloalkyl having from about 5 to about 20 carbon atoms; an aryl havingfrom about 6 to about 20 carbon atoms; and, an aralkyl having from 7 to about 20 carbon atoms; and mixtures thereof, with the limitation that R4 has from 2 toabout 4 nitrogen atoms and a total of from 6 to about 24 atoms in the ring structure thereof.
Use of the anionic initiators of the invention provides a functionalized polymer which comprises a polymer molecule having the general formula AYLi where A is a cyclic amine-containing radical having the general formula ~
R~N--R2 2168~9 - - 5 9408053 (P-112) wherein R1 and R2 are as discussed hereinabove; Y is a divalent polymer radical;and the lithium atom, Li, is bonded directly to a carbon atom of Y.
A functionalized polymer made from the anionic initiator of the present invention also comprises a polymer molecule having the general formula 5 AYLi where A is a cyclic amine-containing radical having the general formula R,~ N--R2 wherein A, R2, Rs and Y are as discussed hereinabove.
The initiators of the present invention can also be used in a method of preparing a polymer which comprises preparing a solution of 1 or more 15 anionically polymerizable monomers in a solvent; and, polymerizing under effective conditions, the monomers in the presence of a polymerization initiatoraccording to the present invention and having the general formula ~
R~ ~N--R2--Li wherein R1, R2 and Li are as discussed hereinabove.
A method for preparing a polymer using the anionic initiators of the present invention comprises preparing a solution of 1 or more anionically polymerizable monomers in a solvent; and polymerizing under affective conditions, the monomers in the presence of a polymerization initiator accordingto the present invention and having the general formula R~ N--R2--Li 21~8~99 6 9408053 (P-112) wl.elein R2, Rs and Li are as discussed hereinabove.

PRtttl~htu EMBODIMENT FOR CARRYING OUT THE INVENTION
As will become apparent from the description which follows, the 5 present invention provides novel aminoalkyllithium compounds useful for example, as anionic poly..,e. i~alion initiators for the preparation of diene polymer and copolymer elastomers. It has been discovered herein that certain vulcanizable elastomeric compounds and articles thereof based upon such polymers formed using such initiators, exhibit useful properties, such as for 10 example, reproducible relatively narrow molecular weight ranges. Fu.ll.er.nore, such polymers also contain a functionality from the initiator, which functionality is useful for example, in reducing hysteresis loss characteristics in the resulting polymers.
The preferred aminoalkyllithium compound according to the invention 15 contains a cyclic amine. The preferred initiator is therefore, an amine having the general formula ALi, wherein the component "A" represents the cyclic amine functionality to be incorporated at the initiation site or the head of the resulting polymer when the inventive amine compound is employed as an initiator. "A"
is preferably a cyclic amine radical having the general formula (I) R, /--R2 wherein R1 is a divalent alkylene, oxy- or amino-alkylene, or substituted alkylene moiety having from 6 to about 20 carbon atoms, more preferably from 6 to 12 carbon atoms; and, R2 is a linear-, branched-, or cyclo-alkylene moiety having from about 2 to about 20 carbon atoms, and more preferably, from 3 to 12 30 carbon atoms. The lithium atom, Li, is bonded directly to a carbon atom of A. Examples of R1 include hexamethylene, heptamethylene, dodecamethylene and hexadecamethylene moieties and the like. Examples of preferred R2 groups have from about 3 to about 6 carbon atoms and include 2168~99 7 9408053 (P-112) propyl and hexyl moieties and the like. Hence, examples of preferred cyclic amino compounds according to the invention include hexamethyleneiminopropyllithium, CN CH2CH2CH2Li;

hexamethyleneiminohexyllithium, CN CH2CH2CH2CH2CH2CH2Li ;

