JPH09249705A - Anionic polymerization catalyst composition and polymerization method using said composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an anionic polymn. catalyst compsn. which permits the anionic polymn. of a styrene monomer in a high-concn. and high-temp. system to proceed in the manner of living polymerization under controlled polymn. temp. conditions to prepare a highly monodisperse polymer by using a mixture of an alkyllithium compd. with a specified heterocyclic nitrogen-contg. compd. SOLUTION: This compsn. comprises an alkyllithium compd. and at least one nitrogen-contg. heterocyclic org. in an amt. of 0.05 to 30mol per mol of the alkyllithium compd. In this compsn., the amt. of the nitrogen-contg. heterocyclic org. compd. is pref. 0.1 to 10mol per mol of the alkyllithium compd. Pref. examples of the alkyllithium compd. include n-butyllithium, sec-butyllithium, and tert-butyllithium. Pref. examples of the nitrogen-contg. heterocyclic org. compd. include alkylpyridine, pyridine, and pyrimidine.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention uses an alkyllithium compound and a specific nitrogen-based heterocyclic organic compound as a catalyst when polymerizing a styrene monomer in an aromatic hydrocarbon or alicyclic hydrocarbon solvent. The present invention relates to a catalyst composition for anionic polymerization and a method for anionic polymerization using the catalyst composition. More specifically, compared with the conventional anionic polymerization method, even though the monomer concentration is higher and the polymerization reaction in a high temperature system, the polymerization proceeds in a living manner without causing a transfer reaction or a termination reaction during the polymerization, and thus the molecular weight distribution The present invention relates to a novel anionic polymerization catalyst composition capable of easily producing a narrow styrene polymer or a terminally reactive styrene polymer, and an anionic polymerization method using the composition.

[0002]

2. Description of the Related Art Styrene-based polymers represented by polystyrene have been industrially produced by a radical polymerization method for a long time, but the radical polymerization of styrene is well known in the art by the recombination reaction of growing radicals of styrene. Since the termination reaction or the transfer reaction to the solvent or monomer occurs, not only the molecular weight distribution becomes broad, but also the terminal structure of the polymer cannot be regulated, and the radical polymerization method makes it easy to obtain a monodisperse polymer, block polymer, or star polymer. It was difficult to obtain shaped polymers.

As a method for solving this, there is a living anion polymerization method of styrene. For example, anionic polymerization of styrene using butyllithium which is a general-purpose initiator is a so-called polymerization system without transfer reaction and termination reaction. A wide variety of polymers have been obtained by forming a living polymerization system and obtaining extremely monodisperse polymers, and by utilizing the reactivity of the growing terminal.

In this styrene living anionic polymerization method, generally, the counter cation at the growing end is often an alkali metal type, the monomer concentration is as low as several 10%, and the polymerization reaction temperature is room temperature. It is often restricted to the vicinity. This is because the initiator concentration in living polymerization is much higher than that in radical polymerization (basically, the initiator concentration = polymer chain concentration), so if the polymerization reaction is carried out at a high concentration or at a high temperature, the polymerization reaction will This is because it becomes extremely fast and a rapid heat of polymerization is generated in the initial stage of polymerization. When heat removal control becomes impossible due to the sudden generation of heat of polymerization, the temperature of the polymerization system rises rapidly, which facilitates the transfer reaction and termination reaction of the polymer growing terminal, thus obtaining an ideal living polymerization system. I will not be able to.

For example, when anionically polymerizing styrene at a monomer concentration of about 20% in a cyclohexane solvent near room temperature of about 30 ° C., polystyrene having a weight average molecular weight of about 100,000 to 300,000 is prepared by using n-BuLi, which is the most general-purpose, as a catalyst. In the case of synthesizing, the polymerization reaction rate is extremely fast, and the conversion time is several seconds to several minutes, and a conversion close to 100% can be obtained. It is difficult to remove the heat of polymerization because the polymerization reaction proceeds almost adiabatically and becomes a runaway reaction. When attempting to industrially carry out the production of polystyrene by anionic polymerization,
Under the above-mentioned polymerization conditions, as compared with the case of producing by bulk polymerization process of radical polymerization polystyrene, the reactor volume becomes large due to the use of a large amount of solvent, and a step of recovering the polymer from a large amount of solvent is required, which is required for production. It's terrible and it's rarely practiced.

