JP2002206003A - Method for producing anionic polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a purifying agent capable of promoting an objective reaction in an anionic polymerization system even in using a reagent which is difficult to be purified, and obtaining a structurally controlled polymer having a narrow molecular weight distribution even in the presence of the above purifying agent. SOLUTION: In this method for producing an anionic polymer, a vinyl aromatic compound or conjugated diene and a compound expressed by formula (I) (R1)nM [wherein, R1 is a 1-20C alkyl or a 6-20C aryl and in the case that (n) is >=2, R1's may be the same or different; M is an atom belonging to the 2nd, 12th or 13th group of the long period Periodic Table; and (n) is the atomic valence of M] are added to a solution of an alkali metal or an organo-alkali metal at a temperature of -100 to 20 deg.C in a polar solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an anionic polymer using a living anionic polymerization method using a plurality of metals as an initiator and a coordination metal at a growth terminal.

[0002]

2. Description of the Related Art In an anionic polymerization system, the presence of a protic polar solvent such as water or alcohol deactivates an anion at the growth terminal or a polymerization initiator. Therefore, these must be removed from the polymerization system. Conventionally, as a solvent or a remover for a protic polar solvent in a monomer used for a reaction, for example, benzylmagnesium bromide, butyllithium, and the like are known, but these act as a polymerization initiator or a polymerization inhibitor. For this reason, purification such as distillation is required before the reaction, but there is a problem that purification of monomers having a high boiling point becomes difficult.

In the synthesis of polymers such as polystyrene, an organic alkali metal such as n-butyllithium and an alkali metal such as sodium serve as an anionic polymerization initiator. However, an organic metal such as dibutylmagnesium alone uses an anionic polymerization initiator. It is known that this is not the case.

Hsieh et al. Disclose that dibutylmagnesium does not have the ability to initiate polymerization with respect to styrene and dienes, but that s-butyllithium or polystyryl anion and dibutylmagnesium form an ate complex to serve as a polymerization initiator. Reporting.

Sawamoto et al. Performed bulk polymerization of styrene using an n-butyllithium / dibutylmagnesium complex, and even if the polymerization temperature was as high as 120 ° C., a polymer having a relatively narrow molecular weight distribution was obtained. It reports that it can be obtained.

[0006]

However, depending on the type of monomer used and the amount of dibutylmagnesium used, there are problems that it is difficult to control the polymerization and that a polymer cannot be obtained with a satisfactory yield. . The present invention provides a purifying agent in which an objective reaction can proceed even when a reagent or the like which is difficult to purify is used in an anionic polymerization system, and further, in the presence of such a purifying agent, a structure having a narrow molecular weight distribution is controlled. It is an object of the present invention to provide a production method capable of obtaining a polymer.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, it has been found that, when a metal reagent such as dibutylmagnesium is used and polymerization is carried out under specific reaction conditions, a structure control with a narrow molecular weight distribution is achieved. It has been found that the polymer obtained can be obtained, and the present invention has been completed.

That is, the present invention relates to (1) a vinyl aromatic compound or a conjugated diene compound and a compound represented by the formula (I):

(R ₁ ) nM (wherein R ₁ is a C1-C20 alkyl group, or C6-
When n represents 2 or more, R ₁ may be the same or different, and M represents an atom belonging to Group 2, 12 or 13 of the periodic table. And n represents the valence of M. (2) a method for producing an anionic polymer, which comprises adding a compound represented by the formula (1) to a solution of an alkali metal or an organic alkali metal in a polar solvent at −100 to 20 ° C .; Growth terminal anion of dimer or higher polymer prepared from conjugated diene compound and alkali metal or organic alkali metal and formula (I)

Embedded image In a polar solvent containing a compound represented by the formula (R ₁ ) nM (wherein R ₁ , M and n have the same meanings as described above), -100
A method for producing an anionic polymer, characterized by adding a vinyl aromatic compound or a diene compound at a temperature of from 20 to 20 ° C;
(3) The method according to any one of (1) to (2), wherein the polar solvent is tetrahydrofuran.
(4) The method according to any one of (1) to (3), wherein the compound represented by the formula (I) is used in excess of an alkali metal or an organic alkali metal.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Specific examples of the vinyl aromatic compound as a monomer used in the present invention include styrene and α-
Examples thereof include alkyl styrene and nucleus-substituted styrene. The nucleus substituent is incompatible with the alkali metal or organic alkali metal used for the polymerization initiator and the organometallic compound represented by the formula (I). It is not particularly limited as long as it is an active group, and specifically, an alkyl group, an alkoxyalkyl group, an alkoxy group, an alkoxyalkoxy group, t
-Butoxycarbonyl group, t-butoxycarbonylmethyl group, tetrahydropyranyl group and the like. Further, as specific examples thereof, α-methylstyrene, α-methyl-p-methylstyrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, p-methylstyrene
Ethylstyrene, 2,4-dimethylstyrene, 2,5-
Dimethylstyrene, p-isopropylstyrene, 2,
4,6-triisopropylstyrene, pt-butoxystyrene, pt-butoxy-α-methylstyrene, m
-T-butoxystyrene and the like.

