JPH1017633A - Method for producing acrylic block copolymer - Google Patents

Abstract

An acrylic block having at least two syndiotactic polymer blocks derived from an alkyl methacrylate and at least one atactic polymer block derived from an alkyl acrylate. The copolymer is produced in good yield and in a relatively short time while controlling the desired structure and molecular weight. SOLUTION: When an organic rare earth metal compound is used as a polymerization initiator, polymerization of alkyl methacrylate and polymerization of alkyl acrylate are alternately performed.
Polymerization of acrylic acid alkyl ester is carried out at -100 ° C to -5
Perform at a temperature of ° C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an acrylic block copolymer comprising a polyalkyl methacrylate block and a polyalkyl acrylate block.

[0002]

2. Description of the Related Art JP-A-6-93060 discloses that at least two syndiotactic polymer blocks derived from an alkyl methacrylate and an alkyl acrylate are synthesized using an organic rare earth metal compound as a polymerization initiator. A method for producing an acrylic block copolymer having at least one atactic polymer block derived from the acrylic block copolymer, wherein the acrylic block copolymer has excellent heat resistance and impact resistance or elastomeric properties. Is described.

[0003] According to the description of the above-mentioned publication, an organic rare earth metal compound is used as a polymerization initiator at -100 ° C.
The above-mentioned acrylic block copolymer is obtained by first polymerizing an alkyl methacrylate at a temperature of up to + 100 ° C. and subsequently performing polymerization of an alkyl acrylate and a polymerization of an alkyl methacrylate at least once alternately. Is said to be manufactured. In this publication, as a specific example of the production method, n-butyl polyacrylate (PnBA) is polymerized at 0 ° C. by sequentially performing polymerization of methyl methacrylate, polymerization of n-butyl acrylate, and polymerization of methyl methacrylate. ) Describes an example of producing a ternary block copolymer (PMMA-PnBA-PMMA) in which a polymethyl methacrylate (PMMA) block is bonded to both ends of a block. According to this specific production example, after the polymerization is completed, the desired ternary block copolymer is separated by reprecipitation to obtain 39.
Obtained in 5% or 74% yield. In addition, the publication discloses that the desired 3
It is described that a PMMA-PnBA binary block copolymer before the second polymerization of methyl methacrylate was separated and recovered in addition to the primary block copolymer.

[0004]

As described above, in the specific production example described in JP-A-6-93060,
The yield of the terpolymer of PMMA-PnBA-PMMA is 39.5% or 74%, and the PMMA-P
The nBA diblock copolymer is by-produced. As is apparent from these descriptions, in the method described in the publication, the intermediate polymer produced by the polymerization step of the alkyl acrylate ester has the active anion terminal of the alkyl acrylate block deactivated ( Since the polymer molecules (which have lost the ability to initiate polymerization) are contained in not less than a small proportion, the yield of the desired acrylic block copolymer decreases.

Further, when a polymer deactivated during the polymerization is mixed into a desired acrylic block copolymer, the inherent properties (impact resistance, mechanical properties, thermoplastic elastomer characteristics) of the acrylic block copolymer are obtained. In this regard, it is also desirable from this point that the acrylic block copolymer can be produced while controlling the desired structure and molecular weight by suppressing deactivation during the polymerization.

It is an object of the present invention to use at least two syndiotactic polymer blocks derived from alkyl methacrylate and at least one block derived from alkyl acrylate using an organic rare earth metal compound as a polymerization initiator. In the method for producing an acrylic block copolymer having a plurality of atactic polymer blocks, the acrylic block copolymer is produced in a high yield and in a relatively short time while controlling the desired structure and molecular weight. Is to provide a possible way.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, when producing an acrylic block copolymer using an organic rare earth metal compound as a polymerization initiator, By performing the polymerization of the alkyl acrylate at a specific temperature, deactivation during the polymerization is suppressed, and as a result, the acrylic block copolymer is produced in good yield and in a relatively short time, and Since the chemical structure can be controlled and the molecular weight distribution is narrow depending on the charging conditions of the starting monomers, it has been found that the obtained acrylic block copolymer has excellent reproducibility.

According to the present invention, an object of the present invention is to provide a method for polymerizing an alkyl methacrylate and an alkyl acrylate by using an organic rare earth metal compound as a polymerization initiator. In producing an acrylic block copolymer having at least two syndiotactic polymer blocks derived from an alkyl ester and at least one atactic polymer block derived from the alkyl acrylate, the acrylic It is achieved by providing a method for producing an acrylic block copolymer, wherein the polymerization of the acid alkyl ester is carried out at a temperature in the range of -100 ° C to -5 ° C.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The organic rare earth metal compound used in the present invention is not limited, but is represented by, for example, the following general formula (I) or (II).