[0006] The living anionic polymerization method of styrene is capable of obtaining various polymers having a controlled structure which cannot be obtained by the radical polymerization method. Except for the above examples, it has not been industrially produced so far.Because the polymerization system is a solution system as described above, it cannot be a sufficiently satisfactory polymer considering the productivity and economic efficiency of the polymer. This is because the.

One of the methods for suppressing a rapid reaction in the case of performing living anion polymerization of a styrene-based monomer at a high concentration is to carry out the polymerization at a lowered temperature. However, since most styrene resins have a glass transition temperature of 100 ° C. or higher, polymerization proceeds at high concentration and low temperature, but the polymerization system is cured during the polymerization process and recovery from the reactor is difficult. It will be difficult. Further, a large-scale refrigerating equipment is required, and the economical efficiency becomes a problem. Therefore, it is a necessary condition to allow living polymerization to proceed in a high-concentration and high-temperature system, but in the prior art, no polymerization system was able to sufficiently satisfy the condition.

As a prior art for delaying anionic polymerization, the effect of adding pyridine during the polymerization of styrene by means of a di-Na complex catalyst of α-methylstyrene tetramer in tetrahydrofuran (hereinafter abbreviated as THF) is known (J. Po.
lym. Sci (Polymerchemistry
Edition) vol14, 1097 to 1105 (1
976) YAGI, TSUYAMA), but the polymerization method is 2
In the vicinity of room temperature around 0 ° C, the monomer concentration is 10% ~
It was carried out in a polar solvent of THF under the condition of 30% at most and using only Na metal catalyst as a catalyst metal species.

Therefore, in the above prior art, since the Na metal compound is the anionic polymerization catalyst species and the sodium alkyl is difficult to dissolve in the hydrocarbon solvent, the anionic polymerization of the styrenic monomer can be carried out in the hydrocarbon solvent. First, it is a serious drawback in industrializing this technology. Also, since the monomer concentration is low, a large amount of solvent must be removed in order to recover the polymerized polymer, which is costly and economically disadvantageous.

[0010]

DISCLOSURE OF THE INVENTION The present invention makes anionic polymerization of a styrene monomer in a high concentration, high temperature system, which cannot be achieved by conventional techniques, proceed in a living manner under the control of polymerization temperature, and is extremely effective. An object of the present invention is to provide a catalyst composition for producing a monodisperse polymer and a novel industrial production method of a styrene-based polymer using the catalyst composition.

[0011]

Means for Solving the Problems As a result of intensive studies on the technical problems, the present inventors have found that anionic polymerization of a styrene-based monomer represented by styrene is carried out with an alkyllithium compound and a specific heterocyclic nitrogen-based compound. When using a mixture of compounds as a catalyst and polymerizing in an aromatic hydrocarbon or alicyclic hydrocarbon, which is almost apolar solvent compared to THF, it is surprisingly high monomer which is hardly considered in conventional anionic polymerization. Despite the concentration and high temperature polymerization, the polymerization reaction does not cause a runaway reaction, the polymerization rate does not extremely slow down, and the polymerization proceeds at a reaction rate that allows sufficient heat removal control, and in a living manner. It was found that the polymerization proceeds, and the present invention was completed based on this finding.