and, dodecamethyleneiminopropyllithium N CH2CH2CH2Li \ - ~

The carbon and nitrogen atoms in the cyclic amine ring structure of "A" can also be substituted, such that the aminoalkyllithium of this embodiment has the general formula (R3)n R~ N R2 Li 21684~9 8 9408053 (P-1 1 2) wherein R3 is a tertiary amino or an alkyl group having from about 1 to about 12carbon atoms; an aryl having from about 6 to about 20 carbon atoms; an aralkyl having from about 7 to about 20 carbon atoms; an alkenyl having from about 2 to about 12 carbon atoms; a cycloalkyl having from about 5 to about 20 carbon atoms; a cycloalkenyl having from about 5 to about 20 carbon atoms; a bicycloalkyl having from about 6 to about 20 carbon atoms; or, a bicycloalkenyl having from about 6 to about 20 carbon atoms; where n is an integer of from about 1 to about 10. The O-, S- or N-containing analogs of R3, which analogs aresubstantially non-reactive with the alkylithium of the cyclic amino compound, are also within the scope of the invention. By "analog" it is meant a compound in which one or more O, S and/or N atoms may replace one or more carbon atoms.
The lithium atom, Li, is bonded direclly to a carbon atom in R2.
Further, R2 can be a branched- or cyclo-alkylene in addition to being a linear-alkylene as discussed hereinabove. Examples of branched-alkylene-containing (lithio)alkyl portions include 2,2-dimethylpropane-1 ,3-diyl; 2-methylpropane-1 ,3-diyl; 2-methylbutane-1,4 diyl; and 2-2-dimethyloctane-1 ,8-diyl.
Examples of cyclo-alkylene (lithio)alkyl portions include cyclohexane-1,4-diyl;
cyclohexane-1,3-diyl; cyclododecane-1,7-diyl; cyclooctane-1,3-diyl; and, cyclohexadecane-1 ,5-diyl.
According to another embodiment of the present invention, the cycloalkyl amine portion of "A" has at least seven ring atoms therein, includingabout 2 to about 4 amine nitrogens. Such a cyclic amine compound has the general formula R4R2Li where R2 is as defined above, and R4 is a cyclic amino radical having the general formula R5 J_ where Rs is selected from the group consisting of a divalent alkylene, an oxy- or amino-alkylene, and a substituted alkylene having from 4 to about 20 carbon atoms, a substituted nitrogen having the general formula R6N where R6 is 9 9408053 (P-112) selected from the group consisting of an alkyl having from 1 to about 12 carbon atoms; a cycloalkyl having from about 5 to about 20 carbon atoms; an aryl havingfrom about 6 to about 20 carbon atoms; and, an aralkyl having from 7 to about 20 carbon atoms; and mixtures thereof, with the limitation that R4 has from 2 toabout 4 nitrogen atoms and a total of from 6 to about 24 atoms in the ring structure thereof. The cyclic amine initiator according to the invention can thus have the following general formula, where Rs, R2 and Li are as described hereinabove:

R~ N--R2--Li.