[0010]

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[0011]

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[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ ,
R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each represent a hydrogen atom, a monovalent hydrocarbon group having 1 to 5 carbon atoms or a carbon atom having 1 carbon atom;
Represents an alkylsilyl group of -5, or two adjacent groups together represent a divalent hydrocarbon group having 1-10 carbon atoms; M represents a scandium atom, an yttrium atom or a lanthanoid atom; B represents a monovalent hydrocarbon group having 1 to 10 carbon atoms which may contain a hydrogen atom or a silicon atom; B represents an alkylene group having 1 to 3 carbon atoms or an alkylsilylene group having 1 to 3 carbon atoms; D represents a solvent molecule; m represents 0 or 1; n represents an integer in the range of 0-3. ]

The scandium atom (Sc), yttrium atom (Y) or lanthanoid atom (La, Ce, Pr, N) represented by M in the general formula (I) or (II).
d, Pm, Sm, Eu, Gd, Tb, Dy, Ho, E
r, Tm, Yb or Lu), the samarium atom (Sm), the europium atom (Eu) and the ytterbium atom (Yb) belong to both divalent rare earth metal atoms and trivalent rare earth metal atoms. The atoms belong to trivalent rare earth metal atoms. When M is a divalent rare earth metal atom, m in the above general formula is 0, and when M is a trivalent rare earth metal atom, m is 1.

As typical examples of the organic rare earth metal compound represented by the general formula (I) or (II), the following compounds can be mentioned.

(1) Representative examples of organic rare earth metal compounds containing a divalent rare earth metal atom: bis (cyclopentadienyl) samarium, bis (pentamethylcyclopentadienyl) samarium, dimethylsilylenebis [2,4- Bis (trimethylsilyl) cyclopentadienyl] samarium, dimethylsilylenebis (2-trimethylsilyl-
4-t-butylcyclopentadienyl) samarium, bis (pentamethylcyclopentadienyl) europium, bis (cyclopentadienyl) ytterbium, bis (pentamethylcyclopentadienyl) ytterbium, dimethylsilylenebis [2,4 -Bis (trimethylsilyl) cyclopentadienyl] ytterbium, dimethylsilylenebis (2-trimethylsilyl-4-t-butylcyclopentadienyl) ytterbium, etherate of the above compound, tetrahydrofuranate, and the like.

(2) Representative examples of organic rare earth metal compounds containing a trivalent rare earth metal atom: bis (pentamethylcyclopentadienyl) scandium hydride, bis (pentamethylcyclopentadienyl) scandium methyl,
Bis (cyclopentadienyl) yttrium hydride, bis (cyclopentadienyl) yttriummethyl, bis (cyclopentadienyl) yttriumbis (trimethylsilyl) methyl, bis (pentamethylcyclopentadienyl) yttrium hydride, bis (pentamethyl Cyclopentadienyl) yttrium methyl, bis (pentamethylcyclopentadienyl) yttrium bis (trimethylsilyl) methyl, bis (cyclopentadienyl) lanthanum hydride, bis (cyclopentadienyl) lanthanum methyl, bis (cyclopentadienyl) ) Lanthanum bis (trimethylsilyl) methyl, bis (pentamethylcyclopentadienyl) lanthanum hydride, bis (pentamethylcyclopentadienyl) lanthanum methyl, (Pentamethylcyclopentadienyl) lanthanum bis (trimethylsilyl) methyl, bis (pentamethylcyclopentadienyl) cerium methyl, bis (pentamethylcyclopentadienyl)
Neodymium methyl, bis (cyclopentadienyl) samarium hydride, bis (cyclopentadienyl) samarium methyl, bis (cyclopentadienyl) samarium bis (trimethylsilyl) methyl, bis (pentamethylcyclopentadienyl) samarium hydride,
Bis (pentamethylcyclopentadienyl) samarium methyl, bis (pentamethylcyclopentadienyl) samarium ethyl, bis (pentamethylcyclopentadienyl) samarium butyl, bis (pentamethylcyclopentadienyl) samarium bis (trimethylsilyl) Methyl, bis [1,3-bis (trimethylsilyl) cyclopentadienyl] samarium methyl, bis (1,3-di-t-butylcyclopentadienyl) samarium methyl, dimethylsilylenebis [2,4-bis (trimethylsilyl) ) Cyclopentadienyl] samariummethyl, dimethylsilylenebis (2-trimethylsilyl-4-t-
Butylcyclopentadienyl) samarium methyl, bis (cyclopentadienyl) europium hydride,
Bis (cyclopentadienyl) europium methyl, bis (cyclopentadienyl) europium bis (trimethylsilyl) methyl, bis (pentamethylcyclopentadienyl) europium hydride, bis (pentamethylcyclopentadienyl) europium methyl, bis ( Cyclopentadienyl) ytterbium hydride, bis (cyclopentadienyl) ytterbiummethyl, bis (cyclopentadienyl) ytterbiumbis (trimethylsilyl) methyl, bis (pentamethylcyclopentadienyl) ytterbium hydride, bis (pentamethylcyclopenta Dienyl) ytterbium methyl, bis (pentamethylcyclopentadienyl) ytterbium bis (trimethylsilyl) methyl, bis [1,3-bis (tri Chirushiriru) cyclopentadienyl] Ytterbium methyl, bis (1,3-di -t-
Butylcyclopentadienyl) ytterbium methyl,
Dimethylsilylenebis [2,4-bis (trimethylsilyl) cyclopentadienyl] ytterbiummethyl, dimethylsilylenebis (2-trimethylsilyl-4-t-
Butylcyclopentadienyl) ytterbium methyl,
Bis (cyclopentadienyl) lutetium hydride, bis (cyclopentadienyl) lutetium methyl,
Bis (cyclopentadienyl) lutetium bis (trimethylsilyl) methyl, bis (pentamethylcyclopentadienyl) lutetium hydride, bis (pentamethylcyclopentadienyl) lutetium methyl, bis (pentamethylcyclopentadienyl) lutetium bis ( Trimethylsilyl) methyl, bis [1,3-bis (trimethylsilyl) cyclopentadienyl] lutetiummethyl, bis (1,3-di-t-butylcyclopentadienyl) lutetiummethyl, dimethylsilylenebis [2,4
-Bis (trimethylsilyl) cyclopentadienyl] lutetium methyl, dimethylsilylenebis (2-trimethylsilyl-4-t-butylcyclopentadienyl) lutetium methyl, etherate of the above compound or tetrahydrofuranate.