That is, the present invention comprises (1): an alkyllithium compound and 0.
A catalyst composition for anionic polymerization, characterized by using one or two or more nitrogen-based heterocyclic organic compounds in an amount of 05 to 30 times, (2): a nitrogen-based heterocycle per 1 mol of the alkyllithium compound. The anionic polymerization catalyst composition according to (1), wherein the formula organic compound is 0.1 to 10 moles, and (3): the alkyllithium compound is n-butyllithium, sec-butyllithium, tert-. One or more of butyllithium, iso-propyllithium, n-propyllithium, benzyllithium, phenyllithium, and hexyllithium (1) or (2).
Anionic polymerization catalyst composition described,

(4) The catalyst composition for anionic polymerization according to (1) or (2), wherein the nitrogen-based heterocyclic organic compound is alkylpyridine, pyridine, pyrimidine, quinoline, pyridaline, benzimidazole, (5): (1) A method for anionic polymerization, characterized by polymerizing a styrenic monomer using the catalyst composition for anionic polymerization described in (6):
An anionic polymerization method according to (5), characterized in that an aromatic hydrocarbon compound or an alicyclic hydrocarbon compound is used as a polymerization solvent in polymerizing the styrene-based monomer.
(7): When polymerizing the styrene-based monomer, the polymerization temperature is 30 to 150 ° C., and the styrene-based monomer concentration is 40 to 100.
The anionic polymerization method according to (5) is characterized in that the content is wt%.

The present invention will be described in detail below. The styrene-based monomer used in the present invention is not particularly limited as long as it is a styrene-based monomer that is generally known and capable of living anionic polymerization in view of its polymerization principle.
Among them, α-alkyl-substituted styrene, nuclear alkyl-substituted styrene, and the like are listed as the preferable monomers in addition to the most typical styrene. Specific examples include α-methylstyrene, α-methyl-p-methylstyrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, p.
-Ethylstyrene, 2,4-dimethylstyrene, 2,5
-Dimethyl styrene, p-isopropyl styrene, 2,
4,6-trimethyl styrene etc. are mentioned. These styrenic monomers may be used alone or for the purpose of obtaining a copolymer.
You may use it in combination more than a kind.

The polymerization temperature is 30 ° C. or higher, preferably 50 ° C.
The above is good. The lower limit temperature of the polymerization temperature must have a rate at which the polymerization is completed at least within a target polymerization time. The polymerization proceeds even at 30 ° C. or lower, but in the polymerization system of the present invention, the polymerization proceeds extremely slowly, and therefore it is judged to be unfavorable from the viewpoint of industrial production. The upper limit of the polymerization temperature is not particularly limited, but if the polymerization system is in a high temperature state for a long time, side reactions such as transfer reaction and termination reaction occur and it becomes difficult to obtain a monodisperse polymer. Further, unreacted monomers undergo radical polymerization due to heat, resulting in a mixture with a polydisperse polymer. In all of these abnormal reactions, the polymerization temperature cannot be unconditionally specified in relation to the polymerization temperature and the polymerization time, but it is preferably 150 ° C. or lower in the polymerization system of the present invention.

The concentration of the styrenic monomer is 40 wt% or more and 100 wt% or less. It is preferably 50 wt% or more and 100 wt% or less. Considering the recovery of the solvent, the higher the concentration, the better, but considering the increase in the viscosity of the polymerization system,
Some amount of solvent is required. However, if the concentration becomes too low, the polymerization reaction will not only be slowed down, but also the transfer reaction to the solvent will easily occur at high temperature. Therefore, considering the living polymerizability, the concentration is preferably at least 40 wt%. In the present invention, the case where the polymerization is carried out with 100% styrene-based monomer without using the polymerization solvent is also included in the scope of the invention. In this case, it is possible to prevent the polymerization system from solidifying by controlling the conversion of the styrene monomer during the polymerization reaction.

To describe the technical breakthrough point of the present invention again, the present invention suppresses the polymerization rate of the styrene-based monomer at a high concentration and at a high temperature so that it can be heat-removed in a process-wise manner, and it is known for industrial production. It has been found from the above that a catalyst composition having an appropriate polymerization rate and in which the polymerization proceeds in a living manner regardless of a high temperature. The catalyst composition is that an alkyllithium compound and a specific nitrogen-based heterocyclic organic compound are used as an anionic polymerization catalyst.