The atoms in Rs can be substituted in the same manner as described above, that is, with "A" being substituted with (R3)n.
Therefore, in addition to formula (I) hereinabove, "A" can also be a cyclic amine radical having the general formula (Il) R4R2- where R4 and R2 are as described hereinabove.
Therefore, according to the present invention, in the alkyl lithium compounds containing cyclic amines, the size of the ring in the cyclic amine portion is greater than or equal to 7 atoms when there is only one nitrogen atomin the ring, or greater than or equal to 6 atoms when there are 2 or more nitrogen atoms in the ring.
Examples of amine compounds having the structure R4R2Li as above are mono-N alkyl or N-aryl derivatives or piperazines; mono N-alkyl derivatives of homopiperazine (1,4-diazacycloheptanes); mono-N-alkyl derivatives of 1,4- or 1,5-diazacyclooctanes, and ring C-substituted 1,4- or 1,5-diazacyclooctanes and the like. Ring C-substituted N-alkylpiperazines are also within the scope of theinvention. Substituted triaza ring systems are also included within R4-.
The initiator used in the present invention can be formed by any number of techniques. One preferred method of preparing a cyclic amine compound according to the invention is to react a cyclic aminoalkyl halide with 10 9408053 (P-112) a lithio reactant selected from elemental lithium metal, an organolithium compound, and mixtures thereof. The aminoalkyl halide has the general formula AX where A is as defined by formulas I or ll hereinabove, and X is a halogen selected from bromine, chlorine, iodine or the like, preferably bromine or chlorine, and wherein X is bonded directly to a carbon atom of R2 in either formula I or ll. The preparation of cyclic aminoalkyl halides is known to the art.
When reacted with elemental lithium metal in a suitable solvent such as hexane, cyclohexane, benzene or the like, the resulting reduction reaction produces a lithiated cyclic amine compound ALi where "A" is as defined hereinabove and the lithium atom, Li, is directly bonded to a carbon atom of A.
The lithiated cyclic amine compound ALi can be complexed with one or more ligand molecules (such as THF) which help stabilize it but do not otherwise affect the reaction.
In the alternative, the amino reactant AX can also be reacted with an organolithium reactant having the general formula RLi, again in a suitable solvent such as those described hereinabove. RLi can be for example, selected from the group consisting of alkyls, cycloalkyls, alkenyls, aryls and aralkyls having from 1 to about 20 carbon atoms ànd short chain length low molecular weight polymers from diolefin and vinyl aryl monomers having up to about 25 units. Typical alkyls include n-butyl, s-butyl, t-butyl, methyl, ethyl, isopropyl and the like. The cycloalkyls include cyclohexyl, menthyl and the like. The alkenyls include allyl, vinyl and the like. The aryl and aralkyl groups include phenyl, benzyl, oligo(styryl) and the like. Exemplary short chain length polymers include the oligo(butadienyls), oligo(isoprenyls), oligo(styryls) and the like. Alkyllithiumreactants such as t-butyl lithium are preferred.
The two components are allowed to react for up to about twenty-four hours at low to ambient temperature (-70 to 30 C), or elevated temperatures up to about 100C, preferably at less than 50C, and more preferably at less than 38C.
If one atom equivalent of lithium in the organolithium reactant is used per atom equivalent of AX, a byproduct of the reaction will be an organo halide (that is, RX) which may be undesirable for the intended use of the inventive compound. It may therefore, be preferable to employ two or more atom 11 9408053 (P-112) equivalents of lithium from the organolithium reactant per atom equivalent of AX.
It is believed that a reaction with the excess of lithium will result in a lithium halide and other low molecular weight hydrocarbon by-products, which may be more acceptable for the intended use of the inventive initiator material.
As stated above, the compound ALi or R4R2Li thus formed may be employed as an initiator to prepare any anionically-polymerized elastomer, e.g.,polybutadiene, polyisoprene and the like, and copolymers thereof with monovinyl aromatics such as styrene, alpha methyl styrene and the like, or trienes such as",~.ce..e. Thus, the elastomers include diene homopolymers and copolymers 10 thereof with monovinyl aromatic polymers. Suitable monomers include conjugated dienes having from about 4 to about 12 carbon atoms and monovinyl aromatic monomers having 8 to 18 carbon atoms and trienes. Examples of conjugated diene monomers and the like useful in the present invention include 1 ,3-butadiene, isoprene, 1 ,3-pentadiene, 2,3-dimethyl-1 ,3-butadiene and 1,3-15 hexadiene, and aromatic vinyl monomers include styrene, alpha-methylstyrene, p-methylstyrene, vinyltoluene and vinylnaphthalene. The conjugated diene monomer and aromatic vinyl monomer are normally used at the weight ratios of 95-50:5-50, preferably 95-65:5-35.
Polymerization is conducted in polar or non-polar solvent, such as 20 tetrahydrofuran (THF), a hydrocarbon solvent, such as the various cyclic and acyclic hexanes, heptanes, octanes, pentanes, their alkylated derivatives, and mixtures thereof. In order to promote randomization in copolymerization and to control vinyl content, a polar coordinator may be added to the polymerization ingredients. Amounts range between 0 and 90 or more equivalents per equivalent 25 of lithium. The amount depends on the amount of vinyl desired, the level of styrene employed and the ten)pelature of the polymerization, as well as the nature of the specific polar coo!dinator (modifier) employed. Suitable polymerization modifiers include for example, ethers or amines to provide the d~i-red microstructure and randomization of the comonomer units. The molecular 30 weight of the polymer ("base polymer") that is produced in this invention is optimally such that a proton-quenched sample will exhibit a gum Mooney (ML/4/100) of from about 1 to about 150. However, useful lower molecular weight compounds can also be made using these initiators. These might typically 2168~99 12 9408053 (P-112) be considered fluids, having molecular weights ranging from several hundreds to tens of thousands of mass units.
Other compounds useful as polar coordinators are organic and include tetrahydrofuran (THF), linear and cyclic oligomeric oxolanyl alkanes such as 2,2-5 bis(2'-tetrahydrofuryl) propane, di-piperidyl ethane, dipiperidyl methane, hexamethylphosphoramide, N-N'~imethylpiperazine, diazabicyclooctane, dimethyl ether, diethyl ether, tributylamine and the like. The linear and cyclicoligomeric oxolanyl alkane modifiers are described in U.S. Pat. No. 4,429,091, owned by the Assignee of record, the subject matter of which relating to such 10 modifiers is incorporated herein by reference. Compounds useful as polar coordinators include those having an oxygen or nitrogen hetero-atom and a non-bonded pair of electrons. Other examples include dialkyl ethers of mono and oligo alkylene glycols; "crown" ethers; tertiary amines such as tetramethylethylene diamine (TMEDA); linear THF oligomers; and the like.
A batch polymerization is begun by charging a blend of monomer(s) and normal alkane solvent to a suitable reaction vessel, followed by the addition of the polar coordinator (if employed) and the initiator compound previously described. The reactants are heated to a temperature of from about 20 to about 200C, and the polymerization is allowed to proceed for from about 0.1 to about 20 24 hours. A functional amine group is derived from the initiator compound andattaches at the initiation site. Thus, substantially every resulting polymer molecule can be represented by the following general formula AYLi where A is as described above, and Y is a divalent polymer radical which is derived from any of the foregoing diene homopolymers, monovinyl aromatic polymers, diene/monovinyl aromatic random copolymers and block copolymers.
The monomer addition at the lithium end causes the molecular weight of the 30 polymer to increase as the polymerization continues.
To terminate the polymerization, and thus further control polymer molecular weight, a terminating agent, coupling agent or linking agent may be employed, all of these agents being collectively referred to herein as "terminating 216~4q9 1 3 9408053 (P-1 1 2) reagents". Certain of these reagents may provide the resulting polymer with a multifunctionality. That is, the polymers initiated according to the present invention, may carry at least one amine functional group A as discussed hereinabove, and may also carry a second functional group selected and derived 5 from the group consisting of terminating reagents, coupling agents and linking agents.
Useful terminating, reagents include active hydrogen compounds such aswateroralcohol; carbondioxide; N,N,N',N'-tetradialkyldiamino-benzophenone (such as tetramethyldiaminobenzophenone or the like); N,N-dialkylamino-10 benzaldehyde (such as dimethylaminobenzaldehyde or the like); 1,3-dialkyl-2-imidazolidinones (such as 1,3-dimethyl-2-imidazolidinone or the like); 1-alkyl substituted pyrrolidinones; 1-aryl substituted pyrrolidinones; dialkyl- and dicycloalkyl-carbodiimides having from about 5 to about 20 carbon atoms;
(R7)azxb;

