JP2011122046A - Method for producing polymer by anionic polymerization - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a polymer having a desired molecular weight while suppressing side reaction in the anionic polymerization of a compound having an anionically polymerizable unsaturated bond. <P>SOLUTION: The method for producing a polymer by anionic polymerization of a polymerizable monomer in an aprotic polar solvent in the presence of a polymerization initiator includes a step (A) of adding to an aprotic polar solvent solution having a polymer anion therein an organic alkali metal which is non-reactive with the polymer anion, a step (B) of deactivating the polymerization initiation ability of the polymerizable monomer which the organic alkali metal has, and a step (C) of adding a polymerizable monomer the same as or different from the polymerizable monomer in the step (A) to the aprotic polar solvent solution having a polymer anion therein to extend the polymer chain. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a polymer by an anionic polymerization method, and more particularly to a method for stably obtaining a homopolymer or copolymer having a desired molecular weight in an anionic polymerization method.

  In the anionic polymerization method, in order to produce a polymer having a controlled molecular weight, the molecular weight of the polymer is measured in the middle of adding the monomer, and the amount of the added monomer is accurately calculated. A method is known in which a polymer having a desired molecular weight is obtained by further adding a corresponding amount of monomer and polymerizing. For example, Patent Document 1 discloses a method for producing a monodisperse polymer having a target molecular weight in anionic polymerization, in which monomer addition is performed a plurality of times while sampling and measuring the molecular weight of the produced polymer. A method for controlling the molecular weight by carrying out the steps separately is disclosed.

US Pat. No. 6,218,485

However, when the method according to Patent Document 1 is applied to a case where a compound having an anionically polymerizable unsaturated bond is polymerized in an aprotic polar solvent such as tetrahydrofuran, a problem occurs. Since the stability of the anion active species in the solvent is poor, the anion active species is likely to be deactivated, and the molecular weight is measured at an intermediate stage using the method for controlling the molecular weight described above under such reaction conditions. During the process, some anion active species are deactivated. As a result, a polymer having a molecular weight at the time when the molecular weight is measured is included in the final polymer.
It is considered that this problem can be solved by improving the stability of the anion active species in the reaction system. In the anionic polymerization method, it is known that when a low polarity solvent such as toluene or hexane is mixed with a polar solvent such as tetrahydrofuran, the stability of the anion active species is improved. As the proportion of the low polarity solvent increases, the stability of the anion active species can be improved, but on the other hand, there is a disadvantage that the polymerization rate is slow. When a polymerization reaction is performed under such reaction conditions, a long time is required to complete the polymerization reaction. Therefore, oxygen contained in a minute amount in the reaction system or air entering the system during the polymerization reaction Side reactions between trace amounts of oxygen and the like and anion active species are likely to occur. As a result, there may be a problem that a polymer having about twice the target molecular weight is contained in the final product.
In addition, the solvent, monomer, etc. used are strictly purified and used, the reactor is completely sealed, and oxygen, moisture, etc. in the air enter the system when measuring the molecular weight in the middle stage. It is considered that the problem can be solved by completely preventing this. However, if too strict reaction conditions are required, it cannot be adopted as an industrial production method.
An object of the present invention is to provide a method for producing a polymer having a desired molecular weight while suppressing side reactions in the case of anionic polymerization of a compound having an anionic polymerizable unsaturated bond using an aprotic polar solvent. It is in.

  The present inventors have conducted intensive research to solve the above problems. As a result, when anionic polymerization of a compound having an anionic polymerizable unsaturated bond in an aprotic polar solvent, an organic alkali such as alkyl lithium that does not react with the polymer anion is present in the reaction system in which the polymer anion exists. It has been found that by adding a metal, the polymerization inhibitor can be quickly trapped and the stability of the polymer anion in the reaction system can be significantly improved. Measure the molecular weight while suppressing the side reaction without deactivating or deactivating the polymer anion in the middle of the polymerization reaction by improving the stability of the polymer anion in the reaction system It became possible to do. Furthermore, after a certain period of time, such as molecular weight measurement, after passing through the step of deactivating the polymerization initiation ability of the organic alkali metal, the necessary amount of anionic polymerizable monomer should be added again. Thus, it was found that anionic polymerization can proceed again. As a result, a simple method for producing a polymer having a desired molecular weight and few impurities due to side reactions has been completed.

