JPH10265510A - Production of conjugated diene-based polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently obtain the subject polymer in which molecular weight and molecular weight distribution are controlled in a short time by subjecting a conjugated diene to anionic polymerization in the presence of an alkali metal salt or alkaline earth metal salt of an acid in an organic solvent containing an ether. SOLUTION: A conjugated diene (e.g. 1,3-butadiene) is subjected to anionic polymerization in an organic solvent (e.g. cyclohexane) containing an ether (e.g. tetrahydrofuran) in the presence of an alkali metal salt (e.g. lithium chloride or sodium sufonate) or an alkaline earth metal (e.g. magnesium chloride) of an acid at -100-25 deg.C by using a usual polymerization initiator (e.g. n-butyl lithium) to provide the objective polymer. Since anionic polymerization of the conjugated diene is carried out at a high reaction rate even in low temperature conditions, production of the conjugated diene-based polymer containing a process of anion polymerization can efficiently be carried out in a short time as at least a part of polymerization process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a conjugated diene-based polymer such as a conjugated diene homopolymer, a copolymer of a conjugated diene and another monomer (for example, a block copolymer containing a conjugated diene polymer block). The present invention relates to a method for producing a polymer.

[0002]

2. Description of the Related Art Conventionally, when an anionic polymerization of a conjugated diene is carried out in an organic solvent containing an ether (for example, tetrahydrofuran), the conjugated diene is anionically polymerized in another organic solvent (for example, a hydrocarbon-only solvent such as cyclohexane). It is known that a conjugated diene-based polymer having a microstructure different from that obtained by the above method can be obtained.
For example, when butadiene is used as the conjugated diene, a polybutadiene containing more 1,2-bonds is obtained, and when isoprene is used, 1,2- and 3,4-bonds are more contained. Polyisoprene is obtained.

[0003] In recent years, with the demand for higher functionality and higher performance of polymer materials, it has become increasingly important to produce a polymer having a freely controlled molecular weight and molecular weight distribution with good reproducibility. In order to produce a conjugated diene-based polymer controlled in this manner by anionic polymerization in a solvent containing an ether as described above, it is necessary to react the polymerization living terminal with an oxygen atom contained in the ether molecule. It is known that polymerization at high temperatures must be avoided to suppress unwanted side reactions. However, when the temperature condition of the anionic polymerization of the conjugated diene is not set to a high temperature, the polymerization rate becomes extremely low, so that a long-time polymerization is required.

As described above, an industrially advantageous method for efficiently producing a conjugated diene polymer having a controlled molecular weight, molecular weight distribution, etc. in a short time by anionic polymerization of a conjugated diene in a solvent containing ether. Has not been found yet.

[0005]

The first object of the present invention is to produce a conjugated diene-based polymer having a controlled molecular weight and molecular weight distribution by anionic polymerization of a conjugated diene in a solvent containing ether. Another object of the present invention is to provide an industrially advantageous method that can efficiently produce the polymer in a short time.

A second object of the present invention is to provide a block copolymer comprising a step of forming a conjugated diene polymer block having a controlled molecular weight and molecular weight distribution by anionic polymerization of a conjugated diene in a solvent containing ether. It is an object of the present invention to provide an industrially advantageous method for producing a block copolymer in a short time and efficiently in a method for producing a polymer.

[0007]

According to the present invention, the first object is to carry out anionic polymerization of a conjugated diene in an organic solvent containing an ether. This is achieved by providing a method for producing a conjugated diene-based polymer, characterized in that an alkaline earth metal salt is present.

According to the present invention, a second object of the present invention is to provide a method for producing a block copolymer comprising a step of anionically polymerizing a conjugated diene in an organic solvent containing an ether. In some cases, this is achieved by providing a method for producing a block copolymer, characterized in that an alkali metal salt or an alkaline earth metal salt of an acid is present in a polymerization reaction system.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The conjugated diene (monomer) that can be used in the method of the present invention is not particularly limited as long as it is capable of anionic polymerization.
-Butadiene, isoprene, 1,3-pentadiene,
2,3-dimethyl-1,3-butadiene and the like. These monomers can be used alone or in combination of two or more.