Specific examples of the alkyl lithium compound include methyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium, t-butyl lithium, iso-propyl lithium, n-propyl lithium, benzyl lithium, phenyl lithium, hexyl lithium and the like. And more preferably n-butyllithium,
sec-butyl lithium, t-butyl lithium, iso
-Propyl lithium, n-propyl lithium, and phenyl lithium are preferable. One or two of these compounds
Combinations of more than one type may be used.

The amount of the alkyllithium compound to be added can be arbitrarily set according to the target molecular weight of the polymer. That is, Mn (number average molecular weight) = [M] _o / [I] ×
{Molecular weight of monomer} ([M] _o is the charged concentration of the monomer,
[I] may be added to the polymerization system at a concentration of an alkyllithium compound calculated by (concentration of alkyllithium compound).

The solvent used during the polymerization is an aromatic hydrocarbon or an alicyclic hydrocarbon. The case of the present invention includes the case where the styrene monomer is 100% and no solvent is used. As a preferable solvent, an aromatic hydrocarbon compound or an alicyclic hydrocarbon compound having a relatively low polarity which is less likely to cause a transfer reaction or a termination reaction is preferable, and specifically, ethylbenzene, toluene, xylene, isopropylbenzene, benzene, cyclohexane and the like. There is.

The specific nitrogen-based heterocyclic organic compound added to the alkyllithium compound is a derivative compound group of pyridine, which is an aromatic organic compound group having an alkylpyridine compound or a pyridine ring in the molecule. Specific examples include pyridine, alkyl pyridine (a compound in which one or two hydrogen atoms in a pyridine aromatic ring are substituted with an alkyl group such as a methyl group, an ethyl group or a propyl group), pyrimidine, quinoline,
Examples include pyridalin and benzimidazole.

The amount of the nitrogen-based heterocyclic organic compound added is in the range of 0.05 to 30 times by mole, preferably 0.1 to 10 times by mole, relative to 1 mole of the alkyllithium compound. This is because if the amount of the nitrogen-based heterocyclic organic compound to be added is 0.05 times mol or less with respect to 1 mol of the lithium compound, the polymerization rate retarding effect is not sufficient, and if it is 30 times or more, the retarding effect is saturated. .

The larger the amount of nitrogen-based heterocyclic organic compound added to the alkyllithium compound, the slower the polymerization rate of the styrene-based monomer. The addition amount of the alkyllithium compound is determined so that the desired molecular weight is obtained, and further the addition amount of the nitrogen-based heterocyclic organic compound is determined so that the desired polymerization rate is obtained with respect to the addition amount of the alkyllithium compound. The mixture of the alkyllithium compound and the nitrogen-based heterocyclic organic compound has good solubility in the aromatic hydrocarbon or alicyclic hydrocarbon. When the solubility of the above mixture is not sufficient, it is easily dissolved by heating.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail with reference to Examples and Comparative Examples. The monomers, solvents and catalysts used in Examples and Comparative Examples were purified by the following method before use. (1) Styrene (SM): Asahi Chemical Industry Co., Ltd., Ca
Styrene was distilled under reduced pressure once under H ₂ , degassed, and then filled in dry nitrogen. (2) Ethylbenzene (EB): manufactured by Wako Pure Chemical Industries, Ltd., a special grade reagent was distilled under reduced pressure once under CaH _{2 and} after degassing, a molecular sieve was put and sealed under dry nitrogen.

(3) n-Butyl lithium (BuLi):
Kanto Chemical Co., Ltd., 1.6M n-hexane solution. (4) Pyridine and alkyl pyridine: Kanto Chemical Co., Inc.
Reagent grade CaH ₂ distilled under and sealed under dry nitrogen was placed dehydrated after the molecular sieve. (5) Other heterocyclic nitrogen compounds: manufactured by Wako Pure Chemical Industries,
Crystals of special grade remedy were used directly. Room temperature liquid compound is C
It was dehydrated with aH ₂ .

