Anionic Polymerization Process And Polymer Production Method Patent Application (2025)

U.S. patent application number 17/271431 was filed with the patent office on 2021-10-28 for anionic polymerization process and polymer production method.This patent application is currently assigned to KURARAY CO., LTD.. The applicant listed for this patent is KURARAY CO., LTD.. Invention is credited to Moe KAWAHARA, Tomohiro ONO.

ANIONIC POLYMERIZATION PROCESS AND POLYMER PRODUCTION METHOD

Abstract

A process for anionically polymerizing a (meth)acrylic acid inthe presence of a tertiary organoaluminum compound (A), anorganolithium compound (B) and at least one kind of a Lewis base(C) in a polymerization system. The tertiary organoaluminumcompound (A) includes a tertiary organoaluminum compound (A1)having a chemical structure in which at least two of three unsharedelectrons of an aluminum atom are bonded to an aromatic ring via anoxygen atom, and the tertiary organoaluminum compound (A) has amolar ratio (A2)/(A1) in the range of 0% or above and 0.8% or belowbetween a tertiary organoaluminum compound (A2) having a chemicalstructure in which at most one of three unshared electrons of analuminum atom is bonded to an aromatic ring via an oxygen atom, andthe tertiary organoaluminum compound (A1).

Foreign Application Data

Claims

1. A process, comprising: anionically polymerizing a (meth)acrylicacid ester in the presence of a tertiary organoaluminum compound(A), an organolithium compound and at least one kind of a Lewisbase in a polymerization system, wherein the tertiaryorganoaluminum compound (A) comprises a tertiary organoaluminumcompound (A1) having a chemical structure in which at least two ofthree unshared electrons of an aluminum atom are bonded to anaromatic ring via an oxygen atom, and the tertiary organoaluminumcompound (A) has a molar ratio (A2)/(A1) of 0% or above and 0.8% orbelow between a tertiary organoaluminum compound (A2) having achemical structure in which at most one of three unshared electronsof an aluminum atom is bonded to an aromatic ring via an oxygenatom, and the tertiary organoaluminum compound (A1).

2. The process according to claim 1, wherein the molar ratio(A2)/(A1) of the tertiary organoaluminum compound (A2) to thetertiary organoaluminum compound (A1) is of more than 0% and notmore than 0.8%.

3. The process according to claim 1, wherein the Lewis basecomprises a tertiary polyamine compound.

4. The process according to claim 3, wherein the tertiary polyaminecompound comprises at least one selected from the group consistingof N,N,N',N'-tetramethylethylenediamine,N,N,N',N'',N''-pentamethyldiethylenetriamine, and1,1,4,7,10,10-hexamethyltriethylenetetramine.

5. The process according to claim 1, wherein the Lewis basecomprises an ether compound.

6. The process according to claim 5, wherein the ether compoundcomprises an acyclic ether compound having one or more ether bondsin a molecule thereof or a cyclic ether compound having two or moreether bonds in the molecule.

7. The process according to claim 1, wherein the tertiaryorganoaluminum compound isisobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum.

8. A method for producing a polymer, the method comprising:polymerizing a (meth)acrylic acid ester by the process of claim1.

9. A method for producing a block copolymer, the method comprising:polymerizing two or more kinds of (meth)acrylic acid esters by theprocess of claim 1.

Description

TECHNICAL FIELD

[0001] The present invention relates to a process for anionicallypolymerizing an anionically polymerizable monomer and to a methodfor producing a polymer by the polymerization process.

BACKGROUND ART

[0002] Numerous studies have been made on processes for anionicallypolymerizing polar monomers such as methacrylic acid esters andacrylic acid esters. These polar monomers have sites such ascarbonyl groups that are susceptible to nucleophilic attack. Thus,unfortunately, the anionic polymerization is accompanied by sidereactions of monomers and by intramolecular cyclization reactions(so-called backbiting) at growth ends. Due to this fact, it isrelatively difficult to obtain high living properties. To attainhigh living properties, the conventional anionic polymerizationprocess often entails the use of polymerization initiators whosesynthesis and purification are complicated. Further, it is oftenthe case that the temperature during anionic polymerization shouldbe as extremely low as about -60.degree. C. The consequent increasein cooling cost is a factor that makes the process disadvantageousto industrial production.

[0003] The present applicant has proposed an approach capable ofsolving the above problem (see, for example, Patent Literature 1).Specifically, an anionically polymerizable monomer is polymerizedusing an anionic polymerization initiator in a polymerizationsystem containing a combination of a specific organoaluminumcompound and a specific Lewis base.

[0004] As compared with the conventional anionic polymerizationprocesses, the above anionic polymerization process can achievehigh polymerization initiation efficiency, high polymerization rateand high living properties. Further, the polymerization process issuperior in that it can produce polymers having a narrow molecularweight distribution and block copolymers having high blockingefficiency in an industrially advantageous manner.

CITATION LIST

Patent Literature

[0005] Patent Literature 1: JP-A-2001-131216

SUMMARY OF INVENTION

Technical Problem

[0006] In the production of a (meth)acrylic acid ester polymer bythe process described in the above patent literature, however, agel probably stemming from the organoaluminum compound is generatedand sometimes adversely affects properties (for example,transparency) of the (meth)acrylic acid ester polymer obtained. Thegelation is sometimes significant and lowers the polymerizationinitiation efficiency or living properties. Further, a blockcopolymer that is produced sometimes has nonuniform molecularweights.

[0007] An object of the present invention is to provide a morereliable process for anionically polymerizing a (meth)acrylic acidester that attains high polymerization initiation efficiency andhigh living properties without impairing the inherentcharacteristics of (meth)acrylic polymers such as transparency.Another object of the present invention is to provide a morereliable method for producing a (meth)acrylic acid ester blockcopolymer having a highly uniform molecular weight.

Solution to Problem

[0008] After extensive studies directed to achieving the aboveobjects, the present inventors have found that a (meth)acrylic acidester may be anionically polymerized without sufferingdeterioration in inherent characteristics of (meth)acrylic polymerswhile still ensuring that high living properties will be obtainedmore reliably during the anionic polymerization and that a blockcopolymer will be produced more reliably with high uniformity inmolecular weight by performing the anionic polymerization in thepresence of a tertiary organoaluminum compound comprising aspecific proportion of a tertiary organoaluminum compound with aspecific chemical structure, an organolithium compound, and atleast one kind of a Lewis base.

[0009] According to the present invention, the objects describedhereinabove are achieved by providing items including the following[1] to [9].

[0010] [1] An anionic polymerization process for anionicallypolymerizing a (meth)acrylic acid ester in the presence of atertiary organoaluminum compound (A), an organolithium compound (B)and at least one kind of a Lewis base (C) in a polymerizationsystem, wherein the tertiary organoaluminum compound (A) comprisesa tertiary organoaluminum compound (A1) having a chemical structurein which at least two of three unshared electrons of an aluminumatom are bonded to an aromatic ring via an oxygen atom, and thetertiary organoaluminum compound (A) has a molar ratio (A2)/(A1) inthe range of 0% or above and 0.8% or below between a tertiaryorganoaluminum compound (A2) having a chemical structure in whichat most one of three unshared electrons of an aluminum atom isbonded to an aromatic ring via an oxygen atom, and the tertiaryorganoaluminum compound (A1).