As the conjugated diene compound which is a monomer used in the present invention, specifically, 1,3-butadiene,
Examples include isoprene, 2,3-dimethylbutadiene, 2-ethyl-1,3-butadiene, and 1,3-pentadiene. These compounds can be used alone or in combination of two or more kinds of the desired copolymer.

[0011] The polymerization is preferably carried out in a temperature range of -100 ° C to 20 ° C. Although the lower limit of the polymerization temperature varies depending on the reactivity of the monomer used, it must be at least a temperature at which the polymerization is completed. Usually, the polymerization proceeds even at −100 ° C. or lower, but the reaction rate becomes slow. When the temperature is 20 ° C. or higher, side reactions such as a transfer reaction and a termination reaction occur, and it is difficult to obtain a target polymer having a controlled structure.

In the present invention, the polymerization temperature does not need to be constant during the polymerization reaction, but may be increased at an arbitrary rate as the polymerization reaction proceeds. For example, the monomer to be added may be divided into two parts, and the polymerization may be performed at first at a low temperature, and then the temperature may be increased to further add the monomer to perform the polymerization. The concentration of the monomer used in the present invention with respect to the polymerization solvent is not particularly limited, but is usually in the range of 10 to 40% by weight.

[0013] The polymerization solvent used in the present invention is not particularly limited as long as it is a polar solvent which does not participate in the polymerization reaction and is compatible with the polymer.
Ether compounds such as tetrahydrofuran, dioxane and trioxane; tetraethylenediamine (TMED
A), hexamethylphosphoric triamide (HMP
Tertiary amines such as A) can be exemplified, and tetrahydrofuran is particularly preferred. In addition, these solvents include 1
The solvents can be used alone or as a mixed solvent of two or more.

In addition, even a low-polarity aliphatic, aromatic or alicyclic hydrocarbon compound can be used in combination with a polar solvent if it is relatively compatible with the polymer. Specifically, toluene, TMEDA, HM
A combination of a tertiary amine with PA can be exemplified. In this case, it is preferable to use about 1 to 10 equivalents based on the initiator using the tertiary amine, and also to use a combination of toluene and an ether solvent such as tetrahydrofuran. In this case, toluene is added to the ether-based solvent in a volume of 50%.
It is preferable to use not more than% by volume.

The polymerization initiator used in the present invention is:
It is composed of an alkali metal or an organic alkali metal, and as the alkali metal, lithium, sodium, potassium, cesium and the like can be exemplified. As the organic alkali metal, an alkylated product, an allylic product, an arylated product of the above alkali metal is used. Specifically, ethyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium, ethyl sodium, lithium biphenyl, lithium naphthalene, lithium triphenyl, sodium naphthalene, potassium naphthalene, α
-Methylstyrene sodium dianion, 1,1-diphenylhexyllithium, 1,1-diphenyl-3-methylpentyllithium, 1,4-dirithi-2-butene, 1,6-dilithiohexane, polystyryllithium, cumylpotassium, Cumyl cesium and the like can be mentioned, and these compounds can be used alone or in combination of two or more.

In the organometallic reagent represented by the formula (I) used in the present invention, R ₁ is a hydrogen atom, a halogen atom, C1
Represents a C20 alkyl group or a C6-C20 aryl group. Specifically, a chloro atom, a bromo atom, an iodine atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, a t-butyl group, an isobutyl group, an amyl group, a hexyl group Group, benzyl group, phenyl group, naphthyl group and the like.

M represents an atom belonging to Group 2, 12 or 13 of the Long Periodic Table, and n represents the valency of M. Of these, magnesium, zinc and aluminum are preferable. . Specific examples of the compound represented by the formula (I) include di-n-butylmagnesium, di-t-butylmagnesium, di-s-butylmagnesium, n-butyl-s-butylmagnesium, and n-butyl-ethyl. Magnesium, di-n-amylmagnesium, dibenzylmagnesium, diphenylmagnesium, diethylzinc, dibutylzinc, trimethylaluminum, triethylaluminum, triisobutylaluminum, trin-hexylaluminum, and the like. These can be used alone or in combination of two or more.