Further, by polymerizing another monomer capable of anionic polymerization simultaneously with or at a different time from the polymerization of the conjugated diene, a random, tapered or block containing a conjugated diene unit and the other monomer unit can be used. It is also possible to obtain polymers. Examples of such other monomers include styrene, α-methylstyrene, methyl (meth) acrylate, t-butyl (meth) acrylate, and the like (in the present specification, “(meth) acrylate” is acrylate And methacrylate). However, when a random or tapered copolymer is produced according to the method of the present invention, it is desirable to set the proportion of the conjugated diene to 60 mol% or more of all monomers from the viewpoint that the effect of improving the polymerization rate becomes more remarkable. .

In the present invention, the conjugated diene is polymerized in an organic solvent containing ether. Such organic solvents include a solvent consisting of ether alone and a mixed solvent of ether and another organic solvent. Examples of the ether include cyclic ethers such as tetrahydrofuran, tetrahydropyran, 2-methyltetrahydrofuran, and dioxane; and non-cyclic ethers such as 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl ether, diethyl ether, and methyl ethyl ether. Ethers. These ethers are used alone or in combination of two or more. The other organic solvent that can be used as a mixture with ether may be any solvent used for ordinary anionic polymerization, such as hexane,
Hydrocarbon solvents such as cyclohexane and benzene are exemplified. The proportion of the ether in the organic solvent containing the ether depends on the bonding mode of the desired conjugated diene (for example, 1,
Ratio of 2-bond and 3,4-bond), the type of monomer used, etc., but it is necessary to increase the ratio of 1,2-bond and 3,4-bond of the conjugated diene. If so, it is desirable to select from the range of 0.1 to 100% by weight in the organic solvent.

The amount of the organic solvent containing ether is such that the concentration of the added monomer is 30% by weight or less with respect to the organic solvent, the effect of improving the polymerization rate becomes more remarkable. Desirable.

In the present invention, an alkali metal salt or alkaline earth acid of an acid is added to an anionic polymerization reaction system of a monomer containing a conjugated diene (alone of the conjugated diene or a mixture with another monomer) in an organic solvent containing an ether. The metal salt is present. As the alkali metal salt or alkaline earth metal salt of the acid, an alkali metal salt or an alkaline earth metal salt of a mineral acid or an organic acid is preferable.
Halides of alkali metals such as lithium fluoride, lithium chloride and lithium bromide; sulfates of alkali metals such as potassium sulfate; nitrates of alkali metals such as potassium nitrate;
Alkali metal borates such as sodium borate; alkali metal sulphonates such as sodium sulfonate; alkaline earth metal halides such as magnesium chloride; alkaline earth metal nitrates such as barium nitrate; . Among these, it is particularly preferable to use a halide of the same kind of metal as the metal which is the counter cation at the terminal of the anionic polymerization. The above salts may be used alone or
A combination of more than one type is used.

The amount of the alkali metal salt or alkaline earth metal salt of the above-mentioned acid is not particularly limited.
It is preferably 0.001 to 10% by weight, more preferably 0.001 to 5% by weight, based on the organic solvent containing ether.

The anionic polymerization reaction of a monomer containing a conjugated diene according to the present invention in an organic solvent containing an ether is carried out in the same manner as described above except that an alkali metal salt or an alkaline earth metal salt of an acid is present in the polymerization reaction system. And conditions and operations according to known anionic polymerization using an organic solvent.

In the anionic polymerization reaction according to the present invention, the polymerization initiator can be appropriately selected from polymerization initiators that can be used in ordinary anionic polymerization. Examples of monofunctional anionic polymerization initiators include alkali metals such as sodium metal and lithium metal; and monovalent saturated aliphatic aliphatic acids as organic groups such as methyllithium, ethyllithium, n-butyllithium and s-butyllithium. Organic monoalkali metal compounds having a hydrocarbon group can be exemplified. Examples of the bifunctional anionic polymerization initiator include organic dialkali metal compounds having a divalent saturated aliphatic hydrocarbon group as an organic group, such as 1,4-dilithiobutane and 1,4-disodiobtan; Organic dialkali metal compounds having a divalent aromatic hydrocarbon group as an organic group, such as naphthalene, may be mentioned. The amount of the polymerization initiator used can be appropriately set in consideration of a desired molecular weight and the like, and is usually selected so as to be within a range of 0.000001 to 0.002 mol per gram of the monomer used. You.