R8--NL N--R8;

Rlo ~CH=O;

J~
L~N--R8;

14 2 1 6 ~ 4 ~ 9 9408053 (P-112) Rlo ~N=CH--Rg;

and, Rlo ~CH=N--Rlo;

where Z is tin or silicon. It is preferred that Z is tin.
R7 is an alkyl having from about 1 to about 20 carbon atoms; a cycloalkyl having from about 3 to about 20 carbon atoms; an aryl having from about 6 to about 20 carbon atoms; or, an aralkyl having from about 7 to about 20 carbon atoms. For example, R7 may include methyl, ethyl, n-butyl, neophyl, phenyl, cyclohexyl or the like.
X is chlorine or bromine, "a" is from 0 to 3, and "b" is from about 1 to 4; where a + b = 4.
Each R8 is the same or different and is an alkyl, cycloalkyl or aryl, having from about 1 to about 12 carbon atoms. For example, R8 may include methyl, ethyl, nonyl, t-butyl, phenyl or the like.
Rg is an alkyl, phenyl, alkylphenyl or dialkylaminophenyl, having from about 1 to about 20 carbon atoms. For example, Rg may include t butyl, 2-methyl~-pentene-2-yl, phenyl, p-tolyl, p-butylphenyl, p-dodecylphenyl, p~iethyl-aminophenyl, p-(pyrrolidino)phenyl, and the like.
Each R10 is the same or different, and is an alkyl or cycloalkyl having from about 1 to about 12 carbon atoms. Two of the R10 groups may together form a cyclic group. For example, R10 may include methyl, ethyl, octyl, tetramethylene, pentamethylene, cyclohexyl or the like.

21~8499 15 9408053 (P-112) R11 may include alkyl, phenyl, alkylphenyl or dialkylaminophenyl, having from about 1 to about 20 carbon atoms. For example, R11 may include methyl, butyl, phenyl, p-butylphenyl, p-nonylphenyl, p-dimethylaminophenyl, p-diethylaminophenyl, p~piperidino)phenyl, or the like.
Other examples of useful terminating reagents include tin tetrachloride, (R1 1)3SnCI, (R1 1)2SnC12, R1 1SnCI3, carbodiimides, N-methylpyrrolidine, cyclicamides, cyclic ureas, isocyanates, Schiff bases, 4,4'-bis(diethylamino) benzophenone, and the like, where R11 is an alkyl, cycloalkyl or aralkyl having from 1 to about 12 carbon atoms, and other reactive hysteresis-reducing terminating compounds which may contain other heteroatoms such as oxygen, nitrogen, sulfur, phosphorus, tin, noninterfering halogen, etc. Suitable terminating reagents also include the isomeric vinylpyridines, dialkylaminobenzaldehydes, (bis)dialkylsminobenzophenones (Michler's ketones), dimethylimidazolidinone, etc. The living polymer may also be coupled with any of the various known coupling reagents, such as silicon tetrachloride, etc., to prepare symmetrically "dicapped" polymers. By the end-linking of polymers initiated with lithium hydrocarbon amides, through reaction with for example, RaSnYb, where R, Y, a and b are as described hereinabove; SnC14; or C4HgSnCI3;
to obtain products with substantially greater than 10 percent end-linking through tin, especially desirable elastomeric compositions with low hysteresis properties are prepared.
The terminating reagent is added to the reaction vessel, and the vessel is agitated for about 1 to about 1000 minutes. As a result, an elastomer is produced having an even greater affinity for compounding materials such as carbon black, and hence, even further reduced hysteresis. Additional examples of terminating reagents include those found in U.S. Patent No. 4,616,069 which is herein incorporated by reference for the disclosure of terminating agents.
The polymer may be separated from the solvent by conventional techniques. These include steam or alcohol coagulation, thermal desolventization, or any other suitable method. Additionally, solvent may be removed from the resulting polymer by drum drying, extruder drying, vacuum drying or the like.