[0011] [2] The anionic polymerization process described in [1],wherein the molar ratio (A2)/(A1) of the tertiary organoaluminumcompound (A2) to the tertiary organoaluminum compound (A1) is inthe range of more than 0% and not more than 0.8%.

[0012] [3] The anionic polymerization process described in [1] or[2], wherein the Lewis base (C) comprises a tertiary polyaminecompound (C1).

[0013] [4] The anionic polymerization process described in [3],wherein the tertiary polyamine compound (C1) comprises at least oneselected from N,N,N',N'-tetramethylethylenediamine,N,N,N',N'',N''-pentamethyldiethylenetriamine, and1,1,4,7,10,10-hexamethyltriethylenetetramine.

[0014] [5] The anionic polymerization process described in [1] or[2], wherein the Lewis base (C) comprises an ether compound(C2).

[0015] [6] The anionic polymerization process described in [5],wherein the ether compound (C2) comprises an acyclic ether compound(C2-1) having one or more ether bonds in the molecule or a cyclicether compound (C2-2) having two or more ether bonds in themolecule.

[0016] [7] The anionic polymerization process described in any of[1] to [6], wherein the tertiary organoaluminum compound (A1) isisobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum. [8] A methodfor producing a polymer comprising polymerizing a (meth)acrylicacid ester by the anionic polymerization process described in anyof [1] to [7].

[0017] [9] A method for producing a block copolymer comprisingpolymerizing two or more kinds of (meth)acrylic acid esters by theanionic polymerization process described in any of [1] to [7].

Advantageous Effects of Invention

[0018] According to the present invention, the occurrence of gelscan be suppressed to allow a (meth)acrylic acid ester to beanionically polymerized more reliably without sufferingdeterioration in inherent characteristics of (meth)acrylic polymerssuch as transparency. Further, anionic polymerization can beperformed with high living properties to give a polymer with anarrow molecular weight distribution and to produce more reliably a(meth)acrylic acid ester block polymer having a highly uniformmolecular weight.

DESCRIPTION OF EMBODIMENTS

[0019] The present invention will be described in detailhereinbelow. In the present specification, "(meth)acrylic acidester" is a general term for "methacrylic acid ester" and "acrylicacid ester", "(meth)acrylic" is a general term for "methacrylic"and "acrylic", and "(meth)acryloyl" is a general term for"methacryloyl" and "acryloyl".

[0020] In the present invention, a polymer is produced bypolymerizing a (meth)acrylic acid ester by an anionicpolymerization process. The (meth)acrylic acid esters that areanionically polymerized in the present invention are notparticularly limited as long as having anionicpolymerizability.

[0021] Examples of the methacrylic acid esters includemonofunctional methacrylic acid esters such as methyl methacrylate,ethyl methacrylate, propyl methacrylate, isopropyl methacrylate,allyl methacrylate, n-butyl methacrylate, t-butyl methacrylate,cyclohexyl methacrylate, benzyl methacrylate, 2-ethylhexylmethacrylate, lauryl methacrylate, glycidyl methacrylate,trimethoxysilylpropyl methacrylate, methoxyethyl methacrylate,N,N-dimethylaminoethyl methacrylate and N,N-diethylaminoethylmethacrylate.

[0022] Examples of the acrylic acid esters include monofunctionalacrylic acid esters such as methyl acrylate, ethyl acrylate, propylacrylate, isopropyl acrylate, allyl acrylate, n-butyl acrylate,t-butyl acrylate, cyclohexyl acrylate, benzyl acrylate,2-ethylhexyl acrylate, lauryl acrylate, glycidyl acrylate,trimethoxysilylpropyl acrylate, methoxyethyl acrylate,N,N-dimethylaminoethyl acrylate and N,N-diethylaminoethylacrylate.

[0023] The (meth)acrylic acid esters may be used singly, or two ormore may be used in combination. The monofunctional (meth)acrylicacid esters described above may be used in combination with otheranionically polymerizable monomers.

[0024] Examples of such additional anionically polymerizablemonomers other than the monofunctional (meth)acrylic acid estersinclude polyfunctional (meth)acrylic acid esters having two or more(meth)acryloyl groups.

[0025] A block copolymer having a plurality of polymer blocks maybe produced by anionically polymerizing a combination of two ormore kinds of (meth)acrylic acid esters, typically, by sequentiallypolymerizing (meth)acrylic acid esters corresponding to respectivepolymer blocks.

[0026] To ensure that the polymerization reaction will take placesmoothly, it is preferable that the (meth)acrylic acid esters andother anionically polymerizable monomers which are used as requiredbe sufficiently dried beforehand by, for example, being treatedunder a stream of an inert gas such as nitrogen gas. The dryingtreatment may be performed with, for example, a dehydrating/dryingagent such as calcium hydride, molecular sieve or activealumina.

[0027] An organolithium compound (B) is used in the anionicpolymerization of (meth)acrylic acid esters. The organolithiumcompound (B) is preferably an organolithium compound which containsone or more carbon atoms serving as anionic centers in themolecule, and has lithium cations as counterion centers pairingwith the anionic centers, namely, as many as the anionic centers.Depending on the carbon atoms as the anionic centers, theorganolithium compounds (B) are classified into three types:organolithium compounds (B1) having a chemical structure in whichthe anionic center is a tertiary carbon atom, organolithiumcompounds (B2) having a chemical structure in which the anioniccenter is a secondary carbon atom, and organolithium compounds (B3)having a chemical structure in which the anionic center is aprimary carbon atom.

[0028] Examples of the organolithium compounds (B1) having achemical structure in which the anionic center is a tertiary carbonatom include t-alkyllithiums such as t-butyllithium and1,1-dimethylpropyllithium; 1,1-diarylalkyllithiums such as1,1-diphenylhexyllithium and 1,1-diphenyl-3-methylpentyllithium;and .alpha.,.alpha.-dialkyl-.alpha.-lithioacetic acid esters suchas ethyl .alpha.-lithioisobutyrate, butyl .alpha.-lithioisobutyrateand methyl .alpha.-lithioisobutyrate.

[0029] Examples of the organolithium compounds (B2) having achemical structure in which the anionic center is a secondarycarbon atom include sec-alkyllithiums such as isopropyllithium,1-methylpropyllithium (sec-butyllithium), 1-methylbutyllithium,2-ethylpropyllithium and 1-methylpentyllithium; cycloalkyllithiumssuch as cyclohexyllithium; diarylmethyllithiums such asdiphenylmethyllithium; and 1-alkyl-1-arylmethyllithiums such as.alpha.-methylbenzyllithium.

[0030] Examples of the organolithium compounds (B3) having achemical structure in which the anionic center is a primary carbonatom include n-alkyllithiums such as methyllithium, propyllithium,n-butyllithium and pentyllithium.

[0031] Among the organolithium compounds (B), the organolithiumcompounds (B2) having a chemical structure in which the anioniccenter is a secondary carbon atom are preferable because theyconcurrently satisfy high levels of convenience in industrial use(such as low risk of ignition, easy handling and easy production)and polymerization initiation performance. For the same reason,lithium salts of C3-C40 hydrocarbons having a chemical structure inwhich the anionic center is a secondary carbon atom are morepreferable, and 1-methylpropyllithium (sec-butyllithium) isparticularly preferable.