That is, the present invention
(1) In a method for producing a polymer by anionic polymerization of a polymerizable monomer in the presence of a polymerization initiator in an aprotic polar solvent,
(A) adding an organic alkali metal that does not react with the polymer anion to the aprotic polar solvent solution containing the polymer anion;
(B) adding a compound that reacts with the organic alkali metal to inactivate the polymerization initiation ability of the polymerizable monomer of the organic alkali metal; and
(C) A step of extending a polymer chain by adding the same or different polymerizable monomer as the polymerizable monomer in step (A) to an aprotic polar solvent solution containing a polymer anion is included. A method for producing a polymer characterized by
(2) The production of the polymer as described in (1) above, wherein the organic alkali metal that does not react with the polymer anion is the same compound as the polymerization initiator used for producing the polymer anion. How,
(3) The method for producing a polymer according to (1) or (2) above, wherein the organic alkali metal that does not react with the polymer anion is alkyl lithium,
(4) The method for producing a polymer according to any one of (1) to (3) above, wherein the polymerizable monomer is a styrene monomer or a conjugated diene monomer,
(5) The method for producing a polymer according to any one of (1) to (4) above, wherein the aprotic polar solvent is an ether solvent,
(6) The method for producing a polymer according to the above (5), wherein the ether solvent is tetrahydrofuran,
(7) The compound that reacts with the organic alkali metal and inactivates the polymerization initiation ability of the polymerizable monomer of the organic alkali metal is selected from the group consisting of an organic magnesium compound, an organic zinc compound, and an organic aluminum compound. The method for producing a polymer according to any one of (1) to (6) above, which is at least one selected
(8) The method for producing a polymer as described in any one of (1) to (7) above, wherein the steps (A) to (C) are repeated a plurality of times.

  By using the production method of the present invention, even if an anion polymerizable monomer or solvent containing a trace amount of a polymerization inhibitor is used, the polymerization inhibitor may be mixed in a trace amount from outside the reaction system. However, the polymerization by anionic polymerization was stabilized, and it became possible to synthesize polymers without side reactions. Since the obtained polymer is well controlled in molecular weight and molecular weight distribution, it is useful as a material such as a resist material and additives for various polymers.

The GPC curve figure of the sample A obtained in Example 1 is shown. The GPC curve figure of the sample B obtained in Example 1 is shown. The GPC curve figure of the sample C obtained in Example 1 is shown.

Hereinafter, the present invention will be described in more detail.
The method for producing the polymer of the present invention comprises:
Step (A): An organic alkali metal that does not react with the polymer anion is added to an aprotic polar solvent solution containing a polymer anion obtained by anionic polymerization of a polymerizable monomer in the presence of a polymerization initiator. Adding step,
Step (B): adding a compound that reacts with the organic alkali metal and inactivates the polymerization initiation ability of the polymerizable monomer that the organic alkali metal has, and
Step (C): A step of extending a polymer chain by adding a polymerizable monomer that is the same as or different from the polymerizable monomer in Step (A) to an aprotic polar solvent solution containing a polymer anion. including.

[Process (A)]
In the step (A), it is necessary that substantially no polymerizable monomer remains when the organic alkali metal is added.

The polymerizable monomer is not particularly limited as long as it is a compound having an anionic polymerizable unsaturated bond, and specific examples include styrene monomers and conjugated diene monomers. .
Specific examples of the styrenic monomer include styrene, α-alkylstyrene such as α-methylstyrene, nucleus-substituted styrene (styrene having a substituent on an aromatic ring), and the like. The nucleus substituent is preferably an anionic species having a polymerization initiating ability or an inert group with respect to an anionic species having no initiating ability. Specifically, an alkyl group (preferably a C1 such as a methyl group or an ethyl group). -C6 alkyl group), alkoxyalkyl group (preferably C1-C6 alkoxy C1-C6 alkyl group such as methoxymethyl group, ethoxyethyl group), alkoxy group (preferably C1-C6 alkoxy such as methoxy group, ethoxy group, etc.) Group), an alkoxyalkoxy group (preferably a C1-C6 alkoxy C1-C6 alkoxy group such as a methoxymethoxy group, an ethoxyethoxy group), an alkoxycarbonyl group (preferably a t-butoxycarbonyl group, a t-butoxycarbonylmethyl group, etc.) C1-C6 alkoxycarbonyl group), a heterocyclic group (preferably, teto It can be exemplified Hidoropiraniru group). Specific examples of the nucleus-substituted styrene include α-methyl-p-methylstyrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, p-ethylstyrene, pt-butylstyrene, p- (1 -Ethoxyethoxy) styrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, p-isopropylstyrene, 2,4,6-triisopropylstyrene, pt-butoxystyrene, pt-butoxy-α- Examples thereof include methylstyrene and mt-butoxystyrene. These can be used alone or in combination of two or more. Among these, styrene, styrene having an alkyl group nucleus substituted, styrene having an alkoxy group nucleus substituted, α-alkyl styrene, α-alkyl styrene having an alkyl group nucleus substituted, or α-alkyl styrene having an alkoxy group nucleus substituted. preferable.
Specific examples of the conjugated diene monomer include conjugated butadiene monomers, and more specifically 1,3-butadiene, isoprene, 2,3-dimethylbutadiene, 2-ethyl. -1,3-butadiene, 1,3-pentadiene, chloroprene and the like can be exemplified, and these can be used alone or in combination of two or more.