16 21 ~ 8 ~ 9 9 9408053 (P-112) The elastomers made from the anionic initiators of the present invention comprise a plurality of polymer molecules, having a functional group at both the head, and preferably also, at the tail of the resulting polymer.
Compounding such elastomers results in products exhibiting reduced hysteresis, 5which means a product having increased rebound, decreased rolling resistance and has less heat build-up when subjected to mechanical stress.
The polymers made from the anionic initiators of the present invention can be used alone or in combination with other elastomers to prepare a product such as a tire treadstock, sidewall stock or other tire component stock compound.
10Such stocks are useful for forming tire components such as treads, subtreads, black sidewalls, body ply skims, bead fillers and the like. At least one such component is produced from a vulcanizable elastomeric or rubber composition.
For example, they can be blended with any conventionally employed treadstock rubber which includes natural rubber, synthetic rubber and blends thereof. Such 15rubbers are well known to those skilled in the art and include synthetic polyisoprene rubber, styrene/butadiene rubber (SBR), polybutadiene, butyl rubber, poly(chloroprene), ethylene/propylene rubber, ethylene/propylene/diene rubber (EPDM), acrylonitrile/butadiene rubber (NBR), silicone rubber, the fluoroelastomers, ethylene acrylic rubber, ethylene vinyl acetate copolymer (EVA), 20epichlorohydrin rubbers, chlorinated polyethylene rubbers, chlorosulfonated polyethylene rubbers, hydrogenated nitrile rubber, tetrafluoroethylene/propylenerubber and the like. When the polymers of the present invention are blended with conventional rubbers, the amounts can vary widely such as between 10 and 99 percent by weight.
25The polymers can be compounded with carbon black in amounts ranging from about 20 to about 100 parts by weight, per 100 parts of rubber (phr), with about 40 to about 70 phr being preferred. The carbon blacks may include any of the co~-"-,only available, co.l"~ercially-produced carbon blacks but those having a surface area (EMSA) of at least 20 m2/g and more preferably at 30least 35 m2/g up to 200 m2/g or higher are preferred. Surface area values usedin this application are those determined by ASTM test D-1765 using the cetyltrimethyl-ammonium bromide (CTAB) technique. Among the useful carbon blacks are furnace black, channel blacks and lamp blacks. More specifically, 17 9408053 (P-112) examples of the carbon blacks include super abrasion furnace (SAF) blacks, high abrasion furnace (HAF) blacks, fast extrusion furnace (FEF) blacks, fine furnace(FF) blacks, intermediate super abrasion furnace (ISAF) blacks, semi-reinforcingfurnace (SRF) blacks, medium processing channel blacks, hard processing channel 5 blacks and conducting channel blacks. Other carbon blacks which may be utilized include acetylene blacks. Mixtures of two or more of the above blacks can be used in preparing the carbon black products of the invention. Typical values for surface areas of usable carbon blacks are summarized in the followingTABLE 1.
TABLE I
CARBON Bl~CKS

ASTM Surface Area 15Designation (m2/g) (D-1765-82a) (D-3765) The carbon blacks utilized in the preparation of the rubber compounds used may be in pelletized form or an unpelletized flocculent mass. Preferably, for more uniform mixing, unpelletized carbon black is preferred. The reinforced rubber compounds can be cured in a conventional manner with known vulcanizing agents at about 0.5 to about 4 phr. For example, sulfur or peroxide-based curing systems may be employed. For a general disclosure of suitable vulcanizing agents one can refer to Kirk-Othmer, Encyclopedia of Chemical Technolo~y, 3rd ed., Wiley Interscience, N.Y. 1982, Vol. 20, pp. 365-468, particularly "Vulcanization Agents and Auxiliary Materials" pp. 390-402.
Vulcanizing agents may be used alone or in combination.

1 8 9408053 tP-1 1 2) Vulcanizable elastomeric compositions made from the above elastomers can be prepared by compounding or mixing the polymers thereof with carbon black and other conventional rubber additives such as fillers, plasticizers, antioxidants, curing agents and the like, using standard rubber mixing equipmentand procedures and conventional amounts of such additives.

GENERAL EXPERIMENTAL
I n order to demonstrate the preparation and properties of the initiators according to the present invention and their use in anionic polymerization, a number of such cyclic amino alkyllithium compounds were prepared. These compounds were then used as initiators to form a number of elastomers.
The aminoalkyllithium reagents of the invention may be prepared under a variety of conditions, using various hydrocarbon solvents as discussed hereinabove. The reagents may be used in polymerizations using such polar or nonpolar solvents as may be necessary for improved solubility of the aminoalkyllithium reagent, provided that the solvents are compatible with anionic polymerizations and the solvent recovery and polymer drying procedures.
In one preferred emlodiment of the invention that provides for the production of reduced hysteresis polymers in substantially hydrocarbon solvents,such as hexane or cyclohexane, the initiator is hexamethyleneiminopropyllithium,which may be generated by at least two exemplary routes as is also discussed above: 1) by the reaction of a mixture of one equivalent of for example, 1~N-hexamethyleneimino)-3-chloropropane with about two atom equivalents of lithium metal; or 2) a "one-pot" gen~rdtion of for example, hexamethyleneiminopropyllithium, wherein 1-bromo-3-chloropropane is treated with N-lithiohexamethyleneimine, and the product 1~N-hexamethyleneimino)-3-chloropropane is then treated in situ with two equivalents of t-butyllithium.
The reactions are preferably performed in hexanes, cyclohexane, benzene, or mixtures thereof.
The amino alkyllithium reagents of the invention may be formed in a solvent or solvent mixture, and then transferred to another solvent or solvent mixture for use in a polymerization reaction.