The polymerization temperature in the anionic polymerization reaction of the monomer containing a conjugated diene according to the present invention in an organic solvent containing an ether may be appropriately adjusted according to the type of the polymerization initiator, the monomer, and the organic solvent used. It may be selected and adopted, and it is not necessarily limited, but usually it can be selected from the range of -100 ° C to 100 ° C. However, in that the polymerization reaction accelerating effect derived from the addition of an alkali metal salt or alkaline earth metal salt of an acid is more remarkably exhibited, and in that the average molecular weight and the molecular weight distribution in the obtained polymer are easily controlled,
It is preferable to select from the range of -100 ° C to 25 ° C.

The anionic polymerization reaction is preferably carried out in an inert gas atmosphere such as a nitrogen gas atmosphere. The polymerization time is not particularly limited, and may be a time until the conversion of the monomer reaches a desired value,
With regard to the polymerization of monomers containing conjugated dienes according to the invention in organic solvents containing ethers, generally from 3 to
Within 72 hours.

When a block copolymer having a polymer block of a monomer containing a conjugated diene having a controlled molecular weight or the like is produced according to the method of the present invention, a polymer of the monomer containing a controlled conjugated diene is used. In the step of anionic polymerization in an organic solvent containing an ether for forming a block, it is necessary to allow an alkali metal salt or an alkaline earth metal salt of an acid to be present in the polymerization reaction system. The presence of the salt is not necessary in the polymerization step to form However, usually, the salt does not adversely affect the anionic polymerization of monomers other than the conjugated diene, so that even in the production of a block copolymer, the salt is present in the reaction system throughout all polymerization steps. No problem. However, an embodiment in which the method for producing a block copolymer according to the present invention adds the salt after the polymerization step of the monomer other than the conjugated diene, and shifts to the anion polymerization step of the monomer containing the conjugated diene, in the presence of the salt Needless to say, an embodiment in which the salt is removed after the anionic polymerization step of a monomer containing a conjugated diene and the process proceeds to a polymerization step of another monomer is included.

In the method of the present invention, after completion of a predetermined polymerization reaction, the polymerization can be terminated according to a known method employed for stopping anionic polymerization. The method for terminating the polymerization is not necessarily limited, but methanol, ethanol, 1-propanol, 2-
Generally, a compound containing an active hydrogen atom, such as an alcohol such as propanol, is added to the reaction system.

In the method of the present invention, after the termination of the polymerization reaction, the conjugated diene polymer can be separated and obtained according to a usual method. Regarding the separation and acquisition method of the polymer, it is not necessarily uniform depending on the polymer to be produced.
After removing the alkali metal salt or alkaline earth metal salt of the acid from the solution containing the conjugated diene-based polymer, the conjugated diene-based polymer is obtained by performing dehydration drying and pelletizing with a twin-screw extruder. can do. The removal of the alkali metal salt or alkaline earth metal salt of the acid after termination of the polymerization can be performed, for example, by replacing the organic solvent containing ether with a water-insoluble organic solvent in the solution after the completion of the polymerization reaction. This can be carried out by obtaining a solution of the coalescing in the water-insoluble organic solvent, and then washing the water-insoluble organic solvent solution with water. Further, by performing reprecipitation treatment using a polar organic solvent that is a poor solvent for the target polymer and can dissolve the alkali metal salt or the alkaline earth metal salt, the solution after the completion of the polymerization reaction is obtained. Thus, a polymer from which an alkali metal salt or an alkaline earth metal salt has been removed can also be obtained.

[0022]

The present invention will be specifically described below with reference to examples.
Note that the present invention is not limited by these examples.

Example 1 (Synthesis of polyisoprene) 0.25 g of lithium chloride was introduced into a reactor previously dried under a nitrogen atmosphere. The reaction vessel containing lithium chloride was heated at 180 ° C. for 3 hours, and further degassed under vacuum to completely remove water. Thereafter, the reaction vessel was returned to room temperature while the inside was again placed under a nitrogen stream, and 50 ml of dried tetrahydrofuran was introduced into the reaction vessel. After lithium chloride is completely dissolved in tetrahydrofuran, the solution is cooled to -40 ° C, and a cyclohexane solution containing 1.3 mol / liter of s-butyllithium is added.
05 ml (s-butyllithium content: 0.065 mmol) were added. 6 ml of isoprene monomer was added to the obtained tetrahydrofuran solution, and the solution was stirred at −40 ° C. under a nitrogen stream to carry out a polymerization reaction of isoprene. 24 hours after the start of the polymerization reaction,
The reaction was stopped by adding 0.1 ml of methanol to the reaction mixture. A reprecipitation operation was performed by adding the obtained mixture to 500 ml of stirred methanol, and as a precipitate, 4 g of polyisoprene from which low-boiling substances (tetrahydrofuran, cyclohexane and methanol) and lithium chloride had been removed (yield). %: 98%).