The polymerization initiator is not particularly limited as long as it is a nucleophile and has a function of initiating polymerization of an anionic polymerizable monomer. Specifically, alkali metal, organic alkali metal A compound etc. can be illustrated.
Examples of the alkali metal include lithium, sodium, potassium, cesium and the like.
Examples of the organic alkali metal compound include alkylated products, allylated products, and arylated products of the above alkali metals. 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 1,1-diphenylhexyllithium, 1,1-diphenyl-3-methylpentyllithium, 1,4-dilithio-2-butene, 1,6-dilithiohexane, polystyryllithium, cumylpotassium, cumylcesium, etc. it can. These anionic polymerization initiators can be used in combination of two or more.

  The aprotic polar solvent used in the present invention is not particularly limited as long as it is an aprotic polar solvent that does not participate in the polymerization reaction and is compatible with the polymer. Specifically, diethyl ether, tetrahydrofuran (THF), ether solvents such as dioxane and trioxane; tertiary amines such as tetramethylethylenediamine and hexamethylphosphoric triamide; and the like can be exemplified, and in particular, THF can be preferably exemplified. Moreover, these solvent can be used individually by 1 type or as a 2 or more types of mixed solvent. Furthermore, even if it is an aliphatic hydrocarbon compound, an aromatic hydrocarbon compound, or an alicyclic hydrocarbon compound with a low polarity, it can be used by combining with a polar solvent. Specific examples of such combinations include hexane and THF, and toluene and THF.

  The organic alkali metal that does not react with the polymer anion used in the present invention does not deactivate or deactivate the polymer anion by reacting with the polymer anion, and also deactivates the polymer anion. There is no particular limitation as long as it can react with the causative substance. Specifically, an organic alkali metal used for generating a polymer anion can be exemplified. For example, an alkyl lithium can be specifically exemplified for a polystyrene anion. The reaction with the polymer anion includes a case where the polymer anion is deactivated or converted into another substance, and the other substance includes a complex such as a metal art complex.

Examples of the organic alkali metal that does not react with the polymer anion include alkyl lithium, aryl lithium, aralkyl lithium, alkyl sodium, aryl sodium, aralkyl sodium, alkyl potassium, aryl potassium, aralkyl potassium, alkyl cesium, aryl cesium, aralkyl cesium, and the like. Alkyllithium is preferred.
Examples of the alkyl lithium include methyl lithium, ethyl lithium, n-propyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium and the like, preferably n-butyl lithium and sec-butyl lithium. is there.
The polymerization initiator used for producing the polymer anion and the organic alkali metal such as alkyl lithium that does not react with the polymer anion may be the same compound or different compounds.

  The amount of the organic alkali metal that does not react with the polymer anion used in the step (A) is not particularly limited as long as the deactivation of the polymer anion can be suppressed, but is usually 0.01 to 10 equivalents, preferably 0.3. ~ 3 equivalents. By adding the organic alkali metal in this range, the anion active species in the reaction system can be remarkably stabilized.

  After step (A), between the next step (B) or in parallel with step (B), the produced polymer is sampled to measure the molecular weight of the polymer, and the amount of monomer added Can be accurately calculated to determine the amount added. The method of the present invention can also be employed when it is necessary to pause once without measuring the molecular weight.

[Process (B)]
In the step (B), as a compound (hereinafter sometimes abbreviated as compound (B)) for inactivating the polymerization initiation ability of the polymerizable monomer possessed by the organic alkali metal, the compound (B) itself, or It is necessary that the compound obtained by reacting or interacting with the compound (B) and the organic alkali metal has an ability to supplement a substance that inhibits polymerization of a monomer added later.