216.~4g9 19 9408053 (P-112) The initiators of this invention may optionally be treated with from about one to S00 equivalents of a monomer such as butadiene or isoprene, before the main (co)polymerization charge is made, although this is not required.
Polymers according to the invention can be prepared with a relatively narrow molecular weight range distribution, with a substantial fraction of living C-Li chain ends adaptable to further functionalization or coupling, being obtained.
The initiator formation, polymerization, and coupling and/or termination may be performed in one reaction vessel, or second or third reactor vessels, or transfer lines from the original reactor can be used, by introducing the preformed initiator to the monomer mixture, or vice-versa. Polymerization and post-treatment conditions should be used that avoid the introduction of air and/or protic or other reactive contaminants, such as moisture, etc., and prolonged heating or storage at excessive tem~.eldtures should be avoided unless the live ends are stabilized. Low to high temperatures (from about -70C to about 200C) are useful for the polymerizations and the terminations. Polymerization and post-treatment temperatures of from about 15C to 125C are preferred. The polymerization time may vary from a few minutes to days, depending on the temperature, solvent and presence of any donor solvent, the monomer structures, and the molecular weight desired.
Any suitable method for isolation of the terminated rubber or fluid may be used, for example: quenching with water, steam, an acid or an alcohol (these may be introduced during the desolventization step), and desolventization by drum drying, coagu'~tion in alcohol, water or steam, extruder drying, vacuum drying, spray drying or any combination thereof. Desolventization by drum-drying, coagulation in alcohol, steam or hot water desolventization, extruder drying, vacuum drying, spray drying or combinations thereof are preferred. An antioxidant and/or antiozonant compound is usually added to the polymer or polymer cement at or before this stage. In most of the ~xp-r;...~..tal examples of this invention, alcohol coagulation followed by drum-drying or 30 vacuum drying were used.
Upon drying, the elastomers are compounded in a carbon black-filled test stock (see Low-Oil Test Recipe, TABLE ll), and the physical properties determined in comparison to those of related base polymers without the 216~4g9 9408053 (P-l 1 2) modifications. In practice, a wide variety of compounding recipes may be used to give favorable results with th;s invention, although hysteresis properties may vary from formulation to formulation, depending on the type and amount of carbon black and oil used, and so on. Certain other fillers, such as silica or 5 hydrated silica may also be useful. Furthermore, the polymers made with the initiators of this invention may be combined in proportions of 20 to 100 percentby weight with 80 to 0 percent by weight of other polymers to give elastomeric compositions with reduced hysteresis loss characteristics. The low molecular weight products made from the initiators of this invention may be used at low 10 levels to influence the properties of mixtures with other fluids and/or particulates.

T~BLE ll LOW-OIL TEST FORMULATION FOR EVALUATION OF EilalL.~E~.J

Parts per Hundred Ingredient Mix Order Parts of Rubber Polymer 1 100 Naphthenic oil 2 10 Carbon black, N-351 3 55 ZnO 4 3 Antioxidant 5 Wax blend 6 2 Total Masterbatch: 171 Stearic acid 2 Sulfur 1.5 Accelerator Total Final: 175.5 Masterbatch: 145-155C, 60 RPM
(drop after 5 min, ~? 155-175C) Final: 77-95C, 40 RPM

The following preparations exemplify the invention.

2168~99 21 9408053 (P-112) EXAMPLE 1. A "one-pot" preparation of hexamethyleneiminopropyllithium The (bis)tetrahydrofuran N-lithio salt of hexamethyleneimine was prepared in hexane. Equimolar amounts of this salt and 1~hloro-3-bromopropane (5 mmol + 5 mmol) were mixed in hexanes at about -25C, and the mixture was allowed to warm to about 0C while swirling over 45 minutes. The mixture was cooled to -25C again, and 10 mmol of t-butyllithium in pentane was added. The resulting mixture was allowed to warm slowly to room temperature and agitated gently overnight before use. It was estimated that 0.28 M active Li was present and 0.24 M, with 0.34 M total base, was found. The mixture was used to initiate the polymerization of butadiene and styrene as des~.ibed in the following examples.