According to the present invention, a vinyl aromatic compound or a conjugated diene compound and an organometallic compound represented by the formula (I) (R ₁ ) nM are prepared by adding an alkali metal or an organic alkali compound at -100 to 20 ° C. in a polar solvent. It is characterized in that it is added to a metal solution. The organometallic compound represented by the formula (I) alone does not initiate polymerization of a vinyl monomer, and the art complex of the organometallic compound represented by the formula (I) with an organic alkali metal initiates polymerization. Despite the ability, the initiator ability is reduced and it is difficult to control the structure of the polymer. Therefore, an organometallic compound represented by the formula (I) is added to a vinyl monomer such as a vinyl aromatic compound in advance. The above problem was solved by adding the mixture to an initiator such as an alkali metal.

By using this method, (1) it is possible to carry out anionic polymerization without performing purification such as removing in advance impurities such as active hydrogen compounds such as water in monomers that inhibit anionic polymerization. Can be. In particular, it is possible to perform living anion polymerization even on a compound that is difficult to purify, such as a compound having a large molecular weight of a monomer or a compound having a hygroscopic property, and (2) the organometallic compound coordinates to the anion growth terminal. As a result, the anionic growth terminal is stabilized, and living anion polymerization can be performed at around 0 ° C. without causing side reactions such as transfer reaction and termination reaction. (3) In the synthesis of high molecular weight compounds of 200,000 or more, Since the anion was stabilized, the polymerization reaction proceeded uniformly, and it was possible to obtain a polymer having a narrow molecular weight distribution.

The amount of the organometallic compound represented by the formula (I) is not particularly limited. However, when the amount of an impurity that inhibits anionic polymerization can be specified, an excess amount is used rather than the amount of the impurity, and the amount cannot be specified. In such a case, it can be used in the range of 1 to 50 equivalents, preferably 1 to 20 equivalents, based on the amount of the initiator. In particular, when synthesizing a polymer having a molecular weight of 200,000 or more, the use of 10 to 50 equivalents, preferably 30 to 50 equivalents relative to the initiator suppresses the production of the polymer on the high molecular weight side and narrows the molecular weight distribution. A polymer can be produced.

Further, after adding an excess of the mixture of the organometallic compound represented by the formula (I) and the vinyl monomer to the initiator to carry out the polymerization, the same kind or different kinds of the same kind or different kinds are further added. The polymerization can be carried out by using the monomer alone or by adding a mixture of the same or different monomer and the organometallic compound represented by the formula (I).

Alternatively, the present invention relates to a method for producing a dimer or higher polymer prepared from a vinyl aromatic compound or a conjugated diene compound and an alkali metal or an organic alkali metal, and a growth terminal anion represented by the formula (I): It is characterized in that a vinyl aromatic compound or a diene compound is added to a polar solvent containing a compound at -100 to 20C.

By synthesizing a polymer having a certain molecular weight from a monomer and a polymerization initiator which are easily purified, and adding a metal compound represented by the formula (I), By adding an excess of the mixture of the metal compound represented by the formula (I) to the initiator, a mixed solution of the growth terminal anion of the polymer and the organometallic compound represented by the formula (I) is prepared. A method in which a polymerization reaction is further performed by adding a vinyl monomer to this solution to obtain a desired polymer, and a vinyl monomer to be added later includes an organometallic compound represented by the formula (I). Can be obtained without adding any of the above. However, a similar polymer can be obtained even if it is added.

The amount of the organometallic compound represented by the formula (I) to be added is not particularly limited, and is preferably in the range of 1 to 50 equivalents to the terminal of the polymer growing anion. The type of counter cation of the polymer growth terminal anion is not particularly limited, but a sodium cation or a potassium cation can be preferably used rather than a lithium cation.

The structure of the polymer growth terminal anion is not particularly limited, but a styryl anion structure can be preferably used rather than an α-methylstyryl anion structure. Further, the molecular weight of the polymer having a growth terminal anion is not particularly limited, and any of a dimer to a tetramer, a polymer having a molecular weight of 1,000 to 10,000 and the like can be used.

By using this method, the polymerization reaction can be carried out without being affected by the organomagnesium compound, so that the operation of adding the organomagnesium compound to the vinyl monomer to be added becomes unnecessary.