The obtained polyisoprene was analyzed by gel permeation chromatography (GPC), and the following values were obtained.

Mn = 87900 Mw = 98000 Mw / Mn = 1.1

Here, Mn means number average molecular weight (calibration curve made with polystyrene), Mw means weight average molecular weight (calibration curve made with polystyrene), and Mw / Mn
Means the molecular weight distribution.

The obtained polyisoprene was analyzed by NMR. As a result, the bonding mode of isoprene was 40 mol% of 1,2-bond, 55 mol% of 3,4-bond and 55 mol% of 1,4-bond. It turned out to be 5 mol%.

Comparative Example 1 (Synthesis of Polyisoprene without Addition of Lithium Chloride) 50 ml of dried tetrahydrofuran was introduced into a reaction vessel previously dried under a nitrogen atmosphere. After cooling to −40 ° C., 0.05 ml of a cyclohexane solution containing s-butyllithium at a concentration of 1.3 mol / liter (s-butyllithium content: 0.065 mmol) was added. Isoprene monomer 6 is added to the obtained tetrahydrofuran solution.
Then, the resulting solution was stirred at −40 ° C. under a nitrogen stream to carry out a polymerization reaction of isoprene. 24 hours after the start of the polymerization reaction, the reaction was stopped by adding 0.1 ml of methanol to the reaction mixture. The obtained mixture was subjected to reprecipitation treatment in the same manner as in Example 1 to obtain 1.6 g of polyisoprene (yield: 39).
%)Obtained.

As a result of analyzing the obtained polyisoprene by GPC, the following values were obtained.

Mn = 35100 Mw = 39700 Mw / Mn = 1.1

As a result of NMR analysis of the obtained polyisoprene, the bonding mode of isoprene was 40 mol% of 1,2-bond, 55 mol% of 3,4-bond and 55 mol% of 1,4-bond. It turned out to be 5 mol%.

Example 2 (Synthesis of styrene-isoprene block copolymer) 0.25 g of lithium chloride was introduced into a reactor previously dried under a nitrogen atmosphere. The reaction vessel containing lithium chloride was heated at 180 ° C. for 3 hours, and further degassed under vacuum to completely remove water. Thereafter, the reaction vessel was returned to room temperature while the inside was again placed under a nitrogen stream, and 50 ml of dried tetrahydrofuran was introduced into the reaction vessel. After lithium chloride is completely dissolved in tetrahydrofuran, the solution is cooled to -78 ° C and a cyclohexane solution containing s-butyllithium at a concentration of 1.3 mol / liter is added.
05 ml (s-butyllithium content: 0.065 mmol) were added. 0.7 ml of a styrene monomer was added to the obtained tetrahydrofuran solution, and the solution was stirred for 1 hour at −78 ° C. under a nitrogen stream to carry out a styrene polymerization reaction. Next, 6 ml of isoprene monomer was added to the obtained reaction mixture, and the solution was stirred at −40 ° C. under a nitrogen stream to carry out a polymerization reaction of isoprene. 24 hours after the start of the isoprene polymerization reaction, 0.1 ml of methanol was added to the reaction mixture.
The reaction was stopped by adding. A reprecipitation operation was carried out by adding the obtained mixture to 500 ml of stirred methanol, and as a precipitate, a styrene-isoprene block copolymer from which low-boiling substances (tetrahydrofuran, cyclohexane and methanol) and lithium chloride had been removed. 4.7 g (yield: 99%) of the combined product was obtained.

The obtained block copolymer was subjected to GP
Analysis by C gave the following values.

Mn = 99500 Mw = 113000 Mw / Mn = 1.1

Example 3 (Synthesis of isoprene-methyl methacrylate block copolymer) In the same manner as in Example 1, a polymerization reaction of 6 ml of isoprene monomer was carried out at -40 ° C for 24 hours. Next, instead of adding methanol, 1,1-diphenylethylene 0.1.
018 g (0.1 mmol) was added thereto under a nitrogen stream.
The reaction was performed at 40 ° C. for 1 hour. Thereafter, the reaction vessel was placed at -78.
℃, methyl methacrylate monomer 0.7m
After the addition of l, the solution was stirred at the same temperature under a nitrogen stream to carry out a polymerization reaction of methyl methacrylate. One hour after the initiation of the polymerization reaction of methyl methacrylate, the reaction was stopped by adding 0.1 ml of methanol to the reaction mixture. A reprecipitation operation was performed by adding the obtained mixture to 500 ml of methanol with stirring, and as a precipitate, a low-boiling substance (tetrahydrofuran, cyclohexane and methanol) and an isoprene-methyl methacrylate block from which lithium chloride had been removed were used. 4.7 g (yield: 99%) of a polymer was obtained.