Among the above-mentioned organic rare earth metal compounds, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R in the general formula (I)
An organic rare earth metal compound in which each of ⁷ , R ⁸ , R ⁹ and R ¹⁰ is a methyl group (that is, an organic rare earth metal compound having a pentamethylcyclopentadienyl group as a ligand) is preferable.

The organic rare earth metal compound is, for example,
Journal of the American Chemical Society (J. Am. Chem. Soc.) Vol. 110,
976 (1988); 107, 8103
107 (1985); pp. 8091 (19
1985); 105, 1401 (1983).
And the like, but the synthesis method is not necessarily limited. Incidentally, depending on the synthesis method, the organic rare earth metal compound,
An organic aluminum compound such as trimethylaluminum, triethylaluminum and triisobutylaluminum may be contained as an impurity. If the content is as low as about 10 times or less based on the organic rare earth metal compound, the present invention Can be carried out without hindrance.

In the present invention, examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, One or more of t-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, pentadecyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, allyl methacrylate, vinyl methacrylate and the like can be used. However, the present invention is not limited to the above examples. However, for the purpose of obtaining an acrylic block copolymer particularly excellent in heat resistance, rigidity, and the like, as alkyl methacrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and the like,
It is preferable to use an ester of methacrylic acid and an alcohol having 3 or less carbon atoms as a main component.

In the present invention, examples of the alkyl acrylate include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, and the like.
Sec-butyl acrylate, t-butyl acrylate, amyl acrylate, isoamyl acrylate, n-acrylate
One or more of -hexyl, 2-ethylhexyl acrylate, lauryl acrylate, allyl acrylate, vinyl acrylate and the like can be used, but are not limited to those described above.

According to the present invention, in the polymerization reaction using the organic rare earth metal compound as a polymerization initiator, a predetermined amount of alkyl methacrylate and alkyl acrylate are alternately added in an organic solvent under an inert gas atmosphere. It is preferable to carry out in a stepwise manner.

The amount of the organic rare earth metal compound to be used is not necessarily limited, but is preferably in the range of 1 × 10 ^-4 to 1 × 10 ^-2 mol based on the monomer used.

It is preferable that the alkyl methacrylate and the alkyl acrylate used in the polymerization are sufficiently dried in advance with a dehydrating / drying agent such as calcium hydride or molecular sieve under an inert gas stream. .

As an inert gas which is preferable as an atmosphere for the polymerization reaction, nitrogen, argon, helium and the like can be mentioned, and argon is particularly preferable.