Hereinafter, the present invention will be described in detail with reference to examples, but the scope of the present invention is not limited to the examples.

[0028]

EXAMPLES The methods for purifying the reagents and solvents used in Examples 1 to 12 of the present invention are described below. (1) Tetrahydrofuran (THF): Distillation was carried out in the presence of sodium wire for one day, followed by distillation in the presence of LiAlH ₄ for several hours and distillation under a nitrogen stream. In addition, dry THF
From the presence of sodium naphthalene by high vacuum
Distillation is performed by the p-to-Trap method, and monomer, Bu ₂
It was used for dilution of Mg and potassium naphthalene. (2) Heptane: Washed with concentrated sulfuric acid and then with water, dried over anhydrous magnesium sulfate, added with phosphorus (V) oxide, stirred overnight, and distilled from nitrogen in the presence of diphenylhexyllithium. Furthermore, the trap-to-trap is carried out in the presence of 1,1-diphenylhexyllithium under a high vacuum.
It was distilled by the method and used for diluting s-BuLi.

(3) sec-butyllithium (s-Bu)
Li): Commercially available cyclohexane of s-BuLi (1.3
M; manufactured by Nakarai Co., Ltd.) was diluted with heptane under high vacuum, and used in small portions. The exact concentration is TH under high vacuum
1,1-diphenylethylene (DPE) at -78 ° C in F
To produce 1,1-diphenyl-3-methylpentyllithium, which was determined by colorimetric titration using standard n-octanol / THF until the red color specific to the anion disappeared. (4) Potassium naphthalene (K-Naph): 2.36 g (60.4 mmol) of potassium metal and 13.0 g (101 mmol) of 1.5 equivalents of naphthalene were added to T under high vacuum.
THF 100 distilled by rap-to-Trap method
The reaction was performed overnight in m1 to synthesize. The exact concentration was determined by colorimetric titration with standard n-octanol / THF at room temperature. (5) Styrene: After washing the commercially aqueous 5% NaOH solution, then with water, with anhydrous magnesium sulfate, dried overnight, from ₂ presence CaH, was distilled under reduced pressure. Then, after distillation under high vacuum in the presence of 2-3 mmol% of benzylmagnesium chloride, a 0.8-1.0 M THF solution was prepared.

(6) α-methylstyrene: 5% of commercial product
After washing with an aqueous NaOH solution and then with water, the resultant was dried over anhydrous magnesium sulfate overnight, and distilled under reduced pressure in the presence of CaH ₂ . Next, after distilling under a high vacuum in the presence of 2-3 mmo 1% of benzylmagnesium chloride, a 1 M THF solution was prepared. (7) Dibutyl magnesium (Bu ₂ Mg): commercially available B
A u ₂ Mg / heptane solution (manufactured by Aldrich) was diluted with THF under high vacuum and used in small portions.

[Polymerization operation method of Examples 1 to 12] The break sealing method under high vacuum was used for anionic polymerization. In the polymerization, the monomer was added to the initiator system and reacted for a predetermined time, and then the reaction was stopped with methanol. Polymerization temperature, polymerization time, Bu ₂ Mg
By changing the amount of addition by changing the order of addition of Bu ₂ Mg, were observed refining capacity also the effect of adding Bu ₂ Mg. Also, the obtained polymer was added with HCl to remove Bu ₂ Mg from the polymer, and MeOH /
A reprecipitation operation was performed in a THF system, and after filtration, air drying was performed, and the yield was determined from the yield of the obtained polymer.

[Method for Determining Initiation Efficiency of Active Terminal Anion]
To determine the initiation efficiency of the active terminal anion, the G of the postpolymer obtained by performing postpolymerization
The PC curve was used. The peak areas corresponding to the prepolymer and the postpolymer were calculated, and the molecular ratio (molar ratio) was obtained by dividing the peak area by the molecular weight to obtain the initiation efficiency.

[Measurement of Gel Permission Chromatography (GPC)] Examples 1 to 12 and Comparative Examples 1 and 2 were measured using Tosoh HLC-8020.
The column used was a combination of HXL 5000, 4000, 3001, or HXL 4000, 3000, 2000. Examples 13 to 17 and Comparative Examples 3 to 6 were measured using a GPC system manufactured by Waters. Using THF as a solvent, a flow rate of 1.0 ml / min,
Used at 40 ° C. The molecular weight was determined from a calibration curve using standard polystyrene. As a sample, 5 mg of a polymer was dissolved in 1 ml of THF.