The obtained block copolymer was subjected to GP
Analysis by C gave the following values.

Mn = 99300 Mw = 116000 Mw / Mn = 1.2

Example 4 (Synthesis of styrene-isoprene-styrene block copolymer) In the same manner as in Example 2, a polymerization reaction of 0.7 ml of a styrene monomer was carried out at -78 ° C for 1 hour, and then at -40 ° C. A polymerization reaction of 6 ml of the monomer was performed for 24 hours. Next, instead of adding methanol, the reaction vessel was cooled to −78 ° C., and 0.7 ml of styrene monomer was added. Then, the solution was stirred at the same temperature under a nitrogen stream to perform a styrene polymerization reaction. Was. One hour after the start of the polymerization reaction of styrene, methanol was added to the reaction mixture.
The reaction was stopped by adding 1 ml. A reprecipitation operation was performed by adding the obtained mixture to 500 ml of methanol with stirring, and as a precipitate, a styrene-isoprene-styrene block from which low-boiling substances (tetrahydrofuran, cyclohexane and methanol) and lithium chloride had been removed. 5.3 g of the copolymer (yield: 9
9%).

The obtained block copolymer was subjected to GP
Analysis by C gave the following values.

Mn = 109200 Mw = 114700 Mw / Mn = 1.1

Example 5 (Synthesis of styrene-isoprene-methyl methacrylate block copolymer) In the same manner as in Example 2, a polymerization reaction of 0.7 ml of styrene monomer was carried out at -78 ° C for 1 hour, and then at -40 ° C. A polymerization reaction of 6 ml of isoprene monomer was performed for 24 hours. Next, instead of adding methanol, 0.018 g (0.1 mmol) of 1,1-diphenylethylene was added, and the mixture was reacted at −40 ° C. for 1 hour under a nitrogen stream. Thereafter, the reaction vessel was cooled to −78 ° C., and 0.7 ml of methyl methacrylate monomer was added. Then, the solution was stirred at the same temperature under a nitrogen stream to carry out a polymerization reaction of methyl methacrylate. One hour after the initiation of the polymerization reaction of methyl methacrylate, methanol 0.1 was added to the reaction mixture.
The reaction was stopped by adding 1 ml. A reprecipitation operation was carried out by adding the obtained mixture to 500 ml of methanol with stirring, and as a precipitate, styrene-isoprene-methyl methacrylate from which low-boiling substances (tetrahydrofuran, cyclohexane and methanol) and lithium chloride had been removed. 5.3 block copolymer
g (yield: 99%).

For the obtained block copolymer, GP
Analysis by C gave the following values.

Mn = 109000 Mw = 128600 Mw / Mn = 1.2

[0044]

According to the present invention, anionic polymerization of a conjugated diene in a solvent containing ether can be carried out at a high reaction rate even under low temperature conditions. The production of the conjugated diene polymer including the anionic polymerization step can be efficiently performed in a reduced time. Therefore, the present invention provides an industrially advantageous method for producing a conjugated diene-based polymer in which the average molecular weight, molecular weight distribution, conjugated diene bonding mode, and the like are controlled.

Claims (4)

[Claims] 1. A conjugated diene-based polymer characterized in that an alkali metal salt or an alkaline earth metal salt of an acid is present in a polymerization reaction system when anionically polymerizing a conjugated diene in an organic solvent containing an ether. Manufacturing method. 2. The method according to claim 1, wherein the conjugated diene is anionically polymerized at a temperature in the range of -100 ° C. to 25 ° C. 3. A method for producing a block copolymer comprising a step of anionically polymerizing a conjugated diene in an organic solvent containing an ether, wherein at least at the time of anionic polymerization of the conjugated diene, an alkali metal of an acid is contained in a polymerization reaction system. A method for producing a block copolymer, wherein a salt or an alkaline earth metal salt is present. 4. The method according to claim 3, wherein the conjugated diene is anionically polymerized at a temperature in the range of -100 ° C. to 25 ° C.