[0032] The organolithium compounds (B) may be used singly, or twoor more may be used in combination. The amount of the organolithiumcompound (B) may be determined appropriately in accordance withfactors such as the types of monomers used, and molecular weight.For reasons such as because a target polymer can be producedsmoothly, the amount is preferably 0.01 to 10 mol per 100 mol ofthe total of a (meth)acrylic acid ester and any other anionicallypolymerizable monomers.

[0033] In the anionic polymerization process of the presentinvention, it is important that a specific tertiary organoaluminumcompound (A) and at least one kind of a Lewis base (C) be presentin the polymerization system.

[0034] The tertiary organoaluminum compound (A) comprises atertiary organoaluminum compound (A1) having a chemical structurein which at least two of the three unshared electrons of analuminum atom are bonded to an aromatic ring via an oxygen atom.The tertiary organoaluminum compound (A1) present as the tertiaryorganoaluminum compound (A) offers enhanced living properties andallows a block copolymer to be produced with enhanced uniformity inmolecular weight.

[0035] Examples of the tertiary organoaluminum compounds (A1)include those tertiary organoaluminum compounds represented by thefollowing general formula (I):

AlR.sup.1R.sup.2R.sup.3 (I)

In the above formula (I), R.sup.1 is an optionally substitutedmonovalent saturated hydrocarbon group, an optionally substitutedmonovalent aromatic hydrocarbon group, an optionally substitutedalkoxy group, an optionally substituted aryloxy group, or anoptionally substituted N,N-disubstituted amino group, and R.sup.2and R.sup.3 are each independently an optionally substitutedaryloxy group, or R.sup.2 and R.sup.3 are bonded to each other toform an optionally substituted arylenedioxy group.

[0036] Examples of the optionally substituted monovalent saturatedhydrocarbon groups which may be represented by R.sup.1 includealkyl groups such as methyl group, ethyl group, n-propyl group,isopropyl group, n-butyl group, isobutyl group, sec-butyl group,t-butyl group, 2-methylbutyl group, 3-methylbutyl group, n-octylgroup and 2-ethylhexyl group; and cycloalkyl groups such ascyclohexyl group.

[0037] Examples of the optionally substituted monovalent aromatichydrocarbon groups which may be represented by R.sup.1 include arylgroups such as phenyl group; and aralkyl groups such as benzylgroup.

[0038] Examples of the optionally substituted alkoxy groups whichmay be represented by R.sup.1 include methoxy group, ethoxy group,isopropoxy group and t-butoxy group.

[0039] Examples of the optionally substituted N,N-disubstitutedamino groups which may be represented by R.sup.1 includedialkylamino groups such as dimethylamino group, diethylamino groupand diisopropylamino group; and bis(trimethylsilyl)amino group.

[0040] These monovalent saturated hydrocarbon groups, monovalentaromatic hydrocarbon groups, alkoxy groups and N,N-disubstitutedamino groups may be each substituted with one or more substituentssuch as, for example, alkoxy groups such as methoxy group, ethoxygroup, isopropoxy group and t-butoxy group; and halogen atoms suchas chlorine and bromine.

[0041] Examples of the optionally substituted aryloxy groups whichmay be represented by R.sup.1, R.sup.2 and R.sup.3 includeunsubstituted aryloxy groups such as phenoxy group, 2-methylphenoxygroup, 4-methylphenoxy group, 2,6-dimethylphenoxy group,2,4-di-t-butylphenoxy group, 2,6-di-t-butylphenoxy group,2,6-di-t-butyl-4-methylphenoxy group, 2,6-di-t-butyl-4-ethylphenoxygroup, 2,6-diphenylphenoxy group, 1-naphthoxy group, 2-naphthoxygroup, 9-phenanthryloxy group and 1-pyrenyloxy group; andsubstituted aryloxy groups such as 7-methoxy-2-naphthoxy group.

[0042] Examples of the optionally substituted arylenedioxy groupsrepresented by R.sup.2 and R.sup.3 bonded to each other includegroups resulting from the removal of hydrogen atoms from twophenolic hydroxyl groups in, for example, 2,2'-biphenol,2,2'-methylenebisphenol,2,2'-methylenebis(4-methyl-6-t-butylphenol),(R)-(+)-1,1'-bi-2-naphthol and (S)-(-)-1,1'-bi-2-naphthol.

[0043] The optionally substituted aryloxy groups and the optionallysubstituted arylenedioxy groups described above may be eachsubstituted with one or more substituents such as, for example,alkoxy groups such as methoxy group, ethoxy group, isopropoxy groupand t-butoxy group; and halogen atoms such as chlorine andbromine.

[0044] R.sup.1, R.sup.2 and R.sup.3 in the general formula (I) mayhave the same chemical structures as one another or may havedifferent chemical structures from one another as long as theirchemical structures satisfy the above definitions.

[0045] Examples of the tertiary organoaluminum compounds (A1)described above includeethylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum,ethylbis(2,6-di-t-butylphenoxy)aluminum,ethyl[2,2'-methylenebis(4-methyl-6-t-butylphenoxy)]aluminum,isobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum,isobutylbis(2,6-di-t-butylphenoxy)aluminum,isobutyl[2,2'-methylenebis(4-methyl-6-t-butylphenoxy)]aluminum,n-octylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum,n-octylbis(2,6-di-t-butylphenoxy)aluminum,n-octyl[2,2'-methylenebis(4-methyl-6-t-butylphenoxy)]aluminum,methoxybis(2,6-di-t-butyl-4-methylphenoxy)aluminum,methoxybis(2,6-di-t-butylphenoxy)aluminum,methoxy[2,2'-methylenebis(4-methyl-6-t-butylphenoxy)]aluminum,ethoxybis(2,6-di-t-butyl-4-methylphenoxy)aluminum,ethoxybis(2,6-di-t-butylphenoxy)aluminum,ethoxy[2,2'-methylenebis(4-methyl-6-t-butylphenoxy)]aluminum,isopropoxybis(2,6-di-t-butyl-4-methylphenoxy)aluminum,isopropoxybis(2,6-di-t-butylphenoxy)aluminum,isopropoxy[2,2'-methylenebis(4-methyl-6-t-butylphenoxy)]aluminum,t-butoxybis(2,6-di-t-butyl-4-methylphenoxy)aluminum,t-butoxybis(2,6-di-t-butylphenoxy)aluminum,t-butoxy[2,2'-methylenebis(4-methyl-6-t-butylphenoxy)]aluminum,tris(2,6-di-t-butyl-4-methylphenoxy)aluminum, andtris(2,6-diphenylphenoxy)aluminum.

[0046] Among these tertiary organoaluminum compounds (A1),isobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum,isobutylbis(2,6-di-t-butylphenoxy)aluminum andisobutyl[2,2'-methylenebis(4-methyl-6-t-butylphenoxy)]aluminum arepreferable for reasons such as high polymerization initiationefficiency, high living properties, high availability and easyhandling. Isobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum ismore preferable.

[0047] The tertiary organoaluminum compounds (A1) may be producedby any methods without limitation and may be prepared, for example,in accordance with a known technique. The tertiary organoaluminumcompounds (A1) may be used singly, or two or more may be used incombination.