Examples of the compound (B) include organic magnesium, organic zinc, and organic aluminum, and dialkyl magnesium, trialkyl aluminum, and dialkyl zinc are preferable, and di-lower alkyl magnesium, tri-lower alkyl aluminum, and di-lower alkyl zinc are more preferable.
The above lower alkyl means a C1-8 alkyl group.
Specific examples of the di-lower alkyl magnesium include di-n-butyl magnesium, di-t-butyl magnesium, di-s-butyl magnesium, n-butyl-s-butyl magnesium, n-butyl-ethyl magnesium, and n-butyl. -N-octylmagnesium and the like can be exemplified, and di-n-butylmagnesium can be particularly preferably exemplified.
Specific examples of the di-lower alkylaluminum include trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-hexylaluminum, and tri-n-octylaluminum. can do.
Specific examples of the di-lower alkyl zinc include dimethyl zinc, diethyl zinc, di-n-propyl zinc, diisopropyl zinc, di-n-butyl zinc, diisobutyl zinc, di-n-hexyl zinc and the like. Particularly preferred is diethyl zinc.
The compound (B) can be appropriately selected depending on the type of organic alkali metal added in the step (A) and the type of monomer added in the step (C). For example, the compound (B) is added in the step (A). When the organic alkali metal to be used is an alkyl lithium compound and the monomer added in step (C) is styrene, di-lower alkyl magnesium or di-lower alkyl zinc is preferred, and di-n-butyl magnesium or diethyl zinc is preferred. More preferred.
The amount of the compound (B) used can be arbitrarily selected within a range not affecting the polymerization. Specifically, it is preferable that 1 mol equivalent or more and 20 mol equivalent or less of compound (B) is used with respect to 1 mol of the organic alkali metal that does not react with the polymer anion added in the step (A). When the amount is smaller than 1 mol, the monomer polymerized in the second stage cannot react with the remaining organic anion to react with the organic alkali metal, so that a single polymer cannot be obtained. Therefore, it becomes impossible to produce a polymer having a controlled molecular weight and molecular weight distribution stably and with good reproducibility. If it is greater than 20 molar equivalents, the growth rate may be significantly reduced in the polymerization reaction.

[Process (C)]
The monomer added in the step (C) is not particularly limited as long as it is a compound having an anionic polymerizable unsaturated bond having reactivity with the polymer anion obtained in the step (A). Specifically, the above-mentioned styrene monomer, conjugated diene monomer and the like can be preferably exemplified, and these can be used alone or in combination of two or more. The monomer added in the step (C) and the compound having an anionic polymerizable unsaturated bond used in producing the polymer anion may be the same compound or different compounds. Good.
Therefore, the production method of the present invention can also be applied to the production of a homopolymer or a copolymer.
Although the density | concentration with respect to the polymerization solvent of the monomer used in a process (C) is not restrict | limited in particular, Usually, it is the range of 1-40 weight%, and the range of 2-15 weight% is especially preferable.
The polymerization temperature in the step (C) is not particularly limited as long as it is a temperature range in which side reactions such as transfer reaction and termination reaction do not occur and the monomer is consumed and the polymerization is completed. It is preferable to carry out in a temperature range of not more than ° C.

  After the step (C), the molecular weight can be controlled more accurately by repeating the steps (A) to (C) a plurality of times while measuring the molecular weight each time.

[Others]
In the present invention, if necessary, an additive can be added at the start of polymerization or during polymerization. Specific examples of such additives include mineral salts and halides such as sodium, potassium, barium, and magnesium sulfates, nitrates, and borates. Examples include barium chloride, bromide, iodide, lithium borate, magnesium nitrate, sodium chloride, potassium chloride, and the like. Among these, lithium halides such as lithium chloride, lithium bromide, iodine Preference is given to using lithium fluoride or lithium fluoride, in particular lithium chloride.
Moreover, the alkali metal salt of thiol can be added as an additive. Such an additive is not particularly limited as long as it is soluble in a polymerization solvent, and examples of the alkali metal in the alkali metal salt of thiol include lithium, sodium, potassium and the like, and lithium is preferable. . Examples of thiols in the alkali metal salt of thiol include aliphatic thiols and aromatic thiols, aromatic thiols are preferred, and nitrogen aromatic thiols are more preferred.
Specifically, C1-C18 alkyl thiol such as ethane thiol, propane thiol, benzyl mercaptan, 2-mercaptoethyl ether and cyclohexyl thiol, cycloalkyl thiol, thiol containing a hydroxyl group such as mercaptoethanol and p-mercaptophenol, Thiols containing carboxylic acid esters such as methyl mercaptoacetate and ethyl mercaptopropionate, aromatic thiols such as benzenethiol, toluenethiol and naphthalenethiol, 2-mercapto-1-methylimidazole, mercaptopyridine, mercaptothiazoline, mercaptobenzthiazoline And nitrogen-containing aromatic thiols such as mercaptobenzoxazole and mercaptopyrimidine. Two or more alkali metal salts of thiol can be used in combination.
EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, the technical scope of this invention is not limited to these illustrations.