Examples of the organic solvent include hydrocarbon solvents such as benzene, toluene and xylene; halogenated hydrocarbon solvents such as chloroform, methylene chloride and carbon tetrachloride; ether solvents such as tetrahydrofuran and diethyl ether. And the like are preferably used alone or in combination. It is preferable that the organic solvent used is previously degassed, dehydrated and purified. The amount of the organic solvent to be used is not particularly limited, but is preferably in the range of 2 to 20 times the weight of the monomer used. However, the polymerization reaction according to the present invention can be carried out in the absence of a solvent.

When an organic rare earth metal compound containing a divalent rare earth metal atom is used as a polymerization initiator, the polymerization reaction is carried out in the first step in which the alkyl acrylate is polymerized.
It comprises two or more polymerization steps including a two-stage polymerization step and a second-stage polymerization step for polymerizing alkyl methacrylate. In the first stage polymerization step, a living polymer of polyacrylic acid alkyl ester having active anion terminals at both ends of the main chain is produced, and in the subsequent second step polymerization process, polymethacrylic acid having active anion terminals at both ends of the main chain is produced. A three-block living polymer of alkyl ester-alkyl polyacrylate-alkyl methacrylate is formed. In the case of producing a block copolymer of five or more elements, if necessary, the polymerization of alkyl acrylate and the polymerization of alkyl methacrylate may be alternately performed.

When an organic rare earth metal compound containing a trivalent rare earth metal atom is used as a polymerization initiator, the polymerization reaction is performed in a first stage polymerization step for polymerizing an alkyl methacrylate, It comprises three or more polymerization steps including a second polymerization step for performing polymerization and a third polymerization step for performing polymerization of alkyl methacrylate. In the first stage polymerization step, a living polymer of polyalkyl methacrylate having an active anion terminal at one terminal of the main chain is produced, and in the second step polymerization, the active anion terminal is a fragment of a polyacrylic acid alkyl ester block. A bipolymer living polymer having a terminal polyalkyl methacrylate-alkyl polyacrylate is formed.
In the polymerization process of the step, 3 of polyalkyl methacrylate-alkyl acrylate-polyalkyl methacrylate having an active anion terminal at one terminal of one polyalkyl methacrylate block is used.
A living polymer of the original block is formed. When producing a quaternary or higher block copolymer, if desired,
Further, the polymerization of alkyl acrylate and the polymerization of alkyl methacrylate may be performed alternately.

In the polymerization reaction according to the present invention, it is important to set the polymerization temperature of the alkyl acrylate to a temperature in the range of -100 ° C to -5 ° C. The polymerization temperature is -5
If the temperature is higher than ℃, the activity of the terminal of the polyacrylic acid alkyl ester portion formed by the polymerization reaction of the alkyl acrylate is likely to be lost, and the polymerization reaction will proceed further even if the alkyl methacrylate is subsequently added. In the end, the higher the proportion of polymer molecules
This leads to a decrease in the yield of the desired acrylic block copolymer, and further to a decrease in the physical properties due to the incorporation of the by-product polymer into the desired acrylic block copolymer. These facts indicate that it is difficult to control the desired acrylic block copolymer by adjusting the monomer charging conditions. In addition, when an acrylic block copolymer containing no by-product polymer is obtained, a complicated separation process is required. On the other hand, when the polymerization temperature is lower than −100 ° C., the polymerization rate is low and the polymerization requires a long time, and thus lacks practicality.

The polymerization temperature of the alkyl acrylate is set to-in view of the fact that the above-mentioned effect of suppressing the deactivation of the terminal of the polyacrylic acid alkyl ester portion and the effect of preventing the reduction of the polymerization rate are both balanced. 95 ° C
It is preferable to set the temperature within the range of -55 ° C.

On the other hand, for the polymerization of alkyl methacrylate, the applicable polymerization temperature range is wider,
Considering both the high activity of the terminal of the polymethacrylic acid alkyl ester portion and the high polymerization rate, the temperature is preferably in the range of -100 ° C to + 50 ° C, particularly preferably -70 ° C to + 20 ° C. Temperature in the range of ° C.

As described above, the polymerization temperature of the alkyl acrylate and the polymerization temperature of the alkyl methacrylate can be set independently of each other. It will take a long time to adjust. Therefore, the polymerization of the alkyl methacrylate is carried out at a temperature in the range of -70 ° C to + 20 ° C, the polymerization of the alkyl acrylate is carried out at a lower temperature than the polymerization of the alkyl methacrylate, and the polymerization of the alkyl methacrylate is carried out. The temperature difference between the polymerization of the acrylic acid alkyl ester and
It is preferable to adopt a condition that the temperature is in the range of 0 ° C. to 80 ° C. because the reaction rate in both the polymerization of the alkyl acrylate and the polymerization of the alkyl methacrylate can be increased.