The method of evaluating the polymerization rate and the living property was as follows. (6) Measurement of polymerization rate: Unreacted styrene was measured by gas chromatography (GC), and the polymerization rate (Conv.) Was determined by the following formula. Conv. (%) = ([Charged SM concentration]-[unreacted S
M concentration]) / [charged SM concentration] × 100 GC measurement conditions Measuring instrument: Shimadzu GC14B column: PEG20M (φ3 mm × 3 m) carrier gas: nitrogen, flow rate 50 ml / min Detector: FID column temperature: 120 ° C. to 220 10 ℃ / min up to ℃
Temperature rise at

(7) Measurement of number average molecular weight (Mn), weight average molecular weight (Mw) and Mw / Mn: Measured using gel permeation chromatography (GPC). GPC measurement conditions Measuring instrument: Tosoh HLC-8020 (built-in differential refractive index detector) Column: Using two Tosoh TSKgel-GMH _XL Temperature: 38 ° C Solvent: Tetrahydrofuran (THF) Sample concentration: 0.1 wt / v % Sampling pitch: 1 / 0.4 (times / second) Molecular weight calculation: A calibration curve was created by using the relationship between the molecular weight of Tosoh TSK standard polystyrene and the elution time as a cubic regression curve,
Calculated.

[0028]

EXAMPLES Unless otherwise specified, all operations in the following Examples and Comparative Examples were carried out under dry nitrogen in a sufficiently dry glass container, and reagents were also collected and added with a dry syringe. The present invention is not limited to these examples.

Example 1 Sufficiently heated and dried 5 equipped with a stirrer for a stirrer
Styrene dewatered and freed of polymerization inhibitors, similarly dehydrated ethylbenzene and CaH in a 0 ml pressure bottle.
₂₎ The reagent grade pyridine after the treatment and dehydration was subjected to precision distillation and the purity was confirmed by gas chromatography, and then charged in a composition of Table 1 in a Chisso box and sealed with a crown with a nitrile rubber stopper. Remove the pressure bottle from the Chisso box and set a thermocouple to measure the reaction solution temperature, 1.6 mm
ol / l n-butyllithium 10 with ethylbenzene
The double-diluted product was used as a catalyst and was injected with the composition shown in Table 1 by using a syringe, and the mixture was stirred by a charging stirrer in an oil bath at 60 ° C. to start polymerization. The runaway reaction due to the heat of the polymerization reaction did not occur, and the temperature in the polymerization system was almost uniformly 60 ° C.

60 minutes after the catalyst was added, tetrahydrofuran (T) containing 10% of methanol (T
2 ml of the HF) solution was added to terminate the polymerization. A small amount was taken out from the solution in which the polymerization was stopped and subjected to GC analysis. Also,
The molecular weight of the polymerized polymer was measured by GPC after adding a solution to methanol, reprecipitating and purifying the polymer, and then drying. Polymerization Conv. The results of measurement of the molecular weight were as follows. Conv. = 26%, Mn = 29000, Mw = 312
00, Mw / Mn = 1.08

Example 2 In exactly the same manner as in Example 1, the reaction was stopped after a polymerization time of 2 hr. The results of the following examples and comparative examples are shown in Table 1. Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that pyridine was not used. Polymerization proceeds extremely rapidly and adiabatically, approximately 3 after catalyst implantation.
The polymerization liquid temperature reached 110 ° C. or higher in minutes. The polymerization proceeded rapidly, the viscosity of the system increased, and the system became solidified. Unless pyridine is used, the polymerization rate cannot be controlled at a monomer concentration of 50%, and the molecular weight distribution is widened due to deactivation at high temperatures.