Example 1 A THF solution in which Bu ₂ Mg was added to a methanol-containing styrene monomer at a ratio shown in Table 1 was used to prepare a THF solution.
Table 1 shows the results of polymerization performed by adding the polymerization initiator s-BuLi in HF at -78 ° C, and its GPC curve is shown in FIG.

COMPARATIVE EXAMPLE 1 Polymerization was carried out in the same manner as in Example 1 except that Bu ₂ Mg was not used.
Shown in the figure.

[0036]

[Table 1]

Examples 2 to 6 A mixture of styrene and Bu ₂ Mg in the proportions shown in Table 2 was used.
The HF solution was added to the polymerization initiator in THF at a predetermined temperature and polymerization was carried out for 1 hour. The results are shown in Table 2 and GP.
The C curves are shown in FIGS.

[0038]

[Table 2]

Examples 7 to 8 T mixed with styrene and Bu ₂ Mg at the ratios shown in Table 3
The HF solution was added to the polymerization initiator at -78 ° C for 1 hour,
The polymerization was carried out and the results are shown in Table 3 and the GPC curves are shown in FIGS.

Comparative Example 2 Polymerization was carried out at the ratios shown in Table 3 except that Bu ₂ Mg was not used. The results are shown in Table 3 and the GPC curve is shown in Table 10.
Shown in the figure.

[0041]

[Table 3]

Example 9 As shown in Table 4, styrene was divided into two parts, and 3.3 equivalents (first monomer: I) and 5.0 equivalents (second monomer: II) of the initiator were used. Bu ₂ Mg was added, the first monomer was polymerized at a predetermined temperature for 1 hour, and then the second monomer was added to perform polymerization. Table 4 shows the results.
The C curve is shown in FIG.

Example 10 As shown in Table 4, styrene was divided into two parts, and 11 equivalents (first monomer) of Bu ₂ Mg relative to the initiator was added.
The first monomer was polymerized at a predetermined temperature for 1 hour, and then the second monomer was added to perform polymerization. The results are shown in Table 4 and the GPC curve is shown in FIG.

[0044]

[Table 4]

Examples 11 to 12 To a polymer dianion (Mn = 2000) prepared from α-methylstyrene (α-MeSt) and K-Naph, Bu ₂ Mg was added at a ratio shown in Table 5. And TH
In F, polymerization was carried out at -78 ° C.
The PC curve is shown in FIGS.

[0046]

[Table 5]

Examples 13 to 15 In 180 g of THF, styrene (St) or pt-butoxystyrene (PTBST, manufactured by Hokuko Chemical Co., Ltd.) and Bu ₂ were added to s-BuLi (a cyclohexane solution manufactured by Nakarai) at 0 ° C. A mixture of Mg was added and polymerization was carried out. The results are shown in Table 6 and GPC curves are shown in FIGS.

Comparative Examples 3 to 5 Polymerization was carried out in the same manner as in Examples 14 to 16 except that Bu ₂ Mg was used. Table 6 shows the results, and
It is shown in FIGS.

[0049]

[Table 6]

Example 16 PTBST2 was used in n-BuLi (manufactured by Aldrich) (6.80 mmol) at −40 ° C. in 250 g of THF.
After polymerizing 5.33 g (160.7 mmol) (I), 10.25 g of Bu ₂ Mg (manufactured by Aldrich) (1
9.43% by weight, 14.4 mmol) was added to the initiator, and at −40 ° C. 18.85 g of PTBST was further added.
The results obtained by adding (106.9 mmol) (II) for polymerization are shown in Table 7, and the GPC curve is shown in FIG.

[0051]

[Table 7]

Example 17 Sodium dispersion in 124 g of THF at -60 ° C. 1.14
g (0.05 mol, dispersed in kerosene at 20% by weight), 2 ml of 1,3-butadiene are added dropwise at the same temperature,
A dianion was formed. 35.7 g of dibutylmagnesium (Bu ₂ Mg: manufactured by Aldrich) was added to this solution.
(19.43% by weight, 0.05 mol), and -2
After the temperature was raised to 0 ° C., 37.5 g of 1,3-butadiene was obtained.
(0.69 mol) of a solution of 41.4 g of hexane was added at the same temperature, and the mixture was stirred at the same temperature for 3 hours. After stopping the reaction by adding methanol at the same temperature, the solvent was distilled off and the yield was 9
A 9-% 1.3-butadiene polymer was obtained. When GPC of the obtained polymer was measured, the number average molecular weight was 2,300 and the degree of dispersion (Mw / Mn) was 1.17, and a monomodal peak was obtained. The obtained GPC curve is shown in FIG.