The polymerization reaction system is preferably kept under a sufficient stirring condition so that the reaction system becomes uniform. The polymerization time in each polymerization step can be appropriately selected,
If the length is too short, the proportion of unreacted monomers increases, while if it is too long, the formed living active terminal is easily deactivated, so that the conversion of the monomer becomes 90% or more and the living active terminal is not largely deactivated. It is preferable to set such time. The preferred polymerization time in each polymerization step is not necessarily uniform according to the polymerization conditions such as the polymerization temperature, but is generally selected from the range of 0.1 to 5 hours.

When the polymerization of the predetermined alkyl methacrylate and alkyl acrylate has been completed,
The polymerization can be stopped by adding a protic compound such as methanol to the reaction mixture. The amount of the protic compound to be used is not particularly limited, but is preferably in the range of 1 to 100 moles based on the organic rare earth metal compound used as the polymerization initiator. When the polymerization of the predetermined alkyl methacrylate and alkyl acrylate has been completed, lactones such as ε-caprolactone and valerolactone may be added to the reaction mixture before terminating the polymerization. In that case, the living active terminal of the acrylic block copolymer is utilized, and polymerization of the lactone further occurs there, so that a hydroxyl group is formed at the terminal.

After termination of the polymerization, the acrylic block copolymer is taken out of the reaction mixture by a reprecipitation method comprising pouring the reaction mixture into a poor solvent, a coagulation method comprising evaporating the solvent from the reaction mixture, or the like. It can be performed by any known method. According to the polymerization method according to the present invention, a desired acrylic block copolymer (that is, a multi-block copolymer having the same number of blocks as the sum of the number of additions of the methacrylate ester and the acrylate ester) is formed with high selectivity. In order to separate the target acrylic block copolymer and by-product polymer, it is not always necessary,
If desired, the polymer can be separated by a method such as a solvent fractionation method utilizing a difference in solubility of the polymer in a solvent.

Further, if a rare earth metal component derived from the organic rare earth metal compound used as the polymerization initiator remains in the acrylic block copolymer taken out of the reaction mixture, a molded article produced therefrom is an acrylic block copolymer. Since the original properties of the copolymer may not be fully exhibited, if necessary, the reaction mixture after termination of the polymerization may be
The rare earth metal component may be removed by performing an optional treatment such as washing with an acidic aqueous solution, reprecipitation in methanol, or treatment with an ion exchange resin.

According to the method of the present invention, the desired acrylic block copolymer can be produced generally in a yield of 80% or more, and in many cases, in a yield of 90% or more. Can be. The acrylic block copolymer obtained by the method of the present invention is useful as a material for various molded articles.

[0037]

EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to the following examples.

[Example 1] (1) Polymerization of methyl methacrylate 500 ml of toluene obtained by drying with sodium and then distilling under an argon atmosphere in a 1,000-ml flask purged with argon, and trivalent rare earth metal an organic rare earth metal compound containing atoms bis (pentamethylcyclopentadienyl) samarium methyl tetrahydrofuranyl inert complexes _{[(C 5 Me 5) 2 SmMe} (THF) ] 1.0
2 g (2.0 mmol) of 100 ml of dry toluene solution
Was added. To this, at 0 ° C., methyl methacrylate (MM
A) was added to 16.0 ml (150 mmol),
Stirred for 0 minutes. Withdraw 20 ml of sample from the system,
A white precipitate [polymethyl methacrylate (PMMA)] was taken out by pouring into 300 ml of methanol, and was taken out.
After drying under reduced pressure, the yield was 0.48 g (98% yield). Further, when the filtrate (methanol solution) at this time was measured by gas chromatography (hereinafter, represented by GC), only a trace amount of MMA was detected, and it was found that the conversion of MMA was 98% or more. PMMA obtained
Was measured by gel permeation chromatography (hereinafter referred to as GPC) using a solution of tetrahydrofuran (THF), and found to have a number average molecular weight (Mn) of 760.
0, molecular weight distribution (weight average molecular weight / number average molecular weight ratio; M
(w / Mn) was 1.08. Furthermore, this PMMA
Was analyzed by ¹ H-NMR to find that syndiotacticity was 83.6% by triad (rr).