[0048] The tertiary organoaluminum compound (A) may comprise asmall amount of a tertiary organoaluminum compound (A2) having achemical structure in which at most one of the three unsharedelectrons of an aluminum atom is bonded to an aromatic ring via anoxygen atom.

[0049] Examples of the tertiary organoaluminum compounds (A2)include those tertiary organoaluminum compounds represented by thefollowing general formula (II):

AlR.sup.4R.sup.5R.sup.6 (II)

[0050] In the formula (II), R.sup.4 is an optionally substitutedaryloxy group, and R.sup.5 and R.sup.6 are each independently anoptionally substituted monovalent saturated hydrocarbon group, anoptionally substituted monovalent aromatic hydrocarbon group, anoptionally substituted alkoxy group, or an optionally substitutedN,N-disubstituted amino group.

[0051] Specific examples of the optionally substituted aryloxygroups which may be represented by R.sup.4 are the same as those ofthe optionally substituted aryloxy groups which may be representedby R.sup.1. The optionally substituted aryloxy groups may be eachsubstituted with one or more substituents such as, for example,alkoxy groups such as methoxy group, ethoxy group, isopropoxy groupand t-butoxy group; and halogen atoms such as chlorine andbromine.

[0052] Specific examples of the optionally substituted monovalentsaturated hydrocarbon groups which may be represented by R.sup.5and R.sup.6 are the same as those of the optionally substitutedmonovalent saturated hydrocarbon groups which may be represented byR.sup.1. Specific examples of the optionally substituted monovalentaromatic hydrocarbon groups which may be represented by R.sup.5 andR.sup.6 are the same as those of the optionally substitutedmonovalent aromatic hydrocarbon groups which may be represented byR.sup.1. Specific examples of the optionally substituted alkoxygroups which may be represented by R.sup.5 and R.sup.6 are the sameas those of the optionally substituted alkoxy groups which may berepresented by R.sup.1. Specific examples of the N,N-disubstitutedamino groups which may be represented by R.sup.5 and R.sup.6 arethe same as those of the N,N-disubstituted amino groups which maybe represented by R.sup.1. These monovalent saturated hydrocarbongroups, monovalent aromatic hydrocarbon groups, alkoxy groups andN,N-disubstituted amino groups may be each substituted with one ormore substituents such as, for example, alkoxy groups such asmethoxy group, ethoxy group, isopropoxy group and t-butoxy group;and halogen atoms such as chlorine and bromine.

[0053] R.sup.5 and R.sup.6 in the general formula (II) may have thesame chemical structures as each other or may have differentchemical structures from each other as long as their chemicalstructures satisfy the above definitions.

[0054] Examples of the tertiary organoaluminum compounds (A2)described above includediethyl(2,6-di-t-butyl-4-methylphenoxy)aluminum,diethyl(2,6-di-t-butylphenoxy)aluminum,diisobutyl(2,6-di-t-butyl-4-methylphenoxy)aluminum,diisobutyl(2,6-di-t-butylphenoxy)aluminum,di-n-octyl(2,6-di-t-butyl-4-methylphenoxy)aluminum anddi-n-octyl(2,6-di-t-butylphenoxy)aluminum.

[0055] The tertiary organoaluminum compounds (A2) may be producedby any methods without limitation and may be prepared, for example,in accordance with a known technique. The tertiary organoaluminumcompounds (A2) may be used singly, or two or more may be used incombination.

[0056] In the tertiary organoaluminum compound (A), the molar ratio(A2)/(A1) of the tertiary organoaluminum compound (A2) to thetertiary organoaluminum compound (A1) is in the range of 0% orabove and 0.8% or below. The (A2)/(A1) ratio in this range ensuresthat (meth)acrylic acid esters may be anionically polymerized whilethe occurrence of a gel stemming from the tertiary organoaluminumcompound is suppressed, and thus inherent characteristics of(meth)acrylic polymers are not impaired. Further, the above ratiomakes it possible to obtain more reliably high living propertiesduring the anionic polymerization and to produce a block copolymerhaving a highly uniform molecular weight more reliably. To furtherenhance living properties during the anionic polymerization and tofurther increase the uniformity in molecular weight of a blockcopolymer that is produced, the molar ratio (A2)/(A1) may be, forexample, 0% or above and 0.5% or below, preferably more than 0% andnot more than 0.8%, more preferably more than 0% and not more than0.5%, still more preferably not less than 0.001% and not more than0.3%, and particularly preferably not less than 0.001% and not morethan 0.1%. From the point of view of the productivity of thetertiary organoaluminum compound (A), the ratio may be 0.001% orabove. When the molar ratio (A2)/(A1) is 0.001% or above, excellentsolubility tends to be obtained and thus storage stability at lowtemperatures is enhanced.

[0057] The molar ratio (A2)/(A1) of the tertiary organoaluminumcompound (A2) to the tertiary organoaluminum compound (A1) may becontrolled by, for example, controlling the amount of synthesistime and the temperature during the synthesis of the tertiaryorganoaluminum compound (A).

[0058] The amount in which the tertiary organoaluminum compound (A)is used may be determined appropriately in accordance with factorssuch as the type of the polymerization operation, the type of asolvent constituting the polymerization system in the case ofsolution polymerization, and other various polymerizationconditions. It is usually preferable that the amount of thetertiary organoaluminum compound (A) be in the range of 0.3 to 300mol, more preferably in the range of 1 to 100 mol per mol of theorganolithium compound (B).

[0059] The Lewis base (C) used together with the tertiaryorganoaluminum compound (A) is not particularly limited as long asthe base is effective for the anionic polymerization of(meth)acrylic acid esters. The Lewis base (C) preferably comprisesat least one kind of a Lewis base selected from the groupconsisting of tertiary polyamine compounds (C1) and ether compounds(C2).

[0060] The tertiary polyamine compounds (C1) that are used are notparticularly limited as long as the compounds have two or moretertiary amine structures in the molecule and do not adverselyaffect the polymerization reaction. In the present invention, the"tertiary amine structure" means a partial chemical structure inwhich three carbon atoms are bonded to one nitrogen atom. The threecarbon atoms bonded to the nitrogen atom may form part of anaromatic ring.

[0061] Examples of the tertiary polyamine compounds (C1) includelinear polyamine compounds such asN,N,N',N'-tetramethylethylenediamine,N,N,N',N'-tetraethylethylenediamine,N,N,N',N'',N''-pentamethyldiethylenetriamine,1,1,4,7,10,10-hexamethyltriethylenetetramine andtris[2-(dimethylamino)ethyl]amine; nonaromatic heterocycliccompounds such as 1,3,5-trimethylhexahydro-1,3,5-triazine,1,4,7-trimethyl-1,4,7-triazacyclononane and1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaazacyclooctadecane;and aromatic heterocyclic compounds such as 2,2'-bipyridyl and2,2':6',2''-terpyridine. Among the tertiary polyamine compounds(C1), linear polyamine compounds are preferable from the point ofview of high polymerization initiation efficiency and also becausehigh living properties can be maintained during the polymerization,and N,N,N',N'-tetramethylethylenediamine,N,N,N',N'',N''-pentamethyldiethylenetriamine and1,1,4,7,10,10-hexamethyltriethylenetetramine are morepreferable.