EXAMPLE 2. Polymerizations of styrene/butadiene mixtures using hexamethyleneiminopropyllithium Polymerizations were run using the initiator solution prepared according to Example 1 hereinabove. The following table (TABLE lll) lists the ingredients and conditions used in the polymerizations. A 0.24 M solution of theabove initiator was added to a dried, sealed, nitrogen-purged bottle, through a Viton rubber cap liner, to a 75 percent/25 percent by weight blend of butadiene and styrene in hexanes, at an estimated level of 0.75 milliequivalent ("mequiv.") active C-Li/100 grams monomer, and an additional amount of N,N,N',N'-tetramethylethylenediamine ("TMEDA") was added at the TMEDA/Li ratio indicated in TABLE lll.

POLYMERIZ~TION OF STYRENE/BUTADIENE

SAMPLE A SAMPLE B
Amount (g) of Monomer 90.6 95.3 ml of 2.0 M TMEDA (TMEDA/Li) 0.42 (1:1) 0.43 (1:1) Initiator, mequiv 0.82 0.86 Initiator, ml 2.91 3.06 Pzn temperature, C 80 80 Pzn time~ minutes 40 40 21fi8~99 22 9408053 (P-112) The mixtures were agitated at 80C for 0.5 to 2.5 hours ("hrn), proceeding to approximately 94-98 percent conversion to polymer. In practice, there is considerable leeway in the reaction times and temperatures, much the same as there is leeway in the reaction vessels, type of agitation, etc., used. The treated 5 cements then were quenched by injection with 1.5 ml of i-PrOH (isopropyl alcohol), treated with an antioxidant (3 ml of a mixture containing 1.6 wt%
dibutyl paracresol (DBPC) in hexane), coagulated in i-PrOH, air-dried at room temperature, then drum-dried. Suitable characterization tests were performed.
Analyses of the product polymer are given in TABLE IV (Run A).
EXAMPLE 3. Polymerizations of styrene/butadiene mixtures using hexamethyleneiminopropyllithium and end-linking with SnC14 The procedure of Example 2 was followed, except that after 40 minutes of polymerization at 80C, the polymerization mixture was treated with 0.8 15 equiv. of SnC14 per equivalent ("equiv.") of Li charged. The mixture was agitated at 50C for 30 minutes. The product was isolated and dried in the same manner as above. It showed about 40 percent coupling in the 80C polymerization.
Analyses of this polymer are also given in TABLE IV (Run B).

TABLE IV
ANALYSIS OF COMPOUNDED POLYMERS

RUN: SAMPLE A SAMrLE B
Polymer recovered % 94 95 tan ~S, C (DSC, onset) -43.9 -44.2 ML/4/100, raw 62.4 96.2 GPC (THF):
Mn 202762 248129 MW/Mn 1.25 1.94 2168~9 23 9408053 (P-112) EXAMPLE 4. Compounded evaluations of polymers made from hexamethyleneiminopropyllithium The product polymers (from Runs A and B of Table IV) were compounded and tested as indicated in the test recipe shown in TABLE ll, and 5 cured 20 min ~? 165C. Compared to the control polymer, the results of the compounded evaluations are summarized in TABLE V. A control polymer, (a tin-coupled styrene/butadiene rubber ("SBRn) initiated with t-butyllithium) was alsocompounded and tested. Compared to the control polymer, the product of Run A exhibited improved hysteresis loss characteristics and enhanced interaction 10 with carbon black, compared to unmodified elastomers of the same molecular weight embodied in the control polymer. In these experiments, the polymers were of higher molecular weight than anticipated, since the initiator was part of a mixture.

TABLE IV
POLYMER ANALYSIS

Polymer ~ oly~ Polymer Sample ja Sample A Sample BC
Feature Sn-Coudled Control HMI-Pr-Lie HMI-Pr-Li (BuLi initiator) 80C 80C/SnC14 ML/4-Raw 74 62.4 96.2 ML/4-Cpd 67.3 107.1 116.1 #1 Dispersion Index % 95.0 89.9 76.7 Dynastat 1 Hz, tan ~, 50C 0.0934 0.0895 0.0926 aControl SBR
30 blnventive polymer prepared according to Example 2 Clnventive polymer prepared according to Example 3 dbutyllithium eHexamethyleneimine propyllithium It is clear from the foregoing examples and specification disclosure, that the present invention provides novel cyclic aminoalkyllithium compounds 21 6Q.A99 24 9408053 (P-112) useful for example, as anionic polymerization initiators for the preparation of diene monomers. Reproducible polymerization of such polymers within a relatively narrow molecular weight range is achieved, and the resulting polymersalso exhibit good preservation of live C-Li ends which permits further polymer 5 functionalization through the use of terminating reagents.
It is to be understood that the invention is not limited to the specific initiator reactants, monomers, terminators, polar coordinators or solvents disclosed herein, except as otherwise stated in the specification. Similarly, the examples have been provided merely to demonstrate practice of the subject 10 invention and do not constitute limitations of the invention. Those skilled in the art may readily select other monomers and process conditions, according to the disclosure made hereinabove.
Thus, it is believed that any of the variables disclosed herein can readily be determined and controlled without departing from the scope of the 15 invention herein disclosed and described. Moreover, the scope of the invention shall include all modifications and variations that fall within the scope of theattached claims.