N-Butyllithium (1.80 g, 4.00 mmol (n-hexane solution 1.60 mol / L) in 2-mercaptothiazoline (0.1200 g, 1.01 mmol) and tetrahydrofuran (300 g) under nitrogen atmosphere at room temperature ) And stirred for 30 minutes. Then, it cooled to -50 degreeC and the n-butyllithium solution (1.22 g, 3.00 mmol (n-hexane solution 1.60 mol / L)) was added. A solution obtained by adding pt-butoxystyrene (15.85 g, 90 mmol) to tetrahydrofuran (7.5 g) was added dropwise for 7 minutes, and the mixture was stirred for 10 minutes after completion of the addition. A part of the solution in the reaction system was sampled and used as sample A. Then, n-butyllithium (0.92 g, 2.00 mmol (n-hexane solution 1.60 mol / L)) was added and stirred for 1 hour.
Thereafter, a dibutyl magnesium hexane solution (1.68 g, 2 mmol) was added, and a part of the solution in the reaction system was sampled to obtain a sample B. A solution of pt-butoxystyrene (47.54 g, 270 mmol) added to tetrahydrofuran (22.5 g) was added dropwise for 15 minutes, stirred for 15 minutes, and then killed with methanol (2.74 g). A part of the solution was sampled as sample C.
When samples A, B, and C were analyzed by gas chromatography, no pt-butoxystyrene was observed in any of samples A, B, and C.
When samples A, B, and C were measured by GPC, samples A and B produced a polymer having a molecular weight (Mn) of 6400 and a dispersity of 1.21. In sample C, a polymer having a molecular weight (Mn) of 18500 and a dispersity of 1.08 was produced. Sample C did not contain a polymer having a molecular weight (Mn) of 6400, and did not contain a polymer having a molecular weight approximately twice the molecular weight (Mn = 18500).

Claims (8)

In a method for producing a polymer by anionic polymerization of a polymerizable monomer in the presence of a polymerization initiator in an aprotic polar solvent,
(A) adding an organic alkali metal that does not react with the polymer anion to the aprotic polar solvent solution containing the polymer anion;
(B) adding a compound that reacts with the organic alkali metal to inactivate the polymerization initiation ability of the polymerizable monomer of the organic alkali metal; and
(C) A step of extending a polymer chain by adding the same or different polymerizable monomer as the polymerizable monomer in step (A) to an aprotic polar solvent solution containing a polymer anion is included. A method for producing a polymer characterized by the above. The method for producing a polymer according to claim 1, wherein the organic alkali metal that does not react with the polymer anion is the same compound as the polymerization initiator used to produce the polymer anion. The method for producing a polymer according to claim 1 or 2, wherein the organic alkali metal that does not react with the polymer anion is alkyl lithium. The method for producing a polymer according to any one of claims 1 to 3, wherein the polymerizable monomer is a styrene monomer or a conjugated diene monomer. The method for producing a polymer according to any one of claims 1 to 4, wherein the aprotic polar solvent is an ether solvent. The method for producing a polymer according to claim 5, wherein the ether solvent is tetrahydrofuran. The compound that reacts with the organic alkali metal and inactivates the polymerization initiation ability of the polymerizable monomer of the organic alkali metal is at least selected from the group consisting of an organic magnesium compound, an organic zinc compound, and an organic aluminum compound It is 1 type, The manufacturing method of the polymer in any one of Claims 1-6 characterized by the above-mentioned. Process (A)-(C) is repeated in multiple times, The manufacturing method of the polymer in any one of Claims 1-7 characterized by the above-mentioned.

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