[0062] It is not preferable to use a tertiary monoamine compoundsuch as triethylamine in place of the Lewis base (C) because suchuse causes a decrease in polymerization initiation efficiency and adecrease in living properties during the polymerization.

[0063] The tertiary polyamine compounds (C1) may be used singly, ortwo or more may be used in combination.

[0064] The ether compounds (C2) that are used may be any compoundswithout limitation as long as the compounds have an ether bond(--O--) in the molecule, do not contain metal components, and donot adversely affect the polymerization reaction. From points ofview such as high polymerization initiation efficiency and highliving properties during the polymerization, preferred ethercompounds (C2) are acyclic ether compounds (C2-1) having one ormore ether bonds in the molecule, and cyclic ether compounds (C2-2)having two or more ether bonds in the molecule.

[0065] Examples of the acyclic ether compounds (C2-1) having one ormore ether bonds in the molecule include acyclic monoethercompounds such as dimethyl ether, diethyl ether, diisopropyl ether,dibutyl ether and anisole; acyclic diether compounds such as1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-diisopropoxyethane,1,2-dibutoxyethane, 1,2-diphenoxyethane, 1,2-dimethoxypropane,1,2-diethoxypropane, 1,2-diisopropoxypropane, 1,2-dibutoxypropane,1,2-diphenoxypropane, 1,3-dimethoxypropane, 1,3-diethoxypropane,1,3-diisopropoxypropane, 1,3-dibutoxypropane, 1,3-diphenoxypropane,1,4-dimethoxybutane, 1,4-diethoxybutane, 1,4-diisopropoxybutane,1,4-dibutoxybutane and 1,4-diphenoxybutane; acyclic triethercompounds such as diethylene glycol dimethyl ether, dipropyleneglycol dimethyl ether, dibutylene glycol dimethyl ether, diethyleneglycol diethyl ether, dipropylene glycol diethyl ether anddibutylene glycol diethyl ether; and polyalkylene glycol dialkylethers such as triethylene glycol dimethyl ether, tripropyleneglycol dimethyl ether, tributylene glycol dimethyl ether,triethylene glycol diethyl ether, tripropylene glycol diethylether, tributylene glycol diethyl ether, tetraethylene glycoldimethyl ether, tetrapropylene glycol dimethyl ether, tetrabutyleneglycol dimethyl ether, tetraethylene glycol diethyl ether,tetrapropylene glycol diethyl ether and tetrabutylene glycoldiethyl ether.

[0066] Examples of the cyclic ether compounds (C2-2) having two ormore ether bonds in the molecule include crown ethers such as12-crown-4, 15-crown-5, and 18-crown-6.

[0067] Among the ether compounds (C2), the acyclic ether compounds(C2-1) are preferable for reasons such as high availability andalso because these compounds have little adverse effects on thetertiary organoaluminum compounds (A) and the advantageous effectsof the present invention are markedly produced. Diethyl ether and1,2-dimethoxyethane are more preferable.

[0068] When a cyclic ether compound having one ether bond in themolecule, for example, tetrahydrofuran or an epoxy compound such aspropylene oxide, is used as the ether compound (C2), such an ethercompound may too strongly interact with the tertiary organoaluminumcompound (A) or may react directly with the organolithium compound(B) or the living polymer in the course of growth. It is thereforeusually desirable to avoid the use of a cyclic ether compoundhaving one ether bond in the molecule as the Lewis base (C).

[0069] The ether compounds (C2) may be used singly, or two or moremay be used in combination.

[0070] Other Lewis bases (C) which may be used are compounds havingone or more ether bonds and one tertiary amine structure in themolecule, and compounds having one or more ether bonds and two ormore tertiary amine structures in the molecule. The compoundshaving one or more ether bonds and one tertiary amine structure inthe molecule may be classified into the ether compounds (C2), andthe compounds having one or more ether bonds and two or moretertiary amine structures in the molecule may be classified intothe polyamine compounds (C1).

[0071] The Lewis bases (C) may be used singly, or two or more maybe used in combination. Thus, use may be made of a mixture of thetertiary polyamine compound (C1) and the ether compound (C2).

[0072] The amount in which the Lewis base (C) is used may bedetermined appropriately in accordance with factors such asreaction conditions. From points of view such as highpolymerization initiation efficiency and high living propertiesduring the polymerization, the molar ratio of the Lewis base (C) tothe organolithium compound (B) is preferably not less than 0.1,more preferably not less than 0.3, and still more preferably notless than 0.5.

[0073] While the Lewis base (C) may also be used as a solvent, itis generally preferable that the amount of the Lewis base (C) belimited to not more than 95 mass % of the total mass of thepolymerization system in order to avoid a significant decrease inpolymerization initiation efficiency.

[0074] The anionic polymerization process of the present inventionmay adopt any polymerization mode such as solution polymerization,bulk polymerization or precipitation polymerization. Solutionpolymerization in an organic solvent is preferable because, forexample, the polymerization temperature can be controlled, and theconditions in the polymerization system can be equalized to allowthe polymerization to proceed smoothly. The organic solvents arenot particularly limited. For example, aromatic hydrocarbonsolvents such as toluene, ethylbenzene and xylene; saturatedhydrocarbon solvents such as hexane, cyclohexane andmethylcyclohexane; halogenated hydrocarbon solvents such aschloroform, methylene chloride and carbon tetrachloride; and estersolvents such as dimethyl phthalate are generally preferably usedbecause, for example, these solvents can be handled relativelysafely, will not find their way into waste water, and can be easilyrecovered for purification. The organic solvents may be usedsingly, or two or more may be used in combination.

[0075] When an organic solvent is used in the anionicpolymerization process of the present invention, the amount thereofmay be selected appropriately in accordance with factors such asthe polymerization degree of the target polymer, the types ofmonomers, the type of the organolithium compound (B) used, the typeof the tertiary organoaluminum compound (A), the type of the Lewisbase (C), and the type of the organic solvent. To ensure, forexample, that the polymerization will take place smoothly, that thepolymer produced may be separated and collected easily, and thatthe burden of waste treatment may be reduced, it is generallypreferable to use an organic solvent in the range of 200 to 3000parts by weight per 100 parts by weight of the anionicallypolymerizable monomers that are used.

[0076] In the anionic polymerization process of the presentinvention, the Lewis base (C) and the tertiary organoaluminumcompound (A) are preferably brought into contact with each otherbefore contact with the organolithium compound (B). In this manner,high polymerization initiation efficiency may be ensured. Thetertiary organoaluminum compound (A) may be added to thepolymerization system before a (meth)acrylic acid ester and anyother anionically polymerizable monomers are added, or may be addedto the polymerization system at the same time as the monomers. Inthe latter case, the tertiary organoaluminum compound (A) and themonomers may be mixed together beforehand and added in the form ofa mixture.

[0077] In the anionic polymerization process of the presentinvention, a copolymer may be obtained by using two or more kindsof (meth)acrylic acid esters, or using one or more kinds of(meth)acrylic acid esters and one or more kinds of otheranionically polymerizable monomers. In this case, the copolymer maybe produced in a desired form such as random, block or taperedblock in a customary manner in usual anionic polymerization, forexample, by adding the monomers appropriately (for example, byadding two or more kinds of monomers concurrently or separatelywith time intervals) or by combining the monomers appropriately. Inview of the fact that the anionic polymerization process of thepresent invention can attain high living properties, the process isparticularly suited for the production of block copolymers thatrequires high blocking efficiency.