Claims

1. An organolithium compound containing a cyclic amino group, comprising the general formula:

wherein R1 is a divalent alkylene, an oxy- or amino-alkylene, or substituted alkylene having from 6 to about 20 carbon atoms; R2 is a linear-, branched-, or cyclo-alkylene having from about 2 to about 20 carbon atoms; and the lithium, Li, is bonded directly to a carbon atom of R2.

2. An organolithium compound as in claim 1, having a formula selected from the group consisting of ;

;

and, .

3. An organolithium compound as in claim 1, wherein when R1 is a substituted-alkylene, the cyclic amine has the general formula wherein R3 is a tertiary amino, an alkyl having from about 1 to about 12 carbon atoms; an alkenyl having from about 2 to about 20 carbon atoms;
a cycloalkyl having from about 5 to about 20 carbon atoms; a cycloalkenyl having from about 5 to about 20 carbon atoms; a bicycloalkyl having from about 6 to about 20 carbon atoms; a bicycloalkenyl having from about 6 to about 20 carbon atoms; an aryl having from about 6 to about 20 carbon atoms; or an aralkyl group having from about 7 to about 20 carbon atoms;
and n is an integer of from about 1 to about 10.

4. An organolithium compound as in claim 3, wherein the cyclic amine contains an O-, S- or N-containing analogue of R3, which analogue is substantially non-reactive with the alkylithium of the cyclic amino compound.

5. An anionic polymerization initiator for the polymerization of diene polymer and copolymer elastomers having reduced hysteresis loss characteristics, comprising:
a cyclic amine compound having the general formula:

wherein R1 is a divalent alkylene, an oxy- or amino-alkylene, or substituted alkylene having from 6 to about 20 carbon atoms; and, R2 is a linear-, branched-, or cyclo-alkylene having from about 2 to about 20 carbon atoms;
and the lithium, Li, is bonded directly to a carbon atom of R2.

6. A method of preparing an organolithium compound containing a cyclic amino group, comprising reacting a cyclic amino organo halide having the general formula wherein R1 is a divalent alkylene, an oxy- or amino-alkylene, or substituted alkylene having from 6 to about 20 carbon atoms; R2 is a linear; branched-, or cyclo-alkylene having from about 2 to about 20 carbon atoms; and X is bromine or chlorine bonded directly to a carbon atom of R2;
with a lithium reactant selected from the group consisting of elemental lithium metal and RLi wherein R is selected from the group consisting of alkyls, cycloalkyls, alkenyls, aryls and aralkyls having from 1 to about 20 carbon atoms and short chain length low molecular weight polymers from diolefin and vinyl aryl monomers having up to about 25 units.

7. A method as in claim 6, wherein said cyclic amino halide is reacted with at least two atom equivalents of said lithium reactant.

8. A method of preparing an anionic polymerization initiator for use in the polymerization of monomer resulting in diene polymer and copolymer elastomers having reduced hysteresis loss characteristics, comprising:
reacting a cyclic amino organo halide having the general formula wherein R1 is a divalent alkylene, an oxy- or amino-alkylene, or substituted alkylene having from 6 to about 20 carbon atoms; R2 is a linear; branched-, or cyclo-alkylene having from about 2 to about 20 carbon atoms; and X is bromine or chlorine bonded directly to a carbon atom of R2;
with a lithium reactant selected from the group consisting of elemental lithium metal and RLi wherein R is selected from the group consisting of alkyls, cycloalkyls, alkenyls, aryls and aralkyls having from 1 to about 20 carbon atoms and short chain length low molecular weight polymers from diolefin and vinyl aryl monomers having up to about 25 units.

9. A cyclic amine compound having the general formula R4R2Li where R2 is a linear-, branched-, or cyclo-alkylene having from about 2 to about 20 carbon atoms; the lithium atom, Li, is bonded directly to a carbon atom of R2; and, R4 is a cyclic amino radical having the general formula where R5 is selected from the group consisting of a divalent alkylene, an oxy- or amino-alkylene, a substituted alkylene having from 4 to about 20 carbon atoms, and a substituted nitrogen having the general formula R6N
where R6 is selected from the group consisting of an alkyl having from 1 to about 12 carbon atoms; a cycloalkyl having from about 5 to about 20 carbon atoms; an aryl having from about 6 to about 20 carbon atoms; and, an aralkyl having from 7 to about 20 carbon atoms; and mixtures thereof, with the limitation that R4 has from 2 to about 4 nitrogen atoms and a total of from 6 to about 24 atoms in the ring structure thereof.