Comparative Example 6 The procedure of Example 17 was repeated, except that the mixture was stirred at -20 ° C. for 1 hour without using Bu ₂ Mg. As a result, a 1,3-butadiene polymer was obtained with a yield of 91%. G of the obtained polymer
When the PC was measured, the number average molecular weight was 3,900, and the degree of dispersion (Mw / Mn) was 2.28, and a multimodal peak was obtained. The obtained GPC curve is shown in FIG.

[0054]

As described above, if the method of mixing the compound represented by the formula (I) with a monomer and adding the mixture to the polymerization initiator is used, (1) the monomer which inhibits anionic polymerization Anionic polymerization can be carried out without performing purification such as removal of impurities therein, for example, active hydrogen compounds such as water. In particular, it is possible to perform living anion polymerization even on a compound that is difficult to purify, such as a compound having a large molecular weight of a monomer or a compound having a hygroscopic property, and (2) the organomagnesium compound is coordinated at the anion growth terminal. As a result, the anionic growth terminal is stabilized, and living anion polymerization can be performed at around 0 ° C. without causing side reactions such as transfer reaction and termination reaction. (3) In the synthesis of high molecular weight compounds of 200,000 or more, Since the anion was stabilized, the polymerization reaction proceeded uniformly, and it was possible to obtain a polymer having a narrow molecular weight distribution. Furthermore, for the polymerization-growth terminal such as polystyryl anion, or the anion terminal of a dimer or tetramer other than lithium, by directly adding to the polymerization initiator without adding to the monomer,
Polymerization at around 0 ° C. became possible.

[Brief description of the drawings]

FIG. 1 shows a GPC curve in Example 1.

FIG. 2 shows a GPC curve in Comparative Example 1.

FIG. 3 shows a GPC curve in Example 2.

FIG. 4 shows a GPC curve in Example 3.

FIG. 5 shows a GPC curve in Example 4.

FIG. 6 shows a GPC curve in Example 5.

FIG. 7 shows a GPC curve in Example 6.

FIG. 8 shows a GPC curve in Example 7.

FIG. 9 shows a GPC curve in Example 8.

FIG. 10 shows a GPC curve in Comparative Example 2.

FIG. 11 shows a GPC curve in Example 9.

FIG. 12 shows a GPC curve in Example 10.

FIG. 13 shows a GPC curve in Example 11.

FIG. 14 shows a GPC curve in Example 12.

FIG. 15 shows a GPC curve in Example 13.

FIG. 16 shows a GPC curve in Example 14.

FIG. 17 shows a GPC curve in Example 15.

FIG. 18 shows a GPC curve in Comparative Example 3.

FIG. 19 shows a GPC curve in Comparative Example 4.

FIG. 20 shows a GPC curve in Comparative Example 5.

FIG. 21 shows a GPC curve in Example 16.

FIG. 22 shows a GPC curve in Example 17.

FIG. 23 shows a GPC curve in Comparative Example 6.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Eiichiro Kobayashi 12-8 Goi-minamikaigan, Ichihara-shi, Chiba F-term (reference) 4J015 DA02 DA03 DA05

Claims (4)

[Claims] (1) a vinyl aromatic compound or a conjugated diene compound and a compound represented by the formula (I): (R ₁ ) nM (wherein R ₁ is a C1-C20 alkyl group, or C6-
When n represents 2 or more, R ₁ may be the same or different, and M represents an atom belonging to Group 2, 12 or 13 of the periodic table. And n represents the valence of M. A method for producing an anionic polymer, comprising adding a compound represented by formula (1) to a solution of an alkali metal or an organic alkali metal in a polar solvent at -100 to 20 ° C. 2. A growth terminal anion of a polymer of a dimer or more prepared from a vinyl aromatic compound or a conjugated diene compound and an alkali metal or an organic alkali metal, and a compound represented by the formula (I): (R ₁ ) nM ( In the formula, R ₁ , M and n have the same meanings as described above.
A method for producing an anionic polymer, characterized by adding a vinyl aromatic compound or a diene compound at a temperature of from 20 to 20 ° C. 3. The method according to claim 1, wherein the polar solvent is tetrahydrofuran. 4. The method according to claim 1, wherein the compound represented by the formula (I) is used in excess of an alkali metal or an organic alkali metal.