(2) Polymerization of n-butyl acrylate After the polymerization of MMA, the polymerization reaction system was cooled to -78 ° C, and 66.6 ml of n-butyl acrylate (nBA) (0 .47 mol) and -7
Stirring was performed at 8 ° C. for 3 hours. A sample of 20 ml was taken out of the system, poured into 300 ml of hexane, and the deposited precipitate was taken out and dried under reduced pressure. The yield was 2.20 g.
(98% yield). Further, when the filtrate (hexane solution) at this time was measured by GC, only a trace amount of nBA was detected, and it was found that the conversion of nBA was 98% or more. The obtained precipitate was converted to a THF solution and measured by GPC. The result was a single peak, and Mn = 738.
00, Mw / Mn = 1.06. ¹ H-N
As a result of analysis by MR, it was found that the constituent units of methyl methacrylate were 19% by weight, the constituent units of n-butyl acrylate were 81% by weight, and the syndiotacticity of the PMMA block was 83.6%. did. Further, as a result of analyzing the precipitate by ¹³ C-NMR, it was found that the PnBA block portion was atactic. From the above,
It was found that a diblock copolymer of PMMA-b-PnBA was obtained.

(3) Polymerization of methyl methacrylate After the polymerization of nBA, 16.0 ml (150 mmol) of MMA was added to the polymerization system as the third monomer.
The solution was added at 78 ° C. and stirred. After the solution became homogeneous, the temperature was raised to 0 ° C., and the mixture was further stirred for 1 hour. To the resulting reaction mixture, 50 ml of methanol was added and reacted at room temperature for 2 hours to deactivate the active terminal and terminate the polymerization. A 20 ml sample was withdrawn from the resulting mixture, poured into 300 ml of hexane, the precipitate was separated by filtration, and the filtrate (hexane solution) was measured by GC. As a result, only trace amounts of MMA could be detected. Is 98%
It turned out that it was above. A sample was taken out, the remaining mixture was poured into 8 liters of hexane, and the obtained precipitate was taken out and dried under reduced pressure. The yield was 82.3 g.
(97% yield). When a part of this precipitate was measured by GPC using a THF solution, it was a single peak, with Mn = 82700 and Mw / Mn = 1.09. As a result of analysis by ¹ H-NMR, the constitutional unit of methyl methacrylate was 31% by weight, the constitutional unit of n-butyl acrylate was 69% by weight, and the syndiotacticity of the PMMA block was 83.6%. It has been found. Further, the precipitate was analyzed by ¹³ C-NMR.
The block was found to be atactic. From the above, a triblock copolymer of PMMA-b-PnBA-b-PMMA was obtained, and the composition ratio was PMM
A (16% by weight) -PnBA (69% by weight) -PMMA
(15% by weight).

Example 2 In the first polymerization step, the amount of the organic rare earth metal compound [(C ₅ Me ₅ ) ₂ SMMe (THF)] containing a trivalent rare earth metal atom was 0.45 g.
The amount of MMA to 13.3 ml and the polymerization temperature to -20 ° C.
In the second stage of the polymerization step, the amount of nBA was changed to 27.8 ml, the polymerization temperature was changed to -60 ° C, and the polymerization time was changed to 1.5 hours. The amount of MMA is 1 in the third stage polymerization step;
The same operation as in Example 1 was performed except that the polymerization temperature was changed to 3.3 ml, the polymerization temperature was changed to -20 ° C, and the polymerization time was changed to 2 hours. As a result, PMMA-b-PnBA-b-PM
45.6 g of a triblock copolymer of MA was obtained (97% yield). About the obtained ternary block copolymer, Mn was 112000, Mw / Mn was 1.07, and the composition ratio was PMMA (27% by weight) -PnBA (4
9% by weight) -PMMA (24% by weight)
The syndiotacticity of the block was 86.3%, and the PnBA block was atactic.

Example 3 In the first polymerization step, the amount of the organic rare earth metal compound [(C ₅ Me ₅ ) ₂ SMMe (THF)] containing a trivalent rare earth metal atom was 0.51 g.
, The amount of MMA to 8.0 ml, and the polymerization temperature to -60 ° C.
In the second stage of the polymerization step, the amount of BA was changed to 40.0 ml, the polymerization temperature was changed to −60 ° C., and the polymerization time was changed to 1.5 hours. In a three-stage polymerization process, the amount of MMA was increased to 10.
The same operation as in Example 1 was performed except that the polymerization temperature was changed to -60 ° C and the polymerization time was changed to 5 hours. As a result, PMMA-b-PnBA-b-PMMA
Was obtained in an amount of 48.3 g (yield 9).
7%). About the obtained triblock copolymer, M
n is 116000, Mw / Mn is 1.08, the composition ratio is PMMA (13% by weight) -PnBA (69% by weight) -PMMA (18% by weight), and the syndiotacticity of the PMMA block is 91. 0.5% and Pn
The BA block was atactic.