[0078] In the anionic polymerization process of the presentinvention, other known additives may be added to the polymerizationsystem as required in accordance with known anionic polymerizationtechniques. Examples of such additives include inorganic salts suchas lithium chloride; metal alkoxide compounds such as lithiummethoxyethoxyethoxide and potassium t-butoxide; and organicquaternary salts such as tetraethylammonium chloride andtetraethylphosphonium bromide.

[0079] In the anionic polymerization process of the presentinvention, the polymerization temperature may be selectedappropriately in accordance with factors such as the type of the(meth)acrylic acid ester used. In general, the polymerizationtemperature is preferably in the range of -60.degree. C. to+100.degree. C., and more preferably in the range of -30.degree. C.to +50.degree. C. At an excessively low polymerization temperature,an acrylic acid ester is polymerized to give a highly stereoregularpolymer. Thus, when the target polymer is an acrylic acid esterpolymer having high flexibility, the polymerization temperature ispreferably -50.degree. C. or above. In the anionic polymerizationprocess of the present invention, the cooling conditions on thepolymerization system may be mild as compared with the conventionalanionic polymerization processes, and high living properties can beachieved even when the polymerization is performed at a temperaturecloser to room temperature.

[0080] The anionic polymerization process of the present inventionis preferably carried out in an atmosphere of an inert gas such asnitrogen, argon or helium. In the anionic polymerization process ofthe present invention, further, polymerization is preferablyconducted while performing sufficient stirring so that thepolymerization system will become uniform. In the anionicpolymerization process of the present invention, the polymerizationtime may be selected appropriately in accordance with factors suchas the molecular weight of the polymer. As compared with theconventional polymerization processes, the process of the presentinvention allows polymerization to proceed at a high rate. Whilethe amount of polymerization time is variable depending on thepolymerization conditions that are adopted, for example, thepolymerization of a methacrylic acid ester can be completed withina few minutes, and the polymerization of an acrylic acid ester canbe completed within a few tens of seconds. Thus, the anionicpolymerization process of the present invention may perform anionicpolymerization in a tubular continuous polymerization apparatusthat offers high productivity and good cooling efficiency.

[0081] In the anionic polymerization process of the presentinvention, the polymerization reaction may be terminated uponcompletion of the formation of the target polymer chains, by addinga polymerization terminator to the reaction mixture in accordancewith the known anionic polymerization processes. For example, aprotonic compound such as methanol, acetic acid, or a methanolsolution of hydrochloric acid may be used as the polymerizationterminator. The amount in which the polymerization terminator isused may be selected appropriately in accordance with factors suchas the amount of the active terminals of the polymer, but isgenerally preferably in the range of 1 to 100 mol per mol of theorganolithium compound (B).

[0082] In the anionic polymerization process of the presentinvention, a terminal functional group-imparting agent (such as,for example, aldehyde, lactone or carbon dioxide) may be added tothe reaction system after the scheduled polymerization has beencompleted and before the polymerization terminator is added. Inthis case, the polymer that is obtained has a functional group suchas a hydroxyl group or a carboxyl group at an end of the molecularchain. The polymer separated and collected from the reactionmixture after the termination of the polymerization containsresidual metal components derived from the organolithium compound(B) or the tertiary organoaluminum compound (A) used in thepolymerization. Such residual metal components sometimes causedeterioration in properties such as transparency of the polymer andmaterials containing the polymer. Thus, the polymer for somespecific use application is preferably cleaned after the completionof the polymerization to remove the metal compounds derived fromthe organolithium compound (B) and the tertiary organoaluminumcompound (A). The metal compounds may be effectively removed bysubjecting the polymer to a purification treatment such as awashing treatment using an acidic aqueous solution or an adsorptiontreatment using an adsorbent such as an ion exchange resin.Examples of the acidic aqueous solutions used here includehydrochloric acid, aqueous sulfuric acid solution, aqueous nitricacid solution, aqueous acetic acid solution, aqueous propionic acidsolution and aqueous citric acid solution.

[0083] The polymer may be separated and collected from the reactionmixture after the termination of the polymerization in any mannerwithout limitation in accordance with known procedures. Forexample, the polymer may be separated and collected by pouring thereaction mixture into a poor solvent for the polymer to precipitatethe polymer, or by distilling off the solvent from the reactionmixture to collect the polymer.

[0084] Further, a polymer with a desired molecular weight may beproduced according to the present invention. The molecular weightsof polymers that may be produced range widely. From points of viewsuch as the handleability, fluidity and mechanical properties of apolymer that is obtained, however, it is generally preferable thatthe number average molecular weight be in the range of 1000 to1000000. Further, according to the present invention, a polymerhaving a highly uniform molecular weight (that is, a narrowmolecular weight distribution) may be usually obtained, and it ispossible to produce a polymer having a molecular weightdistribution (Mw/Mn) of 1.5 or less. Incidentally, a polymer havinga wide molecular weight distribution may be purposefully obtainedby controlling, for example, the rate of addition of theanionically polymerizable monomers to the polymerization system, orthe rate of diffusion of the monomers in the polymerization system.Further, according to the present invention, the tertiaryorganoaluminum compound (A) satisfies the specified molar ratio ofthe tertiary organoaluminum compound (A2) to the tertiaryorganoaluminum compound (A1). Consequently, the tertiaryorganoaluminum compound (A) is unlikely to generate a gel, and thusthe deterioration in polymer characteristics caused by such a gelmay be prevented.

EXAMPLES

[0085] Hereinbelow, the present invention will be described indetail based on Examples. However, it should be construed that thescope of the present invention is not limited thereto. Propertiesin Examples and Comparative Examples were measured or evaluated bythe following methods. Further, chemicals used in Examples andother experiments described below were dried and purified byconventional methods and were deaerated with nitrogen before use.The chemicals were transferred and supplied in nitrogenatmosphere.

"Weight average molecular weight (Mw), number average molecularweight (Mn) and molecular weight distribution (Mw/Mn)"

[0086] The weight average molecular weight, number averagemolecular weight, and molecular weight distribution of blockcopolymers obtained in Examples and Comparative Examples describedlater were measured by gel permeation chromatography (hereinafter,abbreviated as GPC) relative to polystyrenes. The details are asfollows. Device: GPC device "HLC-8020" manufactured by TOSOHCORPORATION. Separation columns: "TSKgel GMHXL", "G4000HXL" and"G5000HXL" manufactured by TOSOH CORPORATION were connected inseries. Eluent: Tetrahydrofuran. Eluent flow rate: 1.0 mL/min.Column temperature: 40.degree. C. Detection method: Differentialrefractive index (RI).

"Molar Ratio (A2)/(A1)"

[0087] The molar ratio ofdiisobutyl(2,6-di-t-butyl-4-methylphenoxy)aluminum (A2) toisobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum (A1) present inthe tertiary organoaluminum compounds (A) obtained in ReferenceExamples described later was determined by .sup.1H-NMRmeasurement.

(.sup.1H-NMR Measurement Conditions)

[0088] Device: Nuclear magnetic resonance device "JNM-ECX400"manufactured by JEOL Ltd.

[0089] Temperature: 25.degree. C.