Example 3 The amount of pyridine added was twice that of Example 1, and the polymerization time was 4 hours. As compared with Examples 1 and 2, it can be seen that the polymerization rate is delayed by increasing the addition amount of pyridine. Example 4 Polymerization was carried out by raising the monomer concentration and further raising the initial polymerization temperature to 80 ° C. Polymerization can be controlled even with such a high monomer concentration and high temperature reaction, the reaction is living and the molecular weight distribution is narrow.

Example 5 Polymerization was carried out by lowering the amount of catalyst used in Example 4. It can be seen that the molecular weight is almost doubled as compared with Example 4, and the reaction is living. Example 6 Cyclohexane was used as a polymerization solvent. Example 7 It was carried out under the conditions of complete bulk polymerization without using a solvent. Although the molecular weight distribution was slightly widened, it was polymerized in a livig-like manner to obtain a polymer having a target molecular weight.

Example 8 Polymerization was carried out by increasing the amount of pyridine added. It can be seen that the polymerization is under control. Examples 9 to 11 Polymerization was carried out using 4-methylpyridine instead of pyridine. A delay effect similar to that of pyridine was observed.

Comparative Example 2 Polymerization was carried out at a monomer concentration of about 20% using cyclohexane as a solvent under the usual anionic polymerization conditions. It can be seen that the polymerization liquid temperature rises near 20 ° C. even when cyclohexane is 80% or more, and the reaction proceeds almost adiabatically. Since the maximum temperature of the polymerization system was 58 ° C. because the monomer concentration was as low as 20%, the molecular weight distribution was 1.08, but if the monomer concentration is further increased, the molecular weight distribution will broaden. If the monomer concentration is 20%, it will be costly to remove the solvent and there will be a problem in economic efficiency in industrialization. Comparative Example 3 Polymerization was carried out at a monomer concentration of 80%. The temperature of the polymerization solution rose sharply in a short time and became high, the catalyst was deactivated, and a complete runaway reaction occurred.

[0036]

[Table 1]

[0037]

By using a mixture of the alkyllithium compound of the present invention and a specific nitrogen-based heterocyclic organic compound as an anionic polymerization catalyst for styrene monomer, it is possible to obtain a high monomer concentration and a high temperature which cannot be considered by conventional anionic polymerization. It is possible to obtain a living monodisperse polymer while controlling the polymerization temperature under the above polymerization conditions. The present invention is extremely important in converting anionic polymerization for obtaining a styrenic polymer into an industrial process.

Claims (7)

[Claims] 1. A catalyst composition for anionic polymerization, which comprises using an alkyllithium compound and one or two or more moles of a nitrogen-based heterocyclic organic compound in an amount of 0.05 to 30 moles per mole of the alkyllithium compound. Stuff. 2. The catalyst composition for anionic polymerization according to claim 1, wherein the amount of the nitrogen-based heterocyclic organic compound is 0.1 to 10 times the mole of the alkyllithium compound. 3. The alkyllithium compound is one or more of n-butyllithium, sec-butyllithium, tert-butyllithium, iso-propyllithium, n-propyllithium, benzyllithium, phenyllithium and hexyllithium. The catalyst composition for anionic polymerization according to claim 1 or 2. 4. The catalyst composition for anionic polymerization according to claim 1, wherein the nitrogen-based heterocyclic organic compound is an alkylpyridine, pyridine, pyrimidine, quinoline, pyridaline, or benzimidazole. 5. An anionic polymerization method comprising polymerizing a styrene-based monomer using the catalyst composition for anionic polymerization according to claim 1. 6. The anionic polymerization method according to claim 5, wherein an aromatic hydrocarbon compound or an alicyclic hydrocarbon compound is used as a polymerization solvent when polymerizing the styrene-based monomer. 7. When polymerizing a styrenic monomer, the polymerization temperature is 30 to 150 ° C., and the concentration of the styrenic monomer is 40 to 40.
It is 100 wt%, The anionic polymerization method of Claim 5 characterized by the above-mentioned.