Example 4 In the first polymerization step, the amount of the organic rare earth metal compound [(C ₅ Me ₅ ) ₂ SMMe (THF)] containing a trivalent rare earth metal atom was 0.62 g.
, The amount of MMA to 5.0 ml, and the polymerization temperature to -20 ° C.
In the second stage of the polymerization step, the amount of nBA was changed to 42.0 ml, the polymerization temperature was changed to -90 ° C, and the polymerization time was changed to 4.5 hours. The same operation as in Example 1 was performed except that the amount of MMA was changed to 5.0 ml, the polymerization temperature was changed to −20 ° C., and the polymerization time was changed to 2 hours in the third polymerization step. As a result, PMMA-b-PnBA-b-PM
43.0 g of MA triblock copolymer was obtained (97% yield). About the obtained ternary block copolymer, Mn was 82000 and Mw / Mn was 1.07,
The composition ratio is PMMA (9% by weight) -PnBA (80% by weight) -PMMA (11% by weight), the syndiotacticity of the PMMA block portion is 86.7%, and Pn
The BA block was atactic.

Comparative Example 1 In the first polymerization step, the amount of the organic rare earth metal compound [(C ₅ Me ₅ ) ₂ SMMe (THF)] containing a trivalent rare earth metal atom was 1.50 g.
(3.0 mmol) and the polymerization time of MMA was changed to 10 minutes, respectively.
Was changed to 44.0 ml (309 mmol), the polymerization temperature was changed to 0 ° C., and the polymerization time was changed to 10 minutes; except that in the third polymerization step, the polymerization time of MMA was changed to 20 minutes. The same operation as in Example 1 was performed. As a result, 24.2 g (yield 35%) of a triblock copolymer of PMMA-b-PnBA-b-PMMA
44.1 g of a diblock copolymer of -b-PnBA
(63% yield) was obtained. About the obtained ternary block copolymer, Mn was 42500 and Mw / Mn was 1.1.
9, and the composition ratio is PMMA (12% by weight) -PnB
A (32% by weight) -PMMA (56% by weight).
Further, regarding the obtained biblock copolymer, Mn
Was 24500, Mw / Mn was 1.18, and the composition ratio was PMMA (27% by weight) -PnBA (73% by weight).

Comparative Example 2 In the first polymerization step, the amount of the organic rare earth metal compound [(C ₅ Me ₅ ) ₂ SMMe (THF)] containing a trivalent rare earth metal atom was 0.74 g.
(1.5 mmol) and the polymerization time of MMA was changed to 20 minutes, respectively.
Comparative Example 1 was changed except that the amount of MMA was changed to 11.0 ml and the polymerization time was changed to 1 hour in the third polymerization step, respectively. The same operation as described above was performed. As a result, P
78.1 g of a triblock copolymer of MMA-b-PnBA-b-PMMA was obtained (69% yield). About the obtained ternary block copolymer, Mn was 11500.
0, Mw / Mn is 1.18, and the composition ratio is PMMA
(8% by weight) -PnBA (78% by weight) -PMMA (1
4% by weight).

Comparative Example 3 In the first stage polymerization step, the amount of the organic rare earth metal compound [(C ₅ Me ₅ ) ₂ SMMe (THF)] containing a trivalent rare earth metal atom was 1.26 g.
(2.48 mmol), the amount of MMA was 10.0 ml (9
4 mmol), a polymerization temperature of -40 ° C, and a polymerization time of 6
Time respectively; in the second stage polymerization step,
changing the amount of nBA to 30 ml (211 mmol), the polymerization temperature to -110 ° C and the polymerization time to 7 hours;
In the third polymerization step, the amount of MMA was reduced to 10 ml.
(94 mmol), except that the polymerization temperature was changed to −40 ° C. and the polymerization time was changed to 6 hours, respectively. (The time required for the polymerization operation was a total of 19 hours.) ). As a result, PMMA-b-PnBA-bP
42.0 g of a triblock copolymer of MMA was obtained (97% yield). About the obtained ternary block copolymer, Mn was 33000, Mw / Mn was 1.12, and the composition ratio was PMMA (20% by weight) -PnBA (5%).
8% by weight) -PMMA (22% by weight).