[0090] Solvent: Deuterated toluene (Calculation of molar ratio)

[0091] In .sup.1H-NMR measurement, signals at near 1.45 ppm and1.55 ppm were assigned to the t-butyl group (--C--(CH.sub.3).sub.3)in diisobutyl(2,6-di-t-butyl-4-methylphenoxy)aluminum (A2) and tothe t-butyl group (--C--(CH.sub.3).sub.3) inisobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum (A1),respectively. The molar ratio (A2)/(A1) was calculated from theintegral ratio of the signals.

"Uniformity in Molecular Weight"

[0092] The molecular weight distribution of block copolymersobtained in Examples and Comparative Examples described later wasmeasured. The molecular weight was evaluated as highly uniform".largecircle." when the molecular weight distribution was 1.5 orless and as poorly uniform "x" when the molecular weightdistribution was more than 1.5.

"Presence or Absence of Gel"

[0093] The presence or absence of a gel in the first-stagepolymerization of Examples and Comparative Examples described laterwas determined by visually checking the inner wall of athree-necked flask used in the test after the first-stagepolymerization. When there was no attachment of a gel, thepolymerization was evaluated as free from gelation ".largecircle.".When a gel had been attached, the polymerization was evaluated ashaving been accompanied by gelation "x".

"Polymerization Initiation Efficiency"

[0094] The polymerization initiation efficiency (F1) in thefirst-stage polymerization was calculated from the followingequation wherein Mn (R1) is the Mn of the polymer obtained in thefirst-stage polymerization, and Mn (I1) is the Mn of the polymercalculated assuming that the polymerization initiation efficiencyin the first-stage polymerization is 100%.

F1=Mn(I1)/Mn(R1)

Preparation of Tertiary Organoaluminum Compound (A):isobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum

Reference Example 1

[0095] 34 mL of dry toluene obtained by drying with sodium anddistillation in an argon atmosphere, and 8.21 g of2,6-di-t-butyl-4-methylphenol were added to a 200 mL volume flaskpurged with argon. The mixture was stirred at room temperature togive a solution. 6.19 mL of a 20 wt % toluene solution oftriisobutylaluminum was added to the solution obtained, and themixture was stirred at 110.degree. C. for 28 hours to give atoluene solution containing a tertiary organoaluminum compound (A)at a concentration of 0.46 mol/L.

[0096] A portion of the tertiary organoaluminum compound (A)obtained was sampled and analyzed by .sup.1H-NMR. The molar ratioof diisobutyl(2,6-di-t-butyl-4-methylphenoxy)aluminum (A2) toisobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum (A1) was0.00438%. Further, it was shown that the toluene solution of thetertiary organoaluminum compound (A) had excellent storagestability at low temperatures.

Reference Example 2

[0097] A tertiary organoaluminum compound (A) was prepared in thesame manner as in Reference Example 1, except that the stirringtime was changed to 25.5 hours. A portion of the tertiaryorganoaluminum compound (A) obtained was sampled and analyzed by.sup.1H-NMR. The molar ratio (A2)/(A1) was 0.307%. Further, it wasshown that the toluene solution of the tertiary organoaluminumcompound (A) had excellent storage stability at lowtemperatures.

Reference Example 3

[0098] A tertiary organoaluminum compound (A) was prepared in thesame manner as in Reference Example 1, except that the stirringtime was changed to 23.7 hours. A portion of the tertiaryorganoaluminum compound (A) obtained was sampled and analyzed by.sup.1H-NMR. The molar ratio (A2)/(A1) was 0.505%. Further, it wasshown that the toluene solution of the tertiary organoaluminumcompound (A) had excellent storage stability at lowtemperatures.

Reference Example 4

[0099] A tertiary organoaluminum compound (A) was prepared in thesame manner as in Reference Example 1, except that the stirringtime was changed to 21.7 hours. A portion of the tertiaryorganoaluminum compound (A) obtained was sampled and analyzed by.sup.1H-NMR. The molar ratio (A2)/(A1) was 0.731%. Further, it wasshown that the toluene solution of the tertiary organoaluminumcompound (A) had excellent storage stability at lowtemperatures.

Reference Example 5

[0100] A tertiary organoaluminum compound (A) was prepared in thesame manner as in Reference Example 1, except that the stirringtime was changed to 19.6 hours. A portion of the tertiaryorganoaluminum compound (A) obtained was sampled and analyzed by.sup.1H-NMR. The molar ratio (A2)/(A1) was 0.999%.

Reference Example 6

[0101] A tertiary organoaluminum compound (A) was prepared in thesame manner as in Reference Example 1, except that the stirringtime was changed to 17.5 hours. A portion of the tertiaryorganoaluminum compound (A) obtained was sampled and analyzed by.sup.1H-NMR. The molar ratio (A2)/(A1) was 1.28%.

TABLE-US-00001 TABLE 1 Organoaluminum Stirring compound [mmol/kg](A2)/(A1) time [h] TBT (A1) DIBA (A2) [%] Ref. Ex. 1 28 67.60.00296 0.00438 Ref. Ex. 2 25.5 77.1 0.237 0.307 Ref. Ex. 3 23.767.1 0.339 0.505 Ref. Ex. 4 21.7 77.0 0.563 0.731 Ref. Ex. 5 19.667.5 0.674 0.999 Ref. Ex. 6 17.5 76.0 0.969 1.28

[0102] The abbreviations in Table 1 mean the following.

IBT: Isobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum DIBA:Diisobutyl(2,6-di-t-butyl-4-methylphenoxy)aluminum

Example 1

[0103] (1) A 100 mL volume, three-necked flask was fitted with asemicircular stirring rod, and the system was purged with nitrogen.There were added 28.3 g of toluene, 0.35 g of1,1,4,7,10,10-hexamethyltriethylenetetramine, and 6.5 mL of the0.46 mmol/L toluene solution of the tertiary organoaluminumcompound (A) prepared in Reference Example 1. The mixture wascooled to 20.degree. C. using a water bath. Further, 1.12 mL of acyclohexane solution containing 1.30 mmol of sec-butyllithium wasadded, and the mixture was stirred for 20 minutes. At this time,the concentrations of 1,1,4,7,10,10-hexamethyltriethylenetetramineand sec-butyllithium were 32.9 mmol/kg and 34.1 mmol/kg,respectively. While vigorously stirring the solution, 8.9 g ofmethyl methacrylate was added dropwise thereto over a period ofabout 2 minutes at 20.degree. C. The solution was initially coloredyellow and the color faded in 1 minute after the completion of thedropwise addition.

[0104] (2) A portion of the solution obtained in (1) was sampledand was poured into a large amount of methanol to precipitate awhite deposit (PMMA), which was then recovered and dissolved intotetrahydrofuran. The polymer (PMMA) obtained in the first-stagepolymerization was analyzed by GPC and was found to have Mw of 7370and Mw/Mn of 1.16. The polymerization initiation efficiency was0.96.

[0105] (3) Another 100 mL volume, three-necked flask was fittedwith a semicircular stirring rod, and the system was purged withnitrogen. After 40.8 g of toluene was added, 4.6 g of the solutionobtained in (1) was added. The mixture was cooled using a-22.degree. C. methanol bath. When the internal temperature reached-19.degree. C., 6.72 mL of n-butyl acrylate as the second monomerwas added dropwise over a period of 13 minutes and was therebypolymerized.