Example 5 (1) Polymerization of n-butyl acrylate 500 ml of toluene obtained by drying with sodium and then distilling under an argon atmosphere was placed in a flask having an inner volume of 1000 ml replaced with argon, and divalent Bis (pentamethylcyclopentadienyl) samarium bistetrahydrofuranate complex [(C ₅ Me ₅ ) ₂ Sm (THF) ₂ ] which is an organic rare earth metal compound containing a rare earth metal 0.52 g
(0.9 mmol) of 100 ml of a dry toluene solution was added. To this, at −78 ° C., 33.0 ml of nBA (23
2 mmol), and the mixture was stirred at -78 ° C for 3 hours. A 20 ml sample was withdrawn from the system, and methanol 300 m
The resulting precipitate (PnBA) was taken out and dried under reduced pressure to give 0.92 g (yield 9).
8%). Further, when the filtrate (methanol solution) at this time was measured by GC, only a trace amount of nBA was detected, and it was found that the conversion of nBA was 98% or more. The obtained PnBA was measured by GPC using a THF solution, and Mn was 92400 and Mw / Mn was 1.
09. Further, when this PnBA was analyzed by ¹ H-NMR and ¹³ C-NMR, it was atactic.

(2) Polymerization of methyl methacrylate After the above-mentioned polymerization of nBA, 13.5 ml (127 mmol) of MMA was added to the polymerization system as a second monomer.
The solution was added at 78 ° C. and stirred. After the solution became homogeneous, the temperature was raised to −20 ° C., and the mixture was further stirred for 3 hours. The active terminal was inactivated by adding 50 ml of methanol to the obtained reaction mixture to terminate the polymerization. A 20 ml sample was withdrawn from the obtained mixture, and hexane 3
The mixture was poured into 00 ml, the precipitate was separated by filtration, and the filtrate (hexane solution) was measured by GC. As a result, only traces of MMA could be detected, and it was found that the conversion of MMA was 98% or more. The total amount of the remaining mixed solution extracted from the sample was poured into 8 liters of hexane, and the resulting precipitate was taken out and dried under reduced pressure. The yield was 38 g (yield 92%).
When a part of this precipitate was measured by GPC using a THF solution, it was a single peak, Mn = 123,000,
Mw / Mn = 1.12. Further analysis by ¹ H-NMR and ¹³ C-NMR revealed that the structural unit of MMA was 2
9% by weight, the constituent unit of nBA is 71% by weight, and PM
The syndiotacticity of the MA block was found to be 85.6%. From the above, PMMA-b-
It was found that a triblock copolymer of PnBA-b-PMMA was obtained.

[0049]

As is apparent from the above examples, according to the production method of the present invention, a structure in which a high syndiotactic polymethacrylic acid ester block is bonded to both ends of a polyacrylic acid ester block is formed in the molecule. The acrylic block copolymer having at least one part can be produced in a good yield and in a relatively short time while controlling the desired structure and molecular weight.

Claims (5)

[Claims] 1. The method according to claim 1, wherein the polymerization of the alkyl methacrylate and the polymerization of the alkyl acrylate are carried out alternately using an organic rare earth metal compound as a polymerization initiator, so that at least two of the methacrylic acid alkyl esters are derived. In producing an acrylic block copolymer having a syndiotactic polymer block and at least one atactic polymer block derived from the alkyl acrylate, the polymerization of the alkyl acrylate is carried out at -100 ° C. A process for producing an acrylic block copolymer, which is carried out at a temperature in the range of -5 ° C. 2. The polymerization of an alkyl acrylate is carried out by
The method according to claim 1, wherein the method is performed at a temperature in a range of 95 ° C. to −55 ° C. 3. A first stage polymerization step in which an organic rare earth metal compound containing a divalent rare earth metal atom is used as a polymerization initiator, and a polymerization step of polymerizing an alkyl acrylate and a polymerization step of polymerizing an alkyl methacrylate. 3. The production method according to claim 1, comprising two or more polymerization steps including two polymerization steps. 4. A first stage polymerization step in which an organic rare earth metal compound containing a trivalent rare earth metal atom is used as a polymerization initiator and polymerization of an alkyl methacrylate is carried out.
3. The production method according to claim 1, comprising three or more polymerization steps including a second polymerization step for polymerizing the alkyl acrylate and a third polymerization step for polymerizing the alkyl methacrylate. 5. The polymerization of the alkyl methacrylate at a temperature in the range of -70 ° C. to + 20 ° C., the polymerization of the alkyl acrylate at a lower temperature than the polymerization of the alkyl methacrylate, and the polymerization of the alkyl methacrylate. The method according to any one of claims 1 to 4, wherein a temperature difference between the polymerization of the ester and the polymerization of the alkyl acrylate is in the range of 20C to 80C.