[0106] (4) A portion of the solution obtained in (3) was sampledand was poured into a large amount of methanol to precipitate awhite deposit (PMMA-b-PnBA), which was then recovered and dissolvedinto tetrahydrofuran. The solution was analyzed by GPC. The blockcopolymer obtained (PMMA-b-PnBA) showed a monomodal peak, and hadMw of 62700 and Mw/Mn of 1.23. The polymerization conditions andthe polymerization results are described in Table 2 later.

Examples 2 to 4, and Comparative Examples 1 and 2

[0107] Polymerization was performed and terminated in the samemanner as in Example 1, except that the tertiary organoaluminumcompound (A) prepared in Reference Example 1 was replaced by any ofthe tertiary organoaluminum compounds (A) prepared in ReferenceExamples 2 to 6. The polymerization conditions and thepolymerization results are described in Table 2 later.

Comparative Example 3

[0108] Polymerization was performed and terminated in the samemanner as in Example 1, except that1,1,4,7,10,10-hexamethyltriethylenetetramine was not used. Thepolymerization conditions and the polymerization results aredescribed in Table 2 below.

TABLE-US-00002 TABLE 2 Polymerization results Polymerizationconditions Second-stage Lewis First-stage polymerization (MMA)polymerization (nBA) Initiator base Polymerization PresenceUniformity (sBL) (HMTETA) (A2)/(A1) initiation or absence inmolecular [mmol/kg] [mmol/kg] [%] Mw Mw/Mn efficiency of gel MwMw/Mn weight Ex. 1 32.9 34.1 0.00438 7370 1.16 0.96 .smallcircle.62700 1.23 .smallcircle. Ex. 2 33.2 34.9 0.307 7820 1.13 0.87.smallcircle. 63500 1.20 .smallcircle. Ex. 3 32.9 34.1 0.505 70801.14 0.98 .smallcircle. 61800 1.22 .smallcircle. Ex. 4 33.1 34.70.731 7920 1.15 0.85 .smallcircle. 69300 1.31 .smallcircle. Comp.32.9 34.0 0.999 7440 1.15 0.94 x 77700 1.53 x Ex. 1 Comp. 33.0 35.01.28 7900 1.16 0.84 x 91100 1.78 x Ex. 2 Comp. 32.9 -- 0.00438 Notpolymerized -- Not polymerized -- Ex. 3

[0109] The abbreviations in Table 2 mean the following.

sBL: sec-Butyllithium

HMTETA: 1,1,4,7,10,10-Hexamethyltriethylenetetramine

[0110] MMA: Methyl methacrylate nBA: n-Butyl acrylate

[0111] The results described in Table 2 showed that Examples 1 to 4in accordance with the present invention successfully producedPMMA-b-PnBA diblock copolymers having a narrow molecular weightdistribution (Mw/Mn=1.20 to 1.31) without the occurrence of agel.

[0112] Comparative Examples 1 and 2 showed that when the molarratio (A2)/(A1) exceeded 0.8%, PMMA-b-PnBA diblock copolymers had awide molecular weight distribution of more than 1.5. Further,Comparative Example 3 showed that PMMA was not formed when thepolymerization omitted the use of1,1,4,7,10,10-hexamethyltriethylenetetramine.

Examples 5 to 7

[0113] Polymerization was performed and terminated in the samemanner as in Example 3, except that1,1,4,7,10,10-hexamethyltriethylenetetramine was replaced byN,N,N',N'',N''-pentamethyldiethylenetriamine, 1,2-dimethoxyethaneor diethyl ether. The polymerization conditions and thepolymerization results are described in Table 3 later.

Comparative Example 4

[0114] Polymerization was performed and terminated in the samemanner as in Example 5, except that the tertiary organoaluminumcompound (A) prepared in Reference Example 3 was replaced by thetertiary organoaluminum compound (A) prepared in Reference Example5. The polymerization conditions and the polymerization results aredescribed in Table 3 later.

Comparative Example 5

[0115] Polymerization was performed and terminated in the samemanner as in Example 6, except that the tertiary organoaluminumcompound (A) prepared in Reference Example 3 was replaced by thetertiary organoaluminum compound (A) prepared in Reference Example5. The polymerization conditions and the polymerization results aredescribed in Table 3 later.

Comparative Example 6

[0116] Polymerization was performed and terminated in the samemanner as in Example 7, except that the tertiary organoaluminumcompound (A) prepared in Reference Example 3 was replaced by thetertiary organoaluminum compound (A) prepared in Reference Example5. The polymerization conditions and the polymerization results aredescribed in Table 3 below.

TABLE-US-00003 TABLE 3 Polymerization results Second-stagePolymerization conditions First-stage polymerization (MMA)polymerization (nBA) Initiator Polymerization Presence Uniformity(sBL) Lewis base (A2)/(A1) initiation or absence in molecular[mmol/kg] Type [mmol/kg] [%] Mw Mw/Mn efficiency of gel Mw Mw/Mnweight Ex. 5 32.9 PMDETA 34.0 0.505 9020 1.25 0.82 .smallcircle.71000 1.27 .smallcircle. Comp. 33.0 PMDETA 34.1 0.999 9300 1.220.78 x 79500 1.56 x Ex. 4 Ex. 6 32.9 DME 138 0.505 6850 1.10 0.94.smallcircle. 61800 1.23 .smallcircle. Comp. 32.9 DME 138 0.9997120 1.12 0.92 x 81000 1.61 x Ex. 5 Ex. 7 32.9 Et.sub.2O 171 0.50510500 1.22 0.71 .smallcircle. 73600 1.31 .smallcircle. Comp. 32.8Et.sub.2O 170 0.999 9680 1.20 0.74 x 94100 1.70 x Ex. 6

[0117] The abbreviations in Table 3 mean the following.

sBL: sec-Butyllithium

PMDETA: N,N,N',N'',N''-Pentamethyldiethylenetriamine

DME: 1,2-Dimethoxyethane

[0118] Et.sub.2O: Diethyl ether MMA: Methyl methacrylate nBA:n-Butyl acrylate

[0119] The results described in Table 3 showed that Examples 5 to 7in accordance with the present invention successfully producedPMMA-b-PnBA diblock copolymers having a narrow molecular weightdistribution (Mw/Mn=1.23 to 1.31) even when the Lewis base (C) waschanged from 1,1,4,7,10,10-hexamethyltriethylenetetramine toN,N,N',N'',N''-pentamethyldiethylenetriamine, 1,2-dimethoxyethaneor diethyl ether.

[0120] Comparative Examples 4 to 6 afforded PMMA-b-PnBA diblockcopolymers, but the molecular weight distributions thereof werelarger than 1.5.

INDUSTRIAL APPLICABILITY

[0121] The present invention, which pertains to a process foranionically polymerizing an anionically polymerizable monomer andto a method for producing a polymer by the polymerization process,is useful in industry because it provides a more reliable processfor anionically polymerizing a (meth)acrylic acid ester thatattains high living properties without impairing the inherentcharacteristics of (meth)acrylic polymers such as transparency, andalso allows for more reliable production of a (meth)acrylic acidester block polymer having a highly uniform molecular weight.

* * * * *